Contaminants(K,Na,Ca,and Mg)were introduced into Cu-SAPO-18 via incipient wetness impregnation to investigate their effect on the selective catalytic reduction of NOx with NH3(NH3-SCR)over Cu-SAPO-18.After the introdu...Contaminants(K,Na,Ca,and Mg)were introduced into Cu-SAPO-18 via incipient wetness impregnation to investigate their effect on the selective catalytic reduction of NOx with NH3(NH3-SCR)over Cu-SAPO-18.After the introduction of contaminants into Cu-SAPO-18,the quantity of acidic sites and Cu^2+ species in catalyst decreases owing to the replacement of H^+ and Cu^2+ by K^+,Na^+,Ca^2+,and Mg^2+.Furthermore,the loss of isolated Cu^2+ induces the generation of CuO and CuAl2O4-like phases,which causes further loss in the Brunauer-Emmett-Teller surface area of the catalyst.Consequently,the deNOx performance of the contaminated Cu-SAPO-18 catalysts drops.Such decline in NH3-SCR performance becomes more pronounced by increasing the contaminant contents from 0.5 to 1.0 mmol/gcatal.In addition,the deactivation influence of the contaminants on Cu-SAPO-18 is presented in the order of K>Na>Ca>Mg,which is consistent with the order of reduction of acidic sites.To a certain degree,the effect of the acidic sites on the deactivation of Cu-SAPO-18 might be more significant than that of isolated Cu2+ and the catalyst framework.Moreover,kinetic analysis of NH3-SCR was conducted,and the results indicate that there is no influence of contaminants on the NH3-SCR mechanism.展开更多
Microtubes/rods of the layered metal hydroxide salt compound Cd2（OH）3（DS）·nH2O, where DS stands for dodecyl sulfate sandwiched between two adjacent inorganic sheets, have been synthesized for the first time t...Microtubes/rods of the layered metal hydroxide salt compound Cd2（OH）3（DS）·nH2O, where DS stands for dodecyl sulfate sandwiched between two adjacent inorganic sheets, have been synthesized for the first time through a mild hydrothermal reaction route. The microtubes/rods have a diameter of about 1 μm and a length ranging from several microns to 20μm. The growth process of microtubes/rods under the experimental conditions employed follows a dissolution-recrystallization route.展开更多
Si coordination structures have been proven to greatly influence the ammonia-selective catalytic reduc-tion(NH_(3)-SCR)catalytic properties and the hydrothermal stability of Cu-based silicoaluminophosphate-form cataly...Si coordination structures have been proven to greatly influence the ammonia-selective catalytic reduc-tion(NH_(3)-SCR)catalytic properties and the hydrothermal stability of Cu-based silicoaluminophosphate-form catalysts.However,the role of various Si coordination structures in the NH_(3)-SCR reaction over Cu-SAPO-34 catalyst remains unknown.Herein,a batch of Cu-SAPO-34 samples with various Si contents was synthesized via a one-pot method to study the role of Si coordination structures in the NH_(3)-SCR catalytic properties and hydrothermal stability.Cu/34-2 with the highest proportion of Si(xOAl)(x=1~3)struc-tures exhibits remarkable durability with 90%NO reduction efficiency within 200~450℃ even after a hydrothermal aging treatment at 850℃.In contrast,Cu/34-1 and Cu/34-4 with the highest proportions of Si(4OAl)and Si(0OAl)structures,respectively,are significantly deactivated by the same hydrothermal treatment.To better understand this phenomenon,the relationship between the Si coordination struc-tures and SCR performance is established using characterization techniques and kinetics measurements.Results reveal that a high content of Si(4OAl)and Si(0OAl)is detrimental to the hydrothermal stability of Cu-SAPO-34 catalyst.However,Si(x OAl)(x=1~3)structures are conducive to the stabilization of isolated Cu^(2+),thus enhancing the stability to severe hydrothermal treatment.展开更多
基金supported by the National Natural Science Foundation of China(21473064)~~
文摘Contaminants(K,Na,Ca,and Mg)were introduced into Cu-SAPO-18 via incipient wetness impregnation to investigate their effect on the selective catalytic reduction of NOx with NH3(NH3-SCR)over Cu-SAPO-18.After the introduction of contaminants into Cu-SAPO-18,the quantity of acidic sites and Cu^2+ species in catalyst decreases owing to the replacement of H^+ and Cu^2+ by K^+,Na^+,Ca^2+,and Mg^2+.Furthermore,the loss of isolated Cu^2+ induces the generation of CuO and CuAl2O4-like phases,which causes further loss in the Brunauer-Emmett-Teller surface area of the catalyst.Consequently,the deNOx performance of the contaminated Cu-SAPO-18 catalysts drops.Such decline in NH3-SCR performance becomes more pronounced by increasing the contaminant contents from 0.5 to 1.0 mmol/gcatal.In addition,the deactivation influence of the contaminants on Cu-SAPO-18 is presented in the order of K>Na>Ca>Mg,which is consistent with the order of reduction of acidic sites.To a certain degree,the effect of the acidic sites on the deactivation of Cu-SAPO-18 might be more significant than that of isolated Cu2+ and the catalyst framework.Moreover,kinetic analysis of NH3-SCR was conducted,and the results indicate that there is no influence of contaminants on the NH3-SCR mechanism.
基金supported by the National Natural Science Foundation of China(51701146 and 51672204)Wuhan Application Foundation Frontier Project(2020020601012220)the Fundamental Research Funds for the Central Universities(WUT:2020YB-032,205209016,and 2020IB005)。
基金the National Natural Science Foun-dation of China for financial support
文摘Microtubes/rods of the layered metal hydroxide salt compound Cd2（OH）3（DS）·nH2O, where DS stands for dodecyl sulfate sandwiched between two adjacent inorganic sheets, have been synthesized for the first time through a mild hydrothermal reaction route. The microtubes/rods have a diameter of about 1 μm and a length ranging from several microns to 20μm. The growth process of microtubes/rods under the experimental conditions employed follows a dissolution-recrystallization route.
基金financial support from the National Natural Science Foundation of China (No.52000084)the China Postdoctoral Science Foundation (No.2019M662630)。
文摘Si coordination structures have been proven to greatly influence the ammonia-selective catalytic reduc-tion(NH_(3)-SCR)catalytic properties and the hydrothermal stability of Cu-based silicoaluminophosphate-form catalysts.However,the role of various Si coordination structures in the NH_(3)-SCR reaction over Cu-SAPO-34 catalyst remains unknown.Herein,a batch of Cu-SAPO-34 samples with various Si contents was synthesized via a one-pot method to study the role of Si coordination structures in the NH_(3)-SCR catalytic properties and hydrothermal stability.Cu/34-2 with the highest proportion of Si(xOAl)(x=1~3)struc-tures exhibits remarkable durability with 90%NO reduction efficiency within 200~450℃ even after a hydrothermal aging treatment at 850℃.In contrast,Cu/34-1 and Cu/34-4 with the highest proportions of Si(4OAl)and Si(0OAl)structures,respectively,are significantly deactivated by the same hydrothermal treatment.To better understand this phenomenon,the relationship between the Si coordination struc-tures and SCR performance is established using characterization techniques and kinetics measurements.Results reveal that a high content of Si(4OAl)and Si(0OAl)is detrimental to the hydrothermal stability of Cu-SAPO-34 catalyst.However,Si(x OAl)(x=1~3)structures are conducive to the stabilization of isolated Cu^(2+),thus enhancing the stability to severe hydrothermal treatment.
