Abstract:

Aiming at the problems of complex plastic components, unstable components and difficult quality control of pyrolysis oil production, this study used municipal sludge as raw material to prepare Fe-loaded sludge-based biochar catalyst, and conducted research on the experimental route of promoting tar cracking and syngas production by catalytic pyrolysis of polypropylene plastic (PP). The tar removal effect in PP pyrolysis products, the key components of H₂-rich syngas, and the effect of catalytic pyrolysis process on the surface characteristics of sludge-based biochar were analyzed. The results showed that the sludge-based biochar with FeCl₃ impregnation ratio of 5% (mass fraction, calculated as Fe) could significantly promote the catalytic pyrolysis of PP to produce hydrogen. The hydrogen yield reached 17.39mmol/g_plastic, which was higher than the biochar without Fe-loaded catalysis control group of 268.43% and the pure PP pyrolysis control group of 2046.91%, respectively. The catalytic pyrolysis process strengthened the tar cracking, and the tar cracking rate reached 29.65%. The relative proportion of alcohols in the tar component decreased, and the relative proportion of olefins and halogenated esters increased. At the same time, a special thin-layered pore structure appeared on the surface of the sludge-based biochar after catalytic pyrolysis, and the specific surface area increased to 225.90m²/g. XPS analysis found that the relative proportion of carbon-oxygen functional groups on the surface of sludge-based biochar bound to carbon, lattice oxygen and carboxyl oxygen increased, which proved that more active sites appeared at this Fe impregnation ratio.

Key words: sludge, biochar, polypropylene, pyrolysis, iron

摘要：

针对塑料成分复杂、热解产油组分不稳定和品质控制难的问题，本文以市政污泥为原料制备Fe负载污泥基生物炭催化剂，以聚丙烯塑料（PP）催化热解促进焦油裂解与合成气生产的试验路线开展研究，分析了PP热解产物中焦油的去除效果、富H₂合成气关键组分以及催化热解过程对污泥基生物炭表面特性的影响。结果显示FeCl₃浸渍比为5%（质量分数，以Fe计）制备的污泥基生物炭可显著促进PP催化热解产氢，1g塑料氢气产率达17.39mmol，分别高于未经Fe负载污泥生物炭催化对照组268.43%以及纯PP热解对照组2046.91%。催化热解过程强化了焦油裂解，焦油裂解率达29.65%。焦油组分中醇类物质相对占比下降，烯烃类与卤代酯类物质相对占比上升。同时，催化热解后污泥基生物炭表面出现特殊的薄层状孔隙结构，比表面积增至225.90m²/g。XPS分析发现污泥基生物炭表面的碳氧官能团结合碳、晶格氧以及羧基氧相对比例上升，证明在此Fe浸渍比例下出现了更多的活性位点。

关键词: 污泥, 生物炭, 聚丙烯, 热解, 铁