Kinetics of Liquid Phase Selective Hydrogenation of Methylacetylene and Propadiene in C₃ Streams

Abstract

A study was made of kinetic parameters of methylacetylene (MA) and propadiene (PD) selective hydrogenation in liquid phase. C₃ cut, produced by naphtha steam cracking, contains 93.5 wt% propylene, 3.5 wt% propane, 2.5 wt% MAPD and lighter hydrocarbons. MA and PD are unwanted for the propylene conversion processes in the downstream plants and are removed by converting them to propylene itself. For this purpose, a palladium based commercial catalyst was used in a lab scale trickle-bed reactor, in the temperature range of 20–50°C and in the WHSV range of 70–110 h^–1, at 2.53 MPa. It was found that MAPD conversion to propylene decreases as temperature and WHSV increase. In the reaction mixture, propylene itself also reacts to give propane. However, propylene conversion remains nearly constant in different WHSV and temperature values. Rate equations for MA, PD and propylene conversions were obtained by using experimental results. Kinetic parameters were calculated by taking into consideration external and internal mass transfer resistances.