WO2000069804A9 - Amination d'hydrocarbures aromatiques et d'analogues heterocycliques de ceux-ci - Google Patents

Amination d'hydrocarbures aromatiques et d'analogues heterocycliques de ceux-ci

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Publication number
WO2000069804A9
WO2000069804A9 PCT/US2000/013266 US0013266W WO0069804A9 WO 2000069804 A9 WO2000069804 A9 WO 2000069804A9 US 0013266 W US0013266 W US 0013266W WO 0069804 A9 WO0069804 A9 WO 0069804A9
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WO
WIPO (PCT)
Prior art keywords
oxide
catalyst
ofthe
benzene
noble metal
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PCT/US2000/013266
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English (en)
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WO2000069804A1 (fr
Inventor
Damodara Poojary
Ramesh Borade
Alfred Hagemeyer
Christopher E Dube
Ziao Ping Zhou
Ulrich Nothels
Ralph Armbrust
Christian Rasp
David M Lowe
Original Assignee
Symyx Technologies Inc
Bayer Ag
Damodara Poojary
Ramesh Borade
Alfred Hagemeyer
Christopher E Dube
Ziao Ping Zhou
Ulrich Nothels
Ralph Armbrust
Christian Rasp
David M Lowe
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Application filed by Symyx Technologies Inc, Bayer Ag, Damodara Poojary, Ramesh Borade, Alfred Hagemeyer, Christopher E Dube, Ziao Ping Zhou, Ulrich Nothels, Ralph Armbrust, Christian Rasp, David M Lowe filed Critical Symyx Technologies Inc
Priority to AU50149/00A priority Critical patent/AU5014900A/en
Publication of WO2000069804A1 publication Critical patent/WO2000069804A1/fr
Publication of WO2000069804A9 publication Critical patent/WO2000069804A9/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
    • C07C209/02—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of hydrogen atoms by amino groups
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

  • the present invention generally relates to the amination of aromatic compounds and to heterocyclic analogs thereof, and specifically, to the direct, catalytic amination of aromatic compounds and heterocyclic analogs thereof.
  • the invention particularly relates, in a preferred embodiment, to the preparation of aniline directly from benzene and ammonia using heterogeneous catalysts.
  • aniline is typically prepared by converting benzene to a derivative, such as nitrobenzene, phenol or chlorobenzene, and then converting the derivative to aniline.
  • a derivative such as nitrobenzene, phenol or chlorobenzene
  • aniline can be produced by direct amination of benzene according to Reaction I:
  • Reaction II is, however, thermodynamically disfavored in the forward direction at reasonable temperatures and pressures. Approaches have been proposed, therefore, to react the hydrogen produced in Reaction I with oxygen to form water, thereby driving the thermodynamic equilibrium in the forward direction, and improving the conversion of benzene to aniline.
  • the overall reaction according to this approach is represented by Reaction II:
  • Thomas et al. disclose effecting the reaction by contacting benzene, ammonia and gaseous oxygen with a platinum catalyst maintained at a temperature of about 1000 °C.
  • Platinum-containing catalysts effective for use in connection with this first embodiment are reported to include, independently, platinum alone, platinum alloyed with certain specifically-recited metals, and platinum combined with certain specifically-recited metal oxides.
  • Thomas et al. disclose effecting the reaction by contacting benzene, ammonia and gaseous oxygen with a platinum catalyst maintained at a temperature of about 1000 °C.
  • Platinum-containing catalysts effective for use in connection with this first embodiment are reported to include, independently, platinum alone, platinum alloyed with certain specifically-recited metals, and platinum combined with certain specifically-recited metal oxides.
  • reducible metal oxides said to be suitable for use in connection with this second embodiment include oxides of Fe, Ni, Co, Sn, Sb, Bi and Cu.
  • a number of processes for the direct amination of benzene and other aromatic hydrocarbons have also involved catalysts comprising noble metals.
  • catalysts comprising noble metals.
  • Becker et al. reported the preparation of aniline by reaction of benzene and ammonia with a gaseous oxygen or carbon monoxide co-feed in a plug-flow or continuous-stirred-tank reactor over a Group VILI-metal catalyst.
  • Specific catalysts ⁇ consisted of, independently, Pd, Pt, Ru, Rh and Ni supported on alumina, and for one experiment, CuO supported on zirconium oxide.
  • catalysts comprising palladium with and without a nitroso-group ligand are compared.
  • the present invention is directed to methods for preparing arylamines or heteroaryl amines.
  • An aromatic hydrocarbon e.g., benzene
  • a heterocyclic analog thereof e.g., pyridine
  • an aminating agent e.g., ammonia
  • the catalyst comprises a noble metal selected from Pd, Rh, Ir and/or Ru and a reducible metal oxide.
  • the catalyst comprises a noble metal and a reducible oxide of a metal selected from Ni, Mn, V, Ce, Tb, Pr, Te, Re, Co, Fe, Cu and/or Bi.
  • the catalyst comprises one or more noble metals selected from Pd, Pt, Rh, Ir, Ru and/or Os, and one or more reducible oxides of a metal selected from Ni, Mn, V, Ce, Tb, Pr, Te, Re, Co, Fe, Cu and/or Bi.
  • the catalyst comprises a noble metal, a first metal oxide and a second metal oxide.
  • the first metal oxide is a reducible metal oxide.
  • the second metal oxide is an oxide of an alkali metal, an alkaline earth metal, a rare earth metal or a selected metal chosen from among Ga, Al, Y, Co, Mo, Cr, Mn, Zn, In, Fe, Bi, Sb or V.
  • the second metal oxide is, in a preferred case, a dopant metal oxide.
  • the catalyst is a supported catalyst and comprises a noble metal and nickel oxide.
  • the noble metal can be selected from Pd, Pt, Rh, Ir and Ru, and is preferably selected from Pd, Rh, Ir and Ru. In some cases, Rh and Ir are particularly preferred noble metals.
  • Nickel oxide can be employed as the reducible metal oxide component alone, or can be employed in combination with other metal oxides, of which manganese oxide is preferred.
  • the invention is directed, moreover, to methods for preparing aniline by direct amination of benzene with ammonia in the presence ofthe catalyst.
  • the catalyst can be any ofthe aforementioned catalysts.
  • benzene and ammonia are reacted in a reaction zone of a reactor without providing an oxygen co-feed (or any co-feed comprising an oxygen-containing gas such as air); that is, benzene and ammonia are reacted without supplying a feed-line to supply an oxygen-containing gas to the reaction zone.
  • the catalyst (or at least a portion thereof) can be regenerated by oxidation (e.g., calcination), after deactivation in a catalyst run, and thereafter used in a series of successive catalyst runs between which the catalyst is again regenerated, up to a total of at least five regeneration cycles (i.e., at least six catalyst runs), without substantial reduction in benzene conversion from run to run and with at least about 90% selectivity for aniline based on weight and relative to benzene in each run.
  • oxidation e.g., calcination
  • the substantially stable benzene conversion for the six or more amination reactions can be characterized by a difference in the benzene conversion for the initial amination reaction (with fresh catalyst) versus the benzene conversion for the amination reaction over the 5- time-regenerated catalyst, with such difference being less than about 50 %, and preferably even smaller (e.g., less than about 25%, less than about 10%, or less than about 5%).
  • the catalyst (or at least a portion thereof) is regenerated by oxidation, but without a separate reduction step. Specifically, the catalyst is exposed to oxidizing conditions to oxidize the metal (or lower oxidation state metal oxide), without exposing the catalyst to reducing conditions during the regeneration protocol. Any noble-metal oxides formed during regeneration are effectively reduced in situ during the next amination reaction.
  • the invention is directed, as well, to catalyst compositions, and to methods for preparing the catalyst compositions.
  • the catalyst compositions are generally characterized as described above.
  • the catalyst composition comprises a noble metal component in an amount ranging from about 0.05 % to about 5% by weight relative to total weight ofthe catalyst, mckel oxide ranging from about 5% to about 50 %, and preferably from about 5% to about 30%, in each case by weight relative to total weight ofthe catalyst, manganese oxide and a support (i.e., a carrier).
  • Manganese is " preferably present in an amount ranging from about 0.5 % to about 30% and more preferably from about 0.5 % to about 20%, while in some cases it ranges from about 0.5% to about 3% and in others from about 10% to about by 20% , in each case by weight relative to total weight ofthe catalyst.
  • the invention is further directed to an unsupported, bulk catalyst composition
  • a noble metal component in an amount ranging from about 0.5% to about 5% by weight relative to the total weight ofthe catalyst, nickel oxide, with the amount of nickel ranging from about 30% to about 90%, and preferably from about 40% to about 80%, in each case by weight relative to the total weight ofthe catalyst, and a binder in an amount ranging from about 10% to about 20%, based on the total weight ofthe catalyst.
  • the catalysts and processes ofthe present invention offer commercially meaningful advantages over the prior art.
  • the catalysts and processes ofthe invention can be employed to prepare aromatic amines and heterocyclic analogs thereof with reproducible, commercially attractive yields. Moreover, such attractive yields can be substantially achieved even after numerous catalyst regeneration cycles.
  • the catalysts and processes ofthe present invention can be used to prepare a number of important chemical intermediates, including, for example, aniline, 4- a inodiphenylamine (4-ADPA), methyldianiline and toluenediimine.
  • Aniline is a commodity chemical useful as an intermediate for the production of many commercially- important materials, including isocyanates, polyurethanes, dyes, pigments, photochemicals, rubber chemicals, specialty fibers, oxidation-inhibiting additives, pesticides and pharmaceuticals, among others.
  • All patents and literature references cited in the instant specification are hereby inco ⁇ orated by reference for all purposes.
  • many relevant references are available to a skilled artisan that will provide further instruction with respect to such subject matter.
  • FIG. 1 is a schematic representation of an exemplary amination reaction, in which benzene is reacted with ammonia in the presence of a catalyst comprising a noble metal (NM) and a reducible metal oxide (MO) to form aniline.
  • NM noble metal
  • MO reducible metal oxide
  • the metal oxide is reduced by hydrogen from the amination reaction, and can be regenerated by oxidation with, for example, molecular oxygen.
  • FIG. 2A through FIG. 2D are schematic representations of a continuous-flow, fixed-bed, tubular plug flow reactor comprising a noble metal / reducible metal oxide (NM / MO) catalyst.
  • NM / MO noble metal / reducible metal oxide
  • aniline (AN) preparation benzene (Bz) and ammonia (NH 3 ) are supplied to the reactor.
  • Bz benzene
  • NH 3 ammonia
  • the reducible metal oxide can be regenerated by oxidizing with gaseous oxygen or an oxygen-containing gas (Fig. 2D).
  • FIG. 2D FIG.
  • 3 A is a schematic representation of one potential embodiment of a two-zone, redox fluidized-bed application ofthe present process
  • 3B is a graph generally depicting the consumption of oxygen and the formation of aniline over the length ofthe fluidized-bed reactor.
  • FIG. 4 is a schematic representation of one potential embodiment of a pulse-feed, fluidized-bed application ofthe present process.
  • a substituted or unsubstituted arylamine or a substituted or unsubstituted heteroarylamine is prepared by direct catalytic amination ofthe corresponding aromatic compound or heterocyclic analog thereof.
  • benzene is aminated in the presence of a heterogeneous catalyst to form aniline.
  • the catalyst generally comprises a noble metal component and a reducible metal oxide component.
  • the noble metal (NM) component catalyzes the amination reaction (Reaction I, above), and the reducible metal oxide (MO) component oxidizes hydrogen produced by the amination reaction to form water and a metal (M) (or a metal oxide in a lower oxidation state), such that the overall reaction proceeds according to Reaction II (above).
  • the catalyst of the present invention can be aptly referred to as a cataloxidant.
  • Combinatorial materials science approaches have been employed to identify useful noble metal / reducible metal oxide cataloxidants, and specifically, to identify noble metal components, reducible metal oxide components, and combinations thereof that are advantageous with respect to reactant conversion, product selectivity and catalyst regenerabihty. Additional components, such as dopant metal oxides, have also been identified as being advantageous with respect to performance and regenerabihty. As such, a number of advantageously useful noble metal / reducible metal oxide cataloxidants have been discovered for the aforementioned amination reactions. Cataloxidants
  • catalyst As used herein, the terms “catalyst,” “cataloxidant” and “cataloreactant” are intended to refer to the compositions ofthe present invention; that is, each term may be used interchangeably herein to refer to compositions which act to catalyze, and which are consumed by, the present process.
  • the noble metal component ofthe cataloxidant ofthe present invention comprises, in the general case, one or more noble metals having catalytic activity for the amination of the aromatic compound or heterocyclic analog of interest.
  • the noble metal component preferably generally comprises Pd, Pt, Rh, Ir, Ru and/or Os.
  • the noble metal component preferably comprises Pd, Rh, Ir and/or Ru.
  • each ofthe preferred noble metals may be specifically preferred for particular reactions and/or for particular reaction conditions.
  • the noble metal component can consist essentially of one ofthe noble metals, or alternatively, can comprise two or more noble metals (e.g., as an alloy of two or more noble metals).
  • the noble metal component comprises a combination of noble metals
  • at least one ofthe noble metals can have catalytic activity for the amination reaction
  • the other noble metal(s) employed in combination therewith can also be catalytically active or can be inert (e.g., Au, Ag), the inert noble metal simply acting to increase the dispersion or physical separation ofthe noble metal particles present.
  • the noble metal component can comprise, for example, two or more ofthe noble metals Au, Ag, Pd, Pt, Rh, Ir and/or Ru, or in some preferred embodiments, two or more ofthe noble metals Au, Pd, Rh, Ir and/or Ru.
  • more than about 50 % ofthe noble metal component can consist essentially of only one of the noble metals. In other such cases, at least about 55%, at least about 60%, at least about 75%, or at least about 90% ofthe noble metal component can consist essentially of one of the noble metals. While the foregoing general preferences have been recited in terms of particular groupings of noble metals, it is to be understood that such preferences may include individually-recited members of such groups as well as any and all possible subsets of such groups, depending on the particular reaction for which the cataloxidant is being applied and on the particular reaction conditions employed.
  • the reducible metal oxide component ofthe cataloxidant ofthe present invention comprises, in the general case, a metal oxide that is reduced to a lower oxidation state when exposed to hydrogen at a temperature of about 200 ° C or greater, and preferably at a temperature ranging from about 200 ° C to about 500 ° C.
  • certain reducible metal oxides have been discovered as being advantageous for use with a noble metal to form a composition suitable for use as a cataloxidant for the amination of aromatic compounds such as aniline.
  • the reducible metal oxide component preferably comprises an oxide of one or more ofthe following metals: Ni, Mn, V, Ce, Tb, Pr, Te, Re, Co, Fe, Cu and/or Bi.
  • the reducible metal oxide component more preferably comprises an oxide of one or more of Ni, Mn, Ce and/or Co, even more preferably comprises an oxide of nickel or an oxide of manganese, and most preferably comprises an oxide of nickel (e.g., NiO).
  • the reducible metal oxide component can consist essentially of an oxide of one ofthe aforementioned metals, such as for example, an oxide of Ni or an oxide of Mn.
  • the reducible metal oxide component can, alternatively, comprise reducible oxides of two or more metals.
  • at least one ofthe reducible metal oxides is preferably a metal selected from Ni, Mn, V, Ce, Tb, Pr, Te, Re, Co, Fe, Cu and/or Bi.
  • the reducible metal oxide component ofthe cataloxidant comprises an oxide of Ni and an oxide of Mn, and in some cases, the reducible metal oxide component can consist essentially of an oxide of Ni and an oxide of Mn. While the foregoing general preferences have been recited in terms of particular groupings of reducible metal oxides, it is to be understood that such preferences may include individually-recited members of such groups as well as any and all possible subsets of such groups, depending on the particular reaction for which the cataloxidant is being applied and on the particular reaction conditions employed.
  • the cataloxidant ofthe invention comprises a noble metal selected from Pd, Rh, Ir and/or Ru and a reducible metal oxide.
  • the cataloxidant ofthe invention comprises a noble metal and a reducible oxide of a metal selected from Ni, Mn, V, Ce, Tb, Pr, Te, Re, Co, Fe, Cu and/or Bi.
  • the preferred noble metals and preferred reducible metal oxides are employed in combination (including all various permutations and combinations thereof), such that the cataloxidant comprises one or more noble metals selected from Pd, Pt, Rh, Ir, Ru and/or Os, and one or more reducible oxides of a metal selected from Ni, Mn, V, Ce, Tb, Pr, Te, Re, Co, Fe, Cu and/or Bi.
  • the particular noble metal / reducible metal oxide catalysts included within the immediately aforementioned generally preferred embodiments are distinguished from the noble metal / reducible metal oxide catalysts known in the art for the amination reactions of interest, particularly from those disclosed in Canadian patent No. 553,988 to Thomas et al.
  • Thomas et al. report that benzene, aniline and gaseous oxygen can be reacted at 1000 °C in the presence of a catalyst comprising Pt in individual combination with oxides of Cr, Mo, W or Nb.
  • the preferred cataloxidants ofthe present invention employ a different noble metal component and/or a different reducible metal oxide component.
  • Pd, Rh, Ir and/or Ru are employed in the noble metal component rather than Pt.
  • Pd, Rh, Ir and Ru are each advantageous over Pt with respect to regenerabihty ofthe cataloxidant.
  • catalysts consisting essentially of platinum and oxides of, independently, Cr, Mo, W or Nb, are not suitably regenerable under the oxidizing conditions that would be required for commercial regeneration. Without being bound by theory, the platinum catalyst particles tend to agglomerate and fuse under such oxidative regeneration conditions, resulting in a reduction of catalyst activity, and a corresponding reduction in desired product (e.g., aniline) yield.
  • the reducible metal oxide component comprises an oxide of a metal other than Cr, Mo, W and Nb - preferably an oxide one or more ofthe following metals: Ni, Mn, V, Ce, Tb, Pr, Te, Re, Co, Fe, Cu and/or Bi.
  • these reducible metal oxides form a cataloxidant that provides for better conversion ofthe aromatic compound (e.g., benzene) and better selectivity for the desired product (e.g., aniline) than the reducible metal oxides disclosed in Thomas et al.
  • the reducible metal oxides of the invention can form a complex with the ammonia or other aminating agent, with the strength of complex being appropriate to achieve substantial aniline selectivity for the temperature ranges of interest.
  • the cataloxidant is advantageous over the prior art noble metal / reducible metal oxide cataloxidants with respect to both performance and regenerabihty.
  • the relative amount ofthe noble metal component and the reducible metal oxide component in the cataloxidant is not narrowly critical, and can vary with the particular reaction being effected, with the form ofthe cataloxidant (e.g., support material, surface area), with the reaction conditions (e.g., temperature, pressure, ratio of reactants, ratio of reactantsxatalyst), and/or with regenerabihty requirements.
  • the form ofthe cataloxidant e.g., support material, surface area
  • reaction conditions e.g., temperature, pressure, ratio of reactants, ratio of reactantsxatalyst
  • the catalyst preferably comprises an amount of noble metal component ranging from about 0.01 % to about 10%), more preferably ranging from about 0.05 % to about 5%, in some cases even more preferably ranging from about 0.1 % to about 5%, or still more preferably ranging from about 0.15 % to about 3%, in each case the percentages being by weight relative to the total weight ofthe catalyst.
  • the catalyst preferably comprises a reducible metal oxide component in an amount ranging from about 5% to about 99.99 %, and more preferably ranging from about 5% to about 75%, in each case by weight relative to the total weight ofthe catalyst.
  • the reducible metal oxide component even more preferably range, particularly where the catalyst is a supported catalyst, from about 5% to about 50%, still more preferably from about 5% to about 30%, or from about 5% to about 20%, in each case by weight relative to the total weight ofthe catalyst.
  • the reducible metal oxide component preferably ranges from about 30% to about 90% and more preferably from about 40% to about 80%, in each case by weight relative to the total weight ofthe catalyst.
  • unsupported catalysts may include, among others, bulk nickel, cobalt or copper catalysts (which are commercially available).
  • these catalysts differ from supported catalyst in that they are prepared by means of precipitation, rather than impregnation. Accordingly, unlike the latter, in which metal loading is dependent upon pore volume, essentially any amount of metal may be incorporated into the unsupported catalysts.
  • Unsupported catalysts preferably have surface areas ranging from about 30 m 2 /g to about 150 m 2 /g, with surface areas ranging from about 50 m 2 /g to about 100 m 2 /g being even more preferred.
  • Regenerabihty ofthe catalyst can, for at least some reducible metal oxides (e.g.,
  • NiO NiO
  • catalyst compositions ranging from about 5% to about 50% by weight relative to total weight ofthe catalyst.
  • the above-recited ranges for the noble metal component and for the reducible metal oxide component can be combined in any ofthe various combinations and permutations. Other, more specific ranges for preferred catalyst compositions are discussed below.
  • the relative molar amount of noble metal component to reducible metal oxide component i.e., the "NM:RMO”
  • the relative molar amount of noble metal component to reducible metal oxide component can, independently ofthe aforementioned weight percentages, range from about 1 :25,000 to about 1:1, preferably from about 1:5,000 to about 1:2, and in some cases from about 1:1000 to about 1:3 or from about 1 : 100 to about 1 :4.
  • the reducible metal oxide component ofthe cataloxidant can be supplied to the reactor as a metal-oxide precursor (e.g., as a metal or lower-oxidation state oxide) and then be oxidized (e.g., calcined) to form the reducible metal oxides.
  • the molar ratio ofthe noble metal component to the reducible metal-oxide precursor i.e., the "NM:RMOP”
  • the NM:RMOP can, independent ofthe aforementioned weight percentages and independent ofthe aforementioned NM:RMO ratios, range from about 1:25,000 to about 1:1, preferably from about 1:5,000 to about 1:2, and in some cases from about 1 : 1000 to about 1 :3 or from about 1 : 100 to about 1 :4.
  • metal oxides preferably when used in the dehydrogenation reaction most ofthe metal atoms (i.e., about 50%, 70%, 90% or more) will be present in an oxidized state, preferably in the form ofthe following oxidation states: Ni +2 ; V *5 ; Fe +3 ; Co +2 or Co +3 (or some combination thereof); Cu +2 ; Mn +2 , Mn +3 or Mn +4 (or some combination thereof); Ce +4 ; Bi +3 ; Pr +4 ; TV 3 or Tb +4 (or some combination thereof); Te +4 or Te " (or some combination thereof); and, Re +4 , Re +6 or Re +7 (or some combination thereof).
  • the cataloxidant ofthe invention can further comprise a second metal oxide component, in addition to the reducible metal oxide component.
  • the second metal oxide component is considered to be a dopant and, as such, is alternatively referred to herein as a dopant oxide component.
  • the second (dopant) metal oxide component can comprise an oxide of a metal selected from the alkali metals (e.g., Li, Na, K and Cs), the alkaline earth metals (e.g., Mg, Ca, Sr, Ba), the rare earth metals (e.g., La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb), and certain other specific selected metals, such other selected metals consisting exclusively of Ga, Al, Y, Co, Mo, Cr, Mn, Zn, In, Fe, Bi, Sb, Cu, Ag and/or V.
  • the second metal oxide component preferably comprises an oxide of Ga, Al, Y, Co, Cr and/or Mn.
  • Manganese oxide is a generally preferred second (dopant) metal oxide.
  • the second metal oxide component can consist essentially of one ofthe aforementioned metal oxides, or alternatively, can comprise two or more ofthe aforementioned metal oxides in combination.
  • the catalyst ofthe present invention comprises a noble metal, a (first) reducible metal oxide, and a (second) dopant metal oxide that is different from the first metal oxide.
  • the second metal oxide component can also be employed as a further component ofthe previously discussed first, second and third generally preferred embodiments.
  • the dopant metal oxide component appears to improve and/or maintain the dispersion of noble metal and/or reducible metal oxide on the support or carrier, particularly after regeneration.
  • the dopant metal oxide component can also improve electron or oxygen ion conductivity ofthe catalyst material and, as such, can lead to higher solid oxidant efficiencies.
  • the dopant oxide component can be important for some cataloxidants ofthe invention with respect to regenerabihty thereof.
  • some dopant metal oxides such as oxides of alkali metals or oxides of alkaline earth metals, can increase the basicity ofthe cataloxidant and, as such, help reduce ammonia adsorption to the catalyst and ultimately reduce ammonia decomposition.
  • the alkali and alkaline oxide dopants also help to "disrobe" aniline from the catalyst surface.
  • the relative amount ofthe dopant oxide component can range from about 0.05 % to about 30%, more preferably from about 0.05% to about 20%, and even more preferably from about 0.1% to about 10%, in each case by weight relative to total weight ofthe catalyst. In some embodiments, the amount of dopant oxide component can preferably range from about 0.1% to about 5% and, in some cases, from about 0.5% to about 5%, from about 1% to about 5%, or from about 2% to about 5%, in each case by weight relative to total weight ofthe catalyst.
  • the above-recited weight-based ranges for the dopant oxide component can be combined in any combination and permutation with the previously recited ranges for the noble metal component and for the reducible metal oxide component.
  • the relative molar amount of noble metal component to second (dopant) oxide component can, independently of the aforementioned weight percentages, range from about 1 : 1000 to about 250:1, preferably from about 1:200 to about 10:1, and in some cases from about 1:100 to about 5:1.
  • the dopant metal oxide component ofthe cataloxidant can be supplied to the reactor as a metal-oxide precursor (e.g., as a metal or lower-oxidation state oxide) and then be oxidized (e.g., calcined) to form the dopant metal oxide.
  • the molar ratio ofthe noble metal component to the dopant metal-oxide precursor can, independent ofthe aforementioned weight percentages and independent ofthe aforementioned NM:DMO ratios, range from about 1:2000 to about 250:1, preferably from about 1 :400 to about 10:1, and in some cases from about 1:200 to about 5:1.
  • Some ofthe metal oxides disclosed as suitable for inclusion in the reducible metal oxide component ofthe catalyst are also suitable for inclusion in the dopant oxide component ofthe catalyst.
  • such commonly-included oxides e.g., manganese oxides
  • a common metal oxide e.g., Mn
  • Mn a common metal oxide
  • Such a common metal oxide can be considered to be a part ofthe second (dopant) metal oxide component if it is present in the catalyst in a proportion of less than 5% by weight relative to the total weight ofthe catalyst.
  • the cataloxidants ofthe present invention are employed in commercial applications as solid materials, typically with gaseous and/or liquid reactants. As such, the cataloxidants ofthe present invention are heterogeneous catalysts. However, the particular physical form ofthe catalysts (including the degree of crystallinity or the particular crystalline structure) may vary substantially and is not generally of critical significance. Moreover, the cataloxidants disclosed and claimed herein can be employed as supported or unsupported catalysts. The catalysts ofthe present invention are preferably supported. The particular support material and/or form is not, however, generally critical and selection of support material and/or form can be effected for a particular cataloxidant according to approaches known in the art. The supports can include any suitable inert and stable support material.
  • the support can comprise, for example, zirconium dioxide, titanium dioxide, alumina, tantalum oxide, niobium oxide, silica, diatomaceous earth and zeolites among other materials.
  • Zirconium dioxide e.g., Norton Chemical Products Corp.
  • titanium dioxide e.g., Norton Chemical Products Corp.; Degussa
  • the supports are, in general, preferably porous, having a porosity, pore structure, pore size distribution, pore volume and surface area suitable to provide substantial dispersion ofthe noble metal component and/or the metal oxide component. Improving the dispersion of noble metal component and/or metal oxide component can favorably affect the regenerabihty ofthe cataloxidant.
  • typical support surface areas can range from about 1 m 2 /g to about 300 m 2 /g, and more typically from about 10 m 2 /g to about 150 m 2 /g, with a surface area of about 50 m 2 /g being appropriate in some applications.
  • the pore volume of these supports typically ranges from about 0.2 cc/g to about 1 cc/g, and more typically from about 0.3 cc/g to about 0.7 cc/g.
  • the mechanical stability ofthe supports should preferably be sufficient to retain structural integrity thereof after repeated cycles of catalyst regeneration.
  • the shape and size ofthe support material are not critical, and can include the many variations known in the art, including, for example, monoliths, cylinders, tablets, pellets, granules, corrugated sheets, shaped-extrudates, etc.
  • the particular shape and/or particle size can vary, for example, depending upon the reactor and/or process configuration to be employed.
  • the pore volume may decrease by about 2% to about 30%, while the surface area may also decrease by about 2% to about 30%.
  • the supports can be modified and/or pretreated with various agents to facilitate catalyst preparation, to improve mechanical properties ofthe support and/or to improve the performance characteristics and/or regenerabihty ofthe catalyst.
  • the support can, for example, be modified with respect to acidity / basicity.
  • the supports are preferably neutral or slightly basic (i.e., non-acidic) to reduce the preference for ammonia adsorption.
  • an acidic support material e.g., titanium dioxide, alumina, silica
  • an alkali metal oxide or an alkaline earth metal oxide such as oxides of potassium, lithium, sodium, rubidium, magnesium, calcium, barium, cesium or strontium.
  • preferred support materials include the relatively neutral zirconium dioxide, as well as alkali-oxide-doped or alkaline-earth-oxide-doped (e.g., potassium- impregnated) titanium dioxide.
  • alkali-oxide-doped or alkaline-earth-oxide-doped e.g., potassium- impregnated titanium dioxide.
  • alkali metal oxides or alkaline-earth metal oxides can be considered to be a dopant oxide component ofthe cataloxidant.
  • dopant oxides can be integrated with the other cataloxidant components, particularly in terms of catalyst preparation.
  • such dopant oxides can be prepared as a modified support onto which the other catalyst components are subsequently added. It may be preferable for some catalysts and for some reactions to modify the support to form the oxide-doped support prior to preparation ofthe catalyst thereon, because different calcination conditions can be employed independent ofthe catalyst components and/or precursors thereof. Such an approach can, in some cases, result in a preferred crystalline structure for the support than would otherwise be achieved if the doping alkali or alkaline earth metal oxide were prepared as part ofthe general catalyst preparation steps outlined below.
  • An oxide-doped support can be prepared, for example, by impregnating the support with an alkali metal or an alkaline earth metal in an amount ranging from about 0.1 % to about 10%, from about 0.5% to about 7.5%, or from about 1% to about 5% by weight, relative to total weight of the support, and then calcining in oxidizing conditions at temperature of about 550 °C or higher.
  • the support will, in any case, typically comprise at least about 50%, and can comprise at least about 60% ofthe resulting catalyst, in each case by weight relative to total weight ofthe supported catalyst.
  • the catalyst comprises the support in an amount ranging from about 70% to about 95%, and preferably from about 80% to about 90%, in each case by weight relative to total weight ofthe supported catalyst.
  • the supports can be supplied to and integrated with the cataloxidant in any of a number of different ways, including for example as a separate component (e.g., as with wet-impregnation approaches for catalyst preparation) and/or as an integrated structure (e.g., as with sol-gel approaches for catalyst preparation).
  • Other additives and agents, such as binders and/or forming agents, can also be included with the catalysts.
  • the cataloxidants of the present invention can comprise a noble metal component in an amount ranging from about 0.05 % to 5% (preferably from about 0.1% to about 5%, and more preferably from about 0.5 % to about 2%), a reducible metal oxide in an amount ranging from about 5% to about 50% (preferably from about 5% to about 30%, and more preferably from about 10% to about 20%), and a support, with percentages in each case being by weight relative to the total weight ofthe catalyst.
  • a specifically preferred cataloxidant ofthe invention can comprise a noble metal component in an amount ranging from about 0.05 % to 5% (preferably from about 0.1 % to about 5%, and more preferably from about 0.5 % to about 2%), a reducible metal oxide in an amount ranging from about 5% to about 50% (preferably from about 5% to about 30%, and more preferably from about 10% to about 20%), a second (dopant) oxide component in an amount ranging from about 0.1 % to about 5% (preferably from about 0.5 % to about 5%, and more preferably from about 1% to about 2%), and a support, with percentages in each case being by weight relative to total weight ofthe catalyst.
  • Pd refers to palladium
  • Pt refers to platinum
  • Rh refers to rhodium
  • Ir refers to iridium
  • Ru refers to ruthenium
  • Os refers to osmium
  • Au gold
  • Ag refers to silver
  • Ni refers to nickel
  • Mn manganese
  • V refers to vanadium
  • Ce refers to cerium
  • Tb refers to terbium
  • Pr refers to praseodymium
  • Te refers to tellurium
  • Re refers to rhenium
  • Co refers to cobalt
  • Bi refers to bismuth
  • Cr refers to chromium
  • Mo refers to molybdenum
  • W refers to tungsten
  • Nb refers to niobium
  • Ga gallium
  • Al refers to aluminum
  • Y refers to ytt
  • the noble metal component ofthe cataloxidant can comprise noble metals in their fully reduced (ground) state, but may also include noble metals in their partially or fully oxidized state.
  • oxide forms ofthe noble metals e.g., oxides of Rh
  • the metal oxide components can comprise any ofthe various oxides associated with a particular metal; that is, the particular metal may be in a partially or fully oxidized state.
  • the particular oxidation state of a particular metal oxide will vary depending on the conditions to which the metal/metal oxide is exposed and thermodynamic considerations. The various oxidation states, the particular molecular structure associated therewith, and the thermodynamic stability thereof at various conditions is well known in the art.
  • the metal oxides can be supplied to the catalyst composition (and to the reactor) as metals in their fully- reduced states (e.g., ground states), or in a lower-oxidation state than the desired oxidation state, and then oxidized as a pretreatment step.
  • their fully- reduced states e.g., ground states
  • the catalysts can be prepared by suitable methods presently known or later developed in the art.
  • Exemplary preferred methods for preparing the cataloxidants include impregnation approaches, co-precipitation approaches, sol-gel approaches, lyophilization (freeze-drying) approaches, spray-drying approaches, and/or slurrying/solvent evaporation approaches.
  • the noble metal / reducible metal oxide catalysts are typically prepared from precursor solutions or dispersions and then treated, either external to the reaction zone ofthe reactor before the reaction and/or in situ in the reaction zone ofthe reactor during the amination reaction.
  • a noble metal precursor solution can comprise, for example, the noble metal of interest and/or oxides or safts thereof.
  • the reducible metal-oxide precursor solution can comprise the metal oxide in the desired oxidation state, an oxide ofthe metal in a relatively lower or higher oxidation state, and/or salts thereof.
  • the noble-metal precursor solution and metal-oxide precursor solution are solutions of metal salts in water, and preferably in halide-free (e.g., chloride-free) water.
  • a support material e.g., ZrO 2
  • pretreated e.g., calcined at moderate temperatures, such as from about 80 °C to about 250 °C, and preferably at about 110 °C, to remove adsorbed gases or water
  • the precursor solutions are preferably combined in the appropriate desired ratios, with the total volume ofthe combined solution being equal to the measured pore volume.
  • the support material can then be impregnated with the combined precursor solutions.
  • the various metal precursor solutions can be applied to the support material individually and sequentially. Several impregnation steps may be required, particularly for larger precursor solution volumes.
  • the impregnated supports are typically dried slowly (e.g., at temperatures ranging from about 80 °C to about 110 °C for a few hours) and then oxidatively calcined (e.g., in air or oxygen at a temperature of about 300 °C to about 600 °C for a few hours) to form a reducible metal oxide in a higher oxidized state.
  • the noble metals included in the cataloxidant composition are likewise oxidized (e.g., Rh, and to a lesser degree, Ir, Ru and or Pd), these oxidized noble metals can be selectively reduced in a further pretreatment step and/or in situ during an early part ofthe amination reaction.
  • the cataloxidants can be heated to a temperature of about 150 ° C to about 200 ° C in an atmosphere comprising hydrogen, to selectively reduce the noble metal (without substantially reducing the reducible metal oxide).
  • the cataloxidants can be heated in an inert atmosphere (e.g., nitrogen) to remove contaminants therefrom.
  • an inert atmosphere e.g., nitrogen
  • metal oxides component ofthe invention are prepared from metal oxide precursors, it may be necessary to convert the known precursor weight to the weight ofthe oxide actually in the catalyst.
  • metal oxide components i.e., reducible metal oxides or dopant metal oxides
  • a catalyst composition prepared from definitive amounts of metal-oxide precursors (e.g., nitrate salts ofthe corresponding metal) followed by oxidative calcination to the oxide, it is assumed that the most likely dominant thermodynamically-stable oxidation state(s) ofthe oxide is (are) formed.
  • oxidation of Ni metal is assumed, for purposes herein, to form an oxide consisting substantially of NiO.
  • Oxidation of Mn metal is assumed, for purposes herein, to form an equimolar mixture of manganese oxides - specifically, Mn 2 O 3 and MnO 2 on a 50 % / 50 % molar basis.
  • aromatic hydrocarbons and Heterocyclic Analogs Thereof The cataloxidants ofthe invention can be employed to effect the conversion of an aromatic hydrocarbon or a heterocyclic analog thereof to its corresponding arylamine or heteroarylamine.
  • aromatic hydrocarbon refers to an unsaturated cyclic hydrocarbon comprising one or more rings and having exclusively aromatic C-H bonds (rather than aliphatic C-H bonds).
  • aromatic hydrocarbons ofthe invention comprise, in preferred embodiments, one or more 5-carbon or 6-carbon rings.
  • a heterocyclic analog of an aromatic hydrocarbon refers to such unsaturated cyclic hydrocarbons in which one or more ofthe ring-carbon atoms have been replaced with a heteroatom selected from the group consisting of N, O and S.
  • the aromatic hydrocarbons and heterocyclic analogs thereof are collectively referred to herein, alternatively, as the "aromatic reactants" ofthe invention.
  • the aromatic hydrocarbon and/or the heterocyclic analog thereof can be unsubstituted or substituted.
  • a substituted aromatic hydrocarbon or a substituted heterocyclic analog thereof is a compound in which one or more ofthe hydrogen atoms bonded to a carbon atom or to a heteroatom ofthe ring is replaced by another group, such as, without limitation, alkyl, alkenyl, alkynyl, substituted alkyl, substituted alkenyl, substituted alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, substituted heteroalkyl, substituted heteroalkenyl, substituted heteroalkynyl, cycloalkyl, cycloalkenyl, substituted cycloalkyl, substituted cycloalkenyl, halogen, hydroxy, alkoxy, aryloxy, amino, amide, thio and phosphino.
  • substituents for the aromatic hydrocarbon or heterocyclic analog thereof are those moieties selected from the group consisting of C,. 6 alkyls, C, .6 alkenyls, C,_ 6 alkynyls, C 3.g cycloalkyls, C 3 .
  • cycloalkenyls alkoxy, aryloxy, amino and amido
  • C U6 alkyls, alkenyls or alkynyls refers to one or more the respective groups having from one to six carbon atoms in the main chain
  • C 3.g cycloalkyls or cycloalkenyls refers to one or more the respective ring structures having from three to eight carbon atoms.
  • the number of substituents groups on a substituted aromatic hydrocarbon or heterocyclic analog thereof is not critical, and will generally depend on the particular aromatic hydrocarbon / heterocyclic analog and/or on the reactivity ofthe substituents.
  • the aromatic hydrocarbon or heterocyclic analog thereof has at least one hydrogen atom bonded to a carbon or to a heteroatom ofthe aromatic or heterocyclic analog ring structure.
  • a six-member ring preferably has five or less substituent groups, and a five-member ring preferably has four or less substituent groups.
  • the number of substituent groups on a six-member ring can be four or less, or even three or less.
  • the number of substituent groups on a five-member ring can be three or less or even two or less.
  • aromatic hydrocarbon and/or heterocyclic analog thereof can be represented by compounds having the formula:
  • A is, independently, aryl or heteroaryl.
  • A can be selected from the group consisting of phenyl, diphenyl, benzyl, dibenzyl, napthyl, anthracene (i.e., anthra), pyridyl and quinoline.
  • the subscript "n” is an integer generally ranging from 0 to 5, especially in connection with six-membered aryl or heteroaryl groups.
  • the value of "n” can also range from 0 to 4, especially in connection with five-membered aryl or heteroaryl groups.
  • the value of "n” more preferably ranges, in the general case, from 0 to 3, from 0 to 2, or from 0 to 1.
  • B is independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, substituted alkyl, substituted alkenyl, substituted alkynyl, heteroalkyl, substituted heteroalkyl, cycloalkyl, cycloalkenyl, substituted cycloalkyl, substituted cycloalkenyl, halogen, hydroxy, alkoxy, aryloxy, carbonyl, amino, amido, thio and phosphino.
  • B can be independently selected from the group consisting of hydrogen, C,_ 6 alkyl, C,_ 6 alkenyl, C 6 alkynyl, C 3 .
  • a particularly recited "A" group or "B” group will generally have the structure that is recognized in the art as corresponding to groups having that name.
  • representative B groups as enumerated above are defined herein. These definitions are intended to supplement and illustrate, not preclude or replace the definitions known to those of skill in the art.
  • alkyl is used herein to refer to a branched or unbranched, saturated acyclic hydrocarbon radical.
  • exemplary alkyl radicals include, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, i-butyl (or 2-methylpropyl), etc.
  • alkyls have between 1 and 50 carbon atoms, between 1 and 20 carbon atoms, between 1 and 6 carbon atoms or between 1 and 3 carbon atoms.
  • alkenyl is used herein to refer to a branched or unbranched acyclic hydrocarbon radical having at least one carbon-carbon double bond.
  • alkenyl radicals include, for example, 2-propenyl (or allyl), vinyl, etc.
  • alkenyls have between 1 and 50 carbon atoms, between about 1 and 20 carbon atoms, between about 1 and 6 carbon atoms, or between about 1 and 3 carbon atoms.
  • this term embraces radicals having both "cis” and “trans” orientations, or alternatively, "E” and "Z” orientations.
  • alkynyl is used herein to refer to a branched or unbranched acyclic hydrocarbon radical having at least one carbon-carbon triple bond.
  • alkynyls have between 1 and 50 carbon atoms, between about 1 and 20 carbon atoms, between about 1 and 6 carbon atoms, or between about 1 and 3 carbon atoms.
  • Substituted alkyl refers to the alkyl, alkenyl and alkynyl radicals, respectively, as just described in which one or more hydrogen atoms to any carbon of these radicals is replaced by another group such as a heteroatom, halogen, aryl, substituted aryl, cycloalkyl, cycloalkenyl, substituted cycloalkyl, substituted cycloalkenyl and combinations thereof.
  • Exemplary substituted alkyls include, for example, benzyl, trifluoromethyl and the like.
  • heteroalkyl refers to the alkyl, alkenyl and alkynyl radicals, respectively, described above in which one or more ofthe carbon chain atoms of these radicals is replaced by a heteroatom selected from the group consisting of N, O and S.
  • the bond between another carbon atom and the heteroatom may be saturated or, in some cases, unsaturated.
  • cycloalkyl is used herein to refer to a saturated cyclic non-aromatic hydrocarbon radical having a single ring or multiple condensed rings.
  • exemplary cycloalkyl radicals include, for example, cyclopentyl, cyclohexyl, cyclooctanyl, bicyclooctyl, etc.
  • cycloalkyls have between 3 and 50 carbon atoms, between 3 and 20 carbon atoms, between 3 and 8 carbon atoms, or between 3 and 6 carbon atoms.
  • cycloalkenyl is used herein to refer to a partially unsaturated (i.e., having at least one carbon-carbon double bond), cyclic non-aromatic hydrocarbon radical having a single ring or multiple condensed rings.
  • exemplary cycloalkenyl radicals include, for example, cyclopentenyl, cyclohexenyl, cyclooctenyl, etc.
  • cycloalkenyls have between 3 and 50 carbon atoms, between 3 and 20 carbon atoms, between 3 and 8 carbon atoms, or between 3 and 6 carbon atoms.
  • Substituted cycloalkyl and “substituted cycloalkenyl” refer to cycloalkyl and cycloalkenyl radicals, respectively, as just described wherein one or more hydrogen atoms to any carbon of these radicals is replaced by another group such as a halogen, alkyl, alkenyl, alkynyl, substituted alkyl, substituted alkenyl, substituted alkynyl, aryl, substituted aryl, cycloalkyl, cycloalkenyl, substituted cycloalkyl, substituted cycloalkenyl, heterocyclo, substituted heterocyclo, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, boryl, phosphino, amino, silyl, thio, seleno and combinations thereof.
  • Exemplary substituted cycloalkyl and cycloalkenyl radicals include, for example, 4- dimethylaminocyclohexyl
  • aryl is used herein to refer to an aromatic substituent which may be a single aromatic ring or multiple aromatic rings which are fused together, linked covalently, or linked to a common group such as a methylene or ethylene moiety.
  • the common linking group may also be a carbonyl as in benzophenone or oxygen as in diphenylether or nitrogen in diphenylamine.
  • the aromatic ring(s) may include phenyl, naphthyl, diphenyl, diphenylether, diphenylamine and benzophenone among others.
  • aryls have between 1 and 50 carbon atoms, between 1 and 20 carbon atoms, between 1 and 8 carbon atoms, or between 1 and 6 carbon atoms.
  • Substituted aryl refers to aryl as just described in which one or more hydrogen atom to any carbon is replaced by one or more functional groups such as alkyl, alkenyl, alkynyl, substituted alkyl, substituted alkenyl, substituted alkynyl, cycloalkyl, cycloalkenyl, substituted cycloalkyl, substituted cylcoalkenyl, heterocyclo, substituted heterocyclo, halogen, alkylhalos (e.g., CF 3 ), hydroxy, amino, phosphino, alkoxy, amino, thio and both saturated and unsaturated cyclic hydrocarbons which are fused to the aromatic ring(s), linked covalently or linked to a common group such as a methylene or ethylene moiety.
  • the linking group may also be a carbonyl such as in cyclohexyl phenyl ketone.
  • heterocyclo is used herein to refer to saturated, partially unsaturated and unsaturated cyclic radicals (including, for example, cycloalkyl and cycloalkenyl radicals as described), wherein one or more or all carbon atoms ofthe radical are replaced by a heteroatom such as nitrogen, oxygen or sulfur.
  • heteroaryl refers to a specific example of a class of unsaturated cyclic radicals wherein one or more carbon atoms of an aromatic ring or rings are replaced by a heteroatom(s) such as nitrogen, oxygen or sulfur.
  • Heteroaryl refers to structures that may be a single aromatic ring, multiple aromatic ring(s), or one or more aromatic rings coupled to one or more nonaromatic ring(s). In structures having multiple rings, the rings can be fused together, linked covalently, or linked to a common group such as a methylene or ethylene moiety.
  • the common linking group may also be a carbonyl as in phenyl pyridyl ketone.
  • rings such as thiophene, pyridine, isoxazole, phthalimide, pyrazole, indole, furan, etc.
  • heteroaryl or benzo-fused analogues of these rings are defined by the term "heteroaryl.”
  • heteroaryl Other exemplary heterocyclo radicals include, for example, piperazinyl, morpholinyl, tetrahydropyranyl, tetrahydrofuranyl, piperidinyl, pyrrolidinyl, oxazolinyl, and the like.
  • Substituted heterocyclo and “substituted heteroaryl” refer to heterocyclo and/or heteroaryl radicals as just described wherein one or more hydrogen atom to any atom of the radical is replaced by another group such as a halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, boryl, phosphino, amino, silyl, thio, seleno and combinations thereof.
  • exemplary substituted heteroaryl radicals include, for example, 4-N,N-dimethylaminopyridine.
  • Other exemplary substituted heterocyclo radicals include, for example, N-methylpiperazinyl, 3- dimethylaminomorpholine, and the like.
  • alkoxy is used herein to refer to the -OZ 1 radical, where Z 1 is selected from the group consisting of alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heterocycloalkyl, substituted heterocycloalkyl, silyl groups and combinations thereof as described herein.
  • exemplary alkoxy radicals include, for example, methoxy, ethoxy, benzyloxy, t-butoxy, etc.
  • aryloxy where Z 1 is selected from the group consisting of aryl, substituted aryl, heteroaryl, substituted heteroaryl, and combinations thereof. Examples of suitable aryloxy radicals include phenoxy, substituted phenoxy, 2-pyridinoxy, 8-quinalinoxy and the like.
  • silyl refers to the -SiZ'Z 2 Z 3 radical, where each of Z 1 , Z 2 , and Z 3 is independently selected from the group consisting of alkyl, substituted alkyl, cycloalkyl, heterocycloalkyl, heterocyclic, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, amino, silyl and combinations thereof.
  • boryl refers to the -BZ'Z 2 group, where each of Z 1 and Z 2 is independently selected from the group consisting of alkyl, substituted alkyl, cycloalkyl, heterocycloalkyl, heterocyclic, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, amino, silyl and combinations thereof.
  • phosphino refers to the group -PZ'Z 2 , where each of Z 1 and Z 2 is independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, cycloalkyl, heterocycloalkyl, heterocyclic, aryl, heteroaryl, silyl, alkoxy, aryloxy, amino and combinations thereof.
  • amino is used herein to refer to the group -NZ'Z 2 , where each of Z 1 and Z 2 is independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heterocycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, silyl and combinations thereof.
  • thio is used herein to refer to the group — SZ 1 , where Z 1 is selected from the group consisting of hydrogen; alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heterocycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, silyl and combinations thereof.
  • seleno is used herein to refer to the group -SeZ 1 , where Z 1 is selected from the group consisting of hydrogen; alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heterocycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, silyl and combinations thereof.
  • saturated refers to lack of double and triple bonds between atoms of a radical group such as ethyl, cyclohexyl, pyrrolidinyl, and the like.
  • unsaturated refers to the presence one or more double and triple bonds between atoms of a radical group such as vinyl, acetylenyl, oxazolinyl, cyclohexenyl, acetyl and the like.
  • the cataloxidants ofthe invention are employed for amination of an aromatic hydrocarbon selected from, independently, benzene, napthalene, anthracene, toluene, xylene, phenol and aniline, or for amination of heterocyclic analogs selected from, independently, pyridine and quinoline.
  • aromatic hydrocarbons and/or heterocyclic analogs thereof for which the cataloxidants ofthe invention will find applications are disclosed, for example, in U.S. Patent No. 3,919,155 to Squire (see Col. 5 at lines 15-62).
  • cataloxidants ofthe invention are more preferably used for amination of benzene, toluene, aniline and/or a mixture of two or more ofthe same.
  • benzene is catalytically aminated in the presence ofthe cataloxidants to form aniline.
  • the aromatic reactants i.e., the aromatic hydrocarbons or heterocyclic analogs thereof
  • an aminating agent in the presence ofthe cataloxidiants to form the corresponding arylamine or heteroarylamine.
  • the aminating agents employed in the reaction are not critical, and can generally include a compound or salt comprising or capable of leaving a -NH 2 moiety.
  • Ammoma is a preferred aminating agent.
  • Ammonium salts such as ammonium carbonate or ammonium carbamate can also be employed.
  • Substituted amines such as alkylamines (e.g., methylamine, and other primary alkylamines), hydroxyamines and alkoxyamines can also be suitably used as aminating agents. Hydrazine can also be an aminating agent.
  • the aminating agents can also be characterized as including compounds (e.g., urea) that decompose to form ammonia in situ in the reaction zone under the reaction conditions therein.
  • the aromatic reactant e.g., benzene
  • the aminating agent in the presence of one ofthe above-described cataloxidants to form an arylamine or heteroarylamine reaction product (e.g., aniline).
  • the aromatic reactant and the aminating agent are supplied to a reaction zone of a reactor, and are allowed to interact with each other on a molecular level in the reaction zone.
  • the aromatic reactant and/or the aminating agent contact the catalyst under reaction conditions suitable to effect the amination reaction of interest.
  • the reactor can be a batch reactor or a flow reactor.
  • the particular type of reactor is, however, not critical, and can include a variety of reactor types and configurations known in the art of heterogeneous catalysis.
  • Typical reactors include, for example, pressure-vessel batch reactors, autoclaves, fixed-bed plug-flow reactors, fluidized-bed reactors, continuous-stirred tank reactors, bubble-reactors, etc., each of which should be operable at and capable of providing the conditions (e.g., temperature, pressure, residence time) that favor the reaction of interest.
  • the reactor configuration can be a single reactor, a series of single reactors and or two or more parallel reactors.
  • the reaction-process configuration can include batch reactions, semi-continuous reactions and/or continuous reactions.
  • reactor designs, reactor configurations and reaction-process configurations can vary depending on the amination reaction of interest, the phase-state of the aromatic reactant and/or the aminating agent, the required contact times, as well as the particular nature of the cataloxidant.
  • the amination reaction is effected in a high-pressure batch reactor, a continuous-flow fixed-bed reactor, or a fluidized-bed reactor.
  • the reactor can be a batch reactor or a flow reactor.
  • the particular type of reactor is, however, not critical, and can include a variety of reactor types and configurations known in the art of heterogeneous catalysis.
  • Typical reactors include, for example, pressure-vessel batch reactors, autoclaves, fixed-bed plug-flow reactors, fluidized-bed reactors, continuous-stirred tank reactors, bubble-reactors, etc., each of which should be operable at and capable of providing the conditions (e.g., temperature, pressure, residence time) that favor the reaction of interest.
  • the reactor configuration can be a single reactor, a series of single reactors and/or two or more parallel reactors.
  • the reaction-process configuration can include batch reactions, semi-continuous reactions and/or continuous reactions.
  • reactor designs, reactor configurations and reaction-process configurations can vary depending on the amination reaction of interest, the phase-state of the aromatic reactant and/or the aminating agent, the required contact times, as well as the particular nature ofthe cataloxidant.
  • the amination reaction is effected in a high-pressure batch reactor, a continuous-flow fixed-bed reactor, or a fluidized-bed reactor.
  • the present process is preferentially carried out in a two-zone, redox fluidized-bed reactor or, alternatively, in a pulsed fluidized-bed reactor.
  • the two-zone, redox fluidized-bed reactor concept has previously been proposed for different reaction systems by, for example, J. Soler et al. (oxidative dehydrogenation of hydrocarbons; Catalyst Letters, 50, pp. 25-30 (1998); Ind. Eng. Chem. Res., 38, pp. 90-97 (1999)), R. Ramos et al. (oxidation of hydrocarbons; J. of Catalysis, 163, pp. 218-221 (1996)), and P.
  • the two-zone reactor is employed as follows: reactant gases (i.e., the aromatic hydrocarbon or heterocyclic analog thereof, and the aminating agent, such as benzene and ammonia, respectively) and an oxygen-containing gas are continuously fed or introduced into a fluidized-bed gas/solid contact zone comprising a fluidized particulate catalyst suspended in a process gas stream flowing through the contact zone.
  • reactant gases i.e., the aromatic hydrocarbon or heterocyclic analog thereof, and the aminating agent, such as benzene and ammonia, respectively
  • an oxygen-containing gas are continuously fed or introduced into a fluidized-bed gas/solid contact zone comprising a fluidized particulate catalyst suspended in a process gas stream flowing through the contact zone.
  • the castalyst is active for promoting the amination ofthe aromatic heterocycle, or analog thereof, to the corresponding amine (for example, benzene to aniline), and is subject to reduction in a redox reaction with hydrogen gas produced as a by-product ofthe reaction between the given reactant and the aminating agent, and is further subject to reoxidation by redox reaction with molecular oxygen.
  • the process gas stream comprises the gases introduced into the contact zone as well as the reaction products produced therein.
  • the point of introduction of oxygen into the fluidized-bed contact zone is spaced upstream from the point of introduction of benzene into the contact zone, with respect to the direction ofthe process gas flow through the contact zone. It is to be further noted that the velocity ofthe gas flow, the particle size and the configuration ofthe suspended catalyst and the geometric configuration ofthe gas/liquid contact zone are such that the process gas flows through the contact zone substantially in plug flow (i.e., the process gas flows through the contact zone without substantial axial back- mixing), while the suspended catalyst is substantially back-mixed therein.
  • the reactant hydrocarbon is oxidatively aminated by the cataloxidant downstream ofthe point of introduction of oxygen into the reaction zone, and thereof this reaction occurs in the substantial absence ofthe gaseous oxygen feed; that is, the oxygen content is less than about 1000 ppma relative to the concentration ofthe aromatic hydrocarbon (i.e., benzene) or heterocyclic analog thereof, and is preferably less than about 500 ppm, 250 ppm, 100 ppm or less.
  • the spent cataloxidant i.e., the reduced cataloxidant
  • the pulsed feed fluidized-bed reactor takes advantage ofthe plug flow manner by which gases proceed through the cataloxidant bed, as well. More specifically, referring now to Fig. 4, in this approach a gaseous aromatic hydrocarbon, or an analog thereof, a gaseous aminating agent and oxygen (or an oxygen-containing gas) are introduced into a process gas stream that flows through a fluidized bed gas/solid contact zone which comprises a fluidized particulate catalyst suspended in the process gas stream.
  • the catalyst as previously noted, is active for promoting the amination ofthe aromatic hydrocarbon or the analog thereof to the corresponding amine (for example, benzene to aniline), is subject to reduction in a redox reaction with hydrogen gas produced as a by-product ofthe reaction between the aromatic hydrocarbon and the aminating agent, and is subject to reoxidation by redox reaction with molecular oxygen.
  • the process gas stream comprises the gases introduced into the contact zone as well as the reaction products produced therein.
  • the introduction of oxygen into the gas/solid contact zone and the process gas stream is temporally alternated with the introduction ofthe aromatic hydrocarbon or analog thereof and the aminating agent into the process gas stream so that molecular oxygen gas is substantially absent from said process gas in any region ofthe contact zone containing an excess ofthe aminating agent and/or the aromatic hydrocarbon with respect to oxygen (i.e, the oxygen content is less than about 1000 ppma relative to the concentration ofthe aromatic hydrocarbon (i.e., benzene) or heterocyclic analog thereof, and is preferably less than about 500 ppm, 250 ppm, 100 ppm or less, while the aromatic hydrocarbon analog thereof and the aminating agent are substantially absent from said process gas in any region ofthe gas/solid contact zone containing an excess of molecular oxygen gas with respect to these.
  • the oxygen content is less than about 1000 ppma relative to the concentration ofthe aromatic hydrocarbon (i.e., benzene) or heterocyclic analog thereof, and is preferably less than about 500 ppm, 250
  • the velocity of gas flow, the particle size and configuration ofthe suspended catalyst and the geometric configuration ofthe gas/liquid contact zone are such that the process gas flows through the contact zone substantially in plug flow (i.e., the process gas flows through the contact zone without substantial axial back-mixing), while the suspended catalyst is substantially back-mixed therein.
  • process parameters such as gas velocities, concentrations, and pulse duration may be optimized to ensure "breakthrough" ofthe oxygen gas or reactants at the reactor outlet does not occur, which could contaminate the product stream; that is, such parameters are controlled to ensure the reactant gases and the oxygen gas are consumed in the bed.
  • the above-referenced reactors are preferred, at least in part, because they essentially enable the cataloxidants to constantly remain in a partially reduced state, which is favorable for consistently obtaining high selectivity in the reaction.
  • such continuous processes are believed to enable higher space time yields ("STY") to be obtained, as well as enable the use of lower operational pressures.
  • STY space time yields
  • such processes allow for other cataloxidant compositions to be employed such as, for example, a combination of nickle/nickel oxide only (i.e., a noble metal is not required).
  • the carrier gas is introduced into the gas/solid contact zone at a rate sufficient to establish fluidization ofthe particulate catalyst without substantial entrainment ofthe catalyst out ofthe contact zone.
  • the catalyst bed is highly back-mixed due to rapid recirculation of catalyst particles within the bed under the influence ofthe turbulent substantially plug flow ofthe gas.
  • the difference between oxygen flow rate and total flow rate determines the rate at which carrier gas should be introduced into the lower end ofthe gas/solid contact zone.
  • Carrier gas exiting the upper end ofthe gas/liquid contact zone may be recirculated to the inlet of the contact zone after separation of reaction product, reaction by-products and unreacted benzene and ammonia.
  • water, aniline, benzene and organic by-products may be condensed and separated from the gas phase. Two condensate phases are obtained comprising benzene and aniline in the organic phase, and ammonium hydroxide and aniline in the aqueous phase.
  • Ammonia remaining in the gas phase may be separated from the carrier gas by further condensation under pressure and refrigeration, or by passing the gas phase through an ammonia scrubber. Water, or a slightly acidic aqueous medium may serve as the scrubbing medium.
  • the carrier gas exiting the ammoma scrubber may then be recirculated to the inlet ofthe oxidation zone, together with any makeup carrier gas that may be required. Any excess of carrier gas may be vented from the system, thereby purging any non-condensable impurities not removed in the ammonia scrubber.
  • the carrier gas is preferably an inert gas, such as nitrogen. Where air is used as the source of oxygen, carrier gas for steady state operation may be entirely supplied by the nitrogen in the air. Nitrogen from another source may be required for startup.
  • Ammonia-rich liquor exiting the scrubber may be transferred to an ammonia stripper in which ammonia is removed from the rich liquor for recycle to the amination zone ofthe fluid bed reactor.
  • an ammonia stripper in which ammonia is removed from the rich liquor for recycle to the amination zone ofthe fluid bed reactor.
  • steam or vacuum stripping may be employed.
  • a side stream of carrier gas may be used to assist in stripping ammonia from the aqueous phase.
  • the organic phase ofthe condensate is distilled for recovery of benzene which is recycled, yielding a bottom stream comprising product aniline. Additional aniline may be recovered by stripping the aqueous condensate. Stripping the aqueous condensate also recovers ammoma which can be recycled to the amination zone together with recovered benzene and ammoma stripped from the scrubber liquor.
  • the catalyst can be supplied or loaded to a reaction zone of a reactor in a reaction- ready, pretreated form (e.g, after preparation and any necessary pre-reaction treatments external to the reaction cavity), or alternatively, the catalyst can be supplied to the reaction zone in a precursor form, with final catalyst preparation steps being carried out in situ in the reaction zone.
  • catalyst pretreatment steps can include calcination to form a noble metal oxide, and/or reduction of a noble metal oxide (e.g., in the presence of hydrogen gas) to the noble metal, as discussed above.
  • catalyst pretreatment steps can include oxidative calcination to form the metal oxide in a higher oxidation state.
  • the catalyst is typically, but not necessarily, loaded in the reactor prior to supplying reactants thereto.
  • the catalyst or catalyst precursor is typically a solid material while the reaction is being effected.
  • the overall amount ofthe cataloxidant loaded into the reaction zone of the reactor to effect the amination reaction of interest can vary with the particular reaction being effected, with the type of reactor, the reaction conditions, the form ofthe catalyst, the scale ofthe process (including, for example, the amounts of reactants supplied to the reaction zone ofthe reactor), and the catalyst loading scheme (e.g., one-time loading, versus intermittent reloading, etc.).
  • the catalyst loading should be sufficient to provide at least a catalytically effective amount of a noble metal.
  • the catalytically effective amount of noble metal can vary with the particular reaction, the reaction conditions, the regeneration requirements and the form ofthe catalyst (e.g., supported or unsupported, porosity, surface area, preparation methods, etc.).
  • the catalytically effective amount can be determined by optimization approaches known in the art. For example, a series of aniline synthesis reactions with varying amounts of cataloxidants (and varying amounts ofthe noble metal component thereof) can be conducted under lab or pilot scale reaction conditions and evaluated with respect to catalyst performance. In some cases, lower noble metal loadings can result in an increased likelihood of noble metal fouling, whereas higher noble metal loadings can result in an increased tendency for ammonia decomposition.
  • the catalyst loading should, moreover, be generally sufficient to provide at least a stoichiometric amount of a reducible metal oxide, relative to the amount of hydrogen produced.
  • the stoichiometric amount ofthe reducible metal oxide will vary with the particular reaction, the amount of aromatic hydrocarbon or heterocyclic analog being converted, and with the particular reducible metal oxide.
  • one mole of hydrogen is produced for each mole of benzene converted, and can react with the NiO on a one to one mole basis to form H 2 O, thereby requiring NiO in a molar amount equal to the molar amount of benzene converted.
  • An amount ofthe reducible metal oxide in excess ofthe stoichiometric amount is preferred, including for example, a 50 % molar excess, a 100% molar excess or more, relative to the stoichiometric required amount.
  • the molar excess can be, in some cases, range from about a 5 times excess to about a 20 times excess, or from about a 5 times excess to about a 100 times excess, or from about a 5 times excess to about a 1000 times excess, in each case relative to the stoichiometric required amount.
  • a useful parameter for characterizing the catalyst loading for a batch reaction is the weight ratio ofthe total amount of all reactants to the total amount of catalyst, referred to herein as the "R/C ratio.”
  • the R/C ratio preferably ranges, in general for preferred applications in which benzene is converted to aniline, from about 0.1:1 to about 50:1, more preferably from about 0.1:1 to about 30:1, even more preferably from about 0.1:1 to about 20:1 and still more preferably from about 0.5:1 to about 10:1, in each case by weight.
  • Particularly preferred R/C ratios for particular catalysts and particular reactions are discussed below.
  • the catalyst loading can be characterized in terms of a liquid hourly space velocity (LHSV).
  • the LHSV preferably ranges from about 0.01 per hour to about 10 per hour, while in some instances it may range from about 0.05 per hour to about 5 per hour, or from about 0.1 per hour to about 3 per hour.
  • productivity for batch and continuous processes will vary, for example, ranging from about 10 to about 1000 g aniline/hour/kg catalyst, depending upon the particular mode by with the process is carried out. More specifically, productivity for a batch process typically ranges from about 10 to less than about 100 g aniline/hour/kg catalyst (i.e., about 25, 50, 75, etc.
  • productivity for a continuous process typically ranges from more than about 100 g aniline/hour/kg catalyst up to about 1000 g aniline/hour/kg catalyst (i.e, about 250, 500, 750, etc. g aniline/hour/kg catalyst).
  • the catalyst is typically exposed to (e.g., flushed with) an inert gas prior to admitting the reactants to the reaction zone ofthe reactor.
  • Nitrogen is a suitable inert gas. Such flushing reduces the amount of gaseous oxygen in the reactor, thereby limiting the potential reaction between oxygen and ammonia (or other aminating agent).
  • the aromatic reactant and the aminating agent can, independently, be supplied to the reaction zone ofthe reactor as a gas or as a liquid. Preferences as to the phase ofthe aromatic reactant and/or the aminating agent will generally depend on the particular amination reaction being effected and/or on the particular reactor configuration. In preferred applications, such as the preparation of aniline from benzene, benzene and ammonia are preferably both present in the reaction zone as gaseous reactants.
  • typically benzene is supplied to the reaction vessel as a liquid, which then evaporates during heat-up to form a gas, while ammonia is present in the reaction vessel in the supercritical phase (i.e., present at a temperature and pressure which are both in excess ofthe respective critical temperature and pressure for ammoma).
  • the reactants can be supplied to the reaction zone together (e.g., as a pre-mixed reactant stream), or separately and, if separately, either concurrently or sequentially.
  • the aromatic reactants and/or the aminating agent are preferably supplied to the reaction zone as a higher-grade, substantially pure feedstocks, but may alternatively, for certain reactions and/or for certain cataloxidants, be supplied as major components of lower-grade feedstocks.
  • the relative amount of aromatic reactant and aminating agent supplied to the reaction zone will vary, depending on the particular amination reaction and the reaction conditions. In general, at least stoichiometric amounts of these reactants are provided to the reaction zone. Typically, however, an amount in excess ofthe stoichiometric amount of one ofthe reactants relative to the other can be supplied to provide for more favorable kinetics, higher aromatic-reactant conversion, and/or to provide for improved product selectivity.
  • the molar ratio of ammonia to benzene can preferably range from about 0.1 :1 to about 100:1, more preferably from about 0.5:1 to about 100:1, and even more preferably from about 1:1 to about 100:1.
  • the NH 3 :C 6 H 6 ratio can range from about 1:1 to about 50:1, from about 1:1 to about 30:1, from about 1:1 to about 10:1, or from about 1:2 to about 1:8.
  • co-reactants co-catalysts or additional agents (e.g., scavenging agents) may also be supplied to the reaction zone ofthe reactor, with particulars thereof depending on the amination reaction of interest.
  • additional agents e.g., scavenging agents
  • gaseous oxygen or an oxygen-containing gas e.g, air
  • the relative amount of gaseous oxygen supplied to the reaction zone is not generally critical, and can vary depending on the relative amounts of noble metal components and reducible metal oxide components, and on the amount of catalyst loaded.
  • the molar ratio of gaseous oxygen to benzene can, for example, range from about 0.05:1 to about 1:1 and preferably from about 0.1:1 to about 1:1. It may also be advantageous, in some embodiments, to effect the benzene amination reaction without supplying oxygen or an oxygen-containing gas to the reaction zone; that is, in some embodiments the reaction may be carried out in the essential absence of an oxygen co-reactant and/or oxygen co-feed.
  • reaction conditions are controlled to effect the desired amination reaction, and preferably, in a manner that optimizes aromatic reactant conversion, arylamine or heteroarylamine selectivity, and/or regenerabihty.
  • benzene is preferably aminated at a temperature, pressure and/or residence time controlled to, and with a cataloxidant selected to effect a benzene conversion of at least about 5%, 7%, 10% or more, with at least about 90%, 95% or more selectivity for aniline based on weight and relative to benzene.
  • reaction temperature may be any temperature within the range bound on the lower end by the temperature needed to dehydrogenate benzene and on the higher end by the temperature at which coking begins; that is, generally the reaction temperature may be any temperature high enough to activate benzene for dehydrogenation but low enough to avoid coking.
  • reaction temperatures for benzene amination preferably range from about 200 ° C to about 600 °C, or from about 200 °C to about 500 °C and, in some embodiments, can range from about 250 °C to about 450 °C, or from about 300 ° C to about 400 ° C, the higher temperatures within each range being more preferred in order to increase the % conversion and the space time yield ("STY").
  • Reaction pressures for the amination reaction generally, and benzene amination in particular preferably range from about 1 bar to about 900 bar, more preferably from about 1 bar to about 500 bar, and even more preferably from about 1 bar to about 300 bar.
  • the pressure in the reaction zone can range about 50 bar to about 300 bar, from about 100 bar to about 300 bar, or from about 150 bar to about 300 bar.
  • the particular reaction pressure employed is at least in part a function ofthe type of reactor in which the reaction is carried out. For example, for some applications utilizing a batch-type reactor, the pressure is typically greater about 100 bar, while for some application in which a continuous flow-type reactor is utilized, the pressure is typically less than about 100 bar (i.e., ranging from about 1 to about 50 bar).
  • the residence time is not generally critical, and can be optimized for a particular reaction system (i.e., for a particular cataloxidant, R/C ratio, NH 3 :C 6 H 6 ratio, temperature, pressure, etc.) with respect to conversion, selectivity and/or regenerabihty according to approaches known in the art.
  • Typical residence times for benzene amination in batch reactors can range from about 15 minutes to about 8 hours, and preferably from about 30 minutes to about 4 hours, depending on the temperature. In general, shorter residence times can be achieved with higher reaction temperatures.
  • a residence time of about 4 hours at about 300 ° C, or of about 15 minutes at about 400 ° C, or of about 1 hour at 350 °C can be satisfactory.
  • the residence times can range from about 0.25 seconds to about 20 minutes, and preferably from about 0.5 seconds to about 10 minutes. The aforementioned ranges are generally preferred, but should be considered non-limiting. Shorter contact times can be achieved, for example, by changing the reaction conditions, and particularly, the reaction temperature.
  • the difference in reaction times between a batch reactor and a continuous flow reactor is at least in part due to the thermodynamic equilibrium ofthe reaction, or lack thereof. More specifically, in a batch reactor, the kinetics ofthe metal oxide reduction (e.g., NiO to Ni) are slow and conversion is low due to the thermodynamic equilibrium that is typically reached in this reaction. However, in a continuous flow reactor, the instantaneous ratio of catalyst to substrate is typically far greater than in batch, especially where the reaction is essentially gas phase, and therefore an equilibrium for this reaction is essentially never reached, so the overall amination reaction proceeds much faster and higher conversions are obtained.
  • the metal oxide reduction e.g., NiO to Ni
  • the most preferred particular temperatures and the most preferred pressures can vary outside ofthe above-described generally preferred ranges and/or within the generally preferred ranges, depending on the particular catalyst being employed for the benzene amination reaction, as exemplified below.
  • varying and sometimes competing thermodynamics and/or kinetics concerns are implicated by varying the reaction temperature and pressure, as well as by the presence or absence of gaseous oxygen as a co-reactant. See Becker et al., Amination of Benzene in the Presence of Ammonia Using a Group VIII Metal Supported on a Carrier as a Catalyst. Cat. Let. 54, 124-128 (1998).
  • higher temperatures are desirable with respect to improved kinetics and improved thermodynamics for benzene conversion to aniline.
  • higher temperatures also can implicate thermodynamic and kinetic concerns for side reactions and/or other reactions, such as decomposition of ammonia.
  • the reaction is preferably effected with appropriately selected heat transfer equipment and temperature-control systems in place.
  • the reaction may be run, for example, isothermally or adiabatically, depending on the particular amination reaction, among other factors.
  • the reaction is preferably effected isothermally with appropriate heat-exchange equipment in thermal communication with the reaction zone ofthe reactor.
  • the product arylamine or heteroaiylamine e.g., aniline
  • aniline can be isolated from other products and/or from excess reactants following the amination reaction.
  • the reactor can be cooled to room temperature or lower, excess aminating agent (e.g., ammonia) can be vented, and a liquid phase can be separated from the cataloxidant. The product can then be isolated from the liquid phase.
  • aminating agent e.g., ammonia
  • the reaction is effected in a continuous flow reactor (e.g., a fixed-bed flow reactor)
  • the gaseous product stream can be separated into its various product / excess reactant components, or alternatively, can be condensed, and the product can be isolated therefrom.
  • product isolation may be achieved using a simple series of distillation columns.
  • the gaseous product mixture upon exiting the continuous flow reactor, can be passed through an initial condenser, where unreacted benzene, the product aniline, as well as any reaction byproducts (such as water, toluene, diphenyl), are condensed and collected.
  • Non-condensibles present in the gaseous product stream such as excess ammoma and, if present, unreacted hydrogen, can either be vented (for example to a flare) or recycled back to the reactor.
  • the organic phase ofthe resulting condensed mixture may then proceed through a series of distillation columns, where various reactants, products and byproducts can be isolated and collected.
  • a first column for example, benzene is distilled, the distilled benzene then being recycled directly to the reactor or collected for later use.
  • the remaining mixture i.e., the first "pot liquor”
  • a second distillation column where typically a small amount of toluene is distilled and collected.
  • the remaining mixture i.e., the second "pot liquor” then proceeds to a third column where the product aniline is isolated from any diphenyl present and collected. Due to the highly selective nature ofthe present process, relatively small columns can be employed for the latter two separations because little, if any, ofthe byproducts toluene and diphenyl are formed.
  • the conversion of benzene is preferably at least about 5% at the temperature and pressure ranges described above, and more preferably at least about 6% at such ranges. Even higher conversions are desirable and may be achieved through optimization protocols known in the art and/or later developed. Hence, the conversion of benzene can be at least about 7%, at least about 8%, 10% or higher. Still higher conversions can be achieved in continuous-flow systems.
  • the "conversion" of benzene or other aromatic reactant can be calculated according to the following equation:
  • the amount of benzene, as used in the immediately-preceding equation can be expressed on a molar or a weight basis, and used consistently in the equation.
  • the selectivity ofthe catalyst for aniline for the benzene amination reaction is preferably at least about 90%, preferably at least about 93%, more preferably at least about 95%), even more preferably at least about 97% and most preferably about 98%, in each case, based on weight and relative to benzene.
  • the selectivity for aniline, based on weight and relative to benzene can be calculated according to the following equation:
  • the conversion and selectivity values refer to the overall (i.e., effectively time and location integrated) conversion and selectivity values associated with the reaction. Values of differential conversions and/or selectivity (e.g., associated with local regions ofthe reaction zone and/or with shorter time periods) may vary from the overall values. Moreover, while the values of conversions and selectivity as referred to herein are intended to be based on total and complete mass-balance calculations, a rough approximation thereof (e.
  • the overall aniline yield for the reaction is preferably at least about 4.5%, more preferably at least about 4.75%, and even more preferably at least about 5%, based on weight and relative to benzene. Higher yields are desirable and expected based on optimization ofthe cataloxidants and/or the reaction systems or conditions described herein.
  • the aromatic reactant conversion is less than 100%, and/or where a stoichiometric excess ofthe aminating agent is employed
  • the cataloxidant involved in the amination reaction can be wholly or partially regenerated.
  • the cataloxidant is contacted with an aromatic reactant such as benzene and/or with an aminating agent such as ammonia in a reaction zone of a reactor to form aniline for at least some initial period of time, with an initial benzene conversion being achieved and with a particular selectivity for aniline during this period of time.
  • the catalyst performance e.g., conversion and/or selectivity
  • the relative amount ofthe reducible metal oxide that is in the reduced form (having a lower oxidation state) after the initial period is not critical.
  • catalyst efficiencies of about 5% to about 50 %, or from about 10% to about 30% are acceptable, with such "catalyst efficiency" referring to the relative amount ofthe reducible metal oxide component in the relatively reduced (i.e., relatively lower oxidation) state, based on weight, relative to the weight ofthe metal oxide component.
  • At least a portion ofthe catalyst contacted during the initial period can be regenerated, either within the reaction zone ofthe reactor or external thereto, by exposing the catalyst to oxidizing conditions, whereby the reduced form ofthe reducible metal oxide is reoxidized.
  • Suitable oxidizing conditions typically include, for example, exposing the catalyst to oxygen gas or to an oxygen-containing gas (e.g., air) at a temperature ranging from about 200 °C to about 800 °C, preferably from about 400 "C to about 600 °C, and most preferably at about 475 "C for a period of time ranging from about 10 minutes to about 10 hours and preferably from about 30 minutes to about 5 hours.
  • the cataloxidant can be flushed, for example with inert gas, prior to the oxidative regeneration (e.g., to remove residual organics and/or ammoma before feeding oxygen and/or for heating and/or cooling purposes).
  • the catalyst is, in preferred embodiments, regenerated without exposing the catalyst to reducing conditions. To the extent any noble-metal oxides are formed during the regeneration-oxidation step, such noble-metal oxides will be selectively reduced in situ at the start ofthe next amination reaction in the cycle.
  • all ofthe catalyst in the reaction zone can be regenerated at the same time without removing the catalyst from the reaction zone ofthe reactor by changing the conditions in the reactor from the (initial) reaction conditions to the regeneration (oxidizing) conditions.
  • a portion ofthe catalyst can be continuously or intermittently withdrawn from the reaction zone, regenerated external thereto, and then reloaded into the reaction zone, without interrupting the continuous reaction occurring in the reaction zone.
  • regeneration ofthe catalyst can be effected, for example, as follows.
  • benzene (Bz) and the aminating agent e.g., NH 3 as shown in Figures 2A through 2C
  • NM noble metal
  • MO reducible metal oxide
  • AN aniline
  • t 0, most, if not all, of reducible metal oxide component ofthe catalyst is present in the oxidized state (MO) (Fig. 2A).
  • reducible metal oxide(s) ofthe cataloxidant oxidize hydrogen gas produced in the aniline reaction, and the metal oxides are themselves reduced to the reduced state ofthe metal (M) - and are therefore present as reduced metal oxides.
  • t ⁇
  • some or all ofthe reducible metal oxide (MO) component is in the reduced state (M) (Fig. 2C).
  • the extent of metal-oxide reduction may be partial or complete, depending on the concentration of such oxides in the cataloxidant composition, the particular cataloxidant employed, and the duration ofthe reaction.
  • An initial benzene conversion is achieved during the initial reaction period, preferably at least about 5% conversion with at least 90% selectivity for aniline based on weight and relative to benzene.
  • the aniline selectivity is preferably even higher, as described above.
  • at least a portion of the catalyst used to effect the reaction during the initial period is regenerated by exposing the catalyst to oxidizing conditions, as described, and preferably in oxygen gas or air at temperatures ranging from about 400 °C to about 500 °C, whereby the reduced metal oxides are reoxidized to the corresponding reducible metal oxide form.
  • the catalyst can be regenerated without exposing the catalyst to reducing conditions (c.f, Du Pont's Ni / NiO catalyst, which requires both reduction and oxidation steps for regeneration).
  • the regeneration is effected to the entire catalyst bed at once, with the catalyst remaining in the reaction zone ofthe reactor as described above for the general case.
  • the cycle ofthe amination reaction followed by regeneration (e.g., Fig. 2A through Fig. 2D) is then reiteratively effected at least four times for at least a portion ofthe catalyst to form an at least five-time- regenerated catalyst (a "5X-regenerated catalyst").
  • such reiterative cycle is repeated at least nine times to form an at least ten-time-regenerated catalyst (a "lOX-regenerated catalyst").
  • a "lOX-regenerated catalyst” the 5X-regenerated catalyst, and preferably the lOX-regenerated catalyst retains commercially attractive performance criteria.
  • achievable benzene conversion is typically at least about 50% ofthe initial benzene conversion value, with conversions of at least about 75%, 85%), 90%, 95% and even about 100% ofthe initial conversion value being achievable in some instances, with at least about 90% selectivity for aniline (based on weight and relative to benzene) also being achieved. While cataloxidant regenerabihty has been described herein with reference to
  • FIGS. 2A through 2D in connection with a continuous-flow, fixed-bed, tubular plug-flow reactor, such description should be considered illustrative and non-limiting.
  • Other reaction systems including back-mixed systems such as fluidized bed and/or pressure- vessel batch reactors, will be more spatially homogeneous with respect to catalyst reduction and/or reoxidation.
  • preferred embodiments ofthe present invention are directed to the conversion of benzene to aniline using cataloxidants having noble metal components comprising, independently, Pd, Rh, Ru or Ir, and having a reducible metal oxide component comprising nickel oxide or, alternatively, cobalt oxide.
  • Manganese oxide is, in some cases, included in the catalyst composition as an additional reducible metal oxide or as a dopant metal oxide.
  • the cataloxidant composition comprises a noble metal component consisting essentially of Rh or, alternatively, consisting essentially of Ir.
  • the cataloxidant composition comprises a noble metal component consisting essentially of Pd, or alternatively, consisting essentially of Ru.
  • the noble metal component can comprise from about 0.05 % to about 5% by weight relative to total weight ofthe catalyst.
  • the reducible metal oxide component ofthe cataloxidant comprises or, in some cases, consists essentially of, nickel oxide or cobalt oxide, with the amount of metal oxide ranging from about 5% to about 30% by weight relative to the total weight ofthe catalyst.
  • Manganese oxide can also be included in some ofthe aforementioned cataloxidant compositions, either as an additional reducible metal oxide or as a second dopant in an amount ranging from about 0.5 % to about 20% by weight relative to total weight ofthe catalyst.
  • the cataloxidant compositions can further comprise a support in each ofthe aforementioned cases.
  • the support is preferably zirconium dioxide or titanium dioxide, and preferably has a surface area of at least about 20 m 2 /g or higher, with a surface area of 50 m 2 /g being suitable in many cases, and a pore volume of at least about 0.2 cc/g, with 0.25 cc/g, 0.3 cc/g and 0.35 cc/g being suitable in many cases.
  • TiO 2 is the support, it is also preferred that it be modified by impregnation with, for example, potassium, typically about 0.5% by weight.
  • Preferred cataloxidant compositions are further discussed below individually for each preferred noble metal.
  • the noble metal component comprises about 0.5% to about 5% by weight relative to the total weight ofthe cataloxidant.
  • the reducible metal oxide component comprises, or in some cases consists essentially of, nickle oxide or cobalt oxide, with the amount ofthe metal oxide ranging from about 30% to about 90%, and preferably from about 40% to about 80%, by weight relative to the total weight ofthe catalyst.
  • the cataloxidant in such instances additionally comprises a binder and, optionally, a dopant (as previously described). Catalyst compositions comprising the preferred components (or appropriate precursors thereof) are loaded into a batch or continuous reactor.
  • the catalyst loading for a batch reactor characterized with respect to the weight ratio of reactants to catalyst (R/C ratio) supplied to the reaction zone, ranges from about 0.1:1 to about 20:1, and in some cases from about 0.5:1 to about 10:1.
  • cataloxidant precursors can be oxidized with oxygen or an oxygen-containing gas, as described.
  • the catalyst can also be flushed with an inert gas such as nitrogen.
  • Benzene and ammonia are then supplied as gasses to the reaction zone, with the molar ratio of ammoma to benzene ranging from about 0.5: 1 to about 100: 1. Any noble metal oxides are selectively reduced with ammonia during heat up ofthe reaction system.
  • Benzene and ammonia are reacted therein in the presence ofthe cataloxidants and at a temperature ranging from about 200 "C to about 500 °C, and at a pressure ranging from about 1 bar to about 500 bar during the reaction.
  • the residence time is preferably about 1 hour for batch reactions, and preferably about lminute for continuous-flow reactions. Deviations and specific preferences, if any and where applicable, are discussed below in connection with the individual noble metal.
  • Preferred rhodium-based supported cataloxidants ofthe invention for batch operation comprise, or alternatively, consist essentially of, Rh in an amount ranging from about 0.05 % to about 2% by weight relative to total weight ofthe catalyst, nickel oxide in an amount ranging from about 10% to about 20% by weight relative to total weight ofthe catalyst, and manganese oxide in an amount ranging from about 0.5% to about 2% by weight relative to the total weight ofthe catalyst.
  • nickel oxide and/or manganese oxide may be replaced with, for example, cobalt oxide; that is, the cataloxidant comprises or consists essentially of Rh (0.05% to about 2% by weight) and cobalt oxide (in an amount ranging from about 10% to about 20% by weight).
  • Particularly preferred rhodium-based supported cataloxidants comprise, or alternatively, consist essentially of: (i) about 0.5 %, 0.75% and 1.25% Rh by weight relative to total weight ofthe catalyst, about 15% nickel oxide by weight relative to total weight ofthe catalyst, about 1.5 % manganese oxide by weight relative to total weight of the catalyst, and a zirconium oxide or titanium oxide support; or, (ii) about 0.5 % Rh by weight, about 15% cobalt oxide by weight, and a zirconium oxide or titanium oxide support (preferably impregnated with potassium). (See, e.g., Example 1).
  • Aniline is prepared in a batch reactor with the preferred rhodium-based cataloxidant compositions by reacting benzene and ammonia with a R/C ratio of about 1:1, a NH 3 :C 6 H 6 ratio of about 3:1 or about 6:1, a temperature ranging from about 300 °C to about 360 °C , a pressure ranging from about 200 bar to about 350 bar, and a residence (reaction) time of about 1 hour.
  • a benzene conversion of about 5%, about 6%, about 10% or more is achieved, with greater than about 95% (i.e., about 98%) selectivity for aniline based on weight and relative to benzene.
  • the rhodium-based cataloxidant can be oxidatively regenerated as described, and the benzene amination can be effected again with favorable performance characteristics (e.g., benzene conversion of about 5%, 10% or more and with about 98% selectivity for aniline, based on weight and relative to benzene after 5 reaction / regeneration cycles).
  • favorable performance characteristics e.g., benzene conversion of about 5%, 10% or more and with about 98% selectivity for aniline, based on weight and relative to benzene after 5 reaction / regeneration cycles.
  • Rhodium-based cataloxidant reactions are particularly preferred at temperatures ranging from about 200 °C up to about 370 °C, and most preferably at temperatures ranging from about 250 °C to about 350 ° C. Above about 350 °C, ammonia decomposition becomes a more substantial concern with the rhodium-based cataloxidant. As noted below, however, the ammonia decomposition at such higher temperatures was mitigated with iridium-based cataloxidants. Based on preliminary scale-up studies, it appears that the absolute amount of rhodium-based cataloxidant can be reduced for larger- scale reactions relative to the loadings for smaller-scale reactions.
  • the rhodium-based cataloxidants appear to be particularly promising for commercial amination reactions.
  • Preferred iridium-based supported cataloxidants ofthe invention for batch operation comprise, or alternatively, consist essentially of Ir in an amount ranging from about 0.05 % to about 2% by weight relative to total weight ofthe catalyst, nickel oxide in an amount ranging from about 10% to about 20% by weight relative to total weight ofthe catalyst, and manganese oxide in an amount ranging from about 0.5% to about 2% by weight relative to the total weight ofthe catalyst.
  • Particularly preferred iridium-based cataloxidants comprise, or alternatively, consist essentially of about 0.5 % to about 1.25% Ir by weight relative to total weight of the catalyst, about 15% nickel oxide by weight relative to total weight ofthe catalyst, about 2% manganese oxide by weight relative to total weight ofthe catalyst, and a zirconium oxide support or a titanium oxide support (preferably impregnated with potassium). (See, e.g., Example 2).
  • Aniline is prepared with the preferred iridium-based cataloxidant compositions by reacting benzene and ammonia with a R/C ratio of about 1:1, a NH 3 :C 6 H 6 ratio of about 3:1, a temperature ranging from about 300 °C to about 500 * C , a pressure ranging from about 200 bar to about 350 bar, and a residence (reaction) time of about 1 hour.
  • a benzene conversion is about 5% is achieved with about 98% selectivity for aniline base on weight and relative to benzene.
  • the iridium-based cataloxidant can be oxidatively regenerated as described, and the benzene amination can be effected again with favorable performance characteristics (e.g., benzene conversion of about 5% with about 98% selectivity for aniline based on weight and relative to benzene after 5 reaction / regeneration cycles).
  • Iridium-based cataloxidant reactions are particularly preferred at relatively higher temperatures, including temperatures ranging from about 325 °C up to about 400 °C, and especially at temperatures ranging from about 340 °C to about 400 °C. Ammoma decomposition at such higher temperatures is mitigated with the iridium-based cataloxidants relative to the rhodium-based cataloxidants.
  • Preferred palladium-based supported cataloxidants ofthe invention for batch operation comprise, or alternatively, consist essentially of, Pd in an amount ranging from about 0.5 % to about 4% by weight relative to total weight ofthe catalyst, nickel oxide in an amount ranging from about 20% to about 30% by weight relative to total weight ofthe catalyst, and manganese oxide in an amount ranging from about 10% to about 20% by weight relative to total weight ofthe catalyst.
  • Particularly preferred palladium-based cataloxidants comprise, or alternatively, consist essentially of, Pd in an amount ranging from about 1% to about 3% by weight relative to total weight ofthe catalyst, nickel oxide in an amount ranging from about 25 % to about 30%) weight relative to total weight ofthe catalyst, manganese oxide in an amount ranging from about 12% to about 18% by weight relative to total weight ofthe catalyst, and a zirconium oxide or titanium oxide support. (Example 3).
  • Aniline is prepared with the preferred palladium-based cataloxidant compositions by reacting benzene and ammonia substantially as described for the generally preferred case above. Benzene conversion is about 5.6 % to about 6.3 %, with about 94% selectivity for aniline based on weight and relative to benzene. The other major reaction product was diphenylamine (about 6% based on weight and relative to benzene). Palladium-based cataloxidant reactions are particularly preferred at relatively moderate temperatures, including temperatures ranging from about 300 °C up to about 350 °C, and especially at temperatures ranging from about 310 °C to about 330 ° C.
  • Preferred ruthenium-based supported cataloxidants ofthe invention for batch operation comprise, or alternatively, consist essentially of Ru in an amount ranging from about 0.05 % to about 5% by weight relative to total weight ofthe catalyst, and nickel oxide in an amount ranging from about 20% to about 30% by weight relative to total weight ofthe catalyst.
  • Particularly preferred ruthenium-based cataloxidants ofthe invention comprise, or alternatively, consist essentially of Ru in an amount ranging from about 0.5 % to about 4% by weight relative to total weight ofthe catalyst, from about 25 % to about 30% nickel oxide by weight relative to total weight ofthe catalyst, optionally from about 5% to about 10% manganese oxide, and a zirconium oxide or titanium oxide support. (Example 4).
  • Aniline is prepared with the preferred ruthenium-based cataloxidant compositions by reacting benzene and ammonia substantially as described for the generally preferred case above. Benzene conversion is about 3% with about 98% selectivity for aniline. Ruthenium-based cataloxidant reactions are particularly preferred at relatively moderate temperatures, including temperatures ranging from about 300 °C up to about 350 °C, and especially at temperatures ranging from about 310 ° C to about 330 ° C.
  • Preferred platinum-based supported cataloxidants ofthe invention for batch operation comprise, or alternatively, consist essentially of Pt in an amount ranging from about 0.05 % to about 5% by weight relative to total weight ofthe catalyst, and nickel oxide in an amount ranging from about 20% to about 30% by weight relative to total weight ofthe catalyst.
  • platinum-based cataloxidants ofthe invention comprise, or alternatively, consist essentially of Pt in an amount ranging from about 0.5 % to about 2% by weight relative to total weight ofthe catalyst, from about 25 % to about 30% nickel oxide by weight relative to total weight ofthe catalyst, optionally from about 15% to about
  • Example 5 Aniline is prepared with the preferred platinum-based cataloxidant compositions by reacting benzene and ammonia substantially as described for the generally preferred case above. A benzene conversion is about 3% is achieved with about 98% selectivity for aniline based on weight and relative to benzene.
  • the following examples illustrate the principles and advantages ofthe invention.
  • Example 1 Preparation of Aniline with Rhodium-Based Cataloxidants This example demonstrates the synthesis of a Rh/Ni-oxide/Mn-oxide/ZrO 2 catalyst
  • Example 1 A a Rh/Ni-oxide/ZrO 2 catalyst (Example IB), a Rh/Ni-oxide/Mn-oxide/ KTiO 2 catalyst (Example IC), and a Rh/Co-oxide/ZrO 2 catalyst (Example ID), as well as the use thereof for the direct amination of benzene to aniline. Effective regeneration of some of these rhodium-based catalyst is demonstrated below (See Example 6A through 6C).
  • Example I A Rh/Ni-oxide/Mn-oxide/Zr0 2
  • a Rh/Ni-oxide/Mn-oxide/ZrO 2 catalyst was prepared as follows.
  • a zirconia support (1/8 inch pellets, surface area 54.1 m 2 /g, pore volume 0.3 cc/g, Norton Chemical Process Products Corp., Product No. XT 16075) was pre-calcined at 110 "C for lhour.
  • the zirconia support (30 g) was impregnated with an aqueous precursor solution comprising nickel nitrate, manganese nitrate and rhodium nitrate.
  • the precursor solution was formed by combining Ni(NO 3 ) 2 .6H 2 O (22.3 g), Mn(NO 3 ) 2 .x H 2 O (1.466 g), rhodium (III) nitrate solution (1.064 ml, 10% wt/wt Rh), and distilled water (1 ml), and slowly warming to facilitate dissolution.
  • the pellets were impregnated with the solution in two steps with an intermediate drying step (100 * C, 2-3 h), resulting in complete absorption ofthe precursor solution by the pellets.
  • the impregnated pellets were then dried at 110 °C for 6 hours.
  • the temperature ofthe oven was then raised to 450 °C in an interval of 4 hours, and the impregnated support material was calcined at this temperature for 4 hours.
  • the catalyst yield was 34.67 g.
  • Direct amination of benzene in the presence ofthe Rh/Ni-oxide/Mn-oxide/ZrO 2 catalyst was then effected in a batch reactor.
  • the 34.67 g catalyst (see above) was loaded into a dried and cleaned Parr bomb cylinder (94 ml volume). Liquid benzene (19.9 ml) was added.
  • the Parr bomb was sealed with a head-piece equipped with a pressure indicator, safety valve and a manually operated valve for venting/loading with gases.
  • the Parr bomb was then cooled by thermally equilibrating with liquid nitrogen.
  • Ammonia gas (14.8 L) was condensed into the Parr bomb, with flow and total volume fed to the Parr bomb controlled by a mass-flow-controller (MFC).
  • MFC mass-flow-controller
  • the reactant to catalyst ratio (R/C ratio) was about 1, and the ammoma to benzene ratio was about 3:1.
  • the Parr bomb was mounted on a mechanical rocker. Electrical mantel-piece heaters (for the bottom, cylinder piece) and electrical ribbon-heaters (for the head piece) were connected. The device was thermally insulated with fiberglass mat.
  • the Parr bomb was heated to 300 °C, and benzene and ammonia were reacted over the catalyst at 300 °C and 300 bar for 4 hours.
  • the benzene conversion was determined to be 6.3% with about 100% aniline selectivity (based on weight and relative to benzene, as determined by calibrated GC analysis; 5.5% conversion prior to calibration) - i.e., no detectable amounts of byproducts were observed with GC.
  • Example IB Rh/Ni-oxide/Zr0 2
  • Ni(NO 3 ) 2 solution was prepared by dissolving Ni(NO 3 ) 2 .6H 2 O (97.3130g ) into water to make 500ml solution (hereinafter referred to as the "Ni(NO 3 ) 2 Solution A”).
  • Rh/Ni-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 /HOC 3 H 7 (70wt%, 8.300ml) was mixed with 5.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material. The Ni(NO 3 ) 2 Solution A (15.0 ml) was combined with the support material, and the mixture was stirred, and then dried at 110°C for 5 hours. Acetic acid (10 ml) and the Rh(III) Solution (1.800ml ) were then added. The sample was dried at 110 °C for 5 hours, and then calcined in air at 450°C for 4 hours.
  • Benzene was directly aminated with ammonia formed in situ from the aminating-agent precursors at 350 °C, at about 200 bar, for 4 hours. After reaction, the reactor was cooled to room temperature, further cooled in a dry ice bath, and then opened for venting. The reactor contents were separated from the catalyst and analyzed by gas chromatography (GC). A benzene conversion of 4.7 % was achieved with about 100% aniline selectivity based on weight and relative to benzene (as determined by GC).
  • GC gas chromatography
  • a Rh/Ni-oxide/Mn-oxide/KTiO 2 catalyst was prepared as follows.
  • a titanium dioxide support 150 g; Degussa, P 25 S, surface area 45 m 2 /g, pore volume 0.25cc/g
  • KNO 3 0.5% K solution
  • the impregnated carrier was dried at 110°C for 20 hours and then the oven temperature was increased to 550°C over an interval of 8 hours. The carrier was then calcined for 4 hours at this temperature.
  • a portion ofthe resulting KTiO 2 carrier (50 g) was then impregnated with a first aqueous precursor solution comprising nickel nitrate, manganese nitrate and rhodium nitrate as follows.
  • the first precursor solution was formed by combining Ni(NO 3 ) 2 *6H 2 O (37.16 g; 15% Ni), Mn(NO 3 ) 2 *xH 2 O (2.44 g), and a 10% (wt/wt) rhodium (III) nitrate solution (3.75 g; 1% Rh; Strem), the resulting solution being heated to about 70°C to about 80°C (with about 1 to 2 ml of H 2 O being added initially as heating began).
  • the solution was maintained at about 60 °C to about 70 °C (to prevent Ni(NO 3 ) 2 from precipitating over the carrier surface), while about 50 g ofthe KTiO 2 carrier was added. In this preparation, the carrier absorbed essentially all ofthe first precursor solution.
  • Two additional portions ofthe KTiO 2 carrier (50 g each) were impregnated in a similar manner with a second and third aqueous precursor solution, respectively, both of which also comprised nickel nitrate, manganese nitrate and rhodium nitrate. More specifically, these precursor solutions were formed as described above, with the exception that they contained 5.0 g and 6.25 g, respectively, ofthe 10% (wt/wt) rhodium (III) nitrate solution.
  • potassium-doped carriers were prepared, they were dried at about 110°C for approximately 20 hours. The oven temperature was then gradually increased to about 450°C over a 12 hour interval, at which temperature they were calcined at 450°C for 4 hours.
  • the resulting catalysts each comprised 15% Ni, 1.5% Mn, 0.5% K, based on the total weight ofthe catalyst. Additionally, these catalysts contained 0.75%, 1.0% and 1.25% Rh, respectively, again based on the total weight ofthe catalyst.
  • Rh/Co-oxide/Zr0 2 A Rh/Co-oxide/ZrO 2 catalyst was prepared as follows. Cobalt nitrate (13.4 g,
  • the impregnated pellets were dried for an additional 4 hours at 120° C followed by calcining at 380° C for 4 hours. After being cooled to about 25 °C, the impregnated pellets (comprising about 0.5% Rh and about 14% Co by weight relative to the total weight ofthe cataloxidant) were lightly crushed using a mortar and pestle to produce a fine white powder.
  • Example 2A This example demonstrates the synthesis of a Ir/Ni-oxide/Mn-oxide/ZrO 2 catalyst (Example 2A), a Ir/Ni-oxide/ZrO 2 catalyst (Example 2B) and a Ir/Ni-oxide/Mn-oxide/ KTiO 2 catalyst (Example 2C), as well as the use thereof for the direct amination of benzene to aniline.
  • Example 2 A Ir/Ni-oxide/Mn-oxide/Zr0 2
  • a Ir/Ni-oxide/Mn-oxide/ZrO 2 catalyst was prepared in duplicate as follows from the following stock solutions: 2M Ni(NO 3 ) 2 .6H2O; 1M Mn(NO 3 ) 2 .6H2O; Iridium(IIi) acetylacetonate (0.19 g in 12 ml of acetone).
  • a Ni-Mn solution was prepared by adding 4.09 ml ofthe 1M Mn(NO 3 ) 2 .6H 2 O solution to 19.15 ml ofthe 2M Ni(NO 3 ) 2 solution.
  • the pre-calcined ZrO 2 support was immersed in the Ni-Mn solution (5 ml) and was then dried at 110 °C.
  • the dried, Ni-Mn impregnated carrier was subsequently immersed in 4 ml ofthe above- described Ir solution, and then dried at 110 °C. Alternate immersion in the remaining amounts ofthe aforementioned Ni-Mn and Ir solutions, with intermittent drying, was continued until both solutions were consumed. Finally, both samples were calcined in air at 110°C for 2h and then additionally at 475°C for 4h.
  • a Ir/Ni-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 /HOC 3 H 7 (70wt%, 8.300ml) was mixed with 5.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material. The Ni(NO 3 ) 2 Solution A (15.0 ml) and the Ir(i ⁇ ) Solution (2.400 ml) were combined with the support material, and the mixture was stirred, dried at 110°C for 10 hours, and then calcined in air at 450°C for 4 hours.
  • Example 2C Ir/Ni-oxide/Mn-oxide/KTi0 2
  • a Ir/Ni-oxide/Mn-oxide/KTiO 2 catalyst was prepared as follows.
  • a titanium dioxide support 150 g; Degussa, P 25 S, surface area 45 m 2 /g, pore volume 0.25cc/g
  • KNO 3 0.5% K solution
  • the impregnated carrier was dried at 110°C for 20 hours and then the oven temperature was increased to 550°C over an interval of 8 hours. The carrier was then calcined for 4 hours at this temperature.
  • a portion ofthe resulting KTiO 2 carrier (10 g) was pre-calcined at 200 °C for about 2 hours in an air oven.
  • Ir-acac an iridium acetylacetonate solution
  • Ir-acac an iridium acetylacetonate solution
  • the carrier was dried at 110°C for 10 hours, and then the temperature was gradually increased to 450°C over a 15 hour interval, at which temperature the carrier was calcined for 4 hours.
  • the dried, impregnated carrier was then analyzed and found to comprise 2% Ir, 15% Ni, 1.5% Mn and 0.5% K, based on the total weight ofthe catalyst.
  • Example 3 Preparation of Aniline with Palladium-Based Cataloxidants This example demonstrates the synthesis of a number of Pd-based catalysts and the use thereof for the direct amination of benzene to aniline.
  • the investigated catalysts include, specifically, a Pd/Ni-oxide/Mn-oxide/ZrO 2 catalyst (Example 3 A), a Pd/Ni- oxide/Mn-oxide/La-oxide/ZrO 2 catalyst (Example 3B), a Pd/Ni-oxide/ZrO 2 catalyst (Example 3C), a Pd/Ni-oxide/La-oxide/ZrO 2 catalyst (Example 3D), a Pd/Ni-oxide catalyst (Example 3E), a Pd/Ni-oxide/Ce-oxide catalyst (Example 3F), a Pd/Ni-oxide/Pr- oxide catalyst (Example 3G), a Pd/Ni-oxide
  • a Ni(NO 3 ) 2 Solution A was prepared as described in Example IB.
  • a Mn(NO 3 ) 2 solution was prepared by dissolving Mn(NO 3 ) 2 .xH 2 O (Aldrich, catalog No.28864-0) (94.0866g) into distilled water to make 500ml solution (hereinafter referred to as the "Mn(NO 3 ) 2 Solution B").
  • a La(NO 3 ) 3 solution was prepared by dissolving La(NO 3 ) 3 .6H 2 O (13.2901 g) in distilled water to make a 50ml solution (hereinafter referred to as the "La(NO 3 ) 3 Solution”).
  • a Ce(NO 3 ) 3 solution was prepared by dissolving Ce(NO 3 ) 3 .6H 2 O (6.3081 g) in distilled water to make a 50ml solution (hereinafter referred to as the "Ce(NO 3 ) 3 Solution”).
  • a Pr(NO 3 ) 3 solution was prepared by dissolving Pr(NO 3 ) 3 .6H 2 O (6.3880 g) in distilled water to make a 50 ml solution (hereinafter referred to as the "Pr(NO 3 ) 3 Solution”).
  • a V 2 O 5 solution was prepared by mixing V 2 O 5 ( 10.0000 g) with oxalic acid dihydrate, adding 50 ml deionized water into the mixture, heating and stirring in water bath (about 80°C) until a clear solution was formed. The clear solution was transferred to a 100ml flask and, after cooling, deionized water was added to make alOOml solution (hereinafter referred to as the "V 2 O 5 Solution").
  • Example 3 A Pd/Ni-oxide/Mn-oxide/Zr0 2
  • a Pd/Ni-oxide/Mn-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 /HOC 3 H 7 (70wt%, 8.300ml, Aldrich Cat. No. 33,397-2) was mixed with 4.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material. The Ni(NO 3 ) 2 Solution A (15.0 ml) and the Mn(NO 3 ) 2 Solution B (7.200 ml) were combined with the support material, and the mixture was stirred and dried at 110 °C for 10 hours.
  • the Pd(II) Solution (12.00 ml) was added to the Ni- and Mn- impregnated support, and the support was then dried at 110°C for 5 hours, and then calcined in air at 480°C for 4 hours.
  • Example SB Pd/Ni-oxide/Mn-oxide/La-oxide/Zr0 2
  • a Pd/Ni-oxide/Mn-oxide/La-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 /HOC 3 H 7 (70wt%, 6.43 ml, Aldrich Cat. No. 33,397-2) was mixed with 4.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material. The Ni(NO 3 ) 2 Solution A (15.0 ml), the Mn(NO 3 ) 2 Solution B (7.200 ml), and the La(NO 3 ) 3 Solution (1.500 ml) were combined with the support material, and the mixture was stirred and dried at 110 * C for 10 hours.
  • the Pd(II) Solution (12.00 ml) was added to the Ni-, Mn-, and La- impregnated support, and the support was then dried at 110°C for 5 hours, and then calcined in air at 480°C for 4 hours.
  • Example IB Direct amination of benzene in the presence ofthe Pd/Ni-oxide/Mn-oxide/La- oxide/ZrO 2 catalyst was then effected as described in Example IB.
  • a benzene conversion of 4.8 % was achieved with about 100 % aniline selectivity based on weight and relative to benzene (as determined by GC).
  • a Pd/Ni-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 /HOC 3 H 7 (70wt%, 8.3 ml, Aldrich Cat. No. 33,397-2) was mixed with 5.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material. The Ni(NO 3 ) 2 Solution A (15.0 ml) was combined with the support material, and the mixture was stirred and dried at 110 °C for 5 hours.
  • the Pd(II) Solution (12.00 ml) was added to the Ni-impregnated support, and the support was then dried at 110°C for 5 hours, and then calcined in air at 450°C for 4 hours.
  • Direct amination of benzene in the presence ofthe Pd/Ni-oxide/ZrO 2 catalyst was then effected as described in Example IB.
  • a benzene conversion of 4.6 % was achieved with about 100 % aniline selectivity based on weight and relative to benzene (as determined by GC).
  • Example 3D Pd/Ni-oxide/La-oxide/Zr0 2
  • a Pd/Ni-oxide/La-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 / HOC 3 H 7 (70wt%, 6.43 ml, Aldrich Cat. No. 33,397-2) was mixed with 4.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material. The Ni(NO 3 ) 2 Solution A (15.0 ml) and the La(NO 3 ) 3 Solution (0.900 ml) were combined with the support material, and the mixture was stirred and dried at 110 °C for 5 hours. After drying, the Pd(LT) Solution (12.00 ml) was added to the Ni- and La-impregnated support, and the support was then dried at 110°C for 5 hours, and then calcined in air at 450°C for 4 hours.
  • Example IB Direct amination of benzene in the presence ofthe Pd/Ni-oxide/La-oxide/ZrO 2 catalyst was then effected as described in Example IB.
  • a benzene conversion of 4.8 % was achieved with about 100 % aniline selectivity based on weight and relative to benzene (as determined by GC).
  • a Pd/Ni-oxide catalyst was prepared as follows.
  • the Ni(NO 3 ) 2 Solution A (60.0 ml) was mixed with poly(acrylic acid) (6.000 g, average M.W. 2000), dissolved in water, dried at 110 °C for 8 hours and then calcined in air at 400 °C for 4 hours to form a powdered Ni-oxide sample.
  • the Pd(II) Solution (12.00 ml) was added to the Ni-oxide powder sample, and the Pd-impregnated sample was dried at 110°C for 4 hours, and then calcined in air at 400°C for 4 hours.
  • Example IB Direct amination of benzene in the presence ofthe Pd/Ni-oxide catalyst was then effected as described in Example IB, except that the reaction temperature was 360 "C. (rather than 350 °C). A benzene conversion of 3.1 % was achieved with about 100 % aniline selectivity based on weight and relative to benzene (as determined by GC).
  • a Pd/Ni-oxide/Ce-oxide catalyst was prepared as follows.
  • the Ni(NO 3 ) 2 Solution A (36.0 ml), the Ce(NO 3 ) 3 Solution (24.0 ml) and poly (acrylic acid) (6.000 g, average M.W. 2000) were dissolved in water.
  • the aqueous solution was freeze-dried, and then calcined in air at 400 °C for 4 hours.
  • the Pd(II) Solution (12.00 ml) was added to the freeze-dried sample, and the Pd-impregnated sample was dried at 110°C for 4 hours, and then calcined in air at 450°C for 4 hours.
  • a Pd Ni-oxide/Pr-oxide catalyst was prepared as follows.
  • the Ni(NO 3 ) 2 Solution A (36.0 ml), the Pr(NO 3 ) 3 Solution (24.0 ml) and poly (acrylic acid) (6.000 g, average M.W. 2000) were dissolved in water.
  • the aqueous solution was freeze-dried, and then calcined in air at 400 °C for 4 hours.
  • the Pd(II) Solution (12.00 ml) was added to the freeze-dried sample, and the Pd-impregnated sample was dried at 110°C for 4 hours, and then calcined in air at 450°C for 4 hours.
  • a Pd/Ni-oxide/V-oxide catalyst was prepared as follows.
  • the Ni(NO 3 ) 2 Solution A (72.0 ml), the V 2 O 5 Solution (24.0 ml) and poly (acrylic acid) (6.000 g, average M.W. 2000) were dissolved in water.
  • the aqueous solution was freeze-dried, and then calcined in air at 400 °C for 4 hours.
  • the Pd(LT) Solution (12.00 ml) was added to the freeze-dried sample, and the Pd-impregnated sample was dried at 110°C for 4 hours, and then calcined in air at 450°C for 4 hours.
  • Example 31 Pd/Ni-oxide/Mn-oxide A Pd/Ni-oxide/Mn-oxide catalyst was prepared as follows. The Ni(NO 3 ) 2 Solution
  • Example 4 Preparation of Aniline with Ruthenium-Based Cataloxidants
  • Ni(NO 3 ) 2 Solution A was prepared as described in Example IB.
  • a Mn(NO 3 ) 2 Solution B was prepared as described in Example 3.
  • a ruthenium solution was prepared by dissolving Ru(NO)(NO 3 ) 3 .xH 2 O (Ru 31.96 wt%, 3.1280 g) into water to make 100ml solution (hereinafter referred to as the "Ru Solution").
  • a Ru/Ni-oxide/Mn-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 /
  • HOC 3 H 7 (70wt%, 7.53 ml, Aldrich Cat. No. 33,397-2) was mixed with 5.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material.
  • the Ni(NO 3 ) 2 Solution A (15.0 ml), the Mn(NO 3 ) 2 Solution B (2.400 ml), and the Ru Solution (6.000 ml) were combined with the support material, the mixture was stirred and dried at 110 °C for 10 hours, and then calcined in air at 480 °C for 4 hours.
  • a Ru/Ni-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 /HOC 3 H 7 (70wt%, 8.300 ml, Aldrich Cat. No. 33,397-2) was mixed with 5.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material. The Ni(NO 3 ) 2 Solution A (15.0 ml) and the Ru Solution (1.800 ml) were combined with the support material, the mixture was stirred and dried at 110 °C for 10 hours, and then calcined in air at 450 ° C for 4 hours.
  • Example 5 Preparation of Aniline with Platinum-Based Cataloxidants This example demonstrates the synthesis of a Pt/Ni-oxide/Mn-oxide/ZrO 2 catalyst
  • Example 5 A and of a Pt/Ni-oxide/ZrO 2 catalyst (Example 5B), as well as the use thereof for the direct amination of benzene to aniline.
  • Ni(NO 3 ) 2 Solution A was prepared as described in Example IB.
  • a Mn(NO 3 ) 2 Solution B was prepared as described in Example 3.
  • a platinum solution was prepared by dissolving
  • Example 5 A Pt/Ni-oxide/Mn-oxide/Zr0 2
  • a Pt/Ni-oxide/Mn-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 / HOC 3 H 7 (70wt%, 6.87 ml, Aldrich Cat. No. 33,397-2) was mixed with 5.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material. The Ni(NO 3 ) 2 Solution A (15.0 ml), and the Mn(NO 3 ) 2 Solution B (6.000 ml) were combined with the support material, the mixture was stirred and dried at 110 ° C for 5 hours, and then calcined in air at 450 °C for 4 hours.
  • the Pt Solution (3.000 ml) and acetic acid (12.0 ml) were added to the Ni- and Mn- impregnated sample, the sample was dried at 110 ° C for 5 hours, and then calcined at 450 °C for 4 hours.
  • a Pt/Ni-oxide/ZrO 2 catalyst was prepared as follows. Zr(OC 3 H 7 ) 4 /HOC 3 H 7 (70wt%, 8.300 ml, Aldrich Cat. No. 33,397-2) was mixed with 5.0 ml distilled water at room temperature while stirring. After hydrolysis, the sample was dried at 110°C for 5 hours to form a support material. The Ni(NO 3 ) 2 Solution A (15.0 ml was combined with the support material, the mixture was stirred and dried at 110 °C for 5 hours, and then calcined in air at 450 "C for 4 hours.
  • the Pt Solution (3.000 ml) and acetic acid (12.0 ml) were added to the Ni- and Mn-impregnated sample, the sample was dried at 110 °C for 5 hours, and then calcined in air at 450 "C for 4 hours.
  • This example demonstrates the effective regenerabihty of three Rh/Ni-oxide/Mn- oxide/ZrO 2 (6A-6C), one Rh/Ni-oxide/Mn-oxide/KTiO 2 (6D), one Rh/Co-oxide/ZrO 2 (6E), one Ir/Ni-oxide/Mn-oxide/KTiO 2 (6F), and two Ir/Ni-oxide/Mn-oxide/ZrO 2 catalysts (6G).
  • These examples illustrate, among other things, the effects of varying amounts of rhodium or iridium in the catalyst, the presence of Co as a reducible metal oxide, as well as the impact of different carriers.
  • Example 6A Rh / Ni-oxide / Mn-Oxide / Zr0 2 (3X-, 8X-Regenerated)
  • Catalyst comprising Rh (about 0.5 %), Ni-oxide (about 15 % Ni, assuming all of the Ni-oxide is in the Ni +2 oxidation state) and Mn-oxide (about 1.5 % Mn, assuming V ⁇ of the Mn-oxide is in the Mn +3 oxidation state and Vi ofthe Mn-oxide is in the Mn +4 oxidation state) on ZrO 2 supports, with all percentages being by weight, relative to the weight ofthe support, were evaluated for regenerabihty as follows.
  • the Rh/Ni-oxide/Mn-oxide/ZrO 2 catalyst of Example 1A was prepared, used in a first cycle of benzene amination and then recovered as described therein.
  • the recovered catalyst was dried at 110 ° C for 1 hour, and then regenerated by reoxidation in air in a calcination oven at 475 ° C for 4h.
  • the one-time (IX) regenerated catalyst was subsequently reevaluated in the Parr bomb under the same conditions as outlined above, except that temperature was 325 °C (rather than 300 °C) and the reaction time was 2 hours (rather than 4 hours).
  • Benzene conversion for the second amination reaction with the catalyst was determined to be 6.8% with about 100% selectivity for aniline (based on weight and relative to benzene, as determined by calibrated GC analysis; 5.9% conversion prior to calibration).
  • the catalyst was regenerated a second and third time, in two additional regeneration experiments, and in each case the 2X- and 3X- regenerated catalyst was employed to effect the direct amination of benzene under the same conditions as in the lX-regenerated case.
  • a stable benzene conversion of about 5.3 % was achieved in the two additional regeneration experiments, with about 100% selectivity to aniline (based on weight and relative to benzene, as determined by calibrated GC analysis; 4.6% conversion prior to calibration).
