摘要
采用TPR,EPR,IR,XPS等手段对由合成气制备C2含氧化合物的Rh基催化剂中各活性组分间的相互作用进行了研究.TPR实验表明,Mn的存在除了促进金属铑在担体表面的分散,增加还原过程的耗氢量外,还使Rh物种的还原温度显著升高;少量Li的加入导致氢向载体SiO2的溢流,使体系的还原特性发生了明显的变化.原位EPR和XPS研究显示,添加剂与Rh相互作用,在催化剂表面形成了稳定的复合氧化物.助剂Mn主要起着吸引电子的作用,使还原后的催化剂表面上Rh+物种的含量增加;相反,作为给电子助剂,Li的加入稳定了表面Rh0物种.
Rh based catalysts which are used for the synthesis of C 2 oxygenates through syngas were investigated by TPR, EPR, XPS and IR methods. TPR results indicate that the addition of Mn to the Rh/SiO 2 system inhibited the reduction of the Rh component, while reduction of the Mn component itself appeared to be enhanced. Corresponding EPR experiments suggest that the addition of the Mn component resulted in the formation of Rh Mn mixed oxides. The existence of the Li species serving as an electron donor gives rise to metallic Rh in the catalyst, as evidenced by the XPS results. IR spectra of adsorbed CO indicate that the existence of Mn in the catalyst improved the dispersion of Rh and enhanced the concentration of Rh + species on the surface. The addition of Li promoted the formation of Rh 0 species. Moreover, the addition of Li to the Rh/SiO 2 system might cause the spillover of hydrogen from the Rh species to the SiO 2 support.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
1998年第6期533-537,共5页
关键词
铑
锰锂
合成气
乙醇
乙酸
催化剂
乙醛
Rhodium, manganese, lithium, interaction, TPR, EPR, XPS, IR