Combining the redox properties of Co and the acid properties of Nb in a Co_(3)-Nb-O_(x)catalyst is shown to provide superior performance in the selective catalytic reduction of NO with NH_(3)(NH_(3)-SCR).Co_(3)O_(4)sh...Combining the redox properties of Co and the acid properties of Nb in a Co_(3)-Nb-O_(x)catalyst is shown to provide superior performance in the selective catalytic reduction of NO with NH_(3)(NH_(3)-SCR).Co_(3)O_(4)shows average activity,however,it exhibits a poor N_(2)selectivity.Nb_(2)O_(5)is not active for NH_(3)-SCR.However,the mixed Co_(3)-Nb-O_(x) catalyst shows higher NO conversion and N_(2)selectivity than the single Co_(3)O_(4)and Nb_(2)O_(5)catalysts at 100–300℃.The results of temperature programmed reduction by H_(2)and X-ray photoelectron(XP)spectra indicate that the addition of Nb changes the chemical states of Co and decreases the concentration of Co^(3+) and Oa,adjusting the activity for catalytic oxidation to a moderate level.This suppresses the formation of undesired N_(2)O from the over-oxidation of NH_(3).Incorporation of Co and Nb into one solid synergistically couples their redox behavior and surface acidity,ensuring the high catalytic activity and N2 selectivity in NH3-SCR.展开更多
This paper reviews the recent progress in the electron transfer and interfacial behavior of redox proteins. Significant achievements in the relevant fields are summarized including the direct electron transfer between...This paper reviews the recent progress in the electron transfer and interfacial behavior of redox proteins. Significant achievements in the relevant fields are summarized including the direct electron transfer between proteins and electrodes, the thermodynamic and kinetic properties, catalytic activities and activity regulation of the redox proteins. It has been demonstrated that the electrochemical technique is an effective tool for protein studies, especially for probing into the electron transfer and interfacial behavior of redox proteins.展开更多
The fullerene compound CoC 60(OH) has been prepared by the reaction of C - 60 anion with Co(Ⅱ) hydrous salt under nitrogen atmosphere and refluxing, and the title compound is characterized by FAB-MS, elemental analys...The fullerene compound CoC 60(OH) has been prepared by the reaction of C - 60 anion with Co(Ⅱ) hydrous salt under nitrogen atmosphere and refluxing, and the title compound is characterized by FAB-MS, elemental analysis, FT-IR, XPS, UV-Vis and 1H NMR. The results prove the presence of C-Co and -OH groups in the resultant, and coovalent of Co bonding to C 60. The apparent charge distribution of the resultant appeaers to be Co 2+C - 60(OH) -, and there are three kinds of carbons with different electron density. The result of redox experiment indicates that the reduction potential of the compound is more negative than that of pure C 60.展开更多
Transition metal oxides are regarded as an economical and efficient catalytic alternate for catalytic oxidation of volatile organic compounds(VOCs)emissions.The morphological decoration and the incorporation of extrin...Transition metal oxides are regarded as an economical and efficient catalytic alternate for catalytic oxidation of volatile organic compounds(VOCs)emissions.The morphological decoration and the incorporation of extrinsic metals were demonstrated to be effective strategies for achieving noticeable catalytic improvement.In this work,a novel Co-Ce composite oxides catalyst was obtained by the pyrolysis of ZIF-67 template with the impregnation of certain cerium cations(denoted as ZIF-CoCe).Compared with the reference Co-Ce composite oxides by the sol-gel(denoted as SG-CoCe)and physical mixing(denoted as MIX-CoCe)methods,ZIF-CoCe delivers significantly higher catalytic activity for vinyl chloride oxidation,which are demonstrated to be closely related with its superior redox capacity,more abundance of surface active Co^(3+)sites and adsorbed active oxygen species from oxygen vacancies.In addition,the unique cage-like morphological feature of the Co-based catalysts derived from ZIF-67 template plays a crucial function in kinetically facilitating the mass transfer of catalytic reaction and promoting the catalytic VC oxidation activity.With regard to in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)analysis,enol and carboxylic acid species are identified to be the key organic intermediates during catalytic vinyl chloride oxidation.展开更多
The CeO_(2),Ce-Nb-O_(x) and Nb_(2)O_(5) catalysts were synthesized by citric acid method and the promotion effect of Nb on ceria for selective catalytic reduction(SCR)of NO with NH_(3) was investigated.The catalytic a...The CeO_(2),Ce-Nb-O_(x) and Nb_(2)O_(5) catalysts were synthesized by citric acid method and the promotion effect of Nb on ceria for selective catalytic reduction(SCR)of NO with NH_(3) was investigated.The catalytic activity measurements indicate that the mixed oxide Ce-Nb-O_(x) presents a higher SCR activity than the single oxide CeO_(2) or Nb_(2)O_(5) catalyst.In addition,the Ce-Nb-O_(x) catalyst shows high resistance towards H_(2)O and SO_(2) at 280℃.The Raman,X-ray photoelectron spectra and temperature programmed reduction with H_(2) results indicate that the incorporation of Nb provides abundant