AMORPHOUS ALUMINUM PHOSPHATE GELS

Amorphous aluminum phosphate gels have been synthesized which have structures analogous to amorphous silica gels. Crystalline aluminum phosphates are known to have structures isomorphous with most SiO2 Structures and therefore the similarity of amorphous material was anticipated. In the present work, amorphous aluminum phosphate gels have been prepared with a P/Al atomic ratio of approximately 1 with higher pore volume and pore diameter than previously reported, making them more suitable for certain catalyst support and adsorbent applications. Maintenance of a P/Al atomic ratio of approximately 1 was done with the intention of synthesizing a uniform AlPO4 phase rather than a mixture of discrete AlPO4, Al2O3 and P2O5 regions. Surface areas ranging from 250-350 m2/g were routinely obtained in conjunction with pore volumes from 0.4-1.8 cc/g. Surface chemistry was studied by NMR and ESCA techniques. Uses of the amorphous aluminum phosphate gels as ethylene polymerization catalysts and adsorbents are described.