A method for co-producing 1,4-butanediol and methacrylic acid

Abstract

The present invention provides a method for co-producing 1,4-butanediol and methacrylic acid, wherein allyl alcohol is subjected to a hydroformylation reaction to generate 4-hydroxybutyraldehyde and 2-methyl-3-hydroxypropanal, and after separation, 4-hydroxybutyraldehyde is hydrogenated to generate 1,4-butanediol, and 2-methyl-3-hydroxypropanal is dehydrated and oxidized to generate methacrylic acid. The co-production method provided by the present invention can significantly improve the utilization value of 2-methyl-3-hydroxypropanal, avoid the problem of low value of 2-methyl-1,3-propylene glycol produced as a by-product of conventional hydrogenation, and significantly improve the added value of allyl alcohol.

Description

Technical Field

[0001] The invention relates to the technical field of hydroformylation reaction, and in particular to a method for co-producing 1,4-butanediol and methacrylic acid. Background Art

[0002] 1,4-Butanediol (BDO), also known as 1,4-butylene glycol, is an important basic organic chemical and fine chemical raw material with a wide range of uses. It can be used as a raw material to derive a variety of high-value-added fine chemical products. As one of the raw materials for biodegradable plastics polybutylene terephthalate adipate (PBAT) and polybutylene succinate (PBS), new market application scenarios have been developed and there is huge room for growth.

[0003] Due to high technical barriers and limited raw material sources, BDO production is relatively concentrated. There are four main process routes for industrialized production of BDO: (1) Reppe method using formaldehyde and acetylene as raw materials; (2) butadiene acetoxylation method using butadiene and acetic acid as raw materials; (3) propylene method using propylene as starting material; (4) maleic anhydride method using n-butane / maleic anhydride as raw materials. Among them, the acetylene method mainly uses calcium carbide as raw material, which is a coal-consuming and high-power consumption industry, and has currently limited the increase in production capacity; the butadiene method / maleic anhydride method has basically withdrawn from the market due to raw material cost reasons: the propylene method has the advantages of small investment, low energy consumption, and flexible production capacity adjustment. This route is mainly divided into two processes: propylene oxidation to prepare propylene oxide, propylene oxide isomerization to obtain allyl alcohol, allyl alcohol is then hydroformylated to obtain 4-hydroxybutyraldehyde, and finally hydrogenation to obtain the final product BDO; or propylene and acetic acid are oxidized and condensed with O2 under the catalysis of a catalyst to synthesize allyl acetate, then hydrolyzed to obtain allyl alcohol, allyl alcohol is then hydroformylated to obtain 4-hydroxybutyraldehyde, and finally hydrogenation to obtain the final product BDO. With the accumulation and release of domestic propylene production capacity, the cost advantage of propylene-based BDO will be significantly improved.

[0004] Although the cost advantage of propylene-based BDO continues to improve, a considerable amount of by-products are generated, which significantly reduces the added value of the overall BDO industry. In the process of allyl alcohol hydroformylation, in addition to the main product 4-hydroxybutyraldehyde, the isomeric product 2-methyl-3-hydroxypropanal is inevitably generated; in addition, allyl alcohol will also isomerize to propionaldehyde under this condition. In the current mature industrial process, the by-products of hydroformylation are hydrogenated together with the main product to form the corresponding alcohols, namely 2-methyl-1,3-propanediol (MPO) and propanol (NPA), and sold as by-products. However, due to the limited market capacity of MPO, the price is more than 20% lower than that of BDO; NPA is produced by the propylene method, and has no cost advantage compared to the mature ethylene method NPA in the market, which significantly affects the revenue of the entire product chain.

[0005] Methacrylic acid (MAA) is an important organic chemical raw material and polymer intermediate. It is mainly used in organic synthesis and polymer preparation. It can be used as a raw material for synthetic rubber, the manufacture of thermosetting coatings, synthetic rubber, fabric treatment agents, etc. It is a monomer for the manufacture of acrylic ester solvent-based and emulsion adhesives to improve the bonding strength and stability of adhesives. The main downstream application is the production of methyl methacrylate, which is used for polymerization to manufacture organic glass. The current industrial routes for methacrylic acid are mainly acetone cyanohydrin method and direct oxidation method: although the acetone cyanohydrin method has high productivity and yield, due to the use of highly toxic chemicals such as hydrocyanic acid, the supply of hydrocyanic acid and the treatment of large amounts of waste acid become problems; the direct oxidation method uses oxygen to directly oxidize isobutylene or tert-butanol to produce methacrolein, which is then oxidized to methacrylic acid, which is heavily dependent on the supply of raw materials isobutylene or tert-butanol.

