Catalyst for methanation of CO and H2, and preparation method thereof

Abstract

The invention relates to the methanation catalysis field, in particular to a catalyst for methanation of CO and H2, and a preparation method thereof. The preparation method of hexa-aluminate comprises the following steps of: 1) dissolving an aluminum salt precursor into water, and adding the obtained water solution into an alcohol solution containing a surface active agent, thus obtaining aluminum salt precursor solution; 2) dissolving an alkaline-earth metal salt precursor into an acetic acid water solution, and adjusting the pH value to be 1, thus obtaining alkaline-earth metal salt precursor solution; 3) adding the alkaline-earth metal salt precursor solution into the aluminum salt precursor solution, and controlling the molar ratio between alkaline-earth metal and aluminum to be 1:(6-12), thus obtaining a precursor mixed solution; and 4) evaporating the precursor mixed solution at the temperature of 20-60 DEG C so as to obtain xerogel, carrying out heat treatment on the xerogel at 800-1200 DEG C in the high-purity inert atmosphere for 2-6 hours, and calcining for 2-6 hours at the same temperature, and finally pickling to obtain a hexa-aluminate carrier. The catalyst is high in catalytic activity, anti-carbon and strong in sintering resistance.

Description

technical field [0001] The invention relates to the field of methanation catalysis, in particular, the invention relates to a method for CO and H 2 Catalysts for methanation and methods for their preparation. Background technique [0002] my country is a country rich in coal, low in oil, and poor in gas. The gas obtained by pyrolysis and gasification of coal or biomass mainly contains H 2 , CO and CO 2 , the main component of coke oven gas in the coking industry is also H 2 , CO, and CO 2 etc. These CO-containing mixed gases can undergo methanation reactions to generate CH 4 ; It can not only increase the heat density of gas, but also provide a practical way to fill the gap in my country's natural gas demand. The methanation process mainly involves the following reactions: [0003] CO+3H 2 →CH 4 +H 2 O Δ r h m =-206kJ / mol [0004] This reaction is a strongly exothermic reaction. Although domestic and foreign researchers have designed many methanation processes t...

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Problems solved by technology

The methanation catalysts introduced in the above patent documents have the following deficiencies: on the one hand, the composition of some catalysts is relatively complex, and one or more additives need to be added, which leads to a complicated preparation process of the catalyst and an increase in cost; on the other hand, the carbon deposition and deactivation of the catalyst Serious, the service life is short; in addition, the active temperature range of the catalyst is narrow, once the heat released by the reaction is not discharged in time, it will lead to the sintering of the catalyst and the decrease of catalytic efficiency

[0009] The synthesis methods of hexaaluminate currently reported mainly include coprecipitation method, sol-gel method and inverse microemulsion method. The hexaaluminate prepared by different methods has great differences when used as a catalyst carrier. Patent CN1698951A and CN101612572A disclose coprecipitation method to prepare hexaaluminate catalyst, which are used for light hydrocarbon combustion and N 2 O decomposition, this method is relatively simple, but the specific surface area of ​​the prepared catalyst is small, and the catalyst performance is low

CN101012066A adopts a urea combustion method, the calcination temperature is very high, and the particle uniformity is poor

Hexaaluminate nanoparticles with larger specific surface can be prepared by microemulsion method and technology combined with supercritical drying, but this method needs to configure organic microemulsion, a large amount of microemulsion cannot be reused, causing pollution, and this method The yield is low, and the prepared nanoparticles are prone to agglomeration at high temperature, resulting in a decrease in the catalytic activity of the material

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