Abstract
Nano gold particle supported on copper zinc catalyst to proceed methanol reforming was investigated in this study. A synthesis method was developed which utilized co-precipitation to produce copper zinc catalyst, gold was added at pH 7 by deposition precipitation method after copper zinc catalyst was precipitated and dried. This synthesis procedure avoids severe gold loss and preserves significant reactivity after calcination. Different gold content, 0%, 0.8%, 3% and 4.3%, on the 30%copper supported on zinc oxide catalyst synthesis by procedure mentioned above, were characterized and tested in a fixed bed reactor through partial oxidation of methanol (POM), steam reforming of methanol (SRM) and oxidative steam reforming of methanol (OSRM) reaction. The addition of gold can suppress the carbon monoxide. In addition, with the increasing gold content, less CO is formed. Furthermore, in the absent of oxygen, addition of gold also decrease the CO formation in SRM reaction. Higher oxygen concentration in POM reaction did not decrease the CO formation significantly, but causing severe hydrogen combustion. Meanwhile, higher oxygen concentration in OSRM reaction leads to higher CO formation. Besides, the addition of gold can lower the initiation temperature. In-situ XAS revealed that without pre-activation, there was no any CuO reduced by methanol on the Cu30ZnO. In contrast, 63% Cu0 and 37% Cu2O were observed on Cu30ZnO with 4.3% gold promoter. Meanwhile, methanol was passed through reduced Au4.3Cu30ZnO and Cu30ZnO at room temperature, Au4.3Cu30ZnO was found having more Cu2O and CuO species which represent more methanol was absorbed on the interface between copper and gold. Besides, we also discovered the initiation temperature of Au3Cu30ZnO was lower to 120oC when 0.7 O/M ration was used in POM reaction while Cu30ZnO was remain at 190oC. Better oxygen absorption ability of gold improved the initiation temperature. Gold is an ideal additive to improve the initiation temperature and decrease CO formation. Lower initiation temperature without pre-activation allow simpler heating module and reduce cost for the reformer.