Patent Publication Number: US-6989131-B2

Title: Catalytic reactor with integral evaporator

Description:
FIELD OF THE INVENTION 
     The present invention relates to one or more reactors that each include an integral evaporator for vaporizing a liquid feed within the reactor, followed by a reaction zone for reacting the resulting vapor in the presence of a catalyst. Particularly the present invention relates to the use of multiple reactors with an integral evaporators in a combinatorial catalytic array. 
     BACKGROUND OF THE INVENTION 
     Before a catalyst is selected for use in a commercial application, for example hydrocarbon reactions in petroleum refining, a great number of catalysts may be examined for use in the envisioned application. A large number of newly synthesized catalytic compositions may be considered as candidates. It then becomes important to evaluate each of the potential catalysts to determine the formulations that are the most successful in catalyzing the reaction of interest under a given set of reaction conditions. 
     Two key characteristics of a catalyst that are determinative of its success are the activity of that catalyst and the selectivity of the catalyst. The term activity refers to the rate of conversion of reactants by a given amount of catalyst under specified conditions, and the term selectivity refers to the degree to which a given catalyst favors one reaction compared with another possible reaction, see,  McGraw - Hill Concise Encyclopedia of Science and Technology , Parker, S. B., Ed. in Chief; McGraw-Hill: New York, 1984; p. 8. 
     The traditional approach to evaluating the activity and selectivity of new catalysts is a sequential one. When using a micro-reactor or pilot plant, each catalyst is independently tested at a set of specified conditions. Upon completion of the test at each of the set of specified conditions, the current catalyst is removed from the micro-reactor or pilot plant and the next catalyst is loaded. The testing is repeated on the freshly loaded catalyst. The process is repeated sequentially for each of the catalyst formulations. Overall, the process of testing all new catalyst formulations is a lengthy process at best. 
     Combinatorial chemistry deals mainly with the synthesis of new compounds. For example, U.S. Pat. No. 5,612,002 B1 and U.S. Pat. No. 5,766,556 B1 teach an apparatus and a method for simultaneous synthesis of multiple compounds. Akporiaye, D. E.; Dahl, I. M.; Karlsson, A.; Wendelbo, R.  Angew Chem. Int. Ed.  1998, 37, 9-611 disclose a combinatorial approach to the hydrothermal synthesis of zeolites, see also WO 98/36826. 
     Combinatorial methods present the possibility of substantially increasing the efficiency of catalyst evaluation. Recently, efforts have been made to use combinatorial methods to increase the efficiency and decrease the time necessary for thorough catalyst testing. For example, WO 97/32208-A1 teaches placing different catalysts in a multi-cell holder with the heat absorbed or liberated in each cell being measured to determine the extent of each reaction. Thermal imaging has also been used; see Holzwarth, A.; Schmodt, H.; Maier, W. F.  Angew. Chem. Int. Ed.,  1998, 37, -47, and Bein, T.  Angew. Chem. Int. Ed.,  1999, 3—3. Measuring the heat absorption or liberation and thermal imaging may provide semi-quantitative data regarding activity of the catalyst in question, but they provide no information about selectivity. 
     Some attempts to acquire information as to the reaction products in rapid-throughput catalyst testing are described in Senkan, S. M.  Nature , July 1998, 4(23), 3-353, where laser-induced resonance-enhanced multiphoton ionization is used to analyze a gas flow from each of the fixed catalyst sites. Similarly, Cong, P.; Doolen, R. D.; Fan, Q.; Giaquinta, D. M.; Guan, S.; McFarland, E. W.; Poojary, D. M.; Self, K.; Turner, H. W.; Weinberg, W. H.  Angew Chem. Int. Ed.  1999, 4-8 teach using a probe with concentric tubing for gas delivery/removal and sampling. Only the fixed bed of catalyst being tested is exposed to the reactant stream, with the excess reactants being removed via vacuum. The single fixed bed of catalyst being tested is heated and the gas mixture directly above the catalyst is sampled and sent to a mass spectrometer. 
     Attempts have been made to apply combinatorial chemistry to evaluate the activity of catalysts. Some applications have focused on determining the relative activity of catalysts in a library; see Klien, J.; Lehmann, C. W.; Schmidt, H.; Maier, W. F.  Angew Chem. Int. Ed.  1998, 37, 39-3372; Taylor, S. J.; Morken, J. P.  Science , April 1998, 0(10), 7-270; and WO 99/34206-A1. Some applications have broadened the information sought to include the selectivity of catalysts. WO 99/19724-A1 discloses screening for activities and selectivities of catalyst libraries having addressable test sites by contacting potential catalysts at the test sites with reactant streams forming product plumes. The product plumes are screened by passing a radiation beam of an energy level to promote photoions and photoelectrons which are detected by microelectrode collection. WO 98/07026-A1 discloses miniaturized reactors where the reaction mixture is analyzed during the reaction time using spectroscopic analysis. 
     In order to determine the activity and selectivity of multiple catalysts, arrays of reactors have been designed to simultaneously examine multiple catalysts using the above mentioned analysis techniques. For example, EP 1108467 A2 teaches reactors with removable sections to allow easy introduction of catalyst to the reactor bed. The reactors are sealed using o-rings to allow quick connection of the reactor parts and also provide a reliable seal between the reactor parts and between each reactor and its environment. 
     Many reactors available currently are designed for the situation where the feed streams are all of the same phase, for example two feed components that are both gases. Many process technologies and chemistries require higher-pressure gas-phase catalysis, in which a liquid feedstock is vaporized before contacting the catalyst. This may become challenging due to the fact that many seals used for combinatorial arrays have a temperature limitation that is below the bubble point of many reactor inlet compositional mixtures. For example, the long-term temperature limitation on a typical O-ring seal is about 170° C., while the bubble point of C 6  to C 9  hydrocarbons, for example toluene, at operating pressures of about 300 psig (2172 kPa) to about 450 psig (3220 kPa) are between about 180° C. and about 240° C. at a hydrogen to toluene molar ratio between about 1 and about 3. 
     U.S. Pat. No. 5,453,526 B1 teaches a catalytic reactor where liquid media can be continuously introduced, evaporated, and fed to a catalytic reaction. U.S. Pat No. 3,359,074 teaches a polycondensation system of a single vertically extending column which is transversely partitioned to define, in descending order, a reaction chamber, an evaporator chamber, and a finishing chamber. Two articles, Bej K. S.; Rao, M. S. Ind. Eng. Chem. Res., 1991 30 (8), 1819-1832, and Eliezer K. F.; Bhinde, M.; Houalla, M.; Broderick, D.; Gates, B. C.; Katzer, J. R.; Olson, J. H. Ind. Eng. Chem. Fundam., 1977, 16 (3), 380-385 show where additional particles are used to aid in flow distribution before a feed is contacted with a catalyst. What is needed is an evaporator that can be integrated into a process vessel, that accommodates a liquid feed so that the seals will not be compromised during operation of the process vessel, while providing for the feed to be in a vapor phase during reaction. 
     Another problem that can occur in some applications is the formation of trace species with dew points that are significantly higher than the temperature of the desired product, which causes a fraction of the reactor effluent mixture to condense out of the gas phase into the liquid phase. For some undesirable trace species, not only is the dew point high, but so is a “freezing point,” resulting in the formation of a solid phase which can obstruct flow of reactor effluent stream. What is needed is a reactor that can accommodate a product with a high dew point and keep the product in the gas phase to avoid clogging of the apparatus. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a reactor with an integral evaporator for vaporizing a liquid feed to form a vapor and reacting the vapor in the presence of a catalyst. 
     It is another object of the present invention to provide an array of a plurality of reactors, wherein each reactor has an integral evaporator for vaporizing a liquid feed within each reactor to form vapor and reacting the vapor in the presence of a catalyst within each of the plurality of reactors. 
     In accordance with the present invention, a reactor is provided for vaporizing a liquid feed to form a vapor and reacting the vapor in the presence of a catalyst. The inventive reactor includes a housing having an inlet for receiving the liquid feed and an outlet for product, the housing encasing an evaporation zone and a reaction zone, an injector passing through the inlet of the housing and having an orifice in the evaporation zone for introducing liquid feed, an insert containing packing within the evaporation zone for vaporizing the liquid feed, a receptacle retaining catalyst in the reaction zone, and at least one heater associated with a portion of the reactor. The injector orifice and the packing define a gap that is sufficiently small to interfere with the formation of a drop at the orifice. 
     In one embodiment, the reactor of the invention includes a header which has a first inlet for a liquid feed and a second inlet for a gas feed, where the housing inlet receives the header. The insert is adjacent to the header so that the first inlet and the second inlet are in fluid communication with the insert. A first seal is placed between the housing and the header to prevent the feeds from leaking and a second seal is placed between the insert and the receptacle to prevent the feeds from leaking past the catalyst. 
     In accordance with the present invention, an array of a plurality of the reactors is provided for evaporating liquid feed and reacting the resulting vapor in the presence of catalyst to make product. The inventive array includes a plurality of housing, each housing having at least one inlet and at least one outlet and encasing an evaporation zone and a reaction zone, a plurality of inserts for containing packing within the evaporation zones for vaporizing the liquid feed to form vapor, a plurality of receptacle retaining catalyst within the reaction zones for contacting and reacting the vapor to form product, where the inserts are placed within the receptacles, and at least one heater associated with a least a portion of the housings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is an exploded side view of a reactor. 
         FIG. 2  is a top view of an insert. 
         FIG. 3  is a cross-sectional side view of an assembled reactor. 
         FIG. 4  is a side close up view of the orifice of the injector and the packing. 
         FIG. 5  is a side view of an alternative assembled reactor. 
