EFFECT OF ZEOLITE PROTONS ON PALLADIUM-CATALYZED HYDROCARBON REACTIONS

Catalytic superactivity of electron-deficient palladium for neopentane conversion, previously reported for Pd/Al2O3, has been verified for Pd/NaHY. The reaction rate, per accessible Pd atom, correlates with the proton content of the catalysts; for samples that contain all the protons generated during H2 reduction of Pd, it is two orders of magnitude higher than that for Pd/SiO2. Samples prepared by reduction of Pd(NH3)22+NaY display an intermediate activity. It is suggested that Pd-proton adducts are highly active sites in neopentane conversion. With methylcyclopentane as a catalytic probe, all Pd/NaHY samples deactivate rapidly and coke is deposited. Temperature-programmed oxidation reveals two types of coke, one of which correlates with the proton concentration in the catalyst. © 1990.