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Spin conversion of hydrogen over LaFeO3/Al2O3 catalysts at low temperature: Synthesis, characterization and activity

Das, Taraknath,Kweon, Soon-Cheol,Choi, Jeong-Gil,Kim, Seo Young,Oh, In-Hwan Elsevier 2015 International journal of hydrogen energy Vol.40 No.1
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Abstract A series of LaFeO3 perovskite catalysts over alumina support (LaFeO3/Al2O3) were prepared by citrate sol–gel method by changing the loading of LaFeO3 on alumina. The morphology and structure of perovskite catalysts were characterized by SEM, XRD, Raman spectroscopy, and the spin conversion of ortho hydrogen to para hydrogen was investigated by in situ FTIR spectroscopy at 17 K temperature. The spin conversion was primarily affected by the dispersion of perovskite phase over the support, the weight percent of LaFeO3 loading on alumina, and the ratio of lanthanum to iron in LaFeO3. The perovskite phase was formed at 1173 K, and less sintered and more dispersed at lower calcination temperatures. Thus, the highest spin conversion was observed for the perovskite catalyst calcined at 773 K with 20LaFeO3/Al2O3 and the 2:8 ratio of La to Fe (20La0.2Fe0.8O3/Al2O3), where 99.8% of ortho hydrogen at 17 K was converted into para hydrogen in 120 min interaction with the perovskite catalyst. Highlights <UL> <LI> Alumina supported LaFeO3 perovskite catalyst </LI> <LI> Low calcination temperature and alumina supported LaFeO3 perovskite phase </LI> <LI> The 20La0.2Fe0.8O3/Al2O3 perovskite oxide calcined at 773 K was the most active catalyst </LI> <LI> In situ FTIR spectroscopy for liquid phase ortho-para hydrogen spin conversion at very low temperature (17 K) </LI> </UL> Graphical abstract [DISPLAY OMISSION]
2
Spin conversion of hydrogen using supported iron catalysts at cryogenic temperature

Das, Taraknath,Kweon, Soon-Cheol,Nah, In Wook,Karng, Sarng Woo,Choi, Jeong-Gil,Oh, In-Hwan Elsevier 2015 Cryogenics Vol.69 No.-
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Abstract Alumina-supported iron oxides have been prepared by incipient wetness impregnation method and employed for orthohydrogen to parahydrogen spin conversion at cryogenic temperature. These materials were characterized using a series of characterization techniques such as SEM, XRD, Raman and in situ FTIR spectroscopy. The spin conversion was investigated at low temperature by a batch mode of operation. The in situ FTIR spectra were collected in a transmission mode to obtain the spin conversion. While the iron oxide was highly dispersed over alumina support at low loading percent, a rodlike crystallite of iron oxide was formed at high loading percent. The 10 and 20wt% iron oxides on alumina were proved to be the most active catalysts. The spin conversion process was very slow and time-dependent. It was concluded that the spin conversion was a function of various factors including the iron oxide loading percent, calcination temperature, and different supports. Highlights <UL> <LI> In situ FTIR spectroscopy for spin conversion of hydrogen. </LI> <LI> Ortho to para hydrogen spin conversion at cryogenic temperature. </LI> <LI> Supported iron oxide catalysts are active at low temperature. </LI> <LI> The most active catalyst was 10–20wt% iron oxide supported on alumina. </LI> </UL> Graphical abstract In situ FTIR system for the spin conversion of liquid phase orthohydrogen to parahydrogen. [DISPLAY OMISSION]
3
페로브스카이트 촉매에 의한 액화수소의 올소-파라 수소변환특성에 관한 연구

나인욱,김정현,Taraknath Das,권순철,오인환 한국수소및신에너지학회 2015 한국수소 및 신에너지학회논문집 Vol.26 No.1
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  ScienceON
  
  DBpia
During the liquefaction of hydrogen, the ortho hydrogen is converted into the para form with heatrelease that evaporates the liquefied hydrogen into the gaseous one backwards. The ortho-para conversion catalystsare usually used during liquefaction to avoid such boil-off. In order to compare and analyze the performance ofthe ortho-para hydrogen conversion catalysts, in-situ FT-IR device was designed and manufactured to measure thepara hydrogen conversion rate in real-time. LaFeO3 and La0.7Sr0.3Cu0.3Fe0.7O3 perovskite catalysts were preparedby the citrate sol-gel method and their spin conversion characteristics from ortho to para hydrogen were investigatedby in-situ FTIR spectroscopy at 17K. It was found that the spin conversion was affected by surface area, particlesize, and crystallite size of the catalysts. Thus, the La0.7Sr0.3Cu0.3Fe0.7O3 perovskite catalyst that had higher surfacearea, higher crystallite size, and smaller particle size than LaFeO3 showed the better spin conversion property of32.3% at 17K in 120min interaction with the perovskite catalysts.