Abstract:
The present invention provides a system, comprising at least one reactor array, comprising at least two reactor vessels ( 2 ) a connecting member for fixating the at least two reactor vessels relative to each other ( 4, 5 ) at least one reactor block ( 18 ) comprising a heating block ( 20 ) for heating the reactor vessels ( 2 ) the heating block ( 20 ) comprising at least two reactor channels for receiving the at least two reactor vessels ( 2 ) wherein the heating block ( 20 ) is constructed of a material having a thermal expansion coefficient &lt;=1×10e−5 K-I (at 293K). In an embodiment the heating block is substantially entirely constructed of graphite.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the National Stage of International Application No. PCT/NL2007/000162, filed Jun. 27, 2007, the contents of which is incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a system, a heating block and a method for using the system. 
       BACKGROUND OF THE INVENTION 
       [0003]    WO-02/053278 provides a system comprising multiple reactor vessels arranged in an array. The reactor vessels operate in parallel. The reactor is suitable for performing different reactions simultaneously. The reactor vessel array is placed in a temperature controlled block for controlling the temperature of the reactor vessels, for instance for heating the vessels. After finalizing a reaction, the reactor vessel array may be removed from the temperature controlled block and replaced with another reactor vessel array for performing subsequent reactions. 
         [0004]    Although the above-mentioned system is beneficial for performing multiple reactions subsequently, the reactor vessel array may become stuck in the temperature controlled block upon raising the temperature. The system including the reactor vessel array must be cooled to be able to remove the reactor vessel array from the temperature controlled block. Cooling the system, removing and replacing the reactor vessel array, and subsequently heating the replaced reactor vessel array increases the time necessary to perform subsequent reactions. 
         [0005]    All currently available systems comprising multiple reactor vessels arranged in an array pose the above-mentioned problem. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention aims to obviate the need to cool the system between subsequent reactions. 
         [0007]    The invention therefore provides a system, comprising: 
         [0008]    at least one reactor array, comprising:
       at least two reactor vessels;   a connecting member for fixating the at least two reactor vessels relative to each other;       
 
         [0011]    at least one reactor block, comprising a heating block for heating the reactor vessels, the heating block comprising at least two reactor channels for receiving the at least two reactor vessels, 
         [0012]    wherein the heating block is constructed of a material having a thermal expansion coefficient &lt;1×10e−5 K-1 (at 293K). 
         [0013]    The system of the invention enables to replace the reactor vessel array for another reactor vessel array at elevated temperatures. Elevated temperatures include for instance temperatures up to 550, 900, or 1200 degree C. The system of the invention obviates cooling and heating between subsequent reactions. The system according to the present invention decreases the time needed to perform subsequent reactions. 
         [0014]    All currently available heating blocks consist of a metal, mostly aluminum or silver. The reactor vessels are arranged in openings in the heating block at room temperature. When the heating block is subsequently heated, for instance to temperatures above 200 degree C., the metal of the heating block expands. The heating block expands to such an extent that the reactor vessels become wedged within the heating block and cannot be removed. Upon heating the heating block to a temperature of for instance 250 to about 300 degree C., the reactor vessels become stuck in the heating block. 
         [0015]    When using the system of the invention, the reactor vessels can be removed from the heating block and replaced with another array of reactor vessels, even at temperatures above 300 degree C. 
         [0016]    The use of an array of reactor vessels provides considerable advantages over the use of a single reactor vessel. The array of reactor vessels comprises at least two reactor vessels. The array may comprise any number of reactor vessels. An array of reactor vessels may be provided with a single gas connection for all reactor vessels of the array. The use of only a few connectors, for instance two screws and bolts, may already be sufficient to provide a gas or fluid tight closure of all the reactor vessels of the array. When using singular reactor vessels, each reactor vessel should be provided with a separate gas connection, and separate connectors. The use of arrays of reactor vessels considerably reduces the time needed to perform tests. 
         [0017]    In an embodiment, the material of the heating block is non-metallic. The inventors found that the problem of the prior art systems is caused by the expanding metal of the prior art heating blocks. Surprisingly, all presently available heating blocks are constructed of metal, mostly aluminum or silver. The non-metallic heating block of the invention prevents wedging of the reactor vessels due to decreased thermal expansion of the heating block. 
