Abstract: The present invention is related to methods for lowering peroxide levels in sucrose acetate isobutyrate formulations and to composition used in and formed by such methods.

Abstract: Disclosed herein are systems and methods for monitoring and controlling a nitroxide-based polymerization inhibitor in vinyl-based monomers. A dosage of the nitroxide-based polymerization inhibitor is provided in the vinyl-based monomers. A residual concentration of the nitroxide-based polymerization inhibitor is measured substantially in real time, and an optimized dosage of the nitroxide-based polymerization inhibitor is provided in response to the measured residual concentration.

Abstract: A method for retarding polymerization of vinyl monomers comprising adding a quinone methide to a liquid comprising the vinyl monomers is described.

Abstract: Polymerization inhibitor compositions are provided. The polymerization inhibitor compositions may include at least one hydroxylamine of a nitroxide and at least one phenylenediamine. Methods of inhibiting the unwanted polymerization of monomers are also provided. The methods include adding the presently disclosed polymerization inhibitor compositions to a fluid containing the monomers. The monomers may be ethylenically unsaturated monomers, such as acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, acrolein, methacrolein, acrylate, methacrylate, acrylamide, methacrylamide, vinyl acetate, butadiene, ethylene, propylene, and styrene.

Abstract: The present invention relates to an improved amine based additive composition for control and inhibition of polymerization of aromatic vinyl monomers including styrene comprising one or more of the quinone methide or derivatives thereof, one or more of nitroxide compounds and further comprising one or more of aliphatic tertiary amines. In one embodiment, the present invention also relates to method of use of presently provided composition. In another embodiment, the present invention also relates to method of controlling and inhibiting polymerization of aromatic vinyl monomers, particularly of styrene by employing presently provided composition. In still another embodiment, the present invention also relates to method of preparation of presently provided composition.

Abstract: The present invention provides a method for inhibiting unwanted polymerization of reactive monomers within a liquid. The method comprises the combined usage of a quinone methide with a quinone diimide to the liquid monomer. This combination has an unexpected synergistic effect. Thus, in some ratios, the combination results in practically 100% inhibition.

Abstract: High temperatures and oxygen exposure during extractive distillation can result in polymerization of vinyl aromatic compounds. In various embodiments, the present disclosure relates to methods for inhibiting polymerization of vinyl aromatic compounds during extractive distillation. In various embodiments, the methods include a) providing a mixture containing at least one vinyl aromatic compound, b) adding at least one dinitrophenol inhibitor to the mixture, and c) after step b), performing an extractive distillation on the mixture to isolate the at least one vinyl aromatic compound. Purified styrene can be isolated by the methods described herein. In some embodiments, the dinitrophenol inhibitor is 2-sec-butyl-4,6-dinitrophenol (DNBP).

Abstract: A process for inhibiting polymerization of (meth)acrylic acid and/or (meth)acrylic esters by introducing an oxygenous gas into the (meth)acrylic acid and/or the (meth)acrylic ester, in which the (meth)acrylic acid and/or the (meth)acrylic ester has a degree of purity of at least 95% and is in the liquid state.

Abstract: A method for suppressing isomerization of an olefin metathesis product produced in a metathesis reaction includes adding an isomerization suppression agent to a mixture that includes the olefin metathesis product and residual metathesis catalyst from the metathesis reaction under conditions that are sufficient to passivate at least a portion of the residual metathesis catalyst. The isomerization suppression agent includes (i) a salt and/or an ester of a phosphorous oxo acid, and/or (ii) a derivative of the phosphorous oxo acid in which at least one P—H bond has been replaced by a P—C bond, and/or (iii) a salt and/or an ester of the derivative. Methods of refining natural oils are described.

