CA2178700A1 - Process for producing aromatic amines by gas phase hydrogenation and a catalyst useful therefor - Google Patents
Process for producing aromatic amines by gas phase hydrogenation and a catalyst useful thereforInfo
- Publication number
- CA2178700A1 CA2178700A1 CA002178700A CA2178700A CA2178700A1 CA 2178700 A1 CA2178700 A1 CA 2178700A1 CA 002178700 A CA002178700 A CA 002178700A CA 2178700 A CA2178700 A CA 2178700A CA 2178700 A1 CA2178700 A1 CA 2178700A1
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- Prior art keywords
- catalyst
- hydrogen
- graphite
- support
- palladium
- Prior art date
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- 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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
- B01J23/44—Palladium
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
- C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
- C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
- C07C209/36—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups by reduction of nitro groups bound to carbon atoms of six-membered aromatic rings in presence of hydrogen-containing gases and a catalyst
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
- Catalysts (AREA)
Abstract
Aromatic amines are produced by catalytic hydrogenation of nitroaromatic compounds in the gas phase. The catalyst is palladium on a graphite or a graphite-containing coke support. From 30 to 6000 equivalents of hydrogen are fed to the catalyst for each equivalent of nitro groups.
Description
LeA 31 091 -Foreign Countries A PROCESS FOR PRODUCING AROMATIC
AMINES BY GAS PHASE HYDROGENATION
AND A CATALYST USEFUL THEREFOR
BACKGROUND OF THE INVENTION
The present invention relates to an improved process for producing aromatic amines by catalytic h~dluu~lldliùll of ~ ludlullldliu compounds in the gas phase and to a new catalyst which is useful in this process.
Aromatic amines are known to those skilled in the art as important intermediates for the production of dyes polyurethanes and plant protection products.
Various procedures for the hyd~uytlndlioll of ~ u~ el1e and other ~ UdlUllldli~ compounds are known to those skilled in the art. Due to the high enthalpy of reaction which is released during these known ~, u~ sesl they are usually conducted in reactors equipped with . integrated heat transfer systems. Examples of some of these known procedures are hyd, U9t:1 Idliul~ in the liquid phase on suspended catalysts such as Pd catalysts (described in EP 476,404) h~lug~l~dliullin the gas phase onfluidized solid catalysts (disclosed in U.S. 3136 818) h~ u~lldliul1in the gas phase over fixed catalysts such as supported Pd catalysts (described in DE-A 2,244 401 2 849 002 and 4,039 026).
DE-A 2 244 401 and 2 849 002 describe Pd catalysts on alumina supports which are operated as fixed catalyst beds in heat e,~..l Idl ,g~, tubes under normal pressure at loadings of less than 1 9 I ~ ub~ e 25 (NBz)/ml (cat)/hour at low hydrogen/nitrobenzene ratios. Between 6 and 11 moles of hydrogen are used for each mole of llillu~
DE-A 4 039 026 describes Pd catalysts on graphitic supports which are operated under conditions similar to those used for Pd catalysts on alumina. These ca alysts provide ill~ulll~ conversion at Le A 31,091 -2- 2, 7~700 loadings cullsid~ldL,ly less than 1 9 (NBz) / ml (cat)/ hour and at a hyd~ug~ ' u~e,l~"e ratio of from 14 to 26 moles to 1 mole. Between 1000 and 4000 ppm r, ' uue"~ e, with respect to the aniline formed, are fûund in the colldt:, ISdl~.
Both an increase in the loading of lli~lUdlUllldLiC compound and an increase in the ratio of hydrogen to nitroaromatic compound increase the volume flow through the bed and thus reduce the dwell time on the contact catalyst. It would therefore be expected that both of these measures would lead to an increase in the breakthrough of the llilludlullldlic compound (i.e., to incomplete conversion).
A general measure of this gas flow through the catalyst bed is the gas hourly space velocity (GHSV), expressed in hour 1.
Even small amounts of lI 'ludlullldlk, compounds in aromatic amines cause signlficant ~ ,cul~ldliul, of the aromatic amine which is otherwise colorless. Such nitroaromatic compounds are therefore u~de~ dule. Separation of l~i~ludlullldliu compounds by distillation is costly in terms of both equipment and energy.
In each of these known processes, the high heat of reaction has to be withdrawn from the reactor via an expensive heat transfer system.
H~lu~el~dliu" processes in the gas phase with simple adiabatic catalyst packed beds are particularly economical, due to the simple construction of the apparatus with reactors that do not include integrated heat ~x-:l Idl ,g~l systems. In an adiabatic type of process, the highly ~xull ~e~ iu nature of the hy.ll u~l ldliul~ of nitro groups imposes particular demands on the catalyst. Due to the col~sid~,dùl~ exothemm, there is a lar~e temperature difference between the beginning and the end of the catalyst. In order to control this temperature difference in an adiabatic process, a heat transfer medium (generally hydrogen in h~dlu~u~lldliull processes) is admixed with the mixture of starting materials resulting in very short dwell times or high GHSVs. This means that the catalyst must 2 1 7870(~
L~: A 31 091 3 be both active and selective over a very large temperature range in order to achieve complete conversion of "il,ube"~ne to aniline even at low UU~ le loadings.
~iUMMARY OF THE INVENTION
It is an object of the present invention to provide a h~ ugelldli catalyst which can be more highly loaded than the known catalysts.
It is also an object of the present invention to provide a h~l ug~l Id~iUI I catalyst which exhibits a higher selectivity than the known prior art catalysts.
It is another object of the present invention to provide a hy~JI us ~l Id~iUI I catalyst which can be used in simple reactor constructions.
It is a further object of the present invention to provide a hyd,uut:l~d~iu, I catalyst having a long service life.
It is also an object of the present invention to provide a hydlUy~lldliUI, process in which extraction of heat from the catalyst bed with an additional heat transfer system is not necessary.
These and other objects which will be apparent to those skilled in the art are accu",~ 71led by h~dlu~u~:lld~il,g ~, udlurlld~i~; compounds in :20 the gas phase in the presence of a Pd catalyst on a graphite or a graphitic carbon support and large excesses of hydrogen. This process may be carried out in simple adiabatic reactors.
~ETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention relates to a process for producing aromatic amines l~pl~ d by the formula 2~3NH2 (1) R
2 ~ 7~700 ~e A 31,091 4_ in which R' and R2, i~l~e~ d~ y of each other, represent hydrogen, a methyl group or an ethyl group and R' may also represent an amino group, by the hydlu~ lldliull of ~ udlullldli~; compounds rt,u,~su,,~d by the formula R~No2 (Il) in which R2 and R3, il Id~,ut:l ,de, Illy of each other, represent hydrogen, a methyl group or an ethyl group and R3 may ad.iiliu, I...ly 1 û represent a nitro group with hydrogen over fixed catalysts in the gas phase. The catalyst used is palladium on a graphite or a graphitic coke support. The graphite or graphitic coke support has a BET specific surface of from û.2 to 1û m2/g.
