Comparison of the one-step and two-step plasma-catalytic upgrading of biomass pyrolysis volatiles to bio-fuel

The non-thermal plasma technology by employing pulsed dielectric barrier discharge manner was introduced for bio-fuel preparation, and the HZSM-5 and Ti/HZSM-5 were selected as catalyst respectively. Configurations of plasma-catalytic system were compared from the aspects of bio-fuel yield and property, energy efficiency, bio-fuel composition, reaction pathway and catalyst stability. The results showed that the one-step configuration using Ti/HZSM-5 gave the 15.05% of bio-fuel yield and the total hydrocarbon content of 77.56%, and the expected hydrocarbons were occupied the highest proportion of 68.89%, contributing to the higher hydrogen retention ratio, so the calorific value reached 36.52MJ/kg. The two-step configuration slightly increased the total hydrocarbons (77.79%), while the prolongation of reaction pathway was not conducive to the retention of hydrogen, and the increase of polycyclic aromatic hydrocarbons made some properties worse. The energy consumption of plasma technology occupied 11.63% of the total, which was not so significant in general. Radical reactions and catalytic reactions might be induced in both configurations, and the one-step configuration could show more and stronger multiple interactions. The coking rates of Ti/HZSM-5 employed in the one-step and two-step configurations were 5.24% and 7.50%. To summarize, the one-step configuration using Ti/HZSM-5 showed obvious advantages.