Abstract：
The escalating volume of sewage sludge (SS) generated poses challenges in disposal, given its potential harm to the environment and human health. This study explored sustainable solutions for SS management with a focus on energy recovery. Employing CO2-assisted pyrolysis, we converted SS into flammable gases (H2 and CO; syngas). Single-stage pyrolysis of SS in a CO2 conditions demonstrated that CO2 enhances flammable gas production (especially CO) through gas phase reactions (GPRs) with volatile matter (VM) at temperatures ≥ 520 ˚C. Specifically, the CO2 partially oxidized the VM released from SS and concurrently underwent reduction into CO. To enhance the syngas production at temperatures ≤ 520 ˚C, multi-stage pyrolysis setup with additional heat energy and a Ni/Al2O3 catalyst were utilized. These configurations significantly increased flammable gas production, particularly CO, at temperatures ≤ 520 ˚C. Indeed, the flammable gas yield in the catalytic pyrolysis of SS increased from 200.3 mmol under N2 conditions to 219.2 mmol under CO2 conditions, representing a 4.4-fold increase compared to single-stage pyrolysis under CO2 conditions (50.0 mmol). By integrating a water-gas-shift reaction, the flammable gases produced from CO2-assisted catalytic pyrolysis were expected to have the potential to generate revenue of US$4.04 billion. These findings highlight the effectiveness of employing CO2 in SS pyrolysis as a sustainable and effective approach for treating and valorising SS into valuable energy resources.
摘要：
产生的污水污泥(SS)的不断增加的体积给处置带来了挑战，鉴于其对环境和人类健康的潜在危害。本研究探索了SS管理的可持续解决方案，重点是能源回收。采用CO2辅助热解，我们将SS转化为可燃气体（H2和CO；合成气）。在CO2条件下SS的单级热解表明，在温度≥520℃时，CO2通过与挥发性物质（VM）的气相反应（GPR）提高了可燃气体的产量（尤其是CO）。具体来说,CO2部分氧化了从SS释放的VM，并同时还原为CO。为了提高温度≤520℃时的合成气产量，使用了具有额外热能和Ni/Al2O3催化剂的多级热解装置。这些配置显著增加了易燃气体的产量，特别是CO，温度≤520℃。的确,SS的催化热解中的可燃气体产率从N2条件下的200.3mmol增加到CO2条件下的219.2mmol，表示与CO2条件下的单级热解(50.0mmol)相比增加4.4倍。通过整合水煤气变换反应，二氧化碳辅助催化热解产生的可燃气体预计有可能产生40.4亿美元的收入。这些发现强调了在SS热解中使用CO2作为处理SS并使其成为有价值的能源的可持续且有效的方法的有效性。
