Process simulation and optimization of propane dehydrogenation combined with selective hydrogen combustion

Abstract

A co-fed process combining propane dehydrogenation (PDH) with selective hydrogen combustion (SHC) is proposed, simulated, and optimized. The co-fed process uses adiabatic moving bed radial flow reactors as PDH reactors and adiabatic fixed bed reactors as SHC reactors. This co-fed process is proven to be very advantageous over the Oleflex process in some aspects, showing a propylene yield 6.0-46.1% higher and saving 2.86-7.24 × 106 kJ per ton of propylene under different operating conditions. These advantages are attributed to the utilization of SHC reactors: they consume some hydrogen in the process, which shifts the reaction equilibrium towards propylene; they also provide much heat to drive the highly endothermic PDH reaction. For the co-fed process, a feed temperature of 873 K, a total pressure of 1 bar, and using four PDH reactors are preferable; the optimal oxygen input is significantly affected by feed temperature and number of PDH reactors. Besides, under these preferable conditions, a SHC catalyst should have a minimum hydrogen combustion selectivity of 60.4% to reproduce and exceed the Oleflex efficiency. This work should provide useful guidelines for the development of co-fed processes for propane dehydrogenation.