Kinetics of the hydrogenation of CO^sub 2^ to methanol at atmospheric pressure using a Pd-Cu-Zn/SiC catalyst

• Published in: Fuel processing technology 2018-05, Vol.173, p.173
• Main Authors: Díez-Ramírez, J, Díaz, JA, Dorado, F, Sánchez, P
• Format: Article
• Language: English
• Subjects: Adsorption; Atmospheric models; Atmospheric pressure; Carbon dioxide; Catalysis; Catalysts; Chemical synthesis; Cobalt; Constraint modelling; Copper; Hydrogenation; Kinetics; Methanol; Palladium; Parameters; Reaction kinetics; Sensitivity analysis; Water gas; Zinc oxide
• ISSN: 0378-3820; 1873-7188

The kinetics of the hydrogenation of CO2 to methanol (MeOH) at atmospheric pressure using a Pd-Cu-Zn/SiC catalyst has been analyzed. An initial sensitivity study was performed in order to evaluate the effect of reaction conditions (temperature, CO2/H2 ratio and the presence of products in the feed stream) on the catalytic performance. The results of this study were used to develop three Langmuir–Hinshelwood kinetic models in which the adsorption term was modified (competitive vs two-site vs three-site adsorption mechanism). All of the kinetic models predicted the experimental results well and the corresponding parameters were statistically meaningful. Model discrimination revealed that the three-site adsorption mechanism led to the lowest residual sum of squares and was the only one that met all of the parameter constraints. The quality of this model was evaluated by comparing the results of additional experiments with the predicted values. The three-site adsorption mechanism agreed with the catalytic observations reported previously, where it was observed that, in the presence of a Pd-Cu-Zn/SiC catalyst, the synthesis of MeOH by hydrogenation of CO2 took place on PdZn active sites, whereas the Reverse Water Gas Shift (RWGS), which led to CO, was catalyzed by PdCu sites. The H2 dissociative adsorption was believed to take place on ZnO.