The Cu/ZnO flower-like hierarchical porous structures were successfully synthesized via the cetyltrimethyl ammonium bromide(CTAB) assisted hydrothermal method. The morphology and structure as well as the catalytic per...The Cu/ZnO flower-like hierarchical porous structures were successfully synthesized via the cetyltrimethyl ammonium bromide(CTAB) assisted hydrothermal method. The morphology and structure as well as the catalytic performance for dimethyl oxalate(DMO) hydrogenation to ethylene glycol(EG) were investigated. Through annealing the zinc copper hydroxide carbonate(ZCHC) precursors, the Cu/ZnO flower-like hierarchical porous structures were obtained, which were assembled by a number of porous nanosheets. The catalyst made of these well-defined flower-like hierarchical porous structures with large specific surface area and effective gas diffusion path via the well-aligned porous structures showed higher EG selectivity and yield as compared to the Cu/ZnO catalyst obtained by conventional co-precipitation technique. The results indicated that the Cu/ZnO flower-like hierarchical porous structures have excellent potential application for manufacture of high performance catalysts.展开更多
Hydrogenation of methyl acetate is a key step in ethanol synthesis from dimethyl ether carbonylation and Cu-based catalysts are widely studied.We report here that the hydrogenation activity of Cu/ZnO catalysts can be ...Hydrogenation of methyl acetate is a key step in ethanol synthesis from dimethyl ether carbonylation and Cu-based catalysts are widely studied.We report here that the hydrogenation activity of Cu/ZnO catalysts can be enhanced by the addition of MgO promoter.The evolution of crystal phases during coprecipitation and the physicochemical properties of calcined and reduced catalysts by X-ray diffraction(XRD),thermogravimetric(TG)-mass spectrometry(MS),Brunauer-Emmett-Teller(BET),transmission electron microscopy(TEM),N_(2)O titration,in situ CO-Fourier transform infrared spectroscopy(FTIR)and H_(2)-temperature programmed reduction(H_(2)-TPR)reveal that the promoter effect likely lies in the presence of Mg^(2+).A proper amount of Mg^(2+)mediates the precipitation process of Cu and Zn,leading to preferable formation of aurichalcite(Cu_(x)Zn_(1-x))5(CO_(3))_(2)(OH)_(6) crystal phase and a small amount of basic carbonates such as hydrozincite Zn_(5)(CO_(3))_(2)(OH)_(6) and malachite Cu_(2) CO_(3)(OH)_(2).The presence of aurichalcite strengthens the interaction between Cu and Zn species,and thus enhances the dispersity of CuO species and helps generation of Cu^(+)species on reduced catalysts.Furthermore,the performance of Cu/ZnO catalysts exhibits an optimal dependence on the Mg loading,i.e.,17.5%.However,too much Mg^(2+)in the precipitation liquid prohibits formation of aurichalcite but enhances formation of basic nitrates,leading to a dramatically reduced hydrogenation activity.These findings may find applications for optimization of other Cu-based catalysts in a wider range of hydrogenation reactions.展开更多
基金financially supported by the National Natural Science Foundation of China(21872106,21603244)the Fundamental Research Funds for the Central Universities,China(2042019kf0019)。
基金the financial support of the National Science Foundation of China (No. 21503137 and 61403263)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, the State Education Ministry (No. 20141685)+1 种基金the Liaoning Educational Department Foundation (No. L2015425)the Chinese Scholarship Council (No. 201604910230)
文摘The Cu/ZnO flower-like hierarchical porous structures were successfully synthesized via the cetyltrimethyl ammonium bromide(CTAB) assisted hydrothermal method. The morphology and structure as well as the catalytic performance for dimethyl oxalate(DMO) hydrogenation to ethylene glycol(EG) were investigated. Through annealing the zinc copper hydroxide carbonate(ZCHC) precursors, the Cu/ZnO flower-like hierarchical porous structures were obtained, which were assembled by a number of porous nanosheets. The catalyst made of these well-defined flower-like hierarchical porous structures with large specific surface area and effective gas diffusion path via the well-aligned porous structures showed higher EG selectivity and yield as compared to the Cu/ZnO catalyst obtained by conventional co-precipitation technique. The results indicated that the Cu/ZnO flower-like hierarchical porous structures have excellent potential application for manufacture of high performance catalysts.
基金supported from the National Natural Science Foundation of China(Grant Nos.21972141,21991094,21991090)the“Transformational Technologies for Clean Energy and Demonstration”,Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA21030100)。
文摘Hydrogenation of methyl acetate is a key step in ethanol synthesis from dimethyl ether carbonylation and Cu-based catalysts are widely studied.We report here that the hydrogenation activity of Cu/ZnO catalysts can be enhanced by the addition of MgO promoter.The evolution of crystal phases during coprecipitation and the physicochemical properties of calcined and reduced catalysts by X-ray diffraction(XRD),thermogravimetric(TG)-mass spectrometry(MS),Brunauer-Emmett-Teller(BET),transmission electron microscopy(TEM),N_(2)O titration,in situ CO-Fourier transform infrared spectroscopy(FTIR)and H_(2)-temperature programmed reduction(H_(2)-TPR)reveal that the promoter effect likely lies in the presence of Mg^(2+).A proper amount of Mg^(2+)mediates the precipitation process of Cu and Zn,leading to preferable formation of aurichalcite(Cu_(x)Zn_(1-x))5(CO_(3))_(2)(OH)_(6) crystal phase and a small amount of basic carbonates such as hydrozincite Zn_(5)(CO_(3))_(2)(OH)_(6) and malachite Cu_(2) CO_(3)(OH)_(2).The presence of aurichalcite strengthens the interaction between Cu and Zn species,and thus enhances the dispersity of CuO species and helps generation of Cu^(+)species on reduced catalysts.Furthermore,the performance of Cu/ZnO catalysts exhibits an optimal dependence on the Mg loading,i.e.,17.5%.However,too much Mg^(2+)in the precipitation liquid prohibits formation of aurichalcite but enhances formation of basic nitrates,leading to a dramatically reduced hydrogenation activity.These findings may find applications for optimization of other Cu-based catalysts in a wider range of hydrogenation reactions.
