Progress 01/15/05 to 01/14/10
Outputs
OUTPUTS: During the past year, experiments towards the use of metal/polymer composite membranes for the low trans fatty acid partial hydrogenation of bleached soybean oil were concluded and overall results were derived and synthesized from the experiments. The impact of temperature, pressure, and hydrogen delivery rate were a focus in interpreting the results. The data collect throughout the project was consolidated and prepared for publication to be available to industry and the public. One presentation at a national meeting was given: Singh, D., Pfromm, P. H., Rezac, M. E., "Behavior of Metal Polymer Composite Membranes for Partial Hydrogenation of Soybean Oil", Session 587, American Institute of Chemical Engineers Annual Meeting, Nashville, TN, November 2009. PARTICIPANTS: Mary Rezac, Project Director; Peter Pfromm, Project co-Director; and Devinder Singh, Graduate Research Assistant. TARGET AUDIENCES: This work aims to inform the commercial producers of partially-hydrogenated vegetable oils and the scientists who conduct research related to this topic. PROJECT MODIFICATIONS: The term date of the project has been extended until 2010 to allow for delays which resulted from difficulties encountered with the Graduate Student visa during year 2.
Impacts
This research has produced a reactor system which can hydrogenate soy oil with only minimal trans fatty acids co-production. Metal polymer composite membranes showed little impact of temperature and pressure on TFA formation. This may be attributed to the ability of the composite membranes to maintain a high concentration of hydrogen at the catalyst. Moreover, while scale-up of a traditional slurry reactor will lead to a further decrease in mass transfer efficiency, a membrane reactor can be scaled-up without impacting mass transfer efficiency. At equivalent extent of hydrogenation, the membrane reactor always had a lower TFA content than the conventional 3-phase system. The order of trans fat formation on different catalysts is: Nickel > Palladium > Pd-Lead > Pt. This is the exact opposite of the order of reaction rate. Parameters which increased hydrogen delivery generally increased reaction rate and decreased TFA formation. These findings may maintain or even increase the market for healthy hydrogenated vegetable oils.
Publications
- Singh, D., Rezac, M. E., Pfromm, P. H., "Partial hydrogenation of soybean oil using metal decorated integral-asymmetric polymer membranes: effects of morphology and membrane properties", Journal of Membrane Science, 348, 99-108, 2010
- Singh, D., Rezac, M. E., Pfromm, P. H., "Partial hydrogenation of soybean oil with minimal trans fat production using a Pt-decorated polymeric membrane reactor", Journal of the American Oil Chemists' Society, 86(1), 93-101, 2009
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Progress 01/15/08 to 01/14/09
Outputs
OUTPUTS: During the past year, the use of metal/polymer composite membranes for the partial hydrogenation of bleached soybean oil was investigated Membrane reactor systems with Platinum, Palladium, Nickel, and alloy catalysts were evaluated and compared to their conventional counterparts. Experiments were completed to understand the impact of processing conditions (reaction temperature and pressure, hydrogen delivery rate of the membranes) and the stability of the membrane reactor system. PARTICIPANTS: Mary Rezac, Project Director; Peter Pfromm, Project co-Director; Devinder Singh, Graduate Research Assistant TARGET AUDIENCES: This work aims to inform the commercial producers of partially-hydrogenated vegetable oils and the scientists who conduct research related to this topic. PROJECT MODIFICATIONS: The term date of the project has been extended until 2010 to allow for delays which resulted from difficulties encountered with the Graduate Student visa during year 2.
Impacts
At equivalent extent of hydrogenation, the membrane reactor always had a lower TFA content than the conventional 3-phase system. . The order of trans fat formation is: Nickel > Palladium > Pd-Lead > Pt. This is the exact opposite of the order of reaction rate. Parameters which increased hydrogen delivery generally increased reaction rate and decreased TFA formation. This research has produced a reactor system which can hydrogenate soy oil with only minimal trans fatty acids co-production. These findings may maintain or even increase the market for healthy vegetable oils.
Publications
- 1. Singh, D., Pfromm, P.H. and Rezac, M. 2009. Partial hydrogenation of soybean oil using metal polymer composite membranes: effect of catalyst dispersion and membrane properties. the Journal of Membrane Science. Submitted.
- 2. Singh, D., Pfromm, P.H. and Rezac, M. 2009. Partial Hydrogenation of Soybean Oil with Minimal Trans Fat Production Using a Pt-Decorated Polymeric Membrane Reactor. JOACS, vol. 86: 93-101.
