Ultradeep hydrodesulfurization of dibenzothiophene (DBT) derivatives over Mo-sulfide catalysts supported on TiO2-coated alumina composite

Youssef Saih, Kohichi Segawa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

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 languageEnglish (US)
Pages (from-to)235-249
Number of pages15
JournalCatalysis Surveys from Asia
Volume7
Issue number4
DOIs
StatePublished - Dec 1 2003

Keywords

  • Dibenzothiophene (DBT)
  • Mo/TiO and Mo/TiO-AlO
  • TiO-coated alumina

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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