Catalyzed Partial Oxidative Gasification of Phenol in Supercritical Water

Phenol, a substance difficult to be gasified, is often an intermediate product from biomass gasification in supercritical water. In this study, 1 wt % phenol is gasified in supercritical water with different oxidation coefficients (0 <= n <= 0.8) at 430-550 degrees C, 25 MPa in a continuous tubular flow reaction plant with or without 0.1 wt 96 Na2CO3. The results show that TOC (total organic carbon) removal rate and COD (chemical oxygen demand) removal rate of reactor effluent will rise with the increase of oxidation coefficient and reaction temperature. When n rises from 0.3 to 0.8 at 500 degrees C, hydrogen yield and hydrogen molar fraction will first increase and then decrease. They reach their respective maximum values of 0.245 mol/mol and 46.2% at n = 0.6 with the residence time of 2.96 min. There is an appropriate oxidation coefficient for obtaining the highest hydrogen yield for phenol supercritical water partial oxidative gasification (SWPO). Na2CO3 can serve as a catalyst or an additive for phenol SWPO. When 0.1 wt % Na2CO3 is added, hydrogen yield is near 0.477 mol/mol at n = 0.6, 500 degrees C with the residence time of 2.96 min. Furthermore, the potential conversion pathways for phenol SWPO with Na2CO3 catalyst are also proposed.