Three‐step macrokinetic model of butane and propane steam conversion to methane‐rich gas

Abstract

AbstractLow‐temperature steam conversion (LTSC) of a methane‐butane mixture (95% methane and 5% butane) into a methane‐rich gas over an industrial Ni‐based catalyst has been studied with the following reaction conditions: temperature 200–320°C, pressure 1 bar, gas hour space velocity 1200–3600 h–1, and steam to carbon ratio 0.64. A three‐step macrokinetic model has been suggested based on the kinetic parameters found. The model includes the following reactions: (1) irreversible steam reforming; (2) CO2 methanation, which occurs in a quasi‐equilibrium mode at temperatures above 260°C; (3) hydrogenolysis of propane and butane, which is essential at temperatures below 260°C. Steam reforming was shown to limit the overall reaction rate, whereas hydrogenolysis and CO2 methanation determined the product distribution in low‐ and high‐temperature regions, respectively. Temperature dependencies of the product distribution for the LTSC of a model ternary methane‐propane‐butane mixture (85% methane, 10% propane, and 5% butane) have been successfully simulated using the three‐step model suggested.