  • Example 1 A a Rh/Ni-oxide/Mn-oxide/ZrO 2 catalyst was prepared, reacted and evaluated as described in Example 1 A.
  • the catalyst was recovered as described in Example 1 A, dried at 110 ° C for 1 hour, and then regenerated by reoxidation in air in a calcination oven at 475 °C for 4h.
  • the cycle of amination reactions and regeneration was repeated eight times.
  • the amination reaction conditions were the same as that described in Example 1 A, except for some variations in reaction temperature and reaction time as noted in Table 1, below.
  • the regeneration conditions were as described above, except for some variation in reoxidation (calcination) time as noted in Table 1, below.
  • benzene conversion ranged from about 6.2% to about 5.5% (as determined by calibrated GC analysis; 5.4% and 4.8% conversion, respectively " prior to calibration) for the first eight reactions (i.e., for the original catalyst and the IX- regenerated through 7X-regenerated catalysts), and from about 5.4 % to about 4.1 % when the ninth reaction (i.e., with the 8X-regenerated catalyst) is included.
  • good conversion was achieved with reaction times of 1 hour or less at a temperature of 350 °C
  • the selectivity for aniline was about 100% selectivity based on weight and relative to benzene, as determined by GC.
  • Example 6B Rh /Ni-oxide / Mn-Oxide / Zr0 2 (1 lX-Regenerated)
  • Catalyst comprising Rh (about 3 %), Ni-oxide (about 10 % Ni, assuming all ofthe Ni-oxide is in the Ni +2 oxidation state) and Mn-oxide (about 3 % Mn, assuming Vz ofthe Mn-oxide is in the Mn +3 oxidation state and Vz ofthe Mn-oxide is in the Mn +4 oxidation state) on ZrO 2 supports, with all percentages being by weight, relative to the weight ofthe support, were evaluated for regenerabihty as follows.
  • the Rh/Ni-oxide/Mn-oxide/ZrO 2 catalyst was prepared substantially as described in Example 1A, except that the amount ofthe support, and the relative amounts ofthe nickel nitrate, the manganese nitrate and the Rh(III) nitrate solution used to prepare the precursor solution were adjusted.
  • the catalyst composition was prepared as described from a zirconia support (22 g), and from a precursor solution formed from the combination of Ni(NO 3 ) 2 .6H 2 O (10.9 g), Mn(NO 3 ) 2 .x H 2 O (2.149 g), and rhodiurn(IT ⁇ ) nitrate solution (4.68 ml, 10% wt/wt Rh).
  • Benzene was directly aminated with ammonia in an initial reaction, the catalyst was regenerated, and then the cycle of amination reactions and regeneration was repeated eleven times.
  • the catalyst was recovered as described in Example 1 A, dried at 110 °C for 1 hour, and then regenerated by reoxidation in air in a calcination oven at 475 ° C for 4h.
  • benzene conversion ranged from about 3.3% to about 2.9% (as determined by calibrated GC analysis; 2.9% and 2.5% conversion, respectively, prior to calibration) for the first six reactions (i.e., for the original catalyst and the IX- regenerated through 5X-regenerated catalysts.
  • Benzene conversion ranged from about 3.7 % to about 1.3 % for the 6X-regenerated through the 1 lX-regenerated catalyst.
  • the selectivity for aniline was about 100% selectivity based on weight and relative to benzene, as determined by GC.
  • Table 2 Regeneration of Rh/Ni-oxide/Mn-Oxide/ZrO 2 Catalyst
  • Example 6C Rh /Ni-oxide / Mn-Oxide /Zr0 2 (7X-Regenerated)
  • the Rh/Ni-oxide/Mn-oxide/ZrO 2 catalyst was prepared substantially as described in Example 1A, except that the relative amounts ofthe mckel nitrate, the manganese nitrate and the Rh(III) nitrate solution used to prepare the precursor solution were adjusted. Specifically, the catalyst composition was prepared as described from a zirconia support
  • Benzene was directly aminated with ammonia in an initial reaction, the catalyst was regenerated, and then the cycle of amination reactions and regeneration was repeated eleven times.
  • the catalyst was recovered as described in Example 1 A, dried at 110 °C for 1 hour, and then regenerated by reoxidation in air in a calcination oven at 475 °C for 4h.
  • the data from the 7X-regenerated catalyst demonstrates that this shorter reaction time can be acceptable if the temperature is raised (e.g., to 325 °C).
  • the selectivity for aniline was about 100% selectivity based on weight and relative to benzene, as determined by GC.
  • Example 6D Rh / Ni-oxide / Mn-oxide / KTi0 2 (5X-Regenerated)
  • the catalyst was prepared and initially utilized for the direct amination of benzene as described in Example IC. After isolation, the catalyst was dried at 110°C for 1 hour, and then regenerated by reoxidation in air in a calcination oven at 475 °C for about 1 hours. The one-time (IX) regenerated catalyst was subsequently reevaluated two times under similar reaction conditions. The catalyst was then isolated, regenerated and reevaluated 3 additional times using similar reaction conditions, the exception being that the ammonia to benzene ratio was increased to 6. The reactions conditions and results are summarized in Table 4, below.
  • Example 6E Rh / Co-oxide / Zr0 2 (2X-Regenerated)
  • the catalyst was prepared and initially utilized for the direct amination of benzene as described in Example ID.
  • the catalyst was isolated and regenerated as described in Example 1 A; more specifically, the catalyst was isolated and then reoxidized by heating in air to 475 °C for 4 hours.
  • the one-time (IX) regenerated catalyst was subsequently reevaluated under similar reaction conditions.
  • the catalyst was then isolated, regenerated and reevaluated a third time using similar reaction conditions, the exception being that the catalyst was reoxidized by heating to 500°C for 4 hours.
  • Table 5 The results are summarized in Table 5, below.
  • Rh/Co-oxide/ZrO 2 catalyst affords greater selectivity when regenerated at 500°C. Additional experimentation (not reported here), was conducted which supported this conclusion.
  • Example 6F Ir / Ni-oxide /Mn-oxide / KTi0 2 (lX-Regenerated)
  • the catalyst was prepared and initially utilized for the direct amination of benzene as described in Example 2C (reactant to catalyst ratio about 2.5). After isolation, the catalyst was dried at 110°C for 1 hour, and then regenerated by reoxidation in air in a calcination oven at 475 °C for about 1 to about 4 hours. The one-time (IX) regenerated catalyst was subsequently reevaluated at 350°C at a pressure of about 300 bar for 1 hour.
  • the reaction conditions and results are summarized in Table 7, below.
  • Example 6G Ir / Ni-oxide / Mn-Oxide / Zr0 2 (1 OX-Regenerated)
  • a catalyst comprising Ir (about 0.5%), Ni-oxide (about 18% Ni, assuming all of the Ni-oxide is in the Ni +2 oxidation state), and Mn-oxide (about 1.5% Mn, assuming l A of the Mn-oxide is in the Mn +4 oxidation state) on a ZrO 2 support, with all percentages being by weight, relative to the weight ofthe support, prepared, reacted and evaluated similar to the procedure described in Example 2A. More specifically, the catalyst was initially reacted in accordance with Example 2A, but using a temperature of 300°C and a reaction time of 4 hours.
  • the catalyst was recovered as described in Example 1A, dried at 110°C for 1 hour, and then regenerated by reoxidation in air in a calcination oven, typically at 475 °C for 4 hours.
  • the cycle of amination reactions and regenerations was repeated 10 times, the precise conditions for each provided in Table 8, below.
  • benzene conversion ranged from about 5.3% to about 3.1%> over the entire reaction sequence, the latter being due to the lower reaction temperature employed in the initial reaction. Additionally, in each case, the selectivity for aniline was about 100%), based on weight and relative to benzene, as determined by GC analysis.
  • a catalyst comprising Ir (about 0.5%), Ni-oxide (about
  • Example 2A 18% Ni, assuming all ofthe Ni-oxide is in the Ni +2 oxidation state) and Mn-oxide (about 1.5% Mn, assuming V ofthe Mn-oxide is in the Mn +4 oxidation state) on a ZrO 2 support, with all percentages being by weight, relative to the weight ofthe support, prepared, reacted and evaluated similar to the procedure described in Example 2A. More specifically, the catalyst was initially reacted in accordance with Example 2A, but using a temperature of 325°C and a reaction time of 2 hours. The catalyst was recovered as described in Example 1A, dried at 110°C for 1 hour, and then regenerated by reoxidation in air in a calcination oven, typically at 475 °C for 4 hours. The cycle of amination reactions and regenerations was repeated 10 times, the precise conditions for each provided in Table 9, below.
  • Rh/Ni-oxide/Mn-oxide/ZrO 2 catalysts were prepared substantially as described in Example 1 A. Benzene was directly aminated with ammonia in accordance with Example 1 A (at a reaction pressure of 300 bar), and then recovered as described therein. The recovered catalyst was dried at 110°C for 1 hour, and then regenerated by reoxidation in air in a calcination oven at 475 °C for 4 hours. The one-time (IX) regenerated catalyst was subsequently reevaluated in the Parr bomb under the same reaction conditions, except that the reaction pressure was changed (as further detailed in Table 10, below). This procedure was repeated until the catalyst had been regenerated and reevaluated 6 times, a total of 7 reactions being performed.
  • ammonia partial pressures are preferably at least about 150 bar, and more preferably at least about 200 bar, in order to drive the reaction, avoid coking and production of toluene and/or diphenyl.
  • effective amination can be achieved at much lower total pressures (i.e., about 1 to about 50 bar).
  • Catalysts comprising (i) Rh (about 0.5%), Ni-oxide (about 15% Ni, assuming all of the Ni-oxide is in the Ni +2 oxidation state) and Mn-oxide (about 1.5% Mn, assuming Vz of the Mn-oxide is in the Mn +4 oxidation state), and (ii) comprising Ir (about 0.5%), Ni-oxide (about 15% Ni, assuming all ofthe Ni-oxide is in the Ni +2 oxidation state) and Mn-oxide (about 1.5% Mn, assuming l A ofthe Mn-oxide is in the Mn +4 oxidation state), both on a ZrO 2 support, with all percentages being by weight and relative to the weight ofthe support, were prepared and evaluated for their performance upon recycle using different reactant ratios, in order to investigate the effects of reactant ratio, and more specifically the ratio of ammonia to benzene, on reaction conversion and selectivity.
  • Example 6G For the Ir/Ni-oxide/Mn-oxide/ZrO 2 catalyst, which was prepared substantially as described in Example 2 A, the impact of varying reactant ratios was studied during the above-described regeneration studies (see Example 6G). More specifically, initially benzene was directly aminated with ammonia in accordance with Example 2A, and then recovered as described therein. The recovered catalyst was dried at 110°C for 1 hour, and then regenerated by reoxidation in air in a calcination oven at 475 °C for 4 hours. The onetime (IX) regenerated catalyst was subsequently reevaluated in the Parr bomb under similar reaction conditions.
  • IX onetime
  • the catalyst was regenerated and reevaluated 10 times, the final 4 of these experiments (i.e., 7X through 10X) being carried out using the same reaction conditions (350 °C for 2 hours), with the exception that the reactant ratio of ammonia to benzene was varied (as further detailed in Table 11, below).
  • Rh/Ni-oxide/Mn-oxide/ZrO 2 catalyst was prepared substantially as described in Example 1A.
  • benzene was directly aminated with ammonia in accordance with Example 1 A, and then recovered as described therein.
  • the recovered catalyst was dried at 110°C for 1 hour, and then regenerated by reoxidation in air in a calcination oven at 475 °C for 4 hours.
  • the onetime (IX) regenerated catalyst was subsequently reevaluated in the Parr bomb under similar reaction conditions.
  • the catalyst was regenerated and reevaluated 8 times, the final 2 of these experiments (i.e., 7X and 8X) being carried out using the same reaction conditions (325 °C for 2 hours), with the exception that the reactant ratio of ammonia to benzene was varied. More specifically, the ratio was 3.0 for catalyst cycle 7X, while the ratio was increased to 6.0 for catalyst cycle 8X.
  • the benzene conversion for these reactions was about 6.2% and 7.0%, respectively, as determined by GC analysis.
  • the aniline selectivity for these reactions remained essentially the same, at about 100% (as determined by GC analysis.

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Abstract

L'invention concerne des catalyseurs à métal noble/oxyde métallique réductible efficaces pour l'amination directe d'hydrocarbures aromatiques et d'analogues hétérocycliques de ceux-ci. Dans un mode de réalisation, l'oxydant catalytique comprend un métal noble sélectionné parmi Pd, Rh, Ir et/ou Ru et un oxyde métallique réductible. Dans un autre mode de réalisation, l'oxydant catalytique comprend un métal noble et un oxyde réductible d'un métal sélectionné parmi Ni, Mn, V, Ce, Tb, Pr, Te, Re, Co, Fe, Cu et/ou Bi. Un oxydant catalytique préféré comprend au moins un métal noble sélectionné parmi Pd, Rh, Ir et/ou Ru, en combinaison avec un oxyde de nickel et/ou un oxyde de manganèse. Dans des applications préférées, du benzène peut être aminé en présence des oxydants catalytiques pour former de l'aniline. On obtient une conversion du benzène d'au moins 5 %, avec une sélectivité pour l'aniline supérieure à 90°. L'oxydant catalytique peut être régénéré sans qu'il présente une réduction substantielle de ses performances, ce qui est important.
PCT/US2000/013266 1999-05-13 2000-05-15 Amination d'hydrocarbures aromatiques et d'analogues heterocycliques de ceux-ci WO2000069804A1 (fr)

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DE102004062253A1 (de) * 2004-12-23 2006-07-06 Basf Ag Direktaminierung von Kohlenwasserstoffen
DE102005041140A1 (de) * 2005-08-30 2007-03-01 Basf Ag Direktaminierung von Kohlenwasserstoffen
ES2370853T3 (es) 2006-02-24 2011-12-23 Basf Se Aminación directa de hidrocarburos.
KR20080104336A (ko) 2006-02-24 2008-12-02 바스프 에스이 탄화수소의 직접 아미노화
EP2061747B1 (fr) 2006-07-14 2013-04-17 Basf Se Procédé de production d'une amine
US7754922B2 (en) 2006-07-14 2010-07-13 Basf Se Process for preparing amines and zirconium dioxide- and nickel-containing catalysts for use therein
JP5637684B2 (ja) 2006-07-14 2014-12-10 ビーエーエスエフ ソシエタス・ヨーロピアＢａｓｆ Ｓｅ アミンの製造方法
WO2008006754A1 (fr) 2006-07-14 2008-01-17 Basf Se Procédé de production d'une amine
US20090292144A1 (en) * 2006-07-21 2009-11-26 Basf Se Direct amination of hydrocarbons
WO2009080510A1 (fr) 2007-12-21 2009-07-02 Basf Se Procédé de fabrication d'une amine
EP2225027B1 (fr) 2007-12-21 2012-05-23 Basf Se Procédé de préparation d'une amine
JP5528349B2 (ja) 2007-12-21 2014-06-25 ビーエーエスエフ ソシエタス・ヨーロピア アミンの製造方法
ATE553844T1 (de) 2007-12-21 2012-05-15 Basf Se Verfahren zur herstellung eines amins
WO2011003964A2 (fr) 2009-07-10 2011-01-13 Basf Se Procédé d'amination directe d'hydrocarbures en amino-hydrocarbures avec séparation électrochimique d'hydrogène
WO2011003932A2 (fr) 2009-07-10 2011-01-13 Basf Se Procédé d'amination directe d'hydrocarbures en amino-hydrocarbures avec séparation électrochimique d'hydrogène
WO2011003934A2 (fr) 2009-07-10 2011-01-13 Basf Se Procédé d'amination directe d'hydrocarbures en amino-hydrocarbures avec séparation électrochimique d'hydrogène
US8642810B2 (en) 2009-07-10 2014-02-04 Basf Se Method for the direct amination of hydrocarbons into amino hydrocarbons, including electrochemical separation of hydrogen and electrochemical reaction of the hydrogen into water
WO2013131723A1 (fr) 2012-03-06 2013-09-12 Basf Se Procédé de préparation d'amino-hydrocarbures par amination directe d'hydrocarbures
WO2013131864A1 (fr) 2012-03-06 2013-09-12 Basf Se Procédé de préparation d'amino-hydrocarbures par amination directe d'hydrocarbures
CN106278904B (zh) * 2016-08-08 2018-03-27 河北工业大学 由苯一锅法制备环己胺的方法
KR102160602B1 (ko) * 2017-12-27 2020-09-28 한화솔루션 주식회사 탄화수소 함유 용액 내의 방향족 함량의 측정 방법

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CA553988A (fr) * 1958-03-04 L. Thomas Charles Preparation d'amines aromatiques
US2948755A (en) * 1958-03-07 1960-08-09 Universal Oil Prod Co Preparation of aromatic amines
HUP0004613A3 (en) * 1997-08-21 2001-05-28 Huntsman Ici Chemicals Llc Sal Process for the production of aromatic amines

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