MA Wei, YANG Zhiping, GUO Cuiping, LI Yao
(Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: LTA (Na-A) zeolite has regular three-dimensional pore structure, high specific surface area and large pore volume, and high water-adsorption efficiency. Therefore, it is widely used in deep dehumidification in industry. Despite that, the regeneration temperature of LTA molecular sieve is normally higher than 200 ℃. As a consequence, reducing the desorption temperature of LTA molecular sieve is one of the major focuses for its functional optimization. LTA (Na-A) zeolites with mesopore-micropore hierarchical structure were prepared by using a step-by-step hydrothermal method. In addition, the effects of hydrothermal temperature on performance of the hierarchical porous zeolite were evaluated. It is found that, at hydrothermal temperature of 100 ℃, the synthesized LTA zeolites display promising crystallinity and stability. The water-adsorption capacity could reach 0.304 g·g−1 at 30 ℃. Meanwhile, TGA result indicates that desorption efficiency of the LTA zeolites is significantly improved, with 81% of the adsorbed water molecules than can be removed at 200 ℃, contrasting to 67% for the conventional Na-A zeolite.
Key words: dehumidification; hierarchical; LTA zeolite; step-by-step hydrothermal