State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074, Wuhan, Hubei, China.
State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074, Wuhan, Hubei, China.
Chemosphere. 2022 Feb;288(Pt 1):132524. doi: 10.1016/j.chemosphere.2021.132524. Epub 2021 Oct 9.
Oily sludge is a hazardous waste due to the enrichment of nitrogen, sulfur, PAHs, and heavy metals. In this work, an oily sludge from oil refining factory was pyrolyzed at various temperatures of 250-850 °C in a fixed bed reactor focusing on product distribution and migration of hazardous compounds of PAHs, sulfur, nitrogen-containing compounds, and heavy metals. The mechanism of PAHs formation and migration of nitrogen, sulfur, heavy metals were elucidated by comprehensive analysis of the solid, liquid, and gas products. The distribution and risk analysis of heavy metals were also conducted. The pyrolytic products distribution was markedly affected by pyrolysis temperatures. A maximum oil yield was observed at 500 °C, which can further crack into gas due to secondary reaction. The pyrolytic gas was enriched in the order of CO > CO > CH > H. At lower temperatures, CO was largely generated due to the elimination of oxygen-containing functional groups, while H was mainly formed above 450 °C due to the recombination reaction. Higher temperatures promoted more N-/S-containing compounds into tar and gas phases. The N-/S-containing compounds mainly included NH, HCN, HS, SO, COS in the gas phase and amines, indoles, pyridines, nitriles, thiophenes in liquid phase. PAHs with 2-ring to 5-ring were mainly generated due to the secondary reaction at higher temperatures. Moreover, Pyrolysis caused the accumulation of heavy metals in chars. Cd presented a high potential risk while the other heavy metals in chars presented a low risk.
含油污泥由于氮、硫、多环芳烃 (PAHs) 和重金属的富集而属于危险废物。在这项工作中，在固定床反应器中，将来自炼油厂的含油污泥在 250-850°C 的各种温度下进行热解，重点研究多环芳烃、硫、含氮化合物和重金属等有害物质的分配和迁移。通过对固、液、气产物的综合分析，阐明了 PAHs 形成和氮、硫、重金属迁移的机理。还对重金属的分布和风险进行了分析。热解产物的分布明显受到热解温度的影响。在 500°C 时观察到最大的油收率，由于二次反应，它可以进一步裂化成气体。热解气中 CO 的含量最高，其次是 CO 和 CH。在较低的温度下，由于含氧官能团的消除，大量生成 CO，而在 450°C 以上，由于重组反应，主要生成 H。较高的温度促进更多的 N-/S-含化合物进入焦油和气相。N-/S-含化合物主要包括气相中的 NH、HCN、HS、SO 和 COS，以及液相中的胺、吲哚、吡啶、腈和噻吩。由于较高温度下的二次反应，主要生成了 2 环至 5 环的多环芳烃。此外，热解导致重金属在焦中的积累。Cd 具有很高的潜在风险，而焦中的其他重金属则具有较低的风险。
