Description TECHNICAL FIELD

This invention relates to a process for the production of polyalkylene-polyamines, the process comprising the condensation of an alkylene-diamine in the presence of hydrogen and a hetero genous catalyst comprising copper and nickel.

STATE OF THE ART

Compounds with primary or secondary amino groups are valuable intermediates in chemical synthesis. Furthermore, they are important monomers and catalysts in the technical field of pol ymers.

Polyalkylene-polyamines are of specific interest due to their high content of primary and sec ondary amino groups.

WO 2020/178219 A1 (BASF) refers to a process to produce polyalkylene-polyamines wherein an alkylene-diamine, a hydroxyalkylene-amine and hydrogen are reacted in presence of an het erogenous catalyst comprising copper.

GB 1 ,508,460 (BASF) refers to a process for the manufacture of diethylene triamine and/or tri- ethylenetetraamine by condensation of ethylenediamine using a heterogeneous catalyst com prising nickel and copper.

TECHNICAL PROBLEM

The technical problem to be solved by the present invention was to improve existing processes for the production of polyalkylene-polyamines, and to remedy one or more disadvantages of the prior art. The intention was to find a process to be performed with high space-time yield and se lectivity.

Surprisingly it has been found that the technical problem as specified above can be solved by a process for the production of polyalkylene-polyamines, the process comprising the condensa tion of an alkylene-diamine in the presence of hydrogen and a heterogenous catalyst compris ing copper and nickel. DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, an alkylene-diamine is subjected to condensation reaction. The term condensation means that two amine molecules are reacted to form a single molecule including the loss of ammonia.

Without wanting to be bound by any theory or limiting the scope of this invention in whatsoever kind, it is believed, that the polyalkylene-polyamines according to the present invention are formed as follows. First, two alkylene-diamine molecules undergo a condensation reaction (in cluding the loss of ammonia) to obtain a di-alkylene-triamine that can also be referred to as a dimer. Such di-alkylene-triamine or dimer can undergo a condensation reaction with another al kylene-diamine molecule (including the loss of ammonia) to form a tetra-alkylene-triamine that can also be referred to as trimer. In a similar manner respective tetramers and higher conden sation products can be formed. It of course also possible that a dimer undergoes a condensa tion reaction with another dimer, trimer etc. (in each case including the loss of ammonia).

The alkylene-diamine is preferably a low molecular weight compound with a molecular weight of at maximum 500 g/mol.

Preferably, the alkylene-diamine does not comprise other atoms than hydrogen, carbon and ni trogen and does not comprise other amino groups than the two primary amino groups.

Preferably the alkylene-diamine is a compound of formula I

H2N-X-NH2 with X representing a linear or branched, the latter being preferred, alkylene group with 2 to 10 carbon, notably 2 to 6, 3 to 6 or even 3 to 4 carbon atoms.

The processes according to the present invention is particularly suited for the condensation of branched alkylene-diamines as it helps to control undesired ring-formation. In principal, ring-for mation is accelerated when the linking chains between the reactive sides bear alkyl substituents (this is also referred to as Thorpe-lngold effect) thus posing a greater problem for the condensa tion of branched alkylene-diamines. Ring-formation is further explained below in more detail for the condensation of 1,2-propanediamine. The process according to the present invention allows for the production of polyalkylene-polyamines with considerable low amounts of cyclic amines, like for example DM-Pip (as defined below), being formed.

Among branched alkylene-diamines, an alkylene diamine of formula II as follows is preferred: wherein

R ¹ , R ² , R ³ , R ⁴ independently of each other mean H or Ci- to C4-alkyl, further provided that the amount of carbon atoms in the alkylene-diamine does not exceed 10 and at least one of R ¹ to R ⁴ is not H.

Preferably R ¹ , R ² , R ³ , R ⁴ independently of each other mean H, Methyl or Ethyl, further provided that at least one of R ¹ to R ⁴ is not H.

In a preferred embodiment the alkylene-diamine is selected from the group consisting of 1,2- propanediamine (1,2-PDA as further described below), butane-2, 3-diamine, hexane-3, 4-dia- mine, butane-1, 2-diamine, 2-methylpropane-1, 2-diamine.

A specifically preferred alkylene-diamine is 1,2-propanediamine (1,2-PDA) of formula III

The condensation of alkylene-diamine results in a polyalkylene-polyamine or a mixture of poly- alkylene-polyamines.

The term “polyalkylene-polyamine” means a compound with at least two alkylene groups and at least three amino groups selected from primary or secondary amino groups. Preferred poly- alkylene-polyamines comprise 2 to 10 alkylene groups and 3 to 11 amino groups selected from primary or secondary amino groups. The molecular weight of the polyalkylene-polyamines is preferably lower than 1000 g/mol more preferably lower than 700 g/mol.

A preferred embodiment of the present invention is the production of dimethyl-diethylene-tri- amine (DM-DETA) and trimethyl-triethylene-tetraamine (TM-TETA), the process comprising the condensation of 1,2-propylenediamine (1,2-PDA). In this case the dimethyl-diethylene-triamine is selected from:

N ¹ - 2-aminGpropyI)propane-1 , 2-diamine NMl-aminopropan-2-yl)piOpane-1, -diamine

N ^x -(1 -aminopropan-2-yl)propane-1 ,2-diamine or any mixture thereof.

The compounds of N ¹ -(2-aminopropyl)propane-1, 2-diamine, N ¹ -(1-aminopropan-2-yl)propane- 1 , 2-diamine and N ² -(1-aminopropan-2-yl)propane-1 ,2-diamine (including their respective stereo- isomers) or any mixture thereof are herein collectively referred to as dimethyl-diethylene-tri- amine (shortly DM-DETA).

The dimethyl-diethylene-triamines obtained may be starting material for a subsequent conden sation reaction with another 1,2-PDA, thus obtaining a further isomeric mixture comprising, for example, a trimethyl-triethylene-tetraamine of formula

L/ ¹ ,/V ^{1 '} -(propane- 1 ,2-diyl)bis(propane-1 ,2-diamine) or any structural- and stereoisomers thereof. Any respective isomer as well as any mixture thereof is herein collectively referred to as trimethyl-triethylene-tetraamine (shortly TM-TETA). Higher amines, like for example tetramethyl-tetraethylene-pentaamine or pentamethyl-penta- ethylene-hexaamine (including their respective structural- and stereoisomers), may also be ob tained, but usually only in small amounts.

Via intramolecular condensation of DM-DETA dimethyl-piperazine of the following formulas (in cluding their respective stereoisomers)

2,5-dimethylpiperazine 2,6-dimethylpiperazine

(shortly DM-Pip) is obtained as an undesired by-product. The process according to the present invention allows for the production of DM-DETA and TM-TETA with considerable low amounts of DM-Pip being formed.

In a preferred embodiment, the reaction conditions, particularly 1,2-propanediamine conversion and liquid hourly space velocity, are adjusted to obtain a mixture of polyalkylene-polyamines that comprises at least 50 % by weight, preferably at least 60 % by weight, more preferably at least 70 % by weight of DM-DETA, based on all polyalkylene-polyamines.

Furthermore, the dimethyl-diethylene-triamines obtained are preferably an isomeric mixture of 1 to 49 % by weight of N ¹ -(2-aminopropyl)propane-1, 2-diamine,

50 to 98 % by weight of N ¹ -(1-a inopropan-2-yl)propane-1, 2-diamine and 1 to 49 % by weight of N ² -(1-aminopropan-2-yl)propane-1, 2-diamine based on 100 % by weight of dimethyl-diethylene-triamines.

The process according to the present invention uses a heterogenous catalyst comprising copper and nickel, preferably a heterogenous catalyst, the catalyti cally active material of which, before the reaction thereof with hydrogen comprises oxygen-containing compounds of copper, oxygen-containing compounds nickel and another oxidic material.

The oxidic material is preferably an oxidic support or an oxidic binder.

Preferably the catalytically active material of the catalyst, before the reaction thereof with hydrogen, comprises

20 to 80 % by weight of oxygen-containing compounds of nickel, calculated as NiO,

5 to 30 % by weight of oxygen-containing compounds of copper, calculated as CuO,

0 to 50 % by weight of oxygen-containing compounds of cobalt, calculated as CoO,

5 to 75 %, preferably 5 to 70 % or even 5 to 65 % by weight of another oxidic material.

More preferably the catalytically active material of the catalyst, before the reaction thereof with hydrogen, comprises

25 to 75 % by weight of oxygen-containing compounds of nickel, calculated as NiO,

10 to 30 % by weight of oxygen-containing compounds of copper, calculated as CuO,

0 to 40 % by weight of oxygen-containing compounds of cobalt, calculated as CoO,

10 to 65, preferably 10 to 55 % or even 10 to 50 % by weight of another oxidic material.

Even more preferably the catalytically active material of the catalyst, before the reaction thereof with hydrogen, comprises

35 to 75 % by weight of oxygen-containing compounds of nickel, calculated as NiO,

10 to 30 % by weight of oxygen-containing compounds of copper, calculated as CuO,

0 to 40 % by weight of oxygen-containing compounds of cobalt, calculated as CoO,

10 to 55, preferably 10 to 50 % or even 10 to 45 % by weight of another oxidic material.

As mentioned above, the oxidic material is preferably an oxidic binder or an oxidic support.

Suitable oxidic materials are, for example, calcium carbonate (calculated as CaCCh), oxygen- containing compounds of silicon (calculated as S1O ₂ ), oxygen-containing compounds of zirconium (calculated as Zr0 ₂ ) or oxygen-containing compounds of aluminum (AI ₂ O ₃ ) including mixtures thereof, preferably oxygen-containing compounds of aluminum (calculated as AI ₂ O ₃ ) or oxygen-containing compounds of zirconium (calculated as ZrC>2) including mixtures thereof, more preferably the oxidic material is an oxygen-containing compound of zirconium (calculated as Zr0 ₂ ).

Preferably the catalytically active material of the catalyst, before the reaction thereof with hydro gen, comprises 0 to 35 %, more preferably 0 to 30 %, even more preferably 0 to 14 %, 0 to 9 %, 0 to 5 % or 0 to 2 % by weight oxygen compounds-containing of cobalt, calculated as CoO. The catalyst may be also essentially free of oxygen-containing compounds of cobalt, meaning that their amount is less than 0.1 % by weight.

The catalyst is preferably used in the form of a catalyst which consist only of catalytically active material and, if appropriate, a shaping assistant (for example graphite or stearic acid) if the cat alyst is used as a shaped body, i.e. do not comprise any further catalytically active ingredients. In this connection, the support or binder is included in the catalytically active material. The cata lysts are used in such a way that the catalytically active material ground to powder is introduced into the reactor or that the catalytically active material, after grinding, mixing with shaping assis tants, shaping and heat treatment, is arranged in the reactor as shaped catalyst bodies - for ex ample as tablets, spheres, rings, extrudates (e.g. strands).

The concentration figures (in % by weight) of the components of the catalyst are based in each case, unless explicitly stated otherwise, on the catalytically active material of the finished cata lyst after its last heat treatment and before its reduction with hydrogen.

The catalytically active material of the catalyst, after its last heat treatment and before its reduc tion with hydrogen, is defined as the sum of the masses of the catalytically active constituents and of the abovementioned catalyst support or binder materials, and preferably comprises es sentially the following constituents:

Support or binder, oxygen compounds of copper, of nickel and where applicable of cobalt.

The sum of the abovementioned constituents of the catalytically active material is for example from 70 to 100% by weight, preferably from 80 to 100% by weight, more preferably from 90 to 100% by weight, particularly > 95% by weight, very particularly > 98% by weight, in particular > 99% by weight, for example more preferably 100% by weight.

