The present invention concerns a process for the catalyzed reaction of CO and hh with a catalytic complex containing a transition metal as a central ion and at least one lewis basic ligand together with a nucleophile promoter to the product methanol.

Methanol is a chemical with the formula CH3OH (a methyl group linked to a hy droxyl group, often-abbreviated MeOH). It is a key component of the chemical industry. Not only it can be used as a fuel component, but also as a basic building block in chemical industries with a production volume of >100 million metric tons in 2018.

A disadvantage in all known reaction mechanisms, however, is that the reaction must be carried out under relatively harsh conditions, especially above 250 °C and high pressures of over 100 bar. This makes current processes very energy intense, which is problematic from both an economic and environmental point of view. By reducing energy consumption, opex and carpex can reduce costs and improve the sustainability of the process.

The invention is, therefore, based on the task of providing a process for the pro duction of methanol, the energy requirement of which is significantly lower than that of the process known from the state of the art.

This task is solved by a procedure with the characteristics of claim 1.

Such a process converts CO and H2 from a catalytic complex having a transition metal as central ion and a lewis base ligand. The reaction also takes place in the presence of a nucleophile promoter. In this invention, a conceptually novel approach to the hydrogenation of carbon monoxide is disclosed. This process involves the capture of CO and transfor mation of CO by a promoter under a Fh containing atmosphere into a formamide or methyl formate and subsequent hydrogenation of the resulting intermediate in one process step i.e. to methanol. CO fixation can be achieved with various nu cleophilic promoters like amines and nitrogen heterocycles. As for hydrogenolysis of the amides or methyl formate it can be promoted with Mn, Fe, and Ru.

The potential reaction path is described as following:

Fig.1 Reaction scheme for a reaction according to the invention

December 10, 2019 C 1 15 P 1 WO 1. CO addition to the metal-ion

2. Lewis base assisted X-H bond split of the promoter and addition to CO followed by an elimination of the carbonylated H-X as H-CO-X

3. Elimination of H-CO-X

4. Hydrogenation of H-CO-X by the catalyst

5. Elimination of formaldehyde

6. Hydrogentation of formaldehyde to methanol

In this reaction path the active center of the catalyst M-LB and the promoter X-H is crucial for the reaction.

The key discovery which enables the methanol synthesis was to find an appropri ate catalyst and promoter combination, which would be compatible with CO and produce methanol under an H2 containing atmosphere. Thus, in the initial stage of this study the effectiveness of various transition metal lewis basic ligand com plexes to cleave amides to amine and methanol, or esters to alcohole with H2/CO mixtures was investigated.

It is essential for the invention that the whole reaction takes part with one mixture and does not require temporally and/or locally separated steps.

Moreover, the process can be performed as a batch process or as a continuous process.

It is possible to have additional compound in the reaction mixture, particularly CO2. This enables the use of synthesis gas from different sources, like reverse water-gas shift reaction, without any cleaning steps. The catalyst is a metal catalyst with the lead structure M-LB, where M is a metal ion and LB is the center of the at least one lewis base. In its simplest form the catalyst can be described as M _x N _y (x = 1 -4, y = 1 -2) which is depicted in fig. 2:

LB

M

Fig. 2

In this easiest form the catalyst is typically a solid compound without any ligand.

However, also metal organic complexes as shown in fig. 3 are possible, whereby M is a metal ion and LB is the center of the at least one lewis base. R is at least one ligand comprising at least one atom selected from a group comprising N, P, O or S. In this var iant, LB contains least one atom selected from a group comprising N, P, O, S or C, in dependent from the atom of the ligand. R and LB can be linked for example by a C2 (- C2H4-) or C3 (-C3H6-) chain. Chelating ligands are particularly preferred. According to this scheme (Fig. 3) the ligand could also be ortho-Aminoaniline.

Fig. 3

Fig. 4 shows an other metal organic complexes with two different ligands. According to this scheme, the ligand could also be for example an ortho-Aminoaniline derivative with a third chelating rest.

Fig. 4

Particularly preferred is a system with a metal ion selected from the group Mn, Fe, Cr, Mo, W, Re, Co, Rh, Ir, Ni and Pd a lewis base containing at least one nitrogen atom and R, R1 and/or R2 containing each at least one phosphor, nitro gen or sulfur atom.

The ligand can be a pincer type complex. It can be selected from the pincer type group of PNP, where R1 = P(iPr)2, R2 = P(iPr)2, and LB = NH. Other pincer types would be PNN, NNN, NNS or NNC, where P can be P = PPh2, PEt2 and N can be N = NH2, NEt2, Pyridine, Pyrrole, Indole, Isoindole, Imidazol, Benzimidazol, Ani line and S can be S = SMe, SEt, SPh. The transition metal is an ion selected from the group consisting of manganese, iron, molybdenum, chromium, cobalt, ruthenium rhodium, nickel or palladium, in which manganese, iron, or molybdenum in particular exhibit good capabilities. In particular, the use of manganese as a central ion shows high turnover rates (TON).

