In an effort to increase utilization of fats and oils with high concentrations of FFA, acid catalysts were investigated at elevated temperatures to determine their efficacy under various operating conditions. Acid-catalyzed alcoholysis of soybean oil using sulfuric, hydrochloric, formic, acetic, and nitric acids was evaluated at 0.1 and 1 wt% loadings at temperatures of 100 and 120°C in sealed ampules, but only sulfuric acid was effective. Kinetic studies at 100°C, 0.5 wt% sulfuric acid catalyst, and nine times methanol stoichiometry provided >99 wt% conversion of TG in 8 h and less than 0.8 wt% FFA concentrations at less than 4 h. Reaction conditions near 100°C at 0.1 to 0.5 wt% were identified as providing the necessary conversions in a 24-h batch cycle while not darkening the product as is typical with high temperatures and catalyst loadings. The oxygen/air contained in the reaction ampules at the onset of the reaction was not sufficient to color the product, but the product darkened if atmospheric air contacted the reacting mixture. The presence of small amounts of stainless steel significantly decreased conversions. FIG. 2.Kinetics of 0.5 wt% sulfuric acid catalyst at 100°C and a 9:1 methanol/TG molar ratio. ME, methyl ester.

This article describes the investigations carried out on the vapor-phase hydrogenolysis of glycerol to acetol over a copper-chromite catalyst in a packed bed flow reactor. The effects of reaction method (liquid-phase vs. vapor-phase mode), vapor-phase reaction with gas feed, reaction temperature, catalyst loading, and hydrogen feed rate were studied to arrive at optimum conditions. Operating the reactor in vapor-phase mode dramatically reduced the amount of undesired by-product formation, and thereby increased the overall yield of acetol and propylene glycol. The optimum reaction temperature is near 2208C. Higher hydrogen feed rates increased propylene glycol selectivity. The proposed production scheme has application for production of both acetol and propylene glycol from the crude glycerol that contains various soluble salts.

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