The Characterization of Hydrocarbon Intermediates in H-ZSM-5

1987 ◽  
Vol 111 ◽  
Author(s):  
T. J. Gricus Kofke ◽  
R. J. Gorte ◽  
W. E. Farneth
Keyword(s):  
Infrared Spectroscopy ◽  
Thermogravimetric Analysis ◽  
Acid Site ◽  
Adsorbed Molecule ◽  
Temperature Programmed Desorption ◽  
Acid Sites ◽  
Adsorption State ◽  
Brönsted Acid ◽  
Temperature Programmed

AbstractWe have examined the adsorption of simple alcohols and 2-propanamine on H-ZSM-5 zeolites with Si/Al2 ratios between 38 and 520. Thermogravimetric analysis (TGA) demonstrated that most of the molecules display a clearly defined adsorption state corresponding to a coverage of one molecule per Al site. Temperature programmed desorption (TPD) and transmission infrared spectroscopy results for each of the molecules in this 1:1 adsorption state are consistent with adsorption being due to the transfer of a proton from the zeolite to the adsorbed molecule. These results provide additional evidence that carefully prepared H-ZSM-5 is a Bronsted acid, with one acid site per framework Al atom, in which all of the acid sites are identical in strength.

scholarly journals Liquid Phase Benzylation of Toluene over Modified Titania Catalysts

2012 ◽  
Vol 11 (2) ◽  
pp. 31-44
Author(s):  
Sunaja Devi K R ◽  
Sugunan S
Keyword(s):  
Liquid Phase ◽  
Lewis Acid ◽  
Benzyl Chloride ◽  
Sol Gel ◽  
Active Phase ◽  
Temperature Programmed Desorption ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Sulfated Titania ◽  
Temperature Programmed

Titania, sulfated titania and a series of iron loaded sulfated titania catalyst with different iron loadings (39 %) are prepared by sol-gel method and calcined at 500°C. Anatase is found to be the active phase with crystallite size in the nano range. All the prepared catalysts are found to be stable up to 700°C. Acidity is measured using spectrophotometric monitoring of adsorption of perylene, thermogravimetric desorption of 2,6-dimethylpyridine and temperature programmed desorption of ammonia. The activities of the catalysts were tested for liquid phase Friedel-Crafts benzylation of toluene with benzyl chloride. It has been concluded that Lewis acid sites are responsible for the reaction.

scholarly journals Thermal Transformation of Caffeic Acid on the Nanoceria Surface Studied by Temperature Programmed Desorption Mass-Spectrometry, Thermogravimetric Analysis and FT–IR Spectroscopy

2019 ◽  
Vol 3 (1) ◽  
pp. 34 ◽  
Author(s):  
Nataliia Nastasiienko ◽  
Borys Palianytsia ◽  
Mykola Kartel ◽  
Mats Larsson ◽  
Tetiana Kulik
Keyword(s):  
Mass Spectrometry ◽  
Thermogravimetric Analysis ◽  
Cerium Dioxide ◽  
Temperature Programmed Desorption ◽  
Hydroxyl Groups ◽  
Surface Complexes ◽  
Desorption Mass Spectrometry ◽  
Ft Ir ◽  
Temperature Programmed ◽  
Ft Ir Spectroscopy

The studies of pyrolysis of caffeic acid (CA) and its surface complexes is important for the development of technologies of heterogeneous catalytic pyrolysis of plant- and wood- based renewable biomass components. In this work, the structure and thermal transformations of the surface complexes of CA on the surface of nanoceria were investigated using Fourier transform–infrared (FT–IR) spectroscopy, thermogravimetric analysis (TGA) and temperature-programmed desorption mass spectrometry (TPD MS). It was found that CA on the surface of cerium dioxide forms several types of complexes: bidentate carboxylates, monodentate carboxylates and complexes formed as a result of interaction with phenolic hydroxyl groups. This is due to the ability of nanosized cerium dioxide to generate basic hydroxyl groups that can deprotonate phenolic groups to form phenolates on the surface. The main pyrolysis products were identified. The possible ways of forming 3,4-dihydroxyphenylethylene, acetylene carboxylic acid, pyrocatechol and phenol from surface complexes of CA were suggested. It was established that on the nanoceria surface effectively occur the decarboxylation, decarbonylation, and dehydration reactions of the CA, which are the desirable processes in biomass conversion technologies.

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