Chemistry: analytical and immunological testing – Testing of catalyst
Reexamination Certificate
2000-10-27
2002-07-30
Soderquist, Arlen (Department: 1743)
Chemistry: analytical and immunological testing
Testing of catalyst
C250S281000, C250S282000, C250S283000, C250S288000, C436S147000, C436S159000, C436S172000, C436S173000, C422S083000, C422S098000
Reexamination Certificate
active
06426226
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to rapid screening for activities and selectivities of heterogeneous and homogeneous catalyst libraries by mass spectrometry. This invention provides very rapid screening of gaseous, liquid or solid products from all catalyst sites in a catalyst library by mass spectrometry and its combination with selective resonance enhanced multiphoton ionization (REMPI).
Solid and liquid catalysts are used in the manufacture of a vast array of chemicals and fuels, and in this manner significantly contribute to the economy and high living standards. National Research Council, “Catalysis Looks to the Future”, National Academy Press, Washington, D.C., 1992. Catalysts also provide important environmental benefits, such as in catalytic converters for internal combustion engines. However, in spite of their significance and broad utility, the development of new and improved catalysts continues to be an arduous and rather unpredictable trial and error process. Conventionally, an individual catalyst is prepared using a large variety of tedious and time consuming methods, characterized and tested for catalytic activity, modified, again characterized and tested again, until no further improvements are justified. This approach, although time consuming, has been successful for the discovery of a significant number of solid state catalysts, Heinemann, H., “A Brief History of Industrial Catalysts”, Catalysis: Science and Technology, Anderson, J. R. and Boudart, M. Eds., Chapter 1, Springer-Verlag, Berlin, 1981, and homogeneous, liquid-state catalysts, Montreus, A. and Petit, F., “Industrial Applications of Industrial Catalysts” Kluwer Publishing, New York, 1988.
Combinatorial chemistry, in which a large number of chemical variants are produced rapidly and a chemical library generated which is then screened for desirable properties using a suitable technique, is a particularly attractive approach for the discovery of new catalysts. Chem. Eng. News, Feb. 12, 1996. Combinatorial synthesis was initially used to synthesize large libraries of biological oligomers, such as peptides and nucleotides, however, the creation of small molecule libraries which can be used for drug testing is growing. Nielsen, J., Chem. & Indus., 902, Nov. 21, 1994. Recently, combinatorial diversity synthesis has been extended to solid-state compounds used in superconducting, xiang, X-D., Sun, X., Briceno, G., Lou, Y., Wang, K-A., Chang, H., Wallace-Freedman, W. G., Chen, S-W. and Schultz, P. G., “A Combinatorial Approach to Materials Discovery”, Science, 268, 1738, 1995, magnetoresistivity, Briceno, G., Chang, H., Sun, X., Schultz, P. G. and xiang, X-D., “A Class of Cobalt Oxide Magnetoresistance Materials Discovered With Combinatorial Synthesis” Science, 270, 273, 1995 and luminescence, Wang, J., Yoo, Y., Takeuchi, I, Sun X-D., Chang, H., Xiang, X-D. and Schultz, P. G., “Identification of Blue Photoluminescent Composite Material from a Combinatorial Library”, Science 279, 1712, 1998, Danielson, E., Golden, J. H., McFarland, E. W., Reaves, C. M., Weinberg, W. H., and Wu, X-D., “A Combinatorial Approach to the Discovery and Optimization of Luminescent Materials”, Nature, 398, 944, 1997, Sun, X-D, Gao, C., Wang, J. and Xiang, X-D., “Identification and Optimization of Advanced Phosphors using Combinatorial Libraries”, App.Phy.Lett., 70, 3353, 1997 and Sun, X-D., Wang, K. A., Yoo, Y., Wallace-Freedman, W. G., Gao, C, xiang, X-D. and Schultz, P.G., “Solution-Phase Synthesis of Luminescent Materials Libraries”, Adv.Mater, 9, 1046, 1997. In these cases physically masked individual specimens were each measured using contact probes with a computer-controlled multichannel switching system. Microprobe sampling coupled to mass spectrometry, Kassem, M., Qum, M. and Senkan, S. M., “Chemical Structure of Fuel-Rich 1,2-C
2
H
4
Cl
2
/CH
4
/O
2
