INFLUENCE OF OXYGEN-CONTAINING, NITROGEN-CONTAINING, AND SULFUR-CONTAINING-COMPOUNDS ON THE HYDRODEOXYGENATION OF PHENOLS OVER SULFIDED COMO GAMMA-AL2O3 AND NIMO/GAMMA-AL2O3 CATALYSTS/

The hydrodeoxygenation (HDO) of phenols is a key reaction of the hydro processing of bio-oils, because phenolic molecules represent an import ant part of these oils and they are among the most difficult to deoxyg enate. This reaction is also a very good reaction test for the charact erization of the hydrogenation and hydrogenolysis functions of hydrotr eating catalysts. In this work, the influence of competitors on the ac tivity and selectivity of 4-methylphenol HDO over conventional CoMo an d NiMo hydrotreating catalysts was evaluated in batch reaction tests. The inhibiting strength followed the order H2O << 2-ethylphenol < H2S < NH3. In all cases, the hydrogenolysis path was more inhibited than t he hydrogenation path, indicating a higher adsorption strength and ele ctrophilicity of associated sites. The inhibition was quantified accor ding to a Langmuir adsorption concept. The deviations from this model were attributed to a distribution of the adsorption strength. As oppos ed to other competitors, hydrogen sulfide slightly promotes the hydrog enation activity of CoMo but not of NiMo. These observations were inte rpreted as the result of an interconversion of the hydrogenolysis and hydrogenation active sites.