XPS STUDY ON THE EFFECTS OF TREATMENTS ON PT2+ AND CO2+ EXCHANGED INTO NAY ZEOLITE

被引:45
作者
ZSOLDOS, Z [1 ]
VASS, G [1 ]
LU, GN [1 ]
GUCZI, L [1 ]
机构
[1] HUNGARIAN ACAD SCI,INST ISOTOPES,DEPT SURFACE CHEM & CATALYSIS,POB 77,H-1525 BUDAPEST,HUNGARY
关键词
D O I
10.1016/0169-4332(94)90070-1
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
X-ray photoelectron spectroscopy was applied to investigate Pt/NaY, Co/NaY and Pt-Co/NaY zeolites prepared by ion exchange (IE) and impregnation (IM). Changes in the electronic states and surface distribution of sodium and silicon were followed in NaY and in Pt and Co containing NaY in the as prepared (AP), calcined (OX) and reduced (RE) states. Decoration of the zeolite surface by alumina detected, is attributed to the local processes during ion exchange. Introduction of Co2+ ions into the Pt-containing samples influences the electronic states of platinum both in calcined and reduced state. Pt-degrees facilitates reduction of Co2+ ions and formation of bimetallic Pt-Co particles within the zeolite supercages could also be evidenced. The results support earlier TPR measurements indicating the presence of very small Pt-Co bimetallic particles for (IE) samples. On the other hand, in the impregnated NaY no sodium exchange occurs and the transition-metal species are located at the external surface of NaY zeolites.
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收藏
页码:467 / 475
页数:9
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