         FIG. 6  is a side view of an assembled array. 
         FIG. 7  is a perspective view of the array and the quick connect system. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the figures, there is shown a novel and improved reactor  10  for evaporating liquid feed to form a vapor and reacting said feed in the presence of catalyst to make a product. The inventive reactor  10  prevents seals  28  and  30  and from being compromised and maintains a reliable seal between reactor  10  and the environment while also providing for a liquid feed to be vaporized within reactor  10  as required by a reaction. Reactor  10  is particularly useful for evaluation of a catalyst  24  for a particular reaction. The inventive reactor  10  may also be used in an array  120  for the simultaneous reaction of a liquid feed in the presence of several catalysts and for the evaluation of multiple catalysts in a combinatorial method. The integrated vaporization of the liquid feed within the reactor makes reactor  10  more versatile than previous reactors used for the combinatorial process because it allows for a liquid component to be introduced to reactor  10 , even if it needs to be in the vapor phase before it is contacted with catalyst  24 , and reactor  10  can perform the vaporization without seal  28  and  30  failing and experimental results being compromised. 
     A. Reactor 
     Turning to  FIG. 1 , reactor  10  includes a housing  12  for housing reactor  10 , a header  14  which provides inlets for the feed to housing  12 , an insert  16  attached to header  14  which retains an evaporation zone  18  for vaporizing the liquid feed, an evaporator heater  20  (see  FIG. 3 ) for providing the heat necessary to vaporize the liquid feed to form a vapor, and a receptacle  22  which retains a catalyst  24 , catalyst  24  forming a reaction zone  26 . The vapor is contacted with catalyst  24  and reacted to form a product. A gas feed may also be introduced to reactor  10 , mixed with the vapor in the evaporation zone  18 , and reacted with the vapor in the presence of catalyst  24  to form the product gas. 
     The liquid feed may be any liquid component or mixture of liquid components, that is able to be vaporized under predetermined temperatures and pressures and is intended to undergo a reaction that is capable of being catalyzed by catalyst  24 . The feed is preferred to be a liquid hydrocarbon mixture. Examples of hydrocarbon intended for the use in reactor  10  are aromatic, aliphatic, and naphthene compounds having six or more carbon atoms, preferably six to nine carbon atoms. Examples of intended feed components are benzene, toluene, xylenes, ethyl benzenes, cumene, higher alkyl substituted benzenes, cyclohexanes, cyclopentanes, higher alkyl substituted cyclic paraffins, pentanes, hexanes, heptanes, octanes, nonanes, decanes, and higher molecular weight aliphatics and mixtures of the above. Alternatively, the liquid feedstock may be or may contain one or more components having hydrogen, carbon, and another element such as oxygen, chlorine, sulfur, nitrogen, and the like. 
     A gas feed is not necessary for the use of reactor  10 , but is included in the discussions below merely to exemplify reactions involving a gas feed as well as a liquid feed. The gas feed may be any gas that can activate or reactivate surface reactive sites or undergo reaction that is capable of being catalyzed by catalyst  24  and could be an organic or inorganic gas. Examples of gas feeds are hydrogen gas, oxygen gas or light hydrocarbons in the gas phase such as methane or ethane. Alternatively, the gas feed could be an inert gas, such as Nitrogen, to act as a carrier for the vaporized liquid feed but not intended to react in reaction zone  26 . The feed to the reactor of the present invention may be one or more gas phase feeds, one or more liquid phase feeds, or a combination of one or more gas phase feeds and one or more liquid phase feeds. 
     Both the liquid feed and the gas feed are introduced to reactor  10  in measured amounts, and with known compositions so that the amount of each component being introduced to reactor  10  is known. The known amount of each component entering reactor  10  combined with the measured flow rate and the analyzed composition of the product gas is used to determine the activity, feed conversion, major product and byproduct selectivities and yields of catalyst  24  in reactor  10 . 
     A first seal  28  is placed between the header  14  and the housing  12  to provide a barrier between reactor  10  and its environment and a second seal  30  is placed between the insert  16  and receptacle  22  to prevent leaks between the insert  16  and receptacle  22 . The removable parts of reactor  10 , along with seals  28  and  30 , allow for easy assembly and disassembly of reactor  10 , as well as allowing individual parts to be replaced if needed. For example, if receptacle  22  becomes damaged, it can be replaced easily with an identical receptacle  22  simply by placing the new receptacle  22  into reactor  10  and engaging seals  28  and  30 . Other parts that are not damaged, do not need to be replaced. The ability of housing  12 , insert  16  and receptacle  22  to be removed and replaced allows easy assembly of reactor  10 , which is beneficial for the experimental setup of a combinatorial array  120 . 
     Dimensions will be provided for the elements of reactor  10 , however the inventive reactor  10  of the present invention is not limited to the dimensions described below, which are provided simply for context in the preferred case of a combinatorial-scale reactor to be used in an array. It is conceivable that reactor  10  could be scaled up to a pilot plant or even a commercial scale or scaled down to micro-scale without varying from the generally broad scope of the invention. 
     1. Housing 
     As is best shown in  FIG. 1 , housing  12  includes an inlet end  32  for receiving feeds and an outlet end  34  for products. Housing  12  encases evaporation zone  18  and reaction zone  26 . Housing  12  includes a shoulder  36  at inlet end  32  of housing  12 , a main section  38  between shoulder  36  and outlet end  34 , and a product conduit  40  at the outlet end  34 . Product conduit  40  is attached to housing  12  at the outlet end  34  and allows a path for product to be withdrawn from reactor  10 . Shoulder  36  includes a surface  42  for seal  28  to engage between housing  12  and header  14 . Seal  28  prevents feeds from leaking from reactor  10  into the environment. Seal  28  may be retained by shoulder  36  of housing  12  or it may be retained by header  14  without varying from the scope of the invention. 
     Seal  28  may be any type capable of forming a reliable, pressure-tight seal between housing  12  and header  14 , but it is preferred that seal  28  be of a type that allows quick assembly of reactor  10 . An example of an acceptable seal  28  being an elastomeric O-ring, or set of O-rings engaged between housing  12  and header  14 . However, typical elastomeric O-ring seals have a maximum temperature limitation for long-term operation of between about 170° C. and 300° C., which is lower than the bubble points of most liquid feeds that will be introduced to reactor  10 . For example, boiling points of C 6  to C 9  hydrocarbons at pressures of between about 400 psig (2860 kPa) and about 500 psig (3351 kPa) range from about 300° C. and about 400° C. Note that the present invention is not limited to operating pressures in the range of 400 psig (2860 kPa) to 500 psig (3351 kPa). Reactor  10  of the present invention could be operated at ambient pressure or in vacuum, or at pressures higher than 500 psig (3351 kPa). The only limitation on operating reactor pressure is a differential pressure limitation on seal  28 . 
     Because of bubble or boiling points that are higher than maximum seal limitations, many liquid feeds cannot be vaporized upstream of reactor  10 , because their elevated temperatures would compromise the integrity of seals  28  and  30 . To solve this problem, an evaporator  44  is placed within reactor  10 , downstream of seal  28  so that the maximum temperature limitation is not reached at seal  28 . It is also desirable to keep seals  28  and  30  in a cool zone that is separate from the heated evaporation zone  18 . 
     Housing  12  and shoulder  36  are preferably cylindrical in shape, but may be of another geometric shape. For ease of discussion, housing  12  and shoulder  36  will each be described as a cylinder having a length and a diameter, but it must be emphasized that the invention is not limited to a cylindrical shape having the size described herein. Other shapes and sizes of housing  12  could also be successfully employed. For the purpose of combinatorial use, reactor  10  is preferred to be small and easy to manipulate so that an array  120  of multiple reactors  10  can be assembled easily without the use of bulky parts. 
     In one embodiment, main section  38  of housing  12  may have a length of between about 13 cm and 14 cm and an inner diameter of between about 0.4 cm and about 0.5 cm. Shoulder  36  may have a length of about 1.0 cm and a diameter of between about 0.8 cm and about 1.0 cm. Product conduit  40  may have an inner diameter of less than 1 mm to about 1.5 mm. However, housing  12 , shoulder  36  and product conduit  40  are not limited to the above dimensions and could be scaled up or down without varying from the scope of the present invention. 
     Housing  12  is preferably constructed out of a material that is inert to reaction with the liquid and gas feeds, is resistant to corrosion, can withstand temperatures of from about 10° C. to about 1000° C., and has good heat transfer properties. Examples of suitable materials of construction include metals and their alloys, low grade steel, stainless steels, super-alloys like Incolloy, Inconel and Hastelloy, engineering plastics and high temperature plastics, ceramics such as silicon carbide and silicon nitride, glass, and quartz. A preferred material of construction of housing  12  is 321 stainless steel and a preferred material of construction of shoulder  36  is 316 stainless steel. 
     2. Header 
     As shown in  FIG. 1 , header  14  and insert  16  are connected to each other so that header  14  and insert  16  form a single piece. Header  14  and insert  16  may be connected by any number of methods such as threading, bolting or welding, but it is preferred that they be able to be disengaged from one another so that packing  76  may be changed out if desired. 
     Header  14  provides fluid to inlet end  32  of housing  12 . Header  14  also provides a surface  46  for seal  28  to engage between header  14  and housing  12  at shoulder  36 , however seal  28  could engage between housing  12  and insert  16 . Header  14  includes an injector  48  for a liquid feed inlet, a gas feed inlet  50 , a diluent gas inlet  52  and a guide tube  56  for a thermocouple  54  to measure the temperature within reactor  10 . Header  16  is received by housing  12  at inlet end  32 . 
