Steam Reforming of Dimethyl Ether over Coupled Catalysts of CuO-ZnO-Al 2O 3-ZrO 2 and Solid-acid Catalyst

Abstract

Steam reforming (SR) of dimethyl ether (DME) was investigated for the production of hydrogen forfuel cells. The activity of a series of solid acids for DME hydrolysis was investigated. The solid acid catalysts wereZSM-5 [Si/Al = 25, 38 and 50: denoted Z(Si/Al)] and acidic alumina (γ-Al 2O 3) with an acid strength order that was Z(25)>Z(38)>Z(50)>γ-Al 2O 3. Stronger acidity gave higher DME hydrolysis conversion. Physical mixtures containing a CuO-ZnO-Al 2O 3-ZrO 2 catalyst and solid acid catalyst to couple DME hydrolysis and methanol SR wereused to examine the acidity effects on DME SR. DME SR activity strongly depended on the activity for DME hydrolysis. Z(25) was the best solid acid catalyst for DME SR and gave a DME conversion>90% [ T = 240°C, n(H 2O)/ n(DME) = 3.5, space velocity = 1179 ml·(g cat) −1·h −1, and P = 0.1MPa]. The influences of the reaction temperature, space velocity and feed molar ratio were studied. Hydrogen production significantly depended ontemperature and space velocity. A bifunctional catalyst of CuO-ZnO-Al 2O 3-ZrO 2 catalyst and ZSM-5 gave a high H 2 production rate and CO 2 selectivity.