TiO_(2)-supported V_(2)O_(5)catalysts are commonly used in NO_(x)reduction with ammonia due to their robust catalytic performance.Over these catalysts,it is generally considered that the active species are mainly deri...TiO_(2)-supported V_(2)O_(5)catalysts are commonly used in NO_(x)reduction with ammonia due to their robust catalytic performance.Over these catalysts,it is generally considered that the active species are mainly derived from the vanadia species rather than the intrinsic structure of V-O-Ti entities,namely the interface sites.To reveal the role of V-O-Ti entities in NH_(3)-SCR,herein,we prepared TiO_(2)/V_(2)O_(5)catalysts and demonstrated that V-O-Ti entities were more active for NO_(x)reduction under wet conditions than the V sites(V=O)working alone.On the V-O-Ti entities,kinetic measurements and first principles calculations revealed that NH_(3)activation exhibited a much lower energy barrier than that on V=O sites.Under wet conditions,the V-O-Ti interface significantly inhibited the transformation of V=O to V-OH sites thus benefiting NH_(3)activation.Under wet conditions,meanwhile,the migration of NH_(4)^(+)from Ti site neighboring the V-O-Ti interface to Ti site of the V-O-Ti interface was exothermic;thus,V-O-Ti entities together with neighboring Ti sites could serve as channels linking NH_(3)pool and active centers for activation of NH_(4)^(+).This finding reveals that the V-O-Ti interface sites on V-based catalysts play a crucial role in NO_(x)removal under realistic conditions,providing a new perspective on NH_(3)-SCR mechanism.展开更多
Traditional vanadium-based selective catalytic reduction(SCR)deNO_(x) catalyst can hardly adapt to the gas conditions(much high NO_(2)/NO_(x) ratio at lower temperature)of the start-up and low loading periods for a ga...Traditional vanadium-based selective catalytic reduction(SCR)deNO_(x) catalyst can hardly adapt to the gas conditions(much high NO_(2)/NO_(x) ratio at lower temperature)of the start-up and low loading periods for a gas turbine.Therefore,a W-Ti-CeO_(x) catalyst with NO_(x) storage and reduction(NSR)function was developed in this work for gas turbine exhaust NO_(x) elimination.The experimental results reveal that W-Ti-CeO_(x) catalyst exhibits high NO_(2) adsorption capacity at relatively low temperature while that is quite low for V-W/TiO_(2).The abundant surface Ce^(3+) species can be mainly responsible for its high adsorption ability owing to the reaction between NO_(2) and Ce^(3+) to form nitrate/nitrite species and NO.Meanwhile,the adsorption capacity of W-Ti-CeO_(x) can easily regenerate at medium-high temperature and NH_(3)-SCR reaction.Furthermore,W-Ti-CeO_(x) also shows good NH_(3)-SCR activity,which can fulfill the deNO_(x) process at high temperature.The addition of W and Ti into ceria can enhance the surface acidity and redox ability,thereby increasing the SCR activity.This work proposes a novel storage-reduction strategy for NO_(x) elimination throughout the operation of gas turbines.展开更多
A novel Mo-doped CuO catalyst is developed and used for low-temperature NH_(3)-SCR reaction.Compared with the undoped CuO sample,the Mo doped CuO catalyst shows an increased SCR performance with above 80%NO_(x) conver...A novel Mo-doped CuO catalyst is developed and used for low-temperature NH_(3)-SCR reaction.Compared with the undoped CuO sample,the Mo doped CuO catalyst shows an increased SCR performance with above 80%NO_(x) conversion at 175℃.The XRD and Raman results have confirmed the incorporation of Mo metal ions into CuO lattice to form Mo-O-Cu species which may be related to the enhanced SCR activity.The XPS and UV-vis results reveal the creation of electron interaction between Cu and Mo in this Mo-O-Cu system which provides an increased amount of Lewis and Brønsted acid sites,thereby promoting the adsorption capacity of NH_(3) and NO_(x) as verified by NH_(3)-TPD and NO_(x)-TPD characterization.Besides,it also promotes the formation of oxygen vacancies,leading to the increasing of chemisorbed oxygen species,which improves the NO oxidation to NO_(2) activity.Furthermore,in situ DRIFTS technology was also used to study the reaction mechanism of this Mo doped CuO catalyst.The formed NO_(2) could react with NHx(x=3,2)species to enhance the low-temperature NH_(3)-SCR activity via the"fast-SCR"reaction pathway.The nitrate and nitrite ad-species may react with NH_(3) and NH4^(+)ad-species through the L-H pathway.展开更多
