A method for preparing bio-based 1,4-butanediol

Abstract

The present invention provides a method for preparing bio-based 1,4-butanediol, belonging to the technical field of organic synthesis. The present invention provides a method for preparing bio-based 1,4-butanediol, comprising the following steps: mixing succinic acid from a bio-based source and an alcohol compound for an esterification reaction to obtain an oligomeric polyester; under a catalyst, subjecting the oligomeric polyester to hydrogenation reduction to obtain a crude 1,4-butanediol; and purifying the crude 1,4-butanediol to obtain the bio-based 1,4-butanediol. The present invention uses succinic acid from a bio-based source and an alcohol compound as raw materials, and prepares the target product bio-based 1,4-butanediol through esterification and hydrogenation reduction. The succinic acid is derived from biological fermentation, the raw material sources are wide and renewable, carbon emissions are reduced, the recyclable utilization of biomass energy is realized, the added value of the product can be increased, environmental pollution can be reduced, and at the same time, considerable economic benefits can be brought.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing bio-based 1,4-butanediol. Background Art

[0002] 1,4-Butanediol (BDO) is a transparent liquid at room temperature and has good chemical stability. It is an important chemical raw material that can be used in pharmaceutical synthesis and the preparation of advanced coatings, advanced inks, advanced resins, synthetic fiber rubber, surfactants, etc.

[0003] At present, the main production processes of 1,4-butanediol are: Reppe process, maleic anhydride process, allyl alcohol process and butadiene process. These traditional methods are all based on petrochemical raw materials. The Reppe process uses acetylene and formaldehyde as raw materials. First, acetylene and formaldehyde are used to synthesize 1,4-butynediol under the action of copper catalyst, and 1,4-butynediol is then hydrogenated to generate 1,4-butanediol. The Reppe process has the advantages of low operating costs, but the acetylene partial pressure in the acetylation process is too high, resulting in the process requiring a reactor design safety factor of up to 12 to 20, which greatly increases the initial equipment investment cost. At the same time, high acetylene partial pressure is also prone to generate polyacetylene, causing pipeline blockage, reducing production efficiency, and easily causing catalyst deactivation. In view of the shortcomings of the traditional Reppe method, the improved Reppe method is safer, with less equipment investment and a longer production cycle. The improved Reppe method is mainly divided into four processes: BASF, Dupont, IS, and Linde&SK.For example, Chinese patent CN101244984A discloses a comprehensive method for continuously preparing 1,4-butanediol, comprising the following stages: (I) reacting formaldehyde and acetylene in the presence of a copper catalyst at a pH value of 5 to 8, wherein the molar ratio of formaldehyde to acetylene is at most 2:1; (II) intermediate buffering the obtained aqueous mixture containing butynediol for 0.1 to 100 hours; (III) hydrogenating the mixture obtained after the intermediate buffering; and (IV) reacting the mixture obtained in stage III with acetylene. The obtained hydrogenation product is distilled to obtain 1,4-butanediol; Chinese patent CN102408307A discloses a method for preparing butanediol by two-stage bed hydrogenation of butynediol. Aiming at the adaptability of the reaction system containing water or the fluctuation of water content in the reaction system in the current two-step hydrogenation process of butynediol to butanediol and the requirement for inhibiting the formation of carbon deposits, it is proposed that the hydrogenation catalysts A and B in the two-stage bed contain a carrier, a metal active component and a silane group, and the silane group is grafted by silylation treatment, wherein the silane The group accounts for 0.1wt% to 12wt% of the total weight of the hydrogenation catalyst. Compared with the prior art, the hydrogenation catalyst has obvious raw material applicability under the premise of ensuring good activity and selectivity. The presence of water has almost no effect on the catalytic performance of the hydrogenation catalyst. At the same time, it can significantly inhibit the formation of carbon on the surface of the catalyst, prolonging the service life of the catalyst, which makes the hydrogenation reaction system have a long stable operation cycle. Chinese patent CN109651110A discloses that the production process mainly includes a formaldehyde section, an acetylene chemical section, a hydrogenation section and a product distillation section. The formaldehyde section mainly generates formaldehyde from raw material methanol and air under the action of a catalyst, the acetylene chemical section mainly generates refined 1,4-butynediol by acetylene and formaldehyde under the action of a catalyst, the hydrogenation section mainly generates crude 1,4-butanediol by reacting 1,4-butynediol and hydrogen from an upstream furnace gas purification section under a certain pressure under the action of a catalyst, and the product distillation section mainly performs distillation treatment on 1,4-butanediol to obtain a high-purity 1,4-butanediol product.

