多孔炭吸附剂的乙烯-乙烷选择性反转机制

Selectivity reversion mechanism of porous carbon for ethane-ethylene separation

烯烃是重要的化工原料,吸附分离技术可在温和工况下实现烯烃纯化,而吸附剂的烷烃选择性是实现高效化工分离过程的关键。基于分子模拟,提出调节孔道尺寸以控制多孔炭优先吸附乙烯或乙烷的选择性反转机制;控制活化条件,实验制备出不同孔径的多孔炭材料并验证了乙烯-乙烷选择性反转规律。结果表明,多孔炭的石墨化表面优先吸附乙烷;随着孔径尺寸的增大,可出现优先吸附乙烯的孔道区间;若孔径进一步增大,多孔炭可回归到优先吸附乙烷的石墨化表面吸附特征。选择性反转机制适用于不同形状的孔道结构。因此,可利用微孔孔道的限域作用放大多孔炭表面的烷烃选择性,并得到高性能的烷烃选择性吸附剂。

Alkenes are important raw materials in chemical industry.Adsorption separation technology can achieve alkene purification under mild working conditions.Adsorbent of alkane selectivity is the key to achieve effective chemical separation processes.With the help of molecular simulation,we proposed the mechanism of tuning ethane/ethylene selectivity by controlling pore size.Porous carbon adsorbents with distinct average pore size,showing ethylene and ethane selectivity,were prepared via different activation processes.The experimentally validated mechanism suggests that:(1)Graphene surface is ethane-selective;(2)Porous carbon undergoes the reversed selectivity of ethane-ethylene-ethane with the increase in its pore size.This mechanism can be applied to porous carbon of different pore shapes.Hence,effective alkane-selective adsorbent can be obtained by amplifying the alkane-selective feature within the confined micropore of the porous carbon adsorbent.