Some K_2NiF_4-type oxides(A_2BO_4) exhibited good catalytic activity for oxidative coupling of methane to form ethane and ethylene. The C_2 selectivity was well correlated with A-site ion when B-site was Ti^(4+) ion.
For the first time, DySrA104 of K2NiF4-type structure was synthesized. The parameters of DySrA104 ele- mentary unit cell are determined as follows： a = 0.368 （4） nm, c = 1.229 （2） nm, V = 0.166 （4） nm3. The res...For the first time, DySrA104 of K2NiF4-type structure was synthesized. The parameters of DySrA104 ele- mentary unit cell are determined as follows： a = 0.368 （4） nm, c = 1.229 （2） nm, V = 0.166 （4） nm3. The research of the complex aluminates ZnSrA104 （Ln = Nd, Gd, Dy） solid-state process demonstrated the change of the formation mecha- nism among LnSrA104 （Ln = Nd, Gd, Dy） series from DySrA104 oxide. The performed analysis provided a possibility to realize why chemists couldn＇t get DySrA104 for a long period of time.展开更多
A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type(La1-xCax)2(Ni0.75Cu0.25)O4+δwas successfully prepared through a sol-gel route.Their chemical compatibility,oxygen permeability,CO and CO...A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type(La1-xCax)2(Ni0.75Cu0.25)O4+δwas successfully prepared through a sol-gel route.Their chemical compatibility,oxygen permeability,CO and CO2 tolerance,and long-term CO2 resistance regarding phase composition and crystal structure at different atmospheres were studied.The results show that higher Ca contents in the material lead to the formation of CaCO3.A constant oxygen permeation flux of about 0.63 mL·min−1·cm−2 at 1173 K through a 0.65 mm thick membrane was measured for(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δ,using either helium or pure CO2 as sweep gas.Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO2 concentration.The membrane showed excellent chemical stability towards CO2 for more than 1360 h and phase stability in presence of CO for 4 h at high temperature.In addition,this membrane did not deteriorate in a high-energy CO2 plasma.The present work demonstrates that this(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δmembrane is a promising chemically robust candidate for oxygen separation applications.展开更多
One of the major challenges to develop"intermediate temperature"solid oxide fuel cells is finding a novel cathode material,which can meet the following requirements:(1)high electronic conductivity;(2)chemica...One of the major challenges to develop"intermediate temperature"solid oxide fuel cells is finding a novel cathode material,which can meet the following requirements:(1)high electronic conductivity;(2)chemical compatibility with the electrolyte;(3)a matched thermal expansion coefficient(TEC);(4)stability in a wide range of oxygen partial pressure;and(5)high catalytic activity for the oxygen reduction reaction(ORR).In this short review,a survey of these requirements for K2NiF4-type material with the formula Ln2MO4,Ln=La,Pr,Nd,Sm;M=Ni,Cu,Fe,Co,Mn,is presented.The composition-dependent TEC,electrical conductivity and oxygen transport property are considered.The Ln2MO4 materials exhibit improved chemical stability and compatibility with most of the traditional electrolytes.The complete fuel cells integrated with Ln2MO4 materials as cathodes show promising results.Furthermore,these materials are considered as cathodes of protonic ceramic fuel cell(PCFC),and/or anodes of high temperature steam electrolysis(HTSE).First results show excellent performances.The versatility of these Ln2MO4 materials is explained on the basis of structural features and the ability to accommodate oxygen non-stoichiometry.展开更多
基金Subject supported by the National Natural Science Foundation of China
文摘Some K_2NiF_4-type oxides(A_2BO_4) exhibited good catalytic activity for oxidative coupling of methane to form ethane and ethylene. The C_2 selectivity was well correlated with A-site ion when B-site was Ti^(4+) ion.
文摘For the first time, DySrA104 of K2NiF4-type structure was synthesized. The parameters of DySrA104 ele- mentary unit cell are determined as follows： a = 0.368 （4） nm, c = 1.229 （2） nm, V = 0.166 （4） nm3. The research of the complex aluminates ZnSrA104 （Ln = Nd, Gd, Dy） solid-state process demonstrated the change of the formation mecha- nism among LnSrA104 （Ln = Nd, Gd, Dy） series from DySrA104 oxide. The performed analysis provided a possibility to realize why chemists couldn＇t get DySrA104 for a long period of time.
基金This work is part of the project “Plasma-induced CO2-conversion”(PiCK,project number:03SFK2S3B)and financially supported by the German Federal Ministry of Education and Research in the framework of the“Kopemikus projects for the Energiewende”.The authors are thankfUl to B.Sc.Laura Steinle(University of Stuttgart)for her assistance during the CO stability tests,and Christine Stefani and Prof.Dr.Robert Dinnebier(Max Planck Institute for Solid State Research,Stuttgart)for the in situ PXRD measurements,respectively.G.C.thanks Frank Hack and Dr.Angelika Veziridis for their kind support during experiments and discussions.
文摘A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type(La1-xCax)2(Ni0.75Cu0.25)O4+δwas successfully prepared through a sol-gel route.Their chemical compatibility,oxygen permeability,CO and CO2 tolerance,and long-term CO2 resistance regarding phase composition and crystal structure at different atmospheres were studied.The results show that higher Ca contents in the material lead to the formation of CaCO3.A constant oxygen permeation flux of about 0.63 mL·min−1·cm−2 at 1173 K through a 0.65 mm thick membrane was measured for(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δ,using either helium or pure CO2 as sweep gas.Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO2 concentration.The membrane showed excellent chemical stability towards CO2 for more than 1360 h and phase stability in presence of CO for 4 h at high temperature.In addition,this membrane did not deteriorate in a high-energy CO2 plasma.The present work demonstrates that this(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δmembrane is a promising chemically robust candidate for oxygen separation applications.
基金supported by the National Natural Science Foundation of China(51072048)Research Project of New Century Excellent Talents in University(NCET-06-0349)Heilongjiang Educational Department(GZ09A204,1152G027,11531274&11531285)
文摘One of the major challenges to develop"intermediate temperature"solid oxide fuel cells is finding a novel cathode material,which can meet the following requirements:(1)high electronic conductivity;(2)chemical compatibility with the electrolyte;(3)a matched thermal expansion coefficient(TEC);(4)stability in a wide range of oxygen partial pressure;and(5)high catalytic activity for the oxygen reduction reaction(ORR).In this short review,a survey of these requirements for K2NiF4-type material with the formula Ln2MO4,Ln=La,Pr,Nd,Sm;M=Ni,Cu,Fe,Co,Mn,is presented.The composition-dependent TEC,electrical conductivity and oxygen transport property are considered.The Ln2MO4 materials exhibit improved chemical stability and compatibility with most of the traditional electrolytes.The complete fuel cells integrated with Ln2MO4 materials as cathodes show promising results.Furthermore,these materials are considered as cathodes of protonic ceramic fuel cell(PCFC),and/or anodes of high temperature steam electrolysis(HTSE).First results show excellent performances.The versatility of these Ln2MO4 materials is explained on the basis of structural features and the ability to accommodate oxygen non-stoichiometry.
