MXPA01003749A - Production of amides and/or acids from nitriles - Google Patents

Abstract

A process for producing an amide and/or acid from a nitrile comprises introducing a nitrile, as a first reactant, and a hydration compound, as a second reactant which is capable of reacting with the nitrile to convert it to its corresponding amide thus hydrating the nitrile and/or to convert it to its corresponding acid, into a treatment zone. The nitrile is subjected to catalytic distillation in the treatment zone in the presence of the hydration compound, to hydrate at least some of the nitrile to the corresponding amide and/or to form its corresponding acid. The amide and/or acid is withdrawn from the treatment zone.

Description

PRODUCTION OF AMIDES AND / OR ACIDS FROM NITRILES DESCRIPTION OF THE INVENTION This invention relates to the production of amides and / or acids from nitriles. It is related in particular to a process for producing an amide and / or an acid from a nitrile. According to the invention, there is provided a process for producing an amide and / or an acid from a nitrile, which process comprises introducing a nitrile, as a first reagent and a hydration compound, as • second reagent which is capable of reacting with the nitrile to convert it to its corresponding amide thereby hydrating the nitrile and / or converting it to its corresponding acid, in a treatment zone; subjecting the nitrile to a catalytic distillation in the treatment zone in the presence of the hydration compound, to hydrate at least part of the nitrile in the corresponding amide and / or to form its corresponding acid; and extracting the amide and / or the acid from the treatment zone. Catalytic distillation in this way involves carrying out a chemical reaction simultaneously with or in combination with the distillation, in a simple treatment zone. The treatment zone in this way will comprise at least one reaction zone in which the hydration reaction of the nitrile to the amide and / or acid is carried out catalytically in the presence of a catalyst, and at least one zone of distillation adjacent to the reaction zone in which the distillation of the reaction product (s) from the reaction zone and / or the unreacted reactants is carried out. In this way, the reaction zone may comprise a packed bed of catalyst particles capable of catalyzing the conversion or hydration of the nitrile to its corresponding amide. Any suitable hydration catalyst can be used, typically a copper or copper-based hydration catalyst, for example a copper oxide or copper-chromium hydration catalyst. The first reagent may comprise an unsaturated or aromatic nitrile, such as acrylonitrile, methacrylonitrile, crotononitrile, allyl anide, or benzonitrile, which will thus be hydrated to the corresponding unsaturated or aromatic acid and / or amide, without a degree being carried out. substantial polymerization. Instead, however, the first reagent may comprise a saturated nitrile, such as acetonitrile, propionitrile, butyronitrile, or isobutyronitrile. The treatment zone will typically be provided in a column or tower, with the catalyst bed providing in a section of the tower. The - ^ E - ^ - ^ teA- distillation zone can thus be provided above and / or below the catalyst bed. Preferably, a distillation zone is provided above and below the catalyst bed. The suitable packaged distillation medium, for example, Raschig rings, or distillation apparatus or apparatus, are then provided in the column below and / or above the catalyst bed, ie, in the distillation zone or zones. The process may include boiling a liquid component in a heat exchange zone operatively connected to a lower end of the treatment zone, to provide the driving force for the catalytic distillation. A portion of the liquid component can then, if desired, be introduced into the treatment zone, for example above or below the catalyst bed. The liquid component can be such that it does not take part in the hydration reaction ie it only provides the driving force for the catalytic distillation and thus aids in the distillation of the reactants and the products in the treatment zone. In such a case, the second reagent can be fed into the treatment zone in a location separate from the point of introduction of the first reagent or nitrile into the treatment zone, for example above the catalyst bed when the nitrile is fed ^^ inside the treatment zone below the catalyst bed. The second reagent must thus be able to hydrate the nitrile under the conditions prevailing in the treatment zone and in the presence of the catalyst. In particular, the second reagent can be water. The liquid