氧化锌常温精脱硫性能主要影响因素及研究进展

Main influencing factors and research progress of zinc oxide desulfurization performance at room temperature

  • 摘要: 硫化氢是一种无色、有臭鸡蛋气味的有毒气体,广泛存在于煤制气、沼气、天然气等工艺气体中。硫化氢不仅会腐蚀管道、毒化下游催化剂,而且危害人类健康,即使微量硫化氢也会致人死亡。此外,当硫化氢排放进入空气中其氧化产物二氧化硫会导致酸雨,后者会严重危害植被并污染地下水。因此,为了保护人体健康和生态环境、维持工艺设备的正常运行,各种工艺气体中的硫化氢必须进行深度去除。氧化锌是目前应用较为广泛的一类脱硫剂,在工业生产中作为把关脱硫剂使用。常温下氧化锌脱除硫化氢更具有热力学优势,能将各种工艺气体中的硫化氢质量浓度降低至0.1 mg/m3以下,可以很好地满足各种工艺和环保法规对原料气中硫化氢含量的要求。但受反应动力学影响,氧化锌常温脱硫活性非常低。为了提高氧化锌常温脱硫活性,适应日渐严格的环保法规及新兴工艺技术如质子交换膜燃料电池等对原料气中硫化氢含量的要求,总结了氧化锌脱硫过程中可能的脱硫机理,概述了晶粒尺寸和比表面积、孔隙结构、晶格缺陷、异质结构和相对湿度等主要因素对脱硫性能的影响机制,综述了负载型和多孔纳米氧化锌脱硫剂的研究进展,最后分析了使用后废脱硫剂的再生状况,以期为脱硫剂的优化设计提供借鉴与参考。

     

    Abstract: H2S is a colorless and highly toxic gas with rotten eggs-like odor, which widely presents in coal derived gas, biogas, natural gas and other industrial gases. Besides corroding pipelines and poisoning downstream catalysts, it can also endanger human health, even trace amounts of H2S can cause people death. Moreover, when H2S is released into the air, its oxidation product, sulfur dioxide, can cause acid rain, which can seriously harm forests and pollute groundwater. Therefore, in order to protect human health and ecological environment, maintain the operation of industrial production, H2S in various industrial gases must be deeply removed. Zinc oxide has been widely used as polishing adsorbent in industrial process. In fact, zinc oxide shows favorable thermodynamics at room temperature, it is capable of reducing H2S to less than 0.1 mg/m3 and well meet the strict requirements of various processes and environmental regulations on the concentration of H2S in feed gas. However, limited by reaction kinetics, the desulfurization activity of zinc oxide at room temperature is very low. In order to improve the desulfurization activity of zinc oxide at room temperature, meeting the requirements of increasingly stringent environmental protection regulations and emerging technology such as proton exchange membrane fuel cells on H2S content, this study provides a summary of the possible desulfurization mechanism during zinc oxide desulfurization process, highlighting the influence of key factors such as grain size and specific surface area, pore structure, lattice defects, heterostructure and relative humidity on the desulfurization performance. The recent advance of supported and porous nano zinc oxide desulfurizer is discussed. Furthermore, the analysis of the regeneration status of spent desulfurizer is presented. This review aims to offer valuable insights for the optimal design of desulfurizer.

     

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