关键词: TG-DSC, 固相反应, 单相复合体, 二苯并噻酚, 加氢脱硫

Abstract:

Mass loss behavior in air and solid-state reaction mechanism of ammonium molybdate with LaHY were investigated by TG-DSC technique, and the physical structure, specific surface area, and surface acid sites by XRD, BET and NH₃-TPD techniques. It showed that surface speicies of Mo arising from decomposition of (NH₄)₆Mo₇O₂₄·4H₂O, over solid-state reaction of (NH₄)₆Mo₇O₂₄·4H₂O with LaHY, allocates in LaHY molecular sieve cage as molybdenum-oxygen clusters to form a single-phase complex nMoO_x·LaHY. The single-phase complex contributes to the lattice shrinkage, the reduced lattice parameter a₀, and the decrease in specific surface area. The as-prepared nMoO_x·LaHY possesses a slightly variation of weak acid center sites, an increase in medium strong acid center sites, a slightly decrease in strong acid center sites, and an increase in total acid sites, in comaprision with LaHY. The hydrodesulfulrization (HDS) performance of the single-phase complex nMoO_x·LaHY was evaluated by using 0.6% (mass) dibenzothiophene(DBT)/decane as the representative reactants. The conversion of DBT in HDS process at 290℃ and 310℃ over nMoO_x·LaHY catalyst with 5.0% (mass) of Mo loading, reached 56.38% and 88.79% under conditions of 4.0 MPa, 20 h^-1 of space velocity and 500:1 of H₂/oil volumetric ratio, which increased 12 and 28 percentage than that of MoO₃/Al₂O₃ with 20% (mass) of Mo loading, respectively. The nMoO_x·LaHY catalyst exhibited higher activity for DBT HDS reaction.

Key words: TG-DSC, solid-state reaction, single-phase complex, DBT, HDS