A simple technique for preparation of presulfided eggshell MoS2/Al2O3 catalysts and kinetics approach for highly selective hydrodesulfurization of FCC gasoline

A new method for the preparation of presulfided eggshell MoS2/Al2O3 catalysts was developed and the catalysts thus prepared were comprehensively characterized and evaluated in terms of their performance in selective hydrodesulfurization (HDS) of FCC gasoline. Using this method, the eggshell thickness of the catalysts with sharp boundary could be easily regulated by controlling the spreading time and/or the temperature of the Mo precursor ([NH3CH2CH2NH3]2MoS4). The characterization by energy-dispersive spectrometry, X-ray diffraction, and high-resolution transmission electron microscopy indicated that the active phase structures, the particle sizes along the basal direction and the stacking degrees of MoS2 particles on eggshell MoS2/Al2O3 catalysts were similar to these on uniform MoS2/Al2O3 catalysts. Moreover, the results of temperature-programmed reduction and Fourier transformed infrared spectroscopy showed that the method used for the preparation of eggshell catalysts did not affect the nature or number of the MoS2 active sites compared to these of uniform catalysts. The evaluation of the eggshell catalysts performance, along with corresponding uniform catalysts, in selective HDS of FCC gasoline demonstrated while significant effect of intra-particle diffusion resistance in uniform catalysts was present, the eggshell catalysts remarkably reduced such diffusion effect due to a decreased reactant diffusion path, thus showing higher HDS selectivity.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (53 K)Download as PowerPoint slideResearch highlights▶ A new and effective method of self-diffusion to prepare presulfided eggshell MoS2/Al2O3 catalysts was developed. ▶ The eggshell thickness could be easily regulated either by controlling the spreading time or by controlling the temperature of the precursor. ▶ The catalytic tests for FCC gasoline selective HDS reaction over catalysts with eggshell and uniform distributions of the active component revealed the effects of inner diffusion of reactants. ▶ The eggshell catalysts can reduce the inner diffusion resistance and show higher selectivity for the HDS of FCC gasoline. ▶ The optimum reaction temperature should be lower than 280 °C in order to obtain the highest HDS selectivity for eggshell catalysts.