烃分子在H-FAU分子筛上吸附模拟研究

利用量子力学与分子力学结合的方法研究C_(14),C_(22),C_(30)的直链2-烯烃、芳烃、直链烷烃、环烷烃在H-FAU分子筛上的吸附特性,烃分子吸附能随碳数的增加而增大。烃分子吸附在H-FAU分子筛上,烯烃和芳烃双键碳原子因具有π电子与分子筛B酸中心间形成π-H键,烷烃、环烷烃与B酸中心间有电子诱导作用,烃分子与分子筛骨架间有范德华作用。烃分子碳数的增加会增大分子与分子筛骨架间的范德华作用,不影响烯烃、芳烃与B酸中心间π-H键作用或烷烃、环烷烃与B酸中心间电子诱导作用。不同类型烃分子与分子筛B酸中心间相互作用由大到小的顺序为直链2-烯烃芳烃直链烷烃环烷烃。

SIMULATION STUDY OF HYDROCARBON ADSORPTION ON H-FAU ZEOLITE

Molecular simulation methods were used to study the adsorption of different types of hydrocarbons (2-olefins, aromatics, alkanes and cycloalkanes with carbon chain of C14、C22、C30) on H-FAU zeolite. The results show that the adsorption energy increases as the chain length extends from 14 to 30. The π-H bond is formed between the Bronsted acid sites on the zeolite and the π-electronics of olefins and aromatics, while Van der Waals interaction exists between zeolite framework and molecules through the electronic induction between Bronsted acid sites and σ-electronics of alkanes and cycloalkanes. The increase of carbon number in molecular chain has little effect on π-H interaction or electronic induction interaction, but increases the Van der Waals interactions. The intensity of interactions between molecules and acid sites decreases in the following order: olefins > aromatics > alkanes > cycloalkanes.