煤气化是煤炭高效清洁利用的关键技术,煤气化过程不可避免地产生固体废弃物———气化细渣。目前,细渣处理方式以填埋为主,利用率极低,大量填埋不仅引起环境问题也造成资源浪费。细渣由多孔结构的残炭和矿物质组成,该特性决定了细渣可用来制备多孔材料。将气化细渣中残炭通过泡沫浮选和酸洗法进行分离,分离的残炭经化学活化法可定向调控分级孔结构。结果表明:最佳活化条件为活化温度800℃,活化剂与原料的质量比2∶1,活化时间90min,此条件下制备的分级多孔炭(RC2-800-90)比表面积和孔体积最高,分别为1596m2/g和1.297cm3/g;分级多孔炭表现出优异的CO2吸附性能,其中RC2-800-90的吸附性能最优,在0℃,25℃和50℃时CO2吸附量分别为4.90mmol/g,2.75mmol/g和0.86mmol/g,吸附热在21.2kJ/mol~28.7kJ/mol之间,为典型的物理吸附过程;当吸附温度为25℃时,微孔及孔径小于1.5nm,1.0nm,0.7nm的孔体积和CO2吸附量的相关系数均大于0.8,该相关系数均高于0℃和50℃下孔结构参数和CO2吸附量的相关系数,其中孔径小于1.5nm的孔体积和CO2吸附量的相关系数最大,表明在25℃下孔径小于1.5nm的孔对CO2吸附发挥主要作用,该多孔炭表现出了较大的吸附速率,在1.5min内达到了吸附饱和状态,且经过10次循环吸附后,CO2吸附量几乎没有明显下降,具有较好的循环稳定性。

Coal gasification is a pivotal technology for the efficient and clean utilization of coal. However, the coal gasification fine slag produced during coal gasification is an industrial waste, and most of them are currently treated by landfill, leading to environmental problems and economic inefficiency. The fine slag consists of carbon residue with porous structure and mineral particles. Therefore, fine slag can be used to prepare porous materials. In this study, carbon res-idue was prepared with froth floatation test and acid treatments. Hierarchical porous carbon was synthesized from carbon residue with chemical activation method. The results show that the opti-mum activation conditions for preparation of porous carbon have determined as follows: activa-tion temperature of 800 ℃, the mass ratio of activated agent and raw materials of 2∶1, activa-tion time of 90 min. The surface area and pore volume of RC2-800-90 under the optimum condi-tion is 1 596 m2/g and 1.297 cm3/g, respectively. By using RC2-800-90 sample, the highest CO2 adsorption capacity of 4.90 mmol/g, 2.75 mmol/g and 0.86 mmol/g at 0 ℃, 25 ℃, and 50 ℃ are achieved, respectively. The isosteric heat of adsorption values is 21.2 kJ/mol-28.7 kJ/mol for RC2-800-90, indicating that the adsorption is physical adsorption. CO2 uptake show a great linear tread with VD<1.5 nm for the porous carbon at 25 ℃, and the fitted curve coefficient is above 0.8 for the pore volume of micropores. Furthermore, the sample exhibits fast adsorption kinet-ics, reaching saturation levels in about 1.5 min, and demonstrates excellent regeneration efficien-cy after ten cycles.