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Progress 01/15/07 to 01/14/08
Outputs
OUTPUTS: Using the metal/polymer composite membranes, bleached soybean oil was hydrogenated using a novel membrane reactor system and a conventional slurry reactor. At equivalent extent of hydrogenation, the membrane reactor always had a lower TFA content than the conventional 3-phase system. At an iodine value of 100 (a high degree of hydrogenation), the membrane reactor had less than 2 wt% TFA while the conventional system had nearly 10 wt% TFA (Pt as catalyst). Membrane reactor systems with Platinum, Palladium, Nickel, and alloy catalysts have all shown reduced TFA production as compared to their conventional counterparts.
PARTICIPANTS: Mary Rezac, PI; Peter Pfromm, Co-PI; Devinder Singh, Graduate Research Assistant; Brent Dringenberg and Alison Young, Undergraduate Research Assistants.
TARGET AUDIENCES: Producers of partially hydrogenated vegetable oils.
PROJECT MODIFICATIONS: No major modifications.
Impacts
U.S. consumption of partially hydrogenated vegetable oil is nearly 14 billion pounds per year. One side-effect of the traditional hydrogenation process is the production of trans fatty acids that have been proven to increase the risk of coronary heart disease. This research has produced a reactor system which can hydrogenate soy oil with only minimal trans fatty acids co-production. These findings may maintain or even increase the market for healthy vegetable oils.
Publications
- Singh, D., Pfromm, P.H., Rezac, M., "Partial Hydrogenation of Vegetable Oil Using Membrane Reactors", North American Membrane Society Meeting, Orlando, FL, May 2007
- Singh, D., Pfromm, P.H., Rezac, M., "Partial Hydrogenation Of Vegetable Oil Using Membrane Reactor: Composite Membrane Properties And Their Influence On Hydrogenation", AIChE National Conference, Salt Lake City, UT, November 8, 2007
- Rezac, M., "Membranes and Reactors and Integration, Oh My!", University of Arkansas Department of Chemical Engineering, Fayetteville, AR, November 15, 2007
- Singh, D., Pfromm, P.H., Rezac, M., "Partial Hydrogenation of Vegetable Oil Using Membrane Reactors", 36th Biochemical Engineering Symposium, Kansas State University, April 21, 2007
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Progress 01/15/06 to 01/15/07
Outputs
During the second year of this 4-year project, our focus has been on objectives 1 and 2. We prepared integrally-skinned asymmetric membranes from a commercial polyimide and subsequently sputter coated these with platinum. These metal/polymer membranes were evaluated as the central component in a membrane reactor. The membrane reactor approach used relies on a fundamental modification of the mechanism of hydrogen addition while drawing on existing hydrogenation catalysts. Here, a membrane capable of selectively transporting hydrogen while acting to prevent any loss of liquid phase is incorporated in the reactor housing. Oil is pumped on one surface of the membrane where it comes into contact with the catalytic metal surface supported on the polymeric membrane support. The metal catalyst has a high hydrogen coverage that has diffused through the membrane due to an imposed chemical potential driving force. High concentrations of hydrogen on the catalyst surface, and the
resulting decrease in temperature and pressure, promote the hydrogenation reaction at the expense of the cis to trans isomerization. Using the metal/polymer composite membranes, the hydrogenation of bleached soybean oil was evaluated using the membrane reactor system. The oil and membrane were maintained at 70 degrees C. A hydrogen pressure of 3.4 atmospheres was employed. The trans-fatty acid content and iodine value for the experimental case were determined via a gas chromatographic analysis of fatty-acid methyl esters of the reactor content as a function of reaction time. The performance of this novel membrane reactor system was compared to a conventional hydrogenation reported in the literature. At equivalent iodine values, the membrane reactor always had a lower TFA content than the conventional 3-phase system. At an iodine value of 90 (a high degree of hydrogenation), the membrane reactor had about 23 wt% TFA while the conventional system had nearly 45 wt% TFA. The influence of
catalyst concentration on the product quality has been measured. Platinum coated membranes with metal contents ranging from 1 - 350 units were evaluated (1 unit = 0.06 x 10-6 g Pt / g oil in the batch reactor). The metal was available as the coating layer on an underlying polymeric membrane. Product quality, measured as the trans fat content at a given iodine value, was insensitive to catalyst concentration. The influence of hydrogen addition to the reaction mixture has been measured by employing membranes with a range of hydrogen addition rates. The hydrogen addition rate has been varied by a factor of 15. For all membranes tested to date, as the hydrogen addition rate is increased, the production of total trans fats is decreased. We anticipate that there will be a point at which the rate of hydrogen supply is greater than the rate of hydrogen consumption for the hydrogenation reaction and at beyond this point increases in hydrogen addition rates will have little influence on the
product.
