Non-Catalytic Biodiesel Production from Soybean Oil Using Supercritical Methanol

Ashley D'Ann Koh, Taiying Zhang , Carter Johnson, and Gary A. Aurand. Department of Chemical and Biochemical Engineering, The University of Iowa, 4133 Seamans Center, Iowa City, IA 52242

Presently, biodiesel is gaining more popularity as an alternative fuel to petroleum diesel as the demand for fuel from biorenewable resources is increasing due to rising fuel prices, and threats to crude oil sources. The traditional production method in existing biodiesel plants is transesterification of vegetable oils and/or animal fats to produce mono-alkyl esters (biodiesel). However, the process utilizes a corrosive liquid catalyst, which then requires costly downstream removal steps.

An alternative method that we are investigating is a two-step catalyst-free process involving sequential hydrolysis and methyl esterification of soybean oil. The initial hydrolysis reaction separates the glycerol from the fatty acids in the triglycerides of the feed oil. The free fatty acids then undergo methyl esterification in supercritical methanol to produce the methyl esters of the fatty acids without the use of a catalyst. This process will require less refining steps for the products since there is no catalyst to remove. The purpose of this research is to create a more environmentally-friendly and cost effective method of producing biodiesel from local resources.

In order to design a scaled-up reactor and perform an economic analysis of this process, necessary reaction parameters must first be determined through experiment: temperature, pressure, and rate constant. Rate data from the esterification of free fatty acids with supercritical methanol will be presented. Furthermore, the products of experiments will be analyzed by GC-MS.