Process and device for producing 1,4-butanediol from maleic anhydride

Abstract

The present application relates to a production process and device for 1,4-butanediol from maleic anhydride, which can obtain high-purity 1,4-butanediol product, high-purity tetrahydrofuran product and gamma-butyrolactone product; the 1,4-butanediol, tetrahydrofuran and gamma-butyrolactone products can be flexibly switched by setting the maleic anhydride hydrogenation reactor and the gamma-butyrolactone hydrogenation reactor in different sections; the tetrahydrofuran crude separation column, the extraction rectification column and the extractant recovery column are combined to use ethylene glycol as the extractant, which can efficiently separate tetrahydrofuran and water, and obtain high-purity tetrahydrofuran product with a mass fraction of 99.99%; the process can adjust the section operation according to the market demand of 1,4-butanediol, produce 1,4-butanediol and by-product tetrahydrofuran in high demand, reduce the production of 1,4-butanediol and by-product tetrahydrofuran and gamma-butyrolactone in low demand, and has good economy and environmental protection.

Description

Technical Field

[0001] This invention relates to a process for producing 1,4-butanediol, and particularly to a process and apparatus for producing 1,4-butanediol from maleic anhydride with high purity. Background Technology

[0002] 1,4-Butanediol (C4H) 10 O2 (1,4-Butanediol, BDO), melting point 20.2 ℃, boiling point 228 ℃. At room temperature and pressure, it is a colorless, oily liquid, miscible with water, soluble in ethanol, and slightly soluble in ether. 1,4-Butanediol is a raw material for the production of polyesters, polyurethanes, and polyethers. Currently, 1,4-Butanediol is mainly used to produce polybutylene succinate (PBS), polybutylene terephthalate (PET), and polybutylene adipate / terephthalate (PET). PBS, PET, and PET are widely used products in the plastics industry. With the increasing international emphasis on green and environmentally friendly practices in the chemical industry, the implementation of the domestic "plastic ban," and the continuous improvement of people's environmental awareness, PBS and PET have received significant attention and widespread application in the plastics field due to their excellent biodegradability.

[0003] The global 1,4-butanediol market reached US$7.684 billion in 2024 and is projected to grow at an annual rate of 9.9% from 2025 to 2030. The continued growth of the 1,4-butanediol market is primarily due to its use in the production of tetrahydrofuran and polyurethane, both of which are experiencing increasing demand. Tetrahydrofuran, as a solvent and polymer precursor, is crucial in the manufacture of spandex fibers and elastomers used in the textile and automotive industries. The growing popularity of lightweight and durable materials further drives the demand for tetrahydrofuran. Polyurethane, known for its versatility, is widely used in various fields such as foams, coatings, adhesives, and sealants, particularly in the construction, automotive, and furniture industries.

[0004] The main production processes for 1,4-butanediol include the acetylacetic aldehyde method, the allyl alcohol method, the butadiene method, and the maleic anhydride method.

[0005] The acetylene-aldehyde process, also known as the Reppe process, is the mainstream production process for 1,4-butanediol in China. This technology was developed early and is relatively mature. Currently, the modified Reppe process is more commonly used. This method offers mild reaction conditions, a safe production process, high product yield, and uses a catalyst that is flame-retardant, explosion-proof, and recyclable. The catalyst also boasts advantages such as long lifespan, high activity, and high selectivity. However, the acetylene-aldehyde process also has drawbacks. The product is limited and cannot be adjusted according to market fluctuations; the production of acetylene requires calcium carbide, which is energy-intensive. The production of acetylene from calcium carbide generates a large amount of calcium carbide slag, which is difficult to treat and requires high investment. Due to environmental, safety, and economic considerations, the use of acetylene and formaldehyde as raw materials for chemical production is facing increasing restrictions.

[0006] The propylene alcohol process, also known as the Lyondell process, utilizes a wide range of feedstocks, including propylene oxide, propylene alcohol, acrolein, or glycerol. The process is simple, and the Rh-based catalyst used in the hydroformylation process has a long lifetime and high yield of 1,4-butanediol. However, the propylene alcohol process also has some drawbacks. The propylene oxide route is costly and its sources are limited; the propylene-propylene acetate route has low product selectivity and high steam consumption; furthermore, propylene alcohol has a degree of toxicity, and the hydroformylation reaction of propylene alcohol has low selectivity.

[0007] The butadiene process, also known as the Mitsubishi process, is a technology developed by Mitsubishi Chemical Corporation of Japan in the 1980s. The advantages of the butadiene process are that the raw material, 1,3-butadiene, is a byproduct of ethylene plants and has a high product yield. Furthermore, it allows for flexible product adjustments by changing process conditions to produce tetrahydrofuran based on market demand. The process also generates relatively little waste liquid. However, the butadiene process also has some drawbacks: its process flow is long and complex, resulting in high equipment and operating costs; the presence of acetic acid in the reaction system necessitates the use of corrosion-resistant materials in the equipment; and the shortage of 1,3-butadiene raw materials in my country makes the butadiene process an unsuitable option for regions or enterprises lacking access to 1,3-butadiene raw materials, particularly for the production of 1,4-butanediol.

[0008] The mature production processes for producing 1,4-butanediol using maleic anhydride mainly include the maleic anhydride aqueous solution hydrogenation method and the maleic anhydride esterification hydrogenation method.

[0009] The maleic anhydride aqueous solution hydrogenation method is also known as the GEMINOX technology. In this process, maleic anhydride is absorbed and hydrolyzed in water to obtain a maleic acid aqueous solution. Then, the maleic acid aqueous solution reacts with hydrogen in a gas-liquid-solid three-phase trickle bed reactor to undergo a carboxyl hydrogenation reaction. The reaction temperature is 100–160 °C, the hydrogen pressure is 17 MPa, and the catalyst is ruthenium metal supported on activated carbon. Compared with Davy's maleic anhydride esterification method, this method eliminates the steps of maleic anhydride dehydration, purification, and esterification, resulting in a simpler process. The precious metal catalyst used has high selectivity and long lifespan. Furthermore, this process can simultaneously produce 1,4-butanediol and co-produce γ-butyrolactone and tetrahydrofuran, with the ratio adjustable according to market conditions, making the production unit highly economical. The disadvantages of this method are that it is easily affected by the market price of n-butane; the precious metal catalyst used is relatively expensive; the hydrogenation temperature and pressure are relatively high; the presence of acid in the reaction system causes severe corrosion to the equipment; and the entire process places high demands on the equipment.

[0010] The maleic anhydride esterification hydrogenation process, also known as the Davy-Mackee technology, involves the following main steps: molten maleic anhydride and methanol undergo catalyst-free monoesterification, acid-ion resin-catalyzed dieesterification, and distillation purification to produce dimethyl maleate. Dimethyl maleate is then vaporized and mixed with hydrogen in a first-stage gas-phase hydrogenation reactor to produce dimethyl succinate. Dimethyl succinate is then fed into a second-stage gas-phase hydrogenation reactor to produce 1,4-butanediol and methanol. Advantages of this maleic anhydride esterification hydrogenation technology include lower system temperature and pressure compared to maleic anhydride aqueous solution hydrogenation; higher catalyst conversion and selectivity; the use of a Cu-based catalyst, which is inexpensive; relatively lower overall investment; less waste; and lower material corrosivity, resulting in less stringent material requirements for equipment. This process can simultaneously produce 1,4-butanediol, tetrahydrofuran, and γ-butyrolactone, with the proportions adjustable according to market demand. The disadvantages of maleic anhydride esterification and hydrogenation include susceptibility to market fluctuations in the raw material maleic anhydride; the requirement that the maleic anhydride used be high-purity; the large amount of methanol circulating in the system, increasing the load on the equipment; the formation of an azeotropic component with tetrahydrofuran, which is difficult to separate, increasing the production cost and investment of the equipment; and the relatively long process flow, requiring esterification followed by hydrogenation.

[0011] In summary, the maleic anhydride hydrogenation technology that urgently needs research and development in industry requires a shorter process flow, avoidance of transesterification side reactions that are prone to occur in the maleic anhydride esterification hydrogenation process, and avoidance of the severe acid corrosion problem on equipment in the maleic anhydride aqueous solution hydrogenation process. Simultaneously, this technology needs to achieve the co-production of 1,4-butanediol, tetrahydrofuran, and γ-butyrolactone by controlling reaction conditions. Summary of the Invention

[0012] To address the shortcomings of existing technologies, this invention relates to a production process for 1,4-butanediol, and particularly to a process for producing high-purity 1,4-butanediol from maleic anhydride. The maleic anhydride-to-1,4-butanediol production process uses maleic anhydride and hydrogen as raw materials, employing a direct hydrogenation method to co-produce 1,4-butanediol and tetrahydrofuran, or alternatively, a tri-product co-production of 1,4-butanediol, tetrahydrofuran, and γ-butyrolactone. The objective of this invention is to provide a novel process for producing high-purity 1,4-butanediol from maleic anhydride through direct hydrogenation, simultaneously producing high-purity tetrahydrofuran and γ-butyrolactone. This process allows for flexible adjustments to product output based on market changes, thereby better meeting market demands.

