THE EFFECT OF SODIUM POISONING ON ACID SITES IN ZSM-22 ZEOLITES

被引：10

作者：

BORADE, RB

ADNOT, A

KALIAGUINE, S

机构：

[1] UNIV LAVAL,DEPT CHEM ENGN,ST FOY G1K 7P4,QUEBEC,CANADA

[2] GRAPS,ST FOY G1K 7P4,QUEBEC,CANADA

来源：

ZEOLITES | 1992年 / 12卷 / 01期

关键词：

ZSM-22; ZEOLITES; NA POISONING; N1S OF PYRIDINE XPS LINES;

D O I：

10.1016/0144-2449(92)90014-G

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：

Acidic properties of NaHZSM-22 zeolites of various exchange degrees were studied by infrared and N1s X-ray photoelectron spectra of chemisorbed pyridine. Two kinds of Bronsted and one type of Lewis sites were detected in fully protonated ZSM-22 zeolite. The concentration of these two kinds of Bronsted acid sites and of Lewis acid sites were determined as a function of sodium content. For fully protonated ZSM-22 zeolite, it has been found that among the total acid sites about 30% are stronger Bronsted acid sites. Introduction of sodium ions into zeolites poisoned both weak and strong Bronsted acid sites simultaneously. Comparison of N1s XPS data with i.r. results allowed us to conclude that at an early stage of sodium poisoning surface Bronsted sites are poisoned preferentially to those in the bulk and that the relative rate of poisoning was higher for stronger Bronsted acid sites than for weak Bronsted acid sites.

引用

页码：76 / 80

页数：5

共 26 条

[1] ACTIVE-CENTERS OVER HZSM5 ZEOLITES .1. XYLENE ISOMERIZATION [J].