Rapid synthesis of MOF CaBTC using an ultrasonic irradiation method and its derivative materials for CO2 capture†

Abstract

Ca-based MOFs and related derived materials offer promising potential for CO₂ capture. In this study, we synthesized a CaBTC MOF and polydopamine coated MOF composite by using an ultrasonic irradiation method, and a corresponding derivative was obtained by thermal treatment. The capacity of CO₂ capture and subsequent adsorption performance of the resulting CaBTC MOF/MOF derivative under different temperatures were investigated in detail. The structural features and textural parameters of the obtained absorbents were assessed by XRD, SEM, EDS, FT-IR spectroscopy, Raman spectroscopy, XPS, TG-DSC, and N₂ absorption/desorption characterization. The results demonstrated that the prepared CaO/CN-x with basic functional groups exhibited micro/mesoporosity derived from organic matter removal through carbonization at 800 °C. Both of these properties accounted for the highest CO₂ capacity of 2.30 mmol g⁻¹ at 273 K using pure CO₂ for the CaO/CN-5 sample. Additionally, we found that the derivative of the CaBTC MOF at high temperatures experienced two stages of chemical adsorption, as well as carbonation reaction. The high CO₂ capture capacity reached 60.2 mass% in 10 min at 873 K for the CaO sample. Furthermore, the introduction of carbon components derived from organic matter in the CaBTC MOF derivative matrix promoted the conversion of CO₂ to CO through the reduction reaction. Possible reaction mechanisms for the conversion of CO₂ to CO were preliminary proposed based on thermodynamic calculation.