[0013] This invention proposes a direct hydrogenation method for maleic anhydride, which involves dissolving maleic anhydride in a high-boiling-point non-aqueous solvent and performing gas-phase or liquid-phase hydrogenation to produce 1,4-butanediol. Maleic anhydride hydrogenation produces succinic anhydride, which is then hydrogenated and dehydrated to produce γ-butyrolactone. Further hydrogenation of γ-butyrolactone yields 1,4-butanediol. The entire process is a continuous hydrogenation process from maleic anhydride to 1,4-butanediol. Compared to the aqueous solution hydrogenation method and the esterification hydrogenation method, the direct hydrogenation method for maleic anhydride has a shorter process flow, avoids the transesterification side reactions that easily occur in the esterification hydrogenation process, and also avoids the severe acid corrosion of equipment in the aqueous solution hydrogenation process. Cu-based and Ni-based catalysts are commonly used and are inexpensive. Simultaneously, 1,4-butanediol, tetrahydrofuran, and γ-butyrolactone can be co-produced by controlling the reaction conditions.

[0014] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0015] The process for producing 1,4-butanediol from maleic anhydride uses maleic anhydride and hydrogen as raw materials, employing a direct hydrogenation method to co-produce 1,4-butanediol and tetrahydrofuran; it can also co-produce 1,4-butanediol, tetrahydrofuran, and γ-butyrolactone. The process includes a maleic anhydride hydrogenation reaction unit, a product separation unit, and γ-butyrolactone hydrogenation and 1,4-butanediol separation units. The maleic anhydride hydrogenation reaction unit is equipped with a maleic anhydride hydrogenation reactor; the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit is equipped with a γ-butyrolactone hydrogenation reactor; and the different products are generated through system operation adjustments.

[0016] The aforementioned process for producing 1,4-butanediol from maleic anhydride includes a product separation unit comprising a tetrahydrofuran separation process and a γ-butyrolactone and 1,4-butanediol separation process. Tetrahydrofuran and water are separated using a combination of a tetrahydrofuran crude fractionation column, an extractive distillation column, and an extractant recovery column to obtain a high-purity tetrahydrofuran product. The azeotrope of tetrahydrofuran and water is successively passed through the tetrahydrofuran crude fractionation column, the extractive distillation column, and the extractant recovery column, using ethylene glycol as the extractant.

[0017] The process for producing 1,4-butanediol from maleic anhydride employs a membrane separation device to separate and purify the hydrogen streams separated from the hydrogenation of γ-butyrolactone and the separation unit of 1,4-butanediol, obtaining high-purity hydrogen gas for use as circulating hydrogen gas, which is then recycled back to the feed of the maleic anhydride hydrogenation reaction unit.

[0018] The apparatus for producing 1,4-butanediol from maleic anhydride according to the present invention includes a maleic anhydride hydrogenation reaction unit comprising a hydrogen feed compressor C101, a maleic anhydride hydrogenation reactor R101, a first hydrogen separator V101, a first atmospheric pressure tank V102, a hydrogen feed preheater E101, a maleic anhydride feed preheater E102, a maleic anhydride hydrogenation reactor outlet heat exchanger E103, a maleic anhydride feed pump P101, a tetrahydrofuran dehydrogenation tower feed pump P102, a hydrogen feed mixer F101, and a first raw material mixer F102. The product separation unit includes a tetrahydrofuran removal column T201, a tetrahydrofuran crude fractionation column T202, an extractive distillation column T203, an extractant recovery column T204, a first light component removal column T205, a γ-butyrolactone refining column T206, a 1,4-butanediol refining column T207, a circulating extractant heat exchanger E201, a tetrahydrofuran removal column bottom liquid heat exchanger E202, a γ-butyrolactone preheater E203, a 1,4-butanediol refining column feed heat exchanger E204, a tetrahydrofuran crude fractionation column feed pump P201, and an extraction column... Extractant recovery tower feed pump P202, tetrahydrofuran product transfer pump P203, first low-boiling waste liquid transfer pump P204, extractant circulation pump P205, second low-boiling waste liquid transfer pump P206, γ-butyrolactone refining tower feed pump P207, first high-boiling waste liquid transfer pump P208, γ-butyrolactone product transfer pump P209, crude 1,4-butanediol first transfer pump P210, 1,4-butanediol product transfer pump P211, second high-boiling waste liquid transfer pump P212, ethylene glycol mixer F201 The crude 1,4-butanediol mixer F202; the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit includes a γ-butyrolactone hydrogenation reactor R301, a second light-removal tower T301, a second hydrogen separator V301, a second atmospheric pressure tank V302, a membrane separation device V303, a feed preheater E301, a γ-butyrolactone hydrogenation reactor outlet heat exchanger E302, a crude 1,4-butanediol second transfer pump P301, a third high-boiling waste liquid transfer pump P302, and a second raw material mixer F301.

[0019] In the apparatus for producing 1,4-butanediol from maleic anhydride, in the maleic anhydride hydrogenation reaction unit, the inlet of the hydrogen feed compressor C101 is connected to the hydrogen feed pipeline, and the outlet is connected to the inlet of the hydrogen feed mixer F101; the outlet of the hydrogen feed mixer F101 is connected to the inlet of the hydrogen feed preheater E101; the inlet of the maleic anhydride feed pump P101 is connected to the maleic anhydride feed pipeline, and the outlet is connected to the inlet of the maleic anhydride feed preheater E102; the inlet of the first raw material mixer F102 is connected to both the outlet of the hydrogen feed preheater E101 and the outlet of the maleic anhydride feed preheater E102, and the outlet is connected to the maleic anhydride hydrogenation reactor R. 101 inlet connection; maleic anhydride hydrogenation reactor R101 outlet is connected to maleic anhydride hydrogenation reactor outlet heat exchanger E103 inlet; maleic anhydride hydrogenation reactor outlet heat exchanger E103 outlet is connected to first hydrogen separator V101 inlet; first hydrogen separator V101 top outlet is connected to second raw material mixer F301 inlet, tower bottom outlet is connected to first atmospheric pressure tank V102 inlet; first atmospheric pressure tank V102 top outlet is connected to flare, tower bottom outlet is connected to tetrahydrofuran dehydrogenation tower feed pump P102 inlet; tetrahydrofuran dehydrogenation tower feed pump P102 outlet is connected to tetrahydrofuran dehydrogenation tower T201 inlet.

[0020] In the apparatus for the production of 1,4-butanediol from maleic anhydride, in the product separation unit, the top outlet of the tetrahydrofuran dehydrofuran tower T201 is connected to the flare and the inlet of the feed pump P201 to the tetrahydrofuran crude fractionation tower, and the bottom outlet is connected to the inlet of the bottom liquid heat exchanger E202 of the tetrahydrofuran dehydrofuran tower; the outlet of the feed pump P201 to the tetrahydrofuran crude fractionation tower is connected to the inlet of the tetrahydrofuran crude fractionation tower T202; the top outlet of the tetrahydrofuran crude fractionation tower T202 is connected to the flare and the inlet of the extractive distillation tower T203, and the bottom outlet is connected to the inlet of the second low-boiling waste liquid transfer pump P206; the outlet of the second low-boiling waste liquid transfer pump P206 is connected to the waste liquid treatment device; the top outlet of the extractive distillation tower T203 is connected to the flare and the inlet of the tetrahydrofuran product transfer pump P203; the tetrahydrofuran product transfer... Pump P203 outlet is connected to the tetrahydrofuran product tank; the bottom outlet of extractive distillation column T203 is connected to the inlet of extractant recovery column feed pump P202; the outlet of extractant recovery column feed pump P202 is connected to the inlet of extractant recovery column T204, the top outlet of extractant recovery column T204 is connected to the inlet of first low-boiling waste liquid transfer pump P204, and the outlet of first low-boiling waste liquid transfer pump P204 is connected to the waste liquid treatment device; the bottom outlet of extractant recovery column T204 is connected to the inlet of extractant circulation pump P205, and the outlet of extractant circulation pump P205 is connected to the inlet of circulating extractant heat exchanger E201; the inlet of ethylene glycol mixer F201 is connected to the outlet of circulating extractant heat exchanger E201 and the ethylene glycol feed pipeline, and the outlet is connected to extractive distillation column T203. 3. Inlet Connections: The inlet of the first light-removal tower T205 is connected to the outlet of the bottom liquid heat exchanger E202 of the tetrahydrofuran removal tower; the top outlet of the tower is connected to the inlet of the feed pump P207 of the γ-butyrolactone refining tower; the bottom outlet of the tower is connected to the inlet of the first crude 1,4-butanediol transfer pump P210; the inlet of the γ-butyrolactone refining tower T206 is connected to the outlet of the feed pump P207 of the γ-butyrolactone refining tower; the top outlet of the tower is connected to the inlet of the first high-boiling waste liquid transfer pump P208; the bottom outlet of the tower is connected to the inlet of the γ-butyrolactone preheater E203; the outlet of the first high-boiling waste liquid transfer pump P208 is connected to the waste liquid treatment device; the outlet of the γ-butyrolactone preheater E203 is connected to the inlet of the γ-butyrolactone product transfer pump P209; the outlet of the γ-butyrolactone product transfer pump P209 is connected to the second... The inlet of the raw material mixer F301 is connected; the inlet of the crude 1,4-butanediol mixer F202 is connected to the outlet of the first crude 1,4-butanediol transfer pump P210 and the outlet of the second crude 1,4-butanediol transfer pump P301, and the outlet is connected to the inlet of the feed heat exchanger E204 of the 1,4-butanediol refining tower; the inlet of the 1,4-butanediol refining tower T207 is connected to the outlet of the feed heat exchanger E204 of the 1,4-butanediol refining tower, the top outlet of the tower is connected to the inlet of the 1,4-butanediol product transfer pump P211, and the bottom outlet of the tower is connected to the inlet of the second high-boiling waste liquid transfer pump P212; the outlet of the 1,4-butanediol product transfer pump P211 is connected to the 1,4-butanediol product tank, and the outlet of the second high-boiling waste liquid transfer pump P212 is connected to the waste liquid treatment device.

