煤中负载氢氧化钙对催化气化和甲烷化反应的影响

以不连沟次烟煤为研究对象,在加压固定床中研究Ca(OH)_2对煤气化及负载Ca(OH)_2煤热解半焦的甲烷化反应活性。结果表明,煤中添加Ca(OH)_2能够明显促进气化反应的进行和甲烷的生成,随着气化温度的升高和负载量的增加,碳转化率增加,但负载量存在饱和点。不同的催化剂负载方式对Ca的分散有一定的影响,进而影响其催化性能。含有Ca的半焦能够明显促进甲烷化的进行,出口气甲烷含量随甲烷化温度和催化剂负载量的升高而增强。采用红外光谱分析揭示了煤负载Ca(OH)_2的离子交换机理和扩散过程,这一过程影响煤气化反应性能。

Effect of Ca(OH)2 catalyst on catalytic coal gasification and methanation

The catalytic gasification performance of Buliangou coal using Ca(OH)₂ as catalyst was investigated at 3.5 MPa and 700-800℃ in a pressurized fixed bed. The effect of gasification temperature, Ca(OH)₂ loading and loading method on coal steam gasification and methanation reaction were examined. The results show that Ca(OH)₂ can enhance the reactivity of char gasification and the formation of CH₄. Increasing temperature and Ca(OH)₂ loading can heighten the carbon conversion, but Ca(OH)₂ loading possesses a saturation point. The gasification reactivity is affected by loading method which determines the Ca(OH)₂ dispersion. The coal char loaded with Ca(OH)₂ shows a great catalytic activity on methanation reaction and the CH₄ content in the product gas increases with the increase of methanation temperature and catalyst loading. The analysis result of coal surface function groups by FT-IR reveals the dispersion mechanism of Ca(OH)₂ into the matrix of coal through ion exchange and diffusion, which is a key factor to improve coal char gasification reactivity.