CHROMIUM(III) SILICATE CATALYSTS SUITABLE FOR PE SYNTHESIS

摘要

Molecular precursor chromium compounds and chromium on silica catalyst precursors suitable for use in producing chromium on silica catalysts are disclosed. The molecular precursor compounds can be chromium(II) and/or chromium(III) and/or chromium (IV) compounds wherein all ligands are easily removable, in particular ligands selected from the group consisting of anionic ligands of the type -O-CR 3 R 4 -CH-R 1 R 2 or -O-Si-(O-CR 3 R 4 -CHR 1 R 2 ) 3 wherein R1, R2, R3 and R4 may be the same or different and may be any group that does not affect decomposition of the ligand via elimination of beta-hydrogen from -CR 3 R 4 -CH-R 1 R 2 , amide anionic ligands of the type -N-Si-R 5 R 6 R 7 and/or -N-C-R 5 R 6 R 7 , wherein R 5 , R 6 and R 7 can be the same or different and are preferably selected from hydrogen, methyl groups, ethyl groups, n-propyl groups, iso-propyl groups, tert-butyl groups or aromatic groups; as well as coordinating solvents. These molecular precursors can be grafted to silica and - if need be - either before or after heat treatment during which the ligands are removed, oxidized to Cr(III). The chromium on silica catalyst is characterized by the absence of any organic ligands.