         [0018]    In another embodiment the material comprises graphite. Graphite is light weight, relatively inexpensive, and easy to machine. 
         [0019]    In a further embodiment the material comprises ceramic. Ceramic is readily available, and is less expensive than a metal such as silver. The linear thermal expansion coefficient of a ceramic such as titanium dioxide is about 8.2×10 −6  K −1  at 293K. 
         [0020]    In an embodiment, the heating block comprises a graphite block that is substantially entirely comprised of graphite. Graphite has a thermal expansion coefficient that is considerably lower than the thermal expansion coefficient of the material used in existing heating blocks. Silver, copper and aluminum are the most common materials for heating blocks. The thermal expansion coefficient alpha of graphite is about 7.8×10 −6  K −1  at 293K and about 8.9×10 −6  K −1  at 500K. 
         [0021]    In contrast, the linear thermal expansion coefficient alpha of aluminum is about 24×10 −6  K −1  (at 293K). The linear thermal expansion coefficient of copper is about 18×10 −6  K −1  (at 293K) and the linear thermal expansion coefficient alpha of silver is about 18×10 −6  K −1  (at 293K). 
         [0022]    The crystal structure of graphite comprises carbon molecules that are arranged in planes forming layers. In one embodiment the planes of the layers of the graphite extend in a length and a width direction of the heating block, i.e. perpendicular to the reactor channels. This is the preferred embodiment used in combination with pressurized reactor vessels, due to the improved transportation of heat along the layers of the graphite towards the reactor vessels. During the reactions, the reactor vessels of pressurized reactors are sealed and pressurized. 
         [0023]    In another embodiment, planes of layers of the graphite extend in a height direction of the heating block, i.e. parallel to the reactor channels and the reactor vessels. This is the preferred embodiment used in flow reactors, wherein during the reactions the reactor vessels are open and are continuously fed with a reaction fluid. An additional advantage of this embodiment, contrary to metal heating blocks, is the improved heat distribution over the length of the reaction vessel. The latter is due to the higher thermal conductivity of the graphite along the planes of the layers, i.e., about 250 W/(m.K) at 273K along the planes of the layers, contrary to about 80 W/(m.K) at 273K in a direction perpendicular to the layers. 
         [0024]    According to another aspect, the present invention provides a heating block suitable for a system as described above. 
         [0025]    According to still another aspect, the present invention provides a method of using a system as described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    Additional features and advantages appear from the enclosed drawings, wherein: 
           [0027]      FIG. 1  shows a perspective view of a first embodiment of a system according to of the present invention; 
           [0028]      FIG. 2  shows a perspective view of the heating block of the system of  FIG. 1 ; 
           [0029]      FIG. 3  shows a schematic side view of the first embodiment of the system of the present invention; 
           [0030]      FIG. 4  shows a perspective view of a second embodiment of the system of the present invention; 
           [0031]      FIG. 5  shows a schematic side view of the system of  FIG. 4 ; 
           [0032]      FIG. 6  shows a schematic side view of a reactor vessel of the system of  FIG. 4 ; and 
           [0033]      FIG. 7  shows a schematic side view of the heating block and a reactor vessel array of the system of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0034]      FIG. 1  shows a system  1  according to the present invention. The system  1  comprises a number of reactor vessels  2 . The reactor vessels are arranged in a reactor array of, for instance, 3×4 reactor vessels  2 . The reactor vessels  2  are at one end fixated in a connecting member, comprising for instance support plate  4  and closure plate  5 . The connecting member is provided with suitable fixing means  6 . Such fixing means are for instance described in WO-02/053278, which is in this respect incorporated by reference. The fixing means include for instance threaded openings, bolts and/or nuts. The closure plate  5  covers the support plate  4 . The closure plate  5  functions for instance as a gas manifold, as a pressure plate, etc. 
         [0035]    The reactor vessels  2  have an open end  30  and a closed end  32  ( FIG. 3 ). In  FIG. 1 , the open end is the top end of the reactor vessels, and the closed end is the bottom end. In use, the closure plate  5  closes the open end  30 . Preferably the connection between the closure plate  5  and the support plate  4  provides a gas and/or fluid tight closure of the reactor vessels  2 . 
