In situ synthesis of TiFSIX-3-Ni@ZIF-7@poly(acrylates) composite for CO2 capture from wet flue gas

TiFSIX-3-Ni, a hybridized ultra-microporous material, exhibiting a remarkable uptake for low concentration CO₂ adsorption under dry condition. However, its high degree of hydrophilicity results in notable decrease in CO₂ capture efficacy under wet flue gas. Moreover, the crystalline structure could be collapsed when exposure to water vapor during regeneration. To solve these problems, here we propose a TiFSIX-3-Ni@ZIF-7@poly(acrylates) composite, where the TiFSIX-3-Ni crystals grow in situ on the marcroporous surface of poly(acrylates) matrix, and each crystal is covered by a thin layer of hydrophobic ZIF-7, forming the confined ZIF-on-MOF structure. Apart from providing hydrophobic protection for the ZIF-on-MOF crystals, the poly(acrylates) skeleton also shapes the downsized crystals into the micrometer-sized spherical particles to avoid powder. At 40 °C and 90 % relative humidity (RH), the composite can maintain 88 % of its dry CO₂ adsorption uptake, and the adsorption time is 73 % of the unshaped TiFSIX-3-Ni powder. After 20 consecutive cycles, the CO₂ adsorption loss rate in a moist flue gas is found to be only 0.24 %, indicating that the TiFSIX-3-Ni@ZIF-7@poly(acrylates) composite is highly suitable for CO₂ adsorption from wet flue gas.