Bio-based 1, 4-butanediol composition, preparation method thereof and polyester prepared from bio-based 1, 4-butanediol composition

Abstract

The invention provides a bio-based 1, 4-butanediol composition and a preparation method thereof, and polyester prepared from the bio-based 1, 4-butanediol composition, the bio-based 1, 4-butanediol composition comprises bio-based 1, 4-butanediol, an acidic compound, a nitrogen-containing compound and acetal; the content of acetal in the bio-based 1, 4-butanediol composition is less than or equal to 195ppm. According to the invention, polyester prepared by taking the bio-based 1, 4-butanediol composition as a raw material has a low color value and a low melt index.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyester preparation, and particularly relates to a bio-based 1,4-butanediol composition, a preparation method thereof, and a polyester prepared therefrom. Background Art

[0002] The preparation methods of bio-based 1,4-butanediol (abbreviated as 1,4-BDO) include a one-step method and a two-step method. The one-step method directly prepares 1,4-BDO from biomass through microbial fermentation. The two-step method first ferments biomass through microorganisms to produce bio-based succinic acid, and then prepares 1,4-BDO through a chemical reduction method. At present, it is a relatively common method to use bio-based succinic acid obtained by fermenting biomass sugars as a raw material, obtain dimethyl succinate through an esterification process, and then hydrogenate and reduce it to prepare bio-based 1,4-BDO.

[0003] However, bio-based succinic acid is derived from biomass raw materials and contains many trace impurity components. First, amino acids, proteins, ammonium salts, urea, and microorganisms will be introduced during the fermentation process to form nitrogen-containing compounds such as 2-pyrrolidone, succinimide, maleimide, N-methylpyrrolidone, etc.; second, miscellaneous acids such as formic acid, acetic acid, lactic acid, malic acid, and fumaric acid will be produced during the fermentation process. Therefore, when using bio-based succinic acid to prepare 1,4-BDO, it is easy to cause the nitrogen-containing impurities and acidic impurities in the intermediate product (i.e., succinic acid ester) and the final product 1,4-BDO to be too high. In addition, during the hydrogenation of dimethyl succinate, acetal 2-(4-hydroxybutoxy)-tetrahydrofuran (HBTHF) is easily produced, and HBTHF will azeotrope with 1,4-BDO during the distillation separation process and cannot be completely separated, resulting in a high content of HBTHF in 1,4-BDO.

[0004] The high content of nitrogen-containing impurities and acidic impurities in the intermediate product will affect the activity of the hydrogenation catalyst, cause the hydrogenation catalyst to be poisoned and inactivated, affect the hydrogenation reaction efficiency, and further affect the subsequent application of 1,4-BDO; the presence of nitrogen-containing impurities and acetal HBTHF in 1,4-BDO will affect the performance of the polyester, such as the polyester prepared being yellowish in color, or affecting the synthesis efficiency, the polyester prepared having a high melt index, being unable to prepare a high molecular weight polyester, and the obtained polyester having poor performance.

[0005] Therefore, developing a bio-based 1,4-butanediol that is beneficial to reducing the color value of the polyester and increasing the melt index of the polyester is an urgent problem to be solved in the art. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a bio-based 1,4-butanediol composition, a preparation method thereof, and a polyester prepared therefrom. The polyester prepared from the bio-based 1,4-butanediol composition as a raw material has a low color value and a low melt index.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a bio-based 1,4-butanediol composition, wherein the bio-based 1,4-butanediol composition comprises bio-based 1,4-butanediol, an acidic compound, a nitrogen-containing compound, and an acetal; the content of the acetal in the bio-based 1,4-butanediol composition is ≤ 195 ppm.

[0009] In the present invention, when the acetal content in the bio-based 1,4-butanediol composition is within a specific range, and the bio-based 1,4-butanediol composition is used as a raw material to prepare a polyester, the influence of the acetal on the polyester can be weakened, and the obtained polyester has a low color value and a low melt index, and its performance is better.

[0010] In the present invention, the content of the acetal in the bio-based 1,4-butanediol composition is ≤ 195 ppm. For example, it can be 10 ppm, 20 ppm, 50 ppm, 80 ppm, 100 ppm, 115 ppm, 118 ppm, 120 ppm, 122 ppm, 125 ppm, 128 ppm, 130 ppm, 132 ppm, 135 ppm, 138 ppm, 140 ppm, 142 ppm, 145 ppm, 148 ppm, 150 ppm, 152 ppm, 155 ppm, 158 ppm, 160 ppm, 162 ppm, 165 ppm, 168 ppm, 170 ppm, 172 ppm, 175 ppm, 178 ppm, 180 ppm, 182 ppm, 185 ppm, 188 ppm, 190 ppm, 192 ppm, 195 ppm, or a range composed of any of the above values; further preferably, the content of the acetal is 115 - 195 ppm, and more preferably, the content of the acetal is 115 - 170 ppm.

[0011] Preferably, the acetal includes 2-(4-hydroxybutoxy)-tetrahydrofuran.

