Abstract:
Processes for thermal conversion of biomass are provided. The processes involve upgrading the pyrolysis vapor from a pyrolysis reactor. The steps include thermally converting a biomass feedstock in a pyrolysis reactor, recovering a pyrolysis vapor from the reactor, passing the pyrolysis vapor in contact with a cracking catalyst, a water-gas shift reaction catalyst, a hydrotreating catalyst, and an acid catalyst, and converting the resulting upgraded pyrolysis vapor into a liquid product. The resulting biooil liquid product is more refined, and the overall processes offer economic and energy efficiency.

Description:
TECHNICAL FIELD 
       [0001]    The present application relates to a process of upgrading biomass pyrolysis vapor. More specifically, the present application relates to a process of in-situ upgrading of biomass pyrolysis vapor using a multi-layer catalyst bed or a cascade of catalytic reactors. 
       BACKGROUND 
       [0002]    With the diminishing supply of fossil fuels, the use of renewable energy sources is becoming increasingly important as a feedstock for production of hydrocarbon compounds. Thermal conversion of carbonaceous materials, such as biomass and waste, can play an important role to provide materials that can replace fossil fuels. These conversions can be accomplished by pyrolysis processes. 
         [0003]    Pyrolysis is one of two major pathways for converting biomass into fuels or chemicals in a thermochemical platform. The major product from a common fast pyrolysis process is called biocrude or biooil, a dark brown liquid that generally is acidic and has high oxygen and water content, which are characteristics that are usually not favored by existing refinery equipment or processes used for further processing to transportation fuels. For instance, the oxygen content could be 50 weight percent (wt %) or higher in biooil, thus requiring a high amount of hydrogen to upgrade the biooil into hydrocarbon fuels via hydroprocessing, which makes the process economically unattractive. In addition, the acidity of biooil causes the biooil to be corrosive to existing pipelines. Moreover, the water content is typically 20 to 30 wt % and the biooil is immiscible with petroleum crude, which makes co-refining difficult. Therefore, biooils with improved properties, such as with less oxygen, less water, and close to neutral pH, would be preferred. 
         [0004]    Currently, most research on improving the properties of biooil has been focused on post-pyrolysis treatment involving upgrading the liquid biooil obtained from fast pyrolysis with hydroprocessing or hydrotreating, and other reactions like esterification. However, little or no effort has been put into in situ catalytic upgrading of pyrolysis vapor before it is condensed into liquid. For example, one common biooil upgrading method is to first separate it into two phases (aqueous and lignin phase), and then use the pyrolytic lignin phase (or organic phase) for hydroprocessing, while the aqueous phase is passed onto steam-reforming to generate the hydrogen required by the hydroprocessing. Although this approach may work, one distinct disadvantage is that both the aqueous and lignin phases have to be reheated up to high temperatures for steam reforming and hydroprocessing, which would require extra heat or energy, thus considerably reducing the overall thermal efficiency of the process. 
         [0005]    Biomass-derived pyrolysis oil has the potential to replace up to 60 percent (%) of transportation fuels, thereby reducing the dependency on conventional petroleum and reducing its environmental impact. Therefore, there is a need in the industry for a process that is more economical and energy efficient for converting biomass to fuels. 
       SUMMARY 
       [0006]    The present invention provides a process for in-situ upgrading of biomass pyrolysis vapor using a multi-layered catalyst bed or cascaded catalytic reactors. In one aspect, the present process for the thermal conversion of biomass comprises the steps of a) thermal conversion of a biomass feedstock in a pyrolysis reactor, b) recovering a pyrolysis vapor from the reactor, c) passing the pyrolysis vapor in contact with a cracking catalyst, a water-gas shift reaction catalyst, a hydrotreating catalyst, and an acid catalyst, and d) converting the resulting pyrolysis vapor from step c) into a liquid product. 
         [0007]    In one other aspect, the present process for the thermal conversion of biomass comprises the steps of a) thermal conversion of a biomass feedstock in a pyrolysis reactor, b) recovering a pyrolysis vapor from the reactor, c) passing the pyrolysis vapor in contact with an acid catalyst in the presence of an alcohol, and d) converting the resulting pyrolysis vapor from step c) into a liquid product. 