The catalyst has a palladium content (based on the total weight of catalyst) greater than 1.5% by weight and up to 7% by weight, preferably from 1.6 to 6% by weight, most preferably from 1.9 to 5% by weight.
From 3û to 6ûûû, preferably from 5û to 3ûûû, more preferably from 8û to 1ûûû, most preferably from 1ûû to 3ûû equivalents of hydrogen for each equivalent of nitro groups are fed to the catalyst.
2û The present invention also relates to a catalyst having a graphite or a graphite-containing coke support. The graphite or graphite-~.ullldillillg support has a BET specific surface of from û.2 to 1û m2/g.
The palladium is deposited on the support by illl~ ul ldLiol~ with a suitable palladium-containing solution. The palladium content of the 2 1 7~700 L~! A 31,091 catalyst is from greater than 1.5% (e.g., 1.5001%) by weight up to 7% by weight (based on the total weight of catalyst). The preferred lower limit of the Pd content is 1.6% by weight, most preferably 1.9% by weight.
The preferred upper limit of the Pd content is 6% by weight, most 5 preferably 5% by weight.
Graphite-containing materials are used as the support for the catalysts of the present invention. Suitable support materials include graphite itself (e.g., t~le-:tlUyld,UIlil~) and cokes such as needle coke 2nd petroleum coke. These supports have BET specific surfaces of from 0.2 10 to 10 m2/g.
The catalyst is prepared by depositing palladium on the support in from 1 to 50, preferably from 2 to 30, most preferably from 4 to 10 impregnation steps. ~etween each illl,Ult::~Jlld~iUIl step the catalyst support is dried in a hot gas stream, preferably a stream of air or 15 nitrogen.
The catalysts of the present invention may be prepared by depositing palladium in the form of suitable salts on the support material in the form of tablets, spheres, lengths of granulated material, Raschig rings, Pall rings, cart wheels or honeycomb structures of d~ameters from 20 1 to 30 mm. A plurality of illl,Ul~JlldliUI~ steps may be used with drying after each d~posiLiu". Drying is effected in an air current at temperatures of from 30 to 140C, preferably from 30 to 60CC and preferably under nonmal pressure. Aqueous and organic solvents and mixtures thereof may be used for the illlpl~ylld~iull of the support. Examples of solvents 25 which may be used include water, NH3, simple alcohols, amines, ketones, esters, cyclic ethers, lldlug~lld~t:d hydro-carbons and nitriles.
Specific examples of organic solvents include methanol, ethanol, propanol, isopropanol, ethylamine, isopropylamine, acetone, methyl ethyl ketone, dioxane, methylene chloride, acetonitrile and cull~,udldble ao solvents. Examples of suitable palladium salts include palladium chloride, 2 ~ 7~700 Le A 31,091 -6-palladium nitrate, palladium acet~ldc~Lu,~d~, palladium acetate and amine wlllpi~ S of palladium The catalyst pl~:pdldLiùll is preferably carried out without the use of halogens in the solvent or the metal salt used. After illlpl~ dliul~ and final drying, the catalyst of the present 5 invention is ready for use.
Before it is first placed in operation, the catalyst is generally activated by treating it with a flow of hydrogen at 1 to 10 bar and temperatures of from 250 to 450C (preferably from 300 to 400C) for from 1 to 50 hours (preferably from 5 to 30 hours).
The hydlug~lld~iun process of the present invention is conducted at a pressure of from 1 to 30 bar, preferably from 1 to 15 bar, most preferably from 1 to 7 bar.
The gaseous mixture of starting materials wntaining the nitroaromatic compound and hydrogen is at a temperature of from 20û to 400C, preferably from 230 to 370C, most preferably 250 to 350C, upstream of the catalyst bed. The maximum catalyst temperature is 600C, preferably 55~C, more preferably 500C, most preferably 460C.
The catalyst of the present invention may be used in reactors without a system for the removal of heat.
The short dwell times or high GHSVs of the process of the present invention are particularly l~,,,dlhd~le. These short dwell times make it possible to use catalyst loadings of from 0.5 to 40 kg, preferably from 1 to 30 kg, most preferably from 2 to 20 kg of l~i~lUdlUllld~iU compound per liter of catalyst per hour.
The space-time yields which can be obtained are therefore an order of magnitude higher than those of the known processes for the h~,~,u~elld~iu" of nitroaromatic compounds. Such higher space-time yields are particularly important for the economic production of large quantities of aromatic amine because only small amounts of catalyst and ~0 .,ull~:,,uul~dillgly small reactors are required.
21 7g700 A 31,091 7 Another important advantage of the process of the present invention is the quantitative conversion of the llilludlullldli~ compound which is surprisingly and ~l ,e,x,oeule~ly obtained, even at the high loadings used.
The process of the present invention is also distinguished by the absence of a so-called catalyst induction phase and by its selectivities which are higher than 99.4% from the outset.
In the process of the present invention, the conversion of nltroaromatic compound is higher than 99.95%, preferably higher than 99.99%, more preferably higher than 99.995%, most preferably higher than 99.999%. This should not, however, be ~l ld~ uod as being : limiting because any desired lower degree of conversion can be achieved by selection of the d,U,UlUplidl~ process conditions.
The catalysts of the present invention can be used in any reactor having a fixed catalyst bed.
One industrial implementation of the process can be described as follows:
The catalyst is fixed in an adiabatic reactor of known design (See Ullmann, EnzykloPadie der l~-.l " li~ l Çhemie [Ullmann's Encyclopedia :20 of Industrial Chemistry~, 4th Edition, Volume 3, pages 468-649; and Kirk-Othmer, EncvcloPedia Qf Chemical Technoloav. Vol. 19 (1982), pages 880-914, for example.). However, the catalyst may also be distributed between a plurality of reactors which are cu"lle~ d in series or in parallel. These reactors may be any of those known in the art to be :25 useful for the oxidation of methanol to roll"dld~l"/de, for example.
The packed catalyst beds are provided on or between gas-permeable walls, as in the prior art. Satisfactory gas distribution must be ensured.
Instead of being used as a bulk packing, the catalyst may also be prepared and used on suitable packings as a support material.
