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    浸渍层溶液燃烧合成应用于太阳能直接煅烧的CaO基CO2吸附剂

    CaO-based CO2 sorbents for direct solar-driven calcium looping synthesized by impregnated layer solution combustion method

    • 摘要: 钙循环(CaL)碳捕集技术因CaO吸附剂理论吸附容量高、原料成本低廉且来源广泛等优势,具有广阔的应用前景。然而,传统CaL系统采用的煤粉掺燃煅烧方式,易导致煤源杂质组分与活性CaO发生交互反应,造成CaO基吸附剂失活。采用聚光太阳能直接煅烧替代煤粉掺燃,可有效规避煤源杂质对CaO基吸附剂的负面影响,但该模式下吸附剂需同时具备优良的CO2循环吸附稳定性与优异的光谱吸收特性。通过浸渍层模板辅助燃烧合成法制备Mn负载CaO基吸附剂,重点探究燃烧合成温度、浸渍层模板种类及Mn载体添加比例对吸附剂CO2循环吸附性能的影响。结果表明,以脱脂棉为浸渍层模板时,所制备吸附剂因孔隙结构改善,在17次循环中CO2最高捕集量达0.380 g/g。燃烧合成温度对吸附剂CO2捕集性能影响显著,750 ℃下制备的CaO基吸附剂具有疏松多孔结构,可有效避免吸附剂过度烧结并抑制CaCO3相原位生成,故750 ℃为理想的燃烧合成及煅烧温度。Mn负载CaO基吸附剂中,Ca2MnO4晶粒均匀分布,显著抑制了高温循环过程中吸附剂的烧结效应,进而提升其吸附性能,其中质量分数为15%的Mn负载比例下CaO基吸附剂表现出优异的CO2循环吸附性能和较高的平均太阳光谱吸收率(~41%)。综合分析表明,以脱脂棉为浸渍层模板、750 ℃下直接燃烧合成的质量分数为15% Mn负载的CaO基吸附剂,是CaL碳捕集系统的潜在优良吸附剂选择。

       

      Abstract: Calcium looping (CaL) CO2 capture technology exhibits broad application prospects due to the advantages of CaO sorbents, such as high theoretical adsorption capacity, low raw material cost, and wide availability. However, the traditional coal-blended combustion calcination method adopted in CaL systems tends to cause interactive reactions between coal-derived impurity components and active CaO, leading to the deactivation of CaO-based sorbents. Replacing coal-blended combustion with concentrated solar direct calcination can effectively avoid the negative impacts of coal-derived impurities on CaO-based sorbents, but sorbents in this mode need to simultaneously possess excellent CO2 cyclic adsorption stability and superior spectral absorption characteristics. In this study, Mn-supported CaO-based sorbents were prepared via the impregnated template-assisted combustion synthesis method. The effects of combustion synthesis temperature, types of impregnated templates, and Mn loading ratio on the CO2 cyclic adsorption performance of the sorbents were systematically investigated. The results show that when degreased cotton is used as the impregnated template, the prepared sorbent achieves a maximum CO2 capture capacity of 0.380 g/g after 17 cycles due to the improved pore structure. The combustion synthesis temperature has a significant influence on the CO2 capture performance of the sorbents. The CaO-based sorbent prepared at 750 ℃ exhibits a loose and porous structure, which can effectively prevent excessive sintering of the sorbent and inhibit the in-situ formation of CaCO3 phase. Thus, 750 ℃ is determined as the optimal combustion synthesis and calcination temperature. In the Mn-supported CaO-based sorbents, Ca2MnO4 grains are uniformly distributed, which significantly suppresses the sintering effect of the sorbents during high-temperature cycles and thereby enhances their adsorption performance. Among them, the CaO-based sorbent with a 15% Mn loading ratio shows excellent CO2 cyclic adsorption performance and a high average solar spectral absorptivity (~41%). Comprehensive analysis indicates that the 15% Mn-supported CaO-based sorbent directly synthesized via combustion at 750 ℃ using degreased cotton as the impregnated template is a potential high-performance sorbent for CaL carbon capture systems.

       

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