Abstract: A process is proposed for distillatively obtaining pure 1,3-butadiene from crude 1,3-butadiene in a plant comprising one or more distillation columns, comprising supply of a feed stream of crude 1,3-butadiene to the one distillation column or the first of the plurality of distillation columns, the one distillation column or the plurality of distillation columns having a flange with an internal diameter of ?80 mm, comprising two mutually opposite plane-parallel surfaces (1) with an intermediate seal (2) which seals the interior of the one distillation column or of the first of the plurality of distillation columns from an intermediate space (3) on the atmosphere side between the two mutually opposite plane-parallel surfaces (1), and the intermediate space (3) on the atmosphere side between the two mutually opposite plane-parallel surfaces (1) being closed off from the atmosphere to form a chamber, wherein the chamber is purged continuously during the operation of the plant with a low-oxygen gas or a low-oxygen

Abstract: Process for distillatively purifying polymerizable compounds using a high-boiling, inert, thermally long-term-stable substance as a boiling oil, characterized in that the boiling oil is disposed in the bottom of a rectification column.

Abstract: Process for devolatilization of a polymer of an aromatic alkylene, such as styrene and, in particular, an improved process using water as a stripping agent (i) in which the total amount of water to be disposed of can be reduced, (ii) which allows at least a portion of the water to be recycled as stripping agent, reducing make-up requirements for the stripping agent, and (iii) which allows at least a portion of the aromatic alkylene monomer in the water to be recycled to the polymerization process (via the devolatilization steps) rather than being disposed.

Abstract: Accumulation of polymer on equipment, which is in contact with polymerizable material during normal process operation, is minimized by the method and apparatus of the present invention. The method involves positioning and affixing the equipment, such as a pressure relief device, to process apparatus, such as a distillation column, proximate to a wetted region comprising liquid phase fluid in the process apparatus, such that the moving liquid phase fluid is at least intermittently in contact with the equipment and one or more of accumulated polymerizable material, condensate comprising same, and polymer, is washed off of the equipment.

Abstract: A method for inhibiting the formation of fouling materials including contacting hydrocarbon media containing aldehyde compounds with an antifoulant while treating the hydrocarbon media with a basic wash. The antifoulant includes a reducing sugar.

Abstract: There is provided a method for rectifying a vinyl compound liquor. The method includes the steps of a) providing a rectification column operated at a temperature and pressure and b) feeding the vinyl compound liquor to be rectified into the rectification column, wherein the pressure of the rectification column and the temperature of the fed vinyl compound liquor are controlled, such that the temperature of the fed vinyl compound liquor ranges from its bubble point at the pressure of the rectification column to 10° C. lower than the bubble point.

Abstract: A condenser includes: a top face of a tube plate on which acrylic acid may be condensed inside the condenser; a spray for spreading a polymerization inhibitor on the tube plate; a first polymerization inhibitor supply tube for supplying the polymerization inhibitor to the spray; and a supporter for supporting the spray at a predetermined position. The supporter supports the first polymerization inhibitor supply tube outside the condenser. The condenser allows a stable continuous operation for a long period of time by preventing polymerization of an easily polymerizable compound in the condenser into which a vapor of an easily polymerizable compound is supplied with a simple structure thereof.

Abstract: A process is proposed for distillatively obtaining pure 1,3-butadiene from crude 1,3-butadiene in a plant comprising one or more distillation columns, comprising supply of a feed stream of crude 1,3-butadiene to the one distillation column or the first of the plurality of distillation columns, the one distillation column or the plurality of distillation columns having a flange with an internal diameter of ?80 mm, comprising two mutually opposite plane-parallel surfaces (1) with an intermediate seal (2) which seals the interior of the one distillation column or of the first of the plurality of distillation columns from an intermediate space (3) on the atmosphere side between the two mutually opposite plane-parallel surfaces (1), and the intermediate space (3) on the atmosphere side between the two mutually opposite plane-parallel surfaces (1) being closed off from the atmosphere to form a chamber, wherein the chamber is purged continuously during the operation of the plant with a low-oxygen gas or a low-oxygen

Abstract: A process for rectificatively separating an acrylic acid-containing liquid, by withdrawing an acrylic acid-rich stream from the rectification column above the feed point and polymerization-inhibiting the upper section of the rectification column by means of diacrylic acid.

Abstract: A decomposition reaction apparatus or distillation apparatus for acrylic acid in which a column bottom liquid heated in a reboiler (5) is supplied from a supply port (1a) provided on a side wall of a column body (1) having: a top plate (12a) above the supply port (1a); and an impingement plate (12b) provided vertically to the top plate (12a), for preventing scattering of the column bottom liquid to a supply direction. The top plate (12a) is provided such that the top face of the top plate (12a) is inclined downward from a base end to a tip end. The present invention allows: suppression of formation of a polymerized product due to flowing of a liquid or gas heated in a reboiler into a column with a simple structure; and a stable continuous operation of column equipment over a long period of time.

