Effect of the acid activation on a layered titanosilicate AM-4: the fine-tuning of structural and physicochemical properties

Abstract

In this work we investigated the microporous layered titanosilicate AM-4 (Aveiro-Manchester material number 4) of a synthetic analogous the mineral Lintisite having edge-shared brookite-type TiO6 chains. The objective of our work was to verify the effects of the acid activation on the AM-4 properties, treated with 0.0625–0.25 M HNO3. The results of the physicochemical characterization by SEM, XRD, IR and DR UV–vis spectroscopy, nitrogen adsorption/desorption at 77 K have provided evidences that texture, chemical composition, structural and physicochemical properties of AM-4 could be adjusted by treatment with 0.0625–0.25 M HNO3. According to the method of mass titration, surface acidity (pHPZC) of AM-4 roses with increasing HNO3 concentration, which was in accord with the increase of the reaction rate and yield of 1,5-benzodiazepine in the reaction of cyclocondansation between 1,2-phenylenediamine and acetone.