Template-free synthesis of AlPO4-H1,-H2, and-H3 by microwave heating

Aluminophosphate molecular sieves (AlPO4's) were prepared by microwave heating without using organic template reagents. The microwave heating enhanced the crystallization of aluminophosphate gels, and AlPO4-H1, -H2(AHT), and -H3(APC) were successfully obtained as single phases in a relatively short reaction time. The reaction conditions used for the crystallization of the three kinds of AlPO4's were very similar to each other, but the use of different aluminum sources resulted in different structures; amorphous aluminum hydroxide, gibbsite, and boehmite were used for the preparation of AlPO4-H1, -H2, and -H3, respectively. The crystallization temperatures were 125, 118, and 90 degreesC, respectively. The addition of hydrochloric acid was needed for the crystallization of AlPO4-H1 and -H2. The addition of seed crystals and stirring the gels were found to be essential for the crystallization of AlPO4-H3. Nitrogen and water adsorption properties were also measured. (C) 2002 Elsevier Science Inc. All rights reserved.