Combined methane reforming with a mixture of methane combustion products and steam over a Ni-based catalyst: An experimental and thermodynamic study

摘要

Combined methane reforming with a mixture of methane combustion products and steam over a commercial Ni-based catalyst is studied both experimentally and theoretically. The 7-holes cylinder of NiO-alpha Al2O3 catalysts is used as the pellets. The thermodynamic analysis of the reforming process was carried out by total Gibbs free energy minimization to determine the maximum achievable methane conversion in the reformer. The reforming performances were determined for various amount of extra steam in inlet reaction mixture (from 0 to 2 mol of H2O per mole of CH4). The methane conversion is increasing when steam is added to the reaction mixture at a fixed temperature. The methane conversion reaches a maximum value (about 1) at the temperature range above 800 degrees C. Based on experimental results, the approximation functions of the methane conversion versus the residence time for the various temperatures and methane-to-oxidizer ratio were obtained. The methane conversion reaches the value that is close to equilibrium at the residence time above 4.0 kg(cat).s/mol. The effect of pressure (in the pressure range from 1 to 5 bar) on methane conversion is insignificant and is no more than 1-2%. The values of the methane conversion can be used for the energy analysis of the thermochemical recuperation system by methane reforming with steam and flue gases. (C) 2019 Elsevier Ltd. All rights reserved.