Mitsui Chemicals, Inc.

Mitsui Petrochemical Industries, Ltd.

Shotaro Matsuda

Satoru Ohtani

Tomohiro Arase

Shinji Abe

Yoshiaki Kikuchi

Ryoichi Yamamoto

Hiroto Nishida

Michiharu Sakata

Toshihiro Okano

A process for producing a polyolefin according to the present invention comprises (co) polymerizing one or two or more &#x3b1;-olefins in a vapor phase in a fluidized-bed reactor, wherein the concentration of (A) a saturated aliphatic hydrocarbon in the fluidized bed reactor is 1 mol % or more and at least one compound selected from (B) an aliphatic amide and (C) a nonionic surfactant constituted only of carbon, oxygen and hydrogen atoms is made to exist in the reactor. The present invention can provide a process for producing a polyolefin, the process ensuring that the prevention of clogging caused by the generation of sheet or block polymers and a high efficiency of the production of a polyolefin due to good catalytic activity can be accomplished at the same time and also having superb continuous productivity.

Process for producing polyolefin

The present invention provides a method for producing a polyolefin composition having a narrow composition distribution and is characterized in that when at least two olefins are copolymerized in the presence of a transition metal compound catalyst using at least two gas phase fluidized bed reactors, a saturated aliphatic hydrocarbon is allowed to exist in each reactor in a concentration from 0.1 to 30 mol %, and the ratio of the concentration (C ) of a saturated aliphatic hydrocarbon in a reactor of a second stage to the concentration (C ) of a saturated aliphatic hydrocarbon in a reactor of a first stage (C /C ) is 0.13 or more. Further, the present invention provides a method for producing a polyolefin composition by multi-stage polymerization, which can prevent sheeting in the reactor and can give a polyolefin composition stably with high productivity, and is characterized in that a saturated aliphatic hydrocarbon is allowed to exist in a transport line for transporting a polymer particle extracted from a fluidized bed reactor in the previous stage to a fluidized bed reactor in the subsequent stage at a concentration from 0.1 to 30 mol %.

Processes for producing polyolefin composition

A method of multistage gas phase polymerization is provided comprising performing polymerization of a feed gas mixture at least containing ethylene gas, an &agr;-olefin gas and hydrogen gas in an upstream fluid bed reactor to thereby produce a polymer powder, recovering the thus-produced polymer powder and performing further polymerization of the polymer powder in a downstream fluid bed reactor, the downstream fluid bed reactor being continuously connected to the upstream fluid bed reactor so that the polymer powder recovered from the upstream fluid bed reactor is introduced into the downstream fluid bed reactor, which method comprises the steps of: recovering polymer powder from the upstream fluid bed reactor, treating the recovered polymer powder so as to lower the content of &agr;-olefin gas and hydrogen gas therein by contacting the polymer powder with a stream of gas comprising ethylene or an inert gas, and introducing the treated polymer powder into the downstream fluid bed reactor. By this method, &agr;-olefin gas and hydrogen gas which inhibit the polymerization reaction in the downstream fluid bed reactor and which render regulation of desired polymer product properties difficult are removed from the polymer product prior to the downstream fluid bed reactor.

Method of multistage gas phase polymerization, apparatus therefor and device for reducing entrainment of subcomponents in polymer powder in apparatus for multistage gas phase polymerization

A rotor 22 accommodated in a casing 26 has a circumferential surface sliding on the internal surface of the casing 26 in airtight condition. The casing 26 is provided with a powder feed part 27 positioned above the rotor and is provided with a powder drop part 30 positioned under the rotor. At least one quantity-measuring recessed part is formed in the slide surface of the rotor. In accordance with the rotation of the rotor, the quantity-measuring recessed part comes to communicate with the powder feed part, so that powder is fed from the powder feed part into the quantity-measuring recessed part. When the rotation is advanced, the quantity-measuring recessed part comes to communicate with the powder drop part, so that the powder drops from the quantity-measuring recessed part through the powder drop part into a high-pressure part 19 arranged thereunder. These members construct a quantitative powder feeder which, even when a pressure difference exists between the supply side and the supplied side, can effectively prevent the gas flow and pressure leak therebetween and can minimize the amount of carrier gas used for feeding powder.

Growing community of inventors

Ichihara, Japan

Shotaro Matsuda