Transfer hydrogenation(TH) with in situ generated hydrogen donor is of great importance in reduction reactions, and an alternative strategy to traditional hydrogenation processes involving pressurized molecular hydrog...Transfer hydrogenation(TH) with in situ generated hydrogen donor is of great importance in reduction reactions, and an alternative strategy to traditional hydrogenation processes involving pressurized molecular hydrogen. Ammonia borane(NH3BH3, AB) is a promising material of hydrogen storage, and it has attracted much attention in reductive organic transformations owing to its high activity, good atom economy, nontoxicity, sustainability, and ease of transport and storage. This review focuses on summarizing the recent progress of AB-mediated TH reactions of diverse substrates including nitro compounds, nitriles, imines, alkenes, alkynes, carbonyl compounds(ketones and aldehydes), carbon dioxide,and N-and O-heterocycles. Syntheses protocols(metal-containing and metal-free), the effect of reaction parameters, product distribution, and variation of reactivity are surveyed, and the mechanism of each reaction involving the action mode of AB as well as structure-activity relationships is discussed in detail. Finally, perspectives are presented to highlight the challenges and opportunities for AB-enabled TH reactions of unsaturated compounds.展开更多
Ammonia plays an essential role in human production and life as a raw material for chemical fertilizers.The nitrate electroreduction to ammonia reaction(NO_(3)RR)has garnered attention due to its advantages over the H...Ammonia plays an essential role in human production and life as a raw material for chemical fertilizers.The nitrate electroreduction to ammonia reaction(NO_(3)RR)has garnered attention due to its advantages over the Haber-Bosch process and electrochemical nitrogen reduction reaction.Therefore,it represents a promising approach to safeguard the ecological environment by enabling the cycling of nitrogen species.This review begins by discussing the theoretical insights of the NO_(3)RR.It then summarizes recent advances in catalyst design and construction strategies,including alloying,structure engineering,surface engineering,and heterostructure engineering.Finally,the challenges and prospects in this field are presented.This review aims to guide for enhancing the efficiency of electrocatalysts in the NO_(3)RR,and offers insights for converting NO_(3)-to NH_(3).展开更多
NH_(3) in ambient air directly leads to an increase in the aerosol content in the air. These substances lead to the formation of haze to various environmental problems after atmospheric circulation and diffusion. Cont...NH_(3) in ambient air directly leads to an increase in the aerosol content in the air. These substances lead to the formation of haze to various environmental problems after atmospheric circulation and diffusion. Controlling NH_(3) emissions caused by ammonia escaping from mobile and industrial sources can effectively reduce the NH_(3) content in ambient air. Among the various NH_(3) removal methods, the selective catalytic oxygen method (NH_(3)-SCO) is committed to oxidizing NH_(3) to environmentally harmless H_(2)O and N_(2);therefore, it is the most valuable and ideal ammonia removal method. In this review, the characteristics of loaded and core-shell catalysts in NH_(3)-SCO have been reviewed in the context of catalyst structure-activity relationships, and the H_(2)O resistance and SO2 resistance of the catalysts are discussed in the context of practical application conditions. Then the effects of the valence state of the active center, oxygen species on the catalyst surface, dispersion of the active center and acidic sites on the catalyst performance are discussed comprehensively. Finally, the shortcomings of the existing catalysts are summarized and the catalyst development is discussed based on the existing studies.展开更多
CrN powder was synthesized by nitriding Cr metal in ammonia gas flow, and its chemical reaction mechanism and nitridation process were studied. Through thermodynamic calculations, the Cr-N-O predominance diagrams were...CrN powder was synthesized by nitriding Cr metal in ammonia gas flow, and its chemical reaction mechanism and nitridation process were studied. Through thermodynamic calculations, the Cr-N-O predominance diagrams were constructed for different tempera- tures. Chromium nitride formed at 700-1200℃ under relatively higher nitrogen and lower oxygen partial pressures. Phases in the products were then investigated using X-ray diffraction （XRD）, and the Cr2N content varied with reaction temperature and holding time. The results indicate that the Cr metal powder nitridation process can be explained by a diffusion model. Further, Cr2N formed as an intermediate product because of an incomplete reaction, which was observed by high-resolution transmission electron microscopy （HRTEM）. After nitriding at 1000℃ for 20 h, CrN powder with an average grain size of 63 nm was obtained, and the obtained sample was analyzed by using a scanning electron microscope （SEM）.展开更多
基金financially supported by the National Natural Science Foundation of China (21908033,21576059,21666008)Fok Ying-Tong Education Foundation (161030)+1 种基金the Program of Introducing Talents of Discipline to Universities of China (111 Program,D20023)Guizhou Frontiers Science Center for Asymmetric Synthesis and Medicinal Molecules ([2020]004)。
文摘Transfer hydrogenation(TH) with in situ generated hydrogen donor is of great importance in reduction reactions, and an alternative strategy to traditional hydrogenation processes involving pressurized molecular hydrogen. Ammonia borane(NH3BH3, AB) is a promising material of hydrogen storage, and it has attracted much attention in reductive organic transformations owing to its high activity, good atom economy, nontoxicity, sustainability, and ease of transport and storage. This review focuses on summarizing the recent progress of AB-mediated TH reactions of diverse substrates including nitro compounds, nitriles, imines, alkenes, alkynes, carbonyl compounds(ketones and aldehydes), carbon dioxide,and N-and O-heterocycles. Syntheses protocols(metal-containing and metal-free), the effect of reaction parameters, product distribution, and variation of reactivity are surveyed, and the mechanism of each reaction involving the action mode of AB as well as structure-activity relationships is discussed in detail. Finally, perspectives are presented to highlight the challenges and opportunities for AB-enabled TH reactions of unsaturated compounds.
