A method for preparing polymerization-grade 1,4-butanediol

Abstract

The present invention relates to a method for preparing polymerization-grade 1,4-butanediol, comprising S1: introducing a special metal element as an auxiliary agent to modify a cheap and readily available natural montmorillonite to obtain a modified montmorillonite carrier, and loading an active metal to obtain a catalyst; S2: under the action of the catalyst, under the reaction conditions of 40-150° C. and 1.0-8.0 MPaG, the acetal impurities in BDO are converted into BDO, while suppressing the occurrence of side reactions; S3: the reaction product is subjected to rectification treatment to obtain a polymerization-grade BDO product. Compared with the prior art, the present invention has the advantages of low cost, high conversion rate, high selectivity, and low energy consumption, can be matched with two process routes of acetylenic aldehyde method and maleic anhydride esterification hydrogenation method, can process BDO with high concentration of acetal content, produce polymerization-grade BDO, improve the added value of BDO products, and has good industrial application prospects.

Description

Technical Field

[0001] The present invention relates to a method for preparing polymerization-grade BDO, and in particular to a catalytic reaction process for obtaining polymerization-grade BDO by catalytic conversion and purification of BDO containing high-concentration acetal. Background Art

[0002] 1,4-Butanediol, English name 1, 4-Butanediol, referred to as BDO, is a colorless, viscous organic compound with a chemical formula of C4H 10 O2. Due to its special structure, 1,4-butanediol is widely used as an intermediate in organic synthesis, industrial solvents and polymer raw materials to produce derivatives such as tetrahydrofuran (THF), γ-butyrolactone (GBL), polybutylene terephthalate (PBT), polyurethane, thermoplastic polyurethane (TPU), etc. These high value-added derivatives are widely used in industries such as automobiles, spandex fibers, engineering plastics and pharmaceuticals. In addition, it is a precursor for synthetic chemicals such as 1,4-butanediol dimethacrylate (BDDMA) and N-methyl-2-pyrrolidone (NMP). These chemicals can be used to produce adhesives, coatings and specialty chemicals. With the rise of the new energy industry, it is also widely used in lithium-ion batteries, and can also be used in fields such as washing semiconductor chips.

[0003] In recent years, with the development of downstream industries and the continuous expansion of application fields, the requirements for product quality have become increasingly stringent. Some unspecified impurities in the existing BDO quality system will undergo complex reactions in the downstream polymerization process to generate substances containing chromophores, thereby affecting the viscosity, color, heat resistance and other indicators of the product, especially the color value of PBT, PBAT, downstream PU and TPU and other materials. It has a significant impact, seriously affecting the quality grade of the product, making it difficult to enter the high-end material fields of food, medical and health care and other people's health and life. There are higher requirements for quality. The quality system of the national standard "Industrial 1,4-Butanediol" (GB / T24768-2009) can no longer meet the increasingly diversified, strict and refined quality requirements of BDO applications.

[0004] According to "Contemporary Chemical Industry" (May 2024, Vol. 53, No. 5, pp. 1052-1056), "Research Report on BDO Refining Technology", acetal is the main color impurity in BDO products. The difference between polymerization-grade BDO products and industrial-grade BDO is that there are special requirements for the acetal content. Acetal, referred to as HBTHF in English, is an oxide impurity produced in the BDO hydrogenation process. This substance is easily oxidized and colored, thereby affecting the quality of BDO downstream polymerization products. Controlling the content of acetal impurities is the key to producing polymerization-grade BDO. Therefore, domestic manufacturers and research institutes have conducted research on this problem, and currently it is mainly solved by two methods:

[0005] The purity of BDO can be improved by means of physical separation, such as changing the distillation conditions, increasing the filling height of the distillation tower and the extremely high reflux ratio to reduce the acetal content and increase the emission. However, due to the special physical property system of HBTHF and BDO, their boiling points are similar and they form azeotropes. This method not only increases equipment investment and energy consumption, but also reduces the yield of BDO, and the separation effect of acetal is not obvious.