[0006] Therefore, it is urgent to find a method to effectively solve the problem of excessive by-products while achieving the production of BDO by the propylene method, while also significantly increasing the added value of the industrial chain. Summary of the invention

[0007] In order to overcome the above-mentioned defects existing in the prior art, the present invention provides a method for co-producing 1,4-butanediol and methacrylic acid, which effectively reduces by-products and increases the output of high value-added methacrylic acid.

[0008] To achieve the above object, the present invention adopts the following technical solution:

[0009] The present invention provides a method for co-producing 1,4-butanediol and methacrylic acid, the method mainly comprising the following steps:

[0010] S1: Allyl alcohol reacts with carbon monoxide and hydrogen in the presence of a homogeneous catalyst to obtain a reaction solution of 4-hydroxybutyraldehyde and 2-methyl-3-hydroxypropanal;

[0011] S2: extracting the reaction liquid in S1 with water to obtain an oil phase solution containing the catalyst and an aqueous solution containing 4-hydroxybutyraldehyde and 2-methyl-3-hydroxypropanal, wherein the oil phase solution as a mixture of catalytic metal, ligand and solvent can be recycled back to S1 to continue participating in the reaction;

[0012] S3: heating the aqueous solution obtained in S2, and separating the 2-methyl-3-hydroxypropanal to generate methacrolein to obtain an aqueous solution of methacrolein and 4-hydroxybutyraldehyde;

[0013] S4: the methacrolein obtained in S3 is subjected to oxidation reaction to obtain methacrylic acid, and then purified to obtain pure methacrylic acid;

[0014] S5: The 4-hydroxybutyraldehyde aqueous solution obtained in S3 is subjected to hydrogenation reaction to obtain an aqueous solution of 1,4-butanediol, which is then purified to obtain pure 1,4-butanediol.

[0015] Preferably, the homogeneous catalyst in the hydroformylation reaction S1 comprises a catalytic metal and a ligand.

[0016] Preferably, the hydroformylation reaction has a reaction temperature of 40 to 200° C., a reaction time of 0.2 to 20 h, and a reaction pressure of 0 to 30 MPaG.

[0017] Preferably, the molar ratio of hydrogen to carbon monoxide (H2:CO) is 0.3:1 to 2:1, and the reaction pressure is controlled to be 0 to 30 MPaG by the feed amount. The total molar number of hydrogen and carbon monoxide is preferably more than twice the molar number of allyl alcohol.

[0018] Preferably, the mass of the catalytic metal in the homogeneous catalyst is 0.0001 to 1% of the mass of the allyl alcohol.

[0019] Preferably, the catalytic metal contained in the homogeneous catalyst exists in the form of a metal salt, preferably in the form of acetate, isooctanoate, cyclopentaneate, acetylacetonate, etc., and the catalytic metal is one or more of Rh, Co, Ir, Ru, Os, Fe, Pd and Pt, preferably one or both of Rh or Co.

[0020] Preferably, the homogeneous catalyst also optionally contains a co-catalyst such as a ligand, and the ligand is selected from one or more of phosphorus-containing ligands, nitrogen-containing ligands, etc.; wherein the phosphorus-containing ligand is selected from one or more of alkyl phosphorus such as tributylphosphine, triphenylphosphine, tricyclohexylphosphine, benzyldiadamantylphosphine, 4,5-bisdiphenylphosphine-9,9-dimethylxanthene, etc., and alkyl phosphites such as triethyl phosphite, tributyl phosphite, triisooctyl phosphite, triphenyl phosphite, etc.; the nitrogen-containing ligand is selected from one or more of pyridine, trimethylamine, triethylamine, etc.; the amount of the ligand used is 1 to 1000 times the molar number of the catalytic metal, calculated as the molar number of phosphorus atoms or nitrogen atoms.

[0021] Preferably, a solvent is used in the hydroformylation reaction process, and the solubility of the solvent in water is less than 1%, and is preferably a mixture of one or more aromatic hydrocarbons, alkanes or cycloalkanes containing 6 to 12 carbon atoms, specifically selected from one or more of benzene, toluene, xylene, cyclohexane, methylcyclohexane, dimethylcyclohexane, hexane, heptane, octane, nonane, decane, undecane and dodecane.