Impacts
U.S. consumption of partially hydrogenated vegetable oil is nearly 14 billion pounds per year. Hydrogenation is applied to achieve chemical stability and desired physical properties by eliminating carbon-carbon double bonds. One effect of the traditional hydrogenation process, however, is the production of trans fatty acids that have been proven to increase the risk of coronary heart disease. New FDA regulations require listing of the trans fatty acid content on food labels by 2006. Consumers will likely expect that the amount of trans fatty acids be minimized in the products that they buy. If the TFA levels are not significantly lowered, the market share for hydrogenated vegetable oil may be in jeopardy. If successful, this research will result in a mechanism by which partially hydrogenated vegetable oil can be produced with little or no trans-fatty acid. In so doing, the market for such material will be maintained or even increased.
Publications
- Singh, D., Pfromm, P., Rezac, M., "Partial Hydrogenation of Vegetable Oil with Less Trans Fatty Acid using Membrane Reactor", North American Membrane Society Meeting, Chicago, IL, May 2006.
- Rezac, M., Pfromm, P., Singh, D., "Partial Hydrogenation of Vegetable Oil with Less Trans Fatty Acid using Membrane Reactor", US Department of Agriculture, Project Managers Meeting, Washington, D.C., July 2006.
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Progress 01/15/05 to 01/14/06
Outputs
The main objectives of this work as identified in the original proposal are to: 1. Demonstrate that a metal/polymer membrane reactor can be used to effectively catalyze the hydrogenation of vegetable oil to a product with low trans fatty acid content. 2. Evaluate the influence of process parameters (temperature, residence time, hydrogen pressure, and membrane characteristics) on the performance of the membrane reactor system for the hydrogenation of vegetable oil. 3. Evaluate the stability of the catalytic membrane for repeated use. During the first year of this 4-year project, our focus has been on objective #1. We prepared integrally-skinned asymmetric membranes from a commercial polyimide. The polymeric membranes were characterized and those which had a ratio of hydrogen to nitrogen transport rates of more than 50 were subsequently sputter coated with platinum. The platinum coatings were approximately 5 nm thick, but contained a few molecular defects - areas where
the underlying polymeric layer were not completely covered with platinum. These metal/polymer membranes were evaluated as the central component in a membrane reactor. The membrane reactor approach used relies on a fundamental modification of the mechanism of hydrogen addition while drawing on existing hydrogenation catalysts. Here, a membrane capable of selectively transporting hydrogen while acting to prevent any loss of liquid phase is incorporated in the reactor housing. Oil is pumped on one surface of the membrane where it comes into contact with the catalytic metal surface supported on the polymeric membrane support. The metal catalyst has a high hydrogen coverage that has diffused through the membrane due to an imposed chemical potential driving force. High concentrations of hydrogen on the catalyst surface, and the resulting decrease in temperature and pressure, promote the hydrogenation reaction at the expense of the cis to trans isomerization. Using the metal/polymer
composite membranes, the hydrogenation of bleached soybean oil was evaluated using the membrane reactor system. The oil and membrane were maintained at 70 degrees C. A hydrogen pressure of 3.4 atmospheres was employed. The trans-fatty acid content and iodine value for the experimental case were determined via a gas chromatographic analysis of fatty-acid methyl esters of the reactor content as a function of reaction time. The performance of this novel membrane reactor system was compared to a conventional hydrogenation reported in the literature. At equivalent iodine values, the membrane reactor always had a lower TFA content than the conventional 3-phase system. At an iodine value of 90 (a high degree of hydrogenation), the membrane reactor had about 23 wt% TFA while the conventional system had nearly 45 wt% TFA. These promising preliminary results are serving as the basis for further optimization of the membrane reactor performance. During the next year, our efforts will focus on
continued evaluation of objective #2.
Impacts
U.S. consumption of partially hydrogenated vegetable oil is nearly 14 billion pounds per year. Hydrogenation is applied to achieve chemical stability and desired physical properties by eliminating carbon-carbon double bonds. One effect of the traditional hydrogenation process, however, is the production of trans fatty acids that have been proven to increase the risk of coronary heart disease. New FDA regulations require listing of the trans fatty acid content on food labels by 2006. Consumers will likely expect that the amount of trans fatty acids be minimized in the products that they buy. If the TFA levels are not significantly lowered, the market share for hydrogenated vegetable oil may be in jeopardy. If successful, this research will result in a mechanism by which partially hydrogenated vegetable oil can be produced with little or no trans-fatty acid. In so doing, the market for such material will be maintained or even increased.
Publications
- Singh, S., Dringenberg, B., Pfromm, P. H., Rezac, M. E., "Partial Hydrogenation of Vegetable Oil using Membrane Reactor Technology", Session 444 "Advances in Food Engineering", Paper 444b, AIChE 2005 Annual Meeting, Cincinnati, OH, November 2005
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