DE102013021508A1 - Process for the preparation of neopentyl glycol - Google Patents

Abstract

The present invention relates to a process for the preparation of neopentyl glycol by reacting isobutyraldehyde and formaldehyde in the presence of acidic solids as a catalyst to hydroxypivalaldehyde at above 100 ° C. Hydroxypivalaldehyde is then hydrogenated in the presence of a hydrogenation catalyst with hydrogen at a temperature of 80 to 180 ° C and at a pressure of 2 to 18 MPa to neopentyl glycol.

Description

The present invention relates to a process for the preparation of neopentyl glycol by reacting isobutyraldehyde with formaldehyde in the presence of solid acidic catalysts and subsequent catalytic hydrogenation of the hydroxypivalaldehyde formed.

Polyhydric alcohols or polyols have a significant economic importance as a condensation component for the construction of polyesters or polyurethanes, synthetic resin paints, lubricants and plasticizers. In this case, especially those polyhydric alcohols of interest, which are obtained by a mixed aldol addition of formaldehyde with iso- or n-butyraldehyde. In the aldol addition between formaldehyde and the corresponding butyraldehyde, an aldehydic intermediate first forms which subsequently has to be reduced to the polyhydric alcohol. A technically significant polyhydric alcohol obtainable by this process is neopentyl glycol [NPG, 2,2-dimethylpropanediol- (1,3)] from the mixed aldolization of formaldehyde and isobutyraldehyde (US Pat. Chemiker-Zeitung, 100th Year (1976) No. 12, pages 504-514 ; Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, 2003, Wiley VCH Verlag GmbH & Co. KGaA, Weinheim, vol. 2, pp. 50-52 ).

The aldol addition is usually carried out in the presence of basic catalysts, for example of alkali metal hydroxides or alkaline earth metal hydroxides or aliphatic amines, and initially yields the isolable intermediate hydroxypivalaldehyde (HPA).

However, the disadvantage of using alkali metal or alkaline earth metal hydroxides as base is the high salt content and contamination of the resulting aldol addition product with alkali metal or alkaline earth metal ions which are troublesome in the subsequent catalytic hydrogenation of hydroxypivalaldehyde to neopentyl glycol for the metal catalyst (US Pat. DE 1 768 274 A1 . DE 1 957 591 A1 ). However, it is also possible for the initially formed aldol addition product hydroxypivalaldehyde to react further in the presence of a stoichiometric amount of a base with one equivalent of formaldehyde in accordance with the Cannizzaro reaction. In this case, aqueous solutions of sodium hydroxide, potassium hydroxide or calcium hydroxide are usually used. The reduction of the aldehyde group in the hydroxypivalaldehyde forms neopentyl glycol and formaldehyde is oxidized to formic acid, so that the corresponding formats, such as sodium formate, potassium formate or calcium formate, are obtained as by-products ( EP 0 769 000 A1 . WO 2000/058246 A1 ).

The aldol addition of isobutyraldehyde and formaldehyde to hydroxypivalaldehyde is also carried out in the presence of catalytic amounts of tertiary amines. Usually lower tertiary alkylamines such as trimethylamine, triethylamine or tri-n-propylamine are used ( DE 1 957 591 A1 . US 4,855,515 . EP 0 522 369 A1 . WO 2010/079187 A1 . EP 1 752 439 A1 . DE 3 644 675 A1 ). Since the amine catalyst is dissolved in the organic reaction product obtained, a high distillation effort is required for its separation and recycling to the aldol addition stage. Also, in the subsequent hydrogenation to polyols, the tertiary alkylamines tend to form nitrogen-containing decomposition products, the presence of which, even in slight traces, massively affects the quality of the polyol for many subsequent applications. When working up the polyol, it is therefore necessary to ensure almost complete removal of nitrogen-containing contaminants.

