ALUMINA-PILLARED ALPHA-ZIRCONIUM PHOSPHATE PREPARED BY IN-SITU POLYMERIZATION METHOD

Alumina-pillared alpha-zirconium phosphate with a surface area as high as 244 m(2)/g and thermal stability up to 823 K was prepared directly from an Al3+ solution by an in-situ polymerization method. The pillar ed materials were characterized by means of X-ray diffraction, thermog ravimetry-differential thermogravimetric analysis, Al-27 and P-31 magi c-angle spinning nuclear magnetic resonance spectroscopy and N-2 adsor ption methods, and compared with the analogous materials prepared by i ntercalation with Al-13(7+) clusters. A weaker interaction between the intercalated aluminum species and the phosphate layer upon heat treat ment is the main advantage of the in-situ polymerization method leadin g to an enhancement of the thermal stability and porosity of the pilla red materials. Temperature-programmed desorption of NH3 and infrared s pectra of pyridine chemisorption revealed that the pillared materials have more Bronsted acid sites than Lewis acid sites, and they display a high catalytic activity and selectivity for the dehydration of isopr opanol. (C) 1998 Elsevier Science B.V. All rights reserved.