Convenient and Environmentally Friendly Production of Isostearic Acid with Protonic Forms of Ammonium Cationic Zeolites

Abstract

Three ammonium‐cationic zeolites (ferrierite, ZSM5, and zeolite BETA) are individually analyzed to produce branched‐chain fatty acid (i.e., isostearic acid) from unsaturated linear‐chain fatty acid (ulc‐FA) with up to 98% conversion and 80% selectivity. The SiO2/Al2O3 molar ratio of zeolite, amount of water and choice of additive are found to be the key factors for the efficiency of zeolites in this particular reaction. Detailed characterization of zeolites supports the optimization parameters to produce the best results. Large scale production of isostearic acid achieving a 76% selectivity and 96% conversion demonstrates the potential of this system's capability at the pilot scale. Variation in isomeric composition of branched‐chain fatty acid (bc‐FA) product is observed for the three different catalytic methods. Dimer production due to interaction with the external acidic surface of these zeolites has been observed, but it can be suppressed.Practical Application: Lubricant, cosmetic and surfactant fields are examples where these biodegradable isostearic acid and other bc‐FA materials are applied.Three ammonium cationic zeolites (i.e., ferrierite, BETA, ZSM‐5) are used to produce the iso‐oleic acid (precursor of isostearic acid) with high selectivity. The iso‐oleic acid products are found to have different isomeric compositions which could potentially expand the application of the isostearic acid.