Dealumination of MOR Zeolites with Different Crystal Morphologies

The process of dealumination of mordenites differing in morphology and crystal size obtained under identical conditions from reaction mixtures of similar composition has been studied. Parameters that have been chosen to change the morphology and crystal size are the dry matter concentration in the r...

Full description

Saved in:
Bibliographic Details
Published in:Petroleum chemistry 2019-08, Vol.59 (8), p.860-869
Main Authors: Knyazeva, E. E., Nikiforov, A. I., Zasukhin, D. A., Rodionova, L. I., Ivanova, I. I.
Format: Article
Language:English
Subjects:
Aluminum
Chemistry
Chemistry and Materials Science
Crystal lattices
Crystal morphology
Crystallization
Crystals
Heat treatment
Industrial Chemistry/Chemical Engineering
Morphology
Needles
NMR
Nuclear magnetic resonance
Packing density
Silicon
Thickness
Zeolites
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:The process of dealumination of mordenites differing in morphology and crystal size obtained under identical conditions from reaction mixtures of similar composition has been studied. Parameters that have been chosen to change the morphology and crystal size are the dry matter concentration in the reaction mixture, the pH of the reaction mixture, the crystallization time, the presence of crystalline seeds, and agitation during the synthesis. Dealumination has been performed by heat treatment at 700°C followed by acid treatment. It has been shown that the stability of the mordenite crystal framework to dealumination depends on the thickness of the primary needle crystal, which forms the basis of large zeolite crystals, not on the size of the zeolite crystal as a whole. With a decrease in the average needle crystal thickness from 250 to 90 nm, the Si/Al molar ratio in the crystal lattice, determined from 29 Si NMR data, increases from 6.8 to 9.5. The dealumination is accompanied by a change in the texture of large mordenite crystals associated with a decrease in the packing density of the primary needles.
ISSN:0965-5441
1555-6239
DOI:10.1134/S0965544119080085