Catalytic gasification of food waste in supercritical water over La promoted Ni/Al2O3 catalysts for enhancing H2 production

Ni/Al2O3 catalyst is the one of promising catalysts for enhancing H-2 production from supercritical water gasification (SCWG) of biomass. However, due to carbon deposition, the deactivation of Ni/Al2O3 catalyst is still a serious issue. In this work, the effects of lanthanum (La) as promoter on the properties and catalytic performance of Ni/Al2O3 in SCWG of food waste were investigated. La promoted Ni/Al2O3 catalysts with different La loading content (3-15 wt%) were prepared via impregnation method. The catalysts were characterized using XRD, SEM, BET techniques. The SCWG experiments were carried out in a Hastelloy batch reactor in the operating temperature range of 420-480 degrees C, and evaluated based on H-2 production. The stability of the catalysts was assessed by the amount of carbon deposition on catalyst surface and their catalytic activity after reuse cycles. The results showed that 9 wt% La promoter is the optimal loading as NV9La Al2O3 catalyst performed best performance with the highest H-2 yield of 8.03 mol/kg, and H-2 mole fraction of 42.46% at 480 degrees C. La promoted Ni/Al2O3 catalysts have better anti-carbon deposition properties than bare Ni/Al2O3 catalyst, resulting in better gasification efficiency after reuse cycles. Ni/9La Al2O3 catalyst showed high catalytic activity in SCWG of food waste and had good stability as it was still active for enhancing H-2 production when used in SCWG for the third time, which indicated that La promoted Ni/Al2O3 catalysts are potential additive to improve the SCWG of food waste. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.