A comprehensive study of methyl decanoate pyrolysis

Abstract

The thermal decomposition of methyl decanoate (MD) was studied in a bench-scale pyrolysis set-up equipped with a dedicated on-line analysis section including a GC×GC-FID/(TOF-MS). This analysis section enables quantitative and qualitative on-line analyses of the entire reactor effluent with high level of detail including measurement of formaldehyde and water. The reactor temperature was varied from 873K to 1123K at a fixed pressure of 1.7bar and a fixed residence time of 0.5s, for both high (10molN2/molMD) and low (0.6molN2/molMD) nitrogen dilution. Thus covering a wide conversion range in both dilution regimes. In these experiments, significant amounts of large linear olefins and unsaturated esters were observed at lower temperatures, the amounts of which decreased at higher temperatures in favor of permanent gasses (CO, CO2, CH4) and light olefins. At the highest temperatures more than 5wt% of mono-aromatic and poly-aromatic components were observed. The acquired dataset was used to validate 3 recently published microkinetic models which were developed to model oxidation and/or pyrolysis of methyl decanoate. The results showed that these models accurately predict the product distribution, although important discrepancies were observed for some major products such as certain unsaturated esters, CO2 and H2O. Reaction path analyses and CBS-QB3 quantum-chemical calculations are presented and discussed in order to explain the observed differences.