A method for co-producing 1,4-butanediol and alkyl-1,4-butanediol

Abstract

The present invention discloses a method for the co-production of 1,4-butanediol and alkyl-1,4-butanediol, which creatively enables the production of two products, BDO and BDO containing alkyl-1,4-butanediol, in an acetylene-aldehyde process BDO device. That is, BDO and a BDO product containing 0-25% by weight of alkyl-1,4-butanediol can be efficiently produced in the same device, achieving product differentiation in a single device and having high economic value.

Description

Technical Field

[0001] The present invention belongs to the field of fine chemicals, and specifically relates to a method for co-producing 1,4-butanediol (BDO) and alkyl-1,4-butanediol. Background Art

[0002] The current production process for BDO plants using the acetylene-formaldehyde process is as follows: Formaldehyde reacts with excess acetylene to produce 1,4-butynediol (BYD). The excess acetylene is separated and recycled back to the BYD synthesis reactor for further reaction. The resulting BYD is concentrated, stripped of formaldehyde and methanol, and then enters a hydrogenation reactor to react with hydrogen to produce crude BDO. The crude BDO is then distilled and separated to produce the BDO product. However, the BDO industry is currently experiencing severe oversupply, with most companies operating below the break-even point.

[0003] Alkyl-1,4-butanediol, as a modified BDO product, offers superior performance. However, industrial production has yet to be achieved, remaining at the laboratory research stage. Patent document US4590312A discloses the synthesis of methyl-1,4-butanediol (MBDO) using BYD and formaldehyde, but this process is a batch reaction, precluding large-scale production and incompatible with existing acetaldehyde process technology. Patent document CN1037701A discloses a method for preparing a butanol mixture using BYD, 4-hydroxybutyraldehyde / cyclic hemiacetal, hydrogen, and formaldehyde over a Raney nickel catalyst to produce 2-MBDO. However, this technology is difficult to obtain due to the limited availability of the 4-hydroxybutyraldehyde / cyclic hemiacetal raw materials, making large-scale production unfeasible. Patent document CN 219232322 U discloses a two-stage hydrogenation unit using a stirred tank in series with a fixed bed to suppress the byproduct MBDO in BDO units. The conventional two-stage hydrogenation reactor described is a trickle bed, characterized by slow bed flow rates and locally high temperatures that affect catalyst life. In addition, the current patent literature reports that the maximum amount of BDO products produced contains 16 wt% MBDO, and fails to produce BDO products with higher MBDO concentrations.

[0004] Therefore, there is an urgent need for a method to synthesize BDO efficiently and at low cost, which can realize the co-production of high-concentration MBDO by the acetylene-aldehyde process. Summary of the Invention

[0005] In order to improve the above technical problems, the present invention provides a method for co-producing 1,4-butanediol and alkyl-1,4-butanediol, comprising the following steps:

[0006] (1) Formaldehyde reacts with acetylene to produce 1,4-butynediol stream;

[0007] (2) The 1,4-butynediol stream undergoes a two-stage hydrogenation reaction to co-produce 1,4-butanediol and alkyl-1,4-butanediol;

[0008] (2-1) When the target product is only 1,4-butanediol, it is necessary to recover the unreacted formaldehyde in step (1);

[0009] (2-2) When the target product is 1,4-butanediol containing alkyl-1,4-butanediol, it is not necessary to recover the unreacted formaldehyde in step (1), to supplement the aldehyde to the initial raw material in step (1), the 1,4-butynediol stream in step (1) and / or the hydrogenation reaction process, and to add a co-catalyst to the hydrogenation reaction process.

[0010] According to an embodiment of the present invention, the alkyl-1,4-butanediol is an alkyl-substituted 1,4-butanediol, for example, C 1~20 Alkyl, C 1~10 Alkyl or C 1~4 Alkyl (methyl, ethyl, propyl, isopropyl, butyl, isobutyl) substituted 1,4-butanediol.

