Determination of reactive critical points of kinetically controlled reacting mixtures

Abstract

A simple computational procedure to determine reactive critical points of kinetically controlled reacting mixtures was developed. The thermodynamic analysis considers the simultaneous calculation of the reactive and non-reactive residue curve maps using the Peng–Robinson equation of state and the Heidemann and Khalil method for the computation of critical points. Two kinetically controlled reactive systems were considered: (i) the reversible esterification reaction of acetic acid with ethanol in the presence of CO2 and, (ii) the irreversible hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene with tetralin as solvent for the production of ultra low sulfur diesel. It was found that the amount of catalyst loaded (α) into the reacting vessel plays a key role for the existence of the reactive critical points for the deep HDS of diesel while for the esterification reactions has little significance. Also, results showed that, while the catalyst loaded does not have any influence on the existence of the reactive critical point for the esterification reactive system (TC∼566K; PC∼68atm; xHAc∼0.39, xEtOH∼0.26, xEtAc∼0.15, xH2O∼0.19, and xCO2∼0.01), it moves the range of temperature where a maximum liquid composition of ethyl acetate can be obtained. Several critical points for the hydrodesulfurization of 4,6-DMDBT were found with different α values.