A novel pre-sulfided hydrotreating catalyst derived from thiomolybdate intercalated NiAl LDHs

A pre-sulfided hydrotreating catalyst was prepared via thiomolybdate intercalated NiAl layered double hydroxides (LDHs) followed by calcination under N2. Upon calcination, the decomposition of thiomolybdate in the interlayer produces MoS2 and releases sulfur to react with nickel in the sheets to produce NiSx. Poorly crystallized MoS2 and NiS2 are formed at 300 °C. However, MoS2 is converted into MoO2 while NiS2 is transformed into NiS and Ni3S2 at higher temperatures. The coordinatively unsaturated sites (CUS) on catalysts and dibenzothiophene (DBT) hydrodesulfurization (HDS) activity decrease as the calcination temperature increases. The catalyst calcined at 300 °C exhibits a little higher HDS activity but 2.3 times higher activity in tetralin (THN) hydrogenation than an oxidic catalyst derived from a molybdate intercalated LDH. Moreover, it shows 2.2 times higher THN hydrogenation activity than a commercial catalyst containing more metals. This could be ascribed to the formation of CUS and non-stoichiometric sulfur species.