Transesterification of soybean oil over Me/Al2O3 (Me = Na, Ba, Ca, and K) catalysts and monolith K/Al2O3-cordierite

TONETTO G.; MARCHETTI J.

TOPICS IN CATALYSIS

SPRINGER/PLENUM PUBLISHERS

Año: 2010 vol. 53 p. 755 - 762

1022-5528

Four different Me/Al2O3 (Me = Na, Ba, Ca and K) powder catalysts prepared by incipient-wetness impregnation, and a K/Al2O3-cordierite monolithic catalyst produced by the dipcoating technique were used for biodiesel production. The samples were characterized and studied in the transesterification of soybean oil with methanol at 120°C and 500RPM, with a alcohol/oil molar ratio = 32, and a catalyst load = 1 wt% for the powder catalyst and 0.5wt% for the monolith. The Ca/Al2O3, Na/Al2O3 and K/Al2O3 powder catalysts reported a FAME (fatty acid methyl esters) formation of 94.7%, 97.1% and 98.9% respectively after 6 h of reaction. On the other hand, Ba/Al2O3 showed little activity (7.6%). The leaching of the alkali and alkaline earth metal species during reaction was important, what indicates that the activity could be explained in terms of a homogeneous–heterogeneous catalyst effect.  When the monolithic sample and the powder catalyst were compared (under identical reaction conditions), the production of FAME for the latter was 89.5% and 59.1% for the monolithic catalyst. After two consecutive runs, the monolithic catalyst presented a partial deactivation of 8% in the FAME yield. The present work shows that the use of monolithic catalysts in the transesterification of vegetable oils is a viable alternative.