# Patent

## Title
Activated base metal catalysts

## Abstract

Nitro-compounds are hydrogenated with an activated Ni catalyst whose Ni/Al alloy also contained one or more elements from the list of Cu, Ag and Au prior to activation. In combination with the Group IB elements mentioned above, this catalyst can also be doped with other elements via their addition to the Ni/Al alloy prior to activation and/or they can be adsorbed onto the surface of the catalyst either during or after the activation of the alloy. The suitable doping elements for the alloy prior to activation in combination with the group IB elements mentioned above are one or more of the elements from the list of Mg, Ti, Ce, Cr, V, Mo, W, Mn, Re, Fe, Co, Tr, Ru, Rh, Pd, Pt and Bi. The suitable doping elements that may be adsorbed onto the surface of the catalyst that was previously doped in the alloy prior to activation with the group IB elements mentioned above are one or more elements from the list Mg, Ca, Ba, Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au and Bi.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is US national stage of international application PCT/EP2007/055185, which had an international filing date of May 29, 2007, and which was published in English under PCT Article 21(2) on Dec. 4, 2008.
FIELD OF THE INVENTION
The invention concerns an activated base metal catalyst, and its use for the hydrogenation of nitro-compounds.
BACKGROUND OF THE INVENTION
Activated metal catalysts are also known in the fields of chemistry and chemical engineering as Raney-type, sponge and/or skeletal catalysts. They are used, largely in powder form, for a large number of hydrogenation, dehydrogenation, isomerization, reductive amination, reductive alkylation and hydration reactions of organic compounds. These powdered catalysts are prepared from an alloy of one or more catalytically-active metals, also referred to herein as the catalyst metals, with a further alloying component which is soluble in alkalis. Mainly nickel, cobalt, copper, iron or combinations thereof are used as catalyst metals. Aluminum is generally used as the alloying component which is soluble in alkalis, but other components may also be used, in particular zinc and silicon or mixtures of these either with or without aluminum.
These so-called Raney alloys are generally prepared by the ingot casting process. In that process a mixture of the catalyst metal and, for example, aluminum is first melted and casted into ingots.
Typical alloy batches on a production scale amount to about ten to a couple hundred kg per ingot. According to DE 21 59 736 cooling times of up to two hours were obtained for this method. This corresponds to an average rate of cooling of about 0.2 K/s. In contrast to this, rates of 102 to 106 K/s and higher are achieved in processes where rapid cooling is applied (for example an atomizing process). The rate of cooling is affected in particular by the particle size and the cooling medium (see Materials Science and Technology edited by R. W. Chan, P. Haasen, E. J. Kramer, Vol. 15, Processing of Metals and Alloys, 1991, VCH-Verlag Weinheim, pages 57 to 110). A process of this type is used in EP 0 437 788 B 1 in order to prepare a Raney alloy powder. In that process the molten alloy at a temperature of 5 to 500° C. above its melting point is atomized and cooled using water and/or a gas.
To prepare a powder catalyst, the Raney alloy which can be made by a known process (i.e. according to EP 0 437 788 B1) is first finely milled, if it has not been produced in the desired powder form during preparation. Then the aluminum is partly (and if need be, totally) removed by extraction with alkalis such as, for example, caustic soda solution (other bases such as KOH are also suitable) to activate the alloy powder. These types of catalysts can be activated with most bases and acids to give varying results. Following extraction of the aluminum, the remaining catalytic power has a high specific surface area (BET), between 5 and 150 m2/g, and is rich in active hydrogen. The activated catalyst powder is pyrophoric and stored under water or organic solvents or is embedded in organic compounds (e.g., distearylamine) which are solid at room temperature.
U.S. Pat. No. 6,423,872 describes the use of Ni catalysts that contain less than 5.5 wt % Al for the hydrogenation of nitrated aromatics. It describes the use of both commercially available standard activated Ni catalysts and supported Ni catalysts for the hydrogenation of nitrated aromatics, where problematic nickel aluminates are formed during this hydrogenation if their Al content is 5.5 wt % Al or higher.
These nickel aluminates can be in the form of takovite and/or takovite-like compounds and all of these nickel aluminates need to be removed from the desired amine before it is processed further. These nickel aluminates tend to form solids in the reactor and in the peripheral equipment (e.g., piping, settling tanks, filtration equipment, pumps and other equipment used in this process) that can deposit on their walls to decrease their heat transfer efficiency and to create blockages in the system.
Hence the formation of these nickel aluminates creates both safety hazards and a drop in productivity. The buildup of these nickel aluminates make it difficult to continue with the reaction and in such cases, one needs to shutdown the plant and clean out these deposits from the reactor and the peripheral equipment.
U.S. Pat. No. 6,423,872 also mentions the use of very specific alloy dopants limited to a definite list of elements that remain in the activated Ni catalyst after activation with caustic and the use of these resulting catalysts for the continuous hydrogenation of nitrated aromatics.
The conventional alloy doping elements from the groups IVA, VA, VIA and VIII of the periodic table of elements were specifically claimed in this patent. Additional Alloy doping elements such as titanium iron and chromium were also claimed.
U.S. Pat. No. 6,423,872 describes the use of a Ni catalyst having less than 5.5 wt % Al for the continuous hydrogenation of nitrated aromatics due to its lower formation of undesirable nickel aluminates during this hydrogenation. In principle, the less Al you have in the catalyst, the lower the amount of the nickel aluminates you will form. However these catalysts still form nickel aluminates and this technology does have its limits since the Al that is present in them is still considerably leachable under the conditions used for the hydrogenation of nitro-compounds such as nitrated aromatics.
U.S. Pat. No. 6,423,872 keeps the Al level lower than 5.5 wt % by changing the Al content of the alloy and/or increasing the intensity of the activation process. Increasing the Al content in the alloy will increase the amounts of Al-rich and more readily leachable phases such as NiAl3 and the Al-eutectic phases. Another way to increase the amounts of these phases would be to perform the appropriate heat treatment to the alloy either after or during its production. Increasing the amounts of these readily leachable phases can also decrease the mechanical stability of these catalysts, thereby leading to a lower lifetime for the catalysts.
Hence lowering the Al content of the catalyst simply by increasing the amount of leachable phases in the precursor alloy does have its limitations.
Another method that U.S. Pat. No. 6,423,872 describes to decrease the Al content in the catalyst was to increase the intensity of the activation process by increasing the leaching temperature, pressure and other parameters that accelerate this process. However, not only does this increase the cost of the catalyst, but it also produces a sodium aluminate side product that is not salable and would need to be disposed of. Moreover if one is not careful during leaching, the newly formed sodium aluminate under these harsher conditions may deposit back on to the catalyst and block its catalytically active surface leading to lower activity and shorter catalyst life.
While the methods of U.S. Pat. No. 6,423,872 do decrease the level of leachable Al to some degree, they do not entirely solve the problems involved with the hydrogen of nitro-compounds, since most alloy activations used in catalyst production occur under different conditions than those of the continuous hydrogenation of nitro-compounds such as nitrated aromatic compounds. Thus the commercially applicable methods of U.S. Pat. No. 6,423,872 produce a catalyst that still has a considerable amount of Al in the catalyst that can be leached out during the hydrogenation of nitrated aromatic compounds.
DESCRIPTION OF THE INVENTION
Hence it is a goal of the present invention to produce a catalyst that generates lower levels of nickel aluminates buy minimizing the leachability of the remaining Al in the catalyst, regardless of the level of Al.
Surprisingly this problem is solved with the activated Ni catalysts according to this invention.
The formation of takovite during the hydrogenation of nitro-compounds with an activated Ni catalyst can be greatly reduced, by doping the Ni/Al alloy with one or more of the doping elements from the list of Cu, Ag and Au prior to activation. Another variation of this catalyst would be to dope the Ni/Al alloy with one or more of the elements from the list of Cu, Ag and Au in addition to one or more elements from the list of Mg, Ti, Ce, Cr, V, Mo, W, Mn, Re, Fe, Co, Ir, Ru, Rh, Pd, Pt and Bi before activation. The preferred version of this catalyst type is produced by the activation of a Ni/Al alloy containing Cu together with one or more elements from the list of Mg, Ti, Cr, V, Mo, Fe, Co, Pd and Pt.