In order to facilitate the separation of the basic catalyst from the organic reaction product, the use of solid, basic catalysts is also recommended. As such catalysts, for example, macroporous ion exchange resins are used which carry basic tertiary amino groups ( DE 1 957 591 A1 ). Both weakly and strongly basic ion exchange resins are described, which are preferably based on a styrene-divinylbenzene polymer matrix having tertiary amino groups as functional groups ( EP 0 948 476 B1 . US 2,818,443 ). Preferably, weakly basic ion exchange resins ( WO 98/29374 A1 ). To WO 92/19579 A1 a mixture of tertiary amines and metal oxides of the elements IB, IVA, IVB, VA, VB, VIB and VIII of the Periodic Table of the Elements, in particular titanium and chromium, used as a catalyst for the aldol addition of isobutyraldehyde and formaldehyde. Although the organic reaction product is easily filtered off from the oxidic solid, laborious work-up is required to sufficiently separate the nitrogen-containing compounds.

The use of acidic ion exchange resins for the aldol addition of isobutyraldehyde with formaldehyde is also described. To DE 26 53 096 A1 strongly acidic cation exchangers are used which are prepared by copolymerization of styrene and polyvinylbenzene and subsequent sulfonation with sulfuric acid or oleum. The aldol addition is generally carried out in one Temperature range from atmospheric pressure to the boiling point of the reaction mixture, preferably between 40 to 95 ° C.

The Hydroxypivalinaldehyd obtained can be converted except in the Cannizzaro reaction by the catalytic hydrogenation on the metal contact in neopentyl glycol, which is technically designed in the form of gas phase hydrogenation or liquid phase hydrogenation. In the gas phase variant, hydroxypivalaldehyde is first freed from high boilers in an evaporator upstream of the hydrogenation stage. The subsequent hydrogenation is preferably carried out in the presence of Raney nickel catalysts or supported catalysts based on nickel, which may additionally contain other active metals such as copper or chromium and moreover activators. For example, in the gas phase variant EP 0 278 106 A1 . US 4,094,014 ; Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, 2003, Wiley VCH Verlag GmbH & Co. KGaA, Weinheim, vol. 2, pp. 50-52 ; Chemiker-Zeitung, 100th Year (1976) No. 12, pages 504-514 received.

To EP 0 484 800 A2 Hydrogenation of hydroxypivalaldehyde occurs in the liquid phase using catalysts based on copper, zinc and zirconium. Also, the use of copper chromite catalysts is described several times in liquid phase hydrogenation. According to US 4,855,515 are suitable for manganese and according to WO98 / 29374 A1 barium-doped copper chromite catalysts. Also EP 0 522 368 A1 recommends the use of copper chromite catalysts in liquid phase hydrogenation in the presence of water and a lower alcohol.

The use of basic or acidic ion exchangers for the conversion of isobutyraldehyde and formaldehyde to hydroxypivalaldehyde has the advantage that the solid aldolization catalyst can be separated from the organic reaction product by simple filtration. However, the thermal stability of the ion exchange resins is limited and the prior art recommends a reaction temperature up to the boiling point of the reaction mixture.

Neopentyl glycol is of great commercial importance as a manufactured product and therefore there is a need to always improve the known processes for neopentyl glycol production, be it through improved product yield, better plant utilization or lower energy input.

Siril, Cross and Brown are featured in the Journal of Molecular Catalysis A: Chemical 29 (2008), pages 63-68 to the low thermal stability of acidic ion exchange resins which limits their use in catalytic processes. The halogenation of the sulfonic acid resin can improve the thermal stability of the acidic ion exchanger. Such modified ion exchangers are commercially available, for example, under the name Amberlyst 70 from Rohm and Haas. A number of catalytic processes in the presence of such ion exchangers are described, for example the isomerization of α-pinene or the benzylation of toluene with benzyl alcohol. Hints to use such temperature-stable ion exchange resins for the aldol addition reaction of formaldehyde with isobutyraldehyde, are in Journal of Molecular Catalysis A: Chemical 29 (2008), pages 63-68 not mentioned.

