Experimental study of the auto-catalytic effect of triethylaluminum and TiCl4 residuals at the onset of non-additive polypropylene degradation and their impact on thermo-oxidative degradation and pyrolysis

Abstract

In this article, the pyrolysis and thermo-oxidative degradation of five industrial waste products was carried out in a discontinuous quartz reactor at 550 °C under the auto-catalytic effect of residues of titanium tetrachloride (TiCl4), triethylaluminium (TEAL), and iron (Fe). We using the coupled on-site analysis of an GCMS/FID/PDHID with 7 valves and 8 columns in series. The study also discusses the effect of the concentration of the catalyst residuals with the Eac (activation energy) and the evolution of the profile of permanent oxygenated gases, hydrocarbons and sulfurs, as well as the functional waste groups from decomposition during pyrolysis and thermo-oxidative degradation. The origin of the degradation and the beginnings of PP pyrolysis and thermo-oxidative degradation are explained by hydrolysis mechanisms and thermal reactions that imply successive reactions with these (TEAL), TiO2, and chloride residues, giving rise to ethyl radicals and explaining the formation of alcohols, ketones, carboxylic acids, alkynes and alkenes. The study also found that the gaseous profiles are very consistent with the DTG curves and the Eac, in terms of the appearance of peaks and relevant stages throughout the total temperature range. The effect of Cl, Fe and TEAL on the PP degradation is very high upon passing from an inert to an oxidative atmosphere. This reduces the content of hydrocarbons and oxygenates to CO2 between 49 and 66% because of the attack of the oxygen atom. In the pyrolysis the propylene content oscillates between 42 and 56%. Finally, the initial reaction mechanisms, and the secondary reaction routes, are proposed and demonstrated experimentally in function of the primary volatile compounds quantified. The thermo-oxidative properties of the five PP waste products improve significantly with the addition of 0.1% of a secondary antioxidant.