Le A 31,091 Fresh ~ UdlUllldli~ compound is metered into the circulating gas stream which is ~""ùosed primarily of recycled and freshly added hydrogen upstream of the catalyst packing. It is preferred however that the nitroaromatic compound be completely volatilized in the fresh hydrogen before being introduced in gaseous form into the circulating gas stream. After passing through the catalyst bed the product gas is cooled with the recovery of steam. The steam may be recovered by means of any of the heat e~.l,d"~e,~ known to those skilled in the art.
Thereafter the product gas is cooled to remove the aromatic amine and the water of reaction from the reaction mixture by, u,,de,,~dLiu,l. The remaining circulating gas is recycled after removing a small amount of gas for the outward transfer of gaseous constituents in the circulating gas. Before recycling the circulating gas should generally be preheated to its inlet temperature and admixed with fresh starting material.
The above d~s~i,uLiu" of one ~",bodi",~"l of the present invention is of an elementary nature and should not have a limiting effect or be judged as limiting.
The process of the present invention is particularly suitable for the h~,d,u~elld~iù,l of l,il,uL~ e or nitrotoluene.
The process of the present invention makes it possible to use catalyst loadings or GHSVs which are extremely high (i.e. higher by a power of ten than those of the prior art). Despite these high catalyst loadings however selectivities greater than 99.4% are obtained with complete conversion even at the commencement of the reaction. The catalysts of the present invention exhibit the greatest productivity achieved without production l 'I .I,~aPc due to catalyst deactivation.
The invention is further illustrated but is not intended to be limited by the following Examples in which all parts and p~l~llldU~:S are parts by weight or p~, ,e"ld~es by weight unless otherwise specified.
L~ ~ 31,091 9 E~AMPLES
The GHSV (gas hourly space velocity), u~ se"l~ the hourly space velocity of the gas under normal conditions or at a given pressure, wlth respect to the empty volume which the packed catalyst bed 5 occupies.
Catalvst ~ Udl~iull EG 17 granulated graphite supplied by Ringsdorff which had a BET specific surface of about 0.4-0.8 m2/g, was used as the support material. The grain size was between 1 and 3 mm and the tap density 10 was from 650 to 1000 9/l.
Results similar to those reported below have also been obtained with other graphites and graphite-containing materials having a low BET
speclfic surface.
The catalysts used in the Examples which follow were prepared in 15 the following manner:
EG 17 granulated graphite with an ~LJSOIIJ~IICY of 7 ml au~ il,ile per 100 9 support was placed in a rotatable vessel and mixed, by rotation, with a solution of palladium acetate in ~Le~u"il,ile. The mixture was agitated until the solvent had been completely absorbed by the 20 support. Thereafter, the solid was dried for 5 minutes in a strongly ascending current of hot air at 40C. The i",,~ ull~iull and drying steps were repeated until the desired amount of palladium had been deposited.
The dried catalyst was subsequently activated in a stream of hot hydrogen under normal pressure.
~ Le A 31,091 -10- 2 j1 78700 ExamPle 1 Catalyst 1 which had a palladium content of 1.6% by weight on 200 9 of EG17 as support was prepared by 7 il~, nt-ylldliol~s, each with 0.95 9 PdAc2 in 14 9 dct lullillilt~ and then activated for 20 hours at 370C.
ExamPle 2 Catalyst 2 which had a palladium content of 2.4% by weight on 200 9 of EG17 as the support was prepared by 10 illlpl~:ylldliull:~, each with 1 9 of PdAc2 in 14 9 aut lu"il,ilt and then activated for 20 hours at 0 370C.
ExamPle 3 Catalyst 3 which had a palladium content of 2% by wei3ht on 2000 9 of EG17 as support was prepared by 9 illl,Ul~lldliUIls, each with 9.25 9 of PdAc2 in 140 9 acetonitrile and then activated for 20 hours at 370C.
ExamPle 4 220 ml (219.0 9) of Catalyst 3, which contained 2.0% Pd, were introduced into a very well insulated reactor to give a poured bed height of 180 mm. The reactor was fitted at its upper end with a vaporizer and su,ùe, I It3dlt'1. A well insulated tube was connected to the reactor outlet forthe continuous removal of the product gas. This tube conveyed the product into a system made up of a tube bundle and a spiral UUl nit~ t~l for the purpose of cu, Idt~l ISdliul ,. The temperature upstream, in and downstream of the catalyst bed packing was measured by means of a )le thermocouple. The catalyst was first treated in the reactor :25 at 200C for 10 hours while passing in hydrogen via the vaporizer and superheater at normal pressure. Thereafter, the hydrogen flow was adjusted to 1620 I/hour. 110 g/hour of nitrobenzene were metered into the hydrogen stream by means of a metering pump via the vaporizer-superheater unit at initial temperatures of Tjnjt = 210C. This ~0 corresponded to a hydrogen/llilluuel,~t l,e m~lar ratio of 81 to 1. The 2~ 78700 Le A 31,091 resuitant temperature difference betweèn the starting material and product gas streams was about 200CC for quantitative conversion under adiabatic conditions. After a few hours, a temperature profile was attained in the catalyst bed which co" eS,uul ,-;led to a heat loss of about 5 10% through the reactor walls. The remainder of the heat of reaction left the catalyst bed with the product gas mixture. Analysis of the cu"de":,dle by gas uillullld~o~u,ld,ully gave the contents listed in the Table below. After 1000 hours, the catalyst showed no signs of deactivation.
GHSV = 7460 hour ' 10Run time Cat. No. NBz* Selectivity Tjnjt Tm~x (hours) (ppm) (%) (C) (C) 4 3 0 99.49 201 376 3 0 99.54 201 376 214 3 0 99.63 201 375 151004 3 0 99.73 201 377 *NBz = Nillube"~elle Example 5 tComparatlve) 220 ml of a catalyst prepared analogously to Example 1 of DE
2,849,002 with 9 9 Pd and 9 9 V on alpha-alumina (SPH 512 supplied by Rhone-Poulenc), were introduced into the same reactor as was used in Example 4 (the procedure was anaiogous to that used in Example 4 aboYe).
The following results were obtained after activatlon and hydrogenation under the same e~.~Jel i, Ldl conditions as were used in Example 4:
GHSV = 7460 hour 1 Le A 3~,091 -12-Run time NBz~ Selectivity Tjnjt Tm~x (hours) (ppm) (%) (C) (C) 2 0 98.0 201 385 0 98.5 199 375 5 301 100 98.9 200 370 ~NBz = Nil~ ube~ t-ln an oil-heated reactor at the same " ube"~ e loadingas in Exa;ple 4 and a.t a hydrogen/nitrobenzene ratio of 611 (GHSV = 637 hour~') the catalyst had a life of about 1000 hours and a selectivity of about 98.0% as ~ lt"l"i"ed 10 over the conversion cycle.