         [0008]    In another aspect, the present process for the thermal conversion of biomass comprises the steps of a) thermal conversion of a biomass feedstock in a pyrolysis reactor, b) recovering a pyrolysis vapor from the reactor, c) passing the pyrolysis vapor in contact with a water-gas shift reaction catalyst and a hydrotreating catalyst, and d) converting the resulting pyrolysis vapor from step c) into a liquid product. 
         [0009]    In yet another aspect, the present process for the thermal conversion of biomass comprises the steps of a) thermal conversion of a biomass feedstock in a pyrolysis reactor, b) recovering a pyrolysis vapor from the reactor, c) passing the pyrolysis vapor in contact with a cracking catalyst, a water-gas shift reaction catalyst, and a hydrotreating catalyst, and d) converting the resulting pyrolysis vapor from step c) into a liquid product. 
         [0010]    Among other factors, it has been found that by in-situ upgrading the biomass pyrolysis vapor using the series of catalysts of the present processes, a liquid biooil product is obtained that is so refined that the liquid product can be combined with crude oil to make gasoline. In addition, it has been found that by in-situ upgrading the biomass pyrolysis vapor to have less acidity, one can attain a liquid biooil product which is easier to handle and less corrosive in post-pyrolysis treatment. It has also been found that in-situ upgrading of hot pyrolysis vapor is more attractive and economical, as biooil with improved properties, such as less oxygen and/or less acidity, is produced directly. This makes the further upgrading into liquid transportation fuels more cost effective due to less hydrogen being required. Energy is also saved for pyrolysis vapor cooling and pyrolysis oil reheating. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    For a more complete understanding of the exemplary embodiments of the present invention and the advantages thereof, reference is now made to the following description in conjunction with the accompanying drawings, which are briefly described as follows. 
           [0012]      FIG. 1  is a schematic of a process for in-situ upgrading of pyrolysis vapor using a multi-layered catalyst bed, with multiple layers of the different catalysts, according to an exemplary embodiment. 
           [0013]      FIG. 2  is a schematic of a process for in-situ upgrading of pyrolysis vapor using cascaded catalyst reactors (or beds), according to an exemplary embodiment. 
           [0014]      FIG. 3  is a schematic of a process for in-situ upgrading of pyrolysis vapor using an acid catalyst in the presence of alcohol, according to an exemplary embodiment. 
           [0015]      FIG. 4  is a schematic of a process for in-situ upgrading of pyrolysis vapor using a water-gas shift reaction catalyst and a hydrotreating catalyst, with multiple layers of the different catalysts, according to an exemplary embodiment. 
           [0016]      FIG. 5  is a schematic of a process for in-situ upgrading of pyrolysis vapor using a water-gas shift reaction catalyst and a hydrotreating catalyst, using cascaded catalyst reactors (or beds), according to an exemplary embodiment. 
           [0017]      FIG. 6  is a schematic of a process for in-situ upgrading of pyrolysis vapor using a cracking catalyst, a water-gas shift reaction catalyst, and a hydrotreating catalyst, with multiple layers of the different catalysts, according to an exemplary embodiment. 
           [0018]      FIG. 7  is a schematic of a process for in-situ upgrading of pyrolysis vapor using a cracking catalyst, a water-gas shift reaction catalyst, and a hydrotreating catalyst, using cascaded catalyst reactors (or beds), according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. One of ordinary skill in the art will appreciate that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
         [0020]    The present invention may be better understood by reading the following description of non-limitative embodiments with reference to the attached drawings wherein like parts of each of the figures are identified by the same reference characters. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, for example, a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, for example, a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase. Moreover, various streams or conditions may be referred to with terms such as “hot,” “cold,” “cooled, “warm,” etc., or other like terminology. Those skilled in the art will recognize that such terms reflect conditions relative to another process stream, not an absolute measurement of any particular temperature. 
         [0021]    The present application is directed to an improved biomass pyrolysis process that performs in-situ upgrading of pyrolysis-vapor using different catalysts. Specifically, a catalyst bed with multi-layered catalysts or cascaded catalytic reactors with different catalysts are implemented in a regular fast pyrolysis unit. The biooil produced this way will have improved properties, for instance, lower oxygen content and/or less acidity, over biooils produced from regular fast pyrolysis. The present application is also directed to systems for implementing such processes. 
