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In this work, Co-promoted MoS2 catalysts supported on Al-modified mesoporous silica (HMS and SBA-16) have been prepared by the decomposition of ammonium tetrathiomolybdate and cobalt nitrate precursors in a H2S/H2 gas mixture. The effects of the support morphology and Al incorporation method (one-pot synthesis vs. support's grafting) on the catalyst activity were investigated in the reaction of hydrodesulfurization (HDS) of dibenzothiophene (DBT) conducted in a high-pressure batch reactor at 350 °C and total H2 pressure of 3.3 MPa. The physical and chemical characterization of the oxide precursors and spent catalysts was studied by a variety of several techniques (N2 adsorption–desorption, XRD, SEM, EDS, 27Al MAS NMR, Raman, TG/DTA and DRS UV–vis). The MoS2 phase of all catalysts exhibits similar size (about 2.8 nm) and stacking layers (4). Activity tests showed that CoAT/HMS-Al was most active and selective toward direct desulfurization (DDS) reaction pathway among the catalysts studied. Its catalytic response was similar to that of CoMo/γ-Al2O3 catalyst activated by reductive sulfiding. A linear correlation was found between DBT conversion at a reaction time of 5 h and the specific surface area and mean pore diameter of the catalysts. The best DBT HDS activity showed CoAT/HMS-Al catalyst having the best textural properties among the catalysts studied. Modification of SBA-16 with Al3+ ions by the one-step synthesis method rendered the catalyst more active in the HDS reaction than its modification by grafting. [ABSTRACT FROM AUTHOR]

This article is focused on the problem of the inhibition of the hydrodeoxygenation (HDO) reaction by competitive adsorption of the S-containing compounds on the active sites. The phosphorous effect during co-processing of pyrolysis bio-oils and S-content model compounds over sulfide NiMo/P/HMS-Al catalysts was investigated. A series of NiMo catalysts supported on mesoporous P (x) /HMS-Al materials were prepared and characterized by several techniques. Guaiacol (GUA) was considered as a pyrolysis bio-oils model compound, while the dibenzothiophene (DBT) was used as a model molecule of S-content. The activity test revealed that support modification with 1.1 wt% of P (NM-P1.1) decreased the inhibition of HDO reaction by co-adsorption of DBT on the active sites. With the most active NM-P1.1 catalyst, the formation of a less susceptible to coke formation product (phenol) was favored. The main superiority of sulfided NM-P1.1 catalyst comes from the support decoration with P 2 O 5 nanoparticles leading to its highest Brønsted acidity, the surface enrichment with metal sulfide species as well as with the diminishing of Al leaching from the framework of support during the HDO reaction. The activity tests demonstrated that support modification with phosphorous is an efficient method to solve the problem of the HDS inhibition by the HDO reaction. Unlabelled Image • The NiMoP/HMS-Al 1.1 wt% of P loaded exhibited the best HDO activity and stability during simultaneous HDO and HDS reactions • P loaded is effective method for diminishing the inhibition of HDO reaction by co-adsorption of S-containing compound • Surface P 2 O 5 nanoparticles decoration is effective for lowering Al leaching from the support framework during HDO reaction [ABSTRACT FROM AUTHOR]

A series of trimetallic Ni–Mo–W catalysts supported on cubic mesoporous silica (SBA-16) modified with Ti were prepared with the aim to study the effect of Ti incorporation method (sol-gel against pore volume post-synthesis impregnation) on the physical and chemical properties of the synthetized materials. The catalytic behavior of the sulfided catalysts was evaluated in the reaction of hydrodesulfurization (HDS) of dibenzothiophene (DBT). The catalyst characterization by variety of techniques demonstrated that one-pot synthesis led to Ti ions incorporation into SBA-16 structure and an increase of acidity whereas the post-synthesis method led to formation of octahedral Ti species decorating support's surface. The catalytic behavior was closely linked with the characteristics of their oxide precursors. The catalysts prepared by sol-gel method demonstrated to be more effective toward S-removal from DBT than the catalyst modified by post-synthesis method. The initial HDS activity of the best NiMoW/S16–Ti catalyst doubled that of NiMoW/SBA-16 and a commercial NiMo/γ-Al 2 O 3 which was linked with its better textural properties, acidity and adequate active phases dispersion. The main effect of the support modification with Ti was the enhancement of selectivity toward HYD route products. The best hydrogenation selectivity was archived by Ti incorporation via post-synthesis method which was linked to the formation of curved Mo(W)S 2 layers having a large amount of "brim" HYD sites. Image 1 • HDS activity of NiMoW catalysts was enhanced by Ti incorporation into SBA-16 framework. • The post-synthesis support's decoration with TiO 2 enhanced HYD selectivity. • The bent Mo(W)S 2 layers are formed around of TiO 2 nanoparticles. [ABSTRACT FROM AUTHOR]