Demonstrating the benefits and pitfalls of various acidity characterization techniques by a case study on bimodal aluminosilicates.
A new combination of a volumetric with a dynamic method to investigate the acidity properties of aluminosilicates is introduced. In the first step, the total acidity is determined volumetrically by the measurement of two-cycle adsorption (TCA) isotherms with ammonia as a probe, directly followed by a dynamic temperature-programmed desorption (TPD) experiment to define the acid strength distribution. Furthermore, the results obtained by the new direct combination of TCA and TPD are validated by comparison with an in-situ FTIR (Fourier transform infrared) study with the same probe molecule on the same materials. Both acidity characterization techniques are compared, and we comment on their complementarity, benefits, and pitfalls. The material under investigation is a new type of bimodal microporous and mesoporous material with zeolitic characteristics, synthesized by a mesotemplate-free method. The acidic nature of the novel material is compared to two reference materials: a crystalline zeolite and a mesoporous aluminum incorporated mesocellular foam (Al-MCF) with amorphous characteristics.
Laboratory of Adsorption and Catalysis, Department of Chemistry, University of Antwerpen, CDE , Universiteitsplein 1, 2610 Wilrijk, Belgium.
Cynthia J
CJ
Van Oers
Kinga
K
Góra-Marek
Bénédicte
B
Prelot
Jerzy
J
Datka
Vera
V
Meynen
Pegie
P
Cool