Methylamine synthesis over solid acid catalysts: Microcalorimetric and infrared spectroscopic studies of adsorbed species

Journal Article · Tue Mar 01 04:00:00 EST 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(94)90029-9· OSTI ID:6798998

Chen, D T; Zhang, L; Dumesic, J A ^[1]; Yi, Chen ^[2]

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1. Univ. of Wisconsin, Madison (United States)
2. Nanjing Univ. (China)

Microcalorimetry was used to determine the differential enthalpy changes of adsorption versus coverage on H-ZSM-5 and H-mordenite of reactants and products of methylamine synthesis. The enthalpy changes of adsorption of dimethylether, ammonia, monomethylamine, and dimethylamine on Bronsted acid sites vary linearly from -90 to -250 kJ/mol with the gaseous proton affinities of these basic molecules. The enthalpy changes of adsorption of water and methanol vary from -60 to -90 kJ/mol. In situ infrared spectroscopy indicates that methoxyl species are present on the catalyst in flowing methanol at temperatures near 600 K; however, adsorbed ammonia and methylamines are associated with the Bronsted acid sites in gas mixtures of methanol and ammonia typically used for methylamine synthesis at these temperatures. These results suggest that dimethylether formation from methanol may occur through surface methoxyl species, while methylamine synthesis most likely involves adsorbed ammonium cations. 41 refs., 10 figs., 1 tab.

• OSTI ID: 6798998
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Journal Issue: 1 Vol. 146:1; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ABSORPTION HEAT
ABSORPTION SPECTROSCOPY
AMINES
AMMONIA
BROENSTED ACIDS
CALORIMETRY
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL PREPARATION
ENERGY
ENTHALPY
ETHERS
HEAT
HETEROGENEOUS CATALYSIS
HYDRIDES
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
METHYLAMINE
MICROANALYSIS
MINERALS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SILICATE MINERALS
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
SYNTHESIS
THERMODYNAMIC PROPERTIES
ZEOLITES