How to evaluate hydrogen storage properties by Sieverts' method in the pressure range up to 100 MPa.

In order to develop suitable hydrogen storage materials for thermochemical hydrogen compressor using metal hydride, it is necessary to evaluate hydrogen storage properties in high pressure range up to 100 MPa. However, several unexpected issues arose for measuring P-C isotherms up to 100 MPa, which was not observed for the relatively lower pressure range. This led to strange shape of P-C isotherms. In order to solve these, in this paper, we considered the effect of the inner volume of the valve, the pressure increment by a valve operation, and the volume expansion of the sample upon hydrogen absorption. Taken into account these factors, reasonable P-C isotherms were successfully obtained. [Display omitted] • Pressure-composition isotherms were successfully drawn for pressures up to 100 MPa. • Valve volume needs to be considered otherwise the capacity is overestimated. • Valve closure causes a pressure increase that also affects the capacity calculation. • Sample expansion during hydrogenation affects hydrogen content calculations. [ABSTRACT FROM AUTHOR]