Generating hydrogen-rich fuel-cell feeds from dimethyl ether (DME) using Cu/Zn supported on various solid-acid substrates

摘要

Several incipient wetness prepared catalysts containing copper and zinc were prepared in-house and reactor tested for the production of hydrogen from dimethyl ether steam reforming (DME-SR). The incorporation of copper and zinc onto a solid acid substrate (viz., zeolites ZSM-5 and Y with Si/Al = 2.5-140, gamma-Al2O3, and ZrO2) Combined the catalytic components for DME hydrolysis to methanol (MeOH) and methanol steam reforming (MeOH-SR) into a single catalyst. Catalyst characterizations included BET surface areas, metal loading, acidity measurements using isopropyl amine, thermogravimetric uptakes of DME, and X-ray diffraction studies. One co-ion exchange sample was tested and was found to be inactive toward DME-SR because of its inactivity toward methanol steam reforming. The most active catalyst was copper-zinc supported on gamma-Al2O3, reaching an equilibrium predicted hydrogen yield of 89% (steam-to-carbon ratio (S/C) = 1.5, space-time(tau) = 1.0 s, T = 400 degrees C, and P-abs = 0.78 atm). Of the zeolite-supported Cu/Zn catalysts, copper-zinc supported on zeolite ZSM-5 with a Si-Al ratio of 25 was observed to be the most active with a hydrogen yield of 55% (S/C = 1.5, tau = 1.0 s, T = 275 degrees C, and P-abs = 0.78 atm). (C) 2006 Elsevier B.V. All rights reserved.