[0021] In the apparatus for the production of 1,4-butanediol from maleic anhydride, in the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit, the outlet of the second feed mixer F301 is connected to the inlet of the feed preheater E301; the inlet of the γ-butyrolactone hydrogenation reactor R301 is connected to the outlet of the feed preheater E301, and the outlet is connected to the inlet of the outlet heat exchanger E302 of the γ-butyrolactone hydrogenation reactor; the inlet of the second hydrogen separator V301 is connected to the outlet of the outlet heat exchanger E302 of the γ-butyrolactone hydrogenation reactor, and the top outlet of the separator is connected to the membrane separation device V303. The inlet is connected to the bottom outlet of the second atmospheric pressure tank V302; the outlet of the membrane separation unit V303 is connected to the flare and the inlet of the hydrogen feed mixer F101; the top outlet of the second atmospheric pressure tank V302 is connected to the flare, and the bottom outlet is connected to the inlet of the second light-duty removal tower T301; the top outlet of the second light-duty removal tower T301 is connected to the flare and the inlet of the third high-boiling waste liquid transfer pump P302, and the bottom outlet is connected to the inlet of the second crude 1,4-butanediol transfer pump P301; the outlet of the third high-boiling waste liquid transfer pump P302 is connected to the waste liquid treatment device.

[0022] The apparatus for producing 1,4-butanediol from maleic anhydride involves the following steps: Fresh hydrogen is pressurized by a hydrogen feed compressor C101 and mixed with recycled hydrogen in a hydrogen feed mixer F101. After being heated by a hydrogen feed preheater E101, it is mixed with maleic anhydride. Maleic anhydride is pressurized by a maleic anhydride feed pump P101 and preheated by a maleic anhydride feed preheater E102 before being fed into a first raw material mixer F102 to mix with hydrogen. The mixed hydrogen and maleic anhydride stream is then fed into a maleic anhydride hydrogenation reactor R101 for reaction. The reaction proceeds from γ-butyrolactone... The γ-butyrolactone product stream from the γ-butyrolactone product transfer pump P209 in the separation process of γ-butyrolactone and 1,4-butanediol enters the second raw material mixer F301 and is mixed with the hydrogen stream separated from the top of the first hydrogen separator V101 of the maleic anhydride hydrogenation reaction unit. After being preheated to the reaction temperature by the feed preheater E301, the mixed raw material stream enters the γ-butyrolactone hydrogenation reactor R301 for reaction. When the market demand for 1,4-butanediol is high, the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit is activated.

[0023] In the apparatus for the production of 1,4-butanediol from maleic anhydride, the top stream from the tetrahydrofuran removal tower T201 is fed into the tetrahydrofuran roughing tower T202 via the tetrahydrofuran roughing tower feed pump P201; the top stream from the tetrahydrofuran roughing tower T202 is directly fed into the extractive distillation tower T203; fresh ethylene glycol is mixed with ethylene glycol recycled from the extractant recovery tower T204 and then enters the extractive distillation tower T203; the mass fraction of tetrahydrofuran in the top stream of the extractive distillation tower T203 is ≥99.99%, and the mass fraction of water is ≤0.19%. ppm; The bottom stream of extractive distillation column T203 is fed into extractant recovery column T204 via extractant recovery column feed pump P202; Ethylene glycol recovered from the bottom stream of extractant recovery column T204 is mixed with fresh ethylene glycol after passing through extractant circulation pump P205 and circulating extractant heat exchanger E201, and then fed into extractive distillation column T203; The top stream of extractant recovery column T204 is sent to the waste liquid treatment device as low-boiling waste liquid.

[0024] In the apparatus for the production process of maleic anhydride to 1,4-butanediol, the gas stream from the second hydrogen separator V301 in the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit is sent back to the maleic anhydride hydrogenation reaction unit as circulating hydrogen. After being separated by the membrane separation device V303, the organic waste gas is mixed with fresh hydrogen and then sent to the flare for incineration.

[0025] The production process for 1,4-butanediol from maleic anhydride of the present invention produces high-quality 1,4-butanediol and high-quality tetrahydrofuran as a byproduct through a direct hydrogenation co-production process of maleic anhydride; alternatively, by adjusting the hydrogenation of γ-butyrolactone and the separation unit of 1,4-butanediol, the yield of high-quality 1,4-butanediol can be reduced while high-quality tetrahydrofuran and high-quality γ-butyrolactone are produced as byproducts.

[0026] The process for producing 1,4-butanediol, tetrahydrofuran, and γ-butyrolactone by direct hydrogenation of maleic anhydride comprises three systems: a maleic anhydride hydrogenation reaction unit, a product separation unit (including the separation processes of tetrahydrofuran and γ-butyrolactone and 1,4-butanediol), and a γ-butyrolactone hydrogenation and 1,4-butanediol separation unit. The roles of the different systems in the process are as follows:

[0027] (1) Maleic anhydride hydrogenation reaction unit. Fresh hydrogen gas is pressurized and mixed with recycled hydrogen gas. After being heated through a heat exchanger, it is mixed with preheated maleic anhydride in a mixer. The mixed feedstock reacts to mainly produce γ-butyrolactone, 1,4-butanediol, tetrahydrofuran, and water, with small amounts of n-butanol, propionic acid, and CO. The hydrogenation product is separated after heat recovery through a heat exchanger. The recovered hydrogen gas is sent to the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit for γ-butyrolactone hydrogenation. The liquid stream is cooled to atmospheric pressure in an atmospheric pressure tank and then subjected to subsequent distillation separation.

[0028] (2) Separation process of tetrahydrofuran. After distillation separation of the liquid phase product from the maleic anhydride hydrogenation reaction unit, a stream containing some water, tetrahydrofuran, and n-butanol is separated for further crude component separation. The crude component separation yields two streams: one is a low-boiling waste liquid containing water, n-butanol, and propionic acid; the other is crude tetrahydrofuran containing small amounts of water, tetrahydrofuran, and n-butanol. The low-boiling waste liquid is sent to the waste liquid treatment unit. Fresh ethylene glycol and recycled ethylene glycol are mixed and used as extractant, and co-extracted with crude tetrahydrofuran for extractive distillation. After extractive distillation, a tetrahydrofuran product with a purity ≥99.99 wt% and a liquid phase stream containing the extractant are obtained. The liquid phase stream containing the extractant is used for extractant recovery, and the recovered extractant ethylene glycol is recycled back and mixed with fresh extractant.

[0029] (3) Separation process of γ-butyrolactone and 1,4-butanediol. After distillation separation of the liquid-phase product from the maleic anhydride hydrogenation unit, a stream containing 1,4-butanediol, γ-butyrolactone, a small amount of propionic acid, and water is separated and further subjected to vacuum distillation. Vacuum distillation yields two streams. One stream contains 1,4-butanediol and heavy components such as tar that may occur in actual production. This stream is mixed with crude 1,4-butanediol from the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit and then purified to obtain a 1,4-butanediol product with a purity ≥99.70 wt%. The other stream obtained from vacuum distillation contains γ-butyrolactone, water, and propionic acid. This stream is purified for γ-butyrolactone and separated into two streams. One stream, containing γ-butyrolactone with a purity ≥99.70 wt%, is sent to the γ-butyrolactone product tank or to the raw material mixer of the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit for γ-butyrolactone hydrogenation reaction; the other stream is sent to the waste liquid treatment unit as low-boiling waste liquid.

[0030] (4) γ-Butyrolactone hydrogenation and 1,4-Butanediol separation unit. Hydrogen separated from the maleic anhydride hydrogenation reaction unit is mixed with the γ-butyrolactone product in a mixer, and the mixture is heated to the reaction temperature to carry out the γ-butyrolactone hydrogenation reaction. The γ-butyrolactone hydrogenation mainly produces 1,4-butanediol, with small amounts of tetrahydrofuran and water. Excess hydrogen separated from the hydrogenation product is separated into organic components by a membrane separation device and then recycled back to the maleic anhydride hydrogenation reaction unit to be mixed with fresh hydrogen. The liquid stream is cooled to atmospheric pressure in an atmospheric pressure tank and then subjected to vacuum distillation. Vacuum distillation yields two streams. One stream is mixed with the crude 1,4-butanediol from the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit for 1,4-butanediol purification. The other stream is sent to the waste liquid treatment unit as low-boiling waste liquid.

[0031] When the γ-butyrolactone hydrogenation and 1,4-butanediol separation units are turned on, this process mainly achieves the co-production of 1,4-butanediol and tetrahydrofuran; when the γ-butyrolactone hydrogenation and 1,4-butanediol separation units are turned off, this process mainly achieves the co-production of 1,4-butanediol, tetrahydrofuran, and γ-butyrolactone. By controlling the on / off state of the γ-butyrolactone hydrogenation and 1,4-butanediol separation units, this production process can flexibly adjust product output according to market changes, thereby better responding to market demands.

[0032] While existing technologies such as maleic anhydride aqueous solution hydrogenation and maleic anhydride esterification hydrogenation can co-produce 1,4-butanediol, tetrahydrofuran, and γ-butyrolactone, they cannot achieve the product yield variation achieved by controlling the γ-butyrolactone hydrogenation process as described in this invention. This is because in existing technologies, the maleic anhydride aqueous solution hydrogenation method involves relatively high temperatures and pressures, and the presence of acid in the reaction system causes severe equipment corrosion; the maleic anhydride esterification hydrogenation method involves a large amount of methanol circulating in the system, and methanol forms an azeotropic component with tetrahydrofuran. Therefore, using the method of this invention to control product yield variation would result in the final product purity not meeting market demands.

