Kinetic modelling of the one-step conversion of aqueous ethanol into 1,3-butadiene over a mixed hemimorphite-HfO2/SiO2 catalyst

Abstract

A kinetic model for the one-step conversion of ethanol into 1,3-butadiene over a mixed hemimorphite-HfO/SiO catalyst has been developed, which, as a novelty, accounts for the effect of water content in ethanol on the performance of one-step catalysts, which is important when designing industrial processes. The model considers the formation of the main reaction products (acetaldehyde, water, hydrogen, 1,3-butadiene, ethene, diethyl ether and 1-butanol) as well as numerous minor products, grouped into three lumps (butenes, heavy compounds (C), and oxygenated compounds). A network of eight reactions is used to describe this complex reaction system. The rate of each reaction is modelled using a power-law kinetics with a corrective term to capture the effect of water on certain reactions. Experimental data on the effect of water and reaction conditions on the performance of the hemimorphite-HfO/SiO catalyst were used for the regression and validation of the kinetic model. The results show that the model can predict well the effect of reaction conditions and water content in ethanol on the formation of major and minor compounds, except for butenes and heavy compounds. The modelling approach to build the kinetic model is expected to be valid for any other one-step catalyst.