Production of Bio-Oil from Thermo-Catalytic Decomposition of Pomegranate Peels over a Sulfonated Tea Waste Heterogeneous Catalyst: A Kinetic Investigation

Abstract

In this study, the pyrolysis procedure was used to extract oil from pomegranate peels (PP) utilizing biomass-derived sulfonated tea waste as a catalyst. FTIR, SAA, SEM, and XRD were used to characterize the catalyst. Thermo-catalytic decomposition was carried out in a salt bath reactor and the bio-oil composition was determined through GC-MS. The oil obtained from virgin PP was observed to contain compounds in the range of C5–C13, whereas from the catalyzed reaction it was found to be rich in C5–C23. For the calculation of kinetic parameters, TG analysis was performed of virgin PP and with the catalyst at different heating rates. TG/DTG indicated weight loss in four steps. The first weight loss below 100 °C is due to the physically adsorbed water molecule evaporation. The second weight loss is attributed to hemicellulose decomposition and the third one to cellulose degradation. The fourth weight loss is due to lignin degradation. Kissinger model was used for measuring the activation energy (Ea) of the decomposition reaction. The activation energy of hemicellulose, cellulose, and lignin for non-catalytic reactions was observed as 199, 249, and 299 kJmol−1, while in the case of the loaded tea waste catalyst, the Ea was reduced to 122, 163, and 207 kJmol−1, respectively, confirming the effectiveness of the catalyst. From these findings, it can be concluded that sulfonated tea waste catalyst has not only lowered the pyrolysis temperature and Ea but also brought a change in oil quality by enhancing value-added compounds in the bio-oil.