Synthesis of aluminophosphate molecular sieves with AFI topology substituted by alkaline earth metal and their application to solid acid catalysis

The isopropylation of benzene and biphenyl was examined over MAPO-5 by VPT method to characterize their acidic properties. Their catalytic activity decreases in the order: MgAPO-5 ≫ CaAPO-5 ⩾ SrAPO-5 ⩾ BaAPO-5; ≫ APO-5; moderate to good selectivity for 4,4′-DIPB was observed in the level of 50-70% for all MAPO-5. These catalytic properties support strongly the incorporation of alkaline earth metals in the AFI framework.