The present paper reviews in detail the different studies now being conducted by our research team concerning the ultradeep hydrodesulfurization (HDS) of dibenzothiophene (DBT) derivatives over Mo/TiO2 and Mo/TiO2-Al2O3 catalysts. First, a detailed characterization of Mo/TiO2 (P-25 Degussa, 50m2/g) catalysts prepared by equilibrium adsorption technique shows that Mo- species are highly and uniformly dispersed on the surface of titania up to 6.6 wt% MoO3 loading. Above this value, some aggregation of Mo occurs, leading to the formation of bulk MoO3. Below 6.6 wt% MoO3 loading, the Raman spectroscopy data of the calcined samples show that the supported Mo-species possess a highly distorted octahedral MoO6 structure. TiO2-Al2O3 composites were prepared by chemical vapor deposition (CVD) using TiCl4 as a precursor. Using several characterization techniques, we demonstrated that the support composite presents a high dispersion of TiO2 over γ-Al2O 3 without forming precipitates up to ca. 11 wt% loading. Moreover, the textural properties of the composite support are comparable to those of alumina. Under the present sulfidation conditions (673 K, 5%H 2S/95%H2), Mo-species supported on TiO2 are better sulfided than on alumina, as demonstrated using XPS. This can be attributed to the relatively lower interaction between Mo-species and titania. The state of sulfide species supported on the composite support can be considered as a transition state between TiO2 and Al 2O3. However, at relatively higher TiO2 loadings (ca. 11 wt%), Mo/TiO2-Al2O3 catalysts exhibit sulfidability similar to that of Mo/TiO2. The HDS tests conducted in both the laboratory and in industry show that sulfide catalysts supported on TiO2-Al2O3 (ca. 11 wt% TiO 2) are more active than those supported on TiO2 or Al 2O3.
|Original language||English (US)|
|Number of pages||15|
|Journal||Catalysis Surveys from Asia|
|State||Published - Dec 2003|
Bibliographical noteFunding Information:
This work has been supported by the New Energy and Industrial Technology Development Organization under a subsidy of the Ministry of Economy, Trade and Industry.
- Dibenzothiophene (DBT)
- Mo/TiO and Mo/TiO-AlO
- TiO-coated alumina
ASJC Scopus subject areas