         [0022]    Referring to  FIG. 1 , a process  100  for in-situ upgrading of pyrolysis vapor using a multi-layered catalyst bed reactor  102  is illustrated. A biomass stream  104  and a recycled off-gas stream  106  are fed into a fluid bed pyrolysis reactor  108 . In certain exemplary embodiments, the recycled off-gas stream  106  includes nitrogen (N 2 ). The recycled off gas stream  106  fluidizes the bed in the pyrolysis reactor  108 . In certain exemplary embodiments, the biomass stream  104  includes wood sawdust, bark, yard waste, waste lumber, agricultural wastes, peat, paper mill wastes, cellulosic wastes, municipal solid waste, food processing wastes, sewage sludge, and the like. In certain embodiments, the biomass stream  104  can be dried prior to entering the fluid bed pyrolysis reactor  108 . In certain exemplary embodiments, the biomass stream  104  is dried to less than 10 wt % moisture content. In certain exemplary embodiments, the biomass stream  104  is ground to form small particles, for instance, less than 3 millimeters (mm) in its shortest dimension. 
         [0023]    The pyrolysis reactor  108  is any reactor type capable of completing a pyrolysis reaction involving thermal decomposition of the biomass stream  104  at short reaction times. The pyrolysis reaction is sometimes called “fast”, “flash”, or “rapid” pyrolysis. The reaction is conducted in a reactor type capable of high heat transfer rates to small biomass particles, in order to achieve the rapid increase in temperature of the particle that is necessary. Suitable examples of pyrolysis reactors include, but are not limited to, fluidized bed reactors, circulating fluidized bed reactors, and transport reactors. In fluidized bed reactors and circulating fluidized bed reactors, hot gases and solids are brought into intimate contact with the biomass particles in the biomass stream  104 . In certain exemplary embodiments, the solids are normally inert, for instance, silica or sand. In transport reactors, either hot gas alone or a mixture of hot gas and solids may be used. All reactors generally require a significant recycled off-gas flow, usually from about 1 to about 10 times the weight of biomass stream  104  being processed. If the pyrolysis reaction is carried out in the absence of oxygen, for example, in a nitrogen atmosphere, then the non-condensable gases formed have significant contents of carbon monoxide, hydrogen, methane and other light hydrocarbons or organics, which can be burned. The pyrolysis reactor  108  is generally operated at conditions which promote maximum yield of organic liquid. In certain exemplary embodiments, the pyrolysis reactor  108  is operated at a temperature in the range of from about 400 degrees Celsius (° C.) to about 650° C., a vapor residence time of less than about 2 seconds, and at substantially atmospheric pressure. Generally, the pyrolysis reaction yields a pyrolysis vapor stream  110  that exits a top  108   a  of the pyrolysis reactor  108 . 
         [0024]    Once the pyrolysis on the biomass stream  104  is complete, the pyrolysis vapor stream  110  is often passed through separation devices, such as filters or cyclones, in order to remove any entrained solid particles, or char,  112   a ,  112   b , resulting from the pyrolysis reaction. In certain exemplary embodiments, the pyrolysis vapor stream  110  enters a first cyclone reactor  114  to separate pyrolysis vapors from entrained char. A pyrolysis vapor stream  116  exits the first cyclone reactor  114  and enters a second cyclone reactor  118  to further separate pyrolysis vapors from entrained char. A pyrolysis vapor stream  120  exits the second cyclone reactor  118  and is introduced at a top  102   a  of the multi-layered catalyst bed reactor  102 . In certain exemplary embodiments, the pyrolysis vapor stream  120  is substantially free of particles so as not to plug the catalyst bed reactor  102 . 
         [0025]    The catalyst bed reactor  102  includes multiple layers of the different catalysts. The pyrolysis vapor stream  120  passes through each catalyst bed, in sequence from the top  102   a  to a bottom  102   b , in the multi-layer catalyst bed reactor  102 . The selection and proper combination of different catalysts is important, as it determines the performance of the catalytic treatment of the pyrolysis vapor stream  120 . 
