Porous silicas have been extensively investigated as amine carriers for the production of CO adsorbents, while few studies demonstrated that as-synthesized silicas (without template removal) can also serve as good amine carriers for efficient CO capture. This raises a fundamental question of whether the time-consuming and energy-intensive process of removing the template from as-synthesized silicas is still necessary. More importantly, a reasonable mechanism is quite needed to explain the as-synthesized silicas as effective amine carriers. To this end, in this study, four types of as-synthesized silicas were compared together with their corresponding porous silicas as amine carriers for CO capture. Experimental results show that as-synthesized silicas exhibit comparable or even better performance at medium amine loadings (50 ∼ 60 wt%), including larger CO adsorption capacities and better cyclic stability, while porous silicas predominate at high amine loadings (70 wt%). Molecular simulation results indicate that the amine species are located in the interparticle cavities in the silicas rather than in the structural pores. This work provides important guidance for the future design of practical solid-amine CO adsorbents.

中文翻译：

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用于 CO2 捕获的胺浸渍合成二氧化硅：实验研究和机理分析


多孔二氧化硅作为用于生产 CO 吸附剂的胺载体已被广泛研究，但很少有研究表明合成的二氧化硅（无需去除模板）也可以作为有效 CO 捕获的良好胺载体。这就提出了一个基本问题：从合成二氧化硅中去除模板的耗时且耗能的过程是否仍然必要。更重要的是，非常需要一个合理的机制来解释合成的二氧化硅作为有效的胺载体。为此，在本研究中，对四种合成二氧化硅及其相应的多孔二氧化硅作为 CO 捕获的胺载体进行了比较。实验结果表明，合成的二氧化硅在中等胺负载量（50~60 wt%）下表现出相当甚至更好的性能，包括更大的CO吸附能力和更好的循环稳定性，而多孔二氧化硅在高胺负载量（70 wt%）下占主导地位。分子模拟结果表明，胺类物质位于二氧化硅的颗粒间空腔中，而不是结构孔中。这项工作为未来实用固体胺CO吸附剂的设计提供了重要指导。