[0011] According to an embodiment of the present invention, in step (1), the feed ratio of formaldehyde to acetylene is not particularly limited, and it is best to convert acetylene as completely as possible, for example, the acetylene conversion rate is not less than 95%, preferably not less than 98%.

[0012] In some embodiments, in step (1), the mass ratio of the formaldehyde flow to the acetylene flow is (2-10):1, for example (3-8):1, exemplified by 4:1, 5:1, 6:1, 6.5:1, and 7:1.

[0013] In some embodiments, the flow rate of the formaldehyde logistics in step (1) is 5000-7000 kg / h, for example, 5500-6500 kg / h, exemplified by 6000 kg / h and 6500 kg / h.

[0014] In some embodiments, the flow rate of the acetylene logistics in step (1) is 500-1500 kg / h, such as 800-1200 kg / h, and exemplarily 1000 kg / h.

[0015] According to an embodiment of the present invention, the reaction conditions of formaldehyde and acetylene include:

[0016] The operating pressure is 0~0.3MPaG, for example 0.05~0.2MPaG;

[0017] The reaction temperature is 80-100°C, for example 85-95°C;

[0018] And / or, the catalyst is a Cu-Bi complex catalyst.

[0019] According to an embodiment of the present invention, the conditions of the first stage hydrogenation reaction include:

[0020] The operating pressure is 3~30MPaG, for example 6~20MPaG;

[0021] The reaction temperature is 60-180°C, for example, 100-160°C or 100-180°C;

[0022] The catalyst is a nickel-based catalyst;

[0023] And / or, the molar ratio of the inlet hydrogen to the 1,4-butynediol is 1-20, such as 2-16, exemplified by 2, 5, 8, 10, 13, and 15.

[0024] According to an embodiment of the present invention, the conditions for the second stage hydrogenation reaction include:

[0025] Operating pressure 10~30MPaG, such as 20~30MPaG or 24~34MPaG;

[0026] The reaction temperature is 100-180°C, for example, 100-160°C or 120-180°C;

[0027] The catalyst is a nickel-based catalyst;

[0028] And / or, the molar ratio of the inlet hydrogen to the 1,4-butynediol is 1-20, such as 2-16, exemplified by 2, 5, 8, 10, 13, and 15.

[0029] According to an embodiment of the present invention, the nickel-based catalyst includes, but is not limited to, one or more of Raney nickel, supported nickel, and precipitated nickel.

[0030] According to an embodiment of the present invention, the two-stage hydrogenation reaction is carried out in a bubbling bed hydrogenation reactor.

[0031] According to an embodiment of the present invention, the operation of recovering the unreacted formaldehyde in step (1) comprises:

[0032] The operating pressure is 20~100KPaA, for example, 30~80KPaA;

[0033] Reflux ratio 0.2~2, for example 0.5~1;

[0034] And / or, the number of theoretical plates is 5 to 60, such as 10 to 50, exemplified by 20, 30, 40 or 45.

[0035] According to an embodiment of the present invention, the aldehyde supplementation to the hydrogenation reaction process may be supplemented to the first hydrogenation reaction process, for example, by adding the aldehyde from the top, upper portion, middle portion, and / or bottom portion of the first hydrogenation reactor. The tower body of the first hydrogenation reactor is divided into three equal parts: the portion away from the ground is designated as the upper portion, the portion close to the ground is designated as the lower portion, and the portion between the upper and lower portions is designated as the middle portion.

[0036] According to an embodiment of the present invention, the supplementary aldehyde in step (2-2) is the aldehyde required to generate the alkyl-1,4-butanediol, for example, C 1~20 Aldehyde, C 1~10 Aldehyde or C 1~4 Aldehydes are exemplified by formaldehyde, acetaldehyde, propionaldehyde, isopropionaldehyde, butyraldehyde, and isobutyraldehyde.

[0037] According to an embodiment of the present invention, in step (2), the mass ratio of the aldehyde supplemented in any process to the formaldehyde logistics of step (1) is 1:(1-50), for example, 1:(5-40), and exemplified by 1:6, 1:8, 1:8.5, 1:9, 1:10, 1:15, 1:20, 1:25, 1:30, 1:31, 1:32, and 1:35.

