The first industrial application of molecular sieves in the field of catalysis was in 1959 by the United States Union Carbide Company.

by:Xintao Technology     2022-04-14
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The first industrial application of molecular sieves in the field of catalysis was in 1959 when the U.S. Union Carbide Company applied the Y-type zeolite-based catalyst to the isomerization reaction, and then in 1962, the American Mobil Company applied the X-type zeolite to catalytic cracking. In 2009, Grace Company developed an ultra-stable Y-type zeolite (USY) catalyst. At that time, in addition to being mainly used in cracking and hydrogen cracking, molecular sieve catalysis has been industrialized in the isomerization of n-alkanes, the low-temperature isomerization of C8 aromatics, and the disproportionation of toluene. With the progress of molecular sieve catalysis industry, the theory of zeolite zeolite solid acid catalysis, the concept of Bronsted acid and Lewis acid active center and the reaction mechanism of carbonium ions have been promoted, and the system has been established in the field of zeolite catalysis. Another feature of molecular sieve catalysis, that is, the research on shape-selective catalysis of molecular sieves was carried out at almost the same period.

By the early 1980s, many shape-selective catalytic reactions of small-pore and medium-pore zeolites such as erionite, ZSM-5 and small-pore mordenite were studied. C. Naccache et al. summarized the shape selection problems in different processes of zeolite catalytic reactions, such as the diffusion and adsorption of reactants, the formation of active intermediate states, the entrustment and diffusion of the reaction and the final product, and believed that the shape selection mechanism of molecular sieves mainly depends on The 'sieve' effect of molecular sieves, the size selectivity of reactants and products, and the size selectivity of intermediate states. Shape-selective catalysis is the main feature of molecular sieve catalysis. Since the 1980s, due to the industrialization of many shape-selective catalytic reactions and a large number of theoretical research results, a relatively systematic shape-selective catalytic reaction theory has been formed. In recent decades, with the needs of ① industrial practice activities, such as the diversification of hydrocarbon conversion in petroleum processing to the catalytic synthesis of intermediates in the fine chemical and pharmaceutical industries to the catalytic treatment of molecular sieves in environmental pollution, (such as dehydration) NOx, removal of organic sulfur, CO conversion, etc.); ②The continuous progress of the second synthesis and modification of zeolite molecular sieves, such as ion exchange of molecular sieves, framework dealumination, isomorphous replacement, and development of molecular sieve cavity assembly technology, etc. '③The emergence of new species of molecular sieves and porous materials, such as the continuous promotion of the advent of a large number of ultra-large microporous molecular sieves, hand-shaped molecular sieves and dielectric materials, the catalytic field of molecular sieves and porous catalytic materials has been continuously developed. In solid acid and shape-selective catalysis On the basis of the theory, metal-molecular sieve bifunctional catalysis, redox catalysis of heteroatom molecular sieves, alkali catalysis of molecular sieves, catalytic reactions in the cavity of super-large micropores and mesoporous materials, chiral catalysis of molecular sieves and many homogeneous phase catalysis have been developed. Catalytic molecular sieve phasing and other new molecular sieve and porous material catalysis fields, and put forward a number of new scientific problems and summed up a number of new scientific laws
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