Method and process system for preparing polysuccinate polyester by using maleic anhydride and / or derivatives thereof as raw materials

Abstract

The invention provides a method and a process system for preparing polysuccinate polyester by using maleic anhydride and / or a derivative thereof as raw materials, which are characterized in that a solid acid supported metal bifunctional catalyst and a fixed bed continuous reaction process are adopted, and maleic anhydride and / or the derivative thereof are subjected to polymerization reaction in the presence or absence of copolymerized polybasic acid and / or the derivative thereof to obtain the polysuccinate polyester. And carrying out hydrogenation-esterification / ester exchange coupling reaction on the polyhydric alcohol to prepare a polyester precursor in one step, and carrying out polycondensation on the polyester precursor under the action of a polymerization catalyst to prepare the polysuccinate polyester. According to the invention, the polysuccinate is prepared from maleic anhydride and / or a derivative thereof through two-step cascade reaction, so that the step of preparing succinic acid and derivative monomers thereof and then synthesizing a polyester precursor in the prior art is omitted; raw materials are cheap and easy to obtain, the technological process is short, and material consumption and energy consumption are low; a polymerization catalyst is less in dosage, and polyester products are high in quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of biodegradable polyester plastic precursors and polyester preparation, and particularly relates to a method and a process system for preparing polybutyrate polyesters using maleic anhydride and / or its derivatives as raw materials. Background Art

[0002] Polybutyrate polyesters, such as polyethylene succinate (PES), polybutylene succinate (PBS), poly(2,5-furandimethanol succinate) (PFS), poly(ethylene succinate-co-butylene succinate) (PBES), poly(butylene succinate-co-2,5-furandimethanol succinate) (PBFS), poly(butylene succinate-co-adipic acid) (PBSA), poly(butylene succinate-co-terephthalic acid) (PBST), etc., are a class of biodegradable plastics with excellent properties and great development potential. The existing synthesis methods include succinic acid esterification polycondensation method, succinic anhydride ring-opening polycondensation method, and succinic acid ester transesterification polycondensation method.

[0003] The succinic acid esterification polycondensation method uses succinic acid and polyols as the main monomer raw materials. With or without the addition of a third monomer, polybutyrate polyesters are obtained through esterification and polycondensation. However, this method has problems such as low esterification reaction rate, incomplete reaction of acid monomers such as succinic acid, a large amount of by-products such as tetrahydrofuran generated by the cycloetherification of alcohol monomers such as 1,4-butanediol, and a large amount of wastewater generated by the esterification-polycondensation reaction. These problems lead to low raw material utilization rate, high raw material consumption and energy consumption, low product yield, large amount of wastewater, and high treatment cost, increasing the production cost of the polyester.

[0004] The succinic acid ester transesterification polycondensation method uses succinic acid esters such as dimethyl ester and polyols as the main monomer raw materials. With or without the participation of a third monomer, polybutyrate polyesters are synthesized through transesterification and polycondensation reactions. Since one of the monomer raw materials for the transesterification method is succinic acid ester, succinic acid ester needs to be synthesized first, and a large amount of small molecules such as methanol are generated during the transesterification process. Compared with the succinic acid esterification polycondensation method, its synthesis route is longer, the raw material utilization rate is lower, and the raw material consumption, energy consumption, and production cost are higher.

[0005] The recently reported ring-opening polycondensation method of succinic anhydride, that is, the ring-opening polycondensation of succinic anhydride with polyols or / and a third monomer to synthesize polybutylene succinate, such as patents CN114015026B and CN113980252B. Since it does not require succinic acid monomers of the esterification method or succinic acid ester monomers of the transesterification method, but uses succinic anhydride prepared by one-step high-selectivity hydrogenation of maleic anhydride as the monomer, it shortens the monomer preparation process, reduces the monomer manufacturing cost, and there is no chemical equilibrium in the ring-opening esterification reaction, with a high esterification rate and fast speed. The amount of small-molecule substances (water or alkanol) generated during the esterification polycondensation to synthesize polyester is reduced by at least half, and the monomer raw material consumption is low. Therefore, compared with the succinic acid esterification polycondensation method and the succinic acid ester transesterification polycondensation method, the synthesis of polyester by the ring-opening polycondensation method of succinic anhydride has been greatly improved in terms of both clean production and process control, as well as product quality and production cost.

[0006] At present, as biodegradable plastics, the excellent properties of polybutylene succinate polyesters have been widely recognized. However, due to their production costs and selling prices still being much higher than those of traditional plastics such as PP and PE, there are still obstacles to large-scale popularization and application, and the market acceptance is still low. Reducing the manufacturing cost of polybutylene succinate has become a key factor for its replacement of traditional plastics and the realization of large-scale production and application. Improving and optimizing the monomer and polyester manufacturing technologies alone has limited room for reducing the polyester manufacturing cost. In order to further reduce the comprehensive manufacturing cost of polyester, it is necessary to carry out an integrated innovation of the overall process from the manufacture of raw materials to the manufacture of polyester. Synthesizing polyester precursors directly from basic raw materials in one step, avoiding the cumbersome processes of traditional monomer synthesis, separation and purification, and monomer esterification or transesterification polycondensation to synthesize polyester, can greatly shorten the process flow and reduce the polyester manufacturing cost. Therefore, integrating a green, efficient, and low-cost overall synthesis process of precursor butylene succinate polyols starting from maleic anhydride and polyester material polybutylene succinate polyols is of great significance for minimizing the manufacturing cost of biodegradable polybutylene succinate polyesters.

[0007] There are the following several combination schemes for the existing polybutylene succinate synthesis process routes starting from maleic anhydride:

[0008] A1. The direct esterification polycondensation process of maleic anhydride via monomer succinic acid:

[0009] A11. The three-step method of maleic anhydride hydrogenation-hydrolysis, esterification, and polycondensation: Maleic anhydride is hydrogenated in one step in an aqueous phase to prepare succinic acid (CN111689845B); succinic acid is esterified with polyols to prepare precursor butylene succinate polyols, and the precursor is then polycondensed to synthesize polybutylene succinate (CN102443149B, CN102007159B).

[0010] A12. Four-step process of maleic anhydride hydrogenation, hydrolysis, esterification, and polycondensation: maleic anhydride is hydrogenated to prepare succinic anhydride (CN113045519B); succinic anhydride is hydrolyzed to prepare succinic acid (CN102311332B); succinic acid is esterified with a polyol to prepare a precursor succinic acid polyol ester, and the precursor is then polycondensed to synthesize a polybutylene succinate (CN102443149B, CN102007159B).

[0011] A13. Four-step process of maleic anhydride hydrolysis, hydrogenation, esterification, and polycondensation: maleic anhydride is hydrolyzed to prepare maleic acid, and maleic acid is hydrogenated to prepare succinic acid (CN102417445A); succinic acid is esterified with a polyol to prepare a precursor succinic acid polyol ester, and the precursor is then polycondensed to synthesize a polybutylene succinate (CN102443149B, CN102007159B).

[0012] A14. Six-step process of maleic anhydride monoesterification, diesterification, hydrogenation, hydrolysis, esterification, and polycondensation: maleic anhydride is successively monoesterified to prepare maleic acid monoester, diesterified to prepare maleic acid diester, and the double bond is hydrogenated to prepare succinic acid diester (CN110563933B); succinic acid diester is hydrolyzed to prepare succinic acid (CN102746138B); succinic acid is esterified with a polyol to prepare a precursor succinic acid polyol ester, and the precursor is then polycondensed to synthesize a polybutylene succinate (CN102443149B, CN102007159B).

[0013] A2. Transesterification polycondensation process of maleic anhydride via monomer succinic acid diester:

[0014] A21. Four-step process of maleic anhydride hydrogenation, esterification, transesterification, and polycondensation: the double bond of maleic anhydride is hydrogenated to prepare succinic anhydride, succinic anhydride is esterified with a monohydric alcohol to prepare succinic acid diester, succinic acid diester is transesterified with a polyol to prepare a precursor succinic acid polyol ester, and the precursor is then polycondensed to synthesize a polybutylene succinate (CN112694602B).

[0015] A22. Five-step process of maleic anhydride monoesterification, diesterification, hydrogenation, transesterification, and polycondensation: maleic anhydride is successively monoesterified to prepare maleic acid monoester, diesterified to prepare maleic acid diester, the double bond is hydrogenated to prepare succinic acid diester, succinic acid diester is transesterified with a polyol to prepare a precursor succinic acid polyol ester, and the precursor is then polycondensed to synthesize a polybutylene succinate (CN113512183A).

[0016] A3. Ring-opening polycondensation process of maleic anhydride via monomer succinic anhydride:

[0017] The three-step method of maleic anhydride hydrogenation, esterification and polycondensation: maleic anhydride is hydrogenated to succinic anhydride (CN113045519B), succinic anhydride is subjected to ring-opening esterification with polyols or / and cyclic ethers to prepare the precursor succinic acid polyol ester, and the precursor is then polycondensed to synthesize polybutyrate (CN114015026B, CN113980252B and CN114920916A).

[0018] It can be seen that for the above six technical routes for synthesizing polybutyrate starting from maleic anhydride, succinic acid, succinic anhydride or dimethyl succinate and other monomers are first prepared, and then the precursor is prepared by esterification or transesterification reaction of these monomers with polyols or / and cyclic ethers, and then the polybutyrate is prepared by polycondensation of the precursor; moreover, all routes have the following disadvantages: 1) The process flow is long, and 3 to 6 steps of reaction are required to synthesize the polyester; 2) The selectivity of hydrogenation to prepare acidic monomers is low, and some even use co-production processes; 3) When esterification / transesterification polycondensation is used to synthesize the polyester, some alcohol monomers are converted into cyclic etherification and enolization by-products, and a large amount of wastewater is generated; 4) The polymerization catalyst is easily hydrolyzed and inactivated, resulting in a large amount of its use, a large amount of metal residues in the polyester, affecting the product quality and limiting its scope of use; 5) The raw material utilization rate is low, the material and energy consumption are high, and a large number of small molecules such as water or methanol are generated, increasing the manufacturing cost of polybutyrate.

