HPW supported on ammonium hexafluorosilicate modified Hβ: Efficient catalysts for ethylene glycol and methyl tert‐butyl ether reaction with high selectivity and stability

Abstract

A series of HPW supported on ammonium hexafluorosilicate (AHFs) modified Hβ (30HPW/Hβ‐Si(x)) was successfully prepared. After Hβ zeolite was pretreated with 0.1 mol·L−1 AHF's solution, the Brønsted/Lewis ratio of Hβ‐Si(0.1) increased compared with those of Hβ, and the strong acid density of 30HPW/Hβ‐Si(0.1) decreased compared with those of 30HPW/Hβ respectively. Strong acidic sites and Lewis acid sites are catalytic sites for by‐products diisobutene and ethylene glycol oligomers, which deposited on the catalyst result in the deactivation of catalysts. According to the results of characterization, the internal Si‐OH groups of Hβ (strong acidity sites) were filled with silicon of AHFs. The extraframework aluminum (strong acid sites) was removed by the H+, which is the hydrolysis of AHFs. In addition, the hydrophobicity of 30HPW/Hβ‐Si(0.1) was also improved compared with that of 30HPW/Hβ due to the SiO2/Al2O3 ratio of Hβ increased after treatment by 0.1 mol·L−1 AHFs solution. The 30HPW/Hβ‐Si(0.1) maintained an 80% conversion of methyl tert‐butyl ether and 100% selectivity to ethylene glycol mono‐tert‐butyl ether and DBE ethylene glycol bis‐tert‐butyl ether with 336 h of time on stream.