Element Substitution And Hydrogen Purification Performance Of ZrMnFe Alloy

High-purity hydrogen is crucial to the manufacture of advanced materials and products in the electronics industry,hydrogen energy applications,and fine chemical industries.The getter has the advantages of high hydrogen purity(99.9999%),simple operation,and low material cost when obtaining high-purity hydrogen.However,the commonly used ZrMnFe alloy has a methane reaction temperature in hydrogen gas higher than 600℃.The excessively high reaction temperature requires higher heating components for the purifier,and leads to poor safety at the same time.The current research mainly focuses on the adsorption performance test of constant impurities in helium,but there is a lack of research on the removal effect of ppm level methane in hydrogen.The methane capacity of the alloy needs to be further improved.In this study,the method of partial substitution of elements was used to modify the ZrMnFe alloy.The alloys were prepared by suspension induction melting,and their phase structures,compositions,and microstructures were systematically analyzed by XRD,ICP,carbon content analysis and SEM.The purification performances of the alloys for hydrogen gas containing 10 ppm methane were tested,and the effects of temperature,pressure,and gas flow rate on the purification performances were investigated.The catalytic effect of the substituted elements was verified using helium gas containing 50 ppm methane,and the methane adsorption capacities of the alloys was measured using hydrogen gas containing 1%methane.On the A side,Ni and Co,which have catalytic effects on CH4 cracking,were partially substituted for Fe in the alloy,with a substitution amount of 0 to 0.4.The alloys maintained a ZrMn2 single-phase structure.In the test of hydrogen purification performance,the performances of the alloys with Ni substitution were better than that of the Co substitution series.The hydrogen purification effects are directly proportional to temperature and inversely proportional to inlet pressure and outlet gas flow rate.The optimal alloy composition was optimized as ZrMnFe0.7Ni0.3.At 450℃,it could adsorb 10 ppm methane in hydrogen gas to 0.124 ppm.SEM results showed that after partial substitution of Fe by Ni and Co,the particle sizes significantly decreased,exposing more active surfaces,which were conducive to the reaction between the alloys and methane.XPS results showed that the electron-rich Ni and Co were more conducive to the activation of methane C-H bond breaking.Excluding the influence of hydrogen on methane removal performance,the purification performance tests were carried out with helium containing 50 ppm CH4.At 450℃,The purification columns of ZrMnFe0.7Ni0.3 and ZrMnFe0.7Co0.3 alloys could both adsorb methane to below the chromatographic detection limit(<0.01 ppm),while the ZrMnFe purification column could only adsorb methane to 0.4 ppm.On the B side,Zr is partially substituted with Ti,which is more likely to form metal carbides with C.Substituting Ti for Zr significantly improved the methane adsorption performances at low temperatures.The optimized alloy composition is Ti0.2Zr0.8MnFe0.7Ni0.3.This alloy could adsorb 10 ppm CH4 in H2 to 0.052 ppm at 450℃,and the methane adsorption capacity is 31.133 scc/g.During the reaction,methane was decomposed into elemental carbon and hydrogen under the catalytic effect of Ni and Fe.The elemental carbon diffuses inward and forms TiC with Ti.