[0004] The butadiene method converts butadiene into 1,4-diacetoxy-2-butene through an acetyl oxidation reaction, and then further hydrogenates to obtain 1,4-diacetoxybutane, and finally hydrolyzes to obtain the target product 1,4-butanediol. This method has the advantages of high selectivity of the target product and flexible regulation of the ratio of tetrahydrofuran to 1,4-butanediol, but it also has disadvantages such as large steam consumption and complex equipment. For example, Chinese patent CN108017509A discloses a method for producing 1,4-butanediol from butadiene, comprising the following steps: using butadiene, acetic acid and oxygen as raw materials, performing an oxyacetylation reaction in the presence of an oxyacetylation catalyst to obtain 1,4-diacetoxybutene, reacting hydrogen with 1,4-diacetoxybutene in the presence of a hydrogenation catalyst to obtain 1,4-diacetoxybutane, and hydrolyzing 1,4-diacetoxybutane to obtain 1,4-butanediol, and the hydrogenation catalyst uses activated carbon as a carrier, and the active component includes a Pt element and a promoter element, and the promoter element includes a metal selected from iron and VA group metals. At least one metal element in the family; Chinese patent CN107915579A discloses that butadiene, acetic acid and oxygen are used as raw materials, and an oxyacetylation reaction is carried out in the presence of an oxyacetylation catalyst to obtain 1,4-diacetoxybutene, in the presence of a hydrogenation catalyst, hydrogen reacts with 1,4-diacetoxybutene to obtain 1,4-diacetoxybutane, and 1,4-diacetoxybutane is hydrolyzed to obtain 1,4-butanediol, the hydrogenation catalyst uses activated carbon as a carrier, and the active component includes a Pt element and a promoter element, and the promoter element is selected from at least one metal element of a metalloid group metal and a VIIB group metal.

[0005] The allyl alcohol method first generates allyl alcohol by isomerization of propylene oxide, and then the allyl alcohol is hydroformylated in liquid phase to generate 4-hydroxybutyraldehyde solution under the action of aromatic hydrocarbons as solvent, rhodium catalyst and triphenylphosphine solution as catalyst, and then hydrogenated to generate 1,4-butanediol under the action of Raney nickel catalyst. This method uses rare precious metals, is expensive, is not environmentally friendly, and has the disadvantages of low product selectivity and more by-products. For example, Chinese patent CN111801312A discloses the use of synthesis gas to hydroformylate allyl alcohol in allyl alcohol feed to produce hydroformylation products including 4-hydroxybutyraldehyde and 3-hydroxy-2-methylpropanal, and hydrogenates at least a portion of the hydroformylation product to produce 1,4-butanediol (BDO) products including BDO and 1,3-methylpropanediol.

[0006] The maleic anhydride method uses maleic anhydride as a raw material to react with methanol to first generate maleic dimethyl ester, and then hydrogenates to obtain 1,4-butanediol and co-produce tetrahydrofuran. This method has the disadvantages of high raw material cost and large equipment investment. For example, Chinese patent CN106083523A discloses combining the maleic anhydride production process with the BDO production process, eliminating the original equipment and energy consumption of rich oil analysis and solvent treatment in the n-butane method maleic anhydride device, removing the impurities generated by the maleic anhydride device together with the impurities of the BDO device, saving the device cost, using butanol as the maleic anhydride esterification raw material to generate dibutyl maleate (DBM), and being able to utilize the butanol byproduct generated in the hydrogenation stage.

[0007] The above traditional methods all use petrochemical-based raw materials as their source, and petrochemical-based raw materials are becoming increasingly scarce and non-renewable. Summary of the invention

[0008] In view of this, the purpose of the present invention is to provide a bio-based 1,4-butanediol and its preparation method and application. The present invention uses bio-based succinic acid as raw material, and prepares the target product bio-based 1,4-butanediol through esterification and hydrogenation reduction. The raw material source is wide and renewable.