[0033] The process apparatus for producing 1,4-butanediol from maleic anhydride according to the present invention includes a maleic anhydride hydrogenation reaction unit comprising a hydrogen feed compressor C101, a maleic anhydride hydrogenation reactor R101, a first hydrogen separator V101, a first atmospheric pressure tank V102, a hydrogen feed preheater E101, a maleic anhydride feed preheater E102, a maleic anhydride hydrogenation reactor outlet heat exchanger E103, a maleic anhydride feed pump P101, a tetrahydrofuran removal tower feed pump P102, a hydrogen feed mixer F101, and a first raw material mixer F102; The product separation unit includes a tetrahydrofuran de-tetrahydrofuran column T201, a tetrahydrofuran crude fractionation column T202, an extractive distillation column T203, an extractant recovery column T204, a first light component removal column T205, a γ-butyrolactone purification column T206, a 1,4-butanediol purification column T207, a circulating extractant heat exchanger E201, a tetrahydrofuran de-tetrahydrofuran column bottom liquid heat exchanger E202, a γ-butyrolactone preheater E203, a 1,4-butanediol purification column feed heat exchanger E204, a tetrahydrofuran crude fractionation column feed pump P201, and an extractant... Recovery tower feed pump P202, tetrahydrofuran product transfer pump P203, first low-boiling waste liquid transfer pump P204, extractant circulation pump P205, second low-boiling waste liquid transfer pump P206, γ-butyrolactone refining tower feed pump P207, first high-boiling waste liquid transfer pump P208, γ-butyrolactone product transfer pump P209, crude 1,4-butanediol first transfer pump P210, 1,4-butanediol product transfer pump P211, second high-boiling waste liquid transfer pump P212, ethylene glycol mixer F201 The system includes: a crude 1,4-butanediol mixer F202; and a γ-butyrolactone hydrogenation and 1,4-butanediol separation unit comprising a γ-butyrolactone hydrogenation reactor R301, a second light-weight removal tower T301, a second hydrogen separator V301, a second atmospheric pressure tank V302, a membrane separator V303, a feed preheater E301, a γ-butyrolactone hydrogenation reactor outlet heat exchanger E302, a crude 1,4-butanediol second transfer pump P301, a third high-boiling waste liquid transfer pump P302, and a second raw material mixer F301. The connections between the equipment are as follows:

[0034] (1) In the maleic anhydride hydrogenation reaction unit, the inlet of the hydrogen feed compressor C101 is connected to the hydrogen feed pipeline, and the outlet is connected to the inlet of the hydrogen feed mixer F101. The outlet of the hydrogen feed mixer F101 is connected to the inlet of the hydrogen feed preheater E101. The inlet of the maleic anhydride feed pump P101 is connected to the maleic anhydride feed pipeline, and the outlet is connected to the inlet of the maleic anhydride feed preheater E102. The inlet of the first raw material mixer F102 is connected to the outlet of the hydrogen feed preheater E101 and the outlet of the maleic anhydride feed preheater E102, respectively, and the outlet is connected to the inlet of the maleic anhydride hydrogenation reactor R101. The outlet of the maleic anhydride hydrogenation reactor R101 is connected to the inlet of the maleic anhydride hydrogenation reactor outlet heat exchanger E103. The outlet of the maleic anhydride hydrogenation reactor outlet heat exchanger E103 is connected to the inlet of the first hydrogen separator V101. The top outlet of the first hydrogen separator V101 is connected to the inlet of the second feed mixer F301, and the bottom outlet is connected to the inlet of the first atmospheric pressure tank V102. The top outlet of the first atmospheric pressure tank V102 is connected to the flare, and the bottom outlet is connected to the inlet of the tetrahydrofuran dehydrogenation tower feed pump P102. The outlet of the tetrahydrofuran dehydrogenation tower feed pump P102 is connected to the inlet of the tetrahydrofuran dehydrogenation tower T201.

[0035] (2) In the product separation unit, the top outlet of the tetrahydrofuran de-tetrahydrofuran tower T201 is connected to the flare and the inlet of the tetrahydrofuran crude fractionation tower feed pump P201, and the bottom outlet is connected to the inlet of the tetrahydrofuran de-tetrahydrofuran tower bottom liquid heat exchanger E202. The outlet of the tetrahydrofuran crude fractionation tower feed pump P201 is connected to the inlet of the tetrahydrofuran crude fractionation tower T202. The top outlet of the tetrahydrofuran crude fractionation tower T202 is connected to the flare and the inlet of the extractive distillation tower T203, and the bottom outlet is connected to the inlet of the second low-boiling waste liquid transfer pump P206. The outlet of the second low-boiling waste liquid transfer pump P206 is connected to the waste liquid treatment device. The top outlet of the extractive distillation tower T203 is connected to the flare and the inlet of the tetrahydrofuran product transfer pump P203. The outlet of the tetrahydrofuran product transfer pump P203 is connected to the tetrahydrofuran product tank. The bottom outlet of the extractive distillation tower T203 is connected to the inlet of the extractant recovery tower feed pump P202. The outlet of the feed pump P202 of the extractant recovery tower is connected to the inlet of the extractant recovery tower T204. The top outlet of the extractant recovery tower T204 is connected to the inlet of the first low-boiling waste liquid transfer pump P204, and the outlet of the first low-boiling waste liquid transfer pump P204 is connected to the waste liquid treatment device. The bottom outlet of the extractant recovery tower T204 is connected to the inlet of the extractant circulation pump P205, and the outlet of the extractant circulation pump P205 is connected to the inlet of the circulating extractant heat exchanger E201. The inlet of the ethylene glycol mixer F201 is connected to the outlet of the circulating extractant heat exchanger E201 and the ethylene glycol feed pipeline, and the outlet is connected to the inlet of the extractive distillation tower T203. The inlet of the first light-removal tower T205 is connected to the outlet of the bottom liquid heat exchanger E202 of the tetrahydrofuran removal tower, the top outlet of the tower is connected to the inlet of the feed pump P207 of the γ-butyrolactone refining tower, and the bottom outlet of the tower is connected to the inlet of the first crude 1,4-butanediol transfer pump P210. The inlet of the γ-butyrolactone refining tower T206 is connected to the outlet of the γ-butyrolactone refining tower feed pump P207. The top outlet of the tower is connected to the inlet of the first high-boiling waste liquid transfer pump P208, and the bottom outlet of the tower is connected to the inlet of the γ-butyrolactone preheater E203. The outlet of the first high-boiling waste liquid transfer pump P208 is connected to the waste liquid treatment device, and the outlet of the γ-butyrolactone preheater E203 is connected to the inlet of the γ-butyrolactone product transfer pump P209. The outlet of the γ-butyrolactone product transfer pump P209 is connected to the inlet of the second raw material mixer F301. The inlet of the crude 1,4-butanediol mixer F202 is connected to the outlet of the first crude 1,4-butanediol transfer pump P210 and the outlet of the second crude 1,4-butanediol transfer pump P301, and the outlet is connected to the inlet of the 1,4-butanediol refining tower feed heat exchanger E204. The inlet of the 1,4-butanediol refining tower T207 is connected to the outlet of the 1,4-butanediol refining tower feed heat exchanger E204. The top outlet of the tower is connected to the inlet of the 1,4-butanediol product transfer pump P211, and the bottom outlet of the tower is connected to the inlet of the second high-boiling waste liquid transfer pump P212. The outlet of the 1,4-butanediol product transfer pump P211 is connected to the 1,4-butanediol product tank, and the outlet of the second high-boiling waste liquid transfer pump P212 is connected to the waste liquid treatment device.

[0036] (3) In the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit, the outlet of the second feed mixer F301 is connected to the inlet of the feed preheater E301. The inlet of the γ-butyrolactone hydrogenation reactor R301 is connected to the outlet of the feed preheater E301, and the outlet is connected to the inlet of the γ-butyrolactone hydrogenation reactor outlet heat exchanger E302. The inlet of the second hydrogen separator V301 is connected to the outlet of the γ-butyrolactone hydrogenation reactor outlet heat exchanger E302, the top outlet of the separator is connected to the inlet of the membrane separation unit V303, and the bottom outlet of the separator is connected to the inlet of the second atmospheric pressure tank V302. The outlet of the membrane separation unit V303 is connected to the flare and the inlet of the hydrogen feed mixer F101. The top outlet of the second atmospheric pressure tank V302 is connected to the flare, and the bottom outlet of the tank is connected to the inlet of the second light-weight removal tower T301. The top outlet of the second light-weight removal tower T301 is connected to the flare and the inlet of the third high-boiling-point waste liquid transfer pump P302, while the bottom outlet is connected to the inlet of the second crude 1,4-butanediol transfer pump P301. The outlet of the third high-boiling-point waste liquid transfer pump P302 is connected to the waste liquid treatment unit.

[0037] The specific operation process for producing 1,4-butanediol from maleic anhydride according to the present invention is as follows:

[0038] (1) Maleic anhydride hydrogenation reaction unit

[0039] Fresh hydrogen is pressurized by the hydrogen feed compressor C101 and mixed with circulating hydrogen in the hydrogen feed mixer F101. After being heated to the reaction temperature of 200 °C by the hydrogen feed preheater E101, it is mixed with maleic anhydride. Maleic anhydride is pressurized by the maleic anhydride feed pump P101 and preheated by the maleic anhydride feed preheater E102 before being fed into the first raw material mixer F102 to mix with hydrogen. The mixed hydrogen and maleic anhydride stream is then fed into the maleic anhydride hydrogenation reactor R101 for reaction. The outlet stream of the maleic anhydride hydrogenation reactor is cooled by the maleic anhydride hydrogenation reactor outlet heat exchanger E103 and then sent to the first hydrogen separator V101 to recover excess hydrogen.

