An analysis of mass-transfer effects in hydroformylation reactions

Bhattacharya, Arijit; Chaudhari, Raghunath V.

doi:10.1021/ie00066a018

Cited by 13 publications

(8 citation statements)

References 7 publications

(7 reference statements)

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“…At low power input per unit volume, the rate increases with increasing power input; it then passes through a maximum and eventually becomes independent of the power input provided by the impeller. This kind of behavior was also observed by Bhattacharya and Chaudhari, 15 who studied the homogeneous one-phase hydroformylation of 1-hexene.…”

Section: Effect Of Catalyst Concentrationsupporting

confidence: 76%

Mass-Transfer Effects in the Biphasic Hydroformylation of Propylene

Cents

Brilman

Versteeg

2004

Ind. Eng. Chem. Res.

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The hydroformylation of propylene to butyraldehyde is an important industrial process. In this reaction system, carbon monoxide, hydrogen, and propylene are converted to n-butyraldehyde in an aqueous phase containing a water-soluble rhodium catalyst. This reaction system consists therefore of three different phases: the aqueous catalyst phase, the organic butyraldehyde phase, and the gas phase. A modeling study indicated that an optimum value of the production rate is reached at a certain power input. It was shown that mass transfer plays an important role in this reaction system and that accurate knowledge of the mass-transfer parameters in the gasliquid-liquid system is necessary to predict and to optimize the production rate. Mass-transfer experiments with CO, H 2 , and propylene in water and in solutions consisting of water with different amounts of n-butyraldehyde were carried out in a stirred autoclave. The results indicated that the addition of small amounts of butyraldehyde caused a relatively small increase increase in k L a, which was probably caused by a larger increase of the gas-liquid interfacial area, a, accompanied by a decrease in the mass-transfer coefficient, k L. Near the point of maximum solubility of butyraldehyde, a strong (factor of 3) increase in k L a was observed. The most logical explanation for this is an increase in k L , because measurement of the interfacial area did not show such an increase. This increase in k L , i.e., the disappearance of the initial decrease, might be due to the disappearance of the rigid layer of butyraldehyde molecules at the gas-liquid interface by formation and spreading of a butyraldehyde layer around the bubble.

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Section: Effect Of Catalyst Concentrationsupporting

confidence: 76%

Mass-Transfer Effects in the Biphasic Hydroformylation of Propylene

Cents

Brilman

Versteeg

2004

Ind. Eng. Chem. Res.

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“…26 The liquid phase of each experiment became essentially saturated with dissolved CO and H2 in the first 60 s. Mass transfer effects are known to severely complicate the interpretation of kinetic data from hydroformylation reactions. 27 In any single 8 h kinetic experiment, less than 0.01 mol conversion (or 3%) of alkene to aldehyde occurred. Therefore, the partial pressures of hydrogen and carbon monoxide in the closed-batch autoclave changed less than 1% during the each 8 h experiment.…”

Section: Methodsmentioning

confidence: 99%

“…Since the maximum observed rate of hydroformylation in this study was 4 × 10 -7 mol s -1 , all experiments belong to the category of infinitely slow reaction with respect to gas−liquid mass transfer (i.e., the kinetic regime, Hatta category H) . The liquid phase of each experiment became essentially saturated with dissolved CO and H 2 in the first 60 s. Mass transfer effects are known to severely complicate the interpretation of kinetic data from hydroformylation reactions …”

Section: Methodsmentioning

confidence: 99%

Unmodified Rhodium-Catalyzed Hydroformylation of Alkenes Using Tetrarhodium Dodecacarbonyl. The Infrared Characterization of 15 Acyl Rhodium Tetracarbonyl Intermediates

1999

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The homogeneous catalytic hydroformylation of 20 alkenes was studied, starting with Rh4(CO)12 as catalyst precursor in n-hexane as solvent, using high-pressure in-situ infrared spectroscopy as the analytical tool. Five categories of alkenes were studied, namely, cycloalkenes (cyclopentene, cycloheptene, cyclooctene, and norbornene), symmetric internal linear alkenes (3-hexene, 4-octene, and 5-decene), terminal alkenes (1-hexene, 1-octene, 1-decene, 1-dodecene, and 1-tetradecene), methylene cycloalkanes (methylene cyclopropane, methylene cyclobutane, methylene cyclopentane, and methylene cyclohexane), and branched alkenes (2-methyl-2-butene, 2-methyl-2-pentene, 2-methyl-2-heptene, and 2,3-dimethyl-2-butene). The typical reaction conditions were T = 293 K, P H2 = 2.0 MPa (0.018 mol fraction), P CO = 2.0 MPa (0.033 mol fraction), [alkene]0 = 0.1−0.02 mol fraction, and [Rh4(CO)12]0 = 6.6 × 10-5 mol fraction. In each experiment, with the exception of those involving methylene cyclopropane and the branched alkenes, the precursor Rh4(CO)12 was converted in good yield to the corresponding observable mononuclear acyl rhodium tetracarbonyl intermediate RCORh(CO)4. Due to the spectral characteristics, the intermediate RCORh(CO)4 is assigned a trigonal bipyrimidal geometry in all cases with C s symmetry, with the acyl group taking an axial position. Under the present conditions, the cycloalkenes result in one acyl complex, the symmetric internal linear alkenes result in two acyl stereoisomers, the terminal alkenes result in three acyl complexes (two are stereoisomers), and the methylene cycloalkanes result in two acyl complexes. The first four categories of alkenes gave rise to slightly different spectral wavenumbers and relative intensities for the complexes, namely, cycloalkenes {2109 (0.41), 2063 (0.46), 2037 (0.72), 2019 (1.0), 1699 cm-1 (0.16)}, symmetric internal linear alkenes {2108 (0.43), 2061 (0.45), 2037 (0.84), 2019 (1.0), 1693 cm-1 (0.12)}, terminal alkenes {2110 (0.35), 2064 (0.46), 2038 (0.72), 2020 (1.0), 1703 cm-1 (0.16)}, and methylene cycloalkanes {2110 (0.33), 2064 (0.46), 2038 (0.72), 2020 (1.0), 1704 cm-1 (0.24)}. Finally, the approximate turnover frequencies (TOF) for each system were also calculated. It was found that the TOFs vary from 0.04 to 0.11 min-1 between alkene categories. Thus, to a first approximation, the primary differences in rates of hydroformylation are due to the conversion of Rh4(CO)12 and not TOFs. This answers a long-standing question concerning hydroformylation rates.