[0012] Preferably, the content of nitrogen element in the bio - based 1,4 - butanediol composition is < 37 ppm, for example, it can be 0.01 ppm, 0.02 ppm, 0.05 ppm, 0.08 ppm, 0.1 ppm, 0.2 ppm, 0.3 ppm, 0.4 ppm, 0.5 ppm, 0.6 ppm, 0.7 ppm, 0.8 ppm, 0.9 ppm, 0.95 ppm, 1 ppm, 2 ppm, 4 ppm, 6 ppm, 8 ppm, 10 ppm, 12 ppm, 15 ppm, 18 ppm, 20 ppm, 22 ppm, 25 ppm, 28 ppm, 30 ppm, 32 ppm, 35 ppm or the range composed of any of the above values; preferably, the content of nitrogen element is < 21 ppm, and more preferably, the content of nitrogen element is < 1 ppm.

[0013] Preferably, the acid value of the bio - based 1,4 - butanediol composition is < 0.062 mgKOH / g, for example, it can be 0.001 mgKOH / g, 0.002 mgKOH / g, 0.005 mgKOH / g, 0.008 mgKOH / g, 0.01 mgKOH / g, 0.012 mgKOH / g, 0.014 mgKOH / g, 0.016 mgKOH / g, 0.018 mgKOH / g, 0.02 mgKOH / g, 0.022 mgKOH / g, 0.024 mgKOH / g, 0.026 mgKOH / g, 0.028 mgKOH / g, 0.03 mgKOH / g, 0.035 mgKOH / g, 0.04 mgKOH / g, 0.045 mgKOH / g, 0.05 mgKOH / g, 0.055 mgKOH / g or the range between any of the above values; further preferably, the acid value is < 0.03 mgKOH / g, and more preferably, the acid value is < 0.018 mgKOH / g.

[0014] Preferably, the mass percentage content of bio - based 1,4 - butanediol in the bio - based 1,4 - butanediol composition is > 99%, for example, it can be 99.2%, 99.4%, 99.6%, 99.8%, 99.82%, 99.84%, 99.86%, 99.88%, 99.9%, 99.92%, 99.94%, 99.96%, 99.98%, 99.99% or the range between any of the above values.

[0015] In the present invention, the acidic compound is derived from the miscellaneous acids generated during the fermentation process when preparing bio - based succinic acid, such as formic acid, acetic acid, lactic acid, malic acid, fumaric acid, etc.; the nitrogen - containing compound is derived from the amino acids, proteins, ammonium salts, urea, and microorganisms introduced during the fermentation process when preparing bio - based succinic acid; the acetal is derived from the product obtained by side reactions during the hydrogenation reaction when preparing bio - based 1,4 - butanediol.

[0016] In a second aspect, the present invention provides a method for preparing the bio - based 1,4 - butanediol composition described in the first aspect, and the preparation method includes the following steps:

[0017] (1) Esterify bio - based succinic acid with an alcohol to obtain a bio - based succinic acid ester;

[0018] (2) Subject the bio - based succinic acid ester obtained in step (1) to a hydrogenation reaction to obtain a crude product of the bio - based 1,4 - butanediol composition;

[0019] (3) Post - treat the crude product of the bio - based 1,4 - butanediol composition obtained in step (2) to obtain the bio - based 1,4 - butanediol composition; the post - treatment in step (3) includes pickling.

[0020] In the present invention, by pickling the hydrogenation product (i.e., the crude product of the bio - based 1,4 - butanediol composition), a bio - based 1,4 - butanediol composition with a low acetal content can be obtained, which is conducive to obtaining a polyester with a low color value and a low melt index.

[0021] Preferably, the alcohol in step (1) includes at least one of methanol, ethanol, propanol, or butanol.

[0022] Preferably, the molar ratio of the bio - based succinic acid to the alcohol in step (1) is (0.5 - 6):1, where the specific values in (0.5 - 6) can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.5, 5.8, or any range composed of the above - mentioned arbitrary values; more preferably (1 - 4):1.

[0023] Preferably, the esterification reaction in step (1) is carried out in the presence of a catalyst.

[0024] In the present invention, the catalyst used in the esterification reaction includes, but is not limited to, sulfonic acid resin.

[0025] In the present invention, the mass of the catalyst used in the esterification reaction is 1 - 4 wt% of the bio - based succinic acid.

[0026] Preferably, the temperature of the esterification reaction in step (1) is 100-130 °C, for example, it can be 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, 125 °C, 130 °C or the range composed of any of the above values.

[0027] In the present invention, the specific steps of the esterification reaction include: mixing biobased succinic acid and an alcohol in a molar ratio of (0.5-3):1, adding them to an autoclave, displacing with nitrogen, heating to 90-120 °C under stirring conditions, controlling the stirring speed at 100-300 r / min, and stirring for 0.5-2 h; obtaining a mixed solution; then cooling to 40-60 °C, continuously pumping the mixed solution into a rectification reactor equipped with an esterification catalyst through a metering pump, controlling the volume space velocity of the mixed solution at 1-3 h -1 , and at the same time continuously pumping the alcohol into the rectification reactor through a metering pump, controlling the volume space velocity of the alcohol at 0.5-2 h -1 , and completing the esterification reaction at 100-130 °C.

[0028] Preferably, after the esterification reaction in step (1), a first post-treatment is further included.

[0029] Preferably, the first post-treatment includes distillation purification and / or adsorption using an adsorption column.

[0030] Preferably, the gas phase temperature of the distillation purification is 125-145 °C, for example, it can be 130 °C, 132 °C, 134 °C, 136 °C, 138 °C, 140 °C or the range between any of the above values; the pressure is 40-65 KPa, for example, it can be 40 KPa, 42 KPa, 44 KPa, 46 KPa, 48 KPa, 50 KPa, 52 KPa, 54 KPa, 56 KPa, 58 KPa, 60 KPa or the range between any of the above values.

[0031] Preferably, the acid value of the biobased succinic acid ester obtained after the distillation purification is <0.3 mg KOH / g, for example, it can be 0.01 mg KOH / g, 0.05 mg KOH / g, 0.1 mg KOH / g, 0.12 mg KOH / g, 0.14 mg KOH / g, 0.16 mg KOH / g, 0.18 mg KOH / g, 0.2 mg KOH / g, 0.22 mg KOH / g, 0.24 mg KOH / g, 0.26 mg KOH / g, 0.28 mg KOH / g or the range composed of any of the above values.

[0032] Preferably, the adsorption includes sequentially passing through a first adsorbent and a second adsorbent for adsorption; the first adsorbent includes macroporous adsorption resin; the second adsorbent includes modified activated carbon.

[0033] Preferably, the modified activated carbon includes hydroxide-modified activated carbon.

[0034] Preferably, the hydroxide includes at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, or aluminum hydroxide.

[0035] Preferably, the adsorption temperature is 40 - 60 °C, for example, it can be 40 °C, 42 °C, 44 °C, 46 °C, 48 °C, 50 °C, 52 °C, 54 °C, 56 °C, 58 °C, 60 °C or the range between any of the above values; the pressure is 1 - 2 MPa, for example, it can be 1 MPa, 1.2 MPa, 1.4 MPa, 1.6 MPa, 1.8 MPa, 2 MPa or the range between any of the above values; the average residence time is 10 - 20 min, for example, it can be 10 min, 12 min, 14 min, 16 min, 18 min, 20 min or the range composed of any of the above values.

[0036] In the present invention, the macroporous adsorption resin can be obtained by commercial purchase; exemplarily, it includes but is not limited to Diaion WA-20, Amberlite IRA-68, Wofatit AP-9, D316, etc.

[0037] In the present invention, the modified activated carbon can be obtained by commercial purchase or prepared by conventional methods. The preparation method includes: pretreating the activated carbon with an acid solution, drying to obtain the acid-treated activated carbon; then, treating the acid-treated activated carbon with a hydroxide solution, washing and drying to obtain the modified activated carbon.

[0038] In the present invention, the particle size of the activated carbon is 30 - 60 mesh, for example, it can be 30 mesh, 32 mesh, 35 mesh, 38 mesh, 40 mesh, 42 mesh, 45 mesh, 48 mesh, 50 mesh, 52 mesh, 55 mesh, 58 mesh, 60 mesh or the range composed of any of the above values; the specific surface area is 500 - 1000 m 2 / g, for example, it can be 500 m 2 / g, 600 m 2 / g, 700 m 2 / g, 800 m 2 / g, 900 m 2 / g, 1000 m 2 / g or the range between any of the above values.

[0039] In the present invention, the specific surface area of the activated carbon can be obtained from the information provided by the manufacturer or measured by conventional methods, such as by using the BET adsorption method for testing.

[0040] In the present invention, based on 1 g of the mass of the activated carbon, the volume of the acid solution is 1 - 2 mL; the concentration of the acid solution is 1 - 5 mol / L, and the acid solution includes a nitric acid solution; the temperature of the pretreatment is 40 - 60 °C, and the time is 5 - 15 h.

[0041] In the present invention, based on 1 g of the mass of the activated carbon after acid treatment, the volume of the hydroxide solution is 1 - 2 mL; the concentration of the hydroxide solution is 1 - 5 mol / L; the temperature of the treatment is 40 - 60 °C, and the time is 1 - 10 h.

[0042] In the present invention, the macroporous adsorption resin is used to adsorb the heteropolyacid to control the content of the heteropolyacid in the bio - based 1,4 - butanediol composition within a specific range; the modified activated carbon is used to adsorb the nitrogen - containing compounds to control the content of the nitrogen - containing compounds in the bio - based 1,4 - butanediol composition within a specific range.

[0043] In the present invention, the adsorption column can be a series connection of an adsorption column filled with macroporous adsorption resin and an adsorption column filled with modified activated carbon; or the macroporous adsorption resin and the modified activated carbon can be filled into the same adsorption column, with the macroporous adsorption resin in the upper layer and the modified activated carbon in the lower layer, and the filling volume ratio of the two is 1:1.

[0044] Preferably, the nitrogen element content of the bio - based succinic acid ester obtained after adsorption < 40 ppm, for example, it can be 1 ppm, 2 ppm, 5 ppm, 8 ppm, 10 ppm, 12 ppm, 14 ppm, 16 ppm, 18 ppm, 20 ppm, 22 ppm, 24 ppm, 26 ppm, 28 ppm, 30 ppm, 32 ppm, 34 ppm, 36 ppm, 38 ppm or a range composed of any of the above values.

[0045] Preferably, the acid value of the bio - based succinic acid ester obtained after adsorption < 0.15 mgKOH / g, for example, it can be 0.01 mgKOH / g, 0.05 mgKOH / g, 0.1 mgKOH / g, 0.12 mgKOH / g, 0.14 mgKOH / g or a range composed of any of the above values.

