Deoxygenation of m-cresol on Pt/γ-Al2O3 catalysts

• Pt/Al2O3 catalysts are very active for m-cresol deoxygenation.
• High selectivities to toluene are obtained at 300 °C.
• At lower temperature, methylcyclohexane yield increases.
• Coke deposition follows a parallel mechanism.
• Benzene is formed by toluene demethylation.

In this work the deoxygenation of m-cresol, used as a bio-oil model compound, was studied at atmospheric pressure, using Pt/γ-Al2O3 catalysts. The main products obtained in this system were toluene, benzene and methylcyclohexane. Possible reaction routes for cresol deoxygenation were proposed. The influence of the metal loading, H2/cresol ratio and temperature on products distribution was analyzed. Catalyst deactivation was studied by TPO. The catalysts were characterized by XPS, XRD, BET, TPR, and TEM. Product distribution is explained based on the relative rates of cresol dehydroxylation and demethylation, which leads to toluene and phenol formation, respectively. High selectivity to toluene was obtained with the catalyst with the higher metal loading (1.7 wt.%), while in the case of low metal loading (0.05 wt.%) high yields of light hydrocarbons were obtained. Coke deposition took place preferentially on the metal particles and could be removed by treatment at low temperatures, e.g. 350 °C. This catalyst displays a very good activity and selectivity towards toluene formation at mild temperature (300 °C) and atmospheric pressure, which is a better performance than that already reported for other catalysts.

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