The Liquid Phase Heterogeneous Catalysis of the Ortho-Parahydrogen Conversion at Low Temperatures under Pressure

Abstract

The ortho-para conversion in liquid hydrogen was investigated for several commercially and laboratory prepared catalysts. The static method was used in these investigations with 25 cc of liquid hydrogen and approximately 33 cc of catalysts being used for each rate determination. The rate of ortho-para conversion was found to be approximately zero order for all these catalysts. For a series of chromic oxide or ferric oxide catalysts on an alumina carrier prepared in this laboratory it was found that the rate of conversion was first order with respect to the concentration of the catalyzing ion on the surface. The rate increase caused by substituting the ferric oxide for chromic oxide was proportional to the squares of the magnetic moments of the Fe⁺³ and Cr⁺³ ions. Chromia-alumina catalysts prepared in this laboratory containing 1 percent to 2 percent Cr₂O₃ were faster than commercial catalysts containing 20 percent to 35 percent Cr₂O₃.