         [0036]    The closure plate  5  is for instance provided with conduits  7 ,  8  and/or valve  12 . The conduits  10 ,  14  are provided with suitable connectors. Tube  16  is the exit of a spring relief valve. 
         [0037]    The system further comprises a reactor block  18  comprising various layers ( FIG. 3 ) having desired characteristics. Reactor channels  24  for receiving the reactor vessels  2  are provided in the various layers of the reactor block. For instance, the closed ends  32  of reactor vessels  2  are arranged in the reactor channels  24  of heating block  20  ( FIG. 2 ). The heating block  20  comprises a graphite block  22 . Preferably, the graphite block is substantially entirely comprised of graphite. The graphite block  22  is relatively flat, i.e. the height h thereof is relatively small compared to its length  1  and width w. 
         [0038]    One or more heating channels  26  are arranged in the heating block  20 . The heating channels  26  extend in the direction of the length and/or the width of the heating block  20 . One or more sensor channels  28  are arranged in the heating block. The sensor channels extend in the direction of the length and/or the width of the heating block  20 . 
         [0039]    Other arrangements of the respective channels are also conceivable. The reactor vessel, heating and/or sensor channels may for instance extend through the entire block  22 . On the other hand, the respective channels may be blind holes, i.e. closed on one end. 
         [0040]    The reactor channels  24  are cylinder shaped. The reactor channels have a diameter that corresponds to the outer diameter of the cylinder shaped reactor vessels  2 . 
         [0041]    As shown in  FIG. 3 , a magnetic stirring rod  36  is provided in the reactor vessels  2 . In the vicinity of the reactor vessels, pairs of controllable magnets (not shown) are arranged. Four magnets are for instance provided in a square, at opposite sides of the closed ends  32  of the reactor vessels  2 . Changing the polarity of the magnets in a controlled fashion will cause the stirring rods  36  to rotate and stir the contents of the respective reactor vessels. 
         [0042]    The open ends  30  of the reactor vessels are provided with flanges  38 . The support plate  4  is provided with openings  40  having a shape that corresponds to the outer shape of the reactor vessels and the flanges. 
         [0043]    The reactor block  18  comprises for instance a cooling layer  42  and/or an insulating layer  44  that are arranged between the support plate  4  and the heating block  20 . The cooling layer  42  and the insulating layer  44  comprise suitable materials for their respective functions, i.e. cooling and insulation. However, if other reactions should be carried out, the cooling layer  42  and/or insulation layer  44  may be omitted and/or changed into other layers that are suitable for the respective reactions. 
         [0044]    Various reactions may be performed using the system  1 . The closure plate  5  seals the open end of the reactor vessels  2 . The magnetic stirring rods  36  are controlled to rotate as desired to stir the contents of the reactor vessels ( FIG. 3 ). Heating elements (not shown) are introduced in the heating channels  26  and thermal sensors are introduced in the sensor channels  28 . The heating elements preferably comprise a metal strip, which is connected to an electrical power source for heating the metal strip. The heated metal strips of the heating elements will heat the graphite block  20 . The graphite subsequently conducts the heat to the reactor vessels  2 . 
         [0045]    To improve the heat conduction towards the reactor vessels  2 , the heating block of the pressurized reactor  1  preferably comprises a graphite block  22 . Planes of layers of the graphite may extend in the length and width direction of the heating block. As mentioned above, the heat conduction of graphite along the planes of the layers thereof is about three times higher than in a direction perpendicular to the planes of the layers. The planes of the graphite preferably have a configuration that is most suitable for the respective type of reactor or reaction. 
         [0046]    Multiple reactor units, i.e. two, three or more, can be arranged adjacent to each other. Thus, the number of reactions that can be carried out simultaneously may be increased. The maximum number of simultaneous reactions is determined by the total number of reactor vessels. 
         [0047]    In another embodiment ( FIGS. 4 ,  5 ) the system  100  of the invention comprises a reactor array  101  comprising one, two or more reactor vessels  102 . The reactor vessel array  101  comprises for instance a row of eight reactor vessels  102 . Multiple rows of reactor vessels may be arranged adjacent to each other. 
