Abstract: A method for improving purification efficiency when distilling off aldehyde contaminants during chemical manufacturing processes by adding a substituted aromatic amine having electron donating group substituents prior to the distillation column. The method is particularly useful for removal of aldehydes such as acrolein, generated as a by-product of acrylonitrile manufacture. Preferred aromatic amines are 2-amino aniline, 3,4-dimethyl aniline and 4-ethyl aniline.
November 5, 1998
Date of Patent:
June 13, 2000
Nalco/Exxon Energy Chemicals, L.P.
Natu R. Patel, Vincent E. Lewis, Margaret D. Enderson
Abstract: The invention provides a method for the inhibition of fouling in petrochemical processes. The method comprises adding from about 0.1 to about 10,000 parts per million sulfonated oils, sulfonated fatty acids, sulfated oils, sulfated fatty acids, or naphthalene sulfonate formaldehyde condensates to a petrochemical process to disperse water insoluble foulant into an aqueous system.
Abstract: Disclosed herein is a process for removing acrolein from a gaseous or liquid mixture, in one case aqueous solutions, involving contacting the mixture with a compound selected from the group consisting of sodium hypochlorite; an acid salt of hydroxylamine; a urea compound such as urea itself or thiourea; sodium bisulfite and 4,4-dimethyl-1-oxa-3-azacyclopentane in an amount effective to substantially remove acrolein has been discovered. The process works particularly well in selectively scavenging acrolein from aqueous solutions containing acrylonitrile.
Abstract: A process for the catalytic distillation production of alkylated aromatic compounds is provided wherein the vapor pressure of the olefin may be increased while maintaining the same olefin feed rate and aromatic to olefin ratio. In one embodiment a side stream from the vapor from the second column below the catalyst and olefin feed is condensed and rerouted to the aromatic make up stream from the reflux drum. The vapor pressure of the olefin in the lower end of the first column in the catalyst bed is thus increased which increases the equilibrium concentration of the olefin in the liquid phase. In another embodiment of the invention the effective driving force for the reaction is increased by injecting the olefin at different heights within the catalyst bed. If additional olefin is injected more catalyst bed height would be required, but the additional catalyst is more that offset by the increased throughput at the same overall olefin conversion.
Abstract: Excess amounts of a pure form of acrylonitrile are reacted with other reactants in the production of various compounds such as 2-acrylamido-2-methyl propane sulfonic acid. Accordingly, large amounts of acrylonitrile remain unreacted and present with other contaminants. The present invention is directed toward the purification of such unreacted acrylonitrile and the purified acrylonitrile obtained from such a purification process. The purification is carried out by treating the unreacted acrylonitrile with a base and removing salts formed. The treated material is fed to a heat exchanger which heats the material preferably under vacuum to about 120.degree. F. and provides a heated fluid material. This heated fluid material is pumped to a lower area of a distillation tower which is maintained under vacuum and includes a plurality of distillation trays.
February 10, 1988
Date of Patent:
February 28, 1989
The Lubrizol Corporation
Douglas J. Hallenburg, Alan C. Clark, James L. Hambrick
Abstract: Methacrylonitrile higher in purity than that obtained by the conventional process is efficiently produced by the present improved process for producing purified methacrylonitrile in which the reaction mixture formed by the ammoxidation of isobutylene or tert-butyl alcohol is distilled using water as solvent to obtain a crude methacrylonitrile solution which contains methacrylonitrile as major constituent, methacrolein, hydrogen cyanide, and isobutyronitrile, and the crude methacrylonitrile solution is then purified in a product column, wherein the improvement comprises first removing isobutyronitrile from said crude solution, then feeding the remaining solution to the product column, withdrawing from the top a vapor containing methacrolein, condensing the vapor, returning a greater part of the condensate to the product column while removing the remainder from the distillation system, and withdrawing purified methacrylonitrile from the middle or lower section, preferably from a point lower than the feeding sta
Abstract: From an acrylonitrile-dimerization liquid product prepared by contacting acrylonitrile with a specific catalyst composed of a metal halide and a trialkylamine, 2-methyleneglutaronitrile is efficiently recovered by a process which comprises contacting the reaction liquid product under stirring with benzene, toluene or xylene as well as with water in specific ratios, and then separating the resulting aromatic hydrocarbon layer from the mixture to recover 2-methyleneglutaronitrile.
