Preparation method and application of CN (at) Ma-Mb supported monatomic catalyst

Abstract

The invention discloses a preparation method of a CN (at) Ma-Mb metal supported monatomic catalyst, which comprises the following steps: supporting active metals Ma and Mb on a carrier to form a catalyst precursor; adding a ligand to form a complex; and performing pyrolysis to form the CN (at) Ma-Mb metal supported monatomic catalyst. The preparation method of the monatomic catalyst is simple in process and easy to regenerate, the catalytic activity is still kept after regeneration, the conversion rate and selectivity of the catalyst for catalyzing direct dehydrogenation of low-carbon alkane are high, and the monatomic catalyst is suitable for large-scale industrial application.

Description

technical field [0001] The invention belongs to the technical field of petrochemical industry, and particularly relates to an alkane dehydrogenation catalyst. Background technique [0002] Low-carbon olefins include isobutene, 1-butene, 2-butene, 1,3-butadiene, propylene, ethylene, etc., which are the basic raw materials of petrochemical industry and are widely used in the production of organic chemical raw materials, resin rubber plastics, synthetic gasoline Wait. In the petrochemical industry, a large number of low-carbon hydrocarbons are produced in the form of by-products, and corresponding low-carbon olefins can be obtained by dehydrogenation, which has gradually attracted the attention of academia and industry. [0003] The catalytic systems for dehydrogenation of low-carbon hydrocarbons that have been successfully industrialized are mainly supported metal nanoparticle catalytic systems with oxides as carriers. The active metal elements can be platinum, chromium, vana...

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Problems solved by technology

[0004] However, these two types of catalysts have obvious defects: platinum exists in the form of nanoparticles on platinum-based catalysts, and the precious metals are not all exposed on the surface of the catalyst, so the loading capacity is high and the utilization rate is low; chromium compounds are highly toxic and easy to cause environmental pollution , and the continuous reaction time is short in the alkane dehydrogenation reaction, and carbon deposits on the surface of the catalyst during the reaction process require frequent switching of the two processes of regeneration and catalysis

For industrial production, this time will greatly reduce production efficiency

In addition, the structures of the catalysts disclosed in the above patents are mostly M / N-C structures

The catalyst carriers of the two patents are both NC carriers. The problem with this carrier is that it exists in the form of powder, which cannot quickly transfer mass and heat in industrial applications, and is prone to coking and clogging, leading to major safety hazards.

In addition, the oxidation and carbon deposition steps commonly used in the catalyst regeneration process will also damage the NC support, resulting in the destruction of the catalyst.

Although some catalyst structures are M / N-C-Al 2 o 3 , but its catalytic performance is significantly lower than that of M / N-C catalysts

In addition, in this patent, considering the problem of mixing with organic ligands, metal precursors should try to choose organic salts such as acetylacetonate salts, resulting in high production costs and it is difficult to control the actual loading of metals

Therefore, the single-atom catalyst is used in industry, and there are still the following problems: 1. It is impossible to solve the industry's demand for fast and efficient preparation of single-atom catalysts; 2. It is impossible to realize rapid regeneration of catalysts.

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