Abstract
The conversion of diethyl ether (DEE) to ethene and ethanol was studied at a gas-solid interface over bulk and supported Brønsted solid acid catalysts based on tungsten Keggin heteropoly acids (HPAs) at 130-250 °C and ambient pressure. The yield of ethene increased with increasing reaction temperature and reached 98% at 220-250 °C (WHSV = 2.2 h(-1)). The most active HPA catalysts were silica-supported H(3)PW(12)O(40) and H(4)SiW(12)O(40) and the bulk heteropoly salt Cs(2).(5)H(0).(5)PW(12)O(40). The HPA catalysts outperformed zeolites HZSM-5 and USY reported elsewhere. A correlation between catalyst activity and catalyst acid strength was established, which indicates that Brønsted acid sites play an important role in DEE elimination over HPA catalysts. The results point to the reaction occurring through the consecutive reaction pathway: DEE → C(2)H(4) + EtOH followed by EtOH → C(2)H(4) + H(2)O, where ethene is both a primary product of DEE elimination and a secondary product via dehydration of the primary product EtOH. Evidence is provided that DEE elimination over bulk HPA and high-loaded HPA/SiO(2) catalysts proceeds via the surface-type mechanism.