Characterization of ZnO and TiO2 catalysts to hydrogen production using thermoprogrammed desorption of methanol

Mixed zinc, titanium and alumina oxides were characterized by X-ray diffraction (XRD) and TPD-methanol techniques. The surface properties were correlated with the products from methanol decomposition. XRD results showed that 20% of ZnO supported on Al2O3 and on TiO2/Al2O3 formed zinc aluminate phase. However, 20%ZnO/TiO2 and 20%TiO2/Al2O3 presented the characteristic structure of the oxides as segregated phases. TPD-methanol results for 20%TiO2/Al2O3 sample showed an intense CO desorption, which was associated with a large density of Lewis acid sites due to TiO2 surface and to the Lewis and Brönsted acid sites of alumina. On the other samples, the higher density of basic sites and weak Lewis acid site was related to ZnO presence that increased the CO2 desorption. The high H2/CO2 ratio and the absence of CO and other desorption products showed that ZnO/TiO2 is a promising system to be used as support or catalyst to H2 production employed in fuel cells.