A method is provided for the synthesis of aluminum-containing forms of molecular sieve CIT-15. The method includes treating an aluminogermanosilicate CIT-13 molecular sieve with water under conditions sufficient to degermanate at least a portion of the aluminogermanosilicate CIT-13 molecular sieve to provide a phyllosilicate comprising delaminated cfi-layers; and calcining the phyllosilicate under conditions sufficient to convert the phyllosilicate to an aluminogermanosilicate CIT-15 molecular sieve.