The catalyst was unsuitable for a process in which a large excess of hydrogen and a high loading of "illube, I~ ,e were used.
ExamPles 6 and 7 The following examples were carried out in the same reactor as 15 that which was used in Example 4 at an absolute pressure of about 5 atm.
Hydrogen and lli~, u~e" ~"e were ~,, upu, ~iu, ,ed in a molar ratio of 81 to 1. For a quantitative conversion under ideal adiabatic conditions this would result in a temperature difference of about 200C between the 20 starting material and product streams. Catalyst 1 (Example 6) or Catalyst 2 (Example 7) was loaded with 10 g ~it~ube~ e per ml catalyst per hour.
GHSV (5 atm.) = 29860 hour~' 2~ 78700 ; L,~ A 31,091 Run time Cat. No. NBz~ Selectivity Tjnjt Tm~x (ppm) (~0) (C) (C) 4 1 0 99.5 250 449 40 1 0 99.7 250 448 400 1 0 99.7 250 447 51100 1 26 99.7 250 448 4 2 0 99.4 250 449 40 2 0 99.5 250 451 400 2 0 99.7 250 450 1600 2 0 99.7 250 449 lO2400 2 14 99.8 250 450 ~NBz = ~ ' u~e"~t:"e The very low "il~ ubd~ e breakthroughs indicate the commencement of a slight deactivation of the contact catalyst.
- Due to the high loading (10 g/ml hour), the same aniline production per unit volume of catalyst was not obtained in a prior art process (loading < 1 glml hour) until after more than 11,000 hours or 24,000 hours, respectively.
Long run times or high productivities of this type without intermediate regel-dldliu" have not been described previously.
.20 The t-~lldul dil Idl ily high selectivity of the process over the entire production cycle is also It:llldlkdLI~.
Examr le 8 Hy.l, u~, IdLiul I of o-nitrotoluene The experimental set-up was the same as that used in Example 4.
The loading was 2.5 ~ o-nitrotoluene per ml catalyst per hour. Hydrogen 2~ 7~7~0 Le A 31,091 -14-and o-nitrotoluene were proportioned in a ratio of 81 to 1. The results obtained were as follows:
Run time Cat. No. NTol Selectivity Tinie Tm~x (ppm) (%) (C) (C) 24 2 0 99.8 250 447 5100 2 0 99.1 250 445 400 2 0 99.4 250 442 600 2 0 99.6 250 440 NTol = o-ni trotol uene Examples 9 and 10 were carried out at normal pressure using 10 about 2 liters of Catalyst 3 in oil-heated heat e~.ul,d"~, tubes made of V2A having a length of about 300 cm, which is customary for industrial reactors, and an inside diameter of about 3 cm.
The loading was 0.65 g/ml hour, and the temperature of the heat transfer medium was adjusted to 250C.
ExamPle 9 GHSV = 9707 houf' H2/NBz = 81/1 Service life > 5000 hours (no llillu~e~ lle breakthrough) Examole 10 (Comparative) GHSV = 2131 hour~1 H2/NBz = 17/1 Service life 95 hours ("il, u~"~"e breakthrough >
100 ppm) A deactivation of the catalyst, which was clearly progressive, occurred below a critical ratio of hydrogen to "i~,ub~"~ e.
Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be ~" Id~l bluod that such detail is solely for that purpose and that variations can be made therein Le A 31,091 -15-by those skilled in the art without departing from the spirit and scope of the inventlon extept as it may be limlted by th~ cl~ims
AMINES BY GAS PHASE HYDROGENATION
AND A CATALYST USEFUL THEREFOR
BACKGROUND OF THE INVENTION
The present invention relates to an improved process for producing aromatic amines by catalytic h~dluu~lldliùll of ~ ludlullldliu compounds in the gas phase and to a new catalyst which is useful in this process.
Aromatic amines are known to those skilled in the art as important intermediates for the production of dyes polyurethanes and plant protection products.
Various procedures for the hyd~uytlndlioll of ~ u~ el1e and other ~ UdlUllldli~ compounds are known to those skilled in the art. Due to the high enthalpy of reaction which is released during these known ~, u~ sesl they are usually conducted in reactors equipped with . integrated heat transfer systems. Examples of some of these known procedures are hyd, U9t:1 Idliul~ in the liquid phase on suspended catalysts such as Pd catalysts (described in EP 476,404) h~lug~l~dliullin the gas phase onfluidized solid catalysts (disclosed in U.S. 3136 818) h~ u~lldliul1in the gas phase over fixed catalysts such as supported Pd catalysts (described in DE-A 2,244 401 2 849 002 and 4,039 026).
DE-A 2 244 401 and 2 849 002 describe Pd catalysts on alumina supports which are operated as fixed catalyst beds in heat e,~..l Idl ,g~, tubes under normal pressure at loadings of less than 1 9 I ~ ub~ e 25 (NBz)/ml (cat)/hour at low hydrogen/nitrobenzene ratios. Between 6 and 11 moles of hydrogen are used for each mole of llillu~
DE-A 4 039 026 describes Pd catalysts on graphitic supports which are operated under conditions similar to those used for Pd catalysts on alumina. These ca alysts provide ill~ulll~ conversion at Le A 31,091 -2- 2, 7~700 loadings cullsid~ldL,ly less than 1 9 (NBz) / ml (cat)/ hour and at a hyd~ug~ ' u~e,l~"e ratio of from 14 to 26 moles to 1 mole. Between 1000 and 4000 ppm r, ' uue"~ e, with respect to the aniline formed, are fûund in the colldt:, ISdl~.
Both an increase in the loading of lli~lUdlUllldLiC compound and an increase in the ratio of hydrogen to nitroaromatic compound increase the volume flow through the bed and thus reduce the dwell time on the contact catalyst. It would therefore be expected that both of these measures would lead to an increase in the breakthrough of the llilludlullldlic compound (i.e., to incomplete conversion).
A general measure of this gas flow through the catalyst bed is the gas hourly space velocity (GHSV), expressed in hour 1.
Even small amounts of lI 'ludlullldlk, compounds in aromatic amines cause signlficant ~ ,cul~ldliul, of the aromatic amine which is otherwise colorless. Such nitroaromatic compounds are therefore u~de~ dule. Separation of l~i~ludlullldliu compounds by distillation is costly in terms of both equipment and energy.
In each of these known processes, the high heat of reaction has to be withdrawn from the reactor via an expensive heat transfer system.