[0009] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0010] The present invention provides a method for preparing bio-based 1,4-butanediol, comprising the following steps:

[0011] The bio-based succinic acid and alcohol compounds are mixed and subjected to esterification reaction to obtain oligomeric polyester;

[0012] In the presence of a catalyst, the oligomer polyester is subjected to hydrogenation reduction to obtain a crude 1,4-butanediol product;

[0013] The crude 1,4-butanediol is purified to obtain the bio-based 1,4-butanediol.

[0014] Preferably, the alcohol compound includes one or more of butanol, pentanol, hexanol, ethylene glycol and 1,4-butanediol.

[0015] Preferably, the molar ratio of the bio-based succinic acid to the alcohol compound is 1:1.2-2.4.

[0016] Preferably, the esterification reaction is carried out at a temperature of 160 to 210° C. and for a time of 4 to 8 hours.

[0017] Preferably, the ratio of hydrogen used in the hydrogenation reduction to the hydrogen ester of the oligomer polyester is 80 to 200:1.

[0018] Preferably, the hydrogenation reduction is carried out at a pressure of 1 to 20 MPa, a temperature of 100 to 220° C., and a time of 2 to 6 hours.

[0019] Preferably, the catalyst is a supported copper-based catalyst.

[0020] Preferably, the supported copper-based catalyst is prepared by a method comprising the following steps:

[0021] (1) mixing copper nitrate hexahydrate, aluminum nitrate nonahydrate, an active metal salt and water to obtain a metal ion salt solution, wherein the metal in the active metal salt comprises magnesium, manganese, nickel, cobalt, zinc, cerium or zirconium;

[0022] (2) Mix sodium hydroxide, sodium carbonate and water to obtain an alkali solution precipitant with a molar ratio of [OH - ]=2([M 2+ ]+[M 3 + ]) and [CO 3- ]=0.5[M 3+ ], M refers to metal element;

[0023] (3) adding the metal ion salt solution and the alkali solution precipitant into a reactor at 60° C. to perform a precipitation reaction to obtain a precipitated product, and maintaining the pH of the reaction system at 8 to 10;

[0024] (4) aging the precipitated product at 70° C. for 24 hours to obtain a ternary hydrotalcite-like substance;

[0025] (5) The ternary hydrotalcite is calcined and activated in sequence to obtain the supported copper-based catalyst.

[0026] Preferably, the molar ratio of the copper nitrate hexahydrate, the metal in the active metal salt and the aluminum nitrate nonahydrate is 1-5:1:0.25-2.

[0027] Preferably, the calcination temperature is 400-800° C. and the calcination time is 0.5-8 h.

[0028] The invention provides a method for preparing bio-based 1,4-butanediol, comprising the following steps: mixing bio-based succinic acid and an alcohol compound for esterification reaction to obtain an oligomer polyester; hydrogenating and reducing the oligomer polyester in the presence of a catalyst to obtain a crude 1,4-butanediol product; and purifying the crude 1,4-butanediol product to obtain the bio-based 1,4-butanediol.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention uses bio-based succinic acid and alcohol compounds as raw materials, and prepares the target product bio-based 1,4-butanediol through esterification and hydrogenation reduction. Succinic acid comes from biological fermentation, and the raw material source is wide and renewable, which reduces carbon emissions and realizes the circular utilization of biomass energy, which can not only increase the added value of the product, but also reduce environmental pollution, and also bring considerable economic benefits.

[0031] Furthermore, the alcohol compound in the present invention includes one or more of butanol, pentanol, hexanol, ethylene glycol and 1,4-butanediol, and the esterification reaction can be carried out between succinic acid and the alcohol compound without a catalyst, and no post-treatment is required after the esterification is completed, and no catalyst needs to be separated, and there is no cumbersome post-treatment process. In addition, the boiling point of 1,4-butanediol is relatively high, which is greatly different from the boiling point of water, and can be separated from water by distillation. The water generated by the esterification reaction can be separated from the reaction system, so that the esterification reaction proceeds smoothly. At the same time, no other types of alcohol are introduced in the esterification process, so the intermediate product does not need to be distilled and purified, and can be used for the next process.

