Boosted surface acidity in TiO2 and Al2O3-TiO2 nanotubes as catalytic supports

•Surface acidity of NTs was modified by adding alumina.•Brönsted acid sites remain constant but Lewis acid sites are increased remarkably.•IR characterization by lutidine and pyridine confirms the surface acidity of NTs.•98% of NO conversion was reached between 380 and 480°C on NT-5Al.•The boosted s...

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Bibliographic Details
Published in:Applied surface science 2015-11, Vol.356, p.115-123
Main Authors: Camposeco, R., Castillo, S., Mejía-Centeno, Isidro, Navarrete, J., Nava, N.
Format: Article
Language:English
Subjects:
Aluminum oxide
Lewis acid
Nanotubes
New technology
SCR-NH3-Process
Surface chemistry
Titanates
Titania acidity
Titania nanotubes
Titania-Alumina nanotubes
Titanium dioxide
Transmission electron microscopy
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Summary:•Surface acidity of NTs was modified by adding alumina.•Brönsted acid sites remain constant but Lewis acid sites are increased remarkably.•IR characterization by lutidine and pyridine confirms the surface acidity of NTs.•98% of NO conversion was reached between 380 and 480°C on NT-5Al.•The boosted surface acidity of NT-Al improves the catalytic activity for SCR-NO. In this study, titanate nanotubes (NT) and titanate nanotubes with alumina (NT-Al) were studied as solid acid catalytic supports to show the relationship between the kind of acidity and catalytic activity. The supports were characterized by XRD, TEM, FTIR, XPS, and tested in the SCR-NO with NH3. It was found that the amount of Brönsted acid sites was maintained and the Lewis acid sites were significantly affected by the addition of alumina (1, 3, 5 and 10wt.%); such acidity was higher than that of the titanate nanotubes (NT) by two-fold. To confirm the formation of titanate nanotubes and titanate nanotubes with alumina, transmission electron microscopy (TEM) was used. X-ray diffraction (XRD) revealed the formation of the H2Ti4O9·H2O phase. All NT and NT-Al supports presented catalytic activity to remove NO with NH3 under lean conditions, confirming the presence of an important amount of Brönsted and Lewis acid sites in both NT and NT-Al supports.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2015.08.026