The CAL family of molecular sieves: Silicoaluminophosphates prepared from a layered aluminophosphate

[M]-CAL-2: MeAPSO-34-like molecular sieves using a lamellar aluminophosphate as precursor

“…The presence of the signals at about 1600 and 1500 cm −1 is related to the presence of the alkylammonium ion [27] these signals are attributed to the N-H bending at NH 3 + and their presence indicates that the amine is protonated and is present as counter-cation of the structural negative charges in the final materials [7]. A careful view of the crystals in Figure 5 showed that they have a lamellar appearance in some of their sides indicating that the precursor to final product formation occurs mainly due to a localized transformation and rearrangement of the lamellar aluminophosphate [8,28,29]. This feature may be extremely important for the use of these materials as catalysts since this lamellar memory effect may improve the diffusional processes and the active sites availability during the catalytic reactions.…”

“…The [M]-CAL-2 was prepared using a modified procedure as the one described in Patent Application for the CAL-2 molecular sieve synthesis [11]. Silica Aerosil 200 was used as silicon source, with SiO 2 /Al 2 O 3 molar ratio of 1.0.…”

“…However this road remained unexplored until the report of a layered aluminophosphate (AlPO-ntu) isostructural to the siliceous kanemite [7]. This lamellar aluminophosphate, herein designated as AlPO-kan, was then used as Al and P single-source in the synthesis of diverse SAPOs denominated as the CAL (acronym of CAmpinas-ALessandria) family molecular sieves [8]. After that, several SAPOs with different structures where obtained by varying the synthesis method always starting from AlPO-kan as precursor.…”

“…After that, several SAPOs with different structures where obtained by varying the synthesis method always starting from AlPO-kan as precursor. Chabazite (CHA) structures, analogous to SAPO-34, where obtained and named as CAL-1 [9,10] and CAL-2 [11];…”

“…Accurate studies of the acidic behavior of these materials were previously described by Pastore et al [8], and therefore their application, for example, in catalysis is restricted to the branch of acid catalysed reactions. The insertion of transition metals in T-positions in the framework could enlarge their application possibilities to redox catalytic reactions such as NO x decomposition [17] or H 2 and methane combustion.…”