[0019] Patent CN112920385A provides a method for preparing polybutylene succinate and its copolymers. 1,4-butanediol, copolymer dibasic acid, an esterification catalyst and a hydrogenation catalyst are added to a pressure reactor. When the hydrogen pressure no longer decreases during the reaction, the hydrogenation catalyst is filtered out to obtain an esterification and hydrogenation product. After the esterification and hydrogenation product removes wastewater and tetrahydrofuran, it is transferred to a polycondensation reactor, and a polycondensation catalyst is added for vacuum polycondensation reaction to obtain polybutylene succinate and its copolymers. However, the overall process of the method in this patent adopts a batch process, which requires multiple material transfers and gas replacements during the process. Especially, the esterification and hydrogenation reaction adopts a batch kettle process, and operations such as feeding, discharging, filtering, pressurizing, depressurizing, and purging must be carried out frequently. This not only makes the operation cumbersome, restricts the large-scale of the device and limits the production capacity, but also causes a large waste of hydrogen, nitrogen, and catalyst, resulting in high consumption. At the same time, there are great potential safety hazards. In addition, the method in this patent has poor effects and lacks practical operability. First, the esterification catalyst uses a metal organic or chloride catalyst with extremely weak acidity and easy hydrolysis. In the examples, tetrabutyl titanate, zirconium acetylacetonate or lanthanum acetylacetonate with a total raw material mass of 500 - 800 ppm is used. This will inevitably lead to a large amount of esterification catalyst consumption, low efficiency and non-recovery, long esterification reaction time, and low esterification rate. As a result, the esterification product contains a large amount of small molecules with higher boiling points such as succinic acid and its alkyl esters, acetylpyruvic acid and its alkyl esters or hydroxyalkyl esters (esters formed by hydrolysis of maleic anhydride hydrogenation product succinic anhydride and alkanols formed by hydrolysis of the catalyst), and the esterification catalyst in a liquid state. Second, the hydrogenation catalyst uses a powdered metal catalyst. In the examples, a Pd / C or Pt / C powdered catalyst with a loading of 3 - 10 wt% and a total raw material mass of 2 - 5% is actually used. The catalyst dosage and loading are too large, and the loss during filtration and recovery is extremely large, resulting in too high catalyst usage cost. Third, since the esterification and hydrogenation product is mainly monoester and there are quite a lot of monomer small molecules such as copolymer acid and 1,4-butanediol remaining in the product, although less tetrahydrofuran and water are generated during the esterification stage, a large amount of water will still be generated during the vacuum high-temperature (10 - 200 Pa and 220 - 260 °C) polycondensation stage. Then, the polycondensation catalyst added before the polycondensation reaction will be hydrolyzed and inactivated in large quantities, resulting in low activity and large dosage of the polycondensation catalyst, and low product polymerization degree. In the examples, tetrabutyl titanate, zirconium acetylacetonate or lanthanum with a total raw material mass of 500 - 800 ppm is actually used. The final result is that the synthesized polyester product has poor quality: high metal content (~300 ppm), low molecular weight (52,000 - 71,000) and wide distribution, high acid value and melt index, and poor thermal and mechanical properties.

[0020] Therefore, it is very necessary to develop and provide a new technical route for preparing low-cost and high-quality polybutylene succinate biodegradable plastics using maleic anhydride and its derivatives as raw materials. Summary of the Invention

[0021] In view of this, the present invention provides an overall process route, system and production method for preparing polybutyrate biodegradable plastics with high efficiency, high quality and low cost.

[0022] To achieve the above object, the technical solution of the present invention is specifically as follows: A method for preparing polybutyrate polyester using maleic anhydride and / or its derivatives as raw materials, comprising the following reaction steps:

[0023] (1) Maleic anhydride and / or maleic anhydride derivatives, polyols, and with or without copolymerized polyacids and / or their derivatives, under the action of a solid acid-supported metal bifunctional catalyst, using a fixed-bed reaction process, through hydrogenation-esterification / transesterification or esterification / transesterification-hydrogenation coupling reaction, to prepare a polyester precursor, succinic acid polyol ester or succinic acid-copolymerized polyacid-polyol mixed ester;

[0024] (2) The obtained polyester precursor is subjected to a kettle polymerization reaction distillation process under the action of a polymerization catalyst, successively through vacuum oligomerization, negative pressure prepolymerization and vacuum final polymerization reactions to prepare polybutyrate or polybutyrate copolyester;

[0025] Among them, the maleic anhydride derivatives include maleic acid, fumaric acid, succinic acid, succinic anhydride, butynedioic acid or their esters; the copolymerized polyacids and / or their derivatives include fatty acids, aromatic acids, heterocyclic acids with two or more functional groups or their anhydrides or esters, and the polyols include fatty alcohols, aromatic alcohols or heterocyclic alcohols with two or more functional groups;

[0026] The solid acid-supported metal bifunctional catalyst is a catalyst prepared by loading a metal active component with hydrogenation function or a precursor of a metal active component and an auxiliary agent onto the surface of a solid acid carrier with esterification or transesterification function. Among them, the metal active component includes one element or a combination thereof selected from Cr, Mn, Fe, Co, Ni, Cu, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag or Au, and the auxiliary agent includes one or a combination of oxides of Mg, Ca, Sr, Ba, Sn, Pb, Sb, Y, Sc, La, Ce, Pr, Pm, Sm, Nd, Er, Yb, Th, B, P, Ti, Zr, V, Nb, Mo, W or Zn; the solid acid carrier is selected from at least one of hydrogen-type molecular sieves, acidic metal oxides or acidic metal oxides supported on porous materials.

[0027] In the above reaction steps, in step (1), the coupling reaction refers to carrying out double bond hydrogenation and esterification or transesterification reactions under the same reactor, the same reaction system, and the same reaction process conditions to prepare succinic acid polyol esters or succinic acid - copolymer polyacid - polyol mixed esters. The process includes the following three cases: (1) The -C=C- double bond or -C≡C- triple bond existing in maleic anhydride and / or its derivatives, copolymer polyacids and / or their derivatives, and polyols is first hydrogenated and saturated, and the resulting succinic anhydride and / or its derivatives, or / and saturated copolymer polyacids and / or their derivatives, then undergo ring-opening, esterification or transesterification reactions with the corresponding saturated polyols; (2) Maleic anhydride or / and its derivatives, or / and copolymer polyacids and / or their derivatives and polyols first undergo ring-opening, esterification or transesterification reactions, and the resulting maleic acid esters or / and copolymer polyacid esters are then hydrogenated and saturated; (3) The aforementioned hydrogenation - esterification / transesterification or esterification / transesterification - hydrogenation processes are carried out simultaneously.

[0028] Furthermore, in the solid acid-supported metal bifunctional catalyst, the metal active component is one element or a combination thereof selected from Fe, Co, Ni, Cu, Ru, Pd, Pt, or Ag, and the promoter is an oxide of Mg, Ca, Sn, Pb, Y, La, Ce, Sm, or Nd, or an oxide of B, P, Mo, W, or Zn, or a combination of these two types of oxides; preferably, the metal active component is Ni, Ru, Pd, Pt single metal or Ni-Cu, Ni-Co, Ni-Ru, Ni-Pd, Pd-Fe, Pd-Ru, Pt-Co bimetal, and the promoter is an oxide of Mg, Sn, La, or Ce, or an oxide of Mo, W, or Zn, or a combination of these two types of oxides;

[0029] The hydrogen form molecular sieve is selected from at least one of HM, HHEU, HY, Hβ, HZSM-5, HZSM-11, HZSM-12, HZSM-18, HZSM-22, HZSM-23, HZSM-35, HZSM-48, HMCM-22, HMCM-41, HMCM-48, HMCM-49, HMCM-50, or HMCM-56; the pore material for loading acidic metal oxides includes porous materials or mesoporous materials, selected from activated carbon, graphene, Al 2 O 3 、SiO 2 、TiO 2 、ZrO 2 、hydrogen form molecular sieves or non-hydrogen form molecular sieves, and the non-hydrogen form molecular sieve is selected from AlPO 4At least one of -11, SAPO-11, SAPO-34, ZRP-3, S-1 (Silicalite-1), S-2 (Silicalite-2), TS-1, TS-2, SBA-1, SBA-15, ZEO-1, ZEO-2, ZEO-3, KIT-6, CMK-1, CMK-2 or CMK-3;

[0030] The acidic metal oxide is selected from at least one of a high-valent metal oxide, a solid superacid or a heteropolyacid, and the high-valent metal oxide includes γ-Al 2 O 3 、SiO 2 -Al 2 O 3 、TiO 2 -SiO 2 , H 2 TiO 3 , Fe 2 O 3 、MoO 3 and Nb 2 O 5 , the solid superacid includes WO 3 / TiO 2 、MoO 3 / TiO 2 , WO 3 / ZrO 2 、MoO 3 / ZrO 2 、SO 4 2- / TiO 2 、SO 4 2- / ZrO 2 -CeO 2 、SO 4 2- / Fe 2 O 3 and SO 4 2- / Fe 2 O 3 -La 2 O 3 , the heteropoly acid includes H 3 PW 12 O 40 , H 3 PMo 12 O 40 , H 4 S W 12 O 40 , H 4 S W 12 O40 and Cs 2.5 H 0.5 PW 12 O 40 。

[0031] Further, the method for preparing polybutyrate polyesters specifically includes the following steps:

[0032] S1. Maleic anhydride and / or maleic anhydride derivatives are mixed with polyols according to a metering ratio, with or without adding copolymeric polyacids and / or their derivatives, to prepare a raw material solution. After preheating the raw material solution, it is fed into a fixed-bed reactor filled with the solid acid-supported metal bifunctional catalyst for hydrogenation-esterification or hydrogenation-transesterification coupling reaction to prepare a polyester precursor;

[0033] S2. The material after the reaction in step S1 is subjected to gas-liquid separation. The separated liquid-phase material is fed into a flash distillation column. Light components are removed from the top of the column, and a material containing the polyester precursor is obtained at the bottom of the column;

[0034] S3. Part of the polymerization catalyst is added to the polyester precursor material after flash distillation in step S2, and it is fed into an oligomerization reaction kettle for vacuum reactive distillation to obtain an oligomer at the bottom of the column;

[0035] S4. The remaining polymerization catalyst is added to the oligomer obtained in step S3. After mixing evenly, it is fed into a prepolymerization reaction kettle for prepolycondensation reaction under negative pressure to obtain a prepolymer;

[0036] S5. The prepolymer obtained in step S4 is fed into a final polycondensation reaction kettle for final polycondensation reaction under vacuum to obtain polybutyrate or copolyester, and then it is pelletized underwater to obtain polybutyrate or copolyester pellet products;

[0037] Wherein: the temperature at the bottom of the flash distillation column in step S2 is 60-150 °C, the temperature at the top of the column is 45-120 °C, and the pressure at the top of the column is 80-101 kPa; preferably, the temperature at the bottom of the flash distillation column is 70-120 °C, the temperature at the top of the column is 50-105 °C, and the pressure at the top of the column is 90-101 kPa;

[0038] The polymerization catalyst used in step S3 accounts for 10-40% of the total polymerization catalyst dosage, preferably 20%-30%.

[0039] Further, in the above process, the hydrogen gas separated by gas-liquid separation in step S2 is recycled, mixed with the supplemented fresh hydrogen gas, heated to the reaction temperature, and then fed into the fixed-bed reactor in step S1.

[0040] Further, in the above process, in steps S2 to S5, the overhead materials of the flash tower and the gaseous materials removed in the polycondensation reaction (including oligomerization, prepolymerization, and final polymerization) are condensed and mixed and then sent to an alcohol / ether recovery system. The recovered cyclic ether and monohydric alcohol are used as by-products, and the recovered polyhydric alcohol is sent to the raw material preparation tank for recycling.

[0041] Further, in the solid acid-supported metal bifunctional catalyst, the loading amount of the metal active component is 0.05 to 30 wt%; preferably, the metal active component is a noble metal active component with a loading amount of 0.2 to 2 wt% or / and a non-noble metal active component with a loading amount of 5.0 to 20 wt%.

