Degradation and regeneration of copper-iron spinel and zeolite composite catalysts in steam reforming of dimethyl ether

The degradation and regeneration behaviors of some composite catalysts of ZSM-5 zeolite and Cu-Fe spinel in steam reforming of dimethyl ether (DME) were systematically studied in various conditions. The degradation of the catalyst could be inhibited by increasing the steam-to-DME ratio and/or lowering the gas hourly space velocity and the reforming temperature. A higher mixing ratio of Cu-Fe spinel to ZSM-5 could also prolong the life of the composite catalysts. The catalyst deactivation was attributable mainly to the carbon deposition in the reaction temperature range of 250-310 degrees C. The regeneration treatment in air at 500-700 degrees C could not only recover the catalytic performance of the degraded catalysts as compared with the fresh catalyst, but could also improve it. We confirmed that the promoting effect of the heat treatment in air was due to the high redispersion of metallic Cu via the re-construction of Cu-Fe spinel as well to as the removal of carbon deposit by burning; the acid property changes over zeolite catalyst were suggested to contribute to the improvement as well. (C) 2010 Elsevier B.V. All rights reserved.