Production of hydrogen via partial oxidation of methanol over bimetallic Au–Cu/TiO 2 catalysts

Abstract

The catalytic activity of Au/TiO 2 (2 wt.% Au), Cu/TiO 2 (2 wt.% Cu) and Au–Cu/TiO 2 (1 wt.% Au–1 wt.% Cu) catalysts were studied for partial oxidation of methanol (POM) to produce H 2. The catalysts were characterized by ICP-AES, XRD, TEM, TPR and XPS analyses. The bimetallic Au–Cu/TiO 2 catalysts are more active, stable and exhibit higher hydrogen selectively with smaller amount of CO compared to the monometallic Au/TiO 2 and Cu/TiO 2 catalysts. The enhanced activity, selectivity and stability of the bimetallic catalysts are due to Au–Cu interaction that creates smaller metal particles, which consequently stabilize the active component for POM to produce hydrogen. The activity of Au–Cu/TiO 2 catalysts at different pH during preparation, calcination temperature and reaction temperature were optimized. The Au–Cu/TiO 2 catalysts prepared at pH 7 and dried at 373 K show higher activity. The catalytic performance at various reaction temperatures shows that the methanol conversion and hydrogen selectivity are increased with rise in temperature. The CO selectivity is increased beyond 548 K. Other possible reactions involved during POM are suggested as methanol combustion, steam reforming, decomposition, reverse water gas shift, water gas shift and CO oxidation.