[0042] Further, the loading amount of the auxiliary agent is 0.02 to 20 wt%; preferably, the auxiliary agent is selected from alkaline earth or rare earth oxide auxiliary agents with a loading amount of 0.1 to 1.0 wt%, or / and other oxide auxiliary agents with a loading amount of 1.0 to 10 wt%.

[0043] Further, in step (1), the reactor used for the coupling reaction is a gas-liquid-solid three-phase fixed bed reactor, preferably an isothermal or adiabatic fixed bed reactor; the inflow mode of hydrogen and liquid raw materials adopts a co-current mode of upward inlet and downward outlet or a counter-current mode of downward inlet and upward outlet of hydrogen and upward inlet and downward outlet of liquid raw materials;

[0044] The solid acid-supported metal bifunctional catalyst is in the form of spherical particles with a diameter of 1.2 to 5.0 mm or cylindrical or shaped particles with a diameter of 1.2 to 3.2 mm and a length of 1.6 to 5.0 mm; preferably spherical particles with a diameter of 1.6 to 3.5 mm or cylindrical or clover-shaped particles with a diameter of 1.6 to 2.6 mm and a length of 2.0 to 4.0 mm; more preferably spherical particles with a diameter of 1.8 to 3.0 mm or clover-shaped particles with a diameter of 1.8 to 2.2 mm and a length of 2.0 to 3.0 mm.

[0045] Further, in step (1), the process conditions of the coupling reaction are as follows: the molar ratio of (maleic anhydride and / or its derivatives + copolymer polyacid and / or its derivatives) to polyhydric alcohol is 1.00:(1.05 to 3.00), the molar ratio of maleic anhydride or / and its derivatives to copolymer polyacid and / or its derivatives is 1.00:(0 to 9.00), the feed space velocity of the liquid raw material is 0.1 to 5.0 h -1 , the molar ratio of hydrogen to carbon-carbon unsaturated bonds is 2.0 to 50.0, the reaction temperature is 50 to 180 °C, and the reaction pressure is 0.2 to 5.0 MPa;

[0046] Preferably, the process conditions for the coupling reaction are as follows: the molar ratio of (maleic anhydride and / or its derivatives + copolymerized polybasic acid and / or its derivatives) to polyol is 1.00:(1.25 - 2.50), the molar ratio of maleic anhydride and / or its derivatives to copolymerized polybasic acid and / or its derivatives is 1.00:0 - 4.00, the liquid feed space velocity is 0.2 - 2.0 h -1 , the molar ratio of hydrogen to carbon-carbon unsaturated bonds is 5.0 - 30.0, the reaction temperature is 60 - 160 °C, and the reaction pressure is 0.3 - 3.0 MPa;

[0047] More preferably, the process conditions for the coupling reaction are as follows: the molar ratio of (maleic anhydride and / or its derivatives + copolymerized polybasic acid and its derivatives) to polyol is 1.00:(1.50 - 2.25), the molar ratio of maleic anhydride and / or its derivatives to copolymerized polybasic acid and / or its derivatives is 1.00:0 - 1.00, the liquid feed space velocity is 0.4 - 1.0 h -1 , the molar ratio of hydrogen to carbon-carbon unsaturated bonds is 10.0 - 20.0, the reaction temperature is 70 - 150 °C, and the reaction pressure is 0.5 - 1.5 MPa.

[0048] Furthermore, the maleic anhydride and / or its derivatives include maleic anhydride, maleic acid, fumaric acid, succinic acid, succinic anhydride, butynedioic acid, or their C 1 - C 4 fatty alcohol esters; preferably maleic anhydride, maleic acid, fumaric acid, succinic acid, succinic anhydride, butynedioic acid, or their methyl esters, ethyl esters, propyl esters, butyl esters, allyl esters, propargyl esters, 2-methylallyl esters, 2-butenyl esters, ethylene glycol esters, propylene glycol esters, or butylene glycol esters; more preferably maleic anhydride, maleic acid, fumaric acid, succinic acid, succinic anhydride, butynedioic acid, or their monomethyl esters or dimethyl esters;

[0049] The copolymerized polybasic acid and / or its derivatives are selected from C 2 - C 22 fatty polybasic acids, C 8 - C 16 aromatic polybasic acids, or C 6 - C 10At least one of a heterocyclic polybasic acid, or its acid anhydride or ester; preferably glutaric acid, 2-pentenedioic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,2'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 2,5-furandicarboxylic acid or 2,6-pyridinedicarboxylic acid, or glutaric anhydride, 2-pentenedioic anhydride, adipic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, phthalic anhydride, aconitic anhydride, trimellitic anhydride or pyromellitic dianhydride, or at least one of their monomethyl esters or dimethyl esters; more preferably glutaric acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid or 2,5-furandicarboxylic acid, or glutaric anhydride, adipic anhydride or aconitic anhydride, or at least one of their monomethyl esters or dimethyl esters;

[0050] The polyol is selected from C 2 ~C 18 aliphatic diols, C 3 ~C 10 aliphatic triols, C 4 ~C 8 aliphatic tetra- to hexaols, C 8 ~C 15 aromatic diols or C 4 ~C 8 at least one of heterocyclic diols; preferably ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, glycerol, trimethylolethane, 1,2,6-hexanetriol, trimethylolpropane, erythritol, pentaerythritol, xylitol, sorbitol, mannitol, inositol, butenediol, butynediol, 1-phenyl-1,3-propanediol, 2-phenyl-1,3-propanediol, 1-phenyl-1,4-butanediol, isophthalic dimethanol, terephthalic dimethanol, 1,4-naphthalenedimethanol, 1,8-naphthalenedimethanol, 2,6-naphthalenedimethanol, 2,2'-biphenyldimethanol, 4,4'-biphenyldimethanol, 2,5-furandimethanol, 2,5-tetrahydrofurandimethanol, 2,6-pyridinedimethanol or 2,6-pyridinedimethanol; more preferably at least one of 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, 1,4-cyclohexanedimethanol, trimethylolpropane, pentaerythritol, butenediol, butynediol, terephthalic dimethanol or 2,5-furandimethanol.

[0051] Further, in step (2), the polymerization catalyst is selected from one or more of titanium dioxide, titanium-silicon composite oxide, titanium-silicon-phosphorus composite oxide, titanium-silicon molecular sieve, titanium trichloride, titanium tetrachloride, tributoxy titanium chloride, tetraethoxy titanium, tetraisopropoxy titanium, tetrabutoxy titanium, tetraisooctoxy titanium, titanium glycolate, titanium propylene glycolate or titanium butylene glycolate, preferably tetrabutoxy titanium, titanium glycolate or titanium butylene glycolate;

[0052] The dosage of the polymerization catalyst is 0.001-0.100% of the total mass of maleic anhydride and / or maleic anhydride derivatives and polyols, as well as copolymerized polybasic acids and / or their derivatives, preferably 0.005-0.050%.

[0053] Further, in step (2), the polymerization reaction process conditions are as follows:

[0054] Oligomerization reaction: temperature 120-200 °C, pressure 50-100 kPa and material residence time 20-60 min; preferably, temperature 140-180 °C, pressure 70-90 kPa and material residence time 30-45 min;

[0055] Pre-polycondensation reaction: temperature 160-220 °C, pressure 5-70 kPa and material residence time 30-90 min, preferably, temperature 180-200 °C, pressure 10-50 kPa and material residence time 45-60 min;

[0056] Final polycondensation reaction: temperature 200-260 °C, pressure 10-200 Pa and material residence time 60-150 min, preferably, temperature 220-250 °C, pressure 50-90 Pa and material residence time 90-120 min.

[0057] The present invention also provides a process system for preparing polybutanedioate polyester using maleic anhydride and / or its derivatives as raw materials, comprising an esterification-hydrogenation coupling reaction system, a polyester precursor refining system and a polycondensation reaction system connected in sequence; wherein, the esterification-hydrogenation coupling reaction system includes a raw material preparation tank, a heat exchanger, a preheater, an esterification-hydrogenation fixed bed reactor, a cooler and a gas-liquid separator; the polyester precursor refining system includes a flash tower, and the polycondensation reaction system includes an oligomerization reaction kettle, a pre-polycondensation reaction kettle and a final polycondensation reaction kettle connected in sequence.

[0058] Further, in the esterification-hydrogenation coupling reaction system, the cold material inlet of the heat exchanger is connected to the bottom outlet of the raw material preparation tank, the cold material outlet is connected to the inlet of the preheater, the hot material inlet of the heat exchanger is connected to the material outlet of the esterification-hydrogenation fixed bed reactor, and the hot material outlet is connected to the inlet of the cooler; the outlet of the preheater is connected to the material inlet of the esterification-hydrogenation fixed bed reactor, the outlet of the cooler is connected to the inlet of the gas-liquid separator, the gas-phase outlet of the gas-liquid separator is connected to the hydrogen inlet of the esterification-hydrogenation fixed bed reactor, and the liquid-phase outlet is connected to the inlet of the flash tower of the polyester precursor refining system;

[0059] The polyester precursor refining system further includes a light component collection tank, the top of the flash tower is connected to the light component collection tank, and the bottom is connected to the inlet of the oligomerization reactor;

[0060] The tops of the oligomerization reactor, the prepolymerization reactor and the final polymerization reactor in the polycondensation reaction system are all connected to the light component collection tank, and the liquid-phase material of the final polymerization reactor enters the subsequent polyester product system. The polyester product system includes an underwater pelletizing, pellet drying and product packaging production line that are sequentially transmitted.

[0061] Further, the operation process of the system includes the following steps: heat-exchange the prepared liquid raw material with the material after the esterification-hydrogenation reaction and preheat it to the reaction temperature, and then send it to the esterification-hydrogenation fixed bed reactor for esterification-hydrogenation reaction; after the reaction, the material is heat-exchanged with the feed and then cooled and condensed, and then sent to the gas-liquid separator for gas-liquid separation; the gas-phase hydrogen is mixed with the supplemented fresh hydrogen, heated to the reaction temperature and then sent to the esterification-hydrogenation reactor for recycling in the hydrogenation reaction, and the liquid-phase material is sent to the flash tower, and the polyester precursor is obtained at the bottom of the tower;

[0062] After adding a part of the polymerization catalyst to the polyester precursor, it is sent to the oligomerization reactor for vacuum reactive distillation, and the oligomer is obtained at the bottom of the tower; the remaining polymerization catalyst is added to the oligomer, and after mixing evenly, it is sent to the prepolymerization reactor for prepolycondensation reaction under negative pressure to obtain a prepolymer; the prepolymer is sent to the final polymerization reactor for final polycondensation reaction under vacuum to obtain polybutylene succinate or copolyester, and then polyester pellet products are obtained through underwater pelletizing; the overhead material of the flash tower and the gas-phase materials of the polycondensation reaction (oligomerization, prepolymerization and final polymerization) are condensed and mixed, and then sent to the light component collection tank.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] 1) The overall process flow of the present invention is: raw material preparation → coupling reaction → gas-liquid separation → flash evaporation for light component removal → vacuum oligomerization under reduced pressure → negative pressure prepolymerization → vacuum final polymerization → underwater pelletizing; while the combined process flow of the prior art is: hydrogenation raw material preparation → hydrogenation reaction → gas-liquid separation → flash evaporation for light component removal → solvent separation → monomer purification → raw material preparation → esterification reaction → negative pressure prepolymerization → vacuum final polymerization → underwater pelletizing. The present invention couples the two reaction processes of hydrogenating and saturating unsaturated basic raw materials maleic anhydride and its derivatives (or copolymeric acids and their derivatives containing unsaturation) to prepare acid monomers succinic acid and its derivatives, and esterifying the acid monomers with polyols to prepare precursor succinic acid polyol esters (or succinic acid-copolymeric acid polyol esters) into one reaction process, shortening the process flow, eliminating the reaction process of preparing acid monomers required by the prior art, eliminating operation units such as hydrogenation raw material preparation, solvent separation cycle, and acid monomer purification and purification, and eliminating solvents such as γ-butyrolactone used for preparing hydrogenation raw materials.

