Hydrogen production by partial oxidation of methanol over ZnO-promoted Au/Al 2O 3 catalysts

Abstract

Production of hydrogen by partial oxidation of methanol (POM) (CH 3OH + 0.5O 2 → 2H 2 + CO 2) was investigated over Au/Al 2O 3 and ZnO-promoted Au/Al 2O 3 (Au/ZnO/Al 2O 3) catalysts. The catalysts were prepared by deposition–precipitation method and characterized by XRD, TEM and TPR analyses. The addition of ZnO to Au/Al 2O 3 resulted in higher catalytic activity for POM to produce hydrogen. The activity of the catalyst for hydrogen formation increases with increasing the addition of ZnO, and it reaches a maximum when the atomic ratio of Zn to Au is 5/1. The main role of ZnO is associated with the progressive formation of smaller Au particles, which comprise active oxygen species for oxidation of methanol. Catalytic activity of Au/ZnO/Al 2O 3 catalyst at various calcination temperatures shows that the uncalcined sample exhibits higher activity for hydrogen formation. The catalytic performance at various reaction temperatures shows that methanol conversion and hydrogen selectivity are increased with rise in reaction temperature. Other by-products formed are traces of methyl formate at low temperatures and traces of methane at high temperatures along with lesser amount of carbon monoxide.