关键词:

超临界水氧化反应（SCWO）, 乙醇, 废水, 动力学, 反应机理

Abstract: Supercritical water oxidation(SCWO) of ethanol was performed in an isothermal, plug-flow reactor at temperatures from 475 to 550℃, pressures from 22 to 30 MPa, reactor residence times from 0.6 to 63.7s, and oxygen/ethanol molar feed ratios from 4.56 to 9.09.The experimental results showed that carbon monoxide and carbon dioxide were the major intermediate and the final product respectively.The ethanol conversion increased with increasing residence time and temperature and did not obviously change with varying pressure or oxygen concentration.The global kinetics for ethanol disappearance was described by a rate law that was first order in ethanol and zero order in oxygen, and the deviation between calculated and experimental results was approximately within 10%.Furthermore, SCWO processes of ethanol with different oxidant——oxygen and hydrogen peroxide were studied and compared.The same behaviors were observed under supercritical conditions, while under subcritical condition the oxidative rate with hydrogen peroxide was faster than that with oxygen.Based on the observed phenomena, a new viewpoint on SCWO reaction mechanism was proposed that under supercritical condition with oxidant of either hydrogen peroxide or oxygen, a very fast equilibrium distribution between these oxidants would be reached through a series of free radical reaction regardless of their initial concentrations, and the oxidation was proceeded under the condition of equilibrium distribution of oxidants.

Key words:

超临界水氧化反应（SCWO）, 乙醇, 废水, 动力学, 反应机理