On the Formation of AlPO₄-Based Molecular-Sieves in the Presence of Cyclohexylamine

Abstract

The hydrothermal synthesis of the AlPO₄-17, SAPO-44, MnAPSO-44 and intermediate solid phases [samples (APO)_N, (APSO)_N and Mn (APSO)_N] in the presence of cyclohexylamine (cha) is described. (APO)_N, (APSO)_N and Mn (APSO)_N represent unknown, layer-type, crystalline phases with different chemical compositions. These phases are predominantly formed at a high cha concentration and low crystallization temperature. All synthesized materials contain protonated cha in their structure, but only in AlPO₄-17, (APO)_N,(APSO)_N and Mn (APSO)_N is the -OH group also found. The calcination of the unknown phases leads to the loss of crystallinity and causes a complete breakdown of the crystal structure above 270°C.