Effect of sulfidation atmosphere on the performance of the CoMo/γ-Al2O3 catalysts in hydrodesulfurization of FCC gasoline

•The CoMo/γ-Al2O3 catalysts sulfided in H2S/N2 showed much high selectivity.•Sulfidation of active components in H2S/N2 was more completed than that in H2S/H2.•The catalytic performance was mainly determined by the first sulfidation atmosphere.•The MoS2 morphology differences could better explain the HDS selectivity.•Controlling the slab lengths of supported MoS2 could regulate its HDS selectivity.

The effect of sulfidation atmosphere (H2S/H2 and H2S/N2) on the morphology of (Co)MoS2 particles supported on γ-Al2O3 was studied and the prepared catalysts were evaluated in selective hydrodesulfurization (HDS) of FCC gasoline. It was found that the selectivity of the CoMo/γ-Al2O3 catalysts sulfided in H2S/N2 was 1.8 times as high as that sulfided in H2S/H2, and the catalytic performance was mainly determined by the first sulfidation atmosphere after the impregnation of Mo. The characterization by XRD, HRTEM, XPS, TPR and FT-IR showed that the more completed sulfidation of Mo oxides in H2S/N2 could effectively weaken the strong interaction between the γ-Al2O3 support and active components, thus inducing the decisive influence on the morphology of MoS2 particles. The MoS2 morphology differences could better explain the HDS selectivity. The CoMo/γ-Al2O3 catalyst sulfided in H2S/N2 showed significantly longer slab lengths of supported MoS2 slabs, which effectively decreased the number of active adsorption sites for olefins and thus suppressed the hydrogenation activity of olefins, leading to a desirable higher HDS selectivity. Therefore, a tailor-made catalyst with high HDS selectivity could be developed by optimally controlling the slab lengths of supported MoS2 slabs.

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