component can be an organic compound, such as an alcohol, an aromatic or a paraffin. However, the liquid component can, instead, be such that the hydration reaction takes part. In this way, in particular, it can be the same as the second reagent. In other words, part of the second reagent is then used for heat exchange, while part of it is introduced into the treatment zone as described above. The highest heat exchange of the first and second reagents can be introduced into the treatment zone above the catalyst bed, with the lowest heat exchange being introduced below or above the catalyst bed. In the event that the first reagent or nitrile is the highest heat exchange component, a portion thereof is then introduced above the catalyst bed, while the remainder thereof will boil in the heat exchange zone to provide the driving force for catalytic distillation. The extraction of the amide can be effected as a distillate component or elevated in the upper part of the treatment zone or as a high heat exchange component in the bottom of the treatment zone, for example, from the exchange zone of the treatment zone. heat, depending on the relative heat exchange points of the first and second reagents. The column can have any length of desired width, and is typically in the region of 10 m to 60 long. Typically, its diameter is in the region of 25 mm to 110 mm on an experimental installation scale and greater than 110 m for a commercial scale operation. The catalyst bed can also have any desired length, for example, 0.05-10 m. The pressure in the column can vary widely, for example between 10 kPa (g) and 10,000 kPa (g), and can be controlled by an inert gas such as nitrogen or argon. The pressure, and consequently the reaction temperature, in the column will determine the product produced. Thus, if an amide corresponding to the nitrile that is fed into the column is produced at a given column pressure and thus a specific reaction temperature, the corresponding acid can instead, or additionally, be produced by increasing the pressure of the column and consequently the reaction temperature at which the reaction is carried out, so that an excess hydrolysis or hydrolysis is carried out, thereby forming the corresponding acid. BRIEF DESCRIPTION OF THE DRAWING The figure is a schematic drawing showing a simplified flow chart of a process according to the invention. The invention will now be described in more detail with reference to the accompanying schematic drawing which shows a simplified flow chart of a process according to the invention for producing an amide and / or an acid from a nitrile, like the Examples Subsequent limitations In the drawing, the reference numeral 10 generally indicates a process according to the invention for producing an amide from a nitrile. The process 10 includes a catalytic distillation column 12. The dimensions of column 12 can vary widely, but it is typically around 10m long with an internal diameter of 25mm. A reaction zone 14 is provided within the column 12 so that a distillation zone 16 is provided above the zone 14 while another distillation zone 18 is provided below the reaction zone 14. Reaction zone 14 comprises a supported bed of a copper-based particulate hydration catalyst such as a supported copper-chromium catalyst, a supported copper oxide catalyst or other similar hydration catalyst. Distillation zones 16, 18 are packed with Raschig rings (not shown). A water supply line 20 is directed towards the column 12 above the bed 14, while a nitrile feed line 22 is directed into the column 12 immediately below the bed 14. However, it should be appreciated that the The nitrile feed line 22 can also be directed into the column 12 above the bed 14. A boiler 24 is located below the column 12. An extraction line 26 is directed from the bottom of the column 12 to the boiler 24, while a return line 28 is directed from the kettle 24 back to the column 12. The kettle 24 is equipped with a heater 30, while a line 34 for extracting product is directed from the kettle. During use, sufficient water is introduced into the kettle 24 to fill it up to 30 and 80% in its volumetric capacity, and it is heated. The pressure in column 12 is regulated between 0.1 and 100 bar, as desired, by means of an inert gas such as nitrogen or argon. The water in the kettle 24 is boiled inside the column 12 until a total reflux is reached. In this step, a feed stream of a nitrile, such as acrylonitrile having a heat exchange point lower than water, is introduced into the column 22 along the feed line 22, typically at a rate of between 0.001 and 50 kg per hour, followed by the introduction of water