         [0026]    In certain exemplary embodiments, a top catalyst  102   c  would be a zeolite type cracking catalyst, preferably HZSM-5, as this catalyst can be operated at a temperature between about 370 and about 410° C., at atmospheric pressure. The cracking catalyst will crack the hydrocarbon in the pyrolysis vapor stream  120 . Suitable examples of other zeolite cracking catalysts for use include, but are not limited to, REX, REY, and USY zeolites. Any suitable temperature and pressure can be used, based upon the degree of cracking desired. Some zeolite type catalysts, such HZSM-5, are prone to coke or char formation on the catalyst. The extent of the coking can be controlled by the relative space velocity of the pyrolysis vapor stream in the catalyst bed. Other cracking catalysts, for example those used in catalytic crackers (for instance fluid catalytic cracking units), may be less prone to coking relative to zeolites. Other types of catalysts, such as alumina based catalysts, can be used as cracking catalysts and will have lower coking tendencies. 
         [0027]    In certain exemplary embodiments, a middle catalyst  102   d  would be a high temperature water-gas-shift catalyst, for example, a precious metal catalyst such as platinum (Pt)/mixed oxide, which are good for operating in the temperature range of from about 350 to about 450° C. The purpose of using a shift catalyst is to convert the water and carbon monoxide (CO) in the pyrolysis vapor stream  120  into hydrogen (H 2 ) and carbon dioxide (CO 2 ), thus providing the hydrogen required by hydrodeoxygenation or hydrotreating. The water-gas shift reaction catalysts generally include a transition metal or transition metal oxide. In certain exemplary embodiments, precious metal catalysts, such as platinum in a mixed oxide, are utilized for operating in a temperature range of from about 350 to about 450° C. The hydrogen is then available for the hydrotreating or hydrodeoxygenation. The relative space velocity of the hot vapor stream through the bed can be designed and controlled to produce the maximum amount of hydrogen. The limiting factor will be the amount of carbon monoxide present in the pyrolysis vapor stream. Since water-gas shift is an equilibrium process, injection of additional hot water vapor before this catalyst would drive the conversion of all of the carbon monoxide into carbon dioxide and produce more hydrogen. 
         [0028]    A third catalyst  102   e  would include a hydrotreating (or hydrodeoxygenation) catalyst. Suitable examples of hydrotreating or hydrodeoxygenation catalysts include, but are not limited to, any known nickel molybdenum (NiMo), cobalt molybdenum (CoMo), or noble metal catalyst supported on γ-alumina. Generally, such catalysts are commercially available. In certain exemplary embodiments, the reaction is generally run at a temperature in the range from about 350 to about 450° C., at atmospheric pressure. The hydrotreating removes the oxygen containing-hydrocarbons in the pyrolysis vapor. 
         [0029]    In certain exemplary embodiments, a solid acid catalyst  102   f , such as sulfated zirconia, zeolite β, or Nafion-silicone disoxide (SiO 2 ) composite (SAC-13), can be added to the very bottom  102   b  of the catalyst bed reactor  102  with an injection of an alcohol stream  124  to perform an esterification process. The alcohol stream  124  can include methanol or ethanol, and can be injected into the catalyst  102   f  bed, catalyst bed reactor  102 , or pyrolysis vapor stream  120  to support the esterification reaction. The purpose of using the catalyst  102   f  is to reduce the acidity of pyrolysis vapor stream  120  by letting the carboxylic acid (e.g., acetic acid) in the pyrolysis vapor stream  120  react with the alcohol stream  124  to form ester and water. An upgraded pyrolysis vapor stream  130  is removed from the bottom  102   b  of the catalyst bed reactor  102  and directed to a quench tower  134 . The pyrolysis vapor stream  130  is generally less acidic and safer for transport through pipes and equipment. 
         [0030]    The order in which the pyrolysis vapor stream  120  contacts the foregoing catalysts can be any order. In certain exemplary embodiments, the water-gas shift catalyst is generally contacted prior to the hydrotreating catalyst so that the water-gas shift reaction can produce hydrogen, which can be used in the hydrotreating reaction, and thereby make the process more efficient. In one embodiment, the cracking catalyst is contacted first, followed by the water-gas shift catalyst, hydrotreating catalyst, and then the acid catalyst. In another embodiment, the water-gas shift catalyst is contacted first, followed by the hydrotreating catalyst, the acid catalyst, and then the cracking catalyst. 
