Lewis acid metal ion-exchanged MAPO-5 molecular sieves for solvent free synthesis of coumarin derivative

Magnesium aluminophosphate (MAPO-5) molecular sieve was synthesised hydrothermally and ion-exchanged with Lewis acid metal ions such as Ga3+, In3+, La3+ and Ce3+ by wet method. The materials were characterised using XRD, FT-IR, SEM, TPD (ammonia) and TGA. The XRD patterns of ion-exchanged molecular sieves are similar to the parent MAPO-5 thus showed absence of structural degradation and non-framework metal oxide phase during ion-exchange. The thermograms of metal ion-exchanged MAPO-5 showed a weight loss between 550 and 600 °C which is assigned to the decomposition of M(OH)2+ into MO+ species. The total acidity of materials decreased after ion-exchange as revealed from TPD (ammonia) studies. Their catalytic activity was tested in the solvent free synthesis of coumarin.