NiW/MgO-TiO2 catalysts for dibenzothiophene hydrodesulfurization: Effect of preparation method

In the present work NiW-based catalysts supported on binary MgO-TiO2 mixed oxides (MT-x, were xis the mol% of TiO2) were prepared by aqueous and non-aqueous methods. The results from the characterization techniques (N-2 adsorption/desorption, XRD, UV-vis DRS and HRTEM) were used to establish a relationship between the preparation method and the structural changes of W phases as well the catalytic activity. N-2 adsorption/desorption isotherms showed higher surface areas with the increase on mol% of TiO2. Catalysts characterization showed that the preparation method did not change the original structure of the supports. Furthermore, the presence of NiO and NiWO4 was not observed in any sample, thus, the supports allowed a good dispersion of Ni and W species. DRS spectra showed the presence of W6+ in octahedral coordination and tetrahedral Ni2+. Correlation of the catalytic activity in the DBT HDS reaction and the fraction of W atoms on the edge of WS2 crystallites indicated that the aqueous impregnation on MT25, followed by drying at 393 K leads to the formation of a greater number of catalytically active sites available for interaction with DBT molecules. (C) 2015 Elsevier B.V. All rights reserved.