[0046] Preferably, the temperature of the hydrogenation reaction in step (2) is 160 - 190 °C, for example, it can be 160 °C, 165 °C, 170 °C, 175 °C, 180 °C, 185 °C, 190 °C or a range composed of any of the above values.

[0047] Preferably, the pressure of the hydrogenation reaction in step (2) is 3 to 10 MPa, for example, it can be 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 5.2 MPa, 5.4 MPa, 5.6 MPa, 5.8 MPa, 6 MPa, 6.2 MPa, 6.4 MPa, 6.6 MPa, 6.8 MPa, 7 MPa, 7.5 MPa, 8 MPa, 8.5 MPa, 9 MPa, 9.5 MPa, 10 MPa or the range composed of any of the above values; more preferably 5 to 7 MPa.

[0048] Preferably, the space velocity of the hydrogenation reaction in step (2) is 0.1 to 0.4 h -1 , for example, it can be 0.1 h -1 , 0.15 h -1 , 0.2 h -1 , 0.25 h -1 , 0.3 h -1 , 0.35 h -1 , 0.4 h -1 or the range composed of any of the above values.

[0049] Preferably, in the hydrogenation reaction, the molar ratio of hydrogen to the bio-based succinic acid ester is (150 - 350):1, where the specific values in (150 - 350) can be, for example, 150, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340 or the range composed of any of the above values.

[0050] Preferably, the pickling includes mixing the crude product of the bio-based 1,4-butanediol composition with an acid for washing.

[0051] Preferably, the volume ratio of the crude product of the bio-based 1,4-butanediol composition to the acid is (18 - 30):1, where the specific values in (18 - 30) can be, for example, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or the range composed of any of the above values.

[0052] Preferably, the acid includes at least one of sulfuric acid, hydrochloric acid or nitric acid.

[0053] Preferably, the mass fraction of the acid is 0.01 - 0.5%, for example, it can be 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.48% or the range composed of any of the above values.

[0054] Preferably, the temperature of the pickling is 40 to 60 °C, for example, it can be 40 °C, 42 °C, 44 °C, 46 °C, 48 °C, 50 °C, 52 °C, 54 °C, 56 °C, 58 °C, 60 °C or the range composed of any of the above values; the time is 5 to 25 min, for example, it can be 5 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min or the range composed of any of the above values.

[0055] Preferably, the post-treatment in step (3) further includes vacuum rectification.

[0056] Preferably, the temperature of the vacuum rectification is 110 to 150 °C, for example, it can be 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, 150 °C or the range composed of any of the above values; the pressure is 0.5 to 2 KPa, for example, it can be 0.5 KPa, 0.6 KPa, 0.8 KPa, 1 KPa, 1.2 KPa, 1.4 KPa, 1.6 KPa, 1.8 KPa, 2 KPa or the range composed of any of the above values; more preferably, the temperature is 120 to 125 °C and the pressure is 0.5 to 0.9 KPa.

[0057] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0058] S1: Esterify biobased succinic acid with an alcohol at a temperature of 100 to 130 °C to obtain a first biobased succinic acid ester with an acid value < 2.0 mgKOH / g, which can be denoted as a crude succinic acid ester;

[0059] S2: Distill and purify the first biobased succinic acid ester obtained in S1 at a gas phase temperature of 125 to 145 °C and a pressure of 40 to 65 KPa to obtain a second biobased succinic acid ester with an acid value < 0.3 mgKOH / g;

[0060] S3: Adsorb the second biobased succinic acid ester obtained in S2 at a temperature of 40 to 60 °C, a pressure of 1 to 2 MPa, and an average residence time of 10 to 20 min through a macroporous adsorption resin and a modified activated carbon in sequence to obtain a third biobased succinic acid ester with an acid value < 0.15 mgKOH / g and a nitrogen element content < 40 ppm, which can be denoted as a refined succinic acid ester;

[0061] S4: Carry out a hydrogenation reaction on the third biobased succinic acid ester obtained in S3 at a temperature of 160 to 190 °C, a pressure of 3 to 10 MPa, and a volume space velocity of 0.1 to 0.4 h-1 to obtain a crude product of a biobased 1,4-butanediol composition;

[0062] S5: Mix the crude product of the bio - based 1,4 - butanediol composition obtained in S4 with an acid at a volume ratio of (10 - 30):1 at a temperature of 40 - 60 °C for 5 - 25 min, and then perform vacuum distillation at a temperature of 110 - 150 °C and a pressure of 0.5 - 2 KPa to obtain the bio - based 1,4 - butanediol composition.

[0063] In a third aspect, the present invention provides a polyester, and the raw materials for preparing the polyester include a dicarboxylic acid and a diol; the diol includes the bio - based 1,4 - butanediol composition described in the first aspect.

[0064] In the present invention, the dicarboxylic acid includes an aromatic dicarboxylic acid and / or an aliphatic dicarboxylic acid; the aromatic dicarboxylic acid includes at least one of terephthalic acid, phthalic acid, or isophthalic acid; the aliphatic dicarboxylic acid includes a C4 - C20 aliphatic dicarboxylic acid; for example, it can be a C4, C5, C6, C8, C10, C12, C14, C16, C18, C20 aliphatic dicarboxylic acid, etc.; exemplarily, the aliphatic dicarboxylic acid includes at least one of succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, or octadecanedioic acid.

