Effect of Metal Dispersity on the Activity of Zeolite Catalysts Containing Transition Metals

摘要: Publisher Summary This chapter discusses how the dispersity of metal particles on catalytic activity affects reaction toluene disproportionation nickel–zeolite catalysts. The latter are obtained by ion exchange (NiCaY and their mixed forms—CrNiCaY PbNiCaY) deposition (NiO/CaY) or mechanical mixing constituents (NiO+CaY). changes in zeolite intracristalline structure followed change size unit cell (X-ray data). parameter average nickel determined air-dry state, reduced state maximal activity, after deactivation. X-ray date for samples different states provides information with respect to taking place during Ni(II) reduction, mutual effects between cations framework possible interaction active sites substrate. study nickel—containing samples—reveals that when is metallic only surface, dealkylation takes catalyst soon deactivated. When ions present (NiCaY), major part them nickel, which partially migrates agglomerates surface as crystallites, sized about 300–500 Ǻ remains intracrystalline structure.