Small pore aluminum phosphate molecular sieves with chabazite structure: Incorporation of manganese in the structures -34 and -44

MnAPO and MnSAPO (APO = aluminum phosphate; SAPO = silicoaluminophosphate) with -34 and -44 framework structures have been synthesized. Rapid synthesis of MnAPO-34 could be achieved using morpholine as the template that subsequently changes to MnAPO-20 during synthesis. The presence of manganese in the framework has been established by a number of experimental techniques. ESR spectra of the low manganese containing samples were better resolved, and by comparison of these with the ESR of Mn2+-exchanged samples, it was possible to conclude that Mn2+ was present in the framework of the MnSAPOs. The nature of the silicon site depended on the manganese content of the sample as seen from Si-29 MASNMR. With higher manganese content, more silica-rich regions next to SAPO domains in the framework were formed. In MnAPO-44, a complete ordering of the T atoms appeared to have been achieved with every P atom being surrounded by three Al and one Mn. DTA-TG, infrared, and UV-visible spectra of the samples will be discussed.