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United States Department of Agriculture

Agricultural Research Service

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Research Project: CRITICAL FLUIDS FOR PROCESSING AGRIMATERIALS

Location: Functional Foods Research Unit

2010 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 method for producing spreads and shortenings that is low in trans-fatty acids was developed using a catalyst switching strategy to give basestocks of low trans fat levels. In this method, soy, canola, high-oleic sunflower, and high-oleic safflower oils were hydrogenated to a specific point using a selective catalyst, then the catalyst was switched to a nonselective catalyst to further hydrogenate the product. This strategy can be used with current industrial equipment and commercially available catalysts. A new group of catalysts have been developed that improves the selectivity of ether formation in the reaction of phenol with hydroxyfatty acids derived from Lesquerella. These catalysts are bifunctional consisting of a chloroethyl group and an acid group and it is thought that the chloroethyl group prevents the ether from reentering the active sites of the catalyst and isomerizing. The phenoxyether of lesquerella oil has now been prepared in large enough quantities to allow the bulk properties of the product to be determined and uses proposed. A critical fluid fractionation column for purifying propyl esters from mono-, di-, and triglycerides was designed and built. This column was used to remove the esters without subjecting the mixture to heat and prevented acyl migration in the glycerides observed during standard vacuum distillation. An enzymatic reactor was designed and constructed utilizing critical carbon dioxide to improve the conversion of soybean oil to SoyScreen™. Using this reactor, cycling carbon dioxide gave significantly higher yields than did static carbon dioxide. This process could be used to obtain higher yields of the product SoyScreen™. A project was initiated to investigate the impact catalysts 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 to quantitatively measure components of the gas and liquid phases as well as the char component. 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. When soybean oil is pyrolyzed, 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. An apparatus for conducting carbon dioxide explosion experiments of lignocellusic materials, such as corn stover, was designed and constructed. Corn stover was extracted with carbon dioxide in both a static as well as dynamic fashion using carbon dioxide. The effects of carbon dioxide pressure, temperature, co-solvent ethanol and pressurization times were studied. These materials were subjected to hydrolysis and fermentation to determine differences in their subsequent ethanol yields.


4.Accomplishments
1. Production of new products from Lesquerella oil. Lesquerella is a genus native to the Southwestern United States and is currently being developed as a new oil seed crop due to its novel oil content. New catalysts have been developed which have allowed for the production of an ether of the oil in high yields. This product has potential use as a lubricant or diesel fuel additive.

2. 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 purified the desired product without subjecting it 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 has been used to purify SoyScreen™ and is envisioned to apply to the purification of similar materials as well.

3. Critical fluid mixes for improving enzymatic reactions. Cycling carbon dioxide through an enzyme bed containing the reactants soybean oil and ethyl ferulate resulted in excellent conversion to the desired product, called SoyScreen™. The use of other gases as well as mixtures of various gases through the enzyme bed had a significant effect on the overall conversion to SoyScreen™. This research provides a technology which allows a more efficient conversion of low-value vegetable oil into the value-added product SoyScreen™ as well as other enzymatic conversions.


Review Publications
Jackson, M.A., Appell, M.D. 2009. Increased selectivity in the formation of the phenoxy ether of methyl lesquerolate over chloroalkyl-modified SBA-15-SO3H catalysts. Applied Catalysis A: General. 373:90-97.

Eller, F.J., Moser, J.K., Kenar, J.A., Taylor, S.L. 2010. Extraction and Analysis of Tomato Seed Oil. Journal of the American Oil Chemists' Society. 87:755-762.

Last Modified: 9/10/2014
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