[0065] 2) The present invention uses a solid acid-supported metal bifunctional catalyst, a fixed-bed pressurized continuous reaction process, and a continuous flash evaporation process for the coupling reaction product to directly prepare polyester precursors from maleic anhydride and its derivatives, inhibiting and significantly reducing the decomposition of alcohol monomers and the generation of wastewater, and preventing small molecules such as acid catalysts, water, and monohydric alcohols generated by the coupling reaction from entering the polycondensation stage; at the same time, by adding a vacuum reaction distillation oligomerization process under reduced pressure to break the esterification reaction equilibrium, completely esterifying the acidic monomers and polyols that are not completely esterified in the coupling reaction, converting the precursor into oligomers with low degrees of polymerization, and removing excess alcohol monomers and other small molecules generated by the reaction from the system, avoiding problems such as hydrolysis and failure of the polymerization catalyst and large consumption, poor color of the polyester product, high acid value and melt index, low molecular weight and wide distribution, and high metal content caused by small molecules such as monomers and water entering the pre-polycondensation and final polycondensation stages. The present invention has high effective utilization rate of raw materials, low material and energy consumption, less wastewater generated, and a clean and efficient process; there is no residual esterification acid catalyst and monomer in the precursor, the polymerization catalyst has high efficiency and small dosage, there is less metal residue in the polyester, and the quality of the polyester product is high.

[0066] 3) The present invention uses basic chemical raw materials such as maleic anhydride (MAH), maleic acid, their esters or fumaric acid, their esters, succinic acid or succinic anhydride, their esters, and acetylenedicarboxylic acid, its esters as raw materials, and directly prepares the precursor through a hydrogenation-esterification / transesterification coupling reaction, and then the precursor is further prepared into polybutylene succinate through a polycondensation reaction; while the prior art uses succinic anhydride, succinic acid or dimethyl succinate as monomer raw materials, and first converts the basic chemical raw materials maleic anhydride and its derivatives into monomers through hydrogenation, and then the monomers are esterified or transesterified with polyols to synthesize the precursor, and finally the precursor is further prepared into polyester through a polycondensation reaction. The present invention directly uses basic chemical raw materials to synthesize the precursor in one step, with wide raw material sources, low price and easy availability; short process flow, simple operation, and low equipment investment; high product polyester yield, low material and energy consumption, and low production cost.

[0067] 4) The present invention can not only directly prepare the succinic acid polyol ester precursor through a hydrogenation-esterification / transesterification coupling reaction process of basic chemical raw materials maleic anhydride and its derivatives with polyols, but also add copolymer acids and their derivatives during the precursor preparation stage to prepare the succinic acid-copolymer acid-polyol ester precursor, and then prepare the polybutylene succinate copolymer through vacuum oligomerization-vacuum pre-polymerization-vacuum final polymerization. The process technical scheme of the present invention is flexible, and the same set of equipment can be used to produce multiple series of polybutylene succinate products, such as polyester PBS, PCS or PFS series products of maleic anhydride and its derivatives with single polyols such as 1,4-butanediol, p-xylene glycol or 2,5-furandimethanol, copolyesters PBSA, PBST or PBSF series products of copolymer dibasic acids such as adipic acid, terephthalic acid or 2,5-furandicarboxylic acid and 1,4-butanediol, copolyesters PBSS or PBTS series products of polyols such as 1,4-butanediol and pentaerythritol or trimethylolpropane, etc., to meet various market demands. Detailed implementation mode

[0068] The following combines specific embodiments to further illustrate the present invention. It should be noted that the embodiments described in this part are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0069] Symbol description:

[0070] MAD is a maleic anhydride derivative, SAA is succinic anhydride, SAD is succinic acid and its methyl ester, MMM is monomethyl maleate, DMM is dimethyl maleate, DMT is dimethyl terephthalate, BDO is 1,4-butanediol, THF is tetrahydrofuran, PTSA is p-toluenesulfonic acid, PXS is polybutylene succinate polyol ester, and PBSX is polybutylene succinate-copolymer polyacid-butanediol ester.

[0071] Calculation instructions:

[0072] 1) Calculation formula for preparing polyester precursor by hydrogenation-esterification / transesterification coupling reaction

[0073]

[0074] 2) Calculation formula for the whole process of synthesizing polyester by coupling reaction and polycondensation reaction

[0075]

[0076] Total feed weight = maleic anhydride and derivative feed weight + polyol feed weight + copolymer polyacid feed weight

[0077] Examples 1-14

[0078] The precursor of polybutylene succinate (PBS) was prepared by the hydrogenation-esterification / transesterification reaction of maleic anhydride and 1,4-butanediol (BDO), and its polycondensation synthesis was carried out as follows:

[0079] (1) Maleic anhydride and BDO were mixed and melted according to the stoichiometric ratio to prepare a raw material solution, which was heat-exchanged with the reacted material, and then the heat-exchanged material was heated to the reaction temperature and fed into a trickle-bed reactor filled with a bifunctional metal catalyst pre-reduced and activated from top to bottom in parallel with hydrogen for the hydrogenation-esterification coupling reaction. Among them, the molar ratio of BDO to maleic anhydride was (1.25-2.50):1;

[0080] (2) The material reacted in step (1) was heat-exchanged with the feed and then subjected to gas-liquid separation. The gaseous hydrogen was mixed with the supplemented fresh hydrogen and heated to the reaction temperature and then fed into the reactor. The liquid-phase material was fed into an atmospheric flash tower (operating conditions of the flash tower: bottom temperature 120°C, top temperature 105°C). The light components containing a very small amount of water and THF were removed from the top and fed into the alcohol / ether recovery system. The bottom of the flash tower obtained a material containing BDO and polyester precursor;

[0081] (3) After adding 20% of the polymerization catalyst titanium butoxide to the polyester precursor material obtained in step (2), it was fed into an oligomerization reactor for vacuum reactive distillation. The gaseous phase removed a small amount of water and THF generated by the oligomerization reaction and excess BDO, and the bottom of the tower obtained an oligomer;

[0082] (4) The remaining 80% of the polymerization catalyst was added to the oligomer, and after mixing evenly, it was fed into a prepolymerization reactor for prepolycondensation reaction under negative pressure to obtain a prepolymer;

[0083] (5) The prepolymer was fed into a final polycondensation reactor for final polycondensation reaction under vacuum to obtain polybutylene succinate (PBS), and then PBS polyester pellet products were obtained by underwater pelletizing;

[0084] In the above process, the total amount of the polymerization catalyst is 0.001-0.100% of the total mass of the raw materials maleic anhydride and polyol; the top material of the flash tower is condensed and mixed with the gas phase material of the polycondensation reaction (including polymerization, prepolymerization and final polymerization), and sent to the alcohol / ether recovery system, the separated and recovered THF is used as a by-product, and the separated and recovered BDO is sent to the raw material preparation tank for circulation.

[0085] The removed water is sent to the wastewater treatment system.

[0086] The bifunctional catalyst, process conditions and reaction results used in the preparation of polyester PBS precursor butylene succinate by hydrogenation-esterification coupling reaction of maleic anhydride and BDO are shown in Table 1. The reaction process conditions, BDO recovery rate, by-product yield, polyester yield and performance indicators of the precursor condensation polymerization to synthesize polyester PBS in Examples 1 to 14 are shown in Tables 2 and 3.

[0087] Comparative Example 1

[0088] Maleic anhydride is first hydrogenated to prepare succinic anhydride, and then an esterification catalyst is added to esterify with BDO to prepare the precursor butylene succinate, and then a polymerization catalyst is added to condense the precursor to synthesize polyester PBS. The specific process is as follows:

[0089] (1) Maleic anhydride hydrogenation to prepare monomer raw material succinic anhydride: a γ-butyrolactone solution of maleic anhydride with a concentration of 20 wt% was prepared, and the material after hydrogenation reaction was exchanged with heat and heated to the reaction temperature, and then fed into a pre-reduced activated 0.3 wt% Pd / γ-Al solution from top to bottom in parallel with hydrogen. 2 O 3 The catalyst was used in a trickle bed reactor at a reaction temperature of 90°C, a hydrogen pressure of 1.0 MPa, and a feed space velocity of 1.0 h -1 The reaction product is subjected to a hydrogenation reaction at a molar ratio of 20 to hydrogen anhydride; the reaction product is separated into gas and liquid, the hydrogen is sent to a hydrogenation reactor for recycling, the liquid material is sent to a light component removal tower, the light components and the solvent γ-butyrolactone are evaporated from the top of the tower, and are sent to a γ-butyrolactone distillation tower after condensation, and the bottom material is sent to a product distillation tower; a small amount of water is produced from the top of the γ-butyrolactone distillation tower, and the γ-butyrolactone obtained in the bottom of the tower is recycled as a hydrogenation solvent; a small amount of heavy components are discharged from the bottom of the product distillation tower, and succinic anhydride, a monomer raw material for synthesizing polyester, is obtained at the top of the tower.

[0090] (2) Preparation of polyester precursor by esterification of succinic anhydride: According to the molar ratio of 1.00:1.25 to BDO, feed the monomer raw material succinic anhydride into the batching tank, and add p-toluenesulfonic acid catalyst accounting for 0.5% of the total mass of the raw materials. Stir evenly and heat to 60 °C to prepare the raw materials, and then feed them into the esterification reactor. Carry out the esterification reaction at a temperature of 180 °C, normal pressure, and a residence time of 60 min. The esterification product is depressurized to remove small molecules such as water, THF, and BDO at 25 kPa to obtain the polyester precursor butylene succinate.

[0091] (3) Polycondensation of polyester precursor to synthesize polyester PBS: Add titanium butoxide as the polymerization catalyst accounting for 800 ppm of the total mass of the raw materials to the polyester precursor. After stirring evenly, continuously feed it into the prepolymerization reactor. Carry out the prepolymerization reaction at a temperature of 200 °C, a pressure of 25 kPa, and a residence time of 60 min; then continuously feed the prepolymerization product into the final polymerization reactor. Carry out the final polymerization reaction at a temperature of 240 °C, a pressure of 75 Pa, and a residence time of 120 min. The final polymerization product is pelletized underwater to obtain the polyester PBS pellet product.

[0092] The process conditions and results of Comparative Example 1 are shown in Tables 1-3.