[0022] Preferably, the extraction process in step S2 can be intermittent or continuous extraction, preferably a continuous extraction process, which can be selected from one of a packed extraction tower, a plate extraction tower, a rotary disc extraction tower, and a stirred clarification tank, and more preferably a plate extraction tower is used.

[0023] Preferably, during the extraction process in step S2, the amount of water used is 0.2 to 3 times the mass of the reaction solution in S1, preferably 0.5 to 1.5 times the mass of the reaction solution in S1, and more preferably 0.8 to 1 times the mass of the reaction solution in S1.

[0024] Preferably, during the extraction process in step S2, the extraction temperature is 20-100°C, preferably 30-50°C.

[0025] Preferably, the extraction process in step S2 is carried out under a gas atmosphere, and the gas is preferably one or more of hydrogen, carbon monoxide, nitrogen, helium, and argon, and more preferably a mixture of hydrogen and carbon monoxide.

[0026] Preferably, the heating process in step S3 adopts an intermittent or continuous process, preferably a continuous process, which may adopt a continuous stirred tank, a tubular reactor, etc., and more preferably a tubular reactor.

[0027] Preferably, during the heating process in step S3, the heating temperature is controlled at 40-90°C, preferably 50-70°C.

[0028] Preferably, the heating process time of step S3 is 0.5 to 24 hours, preferably 4 to 6 hours, so that more than 99% of the 2-methyl-3-hydroxypropanal in the aqueous solution is dehydrated to generate methacrolein.

[0029] Preferably, the separation method after heating in step S3 is distillation.

[0030] Preferably, the distillation process may adopt intermittent or continuous distillation, preferably continuous distillation.

[0031] Furthermore, the distillation process may adopt normal pressure or negative pressure distillation, preferably negative pressure distillation, and the distillation tower pressure is 20-50 kPaA.

[0032] Preferably, in the distillation process, a solution containing methacrolein is obtained at the top of the tower, and an aqueous solution of 4-hydroxybutyraldehyde is obtained at the bottom of the tower, wherein the content of methacrolein solution in the aqueous solution obtained at the bottom of the tower is less than 0.1 wt.%.

[0033] Preferably, during the distillation process, the solution containing methacrolein at the top of the tower also contains distilled propionaldehyde.

[0034] Preferably, in step S4, the oxidation and separation process is to oxidize the solution containing methacrolein using air or oxygen as an oxidant, and the oxidation is performed in the form of an excess of the oxidant. After the oxidation, the propionaldehyde in the solution containing methacrolein is oxidized into propionic acid.

[0035] Preferably, in step S4, the reaction temperature of the oxidation process is 30-150° C., the reaction time is 1-10 h, and the reaction pressure is 0-0.7 MPaG.

[0036] Preferably, in step S4, the purification method after oxidation is distillation, and pure methacrylic acid is obtained by distillation.

[0037] Preferably, in the distillation process of step S4, pure propionic acid is obtained by distillation.

[0038] Preferably, in step S5, the hydrogenation process may be intermittent or continuous hydrogenation, preferably a continuous hydrogenation process, which may be in the form of a continuous stirred tank, trickle bed, slurry bed, bubbling bed, etc.

[0039] Preferably, during the hydrogenation process in step S5, the hydrogenation is carried out in the presence of a solid catalyst. Preferably, the solid catalyst is a nickel-based or copper-based catalyst, more preferably a nickel-based catalyst, and the mass of the solid catalyst is 0.1-1% of the mass of the 4-hydroxybutyraldehyde aqueous solution.

[0040] Preferably, during the hydrogenation process in step S5, the reaction temperature is 40-200°C, preferably 80-130°C.

[0041] Preferably, during the hydrogenation process in step S5, the hydrogen pressure is 0 to 15 MPaG, more preferably, the pressure is 3 to 8 MPaG; the hydrogenation reaction time is 1 to 10 hours, preferably 2 to 6 hours.

