木质纤维类生活垃圾热解过程矿物质和碳结构的演化规律

Evolution of mineral matter and carbonaceous structure during lignocellulosic municipal solid waste pyrolysis

使用水平管式炉,在不同热解温度（500~1 000℃）条件下对废纸屑和樟树叶两种木质纤维类生活垃圾进行了热解实验,分别采用X射线衍射（XRD）和拉曼光谱研究了样品所含矿物质和碳结构随热解温度的变化。结果表明,废纸屑和樟树叶含有的主要矿物分别为方解石和草酸钙,在500℃之前草酸钙全部转化为方解石,焦样中的方解石在800℃以后逐渐分解并形成生石灰。拉曼光谱对生活垃圾焦的碳结构变化非常敏感,低温热解时生活垃圾的大分子结构发生缩合和解聚,产生了孤立sp2碳原子,导致峰参数D1峰半高宽和峰面积比值ID1/IG逐渐增大;高温热解时晶体sp2碳原子增多,导致D1峰半高宽和ID1/IG逐渐减小。焦样的碳结构有序度随热解温度升高先降低后提高。

Two lignocellulosic municipal solid wastes including waste paper and camphor tree leaf were pyrolyzed at temperatures of 500 ~ 1 000 ℃ in a horizontal tube furnace.The mineral matter and carbonaceous structure of both municipal solid wastes were characterized by X-ray diffraction（ XRD） and Raman spectroscopy,respectively.The evolution of mineral matter and carbonaceous structure during pyrolysis was investigated.The results demonstrate that the original mineral matter in waste paper and camphor tree leaf is principally calcite and weddellite,respectively.Weddellite can completely decompose to calcite below500 ℃,and then turn to lime above 800 ℃.In addition,Raman spectroscopy is found to be considerably sensitive to the carbonaceous structure of municipal solid wastes.At relatively lowtemperatures, the macromolecules of municipal solid wastes are subjected to the condensation and depolymerization,resulting in an increase in the amount of isolated sp2 carbon,thus the D1 band full width at half maximum（ FWHM） and band area ratio ID1/IGincrease with increasing pyrolysis temperature.In contrast,at relatively high temperatures,the D1 band FWHMand ID1/ IGdecrease,which is attributed to the increase of ordered sp2 carbon.Consequently,the order of carbonaceous structure of both municipal solid wastes shows an initial decrease and then an increase with the increasing of pyrolysis temperature.