[0065] In the present invention, the raw materials for preparing the polyester further include other diols, exemplarily, including pentanediol, hexanediol, decanediol, etc.

[0066] In the present invention, the polyester can be prepared by a conventional technical method in the art. Exemplarily, the method includes the following steps:

[0067] In the presence of a protective atmosphere, esterify a part of the dicarboxylic acid and the diol at 200 - 230 °C for 1 - 3 h, then add the remaining dicarboxylic acid thereto, react at 220 - 260 °C for 1 - 3 h, then add a catalyst and a stabilizer thereto, and reduce the system pressure to below 50 Pa, and react at 230 - 270 °C for 2 - 6 h to obtain the polyester.

[0068] In the present invention, the molar ratio of the dicarboxylic acid to the diol in the preparation method is 1:(3 - 8); the catalyst includes but is not limited to titanium compounds (such as tetra - n - butyl titanate); the molar content of the catalyst is 1 - 5% of the total molar amount of the dicarboxylic acid and the diol; the stabilizer includes but is not limited to phosphate compounds (such as triphenyl phosphate), and the molar content of the stabilizer is 0.5 - 4.5% of the total molar amount of the dicarboxylic acid and the diol.

[0069] Preferably, the color value (b value) of the polyester ≤ 5.5.

[0070] Preferably, the melt index of the polyester ≤ 10 g / 10 min.

[0071] The numerical ranges described in the present invention include not only the above-listed point values, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the described ranges.

[0072] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0073] The bio-based 1,4-butanediol composition provided by the present invention controls the content of acetal in the bio-based 1,4-butanediol composition ≤ 195 ppm. The polyester prepared from the bio-based 1,4-butanediol composition has a low color value and a low melt index, and has better performance; and it is beneficial to simplify the process and reduce costs. Detailed Embodiments

[0074] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0075] The materials used in the present invention can all be obtained through commercial purchase or prepared by conventional methods. Unless otherwise specified, the materials used in the present invention are as follows:

[0076] Bio-based 1,4-butanedioic acid: purity ≥ 99%, nitrogen element content ≥ 450 ppm, Shanghai Macklin Biochemical Co., Ltd.

[0077] Methanol: purity ≥ 99.8%, Sinopharm Chemical Reagent Co., Ltd.

[0078] Terephthalic acid: purity ≥ 99.0%, Jiangsu Runfeng Synthetic Technology Co., Ltd.

[0079] Adipic acid: purity ≥ 99.8%, Jiangsu Runfeng Synthetic Technology Co., Ltd.

[0080] Macroporous adsorption resin: D316, Hebei Lijiang Biotechnology Co., Ltd.

[0081] Sodium hydroxide-modified activated carbon (C1): self-made, the preparation method includes: 200 g of commercially available granular activated carbon (particle size 30 - 60 mesh, specific surface area 500 - 1000 m 2( / g, manufactured by Ningxia Tingyuan Fruit Wood Energy Technology Co., Ltd.) was added to a glass reaction flask, and then 300 mL of a nitric acid solution with a concentration of 2 mol / L was slowly added. After complete addition, the temperature was raised to 50 °C and continuously stirred for 10 h. After standing, filtering, washing, and drying; 300 mL of a sodium hydroxide solution with a concentration of 2 mol / L was added to the acid-treated activated carbon, the temperature was raised to 50 °C, and continuously stirred for 5 h. After standing, filtering, washing, and drying, sodium hydroxide-modified activated carbon was obtained (specific surface area is 1500 - 1800 m 2 / g).

[0082] Sodium carbonate-zinc sulfate composite-modified activated carbon (C2): The difference in its preparation method from that of sodium hydroxide-modified activated carbon is only that 200 g of acid-treated activated carbon and 300 mL of an aqueous zinc sulfate solution (20%) were continuously stirred at 60 °C for 12 h. After standing, filtering, washing, and drying, then 300 mL of a sodium carbonate solution with a concentration of 2 mol / L was added, the temperature was raised to 50 °C, and continuously stirred for 5 h. After standing, filtering, washing, and drying, sodium carbonate-zinc sulfate composite-modified activated carbon was obtained (specific surface area is 800 - 1100 m 2 / g).

[0083] Granular activated carbon (C3), which is the above-mentioned unmodified commercially available granular activated carbon (particle size is 30 - 60 mesh, specific surface area is 500 - 1000 m 2 / g, manufactured by Ningxia Tingyuan Fruit Wood Energy Technology Co., Ltd.).

[0084] In the present invention, the test method for acid value includes: referring to GB / T 6365 - 2006, quantitative analysis is carried out by titration method, using phenolphthalein solution as the indicator and potassium hydroxide standard solution as the titrant. Weigh a certain amount of sample into a conical flask and add ethanol solution to completely dissolve it. Add the indicator, and titrate with potassium hydroxide standard solution until it turns light pink and remains for 30 s. At the same time, do a blank experiment with ethanol solution. The acid value (mg KOH / g) is calculated by the formula (V - V0)c×56.11 / m, where V and V0 are the volumes (mL) of potassium hydroxide standard solution consumed by the test sample and blank ethanol respectively, c is the concentration (mol / L) of potassium hydroxide standard solution, and m is the mass (g) of the test sample.

[0085] The test method for nitrogen element content includes: referring to SH / T 0657 - 2007, quantitative analysis is carried out by combustion - chemiluminescence method. Prepare a standard solution of carbazole solution, the injection volume is 50 μL, establish a standard curve, and calculate the content of nitrogen element through the standard curve. The detection limit of nitrogen element content is 1 ppm, and those with detection results lower than 1 ppm are uniformly recorded as <1 ppm.

[0086] The test methods for the content of acetal and bio - based 1,4 - butanediol include: referring to GB / T 24768 - 2009, quantitative analysis is carried out by gas chromatography. Standard solutions of 1,4 - BDO and acetal are prepared, the correction factors of acetal and impurities relative to 1,4 - BDO are tested, the correction factor of unknown impurities is taken as 1, and the contents of acetal and 1,4 - BDO are calculated by correcting the integral area.

[0087] Example 1

[0088] This example provides a bio - based 1,4 - butanediol composition. The preparation method of the bio - based 1,4 - butanediol composition includes the following steps:

[0089] (1) Bio - based 1,4 - butanedioic acid and methanol are mixed at a molar ratio of 3:1, then added to an autoclave. After nitrogen replacement, it is heated to 110 °C under stirring conditions, the stirring speed is controlled at 200 r / min, and the stirring time is 1 h to obtain a mixed solution; then it is cooled to 50 °C, and the mixed solution is continuously pumped into a rectifying reactor (including a top condenser, a reaction column, and a bottom receiving bottle) equipped with an esterification catalyst (sulfonic acid resin, with a mass of 4 wt% of bio - based 1,4 - butanedioic acid; DT - 01) through a metering pump. The volume space velocity of the mixed solution is controlled at 2 h -1 , and at the same time, methanol is continuously pumped into the rectifying reactor through a metering pump, and the volume space velocity of methanol is controlled at 1 h -1 , and the reaction is carried out at 120 °C to obtain dimethyl succinate, denoted as crude dimethyl succinate.

[0090] (2) The crude dimethyl succinate obtained in step (1) is distilled and purified. The gas phase temperature is controlled at 140 °C and the pressure is 50 KPa. The fraction after the gas phase temperature and pressure are stable is taken to obtain dimethyl succinate after distillation and purification, denoted as dimethyl succinate.

[0091] (3) The dimethyl succinate obtained in step (2) is passed into an adsorption column filled with an adsorbent. The average residence time is 15 min, the temperature is 50 °C, and the pressure is 1.5 MPa. The volume ratio of the upper and lower bed layers of the adsorption column is 1:1. The upper layer is macroporous adsorption resin and the lower layer is sodium hydroxide - modified activated carbon to obtain adsorbed dimethyl succinate, denoted as refined dimethyl succinate.

[0092] (4) The refined dimethyl succinate obtained in step (3) is continuously pumped into a fixed - bed hydrogenation reactor through a metering pump. The reaction temperature is 170 °C, the pressure is 6 MPa, and the volume space velocity is 0.2 h -1 , and the molar ratio of hydrogen to refined dimethyl succinate is 200:1 to obtain crude bio - based 1,4 - butanediol.

[0093] (5) Mix the crude bio - based 1,4 - butanediol obtained in step (4) with a sulfuric acid aqueous solution with a mass fraction of 0.1% at a volume ratio of 25:1, stir, with the temperature at 45 °C and the time at 15 min; then pass the pickled material into a distillation column, control the vacuum degree at 0.5 KPa and the temperature at 120 °C, take the middle - section fraction to obtain the bio - based 1,4 - butanediol composition; the mass percentage content of bio - based 1,4 - butanediol in the bio - based 1,4 - butanediol composition is 99.88%; the acid value of the bio - based 1,4 - butanediol composition is 0.015 mgKOH / g, the nitrogen element content < 1 ppm, and the content of 2 - (4 - hydroxybutoxy) - tetrahydrofuran (HBTHF), an acetal, is 66 ppm.

[0094] Examples 2 - 15 and Comparative Examples 1 - 2 respectively provide a bio - based 1,4 - butanediol composition, the differences from Example 1 being only the mass percentage content of bio - based 1,4 - butanediol, acid value, nitrogen element content, HBTHF content and process parameters of each step; the specific parameters are shown in Tables 1 - 3; among them, " / " indicates the absence of this component or the non - performance of this step; "Δ" indicates the presence of this component; it should be noted that when the adsorption step of step (3) is not carried out, the dimethyl succinate obtained in step (2) is the refined dimethyl succinate, and the acid value and nitrogen element content of the refined dimethyl succinate in the table are the acid value and nitrogen element content of the dimethyl succinate obtained in step (2).

[0095] Table 1

[0096]

[0097]

[0098] Table 2

[0099]

[0100]

[0101] Table 3

[0102]

[0103]

[0104] Example 16

[0105] This embodiment provides a bio - based 1,4 - butanediol composition. The preparation method includes: subjecting the bio - based 1,4 - butanediol composition obtained in Example 1 to pickling and rectification again, that is, performing step (5) of Example 1 on the bio - based 1,4 - butanediol composition obtained in Example 1 to obtain the bio - based 1,4 - butanediol composition. In the bio - based 1,4 - butanediol composition, the mass content of bio - based 1,4 - butanediol is 99.97%, the acid value of the bio - based 1,4 - butanediol composition is 0.011 mgKOH / g, the nitrogen element content is <1 ppm, and the content of 2 - (4 - hydroxybutoxy) - tetrahydrofuran (HBTHF), an acetal, is 85 ppm.