[0042] Preferably, the refining method after hydrogenation in step S5 is distillation, and pure BDO is obtained by distillation.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention performs special treatment on the product after the hydroformylation of allyl alcohol, dehydrates and oxidizes the undesirable by-product 2-methyl-3-hydroxypropanal to synthesize methacrylic acid, and oxidizes the undesirable by-product propionaldehyde into propionic acid, thereby reducing the by-products of low-value 2-methyl-1,3-propanediol and propanol in the original process, converting them into methacrylic acid and propionic acid with high added value, and significantly improving the added value of the BDO industrial chain. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0046] The sources of the reagent raw materials used in the examples and comparative examples of the present invention are as follows:

[0047] Rhodium acetylacetonate, cobalt acetate, rhodium acetate, and triphenylphosphine were purchased from Aladdin Reagent Co., Ltd.;

[0048] Allyl alcohol was purchased from Merck Reagent Co., Ltd.;

[0049] Hydrogen, carbon monoxide, and air were purchased from Yantai Development Zone Shuangfeng Industrial Co., Ltd.;

[0050] Benzyldiadamantylphosphine, triphenylphosphine carbonyl rhodium acetylacetonate, and 1,3-bis(dicyclohexylphosphino)propane bis(tetrafluoroborate) were purchased from Jiangsu Xinnoko Catalyst Co., Ltd., Xinxiang Runyu New Materials Technology Co., Ltd., and other companies;

[0051] Unless otherwise specified, other reagents and raw materials are commercially available.

[0052] The elemental analysis was performed using Euro Vector's EA3000 elemental analyzer with a carrier gas of 80 kPa, 100 mL / min, 15 mL of oxygen, an oxidation time of 10 s, and an oven temperature of 130 °C.

[0053] NMR spectroscopy was performed using a Bruker AVANCE III NMR spectrometer.

[0054] The catalytic metal content in the hydroformylation reaction liquid was determined by the ICP method according to the standards GB / T23613-2009, YS / T832-2012, etc., using an Agilent ICP-OES720 instrument.

[0055] The conversion rate of allyl alcohol, the conversion rate of aldehydes, the selectivity of aldehydes and the selectivity of acids were calibrated by gas chromatography internal standard method, wherein the conversion rate = (moles of reaction raw materials - moles remaining after the reaction) / moles of reaction raw materials × 100%, and the product selectivity = moles of products after the reaction / (moles of reaction raw materials - moles of remaining raw materials after the reaction) × 100%. The gas chromatograph was Agilent Technologies GC-7820, the gas chromatograph column was a 0.25 mm × 30 m DB-5 capillary column, the column box temperature was programmed from 40°C to 280°C at a rate of 15°C / min and maintained for 5 min, an FID detector was used, the vaporization chamber temperature was 280°C, the detector temperature was 300°C, the argon carrier flow was 2.1 mL / min, the hydrogen flow was 30 mL / min, the air flow was 400 mL / min, and the injection volume was 1.0 μL.

[0056] Unless otherwise specified, the percentages used in the examples and comparative examples of the present invention are all percentages by mass.

[0057] Example 1

[0058] (1) Allyl alcohol hydroformylation reaction

[0059] 0.4g of acetylacetonato rhodium, 50.1g of triphenylphosphine, 100.0g of allyl alcohol, and 349.9g of toluene were added to a 1L pressure-resistant stirred reactor. After three times of syngas replacement, the mixture was stirred and heated to 80°C. H2:CO syngas with a molar ratio of 1:1 was introduced into the reactor until the relative pressure of the reactor was 1.0MPaG. When the pressure in the reactor dropped, the syngas was added until the system pressure was 1.0MPaG. The temperature and pressure in the reactor were kept constant. After 6 hours of reaction, the samples were taken for analysis. The conversion rate of allyl alcohol was 99%, the selectivity of 4-hydroxybutyraldehyde was 76%, the selectivity of 2-methyl-3-hydroxypropanal was 19%, and the selectivity of propanal was 3%. After the reactor was cooled to 30°C, it was vented to normal pressure to obtain 548.3g of hydroformylation reaction liquid.

[0060] (2) Extraction

[0061] Under nitrogen atmosphere, 548.3 g of the hydroformylation reaction solution from step (1) was added to a 2 L three-necked flask, and then 548.3 g of water was added for extraction. After stirring for 30 minutes, the mixture was allowed to stand for 3 hours to separate into layers, thereby obtaining an oil-water phase. The upper clear liquid was the solvent oil phase containing the catalyst and the ligand; the lower layer was the aqueous solution containing 4-hydroxybutyraldehyde.

