Thermal Decomposition of Organo-Ammonium Compounds Exchanged onto Montmorillonite and Hectorite

Abstract

Abstract-A series of organic ammonium ions were exchanged onto clay minerals montmorillonite and hectorite. Thermal effects on these surface modified organic-inorganic complexes were investigated by means of differential thermal analysis and heating-oscillating X-ray diffraction methods. It was found that the organo-clay complexes were dehydrogenated at temperatures from 180 to 350~ depending on the organic cation used. Following the dehydrogenation, hydrolysis took place leaving a layer of "carbon" on the clay surface. The "carbon" was then oxidized at a temperature of about 550~ Investigation of possible correlations between the activation energy of dehydrogenation and basicity, boiling point, ionization potential, molecular structure, and carbon-carbon bond distances of the organic cations showed that the geometric factors outweighed the acid, chemical and electronic factors in determining the effect of montmorillonite and hectorite toward the dehydrogenation of organic ions exchanged on the surfaces of these clay minerals.

Stability of n-Butylammonium Vermiculite in Powder and Flake Forms

“…Decomposition of adsorbed amines and alkylammonium-smectite complexes proceeds above 100 ~ as suggested by others (Weiss and Roloff 1963;Chaussidon and Calvet 1965;Chou and McAtee 1969;Durand et al 1972). De la Calle et al (1996) have studied the evolution upon heating of 1-ornithine and of benzylammonium-vermiculite complex.…”

Clay-Organic Molecule Interactions: Oxidation of Acetaldehyde by Montmorillonite in N2 Atmosphere at Room Temperature

“…Although the nature of this dehydrogenation reaction has not yet been understood, it seems to be highly dependent on the type and the amount of the organic compounds fixed on the clay surface. Chi Chou and McAtee (1969) proposed an oxidation reaction involving carbon and the evolved structural water of the clay in normal dehydroxylation process (500-700~ whilst interaction between the constitution hydroxyls of montmorillonite and ND3 above 200~ was reported by Mortland et al (1963). However, strong interaction between the adsorbate and lattice OH, leading to complete dehydroxylation of the clay surface is not known.…”

Mineralization of Carbon Dioxide: A Literature Review

“…The hydrophobic character of organoclay is preserved up to 300°C. Montmorillonite's activation energy for the dehydrogenation step is higher than hectorite's systems [86] and the hectorite structure slightly favors the hydrogenation step over the montmorillonite [74]. Carbon resulting from the hydrogenation separates the clay platelets enough to permit gas molecules to penetrate the interlayer region.…”