Catalytic hydrodeoxygenation of bio-oil using in situ generated hydrogen in plasma reactor: Effects of allumina supported catalysts and plasma parameters

In this study, hydrodeoxygenation of guaiacol, a lignin derived model compound, has been studied experimentally via a combination of dielectric barrier discharge plasma and catalyst. Cracking of methyl groups in the chemical structure of bio-oil is used to provide the hydrogen which is required for hydrodeoxygenation reaction. In order to maximize the degree of deoxygenation and guaiacol conversion, the effects of operating and plasma parameters including applied voltage, guaiacol and argon flow rate have been examined. Furthermore, performance of plasma alone and catalytic plasma has been compared by filling the active volume of the discharge with different commercial catalysts including Ni, Co-Mo, Ni-Mo, Pt-Re and Pt-Cl supported on Al2O3. The highest guaiacol conversion of 92% and deoxygenation degree of 65% are achieved in the presence of Pt-Cl/Al2O3 and Pt-Re/Al2O3 catalysts, respectively. According to the results, the main products were BTX, phenol, methylphenols and dimethylphenols. Unlike previous studies in which catechol was produced as a major product, in our plasma system phenol can be produced selectively through direct demethoxylation rather than demethylation reaction. It is also evident from the results that the hydrogen challenges of hydrodeoxygenation reaction can be overcome by catalytic DBD plasma reactor. (C) 2018 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.