[0062] (3) Heat treatment of 4-hydroxybutyraldehyde aqueous solution

[0063] Under a nitrogen atmosphere, the 4-hydroxybutyraldehyde aqueous solution obtained in step (2) was added to a 1L three-necked flask, the temperature was raised to 80°C and stirred for reaction for 4 hours, and the aqueous solution after the reaction was distilled to obtain 30.8 g of an aqueous solution of methacrolein at the top of the tower, including 72.2% methacrolein and 9.6% propionaldehyde, and 652.1 g of an aqueous solution of 4-hydroxybutyraldehyde was obtained in the bottom of the tower.

[0064] (4) Oxidation process

[0065] Add 30.8g of methacrolein aqueous solution to a 0.1L pressure-resistant stirred reactor, stir and heat to 50°C. Pass compressed air into the reactor until the relative pressure of the reactor is 0.4MPaG. When the pressure in the reactor drops, add air to the system pressure of 0.4MPaG, keep the temperature and pressure in the reactor constant, and take samples for analysis after 3h of reaction. The conversion rate of methacrolein is 99%, the selectivity of methacrylic acid is 99%, the selectivity of propionaldehyde is 99%, and the selectivity of propionic acid is 98%. After the reactor is cooled to 30°C, it is vented to normal pressure, and the obtained reaction solution is distilled to obtain 3.5g of propionic acid with a purity of 99.3% and 26.2g of methacrylic acid with a purity of 99.5%.

[0066] (5) Hydrogenation process

[0067] Add 652.1g of 4-hydroxybutyraldehyde aqueous solution and 1.3g of Raney nickel catalyst to a 1L pressure-resistant stirred reactor. After hydrogen replacement three times, stir and heat to 150°C. Pass hydrogen into the reactor until the relative pressure of the reactor is 5.0MPaG. When the pressure in the reactor drops, add hydrogen to the system pressure of 5.0MPaG, keep the temperature and pressure in the reactor constant, and take samples for analysis after 2h of reaction. The conversion rate of 4-hydroxybutyraldehyde is 99%, and the selectivity of BDO is 98%. After the reactor is cooled to 30°C, it is vented to normal pressure, and the obtained reaction solution is distilled to obtain 108.7g of BDO product with a purity of 99.9%.

[0068] Comparative Example 1

[0069] (1) Allyl alcohol hydroformylation reaction

[0070] 0.4g of acetylacetonato rhodium, 50.1g of triphenylphosphine, 100.0g of allyl alcohol, and 349.9g of toluene were added to a 1L pressure-resistant stirred reactor. After three times of syngas replacement, the mixture was stirred and heated to 80°C. H2:CO syngas with a molar ratio of 1:1 was introduced into the reactor until the relative pressure of the reactor was 1.0MPaG. When the pressure in the reactor dropped, the syngas was added until the system pressure was 1.0MPaG. The temperature and pressure in the reactor were kept constant. After 6 hours of reaction, the samples were taken for analysis. The conversion rate of allyl alcohol was 99%, the selectivity of 4-hydroxybutyraldehyde was 76%, the selectivity of 2-methyl-3-hydroxypropanal was 19%, and the selectivity of propanal was 3%. After the reactor was cooled to 30°C, it was vented to normal pressure to obtain 548.3g of hydroformylation reaction liquid.

[0071] (2) Extraction

[0072] Under nitrogen atmosphere, 548.3 g of the hydroformylation reaction solution from step (1) was added to a 2 L three-necked flask, and then 548.3 g of water was added for extraction. After stirring for 30 minutes, the mixture was allowed to stand for 3 hours to separate into layers, thereby obtaining an oil-water phase. The upper clear liquid was the solvent oil phase containing the catalyst and the ligand; the lower layer was the aqueous solution containing 4-hydroxybutyraldehyde.

[0073] (3) Hydrogenation process

[0074] Add the 4-hydroxybutyraldehyde aqueous solution obtained in step (2) and 1.3 g of Raney nickel catalyst to a 1 L pressure-resistant stirred reactor. After hydrogen replacement three times, stir and heat to 150° C. Pass hydrogen into the reactor until the relative pressure of the reactor is 5.0 MPaG. When the pressure in the reactor drops, add hydrogen to the system pressure of 5.0 MPaG, keep the temperature and pressure in the reactor constant, and take samples for analysis after 2 hours of reaction. The conversion rate of 4-hydroxybutyraldehyde is 99%, the selectivity of BDO is 98%, the conversion rate of 2-methyl-3-hydroxypropanal is 99%, and the selectivity is 98%. After the reactor is cooled to 30° C., it is vented to normal pressure, and the obtained reaction solution is distilled to obtain 107.6 g of BDO product with a purity of 99.9% and 26.1 g of 2-methyl-1,3-propanediol with a purity of 98.5%.

