WO2018046323A1

WO2018046323A1 - Use of polyalkylene glycol dialkyl ethers as oxidation protection for reduced, heterogeneous catalysts

Info

Publication number: WO2018046323A1
Application number: PCT/EP2017/071483
Authority: WO
Inventors: Thomas Heidemann; Regine Helga BEBENSEE; Christian Gruenanger
Original assignee: Basf Se
Priority date: 2016-09-06
Filing date: 2017-08-28
Publication date: 2018-03-15

Abstract

The invention relates to the use of at least one polyalkylene glycol dialkyl ether of general formula (I): R₁-O-(CH₂-CHR₂O)_n-R₁, in which the substituents independently have the following designations: R₁ : C₁-C₈-alkyl; R₂ : hydrogen or methyl; n : 2 to 10, as oxidation protection for reduced, heterogeneous catalysts, particularly for reduced, heterogeneous catalysts which contain, as an active constituent, at least one element selected from the group consisting of nickel, cobalt, ruthenium, iron and copper or mixtures thereof.

Description

Use of polyalkylene glycol dialkyl ethers as oxidation protection for reduced, heterogeneous catalysts

description

The present invention relates to the use of polyalkylene glycol dialkyl ethers as oxidation protection for reduced, heterogeneous catalysts.

Many catalysts used for reactions with hydrogen are typically reduced as part of their preparation or prior to their use in industrial reactors by methods known to those skilled in the art. In order to enable safe handling of these catalysts, which are usually pyrophoric in the reduced state, it is often necessary to stabilize these metallic catalysts obtained after the end of the reduction. EP 1779928 A2 and DE 19909175 A1 describe processes for the passivation of pyrophoric catalysts by controlled after-treatment with oxygen-containing gases in the presence of CO 2, H 2 O and / or N 2. In this case, a thin oxide and / or carbonate layer is produced on the surface of the catalyst, which makes the catalyst manageable in air.

However, these processes have the disadvantage that the oxidic layer produced on the surface must be removed again before the catalyst is used by an activation process-typically after incorporation of the catalyst into a reactor-in an H2-containing gas stream at elevated temperature.

In addition, in the handling of these so-prepared catalysts is always expected with a dust formation, which makes additional measures necessary in particular in the case of carcinogenic nickel or cobalt-containing materials to exclude a burden on the environment with dusts. A wetting of the catalyst to be incorporated with water or a flow of the reactor with water is a common method for eliminating the formation of dust. A disadvantage of the water treatment is that on the one hand, the water-moist catalysts can be further oxidized (by dissolved oxygen or by the reaction yH ₂ 0 + M - M (OH) x + ZH2) or after filling in the reactor prior to their activation initially consuming to be dried in the reactor.

In the case of suspension catalysts, it has therefore been proposed, for example, in US 2006/0100452, to embed reduced catalyst powders in a waxy material. This so air-stable material is introduced before use in suitable reactors and removed the waxy protective material by melting or dissolving in suitable solvents. At the same time, the formation of dust by embedding in the waxy material is practically impossible. The embedding in waxy materials is not possible when using particulate fixed bed catalysts. In addition, when using waxes in the case of suspension catalysts, the compatibility with the respective reaction or the respective reactants must be taken into account.

It was therefore an object to find new methods for the stabilization of reduced, heterogeneous catalysts which do not have the abovementioned disadvantages.

This object has been achieved by the use of at least one polyalkylene glycol alkyl ether (also referred to below as "polyglycol ether") of the general formula I.

(I) Ri-0- (CH ₂ -CHR ₂ 0) "- R, in which the substituents independently have the following meaning:

Ri, d-Ce-alkyl,

R2 is hydrogen or methyl,

n 2 to 10, as oxidation protection for reduced, heterogeneous catalysts.

The variables listed in general formula I are defined as follows:

Alkyl radicals for R 1 are linear or branched C 1 -C 6 -alkyl chains, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, iso Pentyl, sec-pentyl, neo-pentyl, 1,2-dimethyl-propyl, iso-amyl, n-hexyl, iso-hexyl, sec-hexyl, n-heptyl, and n-octy. Preferred alkyl radicals are C 1 -C 4 -alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, particularly preferably methyl, ethyl and n-butyl. n represents an integer of not less than 2, preferably 2 to 10, more preferably 2 to 4.