The catalytically active material of the catalyst may also comprise one or more elements (oxida tion stage 0) or their inorganic or organic compounds selected from groups I A to VI A and I B to VII B and VIII of the Periodic Table of the Elements.

Examples of such elements and compounds thereof are: transition metals such as Mn or Mn0 ₂ , W or tungsten oxides, Ta or tantalum oxides, Nb or nio bium oxides or niobium oxalate, V or vanadium oxides or vanadyl pyrophosphate; lanthanides such as Ce or Ce0 ₂ or Pr or Pr ₂ C>3; alkaline earth metal oxides such as SrO; alkaline earth metal carbonates such as MgCCh, CaCCh and BaCCh; boron oxide (B ₂ C>3). The catalytically active material of the catalyst preferably does not comprise any rhenium, any ruthenium, any iron and/or any zinc, in each case either in metallic (oxidation state = 0) form or in an ionic (oxidation state ¹ 0), especially oxidized, form.

The catalytically active material of the catalyst preferably does not comprise any silver, either in metallic (oxidation state = 0) form or in an ionic (oxidation state ¹ 0), especially oxidized, form.

The catalytically active material of the catalyst, before the reaction thereof with hydrogen, may further comprise small amounts of oxygen-containing compounds of tin (calculated as SnO). For example, 0.2 to 5 %, particularly 0.4 to 4.0 %, more particularly in the range from 0.6 to 3.0 % or even more particularly 0.7 to 2.5 % by weight oxygen-containing compounds of tin (calculated as SnO).

The catalytically active material of the catalyst, before the reaction thereof with hydrogen, may further comprise small amounts of oxygen-containing compounds of molybdenum (calculated as M0O3). For example, 0.1 to 5 %, preferably from 0.5 to 3.5 % by weight oxygen-containing com pounds of molybdenum (calculated as M0O3). The catalytically active material of the catalyst may also be essentially free of oxygen-containing compounds of molybdenum, meaning that their amount is less than 0.1 % by weight.

In the particularly preferred embodiment, the catalytically active material is not doped with fur ther metals or metal compounds. Preferably, however, typical accompanying trace elements originating from the metal extraction of Cu, Ni and, where applicable, Co, Sn and Mo, are ex cluded therefrom.

In a very preferred embodiment, the catalytically active material of the catalyst, before the reac tion thereof with hydrogen, comprises

20 to 80 %, preferably 20 to 70 % or even 20 to 60 % by weight of oxygen-containing com pounds of nickel, calculated as NiO,

5 to 30 %, preferably 10 to 30 % or even 10 to 25 % by weight of oxygen-containing compounds of copper, calculated as CuO,

0 to 50 %, preferably 10 to 40 % or even 15 to 35 % by weight of oxygen-containing compounds of cobalt, calculated as CoO,

0 to 5 %, preferably 0.2 to 5 % or even 0.7 to 2.5 % by weight of oxygen-containing compounds of tin, calculated as SnO,

5 to 75 %, preferably 5 to 55 % or even 5 to 50 % by weight of oxygen containing compounds of aluminum (calculated as AI ₂ O ₃ ).

In another very preferred embodiment, the catalytically active material of the catalyst, before the reaction thereof with hydrogen, comprises 20 to 80 %, preferably 30 to 70 % or even 40 to 60 % by weight of oxygen-containing compounds of nickel, calculated as NiO,

5 to 30 %, preferably 10 to 30 % or even 10 to 25 % by weight of oxygen-containing compounds of copper, calculated as CuO,

0 to 5 %, preferably 0 to 4 % or even 0.5 to 3.5 % by weight of oxygen-containing compounds of molybdenum (calculated as M0O ₃ ),

5 to 75 %, preferably 5 to 65 % or even 5 to 55 % by weight of oxygen containing compounds of zirconium (calculated as ZrC>2).

