Estimation of RWGS Kinetic Parameters for Methanol Production

Abstract

The hydrogenation process of Natural Gas (NG) with high CO2 content can potentially be employed for a novel process of methanol production that avoids CO2 extraction and emission, at the same time yielding high CO2 conversion to methanol. However, the required hydrogenation reactor has not yet been designed in detail because kinetic information of the Reverse Water Gas Shift (RWGS) reaction, which is indispensable for its simulation, is unavailable. In this paper, the kinetics of the RWGS reaction over a Pd-Ce/α-Al2O3 catalyst is analyzed for mixtures of CO2-CH4-H2. The reaction rate expression is experimentally obtained using an isothermal fixed-bed reactor at 600 °C and 1.62 bar. The experimental results demonstrated the absence of the dry reforming reaction and a negligible activity for methanation. The mass balance equation for a pseudo-homogeneous one-dimension reactor model was solved firstly assuming a power-law (PL) model and then, a Langmuir-Hinshelwood-Hougen-Watson (LH-HW) approach in order to obtain the kinetic parameters. By preprocessing the data set with an evolutionary algorithm before applying the Levenberg-Marquardt method, satisfactory results were obtained. The achieved rate equations will be useful to carry out improvements in the simulation and economic analysis of the process of interest.