[0032] Furthermore, in the present invention, a supported copper catalyst is used in the hydrogenation reduction, a hydrotalcite precursor is prepared by a constant pH value coprecipitation method, and then the final active Cu catalyst is obtained by calcination and decomposition. The coprecipitation method is used for preparation, so the metal loading amount can be significantly increased compared with the traditional impregnation method. At the same time, the surface morphology and physicochemical properties of the supported copper catalyst can be changed by regulating the active metal ratio and the calcination temperature, so that the catalyst has a higher specific surface area, metal dispersion, suitable surface acidity and Cu + / Cu 0 Therefore, the catalyst can achieve a lower hydrogenation pressure (1-20 MPa), a lower hydrogenation temperature (100-220°C) and a lower hydrogen-ester ratio (hydrogen-ester ratio 80-200:1) for the catalytic hydrogenation of oligomer polyester. At the same time, the conversion rate of oligomer polyester is ≥99.5%, and the selectivity of 1,4-butanediol is ≥98.0%.

[0033] The data of the examples show that the purity of the bio-based 1,4-butanediol prepared by the present invention is ≥99.5%, the raw material conversion rate is ≥99.5%, and the 1,4-butanediol selectivity is ≥98.0%. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Flow chart of the method for preparing bio-based 1,4-butanediol in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention provides a method for preparing bio-based 1,4-butanediol, comprising the following steps:

[0036] The bio-based succinic acid and alcohol compounds are mixed and subjected to esterification reaction to obtain oligomeric polyester;

[0037] In the presence of a catalyst, the oligomer polyester is subjected to hydrogenation reduction to obtain a crude 1,4-butanediol product;

[0038] The crude 1,4-butanediol is purified to obtain the bio-based 1,4-butanediol.

[0039] In the present invention, unless otherwise specified, the raw materials used are all commercially available products in the art.

[0040] The invention mixes succinic acid of bio-based source and alcohol compounds to carry out esterification reaction to obtain oligomer polyester.

[0041] In the present invention, taking 1,4-butanediol as an example, the principle of the esterification reaction is shown in the following formula:

[0042]

[0043] n is 1, 2, 3, 4 or 5.

[0044] In the present invention, the bio-based succinic acid is preferably derived from biological fermentation, more preferably starch fermentation or lignocellulose fermentation. The present invention preferably refines and purifies the fermentation to obtain the succinic acid in a manner well known to those skilled in the art. The bio-based succinic acid is widely available and renewable, which reduces carbon emissions and realizes the recyclable utilization of biomass energy, which can not only increase the added value of the product, but also reduce environmental pollution and bring considerable economic benefits.

[0045] In the present invention, the alcohol compound preferably includes one or more of butanol, pentanol, hexanol, ethylene glycol and 1,4-butanediol, and more preferably 1,4-butanediol. The succinic acid and the alcohol compound can undergo an esterification reaction without a catalyst, and no post-treatment is required after the esterification is completed, and no catalyst needs to be separated, and no cumbersome post-treatment process is required; and 1,4-butanediol has a high boiling point, which is greatly different from the boiling point of water, and can be separated from water by distillation. The water generated by the esterification reaction can be separated from the reaction system, so that the esterification reaction proceeds smoothly. At the same time, no other types of alcohol are introduced during the esterification process, so the intermediate product does not need to be distilled and purified and can be used for the next process.

[0046] In the present invention, the mass ratio of the bio-based succinic acid to the alcohol compound is preferably 10:11-16.

[0047] In the present invention, the temperature of the esterification reaction is preferably 160-210° C., more preferably 168-197° C., further preferably 175-190° C., most preferably 182° C., and the time is preferably 5-7 h.

[0048] In the present invention, during the esterification reaction, the acid value is preferably controlled to be less than 10 mgKOH / g.

[0049] In the present invention, during the esterification reaction, samples are preferably taken to detect and analyze the acid value, and the content of carboxylic acid therein is detected. If the acid value is less than 10 mgKOH / g, the esterification requirement is reached, and the esterification reaction is deemed to be substantially completed.

[0050] In the present invention, the acid value analysis method preferably comprises the following steps:

[0051] 1 Reagents and test solutions

[0052] 1.1 Anhydrous ethanol;

[0053] 1.2 Potassium hydroxide ethanol standard solution〔C(KOH)=0.1mol / L〕;

[0054] 1.3 Phenolphthalein indicator solution: 1g / L ethanol solution;

[0055] 1.4 Neutral ethanol: Using phenolphthalein as the indicator, add potassium hydroxide ethanol standard solution to drip anhydrous ethanol until it turns slightly red.

[0056] 2 Steps:

[0057] Weigh 20 g of sample (accurate to 0.0001 g) into a conical flask, add 50 mL of neutral ethanol, add 2 to 3 drops of phenolphthalein indicator, and add potassium hydroxide standard solution until it turns slightly red. The end point is that it does not fade for 10 seconds.

[0058] BE01 acid value X 1 (mgKOH / g) is calculated according to formula (1):

[0059]

[0060] Where: C: concentration of potassium hydroxide ethanol standard titration solution, unit is mol / L;

[0061] V: volume of potassium hydroxide ethanol standard titration solution consumed in titrating the sample, in mL;

[0062] 56.1 is a constant.

[0063] m: mass of the sample, in g.

[0064] The present invention preferably takes the arithmetic mean of the parallel determination results as the analysis result.

[0065] After the esterification reaction is completed, the present invention preferably directly performs hydrogenation reduction on the obtained oligomer polyester without post-treatment.

[0066] After obtaining the oligomer polyester, the present invention performs hydrogenation reduction on the oligomer polyester in the presence of a catalyst to obtain a crude 1,4-butanediol product.

[0067] In the present invention, taking 1,4-butanediol as an example, the main reaction of the hydrogenation reduction is shown as follows:

[0068]

[0069] (2n+1)

[0070] The side reaction is shown below:

[0071]

[0072] In the present invention, the hydrogen-to-ester ratio of the hydrogen used in the hydrogenation reduction to the oligomer polyester is preferably 80 to 200:1, and the hydrogen-to-ester ratio refers to the molar ratio of hydrogen to the oligomer polyester.

[0073] In the present invention, the pressure of the hydrogenation reduction is preferably 1 to 20 MPa, more preferably 8 to 18 MPa, further preferably 10 to 16 MPa, and most preferably 12 to 14 MPa. The temperature is preferably 100 to 220°C, more preferably 160 to 210°C, further preferably 170 to 200°C, and most preferably 180 to 190°C. The time is preferably 2 to 6 h, and more preferably 3 to 5 h.

[0074] In the present invention, the mass ratio of the catalyst to the oligomer polyester is 1:500-1000.

[0075] In the present invention, the catalyst is preferably a supported copper-based catalyst.

[0076] In the present invention, the supported copper-based catalyst is preferably prepared by a method comprising the following steps:

[0077] (1) mixing copper nitrate hexahydrate, aluminum nitrate nonahydrate, an active metal salt and water to obtain a metal ion salt solution, wherein the metal in the active metal salt comprises magnesium, manganese, nickel, cobalt, zinc, cerium or zirconium;

[0078] (2) Mix sodium hydroxide, sodium carbonate and water to obtain an alkali solution precipitant with a molar ratio of [OH - ]=2([M 2+ ]+[M 3 + ]) and [CO 3- ]=0.5[M 3+ ], M refers to metal element;

[0079] (3) adding the metal ion salt solution and the alkali solution precipitant into a reactor at 60° C. to perform a precipitation reaction to obtain a precipitated product, and maintaining the pH of the reaction system at 8 to 10;

[0080] (4) aging the precipitated product at 70° C. for 24 hours to obtain a ternary hydrotalcite-like substance;

[0081] (5) The ternary hydrotalcite is calcined and activated in sequence to obtain the supported copper-based catalyst.

[0082] In the present invention, the molar ratio of the copper nitrate hexahydrate, the metal in the active metal salt and the aluminum nitrate nonahydrate is preferably 1-5:1:0.25-2, and more preferably 2-5:1:0.3-0.7.

[0083] In the present invention, the calcination temperature is preferably 400-800° C., more preferably 500-600° C., and the calcination time is preferably 0.5-8 h, more preferably 2-4 h.

[0084] In the present invention, the activation is preferably carried out at 5 vol% H 2 / Ar.