Particularly preferred polyglycol ethers are the following compounds selected from the group consisting of diglyme [CH ₃ -0- (CH 2 CH ₂ 0) 2 CH 3], Proglyme [CH ₃ -0- (CH ₂ -CHCH ₃ 0) 2 - CH ₃ ], triglyme [CH ₃ -O- (CH ₂ -CH ₂ O) 3-CH ₃ ], tetraglyme [CH ₃ -O- (CH ₂ -CH ₂ O) ₄ -CH ₃ ], ethyl diglyme [C ₂ H5-0- (CH2-CH20) 2-C2H _5], butyl diglyme

Polyglyme [CH ₃ -O- (CH ₂ - CH ₂ O) n-CH ₃ ] and Higlyme [CAS 366009-01-0] or mixtures thereof. Very particularly preferred polyglycol ethers are preglyme, butyl diglyme, polyglyme and higlyme or mixtures thereof.

A further preferred embodiment of the use according to the invention is characterized in that the hydroxyl number (OHN) of the polyglycol ether is less than 100 mg KOH / g, more preferably less than 50 mg KOH / g, most preferably less than 10 mg KOH / g.

A likewise preferred embodiment of the use according to the invention is characterized in that the polyglycol ether is a compound which is in liquid form at a temperature in the range from 10 ° C. to 100 ° C. (at normal pressure).

For practical reasons, the melting temperature of the polyglycol ether is generally lower than the temperature at which the catalyst is stored prior to use. Preferably, the melting temperature of the polyglycol ether is in the range of -5 ° C to -75 ° C, more preferably in the range of -5 ° C to -60 ° C.

The melting temperature of the polyglycol ether to which the catalyst is added is preferably lower than the temperature at which the hydrogenation is carried out, so as to facilitate the separation of the polyglycol ether from the catalyst at the beginning of a hydrogenation process.

The boiling point of the polyglycol ether used in the invention is> 170 ° C, preferably in the range of 170 ° C to 280 ° C, more preferably in the range of 175 ° C to 275 ° C.

Furthermore, the polyglycol ethers used according to the invention are also distinguished by the fact that they have a flash point above 100 ° C., preferably in the range from 110 ° C. to 160 ° C. The use according to the invention of polyglycol ethers as oxidation protection generally applies to those catalysts which are suitable for chemical reactions with hydrogen as reactant, e.g. Hydrogenations or aminations are suitable. These include, for example, heterogeneous catalysts containing as active component at least one element from the group consisting of iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum or mixtures thereof. For the inventive use of polyglycol ethers heterogeneous catalysts are preferred, mentioning as the active component at least one element selected from the group consisting of nickel, cobalt, ruthenium, iron and copper or mixtures thereof, particularly preferably such catalysts, the nickel and / or cobalt contain. Of course, the catalysts may also contain other elements as promoters.

The use of the polyglycol ethers according to the invention is further characterized in that the catalyst to be protected is reduced by means of thermal treatment of its active component present in oxidic form with hydrogen. For reduction, the catalysts are purged at room temperature with nitrogen and under nitrogen atmosphere, a pressure of 2 to 10 bar, preferably 4 to 8 set bar. Subsequently, usually 2 to 30% of the nitrogen stream, preferably 5 to 15%, against hydrogen exchanged and the temperature usually within 2 to 24 h, preferably 5 to 15 h, from room temperature to 80 to 200 ° C, preferably 120 to 160 ° C, increased Then usually a further part of the nitrogen stream is replaced by hydrogen , so that a total hydrogen content of 30 to 70%, preferably 40 to 60% is achieved Subsequently, the temperature is usually within 2 to 24 hours, preferably 5 to 15 hours, to 200 to 400 ° C, preferably 250 to 350 ° C increased This final temperature is usually kept until no more reducing water is detectable in the gas stream leaving the catalyst. Subsequently, the hydrogen content in the gas stream is usually exchanged for nitrogen again and allowed to cool the reduced catalyst in a stream of nitrogen to room temperature.

It may u.a. so-called full catalysts (moldings which are completely permeated by the active component), supported catalysts (solid catalysts, consisting of the active component, which is responsible for the actual catalytic reaction, and a support material) or Raney catalysts (finely divided hydrogenation and dehydrogenation catalysts [ nickel and cobalt in particular], which are prepared by alloying the metals, for example, with aluminum, magnesium or zinc and then dissolving away the alloying metals with alkalis). Depending on the desired hydrogenation process (suspension hydrogenation, fluidized bed hydrogenation, fixed bed hydrogenation), the catalyst may be present, for example, as a powder, grit or shaped article.

