The roles of water, air and reactor walls will be discussed in the context of hydrothermal upgrading of (waste) biomass and polymers.
Our recent research expands upon what is know about the interactions between the reaction components, especially water under supercritical conditions.
Using 1-dodecene as a model compound and reacted under either pyrolysis or supercritical water conditions with an atmosphere of air or argon inside the reactor, the underlying chemistry will be discussed and mechanistic aspects discussed.
Despite reactions being conducted in water, alkene hydration does not appear to be important for double bond isomerisation.
Additionally, we investigated the supercritical water conversion of limonene and isoprene from waste tyres.
Limonene, itself a major product formed during tyre pyrolysis, appears to aromatise to form p-cymene in the hydrothermal reactor.
The observed formation of single ring aromatics from depolymerised isoprene and limonene in particular, are compared between pyrolytic and hydrothermal reaction conditions. More than one aromatisation pathway is possible depending on the reaction medium and the presence of a catalytic surface.
Initial data suggests surface acidity appears to have a major influence on the reaction cascade.