     It is preferred that the cross-section of header  14  be of the same general shape as the cross-section of housing  12  so that header  14  will easily fit within shoulder  36  of housing  12  within predetermined tolerances. It is preferred that header  14  be generally cylindrical, but header  14  could be generally of another geometric shape. For ease of discussion, header  14  will be described as being generally cylindrical with a length and a diameter. Header  14  fits within shoulder  36  of housing  12 , engaging with seal  28 , so that a portion of header  14  is above shoulder  36  of housing  12 . 
     The length of header  14  is preferably larger than the length of shoulder  36  of housing  12  and the diameter of header  14  is preferably slightly smaller than the diameter of shoulder  36  of housing  12  within tolerance limits so that an adequate seal can be formed between header  14  and housing  12 . The diameter of header  14  is also preferred to be large enough so that there is enough area for injector  48 , gas feed inlet  50 , diluent gas inlet  52  and guide tube  56 . In one embodiment, header  14  may have a length between about 1.0 cm and about 1.5 cm and a diameter of between about 0.8 cm and about 0.9 cm. However, header  14  is not limited to the above dimensions and could be scaled up or down without varying from the scope of the present invention. 
     Like housing  12 , header  14  is preferably constructed out of a material that is inert to reaction with the liquid and gas feeds, is resistant to corrosion, can withstand temperatures of from about 10° C. to about 1000° C., and has good heat transfer properties. It is preferred that housing  12  and header  14  be made from similar, or identical materials. Examples of suitable materials of construction include metals and their alloys, low grade steel, stainless steels, super-alloys like Incolloy, Inconel and Hastelloy, engineering plastics and high temperature plastics, ceramics such as silicon carbide and silicon nitride, glass, and quartz. A preferred material of construction of header  14  is 316 stainless steel. 
     Injector  48  passes through inlet end  32  of housing  12  via header  14  and is in fluid communication with the interior of insert  16  so that injector  48  extends substantially into insert  16 , and liquid feed is introduced through an orifice  66  of injector  48  into insert  16 . Preferably, orifice  66  is located within evaporation zone  18  so that the liquid feed is introduced directly into evaporation zone  18 . Preferably, injector  48  is placed so that it is approximately centered radialy within the insert  16 . The radial centering allows for uniform distribution of the liquid feed within evaporator  44 . Injector  48  is preferably tubular with a small inside diameter and an orifice  66 . In one embodiment the diameter of orifice  66  of injector  48  may be about 0.2 mm. The length of injector  48  that is within insert  16  may be about 5 cm. 
     Gas feed inlet  50  extends through header  14  and is in fluid communication with insert  16  so that a gas feed introduced to the insert  16  enters upstream of a liquid feed introduced to insert  16 . Diameters of gas feed inlet  50  may be larger than the diameter of liquid feed inlet. The diameter of gas feed conduit is chosen to accommodate a predetermined flow rate of gas feed. In one embodiment gas feed inlet  50  may have a diameter of less than 1 mm. The length of gas feed inlet  50  is approximately the same as the length of header  14 . 
     Diluent gas inlet  52  extends through header  14  and through a fluid path  68  in reactor  10  so that the diluent gas can bypass catalyst  24  and dilute the product stream and prevent condensation, as discussed below. The diluent gas may be any gas used to dilute the product and suppress the partial pressure of the product or unreacted feed to prevent condensation. It is preferred that the diluent gas be the same gas as the gas feed so that they may be introduced from a common reservoir, but any gas may be used to dilute the product stream. The diameter of diluent gas inlet  52  is chosen to accommodate a predetermined flow rate of the diluent gas. In one embodiment, diluent gas inlet  52  may have an inner diameter less than 1 mm. The length of diluent gas inlet  52  is approximately the same as the length of header  14 . 
     Optional thermocouple  54  is placed within reactor  10  for measuring the temperature within housing  12 . Preferably, optional thermocouple  54  measures the temperature within reaction zone  26 . In one embodiment, thermocouple  54  is retained by a guide tube  56  in header  14  and extends along the length of insert  16  and passes into receptacle  22  so that a sensor  70  of thermocouple  54  is generally centered within reaction zone  26 . However, only the location of sensor  70  effects the invention. Thermocouple  54  may be placed so that it is inserted through the sides of housing  12  and receptacle  22  so that sensor  70  is generally centered within reaction zone  26 . 
     Optional guide tube  56  provides a way for a thermocouple  54  to be easily placed into reactor  10  to measure the temperature within reaction zone  26 . The diameter of guide tube  56  depends on the diameter of thermocouple  54 . In one embodiment, the inner diameter of guide tube  56  may less than 1 mm. 
     However, injector  48 , gas feed inlet  50 , diluent gas inlet  52  guide tube  56  are not limited by the above dimensions and could be scaled up or down without varying from the scope of the present invention. 
     Guide tube  56  is preferably constructed out of a material that is inert to reaction with the liquid and gas feeds, is resistant to corrosion, can withstand temperatures of from about 10° C. to about 1000° C., and has good heat transfer properties. It is preferred that guide tube  56  is constructed from similar or identical materials as the housing  12  and header  14 . Examples of suitable materials of construction include metals and their alloys, low grade steel, stainless steels, super-alloys like Incollsy, Inconel and Hastelloy, engineering plastics and high temperature plastics, ceramics such as silicon carbide and silicon nitride, glass, and quartz. A preferred material of construction of guide tube  56  is 321 stainless steel. 
     3. Insert 
     Header  14  and insert  16  are disengageably connected so that header  14  and insert  16  form a single piece. Header  14  is adjacent to insert  16  so that injector  48  and gas feed inlet  50  are in fluid communication with evaporation zone  18 . Header  14  and insert  16  may be connected by any number of methods such as threading or bolting, but it is preferred that they be able to be disengaged from one another so that packing  76  may be changed out if desired. 
     Header  14  and insert  16  are placed within housing  12  so that seal  28  is engaged between header  14  and housing  12 , sealing reactor  10  from its environment and so that insert  16  is within receptacle  22 . Insert  16  is preferably removable. Insert  16  includes an inlet end  72  and an outlet end  74 . Insert  16  contains packing  76  to form a bed  78  within evaporation zone  18  for vaporizing the liquid feed to form a vapor. Although particulate packing  76  as described is preferred, other evaporation surfaces may be employed instead of a particulate packing  76  (see below). 
     A fluid permeable member  80  is attached at outlet end  74  of insert  16  to retain packing  76 , but still allow fluids, such as the gas feed and the vapor to pass into receptacle  22  to be contacted with catalyst  24 . Fluid permeable member  80  is preferably a sintered metal, such as Hastelloy, but could be any material that is permeable to the fluids flowing into reaction zone  26  in receptacle  22  and sufficiently strong to support packing  76 . Other possible materials of fluid permeable member  80  include glass, sintered glass, Raney metals, electro-bonded membranes, etched alloy membranes, and fine meshed screens with gaps smaller than the minimum packing size, but large enough to allow the gas feed and vapor to flow adequately. 
     Packing  76  could be in any form, so long as it interferes with the formation of a droplet (described below) and provides surfaces  82  for the liquid feed to form a thin liquid film  84 . Packing  76  may be particulate packing, as shown in  FIG. 4 , or it may be a prefabricated, structured monolithic packing, or it may be another means to interfere with droplet formation and provide surfaces for the formation of a thin liquid film  84 , such as a metal insert placed within evaporation zone  18  near orifice  66 . For ease of discussion, packing  76  is described as a particulate packing having a diameter. 
     Thin liquid film  84  allows efficient evaporation of the liquid feed when heat is provided by an evaporator heater  20 . Packing  76  is preferably inert to the gas feed and the liquid feed and may be any inert packing material, such as alumina, and preferably microporous alumina. Packing  76  may be of a uniform size with the same diameter for each particle, or of a random size with minimum and maximum particle diameters. The minimum diameter of packing  76  is preferably larger than the diameter of orifice  66  of injector  48  so that packing  76  does not clog injector  48 , and the maximum diameter of packing  76  should be no larger than about 10% of the inner diameter of insert  16  to prevent the formation of wall flow along interior surface of insert  16 . In one embodiment, the diameter of packing  76  may be between about 0.21 mm and about 0.42 mm. 
     Insert  16  is preferably of the same general shape as housing  12  so that it will fit easily within housing  12 . Insert  16  is preferably cylindrical in shape, but may be of another geometric shape. For ease of discussion, insert  16  is described as a cylinder having a length and a diameter. In one embodiment, insert  16  may have a length of about 10 cm and a diameter of about 0.3 cm. The diameter of insert  16  is chosen so that insert  16  will fit within receptacle  22  within predetermined tolerances. Insert  16  is not limited to the above dimensions and could be scaled up or down without varying from the scope of the present invention. 
     Insert  16  is preferably constructed out of a material that is inert to reaction with the liquid and gas feeds, is resistant to corrosion, can withstand temperatures of from about 10° C. to about 1000° C., and has good heat transfer properties. It is preferred that insert  16  be constructed of a similar, or identical material as the housing  12  and header  14 . Examples of suitable materials of construction include metals and their alloys, low grade steel, stainless steels, super-alloys like Incolloy, Inconel, Hastelloy, engineering plastics and high temperature plastics, ceramics such as silicon carbide and silicon nitride, glass, and quartz. A preferred material of construction of insert  16  is 321 stainless steel. 
     Insert  16  also provides a surface  86  for seal  30  to engage between insert  16  and receptacle  22 . Seal  30  prevents the feeds from leaking past catalyst  24  and prevents the diluent gas from passing into receptacle  22  and coming into contact with catalyst  24 . Seal  30  may be retained by insert  16 , header  14  or or receptacle  22  without varying from the scope of the invention. 
