Crystallization in nonaqueous media of Co- and Mn-substituted microporous aluminophosphates investigated by in situ synchrotron X-ray powder diffraction

In situ synchrotron X-ray powder diffraction was used to investigate the cr ystallization of microporous transition metal-substituted aluminophosphates from nonaqueous media. The gels contained ethylene glycol and triethylamin e as the template and were heated in quartz glass capillaries at temperatur es up to 200 degrees C. The following crystalline products were formed: MnA PO-5, [AFI], CoAPO-5, [AFI], and AlPO4-5, [AFI]. Three nonaqueous systems w ere investigated in situ, where the crystallization of MAPO-5-type material s were followed. Solvothermal crystallization of MnAPO-5 and CoAPO-5 was st udied, and the effect of adding HF as a mineralizing agent was investigated . Time-resolved powder diffraction data were collected using a translating imaging plate (TIP) camera, and crystallization curves were extracted using integrated diffraction peaks. Kinetic analysis of the crystallization curv es was performed using an Avrami-type expression, alpha(t) = exp(-(kt)(n)). Apparent activation energies were determined from Arrhenius plots: MnAPO-5 , 94 kJ/mol; MnAPO-5(HF), 68 kJ/mol; CoAPO-5, 61 kJ/mol. Crystallization of CoAPO-5 is faster than for MnAPO-5, and the values for n obtained by fitti ng with the Avrami-type expression were significantly lower for CoAPO-5 tha n for MnAPO-5.