[0040] The recovered hydrogen is sent to the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit for γ-butyrolactone hydrogenation. Excess hydrogen separated from the top of the hydrogen separator V301 in this unit, containing trace amounts of CO, tetrahydrofuran, water, and other organic matter, is sent to the membrane separation unit V303 for hydrogen stream separation. The hydrogen stream that permeates through the membrane can be mixed with fresh hydrogen as recycled hydrogen, while the organic gases that do not permeate through the membrane are incinerated as waste gas. The separated high-purity hydrogen is mixed with fresh hydrogen, and the organic components are sent to a flare for incineration as waste gas. The liquid stream from the bottom of the first hydrogen separator V101 is sent to the first atmospheric pressure tank V102, where it is reduced to atmospheric pressure and then fed into the tetrahydrofuran dehydrofuran tower T201 via the tetrahydrofuran dehydrofuran tower feed pump P102 for subsequent product separation.

[0041] (2) Product separation unit

[0042] 2.1 Separation process of tetrahydrofuran

[0043] The product stream from the maleic anhydride hydrogenation unit's tetrahydrofuran removal column feed pump P102 enters the tetrahydrofuran removal column T201 for separation. The purpose of the tetrahydrofuran removal column is to obtain a stream mainly composed of tetrahydrofuran, water, and n-butanol from the top of the column, which is then fed to subsequent tetrahydrofuran roughing columns and extractive distillation columns to obtain high-purity tetrahydrofuran product. A stream mainly composed of γ-butyrolactone and 1,4-butanediol from the bottom of the column is sent to a subsequent light-removal column for the separation of γ-butyrolactone and 1,4-butanediol, which are then separately fed to 1,4-butanediol refining columns and γ-butyrolactone refining columns to obtain high-purity 1,4-butanediol and γ-butyrolactone products. The stream collected from the top of the column is fed to the tetrahydrofuran roughing column T202 via the tetrahydrofuran roughing column feed pump P201 for further separation. The waste gas stream from the top of the column is sent to a flare for incineration.

[0044] The fraction collected from the top of the tetrahydrofuran removal column contains a large amount of water. To reduce the amount of extractant used in subsequent extractive distillation, this fraction needs to be coarsely separated in the tetrahydrofuran roughing column T202 to remove the significant amount of water. The stream collected from the top of the tetrahydrofuran roughing column T202 is directly fed into the extractive distillation column T203 to obtain high-purity tetrahydrofuran product. The waste stream from the top of the column is sent to a flare for incineration. The bottom stream is sent to a waste liquid treatment unit as low-boiling waste liquid.

[0045] The overhead stream from the tetrahydrofuran crude fractionator T202 enters the extractive distillation column T203 for separation. Fresh ethylene glycol is mixed with ethylene glycol recycled from the extractant recovery column T204 and then enters the extractive distillation column. The tetrahydrofuran mass fraction in the overhead stream of the extractive distillation column is ≥99.99%, and the water mass fraction is ≤0.19 ppm. According to the specifications for tetrahydrofuran products in GB / T 24772-2009 Industrial Tetrahydrofuran, the tetrahydrofuran product obtained by this process meets the superior grade standard. The tetrahydrofuran product obtained from the top of the column is sent to the tetrahydrofuran product tank for storage. The main component of the bottom stream is ethylene glycol, with small amounts of n-butanol, propionic acid, and tetrahydrofuran. The outflow from the bottom of the column is fed into the extractant recovery column T204 via the extractant recovery column feed pump P202 to recover the extractant ethylene glycol. The recovered ethylene glycol can be mixed with fresh ethylene glycol and then fed into the extractive distillation column.

[0046] Extractant recovery tower T204 is used to recover the extractant ethylene glycol. The ethylene glycol recovered from the bottom stream of the extractant recovery tower has a purity of ≥99.99 wt%. The bottom stream is mixed with fresh ethylene glycol after passing through the extractant circulation pump P205 and the circulating extractant heat exchanger E201, and then sent to the extractive distillation tower. The top stream is a mixture of a small amount of ethylene glycol, water, and n-butanol, which is sent to the waste liquid treatment unit as low-boiling waste liquid.

[0047] 2.2 Separation process of γ-butyrolactone and 1,4-butanediol

[0048] The main components of the bottom stream in the tetrahydrofuran removal tower T201 include γ-butyrolactone, 1,4-butanediol, and small amounts of propionic acid and water. This stream is sent to the separation process of γ-butyrolactone and 1,4-butanediol to obtain high-purity 1,4-butanediol and γ-butyrolactone products. The bottom stream of the tetrahydrofuran removal tower first recovers heat through the bottom liquid heat exchanger E202, and then is sent to the first light component removal tower T205 for separation. The purpose of the first light component removal tower is to separate γ-butyrolactone and light components with lower boiling points than γ-butyrolactone from 1,4-butanediol and heavy components such as tar that may appear in the actual process. The overhead stream of the first light component removal tower contains a large amount of γ-butyrolactone, a small amount of 1,4-butanediol and propionic acid, and is sent to the γ-butyrolactone refining tower T206 for separation to obtain high-purity γ-butyrolactone products. The bottom stream of the first light removal tower contains a small amount of γ-butyrolactone, a large amount of 1,4-butanediol, and heavy components such as tar that may appear in the actual process. It is sent to the 1,4-butanediol refining tower T207 for separation to obtain high-purity 1,4-butanediol product.

[0049] The T206 γ-butyrolactone refining column is used to separate γ-butyrolactone from other impurities to obtain a high-purity γ-butyrolactone product. After separation in the γ-butyrolactone refining column, most of the γ-butyrolactone in the feed stream is collected from the bottom stream, which also contains a small amount of 1,4-butanediol. The overhead stream contains a small amount of γ-butyrolactone, water, and propionic acid, which is sent to the waste liquid treatment unit as low-boiling waste liquid. According to HG / T 4989-2016 Industrial γ-butyrolactone, the superior grade of γ-butyrolactone must have a γ-butyrolactone content ≥ 99.70 wt% and a water content ≤ 0.05 wt%. The γ-butyrolactone mass fraction in the bottom stream of the γ-butyrolactone refining column is ≥ 99.70%, and the water mass fraction is < 0.05%. The γ-butyrolactone product obtained by this process has reached the superior grade standard. The obtained γ-butyrolactone product can be sent to the γ-butyrolactone product tank, or the generated γ-butyrolactone can be sent to the next system, namely the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit, for further hydrogenation and separation, thereby obtaining more 1,4-butanediol product.

[0050] The bottom stream of the first light component removal tower, containing crude 1,4-butanediol product, is mixed with the crude 1,4-butanediol product stream from the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit via the first crude 1,4-butanediol transfer pump P210 in the crude 1,4-butanediol mixer F202. After mixing, the stream is fed into the 1,4-butanediol refining tower T207 via the feed heat exchanger E204 for separation. The purpose of the 1,4-butanediol refining tower is to obtain high-purity 1,4-butanediol product from the top, while the heavy components such as tar are collected from the bottom and sent as high-boiling waste liquid to the waste liquid treatment unit. The top stream of the 1,4-butanediol refining tower yields 1,4-butanediol product with a purity ≥99.70 wt%. According to the purity requirements for 1,4-butanediol products specified in GB / T 24768-2009 "1,4-Butanediol for Industrial Use", the 1,4-butanediol products produced by this process have reached the superior grade standard.

[0051] This process allows for adjustment of the operation of the γ-butyrolactone hydrogenation and 1,4-butanediol separation units. After separation in the 1,4-butanediol refining column, a 1,4-butanediol product with a purity ≥99.70 wt% can be obtained at the top of the column. According to the purity requirements for 1,4-butanediol products in GB / T24768-2009 "1,4-Butanediol for Industrial Use", the 1,4-butanediol product obtained by this process has reached the superior grade standard.

[0052] The 1,4-butanediol product stream is sent to the 1,4-butanediol product tank for storage via the 1,4-butanediol product transfer pump P211. The bottom stream of the 1,4-butanediol refining column contains a small amount of 1,4-butanediol and heavy components such as tar that may occur in actual production. After recovering the 1,4-butanediol product in the bottom stream through a falling film evaporator, it is sent to the waste liquid treatment unit as high-boiling waste liquid.

[0053] (3) Separation unit for hydrogenation of γ-butyrolactone and 1,4-butanediol

[0054] This system is designed to further hydrogenate and separate the obtained γ-butyrolactone product to obtain more high-purity 1,4-butanediol product. The γ-butyrolactone product stream from the γ-butyrolactone and 1,4-butanediol separation process, delivered by pump P209, enters the second feed mixer F301 and mixes with the hydrogen stream separated from the top of the first hydrogen separator V101 in the maleic anhydride hydrogenation reaction unit. The mixed feed stream is preheated to the reaction temperature of 180 °C by the feed preheater E301 before entering the γ-butyrolactone hydrogenation reactor R301 for reaction. The reactor product stream is cooled by the γ-butyrolactone hydrogenation reactor outlet heat exchanger E302 and then sent to the second hydrogen separator V301 to recover excess hydrogen. The gas stream from the second hydrogen separator is returned to the maleic anhydride hydrogenation reaction unit as circulating hydrogen. After being separated by a membrane separator, the organic waste gas is mixed with fresh hydrogen and then sent to a flare for incineration. The liquid stream from the second hydrogen separator is sent to the second atmospheric pressure tank V302 to be reduced to atmospheric pressure before being sent to the second light-weight gas removal tower T301 for further separation.