[0006] Through chemical means, the acetal is catalytically reacted to convert it into other easily separable components, and then further distilled to obtain high-quality BDO products. CN117645586A discloses a method for refining and removing acetal from BDO, which dehydrates and cyclizes BDO to generate THF, and then separates the acetal from THF. Although this method separates the acetal from the system, it reduces the yield of BDO. The methods disclosed in CN1216973A, CN106622393A and CN110833862A use a catalytic hydrogenation method. Acetal is hydrolyzed and hydrogenated to generate BDO under the action of a Ni-based catalyst. The yield of BDO is increased while the acetal is removed. Such methods have high requirements on the performance and mechanical properties of the catalyst. The catalyst has a suitable pore structure, acidity, and mechanical strength. Excessive acidity on the surface of the catalyst will lead to the occurrence of a dehydration cyclization side reaction of BDO, an increase in the THF content, and a reduction in the yield of BDO. Since the reaction requires hydrolysis first, a certain proportion of water needs to be added, which requires that the catalyst has good hydrothermal stability at high temperature and high pressure. Good hydrothermal stability will reduce the pore volume and specific surface area of ​​the catalyst, which is difficult to take into account. It is only suitable for raw materials with a relatively low acetal content. According to the disclosed patents, the acetal content in BDO is usually ≤2000ppm, and the removal capacity for raw materials with a high content is limited.

[0007] From the perspective of engineering implementation, the liquid phase reaction of catalytic hydrogenation requires the addition of water to complete the hydrolysis. The large difference in viscosity between water and butanediol makes it difficult for the two to mix and dissolve. Hydrogen is difficult to fully dissolve in the liquid phase reaction system. In industry, in order to ensure thorough hydrogenation, a large amount of hydrogen needs to be increased, but this will result in a short residence time in the reactor, resulting in a decrease in reaction performance and increased hydrogen consumption. Summary of the invention

[0008] The purpose of the present invention is to overcome the defects of the above-mentioned prior art. In view of the special requirements of polymerization-grade 1,4-butanediol on the acetal content, a method for preparing polymerization-grade 1,4-butanediol is provided to obtain polymerization-grade 1,4-butanediol. The present invention uses a modified inexpensive montmorillonite as a carrier to prepare a novel Ni-based catalyst, which can process raw materials with a high acetal content of up to 50,000 ppm. Under the condition of achieving high hydrothermal stability, it has a suitable pore size distribution, can smoothly transfer the heat inside the catalyst particles, and controls the pH of the catalyst surface by adding a special additive, so as to achieve the acetal conversion reaction while suppressing the side reaction of BDO dehydration cyclization to generate THF.

[0009] The present invention can convert high-acetal BDO in the acetylene aldehyde method and maleic anhydride method BDO process to less than 50000ppm, and simultaneously complete the dual functions of hydrolysis and hydrogenation at a relatively low water content. The water content of the raw material can be in the range of 0.01%wt~60wt%. After distillation and purification, the purity of BDO is ≥99.9wt%, which is better than the national standard of superior products and meets the quality requirements of polymerization-grade BDO. The acetal content is ≤100ppm, the carbonyl number is ≤0.01mg / g KOH, the heat-resistant color number is ≤5#, the synthetic color number is less than 10#, and the hydrochloric acid color number is ≤50#, which meets the high-end fields with special requirements on color value in downstream such as PU, PBAT, PBT and TPU.

[0010] The purpose of the present invention can be achieved by the following technical solutions:

[0011] The present invention provides a method for preparing polymerization-grade 1,4-butanediol, comprising the following steps:

[0012] S1: Preparation of catalyst

[0013] Montmorillonite is used as a carrier, and a metal element X is introduced as an additive to modify the montmorillonite carrier, which not only preserves the rich pore structure and good chemical and thermal stability of natural montmorillonite, as well as the mechanical properties of hydrothermal resistance, but also makes the montmorillonite carrier show suitable surface acidity through the introduced modified additive. The active metal Ni is loaded on the carrier M by an impregnation method to obtain the catalyst NiM-X;

[0014] S2: The prepared catalyst NiM-X is loaded into a reactor to carry out catalytic conversion of acetal. The reaction temperature is 40~150°C, preferably 60~1100°C, and the reaction pressure is 2.0~8.0MPaG, preferably 3.0~5.0MPaG. Under this condition, acetal is converted into 1,4-butanediol. The reactants are mainly composed of 1,4-butanediol, water, THF and other impurities. At this time, the carbonyl number of the reactants is 0.001~0.1mg / gKOH, preferably 0.01~0.05mg / gKOH, the acetal content is ≤100ppm, the THF content is ≤200ppm, and more preferably ≤100ppm.

[0015] S3: The reactants obtained in S2 are distilled and purified to obtain polymerization grade 1,4-butanediol product after removing other trace light components. The purity of 1,4-butanediol is ≥99.9%, the carbonyl number should be ≤0.01mg / gKOH, the acetal content is ≤100ppm, the heat-resistant color number is ≤5#, the synthetic color number is ≤10#, and the hydrochloric acid color number is ≤50#.

