CA2232502A1 - Polymerization inhibitor process - Google Patents
Polymerization inhibitor process Download PDFInfo
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- CA2232502A1 CA2232502A1 CA002232502A CA2232502A CA2232502A1 CA 2232502 A1 CA2232502 A1 CA 2232502A1 CA 002232502 A CA002232502 A CA 002232502A CA 2232502 A CA2232502 A CA 2232502A CA 2232502 A1 CA2232502 A1 CA 2232502A1
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- Prior art keywords
- oxyl
- tetramethylpiperidin
- bis
- vent gas
- styrene
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
- C07C15/40—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals
- C07C15/42—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals monocyclic
- C07C15/44—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals monocyclic the hydrocarbon substituent containing a carbon-to-carbon double bond
- C07C15/46—Styrene; Ring-alkylated styrenes
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
- C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
- C07C5/333—Catalytic processes
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/20—Use of additives, e.g. for stabilisation
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- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Water Supply & Treatment (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Polymerisation Methods In General (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
Abstract
Disclosed is a system and a process for cleanly handling the vent gas by-products of the dehydrogenation reaction of monovinyl aromatic compounds which process involves the use of polymerization inhibitor injected into the vent gas prior to its entry into the vent gas compressor.
Description
Case A-213591A/CGC 1939 CA 02232~02 l998-03-l8 Polymerizatior, Inhibitor Process Background of the invention The present invention relates to the inhibition of polymerization in a material stream containing a polymerizable monomer component, and more particularly involves thepolymerization of monovinyl aromatic monomers such as styrene contained in the vent gas off of a dehydrogenation unit.
In the manufacture of a monovinyl aromatic monomer such as styrene from a chemical feedstock such as ethylbenzene, the monomer is manufactured by dehydrogenating the feedstock in a dehydrogenation or "dehydro" unit. For example, ethylbenzene ("EB") feedstock is converted into styrene by passing the EB through an EB dehydro unit which removes hydrogen atoms from the EB molecules to form styrene molecules. The gaseous side products of the chemical reaction containing mostly hydrogen are drawn off the EB
dehydro unit under a vacuum as dehydro vent gas for additional processing.
The vent gas from the dehydro unit normally comprises hydrogen CO2, CO, HzO vapor, and hydrocarbon vapors. In one instance, the vent gas may be distilled to remove the "heavies"
(EB and styrene) which are recycled to the E.B dehydro unit and into the styrene product line, respectively, with the "lights", including the hydrogen, being burned for fuel value.
Alternatively, the entire vent gas stream can be burned for fuel gas.
In another instance, the dehydro vent gas may be cycled into a phenylacetylene reduction system comprising one or more catalyst reactors through which styrene monomer containing phenylacetylene contaminant is passed over a suitable catalyst in order to reduce the phenylacetylene contaminants to styrene by reacting with the hydrogen contained in the vent gas.
In each instance above the dehydro vent gas must be removed from the dehydro reactors, compressed and sent to another reactor, distillation unit, or burner. Regardless of its end use, the vent gas which is at reduced pressure must be compressed to about 45 PSI (6.5 -103 Pa) in order to transport it to the next stage of the process.
CA 02232~02 1998-03-18 Problems arise when trying to compress EB dehydro vent gas because of the styrene monomer content of the gas, styrene being a fairly reactive element and one which is quick to polymerize. Because of the heat of compression in the vent gas compressor, styrene monomer will polymerize readily on the intemal parts and surfaces of the compressor, causing malfunction and poor efficiency in the compressor. If the compressor has a shut down, the polymer causes it to "freeze". The restart is difficult and is an expensive operation.
The conventional solution for preventing polymer build-up in the vent gas compressor has been a continuous "wash" or "flush" of EB injected with the vent gas into the compressor.
This has no significant beneficial effect on the polymerization of the monomer but it does physically dissolve the polymer off of the compressor components and allows the compressor to continue running. The resultant EB/polymer solution must then be processed to remove the EB from the polymerized monomer which is usually low-grade low molecular weight material, having little commercial value. The disadvantages of this method is that reprocessing the EB/polymer solutions is expensive. The polymer adds to the plant tar and is a loss of valuable raw materials.
It is well known that vinyl aromatic compounds, such as styrene, a-methylstyrene and other substituted vinyl benzenes, have a strong tendency to polymerize when subjected to elevated temperatures. Since vinyl aromatic compounds produced by common industrial methods contain by-products and impurities, these compounds must be subjected toseparation and purification processes in order to be suitable for further industrial applications. Such separation and purification is generally accomplished by distillation techniques.
To prevent premature polymerization of vinyl aromatic monomers during the distillation purification process, various compounds have been used as polymerization inhibitors. Sulfur was widely employed in the past to inhibit polymerization of vinyl aromatic compounds.
However in recent times, many chemical compounds have been disclosed or developed as substitutes for sulfur in polymerization inhibiting applications. These compounds have varying degrees of success for industrial use in the distillation process.
In a typical distillation process for vinyl aromatic compounds using a polymerization inhibitor, the mixture containing the vinyl aromatic cornpound to be distilled is generally contacted with CA 02232~02 1998-03-18 the polymerization inhibitor before being subjected to distillation conditions in the distillation apparatus. It remains a significant problem that the amount of polymer formed in the distillation system and in the high purity product recovered therefrom is substantially higher than desired. Still worse, occasionally, complete polymerization of the vinyl aromatic compound occurs in the distillation system causing considerable economic loss. A typical distillation system is described in U.S. Pat. Nos. 4,252,615 and 4,341,600, the relevant parts of which are incorporated herein by reference.
