整体型多孔炭的制备及其对苯和甲苯吸/脱附行为研究

Adsorption and desorption behavior of benzene and toluene on porous carbon monoliths

以酚醛树脂溶液为前驱体,预氧化聚丙烯腈纤维毡为增强体,通过溶胶-凝胶反应、常压干燥、炭化、CO_2活化等工艺制备出高强度、高比表面积的整体型多孔炭。通过SEM、TEM和N_2吸/脱附表征该材料的微观结构及孔结构参数,并采用重量法测得材料对两种典型VOCs(苯和甲苯)的吸/脱附性能。结果表明,所制整体型多孔炭具有典型的纤维增强气凝胶的结构,活化后样品(ACM-3)比表面积可高达1 872 m^2/g,孔容为0.97 cm3/g,该样品对50 ppm苯的吸附量为117 mg/g,对甲苯的吸附量可高达287 mg/g,且对苯和甲苯都具有最快的吸/脱附动力学。采用三种方程对吸附等温线进行拟合,基于微孔填充机理的DR方程对实验结果的关联度最好。此外,整体型多孔炭还具有长期循环使用的稳定性,是一种具有潜在应用价值的室内空气净化材料。

Highly porous carbon monoliths with good mechanical strength were prepared by the sol-gel polymerization of phenolicresin in oxidized polyacrylonitrile fiber felts, ambient drying,carbonization at 800 益 for 2 h and CO2 activation at 950 益 for 1 to 3 h. Their microstructure and pore structure were investigated by SEM,TEM and N2 adsorption. Their adsorption/desorption per-formance for benzene and toluene was measured by the gravimetric method. It is found that the carbon monoliths have a typical fi-ber-reinforced aerogel structure and the sample activated for 3 h （ACM-3） has a well-developed microporous structure with a BET surface area of 1 872 m2/g and pore volume of 0.97 cm3 /g . ACM-3 shows high adsorption capacities of 117 and 287 mg/g for 50 ppm benzene and toluene, respectively,and the fastest adsorption/desorption kinetics. The Langmuir,Freundlich and DR isotherm models are used to fit the experimental adsorption data and the DR model shows the highest correlation coefficient. Moreover, ACM-3 has an excellent cyclic stability. The as-prepared carbon monoliths are promising adsorbents for the adsorption of volatile or-ganic compounds in indoor air purification.