The temperature programmed desorption of a basic molecule such as ammonia (NH3-TPD) is one of the most commonly used methods used for measuring the surface acidity of porous materials, such as zeolites, clays or mesoporous silica [19].
The results of Table 2 also present the density of surface acidic sites (surface acidity) and basic sites (surface basicity), which are obtained by normalizing to the sample surface area and measured from the NH3- and CO2-TPD peaks.
On the other hand, all catalysts have been characterised by classical methods: surface acidity has been measured by ammonia TPD and metallic particle size has been determined by hydrogen chemisorption, and the results compared to those of test reaction.
The surface acidity of the zeolite acid activated zeolite was determined by amine adsorption analysis.
To understand the distribution of surface acidity and strength of acid sites, a systematic study of NH3-TPD was undertaken.
The surface acidity of the catalysts was measured using temperature programmed desorption of ammonia (NH3-TPD) employing a BEL-CAT TPD analyzer with a TCD detector (BEL Japan Inc., Osaka, Japan).
Their supplied surface acidity could also be used in bi-functional enzymatic-acid catalysts.
W/ZnO catalysts exhibit surface acidity due to the presence of Lewis and Bronsted acidic sites related to W6+ species.
Modified alumina samples with rich Brönsted acid sites were prepared using different fluorine-containing compounds as surface acidity modifiers.
A noticeable increase in surface acidity of commercial activated carbon was usually caused by the presence of sulfuric acid.
