Performance characterization and comparison study of silver molecular sieve hydrogen adsorbents in liquid hydrogen vessels

Abstract

Four commercially available silver molecular sieve (SMS) hydrogen adsorbents were tested and characterized in terms of both material characterization and hydrogen adsorption performance, and an attempt was made to establish the constitutive relationship between material structure and hydrogen adsorption. The results show that the four SMS products have an average Ag content between 33 and 36 wt%, with the SBET between 200 and 400 m2/g and the cumulative hydrogen adsorption capacity in the range of 10–20 cm3(STP)/g. The two SMS products with the best hydrogen adsorption performance can replace or even surpass PdO in the vacuum interlayer of liquid hydrogen vessels. Their hydrogen adsorption capacity at an equilibrium pressure of 2 × 10−2 to 10 Pa is about two orders of magnitude greater than that of PdO. The constitutive relationship between material characterization and hydrogen adsorption performance suggests that the realization of new efficient SMS hydrogen adsorbents requires micro-mesoporous composite molecular sieves with large specific surface area and pore volume, and further improvements in the silver ions exchange process to load more silver ions into the internal pores of the molecular sieve microspheres.