Hydrogenation of waste PET degraded bis(2-hydroxyethyl)cyclohexane- 1,4-dicarboxylate to 1,4-cyclohexanedimethanol over Cu-based catalysts

Abstract

Upcycling of waste polyethylene terephthalate derived bis(2-hydroxyethyl) cyclohexane-1,4-dicarboxylate (BHCD) to valuable monomer (1,4-cyclohexanedimethanol, CHDM) can decrease the emission of CO2 and microplastics. In this work, a stable Cu-based catalyst (Cu/MgAl2O4) with strong metal-support interaction was synthesized via calcination and reduction of CuMgAl-LDH precursor. The properties of precursor and final catalyst were characterized using XRD, TG-DTA, N2-adsorption, SEM/TEM, H2-TPR, CO2/NH3-TPD and XPS techniques. It was found that Cu/MgAl2O4 has high surface area, strong metal-support interaction and plenty basic sites. Cu/MgAl2O45 exhibited prominent performance for the hydrogenation of PET-derived BHCD to CHDM among the tested Cu/MgAl2O4, Cu/MnAl2O4 and Cu/ZnAl2O4 catalyst. The yield of CHDM over Cu/MgAl2O4 reached 98 % with a complete conversion of BHCD at 240 °C, 4 MPa and 0.525 g.gcat-1.h−1. Besides, it remains its activity for at least 80 h on stream under optimized condition. The structure-performance of these catalysts for the hydrogenation of BHCD to CHDM was discussed.