基于煤基活性炭孔隙结构的矿井低浓度瓦斯吸附分离影响研究
Influence of Pore Structure of Coal-based Activated Carbon on Separation of Low-concentration Gas
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摘要: 以低阶烟煤为原料,通过KOH活化法制备了一系列具有相似表面化学结构但孔隙结构不同的煤基活性炭,用以通过PSA技术从煤矿抽采低浓度瓦斯中富集甲烷。制备前后原料表面形态由光滑致密变为疏松多孔,甲烷和氮气的高压吸附等温线表明制备活性炭对甲烷的吸附能力强于氮气,IAST预测结果也表明在低压阶段制备煤基活性炭对混合组分就具有很高的选择性,但是压力越高,选择性随气相甲烷摩尔分数的上升增加地更快,且选择性主要受0.55~0.85 nm范围内的微孔影响,中孔及大孔不具备选择性。Abstract: In this study, low rank bituminous coal was used as raw material for the preparation of a series of coal based activated carbons(CACs) with similar surface properties but different pore structures, and these CACs could be used to enrich methane from low concentration gas by pressure swing adsorption(PSA) method. The surface morphology of raw material changed from smooth and dense to loose and porous before and after preparation, in addition, the high-pressure adsorption isotherms of methane and nitrogen indicated that the adsorption performance of CACs for methane is stronger than nitrogen. The prediction results by ideal adsorbed solution theory(IAST) method also showed that prepared CACs have a high selectivity for methane and nitrogen mixture at low pressure. But when pressure is higher, the selectivity increases more rapidly with increasing molar fraction of methane in the gas phase. Also, selectivity is mainly affected by micro-pores in the range of 0.55 to 0.85 nm, while meso-pores and macro-pores are not selective.
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Keywords:
- activated carbon /
- chemical activation /
- pore structure /
- low-concentration gas /
- CH4 enrichment
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