Stability studies on undoped and doped Mg2TiO4, obtained by the polymeric precursor method

A series of AlMCM-41 molecular sieves were synthesized starting from a hydrogel keeping the following molar composition: 1CTMABr:4.58SiO 2 :(0.437+ X )Na 2 O: X Al 2 O 3 :200H 2 O. Tetramethylammonium silicate (TMAS) was used as silicon source and cethyltrimethylammonium bromide (CTMABr) was used as structure template. The obtained materials were characterized by nitrogen adsorption, XRD and TG/DTG. Acid properties were determined by pyridine thermodesorption. Model-free and Flynn-Wall kinetic models were used in order to correlate the total acidity with the apparent activation energy of pyridine desorption.