[0093] Table 1 Catalysts, process conditions and reaction results for the preparation of polyester PBS precursor by the hydrogenation-esterification coupling reaction of maleic anhydride and BDO

[0094]

[0095] Table 2 Process conditions for the polycondensation of polyester precursor to synthesize polyester PBS

[0096]

[0097] Table 3 Reaction results and performance indicators for the polycondensation of polyester precursor to synthesize polyester PBS

[0098]

[0099] As can be seen from Table 1, using a solid acid-supported metal bifunctional catalyst (noble metal loading of 0.2-0.5 wt% or / and non-noble metal loading of 3-10 wt%, rare earth metal oxide promoter loading of 0.1-0.2 wt% or / and transition metal oxide promoter loading of 3 wt%), under the coupling reaction conditions: temperature 70-120 °C, pressure 0.5-3.0 MPa, feed space velocity 0.2-1.5 h -1At a molar ratio of hydrogen to double bond of 5 to 30 and a molar ratio of BDO to maleic anhydride of 1.25 to 2.50, the double bonds of maleic anhydride in Examples 1 to 14 can be completely hydrogenated and saturated (the double bond conversion rate reaches 100%), and can be completely esterified with BDO (the residual rate of acid and acid anhydride is 0), indicating that the solid acid-supported metal bifunctional catalyst has good catalytic activities for both hydrogenation and esterification; due to the excess of BDO and different degrees of excess, the esterification conversion rate of BDO varies greatly, ranging from 42.7% to 89.8%. Since there is no chemical equilibrium in the double bond hydrogenation reaction and the ring-opening esterification reaction of maleic anhydride or succinic anhydride with BDO, the coupling reaction product using maleic anhydride as the raw material is a mixture of monobutylene succinate, dibutylene succinate and excess BDO.

[0100] As can be seen from Tables 2 and 3, for the precursors prepared by the coupling reaction in Examples 1 to 14, when the total addition amount of titanium butoxide as the polymerization catalyst is 100 to 400 ppm of the raw materials, through the polycondensation reaction (oligomerization: temperature 140 to 180 °C, pressure 50 to 90 kPa and residence time 20 to 60 min, prepolymerization: temperature 180 to 200 °C, pressure 10 to 50 kPa and residence time 30 to 75 min, final polymerization: temperature 220 to 260 °C, pressure 20 to 90 Pa and residence time 75 to 150 min), the effective yield or the effective utilization rate of raw materials for synthesizing polyester PBS is 87.95 to 90.00 wt%, the recovery rate of BDO is 17.22 to 57.75 mol%, the yield of THF is 2.25 to 3.96 mol%, and the yield of wastewater is 9.74 to 9.97 wt%; the metal content in the PBS product is 29.0 to 160.7 ppm, the chromaticity L value is 82 to 91, the melt index is 11 to 31 g / 10 min, the acid value is 18 to 33 t / mol, and the weight-average molecular weight is (16.8 to 20.1) × 10 4 , and the tensile strength is 39 to 49 MPa.

[0101] Obviously, all the solid acid-supported metal bifunctional catalysts listed in the above examples have good catalytic performance for the hydrogenation-esterification coupling reaction of maleic anhydride and BDO to synthesize the PBS polyester precursor; the precursor is synthesized into PBS through three-stage polycondensation of oligomerization-prepolymerization-final polymerization with a relatively high yield, and the synthesized polyester PBS has excellent properties.

[0102] According to the results in Tables 1 - 3, in Comparative Example 1, the conversion rate of maleic anhydride hydrogenation to succinic anhydride is 100 mol%, the residual rate of succinic anhydride esterification is 0, the esterification conversion rate of BDO is 90.5 mol%, and based on maleic anhydride, the overall yield of the whole process is as follows: the effective yield of product PBS is 84.44 wt%, the recovery rate of BDO is 2.55 mol%, the yield of by - product THF is 17.45 mol%, and the yield of by - product wastewater is 10.37 wt%; the performance indicators of PBS are: metal content 209.0 ppm, chromaticity L value 82, melt index 32 g / 10 min, acid value 36 mol / t, weight - average molecular weight 13.2×10 4 , and the tensile strength is 35 MPa.

[0103] Comparative Example 1 is a typical operation process of the prior art for synthesizing PBS by using succinic anhydride and BDO as monomers through ring - opening esterification. The present invention couples the two processes of hydrogenation and esterification in the prior art into one step, simplifies the process and operation flow, reduces the reaction and separation steps, and reduces the investment in devices and equipment.

[0104] By comparing Comparative Example 1 and Examples 1 - 14 in Tables 1 - 3 (wherein, Example 6 and Comparative Example 1 use the same hydrogenation catalyst and hydrogenation and polymerization operation conditions), it can also be found that: ① The esterification conditions of the present invention are milder and have a larger operation space, and the dosage of the polymerization catalyst is less (esterification temperature 70 - 120 °C, feed space velocity 0.2 - 1.5 h -1 and the molar ratio of alcohol to anhydride is 1.25 - 2.50, and the dosage of the polymerization catalyst is 100 - 400 ppm; in Comparative Example 1, the esterification temperature is 180 °C, the feed space velocity is 1.0 h -1 and the molar ratio of alcohol to anhydride is 1.25, and the dosage of the polymerization catalyst is 800 ppm); ② The effective yield of polyester PBS or the effective utilization rate of raw materials and the recovery rate of BDO of the present invention are higher, and the decomposition amount of BDO, the generated by - product tetrahydrofuran and wastewater are less (PBS yield 87.95 - 90.00 wt%, BDO recovery rate 17.22 - 57.75 mol%, THF yield 2.25 - 3.96 mol%, wastewater yield 9.74 - 9.97 wt%; the PBS yield of Comparative Example 1 is 84.44 wt%, the BDO recovery rate is 2.55 mol%, the THF yield is 17.45 mol%, and the wastewater yield is 10.37 wt%); ③ The performance of the polyester PBS product synthesized by the present invention is better, specifically manifested as a significant reduction in metal content, a decrease in acid value, a decrease in melt index, a relatively higher weight - average molecular weight, and an increase in tensile strength.

[0105] Examples 15 - 21

[0106] The hydrogenation - esterification / transesterification reaction of maleic anhydride and its derivatives (MAD) with BDO to prepare a precursor and its polycondensation to synthesize poly(butylene succinate) (PBS) specifically includes the following processes:

[0107] (1) At least one of maleic acid, fumaric acid and their methyl esters is mixed with BDO in a stoichiometric ratio and melted to prepare a raw material solution, which is heat-exchanged with the reacted material, and then the heat-exchanged material is heated to the reaction temperature, and is fed downward in parallel with hydrogen into a trickle-bed reactor filled with a bifunctional catalyst pre-reduced and activated, to carry out a hydrogenation-esterification or transesterification coupling reaction, and the molar ratio of BDO to MAD is (1.25 - 2.25):1; wherein the MAD raw material in Example 19 is a mixed raw material obtained by mixing maleic anhydride and maleic acid in a molar ratio of 1:1.

[0108] (2) The reacted material is subjected to gas-liquid separation after heat-exchange with the feed. The gaseous hydrogen is mixed with the supplemented fresh hydrogen and heated to the reaction temperature and then fed into the reactor. The liquid-phase material is fed into an atmospheric flash tower (operating conditions: bottom temperature 120 °C, top temperature 105 °C). The light components containing water or / and methanol and a very small amount of THF are removed from the top and fed into an alcohol / ether recovery system. The material obtained at the bottom of the flash tower contains residual succinic acid or its methyl ester, BDO and polyester precursor.

[0109] (3) After adding 20% of the polymerization catalyst titanium butoxide to the polyester precursor material, it is fed into an oligomerization reaction kettle for vacuum reactive distillation. The gas phase removes the water or / and methanol, a small amount of tetrahydrofuran, and excessive BDO generated by the oligomerization reaction, and the oligomer is obtained at the bottom of the kettle.

[0110] (4) The remaining 80% of the polymerization catalyst is added to the oligomer, and after mixing evenly, it is fed into a prepolymerization reaction kettle for carrying out a pre-polycondensation reaction under negative pressure to obtain a prepolymer.

[0111] (5) The prepolymer is fed into a final polycondensation reaction kettle for carrying out a final polycondensation reaction under vacuum to obtain poly(butylene succinate) (PBS), and then PBS polyester pellet products are obtained through underwater pelletizing.

[0112] In the above process, the total amount of the polymerization catalyst is 0.001 - 0.100% of the total mass of the raw materials MAD and BDO; the material at the top of the flash tower and the condensed gas-phase materials of the polycondensation reaction (oligomerization, prepolymerization and final polycondensation) are mixed and fed into an alcohol / ether recovery system. The separated and recovered THF and methanol are used as by-products, the separated and recovered BDO is fed into the raw material preparation tank for recycling, and the removed water is fed into the wastewater treatment system.

[0113] The bifunctional catalysts, process conditions and reaction results for the preparation of the PBS precursor butylene succinate by the hydrogenation-esterification / transesterification coupling reaction of maleic anhydride and its derivatives (MAD) with BDO in Examples 15 - 21 are shown in Table 4; the reaction process conditions, BDO recovery rate, by-product yield, polyester yield and performance indexes of the polyester for the synthesis of PBS polyester from the precursors in Examples 15 - 21 are shown in Tables 5 and 6.

[0114] Comparative Examples 2 - 3

[0115] Maleic acid or its dimethyl ester is hydrogenated to prepare succinic acid and dimethyl ester, and then esterified or transesterified with BDO to prepare the precursor butylene succinate, and then the precursor is polycondensed to synthesize the polyester PBS.

[0116] The specific operation process and process conditions are the same as those in Comparative Example 1, except that the hydrogenation catalysts in Comparative Examples 2 and 3 are both 0.5 wt% Pd / (H 3 PW 12 O 40 / γ - Al 2 O 3 ). The hydrogenation raw material in Comparative Example 2 is maleic acid, and the hydrogenation raw material in Comparative Example 3 is dimethyl maleate. The specific operation conditions and results are shown in Tables 4 - 6.