If unsupported catalysts are used, the amount of active components, based on the total mass of the catalyst, is preferably 30 to 100% by weight, more preferably 50 to 99% by weight and most preferably 55 to 98% by weight. For supported catalysts, the content of the active components, based on the total mass of the catalyst, preferably 0.01 to 30 wt .-%, wherein in the case of precious metals Ru, Rh, Pd and Pt their content is more in the range 0.01 to 10 Wt .-%, preferably 0.05 to 5 wt .-%, and in the case of the remaining metals whose content is more in the range 1 to 30 wt .-%, preferably 5 to 20 wt .-%

In the case of Raney catalysts, for example, they may contain 0 to 15% by weight of aluminum and 50 to 100% by weight of nickel or cobalt.

The use according to the invention is advantageously carried out in the form of a dispersion which contains the reduced, heterogeneous catalyst as the disperse phase and at least one polyalkylene glycol dialkyl ether of the general formula I as the dispersion medium.

The amount of polyglycol ether used as the protective material in the dispersion is preferably at least 40% by weight, preferably at least 55% by weight, particularly preferably at least 60% by weight. Very good results were achieved with an amount of polyglycol ether of at least 65 wt .-%. (All wt .-% data based on the total weight of the mixture of catalyst and protective material).

The amount of polyglycol ether is preferably at most 95% by weight, preferably at most 90% by weight, particularly preferably at most 85% by weight. Very good results were with a Weight fraction of polyglycol ether used of at most 80 wt .-% achieved. (All wt .-% data based on the total weight of the mixture of catalyst and protective material).

Polyglycol ethers are to be regarded as inert solvents. Targeted adjustment of the chain lengths and alkyl fragments according to GHS (Globally Harmonized System for Classification and Labeling of Chemicals) does not require labeling of polyethers which are non-flammable as well as liquid in a wide temperature range.

After incorporation of the catalyst stabilized with polyglycol ether, the polyglycol ethers can either be expelled at elevated temperature with an inert gas stream or be dissolved out with suitable process constituents. Due to their inertness, the catalyst is in its active form after removal of the ether and can be used directly for the desired reaction without undergoing a complicated drying or activation procedure.

In the case of multi-purpose systems with high frequency of catalyst changes, it is also possible to remove the activated catalyst in each case in a reduced form from the reactor to store in the protective liquid and re-use after re-installation and removal of the protective liquid.

The present invention will be explained in more detail with reference to the following examples.

1. Catalyst Preparation a) Preparation of a NiO / CuO / CoaO SnO / A Oa-containing catalyst

According to WO 2013/072289, Example B3), a NiO / CuO / Co ₃ 04 / SnO / Al ₂ O 3 -containing catalyst was prepared. The not yet reduced, tablet-shaped catalyst was milled to a splitting fraction of 250-500 μm. A portion of the split fraction was retained (= catalyst I: oxidized), the remainder was at a temperature of 280-300 ° C in a nitrogen / hydrogen mixture (initially 1% H ₂ in N ₂ up to 50% H ₂ in N ₂ ) reduced. After cooling to room temperature under nitrogen, a portion of the reduced catalyst was transferred to a flask and reducted with 1 ml of butyl diglyme (CAS No. 1 12-73-2) per gram. Catalyst added (catalyst II: reduced / Butyldiglyme). The second part of the reduced catalyst was passivated at a maximum of 35 ° C. in dilute air (air in N ₂ with a 0 ₂ content of initially 0.1 to a maximum of 10% by volume) (= catalyst III: reduced / passivated). b) Preparation of a Co-containing catalyst

According to EP 636409 A1 (Ex. Catalyst A), a cobalt-containing catalyst was prepared in the form of 2 mm extrudates. In addition to EP 636409 A1, the cobalt catalyst was transferred to a rotary flask and heated in an N ₂ / H ₂ stream (95% / 5%) to 150 ° C, then the H2 content was gradually increased to 50%. The mixture was then carefully heated to a temperature of 280 ° C (thereby controlling that the product temperature is always <300 ° C) and reduced as long as without pressure until no more water attack in the gas discharge was detected. After cooling in the N ₂ stream to room temperature, the thus-reduced catalyst was surface passivated by controlled addition of air (starting with 5% air in N ₂ increasing to 100% air), wherein the air supply was metered so that the Temperature in the catalyst was kept below 35 ° C (= catalyst IV: reduced / passivated).

