부산대학교 도서관

Aiming to optimize the product distribution of the Cu–Al catalytic system in the oxalate hydrogenation reaction as a way to optimize and improve the product structure of the coal-to-ethylene glycol process (Coal-Oxalate-EG), the researchers have investigated the two anchoring sites for anchoring the Cu component that is available in the Al2O3 support. The results show that the catalyst xSB synthesized from Al2O3 enriched with surface –OH functional groups is superior to the catalyst xSol synthesized from Al2O3 enriched with Al3+Penta sites for oxalate conversion, whereas xSol outperforms the xSB catalyst for the formation of alcohol-ether ester chemicals. Using diethyl oxalate (DEO) as feedstock, the reaction temperature of the 1Sol catalyst (235 °C) was higher than that of the 1SB catalyst (205 °C) for the conversion of the same amount of DEO at the same Cu loading. Meanwhile, the chemical selectivity of alcohol ether esters was higher for the 1Sol catalyst (~ 35%) than for the 1SB (~ 20%). Detailed characterization (XRD, NH3-TPD, XPS, in-situ FTIR, TEM, etc.) shows that the Al3+Penta sites are mainly present in the bulk phase of Al2O3, and the number of Al3+Penta sites present on the surface of the carriers is only sufficient to maintain the low content of Cu species in a highly dispersed state. A certain number of Al–OH is still required for the anchoring of the Cu species to the Al2O3 support surface. Therefore, hydroxyl-rich SB carriers are more favorable for the high dispersion of Cu species. Meanwhile, the stronger LAS distributed on the surface of the hydroxyl-rich SB carrier will lead to the decomposition or dehydration of the raw materials and intermediates during the reaction process, resulting in the formation of lower molecular weight products, which is unfavorable to the formation of the alcohol-ether ester products. Based on the detailed reaction data and characterization, a more complete product formation pathway of oxalate in the Cu–Al catalytic system is given, which provides a certain theoretical basis for the development of new coal-based chemical pathways.Graphical Abstract: