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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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/24—Stationary reactors without moving elements inside
  • B01J19/248—Reactors comprising multiple separated flow channels
  • B01J19/249—Plate-type reactors
• • 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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/0093—Microreactors, e.g. miniaturised or microfabricated reactors
• • 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
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00781—Aspects relating to microreactors
  • B01J2219/00783—Laminate assemblies, i.e. the reactor comprising a stack of plates
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00781—Aspects relating to microreactors
  • B01J2219/00819—Materials of construction
  • B01J2219/00835—Comprising catalytically active material
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00781—Aspects relating to microreactors
  • B01J2219/00851—Additional features
  • B01J2219/00871—Modular assembly
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00781—Aspects relating to microreactors
  • B01J2219/00873—Heat exchange
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00781—Aspects relating to microreactors
  • B01J2219/0095—Control aspects
  • B01J2219/00952—Sensing operations
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/24—Stationary reactors without moving elements inside
  • B01J2219/2401—Reactors comprising multiple separate flow channels
  • B01J2219/245—Plate-type reactors
  • B01J2219/2451—Geometry of the reactor
  • B01J2219/2453—Plates arranged in parallel
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/24—Stationary reactors without moving elements inside
  • B01J2219/2401—Reactors comprising multiple separate flow channels
  • B01J2219/245—Plate-type reactors
  • B01J2219/2451—Geometry of the reactor
  • B01J2219/2456—Geometry of the plates
  • B01J2219/2458—Flat plates, i.e. plates which are not corrugated or otherwise structured, e.g. plates with cylindrical shape
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/24—Stationary reactors without moving elements inside
  • B01J2219/2401—Reactors comprising multiple separate flow channels
  • B01J2219/245—Plate-type reactors
  • B01J2219/2461—Heat exchange aspects
  • B01J2219/2462—Heat exchange aspects the reactants being in indirect heat exchange with a non reacting heat exchange medium
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/24—Stationary reactors without moving elements inside
  • B01J2219/2401—Reactors comprising multiple separate flow channels
  • B01J2219/245—Plate-type reactors
  • B01J2219/2476—Construction materials
  • B01J2219/2477—Construction materials of the catalysts
  • B01J2219/2479—Catalysts coated on the surface of plates or inserts

Definitions

• the invention relates to a process for the preparation of aromatic amines by catalytic hydrogenation of aromatic nitro compounds in the presence of a catalyst applied to the inner wall of an externally cooled reaction channel.
• Aromatic amines are important intermediates that need to be produced inexpensively in large quantities. For the economy of the process therefore high space-time yields and long catalyst life are crucial.
• the hydrogenation of nitroaromatics is a highly exothermic reaction. The removal and energetic use of the heat of reaction is therefore an important aspect in the production of aromatic amines.
• DE2849002 describes a process for the reduction of nitro compounds in the presence of stationary, palladium-containing multicomponent supported catalysts in cooled shell-and-tube reactors.
• the contact consists essentially of 1 to 20 g of palladium, 1 to 20 g of vanadium and 1 to 20 g of lead per liter of CX-Al 2 O 3 .
• the active components as close to the surface of the catalyst in a very sharp Zone are present depressed and inside the support material, no active components are included.
• a disadvantage of the gas phase hydrogenation described in DE 2 849 002 is the low specific loading of the catalysts, which is essentially due to insufficient heat removal. The specified loads are about 0.4 to 0.5 kg / (lh).
• the load is defined as the amount of nitroaromatics in kg, which is enforced per liter of catalyst charge within one hour.
• the load is defined as the amount of nitroaromatics in kg, which is enforced per liter of catalyst charge within one hour.
• Associated with the low catalyst loading is an unsatisfactory space-time yield in industrial processes for the production of aromatic amines.
• the selectivities at the beginning of a driving period are significantly lower than towards the end, which leads to yield losses and problems in the workup of the crude product.
• WO 98/25881 describes the use of inert materials for diluting the catalyst bed in the preparation of aromatic amines.
• the dilution enlarges the reaction zone and thus increases the area available for heat exchange. With this procedure, the hot spot temperature can be lowered or the potential nitroaromatic load can be increased at a constant hot spot temperature. Due to the dilution, however, the service life of the bed decreases. In the example given in WO 98/25881, the productivity of the diluted bed was significantly lower than the productivity of the undiluted bed owing to the short service lives despite higher loading.
• Klemm et al. describe in Chemical Engineering Science 56 (2001) pp. 1347 - 1353 the preparation of a catalytic laboratory wall reactor for the determination of the deactivation kinetics of the catalytic hydrogenation of nitrobenzene to aniline.
• the direct application of the 100 .mu.m-400 .mu.m thick catalyst layer to the inner wall of an externally cooled metal tube with an internal diameter of 10 mm allows isothermal reaction conditions to be achieved.
• a scale-up of the Wanderactors described with individually coated and then assembled into a large-scale reactor pipes is not practical.
• Another disadvantage of the wall reactor described is the low volume fraction of 4% -15%, which would lead to very large reactor dimensions in the case of large-scale implementation of the concept.
• DE 1 0347 439 describes a process for the preparation of aromatic amines in which a catalyst is used which consists of a monolithic carrier and a thin catalytically active coating. It is advantageous here that a higher selectivity is achieved by the thin catalytically active layer than in comparable fixed beds can.
• the disadvantage is that the monolithic supported catalyst described not cooled due to its poor radial heat dissipation from the outside but only adiabatic, ie usually with large gas flow in the circuit, which means a costly management of the process and other costs.
• the object of the present invention is therefore to provide a process for the preparation of aromatic amines by catalytic hydrogenation of aromatic nitro compounds, which reduces the formation of hotspots and allows a high space-time yield, longer life and higher selectivity.
• the invention relates to a process for the preparation of aromatic amines by catalytic hydrogenation of aromatic nitro compounds, which is characterized in that the catalyst required for the reaction is applied to the inner wall of one or more externally cooled reaction channels.
• the cooling medium which is in thermal contact with the reaction channel is also preferably guided into at least two cooling medium channels which are essentially parallel to one another and which are conducted in direct current, countercurrent or crossflow in the reaction channel in relation to the main flow direction.
• the cooling medium used is salt melts, steam, organic compounds or molten metals, preferably molten salts, steam or heat transfer oils, particularly preferably a mixture of potassium nitrate, sodium nitrite and sodium nitrate, dibenzyltoluene or a mixture of diphenyl oxide and diphenyl.
• the cooling medium or the cooling medium are conducted in the cross-flow to the main flow direction in the reaction channel.
• the cooling medium is usually divided into at least two substantially parallel cooling medium channels and the cooling medium channels can have different material properties, flow rates, flow rates or temperatures.
• the catalyst is applied to the inner wall of the reaction channel in a 5 to 1000 .mu.m, preferably 10 to 500 .mu.m, more preferably 20 .mu.m to 200 .mu.m thick layer.
• the application can be carried out in principle by any known technology. Preference is given to using methods in which a plurality of reaction channels are coated by a single coating process with Ka be coated. Particularly preferred methods are used in which the catalyst is applied as a washcoat on the inner wall of the reaction channels. Usually, the catalyst is applied to the inner wall of at least two externally cooled reaction channels simultaneously.
• the catalytically active coating for the hydrogenation of aromatic nitro compounds in the gas phase preferably contains metals from groups VIHa, Ib, IVa, Va, VIa, IVb and Vb of the Periodic Table of the Elements (Mendeleyev, Zeitschrift für Chemie 12, 405-6, 1869) as a catalytically active component.
• Preferred metals are Pd, Pt, Cu or Ni.
• the catalytically active component can be applied to a carrier.
• Suitable carrier substances are ceramic materials, such as, for example, Al 2 O 3 , SiO 2 , TiO 2 or zeolites, but also graphite or carbon.
• the carrier substance is preferably finely ground.
• the volume-related particle size d 90 of the preferably milled carrier substance should preferably be less than 50 ⁇ m, more preferably less than 10 ⁇ m.
• the catalyst described in DE 2 849 002 is particularly preferably used as the catalytically active coating.
• At least two reaction channels are operated under the same reaction conditions.
• the reactor for the catalytic hydrogenation of aromatic nitro compounds according to the process of the invention consists of one or more externally cooled reaction channels, on the inner walls of which the catalyst required for the reaction is applied.
• the proportion of the catalyst volume in the total volume of the device is usually from 1% to 50%, preferably from 5% to 35%, particularly preferably from 10% to 25%.
• the reaction channels have a round or rectangular cross-sectional area with a hydraulic diameter, defined as a ratio of four times the internal cross-sectional area to the inner circumference, of 0.05 mm to 100 mm, preferably 0, 1 mm to 10 mm, particularly preferably 0.5 mm to 2 mm and a length of length of 0.02 m to 5.0 m, preferably 0.1 m to 1.0 m, particularly preferably 0.2 m to 0.7 m.
• At least two, preferably from 20,000 to 200,000,000 reaction channels, preferably of the same geometry, are preferably arranged in parallel.
• the reaction channels are arranged in one or more plates for reaction channels so that this plate is in thermal contact with at least one set of cooling medium channels arranged parallel, preferably also in one or more plates.
• At least two, more preferably 200 to 20,000 reaction channels per plate are arranged in parallel (FIG. 1).
• plates of reaction channels are arranged alternately one above the other, alternating with a comparable number of plates of cooling medium channels (FIGS. 2 and 3).
• the plates of reaction channels, which are arranged one above another in alternating fashion, and the cooling medium channels are subdivided into individual replaceable modules (FIGS. 4 and 5).
• at least two modules of superimposed planes of reaction channels and cooling medium channels are operated in parallel under the same reaction conditions, so that a single module can be removed from the process, added to the process or replaced without the operation of the other modules interrupt.
• the temperature in the reaction channels is kept at as constant a temperature as possible by the cooling medium passages through which cooling medium flows.
• this temperature is between 200 0 C and 500 0 C, preferably between 220 0 C and 400 0 C, more preferably between 24O 0 C and 330 0 C.
• the temperature of the reaction channel can be monitored by means of sensors during the process and the flow rate or the temperature of the cooling medium in the cooling medium channels can be adjusted as required.
• the sensors can be arranged either in the region of the cooling medium or in the region of the reaction channel, preferably in the inlet and outlet of the cooling medium.
• the process according to the invention is preferably operated at pressures of from 1 to 30 bar, particularly preferably from 1 to 20 bar, very particularly preferably from 1 to 15 bar.
• the temperature of the Eduktgasgemischs is prior to the reactor inlet, preferably at 200 to 400 0 C.
• the aromatic nitro compound in particular those of the following formula can be hydrogenated:
• Nitrobenzene or the isomeric nitrotoluenes are preferably hydrogenated by the process according to the invention.
• the process can be carried out continuously or in batch, preferably continuously.
• the process according to the invention can be carried out on an industrial scale.
• the space-time yield (kg of aniline per kg of catalyst and h) is between 0.1 and 100 kg / kg / h, preferably between 1 and 50 kg / kg / h and particularly preferably between 2 and 25 kg / kg / H.
• the catalyst-coated reaction channel used according to the invention for the preparation of aromatic amines has significant advantages over conventional catalyst beds known from the prior art.
• the pressure loss in the coated reaction channel at comparable flow rate is much lower than that of catalyst beds. Conversely, the coated reaction channel can be flowed through at the same pressure loss at much higher speeds.
• the very thin catalytically active coating also offers another advantage. If the catalytically active components are deposited in a very thin layer, the influence of diffusion is far less than with full catalysts. If the main reaction is accompanied by subsequent reactions, a higher selectivity can be achieved with these very thin catalytically active coatings. Application in a thin layer may also provide benefits in terms of value product selectivity.
• FIGS. 1 to 5 Exemplary embodiments of the subject invention are shown in FIGS. 1 to 5 without being limited thereto.
• Fig. 1 structured plate with parallel reaction channels (1).
• Fig. 2 Module of alternately superimposed, structured plates for reaction channels (1) and cooling medium channels (2) in the cross flow.
• Fig. 3 Cross-section of a module of alternately superimposed, structured plates for reaction channels (1) and cooling medium channels (2) in cocurrent or countercurrent.
• Fig. 4 Arrangement of parallel operated, replaceable modules.
• Fig. 5 Connections of the reaction channels and the cooling medium channels of two parallel operated modules that can be replaced without interrupting the operation of the other module.
• the average conversion was at the set load of 10 g of nitrobenzene per g of catalyst per hour averaged over the first two hours 91.6%, which corresponds to a space-time yield of 13.8 g of aniline per kg of catalyst per hour.
• the mean selectivity during the period was 99.4%.
• Example 2 Hydrogenation in a cooled catalyst-coated reaction channel
• reaction channels were arranged in parallel.
• the reaction channels each had a length of 50 mm, a width of 0.5 mm and a height of 0.8 mm and were coated on the inside with a catalyst suitable for the hydrogenation of nitrobenzene.
• the starting base used was a catalyst prepared according to Example 1 in DE-A 28 49 002, which was ground to a particle size fraction with d 90 ⁇ 10 ⁇ m.
• the mass of immobilized catalyst was 78.2 mg in the first reactor module and 76.6 mg in the second reactor module.
• the temperature of the incoming reaction gas consisting of 3 g nitrobenzene per hour and 6 ml of hydrogen per hour, was about 240 0 C, the pressure corresponded to atmospheric pressure.
• the nitrobenzene conversion decreased continuously with time.
• the average conversion was 97.2% at the set load of 19.4 g nitrobenzene per g catalyst per hour averaged over the first two hours, giving a space-time yield of 28.4 g aniline per kg catalyst per hour equivalent.
• the mean selectivity during the period was 99.7%.
• the temperatures between the two reactor modules and after the second reactor module were measured continuously, with no increase in temperature was detected. Gas chromatograph analyzes of the products (average values of the first 2 h runtime)

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• 2006
  • 2006-03-14 DE DE102006011497A patent/DE102006011497A1/de not_active Withdrawn
• 2007
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  • 2007-03-01 EP EP07711728A patent/EP2125192A1/de not_active Withdrawn
  • 2007-03-01 BR BRPI0708889-2A patent/BRPI0708889A2/pt not_active IP Right Cessation
  • 2007-03-01 RU RU2008140366/15A patent/RU2008140366A/ru not_active Application Discontinuation
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