Modification of zsm-5 zeolite with trimethyl phosphite part 1. structure and acidity

In the present work we have studied the structure and the acidic properties of HZSM-5 zeolite modified with trimethyl phosphite. The modifications were carried out by using a chemical vapour deposition method as well as impregnation from n-octane solution. Both modification techniques resulted in ma...

Full description

Saved in:
Bibliographic Details
Published in:Microporous and mesoporous materials 1998-03, Vol.20 (4), p.363-369
Main Authors: Tynjälä, Pekka, Pakkanen, Tuula T.
Format: Article
Language:English
Subjects:
Chemistry
Exact sciences and technology
FTIR
General and physical chemistry
Ion-exchange
MAS NMR spectroscopy
Surface physical chemistry
TPD
Trimethyl phosphite
Zeolites: preparations and properties
ZSM-5
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In the present work we have studied the structure and the acidic properties of HZSM-5 zeolite modified with trimethyl phosphite. The modifications were carried out by using a chemical vapour deposition method as well as impregnation from n-octane solution. Both modification techniques resulted in materials with similar acidic properties. Trimethyl phosphite reacted with both Brönsted acid sites and terminal SiOH groups. The modifications resulted in the total elimination of strong Brönsted acid sites accompanied by the formation of new Brönsted type sites with decreased acid strength. However, the total acidity of the modified zeolites stayed relatively high. A possible structural transformation resulting from the phosphite modifications was proposed to be an insertion of phosphorus species between the structural aluminium- and silicon-oxygen tetrahedra. However, on the basis of 31P MAS NMR studies no evidence of the isomorphous substitution of structural T-atoms by phosphorus was found.
ISSN:1387-1811
1873-3093
DOI:10.1016/S1387-1811(97)00050-4