In such very preferred embodiment, the amount of oxygen-compounds of cobalt (calculated as CoO) is preferably less than 2 % by weight, even more preferably is essentially free of oxygen- containing compounds of cobalt, meaning that their amount is less than 0.1 % by weight.

To prepare the catalysts used in the process according to the invention, various processes are possible. They are, for example, obtainable by peptizing pulverulent mixtures of the hydroxides, carbonates, oxides and/or other salts of the components with water and subsequently extruding and heat-treating the material thus obtained.

The preparation of catalysts is well known in the art and described for example in WO 2011/067199 A1, EP 696572 A, EP 1 106600 A2 and EP 0963975 A1 (all BASF).

The catalyst can be used for example as a suspension or as a fixed bed catalyst. Preferably the catalyst is arranged as a fixed bed in the reactor. It is possible for the flow toward the fixed catalyst bed to be either from the top or from the bottom.

The process can be performed continuously or batchwise. In a batch process the entire amount of the alkylene-diamine to be reacted is added to the reactor. In a continuous process the al- kylene-diamine is continuously fed into and products are continuously withdrawn from the reactor. Preferably the process is conducted continuously.

In a batch process, the catalyst is preferably used in an amount of 0.1 to 10 parts by weight per 100 parts by weight of alkylene-diamine. Hydrogen is added until the desired reaction pressure (as further specified below) is achieved. Preferably, the batch condensation reaction is carried out in a stirred tank reactor. More preferably, the reaction is carried out in a stirred tank reactor where the generated ammonia is continuously removed from the reactor.

In a continuous process, the liquid hourly space velocity is usually in the range from 0.05 to 5 kg, preferably 0.1 to 2 kg and more preferably 0.3 to 1.0 kg of alkylene-diamine per litre of catalyst (bed volume) and hour. The flow rate of fresh hydrogen usually amounts to 100 bis 1000 NL/L catalyst/h, preferably 150 bis 550 NL/L catalyst/h. “NL” means standard litres, i.e. volume converted to standard conditions (S.T.P.) Preferably, the condensation is conducted in a tubular reactor, reactors with external or internal recirculation, plug flow reactors or spray reactors. In a preferred embodiment, the conversion is carried out in a tubular reactor. It is possible to use for example a tube bundle reactor or a sin gle-stream plant. In a single-stream plant, the tubular reactor can consist of a series connection of a plurality of individual tubular reactors.

The condensation is usually carried out at a conversion of the alkylene-diamine, which is not more than 30 %, preferably not more than 25 %, in particular in the range from 5 to 25 % or even 9 to 22 %. The conversion refers to the molar amount of the respective alkylene-diamine being consumed during the condensation.

Such low conversion results in a reaction product that consists of a high amount of respective di- and trimers. The amount of respective tetramers and higher condensations products is con siderably low.

The person having ordinary skill in the art knows, that the conversion of the alkylene-diamine depends on various reaction parameters, such as temperature, pressure, reaction time (batch process) or the liquid hourly space velocity (continuous process).

The condensation is usually carried out at a reaction temperature in the range from 80 to 350°C, particularly 100 to 300°C, preferably 110 to 200°C, more preferably 120 to 190°C.

The condensation is usually carried out at an absolute pressure in a range from 1 to 300 bar, preferably 10 to 200 bar, particularly preferably 20 to 120 bar or even 30 to 110 bar.

It is to be understood that the condensation reaction according to the present invention is pref erably conducted in the absence of any other starting material, including but not limited to any amino-alcohols (e.g. hydroxy-alkylene-amines), that may react with the alkylene-diamine. In particular, the molar ratio of alkylene-diamine to any other respective starting material is less than 1 : 0.1, 1 : 0.01 or even 1 : 0.001.

The reaction may be monitored via gas chromatography. The yield of product obtained corre sponds to the area of the corresponding peak compared to the area of all peaks.

The crude reaction mixture may be purified by standard methods, preferably by distillation at re duced pressure, in order to separate off ammonia (formed during the condensation), unreacted alkylene-diamine and by-products, in particular piperazine derivatives.

