PALLADIUM COPPER-EXCHANGED Y-TYPE ZEOLITES - A TRUE HETEROGENEOUS WACKER CATALYST

Evidence is presented that faujasite-type zeolites with specific Si:Al framework ratios exchanged with Pd(NH3)4(2+) and Cu2+, catalyse the oxidation of ethylene into acetaldehyde, in exactly the same way as the homogeneous Wacker system [Pd(II) and Cu(II) in concentrated chloride solution]; the active centre is found to be a partially ammoniated Pd(II) ion, most probably Pd(II)(NH3)2, which itself belongs to an electron transfer chain consisting of the alkene reagent, the faujasite encaged Pd(II)/Pd0 and Cu(II)/Cu(I) redox couples and dioxygen.