Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET), Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing, 210044, China.
Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Nanjing, 210042, China.
Chemosphere. 2021 Jan;262:128412. doi: 10.1016/j.chemosphere.2020.128412. Epub 2020 Sep 23.
This study explored the feasibility of char and tar formation inhibition during supercritical water gasification of sewage sludge (SS) by additive addition. Experiments were conducted in autoclave with 5 wt% additives at 400 °C for 30 min. The non-additive gasification of SS resulted in a higher char yield (12.6%) and tar yield (16.4%). In contrast, the five additives reduced the char yield (3.4-11.2%), the inhibition of char yield by additives was in the order of NaOH > KCO > HO > acetic acid > NiCl. The inhibition of tar formation was limited, tar yield were 13.3-18.8% with additives. Fourier-transform infrared spectroscopy was used to determine the functional groups of char/tar, and it was observed that the spectra of char were more similar to those of hydrochar obtained in a low-temperature experiment. Model compounds of potential precursors was also tested to study the mechanism of action of additives, the results reveal that additives have different effects on char/tar formation from various components, the inhibitory effects of additives on the yield of char from humus and tar from lignin were limited. Finally, the effects of additives on gasification were also studied. The addition of additives will have an impact on the hydrogen yield and gasification efficiency, which also needs to be considered when use additive to reduce the by-products yield.
本研究通过添加物的添加探索了在超临界水气化污水污泥（SS）过程中抑制炭和焦油形成的可行性。实验在高压釜中进行，添加物浓度为 5wt%，温度为 400°C，时间为 30min。未添加添加剂的 SS 超临界水气化会产生更高的炭产率（12.6%）和焦油产率（16.4%）。相比之下，五种添加剂降低了炭产率（3.4-11.2%），添加剂对炭产率的抑制作用顺序为 NaOH>KCO>HO>醋酸>NiCl。焦油形成的抑制作用有限，添加物存在时焦油产率为 13.3-18.8%。傅里叶变换红外光谱用于确定炭/焦油的官能团，结果表明炭的光谱与低温实验中获得的水炭的光谱更相似。还测试了潜在前体的模型化合物，以研究添加剂的作用机制，结果表明添加剂对不同成分的炭/焦油形成具有不同的影响，添加剂对腐殖质炭产率和木质素焦油产率的抑制作用有限。最后，还研究了添加剂对气化的影响。添加剂的添加会对氢气产率和气化效率产生影响，在使用添加剂来降低副产物产率时，这也需要考虑。