         [0031]    The pyrolysis vapor stream  130  is quenched and converted into a liquid biooil product  140 , and collected at a base  136  of the quench tower  134 . A portion  140   a  of the biooil product  140  is collected in a biooil collection tank  144 , while a portion  140   b  can be pumped via pump  146  through a heat exchanger  148  to produce a cooled biooil stream  150 . In certain exemplary embodiments, the cooled biooil stream  150  is reintroduced at a top  134   a  of the quench tower  134  to quench the pyrolysis vapor stream  130 . 
         [0032]    In certain exemplary embodiments, a biooil vapor stream  154  from the quench tower  134  is directed to a condenser  156  to cool and condense the biooil vapor stream  154  to produce a condensed biooil stream  158  and a non-condensable gas stream  160 . In certain exemplary embodiments, the condensed biooil stream  158  is routed to the biooil collection tank  144 . The biooil collected in tank  144  generally has an oxygen content in the range of from about 30 to about 40 percent (%) (dry, ash free basis) and a water content in the range of from about 15 to about 25%, depending on the operating temperatures of the quench tower and the condensers. The biooil product is generally phase stable and which may separate from a lighter density, more water rich product phase. Typical pH values for the biooil product are in the range of from about 2 to about 5. 
         [0033]      FIG. 2  illustrates a process  200  for in-situ upgrading of pyrolysis vapor, according to another exemplary embodiment. The process  200  for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process  100  for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. The process  200  utilizes cascaded catalytic reactors, each having a single type of catalyst therein. 
         [0034]    Referring now to  FIG. 2 , the pyrolysis vapor stream  120  free of particles exits the second cyclone reactor  118  and is passed through a heat exchanger  202  to control the temperature of the pyrolysis vapor stream  120  to produce a pyrolysis vapor stream  204 . The temperature of the pyrolysis vapor stream  120  is adjusted to achieve optimal conditions for catalysis. The pyrolysis vapor stream  204  is introduced into a first catalytic reactor  208 . In certain exemplary embodiments, the first catalytic reactor  208  includes a zeolite cracking catalyst therein. A pyrolysis vapor stream  210  exits the first catalytic reactor  208  and is passed through a heat exchanger  212  to control the temperature of the pyrolysis vapor stream  210  to produce a pyrolysis vapor stream  214 . The temperature of the pyrolysis vapor stream  210  is adjusted to achieve optimal conditions for catalysis. 
         [0035]    The pyrolysis vapor stream  214  is introduced into a second catalytic reactor  218 . In certain exemplary embodiments, the second catalytic reactor  218  includes a water-gas shift catalyst therein. A pyrolysis vapor stream  220  exits the second catalytic reactor  218  and is passed through a heat exchanger  222  to control the temperature of the pyrolysis vapor stream  220  to produce a pyrolysis vapor stream  224 . The temperature of the pyrolysis vapor stream  220  is adjusted to achieve optimal conditions for catalysis. 
         [0036]    The pyrolysis vapor stream  224  is introduced into a third catalytic reactor  228 . In certain exemplary embodiments, the third catalytic reactor  228  includes a hydrotreating catalyst therein. A pyrolysis vapor stream  230  exits the third catalytic reactor  228  and is passed through a heat exchanger  232  to control the temperature of the pyrolysis vapor stream  230  to produce a pyrolysis vapor stream  234 . The temperature of the pyrolysis vapor stream  230  is adjusted to achieve optimal conditions for catalysis. 
         [0037]    The pyrolysis vapor stream  234  is introduced into a fourth catalytic reactor  238 . In certain exemplary embodiments, the fourth catalytic reactor  238  includes an acid catalyst therein. The alcohol stream  124  can be injected with the pyrolysis vapor stream  234  to perform the esterification process and lower the acidity of the resulting upgraded pyrolysis vapor stream  240 . The pyrolysis vapor stream  240  exits the fourth catalytic reactor  238  and is directed to the quench tower  134 . 
         [0038]    Generally, the processes of the present invention involves thermal conversion of biomass by pyrolysis, i.e., in a pyrolysis reactor. A greatly improved liquid, biooil product is obtained by the present process as the pyrolysis vapor is upgraded. The pyrolysis vapor is contacted with a cracking catalyst, a water-gas shift reaction catalyst, a hydrotreating catalyst and an acid catalyst. This particular selection of catalysts provides an upgraded vapor that is converted into a liquid product by a means such as by quenching, thus resulting in a biooil liquid so refined that it can be combined with crude oil to give a useful gasoline product. No additional refining is necessary. Further refining, of course, can be conducted to fine tune the properties of the biooil product, depending on the ultimate product desired. 
