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Abstract: A bifunctional NiPb/ZnO-diatomite-ZSM-5 (NiPb/ZnO-DZSM-5) catalyst for FCC gasoline upgrading by reactive adsorption desulfurization (RADS) coupling olefin aromatization function was prepared by wet-mixed squeezed method to avoid octane number loss from olefins hydro-saturation in traditional RADS processing. The crystalline structure and textural property of as-prepared adsorbents/catalysts were characterized by X-ray powder diffraction (XRD) and N2 adsorption analysis, respectively. Adsorption desulfurization and aromatization activities evaluation of FCC gasoline and model gasoline over different adsorbents/catalysts were investigated. The results showed directly introducing the composite of aromatization catalyst into the reactive adsorption desulfurization adsorbent is difficult to conquer the loss of gasoline octane number from olefin saturation and sustain the ultra deep desulfurization ability of the reactive adsorption desulfurization process simultaneously. However, the prepared Pb-modified Ni/ZnO-DZSM-5 catalysts (by introducing second metal into Ni/ZnO-DZSM-5 catalyst), exhibited improved aromatization and desulfurization performance with low octane number loss. The aromatic concentration in products increased with the additive amount of ZSM-5 in catalyst composition, meanwhile, as the adding Pb cannot destroy the original crystalline phase, Pb-modified NiPb/ZnO-ZSM-5 catalyst can inhibit olefin saturation effectively with high desulfurization activity. Regenerated bifunctional NiPb/ZnO-DZSM-5 catalyst also exhibits excellent desulfurization and aromatization performance with no octane number loss. [Copyright &y& Elsevier]

Graphical abstract Highlights • Sulfiding agent could effectively react with the supported Mo oxide to form intermediate thiosalts. • The usage of sulfiding agent could generate mononuclear and polynuclear ammonium thiosulfate. • The sulfiding conditions could modify the final morphology of active phase. • The large number of Mo nuclear would lead to the high stacking of MoS 2 slabs. • The catalyst with optimal Mo dispersion and ratios of edge sites to rim sites showed high HDS activity. Abstract The influence of sulfiding conditions in the ex-situ presulfidation process on the morphology and performances of CoMoS/γ-Al 2 O 3 catalysts was studied in details for hydrodesulfurization (HDS) of dibenzothiophene. Surface and bulk characterization using XRD, HRTEM, XPS, TPR and FT-IR confirmed that the sulfiding agent mixture of (NH 4) 2 S and elemental S effectively react with the supported Mo oxide to form intermediate thiosalts from mononuclear ammonium thiomolybdates to polynuclear ammonium thiomolybdates, namely the formed thiosalts from (NH 4) 2 MoS 4 to (NH 4) 2 Mo 2 S 12 and (NH 4) 2 Mo 3 S 13 ,which weaken the strong interaction between the γ-Al 2 O 3 support and Mo oxide, resulting in maximum sulfidation of Mo oxide species. Mo species tend to agglomerate as the number of Mo nuclear increases, which further induces significant changes in the morphology of MoS 2 particles. Such observation was further correlated with HDS activity and selectivity. The CoMoS/γ-Al 2 O 3 catalyst with (NH 4) 2 Mo 2 S 12 as intermediate exhibits suitable slab lengths and stacking numbers of MoS 2 slabs with optimal compromise between the Mo dispersion and ratios of edge sites to rim sites, and show the highest HDS activity. Therefore, a tailor-made catalyst with excellent HDS performance could be developed by adjusting the sulfiding conditions through ex-situ presulfidation method. [ABSTRACT FROM AUTHOR]

Binary NiMo, CoMo, NiW, and CoW transition-metal oxide catalyst precursors, were synthesized through a hydrothermal reaction, and highly-loaded hydrodesulfurization (HDS) catalysts were prepared by mixing the precursors with an alumina gel, calcination and sulfidation. The transition-metal oxide catalyst precursors and highly-loaded sulfide catalysts were characterized by XRD, N 2 adsorption–desorption, XRF, and HRTEM. Dibenzothiophene and fluid catalytic cracking (FCC) diesel were employed to evaluate the HDS performance. The crystalline phases of ammonium nickel (or cobalt) molybdate were detected in the NiMo (or CoMo) oxide catalyst precursors, while quasi-amorphous phases were observed for the CoW and NiW oxide precursors. In the sulfided HDS catalysts, typical MoS 2 or WS 2 phases were observed by TEM, while XRD demonstrated that Ni and Co sulfides were present, in accordance with HRTEM results. The catalytic results showed that the binary transition-metal CoMo sulfide catalyst exhibited high direct desulfurization activity and that the NiMo sulfide catalyst had higher HDS and hydrodenitrogenation activities toward the FCC diesel than the other catalysts, with conversions of higher than 99.1% and 99.7%, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] The steric hindrance mainly suppressed the reactivities of S-compounds and olefins. [•] H2S inhibition effect was severe on HDS reactivity, thus decreasing the selectivity. [•] The interconversion of Lewis and Brønsted acid sites explained the H2S inhibition. [•] The HYD pathway of the HDS reaction was principally affected. [•] Catalysts with appropriate acidic sites proportion was effective in selective HDS. [ABSTRACT FROM AUTHOR]

Abstract: Porous ammonium nickel molybdate, a potential precursor for deep hydrodesulfurization catalyst with the formula of (NH4)HNi2(OH)2(MoO4)2, was synthesized by a high-temperature hydrothermal synthesis method. The unsupported NiMoS catalysts with various Ni/Mo ratios were prepared from the precursors. The precursors and catalysts were characterized by nitrogen physisorption, powder XRD, TG–DSC–MS, HRTEM, SEM and evaluated in the continuous HDS of FCC gas oil. The results indicated that the activities of thus-achieved catalysts were much higher than that of commercial NiMo/Al2O3. The catalysts derived from the crystalline ammonium nickel molybdate showed much higher catalytic activity than that obtained from amorphous precursor, which means they could be attractive material system for futural applications. [Copyright &y& Elsevier]

Abstract: Presulfided CoMoS/γ-Al2O3 catalysts with sharp and deep eggshell concentration profiles of Co and Mo were prepared by a simple method and their properties were characterized by EDS, HRTEM, and FT-IR techniques. It was found that the Co eggshell thickness of the as-prepared catalysts could be conveniently regulated by controlled evaporation depth of the pre-soaked n-decane in the outer layer of the catalyst extrudates prior to the impregnation process, and the remaining n-decane in the core of the extrudates could prevent the diffusion of the acetone impregnation solution of Co(NO3)2 into that zone of extrudates. The evaluation results of the catalytic performance in hydrodesulfurization (HDS) of dibenzothiophene (DBT) indicated that the eggshell catalysts showed higher HDS activity than that of the uniform catalyst. That was because the eggshell catalysts could remarkably decrease the internal diffusion limitation effect due to a short diffusion path of the reactant. In addition, the eggshell catalysts could greatly improve the utilization efficiency of the active components. [Copyright &y& Elsevier]