Due to the easily controllable interlayer anions, metal cation composition proportion and thickness, which is beneficial to modify surface chemical state and tune bandgap, layered double hydroxides(LDHs) have great pr...Due to the easily controllable interlayer anions, metal cation composition proportion and thickness, which is beneficial to modify surface chemical state and tune bandgap, layered double hydroxides(LDHs) have great promising potential for photocatalytic applications. In this study,we have successfully synthesized the ZnAl–LDH intercalated the single anion between ZnAl cationic interlayer without anionic impurities by using a facile calcining and reconstructing routes. The electron structure and surface chemical state of the prepared products have been investigated by combining the DFT calculation and experimental characterization methods. UV–vis DRS was used to certify the light absorption of the prepared products, and we performed the DFT calculation to demonstrate the density of state and activation of reactant. These results suggested that the ZnAl–LDH–CO3 possessed the more proper band structure and superior ability to activate NO and O2 for accelerating the photocatalytic NO oxidation activity. Moreover, the in situ DRIFTS with dynamically monitoring intermediates and products over the ZnAl–LDH–CO3 was adopted to declare the photocatalytic NO oxidized process during the photocatalytic reaction process. This work illustrated the influence of different interlayer anions to the electron structure and surface chemical state of ZnAl–LDH structure through the experimental verification combined DFT calculation and the photocatalytic NO oxidized process via in situ DRIFTS analyzing, which would provide a novel way to design and fabricate the efficient photocatalysis, and understand the reaction process.展开更多
ZnO-Al2O3 derived from layered double hydroxides （ZnAl-LDH） was successfully applied for dispersion of Pd-Ag bimetallic catalysts for the selective hydrogenation of acetylene to ethylene and the Pd-Ag/ZnO-Al2O3 cata...ZnO-Al2O3 derived from layered double hydroxides （ZnAl-LDH） was successfully applied for dispersion of Pd-Ag bimetallic catalysts for the selective hydrogenation of acetylene to ethylene and the Pd-Ag/ZnO-Al2O3 cata- lyst showed the best catalytic performance among the prepared samples. It was found that the catalyst carrier of ZnO-Al2O3 metal-oxides derived form ZnAl-LDH could significantly suppress the over-hydrogenation of acetylene to obtain the relatively higher selectivity of ethylene. The introduction of Ag restricted efficiently the formation of coke because of the oligomerization reaction, which was further evidenced by thermal gravimetric analysis. The se- lectivity towards ethylene was in the order of Pd-Ag/ZnO-Al2O3〉Pd/ZnO-Al2O3〉Pd-Ag/Al2O3〉Pd/Al2O3 at a high conversion level. As the thermal gravimetric and differential temperature analysis （TG-DTA） revealed, Pd-Ag intermetallic catalyst on the ZnO-Al2O3 support showed less coke formation.展开更多
基金financial support of the Fundamental Research Funds for the Central Universities (2018CDYJSY0055, 106112017CDJXSYY0001, 106112017C DJQJ138802, 106112017CDJXSYY0001, 106112017CDJS K04XK11, and 2018CDQYCL0027)the National Natural Science Foundation of China (Grant no. 21576034)+2 种基金the Innovative Research Team of Chongqing (CXTDG201602014)Project funded by Chongqing Special Postdoctoral Science Foundation (XmT2018043)Technological projects of Chongqing Municipal Education Commission (KJZDK201800801)
文摘Due to the easily controllable interlayer anions, metal cation composition proportion and thickness, which is beneficial to modify surface chemical state and tune bandgap, layered double hydroxides(LDHs) have great promising potential for photocatalytic applications. In this study,we have successfully synthesized the ZnAl–LDH intercalated the single anion between ZnAl cationic interlayer without anionic impurities by using a facile calcining and reconstructing routes. The electron structure and surface chemical state of the prepared products have been investigated by combining the DFT calculation and experimental characterization methods. UV–vis DRS was used to certify the light absorption of the prepared products, and we performed the DFT calculation to demonstrate the density of state and activation of reactant. These results suggested that the ZnAl–LDH–CO3 possessed the more proper band structure and superior ability to activate NO and O2 for accelerating the photocatalytic NO oxidation activity. Moreover, the in situ DRIFTS with dynamically monitoring intermediates and products over the ZnAl–LDH–CO3 was adopted to declare the photocatalytic NO oxidized process during the photocatalytic reaction process. This work illustrated the influence of different interlayer anions to the electron structure and surface chemical state of ZnAl–LDH structure through the experimental verification combined DFT calculation and the photocatalytic NO oxidized process via in situ DRIFTS analyzing, which would provide a novel way to design and fabricate the efficient photocatalysis, and understand the reaction process.
基金This work was supported by the National Natural Science Foundation of China （21476145）. The authors thank Y. F. Liu, Z. L. Guo, L. M. Li, and C. Y. ki for useful discussion and helps. X. P. Gao thanks the China Cheng Da Engineering Co., Ltd for scholarship.
文摘ZnO-Al2O3 derived from layered double hydroxides （ZnAl-LDH） was successfully applied for dispersion of Pd-Ag bimetallic catalysts for the selective hydrogenation of acetylene to ethylene and the Pd-Ag/ZnO-Al2O3 cata- lyst showed the best catalytic performance among the prepared samples. It was found that the catalyst carrier of ZnO-Al2O3 metal-oxides derived form ZnAl-LDH could significantly suppress the over-hydrogenation of acetylene to obtain the relatively higher selectivity of ethylene. The introduction of Ag restricted efficiently the formation of coke because of the oligomerization reaction, which was further evidenced by thermal gravimetric analysis. The se- lectivity towards ethylene was in the order of Pd-Ag/ZnO-Al2O3〉Pd/ZnO-Al2O3〉Pd-Ag/Al2O3〉Pd/Al2O3 at a high conversion level. As the thermal gravimetric and differential temperature analysis （TG-DTA） revealed, Pd-Ag intermetallic catalyst on the ZnO-Al2O3 support showed less coke formation.
