Selective formation of SAPO-5 and SAPO-34 molecular sieves with microwave irradiation and hydrothermal heating

SAPO-5 and SAPO-34 molecular sieves can be selectively formed with microwave irradiation and hydrothermal heating, respectively, of the same gel irrespective of the acidity or the type of the templates such as triethylamine and N,N,N',N'-tetraethylethylenediamine. The SAPO-5 structure may transform into the SAPO-34 structure with increase of crystallization time probably due to the relative stability of the two phases at the reaction conditions. Crystallization with microwave irradiation can be used as a phase selective synthesis method for unstable material because of fast crystallization. (C) 2003 Elsevier Inc. All rights reserved.