It has surprisingly been found that isobutyraldehyde and formaldehyde react at over 100 ° C to hydroxypivalaldehyde in good yield when the aldol addition is carried out in the presence of acidic solids. The resulting reaction product is then reacted in the presence of a hydrogenation catalyst at elevated pressure and elevated temperature with hydrogen to neopentyl glycol.

The present invention therefore relates to a process for the preparation of neopentyl glycol, characterized in that the reaction of iso-butyraldehyde and formaldehyde in the presence of an acidic solid as a catalyst for hydroxypivalaldehyde is carried out at above 100 ° C and hydroxypivalaldehyde obtained with hydrogen at a temperature of 80 is reacted to 180 ° C and at a pressure of 2 to 18 MPa in the presence of a hydrogenation catalyst.

In the aldol addition of isobutyraldehyde and formaldehyde solution is generally carried out with an aqueous formaldehyde solution, which is commercially available in concentrations of 20 to 50 wt .-%. The reaction temperature is above 100 ° C., preferably in the temperature range from above 100 ° C. to 200 ° C., in particular from above 100 ° C. to 140 ° C.

Due to the increased reaction temperature advantageously form isobutyraldehyde and the aqueous formaldehyde solution a homogeneous phase, so that the mass transfer is facilitated. The aldol addition takes place in a closed reaction vessel under the autogenous autogenous pressure or by applying a foreign gas pressure, preferably an inert gas pressure such as nitrogen pressure or inert gas pressure, to 5 MPa, preferably to 3 MPa. 0.9 to 1.2, preferably 1 mole of formaldehyde are used per mole of isobutyraldehyde.

In addition to the water from the aqueous formaldehyde solution and small amounts of methanol, which is likewise contained in the aqueous formaldehyde solution, a diluent, for example a lower alcohol such as methanol, ethanol, n-propanol or isobutanol, preferably isobutanol, is optionally added to the reaction mixture. The iso-butanol addition is not mandatory, but if iso-butanol is added, its content in the reaction mixture in the range of 15 to 30 wt .-%, preferably 15 to 25 wt .-%, based on the organic content in the whole reaction mixture. Further solvents and diluents are not required.

Preferably, however, no solvent or diluent is added to the reaction mixture.

The aldol addition reaction is carried out in the presence of acidic solids. As such solids, for example, acidic metal oxides such as alumina or acidic transition metal oxides such as tungsten oxide on zirconia or molybdenum oxide on zirconia are suitable. Also suitable are natural or siliceous materials, such as montmorillonite or acid zeolites, for example of the Y-type, BEA-type, MFI-type or mordenite-type, which are available in industrial quantities and are used industrially, for example, in the catalytic cracking of crude oil , Commercially available ion exchangers such as Amberlyst 15, Amberlyst 70, Amberlyst 36, Nafion or Nafion-SAC can also be used.

The practical implementation of the aldol addition of isobutyraldehyde and formaldehyde can be carried out in suspension in a stirred tank or in a stirred tank cascade, wherein a sufficient distribution of the solid in the reaction solution is to be ensured. Likewise, the aldol addition can be carried out in a tubular reactor on a fixed catalyst bed by the trickle or sump procedure. This variant in the reaction procedure allows a simple way to return from the discharged reaction mixture a partial flow as a circulation stream in the reactor. Otherwise, when using catalysts suspended in the reaction mixture, the aldolization catalyst is filtered off after the end of the reaction. The aldol addition reaction can be carried out either batchwise or continuously. In the batchwise process, per 100 parts by weight of reaction mixture 5 to 25, preferably 10 to 20 parts of acidic solids used. In the continuous process, a catalyst load V / Vh, expressed in throughput volume per catalyst volume and time of 0.1 to 1 h ^-1 , preferably 0.2 to 0.5 h ^{-1 has} proved to be useful.