[0106] Application Example

[0107] A PBAT resin, the preparation method of the PBAT resin includes:

[0108] Put terephthalic acid (PTA) and bio - based 1,4 - butanediol (1,4 - BDO) into a reaction kettle according to the stoichiometric molar ratio n(PTA):n(1,4 - BDO)=1:2.8. After purging with nitrogen, continuously heat up to 220 °C for an esterification reaction for 2 h; then add a measured amount of adipic acid (AA), with the molar ratio n(AA):n(1,4 - BDO)=1:2.8, heat up to 240 °C and continue the reaction for 2 h, add a measured amount of catalyst tetra - n - butyl titanate (TNBT), n(TNBT):n(AA)=0.25:1, add stabilizer triphenyl phosphate (TPP), n(TPP):n(AA)=0.2:1, then reduce the pressure in the reaction kettle to below 50 Pa, continue the reaction at 250 °C for 3 h, then stop stirring, fill the reaction kettle with high - purity nitrogen, extrude the resin from the reaction kettle and pelletize to obtain the PBAT resin. The bio - based 1,4 - butanediol is respectively the bio - based 1,4 - butanediol compositions provided in Examples 1 - 16 and Comparative Examples 1 - 2.

[0109] Performance Test

[0110] (1) Color value: The test method is carried out according to the provisions in 5.5.2 of GB / T 14190 - 2017, and the CIE1976L*a*b color system is used as the result. The specific steps are as follows: Set the automatic color difference meter to a 10°

[0111] viewing angle, D65 light source, CIE L*a*b color system. Put the polyester particles into a sample cup and gently shake the sample cup to make the PBAT sample stack tightly. Place the sample cup on the measuring hole of the automatic color difference meter and measure the color value of PBAT. Test once every 120° rotation, and a total of three measurement values are tested.

[0112] Take the average of the three measurement values as the test result. Retain three significant figures for the L value, and two significant figures for the a value and b value. The b value mainly reflects the yellowness of the polyester.

[0113] (2) Melt Index: The test method is carried out according to Method A in GB / T 3682.1-2018. The test conditions are D (temperature: 190 °C, load: 2.16 kg). The specific steps are as follows: Set the MFR measuring instrument to 190 °C and stabilize for at least 15 min. Load an appropriate amount of dry polyester particles into the melt indexer. After preheating for 4 min, increase the total piston load to 2.16 Kg. Let the piston descend under the action of gravity until a thin strip without bubbles is extruded. Collect the 10 mm - 20 mm polyester thin strips cut within the set time before the marking line on the piston rod reaches the upper edge of the barrel. It is preferably 3 or more. After cooling, weigh them separately and accurately to 1 mg, and calculate the average mass. If the length of the thin strip is not within the range of 10 - 20 mm, the cutting interval time needs to be adjusted and the test is carried out again.

[0114] The specific test results are shown in Table 4.

[0115] Table 4

[0116] Color value (b value) Melt index (g / 10min) Example 1 3.6 6.8 Example 2 4.1 7.2 Example 3 3.5 6.7 Example 4 3.9 6.9 Example 5 3.8 7.0 Example 6 3.7 7.0 Example 7 4.2 7.5 Example 8 4.7 7.9 Example 9 4.9 8.7 Example 10 4.0 7.0 Example 11 4.2 7.5 Example 12 4.2 7.7 Example 13 4.9 7.0 Example 14 5.4 8.1 Example 15 5.2 8.8 Example 16 3.5 6.6 Comparative Example 1 8.8 11.4 Comparative Example 2 10.2 13.7

[0117] As can be seen from Table 4, for the bio-based 1,4-butanediol composition provided by the present invention, the content of acetal in the bio-based 1,4-butanediol composition is controlled ≤ 195 ppm. The polyester prepared from the bio-based 1,4-butanediol composition has a low color value and a low melt index; the color value (b value) of the polyester ≤ 5.5, the melt index ≤ 10 g / 10 min, and it is also beneficial to reduce costs and simplify the process; as can be seen from Example 16, when the content of acetal is too low, it has no obvious effect on reducing the b value and melt index, but it will lead to a complex process and increased costs.

[0118] The above specific embodiments have further detailed the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A bio-based 1,4-butanediol composition, characterized in that: The bio-based 1,4-butanediol composition comprises bio-based 1,4-butanediol, an acidic compound, a nitrogen-containing compound and acetal; The acetal content in the bio-based 1,4-butanediol composition is ≤195 ppm.

2. The bio-based 1,4-butanediol composition according to claim 1, characterized in that The acetal content in the bio-based 1,4-butanediol composition is 115 to 195 ppm, more preferably the acetal content is 115 to 170 ppm; Preferably, the acetal comprises 2-(4-hydroxybutoxy)-tetrahydrofuran.

3. The bio-based 1,4-butanediol composition according to claim 1 or 2, characterized in that: The nitrogen content of the bio-based 1,4-butanediol composition is less than 37 ppm, preferably less than 21 ppm, and more preferably less than 1 ppm; Preferably, the acid value of the bio-based 1,4-butanediol composition is less than 0.062 mgKOH / g, more preferably less than 0.03 mgKOH / g, and more preferably less than 0.018 mgKOH / g; Preferably, the mass percentage of bio-based 1,4-butanediol in the bio-based 1,4-butanediol composition is greater than 99%.

