Economic and Environmental Impact Analyses of Integrated Dehydrogenation and Hydroformylation in Gas-Expanded Liquid Media

Economic and Environmental Impact Analyses of Integrated Dehydrogenation and Hydroformylation in Gas-Expanded Liquid Media

Dupeng Liu,^{1, 2} Raghunath V Chaudhari^{1, 2} and Bala Subramaniam^{1, 2}

¹Department of Chemical & Petroleum Engineering, ²Center for Environmentally Beneficial Catalysis, University of Kansas

Lawrence, KS 66047

Increased shale gas production in the U. S. has also enhanced the availability of C₂-C₅ alkanes (the so-called natural gas liquids) as collateral products, and opportunities for their utilization in novel ways. For example, propylene production capacity via propane dehydrogenation (PDH) is slated to grow rapidly over the next several years.¹ However, for a typical PDH process, the per pass conversion is only about 50%. The separation of propane and propylene mixtures is highly energy and capital intensive. Previously, we had reported the beneficial effects of propane expanded liquids (with propylene/propane mixtures 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. In addition, compared with conventional propylene hydroformylation process to produce butyraldehyde using polymer grade propylene as feedstock, the feed in the propane-expanded liquid (PXL) process is 50% cheaper.³

In this talk, economic and environmental analyses of the integrated dehydrogenation and hydroformylation in PXL process are presented and benchmarked against simulated conventional hydroformylation processes for which data were obtained from the Ruhrchemie/Rh™ne-Poulenc  and Dow processes.^4-5 Preliminary simulation results indicate that capital investment and production cost associated with the PXL process is lower than the conventional processes (by up to 40% and 25%, respectively) due to the elimination of the C₃ separation section. Life cycle analysis (LCA) was also performed based on plant scale simulation of conventional and PXL processes. These analyses have provided guidance in catalyst design and in choosing materials and operating conditions that favor process economics while lessening environmental footprint.

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3. Liu, D., Chaudhari, R.V., Subramaniam, B. Kinetic Modeling of Propene Hydroformylation in Propane-Expanded Liquid with Rh-Based Complexes, 2016 AIChE annual meeting San Francisco, CA.                 

4. Wattimena F, Heijmen H J. U.S. Patent 4,521,630[P]. 1985-6-4.

5. Devon T J, Phillips G W, Puckette T A, et al. U.S. Patent 5,332,846[P]. 1994-7-26.