H~lu~el~dliu" processes in the gas phase with simple adiabatic catalyst packed beds are particularly economical, due to the simple construction of the apparatus with reactors that do not include integrated heat ~x-:l Idl ,g~l systems. In an adiabatic type of process, the highly ~xull ~e~ iu nature of the hy.ll u~l ldliul~ of nitro groups imposes particular demands on the catalyst. Due to the col~sid~,dùl~ exothemm, there is a lar~e temperature difference between the beginning and the end of the catalyst. In order to control this temperature difference in an adiabatic process, a heat transfer medium (generally hydrogen in h~dlu~u~lldliull processes) is admixed with the mixture of starting materials resulting in very short dwell times or high GHSVs. This means that the catalyst must 2 1 7870(~
L~: A 31 091 3 be both active and selective over a very large temperature range in order to achieve complete conversion of "il,ube"~ne to aniline even at low UU~ le loadings.
~iUMMARY OF THE INVENTION
It is an object of the present invention to provide a h~ ugelldli catalyst which can be more highly loaded than the known catalysts.
It is also an object of the present invention to provide a h~l ug~l Id~iUI I catalyst which exhibits a higher selectivity than the known prior art catalysts.
It is another object of the present invention to provide a hy~JI us ~l Id~iUI I catalyst which can be used in simple reactor constructions.
It is a further object of the present invention to provide a hyd,uut:l~d~iu, I catalyst having a long service life.
It is also an object of the present invention to provide a hydlUy~lldliUI, process in which extraction of heat from the catalyst bed with an additional heat transfer system is not necessary.
These and other objects which will be apparent to those skilled in the art are accu",~ 71led by h~dlu~u~:lld~il,g ~, udlurlld~i~; compounds in :20 the gas phase in the presence of a Pd catalyst on a graphite or a graphitic carbon support and large excesses of hydrogen. This process may be carried out in simple adiabatic reactors.
~ETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention relates to a process for producing aromatic amines l~pl~ d by the formula 2~3NH2 (1) R
2 ~ 7~700 ~e A 31,091 4_ in which R' and R2, i~l~e~ d~ y of each other, represent hydrogen, a methyl group or an ethyl group and R' may also represent an amino group, by the hydlu~ lldliull of ~ udlullldli~; compounds rt,u,~su,,~d by the formula R~No2 (Il) in which R2 and R3, il Id~,ut:l ,de, Illy of each other, represent hydrogen, a methyl group or an ethyl group and R3 may ad.iiliu, I...ly 1 û represent a nitro group with hydrogen over fixed catalysts in the gas phase. The catalyst used is palladium on a graphite or a graphitic coke support. The graphite or graphitic coke support has a BET specific surface of from û.2 to 1û m2/g.
The catalyst has a palladium content (based on the total weight of catalyst) greater than 1.5% by weight and up to 7% by weight, preferably from 1.6 to 6% by weight, most preferably from 1.9 to 5% by weight.
From 3û to 6ûûû, preferably from 5û to 3ûûû, more preferably from 8û to 1ûûû, most preferably from 1ûû to 3ûû equivalents of hydrogen for each equivalent of nitro groups are fed to the catalyst.
2û The present invention also relates to a catalyst having a graphite or a graphite-containing coke support. The graphite or graphite-~.ullldillillg support has a BET specific surface of from û.2 to 1û m2/g.
The palladium is deposited on the support by illl~ ul ldLiol~ with a suitable palladium-containing solution. The palladium content of the 2 1 7~700 L~! A 31,091 catalyst is from greater than 1.5% (e.g., 1.5001%) by weight up to 7% by weight (based on the total weight of catalyst). The preferred lower limit of the Pd content is 1.6% by weight, most preferably 1.9% by weight.
The preferred upper limit of the Pd content is 6% by weight, most 5 preferably 5% by weight.
Graphite-containing materials are used as the support for the catalysts of the present invention. Suitable support materials include graphite itself (e.g., t~le-:tlUyld,UIlil~) and cokes such as needle coke 2nd petroleum coke. These supports have BET specific surfaces of from 0.2 10 to 10 m2/g.
The catalyst is prepared by depositing palladium on the support in from 1 to 50, preferably from 2 to 30, most preferably from 4 to 10 impregnation steps. ~etween each illl,Ult::~Jlld~iUIl step the catalyst support is dried in a hot gas stream, preferably a stream of air or 15 nitrogen.
The catalysts of the present invention may be prepared by depositing palladium in the form of suitable salts on the support material in the form of tablets, spheres, lengths of granulated material, Raschig rings, Pall rings, cart wheels or honeycomb structures of d~ameters from 20 1 to 30 mm. A plurality of illl,Ul~JlldliUI~ steps may be used with drying after each d~posiLiu". Drying is effected in an air current at temperatures of from 30 to 140C, preferably from 30 to 60CC and preferably under nonmal pressure. Aqueous and organic solvents and mixtures thereof may be used for the illlpl~ylld~iull of the support. Examples of solvents 25 which may be used include water, NH3, simple alcohols, amines, ketones, esters, cyclic ethers, lldlug~lld~t:d hydro-carbons and nitriles.
Specific examples of organic solvents include methanol, ethanol, propanol, isopropanol, ethylamine, isopropylamine, acetone, methyl ethyl ketone, dioxane, methylene chloride, acetonitrile and cull~,udldble ao solvents. Examples of suitable palladium salts include palladium chloride, 2 ~ 7~700 Le A 31,091 -6-palladium nitrate, palladium acet~ldc~Lu,~d~, palladium acetate and amine wlllpi~ S of palladium The catalyst pl~:pdldLiùll is preferably carried out without the use of halogens in the solvent or the metal salt used. After illlpl~ dliul~ and final drying, the catalyst of the present 5 invention is ready for use.
Before it is first placed in operation, the catalyst is generally activated by treating it with a flow of hydrogen at 1 to 10 bar and temperatures of from 250 to 450C (preferably from 300 to 400C) for from 1 to 50 hours (preferably from 5 to 30 hours).
The hydlug~lld~iun process of the present invention is conducted at a pressure of from 1 to 30 bar, preferably from 1 to 15 bar, most preferably from 1 to 7 bar.
The gaseous mixture of starting materials wntaining the nitroaromatic compound and hydrogen is at a temperature of from 20û to 400C, preferably from 230 to 370C, most preferably 250 to 350C, upstream of the catalyst bed. The maximum catalyst temperature is 600C, preferably 55~C, more preferably 500C, most preferably 460C.
The catalyst of the present invention may be used in reactors without a system for the removal of heat.
The short dwell times or high GHSVs of the process of the present invention are particularly l~,,,dlhd~le. These short dwell times make it possible to use catalyst loadings of from 0.5 to 40 kg, preferably from 1 to 30 kg, most preferably from 2 to 20 kg of l~i~lUdlUllld~iU compound per liter of catalyst per hour.
