The photoreduction of greenhouse gas CO_(2)using photocatalytic technologies not only benefits en-vironmental remediation but also facilitates the production of raw materials for chemicals.Howev-er,the efficiency of C...The photoreduction of greenhouse gas CO_(2)using photocatalytic technologies not only benefits en-vironmental remediation but also facilitates the production of raw materials for chemicals.Howev-er,the efficiency of CO_(2)photoreduction remains generally low due to the challenging activation of CO_(2)and the limited light absorption and separation of charge.Defect engineering of catalysts rep-resents a pivotal strategy to enhance the photocatalytic activity for CO_(2),with most research on met-al oxide catalysts focusing on the creation of anionic vacancies.The exploration of metal vacancies and their effects,however,is still underexplored.In this study,we prepared an In2O3 catalyst with indium vacancies(VIn)through defect engineering for CO_(2)photoreduction.Experimental and theo-retical calculations results demonstrate that VIn not only facilitate light absorption and charge sepa-ration in the catalyst but also enhance CO_(2)adsorption and reduce the energy barrier for the for-mation of the key intermediate*COOH during CO_(2)reduction.Through metal vacancy engineering,the activity of the catalyst was 7.4 times,reaching an outstanding rate of 841.32μmol g(-1)h^(-1).This work unveils the mechanism of metal vacancies in CO_(2)photoreduction and provides theoretical guidance for the development of novel CO_(2)photoreduction catalysts.展开更多
The changes of pH,redox potential,concentrations of soluble iron ions and Cu^2＋ with the time of bioleaching chalcopyrite concentrates by acidithiobacillus ferrooxidans were investigated under the different condition...The changes of pH,redox potential,concentrations of soluble iron ions and Cu^2＋ with the time of bioleaching chalcopyrite concentrates by acidithiobacillus ferrooxidans were investigated under the different conditions of initial total-iron amount as well as mole ratio of Fe（III） to Fe（II） in the solutions containing synthetic extracellular polymeric substances （EPS）.When the solution potential is lower than 650 mV （vs SHE）,the inhibition of jarosites to bioleaching chalcopyrite is not vital as EPS produced by bacteria can retard the contamination through flocculating jarosites even if concentration of Fe（III） ions is up to 20 g/L but increases with increasing the concentration of Fe（III） ions;jarosites formed by bio-oxidized Fe3＋ ions are more easy to adhere to outside surface of EPS space on chalcopyrite;the EPS layer with jarosites acts as a weak diffusion barrier to further rapidly create a high redox potential of more than 650 mV by bio-oxidizing Fe^2＋ ions inside and outside EPS space into Fe^3＋ ions,resulting in a rapid deterioration of ion diffusion performance of the EPS layer to inhibit bioleaching chalcopyrite severely and irreversibly.展开更多
V2O5/TiO2-ZrO2 catalysts containing various amounts of WO3 were synthesized.The catalyst morphologies,catalytic performances,and reaction mechanisms in the selective catalytic reduction of NOx by NH3 were investigated...V2O5/TiO2-ZrO2 catalysts containing various amounts of WO3 were synthesized.The catalyst morphologies,catalytic performances,and reaction mechanisms in the selective catalytic reduction of NOx by NH3 were investigated using in situ diffuse-reflectance infrared Fourier-transform spectroscopy,temperature-programmed reduction（TPR）,X-ray diffraction,and the Brunauer-Emmett-Teller（BET） method.The BET surface area of the triple oxides increased with increasing ZrO2 doping but gradually decreased with increasing WO3 loading.Addition of sufficient WO3 helped to stabilize the pore structure and the combination of WO3 and ZrO2 improved dispersion of all the metal oxides.The mechanisms of reactions using V2O5-9%WO3/TiO2-ZrO2 and V2O5-9%WO3/TiO2were compared by using either a single or mixed gas feed and various pretreatments.The results suggest that both reactions followed the Eley-Ridel mechanism;however,the dominant acid sites,which depended on the addition of WO3 or ZrO2,determined the pathways for NOx reduction,and involved[NH4^＋-NO-Bronsted acid site]^＊ and[NH2-NO-Lewis acid site]^＊ intermediates,respectively.NH3-TPR and H2-TPR showed that the metal oxides in the catalysts were not reduced by NH3 and O2did not reoxidize the catalyst surfaces but participated in the formation of H2O and NO2.展开更多
β-Sialon/ZrN/ZrON composites were successfully fabricated by an in-situ carbothermal reduction？nitridation process with fly ash, zircon and active carbon as raw materials. The effects of raw materials composition an...β-Sialon/ZrN/ZrON composites were successfully fabricated by an in-situ carbothermal reduction？nitridation process with fly ash, zircon and active carbon as raw materials. The effects of raw materials composition and holding time on synthesis process were investigated, and the formation process of the composites was also discussed. The phase composition and microstructure of the composites were characterized by means of XRD and SEM. It was found that increasing carbon content in a sample and holding time could promote the formation of β-Sialon, ZrN and ZrON. The proper processing parameters to synthesize β-Sialon/ZrN/ZrON composites were mass ratio of zircon to fly ash to active carbon of 49：100：100, synthesis temperature of 1550 °C and holding time of 15 h. The average grain size ofβ-Sialon and ZrN（ZrON） synthesized at 1550 °C for 15 h reached about 2 and 1μm, respectively. The fabrication process ofβ-Sialon/ZrN/ZrON composites included the formation ofβ-Sialon and ZrO2 as well as the conversion of ZrO2 to ZrN and ZrON.展开更多
文摘The photoreduction of greenhouse gas CO_(2)using photocatalytic technologies not only benefits en-vironmental remediation but also facilitates the production of raw materials for chemicals.Howev-er,the efficiency of CO_(2)photoreduction remains generally low due to the challenging activation of CO_(2)and the limited light absorption and separation of charge.Defect engineering of catalysts rep-resents a pivotal strategy to enhance the photocatalytic activity for CO_(2),with most research on met-al oxide catalysts focusing on the creation of anionic vacancies.The exploration of metal vacancies and their effects,however,is still underexplored.In this study,we prepared an In2O3 catalyst with indium vacancies(VIn)through defect engineering for CO_(2)photoreduction.Experimental and theo-retical calculations results demonstrate that VIn not only facilitate light absorption and charge sepa-ration in the catalyst but also enhance CO_(2)adsorption and reduce the energy barrier for the for-mation of the key intermediate*COOH during CO_(2)reduction.Through metal vacancy engineering,the activity of the catalyst was 7.4 times,reaching an outstanding rate of 841.32μmol g(-1)h^(-1).This work unveils the mechanism of metal vacancies in CO_(2)photoreduction and provides theoretical guidance for the development of novel CO_(2)photoreduction catalysts.
