Sorption properties of novel-fashioned low-cost hydrogen getters in a high-vacuum-multilayer insulation structure

Abstract

In a high-vacuum-multilayer insulation structure (HVMLIS), H2 is released into the vacuum jacket by manufactured materials, resulting in the deterioration of the insulation vacuum. Palladium oxide (PdO), which is expensive, is typically used as an H2 getter in HVMLIS. However, PdO generates sparks by vigorously reacting with H2, which are a potential threat to HVMLIS. Therefore, in this work, silver-exchanged zeolite is optimised to obtain an inexpensive and safe Ag–Z getter and a silver molecular sieve (SMS) together with a low-temperature active material getter (AMG). Moreover, an experimental platform was designed to test the H2 sorption properties of the three getters and compare them with traditional PdO. The experiment revealed that the cumulative sorption capacities of PdO, Ag–Z, SMS and AMG were 184.8, 63.1, 124.9 and 5.28 mL/g, respectively. However, the costs of SMS, Ag–Z and AMG were only ~7.37%, 5.08% and 6.13% of the cost of PdO, respectively, indicating that SMS is a promising alternative to PdO, which is expensive. Simultaneously, the microstructure of the H2 getters was analysed via X-ray powder diffraction. Further, PdH0.706 and Pd2H1.5 were obtained in addition to Pd, after H2 was absorbed by PdO. Ag+ was reduced to Ag in SMS, and Cu8O was produced by the reaction of CuO in AMG. These findings provide a basis for the subsequent optimisation of the H2 getters.