Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9607948 | Applied Catalysis A: General | 2005 | 7 Pages |
Abstract
It has been shown that homogeneous thin films of silica heavily loaded with phosphotungstic acid (30Â wt.%) or Nafion (50Â wt.%) can be uniformly deposited on various substrates by a dip-coating to give effective structured catalysts with strong acidic properties. Experiments indicate that the use of well condensed silica sols, with over 75% of Qn population in the form of Q3 sites, is a precondition to obtain crack-free films and that the withdrawal speed plays a second order role, especially at lower viscosities. Based on the quality maps of the films prepared under various conditions we conclude that defect-free coatings can be obtained provided that sol viscosity is above the specific threshold value and still within a linear part of the viscosity dependence upon time.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Catalysis
Authors
L. WiÄcÅaw-Solny, A.B. JarzÄbski, J. Mrowiec-BiaÅoÅ, W. Turek, Z. Ujma, A. KudÅa, M. Gibas, J. Å»ak,