[0038] In some embodiments, the flow rate of aldehyde supplemented in any of the steps is 100-1000 kg / h, such as 200-800 kg / h, exemplified by 400 kg / h, 500 kg / h, 600 kg / h, and 700 kg / h.

[0039] According to an embodiment of the present invention, the co-catalyst is selected from an organic base and / or an inorganic base, for example, selected from n-butylamine, trimethylamine, ethylene glycolamine, ammonia water, and one or more oxides or hydroxides of lithium, sodium, potassium, magnesium, and calcium; for example, the co-catalyst is sodium hydroxide and / or potassium hydroxide.

[0040] According to an embodiment of the present invention, the amount of the co-catalyst added is required to control the pH value of the discharge from the second stage hydrogenation reaction to be between 7 and 14, for example, between 8 and 12.

[0041] According to an embodiment of the present invention, the co-catalyst is added in the form of an aqueous solution, for example, the concentration of the co-catalyst aqueous solution is 10-40 wt% (for example, 15-30 wt%), and the amount added does not exceed 1 wt% of the mass of the formaldehyde flow in step (1).

[0042] According to an embodiment of the present invention, the co-catalyst is added to the first stage hydrogenation reaction process or the second stage hydrogenation reaction process.

[0043] According to some embodiments of the present invention, in step (2-2), aldehyde is added to the initial raw material of step (1), the 1,4-butynediol logistics of step (1), the top, upper part, middle part or bottom part of the first hydrogenation reactor, and a promoter is added to the first hydrogenation reaction process.

[0044] According to some embodiments of the present invention, in step (2-2), aldehyde is added to the initial raw material of step (1), the 1,4-butynediol logistics of step (1), the top, upper part, middle part or bottom part of the first hydrogenation reactor, and a promoter is added to the second hydrogenation reaction process.

[0045] According to an embodiment of the present invention, the method further comprises step (3) a distillation process: removing heavy substances, recovering methanol and removing light substances from the discharge of the second stage hydrogenation reaction.

[0046] According to an embodiment of the present invention, the weight removal comprises the following operations:

[0047] Operating pressure 0~20KPaA, for example 3~8KPaA;

[0048] The number of theoretical plates is 5 to 30, for example, 10 to 20;

[0049] And / or, the reflux ratio is 0.2-5, for example 0.5-2.

[0050] According to an embodiment of the present invention, the recovery of methanol comprises the following operations:

[0051] Operating pressure 0~20KPaA, for example 5~10KPaA;

[0052] The number of theoretical plates is 10 to 50, for example, 20 to 40;

[0053] and / or, a reflux ratio of 1 to 5, for example, 1 to 3.

[0054] According to an embodiment of the present invention, the light removal comprises the following operations:

[0055] Operating pressure 0~20KPaA, for example 5~10KPaA;

[0056] The number of theoretical plates is 10 to 50, for example, 20 to 40;

[0057] and / or, a reflux ratio of 1 to 10, for example, 2 to 5.

[0058] According to an embodiment of the present invention, the method can be carried out in the following system, which comprises:

[0059] 1,4-Butynediol synthesis reactor;

[0060] a formaldehyde circulation tower located downstream of the 1,4-butynediol synthesis reactor;

[0061] A first hydrogenation reactor and a second hydrogenation reactor are located downstream of the formaldehyde circulation tower, the first hydrogenation reactor and the second hydrogenation reactor are connected in series, the first hydrogenation reactor and the second hydrogenation reactor are bubbling bed hydrogenation reactors, both of which are provided with a nickel-based catalyst layer, and the first hydrogenation reactor and / or the second hydrogenation reactor are further provided with a co-catalyst feed end;

[0062] an aldehyde feeding end, the aldehyde feeding end being used to provide more aldehyde to the 1,4-butynediol synthesis reactor and / or the first hydrogenation reactor; the aldehyde feeding end being arranged at the feed inlet of the 1,4-butynediol synthesis reactor and / or at the top, upper part, middle part and / or bottom part of the first hydrogenation reactor; preferably being arranged in the middle part of the first hydrogenation reactor;

[0063] and a distillation unit located downstream of the hydrogenation reactor, wherein the distillation unit comprises a de-heavy tower, a methanol recovery tower located downstream of the de-heavy tower, and a light tower located downstream of the methanol recovery tower.

