Calcium carbonate catalyzed alcoholysis of fats and oils

Abstract

Several alcoholysis catalysts, known to be effective for reactions between simple alcohols and soybean oil, were evaluated and found to be ineffective toward alcoholysis of ethylene glycol with soybean oil under traditional reaction conditions. An initial survey of alternative catalysts revealed that organometallic tin complexes were effective but unsatisfactory due to toxicity and difficulty in recovering the catalyst. Satisfactory performance for several alcoholysis reactions was achieved with calcium carbonate catalysts even though at higher temperatures, typically greater than 200°C. Higher reaction temperatures are not considered to be a problem for flow reactors where heat exchangers can be readily used to minimize energy costs. Free fatty acids were esterified by the calcium carbonate and did not appear to inhibit the catalyst. Reaction times of 18 min provided essentially complete conversion. No decrease in the activity of calcium carbonate was observed after weeks of utilization. The robust structure is suitable for use in packed‐bed reactors. The catalyst used for the flow reactors was pulverized limestone. Limestone from two locations was tested and found to be effective. Catalyst removal requires only a screening process at the reactor discharge.