Abstract: Process for the production of vinyl aromatic monomers which comprises: a) feeding an aromatic stream and an olefinic stream to an alkylation unit; b) feeding the reaction product coming from the alkylation section to a first separation section; c) recovering the mono-alkylated aromatic hydrocarbon and the heavy bottom product from the first separation section; d) feeding the mono-alkylated aromatic to a dehydrogenation section; e) feeding the reaction product coming from the dehydrogenation section to a second purification/separation section; f) also feeding the heavy bottom product of step (c) to the second purification/separation section; g) recovering a stream consisting of the vinyl aromatic monomer with a purity higher than 99.7 by weight.

Abstract: A process for rectificatively separating fluids including (meth)acrylic monomers in a rectification column by directly cooling the vapor including (meth)acrylic monomers rising to the top of the rectification column to form top condensate including (meth)acrylic monomers, the condensation space at the top of the column being separated from the region of the rectification column containing the separating internals only by at least one chimney tray from which the top condensate formed is removed from the rectification column, which includes effecting the direct cooling of the vapor in the condensation space in at least two spray zones which are spatially successive and are flowed through by vapor by spraying supercooled top condensate including added polymerization inhibitor, and the temperature of the sprayed supercooled top condensate becoming lower from spray zone to spray zone in the flown direction of the vapor.

Abstract: A method for dimerizing isobutene, wherein, in dimerizing conditions, the isobutene is brought into contact with a porous cation exchange resin comprising a styrene polymer, which is cross-linked with divinyl benzene, and any sulphonic acid groups adhering to the polymer. The harmful deactivation of this catalyst, which is caused by the accumulation of the oligomers and polymers of isobutene and other C4-olefins in the cation exchange resin catalyst, is essentially decreased by selecting the cation exchange resin from a group including cation exchange resins, the acid,capacity of which is 4.7 equivalents/kg at a minimum, and the portion of divinyl benzene units of which is 5% by weight at a minimum and smaller than 20% by weight.

Abstract: Quinone methide derivatives such as 4-benzylidene-2,6-di-tert-butyl-cyclohexa-2,5 dienone are used to inhibit styrene monomer polymerization in the dehydrogenator portion of a styrene monomer production system. The inhibitor contacts the dehydrogenation effluent and does not partition in substantial amounts to the aqueous phase that is separated in the phase separator.

Abstract: Inhibitor blends that include both nitrosophenols and nitrosoanilines, optionally in combination with air or oxygen, reduce the premature polymerization of ethylenically unsaturated monomers. unsaturated monomers.

Abstract: A process for preventing undesired polymerization is conducted by maintaining an effective concentration of a stabilizer which comprises N-oxyl radicals in a mixture containing ethylenically unsaturated compounds, wherein (i) an electronic signal which correlates with the concentration of the N-oxyl radicals in the mixture is obtained periodically or continuously, (ii) the electronic signal is compared with a reference value, and (iii) addition of a stabilizer to the mixture is controlled according to the comparison (ii). The signal is preferably obtained by ESR measurement. The process permits efficient use of the stabilizer.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds.

Abstract: A method for inhibiting and dissolving the deposits formed on caustic or alkaline scrubbers used in scrubbing acidic gases such as carbon dioxide, hydrogen sulfide, which are formed during the pyrolytic cracking of naphtha, ethane, and propane. The cracking operations produce certain oxygenated compounds such as vinyl acetate or acetaldehyde, which undergo polymerization under alkaline condition. The vinyl acetate on hydrolysis releases acetaldehyde under alkaline conditions. Amino acids such as 6 amino caproic acid and lactams such as epsilon caprolactam not only prevent but also dissolve the polymers formed by aldol condensation.

Abstract: Inhibitor blends comprising nitrosophenols and nitrosoanilines, optionally in combination with air or oxygen, reduce the premature polymerization of ethylenically unsaturated monomers.

