A Study on the Ortho-para Hydrogen Conversion Characteristics of Liquefied Hydrogen by Perovskite Catalysts

Abstract

>> During the liquefaction of hydrogen, the ortho hydrogen is converted into the para form with heat release that evaporates the liquefied hydrogen into the gaseous one backwards. The ortho-para conversion catalysts are usually used during liquefaction to avoid such boil-off. In order to compare and analyze the performance of the ortho-para hydrogen conversion catalysts, in-situ FT-IR device was designed and manufactured to measure the para hydrogen conversion rate in real-time. LaFeO3 and La0.7Sr0.3Cu0.3Fe0.7O3 perovskite catalysts were prepared by the citrate sol-gel method and their spin conversion characteristics from ortho to para hydrogen were investigated by in-situ FTIR spectroscopy at 17K. It was found that the spin conversion was affected by surface area, particle size, and crystallite size of the catalysts. Thus, the La0.7Sr0.3Cu0.3Fe0.7O3 perovskite catalyst that had higher surface area, higher crystallite size, and smaller particle size than LaFeO 3 showed the better spin conversion property of 32.3% at 17K in 120min interaction with the perovskite catalysts.