Kinetic Studies of Liquid Phase Hydrogenation of Acetylene for Ethylene Production Using a Selective Solvent over a Commercial Palladium/Alumina Catalyst

The kinetics of selective hydrogenation of acetylene in the liquid phase over a commercial 0.5 wt % Pd/Al2O3 spherical catalyst was investigated in a stirred-tank basket reactor. The liquid phase was acetylene gas absorbed in a selective solvent, N-methylpyrrolidone (NMP). The reactor was operated at a pressure range of 15–250 psig with temperature varying from 60 to 100 °C using different catalyst loadings to identify the suitable operating conditions. The kinetic experiments were conducted in the absence of external mass transfer resistances with the liquid phase in batch mode and the gas phase being continuous. The initial rates varied linearly with the increase in catalyst loading at different temperatures. An intrinsic kinetic model was developed using the power-law model and Langmuir–Hinshelwood–Hougen–Watson (LHHW) approach. The reaction was surface reaction limited with negligible intraparticle diffusion, as estimated from the Thiele modulus and Weisz–Prater criterion. The surface reaction between the adsorbed species was assumed to be the rate-controlling step. The LHHW model provided a good fit to the experimental data, and the intrinsic kinetic rate parameters were estimated.