Immobilization of cobalt phthalocyanine and tetrasulfophthalocyanine onto MCM-41 and MCM-48: effect of immobilization method on catalytic activity

Cobalt tetrasulfophthalocyanine (CoPcS) was chemically anchored to amine-modified MCM-41 and MCM-48 surface. These mesoporous silica were prepared by hydrothermal procedure. Physical mixtures of CoPc in MCM-41 and in MCM-48 were also prepared for comparison purposes. The four prepared catalysts, 10 wt.% CoPcS/NH2-MCM-41, 10 wt.% CoPcS/NH2-MCM-48, 10 wt.% CoPc/MCM-41 and 10 wt.% CoPc/MCM-48, were characterized by X-ray diffractometry (XRD), diffuse reflectance UV-Vis spectroscopy and BET specific surface analysis. The catalytic activity of the immobilized catalysts was tested in the aerobic epoxidation of cyclohexene. CoPcS/NH2-MCM-41 and CoPcS/NH2-MCM-48 showed relatively high epoxide selectivity but low conversion of cyclohexene compared to CoPc/MCM-41 and CoPc/MCM-48. No leaching of metallophthalocyanine from the catalysts immobilized by chemical bonding into the reaction medium was observed and these catalysts could be reused four times.