基金supported by the National Natural Science Foundation of China (Nos.U20B6004,22072179,and 22276202)the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDA23010200)+1 种基金the Special project of eco-environmental technology for peak carbon dioxide emissions and carbon neutrality (No.RCEES-TDZ2021-2)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (No.2019045)。
文摘TiO_(2)-supported V_(2)O_(5)catalysts are commonly used in NO_(x)reduction with ammonia due to their robust catalytic performance.Over these catalysts,it is generally considered that the active species are mainly derived from the vanadia species rather than the intrinsic structure of V-O-Ti entities,namely the interface sites.To reveal the role of V-O-Ti entities in NH_(3)-SCR,herein,we prepared TiO_(2)/V_(2)O_(5)catalysts and demonstrated that V-O-Ti entities were more active for NO_(x)reduction under wet conditions than the V sites(V=O)working alone.On the V-O-Ti entities,kinetic measurements and first principles calculations revealed that NH_(3)activation exhibited a much lower energy barrier than that on V=O sites.Under wet conditions,the V-O-Ti interface significantly inhibited the transformation of V=O to V-OH sites thus benefiting NH_(3)activation.Under wet conditions,meanwhile,the migration of NH_(4)^(+)from Ti site neighboring the V-O-Ti interface to Ti site of the V-O-Ti interface was exothermic;thus,V-O-Ti entities together with neighboring Ti sites could serve as channels linking NH_(3)pool and active centers for activation of NH_(4)^(+).This finding reveals that the V-O-Ti interface sites on V-based catalysts play a crucial role in NO_(x)removal under realistic conditions,providing a new perspective on NH_(3)-SCR mechanism.
基金Project supported by the National Key Research and Development Program of China(2022YFC3701601)the National Natural Science Foundation of China(22276162).
文摘Traditional vanadium-based selective catalytic reduction(SCR)deNO_(x) catalyst can hardly adapt to the gas conditions(much high NO_(2)/NO_(x) ratio at lower temperature)of the start-up and low loading periods for a gas turbine.Therefore,a W-Ti-CeO_(x) catalyst with NO_(x) storage and reduction(NSR)function was developed in this work for gas turbine exhaust NO_(x) elimination.The experimental results reveal that W-Ti-CeO_(x) catalyst exhibits high NO_(2) adsorption capacity at relatively low temperature while that is quite low for V-W/TiO_(2).The abundant surface Ce^(3+) species can be mainly responsible for its high adsorption ability owing to the reaction between NO_(2) and Ce^(3+) to form nitrate/nitrite species and NO.Meanwhile,the adsorption capacity of W-Ti-CeO_(x) can easily regenerate at medium-high temperature and NH_(3)-SCR reaction.Furthermore,W-Ti-CeO_(x) also shows good NH_(3)-SCR activity,which can fulfill the deNO_(x) process at high temperature.The addition of W and Ti into ceria can enhance the surface acidity and redox ability,thereby increasing the SCR activity.This work proposes a novel storage-reduction strategy for NO_(x) elimination throughout the operation of gas turbines.
基金supported by the National Natural Science Foundation of China(Nos.21806017,21876019)the Fundamental Research Funds for the Central Universities(No.DUT20RC(4)003)National Key Research and Development Program of China(No.2019YFC1903903).
文摘A novel Mo-doped CuO catalyst is developed and used for low-temperature NH_(3)-SCR reaction.Compared with the undoped CuO sample,the Mo doped CuO catalyst shows an increased SCR performance with above 80%NO_(x) conversion at 175℃.The XRD and Raman results have confirmed the incorporation of Mo metal ions into CuO lattice to form Mo-O-Cu species which may be related to the enhanced SCR activity.The XPS and UV-vis results reveal the creation of electron interaction between Cu and Mo in this Mo-O-Cu system which provides an increased amount of Lewis and Brønsted acid sites,thereby promoting the adsorption capacity of NH_(3) and NO_(x) as verified by NH_(3)-TPD and NO_(x)-TPD characterization.Besides,it also promotes the formation of oxygen vacancies,leading to the increasing of chemisorbed oxygen species,which improves the NO oxidation to NO_(2) activity.Furthermore,in situ DRIFTS technology was also used to study the reaction mechanism of this Mo doped CuO catalyst.The formed NO_(2) could react with NHx(x=3,2)species to enhance the low-temperature NH_(3)-SCR activity via the"fast-SCR"reaction pathway.The nitrate and nitrite ad-species may react with NH_(3) and NH4^(+)ad-species through the L-H pathway.
