Catalytic Gasification of Mandarin Waste Residue using Ni/CeO2-ZrO2

Catalytic gasification of mandarin waste residue was carried out using direct and indirect catalyst-contact methods for the first time. In the indirect method, non-catalytic reaction in a reactor was followed by catalytic upgrading of vapor product in another reactor. Two different catalysts, Ni/gamma-Al2O3 and Ni/CeO2-ZrO2, were employed. CeO2-ZrO2 support was prepared using hydrothermal synthesis in supercritical water. The catalysts were characterized by H-2-temperature programmed reduction and Brunauer-Emmett-Teller analyses. Under the condition of equivalent ratio (ER) = 0, the indirect catalyst-contact method led to a higher gas yield than the direct method. Under ER = 0.2, the yield of biogas obtained over Ni/CeO2-ZrO2 was higher than that obtained over Ni/gamma-Al2O3. Also, the coke formation of Ni/CeO2-ZrO2 was lower than that of Ni/gamma-Al2O3. Such results were attributed to the higher reducibility and better lattice oxygen mobility of Ni/CeO2-ZrO2, which were advantageous for partial oxidation reaction.