Preparation of macroporous SAPO-34 microspheres by a spray drying method using polystyrene spheres as hard template

Macroporous microspheres of SAPO-34 (MAMISAPO-34) were fabricated using polystyrene spheres (PS, 2 μm) as hard template. Cubic SAPO-34 (1 μm) synthesized by the conventional hydrothermal method was mixed with kaolin, silica sol, aluminium phosphate sol, template, and deionized water. Spray drying was then performed to prepare 30–50 μm microspheres which were converted to macroporous SAPO-34 by post-hydrothermal and calcination treatments. For comparison, 30–50 μm non-macroporous microspheres (NOMISAPO-34) were also obtained without using PS. XRD, NH₃-TPD, and SEM analyses were used to characterize the macroporous and non-macroporous SAPO-34. The results showed that MAMISAPO-34 was more crystalline and had more strong acid sites than NOMISAPO-34. When used in MTO (methanol to olefins) reactions, MAMISAPO-34 had better catalytic performance than NOMISAPO-34, because of its greater crystallinity.