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MULTIPLE PARALLEL CATALYTIC
REACTOR ASSEMBLY
CROSS REFERENCE TO RELATED
APPLICATION 5
The present application is a continuation-in-part of related application U.S. application Ser. No. 09/465,213 filed Dec. 15, 1999, now U.S. Pat. No. 6,576,196 which is hereby incorporated by reference in its entirety.
FIELD OF THE INVENTION
The present invention relates to a multiple parallel catalytic reactor assembly.
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BACKGROUND OF THE INVENTION
Before a catalyst is selected for use in a commercial application, a great number of known catalysts may be contemplated for use in the envisioned application. A large number of newly synthesized catalytic compositions may 20 also 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.
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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 3Q 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: N.Y., 1984; p. 854.
The traditional approach to evaluating the activity and 35 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 40 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. 45
Developments in combinatorial chemistry have first largely concentrated on the synthesis of chemical compounds. For example, U.S. Pat. No. 5,812,002 and U.S. Pat. No. 5,766,556 disclose a method and apparatus for multiple simultaneous synthesis of compounds. WO 97/30784-A1 50 discloses a microreactor for the synthesis of chemical compounds. Akporiaye, D. E.; Dahl, I. M.; Karlsson, A.; Wendelbo, R. Angew Chem. Int. Ed. 1998, 37, 609-611 disclose a combinatorial approach to the hydrothermal synthesis of zeolites; see also WO 98/36826. Other examples 55 include U.S. Pat. Nos. 5,609,826, 5,792,431, 5,746,982, 5,785,927, and WO 96/11878-A1.
Combinatorial approaches have been applied to catalyst testing to expedite the testing process. For example, WO 97/32208-A1 teaches placing different catalysts in a multi- 60 cell holder. The reaction occurring in each cell of the holder is measured to determine the activity of the catalysts by observing the heat liberated or absorbed by the respective formulation during the course of the reaction, and/or analyzing the products or reactants. Thermal imaging has been 65 used as part of other combinatorial approaches to catalyst testing; see Holzwarth, A.; Schmidt, H.; Maier, W. F. Angew.
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Chem. Int. Ed., 1998, 37, 2644-2647, and Bein, T. Angew. Chem. Int. Ed., 1999,38,323-326. Thermal imaging may be a tool to learn some semi-quantitative information regarding the activity of the catalyst but it provides no indication as to the selectivity of the catalyst.
Some attempts to acquire information as to the reaction products in rapid-throughput catalyst testing are described in Senkam, S. M. Nature, July 1998, 384(23), 350-353, 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.; Tuner, H. W.; Weinberg, W. H. Angew Chem. Int. Ed. 1999, 38, 484^-88 teaches 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.
More recently combinatorial chemistry has been applied 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.; Maler, W. F. Angew Chem. Int. Ed. 1998,37, 3369-3372; Taylor, S. J.; Morken, J. P. Science, April 1998, 280(10), 267-270; 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. Some commercial processes have operated using multiple parallel reactors where the products of all of the reactors are combined into a single product stream; see U.S. Pat. No. 5,304,354 and U.S. Pat. No. 5,489,726. U.S. Pat. No. 5,112,574 discloses an array of stoppers that may be inserted into the wells of any multititer plate.
A multiple parallel reactor assembly to simultaneously test a plurality of catalysts in a rapid, economical, and consistent way has been developed. The invention allows for easy simultaneous assembly of the multiple parallel reactors. The tops and bottoms forming the multiple parallel reaction chambers are attached to supports, one support for the plurality of tops and another support for the plurality of bottoms, so that assembly involves manipulating only the two supports instead of individually manipulating the significantly larger number of individual components. However, the present invention retains a great deal of flexibility by not fully integrating the key components into the supports. Each key component is individually removable from the support. Worn or defective components are readily individually replaced without disturbance to other components. Similarly, the vessels containing the catalyst particles are housed within the bottoms can be individually removed. The number of parallel reactors in the assembly is readily varied through the addition or subtraction of as little as one set of key components.
