Dual function intensified cracking of waste engine oil to produce alkane-rich oil: Study on the synergistic effect of Fe-Co/MCM41 catalyst and microwave

In order to use microwave catalytic pyrolysis technology to recover hydrocarbon-rich fuel from waste engine oil, a microwave-driven metal Fe and Co modified MCM41 molecular sieve catalyst was constructed, which solves the defects of the MCM41 of high coking rate, easy deactivation, and poor selectivity. The characterization results showed that Fe and Co were successfully supported on MCM41, and compared with other modified catalysts, Fe/Co-MCM41-85:15 (Fe/Co ratio is 1:1) possessed good thermal stability and microwave absorption properties. The pyrolysis oil yield and alkanes content were greatly improved after catalyzed, which reached the values of 71.91 wt% and 97.44%, respectively, while the oxygenates content was reduced to 0.88%. The Lewis and Brønsted acid sites of Fe/Co-MCM41-85:15 and the excellent pore structure stimulated catalytic activity, which could selectively convert waste engine oil into alkane-rich oil with a low oxygen content through hydrogen transfer, catalytic cracking, and deoxygenation. In-depth analysis of the microwave absorption-catalytic mechanism of the Fe/Co-MCM41-85:15catalys and the catalytic mechanism was investigated by density functional theory (DFT). The Fe/Co-MCM41-85:15 catalyst facilitated the conversion of long-chain paraffins in waste oil to saturated light alkanes. After the Fe/Co-MCM41-85:15 catalyst was used three times continuously, the pyrolysis oil yield was still above 65 wt%, showing good catalytic reuse and regeneration performance.