Hydrodeoxygenation and hydrodesulfurization co-processing over ReS2 supported catalysts

The hydrodeoxygenation (HDO) of bio-oil can be undertaken together with the hydrodesulphurization (HDS) of gas–oil in order to use already existing refinery infrastructures and to directly obtain a partially bio-sourced fuel. In this work, the HDO of 2-methoxyphenol (guaiacol) and the HDS of 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out over ReS2 catalysts supported on SiO2 and γ-Al2O3. It was observed in the co-processing reactions that the total and HDS conversion rates of 4,6-DMDBT decreased compared to the rates obtained in separate reactions over both catalysts, while the total conversion rate of guaiacol increased under the same conditions. This behavior is probably due to the competitive adsorption between 4,6-DMDBT and 2-methoxyphenol occurring on the same active sites on the catalysts. On the other hand, in co-processing reaction the HDO rate decreased 1.4 times over the ReS2/SiO2 catalyst while it increased 1.9 times over ReS2/Al2O3 catalyst. The observed behavior with the ReS2/Al2O3 catalyst was explained in terms of competitive effects and inhibition of acid sites on this catalyst: the less availability of acid sites disfavored the demethylation route which led to the direct conversion of guaiacol to phenol via demethoxylation, and thus enhancing the HDO rate.