【作者】 葛红光；

【导师】 张志杰； 陈开勋；

【作者基本信息】 西安建筑科技大学 ， 环境工程， 2004， 博士

【摘要】 超临界水氧化法是一种新兴的有机废水处理技术。在水的临界点（T_c=374℃、P_c=22.1MPa）以上，水的密度值、介电常数、离子积会下降，氢键会减少，以至于水成为一种具有高扩散性和优良传递特性的非极性介质。此时甚至非极性的有机物和气体如氧气能和水以任意比例互溶，形成单一的均相体系。基于超临界水的特性而产生的超临界水氧化技术具有很多优越性，由于没有相间传质阻力，氧化反应速度非常快，一般只需几秒至几分钟即可将废水中的有机物彻底氧化分解。 本论文在一套连续流超临界水氧化实验装置中，以含氮有机物偏二甲肼和对氨基苯酚为研究对象，进行了非催化、均相催化和非均相催化超临界水氧化实验。研究了这两种含氮有机物在超临界水中的分解氧化效率及其影响因素。 研究结果表明偏二甲肼和对氨基苯酚在超临界水中有很好的氧化去除效果，在反应温度430～550℃、反应压力24～38MPa和H₂O₂过量的实验条件下，数秒钟内COD去除率可高达99％。采用气相色谱分析研究了反应后的气相产物，结果表明氧化产物是CO₂、N₂和过量的O₂。提高反应温度、反应压力、延长停留时间和增加氧化剂用量，均能提高有机物的分解氧化程度，使COD去除率增大。反应温度、压力和停留时间是影响有机物COD去除率的主要因素，在保证氧化剂过量的情况下氧化剂用量对超临界水氧化反应的影响较小。 传统的超临界水氧化通常在大约25MPa和550℃以上的高温下依赖于均相和自由基反应将有机碳转化为CO₂，为了降低苛刻的工艺条件和尽可能减少处理费用，进行了催化超临界水氧化实验研究。结果表明，使用合适的催化剂可以降低超临界水氧化反应的温度和压力、缩短停留时间，在相同的实验条件下能使高浓度含氮有机污染物的COD去除率相比于传统的超临界水氧化法有明显的提高。在均相催化超临界水氧化中，Cu²⁺的催化效果较好，而在非均相催化超临界水氧化反应中催化剂CuO／γ-Al₂O₃的催化效果比催化剂MnO₂／K-Al₂O₃更显著。采用X射线衍射（XRD）和X射线光电子能谱（XPS）技术对使用前后的两种催化剂CuO／γ-Al₂O₃和MnO₂／γ-Al₂O₃的物相和组成进行了表征，结果表明，催化剂CuO／γ-Al₂O₃和MnO₂／γ-Al₂O₃在使用过程中，载体Al₂O₃的晶型发生转变、由γ-Al₂O₃大部分转变为了α-Al₂O₃，晶粒增大、西安建筑科技大学博士学位论文表面积有所减小。在超临界水氧化偏二甲麟和对氨基苯酚时这两种催化剂都出现了不同程度的溶解流失现象，催化活性有一定的降低。在超临界水中CuO的催化活性优于Mnq，但N山q比CuO稳定。 根据超临界水氧化偏二甲脐和对氨基苯酚的液相产物的GC一MS检测研究和对气相产物的气相色谱（oc）分析结果，由此提出并解释了这两种含氮有机物在超临界水中分解氧化的反应路径和反应机理。自由基反应是以上两种物质SCWO反应的共同特征，链引发主要由自由基.oH完成。在经历了一系列复杂的反应后，最终产物为从、C众和氏0。 论文对偏二甲脐和对氨基苯酚在超临界水氧化中的COD去除动力学进行了研究，其宏观动力学方程及动力学参数为: d[c oDIr=一--‘二一二=诬。xp(--Eo/天T犷卯}”’[O2』” 偏二甲脐:Eo为科.65u·mol一，（无催化剂）、35.75u·mol”（euo催化剂）、37.79u·mol一， （Mhq催化剂）。有机物反应级数为1 .13级（无催化剂）、1.11级（CuO催化剂）、1.26级（N恤02催化剂）。氧气反应级数为0.29级（无催化剂）、0.10级（Cuo催化剂）、1 .12级（N山O2催化剂）。 对氨基苯酚:Eo为60.04u·mol”（无催化剂）、37.7ou·mol.，（euo催化剂）、51.47u·mol一， （Mnq催化剂）。有机物反应级数为1 .41级（无催化剂）、0.92级（Cuo催化剂）、0.95级（N[n 02催化剂）。氧气反应级数为0.23级（无催化剂）、0.12级（CuO催化剂）、0.21级（Mnq催化剂）。 有机物的反应级数接近1，氧气的反应级数小于l而接近0，偏二甲脐比对氨基苯酚具有更低的反应活化能，催化剂的引入使偏二甲麟和对氨基苯酚的化学反应活化能均有较大程度的降低。 论文对超临界水氧化技术的应用前景及若干工程化问题进行了探讨，选择合适的催化剂，可以降低操作费用，提高处理效率。通过选择和分离原料或针对不同的原料在反应器的不同部位应用不同的金属材料制作，可使腐蚀降到最低的程度。设计特殊的反应器以及工艺系统的优化设计，可有效防止析出的盐在器壁上沉积。更多还原

