Reaction rate simulation and mechanism analysis of methane steam reforming
As clean energy,hydrogen energy has great potential for development.Methane steam reforming is an economical and environmentally friendly hydrogen production method,which can produce high-purity hydrogen and reduce carbon emissions.However,due to the rapid change of the reaction rate during the chain transfer process of the reaction,the reaction mechanism is still unclear.CHEMKIN simulation software was used to couple the methane steam reforming reaction kinetic model with the Plug Flow Reactor(PFR).The simulation was carried out under the reaction conditions of the temperature of 1200 K,water-carbon ratio(molar ratio)of 3.0,and gas inlet mass flow rate of 0.01 g/s.By analyzing the elementary reaction rates of CH4,H2O and intermediate product CH3,the main substances involved in the reaction were determined,and the reaction mechanism(mainly refers to the reaction pathways)was further analyzed.The results show that the adsorption and desorption reaction of water vapor and methane on the catalyst surface,and the dissociation reaction of H2O(s)(s represents adsorbed state)and CH4(s)on the catalyst has a great influence on methane steam reforming reaction.The two dissociation reactions of CH4(s)on the catalyst surface are direct dissociation and reactive dissociation with O(s),and the reaction rate with O(s)is higher than the direct dissociation rate.The reaction pathway of CH4(s)on the catalyst surface is CH4(g)→ CH4(s)→ CH3(s)→ CH2(s)→ CH(s)→ C(s),and CH4(g)→ CH4(s)→ CH3(s)has the greatest influence on the reaction.H2O(g)is also adsorbed on the surface of catalysts,and the reaction pathway is H2O(g)→ H2O(s)→ OH(s)→ H(s).
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