Raman peaks at 1951 and 2165 cm^(-1) can be confirmed further by H_2/D_2 isotope exchange as H-adspecies on the doubly promoted iron catalyst for ammonia synthesis and are probably ascribed to two terminally adsorbed ...Raman peaks at 1951 and 2165 cm^(-1) can be confirmed further by H_2/D_2 isotope exchange as H-adspecies on the doubly promoted iron catalyst for ammonia synthesis and are probably ascribed to two terminally adsorbed H-species.展开更多
The adsorption of O2 over defective La2O3-based OCM catalysts with anionic vacancies , and the reaction of surface oxygen species with CH4 were studied by means of in situ confocal microprobe Raman spectra. The partia...The adsorption of O2 over defective La2O3-based OCM catalysts with anionic vacancies , and the reaction of surface oxygen species with CH4 were studied by means of in situ confocal microprobe Raman spectra. The partially reduced oxygen species O2, O , O (O<&<1 ) and even the lattice oxygen ion O2-can be detected on the surface of O2-pretreated La2O3-based catalysts. At lower temperatures (< 573 K) it is peroxide species O- or O- that is more essential for the coupling of methane,while at higher temperature. the superoxide O2 and lattice oxygen species O2-are rather important. It is easier for fluoride-containing La2O3-based catalysts to induce the oxygen species with fewer negative charges and the basicity of the cat- alyst surface is weakened , so that the C2 selectivity for OCM reaction is improved.展开更多
基金Supported from the State Key Laboratory for Physical Chemistry of the Solid Surface of Xiamen University.
文摘Raman peaks at 1951 and 2165 cm^(-1) can be confirmed further by H_2/D_2 isotope exchange as H-adspecies on the doubly promoted iron catalyst for ammonia synthesis and are probably ascribed to two terminally adsorbed H-species.
文摘The adsorption of O2 over defective La2O3-based OCM catalysts with anionic vacancies , and the reaction of surface oxygen species with CH4 were studied by means of in situ confocal microprobe Raman spectra. The partially reduced oxygen species O2, O , O (O<&<1 ) and even the lattice oxygen ion O2-can be detected on the surface of O2-pretreated La2O3-based catalysts. At lower temperatures (< 573 K) it is peroxide species O- or O- that is more essential for the coupling of methane,while at higher temperature. the superoxide O2 and lattice oxygen species O2-are rather important. It is easier for fluoride-containing La2O3-based catalysts to induce the oxygen species with fewer negative charges and the basicity of the cat- alyst surface is weakened , so that the C2 selectivity for OCM reaction is improved.
