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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: CRITICAL FLUIDS FOR PROCESSING AGRIMATERIALS

Location: Functional Foods Research Unit

2008 Annual Report


1a.Objectives (from AD-416)
The primary goal of this project is to demonstrate the technical and commercial feasibility of using critical fluids and heterogeneous catalysts to extract and process agrimaterials into value-added products. The long-term objective of this project is to develop new chemical processes to produce high-value products from plant materials. Over the next three years, we will focus on the following objectives:

Objective 1: Develop methods for the conversion of agrimaterials to platform chemicals. There are two aspects to this objective: a) the oxidation of seed oils to platform chemicals such as diacids and hydroxyacids; and b) the design and development of better catalysts for regioselective transformations, including the selective addition of aromatics to the double bond of unsaturated fatty acids.

Objective 2: Develop commercially viable processes based on critical fluids to convert ligno-cellulosic materials to fermentable sugars as well as convert vegetable oils to high-value products. There are two sub-objectives to this objective: a) develop commercially viable processes based on critical fluids such as carbon dioxide (CO2), water and/or ethanol to pretreat ligno-cellulosic biomass prior to its conversion via enzymatic hydrolysis to fermentable sugars; and b) use CO2-based critical fluids to improve the commercial viability of processes for enzymatically converting vegetable oils to high-value products such as feruloylated monoacyl- and diacylglycerides. Critical fluid processes will be evaluated for enhancement of these conversions and integration with downstream recovery processes for these high-value products.


1b.Approach (from AD-416)
New polyoxometalate catalysts will be synthesized, characterized and used to oxidatively cleave double bonds in oleic and petroselinic acids to form platform chemicals. This research will also evaluate critical fluid processes for the conversion of vegetable oils to high-value products, and critical fluid pretreatments for converting ligno-cellulosic biomass to fermentable sugars.


3.Progress Report
A new project was started to investigate the impact catalysts can have on the stability and quality of pyrolysis oil obtained from the liquefaction of lignin and seed oils. A bench-top pyrolysis apparatus was designed and built which gives us the ability to quantitatively measure components of the gas phase, the liquid phase composition and the char component. This allows for the rapid screening of heterogeneous catalysts. We have been able to examine a number of catalysts and have seen changes in gas and liquid compositions resulting from catalyst selection. The liquefaction of lignin over the zeolite H-ZSM-5 gives a liquid fraction consisting of simple aromatics and polyaromatic compounds, whereas catalysts containing molybdenum yield higher amounts of simple aromatics without formation of the undesirable polyaromatic compounds. Similar results are seen when soybean oil is pyrolyzed over these two catalysts. H-ZSM-5 causes deoxygenation and formation of simple aromatics and the molybdenum-containing catalysts produce a liquid fraction consisting of alkanes and alkenes while also producing a large amount of hydrogen in the gas phase.

A new group of catalysts have been developed that improves the selectivity of ether formation in the reaction of phenol with hydroxyfatty acids. These catalysts are bifunctional, consisting of an alcohol group and an acid group, and it is now thought that the function of the alcohol is to prevent the ether from reentering the active sites of the catalyst and isomerizing.

Carbon dioxide explosion experiments of ligno-cellulosic materials have been conducted on switchgrass using carbon dioxide at several combinations of pressure and temperature, as well as with ethanol. These materials will be subjected to hydrolysis and fermentation to determine differences in their subsequent ethanol yields.

An enzymatic reactor was designed and constructed utilizing supercritical carbon dioxide to improve the conversion of soybean oil to SoyScreen™. Using this reactor, the product yields using both static as well as cycling carbon dioxide were compared. The cycling carbon dioxide gave significantly higher yields than did the static carbon dioxide. This process will lead to higher yields of the product SoyScreen™. This research addresses NP 306, Component 2.


4.Accomplishments
1. CRITICAL FLUID FRACTIONATION OF CRUDE ENZYMATIC REACTION MIXTURES. Chemical reactions generally result in a mixture of unreacted starting material and by-products in addition to the desired product. A continuous fractionation method employing liquid carbon dioxide was developed, which removed essentially all of the unwanted starting material as well as by-products to yield the desired purified vegetable oil-derived product. This technology removed essentially all of the unwanted materials and did so without subjecting the desired product to the heat generally used during vacuum distillation. Heat has previously been demonstrated to adversely affect the product. This research provides technology which allows isolation of pure products without subjecting them to damaging heat. This technology is envisioned to apply to the purification of SoyScreen™ as well. The research addresses NP 306, Component 2, Problem Area 2c.


5.Significant Activities that Support Special Target Populations
None.


6.Technology Transfer

Number of New CRADAS1
Number of Non-Peer Reviewed Presentations and Proceedings3

Review Publications
Winkler, J.K., Rennick, K.A., Eller, F.J., Vaughn, S.F. 2007. Phytosterol and tocopherol components in extracts of corn distiller's dried grain. Journal of Agricultural and Food Chemistry. 55:6482-6486.

Eller, F.J., Taylor, S.L., Compton, D.L., Laszlo, J.A., Palmquist, D.E. 2008. Counter-current liquid carbon dioxide purification of a model reaction mixture. Journal of Supercritical Fluids. 43(3):510-514.

Stevenson, D.G., Inglett, G.E., Chen, D., Biswas, A., Eller, F.J., Evangelista, R.L. 2008. Phenolic content and antioxidant activity of supercritical carbon dioxide-treated and air-classified oat bran concentrate microwave-irradiated in water or ethanol at varying temperatures. Food Chemistry. 108(1):23-30.

Peterson, S.C., Eller, F.J., Fanta, G.F., Felker, F.C., Shogren, R.L. 2008. Comparison of the effects of critical fluid and reflux-extracted techniques on cornstarch pasting properties. Carbohydrate Polymers. 71(1):74-79.

Jackson, M.A., List, G.R., Palmquist, D.E. 2008. Low trans fat spreads and shortenings from a catalyst-switching strategy. Journal of the American Oil Chemists' Society. 85:481-486.

Stevenson, D.G., Eller, F.J., Jane, J., Inglett, G.E. 2008. Structure and physicochemical properties of defatted and pin-milled oat bran concentrate fractions separated by air classification. International Journal of Food Science and Technology. 43:995-1003.

Last Modified: 8/27/2014
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