Li Ruimin, Xing Shiyong, Zhang Shuai, Han Minghan
Department of Chemical Engineering, Beijing Key Laboratory of Green Reaction Engineering and Technology, Tsinghua University Beijing 100084 P. R. China
RSC Adv. 2020 Mar 10;10(17):10006-10016. doi: 10.1039/d0ra00393j. eCollection 2020 Mar 6.
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 SiO 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 SiO 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%.
通过正硅酸四乙酯（TEOS）的化学液相沉积（CLD）处理了100 - 200纳米的H-β沸石（命名为BEA-L）和20 - 30纳米的H-β沸石（命名为BEA-S），以提高苯与1-十二碳烯烷基化反应中2-苯基直链烷基苯（2-LAB）的选择性。结果表明，晶体尺寸较小的H-β沸石由于通道较短和扩散限制较小而具有更长的寿命。沉积的SiO层使沸石的外表面酸性位点钝化，并使孔变窄。在相同的TEOS添加量下，BEA-L比BEA-S失去更多的外表面布朗斯台德酸性位点，这是由于BEA-S晶粒的严重聚集。这种增加的钝化作用使BEA-L的2-LAB选择性提高。当SiO的添加量为母体沸石的7.20 wt%时，BEA-L上2-LAB的选择性从41.9%显著提高到54.7%，而BEA-S的选择性仅提高了2%。
