Saeed Sahebdelfar earned his PhD degree in Chemical Engineering from Sharif University of Technology. He is currently the head of Catalysis Research Group in Petrochemical Research and Technology Company. His research interests are in the fields of natural gas conversions and environmental technologies. His main research activities are focused on catalytic oxidative coupling of methane, paraffin dehydrogenation and carbon dioxide utilization. He published more than 60 scientific papers in international journals.
The catalytic dehydrogenation of light alkanes (propane and isobutane) has received much attention for on-purpose production of the corresponding olefins. The rapid deactivation of the catalyst due to coke formation is a major technical problem of the reaction which complicates its industrial implementation. Consequently, catalyst deactivation is an important issue in the development of the catalyst and process for alkane dehydrogenation. In this work the kinetics of deactivation of Pt-Sn-K/Al2O3 catalyst in dehydrogenation of propane and isobutane was studied. A power-law rate was used for the forward and reverse main reactions and a concentration-dependent rate expression incorporating all the main reacting species was used for catalyst deactivation. The long-term catalyst performance test runs were performed in a fixed-bed reactor under the representative commercial operating conditions (575 and 620 °C for isobutane and propane, respectively). The reactor outlet was analyzed by an on-line GC for C1-C4 hydrocarbon products. During the first 100 h on stream, the catalyst exhibited significant deactivation in both reactions although the selectivity to the corresponding olefins remained fairly constant. The parameters of the kinetic models were estimated by non-linear least-squares method using numerical optimization. Favorable fits were observed for both propane and isobutane conversion data. According to the relative magnitudes of the rate constants of deactivation, it was concluded that the deactivation mechanism is chiefly of consecutive type for propane dehydrogenation and of parallel type for isobutane dehydrogenation. Hydrogen showed high coke removing potential thereby it could be used in relatively low concentrations to increase catalyst lifetime.