Location: Bio-oils Research
2020 Annual Report
Objectives
Objective 1: Enable, from a technological standpoint, new commercial separation processes for the production of marketable low-cost high-purity fatty acids.
Objective 2: Enable new commercial products derived from fatty acid esters.
Objective 3: Enable new commercial biobased additives for applications in lubricants.
• Sub-objective 3.A. Develop novel and cost-competitive structures of biobased additives and base oils.
• Sub-objective 3.B. Investigate tribological property of novel biobased additives and base oils and use results to optimize the respective chemical structures.
This project is aimed at developing enabling new commercial technologies, processes, and biobased products for various markets including for: remediation (specifically heavy metal remediation to include water treatment/purification); lubricant additives; lubricant base oils; and chemical additives. The technologies and products from this research will be competitive in cost and performance to those currently in the respective markets. The biobased products targeted in this project will result in significant improvements to the U.S. economy and the environment as well as to the safety and health of the American people.
Approach
(1) This approach outlines work to be performed related to a) screening of feedstock oil properties and quality; b) design of the membrane-based process Step 1 to remove polyunsaturated fatty acids and enrich saturated fatty acids/ monounsaturated fatty acid (MUFA) concentrations in fatty acid or fatty acid methyl ester (FAME) mixtures; c) evaluate two techniques for the design of process Step 2 to efficiently separate and enrich individual MUFA (oleic and erucic acids) with high yield and purity; and d) integrate designs for Steps 1 and 2 into a single process to fractionate fatty acid mixtures to produce valuable MUFA with high yield and purity. These items present a series of decision points that will be addressed during the course of the research project.
(2)Recent research within the unit has shown thioalkyl derivatives of vegetable oils can be used in heavy metal remediation applications with the thioalkyl derivatives acting as metal-coordinating agents for silver ions. Building on these successful findings, new compounds featuring sulfur as the source of binding or chelation will be the primary objective. The initial feedstocks to be examined will be monounsaturated fatty compounds. This will be followed by the more chemically challenging di- and tri-unsaturated fatty compounds and, finally, vegetable oils. Emphasis will be placed on industrial oil feedstocks with enhanced sustainability. Additionally, materials from Objective 1, as they become available, will serve as unique, valuable starting materials.
(3a) New biobased additives and base oils will be synthesized from commodity oils and their derivatives. Commodity vegetable oils comprise fatty acids with unsaturation that can be used as reactive sites for chemical modification. In addition to commodity vegetable oils, polymercaptanized soybean oil, which is produced in large quantities from abundant soybean oil and cheap hydrogen sulfide will be used. Other biobased feedstocks to be used in the synthesis include: FAME, obtained from the biodiesel process, especially those with unsaturation on their hydrocarbon chains; esters of fatty acid with various alcohol structures; etc. (3b) The new biobased additives will be first investigated for their compatibility with standard base oils. Additives found to be incompatible will be investigated using various approaches to make them more compatible. Only compatible additives will be allowed into the next phase which involves the investigation of their effectiveness at performing the specific tasks relevant to its application. Additives will be investigated relative to commercial reference additives using established tests for each application. Various concentrations of the additives in each base oil will be prepared and subjected to the respective tests. Based on these results, optimum concentrations of the additives will be determined.
Progress Report
This is the final report, which terminated in August 2020. See the report for the replacement project, 5010-41000-187-00D, "Versatile Biobased Products with Multiple Functions” currently under review by OSQR.
This project has produced new biobased products and processes that have contributed to the growth of the farm economy; and has also produced improvements to the environment and to the health and well-being of citizens. These discoveries have been detailed in four previous reports, and some examples include: new biobased dialkyl phosphonates with superior anti-wear properties from vegetable oils and fatty acid methyl esters (FAMEs); new thioalkyl derivatives of fatty esters obtained from soybean and other vegetable oils using the biodiesel process for environmental remediation of wastewater contaminated with heavy metals and other industrial applications; mathematical models for predicting the temperature for gel or solid formation in liquid FAME mixtures, useful for preventing plugging problems during flow through pipelines and filters; and new high-performance ultra-low viscosity composite base fluids containing up to 40% biobased base oils derived from soy, with lower friction and lower wear for environmentally friendly hydraulic fluid application.
A method was developed to assess the shelf-life of biodiesel stored at low temperatures (25 °C). During long-term storage, oxidation from contact with air can degrade biodiesel fuel quality. The oxidation kinetics of different biodiesel samples were investigated using pressurized-differential scanning calorimetry (PDSC). The data was used to develop mathematical models to predict the shelf-life of biodiesel at different temperatures. This research will benefit biodiesel fuel producers, terminal operators and other users that need to store biodiesel during warmer weather.