After completion of the aldol addition reaction, the reaction solution is allowed to cool, generally to 60 ° C., and the optionally suspended aldolization catalyst and optionally other solids are separated off.

In some cases, it may prove convenient to treat the organic reaction product with an adsorbent to remove harmful impurities for the hydrogenation catalyst. Suitable adsorbents are, for example, activated carbon, metal-containing solids, such as nickel-containing, molybdenum-containing, copper-containing solids, surface-rich polysilicic acids such as silica gels (silica xerogels) or mineral materials, such as clays or carbonates. The treatment of the organic reaction product with the adsorbent can take place via a fixed cleaning bed or in suspension. The amount of adsorbent, the operation of the cleaning bed, such as temperature or load, can be determined by routine experimentation.

The crude mixture obtained after the aldol addition and catalyst removal is hydrogenated, optionally after distillative or extractive removal of volatile constituents such as water, methanol, isobutanol and residual amounts of formaldehyde, isobutyraldehyde or without prior separation with hydrogen on the metal contact to neopentyl glycol. The hydrogenation can be designed in the form of a gas phase variant or in the form of a liquid phase variant.

In the gas phase variant, the hydroxypivalaldehyde-containing organic crude product is added to an evaporator, which is generally operated at temperatures of 140 to 190 ° C under atmospheric pressure up to an overpressure of 0.3 MPa. High boilers fall in the evaporator as a residue and are discharged from the process. The high boilers are oxygenated compounds such as esters or cyclic acetals in which equivalents of neopentyl glycol are chemical are bound. In the high boilers, the proportion of mono- and di-iso-butyric acid esters of neopentyl glycol as well as on the disproportionation product Neopentylglykolmonohydroxypivalinsäureester formed from Hydroxypivalinaldehyd after the Tishchenko reaction is particularly high.

The volatile evaporator effluent essentially contains hydroxypivalaldehyde and, depending on the optional work-up of the crude aldol addition mixture, water, the diluent, if added, further volatiles, such as methanol from the formaldehyde stabilization. The gas phase hydrogenation is usually operated continuously.

In the liquid phase hydrogenation is carried out with suspended in the organic phase catalysts, which are distributed by intensive stirring in the liquid organic phase. In addition, it is also possible to proceed on fixed catalysts in a tubular reactor by the sump or trickle method. The liquid phase hydrogenation can be carried out either continuously or batchwise.

Suitable hydrogenation catalysts are the hydrogenation catalysts known from the prior art for the hydrogenation of hydroxypivalaldehyde based on copper, cobalt, chromium, manganese, nickel or zinc. Also catalysts of transition metals such as palladium, ruthenium, platinum, rhodium or tungsten can be used. They may be used as unsupported catalysts or as supported catalysts with suitable support materials such as activated carbon, kieselguhr, silica gel, alumina or zirconia as powder or in the form of tablets, stars, strands, rings or other particles of relatively large surface area.

In particular, copper chromite catalysts containing even more metals, such as barium, cadmium, magnesium, manganese and / or a rare earth metal, as activators are suitable. Also, nickel catalysts are preferred, for example Raney nickel or supported nickel catalysts, which contain in an amount of about 5 to 70 wt .-%, preferably about 10 to about 65 wt .-% and in particular about 20 to 60 wt .-% nickel, in each case based on the total weight of the catalyst. Suitable catalyst supports are any conventional support materials, for example, alumina, alumina hydrates in their various forms, silica, polysilicic acids (silica gels) including kieselguhr, silica xerogels, magnesia, zinc oxide, zirconia, and activated carbon. In addition to the main components nickel and support material, the catalysts may also contain additives in minor amounts which serve, for example, to improve their hydrogenation activity and / or their service life and / or their selectivity. Such additives are known, including, for example, the oxides of sodium, potassium, magnesium, calcium, barium, zinc, aluminum, zirconium and chromium. They are generally added to the catalyst in a proportion of 0.1 to 50 parts by weight, based on 100 parts by weight of nickel.

