Osvaldo F. Gorriz

Characterization of Cu/SiO2 catalysts prepared by ion exchange for methanol dehydrogenation

Abstract A series of copper on silica catalysts prepared by using the ion exchange methods with copper loading between 0.45 and 3 wt% have been studied by means of different techniques such as TPR, EPR, XANES, XRD, XRF, BET and methanol dehydrogenation reaction. The TPR patterns showed two well-defined peaks with maxima between 250–350°C and 600–650°C. The first one (peak I) corresponds to two contributions: (i) the one step reduction (Cu 2+ to Cu 0 ) of a low interacted species (S 1 ), and (ii) the partial reduction (Cu 2+ to Cu 1+ ) of a highly dispersed and surface interacted species (S 2 ). The second TPR peak (peak II) observed at a higher temperature corresponds to the second step reduction (Cu 1+ to Cu 0 ) of the S 2 species. In addition, it has been found out that Cu 0 and not Cu 2+ is the active site for methanol dehydrogenation to methyl formate.

Temperature-programmed desorption study of the acidic properties of γ-alumina

Temperature-programmed desorption was used to investigate the acidic properties of a commercial γ-alumina. A model which accurately interprets the thermodesorption spectra was developed by means of the Monte Carlo method. A discrete distribution in strength was observed and the relative abundance of the different types of active sites was determined.

Synergy in the SnMoO catalysts: The selective oxidation of methanol

Abstract This work deals with the performance of mechanical mixtures of SnO 2 and MoO 3 (prepared separately) in the selective oxidation of methanol. Synergetic cooperations occur between these phases in the oxidation of methanol. The catalysts are investigated by different techniques (XRD, XPS, SSA, DTA, Redox cycles and EPR) in order to explain the catalytic behavior. Catalytic activities of artificially contaminated phases by impregnation are also measured. Methanol conversion and selectivity to methyl formiate are closely related to the increase in the redox capacity of the catalyst and to the appearance of Mo 5+ ions. The synergy in the catalytic activity might be accounted by the creation of new active sites.

Methanol steam reforming over Cu/CeO2 catalysts: influence of zinc addition

Methanol steam reforming reaction was studied over Cu(5 wt.%)/CeO2 with and without the presence of Zn. The Zn addition decreased the Cu+2 reducibility and increased the oxygen mobility of ceria. The main products were CO2 and H2 with small amount of CO. Selectivity to CO decreased with the Zn addition and it was lower at lower reaction temperatures and lower space velocities. At 230 oC and W/FMeOH = 648 g min mol-1 selectivities to H2 and to CO2 were 100% on Zn/Cu/Ce. The catalytic results indicated that CO was mainly a secondary product formed from reverse water gas shift reaction.