Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
  • B01J27/20—Carbon compounds
  • B01J27/22—Carbides

Definitions

• ABSTRACT A process for producing secondary alkyl primary amines from n-paraffins where a portion of the paraffin is nitrated to nitroparaffin along with the formation of nitrated and oxygenated by-products, where the nitroparaffin is substantially hydrogenated to the amine, and where the amine is separated from a mixture composed of unreacted paraffin, nitroparaffin, and by products, which comprises catalytically hydrogenating the mixture composed of paraffin, nitroparaffin and by-products in a plurality of zones where the initial hydrogenation is conducted at a temperature of from about 250 to 500F., where hydrogenation in a subse quent zone is conducted at a temperature of from about 600 to 750F. and recycling the hydrogenated product for nitration with the n-paraffin.
• This invention relates to the production of amines and more specifically to the production of secondary alkyl primary amines having from 6 to 30 carbon atoms from paraffin hydrocarbons.
• this invention relates to a continuous process for the production of high purity secondary alkyl primaryamines from paraffin hydrocarbons.
• the principal source of by-products is derived from the initial nitration involving reaction between the nitrating agent, such as nitrogen dioxide, dinitrogen tetroxide and nitric acid, and the paraffin.
• the nitrating agent such as nitrogen dioxide, dinitrogen tetroxide and nitric acid
• the paraffin in addition to the principal nitroparaffin product, there is produced through a series of complex mechanisms a plurality of other materials including nitrites, nitrates, olefins, ketones, alcohols, acids and polyfunctionals, such as nitroalcohols, dinitroparaffins, nitroketones and nitroolefins.
• the mixture of paraffin,'nitroparaffin and by-products was hydrogenated at temperatures of from about 450 to 600F. under hydrogen pressures of from 200 to 4,000 p.s.i.g. in the presenceof known and conventional hydrogenation catalysts. Temperatures below 450F. were taught as not giving appreciable hydrogenolysis and temperatures in excess of 600F. were to be avoided as the same caused undesirable isomerization, cracking and coking of the hydrocarbons. Further, the oxygenated by-products such as alcohols are dehydrogenated to undesired olefins. Consequently, hydrogenating the mixture in accordance with the known procedure provided only partial hydrogenolysis of the mixture such that a considerable amount of incompletely converted by-products are recycled to the initial nitration reactions.
• Another object of'this invention is to provide a process for the production of secondary alkyl primary amines from n-paraffins wherein the by-product content of recycle stream is substantially reduced.
• Yet another object of this invention is to provide a process wherein secondary alkyl'primary amines are prepared from n-paraffins by means of a continuous process wherein the byproduct content in the recycle stream is substantially reduced and where the amines are recovered in high purity.
• this invention contemplates a process for producing secondary alkyl primary amines from nparaffins wherein a portion of the n-paraffin is nitrated to form a nitroparaffin along with nitrated and oxygenated by-products, where the nitroparaffin is substantially hydrogenated to the amine and where the amine is separated from a mixture of' unreacted paraffin, unconverted nitroparaffm and by-products, the improvement which comprises:
• subsequent hydrogenation of the mixture is conducted at a temperature of from about 600 to 750F., preferably from about 650 to 710F.;
• the mixture of unreacted n-paraffin, nitroparaffin and by-products hydrogenated and recycled in accordance with the instant invention is derived from a paraffin hydrocarbon or paraffin hydrocarbon mixtures containing from 6 to 30 carbon atoms, initially nitrated and subsequently hydrogenated to the corresponding amine.
• Typical paraffin hydrocarbons include n-hexane, n-heptane, n-octane, n-decane, n-dodecane, n-tetradecane, n-pentadecane, n-o ctadecane, n-eicosane,
• urea or solvent dewaxing which are capable of recovering n-paraffins from mixtures of isoparaffins, naphthenes, aromatics and n-paraffins.
• Mixtures of n-paraffins having from 6 to 10, or to 14, or 14 to 17 carbon atoms can be obtained by absorption of molecular sieves.
• mixtures containing from to 21 carbon atoms, or to carbon atoms can be obtained by means of urea or solvent dewaxing and are also contemplated as starting materials.
• the nitration of the paraffin hydrocarbons to secondary mono-nitroparaffms is conducted in a liquid-vapor process.
• the paraffin hydrocarbon along with the upgraded recycle hydrogenated stream provided herein is contacted with a nitrating agent, such as nitrogen dioxide, dinitrogen tetroxide or nitric acid, at a temperature of from about 250 to 500F. at pressures ranging from atmospheric to 20 atmospheres thereby converting from about 5 to about 50 per cent of the paraffin hydrocarbon principally to the corresponding secondary mono-nitroparaffin.