[0085] In the present invention, the hydrogenation reduction is preferably carried out in a hydrogenation reaction tower, and the catalyst is preferably loaded in a continuous reactor.

[0086] The present invention preferably prepares a hydrotalcite precursor by a constant pH value coprecipitation method, and then decomposes it by calcination to obtain a final active Cu-based catalyst. The coprecipitation method is used for preparation, so the metal loading amount can be significantly increased compared with the traditional impregnation method. At the same time, the surface morphology and physicochemical properties of the supported copper-based catalyst can be changed by regulating the active metal ratio and the calcination temperature, so that the catalyst has a higher specific surface area, metal dispersion, suitable surface acidity and Cu + / Cu 0 Therefore, the catalytic hydrogenation of oligomer polyester by this catalyst can achieve lower hydrogenation pressure, lower hydrogenation temperature and lower hydrogen-ester ratio, while improving the conversion rate of oligomer polyester and the selectivity of 1,4-butanediol.

[0087] After obtaining the crude 1,4-butanediol, the present invention purifies the crude 1,4-butanediol to obtain the bio-based 1,4-butanediol.

[0088] In the present invention, the purification is preferably distillation purification, the pressure of the distillation purification is preferably 8-25 mmHg, and the temperature of the distillation purification is preferably 140-190°C.

[0089] In the present invention, the distillation and purification preferably further obtains a fore fraction, which preferably includes n-butanol, water, tetrahydrofuran, etc. The fore fraction is preferably used as a by-product solvent.

[0090] In the present invention, the distillation purification preferably also obtains a high boiling component as a by-product.

[0091] In order to further illustrate the present invention, the preparation method of bio-based 1,4-butanediol provided by the present invention is described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0092] Figure 1 Flow chart of the method for preparing bio-based 1,4-butanediol in an embodiment of the present invention.

[0093] The supported copper catalysts in Examples 1 to 7 of the present invention are prepared by a method comprising the following steps:

[0094] (1) 2.4 mol of aluminum nitrate nonahydrate, 1 mol of aluminum nitrate hexahydrate, 0.6 mol of zinc nitrate hexahydrate and water are mixed to obtain a mixed solution;

[0095] (2) Mix sodium hydroxide, sodium carbonate and water to obtain an alkali solution precipitant with a molar ratio of [OH - ]=2([M 2+ ]+[M 3 + ]) and [CO 3- ]=0.5[M 3+ ], M refers to metal element;

[0096] (3) adding the metal ion salt solution and the alkali solution precipitant into a reactor at 60° C. to perform a precipitation reaction to obtain a precipitated product, and maintaining the pH of the reaction system at 8 to 10;

[0097] (4) aging the precipitated product at 70° C. for 24 h to obtain a ternary hydrotalcite-like substance;

[0098] (5) The ternary hydrotalcite was calcined (500°C, 3 h) and activated (in 5 vol% H 2 / Ar).

[0099] The succinic acid in Examples 1 to 7 is all commercially available bio-based succinic acid.

[0100] Examples 1 to 7

[0101] The raw materials were weighed according to the raw material dosage in Table 1, and an esterification reaction was carried out. The temperature of the esterification reaction was shown in Table 1. The obtained oligomer polyester was introduced into a hydrogenation reactor and directly subjected to a hydrogenation reduction reaction. One ton of catalyst was fed to react 500 tons of oligomer polyester. The hydrogenation reduction reaction was shown in Table 1 to obtain crude 1,4-butanediol, which was then distilled and purified at a pressure of 8 to 20 mmHg and a temperature of 140 to 190° C. to obtain bio-based 1,4-butanediol.

[0102] As can be seen from Table 1, the present invention uses bio-based succinic acid and alcohol compounds as raw materials, and prepares the target product bio-based 1,4-butanediol through esterification and hydrogenation reduction. The purity of the prepared bio-based 1,4-butanediol is ≥99.5%, the raw material conversion rate is ≥99.5%, and the 1,4-butanediol selectivity is ≥98.0%.

[0103] Table 1 Reaction conditions, product purity and product batch yield of Examples 1 to 7

[0104]

[0105] Example 8

[0106] The same as Example 1, the only difference is that the calcination temperature during the preparation of the catalyst is 600°C.

