Transition Metals Modified ZSM-5 Molecular Sieve For Hydrogen Isotopes Separation And Analysis

With the approaching of energy crisis,nuclear fusion is currently considered to be one of the most promising sources for finally meeting mankind’s energy demand in future.In the process of nuclear fusion,the reaction of deuterium and tritium is mainly involved.Deuterium as an indispensable hydrogen isotope and low-abundance species of only 0.015%in nature,plays an important role in the scientific research of neutron scattering and non-radioactive isotope tracer,etc.Deuterium in nuclear fusion fuel can be completely recycled after separation and purification.Therefore,the separation of hydrogen isotopes is particularly important and urgent.Since tritium is radioactive,hydrogen and deuterium are often chosen as models to test the separation effect of hydrogen isotopes in scientific research.In recent years,based on quantum sieving,inorganic molecular sieves have attracted increasing interest in the research field of hydrogen isotope separation due to their uniform pore size distribution,excellent radiation resistance and low cost,and they have shown great potential in the separation process.In this thesis,several inorganic molecular sieves modified by transition metals were designed and synthesized,and their performances in hydrogen isotopes separation and analysis were studied.The specific work contents are as follows:1.The Na-ZSM-5 molecular sieve material（Si/Al=100）was obtained by a traditional hydrothermal synthesis method.The ion exchange strategy was selected to obtain a series of Fe/ZSM-5 zeolites and the separation performance of Fe/ZSM-5 was explored in H₂-D₂（50%:50%）binary mixture at the temperature of 20-50 K using cryogenic thermal desorption spectroscopy.The D₂/H₂ selectivity firstly increased,then decreased,and finally leveled off,with increasing iron content（D₂/H₂ selectivity of 33.9 was observed at 20 K for Fe/ZSM-5 with7 wt%Fe）.The location and coordination environment of trivalent iron species were identified for systematically tuning hydrogen isotopes affinity of Fe/ZSM-5.The separation mechanism of Fe/ZSM-5 for hydrogen isotopes was briefly discussed.2.Bimetallic copper and ferric irons were introduced into Na-ZSM-5 via ion exchange to form Cu/Fe-ZSM-5 zeolite（Cu/Fe ratio of 10）.The prepared Cu/Fe-ZSM-5 was utilized as stationary-phase material for gas chromatographic separation of hydrogen isotopes.As a result,the material as chromatographic stationary phase completed baseline separation of hydrogen-deuterium mixture with different ratios within 4 minutes under cryogenic conditions.The quantitative analysis accuracy of peak area and gas concentration was high（R²>0.999）.Additional study indicated that H₂-HD-D₂ ternary mixture could be completely separated on the stationary phase material（the separation factors of H₂/HD and HD-D₂ were1.34 and 2.23）within 5 minutes.Mechanistic study showed that copper divalent dominated the separation and iron species inhibited p-H₂ and o-H₂ splitting.