Preparation method for catalyst prepared from Si-based material having undergone lattice doping by metallic element, and method for oxygen-free preparation of ethylene from methane

Abstract

The invention relates to a preparation method for a catalyst prepared from a Si-based material having undergone lattice doping by a metallic element, and a method for oxygen-free preparation of ethylene from methane. The methods realize zero carbon formation of methane and high-selectivity synthesis of ethylene. According to the invention, in a fixed-bed reaction mode, reaction temperature is 750 to 1100 DEG C and reaction pressure is 0.1 to 0.3 Mpa; the mass space velocity of raw reaction gas is 1000 to 30000 ml / g / h; the conversion rate of methane is 10 to 60%; the selectivity of olefins is 60 to 95%; the selectivity of propylene and butylene is 5 to 25%; the selectivity of aromatic hydrocarbons is 0 to 25%; and zero carbon formation is formed. The methods provided by the invention has the characteristics of long service life (greater than 500 h) of the catalyst, good redox performance and hydro-thermal stability at a high temperature (less than 1400 DEG C) of the catalyst, high product selectivity, zero carbon formation, easy separation of products, good process repeatability, safe and reliable operation, etc., and have good industrial application prospects.

Description

technical field [0001] The invention relates to a catalyst in which a metal element lattice is doped into a Si-based material and a method for catalyzing the direct preparation of ethylene from methane under oxygen-free conditions. Background technique [0002] The development and effective utilization of natural gas (methane) resources represent the development direction of contemporary energy structure, and it is also one of the important ways to ensure sustainable development and green energy. In recent years, developed western countries have also made breakthroughs in the development of shale gas and "combustible ice", and a "shale gas revolution" has erupted. There are many types of shale gas resources in my country, and the distribution is relatively concentrated. The recoverable resource potential is 25 trillion cubic meters (excluding the Qinghai-Tibet area), which is equivalent to the conventional natural gas in my country's land area, and is similar to the 24 trill...

AI Technical Summary

Problems solved by technology

For the selective oxidation of methane to produce methanol or formaldehyde, since the oxidation rate of the target product methanol and formaldehyde is much faster than that of the raw material methane, the selectivity of the reaction is low, and there is basically no prospect of large-scale application

[0008] For the method disclosed in the patent application number 201310174960.5, in the catalyst described, metal elements coexist in the Si-based material as lattice doping and surface loading, resulting in some defects in the catalyst structure, which leads to the following shortcomings in the catalyst and reaction process : (1) redox tolerance temperature is only 800-1150°C; (2) catalyst life is short (about 100 hours); (3) ethylene selectivity is low (30-90%); (4) selection of aromatic products High resistance (10-70%); (5) There is a small amount of carbon deposition in the initial stage of the reaction

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