[0117] Table 4 Catalysts, Process Conditions and Reaction Results for Hydrogenation - Esterification / Transesterification of Maleic Anhydride Derivatives (MAD and BDO) to Prepare Polyester PBS Precursors

[0118]

[0119] Table 5 Process Conditions for Polycondensation of Polyester Precursors Prepared by Hydrogenation - Esterification / Transesterification of MAD and BDO to Synthesize Polyester PBS

[0120]

[0121] Table 6 Reaction Results and Performance Indexes for Polycondensation of Polyester Precursors to Synthesize Polyester PBS

[0122]

[0123]

[0124] As can be seen from Table 4, in the present invention, using the solid acid - supported metal bifunctional catalyst 0.5 wt% Pd / (H 3 PW 12 O 40 / γ - Al 2 O 3 ), under the coupled reaction conditions: temperature 90°C, pressure 1.0 MPa, feed space velocity 1.0 h -1, at a molar ratio of hydrogen to double bond of 20 and a molar ratio of BDO to maleic anhydride derivative of 1.25 - 2.25, the double bonds of the maleic anhydride derivatives in Examples 15 - 21 can all be completely hydrogenated and saturated to convert into succinic acid and methyl ester (the double bond conversion rate reaches 100% in all cases). However, the esterification or transesterification reaction of succinic acid, its monomethyl ester, and dimethyl ester with BDO is incomplete, and the molar esterification rate or transesterification rate is 89.5 - 93.3%, with 6.7 - 10.5% of the monomer raw materials remaining. Due to the excess of BDO and different degrees of excess, the esterification conversion rate varies greatly, ranging from 35.0% to 71.2%. This is because the esterification or transesterification of maleic acid or succinic acid, its monomethyl ester, and dimethyl ester with BDO, as well as the double esterification reaction of succinic acid monobutylene glycol ester with BDO, all have chemical equilibria under pressurized conditions. Moreover, when the molar ratios of BDO to maleic anhydride and its derivatives are 2.25 and 1.25 respectively, the theoretical esterification conversion rate of BDO for 100% reaction to form succinic acid monobutylene glycol ester is 44.4% and 80.0%. Therefore, the coupling reaction product with maleic acid and its esters as the starting materials is a mixture of succinic acid monobutylene glycol ester, dibutylene glycol ester, residual acid monomer succinic acid and its methyl ester, and excess BDO. In addition, the 100% double bond conversion rate and 89.5 - 93.3% esterification rate or transesterification rate of the maleic anhydride derivative indicate that the solid acid-supported metal bifunctional catalyst has good hydrogenation and esterification catalytic activities simultaneously.

[0125] As can be seen from Tables 5 and 6, for the precursors prepared by the coupling reaction in Examples 15 - 21, with a total addition amount of titanium butoxide as the polymerization catalyst of 400 - 450 ppm of the raw materials, through the polycondensation reaction (oligomerization: temperature 160 - 180 °C, pressure 75 kPa, and residence time 60 min; prepolymerization: temperature 190 - 200 °C, pressure 25 kPa, and residence time 45 - 60 min; final polymerization: temperature 240 °C, pressure 75 Pa, and residence time 120 - 135 min), the effective yield or raw material utilization rate of synthesizing PBS is 71.67 - 84.78 wt%, the BDO recovery rate is 16.95 - 52.83 mol%, the tetrahydrofuran yield is 2.72 - 3.05 mol%, and the total yield of wastewater and methanol is 8.92 - 27.25 wt%; the metal content in the PBS product is 128.0 - 194.3 ppm, the chromaticity L value is 70 - 85, the melt index is 19 - 33 g / 10 min, the acid value is 19 - 47 t / mol, and the weight-average molecular weight is (10.1 - 14.7)×10 4 , and the tensile strength is 31 - 37 MPa.

[0126] Obviously, the solid acid-supported metal bifunctional catalyst has good catalytic performance for the hydrogenation-esterification / transesterification coupling reaction of maleic anhydride derivatives and BDO to synthesize the PBS polyester precursor; the precursor has a relatively high PBS yield when synthesized into PBS through the three-stage polycondensation of oligomerization-prepolymerization-final polymerization, and the synthesized polyester PBS has good performance.

[0127] Comparing Comparative Examples 2 and 3 with Examples 20 and 21 in Tables 4 to 6 (Examples 20 and Comparative Example 2, Examples 21 and Comparative Example 3 respectively use the same hydrogenation catalyst and hydrogenation and polymerization operating conditions), it can be seen that: ① The esterification conditions of the present invention are milder and the amount of polymerization catalyst used is less; ② The effective yield of the polyester PBS or the effective utilization rate of raw materials and the BDO recovery rate of the present invention are higher, and the amount of BDO decomposition, the by-products tetrahydrofuran and wastewater generated are less; ③ The performance of the polyester PBS product synthesized by the present invention is better.

[0128] Examples 22 to 33

[0129] Preparation of precursor by hydrogenation-esterification coupling reaction of maleic anhydride and polyol and its polycondensation to synthesize polyol succinate (PXS), which specifically includes the following processes:

[0130] (1) Mix maleic anhydride and polyol according to the stoichiometric ratio and melt them to prepare a raw material solution. After heat exchange with the reacted material, it is heated to the reaction temperature and fed into a trickle bed reactor filled with 0.5 wt% Pd / γ-Al 2 O 3 pre-reduced and activated bifunctional catalyst in a co-current manner from top to bottom for hydrogenation-esterification coupling reaction; the molar ratio of polyol to maleic anhydride is (1.05 - 2.25):1, and the selected polyol raw materials are shown in Table 7. Among them, in Examples 30 to 33, the polyol mixture of two polyols mixed according to the molar ratio shown in Table 7 is used as the polyol raw material;

[0131] (2) After heat exchange with the feed, the reacted material is subjected to gas-liquid separation. The gaseous hydrogen is mixed with the supplemented fresh hydrogen, heated to the reaction temperature and then fed into the reactor. The liquid-phase material is fed into a vacuum flash distillation column (operating conditions: bottom temperature 70 - 100 °C, top temperature 50 - 95 °C, top pressure 90 - 100 kPa). The light components containing water and a small amount of cyclic ether are removed from the top and fed into the alcohol / ether recovery system. The bottom of the flash distillation column obtains a material containing residual succinic acid, polyol and polyester precursor;

[0132] (3) After adding 30% of the polymerization catalyst titanium butanediol to the polyester precursor material, it is fed into an oligomerization reaction kettle for vacuum reaction distillation. The gas phase removes a small amount of water and cyclic ether generated by the oligomerization reaction and the excess polyol, and the kettle bottom obtains an oligomer;

[0133] (4) Add the remaining 70% of the polymerization catalyst to the oligomer, mix evenly and then feed it into a prepolymerization reaction kettle for prepolycondensation reaction under negative pressure to obtain a prepolymer;

[0134] (5) Feed the prepolymer into a final polycondensation reaction kettle for final polycondensation reaction under vacuum to obtain polyol succinate PXS, and then obtain PXS pellet products through underwater pelletization.

[0135] In the above process, the total amount of the polymerization catalyst is 0.001 - 0.100% of the total mass of maleic anhydride and polyol as raw materials; the materials at the top of the flash tower are condensed and mixed with the gas-phase materials in the polycondensation reaction (oligomerization, prepolymerization, and final polymerization), and then sent to the alcohol / ether recovery system. The cyclic ether separated and recovered is used as a by-product, the polyol separated and recovered is sent to the raw material preparation tank for recycling, and the removed water is sent to the wastewater treatment system.

[0136] Examples 22 - 33 use 0.5 wt% Pd / γ-Al of the bifunctional catalyst 2 O 3 The process conditions and reaction results for preparing the polyester PXS precursor succinic acid polyol ester by the hydrogenation-esterification coupling reaction of maleic anhydride and polyol are shown in Table 7. The reaction process conditions, polyol recovery rate, by-product yield, polyester yield, and polyester product performance indicators for the precursor polycondensation synthesis of PXS polyester in Examples 22 - 33 are shown in Table 8.

[0137] Table 7 Catalysts, process conditions, and reaction results for preparing the polyester PXS precursor by the hydrogenation-esterification of maleic anhydride and polyol

[0138]

[0139] Table 8 Process conditions for the polycondensation synthesis of polyester PXS from the precursor prepared by the hydrogenation-esterification of maleic anhydride and polyol

[0140]

[0141] Table 9 Reaction results and performance indicators for the polycondensation synthesis of polyester PXS from the polyester precursor

[0142]

[0143] As can be seen from Table 7, using the bifunctional catalyst 0.5 wt% Pd / γ-Al 2 O 3 , under the coupling reaction conditions: temperature 90 - 150 °C, pressure 1.0 - 3.0 MPa, feed space velocity 0.2 - 1.0 h -1 , molar ratio of hydrogen to unsaturated bond 10 - 30, and molar ratio of polyol to maleic anhydride 1.05 - 2.25, the double bond of maleic anhydride in Examples 22 - 33 is completely hydrogenated and saturated to form succinic anhydride, the esterification rate of succinic anhydride is 100%, the residue rate is 0, and the esterification conversion rate of polyol is 62.5 - 88.5%, indicating that the 0.5 wt% Pd / γ-Al 2 O 3 catalyst has good coupling reaction activity.

[0144] As can be seen from Tables 8 and 9, for the precursors prepared by the coupling reaction in Examples 22 to 33, with the total addition amount of titanium butoxide in the polymerization catalyst being 300 to 400 ppm of the raw materials, through polycondensation reaction (oligomerization: temperature 160 to 180 °C, pressure 50 to 75 kPa, and residence time 45 to 75 min; prepolymerization: temperature 180 to 200 °C, pressure 10 to 50 kPa, and residence time 30 to 60 min; final polymerization: temperature 230 to 250 °C, pressure 10 to 50 Pa, and residence time 90 to 135 min), the effective yield or raw material utilization rate of synthesizing polyester PXS is 82.03 to 94.12 wt%, the recovery rate of polyol is 2.71 to 52.10 mol%, the yield of cyclic ether is 0 to 4.12 mol%, and the total yield of wastewater is 6.61 to 10.70 wt%; the metal content in the PBS product is 76.7 to 118.8 ppm, the L value of chromaticity is 72 to 92, the melt index is 6 to 25 g / 10 min, the acid value is 10 to 26 t / mol, and the weight-average molecular weight is (12.3 to 30.8)×10 4 , and the tensile strength is 25 to 54 MPa. Obviously, the synthesis of PBS through the three-stage polycondensation of oligomerization-prepolymerization-final polymerization of the precursor has a high yield, and the synthesized polyester has excellent properties.

[0145] Examples 34 to 47

[0146] Maleic anhydride and its derivatives and copolymeric polyacids and their derivatives react with BDO through hydrogenation-esterification / transesterification coupling reaction to prepare the precursor and its polycondensation to synthesize polybutylene succinate-copolymeric polyacid-butylene glycol ester (PBSX), including the following process:

[0147] (1) Mix maleic anhydride and its derivatives (maleic acid, fumaric acid, or / and their methyl esters) and copolymeric polyacids and their derivatives with BDO according to the stoichiometric ratio, melt and prepare the raw material solution, heat it to the reaction temperature after heat exchange with the reacted material, and feed it into a trickle-bed reactor filled with 0.5 wt% Pd / (H 3 PW 12 O 40 / γ-Al 2 O 3 ) bifunctional catalyst in a co-current manner from top to bottom to carry out hydrogenation-esterification or transesterification coupling reaction; among them, the molar ratio of BDO:(maleic anhydride or / and its derivatives + copolymeric polyacid and / or its derivatives), that is, the molar ratio of BDO:acidic raw materials shown in Table 10, is 1.00:(1.25 to 1.50), and the acidic raw materials of each example are shown in Table 10;

[0148] (2) The reacted materials are subjected to gas-liquid separation after heat exchange with the feed. The gaseous hydrogen is mixed with the supplemented fresh hydrogen, heated to the reaction temperature, and then sent into the reactor. The liquid-phase materials are sent into a vacuum flash distillation column (operating conditions: bottom temperature 90-100 °C, top temperature 70-95 °C, top pressure 95-100 kPa). The light components containing water or / and methanol and a small amount of THF are removed from the top of the column and sent into the alcohol / ether recovery system. The material obtained at the bottom of the flash distillation column contains residual succinic acid or its derivatives, saturated copolybasic acids or their derivatives, BDO, and polyester precursors;

[0149] (3) After adding 25% of the polymerization catalyst titanium butoxide to the polyester precursor material, it is sent into an oligomerization reaction kettle for vacuum reactive distillation. The gaseous phase removes a small amount of THF, water or / and methanol, and excessive BDO generated by the oligomerization reaction. The oligomer is obtained at the bottom of the column;

[0150] (4) The remaining 75% of the polymerization catalyst is added to the oligomer. After mixing evenly, it is sent into a prepolymerization reaction kettle, and a prepolymer is prepared by carrying out a pre-condensation reaction under negative pressure;

[0151] (5) The prepolymer is sent into a final condensation reaction kettle, and polybutylene succinate-copolybasic acid-butylene glycol ester (PBSX) is prepared by carrying out a final condensation reaction under vacuum, and then PBSX pellet products are obtained through underwater pelletizing.