4. A method for preparing a bio-based 1,4-butanediol composition according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) subjecting bio-based succinic acid to an esterification reaction with alcohol to obtain a bio-based succinic acid ester; (2) subjecting the bio-based succinate obtained in step (1) to a hydrogenation reaction to obtain a crude product of a bio-based 1,4-butanediol composition; (3) post-treating the crude product of the bio-based 1,4-butanediol composition obtained in step (2) to obtain the bio-based 1,4-butanediol composition; The post-treatment in step (3) includes pickling.

5. The preparation method according to claim 4, characterized in that: The alcohol in step (1) includes at least one of methanol, ethanol, propanol or butanol; Preferably, the molar ratio of the bio-based succinic acid to the alcohol in step (1) is (0.5-6):1, more preferably (1-4):1; Preferably, the esterification reaction in step (1) is carried out in the presence of a catalyst; Preferably, the temperature of the esterification reaction in step (1) is 100-130°C.

6. The preparation method according to claim 4 or 5, characterized in that: After the esterification reaction in step (1), a first post-treatment is also included; Preferably, the first post-treatment includes distillation purification and / or adsorption using an adsorption column; Preferably, the gas phase temperature of the distillation purification is 125-145°C and the pressure is 40-65KPa; Preferably, the acid value of the bio-based succinate obtained after distillation and purification is less than 0.3 mgKOH / g; Preferably, the adsorption comprises sequentially adsorbing through a first adsorbent and a second adsorbent; the first adsorbent comprises a macroporous adsorption resin; the second adsorbent comprises modified activated carbon; Preferably, the modified activated carbon comprises hydroxide-modified activated carbon; Preferably, the hydroxide comprises at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide or aluminum hydroxide; Preferably, the adsorption temperature is 40-60°C, the pressure is 1-2MPa, and the average residence time is 10-20min; Preferably, the nitrogen content of the bio-based succinate obtained after the adsorption is less than 40 ppm; Preferably, the acid value of the bio-based succinate obtained after the adsorption is less than 0.15 mgKOH / g.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The temperature of the hydrogenation reaction in step (2) is 160-190°C; Preferably, the pressure of the hydrogenation reaction in step (2) is 3 to 10 MPa, more preferably 5 to 7 MPa; Preferably, the volume space velocity of the hydrogenation reaction in step (2) is 0.1 to 0.4 h -1 ; Preferably, in the hydrogenation reaction, the molar ratio of hydrogen to bio-based succinate is (150-350):

1.

8. The preparation method according to any one of claims 4 to 7, characterized in that: The acid washing comprises mixing the crude product of the bio-based 1,4-butanediol composition with an acid for washing; Preferably, the volume ratio of the crude product of the bio-based 1,4-butanediol composition to the acid is (18-30):1; Preferably, the acid comprises at least one of sulfuric acid, hydrochloric acid or nitric acid; Preferably, the mass fraction of the acid is 0.01 to 0.5%; Preferably, the pickling temperature is 40-60°C and the time is 5-25 minutes; Preferably, the post-treatment in step (3) further comprises vacuum distillation; Preferably, the temperature of the vacuum distillation is 110-150° C. and the pressure is 0.5-2 KPa, more preferably the temperature is 120-125° C. and the pressure is 0.5-0.9 KPa.

9. The preparation method according to any one of claims 4 to 8, characterized in that: The preparation method comprises the following steps: S1: esterifying bio-based succinic acid with alcohol at a temperature of 100 to 130° C. to obtain a first bio-based succinic acid ester with an acid value of less than 2.0 mgKOH / g; S2: distilling and purifying the first bio-based succinate obtained in S1 at a gas phase temperature of 125 to 145° C. and a pressure of 40 to 65 KPa to obtain a second bio-based succinate with an acid value of less than 0.3 mgKOH / g; S3: The second bio-based succinate obtained in S2 is sequentially adsorbed by a macroporous adsorption resin and a modified activated carbon at a temperature of 40 to 60° C., a pressure of 1 to 2 MPa, and an average residence time of 10 to 20 min to obtain a third bio-based succinate having an acid value of less than 0.15 mgKOH / g and a nitrogen content of less than 40 ppm; S4: The third bio-based succinate obtained in S3 is heated to 160-190°C, 3-10 MPa, and a volume space velocity of 0.1-0.4 h -1 A hydrogenation reaction is carried out under the following conditions to obtain a crude product of a bio-based 1,4-butanediol composition; S5: The crude product of the bio-based 1,4-butanediol composition obtained in S4 is mixed with an acid at a temperature of 40 to 60° C. for 5 to 25 minutes in a volume ratio of (10 to 30):1, and then vacuum distilled at a temperature of 110 to 150° C. and a pressure of 0.5 to 2 KPa to obtain the bio-based 1,4-butanediol composition.

10. A polyester, characterized in that The raw materials for preparing the polyester include dibasic acid and diol; the diol includes the bio-based 1,4-butanediol composition according to any one of claims 1 to 3; Preferably, the color value b value of the polyester is ≤5.5; Preferably, the melt index of the polyester is ≤10 g / 10 min.

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