丙酮在分子筛中吸附的模拟研究

Molecular simulation study on influence of pore structure of zeolites on acetone adsorption

挥发性有机化合物(VOCs)是当前诱发雾霾天气的主要污染物之一,其不仅会造成人体出现癌变、畸变,还会与其它污染物反应形成光化学烟雾.丙酮是VOCs的一种,其排放需受到严格控制.研究了孔道结构和压力对丙酮吸附过程的影响,从分子层面解释了其在CHA,BETA,MFI,STT分子筛孔道结构中的吸附规律.结果表明,在室温饱和蒸汽压范围内,丙酮分子在低压下并不吸附于分子筛中,只有当压力超过某一压力后,才开始发生物理吸附现象,并且随着压力的增大吸附量急剧增大,之后逐渐趋于饱和;丙酮在分子筛内部的吸附量随孔隙率的增大而增大;对于CHA和STT等笼型分子筛,丙酮主要吸附于笼腔内;对于MFI和BETA等孔道型分子筛,丙酮优先吸附于孔道交叉部位,少量分布于孔道内.

Volatile Organic Compounds（VOCs）,as one of the major sources of air contaminations,can not only cause canceration,but also lead to photochemistry smog.Acetone is a common chemical of VOCs,whose emissions are strictly controlled.The influence of pore structure of zeolites and pressure on the adsorption processes were investigated.And adsorption behaviors of acetone in CHA,BETA,MFI,STT zeolites were explained from the point of view of molecular size.The results indicated as follows,acetone are not adsorbed in zeolites under low pressure.When the pressure exceeds the specified value,the physical adsorption will happen.As the pressure increase,the adsorption amount of acetone in zeolites increases rapidly,and tends to be a stable state finally.The adsorption capacity increases with the increasing of the accessible volume.Acetone is mainly adsorbed in the cavities of CHA and STT zeolites.Acetone prefers to enter the wide pores of MFI and BETA zeolites because of low resistance,and then extend and deform to pass narrow pore.