The Study of Platinum Particle Genesis and Stabilization in L-Zeolite

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The genesis and stabilization of small platinum particles in zeolite L are being investigated. The inorganic chemistry that occurs between the time that the platinum salt is placed in contact with the zeolite and the formation of the final platinum particle is investigated using temperature-programmed reduction (TPR) followed by observations of X-ray absorption (chemical shift and near-edge structure ıXANES!) and hydrogen consumption; the structures of the platinum species before initiation of TPR, at stages during, and after complete reduction to platinum metal determined by extended X-ray absorption catalytic reaction probes (neopentane isomerization and u-hexane aromatization), and X-ray absorption are used to investigate destabilization of small platinum particles in zeolite L, including particle growth, deactivation by hydrocarbon residue during reaction, sulfur poisoning, and sulfur-promoted migration. Platinum in zeolite L is one of the fastest-growing catalysts in volume. It has valuable applications in the chemical and petroleum industries. Its principal use is in the upgrading of heavy crudes to high-octave gasoline, although it has other applications in chemical synthesis and environmental control as well.