Kinetic modelling applied to selective hydrogenation of polyunsaturated hydrocarbons on innovative alveolar monoliths

A mathematical model for catalytic selective hydrogenation of light polyunsaturated hydrocarbons has been developed. The model, coded on the software MATLAB, has been built to sensitively analyze reactor performances. Case-study focused on textural parameters optimization of alveolar monoliths, having in perspective subsequent use in fixed bed applications. Material balances have been assessed assuming ideal plug-flow behavior for the system. Sensitivity analysis have been undertaken tuning main textural parameters in order to improve selectivity. Finally, the same model has been applied on a common pellets catalyst, comparisons have been made to compare the systems and justify monoliths exploitment. The hydrocarbon cuts investigated in the study (namely C4, C3, C2) are output of separation after cracking process, these light cuts are of primary interest in industry after being selectively hydrogenated to highly pure monounsaturated solutions. Reacting fluids has been modeled as a two-phase solution, thus two interphase mass transfers have been assessed. Reaction mechanism has been lumped into two consecutive reactions leading to the saturated compound, with kinetics based on the Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach. Kinetic parameters have been taken from literature, considering an average load of Pd particles as active phase; macro-cellular silica monoliths, synthetized as polyHIPE, haven been chosen as innovative alveolar monoliths, while alumina-carried catalytic spheres has been chosen for comparison with commonly-used systems.