Performance study on simultaneous tar removal and bio-syngas methanation by combining catalysis with nonthermal plasma

In this work, simultaneous toluene removal and syngas methanation using the combination of packed-bed dielectric barrier discharge and Ni/γ-Al₂O₃ catalyst were conducted with the research object of simulated gasification gas (SGG) containing toluene. The effects of reaction temperature, H₂/CO ratio and H₂O addition on the reaction performances of both toluene removal and SGG methanation were investigated. The results show that high-efficiency simultaneous toluene removal and SGG methanation can be achieved at 400°C under plasma catalysis treatment. When the H₂/CO ratio is 3.2, the toluene removal rate and the tar removal rate are close to 100% and 97%, the CO conversion rate and CH₄ selectivity approach about 88% and 97%, and the energy efficiencies in toluene removal and SGG methanation processes can reach 9.7 g/(kW·h) and 17.3 mol/(kW·h). Both the high H₂/CO ratio and the H₂O addition can promote toluene removal and SGG methanation, and reduce the amount of carbon deposition but increase its graphitized degree. Moreover, high H₂/CO ratio can rise the heating value of SGG and achieve higher energy efficiencies in both toluene removal and SGG methanation processes, while the H₂O addition is difficult to obtain high CH₄ selectivity to increase the heating value and is not conducive to the promotion of energy efficiency in SGG methanation process. In addition, for these two simultaneous processes, the SGG methanation process exerts a significant inhibiting effect on toluene removal, but process of toluene removal has less influence on the other process due to the lower concentration of toluene.