The space-time yields which can be obtained are therefore an order of magnitude higher than those of the known processes for the h~,~,u~elld~iu" of nitroaromatic compounds. Such higher space-time yields are particularly important for the economic production of large quantities of aromatic amine because only small amounts of catalyst and ~0 .,ull~:,,uul~dillgly small reactors are required.
21 7g700 A 31,091 7 Another important advantage of the process of the present invention is the quantitative conversion of the llilludlullldli~ compound which is surprisingly and ~l ,e,x,oeule~ly obtained, even at the high loadings used.
The process of the present invention is also distinguished by the absence of a so-called catalyst induction phase and by its selectivities which are higher than 99.4% from the outset.
In the process of the present invention, the conversion of nltroaromatic compound is higher than 99.95%, preferably higher than 99.99%, more preferably higher than 99.995%, most preferably higher than 99.999%. This should not, however, be ~l ld~ uod as being : limiting because any desired lower degree of conversion can be achieved by selection of the d,U,UlUplidl~ process conditions.
The catalysts of the present invention can be used in any reactor having a fixed catalyst bed.
One industrial implementation of the process can be described as follows:
The catalyst is fixed in an adiabatic reactor of known design (See Ullmann, EnzykloPadie der l~-.l " li~ l Çhemie [Ullmann's Encyclopedia :20 of Industrial Chemistry~, 4th Edition, Volume 3, pages 468-649; and Kirk-Othmer, EncvcloPedia Qf Chemical Technoloav. Vol. 19 (1982), pages 880-914, for example.). However, the catalyst may also be distributed between a plurality of reactors which are cu"lle~ d in series or in parallel. These reactors may be any of those known in the art to be :25 useful for the oxidation of methanol to roll"dld~l"/de, for example.
The packed catalyst beds are provided on or between gas-permeable walls, as in the prior art. Satisfactory gas distribution must be ensured.
Instead of being used as a bulk packing, the catalyst may also be prepared and used on suitable packings as a support material.
Le A 31,091 Fresh ~ UdlUllldli~ compound is metered into the circulating gas stream which is ~""ùosed primarily of recycled and freshly added hydrogen upstream of the catalyst packing. It is preferred however that the nitroaromatic compound be completely volatilized in the fresh hydrogen before being introduced in gaseous form into the circulating gas stream. After passing through the catalyst bed the product gas is cooled with the recovery of steam. The steam may be recovered by means of any of the heat e~.l,d"~e,~ known to those skilled in the art.
Thereafter the product gas is cooled to remove the aromatic amine and the water of reaction from the reaction mixture by, u,,de,,~dLiu,l. The remaining circulating gas is recycled after removing a small amount of gas for the outward transfer of gaseous constituents in the circulating gas. Before recycling the circulating gas should generally be preheated to its inlet temperature and admixed with fresh starting material.
The above d~s~i,uLiu" of one ~",bodi",~"l of the present invention is of an elementary nature and should not have a limiting effect or be judged as limiting.
The process of the present invention is particularly suitable for the h~,d,u~elld~iù,l of l,il,uL~ e or nitrotoluene.
The process of the present invention makes it possible to use catalyst loadings or GHSVs which are extremely high (i.e. higher by a power of ten than those of the prior art). Despite these high catalyst loadings however selectivities greater than 99.4% are obtained with complete conversion even at the commencement of the reaction. The catalysts of the present invention exhibit the greatest productivity achieved without production l 'I .I,~aPc due to catalyst deactivation.
The invention is further illustrated but is not intended to be limited by the following Examples in which all parts and p~l~llldU~:S are parts by weight or p~, ,e"ld~es by weight unless otherwise specified.
L~ ~ 31,091 9 E~AMPLES
The GHSV (gas hourly space velocity), u~ se"l~ the hourly space velocity of the gas under normal conditions or at a given pressure, wlth respect to the empty volume which the packed catalyst bed 5 occupies.
Catalvst ~ Udl~iull EG 17 granulated graphite supplied by Ringsdorff which had a BET specific surface of about 0.4-0.8 m2/g, was used as the support material. The grain size was between 1 and 3 mm and the tap density 10 was from 650 to 1000 9/l.
Results similar to those reported below have also been obtained with other graphites and graphite-containing materials having a low BET
speclfic surface.
The catalysts used in the Examples which follow were prepared in 15 the following manner:
EG 17 granulated graphite with an ~LJSOIIJ~IICY of 7 ml au~ il,ile per 100 9 support was placed in a rotatable vessel and mixed, by rotation, with a solution of palladium acetate in ~Le~u"il,ile. The mixture was agitated until the solvent had been completely absorbed by the 20 support. Thereafter, the solid was dried for 5 minutes in a strongly ascending current of hot air at 40C. The i",,~ ull~iull and drying steps were repeated until the desired amount of palladium had been deposited.
The dried catalyst was subsequently activated in a stream of hot hydrogen under normal pressure.
~ Le A 31,091 -10- 2 j1 78700 ExamPle 1 Catalyst 1 which had a palladium content of 1.6% by weight on 200 9 of EG17 as support was prepared by 7 il~, nt-ylldliol~s, each with 0.95 9 PdAc2 in 14 9 dct lullillilt~ and then activated for 20 hours at 370C.
ExamPle 2 Catalyst 2 which had a palladium content of 2.4% by weight on 200 9 of EG17 as the support was prepared by 10 illlpl~:ylldliull:~, each with 1 9 of PdAc2 in 14 9 aut lu"il,ilt and then activated for 20 hours at 0 370C.
ExamPle 3 Catalyst 3 which had a palladium content of 2% by wei3ht on 2000 9 of EG17 as support was prepared by 9 illl,Ul~lldliUIls, each with 9.25 9 of PdAc2 in 140 9 acetonitrile and then activated for 20 hours at 370C.