SUMMARY OF THE INVENTION
The purpose of the invention is to provide a multiple parallel catalytic reactor assembly having (1) a plurality of
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bottoms, each bottom having an open end and a closed end with the plurality being supported by a single first support; (2) a plurality of tops supported by a single second support with the plurality of tops engaged with the plurality of vessels to form a plurality of sealed independent reaction 5 chambers; (3) a plurality of vessels for containing catalyst, each vessel having an open end and a fluid permeable end, and positioned within the reaction chambers so that the open ends of the vessels are in alignment with the open ends of the bottoms (4) a plurality of first fluid conduits in fluid com- 10 munication with the reaction chambers, and (5) a plurality of second fluid conduits in fluid communication with the reaction chambers. A specific embodiment of the invention is one where one or more heaters are positioned adjacent the plurality of bottoms to heat the bottoms and the reaction 15 chambers. Another specific embodiment of the invention is one where one or more seals are used to engage the plurality of bottoms and the corresponding plurality of tops and optionally another seal or seals are used to engage the plurality of vessels and the plurality of tops to form the 20 sealed reaction chambers.
Another purpose of the invention is to provide a process for conducting multiple parallel catalyst evaluations using the multiple parallel catalytic reactor assembly described above with the advantage of simultaneously sealing all of 25 the open ends of the plurality of bottoms with the plurality of corresponding tops to form the multiple sealed independent reaction chambers. A specific embodiment of the invention also includes simultaneously opening all the multiple sealed reaction chambers by removing the plurality of tops 30 from the open ends of the plurality of bottoms. Another specific embodiment of the invention is one where the plurality of vessels containing catalyst are removed from the plurality of bottoms.
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BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side view of one specific embodiment of a single reactor of the multiple parallel catalytic reactor assembly of the present invention. FIG. 2 is a side view of 4Q another specific embodiment of a single reactor of the multiple parallel catalytic reactor assembly of the present invention. FIG. 3 is a side view of yet a third specific embodiment of a single reactor of the multiple parallel catalytic reactor assembly of the present invention. FIG. 4 is ^ a side view of the yet another specific embodiment of the multiple parallel catalytic reactor assembly of the present invention.
DETAILED DESCRIPTION OF THE
INVENTION 50
In general terms, the present invention is a multiple parallel catalytic reactor assembly where each reactor in the assembly has several key components. Each reactor has a bottom having an open end and a closed end and each 55 reactor also has a top which engages the open end of the bottom to form a sealed reaction chamber. Within the sealed reaction chamber, each reactor has a vessel having an open end and a fluid permeable end and contains catalyst. Finally, the sealed reaction chamber of each reactor is in fluid go communication with two fluid conduits. Two or more individual reactors may be used in the assembly. The assembly is also quite flexible, allowing the number of individual reactors in the assembly to be adjusted with ease.
As mentioned above, each reactor in the parallel catalytic 65 reactor assembly contains a bottom that has a closed end and an open end. Note, however, that the closed end may contain
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a fluid conduit as discussed below. The bottoms are constructed of materials selected to withstand the temperatures, pressures and chemical compounds of the particular application. Examples of suitable materials include metals and their alloys, low grade steel, and stainless steels, superalloys like incollsy, inconel, hastalloy, engineering plastics and high temperature plastics, ceramics such as silicon carbide and silicon nitride, glass, quartz, Teflon polymer, nylon, low temperature plastics such as polyethylene, polypropylene, and polyetherether ketone. It is not necessary that each vessel in the plurality be constructed of the same material.