March 24, 1982
Date of Patent:
December 27, 1983
Mitsubishi Petrochemical Company Limited
Abstract: The invention provides a process for the recovery and purification of acrylonitrile from acetonitrile and relatively heavy impurities mixture by water extractive distillation and solvent stripping wherein the mixture is fed to approximately the middle of a recovery column, a primary solvent water stream is added to the top of this column and a secondary solvent water stream is added to a point intermediate the mixture feed point and the top of the recovery column; a recovery column bottoms stream comprising water, acetonitrile and acrolein is removed from the bottom of the column and is added to a stripper column; acetonitrile is removed from the upper portion of the stripper column, a primary solvent water stream is removed from the bottom of the stripper column and is sent to the top of the recovery column as the source of the added primary solvent water stream and a secondary solvent water stream is removed from an intermediate point of the solvent stripper and is sent to the recovery column as the source
Abstract: A process is described for the recovery and purification of an olefinic nitrile, such as methacrylonitrile, from mixtures of said olefinic nitrile with hydrogen cyanide, acetonitrile, acrylonitrile, and carbonyl compounds, which result from the ammoxidation of an olefin, such as isobutylene. The mixtures of olefinic nitrile are fed to an extractive distillation column at a point above the middle of the column, a vapor sidestream is removed at a point below the middle of the extractive distillation column said sidestream containing substantially all of the hydrogen cyanide, acetonitrile and carbonyl compounds and then concentrating the hydrogen cyanide, acetonitrile and carbonyl compounds in a stripping pot.
Abstract: A multi-stage evaporator is used to remove water from the extracted distillation or stripper tower bottoms recycled as quench liquid to the quench tower of an acrylonitrile purification and recovery system. This results in a significant decrease in the amount of waste quench tower bottoms produced by the system. Use of a multi-effect evaporator represents a significant energy savings as compared with other techniques for decreasing the water content of the recycle stream.
Abstract: A process for separating acetonitrile from a crude olefinically unsaturated nitrile which comprises passing a reaction gas obtained in the ammoxidation of propylene or isobutylene through a quenching column, an absorption column with water, an extractive distillation column for the olefinically unsaturated nitrile and a stripping column for acetonitrile successively, condensing the acetonitrile-containing vapor from the top of the stripping column, evaporating the condensate acetonitrile-containing liquid into a gas, subjecting the resulting gas mixture to a vapor-liquid separation and subjecting the gas separated to an incineration while withdrawing the liquid separated.
Abstract: A process for purifying a crude olefinically unsaturated nitrile containing hydrogen cyanide and water by feeding the crude olefinically unsaturated nitrile at a point above the middle of a rectifying column for stripping hydrogen cyanide, withdrawing and condensing a vapor of hydrogen cyanide from the top of the column while withdrawing the olefinically unsaturated nitrile and water from the bottom of the column, which process comprises withdrawing a vapor in the column at a point between the top of the column and the point of introduction of the crude olefinically unsaturated nitrile at a substantially constant rate, cooling and condensing the vapor withdrawn in a condenser having an outlet for non-condensing gas while continuously withdrawing non-condensing gas in the vapor from the condenser, and returning the condensate liquid to the column at an intermediate point between the point of introduction of the crude olefinically unsaturated nitrile and the top of the column, and a condenser useful for the abo
Abstract: A method for purifying acrylonitrile resulting in capital and operating cost savings consists of distilling a solution of acrylonitrile and impurities in a distillation column under vacuum, and removing the purified acrylonitrile as a vaporous sidestream from the column.
Abstract: Waste water recovered from a nitrile production effluent, containing ammonia, hydrogen cyanide, carbon dioxide and water soluble polymers is stripped of ammonia, carbon dioxide and hydrogen cyanide to produce an aqueous stream containing the water soluble polymer. At least a portion of this stream is introduced into a steam scrubber to generate steam therefrom, with scrubber bottoms and any remaining water from the stripping operation being introduced into a reboiler to provide steam for the stripping and an aqueous concentrate of the water soluble polymer. Heat for the reboiler can be provided by indirect heat transfer with steam from the scrubber which produces a condensate suitable as feed water for steam generation.
Abstract: Substantial operating cost savings are realized in the recovery of acrylonitrile from an aqueous solution containing acrylonitrile by using the recovery column bottoms stream to provide heat to one or more distillation columns in the process.
Abstract: In the recovery and purification of acrylonitrile or methacrylonitrile obtained by the ammoxidation reaction of propylene or isobutylene, the bottoms stream associated with the column for extractively distilling acrylonitrile or methacrylonitrile is both reduced in size and increased in polymer concentration by removing a vapor stream containing water from the lower fourth of said column, thus reducing the amount of solids-containing waste streams to be treated.
Abstract: Waste water resulting from the production of acrylonitrile by gas phase oxidation of propylene and ammonia with oxygen as washing water in the recovery section is purified by treating the waste water with 0.4 to 1 ton of steam per ton of waste water in a detoxification column attached to or following the separation column (for the separation of acetonitrile and acrylonitrile from the waste water in the acrylonitrile process) at a temperature from 100.degree. to 125.degree. C, at a pressure of 0 to 2 (gauge) atmospheres; separating the non-volatile resinous organic compounds from the thus treated waste water in an evaporator and using the vapors from the top of said evaporator to heat the said separation column and detoxification column; and optionally adding an organic amine to said distillation column or to said evaporator.
Abstract: Substantial capital and operating cost savings and improved recovery of acrylonitrile and methacrylonitrile are realized by the recycle of the product column bottoms to the quench liquid of the reactor effluent quench system.