Influence of nanopores of MCM-41 and SBA-15 confining (n-BuCp)2ZrCl2 on copolymerization of ethylene-alpha-olefin.

The effect of nanopore in mesoporous materials confining (n-BuCp),ZrCl2 and methylaluminoxane (MAO) on ethylene-1-hexene and ethylene-1-octene copolymerization was investigated on the basis of the copolymerization results, and the analysis of the supported catalyst and the copolymers. SBA-15 and MCM-41 together with amorphous silica were employed as supports, which are capable of confining (n-BuCp)2ZrCl2 and MAO in the nanopore. The copolymerization activities of MCM-41-supported (n-BuCp)2ZrCl2 were higher than those of SBA-15 and SiO2 although that its Zr content was quite lower than those of SBA-15 and SiO2. SBA-15 and MCM-41 showed a remarkable decrease in BET surface area after confining MAO and (n-BuCp)2ZrCl2 compared to SiO2, explaining an even adsorption of MAO and (n-BuCp)2ZrCl2 complexes on the nanopore surface. Temperature rising elution fractionation (TREF) results showed bimodal curves of MCM-41-supported (n-BuCp)2ZrCl2 at the C6/C2 and C8/C2 molar ratios of 0.6 and 0.5, respectively, which was attributed to the differences in ethylene and alpha-olefin concentrations along with the cylindrical nanopore of MCM-41 due to the narrow nanospace.