(683d) Overcoming Propane Dehydrogenation Equilibrium Limitations Using a Catalyst/Membrane Hollow Fiber System | AIChE

(683d) Overcoming Propane Dehydrogenation Equilibrium Limitations Using a Catalyst/Membrane Hollow Fiber System


Almallahi, R. - Presenter, University of Houston
Wortman, J., University of Michigan
Linic, S., University of Michigan
Propylene is one of the most diverse building blocks in the petrochemical industry. Propane dehydrogenation (PDH) is a promising technology for direct production of propylene and hydrogen. PDH is an endothermic reaction requiring elevated reaction temperatures. Unfortunately, under high temperature conditions, the rates of side reactions are increased, leading to lower selectivity, catalyst deactivation, and requiring costly catalyst regeneration.1 The catalysts used commercially for this process include Pt nanoparticles, heavily promoted by Sn (Sn:Pt atomic ratio of ~5) and supported on Al2O3. The high concentration of Sn is required since the PtSn phase segregates and leads to the formation of a SnO2 phase. For stable performance, these catalysts also require H2 as a cofeed to mitigate carbon buildup. This reduces per-pass propylene conversion and lowers catalyst productivity. Herein, we report the design of a stable and selective catalyst for PDH operating at the thermodynamic limit without the addition of H2 to the feed.2 Furthermore, using reaction engineering, this superior catalyst performance is pushed beyond equilibrium limits, based on Le Châtelier’s principle.3 We couple our stable and selective Pt1Sn1/SiO2 catalyst to a H2-removing, Knudsen-driven SiO2/Al2O3 hollow fiber membrane (where the catalyst is packed inside the membrane) to form a membrane/catalyst system that can overcome equilibrium limitations. Through removal of H2 from the product stream, we obtain propylene yields beyond those at thermodynamic constraints. We explore different operating conditions guided by dimensionless numbers that govern these membrane/catalyst systems to obtain an overall improvement of ~10% above equilibrium limits at 580 °C, while maintaining a propylene selectivity of > 95% and good stability.


  1. Chen, S. et al. Chemical Society Reviews. 2021, 50(5), 3315-3354.
  2. Motagamwala, A. H.; Almallahi, R.; Wortman, J.; Igenegbai, V. O.; Linic, S. Science. 2021, 373(6551), 217-222.
  3. Weyten, H. et al. Catalysis Today. 2000. 56(1-3), 3-11.