Influence of Phenolic Compounds in Obtaining Aromatic Hydrocarbons During the Thermal and Catalytic Co-pyrolysis of Peanut Shells and Plastic Waste

Abstract

During the co-pyrolysis of agro-industrial and plastic waste, phenolic compounds (Phe-OH) undergo hydrogenation and dehydration reactions that lead to the formation of aromatic hydrocarbons. In order to demonstrate this, peanut shell pyrolysis reactions were carried out with polyethylene. Peanut shells have a high percentage of lignin, the main source of phenols. Two conditions were analyzed to study the reaction mechanism. On the one hand, the behavior of Phe-OH in the presence of polyethylene (PE) was studied to know the influence of hydrogen atoms on the reaction medium. In this sense, it was observed that the addition of hydrogen-rich chains generated an increase in the yield to aromatic hydrocarbons (AHC). The results obtained allow us to suggest that phenolic compounds act as a strong hydrogen acceptor when deoxygenated. On the other hand, the improvement in aromatic hydrocarbon formation was studied with the use of a zeolitic catalyst. In this case, the best yields to the aromatic compounds of interest were obtained. This was due to the presence of Brönsted acid sites in the catalyst that provide the route for obtaining these aromatic rings. It was concluded that both reaction routes contributed to obtaining 33 wt% of selectivity to benzene, toluene and xylene (BTX).