Alumina-pillared α-zirconium phosphate prepared by in-situ polymerization method

Abstract

Alumina-pillared α-zirconium phosphate with a surface area as high as 244 m2/g and thermal stability up to 823 K was prepared directly from an Al3+ solution by an in-situ polymerization method. The pillared materials were characterized by means of X-ray diffraction, thermogravimetry–differential thermogravimetric analysis, 27Al and 31P magic-angle spinning nuclear magnetic resonance spectroscopy and N2 adsorption methods, and compared with the analogous materials prepared by intercalation with Al7+13 clusters. A weaker interaction between the intercalated aluminum species and the phosphate layer upon heat treatment is the main advantage of the in-situ polymerization method leading to an enhancement of the thermal stability and porosity of the pillared materials. Temperature-programmed desorption of NH3 and infrared spectra of pyridine chemisorption revealed that the pillared materials have more Brønsted acid sites than Lewis acid sites, and they display a high catalytic activity and selectivity for the dehydration of isopropanol.