介孔活性炭的制备及其高湿储甲烷性能

天然气是一种清洁能源,作为汽车代用燃料以及从天然气开采地到各用户单位之间的运输,都需要有效的存储技术.天然气水合物（NGH）能够降低甲烷存储的成本,而多孔材料孔内生成气体水合物能够有效提高储气密度,本研究目的是合成在孔内能够生成甲烷水合物的低成本高性能吸附剂.首先以农业废弃物玉米芯为原料,采用KOH活化法制备活性炭,其湿储甲烷最优合成条件为：在400,℃炭化30,min,碱炭质量比5∶1、850,℃活化1.0,h合成出C-8高性能活性炭,其孔容达到2.264,cm^3/g,比表面积为2 993,m^2/g,孔径分布主要集中在2～3,nm.合成的C-8是非常好的甲烷湿储吸附剂,在水炭比为3.68时在9.40,MPa下CH4达到最大吸附量为69.66%,是其干燥样品最大吸附量的3.25倍,并可以在较大压力范围内使存储的甲烷提供平稳的放气量,有望作为新型的甲烷水合物存储吸附剂应用于天然气汽车上.

Methane Sorption on Activated Carbon Synthesized from Corncobs with Presence of Water

Natural gas is a clean fuel with relatively abundant resources. The storage cost of natural gas hy- drates （NGH） is 26% lower than that of compressed natural gas （CNG）, with much more methane stored in porous materials in the presence of water. In this study, the activated carbons with high surface area and high mesopore pore volume were prepared from corncobs by KOH activation. The optimum synthesis is realized under the condition of carbonization at 400 ~C for 30 min and then activation at 850 ℃ for 1.0 h, with the mass ratio of KOH to sample of 5 ： 1. The C-8 activated carbon has the highest pore volume of 2.264 cm3/g among all the activated carbons synthe- sized, its specific surface area is 2 993 m2/g, and its pore size is mainly 2--3 nm. The sorption capacity of methane in the C-8 activated carbon for storage is very high in the presence of water. The highest sorption amount of 69.66% was recorded at 275 K and 9.40 MPa, which is 225% higher than the largest sorption capacity observed in dry acti- vated carbon. So the C-8 activated carbon can be applied as methane storage sorbent in natural gas vehicles.