INTERACTION OF HYDROGEN WITH NI/AL2O3 CATALYSTS

The interaction of hydrogen with Ni/Al2O3 catalysts was studied by temperature-programmed desorption (TPD) method. The examinations showed that hydrogen evolves due to: (i) desorption from metal, (ii) reoxidation of nickel with H2O molecules and -OH groups present in the catalysts, and (iii) desorption from alumina support. Contribution of hydrogen evolved due to the reoxidation and the desorption from support increases with the content of alumina and depends on pretreatment of the examined sample. After pre-reduction and pre-desorption of examined sample at high temperature, this contribution is small and TPD spectrum obtained for Ni/Al2O3 catalyst is similar to that recorded for unsupported nickel.