Activated Base Metal Catalysts

The invention concerns an activated base metal catalyst, and its use for the hydrogenation of nitro-compounds .

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 10 ² to 10 ⁶ 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 ⁰ 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 Bl) 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 m ² /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 .

US patent 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.

US patent 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.

US patent 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.

US patent 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 US patent 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 US patent 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 nitrocompounds, 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 US patent 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.

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 verson 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 ⁰ C and pressures ranging from atmospheric pressure to 200 bar. The preferred reaction conditions are within the ranges of 50° to 180 ⁰ C and 3 to 80 bar. This reaction can be performed in an excess of hydrogen or under a stoichiometric amount of hydrogen.

In US patent 6,423,872, the reaction conditions for the continuous hydrogenation of DNT were 20 bar hydrogen at 150 ⁰ 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 US patent 3,935,264, the hydrogenation of DNT was performed with methanol as a solvent under the pressure of 28.5 bar hydrogen and 120 ⁰ C over the activated Ni catalyst.

Recently in US patent 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. US patent 4224249 also showed this to be true as a Raney-type Ni catalyst was successfully used at 130 ⁰ 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 ⁰ 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.

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 US patent 4224249, US patent 6423872 and US Patent 6005143.

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 ⁰ 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 ⁰ 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 ⁰ C to keep the DNT molten. A Buchi 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 9.1wt% 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 H ₂ / 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) .

US Patent 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 ⁰ 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 ⁰ 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 (CEl) 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 ⁰ 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 per gram of Hydrogenation Activity catalyst ml H ₂ per minute per 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 ⁰ 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 per gram of Hydrogenation Activity ml H ₂ 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 ⁰ 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 per gram of Hydrogenation Activity ml H ₂ 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 ⁰ 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.

grams TDA yielded per gram of Hydrogenation Activity catalyst ml H ₂ per minute per 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 ⁰ 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.

grams TDA yielded per gram of Hydrogenation Activity catalyst ml H ₂ per minute 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 ⁰ 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.

grams TDA yielded per gram of Hydrogenation Activity catalyst ml H ₂ per minute 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 ⁰ 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 H ₂ / 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.

grams TDA yielded per gram of Hydrogenation Activity catalyst ml H ₂ per minute 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 ⁰ 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 H ₂ / 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.

grams TDA yielded per gram of Hydrogenation Activity catalyst ml H ₂ per minute 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 ⁰ 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 H ₂ / 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 ⁰ 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 H ₂ / 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.

grams TDA yielded per gram of Hydrogenation Activity catalyst ml H ₂ per minute 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 . %A1 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 . %A1. 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.

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 .