along the flow line 20 at a suitable feed rate, for example between 0.0001 and 100 kg per hour. Typically, the nitrile used as raw material is stabilized against polymerization with radical inhibitors such as hydroquinone or methylated hydroquinone, prior to its introduction into the column. Column 12 is maintained under reflux conditions and a nitrile amide product, together with the excess water, is recovered as the bottom stream along flow line 34, at a rate of 0.002 kg to 150 kg per hour. In simulations of process 10, the following non-limiting examples were conducted in the laboratory. EXAMPLE 1 Pellets of a copper-chromite catalyst in its reduced form (650g), supported in stainless steel wire socks (22 in number), were packed in a 5m section of a catalytic distillation column 12 having dimensions of 10m. of height by 25 mm in diameter. The first upper meter of the column (zone 16) and the lower 4 meters (zone 18) were filled with Raschig rings. Demineralized water was introduced into the kettle 24 to 30% of its capacity. Under a nitrogen atmosphere, the water boiled in the column under atmospheric pressure (85 kPa) until a reflux was reached (96 ° C). Acrylonitrile containing 35 ppm of methylated hydroquinone (MeHQ) was introduced to a feed point (flow line 22) just below the catalyst bed at a rate of 30 g / hour and fed to water (flow line 20) above of the catalytic zone at a speed of 84g / hour. After the introduction of acrylonitrile, the temperature inside the catalyst bed under to the point of heat exchange of the acrylonitrile-water azeotrope (64 ° C). The product solution containing 35% by weight of acrylamide (100% conversion and 100% selectivity) was removed from the kettle along the flow line 34, at a rate of 114g / hour. EXAMPLE 2 Extruded or granulated copper oxide or copper-chromite catalyst in its reduced form (350g), supported in stainless steel wire socks (10 in number) and wrapped in particle separating wire, were packed in the upper section of a catalytic glass distillation column having dimensions of 2. lm height by 35mm diameter. The 600mm bottom of the column was filled with Raschig rings or a structured distillation package. Demineralized water without air was introduced into the kettle at 30% capacity. Under a nitrogen atmosphere, the water boiled in the column under atmospheric pressure (85kPa), until a reflux was reached (96 ° C). The nitrile without air was introduced to a feed point just below the catalyst bed at a rate of 10-25 g / hour, and water was fed into the column above the catalyst zone at the rate required to produce the concentration of the catalyst. desired product. After the introduction of the nitrile, the temperature inside the catalyst bed decreased to the point of heat exchange of the nitrile-water azeotrope. The product solution (25-130 g / h) containing up to 50% by weight of the amide (>90% conversion and selectivity) was removed from the kettle. EXAMPLE 3 Extruded copper oxide catalyst in its reduced form (900g), supported on stainless steel wire socks (22 in number) and wrapped in particle separator wire, were packed in a 8.5m section of a column of catalytic distillation that has the dimensions of lOm of height by 25mm of diameter. The bottom of 1.5m of the column was filled with 10mm Berl polynes. Demineralized water without air was introduced into the kettle at 30% capacity. Under a nitrogen atmosphere of 200 kPa above atmospheric pressure, the water boiled in the column until a reflux was reached (135 ° C). The airless acrylonitrile (containing 35ppm MeHQ) was introduced to a feed point just below the catalyst bed at a rate of 48-152g / hour, and water was fed into the column above the catalyst zone at a rate to produce the required product concentration. After the introduction of the acrylonitrile, the temperature inside the catalyst bed decreased to the heat exchange point of the acrylonitrile-water azeotrope (approximately 104 ° C). The product solution containing up to 50% by weight of acrylamide (> 98% conversion and selectivity) was removed from the kettle at a rate of 200-500 g / hour. EXAMPLE 4 In this example, the arrangement of the column and the packing of the catalyst were the same as for example 3, but the nitrogen pressure inside the column was raised to 400 kPa above the atmospheric pressure, which resulted in that the temperature of the kettle was 158 ° C. When the acrylonitrile (180 g / h) was introduced above the catalyst zone, the temperature in the catalyst zone decreased to 135 ° C-145 ° C and an aqueous solution of acrylic acid was produced (approximately 75 g / h) and acrylamide (approximately 175 g / h).

