Promotion effect of al on MCM-41 supported strong solid acid materials

Al-promoted sulfated zirconia (SZ) was confined inside pure-silica MCM-41 (abbreviated as SZA/MCM-41). It was prepared by slurry impregnation followed by decomposition of the metal sulfate. The effects of aluminum on these samples were investigated by powder XRD, N₂ adsorption and DRIFT techniques in detail. The experimental results show that the ordered porous host structure is still maintained in the catalyst. Sulfated zirconia is in meta-stable tetragonal phase. The IR spectrum of the adsorbed pyridine showed that the amounts of Bronsted acid sited on the SZA/MCM-41 are improved comparing to SZ/MCM-41. The addition of aluminum can help the retention of sulfur species on the surface of the composites. Between SZ/MCM-41 and SZA/MCM-41, no significant changes in structural properties such as surface areas, pore volumes etc. can be found. In comparison to SZ/MCM-41 without aluminum, the catalytic activities of the Al-promoted catalysts are greatly improved. The best conversion is achieved when the catalyst is promoted by l.l% (wt) aluminum and calcined at 720°C.