Fundamental researches on the novel process for laboratory waste treatment by supercritical water oxidation

该项目的目的是获得实验室废物处理过程中超临界水氧化（SCWO）的基本工程信息。本项目的外展活动总结如下。(1)作为卤化有机化合物的模式化合物，2-氯酚（2-CP）的降解，采用连续热解与氧化相结合的方法可有效获得2-CP的高转化率，避免不良副产物的形成。在氯苯甲酸的分解过程中，脱氯产物具有很高的选择性，特别是在较低温度下。还发现Na和K等碱种的加入促进了2-CP的脱氯。(2)在超临界水中，乙酸、苯酚和甲烷等难降解化合物与醇共氧化时，实验表明醇的存在提高了共存难降解化合物的消失率。基于详细的化学动力学模型的计算结果表明，这些混合物在SCWO中的动力学效应很好地表征了OH自由基的浓度。(3)考察了金属氧化物、活性炭等多相催化剂对苯酚的催化氧化作用。非负载型MnO催化剂具有较强的促进苯酚氧化活性，但总体反应速率受内部传质阻力的影响较大。通过动力学分析，确定了表面反应的全局速率表达式，并提出了解释苯酚、氧和水的反应顺序的langmuir型机理。实验还证明了用廉价的碳催化剂可以有效地氧化苯酚。

The objective of this project was to obtain the fundamental engineering information on the lab-waste treatment process by supercritical water oxidation (SCWO). The outreaches of this project are summarized as follows.(1)For the degradation of 2-chrolophenol (2-CP), chosen as a model compound of halogenated organic compounds, a consecutive combination of pyrolysis with oxidation was suggested to be effective to obtain high conversion of 2-CP and to avoid the formation of undesired by-products. In the decomposition of chrolobenzoic acid, very high selectivities for dechrolinated products can be achieved, particularly at lower temperatures. It was also found that addition of such alkali species as Na and K promotes dechlorination of 2-CP.(2)In the co-oxidation of such refractory compounds as acetic acid, phenol and methane with alcohol in supercritical water, it was experimentally suggested that the presence of alcohols enhanced the disappearance rate of the co-existing refractory compounds. The calculated results based on detailed chemical kinetics model suggest that the kinetic effect of such mixtures in SCWO is well characterized by the concentration of OH radical.(3)The catalytic oxidation of phenol in the presence of such heterogeneous catalyst as metal oxide or activated carbon was examined. A non-supported MnO, catalyst possessed a strong activity for promoting phenol oxidation, though the overall reaction rate was appreciably influenced by internal mass transfer resistance. From the kinetic analyses, the global rate expression of the surface reaction was determined, and a Langmuir-type mechanism was proposed to explain the reaction orders for phenol, oxygen and water. It was also experimentally demonstrated that phenol can be effectively oxidized with inexpensive carbon catalysts.