U.S. Pat. No. 3,733,326 discloses the polymerization inhibition of vinyl monomers by free radical precursers. Soviet Patent No. 1,027,150 discloses the stabilization of styrene by using nitroxyl radical. Soviet Patent No. 1,139,722 discloses the use of a bis-nitroxyl radical as the thermal polymerization inhibitor for styrene. Japanese Hei 1-165534 discloses the use of 1-piperidyloxy derivatives as polymerization inhibitors for styrene. Soviet Patent No. 1,588,888 discloses the polymerization inhibition of styrene by a nitroxyl radical.
U.S. Pat. No. 4,087,147 discloses a process using 2-nitro-p-cresol as a polymerization inhibitor. U.S. Pat. Nos. 4,105,506 and 4,252,615 disclose a process using 2,6-dinitro-p-cresol as a polymerization inhibitor. U.S. Pat. Nos. 4,132,602 and 4,132,603 disclose the use of a halogenated aromatic nitro compound as a polymerization inhibitor for use during the distillation of vinyl aromatic compounds. However, these aromatic nitro compounds have relatively weak activity, and thus must be used at fairly high concentrations, especially at higher distillation temperatures. Considering the relatively high toxicity for human exposure, these aromatic nitro compounds cannot be regarded as acceptable agents for inhibiting polymerization.
In addition, U.S. Pat. Nos. 3,988,212 and 4,341,600 disclose the use of N-nitrosodiphenyl-amine combined with dinitro-cresol derivatives for inhibiting the polymerization of vinyl aromatic compounds under vacuum distillation conditions. U.S. Pat. No. 4,466,904 discloses the use of phenothiazine, 4-tert-butylcatechol and 2,6-dinitro-p-cresol as a polymerization inhibitor system in the presence of oxygen during heating of vinyl aromatic compounds. U.S.
Pat. No. 4,468,343 discloses a composition and a process for utilizing 2,6-dinitro-p-cresol and either a phenylenediamine or 4-tert-butylcatechol in the presence of oxygen to prevent the polymerization of vinyl aromatic compounds during heating. European patent application 240,297 A1 teaches the use of a substituted hydroxylamine and a dinitrophenol CA 02232~02 1998-03-18 to inhibit the polymerization of vinyl aromatic compound at elevated temperatures in a distillation process. However, the effectiveness of said systems are oxygen dependent. This results in inconsistent inhibition due to an inconsistent distribution of air throughout the distillation column and raises the possibility of an increased explosion safety hazard.
More recently, U.S. Pat. No. 5,254,760 disclosed an inhibitor composition which was intended to inhibit vinyl aromatic monomer polymerization during distillation and purification of such monomers. Such inhibitors may or may not be applicable in vent gas effluent systems due to the presence of aqueous condensation and because of the solubility of such inhibitors in aqueous condensates. Contamination of the aqueous phase is undesirable from the standpoint of effluent treatment and further from the desirability of avoiding catalyst poisoning arising from recycling of the aqueous phase into the reactors.
All of the above-noted patents and literature citations are hereby incorporated by reference into the present application.
The present invention overcomes these deficiencies by providing a system and a process whereby an EB flush is not necessary to remove polymer accumulations from vent gas compressor components because the process prevents polymerization of the monomer in the vent gas compressor.
The process and system disclosed and claimed herein utilizes a polymerization inhibitor that is injected into the EB dehydro vent gas upstream of the vent gas compressor to prevent polymer from forming inside the compressor.
~ In particular the instant invention is a process for preventing the premature polymerization of styrene monomer during its preparation by dehydrogenating ethylbenzene to styrene, said process comprising:
passing an ethylbenzene feedstream over a dehydrogenation catalyst in a dehydrogenation reactor to form a product stream of styrene;
removing from said reactor a vent gas strearn containing by-products, including hydrogen, ethylbenzene vapor, styrene, benzene and toluene vapors, CO, CO2 and water vapor;
injecting into said vent gas stream a styrene polymerization inhibitor; and, CA 02232~02 1998-03-18 compressing said vent gas stream for further processing without the formation of other than trace amount of polystyrene in the styrene manufacturing system.
Figure 1 is a schematic flow diagram of the system installed in a styrene manufacturing process.
Referring to Figure 1, which is a schematic diagram of a styrene manufacturing system, an ethylbenzene feed stream EBF is fed to an ethylbenzene dehydrogenation reactor EBD.
Hydrogen is removed from the ethylbenzene in the reactor EBD and a stream of styrene monomer SM is removed from the reactor. A by-product vent gas is drawn off of the reactor EBD through line VG and compressed in the vent gas compressor VGC and an inhibitor supply tank I communicates with line VG through inhibitor supply line IS. A styrene inhibitor is injected through line IS into line VG upstream of the compressor VGC. The compressed vent gas/inhibitor mixture then passes through valve V and is either routed to a waste heat boiler B and burned as a fuel or alternatively, is rerouted through valve V through recycle line RC and injected back into the crude styrene from reactor EBD. Alternatively, a phenylacetylene removal system, PAR, may be utilized in conjunction with the present invention by the use of a second valve PV which recycles all or a portion of the compressed vent gas into a phenylacetylene reduction reactor PAR. Likewise, the styrene monomer feedstream from EBD is cycled through a phenylacetylene valve PAV and into the reactor PAR. The inhibited vent gas flowing through valve PV into the PAR reactor system is commingled or admixed with the styrene monomer stream and the hydrogen content of the vent gas reduces the phenylacetylene content of the styrene monomer into styrene which then is removed through purified monomer line PM.
