Redox chemistry of gaseous reactants inside photoexcited FeAlPO4 molecularsieve

The reactivity of ligand-to-metal charge transfer excited Fe centers of FeA lPO4-5 molecular sieve at the gas-micropore interface has been probed by in situ FT-IR spectroscopy. Laser light in the region 350-430 nm was used to excite the metal centers, and reaction was induced between methanol or 2-pr opanol and O-2 Acetone and H2O are the observed products of the 2-propanol + O-2 system, while the reaction of methanol with O-2 yields formic acid, m ethyl formate, and H2O as final products. These originate from secondary th ermal reaction of initially produced formaldehyde and hydrogen peroxide. Th e primary step of the proposed mechanism involves one-electron reduction of O-2 by transient Fe+II under concurrent donation of an electron to the hol e of framework oxygen by the alcohol molecule. The efficient reaction sugge sts that the photoreduced Fe center of the molecular sieve has a substantia lly stronger reducing power than the conduction band electrons of dense-pha se Fe2O3 semiconductor particles.