doi:10.3850/978-981-08-7724-8_09-04

ABSTRACT

This paper investigates the effect of cerium(III) in catalysing the oxidative degradation of linseed oil, used as a drying oil in alkyd paint formulations. The addition of metallic salts enhances the drying rate of alkyd paint, but may also induce self-heating and autoignition, when linseed oil with metallic salts is applied to a cotton fabric. We measured the formation of gaseous products, such as CO₂, CO, C₂H₆, C₂H₄, H₂O and CH₃CHO from the oxidation of linseed oil in the presence of Ce(III) and compared the emissions induced by cobalt(II), which we established in a previous study to greatly enhance the oxidation of linseed oil. The experiments were performed in a copper, plug flow reactor housed inside a Thermoline oven operated at a temperature of either 80 or 100 °C. We impregnated the glass wool or cotton wool substrate with a salt solution, then dried it under flowing nitrogen at 40 °C. Oil samples weighing around 0.2 g each were placed on the wool substrate. Equimolar oxygen and nitrogen mixtures flowed for several hours in each experiment. Evolution of gaseous products during the reaction was quantified by micro gas chromatography (μGC) and Fourier transform infrared spectroscopy (FTIR). In addition, both FTIR and gas chromatography-mass spectrometry (GC-MS) were employed to identify the minor products. Cerium(III) nitrate, compared to cobalt(II) nitrate, yields similar emissions of CO₂, CO and CH₃CHO. Higher amounts of ethane and ethylene emitted during oxidation of linseed oil in the presence of cerium nitrate could be due to smaller emissions of nitrous oxide which decomposes those product gases.

Keywords: Linseed oil, Oxidation, Cerium, Cobalt.

© 2011 CPD Unit, University of Leeds