Kinetic And Computational Fluid Dynamics Simulation Of Electrocatalytic Membrane Reactor Based On Tetrafluoropropanol Oxidation

As a highly selective and safe herbicide chemical intermediate, sodium 2,2,3,3-tetrafluoropropionate (STFP) can be produced in one step by the electrocatalytic oxidation of 2,2,3,3-tetrafluoro-l-propanol (TFP) in electrocatalytic membrane reactor (ECMR). However, the nonuniform distribution of ECMR has restrained its application and development. As the basis of the electro-oxidation of TFP to produce STFP, the aim of the current study is to constitute ECMR by the nano-MnOx loading Ti electrocatalytic membrane to investigate the kinetics of catalytic reaction and simulate the distribution by Computational Fluid Dynamics (CFD) during the operation so as to provide the theoretical guidance for reactor design and optimization.The electrochemical characterization of plate electrode, porous electrode and ECMR were analyzed by electrochemical workstation such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (E1S), and chronoamperometry (CA) using iron potassium cyanide solution as an electrolyte solution. CFD simulation software with porous model was used to simulate the hydrodynamic behavior of two-dimensional ECMR and analyze the effects of membrane parameters on flow distribution along the membrane and on the ECMR performance. The results showed that the porous electrode showed a higher current, more electrochemical active sites and lower interfacial resistance between electrode and bulk solution than plate electrode as a result of ECMR synergistic effect of reaction and enhanced mass transfer. The results showed that the TFP conversion of ECMR (74.3%) was 3.5 times than that of the plate electrode (21.5%) and 1.7 times than that of the porous electrode (43.9%). Further, the CFD simulation results showed that the membrane dimension strongly influenced the hydrodynamic behavior of ECMR and there was one certain range of enhanced mass transfer region along the membrane. A membrane with shorter length or larger diameter would present an uniform crossflow velocity and a higher ratio of enhanced mass transfer region, which were favorable to the ECMR performance. TFP conversion of 97.7%, STFP selectivity of>99.9% and the current efficiency of 40.1% were achieved in ECMR with 40 mm length and 53 mm inner diameter. Further, as the evaluation parameters of ECMR optimization, the enhanced mass transfer region moved with the different outlet position. For the long membrane tube in ECMR, the increase of enhanced mass transfer region could be obtained by several outlets distributed evenly along the membrane tube. The horizontal ECMR could obtain a uniform crossflow velocity distribution along the membrane tube, but both of the TFP conversion and current efficiency were low. In sum, the effective coupling between the electrochemical oxidation and enhanced mass transfer play key roles on the highly efficient of ECMR.