ExamPle 4 220 ml (219.0 9) of Catalyst 3, which contained 2.0% Pd, were introduced into a very well insulated reactor to give a poured bed height of 180 mm. The reactor was fitted at its upper end with a vaporizer and su,ùe, I It3dlt'1. A well insulated tube was connected to the reactor outlet forthe continuous removal of the product gas. This tube conveyed the product into a system made up of a tube bundle and a spiral UUl nit~ t~l for the purpose of cu, Idt~l ISdliul ,. The temperature upstream, in and downstream of the catalyst bed packing was measured by means of a )le thermocouple. The catalyst was first treated in the reactor :25 at 200C for 10 hours while passing in hydrogen via the vaporizer and superheater at normal pressure. Thereafter, the hydrogen flow was adjusted to 1620 I/hour. 110 g/hour of nitrobenzene were metered into the hydrogen stream by means of a metering pump via the vaporizer-superheater unit at initial temperatures of Tjnjt = 210C. This ~0 corresponded to a hydrogen/llilluuel,~t l,e m~lar ratio of 81 to 1. The 2~ 78700 Le A 31,091 resuitant temperature difference betweèn the starting material and product gas streams was about 200CC for quantitative conversion under adiabatic conditions. After a few hours, a temperature profile was attained in the catalyst bed which co" eS,uul ,-;led to a heat loss of about 5 10% through the reactor walls. The remainder of the heat of reaction left the catalyst bed with the product gas mixture. Analysis of the cu"de":,dle by gas uillullld~o~u,ld,ully gave the contents listed in the Table below. After 1000 hours, the catalyst showed no signs of deactivation.
GHSV = 7460 hour ' 10Run time Cat. No. NBz* Selectivity Tjnjt Tm~x (hours) (ppm) (%) (C) (C) 4 3 0 99.49 201 376 3 0 99.54 201 376 214 3 0 99.63 201 375 151004 3 0 99.73 201 377 *NBz = Nillube"~elle Example 5 tComparatlve) 220 ml of a catalyst prepared analogously to Example 1 of DE
2,849,002 with 9 9 Pd and 9 9 V on alpha-alumina (SPH 512 supplied by Rhone-Poulenc), were introduced into the same reactor as was used in Example 4 (the procedure was anaiogous to that used in Example 4 aboYe).
The following results were obtained after activatlon and hydrogenation under the same e~.~Jel i, Ldl conditions as were used in Example 4:
GHSV = 7460 hour 1 Le A 3~,091 -12-Run time NBz~ Selectivity Tjnjt Tm~x (hours) (ppm) (%) (C) (C) 2 0 98.0 201 385 0 98.5 199 375 5 301 100 98.9 200 370 ~NBz = Nil~ ube~ t-ln an oil-heated reactor at the same " ube"~ e loadingas in Exa;ple 4 and a.t a hydrogen/nitrobenzene ratio of 611 (GHSV = 637 hour~') the catalyst had a life of about 1000 hours and a selectivity of about 98.0% as ~ lt"l"i"ed 10 over the conversion cycle.
The catalyst was unsuitable for a process in which a large excess of hydrogen and a high loading of "illube, I~ ,e were used.
ExamPles 6 and 7 The following examples were carried out in the same reactor as 15 that which was used in Example 4 at an absolute pressure of about 5 atm.
Hydrogen and lli~, u~e" ~"e were ~,, upu, ~iu, ,ed in a molar ratio of 81 to 1. For a quantitative conversion under ideal adiabatic conditions this would result in a temperature difference of about 200C between the 20 starting material and product streams. Catalyst 1 (Example 6) or Catalyst 2 (Example 7) was loaded with 10 g ~it~ube~ e per ml catalyst per hour.
GHSV (5 atm.) = 29860 hour~' 2~ 78700 ; L,~ A 31,091 Run time Cat. No. NBz~ Selectivity Tjnjt Tm~x (ppm) (~0) (C) (C) 4 1 0 99.5 250 449 40 1 0 99.7 250 448 400 1 0 99.7 250 447 51100 1 26 99.7 250 448 4 2 0 99.4 250 449 40 2 0 99.5 250 451 400 2 0 99.7 250 450 1600 2 0 99.7 250 449 lO2400 2 14 99.8 250 450 ~NBz = ~ ' u~e"~t:"e The very low "il~ ubd~ e breakthroughs indicate the commencement of a slight deactivation of the contact catalyst.
- Due to the high loading (10 g/ml hour), the same aniline production per unit volume of catalyst was not obtained in a prior art process (loading < 1 glml hour) until after more than 11,000 hours or 24,000 hours, respectively.
Long run times or high productivities of this type without intermediate regel-dldliu" have not been described previously.
.20 The t-~lldul dil Idl ily high selectivity of the process over the entire production cycle is also It:llldlkdLI~.
Examr le 8 Hy.l, u~, IdLiul I of o-nitrotoluene The experimental set-up was the same as that used in Example 4.
The loading was 2.5 ~ o-nitrotoluene per ml catalyst per hour. Hydrogen 2~ 7~7~0 Le A 31,091 -14-and o-nitrotoluene were proportioned in a ratio of 81 to 1. The results obtained were as follows:
Run time Cat. No. NTol Selectivity Tinie Tm~x (ppm) (%) (C) (C) 24 2 0 99.8 250 447 5100 2 0 99.1 250 445 400 2 0 99.4 250 442 600 2 0 99.6 250 440 NTol = o-ni trotol uene Examples 9 and 10 were carried out at normal pressure using 10 about 2 liters of Catalyst 3 in oil-heated heat e~.ul,d"~, tubes made of V2A having a length of about 300 cm, which is customary for industrial reactors, and an inside diameter of about 3 cm.
The loading was 0.65 g/ml hour, and the temperature of the heat transfer medium was adjusted to 250C.
ExamPle 9 GHSV = 9707 houf' H2/NBz = 81/1 Service life > 5000 hours (no llillu~e~ lle breakthrough) Examole 10 (Comparative) GHSV = 2131 hour~1 H2/NBz = 17/1 Service life 95 hours ("il, u~"~"e breakthrough >
100 ppm) A deactivation of the catalyst, which was clearly progressive, occurred below a critical ratio of hydrogen to "i~,ub~"~ e.
Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be ~" Id~l bluod that such detail is solely for that purpose and that variations can be made therein Le A 31,091 -15-by those skilled in the art without departing from the spirit and scope of the inventlon extept as it may be limlted by th~ cl~ims
Claims (10)
1. A process for the production of an aromatic amines represented by the formula (I), in which R1 and R2, independently of each other, represent hydrogen, a methyl group or an ethyl group, and R1 may also represent an amino group, comprising hydrogenating a nitroaromatic compound represented by the formula (II), in which R2 and R3, independently of each other, represent hydrogen, a methyl group or an ethyl group and R3 may also represent a nitro group, with hydrogen over a fixed catalyst in the gas phase in which (1) the fixed catalyst has a palladium content greater than 1.5%
but less than 7% by weight, based on total weight of catalyst and (2) the palladium is on a graphite or a graphite-containing coke support having a BET specific surface of from 0.2-10 m2/g in amounts such that from 30 to 6000 equivalents of hydrogen are fed to the catalyst for each equivalent of nitro groups.
but less than 7% by weight, based on total weight of catalyst and (2) the palladium is on a graphite or a graphite-containing coke support having a BET specific surface of from 0.2-10 m2/g in amounts such that from 30 to 6000 equivalents of hydrogen are fed to the catalyst for each equivalent of nitro groups.
