Efficient CO₂ capture by a directly synthesized molecular trapdoor adsorbent

Carbon capture represents a critical strategy for reducing greenhouse gas emissions and mitigating climate change. High-performance adsorbents with excellent CO 2 selectivity are essential for applications in post-combustion capture and natural gas purification. In this study, we report the synthesis of a high-purity silicon-based molecular trapdoor adsorbent (SBMTA) by hydrothermal and seed-guided methods. The CO 2 adsorption performance of SBMTA was thoroughly evaluated, and its selectivity toward CO 2 over N 2 and CH 4 was quantified using the Ideal Adsorption Solution Theory (IAST). At 333 K and 1 bar, SBMTA exhibits a CO 2 uptake of 1.4 mmol/g, with remarkable IAST selectivity values of 2555 for CO 2 /N 2 and 2291 for CO 2 /CH 4 . This is attributed to the trapdoor effect associated with K + within the molecular sieve. Dynamic binary gas breakthrough experiments were conducted to assess adsorption performance under varying temperatures, and cyclic separation efficiency was evaluated using a single-column three-step cycling process. At a gas flow rate of 0.15 L/min, with adsorption and desorption times of 70 s and 30 s respectively, the product gas purity reached 34.14% and a recovery rate of 86.71%. These results demonstrate that directly synthesized SBMTA holds great promise for efficient carbon dioxide capture from flue gas and natural gas streams.