摘要:
Catalysts and methods for making and using the same are provided. The method for fabricating a catalyst may includes contacting a supported catalyst with a monomer under conditions that reduce an overall charge of the catalyst to less than about 75% of an initial charge of the catalyst. A method for polymerization may include introducing a pre-polymerized catalyst and one or more olefins into a gas phase fluidized bed reactor, operating the reactor at conditions sufficient to produce a polyolefin, wherein the polymerization is carried out in the substantial absence of any continuity additives.
摘要:
Methods are provided to prepare a catalyst system that includes at least one titanium compound, at least one magnesium compound, at least one electron donor compound, at least one activator compound, and at least one silica support material, the at least one silica support material having a median particle size in the range of from 20 to 50 microns with no more than 10% of the particles having a size less than 10 microns and no more than 10% of the particles having a size greater than 50 microns and average pore diameter of at least ≧220 angstroms.
摘要:
Broad molecular weight polyethylene and polyethylene having a bimodal molecular weight distribution can be produced with chromium oxide catalyst supported on silica having particular values of surface area and pore volume in conjunction with alkyl silanols, aluminium alkyls, and silyl chromate, optionally also with titanium alkoxides.
摘要:
Disclosed herein are various processes, including continuous fluidized-bed gas- phase polymerization processes for making a high strength, high density polyethylene copolymer, comprising (including): contacting monomers that include ethylene and optionally at least one non-ethylene monomer with fluidized catalyst particles in a gas phase in the presence of hydrogen gas at an ethylene partial pressure of 100 psi or more and a polymerization temperature of 120°C or less to produce a polyethylene copolymer having a density of 0.945 g/cc or more and an ESCR Index of 1.0 or more wherein the catalyst particles are prepared at an activation temperature of 700°C or less, and include silica, chromium, and titanium.