Abstract: This invention relates to a process of inhibiting the polymerization of vinyl-containing materials through the use of an effective amount of a polymerization inhibitor comprising quinone diimide and a nitroxyl stable free radical under various conditions. This invention also relates to the polymerization inhibitor composition.

Abstract: Methods and compositions for inhibiting the polymerization of vinyl monomers are disclosed. Combinations of nitroxyl compounds and aliphatic amines are effective at inhibiting the polymerization of vinyl monomers under both processing and storage conditions.

Abstract: This invention relates to a method for preventing (meth)acrylic acid from polymerizing during the course of distillation. The method provides for refining (meth)acrylic acid by a procedure including the steps of feeding a mixed gas obtained by catalytic gas phase oxidation of propylene and/or acrolein with a molecular oxygen-containing gas or a mixed gas obtained by catalytic gas phase oxidation of at least one compound of isobutylene, t-butyl alcohol, or methacrolein with a molecular oxygen-containing gas, to a (meth)acrylic acid collection column, collecting a (meth)acrylic acid-containing solution from the mixed gas, and feeding the (meth)acrylic acid-containing solution to a distillation column while maintaining the total concentration of aldehydes of 2-4 carbon atoms and acetone in the solution at a level of not more than 2000 ppm based on the amount of (meth)acrylic acid.

Abstract: Methods and compositions for inhibiting the polymerization of vinyl monomers are disclosed. Combinations of nitroxyl compounds and aliphatic amines are effective at inhibiting the polymerization of vinyl monomers under both processing and storage conditions.

Abstract: A mixture contains one or more vinyl-containing compounds as component (A) and, as a further component, a stabilizer (B) which contains one or more readily volatile nitroxyl compounds as component (b1), one or more sparingly volatile nitroxyl compounds as component (b2), if required one or more aromatic nitro compounds as component (b3) and, if required, one or more iron compounds as component (b4). Stabilizers (B) contain the components (b1) and (b2), (b1) and (b2) and (b3), (b1) and (b2) and (b4), and (b1), (b2), (b3) and (b4), and the premature polymerization of vinyl-containing compounds during their purification or distillation is inhibited by a process in which a stabilizer (B) is added or the components of stabilizer (B) are added as individual substances or in at least two groups of the components.

Abstract: The present invention provides a solvent exchange column for continuously exchanging styrene monomer with the solvent used to produce polybutadiene and a method of use therefor. The solvent exchange column includes an exchange plate support structure coupled to and supporting spaced apart exchange plates, wherein each of the exchange plates has holes located therein to allow a passage of fluid therethrough. The solvent exchange column further includes a vapor ventilation system for allowing the volatized solvent to exit the solvent exchange column.

Abstract: This invention relates to a process of inhibiting the polymerization of vinyl-containing materials through the use of an effective amount of a polymerization inhibitor comprising quinone diimide and a nitroxyl stable free radical under various conditions. This invention also relates to the polymerization inhibitor composition.

Abstract: A monomer composition, stabilized against premature polymerization, comprising: a) an ethylenically unsaturated monomer or mixture of monomers polymerizable by free radical initiation, and b) an effective amount, sufficient to inhibit premature polymerization of component (a) of a mixture of: i) 1 to 99% by weight, based on the total weight of components (i) and (ii), of a mixture of at least one aromatic amine and at least one organic acid in a molar ratio of 10:1 to 1:10, and ii) 99 to 1% by weight, based on the total weight of components (i) and (ii), of at least one stable radical compound.

Abstract: A monomer composition, stabilized against premature polymerization, comprising: a) an ethylenically unsaturated monomer or mixture of monomers polymerizable by free radical initiation, and b) an effective amount, sufficient to inhibit premature polymerization of component (a) of a mixture of: i) 1 to 99% by weight, based on the total weight of components (i) and (ii), of a mixture of at least one aromatic amine and at least one organic acid in a molar ratio of 10:1 to 1:10, and ii) 99 to 1% by weight, based on the total weight of components (i) and (ii), of at least one stable radical compound.