[0107] Table 2 Reaction conditions, product purity and product batch yield of Examples 8 to 14

[0108]

[0109]

[0110] As can be seen from Table 2, the present invention uses bio-based succinic acid and alcohol compounds as raw materials, and prepares the target product bio-based 1,4-butanediol through esterification and hydrogenation reduction. The purity of the obtained bio-based 1,4-butanediol is ≥99.1%, the raw material conversion rate is ≥99.5%, and the 1,4-butanediol selectivity is ≥97.8%.

[0111] Example 9

[0112] The same as Example 1, the only difference is that the raw materials used in preparing the catalyst are 2.7 mol of copper nitrate hexahydrate, 1 mol of aluminum nitrate nonahydrate, and 0.7 mol of zinc nitrate hexahydrate.

[0113] Table 3 Reaction conditions, product purity and product batch yield of Examples 15 to 21

[0114]

[0115] As can be seen from Table 3, the present invention uses bio-based succinic acid and alcohol compounds as raw materials, and prepares the target product bio-based 1,4-butanediol through esterification and hydrogenation reduction. The purity of the obtained bio-based 1,4-butanediol is ≥99.1%, the raw material conversion rate is ≥99.5%, and the 1,4-butanediol selectivity is ≥97.8%.

[0116] And by comparing the data in Tables 1 to 3, it can be seen that the metal loading in the catalyst of the present invention is high, and the surface morphology and physicochemical properties of the supported copper catalyst can be changed by regulating the active metal ratio and the calcination temperature, so that the catalyst has a higher specific surface area, metal dispersion, suitable surface acidity and Cu + / Cu 0 Therefore, the catalytic hydrogenation of oligomer polyester can achieve lower hydrogenation pressure, lower hydrogenation temperature and lower hydrogen-ester ratio, further improving the conversion rate of oligomer polyester and the selectivity of 1,4-butanediol.

[0117] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing bio-based 1,4-butanediol, It is characterized in that The following steps are involved: The bio-based succinic acid and alcohol compounds are mixed and subjected to esterification reaction to obtain oligomeric polyester; The oligomer polyester is subjected to hydrogenation reduction under a catalyst to obtain a crude 1,4-butanediol product; the hydrogen reduction used in the hydrogenation reduction has a hydrogen-ester ratio of 80 to 200:1 to the oligomer polyester; the catalyst is a supported copper catalyst, and the supported copper catalyst is prepared by a method comprising the following steps: (1) mixing copper nitrate hexahydrate, aluminum nitrate nonahydrate, an active metal salt and water to obtain a metal ion salt solution, wherein the metal in the active metal salt is selected from magnesium, manganese, nickel, cobalt, zinc, cerium or zirconium; (2) mixing sodium hydroxide, sodium carbonate and water to obtain an alkali solution precipitation agent; (3) adding the metal ion salt solution and the alkali solution precipitant into a reactor at 60° C. to perform a precipitation reaction to obtain a precipitated product, and maintaining the pH of the reaction system at 8 to 10; (4) aging the precipitated product at 70° C. for 24 hours to obtain a ternary hydrotalcite-like substance; (5) calcining and activating the ternary hydrotalcite in sequence to obtain the supported copper catalyst; the calcination temperature is 500 to 600° C. and the time is 0.5 to 8 h; The crude 1,4-butanediol is purified to obtain the bio-based 1,4-butanediol.

2. The preparation method according to claim 1, It is characterized in that The alcohol compound is selected from one or more of butanol, pentanol, hexanol, ethylene glycol and 1,4-butanediol.

3. The preparation method according to claim 1 or 2, It is characterized in that The molar ratio of the bio-based succinic acid to the alcohol compound is 1:1.2-2.

4.

4. The preparation method according to claim 1 or 2, It is characterized in that The temperature of the esterification reaction is 160-210° C. and the time is 4-8 hours.

5. The preparation method according to claim 1, It is characterized in that The hydrogenation reduction is carried out under a pressure of 1 to 20 MPa, at a temperature of 100 to 220° C., for a time of 2 to 6 hours.

6. The preparation method according to claim 1, It is characterized in that The molar ratio of the copper nitrate hexahydrate, the metal in the active metal salt and the aluminum nitrate nonahydrate is 1-5:1:0.25-2.

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