Gasification of Organosolv-lignin Over Charcoal Supported Noble Metal Salt Catalysts in Supercritical Water

Charcoal supported metal salt catalysts showed activities for the lignin gasification at 673 K, especially the catalysts without chloride anion showed the complete gasification. The order of activity for the gasification among the metal species was following: ruthenium > rhodium > platinum > palladium similar to nickel. X-ray absorption fine structure analysis revealed that small metal particles were formed on the charcoal support after the gasification for the supported ruthenium, rhodium, and platinum salt catalysts without chloride anion; on the other hand, larger metal particles were formed in the presence of chloride anion. Lower activities and deactivation for supported metal salt catalysts having the chloride anion were caused by poisoning by chloride anions and the smaller number of metal sites.