Disclosing the thermal reactions of aliphatic amines in the presence of TiO2 nanoparticles by multi-shot analytical pyrolysis

Analytical pyrolysis is a powerful tool to study the thermal behaviour of organic compounds, but relatively little information is available on the pyrolysis of amines, especially when bound to inorganic systems. In this study, we analysed aliphatic amines (propylamine, dipropylamine, tripropylamine, and tert-butylamine), both as pure compounds and bound to titania nanoparticles, using multi-shot analytical pyrolysis-gas chromatography coupled to mass spectrometry (Py-GC-MS) with a liquid nitrogen cryo-trap system. Desorption of amines was observed at 260 degrees C, while pyrolysis reactions were mostly observed at 600 degrees C. Pure amines underwent intermolecular reactions, generating heavier nitrogen-containing compounds. Conversely, amines bound to titania nanoparticles underwent loss of ammonia and hydrogen, and both inter- and intramolecular couplings generate unsaturated hydrocarbons and aromatics. Differences in the pyrolysis mechanisms were attributed to the catalytic effect of the nanoparticles. The present work provides fundamental information on the pyrolytic behaviour of aliphatic amines and on the catalytic effect of titania nanoparticles.

Automated summary

Analytical pyrolysis is an effective tool to study the thermal behavior of organic compounds, however, there is limited information on the pyrolysis of amines, especially when bound to inorganic systems. This study found that pure amines generated heavier nitrogen-containing compounds, while amines bound to titania nanoparticles produced unsaturated hydrocarbons and aromatics. The differences in pyrolysis mechanisms were attributed to the catalytic effect of the nanoparticles.