Effect of surface silicon modification of H-beta zeolites for alkylation of benzene with 1-dodecene

Ruimin Li; Shiyong Xing; Shuai Zhang; Minghan Han

doi:10.1039/d0ra00393j

Effect of surface silicon modification of H-beta zeolites for alkylation of benzene with 1-dodecene

RSC Adv. 2020 Mar 10;10(17):10006-10016. doi: 10.1039/d0ra00393j. eCollection 2020 Mar 6.

Authors

Ruimin Li¹, Shiyong Xing¹, Shuai Zhang¹, Minghan Han¹

Affiliation

¹ Department of Chemical Engineering, Beijing Key Laboratory of Green Reaction Engineering and Technology, Tsinghua University Beijing 100084 P. R. China hanmh@tsinghua.edu.cn.

Abstract

H-beta zeolites of 100-200 nm (named BEA-L) and 20-30 nm (named BEA-S) were treated by chemical liquid deposition (CLD) of tetraethyl orthosilicate (TEOS) to improve the selectivity of 2-phenyl linear alkylbenzene (2-LAB) from benzene alkylation with 1-dodecene. The results indicate that H-beta zeolite with a smaller crystal size has a longer lifetime due to shorter channels and less diffusion limitation. The deposited SiO₂ layers passivated the external surface acid sites of the zeolite and made the pores narrower. BEA-L lost more external Brønsted acid sites than BEA-S with the same added amount of TEOS, which was due to the severe aggregation of BEA-S grains. This increased passivation gave BEA-L increased 2-LAB selectivity. And when the added amount of SiO₂ was 7.20 wt% of the parent zeolite, the selectivity of 2-LAB over BEA-L significantly increased from 41.9% to 54.7% while that of BEA-S only increased by 2%.