Application of a High-Throughput Analyzer in Evaluating Solid Adsorbents for Post-Combustion Carbon Capture via Multicomponent Adsorption of CO₂, N₂, and H₂O

Despite the large number of metal–organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal–organic frameworks, zeolites, mesoporous silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg2(dobpdc) (mmen = N,N′-dimethylethylenediamine, dobpdc 4– = 4,4′-dioxido-3,3′-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 ± 0.2 mmol/g (16 wt %) at 0.1 bar and 40 °C in the presence of a high partial pressure of H2O.尽管目前针对燃烧后碳捕获领域已研究了大量金属有机框架（metal–organic frameworks），但针对包含CO₂、N₂与H₂O这三种燃煤或天然气发电厂烟气最主要组分的混合气体吸附平衡的相关研究，此前尚未见公开报道。本研究开发并验证了一款高通量多组分吸附测试仪器，该仪器可在贴合发电厂实际烟气的工况条件下，测定混合气体的平衡吸附等温线。我们利用该仪器对15种不同的金属有机框架、沸石、介孔二氧化硅以及活性炭展开了研究，这些材料均为当前广受关注的CO₂捕获用固体吸附剂的典型代表。尽管本研究呈现的多组分吸附结果已提供了诸多颇具价值的基础科学见解，但仅有经烷基胺功能化的吸附剂，在N₂与H₂O共存、平衡分压接近碳捕获工艺预期工况的条件下，才展现出可观的CO₂吸附容量。尤为关键的是，经胺基修饰的金属有机框架mmen-Mg₂(dobpdc)（mmen = N,N′-二甲基乙二胺，dobpdc⁴⁻ = 4,4′-二氧代-3,3′-联苯二甲酸根），在0.1 bar、40 ℃且H₂O分压较高的工况下，展现出4.2 ± 0.2 mmol/g（16 wt%）的创纪录CO₂吸附容量。