Submitted to: European Journal of Lipid Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2014
Publication Date: 5/27/2014
Citation: Ngo, H. 2014. Improved zeolite regeneration processes for preparing saturated branched-chain fatty acids. European Journal of Lipid Science and Technology. 116:645-652.
Interpretive Summary: Isostearic acids (IA) are important commercially successful biobased products derived from renewable fatty acid materials. They are used in applications including body washes, coatings, cosmetics, lubricant additives, hydraulic fluids and emulsifiers. The current technology to produce IA products is neither efficient nor cost effective. We seek to improve the technology in order to make the IA production process economically viable and environmentally sound. Here, we have reported the development of a regeneration method that allows multiple uses of the solid zeolite catalyst. The process produces IA products which have similar properties to the commercial products and is produced in a much more efficient manner. This catalyst process should enable cost-effective, large-scale production products via solid zeolite-catalyzed reactions.
Technical Abstract: Ferrierite zeolite solid is an excellent catalyst for the skeletal isomerization of unsaturated linear-chain fatty acids (i.e., oleic acid) to unsaturated branched-chain fatty acids (i.e., iso-oleic acid) follow by hydrogenation to give saturated branched-chain fatty acids (i.e., isostearic acid). In order for the isomerization process to be cost effective, the spent zeolite catalyst must be capable of regeneration for subsequent uses. We report a much improved zeolite regeneration protocol. In this protocol, the Ferrierite zeolite is efficiently regenerated by heating at 115 oC for 20 h after each use and treatment with an acid solution after every 5th or 6th use. This approach allows the catalyst to be successfully used at least 20 times without significant decrease in conversion and selectivity. The unused and regenerated catalysts have been thoroughly characterized by attenuated total reflectance infrared spectroscopy (ATP-IR), Karl Fisher calorimeter (KF), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The improved catalyst regeneration protocol reported in this paper should enable cost effective, large scale production of isostearic acid via zeolite-catalyzed skeletal isomerization.