[0152] In the above process, the total amount of the polymerization catalyst is 0.001-0.100% of the total mass of maleic anhydride or / and its derivatives, copolybasic acids, and BDO as raw materials. The materials at the top of the flash distillation column and the condensed gaseous materials from the polycondensation reactions (oligomerization, prepolymerization, and final condensation) are mixed and sent into the alcohol / ether recovery system. The separated and recovered THF and methanol are used as by-products. The separated and recovered BDO is sent into the raw material preparation tank for recycling, and the removed water is sent into the wastewater treatment system.

[0153] Examples 34-47 adopt a bifunctional catalyst 0.5 wt% Pd / (H 3 PW 12 O 40 / γ-Al 2 O 3 ). The process conditions and reaction results for preparing the polyester PBSX precursor succinic acid-copolybasic acid butylene glycol ester from maleic anhydride and its derivatives, copolybasic acids and their derivatives, and BDO through a hydrogenation-esterification coupling reaction are shown in Table 10; the reaction process conditions, BDO recovery rate, by-product yield, polyester yield, and performance indicators for the synthesis of PBSX polyester from the precursors in Examples 34-47 are shown in Tables 11 and 12.

[0154] Table 10 Process conditions and coupling reaction results for the hydrogenation-esterification / transesterification of MAD and copolyacids and their derivatives with BDO to synthesize the polyester PBSX precursor

[0155]

[0156]

[0157] Table 11 Process conditions for synthesizing polyester PBSX by polycondensation of polyester precursor

[0158]

[0159] Table 12 Reaction results and performance indicators of synthesizing polyester PBSX by polycondensation of precursor prepared by hydrogenation-esterification / transesterification of MAD and copolymer acid and derivatives with BDO

[0160]

[0161]

[0162] Table 10 shows the process conditions and reaction results of preparing the precursor of polyester PBSX, succinic acid-copolymer polyacid butanediol ester, by the hydrogenation-esterification coupling reaction of maleic anhydride and derivatives and copolymer polyacids and derivatives with BDO using the bifunctional catalyst 0.5 wt% Pd / (H 3 PW 12 O 40 / γ-Al 2 O 3 ) in Examples 34 - 47. Tables 11 and 12 show the process conditions, BDO recovery rate, by-product yield, polyester yield and performance indicators of the polycondensation reaction of synthesizing PBSX polyester from the precursor in Examples 34 - 47.

[0163] As can be seen from Table 10, using the bifunctional catalyst 0.5 wt% Pd / (H 3 PW 12 O 40 / γ-Al 2 O 3 ) under the coupling reaction conditions: temperature 100 - 150 °C, pressure 0.75 - 1.0 MPa, feed space velocity 0.2 - 0.5 h -1 , molar ratio of hydrogen to double bond 10 - 15 and molar ratio of BDO to acidic material 1.25 - 1.50, in Examples 34 - 47, the acidic raw materials are completely hydrogenated and saturated (double bond conversion rate 100%), the residue rate of acidic materials (saturated polyacids and anhydrides or esters) is lower than 4.2 mol%, and the polyol conversion rate is 62.8 - 87.2%, indicating that the bifunctional catalyst has good coupling reaction activity.

[0164] As can be seen from Tables 11 and 12, for the precursors prepared by the coupling reaction in Examples 34 to 47, with the total addition amount of titanium butoxide as the polymerization catalyst being 250 to 400 ppm of the raw materials, through polycondensation reaction (oligomerization: temperature 170 to 180 °C, pressure 75 to 90 kPa, and residence time 60 to 75 min; prepolymerization: temperature 180 to 210 °C, pressure 10 to 30 kPa, and residence time 45 to 60 min; final polymerization: temperature 240 to 250 °C, pressure 30 to 50 Pa, and residence time 120 to 150 min), the effective yield or the effective utilization rate of raw materials for synthesizing polyester PBS is 72.94 to 89.77 wt%, the recovery rate of polyol is 16.95 to 30.47 mol%, the yield of tetrahydrofuran is 2.86 to 3.82 mol%, and the total yield of wastewater and methanol is 9.67 to 26.74 wt%; the metal content in the PBS product is 69.1 to 126.8 ppm, the chromaticity L value is 70 to 89, the melt index is 7 to 35 g / 10 min, the acid value is 19 to 37 t / mol, and the weight-average molecular weight is (14.6 to 22.7)×10 4 , and the tensile strength is 25 to 41 MPa. Obviously, the synthesis of PBS from the precursor through three-stage polycondensation of oligomerization-prepolymerization-final polymerization has a high yield, and the synthesized polyester has excellent properties.

[0165] Looking at Examples 1 to 47 and Comparative Examples 1 to 3, when using the solid acid-supported metal bifunctional catalyst, whether it is the hydrogenation-esterification / transesterification coupling reaction of maleic anhydride and its derivatives with BDO or with other polyols, or the hydrogenation-esterification / transesterification coupling reaction of maleic anhydride and its derivatives and copolymer polyacids and their derivatives with BDO, it has good catalytic performance. Moreover, the polyester synthesized from the precursor prepared by the coupling reaction through the three-stage reactive distillation method of vacuum oligomerization-negative pressure prepolymerization-vacuum final polymerization has good yield and performance, and is significantly superior to the polyester products synthesized by the prior art (Comparative Examples 1 to 3) under the same raw materials and process conditions.

[0166] Comparing the coupling reactions with maleic anhydride as the raw material (Examples 1 to 14 and 22 to 42) and those with maleic anhydride derivatives (Examples 15 to 21 and 43 to 47), it can be seen that the solid acid-supported metal bifunctional catalyst has significantly better performance in the hydrogenation-esterification coupling reaction of polyanhydride and polyol than in the hydrogenation-esterification / transesterification coupling reaction of polyacid and its ester with polyol. For the former, the effective yield of polyester is 83.65 to 94.12 wt%, the metal content in the product is 29.0 to 160.7 ppm, the chromaticity L value is 72 to 92, the melt index is 6 to 32 g / 10 min, the acid value is 10 to 36 t / mol, and the weight-average molecular weight is (12.3 to 30.8)×10 4and a tensile strength of 25 to 49 MPa; for the latter, the effective yield of PBS is 71.67 to 84.78 wt%, the metal content in the product is 69.9 to 194.3 ppm, the chromaticity L value is 68 to 88, the melt index is 11 to 35 g / 10 min, the acid value is 19 to 47 t / mol, and the weight-average molecular weight is (10.1 to 22.3)×10 4 and a tensile strength of 25 to 37 MPa; in particular, the coupling reaction performance using diester of polybasic acid as the raw material is relatively the worst. For example, in Examples 18, 21 and 47, the PBS yield is 71.67 to 72.94% and the metal content in the product is 126.8 to 194.3 ppm.

[0167] The above are only the preferred embodiments of the present invention, and are not intended 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 method for preparing polysuccinate polyester using maleic anhydride and / or its derivatives as raw materials, characterized in that: The process comprises the following reaction steps: (1) maleic anhydride and / or maleic anhydride derivatives and polyols, with or without copolymerized polyacids and / or their derivatives, in the presence of a solid acid-supported metal bifunctional catalyst, using a fixed bed reaction process, through hydrogenation-esterification / ester exchange or esterification / ester exchange-hydrogenation coupling reaction, to prepare polyester precursor succinic acid polyol ester or succinic acid-copolymerized polyacid-polyol mixed ester; (2) subjecting the obtained polyester precursor to a polymerization catalyst, adopting a kettle polymerization reaction distillation process, and sequentially subjecting the obtained polyester precursor to a reaction including reduced pressure polymerization, negative pressure prepolymerization and vacuum final polymerization to prepare polysuccinate or polysuccinic acid copolyester; Wherein, the maleic anhydride derivatives include maleic acid, fumaric acid, succinic acid, succinic anhydride, butynedioic acid or their esters; the copolymerized polyacids and / or their derivatives include divalent or higher fatty acids, aromatic acids, heterocyclic acids or their anhydrides or esters; the polyols include divalent or higher fatty alcohols, aromatic alcohols or heterocyclic alcohols; The solid acid-supported metal bifunctional catalyst is a catalyst prepared by loading a metal active component with a hydrogenation function or a precursor of a metal active component and an auxiliary agent onto the surface of a solid acid carrier with an esterification or transesterification function, wherein the metal active component includes one element or a combination thereof selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag or Au, and the auxiliary agent includes one or a combination thereof selected from the group consisting of oxides of Mg, Ca, Sr, Ba, Sn, Pb, Sb, Y, Sc, La, Ce, Pr, Pm, Sm, Nd, Er, Yb, Th, B, P, Ti, Zr, V, Nb, Mo, W or Zn; and the solid acid carrier is selected from at least one of a hydrogen-type molecular sieve, an acidic metal oxide or an acidic metal oxide supported by a porous material.

2. The method for preparing polysuccinate polyester according to claim 1, characterized in that: In the solid acid supported metal bifunctional catalyst, the metal active component is one element selected from Fe, Co, Ni, Cu, Ru, Pd, Pt or Ag or a combination thereof, and the auxiliary agent is an oxide of Mg, Ca, Sn, Pb, Y, La, Ce, Sm or Nd, or an oxide of B, P, Mo, W or Zn, or a combination of these two oxides; Preferably, the metal active component is a single metal such as Ni, Ru, Pd, or Pt, or a bimetal such as Ni-Cu, Ni-Co, Ni-Ru, Ni-Pd, Pd-Fe, Pd-Ru, or Pt-Co, and the additive is an oxide of Mg, Sn, La, or Ce, or an oxide of Mo, W, or Zn, or a combination of these two types of oxides; The hydrogen type molecule is selected from at least one of HM, HHEU, HY, Hβ, HZSM-5, HZSM-11, HZSM-12, HZSM-18, HZSM-22, HZSM-23, HZSM-35, HZSM-48, HMCM-22, HMCM-41, HMCM-48, HMCM-49, HMCM-50 and HMCM-56; the porous material for supporting the acidic metal oxide includes a porous material or a mesoporous material selected from activated carbon, graphene, Al2O3 , SiO2, TiO2, ZrO2, at least one of the hydrogen molecular sieves or non-hydrogen molecular sieves, the non-hydrogen molecular sieve is selected from at least one of AlPO4-11, SAPO-11, SAPO-34, ZRP-3, S-1 (Silicalite-1), S-2 (Silicalite-2), TS-1, TS-2, SBA-1, SBA-15, ZEO-1, ZEO-2, ZEO-3, KIT-6, CMK-1, CMK-2 or CMK-3; The acidic metal oxide is selected from at least one of a high-valent metal oxide, a solid superacid or a heteropolyacid. The high-valent metal oxide includes γ-Al2O3, SiO2-Al2O3, TiO2-SiO2, H2TiO3, Fe2O3, MoO3 and Nb2O5. The solid superacid includes WO3 / TiO2, MoO3 / TiO2, WO3 / ZrO2, MoO3 / ZrO2, SO4 2- / TiO2、SO4 2- / ZrO2-CeO2, SO4 2- / Fe2O3 and SO4 2- / Fe2O3-La2O3, the heteropoly acid includes H3PW 12 O 40 、H3PMo 12 O 40 、H4SiW 12 O 40 、H4SiW 12 O 40 and Cs 2.5 H 0.5 PW 12 O 40 .

