Influence of grain size of acidic NiMo/TS-1 on its catalytic performance for hydrodesulfurization of dibenzothiophenes

• NiMo/TS-1 with different grain sizes zeolites were synthesized successfully. • The smaller grain size of NiMo/TS-1 promotes the mass transfer of the reactants and products. • Nano-scale TS-1 tends to exhibit more excellent pore structure and abundant acidic sites. • TS-1 with smaller grain size has more highly-coordinated Ti species, facilitating the sulfurization of Mo species. • NiMo/TS-1 (120 nm) with smaller grain size possesses the optimal desulfurization rates of DBT and 4,6-DMDBT. TS-1 zeolites with different grain sizes were prepared under hydrothermal conditions by tuning the amount of template agent, chelating agent, and temperature, which were further used as supports for the NiMo/TS-1 catalysts. The optimization of synthesis conditions has achieved controllable synthesis of grain sizes from nano-scale to micron-scale. TS-1 with smaller grain sizes possess larger specific surface area, external specific surface area, and pore volume, which can effectively shorten the diffusion path of the sulfide with complex structure. Nano-scale TS-1 has more highly-coordinated Ti species, acting as electronic additives to increase the sulfidation degree of the catalyst. Nano-scale NiMo/TS-1 exhibits higher acidity, which is beneficial for hydrodesulfurization (HDS) reactions. Among the series of NiMo/TS-1 catalysts, NiMo/TS-1 (120 nm) catalyst exhibits the highest dibenzothiophene (DBT, 88.4 %) and 4,6-dimethylbenzothiophene (4,6-DMDBT, 62.1 %) HDS activities.