Nima Moazami
The University of Birmingham, UK
Title: Mathematical modelling and chemical kinetic study of Fischer-Tropsch synthesis on a cobalt-silica catalyst
Biography
Biography: Nima Moazami
Abstract
Kinetic description of Fischer-Tropsch (FT) synthesis is crucial to industrial practice, being a prerequisite for industrial process design, optimization and simulation. A comprehensive study of FT synthesis was carried out for production of liquid fuel (C5+) using simulated N2-rich syngas (33% H2, 17% CO and 50% N2) on an in-house cobalt-silica (37% Co/SiO2) catalyst in which detailed product distribution, rate of reactions, conversion and selectivity information were delivered. A mechanistic reaction network was proposed on the basis of various monomers formation. A Langmuir-Hinshelwood-Hougen-Watson type rate was used to develop the overall formation rate of hydrocarbon products. It was assumed that the dissociation of adsorbed surface-bound CO yielding surface carbon and oxygen is rate-determining step. Also, a Langmuir-Freundlich-Hinshelwood rate model was used to develop a water gas shift reaction rate to take CO2 production rate into account. It was assumed the reaction of surface CO with OH is the rate-deterring step. The kinetic parameters and physical properties were estimated by fitting experimental data under a variety of operating conditions using Global Optimization technique in MATLAB. The simulated values of N2, CO, H2, CO2, CH4, C2, C3, C4 and C5+ were in good agreement with those obtained experimentally with mean absolute relative residual error of 3.02%. Also, the accuracy of the model were measured by qualitative analysis, parity diagram, and quantitative analysis i.e. F-test method. To give a better insight about the performance of the catalyst and the quality of the developed kinetic model, the effects of reaction rates and operating conditions were studied on CO and H2 conversion and distribution of hydrocarbon products.