Synthesis and characterization of CoAPO-5, a cobalt-containing AlPO4-5

Abstract Samples of AlPO 4 -5, containing a partial substitution of Co(II) for Al(III), were prepared. The results clearly indicated that, as the level of Co(II) added increased, so did the amount of an impurity phase. At low levels of Co addition, the impurity phase was white and may largely be AlPO 4 -5. Above about 14 mole% of cobalt addition, an amorphous cobalt aluminum phosphate impurity phase was formed and increased in content until no crystallization was observed at a 35 mole% Co addition level. Addition of base (NH 4 OH, NaOH) resulted in increased impurity levels but promoted single crystal growth. Analytical, X-ray, ion exchange, thermogravimetric, and surface-area measurements indicated that only a portion of the cobalt substituted for aluminum, whereas some was present in the ion-exchange sites. The results further indicate that excess alumina is occluded in the CoAPO-5 channels.