         [0039]    The selection and proper combination of the different catalysts allows for upgrading of the pyrolysis vapor, and thereby provides the resulting refined biooil. The use of a cracking catalyst, in combination with a hydrotreating catalyst and a water-gas shift reaction catalyst, and an acid catalyst, can provide one with a liquid biooil product having reduced oxygen and water content as well as lowered acidity. In general, the pyrolysis vapor can contact the different catalysts in any order desired. The catalysts can be arranged in a multi-layer fashion, in separate reactors, or in a combination of such. 
         [0040]    Contacting the catalysts with the pyrolysis vapor stream  120  can be conducted in any suitable fashion. In certain embodiments, the contacting is conducted in a single reactor where the catalysts are situated in a multilayer fashion. The vapor contacts each catalyst in order as situated in the multilayer fashion. In other embodiments, the catalysts are arranged in separate reactors, with the pyrolysis vapor being passed in sequence through each reactor. Heat exchangers can be included in between the cascaded reactors to heat or cool the pyrolysis vapor for the appropriate temperatures required by various upgrading catalysts. In addition, it would allow for easier sampling of the upgraded vapor for analysis after each stage, thus allowing more control over the process. In such an embodiment, the temperature and pressure for each reaction can be better fine tuned to control the reaction. Also, guard beds can be placed before each reactor to filter out unwanted materials, if so desired. 
         [0041]      FIG. 3  illustrates a process  300  for in-situ upgrading of pyrolysis vapor using the acid catalyst, according to an exemplary embodiment. The process  300  for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process  100  for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. Referring now to  FIG. 3 , the pyrolysis vapor stream  120  enters a catalyst bed reactor  302 . The catalyst bed reactor  302  includes a solid acid catalyst bed  302   f  with an injection of alcohol stream  124  to perform an esterification process. An upgraded pyrolysis vapor stream  330  is removed from a bottom  302   b  of the catalyst bed reactor  302  and directed to the quench tower  134 . The pyrolysis vapor stream  330  is generally less acidic and safer for transport through pipes and equipment. 
         [0042]      FIG. 4  illustrates a process  400  for in-situ upgrading of pyrolysis vapor using a water-gas shift catalyst and a hydrotreating (or hydrodeoxygenation) catalyst, according to an exemplary embodiment. The process  400  for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process  100  for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. Referring now to  FIG. 4 , the pyrolysis vapor stream  120  enters a catalyst bed reactor  402  having a top catalyst  402   d  and a bottom catalyst  402   e . The catalyst bed reactor  402  includes multiple layers of the different catalysts. In certain exemplary embodiments, the top catalyst  402   d  is a water-gas shift catalyst. In certain exemplary embodiments, the bottom catalyst  402   e  is a hydrotreating catalyst. The pyrolysis vapor stream  120  passes through each catalyst bed, in sequence from a top  402   a  to a bottom  402   b , in the multi-layer catalyst bed reactor  402 . In certain exemplary embodiments, the water-gas shift catalyst is contacted first, followed by the hydrotreating catalyst. An upgraded pyrolysis vapor stream  430  is removed from the bottom  402   b  of the catalyst bed reactor  402  and directed to the quench tower  134 . 
         [0043]      FIG. 5  illustrates a process  500  for in-situ upgrading of pyrolysis vapor, according to another exemplary embodiment. The process  500  for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process  400  for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. The process  500  utilizes cascaded catalytic reactors, each having a single type of catalyst therein. 
         [0044]    Referring now to  FIG. 5 , the pyrolysis vapor stream  120  is passed through a heat exchanger  512  to control the temperature of the pyrolysis vapor stream  120  to produce a pyrolysis vapor stream  514 . The temperature of the pyrolysis vapor stream  120  is adjusted to achieve optimal conditions for catalysis. The pyrolysis vapor stream  514  is introduced into a first catalytic reactor  518 . In certain exemplary embodiments, the first catalytic reactor  518  includes a water-gas shift catalyst therein. A pyrolysis vapor stream  520  exits the first catalytic reactor  518  and is passed through a heat exchanger  522  to control the temperature of the pyrolysis vapor stream  520  to produce a pyrolysis vapor stream  524 . The temperature of the pyrolysis vapor stream  520  is adjusted to achieve optimal conditions for catalysis. 
