Esterification of rosin with methyl alcohol for fuel applications

Abstract

Oleoresin is obtained via tapping of pine trees and as a by-product of Kraft process in the pulp industry. Because of its low production cost, it is an attractive source for biofuels. Oleoresin is composed mainly of rosin (around 80%, a solid mixture of isomeric abietic acids), and it cannot be used directly as fuel in engines. However, the methyl ester of rosin has lower boiling and melting points than rosin, and it is highly soluble in hydrocarbons. Esterification of rosin with methyl alcohol was evaluated over acid and basic heterogeneous catalysts in the presence of several solvents. In contrast to acid catalysts, basic materials were active in the reaction. In particular, a low-cost calcium-based material showed the best performance. A 55% conversión of rosin with complete selectivity to methyl esters was obtained with 40% wt. Loading of the calcium-based material (respect to rosin), under mild conditions (atmospheric pressure, 64 °C and 3.5 h) and without solvent. Other catalysts, such as magnesium oxide, titanium dioxide, and alumina, achieved up to 30% conversion. Calcium carbonate and calcium hydroxide were the main phases in the calcium-based material, suggesting that the strength of basic sites can be an important property of the catalyst activity. A calcium-based material was used in five reaction cycles, obtaining a significant reduction in the activity attributed to the leaching of some phases of the catalyst.

Keywords

• hydrocarbons
• acidity
• chromatographic analysis
• materials science
• calcium