[0064] Beneficial effects

[0065] The co-production method provided by the present invention achieves efficient production of BDO and a BDO product containing 0-25% wt alkyl-1,4-butanediol in the same device, achieving product differentiation in a single device and having high economic value.

[0066] (1) The acetylene-aldehyde method BDO unit was creatively used to produce two products: BDO and BDO containing alkyl-1,4-butanediol, which improved the efficiency of the unit.

[0067] (2) According to the needs of enterprises and the market, the content of alkyl-1,4-butanediol can be adjusted between 0 and 25 wt%, and even up to 30 wt%, which improves the operational flexibility of the device.

[0068] (3) By adjusting the ratio of formaldehyde and acetylene in the raw materials, the emission of acetylene tail gas is reduced, and the secondary recovery of acetylene and formaldehyde is avoided in the production process of alkyl-1,4-butanediol, which reduces the production energy consumption of the device and reduces the production cost.

[0069] (4) The two-stage bubbling bed hydrogenation process can increase the production capacity of the device and extend the service life of the catalyst.

[0070] (5) By changing the material ratio and the feeding process, BED is generated in the first hydrogenation reaction process, and BED reacts with aldehyde in the second hydrogenation reaction process, thereby generating 30 wt% of alkyl-1,4-butanediol product. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is a schematic diagram of the process flow for the co-production of 1,4-butanediol and methyl-1,4-butanediol;

[0072] The reference numerals are as follows:

[0073] R1-BYD synthesis reactor; T1-formaldehyde circulation tower; R2-first hydrogenation reactor; R2-first hydrogenation reactor; R3-first hydrogenation reactor; C1-heavy removal tower; C2-methanol recovery ring tower; C3-light removal tower;

[0074] Logistics code: 1-Formaldehyde from the methanol oxidation unit; 2-Acetylene; 3-Formaldehyde pipeline; 4-Acetylation reactor tail gas; 5-R1 discharge; 6-9-Formaldehyde; 10-Cocatalyst; 11-Hydrogen; 12-R2 discharge; 13-R3 feed; 14-R3 discharge; 15-Heavy components; 16-Methanol, returned to the methanol oxidation to formaldehyde unit; 17-Aqueous solution of fusel alcohols (propanol, butanol); 18-BDO product or BDO product containing MBDO. DETAILED DESCRIPTION

[0075] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0076] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0077] Figure 1 The process flow chart of the method of the present invention is as follows:

[0078] 1,4-Butynediol synthesis reactor R1;

[0079] Formaldehyde circulation tower T1 located downstream of the 1,4-butynediol synthesis reactor;

[0080] A first hydrogenation reactor R2 and a second hydrogenation reactor R3 are located downstream of the formaldehyde circulation tower T1. The first hydrogenation reactor R2 and the second hydrogenation reactor R3 are connected in series. The first hydrogenation reactor R2 and the second hydrogenation reactor R3 are bubbling bed hydrogenation reactors, each of which is provided with a nickel-based catalyst layer. The first hydrogenation reactor R2 and / or the second hydrogenation reactor R3 is also provided with a co-catalyst feeding end F;

[0081] One or more (for example, two, three, four or five) aldehyde feeding ends, the aldehyde feeding ends being used to provide more aldehyde to the 1,4-butenediol synthesis reactor and / or the first hydrogenation reactor;

[0082] and a distillation unit located downstream of the hydrogenation reactor, the distillation unit comprising: a deheaving tower C1, a methanol recovery tower C2 located downstream of the deheaving tower C1, and a lightness removal tower C3 located downstream of the methanol recovery tower C2.

