酸化后焦煤表面性和孔隙性变化对吸附热的影响  

Effects of surface and porosity changes on adsorption heat in acidified coking coal

作　　者：张小东[1] 李冰辉 张硕[1] 孙泽源 刘晓[1] ZHANG Xiaodong;LI Binghui;ZHANG Shuo;SUN Zeyuan;LIU Xiao(School of Energy Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,Henan,China)

机构地区：[1]河南理工大学能源科学与工程学院,河南焦作454000

出　　处：《河南理工大学学报（自然科学版）》2024年第1期8-15,共8页Journal of Henan Polytechnic University（Natural Science）

基　　金：国家自然科学基金资助项目(42172198,U1904126);河南省瓦斯地质与瓦斯治理重点实验室-省部共建国家重点实验室培育基地开放基金资助项目(WS2021B02)。

摘　　要：目的为了探究酸化后焦煤的表面性和孔隙性变化对其吸附热的影响,方法选取山西古交矿区焦煤为研究对象,利用盐酸(HCl)和氢氟酸(HF)酸化处理,采用接触角法、低温液氮吸附法和微量热法等测试方法,对比分析了酸化前后焦煤的煤-水接触角、表面张力、孔隙结构等变化,并探讨了这些变化对吸附热的影响机制。结果酸化后焦煤的平均煤-水接触角由75.10°增至80.11°,平均表面张力由44.44 mJ/m^(2)减至39.48 mJ/m^(2),亲水性减弱;酸化后焦煤的总孔容、中孔孔容、比表面积和平均孔径均增大,而微孔和大孔的孔容及比表面积均减小,表明矿物质脱除有利于微孔向中孔转化;同等压力下,随着温度升高,分子热运动加强,分子能量突破固体表面势垒,气体分子成为游离态,导致原煤和脱灰煤的积分吸附热和微分吸附热减小,且脱灰煤的吸附热高于原煤的。结论矿物质会减弱焦煤对气体的吸附能力,且占据焦煤表面的吸附位。因此,酸化后矿物质的脱除导致焦煤表面的吸附位增加,是引起吸附热增大的主要原因。Objective In order to explore the impact of changes in the surface and porosity of coking coal after acidification on the adsorption heat.Methods The coking coal from the Gujiao mining area of Shanxi Province was selected as the research sample.Through hydrochloric acid(HCl)and hydrofluoric acid(HF)treatments,the changes of the coal-water contact angle,surface tension,pore structure before and after acidification were analyzed and the impact mechanism of these changes on adsorption heat was discussed by using the contact angle method,low-temperature liquid nitrogen adsorption method and microcalorimetry method.Results After acidification,the coal-water average contact angle increases from 75.1°to 80.11°,and the average surface tension decreases from 44.44 mJ/m^(2) to 39.48 mJ/m^(2),suggesting that the coal hydrophilicity weakens.Meanwhile, the total pore volume,mesopore volume,specific surface area and average pore diameter of coal increase after acidification,but the pore volume and specific surface area of micropores and macropores decrease. This phenomenon indicates that the removal of minerals is conducive to the transformation of micropores to mesopores.Further,with the increase of temperature,the molecular thermal motion strengthens,and then the molecular energy breaks through the solid surface potential barrier to promote gas molecules to become free states,resulting in a decrease in the integral adsorption heat and differential adsorption heat of raw coal and deashed coal,while the adsorption heat of deashed coal is higher than that of raw coal. Conclusion The existence of minerals can weaken the adsorption capacity of coal to gases and occupy the adsorption sites on the coal surface.Therefore,the increase of the adsorption sites on the surface of coking coal,caused by the removal of minerals after acidification,is the main reason for the increase in adsorption heat.

关 键 词：焦煤 酸化 孔隙性 表面性 吸附热 

分 类 号：TQ531[化学工程—煤化学工程]