钙基复合氧化物对五氯酚生成二噁英的阻滞作用

Inhibition of calcium-based composite oxide on PCDD/Fs formation from PCP

以市售的Ca O为阻滞剂,分别添加Mg O、Ce O2、Ba O、γ-Al2O3金属氧化物形成钙基复合氧化物,通过探究它们对前驱体五氯酚(PCP)生成PCDD/Fs反应的阻滞作用,讨论了Mg O、Ce O2、Ba O、γ-Al2O3金属氧化物对Ca O阻滞作用的影响.结果表明,在280℃下加热2 h,钙基复合氧化物对PCP生成PCDD/Fs的阻滞活性都很高.在PCDD/Fs的生成总量上,Ce O2、Ba O、γ-Al2O3金属氧化物对Ca O的阻滞效果起到促进作用;但在ITEQ方面,仅Ba O对Ca O的阻滞效果有促进作用.Ca O与Ba O钙基复合氧化物对PCP生成PCDD/Fs的阻滞效率达到99.98%,总毒性当量阻滞效率TSEI-TEQ达到99.62%.钙基复合氧化物可能的阻滞机理是Ca O、Mg O、Ce O2、Ba O、γ-Al2O3均具有一定的碱性,能与酚类前驱体发生中和反应,阻滞了Ullman反应的发生,进而减少了PCDD/Fs的生成.

Inhibition of calcium-based composite oxides on the formation of PCDD/Fs from PCP precursor was investigated in a laboratory-scale reactor at 280 ℃ for 2 h. The calcium-based composite oxides were prepared by mixing Ca O with Mg O,Ce O2,Ba O and γ-Al2O3,respectively.The results show that the total suppressing efficiency（ TSE） of PCDD/Fs formation by these calcium-based composite oxides were all rather high. The addition of Ce O2,Ba O and γ-Al2O3 into Ca O reduced the total amount of produced PCDD/Fs. However,only Ba O increased the TSE in I-TEQ（ TSEI-TEQ） of the newly formed PCDD/Fs. The TSE and TSEI-TEQof PCDD/Fs formation over Ca O and Ba O mixture were 99. 98% and 99. 62%,respectively. It was speculated that since Ca O,Mg O,Ce O2,Ba O and γ-Al2O3 are alkaline,they can react with the PCP precursor,to prevent the occurrence of Ullman reaction and the formation of PCDD/Fs.