[0083] The 1,4-butynediol synthesis reactor R1 is provided with a feed inlet (e.g., a formaldehyde feed inlet, an acetylene feed inlet), a discharge inlet, a formaldehyde circulation inlet, and an exhaust gas outlet;

[0084] The formaldehyde circulation tower T1 is provided with a feed inlet and a discharge port, the first hydrogenation reactor R2 is provided with a feed inlet and a discharge port, and the second hydrogenation reactor R3 is provided with a feed inlet and a discharge port;

[0085] When only 1,4-butanediol is produced, the discharge port of the 1,4-butynediol synthesis reactor R1 is connected to the feed port of the formaldehyde circulation tower T1, and the discharge port of the formaldehyde circulation tower T1 is connected to the feed port or formaldehyde circulation inlet of the 1,4-butynediol synthesis reactor R1.

[0086] When alkyl-1,4-butanediol is also produced, the valve on the connecting pipeline between the discharge port of the 1,4-butynediol synthesis reactor R1 and the feed port of the formaldehyde circulation tower T1 is closed, and the discharge port of the 1,4-butynediol synthesis reactor R1 is connected to the feed port of the first hydrogenation reactor;

[0087] The discharge port of the first hydrogenation reactor R2 is connected to the feed port of the second hydrogenation reactor R3, and the discharge port of the second hydrogenation reactor R3 is connected to the distillation unit;

[0088] The feed inlet of the first hydrogenation reactor R2 includes a feed inlet for the reaction product of the 1,4-butynediol synthesis reactor and a hydrogen feed inlet.

[0089] The feed inlet of the second hydrogenation reactor R3 includes a feed inlet for the product of the first hydrogenation reactor and a hydrogen feed inlet.

[0090] The heavy removal tower C1, methanol recovery tower C2 and light removal tower C3 are plate-type distillation towers.

[0091] The heavy removal tower C1, methanol recovery tower C2 and light removal tower C3 are all equipped with feed inlets, gas phase discharge ports and liquid phase discharge ports;

[0092] The discharge port of the second hydrogenation reactor R3 is connected to the feed port of the de-weighting column C1, the gas phase discharge port of the de-weighting column C1 is connected to the feed port of the methanol recovery column C2, and the liquid phase discharge port of the methanol recovery column C2 is connected to the feed port of the lightness removal column C3;

[0093] The heavy components are taken out from the liquid phase outlet of the deweighting tower C1;

[0094] The methanol is extracted from the gas phase outlet of the methanol recovery tower C2 and connected to the methanol oxidation to formaldehyde device;

[0095] The liquid phase outlet of the light-removing tower C3 produces 1,4-butanediol and alkyl-1,4-butanediol, and the gas phase outlet of the light-removing tower C3 produces other alcohols except methanol.

[0096] The excess hydrogen in the hydrogenation reactor is separated into gas and liquid in a known manner and then circulated back to the feed ports of the first hydrogenation reactor R2 and the second hydrogenation reactor R3 through a compressor (not shown in the figure).

[0097] Examples 1-3

[0098] Use as Figure 1 In the system shown, formaldehyde 1 from a methanol oxidation unit reacts with acetylene 2 in a 1,4-butynediol synthesis reactor R1 to convert the acetylene as much as possible. The discharge 5 from the 1,4-butynediol synthesis reactor R1 is recovered through a formaldehyde circulation tower T1 and returned to the 1,4-butynediol synthesis reactor R1 for further reaction. The tail gas 4 from the R1 reactor is discharged. The formaldehyde-free stream from the bottom of the formaldehyde circulation tower T1, i.e., feed R2, is reacted with hydrogen 11 in a first hydrogenation reactor R2. The R2 discharge reacts with hydrogen 11 in a second hydrogenation reactor R3. The R3 discharge first passes through a deheaving tower C1 to remove salts and heavy components 15, then passes through a methanol recovery tower C2 to recover methanol 16. The stream from the bottom of the methanol recovery tower C2 enters a lightness removal tower C3 to separate an aqueous solution 17 of impure alcohols (propanol and butanol), and the BDO product is obtained in the bottom of the lightness removal tower C3.

