A NMR system for in situ analysis of hydrogen storage materials under high pressure and temperature conditions was developed. The system consists of a gas pressure and flow rate controlling unit, a temperature controller, a high temperature NMR probe tunable for both H1 and other nuclei, and a sample tube holder. Sample temperature can be controlled up to 623 K by heated N2 gas flow. Sample tube atmosphere can be substituted by either H2 or Ar and can be pressurized up to 1 MPa under constant flow rate up to 100 ml/min. During the NMR measurement, the pressure can be adjusted easily by just handle a back pressure valve. On the blank NMR measurement, 1H background noise was confirmed to be very low. 1H and 11B NMR spectrum of LiBH4 were successfully observed at high temperature for the demonstration of the system. The intensity of the 1H NMR spectra of H2 gas was also confirmed to be proportional to the applied pressure.
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