Hierarchically porous aluminosilicates as the water vapor adsorbents for dehumidification

Abstract

Hierarchically porous aluminosilicates with large surface area (930–1010m2/g) and ordered hexagonal structureswere synthesized as the water vapor adsorbents for dehumidification in this work. Compared to the commercial microporous zeolite 3A (low Si/Al ratio), and mesoporous SILICA GEL (high Si/Al ratio), the synthesized aluminosilicates showed higher adsorption capacity of water vapor at both high and low humidity ranges. Different from zeolite 3A (type I) and silica gel (type III), the adsorption isotherms of aluminosilicates followed type IV isotherms. The aluminosilicate materials showed low desorption activation energy of water vapor (<20kJ/mol, close to the intermolecular H2O–H2O H-bonding interaction). The aluminosilicates showed a low desorption temperature of 87°C and a relatively fast desorption rate. Moreover, regenerability test in the multiple adsorption–desorption cycles suggested that the synthesized aluminosilicates were regenerable. With the promising dehumidification characteristics, including high adsorption capacity of water vapor, fast adsorption and desorption rates, low regeneration temperature, as well as good regenerability, the synthesized hierarchically porous aluminosilicates can be potential adsorbents for energy-efficient and cost-effective dehumidification process in practical applications, i.e. rotary desiccant dehumidifiers.