CHEMICAL IMPROVEMENT OF FATTY-ACID METHYL -ESTERS - STUDIES OF METHYLSTEARATE PYROLYSIS

The pyrolysis of a rapeseed oil methyl esters cut, enriched in methyl stearate, has been studied in a tubular reactor between 600 and 850 de grees C, in dilution with nitrogen or wafer. The residence lime was 32 0 ms and the dilution rate ranged from 6 to 28 moles of diluent/mole o f ester. A specific device for the condensation of cracking effluents was used for the fractionated recovery of liquid and gaseous effluents , which were analyzed online by an infrared spectrography and by gas c hromatography. The cracking products in the liquid effluent were ident ified by GC/MS analysis. The effects of temperature, diluent and dilut ion rate on the cracking reaction were studied. The principal products observed were linear 1-olefins, n-paraffins from C-1 to C-18 and unsa turated methyl esters from C-3:1 to C-16:1. The gas fraction also cont ained CO, CO2 and H-2. The best yields of C-10-C-14 olefins and C-6:1 to C-12:1 unsaturated esters, products with a high added value, while minimizing the formation of light products, are obtained or about 700 degrees C, with water as diluent (molar ratio 13/1).