Photo-assisted SCR(PSCR) offers a potential solution for removal of NO at room temperature. MnTiO_(x)as PSCR catalyst exhibits superior performance with NO removal of 100% at the room temperature. Electron paramagneti...Photo-assisted SCR(PSCR) offers a potential solution for removal of NO at room temperature. MnTiO_(x)as PSCR catalyst exhibits superior performance with NO removal of 100% at the room temperature. Electron paramagnetic resonance(EPR) analysis revealed the presence of numerous oxygen vacancies on MnTiO_(x). Optical carrier density functional theory(DFT) calculations showed that the threedimensional orbital hybridization of Mn and Ti is significantly enhanced under light irradiation. The MnTiO_(x)catalyst exhibited excellent electron–hole separation ability, which can adsorbe NH_(3)and dissociate to form NH_(2)fragments and H atoms. In-situ diffuse reflectance infrared fourier-transform spectroscopy(DRIFTS) indicated that the optical carrier enhanced NH_(3)adsorption on MnTiO_(x), which makes it possess excellent PSCR activity. This work provided an additional strategy to NO removal with PSCR catalysts and showed potential for use in photocatalysis.展开更多
Low temperature catalysts are attracting increasing attention in the selective catalytic reduction(SCR)of NO with NH3.Mn Ox-decorated Mg Al layered double oxide(Mn/Mg Al-LDO)was synthesized via a facile fast pour assi...Low temperature catalysts are attracting increasing attention in the selective catalytic reduction(SCR)of NO with NH3.Mn Ox-decorated Mg Al layered double oxide(Mn/Mg Al-LDO)was synthesized via a facile fast pour assisted co-precipitation(FP-CP)process.Compared to the Mn/Mg Al-LDO obtained via slow drop assisted coprecipitation(SD-CP)method,the Mn/Mg Al-LDO(FP-CP)has excellent activity.The Mn/Mg Al-LDO(FP-CP)catalyst was shown to possess a high NO conversion rate of 76%-100%from 25 to 150℃,which is much better than the control Mn/Mg Al-LDO(SD-CP)(29.4%-75.8%).In addition,the Mn/Mg Al-LDO(FP-CP)offered an enhanced NO conversion rate of 97%and a N2selectivity of 97.3%at 100℃;the NO conversion rate was 100%and the N2selectivity was 90%at 150℃with a GHSV of 60,000 h^-1.The Mn/Mg Al-LDO(FP-CP)catalyst exhibited a smaller fragment nano-sheet structure(sheet thickness of 7.23 nm).An apparent lattice disorder was observed in the HRTEM image confirming the presence of many defects.The H2-TPR curves show that the Mn/Mg Al-LDO(FP-CP)catalyst has abundant reducing substances.Furthermore,the enhanced surface acidity makes the NH3concentration of the Mn/Mg Al-LDO(FP-CP)catalyst lower than 100 ml·m^-3after the reaction from 25 to 400℃.This can effectively reduce the ammonia escape rate in the SCR reaction.Thus,the Mn/Mg Al-LDO(FP-CP)catalyst has potential applications in stationary industrial installations for environmentally friendly ultra-low temperature SCR.展开更多
Ni-Al mixed metal oxides have been successfully prepared by high shear mixer(HSM)and coprecipitation(CP)methods for low temperature CO methanation.In this work,Ni-Al(HSM-CP)catalyst presented small Ni crystallite size...Ni-Al mixed metal oxides have been successfully prepared by high shear mixer(HSM)and coprecipitation(CP)methods for low temperature CO methanation.In this work,Ni-Al(HSM-CP)catalyst presented small Ni crystallite size and high surface area,which all contribute to the methanation reaction at low temperature conditions.The obtained Ni-Al(HSM-CP)sample exhibited a mass of defective oxygen,thereby accelerating the dissociation of CO and ultimately increasing the activity of the catalyst.Ni-Al(HSM-CP)catalyst offered the best activity with CO conversion=100%and CH_(4) selectivity=93%at 300℃,and the CH_(4) selectivity can reach 81.8%at 200℃.In situ Fourier transform infrared spectroscopy and density functional theory show that CHO and COH intermediates with lower activation energy barriers are produced during the reaction,and hydrogen-assisted carbon–oxygen bond scission is more favorable.展开更多
