Grafting of CpMo(CO)3 Na+ on 3,6-dichloro-pyridazine modified mesoporous MCM-41 and MCM-48 molecular sieves

摘要

MCM-41/48 samples are hydrothermally synthesized and employed for fixing a modified pyridazine ligand and grafting a CpMo(CO)3-moiety through the reaction of the chlorine ligand of the surface fixed pyridazine with [CpMo(CO)3]~Na+. The grafted materials are characterized by analytical and spectroscopic techniques including XRD, FT-IR, BET, TEM, 29Si CP MAS NMR and elemental analysis. The heterogenized materials are applied for the catalytic epoxidation of cyclooctene. XRD and N2 adsorption/desorption analysis of the parent MCM-41, MCM-48 and of the grafted samples are providing strong evidence that the mesoporous structure of the support retains long range ordering throughout the grafting process and that the channels remain accessible. Elemental analyses (EA) indicate the presence of 1.7-2.2 wt. % of Mo in the grafted samples. FT-IR and 29Si MAS NMR spectra of the grafted samples show a decrease in the relative intensity of the silanol (Si-OH) band, indicating that the surface hydroxyl groups have been partially used for the grafting. New bands around 2016 and 1956 cm"' can be assigned to terminal carbonyl (CO) group vibrations of the grafted CpMo(CO)3-moiety. Furthermore, the hydrogenised compounds are found to be promising for the epoxidation of defines.