DIRECT AND INDIRECT PROMOTION OF PD/Y BY CA-2+ IONS

Palladium in NaY or CaY zeolites was tested as a catalyst for hydrocarbon conversion reactions, including ring opening and ring enlargement of methylcyclopentane (MCP) and isomerization and hydrogenolysis of 2,2 dimethylpropane (neopentane). As protons are formed during reduction of Pd2+ ions with hydrogen, the catalysts were also tested after neutralization of these protons by reaction with sodium azide. The results suggest a direct interaction of the charge compensating ions (Ca2+ or Na+) with palladium particles and an indirect effect viz. by affecting the concentration of electron-deficient palladium-proton-adducts. In NaY the Pd2+ ions migrate to sodalite cages prior to their reduction, but in CaY they remain in the supercages, as has been previously shown. This leads to a higher concentration of [Pd(n)H]+ adducts in supercages of CaY than in NaY after reduction.