Traditional methods of preparing metal-organic frameworks(MOFs)compounds have the disadvantages such as poor dispersion,inefficient and discontinuous process.In this work,microchannel reactor is used to prepare MOFs-d...Traditional methods of preparing metal-organic frameworks(MOFs)compounds have the disadvantages such as poor dispersion,inefficient and discontinuous process.In this work,microchannel reactor is used to prepare MOFs-derived zeolite-imidazole material via flash nanoprecipitation to form ZIF-67+PEI(FNP),which reduces the MOF synthesis time down to millisecond time interval while keeping the synthesized ZIF-67+PEI(FNP)highly dispersed.The Co@N–C(FNP)catalyst obtained by flash nanoprecipitation and carbonization has a higher Co content and thus more active sites for oxygen reduction reaction than the Co@N–C(DM)catalyst prepared by direct mixing method.Electrochemical tests show that the Co@N–C(FNP)catalyst prepared by this method has excellent oxygen reduction performance,good methanol resistance and high stability.The onset potential and half-wave potential of Co@N–C(FNP)are 0.92 VRHE and 0.83 VRHE,respectively,which are higher than that of Co@N–C(DM)(Eonset=0.90 VRHEand E1/2=0.83VRHE).Moreover,the Zn-air battery assembled with Co@N–C(FNP)as the cathode catalyst has high open circuit voltage,high power density and large specific capacity.The performance of these batteries has been comparable to that of Pt/C assembled batteries.Density functional theory(DFT)calculations confirm that the Co(220)crystal plane present in Co@N–C(FNP)have stronger adsorption energy than that of Co(111)crystal plane in Co@N–C(DM),leading to better electrocatalytic performance of the former.展开更多
Ammonia is crucial in industry and agriculture, but its production is hindered by environmental concerns and energy-intensive processes. Hence, developing an efficient and environmentally friendly catalyst is imperati...Ammonia is crucial in industry and agriculture, but its production is hindered by environmental concerns and energy-intensive processes. Hence, developing an efficient and environmentally friendly catalyst is imperative. In this study, we employed a straightforward and efficient impregnation technique to create various Cu-doped catalysts. Notably, the optimized 10Fe-8Cu/TiO_(2) catalyst exhibited exceptional catalytic performance in converting NO to NH3, achieving an NO conversion rate exceeding 80% and an NH3 selectivity exceeding 98% at atmospheric pressure and 350 °C. We employed in situ diffuse reflectance Fourier transform infrared spectroscopy and conducted density functional theory calculations to investigate the intermediates and subsequent adsorption. Our findings unequivocally demonstrate that Cu doping enhances the rate-limiting hydrogenation step and lowers the energy barrier for NH3 desorption, thereby resulting in improved NO conversion and enhanced selectivity toward ammonia. This study presents a pioneering approach toward energy-efficient ammonia synthesis and recycling of nitrogen sources.展开更多
In this study,the ultralow specific surface area clay vermiculite(VMT)was selected to be a catalyst support for the NH_(3)-SCR process,and the active components MnCeFeO_(x)loaded on vermiculite was just like curling o...In this study,the ultralow specific surface area clay vermiculite(VMT)was selected to be a catalyst support for the NH_(3)-SCR process,and the active components MnCeFeO_(x)loaded on vermiculite was just like curling on ice from the TEM results.The de-NO_(x)performance of Mn-Ce-Fe/VMT exhibited almost complete NO conversion with a gas hourly space velocity(GHSV)of 15,300 h^(-1)at 150℃,which was 25%and 10%higher than that of Mn/VMT and Mn-Ce/VMT,respectively.Ce and Fe co-doping improved the BET surface area,the quantities of active Mn^(4+),the acid sites and NH_(3)adsorption energy of Mn/VMT,all of which contributed to the increase in low-temperature SCR activity.In situ DRIFT measurements suggested that NO_(x)removal over Mn-Ce-Fe/VMT followed both Eley-Rideal(E-R)and Langmuir-Hinshelwood(L-H)mechanisms at 150℃,but the E-R mechanism played a dominant role.Corresponding Mn-Ce-Fe/VMT monolithic catalysts reached 90%NO conversion with a GHSV of 4000 h^(-1).展开更多