A further embodiment of this invention is the use of an activated Ni catalyst for nitro-compound reduction, whereas the Ni/Al alloy contained one or more of the doping elements from the list of Cu, Ag and Au before activation and the catalyst is further doped with one or more elements from the list of Mg, Ca, Ba, Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au and Bi by their adsorption onto the surface of the catalyst during and/or after activation of the precursor alloy. The adsorption of one or more of the above mentioned elements can also be done before, during and/or after washing the catalyst subsequent to activation. The adsorption of the doping element(s) can take place with existing compounds of the doping element(s) and/or with compounds of the doping element(s) that are formed in-situ during the doping process. The adsorption of the doping element(s) normally takes place in a liquid phase and the compounds of the doping elements can be soluble in the liquid medium or only slightly soluble in the liquid phase so that the rate of doping can be controlled by the solubility controlled concentration of the doping element(s) in the slurry phase. One could also add inhibitors (e.g., chelating agents), accelerators (e.g., precipitating agents) and combinations thereof that control the rate of adsorption of the doping element(s) on to the catalytic surface. One could also use the gas phase to adsorb doping elements provided that care is taken to prevent the excessive oxidation and deactivation of the catalyst. In such cases, it could actually be possible to adsorb the promoting elements via techniques such as evaporation, sublimation and sputtering onto the catalytic surface. This use of adsorption methods for the doping of the catalyst is clearly different than the addition of the doping elements to the alloy prior to activation in that the adsorption method concentrates the doping element onto the surface of the catalyst with very little, if any of it at all, being in the bulk of the catalyst particle. This surprisingly helps in inhibiting the formation of takovite. The preferred above mentioned doping elements is Cu via its addition to the Ni/Al alloy prior to activation and one or more of the elements from the list Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au to be adsorbed onto the surface of the catalyst.
An additional embodiment is the activation of a Ni/Al alloy containing one or more of the elements from the list of Cu, Ag and Au in addition to one or more elements from the list of Mg, Ti, Ce, Cr, V, Mo, W, Mn, Re, Fe, Co, Ir, Ru, Rh, Pd, Pt and Bi followed by the doping of this catalyst with one or more elements from the list of Mg, Ca, Ba, Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au and Bi by their adsorption onto the surface of the catalyst during and/or after activation of the precursor alloy. The preferred combination would be to activate a Ni/Al alloy that contains Cu together with one or more elements from the list of Mg, Ti, Cr, V, Mo, Fe, Co, Pd and Pt followed by the further doping of the catalyst via the adsorption of and one or more elements from the list of Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au onto the surface of the catalyst.
The doping level of the preferred catalyst can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
Optimally the catalysts can contain between 0.01 and 1.9 wt.-% Fe.
Optimally the catalysts can contain between 0.01 and 2.4 wt.-% Cr.
Optimally the catalysts can contain between 0.01 and 1.9 wt.-% Fe and contain between 0.01 and 2.4 wt.-% Cr.
The powdered activated base metal catalysts (Raney-type catalysts) are typically used in either batch or continuous processes with stirred tank reactors. Batch processes are very flexible and under the right conditions, they are very economical for the hydrogenation of nitro-compounds to amines.
Another method involves the use of these powder catalysts in loop reactors where the reaction could occur in the vapor, trickle, aerosol or liquid phase. Loop, tube and stirred tank reactors can be used continuously for this process, where the nitro-compound is fed into the reactor at a rate in which it is immediately hydrogenated to completion or in some cases almost to completion when a second hydrogenation reactor (or even more) is used to hydrogenate the remaining amounts of the nitro-compound and its possible intermediates. During the continuous hydrogenation process, the same amount of the desired amine is removed from of the reaction system at the same rate as the nitro-compound is added to maintain the overall volume of the reaction medium in the reactor. In the case of loop and tube reactors, this reaction may be done in a circulation mode where the nitro-compound is introduced in one part of the circulating reaction stream and the finished product mixture is taken out of another part.
This reaction can take place in the presence of one or more solvents (for example but not limited to alcohols such as methanol and ethanol) or it can take place in the product mixture of the resulting amine and water. The advantages of using the product mixture for the reaction medium is that one does not need to buy the solvent and it does not need to be removed from the reaction mixture or possibly purified before being used again. Another option would be to perform the reaction in only the desired amine and to use a high enough reaction temperature so that the water is immediately distilled away from the reaction slurry and so that the desired amine remains in a liquid form. This is especially important for amines such as toluenediamine, where it needs to be kept in the molten state if it is to be used as the reaction medium without the assistance of solvents that maintain the liquid properties of the reaction slurry.
In general, the powder catalysts of this invention can be used in any reaction system and in any reaction process that is suitable for the hydrogenation of nitro-compounds to amines that utilize powder catalysts.
This invention includes the process for the hydrogenation of nitro-compounds with an activated Ni catalyst whose Ni/Al alloy initially contained one or more of the doping elements from the list of Cu, Ag and Au prior to activation. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
A further embodiment of this invention is the process for the hydrogenation of nitro-compounds with an activated Ni catalyst whose Ni/Al alloy contained one or more of the doping elements from the list of Cu, Ag and Au in addition to one or more elements from the list of Mg, Ti, Ce, Cr, V, Mo, W, Mn, Re, Fe, Co, Ir, Ru, Rh, Pd, Pt and Bi before activation. The preferred process for this hydrogenation of nitro-compounds utilizes a catalyst that is produced by the activation of a Ni/Al alloy containing Cu together with one or more elements from the list of Mg, Ti, Cr, V, Mo, Fe, Co, Pd and Pt. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
Another embodiment of this invention is the process for the hydrogenation of nitro-compounds with an activated Ni catalyst whose Ni/Al alloy contained one or more of the doping elements from the list of Cu, Ag and Au before activation and the catalyst is further doped with one or more elements from the list of Mg, Ca, Ba, Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au and Bi by their adsorption onto the surface of the catalyst during and/or after activation of the precursor alloy. The preferred process for this hydrogenation of nitro-compounds is with an activated Ni catalyst whose Ni/Al alloy contained Cu prior to activation and the catalyst is additionally doped with one or more of the elements from the list of Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au by their adsorption onto the surface of the catalyst either during or after activation. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
An additional embodiment of this invention is the process for the hydrogenation of nitro-compounds with an activated Ni catalyst whose Ni/Al alloy contained one or more of the elements from the list of Cu, Ag and Au in addition to one or more elements from the list of Mg, Ti, Ce, Cr, V, Mo, W, Mn, Re, Fe, Co, Ir, Ru, Rh, Pd, Pt and Bi prior to activation followed by the doping of this catalyst with one or more elements from the list of Mg, Ca, Ba, Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au and Bi by their adsorption onto the surface of the catalyst during and/or after activation of the precursor alloy. The preferred process for this hydrogenation of nitro-compounds is with an activated Ni catalyst whose Ni/Al alloy contained Cu together with one or more elements from the list of Mg, Ti, Cr, V, Mo, Fe, Co, Pd and Pt prior to activation followed by the further doping of the catalyst via the adsorption of one or more elements from the list of Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au onto the surface of the catalyst. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
This invention includes the process for the hydrogenation of nitrated aromatics with an activated Ni catalyst whose Ni/Al alloy initially contained one or more of the doping elements from the list of Cu, Ag and Au prior to activation. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
A further embodiment of this invention is the process for the hydrogenation of nitrated aromatics with an activated Ni catalyst whose Ni/Al alloy contained one or more of the doping elements from the list of Cu, Ag and Au in addition to one or more elements from the list of Mg, Ti, Ce, Cr, V, Mo, W, Mn, Re, Fe, Co, Ir, Ru, Rh, Pd, Pt and Bi before activation. The preferred process for this hydrogenation of nitrated aromatics utilizes a catalyst that is produced by the activation of a Ni/Al alloy containing Cu together with one or more elements from the list of Mg, Ti, Cr, V, Mo, Fe, Co, Pd and Pt. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
Another embodiment of this invention is the process for the hydrogenation of nitrated aromatics with an activated Ni catalyst whose Ni/Al alloy contained one or more of the doping elements from the list of Cu, Ag and Au before activation and the catalyst is further doped with one or more elements from the list of Mg, Ca, Ba, Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au and Bi by their adsorption onto the surface of the catalyst during and/or after activation of the precursor alloy. The preferred process for this hydrogenation of nitrated aromatics is with an activated Ni catalyst whose Ni/Al alloy contained Cu prior to activation and the catalyst is additionally doped with one or more of the elements from the list of Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au by their adsorption onto the surface of the catalyst either during or after activation. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
An additional embodiment of this invention is the process for the hydrogenation of nitrated aromatics with an activated Ni catalyst whose Ni/Al alloy contained one or more of the elements from the list of Cu, Ag and Au in addition to one or more elements from the list of Mg, Ti, Ce, Cr, V, Mo, W, Mn, Re, Fe, Co, Ir, Ru, Rh, Pd, Pt and Bi prior to activation followed by the doping of this catalyst with one or more elements from the list of Mg, Ca, Ba, Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au and Bi by their adsorption onto the surface of the catalyst during and/or after activation of the precursor alloy. The preferred process for this hydrogenation of nitrated aromatics is with an activated Ni catalyst whose Ni/Al alloy contained Cu together with one or more elements from the list of Mg, Ti, Cr, V, Mo, Fe, Co, Pd and Pt prior to activation followed by the further doping of the catalyst via the adsorption of one or more elements from the list of Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au onto the surface of the catalyst. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
This invention includes the process for the continuous hydrogenation of nitrated aromatics with an activated Ni catalyst whose Ni/Al alloy initially contained one or more of the doping elements from the list of Cu, Ag and Au prior to activation. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
A further embodiment of this invention is the process for the continuous hydrogenation of nitrated aromatics with an activated Ni catalyst whose Ni/Al alloy contained one or more of the doping elements from the list of Cu, Ag and Au in addition to one or more elements from the list of Mg, Ti, Ce, Cr, V, Mo, W, Mn, Re, Fe, Co, Ir, Ru, Rh, Pd, Pt and Bi before activation. The preferred process for this continuous hydrogenation of nitrated aromatics utilizes a catalyst that is produced by the activation of a Ni/Al alloy containing Cu together with one or more elements from the list of Mg, Ti, Cr, V, Mo, Fe, Co, Pd and Pt. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
Another embodiment of this invention is the process for the continuous hydrogenation of nitrated aromatics with an activated Ni catalyst whose Ni/Al alloy contained one or more of the doping elements from the list of Cu, Ag and Au before activation and the catalyst is further doped with one or more elements from the list of Mg, Ca, Ba, Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au and Bi by their adsorption onto the surface of the catalyst during and/or after activation of the precursor alloy. The preferred process for this continuous hydrogenation of nitrated aromatics is with an activated Ni catalyst whose Ni/Al alloy contained Cu prior to activation and the catalyst is additionally doped with one or more of the elements from the list of Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au by their adsorption onto the surface of the catalyst either during or after activation. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
An additional embodiment of this invention is the process for the continuous hydrogenation of nitrated aromatics with an activated Ni catalyst whose Ni/Al alloy contained one or more of the elements from the list of Cu, Ag and Au in addition to one or more elements from the list of Mg, Ti, Ce, Cr, V, Mo, W, Mn, Re, Fe, Co, Ir, Ru, Rh, Pd, Pt and Bi prior to activation followed by the doping of this catalyst with one or more elements from the list of Mg, Ca, Ba, Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au and Bi by their adsorption onto the surface of the catalyst during and/or after activation of the precursor alloy. The preferred process for this continuous hydrogenation of nitrated aromatics is with an activated Ni catalyst whose Ni/Al alloy contained Cu together with one or more elements from the list of Mg, Ti, Cr, V, Mo, Fe, Co, Pd and Pt prior to activation followed by the further doping of the catalyst via the adsorption of one or more elements from the list of Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au onto the surface of the catalyst. The doping level of these catalysts can range from 0.01 wt % to 10 wt % for each doping element and the Al content ranges from 0.05 wt % to 10 wt %.
There are many types of nitro-compound hydrogenations performed in industry. One of the more commercially interesting and technically challenging is the hydrogenation of dinitrotoluene (DNT) to toluenediamine (TDA). This hydrogenation is performed with activated Ni catalysts at temperatures ranging from room temperature to 210° C. and pressures ranging from atmospheric pressure to 200 bar. The preferred reaction conditions are within the ranges of 50° to 180° C. and 3 to 80 bar. This reaction can be performed in an excess of hydrogen or under a stoichiometric amount of hydrogen.
In U.S. Pat. No. 6,423,872, the reaction conditions for the continuous hydrogenation of DNT were 20 bar hydrogen at 150° C. with 0.7 grams of activated Ni catalyst and a DNT feed that kept the level of DNT below 1000 ppm during this hydrogenation. In U.S. Pat. No. 3,935,264, the hydrogenation of DNT was performed with methanol as a solvent under the pressure of 28.5 bar hydrogen and 120° C. over the activated Ni catalyst.
Recently in U.S. Pat. No. 6,005,143, it was found that one could achieve satisfactory results for the hydrogenation of DNT to TDA over a Ni/Pd catalyst supported on a monolith in the presence of methanol with 16 bar hydrogen and temperatures ranging from 135 to 155° C.
Typically fixed bed hydrogenation processes require higher hydrogen pressures than their slurry phase counterparts, indicating that pressures of  ̃16 Bar should also be suitable for the reactions performed here. U.S. Pat. No. 4,224,249 also showed this to be true as a Raney-type Ni catalyst was successfully used at 130° C. and 160 psig (12 bar) for the hydrogenation of dinitrotoluene (DNT) in both the batch and the incremental feed modes of operation. The incremental feed mode of operation was used to simulate the conditions in which DNT is continuously hydrogenated on a industrial scale.
The hydrogenation of nitro-compounds can take place in the vapor, slurry, trickle, aerosol and/or liquid phase. The reaction could be performed as a batch process or it could be performed as a continuous process. The continuous processes may involve, but they are not limited to, a type of circulation process. This invention also includes a continuous process where the nitro-compound is added at a rate that is the same or slower than the rate of hydrogenation, so that the concentration of the nitro-compound is kept to a very low level. The feeding rate of the nitro-compound may be so low that the level of the nitro-compound is 1000 ppm or lower. This invention also includes the use of the previously mentioned catalyst of this invention in a continuous process that utilizes a second hydrogenation reactor (or more) to hydrogenate any nitro-compounds and/or intermediates that were remaining from the hydrogenation in the first hydrogenation reactor.
The nitro-compound hydrogenation of this invention may take place in the presence of the neat nitro-compound, at high concentrations of the reactant, at very low concentrations of the reactant and/or in the presence of the product mixture that would be acting like a solvent. This hydrogenation may also take place in the presence of practically only the desired amine if the water is removed in a satisfactory method (e.g., distillation) during the reaction. The nitro-compound hydrogenation of this invention may take place in the presence of a solvent. The reactor type could be, but is not limited to, a stirred tank reactor, a continuous stirred tank reactor, a loop reactor or a tube reactor. This nitro-compound hydrogenation may occur between atmospheric pressure and 200 bars of hydrogen and the temperature can range from  ̃10° C. to 210° C.
This invention encompasses the hydrogenation of nitrated aromatics and this may occur either as a batch or a continuous process over the above mentioned catalysts. This invention also includes the hydrogenation of DNT to TDA as either a batch process or a continuous process with the above described catalysts.



BRIEF DESCRIPTION OF THE DRAWNINGS
FIG. 1: FIG. 1 shows DNT pulse hydrogenation data for CE1, CE2, CE3, E1, E2 and E3. This graph is referred to herein as “graph 1.”
FIG. 2: FIG. 2 shows DNT pulse hydrogenation data for CE1, CE2, CE3, E4, E5 and E7. This graph is referred to herein as “graph 2.”



EXAMPLES
Application Example 1
The Pulse Hydrogenation of Dinitrotoluene (DNT) to Toluenediamine (TDA)
DNT is typically hydrogenated in an industrial setting via a continuous mode, where the DNT feed rate is slow enough to keep its concentration low enough so that it doesn't poison the catalyst or become a safety hazard. This means that the hydrogenation rate will be dependent of the DNT feed rate. The goal of our pulse hydrogenation method was to keep the DNT concentration low enough so that it would be comparable to the industrial setting while measuring the activity of the catalyst. We were able to do so by pulsing in the DNT feed at a rate that was slightly faster than the rate of hydrogenation so that we could measure catalyst activity while keeping the time of the slight excess of DNT to a minimum. It was also decided to use the reaction pressure and temperature conditions similar to those described in U.S. Pat. No. 4,224,249, U.S. Pat. No. 6,423,872 and U.S. Pat. No. 6,005,143.
The pulse hydrogenation method was started by placing 150 or 300 milligrams of catalyst, 101 grams of TDA and 59 grams of water (the reaction's stoichiometric TDA-to-water ratio) into a 500 ml autoclave. The autoclave was then closed, purged with nitrogen 3 times, purged with hydrogen 3 times and heated to the reaction temperature of 140° C. over a period of 20 minutes while the reactor was stirring at 300 rpm and kept under 5 bar hydrogen. Once the autoclave reached 140° C., the hydrogen pressure was adjusted to 15 bar hydrogen and the stirring rate was increased to 1700 rpm. The reaction was then started by pulsing 4 milliliters of molten DNT into the reactor over 30 seconds with an HPLC pump. The HPLC pump head, the DNT reservoir and all the stainless tubing used for the transport of DNT was kept at 95° C. to keep the DNT molten. A Büchi hydrogen press flow controller (bpc 9901) was used to monitor the hydrogen consumption and once the reaction stopped to consume hydrogen, another pulse of DNT was introduced at the same feed rate. This procedure was continued until a maximum of 45 pulses had been introduced. The data from these hydrogenations can be seen in graph 1, graph 2 and in data tables 3 to 12.
Application Example 2
The Batch Hydrogenation of Nitrobenzene to Aniline
The low pressure hydrogenation of nitrobenzene was carried out over 1.5 grams of catalyst in 110 ml of a 9.1 wt % nitrobenzene ethanolic solution at 25° C. and atmospheric pressure. A baffled glass reactor outfitted with a bubbling stirrer spinning at 2000 rpm was used for these hydrogenations. The results of these hydrogenations are listed in table 1.







TABLE 1







The batch nitrobenzene hydrogenation data.











Nitrobenzene Activity



Catalyst
ml H2/min/gram catalyst














Comparative Example 1
61



Comparative Example 2
49



Example 1
70



Example 2
67



Example 4
75



Example 5
96



Example 6
103



Example 7
92










Application Example 3
The Determination of the Catalyst's Ability to Form Nickel Aluminates (e.g., Takovite)
U.S. Pat. No. 6,423,872 describes a method for the determination of the catalyst's ability to form nickel aluminates (e.g., takovite). This method involved putting the catalyst together with TDA at the temperature of 150° C. for 1 month. The tube was then opened and the catalyst was examined by X-Ray diffraction. It was found that the compound built up on the catalyst was takovite and its structure was shown by X-Ray diffraction to be the same as that of the deposits observed on the walls of an industrial DNT hydrogenation reactor and its peripheral equipment.
We performed a similar test for our studies here.
To determine the catalyst's ability to form takovite, 0.2 grams of the catalyst was placed together with 3.5 grams of a 63 wt % TDA and 37 wt % water mixture in a sealed tube for 3 weeks at 150° C. After the 3 weeks, the catalyst was removed and its takovite residues were analyzed by X-Ray diffraction. The takovite peak heights were then measured at the 12, 24, 35, 40 and 47 °2 theta positions. The nickel peak height at the 52 °2 theta position was also measured and it was the ratios of the individual takovite peak heights to the nickel peak height that was used to compare the different catalysts to each other. The relative ratios for these °2 theta positions were consistent enough for the different catalysts so that it was possible to consider using the ratio of the sum of the takovite peak heights for the 12, 24, 35, 40 and 47 °2 Theta positions to the nickel peak height at 52 °2 theta for this determination.
The data from these experiments are shown in table 2 and the catalysts with the higher takovite formation had the higher takovite-to-Ni peak height ratios. By comparing the catalysts of the same Al content to each other, one can see that the embodiments of this patent lead to lower levels of takovite formation. Only comparative example 1 (CE1) formed a hard version of takovite and the others examples described here only formed soft takovite, if they formed takovite at all.







TABLE 2







The x-ray diffraction data for the takovite deposits on the activated Ni catalysts.











Takovite peak heights (mm) at
Ni at
Ratio of takovite peak heights to


Example
the below listed °2 Θ positions
52
the Ni peak peak height



















number
12
24
35
40
47
°2Θ
12
24
35
40
47
Sum






















CE1
47
33
22
26
22.5
3.0
15.7
11
7.3
8.7
7.5
50.2


CE2
19.5
12.0
12.0
8.0
7.0
12.5
1.6
1.0
1.0
0.6
0.6
4.7


CE3
54
31.5
25.5
18.5
17
7.0
7.7
4.5
3.6
2.6
2.4
20.9


E1
36.5
21
19
14.5
13
10
3.7
2.1
1.9
1.5
1.3
10.4


E2
23
15
13.5
10
8.5
11.2
2.1
1.3
1.2
0.9
0.8
6.3


E3
16.5
10
10.5
7.5
7.0
15.0
1.1
0.7
0.7
0.5
0.5
3.4


E4
15
10
10
7.5
6.0
13
1.2
0.8
0.8
0.6
0.5
3.7


E5
13
10
10
7.5
6.5
11
1.2
0.9
0.9
0.7
0.6
4.3


E7
20
13
12.5
9
8
11.2
1.8
1.2
1.1
0.8
0.7
5.6









Comparative Example 1
An alloy containing Ni, Al, Cr and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in activated Ni catalyst containing 8.8 wt % Al, 2.5 wt % Cr and 2 wt % Fe with an average particle size value of 35 μm was tested for the formation of takovite as described in application example 3. The ratio of the sum of the takovite x-ray diffraction peak heights at 12, 24, 35, 40 and 47 °2 theta to the nickel x-ray diffraction peak height at 52 °2 theta was found to be 50.2. The individual takovite-to-nickel ratios of the x-ray peaks at 12, 24, 35, 40 and 47 °2 theta can be seen in table 2. This catalyst was used for the batch hydrogenation of nitrobenzene to aniline as described in application example 2. The nitrobenzene hydrogenation activity of this catalyst was found to be 61 ml H2/min/gram of catalyst and additional information can be seen in table 1. As described in application example 1, 150 milligrams of this catalyst were used for the pulse hydrogenation of dinitrotolunene to toluenediamine. The selectivity of this reaction was greater than 90% toluenediamine and the activity data points are given below in table 3 and graph 1.







TABLE 3







The dinitrotoluene hydrogenation data for comparative example 1.










grams TDA yielded
Hydrogenation Activity



per gram of
ml H2 per minute per



catalyst
gram of catalyst














15.5
1719



39.4
1258



59.1
1082



81.2
775



99.7
692



116.4
591



137.9
515










Comparative Example 2
An alloy containing Ni, Al and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in an activated Ni catalyst containing 4 wt % Al, and 0.2 wt % Fe with an average particle size value of 28 μm was tested for the formation of takovite as described in application example 3. The ratio of the sum of the takovite x-ray diffraction peak heights at 12, 24, 35, 40 and 47 °2 theta to the nickel x-ray diffraction peak height at 52 °2 theta was found to be 4.7. The individual takovite-to-nickel ratios of the x-ray peaks at 12, 24, 35, 40 and 47 °2 theta can be seen in table 2. This catalyst was used for the batch hydrogenation of nitrobenzene to aniline as described in application example 2. The nitrobenzene hydrogenation activity of this catalyst was found to be 49 ml H2/min/gram of catalyst and additional information can be seen in table 1. As described in application example 1, 150 milligrams of this catalyst were used for the pulse hydrogenation of dinitrotolunene to toluenediamine. The selectivity of this reaction was greater than 99% toluenediamine and the activity data points are given below in table 4 and graph 1.







