Submitted to: European Journal of Science and Lipid Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/17/2011
Publication Date: 1/1/2012
Citation: Lew, H.N., Hoh, E., Foglia, T. 2012. Improved synthesis and characterization of saturated branched-chain fatty acid isomers. European Journal of Science and Lipid Technology. 114:213-221. Interpretive Summary: Isomeric mixtures of saturated methyl branched-chain fatty acids (sbc-FAs) are commonly referred to as isostearic acids (IA). There is much interest in IA because they have good lubricating properties at low temperatures and good oxidative stability at higher operating temperatures. Due to these properties IA are used in various applications, such as lubricant and fuel additives, surfactants, coatings, soaps, and body washes. Present methods of producing IA, however, provide them as co-products, which impacts their availability and cost. This paper describes an improved catalytic synthesis process for converting linear-chain fatty acids to sbc-FA isomers in high yields using a base-modified zeolite catalyst. The used catalysts can be recycled for at least ten times. This new route to sbc-FA isomers represents an environmentally benign and economically feasible alternative to this important class of compounds.
Technical Abstract: The development of viable technologies for producing green products from renewable fats and oils is highly desirable since such materials can serve as replacements for non-renewable and poorly biodegradable petroleum-based products. Mixtures of saturated branched-chain fatty acid isomers (sbc-FAs), commonly referred to as isostearic acid, are important intermediates for the production of biodegradable lubricants, cosmetics, emollients, and hydraulic fluids. Present methods for producing sbc-FAs, however, often give low yields of sbc-FAs or sbc-FA preparations with a high content of dimer acid fatty acid co-products. This study reports an improved route to synthesizing sbc-FAs from monounsaturated fatty acids using a modified H-Ferrierite zeolite catalyst with small amounts of triphenylphosphine additive. The yields of sbc-FAs (up to 80 wt%) and co-products (up to15 wt%) were determined using a modification of a previously reported GC method.. A more detailed analysis of the distribution of sbc-FA isomers in the products was made by the combined use of GC×GC-ToF-MS. Additionally, it was found that the H-Ferrierite zeolite catalyst was recyclable and reusable up to 10 times without significant loss of activity and selectivity for sbc-FAs.