[0075] Example 2

[0076] (1) Allyl alcohol hydroformylation reaction

[0077] 0.03g of rhodium acetate, 45.4g of triphenylphosphine, 4.6g of benzyldiadamantylphosphine, 100.0g of allyl alcohol, and 349.9g of toluene were added to a 1L pressure-resistant stirred reactor. After three times of syngas replacement, the mixture was stirred and heated to 80°C. H2:CO syngas with a molar ratio of 1:1 was introduced into the reactor until the relative pressure of the reactor was 8.0MPaG. When the pressure in the reactor dropped, the syngas was added until the system pressure was 8.0MPaG. The temperature and pressure in the reactor were kept constant. After 7h of reaction, the samples were taken for analysis. The conversion rate of allyl alcohol was 99%, the selectivity of 4-hydroxybutyraldehyde was 87%, the selectivity of 2-methyl-3-hydroxypropanal was 10%, and the selectivity of propanal was 2%. After the reactor was cooled to 30°C, it was vented to normal pressure to obtain 549.0g of hydroformylation reaction liquid.

[0078] (2) Extraction

[0079] Under nitrogen atmosphere, 549.0 g of the hydroformylation reaction solution from step (1) was added to a 2 L three-necked flask, and then 549.0 g of water was added for extraction. After stirring for 60 minutes, the mixture was allowed to stand for 3 hours to separate into layers, thereby obtaining an oil-water phase. The upper clear liquid was the solvent oil phase containing the catalyst and the ligand; the lower layer was the aqueous solution containing 4-hydroxybutyraldehyde.

[0080] (3) Heat treatment of 4-hydroxybutyraldehyde aqueous solution

[0081] Under a nitrogen atmosphere, the 4-hydroxybutyraldehyde aqueous solution obtained in step (2) was added to a 1L three-necked flask, the temperature was raised to 60°C and stirred for 10 hours, and the aqueous solution after the reaction was distilled to obtain 20.7 g of an aqueous solution of methacrolein at the top of the tower, including 56.6% methacrolein and 9.5% propionaldehyde, and 671.9 g of an aqueous 4-hydroxybutyraldehyde aqueous solution was obtained in the bottom of the tower.

[0082] (4) Oxidation process

[0083] Add 20.7g of methacrolein aqueous solution to a 0.1L pressure-resistant stirred reactor, stir and heat to 80°C. Pass compressed air into the reactor until the relative pressure of the reactor is 0.1MPaG. When the pressure in the reactor drops, add air to the system pressure of 0.1MPaG, keep the temperature and pressure in the reactor constant, and take samples for analysis after 2h of reaction. The conversion rate of methacrolein is 99%, the selectivity of methacrylic acid is 99%, the selectivity of propionaldehyde is 99%, and the selectivity of propionic acid is 99%. After the reactor is cooled to 30°C, it is vented to normal pressure, and the obtained reaction solution is distilled to obtain 2.3g of propionic acid with a purity of 99.4% and 13.8g of methacrylic acid with a purity of 99.8%.

[0084] (5) Hydrogenation process

[0085] Add 671.9 g of 4-hydroxybutyraldehyde aqueous solution and 1.9 g of Raney nickel catalyst to a 1L pressure-resistant stirred reactor. After hydrogen replacement three times, stir and heat to 120°C. Pass hydrogen into the reactor until the relative pressure of the reactor is 3.0 MPaG. When the pressure in the reactor drops, add hydrogen to the system pressure of 3.0 MPaG, keep the temperature and pressure in the reactor constant, and take samples for analysis after 6 hours of reaction. The conversion rate of 4-hydroxybutyraldehyde is 99%, and the selectivity of BDO is 99%. After the reactor is cooled to 30°C, it is vented to normal pressure, and the obtained reaction solution is distilled to obtain 125.7 g of BDO product with a purity of 99.9%.

