有机氯对废弃物衍生焦炭结构和反应活性的影响

Effect of organic chlorine on the structure and reactivity of char derived from solid waste

采用聚氯乙烯(PVC)为氯源与废弃物典型组分等量混合后在500℃氮气气氛条件下制成焦炭样品,通过热重(TGA/DTG)、扫描电子显微镜(SEM)、能谱(EDS)和拉曼光谱分析手段,对样品进行了焦炭碳结构和反应活性分析.结果表明,有机氯会抑制废弃物衍生焦炭的活性,使淀粉热解焦炭最大反应速率从0.15 min^-1下降至0.13 min^-1.动力学方面,淀粉(60.575 kJ·mol^-1)和纤维素焦炭(101.686 kJ·mol^-1)样品的表观活化能均小于其与PVC混合物的热解焦炭;而PVC的添加则会使淀粉和纤维素热解焦炭中的C结构更趋于无序化.微观角度方面,添加PVC后的焦炭表面同样呈现出纤维丝状结构,但气壁更加粗糙,表面有较多的褶皱,破坏了由废弃物内在碱金属催化形成的孔隙结构,使得焦炭表面结构破碎化程度更高.

The paper used polyvinyl chloride(PVC)to simulate source of chlorine.The char samples were obtained from pyrolysis of three components of starch,lignin,cellulose with the same amount of PVC addition at 500℃under N2 atmosphere.The experiment of thermogravimetry(TGA/DTG),scanning electron microscope(SEM),energy spectrum(EDS)and Raman spectrum were used to analyze the carbon structure and reactivity of char samples.The results showed that the reactivity of char was inhibited by organic chlorine,making the maximum reaction rate of starch char decrease from 0.15 min-1 to 0.13 min-1.As for kinetics,the apparent activation energy of starch(60.575 kJ·mol^-1)and cellulose coke(101.686 kJ·mol^-1)samples was much smaller than that of the pyrolysis char with PVC mixture The PVC addition could also result in a more disordered carbon structure of starch and cellulose char samples.As for microstructure,the char surface after adding PVC also presents a fiber⁃like structure,but the gas wall is more rough,with more folds on the surface,destroying some micropores originally formed by alkali metal,making the char surface structure more fragmented.