In one alternative embodiment (not shown), valve PV can be replaced with a purification system such as a distillation unit to separate the heavier volatiles such as ethylbenzene and styrene flowing through valve V into recycle line RC to recycle these heavier volatiles back into the ethylbenzene feedstream EBF. The remainder of the vent gas minus the heavier volatiles is then cycled into the phenylacetylene reduction reactor PAR to further purify the styrene monomer stream from the reactor EBD.
The particular inhibitor used may be of any suitable styrene polymerization inhibitor which is capable of being injected into a stream of gas. For example, one particularly advantageous CA 02232~02 1998-03-18 inhibitor was found to be bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, which is a hindered amine radical trap type of inhibitor.
Preferred hindered amine nitroxyl compounds useful in this invention, contain at least one radical of the formula (I) in the molecule H3C ~CH3 (I) o Particular useful are those hindered amine nitroxyl compounds which are derived from the corresponding hindered amines disclosed in EP-A-592 363.
Preferred amongst those are 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl acetate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butyl-benzoate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate;
N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipamide;
N-(1 -oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-c:aprolactam;
N-(1 -oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-clodecylsuccinimide;
In the manufacture of a monovinyl aromatic monomer such as styrene from a chemical feedstock such as ethylbenzene, the monomer is manufactured by dehydrogenating the feedstock in a dehydrogenation or "dehydro" unit. For example, ethylbenzene ("EB") feedstock is converted into styrene by passing the EB through an EB dehydro unit which removes hydrogen atoms from the EB molecules to form styrene molecules. The gaseous side products of the chemical reaction containing mostly hydrogen are drawn off the EB
dehydro unit under a vacuum as dehydro vent gas for additional processing.
The vent gas from the dehydro unit normally comprises hydrogen CO2, CO, HzO vapor, and hydrocarbon vapors. In one instance, the vent gas may be distilled to remove the "heavies"
(EB and styrene) which are recycled to the E.B dehydro unit and into the styrene product line, respectively, with the "lights", including the hydrogen, being burned for fuel value.
Alternatively, the entire vent gas stream can be burned for fuel gas.
In another instance, the dehydro vent gas may be cycled into a phenylacetylene reduction system comprising one or more catalyst reactors through which styrene monomer containing phenylacetylene contaminant is passed over a suitable catalyst in order to reduce the phenylacetylene contaminants to styrene by reacting with the hydrogen contained in the vent gas.
In each instance above the dehydro vent gas must be removed from the dehydro reactors, compressed and sent to another reactor, distillation unit, or burner. Regardless of its end use, the vent gas which is at reduced pressure must be compressed to about 45 PSI (6.5 -103 Pa) in order to transport it to the next stage of the process.
CA 02232~02 1998-03-18 Problems arise when trying to compress EB dehydro vent gas because of the styrene monomer content of the gas, styrene being a fairly reactive element and one which is quick to polymerize. Because of the heat of compression in the vent gas compressor, styrene monomer will polymerize readily on the intemal parts and surfaces of the compressor, causing malfunction and poor efficiency in the compressor. If the compressor has a shut down, the polymer causes it to "freeze". The restart is difficult and is an expensive operation.
The conventional solution for preventing polymer build-up in the vent gas compressor has been a continuous "wash" or "flush" of EB injected with the vent gas into the compressor.
This has no significant beneficial effect on the polymerization of the monomer but it does physically dissolve the polymer off of the compressor components and allows the compressor to continue running. The resultant EB/polymer solution must then be processed to remove the EB from the polymerized monomer which is usually low-grade low molecular weight material, having little commercial value. The disadvantages of this method is that reprocessing the EB/polymer solutions is expensive. The polymer adds to the plant tar and is a loss of valuable raw materials.
It is well known that vinyl aromatic compounds, such as styrene, a-methylstyrene and other substituted vinyl benzenes, have a strong tendency to polymerize when subjected to elevated temperatures. Since vinyl aromatic compounds produced by common industrial methods contain by-products and impurities, these compounds must be subjected toseparation and purification processes in order to be suitable for further industrial applications. Such separation and purification is generally accomplished by distillation techniques.
To prevent premature polymerization of vinyl aromatic monomers during the distillation purification process, various compounds have been used as polymerization inhibitors. Sulfur was widely employed in the past to inhibit polymerization of vinyl aromatic compounds.
However in recent times, many chemical compounds have been disclosed or developed as substitutes for sulfur in polymerization inhibiting applications. These compounds have varying degrees of success for industrial use in the distillation process.
In a typical distillation process for vinyl aromatic compounds using a polymerization inhibitor, the mixture containing the vinyl aromatic cornpound to be distilled is generally contacted with CA 02232~02 1998-03-18 the polymerization inhibitor before being subjected to distillation conditions in the distillation apparatus. It remains a significant problem that the amount of polymer formed in the distillation system and in the high purity product recovered therefrom is substantially higher than desired. Still worse, occasionally, complete polymerization of the vinyl aromatic compound occurs in the distillation system causing considerable economic loss. A typical distillation system is described in U.S. Pat. Nos. 4,252,615 and 4,341,600, the relevant parts of which are incorporated herein by reference.
U.S. Pat. No. 3,733,326 discloses the polymerization inhibition of vinyl monomers by free radical precursers. Soviet Patent No. 1,027,150 discloses the stabilization of styrene by using nitroxyl radical. Soviet Patent No. 1,139,722 discloses the use of a bis-nitroxyl radical as the thermal polymerization inhibitor for styrene. Japanese Hei 1-165534 discloses the use of 1-piperidyloxy derivatives as polymerization inhibitors for styrene. Soviet Patent No. 1,588,888 discloses the polymerization inhibition of styrene by a nitroxyl radical.
