Preparation of heavy bio-oil-based porous carbon by pyrolysis gas activation and its performance in the aldol condensation for aviation fuel as catalyst carrier

Due to the high molecular weight, high viscosity and strong instability of heavy bio-oil from rape straw, it is necessary to explore new high-value utilization methods. Heavy bio-oil based carbon material (HBC) was prepared via carbonization and activation assisted by pyrolysis gas, and the basic Mg-Zr-O catalysts using HBC as the carrier (Mg-Zr-O/HBC) was synthesized for the aldol condensation of cyclopentanone to produce aviation fuel precursor. The effect of activation condition on the physicochemical properties of HBC and Mg-Zr-O/HBC were evaluated, the evolution of gas component before and after activation was explored, and the catalytic performance of Mg-Zr-O/HBC in the aldol condensation of cyclopentanone for the synthesis of aviation fuel was tested. Instead of traditional KOH activation, pyrolysis gas activation was beneficial for the reduced pollution and increased calorific value of the gas, making it an environmentally friendly method. The results showed that the activation of biochar (BOC) was improved with lower pyrolysis gas flow, higher activation temperature and longer activation time. The pore structure of carbon material was significantly improved, and the specific surface area was boosted from 15.25 m2/g3 to 627.61 m2/g3. Mg-Zr-O was evenly distributed on HBC, and a large number of weak and medium basic sites were found in Mg-Zr-O/HBC, which was quite favorable for the aldol condensation. In the aldol condensation of cyclopentanone, Mg-Zr-O/HBC presented the excellent production of the targeted C10+C15 condensates of 84.95 %, which was comparable to that prepared with KOH as activator. After 8 repeated runs, the yield of the targeted condensates remained at 73.33 %. In general, it provided an environmentally friendly strategy for the preparation of HBC and the high-value utilization of pyrolysis gas assisted by pyrolysis gas for the activation of BOC.