摘要
应用ＦＴＩＲ和脉冲反应技术研究了ＣＯ_２和Ｏ_２在Ａｇ－Ｂａ－Ｃａ－Ｋ／α－Ａｌ２Ｏ３上的吸附及ＣＯ２对Ｃ２Ｈ４环氧化、完全氧化及环氧乙烷（ＥＯ）深度氧化反应的影响．研究结果表明，ＣＯ２和表面吸附氧在负载银催化剂表面存在竞争吸附，ＣＯ２对表面吸附氧有置换作用，该作用降低了银催化剂表面吸附氧的浓度，并且所形成的碳酸根物种改善了乙烯环氧化反应活住氧种的表面分布，对Ｃ_２Ｈ_４的环氧化反应有一定的抑制作用，但是对Ｃ２Ｈ４和ＥＯ的深度氧化反应的抑制作用更强，使得乙烯环氧化反应的选择性得到改善．
he adsorption of CO2 and O2 as well as the effect of CO2 on ethylene epoxidation have been studied over Ba, Ca and K promoted silver/a￣alumina catalyst. The inhibiting effect of CO2 on ethylene epoxidation was measuredby adding a range of co2= 1 %-20% CO2 to the feed gas, and it should be taken into account when CO2 was higher than 5(vol) % in the feed. Carbon dioxide pulse reaction showed that the weakly adsorbed oxygen.was displaced by the, more strongly adsorbed CO2 on' the surface of the supported silver catalyst. It indicated that the competitive adsorption of CO2 and O2 at the same site off the surface of the supported silver catalyst resulted in the declease in the concentration of surface oxygen (Oa). The decrease in the surface concentration of oxygen should kinetically favour the ethylene oxide formation while simultaneously causing a decrease in ethyllene conversion. Furthermore, the results of effect of CO2 on ethylene oxide combustion.indicated that this combustion reaction was also strongly inhibited by the carbonate.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
1996年第2期111-116,共6页
基金
国家自然科学基金
关键词
银
催化剂
二氧化碳
吸附
乙烯
环氧化
silver catalyst, supported catalyst, carbon dioxide, adsorption,ethylene, epoxidation, combustion, inhibition