U.S. Pat. No. 4,087,147 discloses a process using 2-nitro-p-cresol as a polymerization inhibitor. U.S. Pat. Nos. 4,105,506 and 4,252,615 disclose a process using 2,6-dinitro-p-cresol as a polymerization inhibitor. U.S. Pat. Nos. 4,132,602 and 4,132,603 disclose the use of a halogenated aromatic nitro compound as a polymerization inhibitor for use during the distillation of vinyl aromatic compounds. However, these aromatic nitro compounds have relatively weak activity, and thus must be used at fairly high concentrations, especially at higher distillation temperatures. Considering the relatively high toxicity for human exposure, these aromatic nitro compounds cannot be regarded as acceptable agents for inhibiting polymerization.
In addition, U.S. Pat. Nos. 3,988,212 and 4,341,600 disclose the use of N-nitrosodiphenyl-amine combined with dinitro-cresol derivatives for inhibiting the polymerization of vinyl aromatic compounds under vacuum distillation conditions. U.S. Pat. No. 4,466,904 discloses the use of phenothiazine, 4-tert-butylcatechol and 2,6-dinitro-p-cresol as a polymerization inhibitor system in the presence of oxygen during heating of vinyl aromatic compounds. U.S.
Pat. No. 4,468,343 discloses a composition and a process for utilizing 2,6-dinitro-p-cresol and either a phenylenediamine or 4-tert-butylcatechol in the presence of oxygen to prevent the polymerization of vinyl aromatic compounds during heating. European patent application 240,297 A1 teaches the use of a substituted hydroxylamine and a dinitrophenol CA 02232~02 1998-03-18 to inhibit the polymerization of vinyl aromatic compound at elevated temperatures in a distillation process. However, the effectiveness of said systems are oxygen dependent. This results in inconsistent inhibition due to an inconsistent distribution of air throughout the distillation column and raises the possibility of an increased explosion safety hazard.
More recently, U.S. Pat. No. 5,254,760 disclosed an inhibitor composition which was intended to inhibit vinyl aromatic monomer polymerization during distillation and purification of such monomers. Such inhibitors may or may not be applicable in vent gas effluent systems due to the presence of aqueous condensation and because of the solubility of such inhibitors in aqueous condensates. Contamination of the aqueous phase is undesirable from the standpoint of effluent treatment and further from the desirability of avoiding catalyst poisoning arising from recycling of the aqueous phase into the reactors.
All of the above-noted patents and literature citations are hereby incorporated by reference into the present application.
The present invention overcomes these deficiencies by providing a system and a process whereby an EB flush is not necessary to remove polymer accumulations from vent gas compressor components because the process prevents polymerization of the monomer in the vent gas compressor.
The process and system disclosed and claimed herein utilizes a polymerization inhibitor that is injected into the EB dehydro vent gas upstream of the vent gas compressor to prevent polymer from forming inside the compressor.
~ In particular the instant invention is a process for preventing the premature polymerization of styrene monomer during its preparation by dehydrogenating ethylbenzene to styrene, said process comprising:
passing an ethylbenzene feedstream over a dehydrogenation catalyst in a dehydrogenation reactor to form a product stream of styrene;
removing from said reactor a vent gas strearn containing by-products, including hydrogen, ethylbenzene vapor, styrene, benzene and toluene vapors, CO, CO2 and water vapor;
injecting into said vent gas stream a styrene polymerization inhibitor; and, CA 02232~02 1998-03-18 compressing said vent gas stream for further processing without the formation of other than trace amount of polystyrene in the styrene manufacturing system.
Figure 1 is a schematic flow diagram of the system installed in a styrene manufacturing process.
Referring to Figure 1, which is a schematic diagram of a styrene manufacturing system, an ethylbenzene feed stream EBF is fed to an ethylbenzene dehydrogenation reactor EBD.
Hydrogen is removed from the ethylbenzene in the reactor EBD and a stream of styrene monomer SM is removed from the reactor. A by-product vent gas is drawn off of the reactor EBD through line VG and compressed in the vent gas compressor VGC and an inhibitor supply tank I communicates with line VG through inhibitor supply line IS. A styrene inhibitor is injected through line IS into line VG upstream of the compressor VGC. The compressed vent gas/inhibitor mixture then passes through valve V and is either routed to a waste heat boiler B and burned as a fuel or alternatively, is rerouted through valve V through recycle line RC and injected back into the crude styrene from reactor EBD. Alternatively, a phenylacetylene removal system, PAR, may be utilized in conjunction with the present invention by the use of a second valve PV which recycles all or a portion of the compressed vent gas into a phenylacetylene reduction reactor PAR. Likewise, the styrene monomer feedstream from EBD is cycled through a phenylacetylene valve PAV and into the reactor PAR. The inhibited vent gas flowing through valve PV into the PAR reactor system is commingled or admixed with the styrene monomer stream and the hydrogen content of the vent gas reduces the phenylacetylene content of the styrene monomer into styrene which then is removed through purified monomer line PM.
In one alternative embodiment (not shown), valve PV can be replaced with a purification system such as a distillation unit to separate the heavier volatiles such as ethylbenzene and styrene flowing through valve V into recycle line RC to recycle these heavier volatiles back into the ethylbenzene feedstream EBF. The remainder of the vent gas minus the heavier volatiles is then cycled into the phenylacetylene reduction reactor PAR to further purify the styrene monomer stream from the reactor EBD.