     As with seal  28 , seal  30  may be of any type capable of forming a reliable, pressure tight seal between insert  16  and receptacle  22 , but it is preferred that seal  30  be of a type that allows quick assembly of reactor  10 . An example being an elastomeric O-ring, or set of O-rings to engage between insert  16  and receptacle  22 . However, most elastomeric O-ring seals have a maximum temperature limitation that is lower than the bubble point of most liquid feeds that will be introduced to reactor  10 . 
     4. Evaporator—Evaporation Zone 
     Because of bubble points higher than maximum seal limitations, most liquid feeds cannot be vaporized upstream of reactor  10  because their elevated temperatures would compromise the integrity of seals  28  and  30 . To solve this problem, an evaporator  44  is placed within reactor  10 , downstream of seal  30  so that the maximum temperature limitation is not reached at seal  30 . 
     Integrating an evaporator within reactor  10  has some inherent problems that need to be overcome in order for evaporator  44  to be effective, and provide a vaporized gas stream with a constant and uniform composition. One of these problems is non-uniform mixing of a gas feed and liquid feed, and another is non-uniform vaporization of a liquid feed. If the composition of the gas entering reaction zone  26  is not uniform, it will create unreliable results. With one main purpose of reactor  10  being the evaluation of catalysts, unreliable results would yield unreliable data on catalyst  24  for the reaction in question. 
     One problem associated with evaporators in general is non-uniform mixing of a liquid feed and a gas feed. One way non-uniform mixing occurs is when both a gas and a liquid are introduced to an evaporator through a common inlet. The combined feed of liquid and gas causes alternating regions of gas entrainment and liquid pulsation being introduced to an evaporator, and therefore regions of low concentration of the vaporized species followed by regions of high concentration of the vaporized species being sent to a reactor bed. 
     Another problem associated with evaporators in general is non-uniform vaporization which occurs mainly because of a non-uniform flow of liquid into an evaporator. In the case of slower moving flow, a liquid issuing from an orifice into an evaporator can form droplets that detach at a regular periodicity because of the fluid dynamics of the liquid. The periodic formation and detachment of droplets leads to non-uniform vaporization within the evaporator. 
     A stream of liquid issuing out of an orifice can become unstable due to capillarity. This instability results in the formation of drops the size of which can be accurately predicted by linear stability analysis. The character of the liquid breakup at the orifice is primarily controlled by the Weber number, We: 
       We   =       ρ   ⁢           ⁢     DU   2       σ         
 
where D is the diameter of the orifice, U is the average liquid velocity, ρ is the liquid density and σ is the surface tension. The Weber number expresses the balance between external kinetic force and surface force, wherein the external force on the droplet is defined by: 
         F   D     =         ρ   ⁢           ⁢     U   2       2     ·       π   ⁢           ⁢     D   2       4           
 
and the surface force of the droplet is defined by:
 
F S =πDσ
 
The free interface of the droplet is stable when F D &lt;F S  or: 
               ρ   ⁢           ⁢     U   2       2     ·       π   ⁢           ⁢     D   2       4       &lt;     π   ⁢           ⁢   D   ⁢           ⁢   σ   ⁢           ⁢   We       =         ρ   ⁢           ⁢     DU   2       σ     &lt;   8         
 
     When the Weber number is less than 8, a stable interface is created and uniform axi-symetric droplets form at the orifice. In the case of reactor  10 , liquid is introduced to evaporator  44  at low liquid flow rates, which result in low liquid velocities. For reactor  10 , it is not uncommon to have Weber numbers that are much less than one. At very low Weber numbers the droplets approach static equilibrium conditions, and the droplet diameter can be very accurately predicted using the Young-LaPlace equation: 
           (       π   ⁢           ⁢     s   3       6     )     ⁢     g   ⁡     (       ρ   L     -     ρ   G       )         =     π   ⁢           ⁢   D   ⁢           ⁢   σ         
 
where s is the predicted diameter of the droplet, g is the acceleration of gravity, ρ L  is the density of the liquid, ρ G  is the density of the gas, D is the diameter of the orifice and σ is the surface tension of the liquid.
 
     The droplet volume and liquid flow rate allow the estimation of droplet detachment times, in the case of reactor  10  of between about 4 and about 6 seconds. The periodic detachment of droplets leads to severe malfunctioning patterns of vapor concentrations associated with non-uniform vaporization of the droplets. 
     In the inventive evaporator  44  of the present invention, the problem of non-uniform mixing is solved by feeding the liquid feed and gas feed at different locations within insert  16  so that mixing occurs between the gas feed and liquid feed in evaporation zone  18 , not in injector  48 . Liquid feed enters insert  16  through orifice  66  of injector  48 , where orifice  66  is a substantial distance down the length of insert  16 , while gas feed enters insert  16  near inlet end  72  of insert  16 . Preferably, orifice  66  is located within evaporation zone  18 . 
     To prevent periodic droplet formation and detachment, and thereby solve the problem of non-uniform vaporization, at least one evaporation surface, such as surfaces  82  of packing  76 , is placed within the inventive evaporator  44  of the present invention relative to orifice  66  of injector  48  to interfere with the formation of droplets. 
     Evaporation surfaces other than those on packing  76  as described may be successfully employed in the present invention. Examples of such evaporation surfaces include, but are not limited to, plates, a porous monolith, a cone, and the like. The selected evaporation surface is positioned to prevent the formation of a droplet at orifice  66  of injector  48 . the description herein will exemplify the preferred embodiment where the evaporation surfaces are surfaces  82  of packing  76 , however, one of ordinary skill in the art would readily understand the invention as employing other suitable evaporation surfaces. 
     Bed  78  provides an evaporation zone  18  necessary to effectively vaporize the liquid feed. Evaporation zone  18  is encased within housing  12 .  FIG. 4  shows a close up view of injector  48  and packing  76  at the point where the liquid feed is injected into bed  78 . Injector  48  includes orifice  66  with a diameter D at its terminal end. Liquid feed flows through injector  48  at a average liquid flow rate, U, that would result in the periodic formation of a droplet  88  with a diameter, s, as shown in  FIG. 4 , where s is determined by the Young-LaPlace equation. Packing  76  is placed in close proximity to orifice  66 , defining a gap  90  between orifice  66  and packing  76 . It has been hypothesized that if gap  90  is sufficiently smaller than the predicted diameter s of droplet  88 , then packing  76  will interfere with the formation of a stable interface and droplet  88  is not allowed to form. Instead, the liquid feed forms a thin liquid film  84  on the surfaces  84  of packing  76  allowing uniform vaporization of the liquid feed. Because of the uniform vaporization, a constant concentration of vapor is contacted by catalyst  24 , resulting in accurate results obtained by reactor  10 . It is preferred that gap  90  be minimized to be as small as possible without plugging orifice  66  to ensure that packing  76  interferes with the creation of a stable interface of droplet  88 . 
     Unexpectedly, a minimized gap  90  between packing  76  and orifice  66  in inventive evaporator  44  of the present invention is so effective that attempts to reproduce non-uniform vaporization by setting evaporator heater  20  low enough so that the temperature of the liquid feed is below its bubble point until well into bed  78  were unsuccessful. No malfunctioning concentration patterns were created by evaporator  44 , despite the attempt to artificially produce them. 
     In order to ensure adequate flow distribution over packing  76  in bed  78 , it is important to use appropriate sizes of packing  76 . Diameters of packing  76  should be small enough to avoid a “wall effect” of the liquid flowing along the inner surface of insert  16 . Preferably, the maximum diameter of packing  76  should be less then about 10% of the inside diameter of insert  16  to avoid wall flow. However, the minimum diameter of packing  76  should be larger than the diameter of orifice  66  to prevent clogging of orifice  66  by particles of packing  76 . In one embodiment, the diameter of packing  76  may be between about 0.21 mm and about 0.42 mm. However, packing  76  is not limited to the above dimensions and could be scaled up or down without varying from the scope of the present invention. 
     Evaporator  44  of reactor  10  is not limited to use in a reactor. Evaporator  44  itself is novel and inventive and provides an improvement over previous evaporators. The inventive evaporator  44  of the present invention could also be used in another process vessel where it is desirable to vaporize a liquid feed, followed by further processing in a treatment zone within the same process vessel. The process vessel would have both an evaporation zone and a treatment zone, with the evaporation zone including the inventive evaporator  44 . In the case of the present invention, reactor  10  is the process vessel and reaction zone  26  is the treatment zone of the vapor. 
     5. Evaporator Heater 
     Evaporator heater  20  provides the necessary energy to vaporize liquid feed within bed  78 . Evaporator heater  20  is associated with a portion of reactor  10 . Preferably, evaporator heater  20  is associated primarily with evaporation zone  18  at the point where the liquid feed is injected into bed  78  as shown in  FIG. 3 , although other locations may be successful as well. The duty of evaporator heater  20  is preferably provided by electrical resistive heating adjacent to housing  12 . Evaporator heater  20  could be a heater block with a thickness larger then the diameter of housing  12  so that evaporator heater  20  is placed around housing  12  housing  12 . However, evaporator heater  20  could be any other type of heater, such as one utilizing a heat transfer fluid, and would not vary from the scope of the invention. Evaporator heater  20  is set at a temperature sufficient to vaporize the liquid feed within evaporation zone  18 , forming a vapor. Preferably, the temperature of the liquid feed at orifice  66  is below its bubble point, and evaporator heater  20  is set so that the liquid feed is heated to above its bubble point within evaporation zone  18 , creating a temperature gradient within evaporation zone  18 . Still more preferably, evaporator heater  20  is set so that a temperature gradient is created throughout evaporation zone  18  so that the temperature of the vapor is heated to a predetermined reaction temperature within evaporation zone  18  before the vapor enters reaction zone  26 . 