[0016] Further, in S1, the montmorillonite is natural sodium-based or calcium-based montmorillonite, or similar kaolin, bentonite, bentonite and bleaching earth, preferably montmorillonite, the modification aid is one or more Lewis acid composite oxides composed of transition metal elements from the III to XIV main groups and lanthanide metals, preferably Sc, Y, Ti, Zr, Hf, Zn, Mg, and the surface acidity of the modified montmorillonite carrier is 0.1-1.0 mmol / g, preferably 0.2-0.5 mmol, and the specific surface area is 100-500 m 2 / g, preferably 120~300m 2 / g, mechanical strength 30~80N.

[0017] Furthermore, the content of the metal element additive is 0.001% to 6wt%, preferably 0.01% to 5wt%, and most preferably 1wt% to 2wt%.

[0018] Furthermore, in S1, the loading amount of active metal Ni is 0.01-35 wt%, preferably 5 wt%-30 wt%, and most preferably 10 wt%-20 wt%.

[0019] Further, in S2, the acetal content in the feed BDO is not more than 50000 ppm, preferably not more than 30000 ppm.

[0020] Furthermore, in S2, the reactor is a trickle bed reactor, the reaction temperature is 80°C, and the reaction pressure is 3 MPaG.

[0021] Furthermore, in S2, after catalytic conversion, the carbonyl number of the reaction product is ≤0.01 mg / g KOH, the acetal content is ≤100 ppm, and the THF content is ≤100 ppm.

[0022] Furthermore, in S3, during the distillation and purification process, the operating pressure of the distillation tower is 4-6 KPaA, and the operating temperature is 160-180°C.

[0023] Furthermore, in S3, the obtained polymerization-grade 1,4-butanediol product has a purity greater than 99.9 wt%, a carbonyl number ≤0.01 mg / g KOH, an acetal content ≤100 ppm, a synthetic color number ≤10#, and a hydrochloric acid color number ≤50#.

[0024] Compared with the prior art, the present invention has the following technical advantages:

[0025] 1. Economical and efficient: The present invention can use cheap natural montmorillonite as a carrier, utilize the rich pore structure, good chemical stability and thermal stability, and natural hydrothermal resistance of montmorillonite, and introduce trace amounts of metal elements as additives. The modified montmorillonite carrier and the active metal Ni have a synergistic effect, which can not only efficiently complete the hydrolysis, isomerization and hydrogenation conversion reactions of acetal, but also suppress the side reaction of BDO dehydration cyclization to generate THF at a low level, so that almost all of the acetal is converted into BDO. Compared with the prior art, the present invention has the advantages of low cost, high catalyst conversion rate and high selectivity.

[0026] 2. Environmental protection and energy saving: High-efficiency catalysts provide favorable conditions for distillation separation, and high filler and reflux ratio are not required to achieve BDO purity that meets the quality requirements of polymerization-grade BDO products. At the same time, since montmorillonite is cheap and harmless, the cost is low, and the waste catalyst is easy to handle and harmless to the environment, it is conducive to the green and environmentally friendly production needs of the BDO industry.

[0027] 3. Wide application scope: The present invention can process materials with high acetal content, and the acetal content can reach up to 50,000 ppm, which is much higher than the existing technology. Both BDO process routes, namely, the acetylene aldehyde method and the maleic anhydride esterification hydrogenation method, can be used in combination, and the existing BDO industrial-grade products can be upgraded to the level of polymerization-grade BDO products, which fully meets the requirements of downstream high-end fields such as PU / TPU, PBT, PBAT, etc., improves the added value of BDO products, and has good industrial application prospects. DETAILED DESCRIPTION

[0028] In general, the main concepts of the present invention are as follows:

[0029] Catalyst preparation

[0030] Montmorillonite carrier modification

[0031] Commercial montmorillonite with a particle size of 25 microns was purchased. Weigh the montmorillonite and place it in a certain concentration (0.5-1.0 mol / L) of sulfuric acid, with a mass ratio of sulfuric acid to montmorillonite of 1:5-1:20. After stirring at 80-100° for 24 hours, add a small amount of 30%-50wt% sulfuric acid, continue stirring for 48 hours, and then cool naturally to room temperature. Use deionized water for replacement, washing, and suction filtration, and place it in a nitrogen drying oven at 120°C for 5 hours to remove moisture.

