Abstract: A specific nonionic surfactant is added to a component mainly comprising hydrocarbons before passing through a heat exchanger in a petrochemical plant or a polyolefin production plant, whereby fouling of the heat exchanger can be efficiently prevented, that is, the performance of the heat exchanger can be prevented from being deteriorated, and long-term operation is feasible without sacrificing the speed of production. The nonionic surfactant is preferably a polyoxyalkylene compound represented by the general formula [I] below, more preferably a compound represented by the general formula [II] below. R1—O—[CH2—CH(R3)—O]k—R2[I] wherein R1, R2 and R3 are selected from a hydrogen atom, a C1 to C20 alkyl group, a C6 to C20 aryl group and a C1 to C20 acyl group, and may be the same or different from each other. HO—(CH2CH2O)m—[CH2CH(CH3)O]n—(CH2CH2O)pH[II] wherein m, n and p each represent the average number of repeating units, and m is in the range of 1 to 20, n is 2 to 50 and p is 1 to 20.

Abstract: A specific nonionic surfactant is added to a component mainly comprising hydrocarbons before passing through a heat exchanger in a petrochemical plant or a polyolefin production plant, whereby fouling of the heat exchanger can be efficiently prevented, that is, the performance of the heat exchanger can be prevented from being deteriorated, and long-term operation is feasible without sacrificing the speed of production. The nonionic surfactant is preferably a polyoxyalkylene compound represented by the general formula [I] below, more preferably a compound represented by the general formula [II] below. R1—O—[CH2—CH(R3)—O]k—R2??[I] wherein R1, R2 and R3 are selected from a hydrogen atom, a C1 to C20 alkyl group, a C6 to C20 aryl group and a C1 to C20 acyl group, and may be the same or different from each other. HO—(CH2CH2O)m-[CH2CH(CH3)O]n—(CH2CH2O)pH??[II] wherein m, n and p each represent the average number of repeating units, and m is in the range of 1 to 20, n is 2 to 50 and p is 1 to 20.

Abstract: In a gas phase olefin polymerization process using a fluidized bed vessel, an apparatus is employed having a device for measuring temperature or temperature distribution on the external wall surface of the vessel and a controlling means which predicts the progressive state of reaction inside the vessel, calculates the difference between the measured value and a target value determined beforehand and modifies polymerization conditions in relation thereto.

Abstract: A process for producing a polyolefin according to the present invention comprises (co) polymerizing one or two or more ?-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.

Abstract: A process for producing a polyolefin according to the present invention comprises (co) polymerizing one or two or more &agr;-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.

Abstract: In a gas phase olefin polymerization process using a fluidized bed vessel, an apparatus is employed having a device for measuring temperature or temperature distribution on the external wall surface of the vessel and a controlling means which predicts the progressive state of reaction inside the vessel, calculates the difference between the measured value and a target value determined beforehand and modifies polymerization conditions in relation thereto.

Abstract: 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 (C2) of a saturated aliphatic hydrocarbon in a reactor of a second stage to the concentration (C1) of a saturated aliphatic hydrocarbon in a reactor of a first stage (C2/C1) is 0.13 or more.

Abstract: In a gas phase olefin polymerization process using a fluidized bed vessel, an apparatus is employed having a device for measuring temperature or temperature distribution on the external wall surface of the vessel and a controlling means which predicts the progressive state of reaction inside the vessel, calculates the difference between the measured value and a target value determined beforehand an modifies polymerization conditions.

Abstract: A method of terminating a gas phase polymerization of an olefin to be conducted subsequent to producing a polyolefin by feeding a gaseous olefin into a fluidized bed reactor to polymerize the gaseous olefin while holding solid particles containing a catalyst in a fluid state, said method comprising introducing a deactivator in the fluidized bed reactor through at least two deactivator introduction ports of the fluidized bed reactor so as to terminate the gas phase polymerization. The height of the fluidized bed is generally at least 3 m. The deactivator is preferably introduced through deactivator introduction ports disposed at heights Ha=-0.3 D to 0.3 D (a) and Hb=0.3 D to 2.0 D (b) (D is the inside diameter of the fluidized bed reactor (cm)). After the termination of the polymerization, the gas phase polymerization can directly be resumed.

Abstract: 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.

Abstract: A process for producing N,N-disubstituted aminophenol which comprises the steps of:obtaining a reaction mixture containing N-substituted aminophenol by reacting a dihydric phenol and an amine;subjecting said reaction mixture to heat treatment so as to thermally decompose quaternary ammonia salt contained in said reaction mixture into a dihydric phenol and an amine, and removing at least said amine by distillation;separating high-boiling impurities by distillation to separate N-substituted aminophenol; andsubjecting said separated N-substituted aminophenol to reduction alkylation using an aldehyde compound.According to the present invention, high-purity N,N-disubstituted aminophenol can be obtained in a high yield at high selectivity, and a reduction catalyst can be used repeatedly because its activity can be maintained at a high level and yet it can retain high activity for a long period of time.