Porous organic polymer/MMT hybrid supports for efficient metallocene catalysts

The preparation of organic/inorganic hybrid materials has been proven to be an effective method to overcome the drawbacks of organic or inorganic materials. In this paper, porous organic polymer/montmorillonite (POP/MMT) hybrid materials by in situ intercalative radical polymerization were synthesized for metallocene catalyst support, and the prepared POP/MMT hybrid supports obtained excellent particle flowability with tunnable bulk density (0.20-0.40 cm(3)/g) and specific surface area (SSA) (100-350 m(2)/g) suitable for polyolefin catalysts. N-2 sorption porosity, TGA, IR, XRD, SEM characterization were conducted to evaluate the POP/MMT hybrid supports, and the results showed that the MMT sheets could be well-dispersed in the POP matrix through in situ intercalative polymerization when 80% DVB was used, and when DVB/HEMA with 3:1 molar ratio was added, the prepared POP/MMT hybrid support POP-7 (331 m(2)/g) gained excellent particle flowability and single peak of particle size distribution. Ethylene polymerization results exhibited that the POP/MMT supported metallocene catalysts could obtain better polymerization performance than MMT and silica gel-supported catalysts. The hybrid support POP-4 based metallocene catalyst achieved the highest polymerization activity of 8019 kg PE/mol Zr.bar.h and productivity of 1136 g PE/g cat.h with the produced PE bulk density of 0.27 g/ml. POP-4 supported metallocene catalyst obtained increased productivity of 2300 g PE/g cat.h and bulk density of 0.32 g/ml in higher ethylene partial pressure of 6 bar, and gained stable polymerization kinetics in 80 degrees C with no obvious decay. Furthermore, the pore structure played a significant effect on the molecular weight and molecular weight distribution by nanoconfined polymerization, and larger molecular chains could be produced on the POP/MMT supported catalysts with smaller nanopore size.