Synthesis and characterization of composite molecular sieves M1-MFI/M2-MCM-41(M1, M2=Ni, Co) with high heteroatom content and their catalytic properties for hydrocracking of residual oil

The novel rich heteroatom-containing (15 wt.%) composite molecular sieves M(1)-MFI/M(2)-MCM-41 have been prepared from the ionic complex [(C(4)H(9))(4)N](2)(+)[M(1)(EDTA)](2-) and [C(16)H(33)(CH(3))(3)N](2)(+)[M(2)(EDTA)](2-) as the organic templates, which could effectively introduce a large amount of heteroatoms into the framework of molecular sieves. The products were characterized by XRD, XRF, SEM, HRTEM, N(2) adsorption-desorption, H(2)-TPR, FT-IR, TG and DSC techniques. The catalytic performances of the composite materials were investigated by means of residual oil hydrocracking. Characterization results showed that the composite materials simultaneously possessed a typical orthogonal MFI phase and a hexagonal MCM-41 phase and the two phases were composite rather than the physical mixture. H(2)-TPR data indicated all of the heteroatoms were incorporated by isomorphous substitution of silicon in framework. N(2) adsorption-desorption analysis exhibited that these samples possessed regular and stable structure with high specific surface area and large pore diameters of 550-620 m(2) g(-1), 3.5 nm and 5.5 nm, respectively. M(1)-MFI/M(2)-MCM-41 presented excellent activities in hydrocracking of residual oil, which were superior to the pure materials of MFI/MCM-41.