Regeneration of Deactivated Hierarchical La/Hi-ZSM-5 for Catalytic Pyrolysis of Rape Straw Assisted by Ozone from Nonthermal Plasma
Xiaohua Li, Zhichao Lv, Shanshan Shao, Yongchen Zhu, Jingfeng Cheng, Wenbin Dong
Abstract
Regeneration of deactivated hierarchical La/Hi-ZSM-5 zeolites at a low temperature of 150–300 °C by a nonthermal plasma (NTP) spray system with oxygen as a gas source was investigated, and a catalytic test was performed to understand their performance in the upgrading of pyrolysis vapor from rape straw. The results showed that the concentration of ozone as an active species was highly controllable. The coke on the deactivated catalysts was almost completely removed (97.4%) at an optimized temperature of 250 °C; the skeleton structure of the catalysts was not destroyed by NTP. The total volume of acid sites returned to the original value of 96.5%; the specific surface area and pore volume of R-250 returned to 97.0%. The regenerated catalysts (R-250) showed optimal catalytic performance. The bio-oil obtained over R-250 presented the highest heating value of 36.48 MJ/kg, the highest hydrocarbon content of 40.51%, the highest pH value of 5.95, and the lowest viscosity of 5.69 mm2/s. After five cycles of catalysis-regeneration, it was found that the content of hydrocarbons in the oil sample could be maintained at 84.6% of that in the original catalytic test, indicating that the catalyst activity remained excellent after cycles. Generally, NTP is an efficient technology for the regeneration of deactivated catalysts without destroying its skeleton structure because of the low temperature.