The bottom is preferably cylindrical in shape, but may be of other geometric shapes. For example, the cross-section of the bottom may be in the shape of a square, an ellipse, a rectangle, a polygon, "D"-shaped, segment- or pie-shaped, a chard, a cone or the like. For ease of discussion, the bottom is discussed here as having a cylindrical shape. The bottom has a top end, sides, and a bottom end. The top end is open and the bottom end is permanently closed. The preferred volume of the bottoms ranges from about 0.001 cm3 to about 10 cm3 with two most preferred volumes being 0.1 cm3 and 1 cm3. The preferred size of the bottoms ranges from a length/diameter ratio of about 1 to about 20. It is more preferred that the length/diameter of the bottoms be greater than 4 and ideally 5 or 10. It is preferred that the bottoms be constructed of material that is able to withstand temperatures of from about 10° C. to about 1000° C. It is contemplated that the equipment may be used in applications that require cooling, and therefore in some specific applications the bottoms should be constructed of material that is able to withstand temperatures as low as -70° C. It is also preferred that the bottoms be constructed of material having good heat transfer properties and that the material of construction is inert in the reaction being conducted. While it may be preferred, all the bottoms in the plurality are not necessarily identical. The geometry, size, volume, and material of construction may be varied between bottoms within the plurality.
Each of the bottoms is a freestanding unit or independent piece of apparatus, however, significant advantages are achieved through attaching each of the bottoms to a single support. The attachment of all of the bottoms to a single support operates to provide the benefits of having all of the bottoms maneuverable as a single unit, while maintaining the flexibility of replacing any or all of the individual bottoms as necessary. For example, it is far more convenient for handling and assembly to be able to manipulate a single support as opposed to individually manipulating multiple bottoms. Also, robotics, which are frequently used in combinatorial application, are more readily adapted to manipulating a single tray. Furthermore, as will be discussed in greater detail below, the assembly of the reactors is reduced to a single step which simultaneously seals and forms the multiple parallel reactors. Although less preferred, two-stage action is within the scope of the present invention. The attachment may be fixed, or may be temporary such as using bolts or fasteners.
The support may provide for the attachment of any number of individual bottoms. For example, a support may attach 6,8,12,24,48, 96, and 384 bottoms. Ease of handling is only one of the benefits of the support, flexibility is another. In any given application, the full capacity of a support need not be utilized, i.e., a support capable of supporting 24 bottoms may be used to support only two bottoms. The system is very flexible in that the number of bottoms in use is easily altered by simply adding or remov5
ing bottoms to the support. Similarly, should one bottom of a plurality become worn or damaged, that single bottom may be independently replaced without replacement of other bottoms in the plurality.
As with the bottom itself, the support may be constructed 5 of a variety of materials including metals and their alloys, low grade steel, and stainless steels, super-alloys like incollsy, inconel, hastalloy, engineering plastics and high temperature plastics, ceramics such as silicon carbide and silicon nitride, glass, quartz, Teflon polymer, nylon, and low 10 temperature plastics such as polyethylene, polypropylene, and polyetherether ketone. The support may allow for the attachment of the vessels in any number of geometrical patterns with the preferred being a grid. It is preferred that the support have dimensions similar to the dimensions of ^ commonly used microtiter trays. It is preferred that the support be constructed of material that is able to withstand temperatures of from about 10° C. to about 1000° C, and for many catalytic reactions, the support may be required to withstand temperatures ranging from about 300° C. to about 2o 1000° C. As discussed above, in some applications requiring cooling, the support may be constructed of material able to withstand temperatures as low as -70° C.
