PHYSICAL CONVERSION OF H-2 ADSORBED ON CR2O3 AL2O3/

The magnetic interaction of a hydrogen molecule physisorbed on a chrom ia/ alumina catalyst is presented and the influence of the Cr3d dangli ng bond on the ortho-para hydrogen conversion stressed. The Wigner pro cess, which assumes catalyst point dipoles, is analyzed and compared t o the magnetic dipolar process which includes the orbital degrees of f reedom of the surface electrons. The surface-molecule distance depende nces of the investigated processes are compared and the relative effic iencies of the different surface orbitals stressed. The conversion rat e is found to be increased by a factor of between 2 and 9, as compared to the original Wigner theory.