TABLE 4







The dinitrotoluene hydrogenation data for comparative example 2.










grams TDA yielded
Hydrogenation Activity ml H2



per gram of catalyst
per minute per gram of catalyst














20
1575



31
1620



44
1842



59
1848



77
1893



96
1796



116
1644



137
1567



158
1520



179
1541



200
1586



222
1439



243
1488



265
1533



288
1527



309
1456



333
1436



354
1469



375
1480



397
1422



418
1447



440
1424



462
1393



484
1385



506
1370



528
1341



549
1259



571
1283



593
1183










Comparative Example 3
An alloy containing Ni, Al, Cr and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in an activated Ni catalyst containing 6.3 wt % Al, 1.9 wt % Cr and 0.8 wt % Fe with an APS value of 29 μm was tested for the formation of takovite as described in application example 3. The ratio of the sum of the takovite x-ray diffraction peak heights at 12, 24, 35, 40 and 47 °2 theta to the nickel x-ray diffraction peak height at 52 °2 theta was found to be 20.9. The individual takovite-to-nickel ratios of the x-ray peaks at 12, 24, 35, 40 and 47 °2 theta can be seen in table 2. As described in application example 1, 150 milligrams of this catalyst were used for the pulse hydrogenation of dinitrotolunene to toluenediamine. The selectivity of this reaction was greater than 99% toluenediamine and the activity data points are given below in table 5 and graph 1.







TABLE 5







The dinitrotoluene hydrogenation data for comparative example 3.










grams TDA yielded
Hydrogenation Activity ml H2



per gram of catalyst
per minute per gram of catalyst














6
3154



18
3447



34
3587



51
3440



71
3175



89
3210



111
2924



129
3057



151
2808



172
2607



193
2521



214
2350



237
2273



258
2223



280
2142



302
2070



324
2016



346
1764



367
1788



389
1618



411
1677



432
1591



453
1486



473
1424



494
1380



514
1292



532
1216



552
1187










Example 1
An alloy containing Ni, Al, Cr, Cu and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in an activated Ni catalyst containing 5.04 wt % Al, 1.6 wt % Cr, 0.2 wt % Cu and 0.2 wt % Fe with an APS value of 27 μm was tested for the formation of takovite as described in application example 3. The ratio of the sum of the takovite x-ray diffraction peak heights at 12, 24, 35, 40 and 47 °2 theta to the nickel x-ray diffraction peak height at 52 °2 theta was found to be 10.4. The individual takovite-to-nickel ratios of the x-ray peaks at 12, 24, 35, 40 and 47 °2 theta can be seen in table 2. This catalyst was used for the batch hydrogenation of nitrobenzene to aniline as described in application example 2. The nitrobenzene hydrogenation activity of this catalyst was found to be 70 ml H2/min/gram of catalyst and additional information can be seen in table 1. As described in application example 1, 150 milligrams of this catalyst were used for the pulse hydrogenation of dinitrotolunene to toluenediamine. The selectivity of this reaction was greater than 99.5% toluenediamine and the activity data points are given below in table 6 and graph 1.







TABLE 6







The dinitrotoluene hydrogenation data for example 1.











Hydrogenation Activity



grams TDA yielded
ml H2 per minute per



per gram of catalyst
gram of catalyst














16
3290



27
3523



43
3869



62
3772



82
3664



102
3746



123
3622



144
3527



165
3565



185
3593



206
3311



226
3415



246
3311



267
3209



288
3070



310
3009



331
3050



352
2905



373
2856



394
2737



415
2654



436
2691



457
2528



478
2528



499
2406



520
2363



541
2241



563
2185



584
2118



604
2078



626
1947



647
1850



668
1819



689
1732



710
1672



730
1592



751
1450



769
1336










Example 2
An alloy containing Ni, Al, Cr, Cu and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in an activated Ni catalyst containing 4.5 wt % Al, 0.7 wt % Cr, 0.2 wt % Cu and 0.2 wt % Fe with an APS value of 26 μm was tested for the formation of takovite as described in application example 3. The ratio of the sum of the takovite x-ray diffraction peak heights at 12, 24, 35, 40 and 47 °2 theta to the nickel x-ray diffraction peak height at 52 °2 theta was found to be 6.3. The individual takovite-to-nickel ratios of the x-ray peaks at 12, 24, 35, 40 and 47 °2 theta can be seen in table 2. This catalyst was used for the batch hydrogenation of nitrobenzene to aniline as described in application example 2. The nitrobenzene hydrogenation activity of this catalyst was found to be 67 ml H2/min/gram of catalyst and additional information can be seen in table 1. As described in application example 1, 150 milligrams of this catalyst were used for the pulse hydrogenation of dinitrotolunene to toluenediamine. The selectivity of this reaction was greater than 99.5% toluenediamine and the activity data points are given below in table 7 and graph 1. Although the initial activity of this catalyst was lower than that of CE3, this catalyst had a far lower rate of deactivation than the CE3 and it became more active than CE3 during the reaction and remained more active. Hence, this catalyst is considerably better than CE3.







TABLE 7







The dinitrotoluene hydrogenation data for example 2.











Hydrogenation Activity



grams TDA yielded
ml H2 per minute



per gram of catalyst
per gram of catalyst














18
2767



38
2788



58
2914



78
2863



99
2544



120
2632



141
2532



162
2476



183
2381



204
2334



224
2252



246
2295



267
2231



288
2081



310
2190



331
2062



353
2059



374
1968



396
1898



418
1880



440
1872



462
1837



484
1867



505
1725



527
1675



549
1641



571
1590



592
1564



614
1489



635
1448



657
1422



678
1374



700
1325



722
1273



743
1241



764
1136










Example 3
An alloy containing Ni, Al, Cu and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in an activated Ni catalyst containing 3.81 wt % Al, 0.2 wt % Cu and 0.2 wt % Fe with an APS value of 28 μm was tested for the formation of takovite as described in application example 3. The ratio of the sum of the takovite x-ray diffraction peak heights at 12, 24, 35, 40 and 47 °2 theta to the nickel x-ray diffraction peak height at 52 °2 theta was found to be 3.4. The individual takovite-to-nickel ratios of the x-ray peaks at 12, 24, 35, 40 and 47 °2 theta can be seen in table 2. As described in application example 1, 150 milligrams of this catalyst were used for the pulse hydrogenation of dinitrotolunene to toluenediamine. The selectivity of this reaction was greater than 99.5% toluenediamine and the activity data points are given below in table 8 and graph 1. Although the initial activity of this catalyst was lower than that of CE3, this catalyst had a far lower rate of deactivation than the CE3 and it became more active than CE3 during the reaction and remained more active. As the reaction proceeded, the deactivation rate of the catalyst became very close to zero. Hence, this catalyst is considerably better than CE3.







