Abstract: The invention provides a fluidized bed polymerization reactor, including: a column, in which a liquid distributor and a gas distributor above the liquid distributor are arranged, so that the reaction zone being divided into a first zone and a second zone through the gas distributor; and a circulating unit for circulating the gas material originated from the top zone of the column into the bottom zone thereof in a form of gas-liquid mixture. The gas-liquid mixture is undergone a gas-liquid separation in the bottom zone, the gas phase portion obtained being fed to the gas distributor and then into the second zone while the liquid phase portion obtained being entered into the first zone through the liquid distributor, so that the temperature in the first zone is lower than that in the second zone. Therefore, polymer with a molecular weight distributed in a relatively wide range can be obtained. The invention further provides a method for preparing polymer.

Abstract: The invention provides a fluidized bed polymerization reactor, including: a column, in which a liquid distributor and a gas distributor above the liquid distributor are arranged, so that the reaction zone being divided into a first zone and a second zone through the gas distributor; and a circulating unit for circulating the gas material originated from the top zone of the column into the bottom zone thereof in a form of gas-liquid mixture. The gas-liquid mixture is undergone a gas-liquid separation in the bottom zone, the gas phase portion obtained being fed to the gas distributor and then into the second zone while the liquid phase portion obtained being entered into the first zone through the liquid distributor, so that the temperature in the first zone is lower than that in the second zone. Therefore, polymer with a molecular weight distributed in a relatively wide range can be obtained. The invention further provides a method for preparing polymer.

Abstract: A composite catalyst useful in the production of polyethylene, which comprises at least a first catalyst and a second catalyst separated by a polymer layer, with the first catalyst and the second catalyst being identical or different, is described. A composite catalyst useful in the production of polyethylene with a broad molecular weight distribution in a single polymerization reactor, which comprises at least a first catalyst and a second catalyst separated by a polymer layer, with the first catalyst and the second catalyst being different, is also described. A process for preparing said catalysts and a process for the production of a polyethylene by using said catalysts are also described.

Abstract: A composite catalyst useful in the production of polyethylene, which comprises at least a first catalyst and a second catalyst separated by a polymer layer, with the first catalyst and the second catalyst being identical or different, is described. A composite catalyst useful in the production of polyethylene with a broad molecular weight distribution in a single polymerization reactor, which comprises at least a first catalyst and a second catalyst separated by a polymer layer, with the first catalyst and the second catalyst being different, is also described. A process for preparing said catalysts and a process for the production of a polyethylene by using said catalysts are also described.