摘要
研究了负载Ru,Rh和Pd的WO3-ZrO2催化剂在乙烯直接氧化制乙酸反应中的催化性能.结果显示,负载的贵金属对催化剂的催化性能有非常重要的影响.Rh/WO3-ZrO2催化剂具有最高的乙烯转化率,而Ru/WO3-ZrO2催化剂对反应几乎没有活性.H2化学吸附结果显示,高的催化性能来源于高的金属分散度.Pd/WO3-ZrO2催化剂显示了最高的乙酸选择性(75%),而其它两个催化剂的乙酸选择性都非常低(～10%).程序升温氧化和程序升温还原结果显示,贵金属–O键的键强对产物的选择性具有重要的影响.弱的贵金属–O键可以通过将氧插入到乙烯和/或乙醛中而有利于乙酸的生成,而强的贵金属–O键会导致乙烯完全氧化为COx.
Ru-, Rh-, and Pd/WO3-ZrO2 catalysts were studied for the direct oxidation of ethylene to acetic acid. The catalytic activity and selectivity depended strongly on the noble metals used. Rh/WO3-ZrO2 gave the highest conversion of ethylene, whereas Ru/WO3-ZrO2 was almost inactive. The higher catalytic activity was attributed to a better metal dispersion. Pd/WO3-ZrO2 gave the highest selectivity for acetic acid （75%）, with the selectivity of the other two catalysts being rather low （～10%）. Temperature-programmed oxidation and H2 reduction experiments were used to show that the strength of the noble metal-oxygen bond played an important role in product distribution. A weak metal--oxygen bond favored the formation of acetic acid, while a strong metal-oxygen bond favored the combustion of ethylene to COx.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第12期1281-1286,共6页
基金
Supported by the National Science Foundation for Distinguished Young Scholars (20725313)
the National Basic Research Program of China (973 Program, 2005CB221404)
关键词
乙烯
氧化
乙酸
氧化钨
氧化锆
钯
钌
铑
ethylene
oxidation
acetic acid
tungstated zirconia
palladium
ruthenium
rhodium
