Acidity of aluminophosphate structures. Part 2.—Incorporation of cobalt into CHA and AFI by microwave synthesis

On the synthesis of vanadium containing molecular sieves by experimental design from a VOSO4·5H2O·Al(iPrO)3·Pr2NH·H2O gel: occurrence of VAPO-41 as a secondary structure in the synthesis of VAPO-11

“…5 together with the most important assignments. When the desorption temperature increases from room temperature to 523 K, the spectra change dramatically, especially in the region of the OH stretching vibrations [39], as expected if water is supposed to be desorbed. Even though the exact changes in the intensity of the template peaks appearing in the domains of symmetrical and asymmetrical stretching of C±H and N±H bonds, respectively, as well as in the domain of the deformation vibrations of the CH 3 , CH 2 and NH groups can be hardly appreciated due to changes in the overall baseline of the spectra, it is however obvious that the template is not desorbed till 473 K, but disappears almost totally at 573 K.…”

A Facile Synthesis of SAPO-34 Molecular Sieves with Microwave Irradiation in Wide Reaction Conditions

“…Moreover, SAPO-34, rather than SAPO-5, can be obtained selectively when the TEAOH and silica concentrations and the reaction temperature are high. The preferential formation of CHA molecular sieves, rather than AFI molecular sieves, has been observed in the presence of high concentration of heteroatoms like Mg 36 and Co. 38 Moreover, high pH also leads to CHA molecular sieves. 36,37 Because of a low stability of AFI (compared with CHA structure) in thermodynamics, due to large pore size 26,27 or low framework density, 39 AFI, rather than CHA, is selectively obtained in low temperatures and over shorter reaction times.…”

“…Changing other factors such as pH, temperature and silica concentration, even though very important for the synthesis of SAPO-34 under CE heating, [36][37][38] does not lead to the formation of the SAPO-34 phase. For example, even a condition of high basicity (pH of 9.7) and/or seeding of SAPO-34 crystals were not sufficient to produce a pure SAPO-34 molecular sieve when triethylamine was used as the templating molecule.…”

An Overview of Zeolite, Zeotype and Mesoporous Solids Chemistry: Design, Synthesis and Catalytic Properties

“…Cutting the reaction times short can, however, jeopardize the silica condensation process, leading to poorly polymerized products. Microwave heating overcomes this problem by speeding up the condensation step, allowing high quality products to form in times as short as 1 h at 150 C. [39][40][41][42] The resulting MCM-41 crystallites are very small (approximately 100 nm in diameter).…”