It is also preferred that the procedure takes place in the presence of a base, which further enables a stabilization of the coordination at the central ion and/or depro tonation. In particular, it has been found that hydroxide and/or the alkali oxide of at least one of the elements Lithium, Sodium, Potassium or Calcium can be used. It was found that the promoter plays an important role in the CO hydrogenation process. In particular, promoters such as primary, secondary amines, primary anilines, and nitrogen heterocycles: pyrroles, indoles, imidazoles, carbazoles, benzimidazoles have been found active.

Promoters that show TON higher than 50, are of particular interest, since they indicate that the amount of methanol produced exceeds the amount nitrogen-pro moter. The most efficient promoters are secondary anilines, pyrroles, indoles and carbazoles.

In principle, the following promoters were tested successfully:

 It has also been shown that a ratio r1 between promoter and base between 1 : 1 and 3: 1 and/or a ratio r2 between base and catalyst between 25: 1 and 100: 1 is particularly favorable. The highest turnover rates were found here.

In addition, it has proved to be particularly advantageous to carry out the process at a temperature below 160 °C. The temperature of the sample is therefore below 160 °C. This allows further energy savings.

It is advantageous that the reaction takes place in weak coordinating (to the cat alyst) or a non-polar solvent. Cyclohexane is particularly preferred here. This re liably prevents interactions with the active center of the catalyst.

CO and Fh are both introduced into the process preferably at a partial pressure between 0.1 and 50 bar. CO with a pressure between 0.1 and 25 bar, hydrogen with a pressure between 30 and 50 bar is introduced into the system in particular. Increasing the pressure of the hydrogen slightly above that of the CO ensures that the downstream hydrogenation actually takes place as completely as possi ble. For CO it is not necessary to increase those pressures further.

Furthermore, it is possible to carry out the reaction homogeneously catalyzed. The advantage of a homogeneous catalyzed reaction is that there are no addi tional material transport effects such as adsorption, desorption on surfaces or ad ditional restrictions due to a limited surface area.

At the same time, however, it is also conceivable to stabilize the complex accord ing to the invention on a surface and to apply a heterogeneously catalyzed reduc tion. The advantages of the reaction would be on the one hand that it corresponds to the processes used in the chemical industry, so that only the catalyst has to be replaced and the operating conditions changed, and on the other hand hydrogen catalyzed processes usually facilitate the separation of the catalyst. Methanol production from CO and H2 at a pressure between 10 and 40 bar is therefore particularly preferred, with the pressure of each component being inde pendent of that of the others. The temperature lies between 120 and 150 °C. The catalyst is present in a concentration between 1 and 10 mmol. A manganese-PNP complex is used as catalyst. In addition, 0.2 to 1 mmol aniline are used as pro moters or 0.1 to 0.5 mmol are used as base. The entire reaction is performed in cyclohexane.

The following examples show individual aspects of the invention. All the features described and/or depicted, either individually or in any combination, constitute the subject matter of the application, irrespective of whether they are depicted in the claims or referred back to them.

Further identified catalysts

According to the identified reaction path, other catalysts could be identified by quantum mechanical virtual high throughput screenings. The most important steps of the reaction are the free energy of the addition of the promoter to the carbonyl complex (Scheme step 2) and the free energy transition barrier (TS) of the elimination of the formamide (Scheme step 3).

Mn-1 Mn-2

Fe-5 Fe-6 General Procedure for the Hydrogenation of Amides with manganese complexes using CO/H ₂

A flame-dried 8 ml_ vial with a magnetic stir bar was charged with 5pmmol of Mn- 1 , 0.25 mmol of amide and 2 ml_ of dry solvent. The vial was capped with a septum and the mixture was stirred for 10 seconds. Then the reaction mixture was purged with Ar for 30 seconds and 0.125 mmol of base (t-BuOK) was added. The septum was punctured with a needle and the vial was placed in a 300 ml_ autoclave. The autoclave was purged with carbon monoxide 5 times (5-7 atm) and then pressur ized to 5-20 atm. The autoclave was connected to a hydrogen line and was filled to 50 atm overall pressure. The autoclave was placed in a preheated aluminum block and stirred at 700 rpm at 150°C for 20 h. Then the reaction was placed in ice, cooled and depressurized. The reaction vial was analyzed via GC and NMR analysis, amount of methanol and corresponding amine was determined via GC using n-hexadecane as a standard.

General Procedure for the conversion of CO/H ₂ to methanol

A flame-dried 8 ml_ vial with a magnetic stir bar was charged with 5pmmol of Mn- 1 , 0.25-6.0 mmol of promoter and 2 ml_ of dry solvent. The vial was capped with a septum and the mixture was stirred for 10 seconds. Then the reaction mixture was purged with Ar for 30 seconds and 0.125 mmol of base (t-BuOK) was added. The septum was punctured with a needle and the vial was placed in a 300 ml_ autoclave. The autoclave was purged with carbon monoxide 5 times (5-7 atm) and then pressurized to 20 atm. The autoclave was connected to a hydrogen line and was filled to 50 atm overall pressure. The autoclave was placed in a pre heated aluminum block and stirred at 700 rpm at 150°C for 20 h. Then the reaction was placed in ice, cooled and depressurized. The reaction vial was analyzed via GC and NMR analysis, the amount of methanol was determined via GC using n- hexadecane as a standard.