不同粒径Pd/Al_2O_3催化乙炔加氢反应微观动力学分析  

Microkinetics analysis of acetylene hydrogenation over Pd/Al_2O_3 catalyst with different particle sizes

作　　者：庞洪强 隋志军[1] 朱贻安[1] 周兴贵[1] 

机构地区：[1]华东理工大学化学工程联合国家重点实验室,上海200237

出　　处：《化工学报》2016年第9期3692-3698,共7页CIESC Journal

基　　金：国家重点基础研究发展计划项目(2012CB720500);国家自然科学基金项目(21376076)~~

摘　　要：采用等量浸渍法制备了α-Al_2O_3负载的系列Pd催化剂,运用BET、XRD、ICP-AES、CO化学吸附、TEM等手段对催化剂进行了表征;根据部分析因实验设计方案进行动力学实验,采用微观反应动力学方法模拟和分析了所获稳定期本征动力学实验结果。结果发现,制备所得催化剂Pd颗粒的平均粒径分别为1.6、3.4、5.5 nm,CO化学吸附所测定达到活性稳定期后的催化剂表面Pd原子数与Hardeveld模型计算的Pd(111)表面原子数一致;模拟结果表明该微观动力学模型可以很好地模拟不同粒径催化剂上的动力学结果,在所研究范围内表面最丰物种为C_2H_4*和C_2H_3*,通过微观与宏观动力学的特征判断3种催化剂上乙炔加氢的速率控制步骤为乙烯基加氢生成乙烯。Pd/α-Al_2O_3 with different particle sizes were prepared by the incipient wetness method and characterized by BET, XRD, ICP-AES, CO chemisorption and TEM. The kinetic characteristics over these catalysts were explored following a fractional factorial designs of experiment and the experiment results were analyzed by microkinetic method. The size of three catalysts obtained was 1.6 nm, 3.4 nm and 5.5 nm, respectively, as verified by TEM and CO chemisorption results. After stable performance of the catalyst, the exposed surface Pd number of catalysts measured from CO chemisorption agreed well with that of Pd（111） surface calculated from Hardeveld＇s model. The microkinetic analysis results showed that the microkinetic model can fit the kinetic experiment results quite well on all catalysts. C_2H_4＊ and C_2H_3＊ were the most abundant surface species independent of the reaction conditions. The rate determining step was the hydrogenation of vinyl group to form ethylene according to the relationship between microkinetic information and macrokinetic characteristics.

关 键 词：多相反应 乙炔加氢 微观动力学模型 粒径效应 催化剂 

分 类 号：TQ032.4[化学工程]