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

研究了L型沸石中铂小颗粒的成因及稳定性。在铂盐与沸石接触和最终铂颗粒形成之间发生的无机化学过程，采用程序升温还原法（TPR）进行了研究，随后观察了x射线吸收（化学位移和近边结构ıXANES!）和氢消耗；利用扩展的x射线吸收催化反应探针（新戊烷异构化和u-己烷芳构化）测定了TPR起始前、还原过程中和完全还原成铂金属后铂物种的结构，并利用x射线吸收研究了L沸石中小铂颗粒的不稳定性，包括颗粒生长、反应过程中烃类残留物失活、硫中毒和硫促进迁移。L型沸石中的铂是体积增长最快的催化剂之一。它在化学和石油工业中有宝贵的应用。它的主要用途是将重质原油升级为高倍频汽油，尽管它在化学合成和环境控制方面也有其他应用。

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.