A series of La-Cu-Zn-O mixed oxide catalysts were synthesized by a co-precipitation method and calcined under different temperatures. The XRD, BET, TPR, N2 O-adsorption, XPS, SEM and TPD techniques were carried out to...A series of La-Cu-Zn-O mixed oxide catalysts were synthesized by a co-precipitation method and calcined under different temperatures. The XRD, BET, TPR, N2 O-adsorption, XPS, SEM and TPD techniques were carried out to measure the aimed catalysts. The results indicated that the chemical environment of lanthanum element changes with the increase of calcination temperature. The La2 CuO4 perovskite structure is obtained at the temperature higher than 823 K and the special copper species appear in the perovskites due to the special structure property. The catalysts with La2 CuO4 perovskite structure show higher methanol selectivity compared with the mixed copper catalyst. For the perovskite catalysts, the conversion of CO2 changes with the same tendency of the copper species ratio（（Cu^（α＋）＋Cu^0）/（Cu（Total））%）, which implied both Cu^（α＋） and Cu^0 are important active sites in the perovskite catalyst for the reaction.展开更多
La<sub>2</sub>CuO<sub>4</sub>, the parent compound of the La system high-temperaturesuperconductors, can be rendered superconducting at～40 K by substituting A<sup>2+</sup>（A=Ca, S...La<sub>2</sub>CuO<sub>4</sub>, the parent compound of the La system high-temperaturesuperconductors, can be rendered superconducting at～40 K by substituting A<sup>2+</sup>（A=Ca, Sr, Ba） at La<sup>3+</sup> sites or introducing excess oxygen to compound by annealingunder high oxygen pressures as well as other treatments. It is a hard Moot insulatorof which crystal cells contain Cu-O sheet, and 3D antiferromagnetic property展开更多
基金Project supported by the Natural Science Foundation of Ningxia Province(NZ16003)
文摘A series of La-Cu-Zn-O mixed oxide catalysts were synthesized by a co-precipitation method and calcined under different temperatures. The XRD, BET, TPR, N2 O-adsorption, XPS, SEM and TPD techniques were carried out to measure the aimed catalysts. The results indicated that the chemical environment of lanthanum element changes with the increase of calcination temperature. The La2 CuO4 perovskite structure is obtained at the temperature higher than 823 K and the special copper species appear in the perovskites due to the special structure property. The catalysts with La2 CuO4 perovskite structure show higher methanol selectivity compared with the mixed copper catalyst. For the perovskite catalysts, the conversion of CO2 changes with the same tendency of the copper species ratio（（Cu^（α＋）＋Cu^0）/（Cu（Total））%）, which implied both Cu^（α＋） and Cu^0 are important active sites in the perovskite catalyst for the reaction.
文摘La<sub>2</sub>CuO<sub>4</sub>, the parent compound of the La system high-temperaturesuperconductors, can be rendered superconducting at～40 K by substituting A<sup>2+</sup>（A=Ca, Sr, Ba） at La<sup>3+</sup> sites or introducing excess oxygen to compound by annealingunder high oxygen pressures as well as other treatments. It is a hard Moot insulatorof which crystal cells contain Cu-O sheet, and 3D antiferromagnetic property
