DEACTIVATION MECHANISM OF DIETHYL OXALATE SYNTHESIS BY VAPOR PHASE CATALYTIC COUPLING REACTION OF CO AFTER INTRODUCTION OF HYDROGEN

Abstract

Abstract: In this paper, the effects of hydrogen on CO coupling reaction to diethyl oxalate at different hydrogen concentrations, reaction temperatures and residence times are studied. The results show that after introduction of hydrogen, CO conversion, selectivity and STY of diethyl oxalate all decrease with the increase of hydrogen concentration and reaction temperature. The deactivation kinetics of CO coupling reaction after introduction of hydrogen is obtained as follows:-da/dt=k_dc^0.65_H2. According to this kinetic model the deactivation mechanism of the catalyst is further discussed. It is found that the co-adsorption of hydrogen and CO on the same active site of the catalyst occurrs.Adsorption of hydrogen will decrease the adsorption of CO on the catalyst and then decrease the formation rate of diethyl oxalate, CO conversion and space yield of diethyl oxalate.

Key words:

一氧化碳, 偶联, 氢气, 失活动力学

摘要： 重点研究了氢气（H₂）对一氧化碳（CO）催化偶联反应制草酸二乙酯的影响，分别考察了不同H₂浓度、不同温度和不同空时条件下加入H₂对CO偶联反应的影响，结果发现H₂的加入使反应过程中CO转化率、草酸二乙酯选择性和空时收率明显下降，且在实验条件范围内，通入H₂浓度越高、反应温度越高，催化剂活性下降越快.研究得出，H₂气氛下CO偶联反应失活动力学方程为：-da/dt=k_dc^0.65_H2.进一步分析失活动力学方程可知，加氢反应过程中，H₂和CO吸附在同一个活性中心上，H₂在活性中心上的吸附抑制了CO在催化剂上的吸附，从而使得CO催化偶联反应生成草酸二乙酯的速率下降，导致加氢后CO转化率、草酸二乙酯选择性和空时收率降低.

关键词:

一氧化碳, 偶联, 氢气, 失活动力学

LI Zhenhua, XU Genhui, WANG Baowei, MA Xinbin, DU Pa. DEACTIVATION MECHANISM OF DIETHYL OXALATE SYNTHESIS BY VAPOR PHASE CATALYTIC COUPLING REACTION OF CO AFTER INTRODUCTION OF HYDROGEN[J]. CIESC Journal, 2003, 54(1): 59-63.

李振花, 许根慧, 王保伟, 马新宾, 杜葩. H₂对CO气相催化偶联制草酸二乙酯反应的失活机理 [J]. 化工学报, 2003, 54(1): 59-63.

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