     In one embodiment, the thickness of evaporator heater  20  may be about 8 mm. However, evaporator heater  20  is not limited to the above dimensions and could be scaled up or down without varying from the scope of the present invention. 
     6. Receptacle 
     Referring to  FIG. 3 , receptacle  22  is placed within housing  12 , and insert  16  is placed within receptacle  22  in a nested configuration so that seal  28  is engaged between header  14  and shoulder  36  of housing  12  and seal  30  is engaged between insert  16  and receptacle  22 . Receptacle  22  is preferably removable. Receptacle  22  includes an inlet end  94  and an outlet end  96 . A flange  98  is attached to inlet end  94 . Flange  98  of receptacle  22  includes cut-out sections  102  (See  FIG. 2 ) to allow a diluent gas to pass through. The diluent gas passes through cut-out sections  102  in flange  98  and into a fluid path  68  formed between receptacle  22  and main section  38  of housing  12 . 
     Receptacle  22  retains catalyst  24 , within reaction zone  26 . It is within reaction zone  26  that the gas feed and the vapor are contacted, at reaction conditions, with catalyst  24 , where they are reacted to form a product. A fluid permeable member  104  is attached at outlet end of receptacle  22  to retain catalyst  24 , but allow fluids, such as unreacted feeds and product gas, to pass out of receptacle  22  and exit reactor  10  out of product conduit  40 . Fluid permeable member  104  is preferably a sintered metal, such as Hastelloy, but could be any material that is permeable to the fluids passing out of receptacle  22  and sufficiently strong to support catalyst  24 . Other possible materials of fluid permeable member  104  include glass, sintered glass, Raney metals, electro-bonded membranes, etched alloy membranes, and fine meshed screens with gaps that are smaller than the size of catalyst  24 , but large enough to allow the unreacted feeds and product gas to flow adequately. 
     Catalyst  24  is selected to provide active sites for the desired reaction. Catalyst  24  may be any material or mixture of materials that possibly catalyze the desired reaction, but preferably catalyst  24  is a zeolite or some other type of catalyst that can be synthesized by combinatorial methods. In one embodiment, an effective mass of catalyst  24  placed within receptacle  22  of reactor  10  may range from about 1 mg to about 1 gram. However, catalyst  24  is not limited to the above masses, and more or less catalyst  24  could be added to reactor  10  without varying from the scope of the present invention. 
     Reaction zone  26  is flanked by fluid permeable members  80  and  104  upstream and downstream of catalyst  24  and by inner surface  106  of receptacle  22  on the side so that catalyst  24  remains within reaction zone  26 . Reaction zone  26  has the same diameter as the inside diameter of receptacle  22 . In one embodiment, reaction zone  26  may have a height of between about 1.0 cm and about 1.5 cm. 
     Receptacle  22  is preferably of the same general shape as housing  12  and insert  16  so that receptacle  22  may easily fit between housing  12  and insert  16  within predetermined tolerances. Receptacle  22  is preferably cylindrical in shape, but may be of another geometric shape. For ease of discussion, receptacle  22  is described as a cylinder having a length and a diameter. The length of receptacle  22  is approximately the same as the length of main section  38  of housing  12 . The lengths of insert  16  and receptacle  22  are chosen so that reaction zone  26  has its desired height. The diameter of receptacle  22  is chosen so that fluid path  68  is provided between receptacle  22  and housing  12  to allow the diluent gas to bypass reaction zone  26  as shown in FIG.  3 . Fluid path  68  may also be formed by channels or groves in receptacle  22  or housing  12  to allow the diluent gas to bypass reaction zone  26 . In one embodiment, receptacle  22  may have a length of between about 10 cm and about 14 cm and a diameter of between about 0.4 cm and about 0.5 cm. 
     The diameter of flange  98  of receptacle  22  is preferred to be approximately the same as the diameter of shoulder  36  of housing  12 . In one embodiment, the diameter of flange  98  of receptacle  22  may be about 0.8 cm. 
     Receptacle  22  and reaction zone  26  are not limited to the above dimensions and could be scaled up or down without varying from the scope of the present invention. 
     Receptacle  22  is preferably constructed out of a material that is inert to reaction with the liquid and gas feeds, is resistant to corrosion, can withstand temperatures of from about 10° C. to about 1000° C., and has good heat transfer properties. It is preferred that receptacle  22  be constructed of a similar, or identical material as housing  12  and insert  16 . Examples of suitable materials of construction include metals and their alloys, low grade steel, stainless steels, super-alloys like Incolloy, Inconel, Hastelloy, engineering plastics and high temperature plastics, ceramics such as silicon carbide and silicon nitride, glass, and quartz. A preferred material of construction of receptacle  22  is 321 stainless steel. 
     7. Reaction Heater 
     A reaction heater  108  is placed adjacent to housing  12  so that it is associated primarily with reaction zone  26  and so that all of reaction zone  26  is surrounded by reaction heater  108 . Reaction heater  108  provides heat for reaction zone  26  so that catalyst  24  and reaction zone  26  can be maintained at a controlled constant temperature. Reaction heater  108  can be any type of heater to provide the heat needed for reaction zone  26 , such as an aluminum-bronze oven using electrical resistive heating. 
     As shown in  FIG. 3 , reaction heater  108  is placed around outlet end of housing  12  so that all of reaction zone  26  is within the oven. In one embodiment, reaction heater  108  may have a thickness of about 9 cm and the length of reactor  10  that is within reaction heater  108  may be between about 4 cm and about 6 cm. However, reaction heater  108  is not limited to the above dimensions and could be scaled up or down without varying from the scope of the present invention. 
     Preferably, the length of reactor  10  that is between evaporator heater  20  and reaction heater  108  is sufficient so that the temperature at packing  76  is substantially independent of the temperature at catalyst  24 . The temperature of the liquid feed at orifice  66  of injector  48  should not be affected by how reaction heater  108  is set, and the temperature within reaction zone  26  should not be affected by how evaporator heater  20  is set. In one embodiment, the length of reactor  10  between evaporator heater  20  and reaction heater  108  may be between about 2.5 cm and about 8 cm, but reactor  10  is not limited to this dimension and could be scaled up or down without varying from the scope of the present invention. 
     8. Diluent Gas and Diluent Zone 
     Some reaction mixtures of reactor  10  include a liquid feed or a product that has a high dew point. This creates a problem for a product mixture exiting reactor  10  through outlet end after leaving reaction heater  108  because the temperature of the reaction mixture decreases to below the mixture&#39;s dew point, causing liquid feed or product to condense out of the gas phase. For some products, not only is the dew point high, but so is a freezing point, so that not only does the product condense out of the gas phase, but it also forms a solid, or plates along product conduit  40 . Condensing or plating of product causes two problems. First, it can block or obstruct flow through product conduit  40 , and second, it alters the gas phase composition of the product stream. Because it is the gas phase composition that is measured by analyzing downstream of reactor  10 , condensation or plating can adversely impact experimental results determined by reactor  10 . 
     It has been verified that the addition of a diluent gas to reactor  10  allows for a reduction in pressure for analysis of product, while preventing the condensation and plating of product. As shown in  FIG. 3 , diluent gas is introduced through diluent gas inlet  52  of header  14 . The diluent gas then passes through cut-out sections  102  in flange  98  of receptacle  22  where it flows into fluid path  68  between receptacle  22  and main section  38  of housing  12  so that the diluent gas bypasses catalyst  24 . Fluid path  68  is in fluid communication with diluent gas inlet  52  and diluent gas mixing zone  110 . Fluid path  68  may be formed due to a difference in diameter between housing  12  and receptacle  22 , as shown in  FIG. 3 , or housing  12  and receptacle  22  may have a small tolerance between them and fluid path  68  may be formed by grooves or channels in either housing  12  or receptacle  22 . Grooves or channels (not shown) may also provide for more efficient heat transfer between the diluent gas and evaporation zone  18  and reaction zone  26 . 
     The diluent gas dilutes product and unreacted feeds in mixing zone  110  downstream of reaction zone  26  and fluid permeable member  104  of receptacle  22  near outlet  34  of housing  12 . The addition of diluent gas dilutes the product stream in mixing zone  110 , lowering the concentration and partial pressure of trace undesirable byproducts in the reactor effluent, thus preventing condensation and/or plating and subsequent equipment fouling. 
     The diluent gas may be mixed with the product stream at any point downstream of reaction zone  26 , but it is preferred that it be mixed before product conduit  40  exits reaction heater  108  so that there is no possibility of condensation or plating of product. 
     The diluent gas may be any gas capable of mixing with the product stream. It is preferred that the diluent gas be the same as the gas feed so that both the gas feed and the diluent gas may be introduced to reactor  10  from a common gas reservoir. Like the liquid feed and the gas feed, diluent gas is introduced to reactor  10  in a measured amount and with a known composition so that the amount of each component being mixed with the product gas is known. 
     9. Sampling and Analyzing 
     Reactor  10  is used to evaluate catalysts by determining their activity and selectivity. To accomplish this, at least a portion of the product gases flowing through product conduit  40  is analyzed by an analyzer  112  to determine its chemical composition. In one embodiment, a portion of the product is sampled prior to analyzation by analyzer  112 . The flow rate of product in product conduit  40  is also measured so that the amount of each species exiting reactor  10  can be determined. Analyzer  112  can use any method to determine each product gasses composition, but preferably uses one of the following analytic techniques; spectroscopy, spectrometry, chromatography, nuclear magnetic resonance, or a combination thereof. 
