At present, the separation of O2and N2from air is still extremely important. And it must be mentioned that the proportion of N2in air is much larger than that of O2(78% versus 21%), the O2-selective sorbents will be more efficient than N2-selective materials. Zeolite is one of the most common used adsorbents, which adsorbs N2selectively. Very few zeolites have been found that successfully achieved a higher O2uptake than N2by non-kinetic factors.
Recently, a research group led by Prof. XU Yunpeng and Prof. LIU Zhongminfrom the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences reported that the adsorption capacity of O2and N2on a LTA-type zeolite can besignificantly affected by the change of its Si/Al ratio. TheO2uptakeon protonated high-silica LTA zeoliteis higher than that of N2.
They found that the amounts of N2and O2adsorbed on LTA zeolite areclosely related to its Si/Al ratio. The adsorption isotherms at 298K indicated that N2uptakes decreased with the increase of Si/Al ratio, while the high-silica LTA had higher O2adsorption capacity than low-silica LTA, which had not been found in other zeolites. Through ion exchange and calcination, the proton-type high-silica LTA samples had been obtained and finally achieved O2-selective adsorption relative to N2(SO2/N2=1.32 at 100kPa). The DFT simulation results indicated that the binding ability of O2on high-silica LTA fragment was stronger than that of N2. These protonated high-silica LTA will show certain potential on O2-selective air separation.
This work, published inChemicalCommunicationson August 10, was supported by the National Natural ScienceFoundation of China. (Text by LIUHanbang)
Oxygen-selective adsorption on high-silica LTA zeolite. Hanbang Liu, Danhua Yuan, Guangye Liu, Jiacheng Xing, Zhongmin Liu, Yunpeng Xu*, Chem. Commun., 56(75):11130-11133, 2020.
