(178a) Kinetic Modeling of Propene Hydroformylation in Propane-Expanded Liquid with Rh-Based Complexes

Conventional propylene hydroformylation to produce butyraldehyde requires polymer grade propylene as feedstock.¹ High purity propylene is obtained by energy intensive separation from propane/propylene mixtures. If propane/propylene mixtures can be used effectively as feed, process economics would be significantly enhanced. Previously, we had reported preliminary results on the beneficial effects of propane expanded liquids (with propylene/propane mixtures instead of polymer grade propylene as feed) for propylene hydroformylation with Rhodium-based catalysts. At sufficiently high pressures (>10 bar), the pressurized propane/propylene mixture forms a gas-expanded liquid phase that promotes regio-selective hydroformylation of propylene with homogenous Rh complex.² In this talk, we report hydroformylation of propene in propane expanded solvents in the kinetic regime in a semi batch stainless steel reactor at 70â??90 °C and 6â??18 bar overpressure in 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (NX-795), toluene and n-butanol solvent with rhodium based complexes (Rh/TPP, Rh/ CHDPP, Rh/TPPA and Rh/BIPHEPHOS). The n/i ratio and TOF achieved during Rh/BIPHEPHOS catalyzed hydroformylation in propane-expanded solvents is comparable with conventional processes in neat solvent. By tuning the propane/propylene partial pressure, the n/i ratio in propane-expanded solvents could be enhanced by 30% in Rh-catalyzed reaction with mono-phosphine ligands while maintaining a reaction rate comparable to that without propane addition. Vaporâ??liquid equilibria of the reaction system were also measured in a variable-volume view cell at temperatures ranging from (343.15 to 363.15) K and pressures up to 20 Bar. The measured solubilities of CO and H₂ in the liquid phases were consistent with literature values.³ The presence of propane was found to enhance the solubilities of both CO and H₂ in the liquid phase. The enhancement factor is up to 1.56 for carbon monoxide and 1.91 for hydrogen. Based on experimentally recorded kinetic data, a kinetic model was developed to explain the effects of propane-expanded solvent on the observed rate and selectivity.

1.Krokoszinski, R., Hammon, U., & Todd, K. (2005). U.S. Patent No. 6,864,391. Washington, DC: U.S. Patent and Trademark Office.

2. Liu, D., Xie Z., Chaudhari, R.V., Subramaniam, B. Enhanced Hydroformylation of Propylene in Propane-Expanded Liquids with Rh-Based Complexes, 2015 AIChE annual meeting. Salt Lake City, UT

3. Nair, V. S., Mathew, S. P., & Chaudhari, R. V. (1999). Kinetics of hydroformylation of styrene using homogeneous rhodium complex catalyst. Journal of Molecular Catalysis A: Chemical, 143(1), 99-110.