     10. Alternative Embodiment with Cooler 
     Seals  28  and  30  and both have a maximum temperature limitation that is lower than the bubble point of many liquid feeds that will be introduced to reactor  10 . In an alternative embodiment of reactor  10 , shown in  FIG. 5 , a cooler  114  is added to maintain a temperature at seals  28  and  30  to ensure that seals  28  and  30  are not compromised. Cooler  114  is placed adjacent to housing  12  between evaporator heater  20  and header  14 , preferably so that cooler  114  is adjacent to both seals  28  and  30 . Cooler  114  is set so that the temperature of seals  28  and  30  is below their maximum temperature limitation, ensuring that seals  28  and  30  are not compromised. 
     Cooler  114  may be of any type capable of removing the heat necessary to maintain seal temperatures below the maximum temperature limitation, but it is preferred that cooler be a plate heat exchanger cooled with water flowing through a conduit within plate  116 . Plate  116  of cooler  114  may be made of any heat conducting material, but aluminum is preferred. In one embodiment the thickness of plate  116  of cooler  114  may be about 1 cm and the diameter of the cooling water conduit (not shown) within plate  116  may be about 0.0625 inches. However, cooler  114  is not limited to the above dimensions and could be scaled up or down without varying from the scope of the present invention. 
     B. Process of Evaporating and Reacting in a Reactor 
     The process by which reactor  10  vaporizes a liquid feed and reacts the resulting vapor in the presence of catalyst  24  includes the steps of providing packing  76  in evaporation zone  18 , providing catalyst  24  in reaction zone  26 , introducing a liquid feed to evaporation zone  18 , heating and vaporizing the liquid feed within evaporation zone  18  to form a vapor, flowing the vapor into reaction zone  26 , and contacting, at predetermined reaction conditions, the vapor with catalyst  24  to form a product. In some cases a gas feed may also be introduced to reactor  10  so that both the gas feed and the vapor are contacted with catalyst  24  in reaction zone  26  to react and form a product. 
     The liquid feed may be any liquid component or mixture of liquid components, that is able to be vaporized under a predetermined range of temperatures and pressures and may undergo a reaction that may be capable of being catalyzed by catalyst  24 . The liquid feed is preferred to be a liquid hydrocarbon. Examples of hydrocarbon intended for the use in reactor  10  are aromatic, aliphatic, and naphthene compounds having six or more carbon atoms, preferably six to nine carbon atoms. Examples of intended feed components are benzene, toluene, xylenes, ethyl benzenes, cumene, higher alkyl substituted benzenes, cyclohexanes, cyclopentanes, higher alkyl substituted cyclic paraffins, pentane, hexanes, heptanes, octanes, nonanes, decanes, and higher molecular weight aliphatics and mixtures of the above. Alternatively, the liquid feedstock may be or may contain one or more components having hydrogen, carbon, and another element such as oxygen, chlorine, sulfur, nitrogen, and the like. 
     It is preferred that the chemical composition of the liquid feed be known and that the liquid feed be introduced to reactor  10  in a measured amount so that calculations can be performed to determine characteristics of catalysts  24  such as activity, feed conversion, major product and byproduct selectivities and yields. 
     The gas feed may be any gas that may undergo a reaction that is capable of being catalyzed by catalyst  24 , or that may provide a stabilizing effect on the catalyst, and could be an organic or inorganic gas. Examples of gas feeds are hydrogen gas, oxygen gas, nitrogen gas or light hydrocarbons in the gas phase such as methane or ethane. It is preferred that the chemical composition and flow rate of the gas feed into reactor  10  feed be known so that calculations can be performed to determine an activity and selectivity for catalyst  24  as described below. 
     In one process, catalyst receptacle  22  is placed containing catalyst  24  for reacting vaporized feed within housing  12  where receptacle  22  is positioned within reactor  10  so that catalyst  24  is within reaction zone  26 , insert  16  is placed containing packing  76  having surfaces  82  for evaporating feed where insert  16  is positioned within receptacle  22  so that packing  76  is within evaporation zone  18 , the liquid feed is injected into evaporation zone  18  through injector  48  in a measured amount, where it passes through header  14  and into insert  16 . Next, liquid feed is injected through orifice  66  in injector  48  into bed  78  formed by packing  76 , and forms a thin liquid film  84  on the surfaces  82  of packing  76 . 
     After the liquid feed is injected into bed  78  and forms thin liquid film  84 , the liquid feed is heated by evaporator heater  20  which is situated so that the liquid feed is heated at or near orifice  66 . Evaporator heater  20  is set at a temperature sufficient to vaporize the liquid feed within evaporation zone  18 , forming a vapor. Preferably, the temperature of the liquid feed at orifice  66  is below its bubble point, and evaporator heater  20  is set so that the liquid feed is heated to above its bubble point within evaporation zone  18 , creating a temperature gradient within evaporation zone  18 . Still more preferably, evaporator heater  20  is set so that a temperature gradient is created throughout evaporation zone  18  so that the temperature of the vapor is heated to a predetermined reaction temperature within evaporation zone  18  before the vapor flows into reaction zone  26 . 
     Packing  76  is provided and placed in insert  16  so that there is a gap  90  defined between orifice  66  and packing  76  that is sufficiently small to interfere with the formation of a droplet on injector  48  at orifice  66 . Instead of forming a liquid droplet, the liquid feed forms a thin liquid film  84  on surfaces  82  of packing  76  which is easily vaporized. Heat provided by evaporator heater  20  vaporizes the liquid feed within bed  78  before it enters reaction zone  26  to contact catalyst  24  and react. After being heated and vaporized, the resulting vapor flows through the remainder of evaporation zone  18  and passes through fluid permeable member  80  and into reaction zone  26 . 
     If a gas feed is to be introduced to reactor  10 , it is introduced through header  14  in a measured amount and enters insert  16  at some point upstream of orifice  66 . The gas feed is then mixed with the vapor in evaporation zone  18  and acts as a carrier gas for the vapor as they pass down the remainder of bed  78 , through fluid permeable member  80  and into reaction zone  26 . 
     After entering reaction zone  26 , the vaporized hydrocarbon feed and the gas feed, if present, as well as catalyst  24  are heated by reaction heater  108  to a predetermined reaction temperature. Reaction heater  108  provides the heat requirement, to maintain a constant, predetermined and controlled temperature in reaction zone  26 . To control the temperature of reaction zone  26 , the temperature of reaction zone  26  is constantly measured by thermocouple  54 . This measured temperature is then used to control the setting of reaction heater  108 . For example, if the temperature measured by thermocouple  54  is too high, the actual temperature is compared with a specified temperature to create an error between the two, and this error is used to lower the heater block set-point. 
     After passing through fluid permeable member  80  in insert  16  into reaction zone  26 , the vaporized hydrocarbon and the gas feed quickly reach the predetermined temperature. The vapor and gas feed are contacted with catalyst  24  and go through at least one reaction to generate a product mixture of a product, byproducts, and unreacted feeds. The product mixture then flows out of reaction zone  26  through fluid permeable member  104  and into product conduit  40 , where it is carried away from reactor  10 . 
     A portion of the product mixture is sampled and analyzed by analyzer  112  to determine its chemical composition. The product mixture may be analyzed by any of the following analytic techniques; spectroscopy, chromatography, nuclear magnetic resonance, and combinations thereof. 
     In an alternate embodiment, reaction heater  108  may provide sufficient heat to also heat the packing  76  in evaporation zone  18 . With the heat for the packing  76  being provided by reaction heater  108 , a gradient of heat may be established across packing  76 . The amount of heat provided to the packing  76  may be controlled by the positioning of reaction heater  108  and the distance between reaction zone  26  and packing  76 . 
     As described above, in some cases it may be desirable to dilute the product mixture with a diluent gas after the product has been formed in reaction zone  26  to suppress the partial pressure of one or more components in the product mixture and prevent condensation into the liquid phase or plating into the solid phase. Preferably, the diluent gas is the same gas as the gas feed so that they may be introduced from a common reservoir. It is preferred that the chemical composition and flow rate of the diluent gas into reactor  10  be known so that calculations can be performed to determine an activity, feed conversion, major product and byproduct selectivities and yields for catalyst  24 . 
     If it is desired, the product mixture is diluted with diluent gas in mixing zone  110  after the product mixture has passed through fluid permeable member  104 . The diluent gas may be introduced by any number of methods but it is preferred that the diluent gas be introduced to reactor  10  in a measured amount and bypass reaction zone  26  so that the diluent gas does not come in contact with catalyst  24 . Feeding the diluent gas to reactor  10  is desirable so that the inlets for the liquid feed, the gas feed and the diluent gas will all be introduced to the apparatus at the same general location. However, diluent gas could be introduced to product mixture by a different method, such as a separate conduit that is in fluid communication with mixing zone  110  of fluid permeable member  104 . 
     After the diluent gas is introduced to product mixture, it quickly mixes with the product mixture in mixing zone  110  in product conduit  40  to suppress partial pressures of the components of the product mixture and forms a diluted product mixture. At least a portion of the diluted product mixture is sampled and analyzed by  112  as described above. 
     C. Array of Multiple Reactors 
     Although reactor  10  by itself is an inventive and novel reactor for vaporizing a liquid feed and reacting the resulting vapor in the presence of catalyst  24 , it is when an array  120  of two or more reactors  10  is formed and operated in parallel that the present invention provides the fullest range of utility. An array  120  of reactors  10  operated in parallel allows catalyst  24  to be tested at several different reaction conditions, or a plurality of different catalysts  24  to be compared, or a plurality of feeds or feed compositions to be contacted with catalysts  24 , or a combination thereof, so that the activity and selectivity of each catalyst  24  can be calculated for various conditions, so that the most effective catalyst, and the optimal conditions for that catalyst, can be determined for the reaction of interest. 
