Partial oxidative gasification of phenol for hydrogen in supercritical water

The paper reports partial oxidative gasification of phenol for hydrogen in supercritical water (SCW) at lower temperature (<753 K), at which cleavages of aromatic ring occur difficultly and tend to undesirable polymerization. The results showed that O2 is effective to gasification of phenol in SCW. ∼76% of phenol was gasified and 2.7 mol/mol of hydrogen was produced within 180 s with Na2CO3 as catalyst at the selected process conditions, a molar ratio of oxygen-to-phenol, 7.5–1, 723 K, and 24 MPa. It was found that unstable opening-rings products oxalic and maleic acid and stable dimmerization compounds in liquid water were formed during partial oxidation process. The process also indicated phenol was rapidly converted, and some opening-rings products were slowly gasified, which also confirmed oxygen served as effective reactant for ring-opening. Based on the given reaction conditions, a treatment process using a real wastewater from coking industry was performed. The data showed that the present technology provides an effective way to gasification of phenol wastewater for high-value energy utilization.