[0099] The specific parameters are shown in Table 1. In addition, the R2 / R3 liquid phase space velocity is 0.3h -1 The molar ratio of hydrogen to BYD in R2 / R3 is 13 (the molar ratio of hydrogen to BYD refers to the molar ratio of hydrogen to BYD at the inlet of reactor R2 / R3). The results show that the acetylene conversion rate can be improved by increasing the formaldehyde feed rate.

[0100] Table 1

[0101]

[0102] Examples 4 to 7

[0103] Formaldehyde 1 from the methanol oxidation unit reacts with acetylene 2 in the 1,4-butynediol synthesis reactor R1. The discharge 5 from the 1,4-butenediol synthesis reactor R1 is fed directly into the first hydrogenation reactor R2. Fresh formaldehyde is added to the 1,4-butenediol synthesis reactor R1 or the first hydrogenation reactor R2 through the aldehyde feed port to adjust the material ratio and increase the MBDO content. R1 output 5 and hydrogen 11 enter the first hydrogenation reactor R2 for a hydrogenation reaction under the action of a catalyst and a co-catalyst 10. The resulting R2 output 12 and hydrogen 11 enter the second hydrogenation reactor R3 for a hydrogenation reaction. 1,4-Butynediol (BYD), formaldehyde, and hydrogen are converted into R3 output 14 under the combined action of a nickel-based catalyst and a co-catalyst. This output 14 comprises 1,4-butanediol (BDO), methyl-1,4-butanediol (MBDO), methanol, impurity alcohols (such as butanol and propanol), and heavy components. R3 output 14 first passes through a de-weighting tower C1 to remove salts and heavy components 15. It then passes through a methanol recovery tower C2 to recover methanol 16. The methanol recovered at the top of the tower is directly sent to a methanol oxidation unit for conversion into formaldehyde before re-entering the system. The bottom stream of the methanol recovery tower C2 enters the light alcohol removal tower C3 to separate the aqueous solution 17 of fusel alcohols (propanol and butanol), and a BDO product 18 containing MBDO is obtained in the bottom stream of the light alcohol removal tower C3.

[0104] Aldehyde feeding end: formaldehyde is added to the formaldehyde in logistics 1 from the methanol oxidation unit, and formaldehyde logistics 7 is added to the upper part of the first hydrogenation reactor R2 through the formaldehyde pipeline 3, formaldehyde logistics 8 is added to the middle part of the first hydrogenation reactor R2, or formaldehyde logistics 9 is added to the bottom of the first hydrogenation reactor R2.

[0105] The specific parameters are shown in Table 2 below. In addition, the R2 / R3 liquid phase space velocity is 0.3h -1 The hydrogen to BYD molar ratio at R2 / R3 was 13 (the hydrogen to BYD molar ratio refers to the hydrogen to BYD molar ratio at the R2 / R3 inlet). The reaction conditions for R1, R2, and R3 were the same as in Examples 1-3. The co-catalyst, 25% sodium hydroxide, was added at a rate of 30 kg / h. The results showed that adding formaldehyde at positions 1, 7, 8, and 9 produced different effects, with a maximum MBDO content of 25%.

[0106] Example 8

[0107] Other conditions were the same as in Example 4, except that the cocatalyst was fed to R3 instead of R2, and the aldehyde feed was a formaldehyde stream 6 from the top of the first hydrogenation reactor R2. The hydrogen to BYD molar ratio in R2 was 2, and in R3 was 13. Results showed that up to 30 wt% MBDO could be achieved.

[0108] Table 2

[0109]

[0110] The present invention surprisingly discovered that 1,4-butynediol can be hydrogenated to 1,4-butenediol (BED), and that BED and formaldehyde more readily form MBDO under a hydrogen atmosphere. By controlling the ratio of hydrogen to BYD in reactor R2, the BED content in the R2 output can be regulated. Through a newly added process, formaldehyde is added via stream 6 to reactor R3, and a co-catalyst enters R3 via stream 10. This allows BED to be synthesized in R2, and a hydrogenation reaction of BED, formaldehyde, and hydrogen occurs in R3, producing a BDO product with a 30% wt. MBDO content.