The particular inhibitor used may be of any suitable styrene polymerization inhibitor which is capable of being injected into a stream of gas. For example, one particularly advantageous CA 02232~02 1998-03-18 inhibitor was found to be bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, which is a hindered amine radical trap type of inhibitor.
Preferred hindered amine nitroxyl compounds useful in this invention, contain at least one radical of the formula (I) in the molecule H3C ~CH3 (I) o Particular useful are those hindered amine nitroxyl compounds which are derived from the corresponding hindered amines disclosed in EP-A-592 363.
Preferred amongst those are 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl acetate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butyl-benzoate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate;
N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipamide;
N-(1 -oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-c:aprolactam;
N-(1 -oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-clodecylsuccinimide;
2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]-s-triazine, and CA 02232~02 1998-03-18 4,4'-ethylenebis( 1 -oxyl-2 ,2,6,6-tetramethylpiperazin-3-one).
Most preferably, the compound is bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;
2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]-s-triazine; or 4,4'-ethylenebis(1-oxyl-2,2,6 ,6-tetramethylpiperazin-3-one) .
The inhibitor is preferably injected in an amount of 0.1 ppm to 1000 ppm, more preferably in an amount of 1 ppm to 500 ppm and most preferably in an amount of 5 ppm to 100 ppm based on the weight of the monomer.
This inhibitor is injected into the vent gas stream through line IS upstream of the vent gas compressor so that such inhibitor can successfully prevent polymerization of styrene on the compressor components. It is believed by the inventors that other similar injectable styrene inhibitors would also serve to prevent styrene polymerization on the internal compressor components. Although the process has not been actually attempted in an actual vent gas compressor, the inventors are of the belief that due to the nature of the inhibitor and the known characteristics of styrene monomer in vent gas applications, the presently disclosed inhibitor would sufficiently prevent polymerization in the compressor such that no polymer would be allowed to form therein.
Another subject of the present invention is a system for dehydrogenating ethylbenzene into styrene, said system comprising:
a catalytic dehydrogenation reactor adapted for dehydrogenating ethylbenzene into styrene;
an ethylbenzene feedstream supply connected to said reactor;
a vent gas removal sub-system connected to said reactor and arranged to remove from said reactor vent gas by-products of ethylbenzene dehydrogenation;
a vent gas compressor connected with said removal system and arranged to receive vent gas therefrom; and, a polymerization inhibitor sub-system between said removal sub-system and said compressor arranged to inject a polymerization inhibitor into vent gas from said reactor.
The definitions and preferences given above for the process also apply for the system for dehydrogenating ethylbenzene.
CA 02232~02 1998-03-18 Although a specific preferred embodiment of the present invention has been described in the detailed description above, the description is not intended to limit the invention to the particular forms or embodiments disclosed therein since they are to be recognized as illustrative rather than restrictive and it will be obvious to those skilled in the art that the invention is not so limited. For example, whereas the embodiments herein as disclosed with respect to the vent gas from ethylbenzenelstyrene reactor unit, it is obvious that the invention would pertain to other gas systems containing polymerizable monomers. Thus, the invention is declared to cover all changes and modifications of the specific example of the invention herein disclosed for purposes of illustration which do not constitute departure from the spirit and scope of the invention. The embodiments of the invention in which a specific property or privilege is claimed are defined as follows.
Example 1 A styrene processing plant, having a design similar to the schematic diagram in Figure 1 is run under typical conditions with no inhibitor added to the stream leading to the vent gas compressor. After three months, polystyrene accumulates on internal components of the compressor. The presence of polymer on compressor turbine blades results in imbalance and vibration. Polymer buildup reduces the efficiency of the compressor. After about five months, the compressor would need to be shut down for cleaning to prevent permanent damage to the equipment.
ExamPle 2 The same plant is operated as described in Example 1. However, 20 ppm of water insoluble polymerization inhibitor bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4.yl)sebacate is injected into the stream entering the vent gas compressor. After four months of operation the compressor is operating with no increase in vibration and no loss of efficiency. Traces of polystyrene are found in water condensing tank down stream from the EBD reactor. No traces of inhibitor are detected in the water phase of the condensing tank.
ExamPle 3 The plant is operated as described in Example 2. In this case, 20 ppm of water soluble polymerization inhibitor 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine is injected into the stream entering the vent gas compressor. After twelve months of operation the compressor is operating with no increase in vibration and no loss of efficiency. No polymer is detected in CA 02232~02 1998-03-18 ..9 the water phase of the condensing tank. Only a small amount of inhibitor is detected in the water phase of the condensing tank.
Example 4 The plant is operated as described in Example 2. In this case, 20 ppm of water soluble polymerization inhibitor 1-oxyl-2,2,6,6-tetramethylpiperidin-4-one is injected into the stream entering the vent gas compressor. After twelve months of operation the compressor is operating with no increase in vibration and no loss of efficiency. No polymer is detected in the water phase of the condensing tank. Only a small amount of inhibitor is detected in the water phase of the condensing tank.
ExamPle 5 The plant is operated as described in Example 2. In this case, 20 ppm of polymerization inhibitor 1-oxyl-2,2,6,6-tetramethylpiperidine 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate, 2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]-s-triazine or 4,4'-ethylenebis(1-oxyl-2,2,6,6-tetramethylpiperazin-3-one) is injected into the stream entering the vent gas compressor. After four months of operation the compressor is operating with no increase in vibration and no loss of efficiency.
Most preferably, the compound is bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;
2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]-s-triazine; or 4,4'-ethylenebis(1-oxyl-2,2,6 ,6-tetramethylpiperazin-3-one) .
