Rich-O-Vacancy WO3/ZrO2–Hβ with High Lewis/Brønsted Ratio: An Efficient Catalyst for the Highly Selective Synthesis of Dipropylene Glycol

A series of WO3 supported on 20 wt % ZrO2–Hβ zeolite catalysts (xWO3/20ZrO2–Hβ) were prepared and used as catalysts for the synthesis of dipropylene glycol (DPG) from propylene oxide (PO) and propylene glycol (PG). According to the results of characterization and catalytic activity, the 30WO3/20ZrO2–Hβ has a high proportion of medium–total acid density and Lewis/Brønsted ratio due to the O-vacancy concentration after WO3 loading. The conversion of PO and selectivity to DPG over 30WO3/20ZrO2–Hβ were 97.32% and 74.32%, respectively, under the optimal conditions, and the activity of 30WO3/20ZrO2–Hβ almost maintained unchanged after 720 h on stream. It was demonstrated that the formation of tetrahedral [WO4]2– species induced the formation of O-vacancies and resulted in an increase of Lewis/Brønsted ratio and the proportion of medium–total acid density of the xWO3/20ZrO2–Hβ catalyst, efficiently regulating the adsorption and activation of PG. The high activity of 30WO3/20ZrO2–Hβ is attributed to the high Lewis/Brønsted ratio (3.52) and the O-vacancy concentration (48.83%) of catalysts.