The hydrogenation of the crude hydroxypivalaldehyde is carried out at a temperature of from 80 to 180 ° C, preferably from 110 to 140 ° C. The pressure is 2 to 18 MPa, preferably 3 to 10 MPa. Especially a temperature of 110 to 140 ° C and a pressure of 3 to 10 MPa prove. At even lower pressures, satisfactory hydrogenation of the hydroxypivalaldehyde is no longer observed.

The hydrogenation is preferably carried out with pure hydrogen. However, it is also possible to use mixtures which contain free hydrogen and, in addition, inert constituents under the hydrogenation conditions.

The recovery of pure neopentyl glycol from the hydrogenated reaction mixture is carried out by conventional distillation methods. Separated solvent or diluent can be recycled back to the aldol addition stage and / or to the hydrogenation stage.

According to the novel process, the aldol addition of formaldehyde and isobutyraldehyde is carried out in the presence of acidic solids at temperatures above 100.degree. In this procedure, a homogeneous solution is formed from the aqueous formaldehyde solution and the organic isobutyraldehyde in the reaction vessel, which reacts in the presence of the solid aldolization catalyst. After completion of the adol addition, the liquid reaction mixture can be easily separated from the solid acidic aldolization catalyst.

In the following, the method according to the invention will be explained in more detail with reference to a few examples.

Examples

example 1

Preparation of Neopentylglycol (NPG)

125 g of isobutyraldehyde, 140 g of aqueous formaldehyde solution (35.9% strength aqueous solution) and 37.5 g of Amberlyst 15 wet (manufacturer: The Dow Chemicals, USA) were initially introduced under nitrogen as protective gas in an autoclave. Subsequently, the pressure was increased to 5 MPa by adding nitrogen and the autoclave was heated to 120 ° C. After reaching 120 ° C, the reaction mixture was left for one hour under these experimental conditions.

The reaction mixture was then cooled, expanded and removed and filtered off from the Amberlyst 15wet. The resulting reaction product was then hydrogenated without further purification at 130 ° C and 8 MPa hydrogen pressure in the presence of five weight percent of a 5% Ru / C catalyst for 2 hours in an autoclave. The reaction mixture had the following composition, the organic fraction being analyzed by gas chromatography: TABLE 1 Composition of the hydrogenation product in% by weight methanol 1,5% isobutanol 1.7% Cyclic acetal NPG / formalin 0.2% neopentylglycol 58.8% NPG-mono isobutyrate 0.3% Schenk served Oester * 2.8% water 34.7% total 100.0% * Tishchenkoester: 2,2-Dimethyl-1,3-propandiolmonohydroxypivalinsäureester

The yield of NPG based on isobutyraldehyde is 91.7% of theory over both stages.

Example 2

catalyst screening

Analogous to Example 1, further acidic catalysts were tested. The following results were obtained: Table 2: Testing of acidic catalysts in the aldol addition of isobutyraldehyde with formaldehyde and subsequent hydrogenation catalyst Yield of NPG based on isobutyraldehyde [%] Zeolite HY (CBV 600, Zeolyst) 48.6 Zeolite H-BEA (Zeochem) 56.1 Zeolite H-ZSM5 (Zeochem) 81.1 Zeolite H-MOR (Zeochem) 67.3 Tungsten oxide on zirconium dioxide (Saint-Gobain) 40.2 Nafion SAC 13 (BASF) 67.8 Amberlyst 70 (The Dow Chemicals) 85.9 Amberlyst 36 (The Dow Chemicals) 89.2 Sial 3113 (WC Grace) 37.4

