Optimizing Reaction Conditions for the Isomerization of Fatty Acids and Fatty Acid Methyl Esters to Their Branch Chain Products

摘要

In order to improve the oxidative stability and cold flow properties of oleic acid or methyl oleate, branch chain isomerization was conducted using a beta zeolite catalyst. Reaction conditions of temperature (200–300 °C), pressure (0.1–3.0 MPa), and co-catalyst (0–2 wt%) were optimized based on branch chain conversion and the cloud point of the ester following the isomerization reaction of oleic acid or methyl oleate. Fourier transform infrared spectroscopy (FTIR) and Gas Chromatograph equipped with Mass Spectrometry (GC/MS) analyses were used to analyze and quantify the isomerization product samples, while the cloud point of each sample was tested. The lowest and therefore, best cloud point measured was −15.2 °C at conditions of 200 °C, 3 MPa, and 2% co-catalyst using methyl oleate as a starting material. The highest branch chain conversion achieved was 50% under conditions of 300 °C, 1.5 MPa and 0% co-catalyst using oleic acid as a starting material. The use of oleic acid and methyl oleate is based on whether it is optimal to carry out the skeletal isomerization before or after the esterification reaction. Performing the isomerization reaction on the ester was preferred over the fatty acid based on the trans isomerization and cloud point results. Reducing the unbranched trans isomers was desirable in obtaining a low cloud point.