Kinetic study of propane dehydrogenation over chromia-alumina catalyst

Shuai Tan, Seung Won Choi, Sankar Nair, David S. Sholl and Chris topher W. Jones *

School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332

*chris topher.jones @chbe.gatech.edu

Jas on S. Moore, Yujun Liu , Ravindra S. Dixit and John G. Pendergas t

Engineering & Process Sciences, The Dow Chemical Company, Freeport, TX 77541

With the influx of abundant light gases in North America, technologies for their valorization are again rising to prominence. Propane dehydrogenation (PDH) is a potential pathway for production of valuable olefins from such light gases. C urrent promising industrial processes are based on Cr (Catofin) and Pt (Oleflex) catalysts. A key challenge with any catalytic system from PDH is cracking reaction and catalyst deactivation via carbon deposition. Furthermore, P DH is an endothermic reaction that is equilibrium limited. Development of membrane reactors for PDH, combining catalytic reaction and membrane separation in the same device, can significantly improve olefin productivity and decrease the energy cost of PDH by shifting the reaction equilibrium. Among several factors, a detailed understanding of the PDH catalyst is required fo r the successful P DH intensification by membrane reactors. In this work, we discuss a detailed study of P DH catalysis over Al2O3-supported Cr2O3, doped with Na2O. Alkali addition (1 wt%) results in an increase in C3H6 selectivity and consequently provides higher C3H6 yield compared to the alkali- free catalyst. In addition, the alkali additive suppresses production of CH4 significantly. Detailed k inetic data are interpreted by several models based on Langmuir-Hinshelwood mechanisms to aid in the design and modeling of the membrane reactor. Details of the catalytic behavior are captured by estimating key parameters (i.e., activation energy, heat of adsorption), and the results are compared to those for related PDH catalysts in the literature.