[0055] The purpose of the second light component removal tower is to separate γ-butyrolactone and light components with lower boiling points than γ-butyrolactone from 1,4-butanediol and heavy components such as tar that may appear during the actual process. The bottom stream of the second light component removal tower is fed into the crude 1,4-butanediol mixer F202 via the second crude 1,4-butanediol transfer pump P301 to mix with the crude 1,4-butanediol stream from the first crude 1,4-butanediol transfer pump P210 from the product separation unit. The mixed stream is then fed into the 1,4-butanediol refining tower T207 to obtain high-purity 1,4-butanediol product.

[0056] The advantages and beneficial effects of this invention are as follows:

[0057] 1. This invention relates to a novel process for producing 1,4-butanediol from maleic anhydride, a high-purity product. Its advantage lies in its ability to flexibly adjust the production volume according to market changes, thereby better meeting market demands. Specifically, this process can produce high-grade tetrahydrofuran as a byproduct while producing high-grade 1,4-butanediol. This process can also reduce the yield of high-grade 1,4-butanediol while producing high-grade tetrahydrofuran and high-grade γ-butanediol as byproducts by adjusting the hydrogenation of γ-butyrolactone and the separation unit of 1,4-butanediol.

[0058] 2. This invention relates to a novel process for producing 1,4-butanediol from maleic anhydride, which has the advantages of yielding superior-grade 1,4-butanediol with a purity ≥99.70 wt% and a water mass fraction ≤0.03 wt%; superior-grade γ-butyrolactone with a purity ≥99.70 wt% and a water mass fraction ≤0.05 wt%; and superior-grade tetrahydrofuran with a purity ≥99.99 wt% and a water mass fraction ≤0.2 ppm.

[0059] The direct hydrogenation process of maleic anhydride has a very broad application prospect, attracting the attention of many investors. Attached Figure Description

[0060] Figure 1 : Schematic diagram of the maleic anhydride hydrogenation reaction unit and product separation unit of the present invention.

[0061] Figure 2 : Schematic diagram of the process flow of the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit of the present invention.

[0062] Among them: R101 - maleic anhydride hydrogenation reactor; R301 - γ-butyrolactone hydrogenation reactor; T201 - tetrahydrofuran removal tower; T202 - tetrahydrofuran crude fractionation tower; T203 - extractive distillation tower; T204 - extractant recovery tower; T205 - first light component removal tower; T206 - γ-butyrolactone refining tower; T207 - 1,4-butanediol refining tower; T301 - second light component removal tower; C101 - hydrogen feed compressor; V101 - first hydrogen separator; V102 - first atmospheric pressure... Tanks: V301 - Second hydrogen separator, V302 - Second atmospheric pressure tank, V303 - Membrane separator; F101 - Hydrogen feed mixer, F102 - First feed mixer, F201 - Ethylene glycol mixer, F202 - Crude 1,4-Butanediol mixer, F301 - Second feed mixer; E101 - Hydrogen feed preheater, E102 - Maleic anhydride feed preheater, E103 - Maleic anhydride hydrogenation reactor outlet heat exchanger, E201 - Circulating extractant heat exchanger, E202 - Heat exchanger for the bottom liquid of the tetrahydrofuran removal tower; E203 - γ-butyrolactone preheater; E204 - 1,4-butanediol refining tower feed heat exchanger; E301 - feed preheater; E302 - γ-butyrolactone hydrogenation reactor outlet heat exchanger; P101 - maleic anhydride feed pump; P102 - tetrahydrofuran removal tower feed pump; P201 - tetrahydrofuran coarse fractionation tower feed pump; P202 - extractant recovery tower feed pump; P203 - tetrahydrofuran product transfer pump; P204 - first low-boiling waste liquid transfer pump. P205 - Extractant circulation pump; P206 - Second low-boiling waste liquid transfer pump; P207 - γ-Butyrolactone refining tower feed pump; P208 - First high-boiling waste liquid transfer pump; P209 - γ-Butyrolactone product transfer pump; P210 - First crude 1,4-butanediol transfer pump; P211 - 1,4-butanediol product transfer pump; P212 - Second high-boiling waste liquid transfer pump; P301 - Second crude 1,4-butanediol transfer pump; P302 - Third high-boiling waste liquid transfer pump; Names and numbers are as follows... Figure 1 and Figure 2 As shown. Detailed Implementation

[0063] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.

[0064] The following specific examples illustrate the implementation process of the method in this application.

[0065] Example:

[0066] like Figure 1 Flow diagrams of the maleic anhydride hydrogenation reaction unit and product separation unit. Figure 2 The schematic diagram of the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit is shown below:

[0067] The feed rate of maleic anhydride is 33339.75 kg / h. Fresh maleic anhydride is pressurized by maleic anhydride feed pump P101 and preheated by maleic anhydride feed preheater E102 before being fed into the first feed mixer F102 to mix with hydrogen. The feed rate of hydrogen is 102810.47 kg / h. Fresh hydrogen is pressurized by hydrogen feed compressor C101 and mixed with circulating hydrogen in hydrogen feed mixer F101. After being heated to the reaction temperature of 200.0 ℃ by hydrogen feed preheater E101, it is mixed with maleic anhydride. The mixed hydrogen and maleic anhydride stream is fed into maleic anhydride hydrogenation reactor R101 for reaction. The inlet temperature of maleic anhydride hydrogenation reactor R101 is 200.0 ℃, the outlet temperature is 215.0 ℃, and the operating pressure is 2.0 MPa.

[0068] The hydrogen stream emanating from the maleic anhydride hydrogenation reactor is cooled by the reactor outlet heat exchanger E103 and then sent to the first hydrogen separator V101 to recover excess hydrogen. The recovered hydrogen is sent to the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit for γ-butyrolactone hydrogenation. The excess hydrogen separated from the hydrogen separator in this unit, containing trace amounts of CO, tetrahydrofuran, water, and other organic matter, is sent to the membrane separation unit V303 for further hydrogen stream separation. The hydrogen stream that permeates through the membrane can be mixed with fresh hydrogen as recirculated hydrogen, while the organic gases that do not permeate through the membrane are incinerated as waste gas. Finally, the high-purity hydrogen after separation is mixed with fresh hydrogen, and the organic components are sent to a flare for incineration as waste gas. The liquid stream from the first hydrogen separator V101 is sent to the first atmospheric pressure tank V102 to be reduced to atmospheric pressure, and then fed into the detetrahydrofuran tower via the detetrahydrofuran tower feed pump P102 for subsequent product separation.

[0069] The product stream from the maleic anhydride hydrogenation unit enters the tetrahydrofuran removal tower T201 for separation. The bottom stream, mainly composed of γ-butyrolactone and 1,4-butanediol, is fed into a subsequent light-removal tower for further separation of γ-butyrolactone and 1,4-butanediol. These are then fed into 1,4-butanediol and γ-butyrolactone refining towers for further separation, yielding high-purity 1,4-butanediol and γ-butyrolactone products, respectively. The top stream, primarily containing tetrahydrofuran, n-butanol, and water, is fed to the tetrahydrofuran roughing tower T202 via the tetrahydrofuran roughing tower feed pump P201 for further separation. The waste stream is sent to a flare for incineration. The top temperature of the tetrahydrofuran removal tower T201 is 76.0 °C, the bottom temperature is 177.8 °C, and the operating pressure is 0.14 MPa.

[0070] The top stream from the tetrahydrofuran crude fractionation column T202 is directly fed into the extractive distillation column T203 to obtain high-purity tetrahydrofuran product, while the waste stream is sent to a flare for incineration. The bottom stream from the tetrahydrofuran crude fractionation column T202 is sent to a waste liquid treatment unit as low-boiling waste liquid. The top temperature of the tetrahydrofuran crude fractionation column T202 is 74.6 ℃, the bottom temperature is 104.1 ℃, and the operating pressure is 0.15 MPa.

[0071] The overhead stream from the tetrahydrofuran (THF) crude fractionator enters the extractive distillation column T203 for separation. Fresh ethylene glycol is mixed with ethylene glycol recycled from the extractant recovery column T204 before entering the extractive distillation column. The THF mass fraction in the overhead stream is ≥99.99%, and the water mass fraction is ≤0.19 ppm. The THF product obtained from the overhead stream is sent to the THF product tank for storage. The main component of the bottom stream is ethylene glycol, with small amounts of n-butanol, propionic acid, and THF. The bottom stream is sent to the extractant recovery column T204 via the extractant recovery column feed pump P202 to recover the extractant ethylene glycol. The recovered ethylene glycol can be mixed with fresh ethylene glycol before entering the extractive distillation column. The overhead temperature of the extractive distillation column T203 is 66.9 ℃, the bottom temperature is 152.0 ℃, and the operating pressure is 0.11 MPa.

[0072] The ethylene glycol recovered from the bottom stream of extractant recovery column T204 has a purity ≥99.99 wt%. The bottom stream is mixed with fresh ethylene glycol after passing through extractant circulation pump P205 and circulating extractant heat exchanger E201, and then fed into the extractive distillation column. The top stream, a small mixture of ethylene glycol, water, and n-butanol, is sent to the wastewater treatment unit as low-boiling waste liquid. The top temperature of extractant recovery column T204 is 39.9 ℃, the bottom temperature is 140.5 ℃, and the operating pressure is 0.01 MPa.

