Synthesis and characterization of composite molecular sieves M 1-MFI/M 2-MCM-41(M 1, M 2 = Ni, Co) with high heteroatom content and their catalytic properties for hydrocracking of residual oil

Abstract

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.