Abstract: The present invention is directed to an apparatus and method for the distillation of a readily polymerizable vinyl aromatic compound employing a polymerization inhibitor. The vinyl aromatic compound is subjected to distillation in at least one fractionation column having at least one reboiler for maintaining the bottoms of said column at a proper temperature. The reboiler includes a heating section and a vapor phase section. The bottoms fraction from the fractionation column is cycled to the reboiler and subjected to heat to vaporize at least a portion of the bottoms fraction to form a vapor phase in the vapor section, A slip stream of the bottoms fraction is introduced to the vapor phase section of the reboiler. The slipstream contains polymerization inhibitor that had been added to the process at the fractionation column. The invention reduces fouling at the reboilers. The slipstream is optionally introduced to the reboiler using one or more spray nozzles.

Abstract: The present invention provides compositions and methods inhibiting polymerization of vinyl aromatic compounds comprising a bisphenol compound and an oxidized p-phenylenediamine. In a specific, non-limiting embodiment, the polymerization of the vinyl aromatic compound styrene is inhibited by a composition comprising the bisphenol compound 4,4′-methylenebis(2,6-di-tert-butyphenol) and the oxidized p-phenylenediamine compound N-phenyl-N′-methyl-benzoquinonediimide.

Abstract: Popcorn polymer growth is inhibited in unstabilized materials comprising olefinically unsaturated organic compounds by adding thereto an effective amount of an aliphatic alcohol of the formula I

Abstract: Methods and compositions for inhibiting the polymerization of ethylenically unsaturated hydrocarbons are disclosed. Combinations of aminophenol compound and either of phenylenediamine or hydroxylamine compounds are effective at inhibiting this polymerization under both processing and storage conditions.

Abstract: This invention is directed to certain N,N′-dinitroso phenylenediamines useful as polymerization inhibitors for acrylic acids and esters thereof. Also disclosed are compositions containing such compounds, and methods for inhibiting polymerization using such compounds and compositions.

Abstract: Methods and compositions for inhibiting the polymerization of ethylenically unsaturated hydrocarbons are disclosed. Combinations of aminophenol compound and either of phenylenediamine or hydroxylamine compounds are effective at inhibiting this polymerization under both processing and storage conditions.

Abstract: The production of 1,2-butadiene in purities of at least 85% becomes possible by means of a process in which a polymerization-inhibitor-containing C4 hydrocarbon fraction is subjected to at least one fractional distillation.

Abstract: When a nitroxyl compound is heated in an oxygen-free atmosphere with a vinyl aromatic monomer at 50-140.degree. C. for up to 60 days, it forms an activated inhibitor mixture which is superior to the nitroxyl compound itself in preventing the premature polymerization of a vinyl aromatic monomer during its processing and purification.

Abstract: Process technology is described making possible substantial improvements in the separation and recovery of highly pure vinyl aromatic monomers, notably styrene. A number of design, construction and operational features are made available for selection and use both for new plant facilities and for upgrading existing plant facilities. One major aspect of the invention is reduction in retention or residence times in the distillation towers. In another embodiment, a startup process comprises (i) introducing a feed comprising vinylaromatic monomer, polymerization inhibitor, aromatic hydrocarbon components having boiling points above that of the vinylaromatic monomer to a packed distillation column, said column having a maximum theoretical .DELTA.

Abstract: Process technology is described making possible substantial improvements in the separation and recovery of highly pure vinyl aromatic monomers, notably styrene. A number of design, construction and operational features are made available for selection and use both for new plant facilities and for upgrading existing plant facilities. One major aspect of the invention is reduction in retention or residence times in the distillation towers.

Abstract: Inhibition performance is improved in styrene processing through the addition of a stable nitroxide free radical compound to the styrene feed and to the reflux of at least one column.

Abstract: The polymerization of vinyl aromatic monomers such as styrene is inhibited by the addition of a composition of a stable hindered nitroxyl radical and an oxime compound.

Abstract: The polymerization of a vinylaromatic or vinylaliphatic compound at elevated temperature in the absence of air is inhibited by processing the vinylaromatic or vinylaliphatic compound in the presence of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl or 4-acetylamino-2,2,6,6-tetramethylpiperidine-N-oxylalone or in admixture with p-nitrosophenol or 2-methyl-4-nitrosophenol.