Analytical and Applied Copyrolysis of <i>Mesua ferrea</i> L. and Polyethyelene Terephthalate Plastic for Hydrocarbon-Rich Bio-oil

The current investigation focuses on the copyrolysis of <i>Mesua ferrea</i> L. (a nonedible oilseed, also known as Nahar) and polyethyelene terephthalate (PET) plastic waste to gain insights into the composition of pyrolysates and the thermal decomposition of complex and mixed feedstocks. The physicochemical properties of the feedstocks were studied through thermogravimetric analysis at a heating rate of 15 °C min^-1, bomb calorimetry, and proximate/ultimate analysis. The proximate analysis revealed that both biomass and PET had relatively low moisture contents (3.33 and 0.61%, respectively) and high volatile matter (88% for biomass and 94.53% for PET). The pyrolysate composition studies using analytical pyrolysis coupled with a gas chromatograph/mass spectrometer revealed significant generation of fatty acids (∼79%) from Nahar and benzoic acid (24%) and acetylbenzoic acid (15.5%) from PET at 590 °C. The analytical pyrolysis of feedstock mixtures at biomass:PET (B:P) of 1:1, 2:1, and 1:2 w/w revealed the dominance of both aliphatic and carboxylic acids. Further, fixed-bed copyrolysis experiments were performed using Nahar, PET, and its mixtures in a temperature range of 550-650 °C at 15 °C min^-1 heating rate. The optimal temperature of 600 °C was chosen for both biomass and copyrolysis (2:1 feed ratio) due to the high yield of pyrolytic liquid (27 wt % for biomass alone; 35 wt % for copyrolysis). The produced bio-oil was thoroughly characterized, and it was found that fatty acids and carboxylic acids such as <i>n</i>-hexadecanoic acid, octadecenoic acid, octadecanoic acid, and benzoic acid were found in a significant proportion. The mechanism of copyrolysis vapors was studied by analyzing the pyrolysates obtained at different operating conditions. Decarboxylation and decarbonylation fatty acid species were found to be typical pathways for the formation of hydrocrabons like hexadecane, pentadecane, heptadecane, and heptadecene.