Microwave-assisted preparation of a new esterification catalyst from wasted flint kaolin

作者：de Oliveira Alex de Nazare; da Silva Costa Laura Rafaela; de Oliveira Pires Luiza Helena; do Nascimento Luis Adriano S; Angelica Romulo S; da Costa Carlos E F; Zamian Jose R; da Rocha Filho Geraldo N^*

来源：Fuel, 2013, 103: 626-631.

DOI：10.1016/j.fuel.2012.07.017

• Flint metakaolin
• Microwaves
• Acid catalysis
• Esterification
• Biodiesel

Amazon flint kaolin, considered useless from an economic and industrial point of view, was calcined at 850 and 950 degrees C to obtain metakaolin samples. These samples were subsequently treated with sulfuric acid (4 M) by assisted heating with microwave radiation. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy and N-2 physisorption; the surface acidity was determined by titration with 0.2 M KOH. The materials obtained were used as catalysts in the esterification of oleic acid with methanol. Metakaolin that was calcined at 850 degrees C and activated at 400 W for 15 min presented a surface area of 187 m(2) g(-1), yielding acidic sites with a concentration of 4.32 mmol g(-1) and a conversion of 96.5% (115 degrees C, 40 min, molar ratio of oleic acid: methanol 1: 60). In addition to a lower preparation time, the flint metakaolin activated by microwave radiation gave a catalytic performance equivalent or superior to the one prepared by reflux, as well as it showed considerably reduced reaction time and temperature.

• 出版日期2013-1