Jiang Jie, Diao Yongfa
College of Environmental Science and Engineering, Donghua University, Shanghai 201620, China.
Int J Environ Res Public Health. 2022 Jun 9;19(12):7082. doi: 10.3390/ijerph19127082.
As the solid waste by-product from the delayed coking process, high-sulfur petroleum coke (HSPC), which is hardly used for green utilization, becomes a promising raw material for Hg removal from coal-fired flue gas. The effects of the physical-chemical evolution of HSPC on Hg removal are discussed. The improved micropores created by pyrolysis and KOH activation could lead to over 50% of Hg removal efficiency with the loss of inherent sulfur. Additional S-containing and Br-containing additives are usually introduced to enhance active surface functional groups for Hg oxidation, where the main product are HgS, HgBr, and HgBr. The chemical-mechanical activation method can make additives well loaded on the surface for Hg removal. The DFT method is used to sufficiently explain the micro-scale reaction mechanism of Hg oxidation on the surface of revised-HSPC. ReaxFF is usually employed for the simulation of the pyrolysis of HSPC. However, the developed mesoporous structure would be a better choice for Hg removal in that the coupled influence of pore structure and functional groups plays a comprehensive role in both adsorption and oxidation of Hg. Thus, the optimal porous structure should be further explored. On the other hand, both internal and surface sulfur in HSPC should be enhanced to be exposed to saving sulfur additives or obtaining higher Hg removal capacity. For it, controllable pyrolysis with different pyrolysis parameters and the chemical-mechanical activation method is recommended to both improve pore structure and increase functional groups for Hg removal. For simulation methods, ReaxFF and DFT theory are expected to explain the micro-scale mechanisms of controllable pyrolysis, the chemical-mechanical activation of HSPC, and further Hg removal. This review work aims to provide both experimental and simulational guidance to promote the development of industrial application of Hg adsorbent based on HSPC.
作为延迟焦化过程产生的固体废弃物副产品，高硫石油焦（HSPC）难以进行绿色利用，却成为了燃煤烟气脱汞的一种有前景的原材料。本文讨论了HSPC的物理化学演变对汞去除的影响。热解和KOH活化产生的改良微孔可在固有硫损失的情况下实现超过50%的汞去除效率。通常会引入额外的含硫和含溴添加剂来增强活性表面官能团以促进汞氧化，主要产物为HgS、HgBr和HgBr。化学机械活化方法可使添加剂很好地负载在表面以实现汞去除。采用密度泛函理论（DFT）方法充分解释了改性HSPC表面汞氧化的微观反应机理。反应分子动力学（ReaxFF）通常用于模拟HSPC的热解。然而，发达的介孔结构对于汞去除将是更好的选择，因为孔结构和官能团的耦合影响在汞的吸附和氧化中都发挥着综合作用。因此，应进一步探索最佳的多孔结构。另一方面，应增强HSPC内部和表面的硫暴露，以节省硫添加剂或获得更高的汞去除能力。为此，建议采用具有不同热解参数的可控热解和化学机械活化方法，以改善孔结构并增加用于汞去除的官能团。对于模拟方法，期望ReaxFF和DFT理论能够解释HSPC可控热解、化学机械活化以及进一步汞去除的微观机理。本综述旨在提供实验和模拟指导，以推动基于HSPC的汞吸附剂工业应用的发展。
