Changes in surface and catalytic dehydration activities of 2-propanol on AlPO-5 induced by silver impregnation

Abstract

Five samples of pure Al-Phosphates (ALPO-5) and silver oxide impregnated Al-Phosphates (wt.% of Ag=1.5–8.0) were prepared. The structural characterization was studied using X-ray diffraction (XRD) and FT-IR techniques. The textural properties (surface area end mean pore radius) were determined from N 2 adsorption at 77 K. Surface acidities of all prepared samples was estimated by nonaqueous titration of solid catalysts with n-butylamine using Hammett’s indicators. The catalytic conversion of 2-propanol at 300°C was also performed using microcatalytic pulse technique. Both XRD and FT-IR techniques give the characteristic ALPO-5 patterns only, whereas Ag 2O-AlPO-5 or silver-aluminium phosphate spinel were not be detected. The surface area, mean pore radius, surface acidity and catalytic activity were overall increased upon increasing the loading amounts of silver. Pure and silver impregnated aluminium phosphates show no dehydrogenation (DHG) activity. Impregnation with silver favors dehydration of 2-propanol to ether via intermolecular reaction which can proceed on weak acid sites.