In this article, an atmospheric dielectric barrier discharge (DBD) plasma reactor was used as a novel tool for the upgrading of bio-oil using anisole as a model compound. The influences of different carrier gases (Ar, H 2 , and He) on the performance of the reactor were carefully studied. The results revealed that the conversion of anisole in He plasma is higher than that in Ar or H 2 plasma. This may be attributed to the more stable and homogeneous discharge of He plasma. It is believed that in all of the experiments phenoxy radical was formed as the primary product of anisole dissociation via electron-attack reactions. Moreover, the most abundant product was phenol, which was formed by the free-radical reaction between phenoxy and H radicals. It was found that the upgrading of anisole involved demethylation, transalkylation, and hydrogenolysis reactions. In addition to phenol, 4-methylanisole, 2-methylphenol, benzene, 4-methylphenol, 2,6-dimethylanisole, and cyclohexane were also formed in the reactor. Furthermore, the effect of applied voltage and pulse frequency on the performance of He plasma were carefully investigated. As the voltage and frequency were increased, the quantity and quality of efficient collisions between active species and anisole molecules increased, resulting in an increase in anisole conversion and specific input energy of the discharge. The highest conversion of anisole was 72.7%, which was obtained in a He plasma at an applied energy of 9 kV and a pulse frequency of 20 kHz. Under these conditions, the average input power and specific input energy of the discharge were 71.2 W and 42.7 kJ/mL. The results imply that the DBD plasma reactor is a promising tool for the upgrading of anisole.

A dielectric barrier discharge (DBD) plasma reactor for upgrading of anisole, a model compound representative of lignin-derived bio-oils, was investigated with helium as a carrier gas. The effects of carrier gas flow rate, liquid anisole feed flow rate, and reactor length on the reactor performance were investigated. As a result of the decomposition of anisole, the most prevalent free radical species that formed is inferred to have been phenoxy, resulting from the breaking of the C methyl −O bond. The residence times of reactive species and feed molecules are inferred to be key parameters affecting the conversion of anisole as well as the distribution of products. The three main classes of reaction of anisole were demethylation to give phenol, transalkylation, yielding 4-methylanisole and methylphenols, and hydrogenolysis of phenol to give benzene. The optimal experimental conditions were the carrier gas flow rate of 100 mL/min, the feed flow rate of 0.1 mL/min, and the outer electrode length of 20 cm; the anisole conversion and input power under these conditions were 72.7% and 71.2 W, respectively.

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