Preparation of CaCl₂/MOF-303 composite and its dehumidification properties

A series of aluminium based Metal-Organic Framework (Al-MOF) composite adsorbents were prepared by impregnating moisture-sensitive CaCl₂ with different relative contents into Al-MOF (MOF-303). The composite adsorbents were characterized by adsorption isotherm of N₂, elemental analysis and scanning electron microscopy, and subjected to static and dynamic adsorption tests of water vapor, as well as cyclic adsorption and desorption tests. The results showed that with the addition of CaCl₂, the high surface area of MOF-303 granules (1276 m² g^-1) dropped sharply to 588-683 m² g^-1. However, under the synergistic effect of physical adsorption and chemical adsorption, the purification effects of the composite adsorbents were significantly better than those of unmodified MOF-303, molecular sieves, and silica gel. The adsorption performance was correlated with the impregnation amount of CaCl₂. As the CaCl₂ content increased, the saturation adsorption capacity and breakthrough adsorption capacity of the composite adsorbents all showed a trend of first increasing and subsequently decreasing. The maximum water adsorption capacity of the CaCl₂/MOF-303 composite was 1077 mg g^-1. In addition, the regenerative rate of the CaCl₂/MOF-303 composite was over 96.1% after fifty adsorption and desorption cycles of water, showing good desorption performance and excellent structural stability, which proved a broad application prospect in the field of dehumidification.