Upgrading of 4-methylanisole in a catalytic reactor with electric discharges: A novel approach to O-removal from bio-oils

Lignocellulosic biomass is considered as a very promising alternative to replace fossil sources due to its abundance, consistency with environment and renewability. Conversion of lignin biomass to bio-oil by flash pyrolysis is considered recently due to its feasibility and economical profits. The produced bio-oil contains highly oxygenated compounds that require upgrading in order to be used as a fuel source. In this study, upgrading of 4-methylanisole as a model compound of lignin derived bio-oil was performed in a hybrid catalytic dielectric barrier discharge (DBD) plasma reactor under ambient temperature and atmospheric pressure. Different commercial catalysts including Pt-Cl, Ni-Mo, Co-Mo, Pt-Re and Ni supported on Al2O3 were packed between the two electrodes in the discharge zone. The effects of various catalysts on conversion of 4-methylanisole, discharge power (DP) to the rector, distribution of products and degree of deoxygenation were investigated. The highest 4-methylanisole conversion (98.7%) and deoxygenation degree (47%) were achieved in the presence of Pt-Cl/Al2O3 and Pt-Re/Al2O3 catalysts, respectively. The plasma catalysis system has a lower DP, electrode temperature and breakdown voltage compared to plasma alone. According to the results, the main products were 4-methylphenol, 2,4-dimethylphenol and p-xylene. The results indicated that the catalytic DBD plasma reactor is a promising tool for the upgrading of 4-methylanisole.