Co-pyrolysis and Cl release characteristics of PVC and lignocellulose
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摘要: 生活干垃圾的主要有机组分为聚氯乙烯 (PVC)等多聚类废弃物和木质纤维素,为了阐明其热解特性和Cl的迁移规律,本实验研究了PVC与木质纤维三组分(纤维素、半纤维素和木质素)共热解过程的相互作用及氯化物释放特性。结果表明,在脱氯化氢阶段,PVC与三组分之间存在正协同作用,PVC能够加速三组分的热解;共热解过程中Cl主要以HCl和CH3Cl的形态释放,其次是氯苯。纤维素与PVC共热解过程中,HCl作为酸性催化剂促进生成了更多的芳香烃。纤维素与PVC共热解过程中,HCl作为酸性催化剂促进生成了更多的芳香烃;PVC与半纤维素共热解时,半纤维素生成的乙酸降低了HCl释放的起始温度,25–30 ℃;与纤维素和半纤维素相比,木质素对HCl释放的抑制作用最大。木质素增强了PVC化学键C−Cl断裂, 减少HCl但促进了CH3Cl释放。三组分促进了PVC的热裂解反应,降低了脱氯化氢阶段的反应活化能,混合物热解平均活化能比纯PVC分别降低了25.88%–48.73%,36.46%–43.73%,44.88%–72.83%。Abstract: To elucidate the pyrolysis characteristics and Cl release law of domestic dry waste, these organics are divided into polyvinyl chloride (PVC), polymorphic waste, and lignocellulose. The interaction mechanism and chloride release characteristics of PVC with llulose, xylan, and lignin, the three components of lignocellulose, were examined in the co-pyrolysis process. The results show that the PVC and the three components synergize positively in the de-hydrogen chloride stage. The PVC can accelerate the pyrolysis of the three components. Cl is mainly released as HCl, CH3Cl, and chlorobenzene during the co-pyrolysis process. In the co-pyrolysis process of PVC and cellulose, HCl acts as an acidic catalyst to promote the formation of more aromatic hydrocarbons. During the co-pyrolysis of PVC and xylan the acetic acid produced by xylan reduces the starting temperature of HCl release by about 25–30 ℃. Compared with cellulose and xylan, lignin has the greatest inhibitory effect on HCl release. Lignin enhances the chemical bond C–Cl breakage in PVC, reducing HCl but promoting the release of CH3Cl. In short, the three-component promotes the thermal cracking reaction of PVC, reduces the activation energy of the response in the de-hydrogen chloride stage, and produces more chloride. The average activation energies of pyrolysis of PVC with the mixture of three-component are reduced by 25.88%–48.73%, 36.46%–43.73%, and 44.88%–72.83%, respectively.
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Key words:
- PVC /
- lignocellulose /
- co-pyrolysis /
- de-chlorination
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表 1 PVC和纤维素、半纤维素、木质素的工业分析与元素分析
Table 1 Proximate and ultimate analysis of PVC and cellulose, xylan, lignin
Material Ultimate analysis w/% Proximate analysis w/% LHV /(MJ·kg–1) C H N Oa S Cl A V FC b M PVC 38.70 4.74 0.00 0.05 0.01 56.50 0.00 94.09 5.73 0.18 20.11 Cellulose 42.61 6.13 0.00 51.12 0.04 0.00 0.00 89.68 5.49 4.83 21.75 Xylan 42.54 6.36 0.00 51.07 0.03 0.00 0.34 91.01 0.61 8.04 17.09 Lignin 45.69 3.96 0.00 50.56 0.06 0.00 9.50 52.76 35.87 1.87 17.11 a: by difference (O=100−C−H−N−Cl−S); b: by difference (FC=100−A−V−M) -
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