升温速率对准东褐煤热解特性及煤焦孔隙结构的影响

为了简化活性焦的制备工艺流程，降低其生产成本，同时拓宽准东褐煤利用途径，需要对准东褐煤热解过程进行更深入的研究。利用热重(TGA)技术考察了准东褐煤在不同升温速率(10,20,30,40和50 ℃/min)热解失重特性并采用等转化率法分析了其动力学参数，同时利用程序升温和快速热解在终温为800 ℃条件下制备出活性焦SC1和SC2。采用氮吸附仪(BET)获得煤焦的孔隙结构参数，利用红外吸收光谱仪(FT-IR)和拉曼仪光谱仪(Raman)分别获取煤焦大分子结构中的官能团和碳骨架结构信息。研究结果表明，基于热重法分析出准东褐煤热解动力学参数，活化能和指前因子变化范围为38.89～229.13 kJ/mol和108.26～1.18×109 s-1。升温速率为30 ℃/min时，有足够热量促进煤焦内部有机结构分解生成大量挥发分，煤焦内部形成合理的温度梯度，阻碍了热缩聚反应造成孔隙阻塞，挥发分顺利释放促进了孔隙结构形成。程序升温热解焦SC1烧失率为46.5%，比表面积为312.91 m2/g，孔容为0.178 cm3/g，平均孔径为2.271 nm;而快速热解焦SC2烧失率为37.3%，比表面积达到424.25 m2/g，孔容为0.189 cm3/g，平均孔径2.342 nm，以微孔为主，结构参数明显好于SC1。快速热解炭化制备活性焦前驱体，促进煤焦生成大量无定形结构和缺陷结构，利于活化阶段微孔孔隙结构的构筑。

Effect of heating rate on pyrolysis characteristics and char structure of Zhundong lignite coal

It is necessary to research thoroughly on the pyrolysis process of Zhundong lignite coal,in order to simplify the preparation process of activated coke,cut the production cost and improve the utilization of the lignite coal.The pyrolysis characteristics of Zhundong lignite coal were investigated by thermos gravimetric analysis (TGA) at different heating rates of 10,20,30,40 and 50 ℃/min.Meanwhile,two kinds of activated carbons (SC1 and SC2) were respectively prepared at 800 ℃ by rapid pyrolysis and temperature programmed pyrolysis.To obtain the information of char on pore structure parameters,organic functional groups and carbon skeleton structures,the chars were characterized by BET,FT IR and Raman.Results showed that the variation range of activation energy and pre exponential factor were 38.89-229.13 kJ/mol and 108.26-1.18×109 s-1,which were analyzed by TGA data for the pyrolysis of Zhundong lignite coal.The efficiency energy was transmitted to promote the decomposition of organic molecules and produce a large amount of volatile during the pyrolysis process with a heating rate of 30℃/min.Simultaneously,a reasonable temperature gradient inside the coal char prevented the pore structure blocking caused by thermal condensation reaction.Also,the smooth release of volatiles promoted the formation of pore structure.The char produced by temperature programmed pyrolysis had the specific surface area of 312.91 m2/g,average pore volume of 0.178 cm3/g and average pore size of 2.271 nm at a burning off rate of 46.5%.The char produced by rapid pyrolysis had the specific surface area of 424.25 m2/g,average pore volume of 0.189 cm3/g and average pore size of 2.342 nm at a burning off rate of 37.3%.A large number of amorphous structures and defect structures were generated in precursor char during the rapid pyrolysis process,which were conducive to the construction of microporous pore structure at activation stage.