EXAMPLE 5 Extruded copper oxide catalyst in its reduced form (13.5kg), supported on stainless steel wire socks and wrapped in particle separator wire, were packed in a 7m section of a catalytic distillation column having dimensions of lOm of height per llOmm of diameter. The bottom of 2m of the column was filled with Berl rollers of 10 m. Demineralized water without air was introduced into the kettle at 50% capacity. Under a nitrogen atmosphere of 100 kPa above atmospheric pressure, the water was boiled in the column until a reflux was reached (121 ° C). The airless acrylonitrile containing 35 ppm of MeHQ was introduced to a feed point above the catalyst bed at a rate of 0.05-2.5 g / hour, and water was fed into the column above the catalyst zone at a rate to produce the required concentration of products. After the introduction of acrylonitrile, the temperature inside the catalyst bed decreased to a point of heat exchange of the acrylonitrile-water azeotrope (approximately 89 ° C). The pH of the product solution was controlled between 5.0 and 6.0 by the addition of 0.0125M of sulfuric acid solution inside the kettle. The product solution containing up to 50% by weight of acrylamide (> 98% conversion and selectivity) was removed from the kettle - ~ --------- 1t? Lfa? a speed of 5-30kg / h). The production of amides in nitriles is known by the hydration of nitriles in fixed or batch mixed bed reactors. Three types of reactions are known, 5 mainly: a) Homogeneous reactions, mainly of sulfuric acid, catalyzed. b) Heterogeneous reactions catalyzed by copper or copper oxide mixtures of metal, for example, copper oxide or chromium oxide, as catalysts. c) Reactions in which biocatalysts such as enzymes are used to facilitate nitrile hydration. These reactions are used for the production of 15 amides, such as for the production of an acrylamide monomer of a nitrile such as an acrylonitrile. Such monomers are in turn used for the production of water-soluble polymers and copolymers which are used as flocculants for mining, papermaking auxiliaries, thickeners, surface coatings and improved oil recovery products. The applicant is aware that mainly the catalyzed batch processes of sulfuric acid, the highly exothermic hydration reaction of the nitriles is complicated by the formation of polymers, if the temperature ^ ^ ^ ^ G ^^ reaction and the speeds of the reagent are not carefully controlled. To finish the reaction, the acid is neutralized, and this results in the production of an effluent comprising mainly sulphates contaminated with acrylamide. It is necessary that the highly poisonous acrylamide be crystallized from the residual water and handled as a powder. The Applicant is also aware that processes involving the heterogeneous catalytic reaction are prone to problems of polymerization and separation when using a bedding technology, while low concentrations of acrylamide in water, in the order of 7%, they only occur when simple fixed-bed reactors are used, that is, not a series of reactors. The phase separation limits the amount of acrylonitrile that can be fed to the reactor with water. In this case, unreacted catalyst, acrylonitrile and water have to be removed by filtration and / or distillation to achieve a desired concentration of about 50%. In addition to not being economical with respect to energy use (heat is removed in the reaction step and added once more in the distillation stage), these processes are very expensive since several reactors and distillation towers are required and the purification and concentration of the product. The life time of the catalyst is also limited although the catalyst can in some cases be regenerated by oxidation followed by reduction with hydrogen. The applicant has surprisingly found that by applying catalytic distillation technology to the hydration of amides, many disadvantages of the known processes can be eliminated. The process of the invention is a continuous process, which allows large savings in capital costs (typically a reaction vessel against five reaction vessels with known processes) with little or no effluent production. Another advantage is that the heat of the reaction is partially used to heat the reactants involving lower energy requirements. Since the catalytic distillation is essentially a distillation process, controlling the reaction temperature and thus preventing or inhibiting the unwanted polymerization does not present difficulties. The required concentration of the product (50%) can also be achieved without additional separation processes, and the catalyst life time is improved. Little or no unwanted polymerization is experienced as the product is constantly removed from the heat source. In this way, an aqueous solution of the product at the desired concentration (1% -60%) can be obtained directly from the reactor without requiring additional purification or concentration, while minimizing the energy requirements. In the case of olefinic nitriles, the oligomerization / polymerization does not present problems if the pH is controlled between 3 and 8 since the product is constantly removed from the heat source. The olefinic amides, for example, acrylamides, methacrylamide, crotonamide, and 3-butenamide, which are prepared by the process of this invention can be used as monomers in the polymerization reactions. For example, anionic and nonionic polyacrylamides have been produced from acrylamides prepared by the process of the invention. It is believed that it would also be possible to produce, by means of the process of the invention, acrylamides suitable for the production of cationic polyacrylamides.

