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Heterogeneous catalysis is of great importance in chemical industries. Hence, various approaches are studied to improve catalyst characteristics with the purpose of promoting catalytic reactions. Among them, non‐thermal plasma treatment has attracted more attention due to its low temperature operation, simplicity, and shorter processing time. An extensive review has been performed for better understanding of various aspects of this technique. Unanimously, it is reported that plasma method leads to higher conversion, lower temperature activity and better coke suppression. In light of the investigated literature, application of plasma seems to have potential of starting a revolution in chemical processes. However, it necessitates more works to promote this technology toward industrial application.

In the present work, cracking of a model heavy hydrocarbon (hexadecane) in a nanosecond pulsed catalytic dielectric barrier discharge (DBD) plasma reactor has been investigated. The effect of different commercial catalyst materials based on alumina, titania, and silica has been considered on the reactor performance and products distribution. The reactor performance increases significantly when the discharge zone is packed with catalyst granules. Energy efficiency and hydrogen concentration in the produced gas vary between 36.98 and 194.44 lit/kWh and 17.7% and 63.7%, respectively. The highest energy efficiency was achieved when the plasma was packed with Mo–Ni/Al2O3 catalyst for 52.3 W power input. In this condition, the production rate and concentration of hydrogen have been 108.03 mL/min and 63.7%, respectively. The breakdown voltage is decreased significantly when the reactor is packed with TiO2 based catalyst.

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.

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