Properties and Catalytic Activity of Acid-Modified Montmorillonite and Vermiculite

Abstract

Abstract--The acidic properties of acid-modified montmorillonite and vermiculite were determined by pyridine and ammonia adsorption to correlate with the alkylating and dehydrating activity of the activated samples. Treatment of the minerals with different concentrations of hydrochloric acid results in the variation of overall acidity and density of acidic sites. Infrared (IR) spectral and differential scanning calorimetric analyses have revealed the presence of Bronsted and Lewis acid sites on the activated samples. The catalytic activity towards the above reaction has been correlated to the acid strength and density of Lewis acid sites. Treatment of montmorillonite with hydrochloric acid in the range of 0.1 and 0.3 M and vermiculite with 0.2 to 0.3 M seemed to be suitable for the conversion of methanol into olefin-rich hydrocarbons. Acid-activated montmorillonite catalyzed the isopropylation of benzene to a maximum extent of 16%, whereas acid-activated vermiculite gave a maximum conversion of only 4%.

Vermiculite: Structural Properties and Examples of the Use

“…Therefore, vermiculite has been successfully delaminated with acid treatment and used to mix with engineering polymer directly to synthesize polymer-vermiculite nanocomposites [129,130]. Acid delaminated vermiculite was successfully utilized for preparation of PVA nanocomposite.…”

Distinguishing Kaolinites and Smectite Clays from Central and Eastern Uganda Using Acidity, pH, Colour and Composition

“…Clay minerals have been shown to possess attractive properties as solid acids [13] [14] and these surface properties are associated with acidity brought about by Broensted and Lewis centres.…”

Estudo da adsorção de surfactante catiônico em uma matriz inorgânica preparada via óxido de nióbio

“…Os resultados de área superficial apresentados na literatura para alguns silicatos naturais, como a crisotila [26], montmorillonita, vermiculita [27] mostram-se concordantes com o resultado encontrado neste trabalho. O mesmo pode ser afirmado para algumas esmectitas sódicas sintéticas [28].…”