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Contribution of mass spectrometry to the determination of basic sites in solid catalysts
Author(s) -
Aramendía María Angeles,
Borau Victoriano,
Jiménez César,
Lafont Fernando,
Marinas José María,
Porras AndréS,
Urbano Francisco José
Publication year - 1995
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290090303
Subject(s) - chemistry , catalysis , titration , mass spectrometry , desorption , adsorption , analytical chemistry (journal) , benzoic acid , thermal desorption , thermal desorption spectroscopy , inorganic chemistry , chromatography , organic chemistry
This paper reports a new thermal programmed desorption–mass spectrometry (TPD‐MS) method for determining the number and relative strength distribution of basic sites in solid catalysts using CO 2 as titrant. The overall desorbed CO 2 area is proportional to the total basicity, while the number of peaks and their maximum temperature ( T max ) are related to the particular type of basic site and its strength. The activation energy for CO 2 desorption from various basic sites in each catalyst was calculated via TPD‐MS experiments conducted at a variable heating rate for each catalyst, using the Kissinger equation. Diffuse reflectance infrared analysis of the bands at 2000–1000 cm −1 for CO 2 adsorbed on various catalysts allows one to elucidate the nature of the chemical species involved, which depends on the particular type of site. The total basicity results obtained are compared with those provided by an existing spectrophotometric method using benzoic acid (p K a =4.19) as titrant.