[0032] The acid-washed montmorillonite is modified by adding an additive, wherein the additive is selected from one of the third to fourteenth main group transition metal elements and lanthanide metals or a Lewis acid composite oxide composed of two or more elements, preferably (Sc, Y, Ti, Zr, Hf, Zn, Mg), and the amount of the additive added is 0.001% to 5%.

[0033] Mix the oxide of the modified additive and the acid-washed montmorillonite and grind them evenly, add ethanol / water (4:1) solution and stir evenly, place in a 80℃ water bath until the montmorillonite and the modified elements are observed to fill the entire flask in the form of floccules, stop stirring and let it stand for 48 hours. Wash and replace with ethanol 3~5 times, dry at 120℃ for 24 hours, then roast at 550℃ for 5 hours, and cool to room temperature for use. After extrusion, drying and roasting, it is made into a Φ=3m spherical carrier.

[0034] Active metal impregnation, nickel content 0.05~40wt%, take modified montmorillonite carrier, prepare a solution of appropriate amount of nickel nitrate at a ratio of 2ml nickel salt solution per gram of carrier, impregnate it on the weighed carrier, let it stand for 15min~300min, preferably 30~120min, filter and separate, dry at 120℃ for 5hr, and calcine at 350~750℃ for 24hr to obtain the final catalyst.

[0035] Acetal catalytic conversion

[0036] The catalyst prepared by the above method is added to the reactor. The reactor adopts a trickle bed. BDO containing acetal and hydrogen are added together from the top of the reactor. A small amount of deionized water is appropriately added according to the water content in the raw material. The water content is not less than 100ppm. The material undergoes hydrolysis and hydrogenation reactions on the catalyst surface.

[0037] Distillation

[0038] After the BDO product is hydrolyzed and hydrogenated, the product is distilled, which can further improve the purity of the BDO product and obtain polymerization-grade BDO.

[0039] The Ni-based catalyst with modified montmorillonite as the carrier is prepared by the above method, wherein the nickel content is 0.1%~40wt%, and the metal element content in the additive is 0.01~6wt%. It not only retains the rich pore structure and good chemical stability and thermal stability of montmorillonite, but also shows suitable surface acidity. Under the combined action of active metal Ni and the surface acidity of the modified carrier, it shows excellent performance, can convert high-concentration acetal into BDO, and suppress the side reaction of generating THF at a reduced level, and has high conversion rate and selectivity. The conversion rate is greater than 99%, and the selectivity is ≥99.9%.

[0040] According to the findings of the present invention, polymerization-grade BDO can be obtained through conversion reaction and one-step distillation, and the purity of BDO can reach more than 99.9wt%, the carbonyl number is ≤0.01mg / gKOH, the acetal is ≤100ppm, the heat-resistant color is ≤5#, the synthetic color number is ≤10#, and the hydrochloric acid color is ≤50#.

[0041] The present invention is described in detail below in conjunction with specific embodiments. Any features such as preparation means, materials, structures or composition ratios not clearly described in this technical solution are regarded as common technical features disclosed in the prior art.

[0042] Example 1

[0043] This embodiment provides a method for preparing polymer-grade BDO, and the specific steps are as follows:

[0044] Step 1, preparation of 20%NiM-2%Zr catalyst with 20%Ni content

[0045] 10 kg of commercially available natural montmorillonite (Clariant Chemicals, natural sodium montmorillonite) was weighed and placed in 1.0 mol / L sulfuric acid, with a mass ratio of sulfuric acid to montmorillonite of 1:10. After stirring at 80°C for 48 hours, it was naturally cooled to room temperature, washed and filtered with deionized water until the pH was neutral or weakly acidic, placed in a nitrogen drying oven at 120° for 5 hours to remove moisture, and ground into powder to obtain acid-washed montmorillonite (M). The acid-washed montmorillonite was modified by adding 2 wt% of Zr element.

[0046] Weigh 0.2kg ZrO(NO3) with a zirconium content of 2wt%, grind and mix evenly with the acid-washed montmorillonite, add 10L ethanol / water solution (ethanol: water mass ratio is 4:1), place in a 80℃ water bath, keep stirring for 12 hours, observe that montmorillonite and zirconium are in the form of flocs and evenly fill the entire stirring tank, stop stirring and let stand for 48 hours. Wash and replace with anhydrous ethanol 3 times, dry at 120℃ for 24 hours to remove moisture, then roast at 550℃ for 5 hours, cool to room temperature, and obtain a montmorillonite carrier (M-2%Zr) containing 2% Zr additive, and then go through a molding step to make a spherical carrier with Ø=3mm. Surface acid strength 0.32mmol / g, specific surface area 220m 2 / g, strength 55N.

