摘要
The utilization of CO2 as raw material for chemical synthesis has the potential for substantial economic and green benefits. Thermal decomposition of hexamethylene-1,6-dicarbamate （HDC） is a promising approach for indirect utilization of CO2 to produce hexamethylene-1,6-diisocyanate （HDI）. In this work, a green route was developed for the synthesis of HD1 by thermal decomposition of HDC over Co3O4/ZSM-5 catalyst, using chlorobenzene as low boiling point solvent. Different metal oxide supported catalysts were prepared by incipient wetness impregnation （IWI）, PEG-additive （PEG） and deposition precipitation with ammonia evaporation （DP） methods. Their catalytic performances for the thermal decomposition of HDC were tested. The catalyst screening results showed that Co3O4/ZSM-525 catalysts prepared by different methods showed different performances in the order of Co3O4/ZSM-5 25（PEG） 〉 Co3O4/ZSM-525（IWI） 〉 Co3O4/ZSM-525（DP）. The physicochemical properties of Co3O4/ZSM- 52s catalyst were characterized by XRD, FTIR, N2 adsorption-desorption measurements, NH3-TPD and XPS. The superior catalytic performance of Co3O4/ZSM-52S（PEG） catalyst was attributed to its relative surface content of Co3 ＋, surface lattice oxygen content and total acidity. Under the optimized reaction conditions： 6.5% HDC concentration in chlorobenzene, 1 wt% Co3O4/ZSM-525（PEG） catalyst, 250℃ temperature, 2.5 h time, 800 ml.min 1 nitrogen flow rate and 1.0 MPa pressure, the HDC conversion and HDI yield could reach 100% and 92.8% respectively. The Co3O4/ZSM-525（PEG） catalyst could be facilely separated from the reaction mixture, and reused without degradation in catalytic performance. Furthermore, a possible reaction mechanism was proposed based on the physicochemical properties of the Co3O4/ZSM-5 25 catalysts.
The utilization of CO_2 as raw material for chemical synthesis has the potential for substantial economic and green benefits. Thermal decomposition of hexamethylene-1,6-dicarbamate(HDC) is a promising approach for indirect utilization of CO_2 to produce hexamethylene-1,6-diisocyanate(HDI). In this work, a green route was developed for the synthesis of HDI by thermal decomposition of HDC over Co_3O_4/ZSM-5 catalyst, using chlorobenzene as low boiling point solvent. Different metal oxide supported catalysts were prepared by incipient wetness impregnation(IWI), PEG-additive(PEG) and deposition precipitation with ammonia evaporation(DP) methods. Their catalytic performances for the thermal decomposition of HDC were tested. The catalyst screening results showed that Co_3O_4/ZSM-5_(25) catalysts prepared by different methods showed different performances in the order of Co_3O_4/ZSM-5_(25)(PEG)N Co_3O_4/ZSM-5_(25)(IWI)N Co_3O_4/ZSM-5_(25)(DP). The physicochemical properties of Co_3O_4/ZSM-5_(25) catalyst were characterized by XRD, FTIR, N2 adsorption-desorption measurements, NH3-TPD and XPS.The superior catalytic performance of Co_3O_4/ZSM-5_(25)(PEG)catalyst was attributed to its relative surface content of Co^(3+), surface lattice oxygen content and total acidity. Under the optimized reaction conditions: 6.5% HDC concentration in chlorobenzene, 1 wt% Co_3O_4/ZSM-5_(25)(PEG)catalyst, 250 °C temperature, 2.5 h time, 800 ml·min-1 nitrogen flow rate and 1.0 MPa pressure, the HDC conversion and HDI yield could reach 100% and 92.8%respectively. The Co_3O_4/ZSM-5_(25)(PEG)catalyst could be facilely separated from the reaction mixture, and reused without degradation in catalytic performance. Furthermore, a possible reaction mechanism was proposed based on the physicochemical properties of the Co_3O_4/ZSM-5_(25) catalysts.
基金
National Natural Science Foundation of China(21476244 and 21406245)
Youth Innovation Promotion Association CAS
