Catalytic decomposition of tar derived from biomass pyrolysis using Ni-loaded chicken dropping catalysts

The Ni-loaded chicken droppings (Ni/CD) and chicken dropping ash (Ni/CDA) were prepared by the impregnation method and applied as catalysts for biomass tar decomposition at low temperature (450 °C) under N₂ and steam/N₂ conditions. The prepared samples and the supports were characterized by N₂ adsorption measurements, X-ray diffraction, H₂ temperature-programmed reduction, and X-ray photoelectron spectroscopy. The results reveal that Ni/CD and Ni/CDA showed higher catalytic activity for tar decomposition, in terms of producing hydrogen-rich gas, relative to commercial Ni/Al₂O₃ under N₂ conditions. This higher activity was caused by lower interactions of Ni with the support and the presence of additional reduced Ni. In the case of steam reforming, Ni/CDA also showed higher hydrogen yield and a lower amount of carbon deposition than Ni/Al₂O₃. This result indicates that a hydrophilic hydroxyapatite in the CDA support promoted the water–gas shift reaction to suppress carbon deposition and increase hydrogen yield.