         [0048]    The reactor vessels  102  are at one end fixated in a connecting member, comprising for instance support plate  104  and connecting plate  105 . The connecting member is provided with suitable fixing means  106 ,  107 . Such fixing means are for instance described in WO-02/053278, which is in this respect incorporated by reference. The fixing means include for instance threaded openings, bolts and/or nuts. The connecting plate  105  covers the support plate  4 . The connecting plate  105  is for instance provided with openings  108  that are aligned with the reactor vessels for inputting fluid or gas. 
         [0049]    The support plate  104  is at its opposite ends supported by elongated beams  110 ,  112  of a guiding structure ( FIGS. 4 ,  5 ). The beams  110 ,  112  are provided with grooves  114 ,  116  for slidably guiding extending cams  117  of the support plate  104 . 
         [0050]    The reactor vessels  102  are arranged in corresponding reactor channels  124  in a reactor block  118 , comprising heating block  120 . Corresponding herein indicates a shape that corresponds to the outer shape of the reactor vessels  102 . The heating block  120  may provide a relatively tight fit to the reactor vessels  102 , to improve heat conduction. 
         [0051]    The heating block  120  preferably comprises a graphite block. Planes of layers of the graphite may extend along the length of the reactor vessels  102 , i.e. in the height direction of the heating block  120  to improve the heat distribution along the reactor vessels. 
         [0052]    The reactor vessels  102  comprise cylinders  174  having an open end  176  and a fluid and/or gas permeable end  178  ( FIG. 6 ). Along a certain length, the cylinders  174  may be provided with outer cylinders  180  ( FIG. 7 ), i.e. the reactor vessels  102  may at least partly comprise a double wall. 
         [0053]    Reaction fluid may be introduced into the reactor vessels  102  via conduits  181  through the open ends  176 . The fluid and/or gas permeable end  178  is in fluid/gas communication with a fluid/gas conduit  182  for draining reaction products away from the reactor vessels. The fluid permeable end  178  may be provided with means, such as a filter or a mesh  184  ( FIG. 6 ), for retaining catalyst  190 . In an embodiment, cylinder  174 , conduit  181  and conduit  182  are formed as a single tube. 
         [0054]    In use, the ends  176  of the reactor vessels  102  ( FIG. 6 ) are continuously supplied with a reaction fluid. The heating block  120  is heated, substantially corresponding to the heating of the heating block  20  of  FIG. 1 . 
         [0055]    The reactor  100  of  FIGS. 4-7  is denominated as a continuous flow reactor. As the catalyst  190  remains in the reactor vessels, exchange of the reactor vessels is obviated and the fit of the reactor vessels in the reactor channels  124  may be relatively tight. 
         [0056]    Known continuous flow reactors comprise a heating block made of a metal, mostly silver or chromium. Silver and chromium are suitable for relatively high temperatures, up to 600 degree C. (silver) or 900 degree C. (chromium). However, the reactor vessels, and hence also the reactor channels, may differ for different kinds of reactions. The latter is especially true when performing reactions, i.e. tests, on demand, for instance for clients. The need for different reactor channels for a certain test requires the construction of a new heating block for the respective test. The construction of a new heating block made of silver or chromium is however time consuming and expensive. 
         [0057]    The heating block  120  according to the present invention comprises for instance a graphite block. Construction of the graphite block is relatively fast and inexpensive. Machining the graphite block comprises cutting off a flat block of graphite and machining the respective openings therein. Heating elements for heating the heating block may be introduced in heating channels of the heating block. 
         [0058]    The graphite is able to withstand high temperatures, for instance up to about 550, 900, or up to 1200 degree C. The heating block according to the present invention will provide a cost reduction when carrying out different reactions, and enable a wide temperature range. 
         [0059]    The system of the present invention is for instance applicable in a laboratory setup. The system enables chemical scientists to screen a multitude of, for instance  96 , batch reactions in parallel. The reactions may be performed on a scale of about 1 ml. The system is suitable for chemical process development and/or catalysis research. 
         [0060]    The system allows investigating the effect of catalysts, solvents, temperature, and/or pressure for a broad range of batch chemistries. The chemical reactions may include, but are not limited to hydrogenations, oxidations, hydroformylations, carbonylations, coupling reactions and polymerizations. The system of the present invention is easy to use and requires only a small amount of precious starting material. 
         [0061]    The present invention is not limited to the above described embodiments thereof; many modifications are imaginable within the scope of the enclosed claims.