SBE type cobalt aluminophosphate nanoporous materials: Degradation of the structure-directing agent

The extent of detemplation of cobalt containing aluminophosphates (SBE; Co/Al = 1) was investigated. SBE powder crystals were obtained for the first time by extending the aging stage during synthesis. While X-ray powder diffraction data confirmed the presence of a rich Co-SBE phase, scanning electron microscopy images indicated that the crystal morphology was no longer a truncated hexahedron. Instead, the material displayed a hexagonal plate-like habit. Treatment in an oxidative atmosphere and vacuum, respectively, was used to study the removal of the structure-directing agent (SDA; 1,9-diaminononane). The former results in a “non-porous” framework as evidenced by low nitrogen uptake at 77 K. The latter treatment, however, resulted in a material with a surface area and unit cell cage diameter of ca. 320 m2/g and 9Å, respectively. From thermal gravimetric analyses, it was found that the SDA elimination proceeds in a traditional stepwise fashion. The first weight loss corresponding to the SDA elimination under inert (i.e., helium) conditions matches well with the predicted formation of alkene based on the theoretical unit cell data. Calcination in air at similar conditions results in only partial removal of the SDA followed by an immediate collapse of the framework, which correlates well with the sorption test results. UV–vis, Raman and FT-IR spectroscopy data confirmed that many of the original phase characteristics remained nearly unaffected after vacuum treatment. Oxidative calcination, however, results in the formation of extraframework cobalt formation. In general, this report represents the first step in releasing the theoretical catalytic and/or adsorption unique features of high-cobalt concentration porous with SBE-like frameworks.