(431a) Enhanced Hydroformylation of Propylene in Propane-Expanded Liquids with Rh-Based Complexes

Enhanced
Hydroformylation of Propylene in Propane-Expanded Liquids with Rh-based
Complexes

Dupeng Liu, ^{1, 2} Zhuanzhuan
Xie, 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 increased the
availability of C₂-C₅ alkanes (the so-called natural gas
liquids or NGLs) and opportunities for their utilization in novel ways. For example,
in a typical propane dehydrogenation process, the per pass conversion is only
about 50%.¹ The separation of propane and propylene
mixtures is highly energy and capital intensive. In this talk, we propose a
process that combines propane dehydrogenation and propylene hydroformylation.
The unreacted propane from the dehydrogenation section, an inert component during
hydroformylation, is used to form a propane-expanded liquid phase to promote
regioselective hydroformylation of propylene. In this manner, enrichment of the
propane stream is achieved without energy intensive separation. Previously, we
had reported on the beneficial effects of carbon dioxide expanded liquids for
hydroformylation with Rhodium-based catalyst.^2-3
Here we exploit propane-expanded reaction medium for performing propylene
hydroformylation with Rhodium-based catalyst. At typical reaction temperatures
(70°C for example),  it is found that both propane and propylene can volumetrically
expand reaction mixtures significantly (by up to two-fold with 15 bar propane or
17 bar propylene).  These experimental observations match well with simulation
results. It is also shown that H₂/CO ratio in the propane-expanded
liquid phase (containing propylene and dissolved catalyst complex), a key
determinant of the turnover frequency and regioselectivity, can be easily tuned
to maximize these performance metrics. For example, the regioselectivity is
enhanced by more than threefold in propane-expanded toluene relative to neat
toluene as solvent. Systematic investigations of the effects of reaction
parameters such as syngas partial pressure, catalyst concentration, ligand mass
fraction and propylene pressure on activity and selectivity will be presented,
along with preliminary economic analysis.

1.              http://www.cbi.com/images/uploads/tech_sheets/CatofinDehyrogenation-12.pdf

2.              Xie
Z, Fang J, Subramaniam B, Maiti SK, Snavely W, Tunge JA. Enhanced
hydroformylation by carbon dioxide-expanded media with soluble Rh complexes in
nanofiltration membrane reactors. AIChE Journal. 2013;59(11):4287-4296.

3.              Fang
J, Jana R, Tunge JA, Subramaniam B. Continuous homogeneous hydroformylation
with bulky rhodium catalyst complexes retained by nano-filtration membranes. Applied
Catalysis A: General. 2011;393(1–2):294-301.