         [0045]    The pyrolysis vapor stream  524  is introduced into a second catalytic reactor  528 . In certain exemplary embodiments, the second catalytic reactor  528  includes a hydrotreating catalyst therein. A pyrolysis vapor stream  530  exits the second catalytic reactor  528  and is directed to the quench tower  134 . By upgrading the pyrolysis vapor in accordance with the processes  400 ,  500 , the overall upgrading process is more thermally efficient. The heat loss due to condensation of pyrolysis vapor and the reheating of biooil is avoided. Furthermore, no hydrogen is needed, as hydrogen can be provided internally by the water-gas-shift reaction. In addition, the biooil produced from the quench tower  134  would have a lower oxygen content, lower water content, and lower acidity. 
         [0046]      FIG. 6  illustrates a process  600  for in-situ upgrading of pyrolysis vapor using a cracking catalyst, a water-gas shift catalyst, and a hydrotreating (or hydrodeoxygenation) catalyst, according to an exemplary embodiment. The process  600  for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process  100  for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. Referring now to  FIG. 6 , the pyrolysis vapor stream  120  enters a catalyst bed reactor  602  having a top catalyst  602   c , a middle catalyst  602   d , and a bottom catalyst  602   e . The catalyst bed reactor  602  includes multiple layers of the different catalysts. In certain exemplary embodiments, the top catalyst  602   c  is a cracking catalyst. In certain exemplary embodiments, the middle catalyst  602   d  is a water-gas shift catalyst. In certain exemplary embodiments, the bottom catalyst  602   e  is a hydrotreating catalyst. The pyrolysis vapor stream  120  passes through each catalyst bed, in sequence from a top  602   a  to a bottom  602   b , in the multi-layer catalyst bed reactor  602 . The order in which the pyrolysis vapor stream  120  contacts the foregoing catalysts can be any order. In certain exemplary embodiments, the water-gas shift catalyst is generally contacted prior to the hydrotreating catalyst so that the water-gas shift reaction can produce hydrogen, which can be used in the hydrotreating reaction, and thereby make the process more efficient. In one embodiment, the cracking catalyst is contacted first, followed by the water-gas shift catalyst, and then the hydrotreating catalyst. In another embodiment, the water-gas shift catalyst is contacted first, followed by the hydrotreating catalyst, and then the cracking catalyst. An upgraded pyrolysis vapor stream  630  is removed from the bottom  602   b  of the catalyst bed reactor  602  and directed to the quench tower  134 . 
         [0047]      FIG. 7  illustrates a process  700  for in-situ upgrading of pyrolysis vapor, according to another exemplary embodiment. The process  700  for in-situ upgrading of pyrolysis vapor is the same as that described above with regard to the process  600  for in-situ upgrading of pyrolysis vapor, except as specifically stated below. For the sake of brevity, the similarities will not be repeated hereinbelow. The process  700  utilizes cascaded catalytic reactors, each having a single type of catalyst therein. 
         [0048]    Referring now to  FIG. 7 , the pyrolysis vapor stream  120  is passed through a heat exchanger  702  to control the temperature of the pyrolysis vapor stream  120  to produce a pyrolysis vapor stream  704 . The temperature of the pyrolysis vapor stream  120  is adjusted to achieve optimal conditions for catalysis. The pyrolysis vapor stream  704  is introduced into a first catalytic reactor  708 . In certain exemplary embodiments, the first catalytic reactor  708  includes a zeolite cracking catalyst therein. A pyrolysis vapor stream  710  exits the first catalytic reactor  708  and is passed through a heat exchanger  712  to control the temperature of the pyrolysis vapor stream  710  to produce a pyrolysis vapor stream  714 . The temperature of the pyrolysis vapor stream  710  is adjusted to achieve optimal conditions for catalysis. 
         [0049]    The pyrolysis vapor stream  714  is introduced into a second catalytic reactor  718 . In certain exemplary embodiments, the second catalytic reactor  718  includes a water-gas shift catalyst therein. A pyrolysis vapor stream  720  exits the second catalytic reactor  718  and is passed through a heat exchanger  722  to control the temperature of the pyrolysis vapor stream  720  to produce a pyrolysis vapor stream  724 . The temperature of the pyrolysis vapor stream  720  is adjusted to achieve optimal conditions for catalysis. 
