A kind of chromium base metal oxide-molecular sieve catalyst and its preparation method and application

Abstract

The invention provides a chromium-based metal oxide-molecular sieve catalyst, comprising chromium-based metal oxide and H-SAPO-34 molecular sieve; the chemical formula of the chromium-based metal oxide is Cr a m b o c ; said a~c represent the relative substance amount of each element, satisfying that the total valence of chromium-based metal oxide is zero; said M is one or more of zinc, indium, aluminum and zirconium. In the present invention, H-SAPO-34 molecular sieve is used as a matrix, and chromium-based metal oxide is used as an active component to make a composite catalyst for CO 2 Hydrogenation to ethylene can significantly improve the selectivity of ethylene. The results of the examples show that the chromium-based metal oxide-molecular sieve catalyst provided by the invention is used for CO 2 Hydrogenation to ethylene, CO 2 The conversion rate is 12.7%, the selectivity of total light olefins is 95.9%, and the selectivity of ethylene is 66.4%.

Description

technical field [0001] The invention relates to the technical field of catalysts, in particular to a chromium-based metal oxide-molecular sieve catalyst and a preparation method and application thereof. Background technique [0002] The rapid consumption of fossil energy induces CO 2 A large amount of emissions have caused serious environmental problems and global warming. will CO 2 Transformation into high value-added chemical raw materials, such as methanol, formic acid, methane, low-carbon olefins and aromatics, can not only reduce CO in the atmosphere 2 It also provides a new idea for the preparation of clean energy. Among them, low carbon olefins (C 2 ＝ –C 4 ＝ ), including ethylene, propylene and butene, as an important basic raw material in the chemical industry, has attracted the interest of a large number of researchers, and compared with propylene and butene, ethylene has higher economic value and has an important role in the modern chemical industry A lot o...

AI Technical Summary

Problems solved by technology

In the Fischer-Tropsch synthesis route, Fe-based, Co-based or Rh-based catalysts are generally used, although exhibiting higher CO 2 Conversion rate, but due to the limitation of the Anderson-Schultz-Flory (abbreviated ASF) rule, the selectivity of low carbon olefins is generally lower than 58%, wherein C 2 Selectivity to hydrocarbons (including ethylene and ethane) less than 30%

ZnZrO Prepared Based on Methanol Intermediate Route x / SAPO-34, ZnAl 2 o 4 / SAPO-34, ZnGa 2 o 4 / SAPO-34, In 2 o 3 / SAPO-34 and InZrO x / SAPO-34 and other bifunctional catalysts, in CO 2 In the reaction of hydrogenation to olefins, it can effectively break through the restrictions of ASF rules and greatly increase the C 2 ＝ –C 4 ＝ Olefin selectivity, but there is still the problem of low ethylene selectivity

For example, there are studies (Gao P, Dang S, Li S, et al. Direct Production of lower olefins from CO 2 conversion via bifunctional catalysis[J].ACSCatal, 2018, 8, 571-578) with In 2 o 3 / H-SAPO-34 composite catalyst catalyzes CO 2 In the hydrogenation reaction, the selectivity of low-carbon olefins in the total hydrocarbons can reach 80%, but the selectivity of ethylene is lower than 35%; research (Liu X, Wang M, Yin H, et al.Tandemcatalysis for hydrogenation of CO and CO 2 to lower olefins with bifunctional catalysts composed of spine oxide and SAPO-34[J].ACS Catal, 2020, 10, 8303-8314; Liu Xiaoliang, Wang Ye et al.Selective transformation of carbon dioxide into lower olefins with a bifunctional catalyst composed of ZnGa 2 o 4 and SAPO-34[J].Chem.Commun, 2018, 54, 140-143) reported that ZnAl 2 o 4 / SAPO-34 and ZnGa 2 o 4 / SAPO-34 two catalysts, in CO 2 In the hydrogenation of olefins, the selectivity of low-carbon olefins in the total hydrocarbons reaches 80-87%, but the selectivity of ethylene is still lower than 30%

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