Supercritical water gasification of phenol and glycine as models for plant and protein biomass

We examined the gasification of phenol and glycine in supercritical water (SCW). For phenol SCW gasification, the water density and phenol loading were varied to determine their effects. Increasing the water density at a constant phenol loading lowered the phenol conversion for Ni-catalyzed reactions. Increasing the phenol loading at a fixed water density increased the conversion. The H₂ yields at equilibrium increased with decreasing water density, decreasing phenol loading, and increasing temperature. Glycine was much more resistant to gasification than phenol. Large amounts (20%-90%) of the initial carbon remained in the aqueous phase even after 1 h for both homogeneous and Ni-catalyzed reactions. Solid material was also produced. Of the gases that were formed, CO was most abundant from the homogeneous reactions, while hydrogen was the most abundant in the presence of a nickel catalyst. The Ni catalyst assisted in glycine gasification, as less carbon was found in the aqueous phase, and gas yields were increased.