Project : USDA ARS

ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Bio-oils Research » Research » Research Project #429181

Research Project: Value-added Bio-oil Products and Processes

Location: Bio-oils Research

2019 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
Correlations were developed to predict the oxidative stability of fatty acid methyl ester (FAME) mixtures. Fatty derivatives will decompose and degrade if they are exposed to oxygen (in air) during storage. The degree of unsaturation in FAME mixtures affects their relative resistance to oxidation. Mixtures with high concentrations of polyunsaturated fatty acids are more susceptible to oxidation than those that are predominantly saturated or monounsaturated. This research established a mathematical correlation between oxidation stability and the degree of unsaturation in FAME mixtures. FAME mixtures are used in biobased diesel fuels (biodiesel), cleaners, solvents and lubricants. Grafting anhydrides to derivatized fatty acid methyl esters (PFAMEs) is the first step in the synthesis of novel biobased lubricant additives proposed in this project. We have successfully grafted an anhydride to a derivatized FAME and achieved up to 61% of product yield. Gas chromatography-mass spectrometry (GC-MS) analysis confirmed the structure of the targeted product and detected no side reaction products in the product mixture. So far, we can purify the product mixture and enrich the targeted product up to 82%. The reaction and purification processes are being optimized.

Accomplishments
1. Low-temperature performance of liquid biobased products. Fatty acid methyl ester (FAME) mixtures (biodiesel) are susceptible to formation of solids that can restrict flow in process streams during cold weather. The cold flow plugging point (CFPP) is a performance test that takes into account the ability of a multi-phase (liquid with solids present) FAME mixture to flow without restriction in pipes and channels. ARS scientists in Peoria, Illinois, developed mathematical correlations to calculate the CFPP of FAME mixtures with diverse composition (fatty acid) profiles. This research increased the fundamental understanding of the solid-liquid phase behavior in fatty acid methyl ester mixtures. Results will be employed in the design of processes for handling FAME mixtures with varying compositions to benefit the growing biodiesel industry in the U.S.

2. Characterization of oleic estolides with gel-permeation chromatography (GPC). Estolides are biobased base oil that are successfully used to formulate high-performing and highly biodegradable engine oils and other lubricants. An important property of estolides is their degree of oligomerization, described by the estolide number (EN). To fully describe the oligomerization, the polydispersity index (PI) is also needed. ARS scientists in Peoria, Illinois, evaluated the applicability of GPC as a method to determine the EN of estolides. They demonstrated that GPC is almost three times more sensitive than traditional methods and also provides additional data about the estolide samples, such as PI. It was concluded that GPC is a better procedure for characterizing the degree of oligomerization of estolides than existing methods. Precise characterization of the degree of oligomerization will help optimize the synthesis of various viscosity grades of estolides.

3. High-performance ultra-low viscosity composite base fluids containing biobased base oils derived from soy. Such composite fluids are obtained by blending petroleum base oils such as polyalphaolefins (PAOs) with biobased base oils derived from vegetable oils. Blending allows for producing composite fluids that meet biocontent requirements (e.g., 34% for 2-cycle engine oil according to the USDA BioPreferred® standard) without compromising cost or performance. Biobased polyester fluids synthesized from soybean oil by ARS scientists in Peoria, Illinois, were investigated for application as ultra-low viscosity composite fluids in collaboration with scientists at Argonne National Laboratory. Ultra-low viscosity composite fluids are preferred for engine oil formulation because they generate very low friction when sheared, which translates into high fuel efficiency, low fuel consumption, low tailpipe emission and improved air quality. The investigation showed that blending up to 40% of biobased polyesters to ultra-low viscosity PAOs caused very slight change in viscosity. In addition, the composite fluid with 40% biobased polyester gave lower friction and more than 10-fold lower wear than either pure PAO or pure polyester. This result indicates that successful commercialization of composite fluids will have the potential to generate new markets for soybean and other seed crops.

U.S. DEPARTMENT OF AGRICULTURE

Bio-oils Research: Peoria, IL