     As shown in  FIG. 6 , an array  120  of two or more reactors  10  is provided. Each of the reactors  10  of array  120  have all of the elements described above for reactor  10 , a housing  12 , a header  14 , an insert  16  for retaining packing  76  that forms a bed  78  within evaporation zone  18 , and a receptacle  22  for retaining catalyst  24  that forms a reaction zone  26 . Each reaction zone  26  can consist of the same catalyst  24 , and reactors  10  in array  120  can be operated at different reaction conditions, or a plurality of different catalysts  24 , or blocks of catalysts  24 , can be placed in the reaction zones  26  to compare a plurality of catalysts  24 . However, only one evaporator heater  20  is provided to heat the liquid feed at the orifices  66  of the injectors  48  in each reactor  10 . Evaporator heater  20  is placed so that it is associated with each of the outside surfaces  92  of each of the housings  12  in array  120 . 
     Reactors  10  in array  120  are intended to perform the same reaction so that common liquid feed, gas feed, and diluent gas is introduced to each reactor  10  in array  120 . The liquid feed, gas feed and diluent gas are introduced to reactors  10  simultaneously so that reactors  10  operate in parallel allowing several catalysts  24 , or several reaction conditions, to be evaluated simultaneously, greatly decreasing the experimental time requirement associated with testing multiple catalysts  24  at multiple reaction conditions by conventional methods. 
     1. Each Housing Attached to a Bottom Support Plate 
     Each housing  12  of array  120  can be a free-standing unit with the features of housing  12  described above, or the housings  12  can be formed from a single tray or block of material. It is preferred that housings  12  be free-standing units so individual housings  12  may be replaced as needed due to damage or change-out. But, it is also preferred that housings  12  be connected to a common bottom support  122  so that the plurality of housings  12  in array  120  can be moved as a single unit, as it is far more convenient to handle an assembly of one unit than to individually manipulate multiple housings  12 . Also, robotics, which is frequently used in combinatorial applications, is more readily adapted to manipulating a single tray. It is preferred that each housing  12  in array  120  be constructed of the same material, but it is not necessary. Housings  12  can be constructed of the same materials as housing  12  described above. It is further preferred that inserts  16  and receptacles  22  be constructed of the same material as housings  12 . 
     Bottom support  122  may provide for the connection of any number of individual housings  12 . For example, bottom support  122  may connect to 6, 8, 12, 24, 48, 96 or 384 of housings  12 . Also, the full capacity of a particular bottom support  122  need not be used. For example, a bottom support  122  designed to hold up to 48 of housings  12  may be used to support only 24. Array  120  is flexible in this respect, because the number of reactors  10  being used by array  120  can be changed simply by adding or taking away a desired number of housings  12  from bottom support  122 . 
     Bottom support  122  could be any shape or configuration capable of supporting the plurality of housings  12  in a desired, predetermined pattern, but it is preferred that bottom support  122  be a plate with holes for each corresponding housing  12 . As shown in FIG.  6  and  FIG. 7 , the plate of bottom support  122  includes a surface  124  which is generally planar. 
     As with the housing  12  itself, bottom support  122  may be constructed of a variety of materials including metals and their alloys, low grade steel, and stainless steels, super-alloys like Incolloy, Inconel and Hastelloy, engineering plastics and high temperature plastics, ceramics such as silicon carbide and silicon nitride, glass, quartz, Teflon polymer, nylon, and low temperature plastics such as polyethylene, and polypropylene. It is preferred that bottom support  122  be rigid enough to resist twisting from torque so that bottom support  122  remains substantially planar throughout operation of array  120 . 
     Bottom support  122  may allow for the connection of housings  12  in any number of geometrical patterns with the preferred being a grid. It is preferred that bottom support  122  has dimensions similar to the dimensions of commonly used micro titer trays. It is preferred that bottom support  122  be constructed of material that is able to withstand temperatures of from about 10° C. to about 1000° C., and for many catalytic reactions, bottom support  122  may be required to withstand temperatures ranging from about 0° C. to about 1000° C. 
     2. Each Header Attached to a Top Support Plate 
     Each housing  12  of array  120  has a corresponding insert  16  and header  14  that has all of the features of insert  16  and header  14  described above. Each of the headers  14  are connected to a top support  126  so that each housing  12  has a corresponding insert  16  placed inside the housing  12  to enclose the plurality of reactors  10  in array  120 . Headers  14  are connected to top support  126  so that the plurality of headers  14  and inserts  16  can be moved as a single unit, as it is far more convenient to handle an assembly of one unit than to individually manipulate multiple inserts  16 . Also, because housings  12  are connected to bottom support  122  and headers  14  are connected to top support  126 , the plurality of headers  14  and inserts  16  can be moved as a single pieces, allowing array  120  to be assembled by one step which simultaneously seals to form array  120 . 
     It is preferred that each header  14  and each insert  16  of array  120  be constructed of the same material, but it is not necessary. Inserts  16  may be constructed from the same materials as header  14  and insert  16  described above. In some applications it may be preferred for headers  14  and inserts  16  to be constructed from the same material, or similar material, as the corresponding housings  12 . 
     Top support  126  may provide for the connection of any number of individual headers  14 . For example, top support  126  may connect to 6, 8, 12, 24, 48, 96 or 384 of headers  14 . Also, the full capacity of a particular top support  126  need not be used. For example, a top support  126  designed to hold up to 48 of headers  14  may be used to support only 24. Array  120  is flexible in this respect, because the number of reactors  10  being used by array  120  can be changed easily simply by adding or taking away a desired number of headers  14  and inserts  16  from top support  126 . 
     Top support  126  could be any shape or configuration capable of supporting the plurality of inserts  16  in a desired, predetermined pattern, but it is preferred that top support  126  be a plate with holes for each corresponding header  14 . As shown in FIG.  6  and  FIG. 7 , the plate of top support  126  includes a surface  128  which is generally planar. 
     As with header  14  and insert  16 , top support  126  may be constructed of a variety of materials including metals and their alloys, low grade steel, and stainless steels, super-alloys like Incolloy, Inconel and Hastelloy, engineering plastics and high temperature plastics, ceramics such as silicon carbide and silicon nitride, glass, quartz, Teflon polymer, nylon, and low temperature plastics such as polyethylene, and polypropylene. It is preferred that top support  126  be rigid enough to resist twisting and torque so that top support  126  remains substantially planar throughout operation of array  120 . 
     Top support  126  may allow for the connection of inserts  16  in any number of geometrical patterns with the preferred being a grid. It is preferred that top support  126  has dimensions similar to the dimensions of commonly used micro titer trays. It is preferred that top support  126  be constructed of a material capable of withstanding temperatures from 10° C. to about 1000° C., but a preferred range of temperatures includes temperatures ranging from about 10° C. to about 300° C. 
     3. Receptacles 
     Each set of housings  12  and corresponding inserts  16  has a corresponding receptacle  22  for retaining catalyst  24  having the features of the receptacle  22  described above to form a reactor  10  within array  120 . Each reactor  10  is assembled in the same manner as described above, except that each reactor  10  is connected to a set of supports  122  and  124  to form array  120 . 
     It is preferred that each receptacle  22  of array  120  be constructed from the same material, but it is not necessary. In some case it may also be preferred for the receptacle  22  to be constructed from the same material, or a similar material, as the housing  12 , or the same material, or a similar material, as the insert  16 , or both. 
     4. Quick Connect System Including Quick Sealing 
     Array  120  of reactors  10  allows for the rapid evaluation of multiple variables simultaneously. For example, each reactor  10  of array  120  can be used to evaluate a different catalyst  24  under the same reaction pressure and temperature and with the same feed compositions, or each reactor  10  can evaluated the same catalyst  24  under varying reaction conditions, such as multiple pressures, temperatures and feed rates and compositions. To fully realize the greatest utility, it is preferred that array  120  include an apparatus that allows for the quick assembly and disassembly of array  120 . Seals  28  and  30  aid in this quick-connect because they allow each reactor  10  to be assembled quickly, but still prevent leaks between parts of the reactor and between reactor  10  and its environment. Each seal  28 ,  30  operates to seal the plurality of reactors  10  simultaneously. Housing support  122  is important because it allows the plurality of housings  12  to be moved as a single piece and insert support  126  is important because it allows the plurality of headers  14  and inserts  16  to be moved as another single piece. However, an apparatus is still needed to raise and lower housing support  122  and insert support  126 . 
     Quick-connect system  130  provides a method to raise and lower supports  122  and  126  while still assuring high precision in the horizontal plane, allowing seals  28  and  30  to seal effectively in each reactor  10 . Quick-connect system  130  can be used to raise and lower housing support  122  with insert support  126  remaining stationary, or it can be used to raise and lower insert support  126  with housing support  122  remaining stationary, or each support can have its own quick-connect system and both supports  122  and  126  can be raised and lowered as desired. For ease of discussion, quick-connect system will be described as being used to raise and lower insert support  126  while housing support  122  remains stationary, as shown in  FIG. 7 , but as discussed above quick-connect system  130  could be used for either support  122  or  126 . 
     One embodiment of quick-connect system  130  includes threaded guide rods  132 , guide rings  134 , stationary rings  136  and wheels  138 . Guide rings  134  are attached to insert support  126  so that they extend away from insert support  126 . In  FIG. 7 , a set of two guide rods  132  are shown, each guide rod  132  having a corresponding guide ring  134 , stationary ring  136  and wheel  138 . Although two of each of the pieces is shown in  FIG. 7 , any number could be used without varying from the scope of the present invention. 