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“…Since the maximium observed rate of hydroformylation in this study was 3 × 10 -6 mol s -1 , all experiments belong to the category of infinitely slow reaction with respect to gas−liquid mass transfer (i.e., the kinetic regime, Hatta category H) . The liquid phase of each experiment became essentially saturated with dissolved CO and H 2 in the first 60 s. Mass transfer effects are known to severely complicate the interpretation of kinetic data from hydroformylation reactions …”

Section: Methodsmentioning

confidence: 99%

Unmodified Homogeneous Rhodium-Catalyzed Hydroformylation of Styrene. The Detailed Kinetics of the Regioselective Synthesis

Feng

Garland

1999

Organometallics

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The homogeneous regioselective catalytic hydroformylation of styrene to (()-2-phenylpropanal and 3-phenylpropanal was studied starting with Rh 4 (CO) 12 as catalyst precursor in n-hexane as solvent. The reaction conditions were T ) 298-313 K, P H2 ) 0.27-1.01 MPa (0.002-0.0074 mol fraction), P CO ) 3.0-6.0 MPa (0.042-0.075 mol fraction), [Rh 4 (CO) 12 ] o ) 3.5 × 10 -5 to 1.7 × 10 -4 mol fraction, and [C 8 H 8 ] o ) 0.118-0.349 mol fraction. Quantitative high-pressure in-situ infrared spectroscopic measurements were made under isobaric and isothermal conditions during the 5-h kinetic experiments. In all experiments, the disappearance of the precursor Rh 4 (CO) 12 resulted in the formation of two observable acyl intermediates, namely the major isomer (()-PhCH(CH 3 )CORh(CO) 4 and the minor isomer PhCH 2 CH 2 CORh(CO) 4 . Clean, high-signal-to-noise spectra of the two intermediates (()-PhCH(CH 3 )CORh(CO) 4 and PhCH 2 CH 2 CORh(CO) 4 were obtained. The disappearance of Rh 4 -(CO) 12 was found to followed the rate expression rate ) k o R [Rh 4 (CO) 12 ] 1.0 [CO] 1.3 [H 2 ] 0.9 [C 8 H 8 ] 0.15 where k o R ) (κT/h)exp(-62.6 kJ/(mol RT)) + 37.2 J/(mol R)). This rate expression suggests that cluster fragmentation of Rh 4 (CO) 12 proceeds via CO addition and polyhedron opening as the first step. The hydrogenolysis of (()-PhCH(CH 3 )CORh(CO) 4 to yield the major product (()-PhCH(CH 3 )CHO was found to follow the rate expression rate ) k o [PhCH(CH 3 )CORh-(CO) 4 ] 1.0 [CO] -1.0 [H 2 ] 1.0 [C 8 H 8 ] 0.0 with k o ) (κT/h)exp(-78.8 kJ/(mole RT) + 15.2 J/(mol R), and the hydrogenolysis of PhCH 2 CH 2 CORh(CO) 4 to yield the minor product PhCH 2 CH 2 -CHO was found to follow the rate expression rate ) k o γ [PhCH 2 CH 2 CORh(CO) 4 ] 1.0 [CO] -1.0 -[H 2 ] 1.0 [C 8 H 8 ] 0.0 with k o γ ) (κT/h)exp(-113 kJ/(mol RT)) -102 J/(mol R). The two rate expressions for hydrogenolysis are consistent with (1) equilibrium controlled dissociation of a CO ligand from the acyl intermediates to form coordinatively unsaturated species, (2) a rate-limiting step involving hydrogen activation on the 4-coordinate species, and (3) product formation accompanied by the formation of a transient species {HRh(CO) 3 }.

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An analysis of mass-transfer effects in hydroformylation reactions

Cited by 13 publications

References 7 publications

Mass-Transfer Effects in the Biphasic Hydroformylation of Propylene

Mass-Transfer Effects in the Biphasic Hydroformylation of Propylene

Unmodified Rhodium-Catalyzed Hydroformylation of Alkenes Using Tetrarhodium Dodecacarbonyl. The Infrared Characterization of 15 Acyl Rhodium Tetracarbonyl Intermediates

Unmodified Homogeneous Rhodium-Catalyzed Hydroformylation of Styrene. The Detailed Kinetics of the Regioselective Synthesis

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