[0086] Embodiment 3:

[0087] (1) Allyl alcohol hydroformylation reaction

[0088] 0.5g acetylacetonato triphenylphosphine carbonyl rhodium, 6.7g 1,3-bis(dicyclohexylphosphino)propane bis(tetrafluoroborate), 100.0g allyl alcohol, 350.1g toluene were added to a 1L pressure-resistant stirred reactor. After three times of syngas replacement, the mixture was stirred and heated to 90°C. H2:CO syngas with a molar ratio of 1:1 was introduced into the reactor until the relative pressure of the reactor was 0.6MPaG. When the pressure in the reactor dropped, the syngas was added until the system pressure was 0.6MPaG. The temperature and pressure in the reactor were kept constant. After 9h of reaction, the samples were taken for analysis. The conversion rate of allyl alcohol was 97%, the selectivity of 4-hydroxybutyraldehyde was 81%, the selectivity of 2-methyl-3-hydroxypropanal was 13%, and the selectivity of propanal was 5%. After the reactor was cooled to 30°C, it was vented to normal pressure to obtain 492.4g of hydroformylation reaction liquid.

[0089] (2) Extraction

[0090] Under nitrogen atmosphere, 492.4 g of the hydroformylation reaction solution from step (1) was added to a 2 L three-necked flask, followed by extraction with 492.4 g of water. The mixture was stirred for 30 minutes and allowed to stand for 2 hours to separate into two phases, to obtain an oil-water phase. The upper clear liquid was the solvent oil phase containing the catalyst and the ligand; the lower layer was the aqueous solution containing 4-hydroxybutyraldehyde.

[0091] (3) Heat treatment of 4-hydroxybutyraldehyde aqueous solution

[0092] Under a nitrogen atmosphere, the 4-hydroxybutyraldehyde aqueous solution obtained in step (2) was added to a 1L three-necked flask, the temperature was raised to 80°C and stirred for 5h, and the aqueous solution after the reaction was distilled to obtain 27.6g of an aqueous solution of methacrolein at the top of the tower, wherein the methacrolein was 53.5% and the propionaldehyde was 17.6%, and 606.6g of an aqueous solution of 4-hydroxybutyraldehyde was obtained in the bottom of the tower.

[0093] (4) Oxidation process

[0094] Add 20.7g of methacrolein aqueous solution to a 0.1L pressure-resistant stirred reactor, stir and heat to 90°C. Pass compressed air into the reactor until the relative pressure of the reactor is 0.1MPaG. When the pressure in the reactor drops, add air to the system pressure of 0.1MPaG, keep the temperature and pressure in the reactor constant, and take samples for analysis after 2h of reaction. The conversion rate of methacrolein is 99%, the selectivity of methacrylic acid is 97%, the selectivity of propionaldehyde is 99%, and the selectivity of propionic acid is 97%. After the reactor is cooled to 30°C, it is vented to normal pressure, and the obtained reaction solution is distilled to obtain 5.7g of propionic acid with a purity of 99.5% and 17.4g of methacrylic acid with a purity of 99.9%.

[0095] (5) Hydrogenation process

[0096] Add 606.6g of 4-hydroxybutyraldehyde aqueous solution and 1.7g of Raney nickel catalyst to a 1L pressure-resistant stirred reactor. After hydrogen replacement three times, stir and heat to 140°C. Pass hydrogen into the reactor until the relative pressure of the reactor is 2.0MPaG. When the pressure in the reactor drops, add hydrogen to the system pressure of 2.0MPaG, keep the temperature and pressure in the reactor constant, and take samples for analysis after 4 hours of reaction. The conversion rate of 4-hydroxybutyraldehyde is 99%, and the selectivity of BDO is 98%. After the reactor is cooled to 30°C, it is vented to normal pressure, and the obtained reaction solution is distilled to obtain 113.6g of BDO product with a purity of 99.9%.

[0097] Calculated according to the product prices in September 2021, with BDO at RMB 29,000 / ton, methacrylic acid at RMB 19,000 / ton, propionic acid at RMB 9,200 / ton, and 2-methyl-1,3-propanediol at RMB 7,000 / ton, the value of a ton of allyl alcohol product, including only the material value-added part, is shown in the following table.

[0098]

[0099] It can be seen from the above examples and comparative examples that the BDO and methacrylic acid method of the present invention can effectively increase the product value, and the added value of a single ton of allyl alcohol product can reach more than 3,700 yuan, and up to 6,200 yuan, which significantly increases the added value of the BDO device and improves the competitiveness of the BDO device. It can be seen that the co-production method of the present invention is very valuable for industrial application.