The inhibitor is preferably injected in an amount of 0.1 ppm to 1000 ppm, more preferably in an amount of 1 ppm to 500 ppm and most preferably in an amount of 5 ppm to 100 ppm based on the weight of the monomer.
This inhibitor is injected into the vent gas stream through line IS upstream of the vent gas compressor so that such inhibitor can successfully prevent polymerization of styrene on the compressor components. It is believed by the inventors that other similar injectable styrene inhibitors would also serve to prevent styrene polymerization on the internal compressor components. Although the process has not been actually attempted in an actual vent gas compressor, the inventors are of the belief that due to the nature of the inhibitor and the known characteristics of styrene monomer in vent gas applications, the presently disclosed inhibitor would sufficiently prevent polymerization in the compressor such that no polymer would be allowed to form therein.
Another subject of the present invention is a system for dehydrogenating ethylbenzene into styrene, said system comprising:
a catalytic dehydrogenation reactor adapted for dehydrogenating ethylbenzene into styrene;
an ethylbenzene feedstream supply connected to said reactor;
a vent gas removal sub-system connected to said reactor and arranged to remove from said reactor vent gas by-products of ethylbenzene dehydrogenation;
a vent gas compressor connected with said removal system and arranged to receive vent gas therefrom; and, a polymerization inhibitor sub-system between said removal sub-system and said compressor arranged to inject a polymerization inhibitor into vent gas from said reactor.
The definitions and preferences given above for the process also apply for the system for dehydrogenating ethylbenzene.
CA 02232~02 1998-03-18 Although a specific preferred embodiment of the present invention has been described in the detailed description above, the description is not intended to limit the invention to the particular forms or embodiments disclosed therein since they are to be recognized as illustrative rather than restrictive and it will be obvious to those skilled in the art that the invention is not so limited. For example, whereas the embodiments herein as disclosed with respect to the vent gas from ethylbenzenelstyrene reactor unit, it is obvious that the invention would pertain to other gas systems containing polymerizable monomers. Thus, the invention is declared to cover all changes and modifications of the specific example of the invention herein disclosed for purposes of illustration which do not constitute departure from the spirit and scope of the invention. The embodiments of the invention in which a specific property or privilege is claimed are defined as follows.
Example 1 A styrene processing plant, having a design similar to the schematic diagram in Figure 1 is run under typical conditions with no inhibitor added to the stream leading to the vent gas compressor. After three months, polystyrene accumulates on internal components of the compressor. The presence of polymer on compressor turbine blades results in imbalance and vibration. Polymer buildup reduces the efficiency of the compressor. After about five months, the compressor would need to be shut down for cleaning to prevent permanent damage to the equipment.
ExamPle 2 The same plant is operated as described in Example 1. However, 20 ppm of water insoluble polymerization inhibitor bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4.yl)sebacate is injected into the stream entering the vent gas compressor. After four months of operation the compressor is operating with no increase in vibration and no loss of efficiency. Traces of polystyrene are found in water condensing tank down stream from the EBD reactor. No traces of inhibitor are detected in the water phase of the condensing tank.
ExamPle 3 The plant is operated as described in Example 2. In this case, 20 ppm of water soluble polymerization inhibitor 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine is injected into the stream entering the vent gas compressor. After twelve months of operation the compressor is operating with no increase in vibration and no loss of efficiency. No polymer is detected in CA 02232~02 1998-03-18 ..9 the water phase of the condensing tank. Only a small amount of inhibitor is detected in the water phase of the condensing tank.
Example 4 The plant is operated as described in Example 2. In this case, 20 ppm of water soluble polymerization inhibitor 1-oxyl-2,2,6,6-tetramethylpiperidin-4-one is injected into the stream entering the vent gas compressor. After twelve months of operation the compressor is operating with no increase in vibration and no loss of efficiency. No polymer is detected in the water phase of the condensing tank. Only a small amount of inhibitor is detected in the water phase of the condensing tank.
ExamPle 5 The plant is operated as described in Example 2. In this case, 20 ppm of polymerization inhibitor 1-oxyl-2,2,6,6-tetramethylpiperidine 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate, 2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]-s-triazine or 4,4'-ethylenebis(1-oxyl-2,2,6,6-tetramethylpiperazin-3-one) is injected into the stream entering the vent gas compressor. After four months of operation the compressor is operating with no increase in vibration and no loss of efficiency.
Claims (8)
1. A process for preventing the premature polymerization of styrene monomer during its preparation by dehydrogenating ethylbenzene to styrene, said process comprising:passing an ethylbenzene feedstream over a dehydrogenation catalyst in a dehydrogenation reactor to form a product stream of styrene;
removing from said reactor a vent gas stream containing by-products, including hydrogen, ethylbenzene vapor, styrene, benzene and toluene vapors, CO, CO2 and water vapor;
injecting into said vent gas stream a styrene polymerization inhibitor; and, compressing said vent gas stream for further processing without the formation of other than trace amount of polystyrene in the styrene manufacturing system.
removing from said reactor a vent gas stream containing by-products, including hydrogen, ethylbenzene vapor, styrene, benzene and toluene vapors, CO, CO2 and water vapor;
injecting into said vent gas stream a styrene polymerization inhibitor; and, compressing said vent gas stream for further processing without the formation of other than trace amount of polystyrene in the styrene manufacturing system.
2. The process of claim 1, wherein said polymerization inhibitor is a hindered amine radical trap inhibitor.
3. The process of claim 1, wherein said polymerization inhibitor is selected from the group consisting of 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl acetate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butyl-benzoate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate;
N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipamide;
N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-caprolactam;
N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-dodecylsuccinimide;
2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]-s-triazine, and4,4'-ethylenebis(1-oxyl-2,2,6,6-tetramethylpiperazin-3-one).
