Catalyst, preparation method and application of high-stability synthesis gas for directly producing low-carbon olefins

Abstract

The invention provides a catalyst used for direct synthesis gas transformation for low carbon olefin preparation, a preparation method and application of the catalyst used for direct synthesis gas transformation for low carbon olefin preparation. The catalyst is formed by conducting physical mixing and grinding on a metal oxide catalyst and a covered coated molecular sieve catalyst according to amass ratio of (0.4 to : 1) to (2 to : 1), wherein the metal oxide catalyst is a ZrO2-ZnO catalyst with a molar ratio of Zr to Zn being equal to 2 to 1, and the covered coated molecular sieve catalystis a covered coated M@Sillicalite-1 molecular sieve catalyst formed by covering coating SAPO-34 or SSZ-13 molecular sieves with pure silicon Silicalite-1 molecular sieves. The covered coated molecularsieve catalyst is adjustable in acidity, rich in pore structure and large in specific surface area, by applying the covered coated molecular sieve catalyst and the metal oxide catalyst to reaction ofdirect synthesis gas transformation for low carbon olefin preparation at the same time, the selectivity of low carbon olefin can be improved, the selectivity of a by-product CO2 can be reduced, and the service lives of the catalysts can be prolonged.

Description

technical field [0001] The invention relates to a dual-functional catalyst used for one-step direct conversion of synthesis gas to produce low-carbon olefins and a preparation method thereof, in particular to a preparation method of a coated composite molecular sieve catalyst. Background technique [0002] Low-carbon olefins (ethylene, propylene, butadiene) are important basic chemical raw materials and are widely used in organic chemicals such as synthetic rubber, plastics, and organic solvents. It plays a pivotal role in industrial production and national economy. [0003] There are mainly two ways to produce light olefins from syngas: FTO (to produce low-carbon olefins from syngas) and MTO (to produce low-carbon olefins with methanol as an intermediate product). Among them, the FTO route is the conversion of synthesis gas through iron-based and cobalt-based catalysts at high temperatures, and the reaction products are mostly C 5+ Hydrocarbons, the selectivity of low-car...

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Problems solved by technology

Among them, the FTO route is the conversion of synthesis gas through iron-based and cobalt-based catalysts at high temperatures, and the reaction products are mostly C 5+ Hydrocarbons, the selectivity of low-carbon olefins in the product is difficult to break through the Anderson-Schulz-Flory distribution (58%) in Fischer-Tropsch synthesis, this method is not the best choice for high-selectivity production of low-carbon olefins

The MTO pathway consists of a two-step series reaction, that is, hydrogenation of CO in the first reactor at a lower temperature to synthesize methanol, and then methanol is introduced into the second reactor to be catalytically converted to low-carbon olefins by molecular sieves at high temperature, However, the two-step reaction temperature is inconsistent, the reaction process consumes a lot of energy, and the equipment investment cost is high.

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