The Application Of Combinatorial Catalysis In The Coupling Methane With Small Molecule Componds

Combinatorial chemistry, by which a large diversity of chemical compounds are prepared, processed, and tested in a high-throughput fashion, has created a revolution in pharmaceutical and biotechnology development. Now it has been extended to the discovery of new materials since the initial example published in Science in 1995. It is considered that combinatorial technique will revolutionarily improve the development of material science.In this paper, a method for combinatorial preparation and high-throughput screening heterogeneous catalysts was established. The combinatorial preparation method based on wet impregnating was validated an effective and precise tool for preparation of supported catalysts. A high-throughput screening system has been developed by incorporation of an 80-pass reactor and a quantified multistream mass spectrometer screening (MSMSS) technique. With low temperature melting alloy as heating medium, a uniform reaction temperature could be obtained in the multistream reactor (maximum temperature differences are less than 1 K at 673K). The quantification of the results was realized by combination of a gas chromatogram with the MSMSS, which could provide product selectivities of each catalyst in a heterogeneous catalyst library. Because the catalyst loading of each reaction tube is comparable with that of the conventional micro-reaction system, and the parallel reactions could be operated under identical conditions (homogeneous temperature, same pressure and WHSV), the reaction results of a promising catalyst selected form the library could be reasonably applied to the further scale-up system. By combination the MSMSS with another kind of multistream reactor that can be heated to 923 K with a linear heating rate, we can realize the examination of surface acidityof 20-40 catalyst samples in one day by NH3-TPD method, which is an improvement over the traditional process. The demonstrating of the feasibility of high-throughput TPD can be significant in convincing the hardened traditionalists in the heterogeneous catalysis community that, combinatorial methods indeed should have an important place in scientific catalyst research and development. The developed method could also be used for almost all the temperature-programmed analysis theoretically with carefully designed multistream reactors.Based on the developed combinatorial method, we investigate some new reactions, such as coupling methane with CO, coupling methane with ethylene, coupling methane with dimethyl ether and selective oxidation dimethyl ether to methyl formate. The results indicate that Zn/HZSM-5 is effective catalyst for the reaction of coupling methane with CO, and methyl formate is formed over Pt/SiO2 catalyst by oxidation dimethyl ether.