基金supported by the National Natural Science Foundation of China(22202151)Fundamental Research Program of Shanxi Province(202203021212243)。
文摘Ammonia plays an essential role in human production and life as a raw material for chemical fertilizers.The nitrate electroreduction to ammonia reaction(NO_(3)RR)has garnered attention due to its advantages over the Haber-Bosch process and electrochemical nitrogen reduction reaction.Therefore,it represents a promising approach to safeguard the ecological environment by enabling the cycling of nitrogen species.This review begins by discussing the theoretical insights of the NO_(3)RR.It then summarizes recent advances in catalyst design and construction strategies,including alloying,structure engineering,surface engineering,and heterostructure engineering.Finally,the challenges and prospects in this field are presented.This review aims to guide for enhancing the efficiency of electrocatalysts in the NO_(3)RR,and offers insights for converting NO_(3)-to NH_(3).
基金the National Natural Science Foundation of China(No.52000093)Yunnan Fundamental Research Projects(No.202101BE070001-001)National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2019B03).
文摘NH_(3) in ambient air directly leads to an increase in the aerosol content in the air. These substances lead to the formation of haze to various environmental problems after atmospheric circulation and diffusion. Controlling NH_(3) emissions caused by ammonia escaping from mobile and industrial sources can effectively reduce the NH_(3) content in ambient air. Among the various NH_(3) removal methods, the selective catalytic oxygen method (NH_(3)-SCO) is committed to oxidizing NH_(3) to environmentally harmless H_(2)O and N_(2);therefore, it is the most valuable and ideal ammonia removal method. In this review, the characteristics of loaded and core-shell catalysts in NH_(3)-SCO have been reviewed in the context of catalyst structure-activity relationships, and the H_(2)O resistance and SO2 resistance of the catalysts are discussed in the context of practical application conditions. Then the effects of the valence state of the active center, oxygen species on the catalyst surface, dispersion of the active center and acidic sites on the catalyst performance are discussed comprehensively. Finally, the shortcomings of the existing catalysts are summarized and the catalyst development is discussed based on the existing studies.
基金financially supported by the Innovation Foundation of Shanghai University (Nos. sdcx2012033 and sdcx2012062)the Special Research Foundation for Training and Selecting Outstanding Young Teachers of Universities in Shanghai (No. B.37-0407-12-008)+1 种基金the National Natural Science Foundation of China (Nos. 51072112 and 51272154)the Projects of International Cooperation and Exchanges NSFC (No. 51311130110)
文摘CrN powder was synthesized by nitriding Cr metal in ammonia gas flow, and its chemical reaction mechanism and nitridation process were studied. Through thermodynamic calculations, the Cr-N-O predominance diagrams were constructed for different tempera- tures. Chromium nitride formed at 700-1200℃ under relatively higher nitrogen and lower oxygen partial pressures. Phases in the products were then investigated using X-ray diffraction （XRD）, and the Cr2N content varied with reaction temperature and holding time. The results indicate that the Cr metal powder nitridation process can be explained by a diffusion model. Further, Cr2N formed as an intermediate product because of an incomplete reaction, which was observed by high-resolution transmission electron microscopy （HRTEM）. After nitriding at 1000℃ for 20 h, CrN powder with an average grain size of 63 nm was obtained, and the obtained sample was analyzed by using a scanning electron microscope （SEM）.
基金supported by the National Natural Science Foundation of China(51306034)Key Research&Development Projects of Jiangsu Province(BE2015677)the National Basic Research Program of China(2013CB228505)~~