TABLE 8







The dinitrotoluene hydrogenation data for example 3.











Hydrogenation Activity



grams TDA yielded
ml H2 per minute



per gram of catalyst
per gram of catalyst














10
2050



20
2261



37
2694



56
2685



74
2526



94
2575



111
2346



129
2468



149
2355



168
2176



189
2081



209
2066



230
2043



251
2124



271
2068



293
1871



315
1733



337
1766



358
1725



380
1659



402
1589



423
1622



445
1601



467
1559



488
1519



511
1575



532
1498



554
1501



576
1438



598
1377



619
1432



642
1444



663
1421



686
1447



706
1343










Example 4
An alloy containing Ni, Al, Cr, Cu and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in an activated Ni catalyst containing 3.9 wt % Al, 0.72% Cr, 0.07% Cu and 0.26 wt % Fe. This catalyst had an APS value of 22 μm and was tested for the formation of takovite as described in application example 3. The ratio of the sum of the takovite x-ray diffraction peak heights at 12, 24, 35, 40 and 47 °2 theta to the nickel x-ray diffraction peak height at 52 °2 theta was found to be 3.7. The individual takovite-to-nickel ratios of the x-ray peaks at 12, 24, 35, 40 and 47 °2 theta can be seen in table 2. This catalyst was used for the batch hydrogenation of nitrobenzene to aniline as described in application example 2. The nitrobenzene hydrogenation activity of this catalyst was found to be 75 ml H2/min/gram of catalyst and additional information can be seen in table 1. As described in application example 1, 300 milligrams of this catalyst were used for the pulse hydrogenation of dinitrotolunene to toluenediamine. The selectivity of this reaction was greater than 99.5% toluenediamine and the activity data points are given below in table 9 and graph 2







TABLE 9







The dinitrotoluene hydrogenation data for example 4.











Hydrogenation Activity



grams TDA yielded
ml H2 per minute



per gram of catalyst
per gram of catalyst














9
2928



15
3135



22
2904



31
3289



40
3330



49
3279



59
3404



69
3533



79
3350



90
3145



100
3169



111
3333



120
3750



131
3350



141
3385



151
3179



162
3518



172
3331



182
3245



193
3518



203
3594



214
3402



225
3349



235
3385



245
3422



256
3279



266
3367



277
3195



288
3212



298
3232



307
3064



318
3268



328
3286



339
3094



350
2990



350
2924



360
2704



371
2815



392
2535



402
2471










Example 5
An alloy containing Ni, Al, Cr, Cu and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in an activated Ni catalyst containing 4.3 wt % Al, 1.53% Cr, 0.12% Cu and 0.25 wt % Fe. This catalyst had an APS value of 22 μm and was tested for the formation of takovite as described in application example 3. The ratio of the sum of the takovite x-ray diffraction peak heights at 12, 24, 35, 40 and 47 °2 theta to the nickel x-ray diffraction peak height at 52 °2 theta was found to be 4.3.
The individual takovite-to-nickel ratios of the x-ray peaks at 12, 24, 35, 40 and 47 °2 theta can be seen in table 2. This catalyst was used for the batch hydrogenation of nitrobenzene to aniline as described in application example 2. The nitrobenzene hydrogenation activity of this catalyst was found to be 96 ml H2/min/gram of catalyst (please see table 1). As described in application example 1, 300 milligrams of this catalyst were used for the pulse hydrogenation of dinitrotolunene to toluenediamine. The selectivity of this reaction was greater than 99.5% toluenediamine and the activity data points are given below in table 10 and graph 2







TABLE 10







The dinitrotoluene hydrogenation data for example 5.











Hydrogenation Activity



grams TDA yielded
ml H2 per minute



per gram of catalyst
per gram of catalyst














21
3382



44
2829



66
2775



89
2857



112
2818



135
2613



158
2535



181
2326



204
2164



227
2146



250
2236



273
2205



297
2185



320
2133



343
2105



367
2078



390
2040



413
2081










Example 6
An alloy containing Ni, Al, Cr, Cu and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in an activated Ni catalyst containing 4.7 wt % Al, 1.66% Cr, 0.08% Cu and 0.26 wt % Fe. This catalyst had an APS value of 22 μm. This catalyst was used for the batch hydrogenation of nitrobenzene to aniline as described in application example 2. The nitrobenzene hydrogenation activity of this catalyst was found to be 103 ml H2/min/gram of catalyst (please see table 1).
Example 7
An alloy containing Ni, Al, Cr, Cu and Fe was activated in an aqueous 20 wt.-% NaOH suspension between 100 and 110° C. resulting in an activated Ni catalyst containing 4.5 wt % Al, 1.35% Cr, 0.17% Cu and 0.26 wt % Fe. This catalyst had an APS value of 20 μm and was tested for the formation of takovite as described in application example 3. The ratio of the sum of the takovite x-ray diffraction peak heights at 12, 24, 35, 40 and 47 °2 theta to the nickel x-ray diffraction peak height at 52 °2 theta was found to be 5.6. The individual takovite-to-nickel ratios of the x-ray peaks at 12, 24, 35, 40 and 47 °2 theta can be seen in table 2. This catalyst was used for the batch hydrogenation of nitrobenzene to aniline as described in application example 2. The nitrobenzene hydrogenation activity of this catalyst was found to be 92 ml H2/min/gram of catalyst (please see table 1). As described in application example 1, 300 milligrams of this catalyst were used for the pulse hydrogenation of dinitrotolunene to toluenediamine. The selectivity of this reaction was greater than 99.5% toluenediamine and the activity data points are given below in table 11 and graph 2







TABLE 11







The dinitrotoluene hydrogenation data for example 7.











