Mathematical modeling of regeneration of coked Cr-Mg catalyst in fixed bed reactors

[Display omitted] •The mathematical modeling of the coked Cr-Mg catalyst regeneration is studied.•The parameters of the model were determined from the lab-scale experiments.•The inlet gas temperature higher than catalyst one leads to the adiabatic bed heating.•The low inlet gas temperature leads to the overheating and catalyst damage. On the base of two-dimensional (bed length and pellet radius coordinates) two-temperature (gas and catalyst phases) mathematical model the coked CrF3/MgF2 catalyst regeneration process in the adiabatic reactor of gas-phase perchloroethylene hydrofluorination to pentafluoroethane (Freon 125) is studied. The parameters of the mathematical model such as coke burning rate constant, temperature of the coke burning beginning T* (ignition point), heat of the reaction and activation energy were determined from experiments in lab-scale reactor and from the thermal analysis data. The influence of process parameters, e.g. oxygen and coke concentrations, initial gas and catalyst temperatures and pellet size was investigated. The simulation was carried out under conditions of low oxygen concentration (oxygen shortage) and showed that if the inlet gas temperature Tgo is lower than initial catalyst temperature Tp0 (Tgo