[0073] The bottom stream from the tetrahydrofuran removal tower first recovers heat through the bottom liquid heat exchanger E202, and then is sent to the first light component removal tower T205 for separation. The overhead stream from the first light component removal tower contains a large amount of γ-butyrolactone, a small amount of 1,4-butanediol, and propionic acid, and is sent to the γ-butyrolactone refining tower T206 for separation to obtain high-purity γ-butyrolactone product. The bottom stream contains a small amount of γ-butyrolactone, a large amount of 1,4-butanediol, and heavy components such as tar that may appear in the actual process, and is sent to the 1,4-butanediol refining tower T207 for separation to obtain high-purity 1,4-butanediol product. The top temperature of the first light component removal tower T205 is 98.1 ℃, the bottom temperature is 177.8 ℃, and the operating pressure is 0.01 MPa.

[0074] In the T206 γ-butyrolactone refining column, most of the γ-butyrolactone in the feed stream is collected from the bottom stream, which also contains a small amount of 1,4-butanediol. The overhead stream contains small amounts of γ-butyrolactone, water, and propionic acid, and is sent to the wastewater treatment unit as low-boiling waste liquid. The obtained γ-butyrolactone product can be sent to the γ-butyrolactone product tank, or the generated γ-butyrolactone can be sent to the next system, namely the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit, for further hydrogenation and separation to obtain more 1,4-butanediol product. The top temperature of the γ-butyrolactone refining column T206 is 53.8 ℃, the bottom temperature is 136.5 ℃, and the operating pressure is 0.01 MPa.

[0075] The bottom stream of the first light component removal tower, containing crude 1,4-butanediol product, is mixed with the crude 1,4-butanediol product stream from the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit via the first crude 1,4-butanediol transfer pump P210 in the crude 1,4-butanediol mixer F202. After mixing, the stream is fed into the 1,4-butanediol refining tower T207 via the feed heat exchanger E204 for separation. The overhead stream of the 1,4-butanediol refining tower yields 1,4-butanediol product with a purity ≥99.70 wt%, while the bottom stream, containing heavy components such as tar, is sent as high-boiling waste liquid to the waste liquid treatment unit. The top temperature of the 1,4-butanediol refining tower T207 is 80.2 ℃, the bottom temperature is 170.5 ℃, and the operating pressure is 0.01 MPa. The 1,4-butanediol product stream is sent to the 1,4-butanediol product tank for storage via the 1,4-butanediol product transfer pump P211. The bottom stream of the 1,4-butanediol refining column contains a small amount of 1,4-butanediol and heavy components such as tar that may occur in actual production. After recovering the 1,4-butanediol product in the bottom stream through a falling film evaporator, it is sent to the waste liquid treatment unit as high-boiling waste liquid.

[0076] The γ-butyrolactone product stream from the separation process of γ-butyrolactone and 1,4-butanediol enters the second feed mixer F301 and mixes with the hydrogen stream separated from the maleic anhydride hydrogenation reactor. The mixed feed stream is preheated to the reaction temperature of 180 °C by the feed preheater E301 before entering the γ-butyrolactone hydrogenation reactor R301 for reaction. The inlet temperature of the γ-butyrolactone hydrogenation reactor R301 is 180.0 °C, the outlet temperature is 188.4 °C, and the operating pressure is 2.0 MPa. The product stream is cooled by the outlet heat exchanger E302 of the γ-butyrolactone hydrogenation reactor and then sent to the second hydrogen separator V301 to recover excess hydrogen. The gaseous stream from the second hydrogen separator is returned to the maleic anhydride hydrogenation reactor as recycled hydrogen. After being separated by a membrane separator, the organic waste gas is mixed with fresh hydrogen and then sent to a flare for incineration. The liquid stream is sent to the second atmospheric pressure tank V302 to be reduced to atmospheric pressure, and then sent to the second light-weight removal tower T301 for separation.

[0077] The bottom stream from the second light-weight removal tower is fed into the crude 1,4-butanediol mixer F202 via the second crude 1,4-butanediol transfer pump P301 to mix with the crude 1,4-butanediol stream from the product separation unit. The mixed stream is then fed into the 1,4-butanediol refining tower T207 to obtain high-purity 1,4-butanediol product. The top temperature of the second light-weight removal tower T301 is 27.8 ℃, the bottom temperature is 170.1 ℃, and the operating pressure is 0.01 MPa.

[0078] This implementation case ultimately achieved a novel process for producing 1,4-butanediol from maleic anhydride, a high-purity product:

[0079] 1. This invention relates to a novel process for producing 1,4-butanediol from maleic anhydride, a high-purity product. Its advantage lies in its ability to flexibly adjust the production volume according to market changes, thereby better meeting market demands. Specifically, this process can produce high-grade tetrahydrofuran as a byproduct while producing high-grade 1,4-butanediol; alternatively, by adjusting the hydrogenation of γ-butyrolactone and the separation unit of 1,4-butanediol, the production of high-grade 1,4-butanediol can be reduced while simultaneously producing high-grade tetrahydrofuran and γ-butyrolactone as byproducts.

[0080] 2. This invention relates to a novel process for producing 1,4-butanediol from maleic anhydride, which has the advantages of yielding superior-grade 1,4-butanediol with a purity ≥99.70 wt% and a water mass fraction ≤0.03 wt%; superior-grade γ-butyrolactone with a purity ≥99.70 wt% and a water mass fraction ≤0.05 wt%; and superior-grade tetrahydrofuran with a purity ≥99.99 wt% and a water mass fraction ≤0.2 ppm.

[0081] Although the invention has been described in conjunction with specific embodiments and accompanying drawings, it is not intended to be limited to the specific forms set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, while individual features may be contained in different claims, these features may be advantageously combined, and inclusion in different claims does not imply that such combinations of features are not feasible and / or advantageous. References to "first," "second," etc., do not exclude the plural.

Claims

1. A process for producing 1,4-butanediol from maleic anhydride, characterized in that, The process for producing 1,4-butanediol from maleic anhydride uses maleic anhydride and hydrogen as raw materials, employing a direct hydrogenation method to co-produce 1,4-butanediol and tetrahydrofuran; it can also co-produce 1,4-butanediol, tetrahydrofuran, and γ-butyrolactone. The process includes a maleic anhydride hydrogenation reaction unit, a product separation unit, and γ-butyrolactone hydrogenation and 1,4-butanediol separation units. The maleic anhydride hydrogenation reaction unit is equipped with a maleic anhydride hydrogenation reactor; the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit is equipped with a γ-butyrolactone hydrogenation reactor. Different products can be generated through adjustments to the system's operation.

2. The process for producing 1,4-butanediol from maleic anhydride as described in claim 1, characterized in that, The product separation unit includes the separation processes of tetrahydrofuran and γ-butyrolactone and 1,4-butanediol. Tetrahydrofuran and water are separated using a combination of a tetrahydrofuran crude fractionation column, an extractive distillation column, and an extractant recovery column to obtain high-purity tetrahydrofuran. The azeotrope of tetrahydrofuran and water is successively passed through the tetrahydrofuran crude fractionation column, the extractive distillation column, and the extractant recovery column, using ethylene glycol as the extractant. A membrane separation device is used to separate and purify the hydrogen streams separated from the γ-butyrolactone hydrogenation and 1,4-butanediol separation units to obtain high-purity hydrogen, which is used as circulating hydrogen and recycled back to the maleic anhydride hydrogenation reaction unit feed.

3. An apparatus for producing 1,4-butanediol from maleic anhydride according to claim 1, characterized in that, The maleic anhydride hydrogenation reaction unit includes a hydrogen feed compressor C101, a maleic anhydride hydrogenation reactor R101, a first hydrogen separator V101, a first atmospheric pressure tank V102, a hydrogen feed preheater E101, a maleic anhydride feed preheater E102, a maleic anhydride hydrogenation reactor outlet heat exchanger E103, a maleic anhydride feed pump P101, a tetrahydrofuran removal tower feed pump P102, a hydrogen feed mixer F101, and a first raw material mixer F102; the product separation unit includes a tetrahydrofuran removal tower T201. The following are listed: Tetrahydrofuran crude fractionation column T202, extractive distillation column T203, extractant recovery column T204, first light component removal column T205, γ-butyrolactone refining column T206, 1,4-butanediol refining column T207, circulating extractant heat exchanger E201, tetrahydrofuran removal column bottom liquid heat exchanger E202, γ-butyrolactone preheater E203, 1,4-butanediol refining column feed heat exchanger E204, tetrahydrofuran crude fractionation column feed pump P201, and extractant recovery column feed pump P202. Tetrahydrofuran product transfer pump P203, first low-boiling waste liquid transfer pump P204, extractant circulation pump P205, second low-boiling waste liquid transfer pump P206, γ-butyrolactone refining tower feed pump P207, first high-boiling waste liquid transfer pump P208, γ-butyrolactone product transfer pump P209, crude 1,4-butanediol first transfer pump P210, 1,4-butanediol product transfer pump P211, second high-boiling waste liquid transfer pump P212, ethylene glycol mixer F201, crude 1,4- The butanediol mixer F202; the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit includes a γ-butyrolactone hydrogenation reactor R301, a second light-removal tower T301, a second hydrogen separator V301, a second atmospheric pressure tank V302, a membrane separation device V303, a feed preheater E301, a γ-butyrolactone hydrogenation reactor outlet heat exchanger E302, a crude 1,4-butanediol second transfer pump P301, a third high-boiling waste liquid transfer pump P302, and a second raw material mixer F301.