The catalyst IV described above was again transferred to a rotary flask and heated in an ISb / l-b stream (95% / 5%) to 150 ° C, then the h-portion was gradually increased to 50%. The mixture was then carefully heated further to a temperature of 280 ° C and reduced while depressurized until no more water attack in the gas discharge was detectable. After cooling in the N 2 stream to room temperature, the catalyst was mixed with butyl diglyme (2 ml per g of catalyst), placed in a container and allowed to stand for 6 months at room temperature (= catalyst V: reduced / Butyldiglyme). c) Preparation of a CoO / M ^ CVHaPCV-Containing Catalyst

According to DE 19516845 A1 (Ex. Catalyst A), a CoO / Mn ₂ O ₃ / H ₃ PO 4 -containing catalyst was prepared, ground to powder and reduced in a stream of hydrogen. After cooling to room temperature, the reduced powder was divided into several fractions under nitrogen and mixed with various protective liquids listed in Table 1 (1 ml per g of powder) (= catalyst VI: reduced / oxidation protection). Part of the reduced, dry catalyst was passivated at a maximum of 35 ° C. in dilute air (air in N ₂ with a 0 ₂ content of initially 0.1% to a maximum of 10% by volume) (= catalyst VII: reduced / passivated ).

Table 1

Oxidation protection OH groups boiling point. Flash point. [° C]

mg KOH / g [° C]

Dipropylene glycol 860 227 130

Tripropylene glycol 570 270 145

1, 5-pentanediol 1080 240 142

1, 2-propanediol 1480 184 104

Degassed water 6330 100 0

Butyl diglyme 0 256 117 Proglyme 0 175 65

Higlyme 0 275> 140

Subsequently, the wet powders thus obtained were handled in air and examined by XRD (X-ray diffractometry) and XPS (X-ray photoelectron spectroscopy). The results obtained are shown in Table 2 below. Table 2

As can be seen from Table 2, the use of degassed water as an oxidation inhibitor for catalyst VI is unsuitable because the reduced powder is almost completely oxidized to Co (OH) 2. The mixtures of catalyst VI with the abovementioned alcohols and ethers are comparable with catalyst VII with respect to XRD.

Differences can be seen by looking more closely at the catalyst surface using XPS. The proportion of cobalt in the oxidation state 0 is highest when the ethers are used and the proportion of the adsorbed "C" fragments is lowest, which is also reflected in the surface ratios O to Co and C to Co, which are obtained when the polyglycol ethers are used are lowest.

Furthermore, the water solubility of the polyglycol ethers is very low compared to the alcohols investigated, so that the risk of wetting the reduced catalyst by dissolved water into the protective liquid is very low. 2. Application examples a. Amination of Monoethylene Glycol In each case 6 g (dry weight) of the catalysts I to III prepared according to Example 1a) were incorporated into a 100 ml autoclave and mixed with 15 ml of monoethylene glycol (MEG). When using the catalyst II of the invention was first slurried with an excess of MEG and decanted. The procedure was repeated three times with 50 ml MEG each time to separate the butyl diglyme. It was then filled to the extent that 15 ml of MEG were in the autoclave.

The autoclaves were closed and subjected to leakage test with 20 bar H2. Subsequently, 48 ml of N H3 were pressed (5 ml / min) and heated at a heating rate of 5 ° C / min to 160 ° C reaction temperature. The pressure was adjusted by pressing on H2 to 150 bar and held constant over the experimental period of 5 h at 150 bar. Each hour samples were taken and analyzed by GC.

Table 3 below shows the results obtained after 3 h and 5 h running time.

Table 3

MEG = monoethylene glycol, MEOA = monoethanolamine, EDA = ethylenediamine

It can be clearly seen that the oxidic catalyst I is expected to have practically no activity, since it does not activate under the reaction conditions, while the reduced / passivated catalyst III and the reduced and butyldiglyme provided with catalyst II lead to significant conversions. Due to the "Nichf passivation, the conversion with the catalyst II according to the invention is above that of the reduced / passivated comparative catalyst III. The selectivity to the primary value products MEOA and EDA are virtually identical for comparable sales. b. Preparation of isophorone diamine (IPDA) by amination of isophorone nitrile (IPN)

