Crucial Role of Weak Acid Sites for Catalytic Performance of Zeolites in Ethyl tert-butyl Ether Synthesis

Abstract

Catalytic activity of different zeolites: H,NH4-form of mordenite-containing rock (H-CMK) and H-Beta with a Si/Al ratio of 15–407 (H-ВЕА) in ethyl tert-butyl ether (ETBE) synthesis in a packed-bed flow reactor at 80–180°C and 1 MPa has been studied. Acid characteristics of zeolites were determined by stepwise (Quasi-Equilibrium) ammonia thermodesorption. Three types of acid sites of different strength has been found, which is marked as weak (ENH3 = 60–75 kJ/mol), medium (ENH3 = 86–123 kJ/mol), and strong (ENH3 = 112–145 kJ/mol). The correlation between ETBE productivity and the concentration of weak acid sites has been found. Thereby, it was established that weak acid sites of zeolites are the active sites in ETBE synthesis.