4. The apparatus for producing 1,4-butanediol from maleic anhydride as described in claim 3, characterized in that, In the maleic anhydride hydrogenation reactor unit, the inlet of the hydrogen feed compressor C101 is connected to the hydrogen feed pipeline, and the outlet is connected to the inlet of the hydrogen feed mixer F101; the outlet of the hydrogen feed mixer F101 is connected to the inlet of the hydrogen feed preheater E101; the inlet of the maleic anhydride feed pump P101 is connected to the maleic anhydride feed pipeline, and the outlet is connected to the inlet of the maleic anhydride feed preheater E102; the inlet of the first raw material mixer F102 is connected to both the outlet of the hydrogen feed preheater E101 and the outlet of the maleic anhydride feed preheater E102, and the outlet is connected to the inlet of the maleic anhydride hydrogenation reactor R101; the maleic anhydride... The outlet of hydrogen reactor R101 is connected to the inlet of heat exchanger E103 at the outlet of maleic anhydride hydrogenation reactor; the outlet of heat exchanger E103 at the outlet of maleic anhydride hydrogenation reactor is connected to the inlet of first hydrogen separator V101; the top outlet of first hydrogen separator V101 is connected to the inlet of second raw material mixer F301, and the bottom outlet is connected to the inlet of first atmospheric pressure tank V102; the top outlet of first atmospheric pressure tank V102 is connected to a flare, and the bottom outlet is connected to the inlet of feed pump P102 for detetrahydrofuran tower; the outlet of feed pump P102 for detetrahydrofuran tower is connected to the inlet of T201 for detetrahydrofuran tower.

5. The apparatus for producing 1,4-butanediol from maleic anhydride as described in claim 3, characterized in that, In the product separation unit, the top outlet of the tetrahydrofuran de-tetrahydrofuran tower T201 is connected to the flare and the inlet of the tetrahydrofuran crude fractionation tower feed pump P201, and the bottom outlet of the tower is connected to the inlet of the tetrahydrofuran de-tetrahydrofuran tower bottom liquid heat exchanger E202; the outlet of the tetrahydrofuran crude fractionation tower feed pump P201 is connected to the inlet of the tetrahydrofuran crude fractionation tower T202; the top outlet of the tetrahydrofuran crude fractionation tower T202 is connected to the flare and the inlet of the extractive distillation tower T203, and the bottom outlet of the tower is connected to the inlet of the second low-boiling waste liquid transfer pump P206; the outlet of the second low-boiling waste liquid transfer pump P206 is connected to the waste liquid treatment device; the top outlet of the extractive distillation tower T203 is connected to the flare and the inlet of the tetrahydrofuran product transfer pump P203; the outlet of the tetrahydrofuran product transfer pump P203 is connected to the tetrahydrofuran product tank. Connections: The outlet of the bottom of the extractive distillation column T203 is connected to the inlet of the feed pump P202 of the extractant recovery column; the outlet of the feed pump P202 of the extractant recovery column is connected to the inlet of the extractant recovery column T204; the top outlet of the extractant recovery column T204 is connected to the inlet of the first low-boiling waste liquid transfer pump P204; the outlet of the first low-boiling waste liquid transfer pump P204 is connected to the waste liquid treatment device; the outlet of the bottom of the extractant recovery column T204 is connected to the inlet of the extractant circulation pump P205; the outlet of the extractant circulation pump P205 is connected to the inlet of the circulating extractant heat exchanger E201; the inlet of the ethylene glycol mixer F201 is connected to the outlet of the circulating extractant heat exchanger E201 and the ethylene glycol feed pipeline; the outlet is connected to the inlet of the extractive distillation column T203; the first light-removing... The inlet of column T205 is connected to the outlet of the bottom liquid heat exchanger E202 of the tetrahydrofuran removal column; the top outlet of the column is connected to the inlet of the feed pump P207 of the γ-butyrolactone refining column; and the bottom outlet of the column is connected to the inlet of the first crude 1,4-butanediol transfer pump P210. The inlet of column T206 of the γ-butyrolactone refining column is connected to the outlet of the feed pump P207 of the γ-butyrolactone refining column; the top outlet of the column is connected to the inlet of the first high-boiling waste liquid transfer pump P208; and the bottom outlet of the column is connected to the inlet of the γ-butyrolactone preheater E203. The outlet of the first high-boiling waste liquid transfer pump P208 is connected to the waste liquid treatment device; the outlet of the γ-butyrolactone preheater E203 is connected to the inlet of the γ-butyrolactone product transfer pump P209; and the outlet of the γ-butyrolactone product transfer pump P209 is connected to the second raw material mixer. The F301 inlet is connected; the F202 inlet of the crude 1,4-butanediol mixer is connected to the outlet of the first crude 1,4-butanediol transfer pump P210 and the outlet of the second crude 1,4-butanediol transfer pump P301, and the outlet is connected to the inlet of the feed heat exchanger E204 of the 1,4-butanediol refining tower; the T207 inlet of the 1,4-butanediol refining tower is connected to the outlet of the feed heat exchanger E204 of the 1,4-butanediol refining tower, the top outlet of the tower is connected to the inlet of the 1,4-butanediol product transfer pump P211, and the bottom outlet of the tower is connected to the inlet of the second high-boiling waste liquid transfer pump P212; the outlet of the 1,4-butanediol product transfer pump P211 is connected to the 1,4-butanediol product tank, and the outlet of the second high-boiling waste liquid transfer pump P212 is connected to the waste liquid treatment device.

6. The apparatus for producing 1,4-butanediol from maleic anhydride as described in claim 3, characterized in that, In the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit, the outlet of the second feed mixer F301 is connected to the inlet of the feed preheater E301; the inlet of the γ-butyrolactone hydrogenation reactor R301 is connected to the outlet of the feed preheater E301, and the outlet is connected to the inlet of the γ-butyrolactone hydrogenation reactor outlet heat exchanger E302; the inlet of the second hydrogen separator V301 is connected to the outlet of the γ-butyrolactone hydrogenation reactor outlet heat exchanger E302, the top outlet of the separator is connected to the inlet of the membrane separation unit V303, and the bottom outlet is connected to... The inlet of the second atmospheric pressure tank V302 is connected; the outlet of the membrane separation unit V303 is connected to the flare and the inlet of the hydrogen feed mixer F101; the top outlet of the second atmospheric pressure tank V302 is connected to the flare, and the bottom outlet is connected to the inlet of the second light-duty removal tower T301; the top outlet of the second light-duty removal tower T301 is connected to the flare and the inlet of the third high-boiling waste liquid transfer pump P302, and the bottom outlet is connected to the inlet of the second crude 1,4-butanediol transfer pump P301; the outlet of the third high-boiling waste liquid transfer pump P302 is connected to the waste liquid treatment device.

7. The apparatus for producing 1,4-butanediol from maleic anhydride as described in claim 5, characterized in that, Fresh hydrogen is pressurized by the hydrogen feed compressor C101 and mixed with recycled hydrogen in the hydrogen feed mixer F101. After being heated by the hydrogen feed preheater E101, it is mixed with maleic anhydride. The maleic anhydride is pressurized by the maleic anhydride feed pump P101 and preheated by the maleic anhydride feed preheater E102 before being sent to the first raw material mixer F102 to mix with hydrogen. The mixed hydrogen and maleic anhydride stream is then sent to the maleic anhydride hydrogenation reactor R101 for reaction. The components from γ-butyrolactone and 1,4-butanediol... The γ-butyrolactone product stream from the γ-butyrolactone product transfer pump P209 enters the second raw material mixer F301 and mixes with the hydrogen stream separated from the top of the first hydrogen separator V101 from the maleic anhydride hydrogenation reaction system. After being preheated to the reaction temperature by the feed preheater E301, the mixed raw material stream enters the γ-butyrolactone hydrogenation reactor R301 for reaction. When the market demand for 1,4-butanediol is high, the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit is activated.

8. The apparatus for producing 1,4-butanediol from maleic anhydride as described in claim 6, characterized in that, The effluent stream from the top of the tetrahydrofuran removal column T201 is fed into the tetrahydrofuran roughing column T202 via the tetrahydrofuran roughing column feed pump P201. The effluent stream from the top of the tetrahydrofuran roughing column T202 is directly fed into the extractive distillation column T203. Fresh ethylene glycol is mixed with ethylene glycol recycled from the extractant recovery column T204 and then enters the extractive distillation column T203. The mass fraction of tetrahydrofuran in the effluent stream from the extractive distillation column T203 is ≥99.99%, and the mass fraction of water is ≤0.19%. ppm; The bottom stream of extractive distillation column T203 is fed into extractant recovery column T204 via extractant recovery column feed pump P202; Ethylene glycol recovered from the bottom stream of extractant recovery column T204 is mixed with fresh ethylene glycol after passing through extractant circulation pump P205 and circulating extractant heat exchanger E201, and then fed into extractive distillation column T203; The top stream of extractant recovery column T204 is sent to the waste liquid treatment device as low-boiling waste liquid.

9. The apparatus for producing 1,4-butanediol from maleic anhydride as described in claim 7, characterized in that, The gas stream from the second hydrogen separator V301 in the γ-butyrolactone hydrogenation and 1,4-butanediol separation unit is sent back to the maleic anhydride hydrogenation reaction system as circulating hydrogen. After the organic waste gas is separated by the membrane separator V303, it is mixed with fresh hydrogen and then sent to the flare for incineration.

10. The process for producing 1,4-butanediol from maleic anhydride as described in claim 1, characterized in that, A direct hydrogenation process of maleic anhydride can be used to produce high-quality 1,4-butanediol while simultaneously producing high-quality tetrahydrofuran; or by adjusting the hydrogenation of γ-butyrolactone and the separation unit of 1,4-butanediol, the yield of high-quality 1,4-butanediol can be reduced while simultaneously producing high-quality tetrahydrofuran and high-quality γ-butyrolactone.

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