• a nitrating agent such as nitrogen dioxide, dinitrogen tetroxide or nitric acid
• Illustrative mono-nitroparaffms include 2 or 3- nitrohexane, 2, 3 or 4-nitroheptane, 2, 3 or 4-nitrooctane, 2, 3, 4 or S-nitrodecane, 2, 3, 4, 5 or 6-nitroundecane, 2, 3, 4, 5 or 6-nitrododecane, 2, 3, 4, 5, 6 or 7-nitrotridecane, 2, 3, 4, 5, 6 or 7-nitrotetradecane, 2, 3, 4, 5, 6, 7, 8 or 9-nitrooctadecane and mixtures thereof.
• the amount of nitrating agent employed can vary within wide limits, as for example, from about 0.05 to 0.55, preferably 0.1 to 0.3, moles of nitrating agent per mole of paraffin.
• nitrating agent can be recovered alongwith, for example, nitric oxide, a gaseous reaction by-product, the latter in continuous operations subsequently oxidized to nitrogen dioxide and the nitrating agent stream recycled for reintroduction into the nitration reaction zone.
• reaction by-products including C to C ketones, alcohols, carboxylic acids, nitrites, nitrates and multifunctional by-products, such as dinitroparaffins, nitroalcohols, nitroketones, nitroolefins, nitroacids and trinitroparaffins.
• by-products are carried along in the liquid crude nitration product after separation of such off-gases as nitrogen, nitrous oxide, carbon dioxide, carbon monoxide, nitric oxide, water and unreacted nitrating agent.
• the crude nitrated liquid product typically comprises from 5 to weight percent nitroparaffin and from 0.5 to 15 weight percent by-products.
• the secondary mono-nitroparaffins described above contained in the crude liquid nitrated product are substantially hydrogenated to secondary alkyl primary amines at average conversion temperatures ranging from about 100 to 450F. in the presence of conventional and well-known hydrogenation catalysts.
• the crude liquid product is caustic washed in an aqueous medium prior to the hydrogenation where some of the by-products deleterious to hydrogenation catalyst life are removed.
• the crude liquid hydrogenated product comprises C to C n-paraffin, secondary alkyl primary amine and lesser amounts of secondary alkyl secondary amine, alcohols, ketones, unconverted nitroparaffin, water and polyfunctionals such as nitroamines, aminoketones and aminoalcohols.
• Conventional recovery procedures may be employed for recovering the desired primary amine as by distilling the hydrogenated product by stepwise fractionation.
• the amine may be converted and recovered as an amine salt by reaction of the crude liquid product with an inorganic acid followed by further treatment of the amine salt with alkali and thereafter recovering the primary amine by distillation.
• the amine containing liquid hydrogenation product is treated with carbon dioxide at about 15 to C.
• Separation employing a strong inorganic acid extracts both primary and secondary amines which can be subsequently separated by distillation after neutralization.
• the solvent phase is thereafter heated to about 60 to C., or alternative the pressure of the solvent phase is reduced, thereby springing the amine and flashing off carbon dioxide and a portion of the solvent.
• the amine is recovered from residual solvent by distillation or a combination of distillation and decantation and the purity of the amine recovered is in excess of 98 weight per cent.
• the unreacted nitroparaffin and by-products of the nitration and hydrogenation reactions in admixture with the paraffin separated above are upgraded and made suitable for recycle and introduction to the initial nitration reaction by means of a plural stage hydrogenation treatment.
• the recycle mixture contemplated for hydrogenolysis in accordance with the instant invention is predominantly C to C n-paraffin containing from 0 to 5 weight per cent unconverted nitroparaffin and from 0.5 to 15 weight per cent of all byproducts.
• Representative of the by-products are C and C oxygenated, nitrated or nitrooxidized materials illustrated by alcohols, ketones and polyfunctionals including nitroketones, nitroalcohols, nitrates, nitrites and dinitroparaffins.
• the mixture may also contain aminated by-products such as secondary amines, aminoketones, aminoalcohols and unextracted amine product.
• the feed for the plural stage hydrogenation treatment can also include such by-product streams from the process as, for example, the bottoms from the amine distillation which consist of primarily secondary amines and polyfunctional products as aminoalcohols or aminoketones.
• the organic material sprung with acid from the caustic extract generated in contacting the crude nitration product contains organics which can be converted to paraffins for recycle and the paraffin stream derived from the initial vacuum distillation of the crude amines can be added to the recycle mixture intended for hydrogenolysis.
• the mixture can contain some or all of the aforementioned by-products in varying amounts depending upon the conditions and reaction employed for the initial nitration of the paraffin, the subsequent hydrogenation of the nitroparaffin to primary amine and the procedure employed for separating and recovering the secondary alkyl primary amine.
