Novel mesoporous TiO2(B) whisker-supported sulfated solid superacid with unique acid characteristics and catalytic performances

Abstract

Mesoporous TiO2(B) whisker was firstly applied as a support for synthesizing the novel sulfated solid superacid (SO42−/TiO2(B)). According to NH3-TPD, TG and Py-IR characterization results, it was found that the similar amount of sulfate group on TiO2(B) and anatase showed significantly different acid characteristics and catalytic performances. The total acid amount of SO42−/TiO2(B) was about 1.8 times as anatase-supported sulfated solid superacid (SO42−/Anatase). Simultaneously, the SO42−/TiO2(B) possessed higher percentage of Brønsted acid and more weak-medium acid strength than SO42−/Anatase. These acidic properties endowed SO42−/TiO2(B) with the increased esterification reaction rate and decreased alkylation byproduct selectivity compared with that of SO42−/Anatase. Structure-performance analysis exhibited that there were more bridged bidentate sulfate groups coordinated to the TiO2(B) in SO42−/TiO2(B), which could induce more Ti cations than that of the chelating one. This was the key factor to be responsible for the unique acid characteristics of SO42−/TiO2(B). The present work provides a novel solid superacid and might open a strategy to mediate the acid characteristic for sulfated solid superacid.