基金supported by Science and Technology Innovation Talents Program of Bingtuan (No.2019CB025)Major Scientific and Technological Project of Bingtuan (No.2018AA002)Project of Regional Innovation in Bingtuan (No.2021BB005)。
文摘Photo-assisted SCR(PSCR) offers a potential solution for removal of NO at room temperature. MnTiO_(x)as PSCR catalyst exhibits superior performance with NO removal of 100% at the room temperature. Electron paramagnetic resonance(EPR) analysis revealed the presence of numerous oxygen vacancies on MnTiO_(x). Optical carrier density functional theory(DFT) calculations showed that the threedimensional orbital hybridization of Mn and Ti is significantly enhanced under light irradiation. The MnTiO_(x)catalyst exhibited excellent electron–hole separation ability, which can adsorbe NH_(3)and dissociate to form NH_(2)fragments and H atoms. In-situ diffuse reflectance infrared fourier-transform spectroscopy(DRIFTS) indicated that the optical carrier enhanced NH_(3)adsorption on MnTiO_(x), which makes it possess excellent PSCR activity. This work provided an additional strategy to NO removal with PSCR catalysts and showed potential for use in photocatalysis.
基金supported by Science and Technology Innovation Talents Program of Bingtuan(No.2019CB025)Major Scientific and Technological Project of Bingtuan(No.2018AA002)。
文摘Low temperature catalysts are attracting increasing attention in the selective catalytic reduction(SCR)of NO with NH3.Mn Ox-decorated Mg Al layered double oxide(Mn/Mg Al-LDO)was synthesized via a facile fast pour assisted co-precipitation(FP-CP)process.Compared to the Mn/Mg Al-LDO obtained via slow drop assisted coprecipitation(SD-CP)method,the Mn/Mg Al-LDO(FP-CP)has excellent activity.The Mn/Mg Al-LDO(FP-CP)catalyst was shown to possess a high NO conversion rate of 76%-100%from 25 to 150℃,which is much better than the control Mn/Mg Al-LDO(SD-CP)(29.4%-75.8%).In addition,the Mn/Mg Al-LDO(FP-CP)offered an enhanced NO conversion rate of 97%and a N2selectivity of 97.3%at 100℃;the NO conversion rate was 100%and the N2selectivity was 90%at 150℃with a GHSV of 60,000 h^-1.The Mn/Mg Al-LDO(FP-CP)catalyst exhibited a smaller fragment nano-sheet structure(sheet thickness of 7.23 nm).An apparent lattice disorder was observed in the HRTEM image confirming the presence of many defects.The H2-TPR curves show that the Mn/Mg Al-LDO(FP-CP)catalyst has abundant reducing substances.Furthermore,the enhanced surface acidity makes the NH3concentration of the Mn/Mg Al-LDO(FP-CP)catalyst lower than 100 ml·m^-3after the reaction from 25 to 400℃.This can effectively reduce the ammonia escape rate in the SCR reaction.Thus,the Mn/Mg Al-LDO(FP-CP)catalyst has potential applications in stationary industrial installations for environmentally friendly ultra-low temperature SCR.
基金This work was supported by National Natural Science Foundation of China(No.22068034)Science and Technology Innovation Talents Program of Bingtuan(No.2019CB025).
文摘Ni-Al mixed metal oxides have been successfully prepared by high shear mixer(HSM)and coprecipitation(CP)methods for low temperature CO methanation.In this work,Ni-Al(HSM-CP)catalyst presented small Ni crystallite size and high surface area,which all contribute to the methanation reaction at low temperature conditions.The obtained Ni-Al(HSM-CP)sample exhibited a mass of defective oxygen,thereby accelerating the dissociation of CO and ultimately increasing the activity of the catalyst.Ni-Al(HSM-CP)catalyst offered the best activity with CO conversion=100%and CH_(4) selectivity=93%at 300℃,and the CH_(4) selectivity can reach 81.8%at 200℃.In situ Fourier transform infrared spectroscopy and density functional theory show that CHO and COH intermediates with lower activation energy barriers are produced during the reaction,and hydrogen-assisted carbon–oxygen bond scission is more favorable.