Investigation of Thiol-Michael addition for Functionalizing Vegetable oils. Functionalization of vegetable oils by addition across the double bonds is an important route in the development of biobased products. Addition reactions were studied for grafting functionalities such as anhydrides to mercaptanized lipids. Mercaptanized lipids have one or more thiol groups in their structures. Two grafting methods were investigated: (1) a radical-initiated thiol-ene reaction, and (2) a base-catalyzed thiol-Michael addition reaction. Low yields were observed with the radical thiol-ene reaction; while the base-catalyzed thiol-Michael addition showed inconsistent results. We attribute the inconsistency of the thiol-Michael addition to the decomposition of products during Gas Chromatography analysis, which involves vaporizing the product mixture to separate the components at elevated temperatures. Alternative analysis methods (such as Nuclear Magnetic Resonance, Raman spectroscopy) will be explored. This work demonstrates the need for alternative methods of analysis, especially ones that can be applied in-situ, such as Raman spectroscopy.
Accomplishments
1. Novel biobased lubricant additive. Commercial base oils lack certain qualities that make them unsuitable as a lubricant and need to have additive packages to meet these requirements. Most commercial additive packages are petroleum-based and are not safe for the environment, thus new biobased lubricant additives are highly desirable. ARS researchers in Peoria, Illinois, developed a novel soybean oil fatty acid methyl ester disulfide, SOY-FAME-S2, from polymercaptanized soybean oil. Blends of SOY-FAME-S2 (1-10%) in base oils and vegetable oils showed increased oxidative stability and better lubrication properties than similar blends without this new additive. These new materials could be a commercial replacement for current petroleum-based additives. Application of these new biobased additives will allow the production of environmentally friendly lubricants, increase the utilization of soybean and other seed oil crops, and enhance the economic security of rural communities.
2. New cold flow index for biodiesel. Biodiesel is composed of mixture of fatty acid methyl esters (FAMEs) with high melting point, which can adversely affect its cloud point (CP). The CP is defined as the highest temperature where haziness of biodiesel is observed. The new index, called the long-chain saturation factor (LCSF), was developed by ARS scientists in Peoria, Illinois, to correlate the effects of individual FAME components on the CP of biodiesel. The developed index accurately predicts the temperatures at which solid formation begins. This hinders biodiesel flow through fuel systems causing startup and operability problems of engines. The index provides a useful tool to fuel producers, blenders, distributors and consumers to determine if biodiesel will perform in cooler weather. The index can also be used to optimize the FAME composition of biodiesel for use in cooler climates, which will increase its utilization and the demand for soybean and other crops used in biodiesel production.
3. Safe route to soy-based polymercaptan. Soybean based polymercaptan has been demonstrated to be a good candidate for applications in polymers and as a biobased lubricant additive. However, its production involves the use of the highly toxic hydrogen sulfide gas. ARS researchers from Peoria, Illinois, have successfully completed the first step of an alternative safe route for its synthesis that uses less toxic chemical instead of hydrogen sulfide gas. The synthesized intermediate material was obtained in higher yields and purity than in the original route. This work is a step forward towards a less-hazardous route to biobased polymercaptan. Safe synthesis of soy-based polymercaptans will increase its utilization in lubrication and open a new demand for soybean and other oilseed crops.
Review Publications
Dunn, R.O. 2020. Correlating the cold filter plugging point to concentration and melting properties of fatty acid methyl ester (biodiesel) admixtures. Energy and Fuels. 34(1):501-515. https://doi.org/10.1021/acs.energyfuels.9b03311.
Biresaw, G., Bantchev, G.B., Lansing, J., Harry-O'kuru, R.E., Chen, Y. 2020. Sulfurized methyl esters of soya fatty acids: Synthesis and characterization. Tribology Letter. 68. Article 61. https://doi.org/10.1007/s11249-020-01292-y.
Bantchev, G.B., Vermillion, K.E., Biresaw, G., Berhow, M.A. 2019. Acetylthiostearates – mass spectroscopy and NMR characterization. Journal of Sulfur Chemistry. 41(2):154-169. https://doi.org/10.1080/17415993.2019.1699928.
Chen, Y., Biresaw, G., Cermak, S.C., Isbell, T., Ngo, H.L., Chen, L., Durham, A.L. 2020. Fatty acid estolides: A review. Journal of the American Oil Chemists' Society. 97(3)231-241. https://doi.org/10.1002/aocs.12323.
Biresaw, G. 2020. Vegetable oils in lubrication. In: Shahidi, F., editor. Bailey's Industrial Oil and Fats Products. 7th edition, Vol. 7. New York, NY: John Wiley & Sons. p. 213-241. https://doi.org/10.1002/047167849x.bio055.pub2.
Harry-O'Kuru, R.E., Biresaw, G., Xu, J. 2019. Thermal behavior of polyformates of milkweed and soybean oils. Journal of Applied Polymer Science. 136(48):48225. https://doi.org/10.1002/app.48225.
