Zhangxi Gao,Mei Xiang,Mingyang He,Weiyou Zhou,Jiayao Chen,Jiamin Lu,Zeying Wu,Yaqiong Su
Catalytic conversion of CO2with the surplus glycerol (GL) produced from biodiesel manufacturing has attracted much academic and industrial attention, which proves the urgent requirement for developing high-performance catalysts to afford significant environmental benefits. Herein, titanosilicate ETS-10 zeolite-based catalysts with active metal species introduced by impregnation were employed for coupling CO2with GL to efficiently synthesize glycerol carbonate (GC). The catalytic GL conversion at 170 °C miraculously reached 35.0% and a 12.7% yield of GC was obtained on Co/ETS-10 with CH3CN as a dehydrating agent. For comparison, Zn/ETS- Cu/ETS-10, Ni/ETS-10, Zr/ETS-10, Ce/ETS-10, and Fe/ETS-10 were also prepared, which showed inferior coordination between GL conversion and GC selectivity. Comprehensive analysis revealed that the presence of moderate basic sites for CO2adsorption-activation played a crucial role in regulating catalytic activity. Moreover, the appropriate interaction between cobalt species and ETS-10 zeolite was also of great significance for improving the glycerol activation capacity. A plausible mechanism was proposed for the synthesis of GC from GL and CO2in the presence of CH3CN solvent over Co/ETS-10 catalyst. Moreover, the recyclability of Co/ETS-10 was also measured and it proved to be recycled at least eight times with less than 3% decline in GL conversion and GC yield after a simple regeneration process through calcination at 450 °C for 5 h in air.Keywords:CO2;glycerol;glycerol carbonate;ETS-10 zeolite;cobalt-based catalyst
A detailed investigation was carried out to develop novel pore- and morphology-controllable ETS-10 zeolite. The XRD , N 2 adsorption/desorption, SEM, TEM and 29 Si NMR MAS results proved that a series of hierarchical ETS-10 zeolites was successfully synthesized and more importantly, their morphologies and pore sizes can be freely confined in the desired range under the mesoporogen, morphology- and structure-directing actions of different additives. What's more, the close relationship between various additives and raw materials especially titanium source was discussed, which played an active part in morphology change and hierarchical pores formation. This can be ascribed to the special reducibility of inorganic Ti source, system liquidity and pH, and the enhanced inorganic species dissolution. Finally, the synthesized hierarchical ETS-10 materials were used as heterogeneous catalysts for different biomass-derivatives hydrogenation. Remarkably catalytic performance can be attributed to the unique TiO 6 octahedra carrying two negative charges that strengthens the interaction with active metal species, and thus improves their dispersion. Moreover, the inherent strong Lewis basicity and moderate Lewis acidity favor the oriented conversion of reactants. The controllably hierarchical structure and morphology benefit exposure of more highly dispersed active sites and prolong the catalyst life circle. Especially, an analogous molecular-recognition pattern was found by using sodium lignosulphonate, which is identified as the leading role in noticeably enhancing the catalytic activity and selectivity of the correspondingly ETS-10-based catalyst.
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