3. The method for preparing polysuccinate polyester according to claim 1, characterized in that: The specific steps include: S1, maleic anhydride and / or maleic anhydride derivatives, with or without copolymerized polyacids and / or their derivatives, are mixed with polyols according to a stoichiometric ratio to prepare a raw material solution, the raw material solution is preheated, and then fed into a fixed bed reactor filled with the solid acid-supported metal bifunctional catalyst to perform hydrogenation-esterification or hydrogenation-ester exchange coupling reaction to prepare a polyester precursor; S2, separating the material after the reaction in step S1 into gas and liquid, sending the separated liquid phase material into a flash tower, removing the light components at the top of the tower, and obtaining the material containing the polyester precursor at the bottom of the tower; S3, adding part of the polymerization catalyst to the polyester precursor material after flash evaporation in step S2, sending the material into a polymerization reactor for reduced pressure reaction distillation, and obtaining a polymer in the reactor; S4, adding the remaining polymerization catalyst to the oligomer obtained in step S3, mixing evenly and sending into a prepolymerization reactor, and performing a pre-polycondensation reaction under negative pressure to obtain a prepolymer product; S5, sending the prepolymer product obtained in step S4 into a final polymerization reactor, performing a final polycondensation reaction under vacuum to obtain polysuccinate or copolyester, and then underwater pelletizing to obtain polysuccinate or copolyester pellet products; Among them, in step S2, the flash tower kettle temperature is 60-150° C., the tower top temperature is 45-120° C., and the tower top pressure is 80-101 kPa; the polymerization catalyst used in step S3 accounts for 10-40% of the total polymerization catalyst usage.

4. The method for preparing polysuccinate polyester according to claim 1, characterized in that: In the solid acid-supported metal bifunctional catalyst, the loading amount of the metal active component is 0.05-30wt%; preferably, the metal active component is a noble metal active component with a loading amount of 0.2-2wt%, or / and a non-noble metal active component with a loading amount of 5.0-20wt%; The loading amount of the auxiliary agent is 0.02-20 wt %. Preferably, the auxiliary agent is an alkaline earth or rare earth oxide auxiliary agent with a loading amount of 0.1-1.0 wt %, or / and other oxide auxiliary agents with a loading amount of 1.0-10 wt %.

5. The method for preparing polysuccinate polyester according to claim 1, characterized in that: In step (1), the reactor used for the coupled reaction is a gas-liquid-solid three-phase fixed bed reactor, preferably an isothermal or adiabatic fixed bed reactor; the hydrogen and liquid raw materials flow in in a top-in-bottom-out parallel flow manner or a bottom-in-top-out counter-flow manner of hydrogen and top-in-bottom-out of the liquid raw materials; The solid acid-supported metal bifunctional catalyst is selected from spherical particles with a diameter of 1.2 to 5.0 mm, cylindrical particles with a diameter of 1.2 to 3.2 mm and a length of 1.6 to 5.0 mm, or irregular particles; preferably, spherical particles with a diameter of 1.6 to 3.5 mm, cylindrical particles with a diameter of 1.6 to 2.6 mm and a length of 2.0 to 4.0 mm, or clover-shaped particles; more preferably, spherical particles with a diameter of 1.8 to 3.0 mm, or clover-shaped particles with a diameter of 1.8 to 2.2 mm and a length of 2.0 to 3.0 mm.

6. The method for preparing polysuccinate polyester according to claim 1, characterized in that: In step (1), the coupling reaction process conditions are: the molar ratio of (maleic anhydride and / or its derivatives + copolyacid and / or its derivatives) to polyol is 1.00:(1.05-3.00), the molar ratio of maleic anhydride and / or its derivatives to copolyacid and / or its derivatives is 1.00:(0-9.00), and the feed space velocity of the liquid raw material is 0.1-5.0h -1 , the molar ratio of hydrogen to carbon-carbon unsaturated bonds is 2.0 to 50.0, the reaction temperature is 50 to 180°C, and the reaction pressure is 0.2 to 5.0 MPa; Preferably, the coupling reaction process conditions are: the molar ratio of (maleic anhydride and / or its derivatives + copolyacid and / or its derivatives) to polyol is 1.00:(1.25-2.50), the molar ratio of maleic anhydride and / or its derivatives to copolyacid and / or its derivatives is 1.00:0-4.00, and the liquid raw material feed space velocity is 0.2-2.0h -1 , the molar ratio of hydrogen to carbon-carbon unsaturated bonds is 5.0-30.0, the reaction temperature is 60-160°C, and the reaction pressure is 0.3-3.0MPa; More preferably, the coupling reaction process conditions are: the molar ratio of (maleic anhydride and / or its derivatives + copolyacid and its derivatives) to polyol is 1.00:1.50-2.25, the molar ratio of maleic anhydride and / or its derivatives to copolyacid and / or its derivatives is 1.00:0-1.00, and the liquid raw material feed space velocity is 0.4-1.0h -1 , the molar ratio of hydrogen to carbon-carbon unsaturated bonds is 10.0-20.0, the reaction temperature is 70-150°C, and the reaction pressure is 0.5-1.5MPa.

7. The method for preparing polysuccinate polyester according to claim 1, characterized in that: The maleic anhydride and / or its derivatives include maleic anhydride, maleic acid, fumaric acid, succinic acid, succinic anhydride, ynedioic acid or C1-C4 fatty alcohol esters thereof; preferably maleic anhydride, maleic acid, fumaric acid, succinic acid, succinic anhydride, ynedioic acid or their methyl esters, ethyl esters, propyl esters, butyl esters, allyl esters, propargyl esters, 2-methylallyl esters, 2-butene esters, ethylene glycol esters, propylene glycol esters or butanediol esters; more preferably maleic anhydride, maleic acid, fumaric acid, succinic acid, succinic anhydride, ynedioic acid or their monomethyl esters or dimethyl esters; The copolymerized polyacid and / or its derivatives are selected from C2 to C 22 Fatty polyacid, C8~C 16 Aromatic polyacid or C6~C 10 At least one of the heterocyclic polyacids, or their anhydrides or esters; preferably 1,5-pentanedioic acid, 2-pentaconedioic acid, 1,6-hexanedioic acid, 1,10-decanedioic acid, 1,4-cyclohexyldicarboxylic acid, terephthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,2′-biphenyldicarboxylic acid, 4,4′-biphenyldicarboxylic acid, 2,5-furandicarboxylic acid or 2,6-pyrandicarboxylic acid, or glutaric anhydride, 2-pentaconedioic acid anhydride, adipic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, phthalic anhydride, aconitic anhydride, trimellitic anhydride or pyromellitic anhydride, or at least one of their monomethyl esters or dimethyl esters; more preferably 1,5-pentanedioic acid, 1,6-hexanodioic acid, 1,10-decanedioic acid, 1,4-cyclohexyldicarboxylic acid, terephthalic acid, isophthalic acid or 2,5-furandicarboxylic acid, or glutaric anhydride, adipic anhydride or aconitic anhydride, or at least one of their monomethyl esters or dimethyl esters; The polyol is selected from C2 to C 18 Fatty diols, C3~C 10 Fatty triols, C4-C8 fatty tetra- to hexa-alcohols, C8-C 15 At least one of aromatic diols or C4-C8 heterocyclic diols; preferably ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, glycerol, trimethylolethane, 1,2,6-hexanetriol, trimethylolpropane, erythritol, pentaerythritol, xylitol, sorbitol, glycerol At least one of nitrile alcohol, inositol, butylene glycol, butynediol, 1-phenyl-1,3-propanediol, 2-phenyl-1,3-propanediol, 1-phenyl-1,4-butanediol, isophthalic acid methanol, p-phthalic acid methanol, 1,4-naphthalenedimethanol, 1,8-naphthalenedimethanol, 2,6-naphthalenedimethanol, 2,2′-biphenyl dimethanol, 4,4′-biphenyl dimethanol, 2,5-furan dimethanol, 2,5-tetrahydrofuran dimethanol, 2,6-pyran dimethanol or 2,6-pyridine dimethanol.

8. The method for preparing polysuccinate polyester according to claim 1, characterized in that: In step (2), the polymerization catalyst is selected from one or more of titanium dioxide, titanium silicon composite oxide, titanium silicon phosphorus composite oxide, titanium silicon molecular sieve, titanium trichloride, titanium tetrachloride, tributoxytitanium chloride, tetraethoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium, tetraisooctoxytitanium, ethylene glycol titanium, propylene glycol titanium or butanediol titanium; The amount of the polymerization catalyst used is 0.001-0.100%, preferably 0.005-0.050%, of the total mass of the raw materials maleic anhydride and / or maleic anhydride derivatives and polyols, and copolymerized polyacids and / or their derivatives.

9. The method for preparing polysuccinate polyester according to claim 1, characterized in that: In step (2), the polymerization reaction process conditions are: The polymerization reaction conditions are: temperature 120-200°C, pressure 50-100 kPa and material residence time 20-60 min; preferably, temperature 140-180°C, pressure 70-90 kPa and material residence time 30-45 min; The pre-polycondensation reaction conditions are: temperature 160-220°C, pressure 5-70 kPa and material residence time 30-90 min, preferably, temperature 180-200°C, pressure 10-50 kPa and material residence time 45-60 min; The final polycondensation reaction conditions are: temperature 200-260° C., pressure 10-200 Pa and material residence time 60-150 min, preferably, temperature 220-250° C., pressure 50-90 Pa and material residence time 90-120 min.

10. A process system for preparing polysuccinate polyester using maleic anhydride and / or its derivatives as raw materials, characterized in that: It includes an esterification hydrogenation coupling reaction system, a polyester precursor refining system and a polycondensation reaction system which are connected in sequence; wherein the esterification hydrogenation coupling reaction system includes a raw material preparation tank, a heat exchanger, a preheater, an esterification hydrogenation fixed bed reactor, a cooler and a gas-liquid separator; The polyester precursor refining system comprises a flash tower, and the polycondensation reaction system comprises a polymerization reactor, a pre-polycondensation reactor and a final polycondensation reactor which are connected in sequence.

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