/Ar Flames: Effects of Microprobe Cooling on Sampling of Flames of Chlorinated Hydrocarbons”, Combust. Sci. Tech., 67, 147, 1989, and in situ IR, Moates, F. C., Somani, M., Annamalai, J., Richardson, J. T., Luss, D. and Wilson, R. C., “Infrared Thermographic Screening of Combinatorial Libraries of Heterogeneous Catalysts”, Ind. Eng. Chem. Res., 35, 4801, 1996, have been proposed for catalyst screening, but suffer serious deficiencies in not having sufficient sensitivity, selectivity, spatial resolution or high throughput capacity to screen large catalyst libraries, as well as the lack of ability to test the activity of hundreds or thousands of compounds simultaneously. Service, R. F., “High Speed Materials Design”, Science, 277, 474, 1997. Microprobe mass spectrometry requires sampling and transfer of very small quantities of gases containing low concentrations of product species from each site rendering the process impractical for rapid screening. In situ infrared techniques cannot provide information on product selectivity which is crucial for catalyst identification.
Mass spectrometry is a well established and broadly applicable method for determining mass of gaseous species. The technique involves the ionization of gaseous molecules by a number of methods, such as, for example, by electron impact or light photoionization followed by separation of ions using techniques, such as, for example, quadrupole mass spectrometry or time of flight mass spectrometry and detection of selected ions by a suitable detector. Capillary probe sampling mass spectrometry has recently been reported for screening of catalyst libraries by Cong, P.; Giaquinta, D.; Guan, S.; McFarland, E.; Self, K.; Turner, H.; and Weinberg, W. H., “A combinatorial Chemistry Approach to Oxidation Catalyst Discovery and Optimization”, Process Miniaturization Section, 2nd Intl. Conf. Micro Technol., Mar. 9-12, 1998, New Orleans, La., pg. 118. Cong, et al teach introduction of reactant gas to an individual library site through an annular space surrounding a capillary tube through which product gas flows from that library site to the ionization zone of a mass spectrometer. Cong. et al report measurement of 144 library sites in about 2 hours. Sample transfer rates by capillary in the Cong, et al method are limited by the pumping speed tolerated by the mass spectrometer chamber. Another disadvantage of capillary probe sampling is the potential of adsorption and catalysis induced by relatively long transfer line surfaces. There remains a large unexplored universe of binary, ternary, quaternary and higher-order solid state materials, organometallic species and other complex metal compounds that could have superior catalytic properties. Prior conventional approaches have been inadequate to rapidly synthesize and screen this vast universe of catalytic compounds. There is clearly a need for development or more efficient and systematic methods to produce heterogeneous and homogeneous state libraries and to screen them for desired catalytic properties. Combinatorial solid state synthesis techniques have not been applied to the discovery of new and/or improved catalysts. A significant impediment for this has been the lack of a broadly applicable, sensitive, selective and high throughput measurement technique which could be used to rapidly screen large catalysts libraries. Catalyst screening requires the unambiguous detection of the presence of a specific product molecule in the vicinity of a small catalyst site on a large library, unlike superconductivity or magnetoresisitivity which can both be easily tested by conventional contact probes, or luminescence that can be tested by light emission.
SUMMARY OF THE INVENTION
This invention provides a high-throughput method to rapidly screen the activities and selectivities of homogeneous and heterogeneous catalyst libraries generated by combinatorial synthesis. Solid and liquid state catalyst libraries can be generated using a variety of techniques and can involve the combination of a large number of chemical elements and compounds.
In one embodiment, catalyst libraries may be screened for both activity and selectivity by high throughput screening using mass spectrometr
Finnegan, Henderson, Farabow, Garrett and Dunner, L.L.C.
Laboratory Catalyst Systems LLC
Soderquist Arlen
LandOfFree
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