The multiple parallel catalytic reactor assembly of the present invention may optionally contain one or more heat- 25 ers to heat at least a portion of one or more of the bottoms. For many reactions, the catalyst used in the reaction must be heated to a desired temperature range. The multiplicity of bottoms may be heated as a unit or each bottom may be individually heated. All heated bottoms may be heated to the 30 same temperature, or different individual bottoms may be heated to different temperatures. The portion of the bottom that is heated is usually that portion closest to the location of the catalyst (discussed below), and generally, it is preferred that the closed end of the bottoms be heated. 35
The multiple parallel catalytic reactors of the present invention further contain a plurality of tops which correspond to the plurality of bottoms. The tops engage the open ends of the bottoms to form sealed reaction chambers. Therefore, for every bottom in the plurality there must be a 40 corresponding top. Like the bottoms, the tops may be constructed of a variety of materials including metals and their alloys, low grade steel, and stainless steels, superalloys such as incollsy, inconel, hastalloy, engineering plastics and high temperature plastics, ceramics such as silicon 45 carbide and silicon nitride, glass, quartz, Teflon polymer, nylon, and low temperature plastics such as polyethylene, polypropylene, and polyetherether ketone. The support for the tops may be required to withstand temperatures from 10° C. to about 1000° C, but a preferred range of temperatures 50 includes temperatures ranging from about 10° C. to about 350° C. It is also contemplated that in some applications, the support for the tops may be required to withstand temperatures as low as -70° C. It is preferred that each top in the plurality be constructed of the identical material, but it is not 55 necessary. Similarly, in some applications it may be preferred that the plurality of tops be constructed of the same material as the corresponding plurality of bottoms, but again it is not necessary. For example, in the situation where only the closed end of the bottoms are heated, heat resistant 60 material may be used for the construction of the bottoms, where non-heat resistant material may be used for the corresponding tops. It is preferred that the length of the bottoms be sufficient so that the tops are not affected by the heater used at the closed end of the bottoms, thereby 65 allowing lower temperature materials to be used for the construction of the tops.
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It is preferred that the overall shape of the tops conform to the shape of the corresponding bottoms so that the tops may adequately engage the bottoms to form sealed reaction chambers. The tops may be formed so as to merely seal the open end of the bottoms, or the top may extend within the open end of the bottoms to further define the reaction chambers. If necessary, one or more seals may be used to engage both the bottoms and the tops to form the sealed reaction chambers. One seal may be used to engage both the plurality of bottoms and the plurality of tops, or each set of a bottom and its corresponding top may have an independent seal. As discussed below, the seal(s) may also seal the vessel. An advantage of the present invention is that seals that function only at lower temperatures may be employed even if the catalyst in the reaction chamber is to be heated to a high temperature. In such a situation, the catalyst is contained near the closed end of the bottoms and only the closed end of the bottoms are heated. The lengths of the bottoms are preferably chosen so that the position of the seal(s) is a sufficient distance from the heater and the seal(s) is not affected by the heat. It is most preferred that the seals be prevented from exceeding 200° C.
As with the bottoms, each of the tops is a freestanding unit or independent piece of apparatus. Again, however, significant advantages are achieved by attaching each of the tops to a single support. Manual or robotic handling and assembly is simplified by manipulating a single support as opposed to individually manipulating multiple bottoms. Furthermore, as will be discussed in greater detail below, the assembly of the reactors is reduced to a single step which simultaneously seals and forms the multiple parallel reactors.
The support for the tops may provide for the attachment of any number of individual tops. For example, a support may attach 6, 8, 12, 24, 48, 96, 384, and 1264 tops. As with the bottoms, ease of handling is only one of the benefits of the support, and flexibility is another. In any given application, the full capacity of a support need not be utilized, i.e., a support capable of supporting 24 tops may be used to support only two tops. The system is very flexible in that the number of tops in use is easily altered by simply adding or removing one or more tops to the support. Similarly, should a top of a plurality become worn or damaged, that single top may be independently replaced without replacement of other tops in the plurality.
As with the tops themselves, the support for the tops may be constructed of a variety of materials including metals and their alloys, low grade steel, and stainless steels, superalloys like incollsy, inconel, hastalloy, 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, polypropylene, and polyetherether ketone. The support for the tops may be required to withstand temperatures from 10° C. to about 1000° C, but a preferred range of temperatures includes temperatures ranging from about 10° C. to about 350° C. In some applications, it is anticipated that the support for the tops may be required to withstand temperatures as low as -70° C. The support may allow for the attachment of the tops in any number of geometrical patterns with the preferred support being a grid arrangement. However, it is important that the arrangement of the tops be such that it allows for each top to properly engage its corresponding bottom to form the sealed reaction chambers. It is therefore preferred that the arrangement of the tops coordinate with the arrangement of the bottoms.
Another component of the present invention is a plurality of vessels to contain the catalyst. Each vessel has an open
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