[0047] The active metal Ni was loaded by impregnation method. According to the loading amount of 20wt% Ni, 7kg of nickel nitrate was weighed to prepare 0.3g / ml nickel nitrate solution, which was impregnated on the carrier at a concentration of 1mL / gM. After standing for 2hr, it was filtered and separated. The water was removed by drying at 120℃ for 5hr. The catalyst 20%NiM-2%Zr was obtained by calcination at 650℃ for 24hr.

[0048] Step 2: The catalyst 20% NiM-2% Zr prepared in step 1 is loaded with a loading amount of 10 kg. After loading is completed, the entire system is replaced with nitrogen.

[0049] Step 3: The catalyst is activated and the reactor is heated to 150°C in a hydrogen environment (heated to 100°C at 20°C / hr, and 150°C at 5°C / hr), maintained at 150°C for 48 hours, with a hydrogen pressure of 1000 kPa.

[0050] Step 4: Purchase crude BDO from a domestic maleic anhydride BDO unit (Hengli Group Co., Ltd.) as a raw material and feed it into the reactor at a flow rate of 20 kg / hr. The feed composition is as follows (the percentages in the table are mass percentages):

[0051]

[0052] The reactor adopts a trickle bed reactor, the reaction temperature is 80°C, and the reaction pressure is 3MPaG.

[0053] After the liquid level in the reactor reaches 50%, the distillation column is fed.

[0054] Step 5: The operating pressure of the distillation tower is 5KPaA, the operating temperature is 170±5℃, the reflux ratio is 2.0, and the tower bottom extraction is continuously fed and continuously extracted after it is qualified. The indicators of the tower bottom extraction are as follows (the percentages in the table are mass percentages):

[0055]

[0056] Example 2

[0057] The catalyst preparation method is the same as that in Example 1, except that the loading amount of active metal Ni is 10 wt % and the process operation conditions are the same as those in Example 1.

[0058] Example 3

[0059] The catalyst preparation method is the same as that in Example 1, except that the content of the auxiliary agent Zr element is 1 wt % and the process operation conditions are the same as those in Example 1.

[0060] Comparative Example 1

[0061] Purchased alumina carrier (KNT spherical alumina carrier, particle size 3.0mm, surface area 210m 2 / g), the Ni-Al2O3 catalyst was prepared by the impregnation method of Example 1, and the process conditions were the same as those of Example 1. The catalyst was recorded as B1, and the total acid content was 0.12mmol / g.

[0062] Comparative Example 2

[0063] The catalyst was prepared by the same method as in Comparative Example 1, except that the carrier was purchased silica (Q-10 series SiO2 carrier from Fuji, Japan, with a particle size of 4 mm and a specific surface area of ​​190 m 2 / g) Ni-SiO2 catalyst was prepared by the impregnation method of Example 1, and the process conditions were the same as those of Example 1. The catalyst was recorded as B2, and the total acid content was 0.06mmol / g.

[0064] Test Example 1

[0065] In view of the special requirements of polymer-grade BDO products, the synthetic color number test was carried out on the untreated raw materials, Examples 1 to 4 and Comparative Examples 1 to 2. The test method is as follows:

[0066] The ratio of adipic acid to the sample of the embodiment is 10:7. Weigh 100 g of adipic acid and 70 g of 1,4-butanediol;

[0067] Put the reagents into a four-necked flask at the same time and replace with nitrogen for 15 minutes;

[0068] Set the temperature to 220°C and heat for three and a half hours;

[0069] Measure color, usually at 110 degrees Celsius;

[0070] The whole process requires nitrogen pressure maintenance.

[0071] Test Example 2

[0072] The untreated raw materials, Examples 1 to 4 and Comparative Examples 1 to 2 were tested for the color number of hydrochloric acid. The test method was as follows: a certain amount of sample was taken, and hydrochloric acid was measured in a ratio of 1:1 and placed in a conical flask, and shaken well;

[0073] Place in a 30℃ constant temperature water bath and let stand for 30 min.

[0074] Take out the sample and measure the colorimeter to get the colorimetry of hydrochloric acid.

