Developing hierarchically ultra-micro/mesoporous biocarbons for highly selective carbon dioxide adsorption
Developing hierarchically ultra-micro/mesoporous biocarbons for highly selective carbon dioxide adsorption
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DOI：
10.1016/j.cej.2018.11.062
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发表时间：
2019-04-01
影响因子：
15.1
通讯作者：
Snape, Colin
中科院分区：
文献类型：
--
作者：
Liu, Xin;Sun, Chenggong;Snape, Colin
活性炭是目前正在开发的二氧化碳捕获吸附材料的重要类别之一。然而，在低CO2分压和/或相对高的烟道气温度下的低吸附能力和选择性是碳在实际条件下应用于燃烧后CO2捕集的主要障碍。在这里，我们报告了成功的制备分级超微/介孔生物炭从使用一个简单的一步法与低品位的生物质废物作为原料。在室温和低CO2分压下，生物炭的吸附容量为1.90 mmol/g，亨利定律CO2/N-2选择性高达212。与传统的化学活化法制备炭材料不同，该方法使生物废弃物衍生炭材料具有独特的分级生物模态孔结构，其特征在于高中孔率和高超微孔率，孔径分布窄。结果表明，由于同时实现的钾插层，独特的表面纹理特性沿着增强的表面化学为在低CO2分压下具有高CO2/N-2选择性的CO2吸附创造了有利条件，而中孔的存在大大增加了CO2吸附动力学。CO2吸附热的测量证实了所制备的生物炭对CO2分子的强表面亲和力。
Activated carbons represent one of the important categories of the adsorbent materials for CO2 capture currently under development. However, the low adsorption capacity and selectivity at low CO2 partial pressure and/or relatively high flue gas temperatures is the main barrier for carbons to be applied in post-combustion CO2 capture under practical conditions. Here, we report the successful preparation of hierarchical ultra-micro/mesoporous bio-carbons from using a facile one-step method with a low-grade biomass waste as the feedstock. The bio-carbons exhibit high adsorption capacities (1.90 mmol/g) and record-high Henry's law CO2/N-2 selectivities up to 212 at ambient temperature and low CO2 partial pressure. Unlike conventional chemical activation process for manufacturing carbon materials, the integrated compaction-carbonization-activation method proposed endows the biowaste-derived carbons with unique hierarchical bio-modal pore structures, which are highly characterised by their high mesoporosity and high ultra-microporosity with narrow pore size distributions. The results demonstrated that the unique surface textural properties along with the enhanced surface chemistry due to the simultaneously achieved potassium intercalation created favourable conditions for CO2 adsorption with high CO2/N-2 selectivity at low CO2 partial pressures, whilst the presence of mesoporosity greatly increased the CO2 adsorption kinetics. Measurements of CO2 adsorption heat confirmed the strong surface affinity of the prepared bio-carbons to CO2 molecules.