TEXTURE AND STRUCTURE OF AMORPHOUS CO-PRECIPITATED SILICA-ALUMINUM PHOSPHATE CATALYST SUPPORTS

A series of co-precipitated silica-aluminum phosphate containing betwe en 0 and 100 mol% silica were synthesized by a coprecipitation techniq ue and characterized by various methods. X-ray fluorescence analysis s hows that the P/Al molar ratio in the solid mixture decreases as the s ilica content increases, whereas this ratio remains one in the solutio n. Nearly all these materials are shown to be meso- and macroporous. T he specific surface area decreases with increasing aluminum phosphate content, whereas the pore volume passes through a maximum at high sili ca content. Al-27, P-31, and Si-29 MAS-NMR spectra have also shown the existence of domains of silica and aluminum phosphate in binary suppo rts, but these domains are not larger than a few microns, as shown by EDS measurements. (C) 1998 Academic Press.