Claims (15)

1. CLAIMS 1. A process for producing an amide and / or acid from a nitrile, whose process is characterized in that it comprises: introducing a nitrile, as a first reagent, and a hydration compound, as a second reagent that is capable of reacting with a nitrile to convert it to its corresponding amide in this way by hydrating the nitrile and / or converting it to its corresponding acid, in a treatment zone; subjecting the nitrile to a catalytic distillation in the treatment zone in the presence of the hydration compound to hydrate at least part of the nitrile to the corresponding amide and / or to form its corresponding acid; and extracting the amide and / or the acid from the treatment zone. The process according to claim 1, characterized in that the treatment zone comprises at least one reaction zone in which the hydration reaction of the nitrile to amide and / or acid is carried out catalytically in the presence of a catalyst , and at least one distillation zone adjacent to the reaction zone in which the distillation of the reaction product (s) from the reaction zone and / or the unreacted reactants is carried out, with the reaction zone comprising a packed bed of particles of a copper hydration catalyst or copper based. 3. The process according to claim 5 2, characterized in that the first reagent comprises an aromatic or unsaturated nitrile which in this way hydrates the corresponding amide and / or aromatic or unsaturated acid. 4. The process according to claim 2 or 3, characterized in that the treatment area is 10 provides in a column or tower, with the catalyst bed placed in a section of the tower, and with a distillation zone being provided above and below the catalyst bed. The process according to claim 15 2 or 3, characterized in that it includes boiling a liquid component in a heat exchange zone operatively connected to a lower end of the treatment zone, to provide the driving force for the catalytic distillation , with a portion of the liquid component 20 optionally being introduced into the treatment zone above or below the catalyst bed. 6. The process according to claim 5, characterized in that the liquid component is such that it does not take part in the hydration reaction and only provides 25 the driving force for the catalytic distillation, of this -w --- - ¡- Éi-ñteSii ----- mode aiding the distillation of reagents and products in the treatment zone, feeding the second reagent into the treatment zone in a location separate from the introduction of the first reagent into the treatment zone. The process according to claim 6, characterized in that the second reagent is water and wherein the liquid component is an organic compound. 8. The process according to claim 5, characterized in that the liquid component and the second reagent are water, so that the liquid component takes part in the hydration reaction. The process according to claim 2 or 3, characterized in that the highest heat exchange of the first and second reagents is introduced into the treatment zone above the catalyst bed, with the lowest heat exchange thereof being introduced. below the catalyst bed. The process according to claim 4, characterized in that it includes boiling a liquid component in a heat exchange zone operatively connected to a lower end of the treatment zone, to provide the driving force for the catalytic distillation, with a portion of the liquid component optionally being introduced into the treatment zone above or below the catalyst bed. 11. The process according to claim 4, characterized in that the highest heat exchange of the first and second reagents is introduced into the zone of 5 treatment above the catalyst bed, with the lowest heat exchange thereof being introduced below the catalyst bed. 12. The process according to claim 5, characterized in that the highest heat exchange of the first and second reagents is introduced into the treatment zone above the catalyst bed, with the lowest heat exchange thereof being introduced below the catalyst bed. The process according to claim 15, characterized in that the highest heat exchange of the first and second reagents is introduced into the treatment zone above the catalyst bed, with the lowest heat exchange thereof being introduced below the catalyst bed. 14. The process according to claim 7, characterized in that the highest heat exchange of the first and second reagents is introduced into the treatment zone above the catalyst bed, with the lowest heat exchange thereof being 25 introduced under the catalyst bed. ^ - ^ - ^ ------ ~ '"ji-? Miift i 15. The process according to claim 8, characterized in that the highest heat exchange of the first and second reagents is introduced in the zone of treatment above the catalyst bed, with the lowest heat exchange thereof being introduced under the catalyst bed. A.-Jriaiittlt