基金supported by the National Basic Research Program of China (973 Program, 2010CB732304)the National High Technology Research and Development Program of China (863 Program, 2013AA065302)the National Natural Science Foundation of China (51202126)~~
基金Project(2010CB630904) supported by the National Basic Research Program of ChinaProject(50621063) supported by the Chinese Science Foundation for Distinguished Group
文摘The changes of pH,redox potential,concentrations of soluble iron ions and Cu^2＋ with the time of bioleaching chalcopyrite concentrates by acidithiobacillus ferrooxidans were investigated under the different conditions of initial total-iron amount as well as mole ratio of Fe（III） to Fe（II） in the solutions containing synthetic extracellular polymeric substances （EPS）.When the solution potential is lower than 650 mV （vs SHE）,the inhibition of jarosites to bioleaching chalcopyrite is not vital as EPS produced by bacteria can retard the contamination through flocculating jarosites even if concentration of Fe（III） ions is up to 20 g/L but increases with increasing the concentration of Fe（III） ions;jarosites formed by bio-oxidized Fe3＋ ions are more easy to adhere to outside surface of EPS space on chalcopyrite;the EPS layer with jarosites acts as a weak diffusion barrier to further rapidly create a high redox potential of more than 650 mV by bio-oxidizing Fe^2＋ ions inside and outside EPS space into Fe^3＋ ions,resulting in a rapid deterioration of ion diffusion performance of the EPS layer to inhibit bioleaching chalcopyrite severely and irreversibly.
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)~~
文摘V2O5/TiO2-ZrO2 catalysts containing various amounts of WO3 were synthesized.The catalyst morphologies,catalytic performances,and reaction mechanisms in the selective catalytic reduction of NOx by NH3 were investigated using in situ diffuse-reflectance infrared Fourier-transform spectroscopy,temperature-programmed reduction（TPR）,X-ray diffraction,and the Brunauer-Emmett-Teller（BET） method.The BET surface area of the triple oxides increased with increasing ZrO2 doping but gradually decreased with increasing WO3 loading.Addition of sufficient WO3 helped to stabilize the pore structure and the combination of WO3 and ZrO2 improved dispersion of all the metal oxides.The mechanisms of reactions using V2O5-9%WO3/TiO2-ZrO2 and V2O5-9%WO3/TiO2were compared by using either a single or mixed gas feed and various pretreatments.The results suggest that both reactions followed the Eley-Ridel mechanism;however,the dominant acid sites,which depended on the addition of WO3 or ZrO2,determined the pathways for NOx reduction,and involved[NH4^＋-NO-Bronsted acid site]^＊ and[NH2-NO-Lewis acid site]^＊ intermediates,respectively.NH3-TPR and H2-TPR showed that the metal oxides in the catalysts were not reduced by NH3 and O2did not reoxidize the catalyst surfaces but participated in the formation of H2O and NO2.
基金Project(2013AA030902)supported by the National High-tech Research and Development Program of ChinaProjects(51074038,51274057)supported by the National Natural Science Foundation of China+2 种基金Projects(N120402006,N100302002)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(L2012079)supported by the Educational Commission of Liaoning Province of ChinaProject(110215)supported by the Training Program on National College Students Innovation Experiment
文摘β-Sialon/ZrN/ZrON composites were successfully fabricated by an in-situ carbothermal reduction？nitridation process with fly ash, zircon and active carbon as raw materials. The effects of raw materials composition and holding time on synthesis process were investigated, and the formation process of the composites was also discussed. The phase composition and microstructure of the composites were characterized by means of XRD and SEM. It was found that increasing carbon content in a sample and holding time could promote the formation of β-Sialon, ZrN and ZrON. The proper processing parameters to synthesize β-Sialon/ZrN/ZrON composites were mass ratio of zircon to fly ash to active carbon of 49：100：100, synthesis temperature of 1550 °C and holding time of 15 h. The average grain size ofβ-Sialon and ZrN（ZrON） synthesized at 1550 °C for 15 h reached about 2 and 1μm, respectively. The fabrication process ofβ-Sialon/ZrN/ZrON composites included the formation ofβ-Sialon and ZrO2 as well as the conversion of ZrO2 to ZrN and ZrON.
