Influence of salts during hydrothermal biomass gasification: The role of the catalysed water-gas shift reaction

Near-critical and supercritical water is an unusual reaction medium with extraordinary properties, varying with temperature and density. This opens the opportunity for new reactions and new technical processes. In the studies of synthesis reactions, total oxidation and biomass gasification interesting effects of salts are observed. These effects are assumed to be caused by complex formation, acidity/basicity or the presence of active hydrogen due to the water-gas shift reaction. The water-gas shift reaction is catalysed by salts and lead to the formation of hydrogen, which might react with other compounds. This article focuses on the salt effects during hydrogen production by biomass gasification in supercritical water. This is a very interesting process to make use of "wet biomass", which is up to now not applied in a technical process. Here salts influenced the main reactions pathways. Possible reasons are discussed.