Synthesis and Characterization of a New Microporous Material. 2. AlPO and SAPO Forms of EMM-3

• Published in: Chemistry of materials 2006-03, Vol.18 (6), p.1705-1710
• Main Authors: Afeworki, Mobae, Kennedy, Gordon J, Dorset, Douglas L, Strohmaier, Karl G
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm052175j

A new aluminophosphate (AlPO) material, EMM-3, was recently synthesized at ExxonMobil. EMM-3, ExxonMobil material no. 3, was synthesized in both the AlPO- and SAPO-forms. The structure of the AlPO-form of EMM-3 has been solved using FOCUS Fourier recycling method with the help of a series of characterization techniques. Multinuclear, multifield solid-state NMR, SEM, and powder XRD measurements were performed in order to help understand the molecular arrangement and structure of the material. Carbon-13 CPMAS NMR of the as-synthesized material shows that the structure-directing agent remains intact with no strong chemical shift anisotropy indicating considerable mobility of the structure-directing agent in the internal voids of EMM-3. The multitechnique characterization of EMM-3 shows that only one type of crystal morphology is present, indicating the high purity of the sample. The XRD pattern of calcined-dry EMM-3 is consistent with orthorhombic symmetry. Distinct changes in local symmetry of the P and Al atoms occur upon calcination and subsequent hydration, and these changes are observed by solid-state NMR. Whereas the 31P MAS NMR of calcined-dry EMM-3 shows three peaks in a ratio of 1:2:3, upon rehydration, the 31P MAS NMR of EMM-3 shows that there are at least five distinct environments for the P atoms in a ratio of 1:2:1:1:1. The calcined-rehydrated sample shows a strong octahedral 27Al signal, due to framework hydration. SAPO-forms of EMM-3 were successfully synthesized and show acid activities. The Brønsted acidity was measured quantitatively by 1H MAS NMR.