• the stream suitable for recycle is provided by catalytically hydrogenating the mixture in a plurality of zones where initial hydrogenation is conducted at a temperature of from about 250 to 500F., preferably between about 350 and 475F., for a time of sufficient duration whereby unconverted nitroparaffins are hydrogenated to amines and unstable oxygenates such as nitrites and nitrates are converted to more thermally stable forms.
• the initial hydrogenation converts the nitroparaffin and unstable oxygenated by-products to, for example, amines, am ides, diamines and alcohols.
• the mixture is subsequently hydrogenated at a temperature of from about 600 to 750F., preferably between about 650 and 710F., for a time of sufficient duration whereby primary amines, secondary amines, alcohols, ketones, aminoalcohols, amides, and diamines contained in the mixture are substantially converted to n-paraffins.
• An additional hydrogenation treatment may in some instances be desirable as, for example, where the liquid product hydrogenated at about 600 to 750F. is found to contain small amounts of olefins.
• Such an additional hydrogenation treatment can be conducted at from about 450 to 650F. whereby the olefins are converted to n-paraffin.
• each of the plural reaction zones is undertaken in the presence of hydrogen pressures ranging from about 100 to 1,500 p.s.i.g. for periods of from 0.1 to 5 hours.
• the mixture can be introduced into each of the plural zones at space velocities of from 0.2 to 10 v./v./hr.
• Conventional hydrogenation catalysts can be employed in each zone as, for example, nickel, cobalt, molybdenum, platinum, palladium and rhodium.
• the catalysts may be supported on kieselguhr, silica, carbon or alumina as is known in the art.
• a highly preferred catalyst is composed of nickel-molybdenum or cobalt-molybdenum on an alumina support.
• the plural stage hydrogenation of the mixture ultimately intended for recycle provides an improved and upgraded material having an n-paraffin content of 99 weight per cent and higher.
• the purity of the recycle material is related to the plural zone hydrogenation described above in that the mixture separated from the amine while originally unstable to temperatues of 600F. and higher with regard to components therein being subject to isomerization, cracking and coking, can be subjected to such elevated temperatures if the initial hydrogenation at the lower temperatures is previously undertaken. It is believed that the components responsible for the lack of staiblility at temperatures of 600F. and higher are the unconverted nitroparaffin and oxygenated by-products which according to the instant invention are essentially converted to forms more stable to elevated temperatures thereby deterring cracking, isomerization and coking.
• the instant process embodying the improvements related to upgrading recycle stream provides a highly selective process for the production of secondary alkyl primary amines.
• These amines can be employed as mold-release agents, emulsion freeze-thaw stabilizers, pigment dispersing agents, polyurethan catalysts and anti-caking anti-dusting agents.
• the amines can also be used as corrosion inhibitors, deleterious bacterial control agents, sludge dispersants and as detergents and deicers in gasolines.
• EXAMPLE I A continuous process for converting n-paraffins to secondary alkyl primary amines is undertaken by providing a fresh water-white C to C n-paraffm hydrocarbon composition having the following carbon chain length distribution on a weight per cent basis: C 11.1, C 28.7, C 32.2, c 26.9, C 1.1. To 10.7 weight per cent of fresh normal paraffins there is mixed 89.3 weight per cent of previously processed and upgraded recycle paraffins according to the instant invention.
• the washed nitrated product contains 129 pounds per hour of nitrated paraffin and 833 pounds per hour of n-paraffin and other materials that include 0.43 weight per cent ketones, 0.95 weight per cent nitrites and 0.41 weight per cent nitrates.
• the crude nitrated paraffin composition is introucked at an inlet temperature of 200F. to a hydrogenation reactor containing a hydrogenation catalyst composed of one weight per cent palladium on carbon at a liquid hourly space velocity of 2.0 volumes ofliquid per volume of catalyst per hour. Hydrogenation is conducted under a hydrogen pressure of 560 p.s.i.g. and up to a maximum conversion temperature of 410F. Following hydrogenation; substantially all of the nitroparaffin is reduced. to amine. Hydrogen, ammonia and some water are removed as gases and remaining water and ammonia are decanted from the recovered crude hydrogenation product at 110F.
• the carbon dioxide saturated-crude hydrogenation product is countercurrently contacted in a tower with 1,500 pounds per hour of a solvent mixture comprising 40 per cent methanol and 60 per cent water, the solvent mixture having been previously saturated with 50 pounds per hour of carbon dioxide at 300 p.s.i.g. and 110F.
• the primary amine complex transfers from the predominantly paraffin stream to the solvent stream.
• the amine depleted paraffin stream is subsequently reduced to atmospheric pressure in a flash drum whereupon carbon dioxide therein is removed overhead.
