New generation of titanium dioxide support for hydrodesulfurization

Mesoporous titanium oxide with a high specific surface area of 120 m2/g prepared by a novel method developed by Chiyoda was used for supporting molybdenum sulfide. In order to examine the influence of the surface area on the properties of the molybdenum sulfide phase, two different samples of titanium oxide were studied, a commercial one with a surface area of 72 m2/g and that prepared by Chiyoda. Molybdenum was deposited on the TiO2 supports by incipient wetness impregnation with ammonium heptamolybdate in one or two steps depending on the Mo loading. Some samples were also prepared by impregnation of ammonium heptamolybdate basified by ammonia. Raman spectroscopy and XPS were used to examine the nature of the molybdate phase and its dispersion in the oxidic state. HREM and XPS were used for studying the sulfided state. As expected, the maximum amount of well-dispersed molybdenum is higher on the Chiyoda support than on the reference support with a lower surface area. The catalytic properties of the catalysts were studied in dibenzothiophene conversion. For the Chiyoda support, the catalytic activity varied linearly with the Mo loading up to 6–7 Mo/nm2 then became nearly constant for the higher loadings. Much higher activities (six times, expressed per gram of catalyst) were obtained compared to molybdenum sulfide supported on alumina.