Example 3

Preparation of neopentyl glycol in a fixed bed reactor

Continuous aldol addition

A 600 mL tube volume tubular reactor was charged with Amberlyst 70 (The Dow Chemicals). Isobutyraldehyde and formaldehyde as a 49% aqueous solution were fed continuously at the bottom of the reactor. At the top of the reactor, the reaction mixture was removed and transferred to a non-pressurized template. The process was carried out under nitrogen pressure and the pressure was controlled by an overflow. The experimental conditions were set as follows: Temperature [° C] Use of isobutyraldehyde [mL / h] Commitment; 49% aqueous formaldehyde solution [mL / h] Pressure [MPa] 190 122.5 76.0 3.5

Catalytic hydrogenation

The reaction mixture thus obtained was hydrogenated analogously to the conditions of Example 1 in an autoclave. In this case, a yield of NPG of 49% based on isobutyraldehyde was achieved.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 1768274 A1 [0004]
• DE 1957591 A1 [0004, 0005, 0006]
• EP 0769000 A1 [0004]
• WO 2000/058246 A1 [0004]
• US 4855515 [0005, 0009]
• EP 0522369 A1 [0005]
• WO 2010/079187 A1 [0005]
• EP 1752439 A1 [0005]
• DE 3644675 A1 [0005]
• EP 0948476 B1 [0006]
• US Pat. No. 2,818,444 [0006]
• WO 98/29374 A1 [0006, 0009]
• WO 92/19579 A1 [0006]
• DE 2653096 A1 [0007]
• EP 0278106 A1 [0008]
• US 4094014 [0008]
• EP 0484800 A2 [0009]
• EP 0522368 A1 [0009]

Cited non-patent literature

• Chemiker-Zeitung, 100th Year (1976) No. 12, pages 504-514 [0002]
• Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, 2003, Wiley VCH Verlag GmbH & Co. KGaA, Weinheim, vol. 2, pp. 50-52 [0002]
• Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, 2003, Wiley VCH Verlag GmbH & Co. KGaA, Weinheim, vol. 2, pp. 50-52 [0008]
• Chemiker-Zeitung, 100th year (1976) No. 12, pages 504-514 [0008]
• Siril, Cross and Brown are featured in the Journal of Molecular Catalysis A: Chemical 29 (2008), pages 63-68 [0012]
• Journal of Molecular Catalysis A: Chemical 29 (2008), pages 63-68 [0012]

Claims (9)

A process for the preparation of neopentyl glycol, characterized in that the reaction of iso-butyraldehyde and formaldehyde in the presence of an acidic solid as a catalyst for hydroxypivalaldehyde is carried out at above 100 ° C and hydroxypivalaldehyde obtained with hydrogen at a temperature of 80 to 180 ° C and at is reacted at a pressure of 2 to 18 MPa in the presence of a hydrogenation catalyst. A method according to claim 1, characterized in that the reaction of isobutyraldehyde and formaldehyde at a temperature of about 100 ° C to 200 ° C, preferably from about 100 to 140 ° C. Process according to Claim 1 or 2, characterized in that the acidic solid used is acidic metal oxides, acidic transition metal oxides, acidic zeolites, acidic silicatic substances or acidic ion exchangers. Method according to one or more of claims 1 to 3, characterized in that the reaction of isobutyraldehyde with an aqueous formaldehyde solution. Method according to one or more of claims 1 to 4, characterized in that the reaction of isobutyraldehyde with formaldehyde is carried out with the addition of a diluent. Process according to one or more of Claims 1 to 5, characterized in that, after the reaction of isobutyraldehyde with formaldehyde, the reaction product is treated with an adsorbent. Process according to Claim 6, characterized in that activated carbon, molybdenum-containing, nickel-containing, copper-containing solids, surface-rich polysilicic acids or mineral materials are used as the adsorbent. Process according to one or more of Claims 1 to 7, characterized in that the hydrogenation catalyst used is a nickel catalyst or a copper-chromite catalyst. Method according to one or more of claims 1 to 8, characterized in that the hydrogenation is carried out at a temperature of 110 ° C to 140 ° C and at a pressure of 3 to 10 MPa.