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

A series of HPW supported on ammonium hexafluorosilicate (AHFs) modified H beta (30HPW/H beta-Si(x)) was successfully prepared. After H beta zeolite was pre-treated with 0.1 mol center dot L-1 AHF's solution, the Bronsted/Lewis ratio of H beta-Si (0.1) increased compared with those of H beta, and the strong acid density of 30HPW/H beta-Si(0.1) decreased compared with those of 30HPW/H beta 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 H beta (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/H beta-Si(0.1) was also improved compared with that of 30HPW/H beta due to the SiO2/Al2O3 ratio of H beta increased after treatment by 0.1 mol center dot L-1 AHFs solution. The 30HPW/H beta-Si(0.1) maintained an 80% conversion of methyl tertbutyl 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.

Automated summary

A series of HPW supported on AHFs modified H beta zeolite catalysts were prepared, which showed improved catalytic performance and stability compared to the untreated catalysts.