         [0050]    The pyrolysis vapor stream  724  is introduced into a third catalytic reactor  728 . In certain exemplary embodiments, the third catalytic reactor  728  includes a hydrotreating catalyst therein. A pyrolysis vapor stream  730  exits the third catalytic reactor  728  and is directed to the quench tower  134 . By upgrading the pyrolysis vapor in accordance with the processes  600 ,  700 , the overall upgrading process is more thermally efficient. The heat loss due to condensation of pyrolysis vapor and the reheating of biooil is avoided. Also, a liquid biooil product is obtained that is refined such that the product can be combined with crude oil to produce gasoline. Furthermore, no hydrogen is needed, as hydrogen can be provided internally by the water-gas shift reaction. In addition, the biooil produced from the quench tower  134  would have a lower oxygen content, lower water content, and lower acidity. 
         [0051]    By upgrading pyrolysis vapor in accordance with the processes of the present invention, the overall upgrading process is more thermally efficient than conventional processes. Heat loss due to condensation of pyrolysis vapor and reheating of biooil is avoided. Furthermore, no hydrogen (H 2 ) is needed, as hydrogen can be provided internally by the water-gas-shift reactions. In addition, the biooil produced from the quench tower has less oxygen, less water, and fewer acids than biooils produced using conventional processes, and therefore has an improved quality over conventional biooils. By treating the pyrolysis vapor in accordance with the present invention, a liquid biooil product can be obtained that is already so refined that it can be combined directly, or with minimal further refining, to crude oil to make a gasoline product. 
         [0052]    To facilitate a better understanding of the present invention, the following examples of certain aspects of some embodiments are given. In no way should the following examples be read to limit, or define, the scope of the invention. 
       EXAMPLES 
     Example 1 
       [0053]    The typical operating conditions for a multi-layer fixed-bed reactor would be:
       Catalysts used:
           Top layer—HZSM-5 (cracking catalyst);   2nd layer—Pt supported on mixed oxide (water-gas shift catalyst);   3rd layer—NiMo and CoMo Supported on γ-alumina (hydrotreating catalyst);   Bottom layer—Zeolite β (acid catalyst).   
           Pressure: Atmospheric   Temperature: 350-400° C.   Volume Ratio: Determined by space velocities required; also considering cost, generally
           Top layer:2nd layer:3rd layer:Bottom layer=5:2:3:10   
           Expected Bio-oil Quality:
           Oxygen content: &lt;10 wt %   Water content: &lt;5 wt %   pH: 5-6   
               
 
       Example 2 
       [0067]    The typical operating conditions for an acid catalyst fixed-bed reactor would be:
       Catalysts used: Zeolite β (acid catalyst).   Pressure: Atmospheric   Temperature: 350-400° C.   Expected Bio-oil Quality:
           pH: 5-6   
               
 
       Example 3 
       [0073]    The typical operating conditions for a multi-layer fixed -bed reactor would be:
       Catalysts used:
           Top layer—Pt supported on mixed oxide (water-gas shift catalyst);   2nd layer—NiMo and CoMo Supported on γ-alumina (hydrotreating catalyst);   
           Pressure: Atmospheric   Temperature: 350-400° C.   Expected Bio-oil Quality:
           Oxygen content: &lt;10 wt %   Water content: &lt;5 wt %   
               
 
       Example 4 
       [0082]    The typical operating conditions for a multi-layer fixed -bed reactor would be:
       Catalysts used:
           Top layer—HZSM-5 (cracking catalyst);   2nd layer—Pt supported on mixed oxide (water-gas shift catalyst);   3rd layer—NiMo and CoMo Supported on γ-alumina (hydrotreating catalyst).   
           Pressure: Atmospheric   Temperature: 350-400° C.   Volume Ratio: Determined by space velocities required; also considering cost, generally
           Top layer:2nd layer:3rd layer=5:2:3   
           Expected Bio-oil Quality:
           Oxygen content: &lt;10 wt %   Water content: &lt;5 wt %   
               
 
         [0094]    Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as defined by the appended claims. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention. The terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.