Hydrogenation Activity



grams TDA yielded
ml H2 per minute



per gram of catalyst
per gram of catalyst














22
3945



43
3608



65
3518



87
3380



110
3186



132
3038



154
3000



177
2835



200
2775



223
2585



245
2574



268
2341



290
2491



314
2262



336
2280



360
2181



383
1986



405
1778



429
1707










The results shown in the above examples clearly demonstrate that the present invention is well adapted to carry out the objectives and attain the ends and advantages mentioned as well as those inherent therein. While increasing the Al content of the catalyst enhances its activity, it can also increase the amount of takovite produced during the hydrogenation of nitro-compounds such as dinitrotoluene. Hence in the past, one had to select between either higher activity and the increased presence of takovite, or less catalyst activity (with lower Al contents) and less takovite. Stabilizing the Al in the catalyst by the inventions of this patent will allow the practitioner of nitro-compound hydrogenation to have both high activity and less takovite. Application example 3 describes how we determined the ability of the catalyst to form takovite and the ratio of the sum of takovite °2 theta peak heights to the Ni 52 °2 theta peak height normalizes this measurement with respect to the XRD measured Ni quantity and this value is referred to here as the takovite propensity. To compare the takovite propensities of catalysts containing different Al contents one should then divide the takovite propensity by the wt. % Al to determine the relative amount of Al in the catalyst that is leachable with a amino compounds such as toluenediamine (TDA) to form takovite. Another aspect is the activity of the catalyst. If the catalyst is highly active, one would need less of this catalyst to form the same amount of the desired amine. Hence the most important aspect of the takovite propensity is the relative amount of takovite formed with respect to catalyst activity and the wt. % Al. Since the dinitrotoluene hydrogenation experiments measured here go to a minimum of  ̃350 grams of toluenediamine produced per gram of catalyst, we took the average activity up to 350 grams of toluenediamine per gram of catalyst as the standard comparison for our catalysts and this together with the relative amount of takovite formed with respect to activity and Al content are listed in table 12. One can see from the data that the incorporation of Cu into a Ni/Al alloy prior to activation with and without additional doping elements added by either adsorption or alloy addition can surprisingly lead to a catalyst that has a high activity and forms a low amount of takovite with respect to activity and Al content.







TABLE 12







The comparison of takovite formation with respect to Al


content and pulse dinitrotoluene hydrogenation activity.


















Average




Relative amount





Activity




of Takovite





to 350 g


Ratio of
Relative
with respect



Doping
APS
TDA per

Sum
Takovite:Ni
Activity
to wt % Al


Catalyst
elements
μm
g cat
wt. % Al
Takovite:Ni
to wt. % Al
to CE2
and Activity


















CE1
Cr, Fe
35
379
8.8
50.2
5.70
0.24
24.08


CE2
Fe
28
1599
4
4.7
1.17
1.00
1.17


CE3
Cr, Fe
29
2709
6.29
20.9
3.33
1.69
1.96


E1
Cr, Fe,
27
3414
5.04
10.4
2.06
2.14
0.97



Cu


E2
Cr, Fe,
26
2435
4.63
6.3
1.35
1.52
0.89



Cu


E3
Fe, Cu
28
2190
3.81
3.4
0.90
1.37
0.66


E4
Cr, Fe,
22
3292
3.9
3.7
0.96
2.06
0.46



Cu


E5
Cr, Fe,
22
2487
4.3
4.3
0.99
1.56
0.64



Cu


E7
Cr, Fe,
20
2875
4.5
5.6
1.24
1.80
0.69



Cu









While modification may be made by those skilled in the art, such modifications are encompassed within the spirit of the present invention as defined by the disclosure and the claims.

## Claims

1. A catalyst comprising a Ni/Al alloy doped with Cu and Fe wherein:
a) said Ni/Al alloy doped with Cu and Fe has been activated;
b) Cu and Fe are each present in the activated catalyst at 0.01 wt % to 10 wt %;
c) Al is present in the activated catalyst at 0.05 wt % to 10 wt %.

2. The catalyst of claim 1, wherein said Ni/Al alloy is further doped with Cr and said Cr is present in the activated catalyst at 0.01 wt % to 10 wt %.

3. The catalyst of claim 2, wherein the activated catalyst comprises between 0.01 wt % and 2.4 wt % of Cr and between 0.01 wt % and 1.9 wt % of Fe.

4. The catalyst of claim 1, wherein said Ni/Al alloy is further doped with one or more additional doping elements selected from the group consisting of: Mg, Ti, V, Mo, Co, Pd and Pt, and where one or more additional doping elements are present in the activated catalyst at 0.01 wt % to 10 wt %.

5. The catalyst of claim 4, wherein said Ni/Al alloy is further doped with Cr and said Cr is present in the activated catalyst at 0.01 wt % to 10 wt %.

6. The catalyst of claim 1, further comprising one or more postactivation doping elements selected from the group consisting of: Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au, adsorbed to the surface of the activated catalyst, wherein each of said postactivation doping elements is present in the activated catalyst at 0.01 wt % to 10 wt %.

7. The catalyst of claim 6, wherein said Ni/Al alloy is further doped with Cr and said Cr is present in the activated catalyst at 0.01 wt % to 10 wt %.

8. The catalyst of claim 1, wherein said Ni/Al alloy is further doped with one or more additional doping elements selected from the group consisting of: Ce, W, Mn, Re, Ir, Ru, Rh and Bi, and where said one or more additional doping elements are present in the activated catalyst at 0.01 wt % to 10 wt %.

9. The catalyst of claim 8, wherein said Ni/Al alloy is further doped with Cr and said Cr is present in the activated catalyst at 0.01 wt % to 10 wt %.

10. The catalyst of claim 8, further comprising one or more postactivation doping elements selected from the group consisting of: Mg, V, Cr, Mo, Fe, Co, Pd, Pt, Cu and Au, adsorbed to the surface of the activated catalyst, wherein each of these doping elements is present in the activated catalyst at 0.01 wt % to 10 wt %.

11. The catalyst of claim 10, wherein said Ni/Al alloy is further doped with Cr and said Cr is present in the activated catalyst at 0.01 wt % to 10 wt %.

12. A method for the hydrogenation of a nitro-compound, comprising reacting said nitro compound with hydrogen in the presence of the catalyst of claim 1.

13. The method of claim 12, wherein said nitro-compound is a nitrated aromatic.

14. The method of claim 13, wherein said hydrogenation of said nitro-compound is carried out continuously.

15. The method of claim 12, wherein said Ni/Al alloy in said catalyst is further doped with Cr and said Cr is present in the activated catalyst at 0.01 wt % to 10 wt %.

16. The method of claim 15, wherein said nitro-compound is a nitrated aromatic.

17. The method of claim 15, wherein said hydrogenation of said nitro-compound is carried out continuously.

18. The method of claim 15, wherein the activated catalyst comprises between 0.01 wt % and 2.4 wt % of Cr and between 0.01 wt % and 1.9 wt % of Fe.

19. The method of claim 18, wherein said nitro-compound is a nitrated aromatic.

20. The method of claim 19, wherein said hydrogenation of said nitro-compound is carried out continuously.