     Each guide rod  132  is threaded so that when it is rotated insert support  126  will be raised or lowered depending on which direction guide rod  132  is rotated. Each guide ring  134  includes a hole  140  that is generally in the center of guide ring  134 . It is preferred that hole  140  be generally cylindrical in shape and extend through guide ring  134 . Hole  140  is also threaded so that a corresponding threaded guide rod  132  can be placed through hole  140 . Guide rod  132  and hole  140  are threaded so that when guide rod  132  is rotated, guide ring  134 , and therefore insert support  126 , is moved up or down depending on which direction guide rod  132  is rotated. 
     Each hole  140  includes an inside surface (not shown). It is preferred that the inside surface of hole  140  be generally perpendicular to surface  128  of insert support  126  so that when insert support  126  is raised and lowered surface  128  of insert support  126  remains parallel to surface  124  of housing support  122 . This perpendicular raising and lowering of insert support  126  is preferred because it ensures that seals  28  and  30  of each reactor  10  engage simultaneously when each insert  16  is lowered into its corresponding housing  12 -receptacle  22  combination as insert support  126  is lowered. If surface  128  of insert support  126  did not remain parallel to surface  124  of housing support  122  not every reactor  10  of array  120  would be sealed. Some of the seals  28  and  30  would engage properly, while other seals  28 ,  30  would not come into contact with their corresponding housings  12  or receptacles  22  and would fail to properly seal certain reactors  10 . Still other seals  28  and  30  could pinch or bind within their corresponding reactors  10 , causing a problem when insert support  126  is attempted to be raised because certain inserts  16  would stick within their corresponding housings  12 . 
     Each stationary ring  136  also includes a hole  142  for a corresponding guide rod  132  to pass through. Stationary ring  136  is anchored to a stationary support  144  of array  120  so that it remains stationary while guide rod  132  rotates. Stationary ring  136  keeps guide rod  132  in position while it is rotated so that insert support  126  is raised and lowered instead of guide rod  132 . Each hole  142  is threaded, like its counterpart hole  140  in guide ring  134 . Each hole  142  includes an inside surface (not shown) that is preferred to be generally perpendicular to the plane of surface  124  of housing support  122  so that surface  124  of housing support  122  and surface  128  of insert support  126  remain parallel throughout operation of quick-connect system  130 . Stationary ring  136  could be anchored by any method to any stationary member of array  120 , but it is preferred that it be anchored to something near insert support  126  so that guide rod  132  need not be excessively long. In one embodiment, stationary rings  136  are shown to be anchored by anchors  146  to support  144  of housing support  122 , as shown in FIG.  7 . 
     Each guide rod  132  has a corresponding wheel  138  which is used to rotate guide rod  132 . Each wheel  138  is attached to an end of guide rod  132  and may include a handle  148 . If more than one guide rod  132  is used, as shown in  FIG. 7 , it is preferred that the rotation of guide rods  132  be synchronized to ensure that support  122  or  126  remains in a horizontal plane throughout operation of quick-connect system  130 . A means that could accomplish this would be coupling the rods with a belt system (not show) so that both guide rods  132  rotate the same amount at the same time. 
     Although a quick-connect system  130  with guide rods  132 , rings  134 ,  136  and wheels  138  is described, the present invention is not limited to a quick-connect system  130  with these embodiments. Other means could be used to ensure that support plates  122  and  126  remain in a horizontal plane and remain parallel to each other, such as a precision rail guide system attached to support plates  122  and  126 . One of ordinary skill in the art will appreciate the many types of systems that could be used to raise and lower support plates  122  and  126  and still remain within the scope of the present invention. 
     Guide rods  132 , guide rings  134  and stationary rings  136  can be purchased from a supplier so that a predetermined precision can be provided by quick-connect system  130 . Examples are catalog numbers S 151101900, S 151201023, S 150600010 and S 159111020 from Rexroth Bosch Group. 
     5. Common Feed Reservoirs 
     Array  120  also creates the need for fewer feed reservoirs to store feed liquids and gases to be introduced to the reactors  10  in array  120 . Only one liquid feed reservoir  150  is required to introduce liquid feed through injectors  48  associated with each of the reactors  10  of array  120  because each reactor  10  of array  120  is performing the same reaction, with the same liquid feed. Similarly, only one gas feed reservoir  152  is required to introduce feed to the gas feed inlets  50  associated with each header  14 . Also, if the diluent gas is the same gas as the gas feed, a third reservoir is unnecessary so that only liquid feed reservoir  150  and a gas feed reservoir  152  are required for the operation of array  120 . However, if a gas other than the gas feed is used as the diluent gas, a third reservoir (not shown) for the diluent gas would be required. 
     In some cases it may be desirable to introduce the liquid feed, gas feed and diluent gas to reactors  10  in array  120  in measured amounts so that the exact amount of each substance entering each reactor  10  is known. It is desirable to do this because the combination of knowing how much reactant or diluent gas is introduced to each reactor  10  and the composition of the product gas exiting each reactor  10  can be used to calculate the activity, feed conversion, major product and byproduct selectivities and yields for each catalyst  24  in each reactor  10 . 
     6. Sampling and Analyzing 
     Array  120  is used to evaluate catalysts by determining their activity and selectivity. To accomplish this, at least a portion of each of the product mixtures flowing through each product conduit  40  is sampled and analyzed to determine its composition. Preferably, analyzer  112  uses any one of the following analytic techniques to determine each product gases composition; spectroscopy, spectrometry, chromatography, nuclear magnetic resonance, or a combination thereof. 
     7. Reaction Heater 
     As with individual reactor  10 , array  120  includes reaction heater  108  shown in FIG.  6 . Reaction heater  108  of array  120  provides heat for reaction zones  26  so that catalysts  24  can be kept at a controlled constant temperature. Reaction heater  108  can be any type of heater to provide the heat needed for reaction zones  26 , such as an aluminum-bronze oven using electrical resistance heating. 
     Although  FIG. 6  shows a single reaction heater  108  common to all reactors  10  in array  120 , in some cases it may be desirable that each reactor  10  in array  120  have its own corresponding reaction heater  108  so that different reactors  10  in array  120  may be kept at different temperatures. Similarly, it may be desirable in some cases to have two or more reaction heaters  108 , each reaction heater  108  providing energy for one or more reactors  10  in array  120  so that there are blocks of reactors  10  operating at different reaction temperatures. 
     D. Process of Evaporating and Reacting in an Array of Reactors 
     The process of vaporizing liquid feed and reacting the resulting vapor in the presence of catalyst  24  within each reactor  10  of array  120  is similar to the process for an individual reactor  10 . The process includes the steps of introducing liquid feed to a plurality of reactors  10 , heating the liquid feed within each reactor  10 , vaporizing the heated liquid feed within each reactor  10  to form a vapor and contacting, at predetermined reaction conditions, the vapor with catalyst  24  in each reactor  10  to form a product. 
     The liquid feed is introduced to each evaporation zone  18  in array  120  simultaneously through injectors  48  so that reactors  10  of array  120  are operating in parallel. The liquid feed in each reactor  10  is contacted with packing  76  and then heated within each reactor  10  until it is vaporized within evaporation zones  18 . Evaporator heater  20  provides the heat for each reactor  10  in array  120  so that the liquid feed in each bed  78  reaches its bubble point very soon after it is injected into bed  78 . 
     The vapor in each reactor  10  then passes into receptacle  22  of each reactor  10  through fluid permeable member  80 . As with individual reactor  10 , a gas feed may be introduced in some cases and contacted with catalyst  24  and vapor to react and form a product gas. 
     After passing through fluid permeable member  80  and into reaction zone  26  of each reactor  10 , the vapor and the gas feed, if present, are heated to a predetermined temperature by reaction heater  108 . A single reaction heater  108  may be used to provide the heat necessary to maintain a predetermined temperature within each of the reaction zones  26 , or multiple reaction heaters  108  may be used to heat individual reaction zones  26 , or blocks of reaction zones  26 . 
     The temperature of catalyst  24  in each reaction zone  26  is constantly measured with a thermocouple  54 . This temperature is then used to control the setting of reaction heater  108  of array  120 , or of the individual corresponding heater for that particular reaction zone  26 , or block of reaction zones  26  as described above. 
     After being heated to a predetermined temperature, the vapor, the gas feed and catalyst  24  are contacted in each reaction zone  26  of each reactor  10  in array  120  so that they react and form a product mixture of a product gas, byproducts and unreacted feeds. The product mixture then exits from each of the reactors  10  through a corresponding product conduit  40 . As with a single reactor  10 , each of the product mixtures may be diluted with a diluent gas that is mixed with the product mixtures in a corresponding mixing zone  110  after the product has been formed in each of the reaction zones  26 . 
     It is preferred that the chemical composition of the liquid feed, the gas feed and the diluent gas be known and that the liquid feed, the gas feed and the diluent gas be introduced to each reactor  10  of array  120  in measured. 
     At least a portion of each of the product mixtures is sampled and analyzed by a corresponding analyzer  112  to determine its chemical composition so that the activity, feed conversion, major product and byproduct selectivities and yields for each catalyst  24  may be calculated. 
     Several advantages of the present invention are apparent. Reactor  10  is versatile because it accommodates feeds of different phases. Liquid and gaseous feed may be introduced to reactor  10 , the liquid feed evaporated, the resulting vapor mixed with the gaseous feed, and the mixture reacted, all within reactor  10 . Reactor  10  is particularly useful in the evaluation of a catalyst for a reaction of interest because of its ease of assembly and disassembly the inventive use of seals within reactor  10  provides for the easy to assemble reactor while at the same time the design allows a liquid feed to be vaporized before being contacted with a catalyst, without compromising the seals. Reactor  10  can also be placed into an array of reactors and operated in parallel so that several catalysts may be evaluated simultaneously, greatly reducing the time required to evaluate catalysts for a particular application. 
     The present invention should not be limited to the above-described embodiments, but should be limited solely by the following claims.