Abstract:

A typical electrode reaction of electro-organic synthesis usually takes place with competing side electrode reaction and homogeneous reaction.To enhance the electrode polarization for increasing reaction rate will considerably reduce the reaction selectivity.Packed bed electrodes can reach higher current densities at relatively low electrode polarizations，which is favorable to mitigating the inconsistency between reaction rate and selectivity.In this paper，the typical process of electro-organic synthesis in a differential reactor of packed bed electrode（PBEDR），was theoretically analyzed with emphasis on the effect of lateral distribution of over-potential on the selectivity.A generalized mathematical model was developed to describe the distribution of over-potential.Dimensionless variables μ and ω that characterize the polarization and influence of side electrode reaction in the system，were derived from modeling.Adomian’s decomposition method(ADM）was used to solve the nonlinear differential equation of the model to obtain an approximate analytical solution，which was in the form of algebraic expressions of infinite power series.By the solution，the relationship between over-potential distribution and average selectivity could be easily calculated without solving the nonlinear model time and again.Finally，an analysis of electrochemical reduction of nitrobenzene in a PBEDR was presented，and the characteristic size of the reactor，namely the thickness of the packed bed electrode，was theoretically optimized.The results showed that the calculated results were consistent with experimental data satisfactorily.

Key words:

有机电合成, 硝基苯还原, 反应选择性, 填充床电极, 普遍化数模

摘要： 典型的有机电合成反应，常伴有相互竞争的电极副反应和均相反应，增加电极极化以提高反应速率会使选择性明显降低。填充床电极具有大的内表面，能在相对低的极化下，达到较高的表观电流密度，有利于缓解反应速率和选择性之间的突出矛盾。本文对填充床电极微分反应器（PBEDR）中典型有机电合成反应过程进行了理论分析，重点在于床层内超电势横向分布对选择性的影响。建立了描述超电势分布的普遍化数学模型，归纳出表征电极极化和副反应影响的量纲1数μ和ω，并用ADM（Adomian’s decomposition method）对该非线性微分方程模型求解；所获得的逼近解代数表达式，可方便地计算不同参数下超电势分布对平均选择性的影响，而毋需反复求解模型微分方程。最后给出了PBEDR硝基苯电还原制对氨基苯酚选择性分析实例，优化了反应器特征尺寸（填充床电极厚度）。结果证明：理论计算与实验数据令人满意地一致。

关键词:

有机电合成, 硝基苯还原, 反应选择性, 填充床电极, 普遍化数模