Experimental study and mechanistic kinetic modeling for selective production of hydrogen via catalytic steam reforming of methanol

Abstract

The mechanistic kinetic model using Langmuir–Hinshelwood (LH) approach has been developed for the steam reforming of methanol (SRM), accompanied by the reverse water gas shift (rWGS) reaction over a Cu/ZnO/Al 2O 3 catalyst. The major products of steam reforming of methanol were hydrogen and carbon dioxide with small amount of carbon monoxide which is formed as a secondary product. The kinetics study was performed over a wide range of reaction temperature and contact-time in an integral reactor under the conditions of no diffusion limitation. The five intrinsic LH kinetic models were proposed based on two reaction mechanisms, and subjected to the rigorous parameter estimation and model discrimination in order to obtain the appropriate kinetic model. The parameters were estimated by nonlinear least square regression for which correlation among the parameters was minimized by temperature centering of Arrhenius and van’t Hoff equations. A good agreement was obtained between the experimental and model predicated results for the LH model based on formation of formic acid from formaldehyde, and formation of adsorbed CO and surface hydroxyls from formate species as the rate-determining steps for methanol steam reforming and reverse water gas shift reactions respectively.