Improved catalytic activity and stability of mesostructured sulfated zirconia by Al promoter

Al-promoted mesostructured sulfated zirconia (Al-MSZ-5) has been successfully synthesized from the template of triblock polymer surfactant (P123) in aqueous solution. Mesostructured Al-MSZ-5 shows high thermal stability, and it can preserve its characteristic mesostructures until calcination at 650°C. In contrast, the mesostructure of mesoporous sulfated zirconia (MSZ-5) will be destroyed during calcination at 600°C. Catalytic data for n-butane isomerization show that the Al-MSZ-5 exhibits higher catalytic activity and better stability than both MSZ-5 and conventional Al-promoted sulfated zirconia (Al-SZ). The Al-MSZ-5 sample was characterized by XRD, bright-field and dark-field TEM images, N₂ adsorption isotherms, NMR, TG-DTA, IR, and numerous other techniques. The results suggest that Al-MSZ-5 has worm-like mesopores, and that the mesostructured walls contain tetragonal crystalline ZrO₂. Such unique structural features might be responsible for the observed large surface area, high catalytic activity for n-butane isomerization, and high thermal stability of mesostructured Al-MSZ-5.