基金supported by National Natural Science Foundation of China(No.21865025)Science and Technology Innovation Talents Program of Bingtuan(No.2019CB025)。
文摘Traditional methods of preparing metal-organic frameworks(MOFs)compounds have the disadvantages such as poor dispersion,inefficient and discontinuous process.In this work,microchannel reactor is used to prepare MOFs-derived zeolite-imidazole material via flash nanoprecipitation to form ZIF-67+PEI(FNP),which reduces the MOF synthesis time down to millisecond time interval while keeping the synthesized ZIF-67+PEI(FNP)highly dispersed.The Co@N–C(FNP)catalyst obtained by flash nanoprecipitation and carbonization has a higher Co content and thus more active sites for oxygen reduction reaction than the Co@N–C(DM)catalyst prepared by direct mixing method.Electrochemical tests show that the Co@N–C(FNP)catalyst prepared by this method has excellent oxygen reduction performance,good methanol resistance and high stability.The onset potential and half-wave potential of Co@N–C(FNP)are 0.92 VRHE and 0.83 VRHE,respectively,which are higher than that of Co@N–C(DM)(Eonset=0.90 VRHEand E1/2=0.83VRHE).Moreover,the Zn-air battery assembled with Co@N–C(FNP)as the cathode catalyst has high open circuit voltage,high power density and large specific capacity.The performance of these batteries has been comparable to that of Pt/C assembled batteries.Density functional theory(DFT)calculations confirm that the Co(220)crystal plane present in Co@N–C(FNP)have stronger adsorption energy than that of Co(111)crystal plane in Co@N–C(DM),leading to better electrocatalytic performance of the former.
文摘Ammonia is crucial in industry and agriculture, but its production is hindered by environmental concerns and energy-intensive processes. Hence, developing an efficient and environmentally friendly catalyst is imperative. In this study, we employed a straightforward and efficient impregnation technique to create various Cu-doped catalysts. Notably, the optimized 10Fe-8Cu/TiO_(2) catalyst exhibited exceptional catalytic performance in converting NO to NH3, achieving an NO conversion rate exceeding 80% and an NH3 selectivity exceeding 98% at atmospheric pressure and 350 °C. We employed in situ diffuse reflectance Fourier transform infrared spectroscopy and conducted density functional theory calculations to investigate the intermediates and subsequent adsorption. Our findings unequivocally demonstrate that Cu doping enhances the rate-limiting hydrogenation step and lowers the energy barrier for NH3 desorption, thereby resulting in improved NO conversion and enhanced selectivity toward ammonia. This study presents a pioneering approach toward energy-efficient ammonia synthesis and recycling of nitrogen sources.
基金supported by the Program of Science and Technology Innovation Team in Bingtuan(No.2020CB006)Science and Technology Innovation Talents Program of Bingtuan(No.2019CB025)Major Scientific and Technological Project of Bingtuan(No.2018AA002).
文摘In this study,the ultralow specific surface area clay vermiculite(VMT)was selected to be a catalyst support for the NH_(3)-SCR process,and the active components MnCeFeO_(x)loaded on vermiculite was just like curling on ice from the TEM results.The de-NO_(x)performance of Mn-Ce-Fe/VMT exhibited almost complete NO conversion with a gas hourly space velocity(GHSV)of 15,300 h^(-1)at 150℃,which was 25%and 10%higher than that of Mn/VMT and Mn-Ce/VMT,respectively.Ce and Fe co-doping improved the BET surface area,the quantities of active Mn^(4+),the acid sites and NH_(3)adsorption energy of Mn/VMT,all of which contributed to the increase in low-temperature SCR activity.In situ DRIFT measurements suggested that NO_(x)removal over Mn-Ce-Fe/VMT followed both Eley-Rideal(E-R)and Langmuir-Hinshelwood(L-H)mechanisms at 150℃,but the E-R mechanism played a dominant role.Corresponding Mn-Ce-Fe/VMT monolithic catalysts reached 90%NO conversion with a GHSV of 4000 h^(-1).