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butyl-benzoate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate;
N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipamide;
N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-caprolactam;
N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-dodecylsuccinimide;
2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]-s-triazine, and4,4'-ethylenebis(1-oxyl-2,2,6,6-tetramethylpiperazin-3-one).
4. The process of claim 3, wherein said polymerization inhibitor is bis(1-oxyl-2,2,6,6-tetra-methylpiperidin-4-yl) sebacate.
5. A system for dehydrogenating ethylbenzene into styrene, said system comprising:
a catalytic dehydrogenation reactor adapted for dehydrogenating ethylbenzene into styrene;
an ethylbenzene feedstream supply connected to said reactor;
a vent gas removal sub-system connected to said reactor and arranged to remove from said reactor vent gas by-products of ethylbenzene dehydrogenation;
a vent gas compressor connected with said removal system and arranged to receive vent gas therefrom; and, a polymerization inhibitor sub-system between said removal sub-system and said compressor arranged to inject a polymerization inhibitor into vent gas from said reactor.
a catalytic dehydrogenation reactor adapted for dehydrogenating ethylbenzene into styrene;
an ethylbenzene feedstream supply connected to said reactor;
a vent gas removal sub-system connected to said reactor and arranged to remove from said reactor vent gas by-products of ethylbenzene dehydrogenation;
a vent gas compressor connected with said removal system and arranged to receive vent gas therefrom; and, a polymerization inhibitor sub-system between said removal sub-system and said compressor arranged to inject a polymerization inhibitor into vent gas from said reactor.
6. A system according to claim 5, wherein said polymerization inhibitor is a hindered amine radical trap inhibitor.
7. A system according to claim 6, wherein said polymerization inhibitor is selected from the group consisting of 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl acetate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butyl-benzoate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate;
N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipamide;
N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-caprolactam;
N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-dodecylsuccinimide;
2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]-s-triazine, and4,4'-ethylenebis(1-oxyl-2,2,6,6-tetramethylpiperazin-3-one).
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate;
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butyl-benzoate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate;
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate;
N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipamide;
N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-caprolactam;
N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-dodecylsuccinimide;
2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]-s-triazine, and4,4'-ethylenebis(1-oxyl-2,2,6,6-tetramethylpiperazin-3-one).
8. A system according to claim 7, wherein said polymerization inhibitor is bis(1-oxyl-2,2,6,6-tetra-methylpiperidin-4-yl) sebacate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US82128197A | 1997-03-20 | 1997-03-20 | |
| US08/821281 | 1997-03-20 |
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| CA2232502A1 true CA2232502A1 (en) | 1998-09-20 |
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| Application Number | Title | Priority Date | Filing Date |
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| CA002232502A Abandoned CA2232502A1 (en) | 1997-03-20 | 1998-03-18 | Polymerization inhibitor process |
Country Status (13)
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| JP (1) | JPH10330297A (en) |
| KR (1) | KR19980080447A (en) |
| BE (1) | BE1011649A5 (en) |
| BR (1) | BR9800931A (en) |
| CA (1) | CA2232502A1 (en) |
| CZ (1) | CZ83398A3 (en) |
| DE (1) | DE19811602A1 (en) |
| ES (1) | ES2142274B1 (en) |
| FR (1) | FR2761060B1 (en) |
| ID (1) | ID20069A (en) |
| IT (1) | IT1298751B1 (en) |
| NL (1) | NL1008644C2 (en) |
| SK (1) | SK36398A3 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016149433A1 (en) * | 2015-03-18 | 2016-09-22 | Ecolab Usa Inc. | The use of stable lipophilic hydroxylamine compounds for inhibiting polymerization of vinyl monomers |
| US9884951B2 (en) | 2014-10-14 | 2018-02-06 | Ecolab Usa Inc. | Reducing polymer fouling and agglomeration in acrylate/methacrylate processes |
| US9957209B2 (en) | 2015-03-31 | 2018-05-01 | Ecolab Usa Inc. | Use of quinone methides as antipolymerants for vinylic monomers |
| US10155705B2 (en) | 2015-04-20 | 2018-12-18 | Ecolab Usa Inc. | Sterically hindered hydroquinones as antifoulants for unsaturated monomers |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000036052A1 (en) * | 1998-12-17 | 2000-06-22 | Nalco/Exxon Energy Chemicals, L.P. | Inhibiting polymerization of vinyl aromatic monomers using synergistic mixtures containing nitroxide stabilizers |