In case of the production of dimethyl-diethylene-triamine (DM-DETA) and trimethyl-triethylene- tetraamine (TM-TETA) (via condensation of 1,2-propylenediamine (1,2-PDA) as further speci fied above) and after distillation (preferably as described in the preceding paragraph) of the resulting crude reaction mixture, the polyalkylene-polyamines thus obtained usually have a composition as follows:

50 to 70, preferably 50 to 65 by weight DM-DETA,

30 to 50, preferably 35 to 50 by weight TM-TETA, such polyalkylene-polyamines preferably consisting of more than 95, particularly more than 97 or even more particularly more than 99 % by weight of DM-DETA and TM-TETA.

The weight percentages are based on all polyalkylene-polyamines.

In a very preferred embodiment such polyalkylene-polyamines consists of about 60 % by weight of DM-TETA, about 40 % by weight of TM-TETA and less than 1 % by weight of higher poly alkylene-polyamines such as tetramethyl-tetraethylene-pentaamine or pentamethyl-pentaethylene- hexaamine.

The following examples only serve for the purpose of the illustration of the present invention and shall therefore not limit it in whatsoever kind.

EXAMPLES Preparation of catalysts:

The catalysts were prepared as follows:

The catalyst as per Comparative Example 1 was prepared in accordance with the preparation of catalyst 3 of WO 2007/036498 A1.

The catalysts as per Examples 2 and 3 were prepared in accordance with the preparation of catalyst A of EP 696 572 A1, the amounts of nickel nitrate, copper nitrate, zirconium acetate and, in case of Example 2, ammonium heptamolybdate were adapted accordingly.

The catalyst as per Example 4 was prepared in accordance with Example 5 of WO 2011/067199 A1 , the amounts of nickel nitrate, copper nitrate, cobalt nitrate, tin chloride and aluminum oxide powder were adapted accordingly.

The composition of the respective catalysts prior to reduction with hydrogen was as further specified in table 1 : Table 1: Composition of catalysts

* Catalyst composition in % by weight; remainder up to 100% by weight is the support ** Corresponds to the catalyst as used in Example 1 of GB 1 ,505,460.

Examples 1 to 4 - Production of DM-DETA and TM-TETA:

80 g 1,2-propanediamine and 15 g of the fixed bed catalyst in reduced and passivated form in a catalyst basked were transferred to a laboratory autoclave (300 ml_ volume) under a nitrogen atmosphere. At room temperature, the pressure was increased to 10 bar by injecting hydrogen into the autoclave. Then, the autoclave was heated to the desired reaction temperature. Upon reaching the desired reaction temperature, the pressure was increased to 50 bar by injecting further hydrogen into the autoclave. Upon reaching 50 bar, the reaction mixture was stirred for eight hours. Thereafter, the reaction mixture was cooled to room temperature and the autoclave was depressurized with nitrogen gas. The reaction mixture was analyzed by gas chromatog raphy.

The results are presented in table 2 below.

able 2 - Results

Discussion of results:

Using a catalyst according to the invention (see Examples 2 to 4) results in an improved ratio of DM-DETA to DM-PIP (see last column of table 2). Thus, the selectivity of value product DM- DETA as compared to DM-PIP can be improved. The same also applies with respect of the combined selectivity of both values products DM-DETA and TM-TETA with respect to DM-PIP.

For the person having ordinary skill in the art, these results were surprising at least for the fol lowing reasons. According to the literature, the catalyst as per Comparative Example 1 is explic itly suited for condensation of diamines (see GB 1,505,460). The types of catalyst as per Exam- pies 2 to 4 are reportedly suited for the amination of alcohols (see WO 2011/067199 A1 and EP 696 572 A1). There is no mention, that these catalysts are also suited for the condensation of diamines. Therefore, it was surprising to find that even better results are obtained using the catalysts according to the invention as compared to the results obtained using a catalyst ac cording to GB 1,505,460.