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

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.