The reaction was carried out in four continuously operated tubular reactors connected in series. The imination of isophorone nitrile (IPN) with ammonia to give isophorone nitrilimine (I PNI) in the first reactor was carried out at 60 ° C. on T1O2 (75 ml). The feed amount of IPN was 80 g / h, the NH3 amount 165 g / h. The effluent from the reactor was fed to the second reactor along with hydrogen and along with a recycle stream from the fourth reactor. The effluent from the second reactor was passed to the third reactor. The discharge of the third reactor was passed to the fourth reactor. The temperature of the second reactor was 70 ° C, that of the third reactor 1 10 ° C and that of the fourth reactor 140 ° C. The amount of hydrogen supplied was 87 Nl / h. The recycle stream from the fourth reactor to the inlet of the second reactor was 1100 g / hr. The system was operated at 195 bar.

Comparative reactions were run in the same facility under the same conditions. I. Comparative Example:

Under the conditions described above, 100 ml of the catalyst IV was charged into each of the second, third and fourth reactors. The cobalt catalyst was activated in the system by passing 200 Nl / h of hydrogen over the catalyst under normal pressure and the temperature was increased from 70 ° C to 280 ° C within 48 h. The temperature was kept at 280 ° C for 24 h and then lowered to 80 ° C within 12 h. The plant was then started up and the conditions described above were set. The proportion of unreacted aminonitrile (IPNA) in the reactor effluent from the hydrogenation reactor was 0.04 GC area%. The proportion of IPDA was 96.6 GC areas%. ii. Inventive example: In the second, third and fourth reactor 100 ml of this catalyst V were filled. The catalyst was introduced into the reactors under air without any special precautions. Subsequently, the plant was started under the conditions described above but without any preactivation and initially without dosing of IPN. Within 28 h, about 307 ml of butyl diglyme were discharged. Subsequently, IPN was metered in and after 32 hours no butyl diglyme could be detected in the discharge by GC analysis. Thus, the butyl diglyme is apparently easily removed from the pores of the catalyst. Under the conditions described above, the proportion of unreacted aminonitrile (IPNA) in the reactor effluent of the hydrogenation reactor was 0.08 GC area%. The proportion of IPDA was 96.2 GC area%. It can be seen from these comparative examples that the prereduced catalyst, which was stored according to the invention in the presence of a polyglycol ether, has a comparable activity to a catalyst which has been freshly reduced in the reactor.

Claims

claims

1. Use of at least one polyalkylene glycol dialkyl ether of the general formula I

(I) Ri-0- (CH ₂ -CHR ₂ 0) "- R in which the substituents have the following meanings independently of one another:

Ri, d-Ce-alkyl,

R _{2 is} hydrogen or methyl,

n 2 to 10,

as oxidation protection for reduced, heterogeneous catalysts.

Use according to claim 1 in the form of a dispersion comprising a reduced, heterogeneous catalyst as the disperse phase and at least one polyalkylene glycol dialkyl ether of the general formula I as the dispersion medium.

Use according to claim 1 or 2, characterized in that the substituents of the formula I independently of one another have the following meaning:

Ri is methyl, ethyl, propyl or butyl,

R _{2 is} hydrogen or methyl,

n 2 to 4. Use according to claim 3, characterized in that the polyalkylene glycol dialkyl ether is at least one compound selected from the group consisting of diglyme, proglyme, triglyme, tetraglyme, ethyl diglyme, butyl diglyme, polyglyme and higlyme or mixtures thereof. 5. Use according to any one of claims 1 to 4, characterized in that the hydroxyl number (OH number) of the polyalkylene glycol dialkyl ether is less than 100 mg KOH / g.

6. Use according to one of claims 1 to 5, characterized in that the polyalkylene glycol dialkyl ether has a boiling point of> 170 ° C.

7. Use according to any one of claims 1 to 6, characterized in that it is the polyalkylene glycol dialkyl ether is a compound which is in a liquid at a temperature in the range of 10 ° C to 100 ° C (at atmospheric pressure). 8. Use according to one of claims 1 to 7, characterized in that the reduced, heterogeneous catalyst as active component at least one element selected from the group consisting of nickel, cobalt, ruthenium, iron and copper or Contains mixtures thereof.

Use according to claim 8, characterized in that the reduced, heterogeneous catalyst contains as active component nickel and / or cobalt.

Use according to claim 8 or 9, characterized in that the catalyst was reduced by thermal treatment of its present in oxidic form active component with hydrogen.