[0111] To produce 2-ethyl-1,4-butanediol, the formaldehyde in streams 6-9 needs to be replaced with an equal molar amount of acetaldehyde. Similarly, to produce 2-propyl-1,4-butanediol in a known manner, the formaldehyde in streams 6-9 needs to be replaced with propionaldehyde. This patent is also applicable to the production of all alkyl-substituted alkyl-1,4-butanediols, such as butyl, isopropyl, and isobutyl, by simply replacing the formaldehyde in the hydrogenation reactor feed with the corresponding alkyl aldehyde.

[0112] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for co-producing 1,4-butanediol and methyl-1,4-butanediol, characterized in that: The method comprises the following steps: (1) Formaldehyde and acetylene react in a 1,4-butynediol synthesis reactor to generate a 1,4-butynediol stream; (2) The 1,4-butynediol stream undergoes a two-stage hydrogenation reaction to co-produce 1,4-butanediol and methyl-1,4-butanediol; Without recovering the unreacted formaldehyde in step (1), the valve on the connecting pipeline between the discharge port of the 1,4-butynediol synthesis reactor and the feed port of the formaldehyde circulation tower is closed, and the discharge port of the 1,4-butynediol synthesis reactor is connected to the feed port of the first hydrogenation reactor; formaldehyde is added to the middle part of the first hydrogenation reactor, and a co-catalyst is added to the first hydrogenation reaction process; The mass ratio of the supplementary formaldehyde to the formaldehyde flow in step (1) is 1:(25-35); The co-catalyst is selected from sodium hydroxide and / or potassium hydroxide and is added in the form of an aqueous solution. The amount of the co-catalyst added is required to control the pH value of the second stage hydrogenation reaction discharge to be between 7 and 14. The conditions for the first stage hydrogenation reaction include: an operating pressure of 3 to 30 MPaG, a reaction temperature of 100 to 180° C., a nickel-based catalyst, and a molar ratio of inlet hydrogen to 1,4-butynediol of 10 to 15; The conditions for the second stage hydrogenation reaction include: an operating pressure of 24-34 MPaG, a reaction temperature of 120-180° C., a nickel-based catalyst, and a molar ratio of inlet hydrogen to 1,4-butynediol of 10-15; The two-stage hydrogenation reaction is carried out in a bubbling bed hydrogenation reactor.

2. A method for co-producing 1,4-butanediol and methyl-1,4-butanediol, characterized in that: The method comprises the following steps: (1) Formaldehyde and acetylene react in a 1,4-butynediol synthesis reactor to generate a 1,4-butynediol stream; (2) The 1,4-butynediol stream undergoes a two-stage hydrogenation reaction to co-produce 1,4-butanediol and methyl-1,4-butanediol; Without recovering the unreacted formaldehyde in step (1), the valve on the connecting pipeline between the discharge port of the 1,4-butynediol synthesis reactor and the feed port of the formaldehyde circulation tower is closed, and the discharge port of the 1,4-butynediol synthesis reactor is connected to the feed port of the first hydrogenation reactor; formaldehyde is added to the top of the first hydrogenation reactor, and a co-catalyst is added to the second hydrogenation reaction process; The mass ratio of the supplementary formaldehyde to the formaldehyde flow in step (1) is 1:(6-9); The co-catalyst is selected from sodium hydroxide and / or potassium hydroxide and is added in the form of an aqueous solution. The amount of the co-catalyst added is required to control the pH value of the second stage hydrogenation reaction discharge to be between 7 and 14. The conditions for the first stage hydrogenation reaction include: an operating pressure of 3 to 30 MPaG, a reaction temperature of 100 to 180° C., a nickel-based catalyst, and a molar ratio of inlet hydrogen to 1,4-butynediol of 1 to 5; The conditions for the second stage hydrogenation reaction include: an operating pressure of 24-34 MPaG, a reaction temperature of 120-180° C., a nickel-based catalyst, and a molar ratio of inlet hydrogen to 1,4-butynediol of 10-15; The two-stage hydrogenation reaction is carried out in a bubbling bed hydrogenation reactor.