oxygen vacancies for capturing more surface adsorbed oxygen,which provides a superior redox capability and accelerates the renewal of active sites.Furthermore,the Fourier transform infrared spectra and temperature programmed desorption of NH_(3) results suggest that niobium pentoxide shows high surface acidity,which is partly retained in the Ce-Nb-O_(x) catalyst possessing a high content of Lewis and Br?nsted acid sites.Therefore,the incorporation of Nb improves both the redox and acidic capacities of Ce-Nb-O_(x) catalyst for the SCR reaction.Here,the redox behavior is primarily taken on Ce and the acidity is well improved by Nb,so the synergistic effect should exist between Ce and Nb.In terms of the reaction mechanism,in situ DRIFT experiments suggest that both NH_(3) on Lewis acid sites and NH_(4)^(+) on Bronsted acid sites can react with NO species,and adsorbed NO and NO_(2) species can both be reduced by NH_(3).In the SCR process,O_(2) primarily acts as the accelerant to improve the redox and acid cycles and plays an important role.This work proves that the combination of redox and acidic properties of different constituents can be feasible for catalyst design to obtain a superior SCR performance.展开更多
An electrochemical study on the redox behavior of indium in the eutectic LiCl-KCl system at 450 ℃ was carried out with the transient techniques of cyclic voltammetry and chronopotentiometry on an inert molybdenum ele...An electrochemical study on the redox behavior of indium in the eutectic LiCl-KCl system at 450 ℃ was carried out with the transient techniques of cyclic voltammetry and chronopotentiometry on an inert molybdenum electrode. The reduction of In(Ⅲ) was found to be a two-step process involving In(Ⅲ)/In(Ⅰ) and In(Ⅰ)/In couples at the potentials of about-0.4 and-0.8 V versus Ag/AgCl, respectively. The redox mechanism was further confirmed by the theoretical evaluation of the number of transferred electrons based on cyclic voltammetry and characterizations of the precipitates generated by the potentiostatic electrolysis. The diffusion coefficients of indium ions in the eutectic LiCl-KCl melt at 450 ℃ were estimated by cyclic voltammetry and chronopotentiometry. The results obtained through the two methods are in fair agreement, delivering an average diffusion coefficient of approximately 1.8×10^(-5)cm^(2)/s for In(Ⅲ), and 1.4×10^(-4)cm^(2)/s for In(Ⅰ).展开更多
基金This work was financially supported by the National Key R&D Projects(No.2019YFC1907101)the National Natural Science Foundation of China(No.U2002212)+2 种基金the State Key Laboratory for Advanced Metals and Materials(No.2019Z-05)the Fundamental Research Funds for the Central Universities(Nos.FRFIDRY-20-005 and FRF-TP-20-097A1Z)the Postdoctor Research Foundation of Shunde Graduate School of University of Science and Technology Beijing(No.2020BH012).
文摘Combining the redox properties of Co and the acid properties of Nb in a Co_(3)-Nb-O_(x)catalyst is shown to provide superior performance in the selective catalytic reduction of NO with NH_(3)(NH_(3)-SCR).Co_(3)O_(4)shows average activity,however,it exhibits a poor N_(2)selectivity.Nb_(2)O_(5)is not active for NH_(3)-SCR.However,the mixed Co_(3)-Nb-O_(x) catalyst shows higher NO conversion and N_(2)selectivity than the single Co_(3)O_(4)and Nb_(2)O_(5)catalysts at 100–300℃.The results of temperature programmed reduction by H_(2)and X-ray photoelectron(XP)spectra indicate that the addition of Nb changes the chemical states of Co and decreases the concentration of Co^(3+) and Oa,adjusting the activity for catalytic oxidation to a moderate level.This suppresses the formation of undesired N_(2)O from the over-oxidation of NH_(3).Incorporation of Co and Nb into one solid synergistically couples their redox behavior and surface acidity,ensuring the high catalytic activity and N2 selectivity in NH3-SCR.
基金support from the National Natural Science Foundation of China (Grant Nos. 90406005 & 20575028) the Program for New Century Excellent Talents in University,the Chinese Ministry of Education (Grant No. NCET-04-0452)
文摘This paper reviews the recent progress in the electron transfer and interfacial behavior of redox proteins. Significant achievements in the relevant fields are summarized including the direct electron transfer between proteins and electrodes, the thermodynamic and kinetic properties, catalytic activities and activity regulation of the redox proteins. It has been demonstrated that the electrochemical technique is an effective tool for protein studies, especially for probing into the electron transfer and interfacial behavior of redox proteins.
文摘The fullerene compound CoC 60(OH) has been prepared by the reaction of C - 60 anion with Co(Ⅱ) hydrous salt under nitrogen atmosphere and refluxing, and the title compound is characterized by FAB-MS, elemental analysis, FT-IR, XPS, UV-Vis and 1H NMR. The results prove the presence of C-Co and -OH groups in the resultant, and coovalent of Co bonding to C 60. The apparent charge distribution of the resultant appeaers to be Co 2+C - 60(OH) -, and there are three kinds of carbons with different electron density. The result of redox experiment indicates that the reduction potential of the compound is more negative than that of pure C 60.
