Influence of hydrophilicity and titanium species on activity and stability of Cr/MWW zeolite catalysts for dehydrogenation of ethane with CO2

Abstract

Borosilicate zeolite ERB-1 with MWW topological structure was post-processed to prepare deboroned D-ERB-1, pillared layer MCM-36 and delaminated layer structure ITQ-2. Titanium was introduced into MWW structure by atom-planting method. Cr species were loaded by the impregnation for comparison with the one-pot synthesized Cr-MCM-41 and Cr/TS-1. The results show that Cr(Ⅵ) is the active site for oxidative dehydrogenation of ethane with CO2. As the number of hydroxyl groups on the zeolite increases, the content of CrOx and Cr(VI) loaded also increases. The hydroxyl-anchored Cr(VI) on MWW zeolite is easier to be regenerated. The addition of titanium can enhance the dispersion of Cr on the hydrophilic surface of the MWW zeolite and improve the stability of the catalyst. The presence of surface hydroxyl groups is critical to the activity of CrOx-based catalysts. The CO2 can not only promote the reverse water gas shift reaction but also Bouduoard reaction.