3. The method according to claim 1 or 2, characterized in that In the step (1), the mass ratio of the formaldehyde flow to the acetylene flow is (2-10):

1.

4. The method according to claim 1 or 2, characterized in that In the step (1), the mass ratio of the formaldehyde flow to the acetylene flow is (3-8):

1.

5. The method according to claim 1 or 2, characterized in that The reaction conditions of the formaldehyde and acetylene include: Operating pressure is 0.05~0.2MPaG; The reaction temperature is 85~95℃; And / or, the catalyst is a Cu-Bi complex catalyst.

6. The method according to claim 1 or 2, characterized in that The flow rate of the formaldehyde logistics in step (1) is 5000-7000 kg / h, and / or the flow rate of the acetylene logistics in step (1) is 500-1500 kg / h.

7. The method according to claim 1 or 2, characterized in that The amount of the co-catalyst added is required to control the pH value of the second stage hydrogenation reaction output to be between 8 and 12; And / or, the concentration of the co-catalyst aqueous solution is 10-40 wt%, and the amount added does not exceed 1 wt% of the mass of the formaldehyde flow in step (1).

8. The method according to claim 1 or 2, characterized in that The method further comprises step (3) a distillation process: removing heavy substances, recovering methanol and removing light substances from the discharge of the second stage hydrogenation reaction.

9. The method according to claim 8, characterized in that The de-weighting comprises the following operations: Operating pressure 3~8KPaA; The number of theoretical plates is 10~20; and / or, reflux ratio 0.5~2; The methanol recovery comprises the following operations: Operating pressure 5~10KPaA; The number of theoretical plates is 20~40; and / or, reflux ratio 1 to 3; The light removal includes the following operations: Operating pressure 5~10KPaA; The number of theoretical plates is 20~40; and / or, reflux ratio 2~5.

10. The method according to claim 1, characterized in that The method is carried out in the following system, which comprises: 1,4-Butynediol synthesis reactor; a formaldehyde circulation tower located downstream of the 1,4-butynediol synthesis reactor; A first hydrogenation reactor and a second hydrogenation reactor are located downstream of the formaldehyde circulation tower, the first hydrogenation reactor and the second hydrogenation reactor are connected in series, the first hydrogenation reactor and the second hydrogenation reactor are bubbling bed hydrogenation reactors, both of which are provided with a nickel-based catalyst layer, and the first hydrogenation reactor is also provided with a co-catalyst feed end; an aldehyde feeding end, the aldehyde feeding end being used to provide more aldehyde to the first hydrogenation reactor; the aldehyde feeding end being arranged in the middle of the first hydrogenation reactor; and a distillation unit located downstream of the hydrogenation reactor, wherein the distillation unit comprises a de-heavy tower, a methanol recovery tower located downstream of the de-heavy tower, and a light tower located downstream of the methanol recovery tower.

11. The method according to claim 2, wherein the method is performed in the following system, the system comprising: 1,4-Butynediol synthesis reactor; a formaldehyde circulation tower located downstream of the 1,4-butynediol synthesis reactor; A first hydrogenation reactor and a second hydrogenation reactor are located downstream of the formaldehyde circulation tower, the first hydrogenation reactor and the second hydrogenation reactor are connected in series, the first hydrogenation reactor and the second hydrogenation reactor are bubbling bed hydrogenation reactors, both of which are provided with a nickel-based catalyst layer, and the second hydrogenation reactor is also provided with a co-catalyst feed end; an aldehyde feeding end, the aldehyde feeding end being used to provide more aldehyde to the first hydrogenation reactor; the aldehyde feeding end being arranged at the top of the first hydrogenation reactor; and a distillation unit located downstream of the hydrogenation reactor, wherein the distillation unit comprises a de-heavy tower, a methanol recovery tower located downstream of the de-heavy tower, and a light tower located downstream of the methanol recovery tower.

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