Modeling of Fe/HZSM-5 catalyst deactivation of Fischer-Tropsch synthesis

Deactivation of Fe/HZSM-5 catalyst for Fischer-Tropsch synthesis in a fixed bed reactor was investigated, at different H2/CO ratios of (0.5, 1 and 2), temperatures of (270, 290 and 310 ᜀC) and pressures of (13, 17 and 21 bar). The reactor was also modeled, where different catalyst deactivation equations were incorporated into the model in order to select the best deactivation equations. Since reactant mass value changes very slowly during catalyst deactivation, a pseudo static condition was assumed for the reactor and the deactivation equation was solved separately. Model equations were solved applying TR-BDF2 method, which is an implicit Rung–kutta method. The experimental data were used to validate model predictions. They were also used to estimate model parameters and to select the best deactivation model. The criterion for this selection was the least squares of the errors between reactor model predictions and experimental data. General Power Law equation was found to be the best deactivation model.

Keywords:

Fischer–Tropsch synthesis , deactivation model , iron based catalyst , fixed-bed reactor