A kind of multistage nano-reactor catalyst for directly preparing aromatic compounds from syngas and its preparation and application

Abstract

The invention discloses a multi-level nano-reactor catalyst capable of directly converting synthesis gas into aromatics in one step, as well as its preparation and application. The catalyst consists of a core layer iron-based Fischer-Tropsch catalyst, a transition layer of porous oxide or porous carbon material and a molecular sieve shell layer with aromatization function. Among them, the shell molecular sieve can be further modified with metal elements or non-metal elements, and the outer surface of the molecular sieve can be further modified with silicon oxide compounds to adjust the acidic sites on the outer surface and the pore size of the molecular sieve, thereby inhibiting the formation of heavy aromatics. The preparation method of the multi-stage nanoreactor catalyst of the present invention can be obtained by the iron-based Fischer-Tropsch catalyst through multi-steps, and the molecular sieve containing the transition layer, the shell layer containing additives or no additives, and the shell layer containing surface modification or not containing . The catalyst can be used to directly prepare aromatic compounds, especially light aromatic compounds, from synthesis gas; the selectivity of light aromatics in hydrocarbons can reach more than 75%, and the content in liquid phase products is not less than 95%; the catalyst has good stability, It has good industrial application prospect.

Description

technical field [0001] The invention belongs to the technical field of synthesis gas conversion, and relates to a catalyst for directly producing aromatic compounds from synthesis gas through a Fischer-Tropsch synthesis route, as well as its preparation and application. Background technique [0002] Aromatic compounds including benzene, toluene and xylene (BTX) are important chemical basic raw materials, which are mainly derived from petroleum-based production processes, such as naphtha steam cracking for ethylene production and catalysis for gasoline and diesel production reforming or cracking. With the lightening of olefin raw materials, the reduction of crude oil resources and the increasingly prominent environmental problems, it is challenging and unsustainable to obtain aromatic compounds from petroleum routes. Therefore, more and more attention has been paid to the production of aromatics from non-petroleum routes. Based on my country's energy structure rich in coal ...

AI Technical Summary

Problems solved by technology

[0004] However, the use of direct composite catalysts for the direct production of aromatics from syngas still has certain limitations. For example, for intermediate products that are easy to undergo aromatization reactions, such as C2-C5, they still need to undergo several diffusions before entering the aromatization catalyst. At the same time, these intermediate products have the opportunity to escape; at the same time, after CO passes through the CO conversion catalyst, CO often cannot continue to be activated and reacted on the second catalyst; in addition, the physical mixing method is easy to cause two The uneven distribution of active site concentration in the reaction system will affect the aromatization reaction of intermediate products to varying degrees

Due to the existence of these problems, the selectivity and yield of final aromatics are generally not high, especially light aromatics such as benzene, toluene and xylene

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