[0100] Unless otherwise defined, the terms used in the present invention have the meanings commonly understood by those skilled in the art.

[0101] The embodiments described in the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Those skilled in the art may make various other substitutions, changes and improvements within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments, but is only limited by the claims.

Claims

1. A method for co-producing 1,4-butanediol and methacrylic acid, characterized in that: The following steps are involved: S1: Allyl alcohol reacts with carbon monoxide and hydrogen in the presence of a homogeneous catalyst to obtain a reaction solution of 4-hydroxybutyraldehyde and 2-methyl-3-hydroxypropanal; S2: extracting the reaction solution in S1 with water to obtain an oil phase solution containing a catalyst and an aqueous solution containing 4-hydroxybutyraldehyde and 2-methyl-3-hydroxypropanal; S3: heating the aqueous solution in S2, and separating the 2-methyl-3-hydroxypropanal to generate methacrolein to obtain methacrolein and 4-hydroxybutyraldehyde aqueous solution; S4: the methacrolein obtained in S3 is subjected to oxidation reaction to obtain methacrylic acid, and then purified to obtain pure methacrylic acid; S5: The 4-hydroxybutyraldehyde aqueous solution obtained in S3 is subjected to hydrogenation reaction to obtain an aqueous solution of 1,4-butanediol, and the purified 1,4-butanediol is obtained after refining; the homogeneous catalyst in step S1 includes a catalytic metal and a ligand; the catalytic metal is one or both of Rh and Co; the catalytic metal exists in the form of acetate or acetylacetonate; the ligand is selected from phosphorus-containing ligands.

2. The method according to claim 1, characterized in that In step S1, the molar ratio of the catalytic metal to the phosphorus in the ligand is 1:1-1000; based on the mass of allyl alcohol being 100%, the mass of the catalytic metal is 0.0001-1% of the mass of allyl alcohol.

3. The method according to claim 1, characterized in that The reaction temperature of step S1 is 40-200° C., the reaction time is 0.2-20 h, and the reaction pressure is 0-30 MPaG; and / or the molar ratio of hydrogen to carbon monoxide is 0.3-2:

1.

4. The method according to any one of claims 1 to 3, characterized in that: The amount of water used in step S2 is 0.2 to 3 times the mass of the reaction solution in step S1; and / or the extraction temperature in the extraction process is 20 to 100°C.

5. The method according to any one of claims 1 to 3, characterized in that: The amount of water used in step S2 is 0.5 to 1.5 of the mass of the reaction solution in step S1; and / or the extraction temperature in the extraction process is 30 to 50°C.

6. The method according to any one of claims 1 to 3, characterized in that: The extraction process in step S2 is carried out under a gas atmosphere, and the gas is one or more of hydrogen, carbon monoxide, nitrogen, helium, and argon.

7. The method according to any one of claims 1 to 3, characterized in that: The temperature of the heating treatment in step S3 is 40-90° C., and the heating time is 0.5-24 hours.

8. The method according to claim 7, characterized in that The temperature of the heating treatment in step S3 is 50-70° C., and the heating time is 4-6 hours.

9. The method according to any one of claims 1 to 3, characterized in that: The separation method in step S3 is distillation; the distillation is selected from one of intermittent distillation and continuous distillation.

10. The method according to any one of claims 1 to 3, characterized in that: The oxidant of the oxidation process in step S4 is air or oxygen, the reaction temperature of the oxidation process is 30-150° C., the reaction time is 1-10 hours, and the reaction pressure is 0-0.7 MPaG.

11. The method according to any one of claims 1 to 3, characterized in that: The hydrogenation process in step S5 may be intermittent or continuous hydrogenation; and / or, the hydrogenation process is carried out under the action of a solid catalyst, the solid catalyst is one of a nickel-based or copper-based catalyst, and the mass of the solid catalyst is 0.1-1% of the mass of the 4-hydroxybutyraldehyde aqueous solution.

12. The method according to any one of claims 1 to 3, characterized in that: In step S5, the hydrogenation reaction temperature is 40-200° C., the hydrogen pressure is 0-15 MPaG, and the hydrogenation reaction time is 1-10 h.

13. The method according to claim 12, characterized in that In step S5, the hydrogenation reaction temperature is 80-130° C., the hydrogen pressure is 3-8 MPaG, and the hydrogenation reaction time is 2-6 hours.

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