Fe-ZSM-5 catalysts modified by Cu and Ce by aqueous solution ion-exchange and incipient wetness impregnation methods were tested in the selective catalytic reduction of NO_(x) with NH_(3).A variety of characterization...Fe-ZSM-5 catalysts modified by Cu and Ce by aqueous solution ion-exchange and incipient wetness impregnation methods were tested in the selective catalytic reduction of NO_(x) with NH_(3).A variety of characterization techniques(NH_(3)-SCO,BET,XRD,XPS,UV-Vis,NH_(3)-TPD,H_(2)-TPR)were used to explore the changes of the active sites,acid sites and pore structure of the catalyst.It was found that the dispersion of active Cu species and Fe species had great influences on the catalytic activity in the whole catalytic process.The Cu doping into the Fe-ZSM-5 catalyst produced new active species,isolated Cu ions and CuO particles,resulting in the improved low-temperature catalytic activity.However,the NH_(3) oxidation was enhanced,and part of the Fe^(3+)active sites and more Brønsted acidic sites in the catalyst were occupied by Cu species,which causes the decrease of the high-temperature activity.The recovery of hightemperature activity could be attributed to the recovery of active Cu species and Fe species promoted by Ce and the promotion of active species dispersion.The results provide theoretical support for adjusting the active window of Febased SCR catalyst by multi-metal doping.展开更多
To obtain lightweight multicomponent magnesium alloys with high tensile strength,ductility,and stiffness,two extruded Mg_(92−5x)Al_(1.5+3x)Zn_(3)Cu_(3.5+x)Ce_(x)(x=0.5 and 1,labeled as C0.5 and C1)alloys were designed...To obtain lightweight multicomponent magnesium alloys with high tensile strength,ductility,and stiffness,two extruded Mg_(92−5x)Al_(1.5+3x)Zn_(3)Cu_(3.5+x)Ce_(x)(x=0.5 and 1,labeled as C0.5 and C1)alloys were designed.The results reveal that the ultimate tensile strength,yield strength(YS),and fracture strain of the C0.5 alloy are simultaneously improved compared to those of the C1 alloy,with values of 346 MPa,312 MPa,and 11.7%,respectively.This enhancement is primarily attributed to the refinement of numerous secondary phases(micron scale Al_(3)CuCe,micron scale MgZnCu,and nanoscale MgZnCu phases).The calculation of YS shows that the Orowan strengthening and coefficient of thermal expansion mismatch strengthening are the main strengthening mechanisms,and the contribution values of both to the YS are 28 and 70 MPa for C0.5 alloy.In addition,the C0.5 alloy has a greater plasticity than the C1 alloy because the<c+a>slip system is initiated.展开更多
在6种不同浓度的铈(C e3+)对0.1 m g.L-1的Cu2+毒害下,研究了菹草叶片中保护酶SOD、POD、CAT的活性,活性氧H2O2,膜脂过氧化产物M DA含量及叶绿素含量等的变化及影响.结果表明,在9~12 d之内,7.5 m g.L-1以下的C e3+可以增强SOD、CAT、PO...在6种不同浓度的铈(C e3+)对0.1 m g.L-1的Cu2+毒害下,研究了菹草叶片中保护酶SOD、POD、CAT的活性,活性氧H2O2,膜脂过氧化产物M DA含量及叶绿素含量等的变化及影响.结果表明,在9~12 d之内,7.5 m g.L-1以下的C e3+可以增强SOD、CAT、POD活性,降低M DA的含量,提高叶片中叶绿素和可溶性蛋白含量,从而减轻Cu2+对菹草植物体的伤害.而随着C e3+作用时间的延长和浓度的增大,C e3+的缓解作用不断减弱,C e3+和Cu2+产生协同效应,加重毒害.本实验结果认为,5~7.5 m g.L-1的C e3+缓解菹草叶片Cu2+毒害效果最好.展开更多
基金Project(51906089)supported by the National Natural Science Foundation of ChinaProject(NELMS2018A18)supported by the National Engineering Laboratory for Mobile Source Emission Control Technology,China+1 种基金Project(XNYQ2021-002)supported by the Provincial Engineering Research Center for New Energy Vehicle Intelligent Control and Simulation Test Technology of Sichuan,ChinaProject(GY2020016)supported by the Zhenjiang City Key R&D Program,China。
文摘Fe-ZSM-5 catalysts modified by Cu and Ce by aqueous solution ion-exchange and incipient wetness impregnation methods were tested in the selective catalytic reduction of NO_(x) with NH_(3).A variety of characterization techniques(NH_(3)-SCO,BET,XRD,XPS,UV-Vis,NH_(3)-TPD,H_(2)-TPR)were used to explore the changes of the active sites,acid sites and pore structure of the catalyst.It was found that the dispersion of active Cu species and Fe species had great influences on the catalytic activity in the whole catalytic process.The Cu doping into the Fe-ZSM-5 catalyst produced new active species,isolated Cu ions and CuO particles,resulting in the improved low-temperature catalytic activity.However,the NH_(3) oxidation was enhanced,and part of the Fe^(3+)active sites and more Brønsted acidic sites in the catalyst were occupied by Cu species,which causes the decrease of the high-temperature activity.The recovery of hightemperature activity could be attributed to the recovery of active Cu species and Fe species promoted by Ce and the promotion of active species dispersion.The results provide theoretical support for adjusting the active window of Febased SCR catalyst by multi-metal doping.
基金financially supported by the National Key Research and Development Program of China(No.2022YFB3709300)the Guangdong Major Project of Basic and Applied Basic Research,China(No.2020B0301030006)the Chongqing Special Project of Science and Technology Innovation,China(No.cstc2021yszx-jcyjX0007)。
文摘To obtain lightweight multicomponent magnesium alloys with high tensile strength,ductility,and stiffness,two extruded Mg_(92−5x)Al_(1.5+3x)Zn_(3)Cu_(3.5+x)Ce_(x)(x=0.5 and 1,labeled as C0.5 and C1)alloys were designed.The results reveal that the ultimate tensile strength,yield strength(YS),and fracture strain of the C0.5 alloy are simultaneously improved compared to those of the C1 alloy,with values of 346 MPa,312 MPa,and 11.7%,respectively.This enhancement is primarily attributed to the refinement of numerous secondary phases(micron scale Al_(3)CuCe,micron scale MgZnCu,and nanoscale MgZnCu phases).The calculation of YS shows that the Orowan strengthening and coefficient of thermal expansion mismatch strengthening are the main strengthening mechanisms,and the contribution values of both to the YS are 28 and 70 MPa for C0.5 alloy.In addition,the C0.5 alloy has a greater plasticity than the C1 alloy because the<c+a>slip system is initiated.
