Catalytic ethanolysis of Xiaojihan subbituminous coal to platform chemicals enhanced by pre-oxidation with ozone

Abstract

Xiaojihan subbituminous coal (XSBC) was pre-oxidized by ozone to prepare oxidized XSBC (OXSBC). Then, the ethanolysis was conducted on OXSBC at 300 °C under an initial nitrogen pressure (INP) of 1 MPa for 2 h. On this basis, the influences of pre-oxidation conditions on the content of oxygen-containing functional groups and the yield of soluble portion (SP) from the ethanolysis of XSBC and OXSBC were explored. The research results show that the yield of SP from the OXSBC ethanolysis is higher than that from the XSBC ethanolysis, and the highest yield of SP from the OXSBC ethanolysis reaches 24.9 wt% at 50 °C for 3 h, an increase of 80.4 % compared to the yield of SP from the XSBC ethanolysis. Besides, the magnetic nanosphere Co-CuFe₂O₄ catalyst, prepared by adopting the one-pot hydrothermal method, was applied to the catalytic ethanolysis (CE) of OXSBC3 at 300 °C, 1 MPa INP, and 2 h. The catalyst is noticeably active in the CE of OXSBC3, as it promotes the yields of SP and oxygen-containing organic compounds obtained from the OXSBC3 ethanolysis from 24.9 wt% and 76.25 mg g⁻¹ to 42.8 wt% and 204.16 mg g⁻¹, respectively. The CE of the model compound demonstrates that ethanol is activated by Co-CuFe₂O₄ to release H⁺, H^-, and ⁺CH₂CH₃, which play a crucial role in the conversion of benzyloxybenzene. This study provides a novel approach for acquiring value-added organic chemicals from low-rank coals.