A comparative investigation on the catalytic activity of H-Al-MCM-48 and H-Zr-MCM-48 mesoporous molecular sieve on alkylation of phenol with tert-butyl alcohol

Abstract

Mesoporous H-Al (or Zr)-MCM-48 solid acid catalysts were prepared by wet impregnation method through using Al (or Zr)-MCM-48 mesoporous molecular sieves derived from conventional hydrothermal method as starting materials. These solid acid catalysts were characterized by XRD, TEM, NH3-TPD and N2 physical adsorption, respectively. The alkylation of phenol with tert-butyl alcohol was carried out over these solid acid catalysts. The effect of various factors including reactant molar ratio, weight hour space velocity (WHSV), reaction time and temperature on phenol conversion and product selectivity was investigated and the results were discussed. Experimental results reveal that the resulting solid acid catalysts still retained a typical cubic mesoporous framework of MCM-48. Under comparable conditions, the H-Al-MCM-48-25 catalyst exhibits much high catalytic activity and gives a maximum phenol conversion of 98.9% with 70.3% selectivity to 4-t-butyl phenol (4-TBP). The optimum reaction conditions over these solid acid catalysts are the following: WHSV=5h−1, time=2h, temperature=140°C, the molar ratio of tert-butyl alcohol:phenol=2:1.