Chemical and Physical Properties of the Al_(1-x)Fe_xPO_4 System Prepared by the Coprecipitation Method. II. Surface Acidity, Textural Properties and Catalytic Activity

摘要

A coprecipitation method for the preparation of Al_(1-x)Fe_xPO_4 catalysts with x (or Fe/P ratio) = 0.0, 0.2, 0.4, 0.6 and 0.8 was developed. The samples were calcined at temperatures within the range 200 - 800 ℃. The surface structure, cumulative acidity, textural properties, and the catalytic activity and selectivity of the prepared samples towards isopropanol and cyclohexane conversion were studied using different techniques. The results showed that the freshly calcined samples consisted of an amorphous phase, a quartz-type and a tridymite-type phase depending on the calcination temperature. The total surface acidity decreased with FePO_4 content or calcination temperature. Variations in the Fe/P ratio and the calcination temperature led to changes in both the surface area and total pore volume of the Al_(1-x)Fe_xPO_4 samples. Increases in the Fe/P ratio and increasing calcination temperature led to increases in the pore radius. The catalytic activity and selectivity were significantly affected as the structures of the Al_(1-x)Fe_xPO_4 catalysts varied. The kinetics of the reaction were also studied.