Mechanism-based kinetics of the water–gas shift reaction at low temperature with a ruthenium catalysts

Abstract

The kinetics of the water–gas change reaction was evaluated with formulated ruthenium catalysts (Ru 2 wt%/TiO2, Ru 2 wt%/Al2O3) in a fixed bed reactor with a gas mixture containing 15% CO + Ar at temperatures ranging from 453 to 573 K under atmospheric pressure. Component mass balances were developed to represent the experimental data of the operations, including reaction rates expressed by the surface redox and Langmuir–Hinshelwood (LH) models. Parametric estimation was performed using nonlinear programming with MATLAB software, and an algorithm developed to fit the model to the data. The LH model provided the best adjustment, indicating orders of apparent activation energies of 12 and 12.9 kJ/mol for the reactions with Ru/TiO2 and Ru/Al2O3 catalysts, respectively. For comparison purposes, an empirical model of power law for the reaction rate was adjusted, involving unit reaction orders for CO, H2O and CO2, and zero order for the hydrogen, providing an apparent activation energy of 53.8 kJ/mol. The evolutions of component concentration were simulated allowing the model validation by comparing calculated versus experimental values.