• the amine-enriched solvent stream is heated to a temperature of 150F. and introduced to a flash tower maintained at atmospheric pressure where carbon dioxide, along with some methanol and water, is removed overhead.
• the amine-rich liquid from the flash tower is passed through a fractionator where methanol, residual carbon dioxide and some water are removed overhead.
• the bottom stream containing water and crude amines separates as two phases, namely a water phase containing some methanol and amines, and a crude amine phase containing some water.
• the amber colored amine-depleted paraffln stream from the rafflnate flash drum is combined with the predominantly paraffinic waste streams derived from vacuum distilling the crude amines to form a recycle stream comprising about 98 weight per cent n-paraffin, 0.15 weight per cent nitroparaffins and about 1.85 weight per cent by-products.
• the mixed recycle stream is introduced into an initial hydrogenation zone at the rate of -840 pounds per hour and hydrogenated at 400F. with 17 pounds per hour of hydrogen at 500 p.s.i.g. at a liquid hourly space velocity of 3.0 in the presence of a nickel-molybdenum on alumina catalyst.
• the product of the initial hydrogenation zone is introduced into a subsequent hydrogenation zone at the rate of 840 pounds per hour and hydrogenated at 660F. with 16 pounds per hour of hydrogen at 500 p.s.i.g. at a liquid hourly space velocity of 1.5 in the presence of a nickel-molybdenum on alumina catalyst.
• the hydrogenated water-white product is essentially free of nitrated and oxygenated by-products, contains 3 ppm of nitrogen, possesses a Bromine Index of 41 and is recycled for introduction to the nitration reactor.
• the system for producing the amines continues to operate for long periods of time without interruption.
• EXAMPLE IV An amine-depleted n-paraffin stream containing 1.4 weight per cent nitroparaffin and 0.5 weight per cent of carbonyl compounds was passed over a bed of porcelain saddles at a liquid hourly space velocity of 0.6 together with hydrogen introduced at the rate of 2,200 SCF hydrogen per barrel of liquid feed and at temperatures of 450 and 550F. for periods of 8 hours.
• the product contains about 0.4 per cent nitroparaffin and at 550F. no nitroparaffin.
• No amines are formed and the carbonyl concentrations are not decreased at either 450 or 550F.
• the porcelain saddles are blackened in 8 hours at 450F., a thick gummy black residue is formed at 550F.
• a feedstock comprising 0.7 weight per cent amine bottoms, 0.7 weight per cent of oxygenated paraffins sprung from the caustic extract stream and 98.6 weight per cent of amine-depleted paraffin, the feedstock having a Bromine Index of 108, a Total Base Number of 0.97 and Total Nitrogen of 580 p.p.m., is hydrogenated in two stages at 500 p.s.i.g. and with a hydrogen flow of 3 SCF per pound of charge.
• the catalyst used in each stage is nickel-molybdenum on alumina.
• the initial stage reactor operates at 400F. and 3.0 weight hourly space velocity and the subsequent stage reactor is operated at 700F. and 1.5 W.I-I.S.V.
• the product formed after initial and subsequent hydrogenation has a Bro mine Index of 262, a Total Base Number of 0.03 and Total Nitrogen of 2 p.p.m.
• the Bromine Index is reduced to below 50 and the color of the product is water-white.
• a process according to claim 1 wherein said subsequent hydrognation is conducted at a temperature of from about 650 to 710F.
• step (a) is conducted in said zones at a liquid hourly space velocity of 0.2 to 10.
• a process according to claim 1 wherein said nitroparaffin and by-products are aqueous caustic washed, recovering an aqueous solution, separating organic materials from said aqueous solution and introducing said organic materials to said mixture in (a).

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Citations (1)

• 1973
  • 1973-12-26 US US428641A patent/US3917706A/en not_active Expired - Lifetime
• 1974
  • 1974-09-24 CA CA209,908A patent/CA1029040A/en not_active Expired
  • 1974-10-21 GB GB4551774A patent/GB1438216A/en not_active Expired
  • 1974-11-11 NL NL7414654A patent/NL7414654A/xx not_active Application Discontinuation
  • 1974-11-28 JP JP49135939A patent/JPS5095212A/ja active Pending
  • 1974-12-20 BE BE151837A patent/BE823733A/xx unknown
  • 1974-12-23 BR BR10757/74A patent/BR7410757D0/pt unknown
  • 1974-12-23 FR FR7442452A patent/FR2256148B1/fr not_active Expired
  • 1974-12-23 DE DE2461075A patent/DE2461075C3/de not_active Expired
  • 1974-12-23 IT IT30948/74A patent/IT1027988B/it active
  • 1974-12-23 ES ES433275A patent/ES433275A1/es not_active Expired

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