2. The process of Claim 1 in the hydrogenation is carried out at a pressure of from 1 to 30 bar.
3. The process of Claim 1 in which the nitroaromatic compound and hydrogen are mixed and that mixture is at a temperature of from 200 to 400°C upstream of the catalyst bed.
4. The process of Claim 3 in which the maximum catalyst temperature is 600°C.
5. The process of Claim 1 in which a catalyst loading of from 0.5 to 40 kg nitroaromatic compound per liter of catalyst per hour is set.
6. The process of Claim 1 in which the hydrogenation reaction is conducted in a reactor without a system for the dissipation of the heat of reaction.
7. The process of Claim 1 in which nitrobenzene or nitrotoluene is the nitroaromatic compound.
8. A catalyst suitable for the hydrogenation of nitroaromatic compounds having (1) a graphite or graphite-containing coke with a BET
specific surface of from 0.2-10 m2/g support and (2) a palladium content greater than 1.5 and up to 7% by weight, based on the total weight of catalyst.
specific surface of from 0.2-10 m2/g support and (2) a palladium content greater than 1.5 and up to 7% by weight, based on the total weight of catalyst.
9. The catalyst of Claim 8 in which the palladium is deposited on the support in 1 to 50 impregnation steps, between each of which the catalyst support is dried in a hot gas stream.
10. The catalyst of Claim 8 in which the catalyst is activated in a stream of hydrogen at from 1 to 10 bar and at temperatures from 250 to 450°C before use.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19521670A DE19521670A1 (en) | 1995-06-14 | 1995-06-14 | Process and catalyst for the production of aromatic amines by gas phase hydrogenation |
| DE19521670.9 | 1995-06-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2178700A1 true CA2178700A1 (en) | 1996-12-15 |
Family
ID=7764383
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002178700A Abandoned CA2178700A1 (en) | 1995-06-14 | 1996-06-10 | Process for producing aromatic amines by gas phase hydrogenation and a catalyst useful therefor |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0748789B1 (en) |
| JP (1) | JPH093013A (en) |
| KR (1) | KR100413575B1 (en) |
| CN (1) | CN1071308C (en) |
| BR (1) | BR9602790A (en) |
| CA (1) | CA2178700A1 (en) |
| CZ (1) | CZ287872B6 (en) |
| DE (2) | DE19521670A1 (en) |
| ES (1) | ES2139276T3 (en) |
| PL (1) | PL183134B1 (en) |
| TW (1) | TW328073B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9067864B2 (en) | 2006-07-29 | 2015-06-30 | Bayer Materialscience Ag | Process for producing aromatic amines |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100493190B1 (en) * | 1997-12-29 | 2005-08-11 | 삼성테크윈 주식회사 | Method for driving by accelerating and decelerating motor |
| EP1980583A1 (en) * | 2007-04-10 | 2008-10-15 | Solvay Solexis S.p.A. | A method for preparing carbonylic perfluoropolyethers |
| CN101265236B (en) * | 2008-04-28 | 2012-05-23 | 武穴市龙翔药业有限公司 | Synthesis technique for toltrazuril |
| DE102009019436A1 (en) | 2009-04-29 | 2010-11-04 | Bayer Materialscience Ag | Process for the preparation of aromatic amines |
| CN102070464B (en) * | 2011-02-16 | 2013-09-04 | 上海安诺芳胺化学品有限公司 | Method for producing phenylene diamine by performing hydrogenation reduction on mixed dinitrobenzene with palladium catalyst |
| US8933262B2 (en) | 2011-05-24 | 2015-01-13 | Basf Se | Process for preparing polyisocyanates from biomass |
| BR112013029665A2 (en) | 2011-05-24 | 2019-09-24 | Basf Se | "process for the preparation of polyisocyanates, and polyisicianate composition" |
| WO2015052068A1 (en) | 2013-10-08 | 2015-04-16 | Bayer Materialscience Ag | Method for producing diaminotoluene |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4039026A1 (en) * | 1990-12-07 | 1992-06-11 | Bayer Ag | METHOD FOR PRODUCING ANILINE |
| DE4428017A1 (en) * | 1994-08-08 | 1996-02-15 | Bayer Ag | Process for the preparation of aromatic amines |
-
1995
- 1995-06-14 DE DE19521670A patent/DE19521670A1/en not_active Withdrawn
-
1996
- 1996-06-03 DE DE59603325T patent/DE59603325D1/en not_active Expired - Fee Related
- 1996-06-03 ES ES96108855T patent/ES2139276T3/en not_active Expired - Lifetime
- 1996-06-03 EP EP96108855A patent/EP0748789B1/en not_active Expired - Lifetime
- 1996-06-10 TW TW085106932A patent/TW328073B/en active
- 1996-06-10 CA CA002178700A patent/CA2178700A1/en not_active Abandoned
- 1996-06-11 JP JP8170701A patent/JPH093013A/en not_active Withdrawn
- 1996-06-12 PL PL96314750A patent/PL183134B1/en not_active IP Right Cessation
- 1996-06-13 CZ CZ19961739A patent/CZ287872B6/en not_active IP Right Cessation
- 1996-06-13 KR KR1019960021211A patent/KR100413575B1/en not_active IP Right Cessation
- 1996-06-13 BR BR9602790A patent/BR9602790A/en not_active IP Right Cessation
- 1996-06-14 CN CN96106185A patent/CN1071308C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9067864B2 (en) | 2006-07-29 | 2015-06-30 | Bayer Materialscience Ag | Process for producing aromatic amines |
Also Published As
| Publication number | Publication date |
|---|---|
| KR970001304A (en) | 1997-01-24 |
| CN1071308C (en) | 2001-09-19 |
| DE59603325D1 (en) | 1999-11-18 |
| EP0748789B1 (en) | 1999-10-13 |
| EP0748789A3 (en) | 1998-04-08 |
| ES2139276T3 (en) | 2000-02-01 |
| BR9602790A (en) | 1998-09-08 |
| TW328073B (en) | 1998-03-11 |
| PL314750A1 (en) | 1996-12-23 |
| CN1142487A (en) | 1997-02-12 |
| DE19521670A1 (en) | 1996-12-19 |
| JPH093013A (en) | 1997-01-07 |
| PL183134B1 (en) | 2002-05-31 |
| KR100413575B1 (en) | 2004-04-03 |
| EP0748789A2 (en) | 1996-12-18 |
| CZ287872B6 (en) | 2001-02-14 |
| CZ173996A3 (en) | 1997-01-15 |
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