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Bioenergy and emission characterizations of catalytic combustion and pyrolysis of litchi peels via TG-FTIR-MS and Py-GC/MS

Liu, Chao, Liu, Jingyong, Evrendilek, Fatih, Xie, Wuming, Kuo, Jiahong, Buyukada, Musa
Renewable energy 2020 v.148 pp. 1074-1093
Litchi, activation energy, aluminum oxide, bioenergy, byproducts, carbon dioxide, carbon monoxide, catalysts, catalytic activity, combustion, emissions, fatty acids, gases, magnesium carbonate, methane, nitrogen oxides, phenols, potassium carbonate, pyrolysis, sodium carbonate, steroids, sulfur oxides, terpenoids, wastes
This study characterized the catalytic combustions and emissions of litchi peels as a function of five catalysts as well as the effect of the best catalyst on the pyrolysis by-products. Na₂CO₃ and K₂CO₃ accelerated the devolatilization but delayed the coke burnout, while Al₂O₃ enhanced the coke oxidation rate. Both comprehensive combustion index and average activation energy dropped with the added catalysts. CO₂, CO, and H₂O were the main combustion gases between 300 and 510 °C. CO₂, C-H, C=O, and C-O were generated from the pyrolysis between 200 and 430 °C above which CO₂ and CH₄ were slightly released. Total H₂O, CO₂, CO, NOₓ and SOₓ emissions declined with the added catalysts among which K₂CO₃ performed better. The main pyrolytic by-products at 330 °C were terpenoids and steroids (71.87%), phenols (15.51%), aliphates (9.95%), and small molecules (2.78%). At 500 °C, terpenoids and steroids (78.35%), and small molecules (3.20%) rose, whereas phenols (12.87%), and aliphates (5.83%) fell. Fatty acid, and ester decreased, while terpenoids, and steroids increased with MgCO₃ at 330 °C. Litchi peels appeared to be a promising biowaste, with MgCO₃ as the optimal catalytic option in terms of the bioenergy performance, and emission reduction.