PCBs的超(亚)临界水催化氧化及还原裂解

PCBs Treatment by Sub-Supercritical Water Catalytic Oxidation,Thermolysis and Reduction

简要分析了多氯联苯(PCBs)的来源及其对环境构成的危害,介绍了PCBs在超(亚)临界水中的反应及其处理效果。分别从超临界水氧化、超临界水裂解及亚临界水还原3个方面阐明了超临界反应过程中PCBs降解的反应路径和降解效率,解释了共溶剂(甲醇、苯)、碱催化剂(Na2CO3、NaOH)、氧化剂(NaNO3、NaNO2)等对PCBs脱氯和分解的增效作用机理。发现在超临界水氧化与超临界水裂解条件下CH3OH对PCBs降解反应的促进机制有所不同,碱催化剂通过中和反应过程中产生的HCl生成NaCl沉淀导致体系中Cl的含量降低,从而促进脱氯反应的进行。对反应器防腐处理的经济性方面略作讨论,在总结上述研究工作的基础上提出了PCBs的超临界反应处理技术的若干研究方向。

The major sources and environmental hazards of PCBs are briefly introduced. The reaction pathways and decomposition efficiencies of PCBs in supercritical water （SCW） are reviewed in terms of supercritical water oxidation （SCWO）, supercritical water thermolysis （SCWT）, and subcritical water reduction （SCWR）. The mechanisms of decomposition and dechlorination of PCBs on account of the action of cosolvent with methanol or benzene, alkali catalyst with sodium carbonate or sodium hydroxide and oxidant with sodium nitrate and sodium nitrite are summarized. The diffirences about the promotion mechanism of methanol to PCBs decomposition are found between SCWO and SCWT. The dechlorination reaction is accelerated due to the decrease of HCl which produce in the dechlorination process by the neutralisation of HCl with alkali catalyst. The corrosion problem of reactor and cost-effectiveness during the process of SCWO PCBs are discussed. The research trends for the future in SCWO PCBs are proposed.