MECHANISM OF THE THERMAL-DECOMPOSITION OF TETRAETHYLAMMONIUM IN ZEOLITE-BETA

The mechanism of the thermal decomposition of tetraethylammonium (TEA) in zeolite-beta has been investigated under air and argon atmosphere using a combined technique of thermogravimetric analysis and mass spectrometry. The nature of the volatile products and the characterization of the solid after each thermal phenomenon shows that all TEA species, occluded ion pairs and counteranions, decompose into triethylamine and ethylene in a single step, in the temperature range 200-350 degrees-C. The amine readsorbs on the acidic sites of the zeolite and, as the temperature is increased, decomposes into lighter amines by sequential Hofmann elimination reactions. Part of the ethylene also reacts with the acid sites yielding aliphatic and aromatic hydrocarbons. Complete desorption of the organic species from the structure requires a temperature higher than 500-degrees-C.