Ethylene polymerisation using solid catalysts based on layered double hydroxides

Abstract

We report here the use of methylaluminoxane (MAO) modified aqueous miscible organic solvent treated (AMOST) layered double hydroxide, Mg₆Al₂(OH)₁₆CO₃·4H₂O (AMO-Mg₃Al-CO₃) as a catalyst support system for the slurry phase polymerisation of ethylene using immobilised metallocene and non-metallocene metal complexes. The polymerisation data demonstrates that the catalyst productivity is dependent on the thermal treatment of the LDH and the temperature, pressure and time of the polymerisation. The solid catalyst system, AMO-Mg₃Al-CO₃/MAO/(^MesPDI)FeCl₂ has been shown to have the highest overall activity for a non-metallocene system (14166 kg_PE mol⁻¹_complex h⁻¹ bar⁻¹), and AMO-Mg₃Al-CO₃/MAO/(^2-Me,4-PhSBI)ZrCl₂ was the most productive for a metallocene-based system (∼3300 kg_PE mol⁻¹_complex h⁻¹ bar⁻¹). The molecular weights and polydispersities vary with the complex on the AMO-LDH surface. Scanning electron microscopy images show that the morphology of the as produced polyethylene mimics that of the LDH support.