【Abstract】 Supercritical water oxidation (SCWO) was a promising technology for treatment organic-containing wastewater. When exceeding critical point of water (Tc = 374℃; Pc = 22.1MPa), the values of density, dielectric constant, hydrogenous bond and ionic product of water drop down, so supercritical water acts as a non-polar solvent of high diffusivity and excellent transport properties. Consequently, even non-polar organic compounds and gases like oxygen become completely miscible with the supercritical fluid. The SCWO process that is based on the special physical properties of supercritical water has a great many of advantages. The oxidation reactions to occur rapidly without any interphase mass transport limitations. The organic compounds in wastewater were completely oxidized in several seconds to several minutes.The non-catalytic SCWO, homogeneous and inhomogeneous catalyzed SCWO of unsymmetrical dimethyl-hydrazine (UDMH) and para-aminophenol were performed in a continuous flow reactor. The oxidation efficiency and influence factor of this two kinds of organic compound contain nitrogen in supercritical water were investigated.The results indicate that UDMH and para-aminophenol were easily oxidized in supercritical water. 99% COD removal was obtained in several seconds at 430~550℃, 24~38MPa with H2O2 in excess. Gas products were analyzed with Gas Chromatogram (GC). The results indicate that gas products were CO2 N2 and excess O2. The COD elimination efficiency was significantly improved as reaction temperature, pressure, residence time or oxidant dosage was increased. The main influential factors of COD elimination efficiency were temperature, pressure and residence time. Oxidant dosage had little influence on SCWO under conditions of oxidant excess.Conventional SCWO processes, which usually operate around 25MPa and up to 550℃, rely on homogeneous, free-radical reactions to convert organic carbon to CO2, The catalytic supercritical water oxidation (CSCWO) was performed to reduce the severity of the processing conditions and possibly toreduce the processing cost. The results indicate that reaction temperature, pressure and residence time caught be reduced by using appropriate catalysts. The higher COD elimination efficiency was obtained by using CSCWO than conventional SCWO in the same experiment condition. The Cu2+ was a better catalyst in homogeneous catalyzed oxidation. CuO/ γ-Al2O3 catalysts exhibited higher activity than MnO2/γ-Al2O3 catalysts in heterogeneous catalyzed oxidation. The structure and composition of the fresh and used CuO/ γ - A12O3 and MnO2/ γ -Al2O3 catalysts were identified by X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) . The XRD and XPS results suggest that the γ-Al2O3 support in the fresh catalyst was largely transformed to Al2O3 during SCWO processes. The BET surface areas for two catalysts decreased after some day of continuous use. The supported CuO and MnO2 catalysts and Al2O3 support were dissolved during SCWO processes of UDMH and para-aminophenol, so activity of catalyst reduced. The CuO/ γ-Al2O3 catalyst exhibited higher activity than MnO2/ γ-Al2O3 catalyst in supercritical water, but CuO/ γ-Al2O3 catalyst offered lower stability than MnO2/ γ-Al2O3 catalyst under SCWO conditions.The liquid products and gas products of SCWO of UDMH and para-aminophenol were analyzed and identified systematically by GC-MS and GC, respective. The reaction path and mechanism of this two organic compounds contained nitrogen in SCWO processes were obtained. Free radical reactions were the same characters of SCWO for the two substances above. Free radicals -OH began the reactions. The final products were N2, CO2 and H2O after a series of complicated reactions.The kinetics of oxidative degradation of UDMH and para-aminophenol in SCW were investigated systematically. The global power-law rate equation and parameters as follows:UDMH: Ea is 44.65 kJmol-1 (without catalyst), 35.75 kJ-mol-1 CuO catalyst), 37.79 kJ mol-1 MnO2 catalyst). The reaction order of o更多还原