Modeling and performance evaluation of noncovalent supramolecular adsorbent for post-combustion CO2 capture across various emission sources

초록

Solid adsorbents provide a safer method for capturing CO2 while addressing the technical issues associated with liquid amine processes. This study evaluates a supramolecular cucurbit[6]uril-polyethylenimine/silica, which exhibits enhanced thermal and oxidative stability while preserving the reactivity of the amine groups. Binary adsorption isotherms for CO2 and H2O were established using the Langmuir and Brunauer-Emmett-Teller models, respectively. The calculated heats of adsorption based on these models were 75.9 kJ/mol for CO2, whereas H2O exhibited 66.4 and 49.1 kJ/mol for mono-and multilayer adsorption, respectively (average 57.7 kJ/mol). CO2 and H2O adsorption exhibited negligible mutual interference; this behavior is attributed to the cucurbit[6]uril structure, which prevents bicarbonate formation and stabilizes captured CO2 as ammonium carbamate. To verify industrial feasibility, 30 kg of the adsorbent was mass-produced and subsequently evaluated in a twin-bed bubbling fluidized bed system operated continuously for 80 h under simulated natural gas combined cycle and coal-fired power plant flue gas conditions. The experimental results showed stable performance and closely matched the model predictions. Furthermore, the developed models were used to predict the adsorbent performance across various emission sources. The optimal adsorption temperature varied with the source conditions, as energy efficiency is improved by adjusting the temperature to minimize the H2O/CO2 adsorption ratio. With heat integration, the estimated regeneration heat energies for the natural gas combined cycle, naphtha cracking center, coal-fired power plant, and cement plant were 4.17, 4.78, 3.65, and 2.46 GJ/ tCO2, respectively.

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