Synthesis of γ-alumina by hydrothermal reaction and hydrodesulfurization over the NiMo/γ-Al₂O₃ catalyst

Ammonium aluminum carbonate hydroxide(AACH) as the precursor of γ-alumina was hydrothermally synthesized from pseudo boehmite and ammonium bicarbonate solution, and NiMo/γ-Al₂O₃ was prepared by impregnation. AACH, γ-Al₂O₃ and NiMo/γ-Al₂O₃ samples were characterized by means of XRD, BET, SEM, ²⁷Al MAS NMR, Py-IR and HRTEM. The influences of ammonium bicarbonate concentration and hydrothermal reaction time on the AACH preparation were researched and the performances of the NiMo/γ-Al₂O₃ catalyst in hydrodesulfurization were inestigated. The results indicated that, rod-like AACH with high crystallinity could be synthesized under the conditions of NH₄HCO₃ 2.00 mol/L and hydrothermal time 8 h, and the synthesized γ-Al₂O₃ support had larger specific surface area, pore volume and pore diameter than γ-Al₂O₃ prepared directly from pseudo boehmite. Under the conditions of hydrogen pressure 2 MPa, LHSV 4.0 h^-1 and V(H₂):V(Oil) 300, the conversion of dibenzothiophen in the hydrodesulfurization over the NiMo/Al₂O₃-AC catalyst reached 76.12%.