基金Project supported by the National Natural Science Foundation of China(22076088,21607163).
文摘Transition metal oxides are regarded as an economical and efficient catalytic alternate for catalytic oxidation of volatile organic compounds(VOCs)emissions.The morphological decoration and the incorporation of extrinsic metals were demonstrated to be effective strategies for achieving noticeable catalytic improvement.In this work,a novel Co-Ce composite oxides catalyst was obtained by the pyrolysis of ZIF-67 template with the impregnation of certain cerium cations(denoted as ZIF-CoCe).Compared with the reference Co-Ce composite oxides by the sol-gel(denoted as SG-CoCe)and physical mixing(denoted as MIX-CoCe)methods,ZIF-CoCe delivers significantly higher catalytic activity for vinyl chloride oxidation,which are demonstrated to be closely related with its superior redox capacity,more abundance of surface active Co^(3+)sites and adsorbed active oxygen species from oxygen vacancies.In addition,the unique cage-like morphological feature of the Co-based catalysts derived from ZIF-67 template plays a crucial function in kinetically facilitating the mass transfer of catalytic reaction and promoting the catalytic VC oxidation activity.With regard to in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)analysis,enol and carboxylic acid species are identified to be the key organic intermediates during catalytic vinyl chloride oxidation.
基金Project supported by the Postdoctor Research Foundation of Shunde Graduate School of University of Science and Technology Beijing(2020BH012)the National Key Research&Development Projects(2021YFC1910504)+1 种基金the National Natural Science Foundation of China(U2002212)the Fundamental Research Funds for the Central Universities(FRF-IDRY-20-005)。
文摘The CeO_(2),Ce-Nb-O_(x) and Nb_(2)O_(5) catalysts were synthesized by citric acid method and the promotion effect of Nb on ceria for selective catalytic reduction(SCR)of NO with NH_(3) was investigated.The catalytic activity measurements indicate that the mixed oxide Ce-Nb-O_(x) presents a higher SCR activity than the single oxide CeO_(2) or Nb_(2)O_(5) catalyst.In addition,the Ce-Nb-O_(x) catalyst shows high resistance towards H_(2)O and SO_(2) at 280℃.The Raman,X-ray photoelectron spectra and temperature programmed reduction with H_(2) results indicate that the incorporation of Nb provides abundant oxygen vacancies for capturing more surface adsorbed oxygen,which provides a superior redox capability and accelerates the renewal of active sites.Furthermore,the Fourier transform infrared spectra and temperature programmed desorption of NH_(3) results suggest that niobium pentoxide shows high surface acidity,which is partly retained in the Ce-Nb-O_(x) catalyst possessing a high content of Lewis and Br?nsted acid sites.Therefore,the incorporation of Nb improves both the redox and acidic capacities of Ce-Nb-O_(x) catalyst for the SCR reaction.Here,the redox behavior is primarily taken on Ce and the acidity is well improved by Nb,so the synergistic effect should exist between Ce and Nb.In terms of the reaction mechanism,in situ DRIFT experiments suggest that both NH_(3) on Lewis acid sites and NH_(4)^(+) on Bronsted acid sites can react with NO species,and adsorbed NO and NO_(2) species can both be reduced by NH_(3).In the SCR process,O_(2) primarily acts as the accelerant to improve the redox and acid cycles and plays an important role.This work proves that the combination of redox and acidic properties of different constituents can be feasible for catalyst design to obtain a superior SCR performance.
基金the National Natural Science Foundation of China(Nos.51904003,U1703130,51704011)the China Postdoctoral Science Foundation(No.2019M651466)the Foundation of Anhui Province Key Laboratory of Metallurgical Engineering&Resources Recycling of China(Nos.SKF18-01,SKF19-05).
文摘An electrochemical study on the redox behavior of indium in the eutectic LiCl-KCl system at 450 ℃ was carried out with the transient techniques of cyclic voltammetry and chronopotentiometry on an inert molybdenum electrode. The reduction of In(Ⅲ) was found to be a two-step process involving In(Ⅲ)/In(Ⅰ) and In(Ⅰ)/In couples at the potentials of about-0.4 and-0.8 V versus Ag/AgCl, respectively. The redox mechanism was further confirmed by the theoretical evaluation of the number of transferred electrons based on cyclic voltammetry and characterizations of the precipitates generated by the potentiostatic electrolysis. The diffusion coefficients of indium ions in the eutectic LiCl-KCl melt at 450 ℃ were estimated by cyclic voltammetry and chronopotentiometry. The results obtained through the two methods are in fair agreement, delivering an average diffusion coefficient of approximately 1.8×10^(-5)cm^(2)/s for In(Ⅲ), and 1.4×10^(-4)cm^(2)/s for In(Ⅰ).
