Methods for accurate high-temperature Sieverts-type hydrogen measurements of metal hydrides

Improving Reproducibility in Hydrogen Storage Material Research

“…Potential causes of leakage include insufficient tightening of pressure fittings, contaminated valves, damaged pressure seals and valve seats, and hydrogen permeation through the walls of sample cells at elevated temperature (see, for example, Sheppard et al.). [78] Valves can become contaminated by fine powder, so samples must be secured in the sample cell or holder, to prevent contamination. Quartz wool can provide an effective barrier, to prevent powder particles contaminating the rest of the system, but valves can also be protected by commercially available sintered filter gaskets.…”

“…Hydrogen permeates through different grades of stainless steel (SS), for example, at significantly different rates,[ 79 , 80 ] although 316 L SS is standard for high pressure H 2 systems and is resistant to permeation up to relatively high temperatures. [78] Nevertheless, the source of any leakage must be investigated thoroughly. Removal and cleaning of components is sometimes necessary, prior to re‐testing a system and then using a process of elimination to achieve leak‐free operation.…”

Thermochemical energy storage performance of zinc destabilized calcium hydride at high-temperatures

“…H2 sorption properties were studied by Temperature Programmed Desorption (TPD), using a computer-controlled Sievert's apparatus. 35 CaH2-3Zn was heated to either 630 °C or 830 °C, with 5 °C/min heating rates. The powder mixture was placed inside a stainless-steel sample holder and then loaded into a silicon carbide (SiC) reactor.…”

“…H2 has a negligible hydrogen permeation through SiC at high temperatures (> 450 °C) and therefore was chosen as the most suitable reactor material for such measurements. [35][36] The sample temperature was measured using a K-type thermocouple which is kept inside the SiC reactor and direct contact with the sample. Pressure Composition Isotherm (PCI) measurements of CaH2-3Zn were conducted on the same apparatus to acquire the thermodynamic properties of the dehydrogenation reaction between 565 °C and 614 °C with a 1 bar pressure step size and a 3 h equilibration time per step.…”

Exploring halide destabilised calcium hydride as a high-temperature thermal battery

“…A frequent method applied to thermodynamically destabilising a metal hydride and to decompose it at lower temperatures is to substitute a hydrogen atom with a halide such as fluorine in its crystal structure [28,44]. Halide substitution using chlorine, bromine or iodine in calcium hydride has not been widely investigated, most likely due to the difficulties in measuring metal hydride compounds at high temperatures [45]. In 1956, Ehrlich et.…”