Effect of the structural modification by carbiding of alumina supported Anderson-type (NH₄)₄[NiMo_{6 − x}W_xO₂₄H₆]·5H₂O on hydrodesulfurization, hydrodechlorination and selective oxidation

The γ-Al₂O₃-supported Anderson-type complexes (NH₄)₄[NiMo_{6 − x}W_xO₂₄H₆]·5H₂O (x = 0, 3 or 6) were carburized with CH₄/H₂ (1:4) mixture (denoted by NiMo_{6 − x}W_x-C/Al). These solid compounds have been tested in a continuous flow, fixed bed reactor for thiophene hydrodesulfurization and polychlorinated biphenyls hydrodechlorination, and in (semi-) batch reactor for dibenzothiophene selective oxidation. The specific surface area and pore volume of NiMo₆-C/Al were greater than those of NiW₆-C/Al and NiMo₃W₃-C/Al. XRD results evidenced a bulk structure typical of Mo₂C, W₂C, WC and NiC. FT-IR verified the absence of bands corresponding to metal oxides. Generally, the catalytic activity toward a given reaction product of NiMo₆-C/Al was greater than those of NiW₆-C/Al and NiMo₃W₃-C/Al due either to its better textural properties or to a more complete transformation of the metal phases into active ones.