高硫石油焦制备富硫高活性吸附剂烟气喷射脱汞的机理研究

Mercury emission from coal ranks the forth biggest pollutant following dust, SO2 and NOx. This project proposed that a novel and high effective adsorbent activated from petrochemical industry by-product high sulfur petroleum coke (HSPC) injecting into flue gas to capture mercury in place of expensive commercial sulfur loaded activated carbon for coal-fired power plant. The original sulfur existence, its transfer of species in pyrolysis and activation processes, and enhancement for mercury adsorption will be thoroughly studies in experiments and mechanisms. Catalytic reaction condition and principle will be detected for organic sulfur in HSPC transferring into inorganic and elemental one in the process of activation. Chemical groups and sorption active sites on surface of the adsorbent will be recognized in its sorts and distributions. Effects of superficial chemistry and speciation structure of the new sulfur enriched high reactive petroleum coke (SEPC) on mercury adsorption and chemical dynamics will be explored. Catalytic reaction condition and mechanisms of the elemental sulfur extracted from flue gas after reductive reaction by the new SEPC on mercury enhanced adsorption will be studied. The mechanisms of activated enrichment of sulfur in heat conversion process of the original HSPC, sulfur extraction from flue gas via the reductive reaction, and how the sulfur speciation speeds up mercury adsorption will also discussed. Experimental and theoretical research will be done on mercury adsorption and removal through flue gas injection of SEPC in to coal-fired flue gas. Theories and models of mercury adsorption will be developed through this study. It is hopefully to see a new technique of newly developed low-cost and high effective adsorbent injecting into flue gas to removal mercury efficiently in the near future following accomplish of this project.

燃煤汞污染已成为继粉尘、SO2、NOx之后的第四大污染物。本项目提出以石化行业副产物高硫石油焦代替高成本载硫活性炭作为燃煤烟气喷射脱汞吸附剂，对其中硫的赋存形态以及在热解、活化等热转化过程中硫向表面富集、形态转化、强化汞吸附的机理进行深入细致的研究。探明热解、活化过程中吸附剂中有机硫向无机硫和单质硫转化的催化反应机理和条件，揭示吸附剂表面亲汞官能团和汞吸附活性位的种类和分布，考察富硫高活性石油焦表面化学与形态结构对汞吸附的反应动力学机理和影响规律。研究富硫高活性石油焦还原烟气中SO2和析出单质硫对强化汞吸附的催化反应条件和反应机制。探讨高硫石油焦热转换过程中活化富硫、还原烟气固硫、硫形态强化汞吸附的机理。进行富硫高活性石油焦烟气汞吸附脱除的系统性实验和理论研究，发展吸附剂汞吸附的理论体系。以期孵化出具有我国自主知识产权和工程实际应用价值的燃煤烟气喷射富硫高活性石油焦高效脱汞技术。

本项目提出以石化行业副产物高硫石油焦代替高碳能源活性炭作为燃煤烟气喷射脱汞的廉价高效吸附剂，并首次系统深入地研究了高硫石油焦中硫的赋存形态以及热解、KOH活化及SO2活化过程中硫元素向石油焦表面富集转化的规律，能够促进汞吸附的含硫官能团的产生条件、数量及分布，及其吸附脱除烟气中Hg0的作用机理。首先，进行了高硫石油焦热解特性及其汞吸附的基础性研究，结合XPS及元素分析等表征方法，从微观机理方面研究了石油焦中原生硫的热转化特性及其对单质汞有限的吸附促进作用。其次，从改善石油焦孔隙结构和提高其表面汞吸附活性的角度，分别就KOH碱活化及元素硫担载、SO2物理活化改性两方面进行研究，并对活化前后的石油焦吸附剂进行了物理化学特性和微观结构形貌等一系列表征，从微观机理方面论证活化改性对提高石油焦吸附剂汞吸附性能的作用机理，特别是活化过程中硫元素的富集及转化规律，并优化出活化改性制备高硫石油焦脱汞吸附剂的最佳制备条件。第三，在固定床汞吸附实验装置上进行了大量的吸附剂性能评价与汞吸附机理的实验研究和理论分析，考察了高硫石油焦吸附剂制备条件及吸附过程操作参数对吸附剂脱汞过程的影响机理，并在此基础上获得了不同形态硫对汞的吸附活性差异及吸附形态差异，探索出原生高硫石油焦获得高效汞脱除效率的实用技术路线和方法。研究结果表明，不同硫形态的汞吸附活性按如下顺序排列：元素硫、二硫化物、非氧化态有机硫、氧化态硫。且不同硫形态的汞吸附热稳定性、对吸附过程操作参数的敏感性均不同，选择合适的制备条件和操作参数下制备的高硫石油焦吸附剂具有较高的脱汞效率，可用于燃煤烟气喷射脱汞技术中。