Process for step-by-step improvement of methane conversion through methane cracking and carbon elimination

Abstract

The invention provides a process for step-by-step improvement of methane conversion through methane cracking and carbon elimination. The process comprises the following steps: introducing mixed gas of CH4 and Ar into a fixed bed filled with a catalyst and carrying out a methane cracking reaction at a pressure of 0.1 to 3 MPa and a temperature of 300 to 900 DEG C for 10 to 60 min; carrying out purging with Ar; introducing carbon elimination gas and carrying out a carbon elimination reaction at a pressure of 0.1 to 3 MPa and a temperature of 400 to 900 DEG C for 15 to 60 min; carrying out purging with Ar again to finish a methane conversion reaction once; and repeating the cracking reaction and the carbon elimination reaction to complete the methane conversion reaction a plurality of times. According to the invention, the methane cracking reaction is carried out first and then the carbon elimination reaction is carried out so as to eliminate accumulated carbon the surface of a catalyst; since the separate two-step reactions need low temperature, energy consumption is reduced and sintering of the catalyst at high temperature is avoided at the same time; and the method allows the catalyst to maintain catalytic activity for a long time.

Description

technical field [0001] The invention relates to a method for preparing synthesis gas by catalytic conversion of methane, in particular to a process for improving methane conversion step by step through methane cracking and carbon elimination. Background technique [0002] The methods of catalytic conversion of methane to synthesis gas mainly include carbon dioxide reforming of methane, steam reforming of methane and partial oxidation of methane. These reactions convert the greenhouse gas methane into synthesis gas capable of synthesizing various chemicals, and have bright application prospects. Nickel-based catalysts have been widely used in the above reactions due to their abundant resources, low price, high activity, and high selectivity. However, nickel-based catalysts have problems of carbon deposition and sintering, which hinder the industrial application of methane to synthesis gas. Most of the research work in the prior art is devoted to overcoming a shortcoming of ni...

AI Technical Summary

Problems solved by technology

[0003] Chinese patent [CN101637726] discloses a method for improving the carbon deposition resistance of methane carbon dioxide reforming catalysts. The patent uses γ-Al 2 o 3 or NiAl 2 o 4 As the carrier, Ni is used as the active component, and a small amount of Pt is used as the auxiliary agent to prepare a nickel-based catalyst. It has good anti-coking performance for carbon dioxide reforming of methane, but the addition of auxiliary agents is limited due to the high price of Pt and limited resources. To realize the industrial application of anti-carbon deposition

Catalysts usually obtained by reduction of perovskite have good activity, stability and anti-coking properties, but their specific surface area is small, which limits industrial applications.

In addition, this method also has the problem that the reduction temperature is too high

[0007] The above methods only improve the anti-coking or anti-sintering performance of the catalyst through the improvement of the catalyst. However, carbon deposition and sintering often occur at the same time, and they will affect each other, greatly reducing the stability of the catalyst.

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