J. M. Smith

The low-temperature orthohydrogen conversion over supported oxides and metals

Abstract Rate data corrected for diffusion effects have been obtained for the orthohydrogen → parahydrogen conversion at −196 °C and up to 28.2 atm over alumina-supported oxides of copper, nickel, manganese, and terbium. Other catalysts used were alumina-supported copper, nickel, and palladium metals, and zirconia-supported terbium oxide. The supported nickel metal catalysts showed the highest activity; a sample prepared by multiple impregnation, and hence containing highly dispersed nickel, was 90 times more active than commercial 19% chromia-alumina used for comparison. In relation to atomic radius and magnetic moment, the supported nickel metal was over 103 times more active than the oxides. Possible reasons for this effect are explored. Evidence is presented to show that the low-temperature conversion on nickel metal probably does not involve dissociated hydrogen.