PYROLYSIS of glycerol with modified vermiculite catalysts

Abstract

Sodium and activated vermiculites were applied as catalysts in the pyrolysis of glycerol. The physical–chemical characterization showed that acid treatment significantly modified the chemical composition, specific area, porosity and structure of sodium vermiculite. Thermogravimetric analysis of the pyrolysis process showed that the presence of catalysts reduced the degradation temperature of glycerol. Kinetic study by the Ozawa–Flynn–Wall model indicated a reduction in the activation energy (Ea) of the process with the use of the catalysts: thermal pyrolysis, Ea = 106.7 kJ mol−1; thermocatalytic pyrolysis with sodium vermiculite, Ea = 90.7 kJ mol−1; and with activated vermiculite, Ea = 85.2 kJ mol−1. Pyrolysis via a pyrolyzer coupled to gas chromatography/mass spectrometry (Py-GC/MS) showed that activated vermiculite provided higher deoxygenation. Thus, the use of activated vermiculite in thermocatalytic pyrolysis is a good option for the transformation of glycerol, because it decreases the activation energy of the process and increases the selectivity for a range of industrially valued products, such as acetaldehyde, acrolein, acetol, glycidol, propylene glycol and 2-propanol.