[0075] Test Example 3

[0076] The untreated raw materials, Examples 1 to 4 and Comparative Examples 1 to 2 were tested for heat resistance color numbers, and the test method was as follows:

[0077] Pour about 2 / 3 of the sample into the flat-bottom flask, set it to 200℃, turn on the heating stove, heat it to boiling, continue heating and boiling for 10 minutes, then stop heating, put it in a 30℃ constant temperature water bath, and let it stand for 20 minutes; take out the sample and measure the colorimeter.

[0078] The comparison results of the hydrogenation indicators of implementation 1 to 3 and the final BDO product indicators are shown in the following table (the percentages in the table are mass percentages):

[0079]

[0080] Note: The above analysis results are the contents of each component in organic matter without water.

[0081] It can be seen from the comparison table that Examples 1 to 3 all show good effects, and the acetal content is less than 100 ppm.

[0082] The BDO product index results of Comparative Examples 1-2 and Example 1 are shown in the following table (the percentages in the table are mass percentages):

[0083]

[0084] The results of test cases 1 and 2 are compared as follows:

[0085]

[0086] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing polymerization-grade 1,4-butanediol, characterized in that: The following steps are involved: S1: Preparation of catalyst Montmorillonite is used as a carrier, and the metal element Zr is introduced as an additive to modify the montmorillonite carrier, thereby preserving the pore structure, chemical stability, thermal stability, and hydrothermal resistance of the montmorillonite. At the same time, the introduced modification additive makes the montmorillonite carrier exhibit a suitable surface acidity, and the active metal Ni is loaded on the modified montmorillonite carrier M by an impregnation method to obtain a catalyst NiM-Zr; S2: The prepared catalyst NiM-Zr and the high acetal content 1,4-butanediol product are loaded into a reactor for catalytic conversion of acetal, the reaction temperature is 40-150°C, and the reaction pressure is 1.0-8.0MPaG. Under this condition, the acetal in the high acetal content 1,4-butanediol product is converted into 1,4-butanediol. At this time, the carbonyl number of the reactant is 0.001-0.1mg / gKOH, the acetal content is ≤100ppm, and the THF content is ≤200ppm; S3: The reaction product obtained in S2 is subjected to distillation and purification to obtain a polymerization-grade 1,4-butanediol product, wherein the purity of 1,4-butanediol is ≥99.9wt%, the number of carbonyl groups is ≤0.01mg / gKOH, the acetal content is ≤100ppm, and the synthetic color number is ≤10.

2. The method for preparing polymerization-grade 1,4-butanediol according to claim 1, characterized in that: In S1, the montmorillonite is selected from one of natural montmorillonite, kaolin, bentonite, bentonite and bleaching earth.

3. The method for preparing polymerization-grade 1,4-butanediol according to claim 2, characterized in that: In S1, the montmorillonite is natural sodium-based or calcium-based montmorillonite.

4. The method for preparing polymerization-grade 1,4-butanediol according to claim 1, characterized in that: In S1, the metal element content of the modification aid is 0.001-6wt%.

5. The method for preparing polymerization-grade 1,4-butanediol according to claim 1, characterized in that: In S1, the surface acidity of the modified montmorillonite carrier is 0.1~0.5mmol / g, and the specific surface area is 100~500m 2 / g, mechanical strength 30~80N.

6. The method for preparing polymerization-grade 1,4-butanediol according to claim 1, characterized in that: In S1, the loading amount of active metal Ni element is 0.01~35wt%.

7. The method for preparing polymerization-grade 1,4-butanediol according to claim 1, characterized in that: In S2, the acetal content in the feed 1,4-butanediol does not exceed 50,000 ppm.

8. The method for preparing polymerization-grade 1,4-butanediol according to claim 1, characterized in that: In S2, the reactor is a trickle bed reactor, the reaction temperature is 80°C, and the reaction pressure is 3MPaG; In S2, after catalytic conversion, the carbonyl number of the reaction product is ≤0.01 mg / gKOH, the acetal content is ≤100 ppm, and the THF content is ≤200 ppm.

9. The method for preparing polymerization-grade 1,4-butanediol according to claim 1, characterized in that: In S3, during the distillation and purification process, the operating pressure of the distillation tower is 4~6 KPaA and the temperature is 160~180℃; In S3, the obtained polymerization grade 1,4-butanediol product has a purity greater than 99.9wt%, a carbonyl number ≤0.01, an acetal content ≤100ppm, a heat-resistant color number ≤5#, a synthetic color number ≤10#, and a hydrochloric acid color number ≤50#.

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