| US6300533B1 (en) | 1999-08-16 | 2001-10-09 | Uniroyal Chemical Company, Inc. | Inhibition of polymerization of ethylenically unsaturated monomers |
| AR029410A1 (en) | 1999-12-02 | 2003-06-25 | Crompton Corp | METHOD FOR INHIBITING PREMATURE POLYMERIZATION OF ETHENICALLY INSATURED MONOMERS AND COMPOSITIONS OF THE SAME |
| DE60023542T2 (en) | 1999-12-02 | 2006-07-20 | Crompton Corp., Middlebury | POLYMERIZATION INHIBITION OF UNSATURATED MONOMERS |
| WO2001040404A1 (en) | 1999-12-03 | 2001-06-07 | Uniroyal Chemical Company, Inc. | Composition and method for inhibiting polymerization and polymer growth |
| US6403850B1 (en) | 2000-01-18 | 2002-06-11 | Uniroyal Chemical Company, Inc. | Inhibition of polymerization of unsaturated monomers |
| US6344560B1 (en) | 2000-05-03 | 2002-02-05 | Uniroyal Chemical Company, Inc. | Nitroaromatic solubilizer for nitroxyls in aromatic solvents |
| CA2422655A1 (en) | 2000-10-16 | 2002-04-25 | Uniroyal Chemical Company, Inc. | Blends of quinone alkide and nitroxyl compounds as polymerization inhibitors |
| US6685823B2 (en) | 2000-10-16 | 2004-02-03 | Uniroyal Chemical Company, Inc. | C-nitrosoaniline compounds and their blends as polymerization inhibitors |
| US6689926B2 (en) * | 2002-02-12 | 2004-02-10 | Fina Technology, Inc. | Process for purifying styrene monomer feedstock prior to polymerization |
| JP2006016350A (en) * | 2004-07-02 | 2006-01-19 | Hakuto Co Ltd | Method for preventing fouling in styrene production |
| US7553896B2 (en) | 2005-06-17 | 2009-06-30 | Chemtura Corporation | Ortho-nitrosophenols as polymerization inhibitors |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IL40059A (en) * | 1971-08-11 | 1975-02-10 | Universal Oil Prod Co | Fractional distillation of polymerizable compounds |
| US4670131A (en) * | 1986-01-13 | 1987-06-02 | Exxon Chemical Patents Inc. | Method for controlling fouling of hydrocarbon compositions containing olefinic compounds |
| US5254760A (en) * | 1992-07-29 | 1993-10-19 | Ciba-Geigy Corporation | Inhibiting polymerization of vinyl aromatic monomers |
| ES2126185T3 (en) * | 1994-08-19 | 1999-03-16 | Huels Chemische Werke Ag | INHIBITION OF THE POLYMERIZATION OF STYRENE. |
| US5545786C1 (en) * | 1994-11-28 | 2001-10-16 | Ciba Geigy Corp | Method for inhibiting premature polymerization of vinyl aromatic monomers |
| JP4392807B2 (en) * | 1995-06-07 | 2010-01-06 | フイナ・テクノロジー・インコーポレーテツド | Polymerization inhibitor method |
| WO1998002403A1 (en) * | 1996-07-15 | 1998-01-22 | Betzdearborn Inc. | Method for inhibiting vinyl aromatic monomer polymerization in condenser and compression systems |
-
1998
- 1998-03-17 DE DE19811602A patent/DE19811602A1/en not_active Withdrawn
- 1998-03-17 ID IDP980385A patent/ID20069A/en unknown
- 1998-03-18 CZ CZ98833A patent/CZ83398A3/en unknown
- 1998-03-18 IT IT98MI000548A patent/IT1298751B1/en active IP Right Grant
- 1998-03-18 BE BE9800215A patent/BE1011649A5/en not_active IP Right Cessation
- 1998-03-18 CA CA002232502A patent/CA2232502A1/en not_active Abandoned
- 1998-03-18 SK SK363-98A patent/SK36398A3/en unknown
- 1998-03-19 BR BR9800931-1A patent/BR9800931A/en not_active Application Discontinuation
- 1998-03-19 FR FR9803351A patent/FR2761060B1/en not_active Expired - Fee Related
- 1998-03-19 NL NL1008644A patent/NL1008644C2/en not_active IP Right Cessation
- 1998-03-19 KR KR1019980009415A patent/KR19980080447A/en not_active Application Discontinuation
- 1998-03-19 JP JP10090923A patent/JPH10330297A/en active Pending
- 1998-03-20 ES ES009800596A patent/ES2142274B1/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9884951B2 (en) | 2014-10-14 | 2018-02-06 | Ecolab Usa Inc. | Reducing polymer fouling and agglomeration in acrylate/methacrylate processes |
| WO2016149433A1 (en) * | 2015-03-18 | 2016-09-22 | Ecolab Usa Inc. | The use of stable lipophilic hydroxylamine compounds for inhibiting polymerization of vinyl monomers |
| US9914701B2 (en) | 2015-03-18 | 2018-03-13 | Ecolab Usa Inc. | Use of stable lipophilic hydroxylamine compounds for inhibiting polymerization of vinyl monomers |
| RU2715559C2 (en) * | 2015-03-18 | 2020-03-02 | ЭКОЛАБ ЮЭсЭй ИНК. | Use of stable lipophilic hydroxylamine compounds to inhibit polymerisation of vinyl monomers |
| US9957209B2 (en) | 2015-03-31 | 2018-05-01 | Ecolab Usa Inc. | Use of quinone methides as antipolymerants for vinylic monomers |
| US10155705B2 (en) | 2015-04-20 | 2018-12-18 | Ecolab Usa Inc. | Sterically hindered hydroquinones as antifoulants for unsaturated monomers |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2761060B1 (en) | 1999-08-20 |
| CZ83398A3 (en) | 1998-10-14 |
| SK36398A3 (en) | 2000-02-14 |
| JPH10330297A (en) | 1998-12-15 |
| BR9800931A (en) | 2000-04-04 |
| BE1011649A5 (en) | 1999-11-09 |
| NL1008644A1 (en) | 1998-09-22 |
| ES2142274B1 (en) | 2001-01-01 |
| DE19811602A1 (en) | 1998-11-12 |
| KR19980080447A (en) | 1998-11-25 |
| IT1298751B1 (en) | 2000-02-02 |
| NL1008644C2 (en) | 1998-12-15 |
| ES2142274A1 (en) | 2000-04-01 |
| ITMI980548A1 (en) | 1999-09-18 |
| FR2761060A1 (en) | 1998-09-25 |
| ID20069A (en) | 1998-09-24 |
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