Cryochemical Approach To Develop Catalysts for Intensification of the Hydrodesulfurization Reaction

Ni-Mo/Al2O3 and Co-Mo/Al2O3 catalysts were synthesized both by conventional and cryochemical coprecipitation methods, and their performances for hydrodesulfurization of a model fuel have been explored. The catalysts were characterized by Brunauer, Emmett, and Teller analysis, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, atomic force microscopy, temperature programmed desorption, X-ray photoelectron spectroscopy, and Fourier transform infrared. Analyses showed that catalysts prepared by the cryochemical technique have higher dispersion, surface area, and chemical homogeneity compared to the conventionally prepared ones. Hydrodesulphurization of a model fuel, composed of dodecane with a definite concentration of dibenzothiophene as a sulfur compound, was carried out in batch mode using in situ generated hydrogen obtained by ethanol reforming. Experimental results showed that Ni-Mo/Al2O3 catalyst is superior to Co-Mo/Al2O3 for the reaction, and the cryochemical catalyst performed better than the conventional catalyst at all temperatures. The absence of any mass transfer resistance, external and internal is established, and the reaction is intrinsically kinetically controlled. The endothermicity of the reaction was proven by thermodynamic analysis.