Recovery process of p-tert-butylphenol waste liquid

Abstract

The invention relates to the technical field of p-tert-butylphenol, and discloses a p-tert-butylphenol waste liquid recovery process which comprises the following steps: mixing a p-tert-butylphenol waste liquid with phenol, and enabling the mixture to enter a transalkylation reactor for reaction; the reaction product is separated, the obtained phenol is separated from the tower top, a part of phenol is recycled to the transalkylation reactor to be continuously used, the other part of phenol is recycled to the p-tert-butylphenol device to serve as a raw material, a liquid phase obtained in the tower kettle is sent to a p-tert-butylphenol refining system, and heavy-component tar is finally sent to an incinerator to be treated. According to the method, the p-tert-butylphenol waste liquid can be directly recycled to a p-tert-butylphenol device after being recycled through the transalkylation reaction, so that the yield and quality of a p-tert-butylphenol product are improved, meanwhile, the yield of an o-tert-butylphenol product and the yield of a 2, 4-di-tert-butylphenol product are improved, and the production cost is reduced. The unit consumption of the p-tert-butylphenol product and the waste liquid discharge amount of the whole device are reduced, no new waste gas or waste liquid is added, and efficient utilization of resources is achieved.

Description

Technical Field

[0001] This invention relates to the field of p-tert-butylphenol preparation technology, specifically a process for recovering p-tert-butylphenol waste liquid. Background Technology

[0002] p-tert-Butylphenol is an important organic chemical raw material, mainly used in: oil-soluble phenolic resins, polycarbonate resin end-capping agents, rubber vulcanizing agents, ink additives, flame retardants, etc. In addition, it is also used in ultraviolet absorbers, surfactants, and pesticides.

[0003] There are four methods for producing p-tert-butylphenol: (1) Sulfuric acid catalytic method, using phenol and tert-butanol as raw materials and sulfuric acid as catalyst, alkylation reaction is carried out at a temperature of 80-120℃, and the product is obtained by washing with water, crystallization, separation and drying; (2) Resin catalytic batch production method, using phenol and isobutylene as raw materials, synthesizing with a strong acid cation exchange resin as catalyst, and refining by crystallization, washing with water and separation; (3) Improved method of resin catalytic batch production, in which molten phenol is transported to the bottom of the reaction tower, and then isobutylene is introduced from the bottom of the tower and raised under normal pressure. The alkylation reaction is carried out at 80-120℃, and a certain reaction time is controlled so that the p-tert-butylphenol content in the solution exiting the tower is more than 60%. After the alkylphenol is transposed, almost all of it becomes p-tert-butylphenol. Then, it is pumped to the distillation tower by vacuum pump and the product is obtained by vacuum distillation. (4) Resin catalytic continuous production method: Phenol and isobutylene are catalytically alkylated by cation exchange resin in a fluidized bed. The resulting mixed tert-butylphenol is fixed and transposed to p-tert-butylphenol by catalyst. The excess phenol is then separated by vacuum distillation for recycling and the product p-tert-butylphenol is obtained.

[0004] Current methods either have low conversion rates, cause serious pollution, or are not yet industrialized. Meanwhile, the main problem with the molecular sieve catalyst method is that the 2,6-di-tert-butylphenol and p-tert-butylphenol generated during the alkylation reaction are difficult to separate, resulting in excessive 2,6-di-tert-butylphenol content in the p-tert-butylphenol product, which directly leads to the need to discharge a large amount of p-tert-butylphenol waste liquid during the operation of the plant. Summary of the Invention

[0005] The purpose of this invention is to provide a process for recovering tert-butylphenol waste liquid to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A process for recovering p-tert-butylphenol waste liquid includes the following steps:

[0008] S1. The waste liquid of p-tert-butylphenol is mixed with phenol to carry out an alkyl transfer reaction;

[0009] S2. The reaction outlet material is sent to the phenol recovery tower, phenol is obtained at the top of the tower, and the material at the bottom of the tower enters the purification system of the p-tert-butylphenol unit to obtain o-tert-butylphenol, p-tert-butylphenol and 2,4-di-tert-butylphenol.

[0010] Furthermore, the p-tert-butylphenol waste liquid of the present invention comprises p-tert-butylphenol content of at least 98%, preferably 98-99.5%, 2,4-di-tert-butylphenol 0.5-1.2%, and 2,6-di-tert-butylphenol 800-1500 ppm, based on the total mass of the waste liquid.

[0011] The p-tert-butylphenol waste liquid described in this invention originates from a p-tert-butylphenol production unit. This waste liquid contains excessive levels of 2,6-di-tert-butylphenol. The reason for this waste liquid is that during the refining of p-tert-butylphenol, conventional distillation processes result in a severe azeotropic reaction between p-tert-butylphenol and 2,6-di-tert-butylphenol, making separation difficult. Under full-load operation, as the 2,6-di-tert-butylphenol content at the reaction end increases, conventionally designed distillation columns, even at high loads, cannot meet the separation target of 30 ppm or even below 15 ppm for 2,6-di-tert-butylphenol. This necessitates the discharge of large quantities of p-tert-butylphenol waste liquid containing 2,6-di-tert-butylphenol to ensure the p-tert-butylphenol product meets standards. This leads to a significant waste of p-tert-butylphenol in the waste liquid, high treatment costs, and low utilization value. Therefore, this invention proposes a p-tert-butylphenol waste liquid recovery process to achieve the goal of improving quality and increasing production in p-tert-butylphenol production.

[0012] Furthermore, the amount of phenol added is 10wt%-50wt% of the p-tert-butylphenol content in the p-tert-butylphenol waste liquid.

[0013] Furthermore, the alkyl transfer reaction takes place in an alkyl transfer reactor, and the material is preheated before entering the reactor. Specifically, a preheating system is provided before the alkyl transfer reactor. This preheating system uses the reactor outlet material as a heat source to heat the reactor inlet material, that is, the reactor inlet and outlet materials exchange heat, thereby reducing energy consumption and improving energy utilization.

[0014] Furthermore, there is a mixing process before the reactor, in which the tert-butylphenol waste liquid is mixed with phenol. A static mixer is preferably used to fully mix the materials, thereby reducing the problem of poor transfer reaction effect caused by local high material concentration.

[0015] Furthermore, the alkyl transfer reactor is a fixed-bed reactor with a sufficient amount of high-efficiency molecular sieve catalyst to ensure the residence time of the reaction.

[0016] Furthermore, there are many types of catalysts that can be selected for the fixed-bed reactor. Modified catalysts using ZSM-5 molecular sieves are preferred, with a silica-alumina ratio of 15-30 to enhance the accessibility of acidic sites, making them suitable for macromolecular cracking. Modification methods such as impregnation and hydrothermal methods can be used for modification loading. Existing technologies such as CN119215968A and CN119220292A can be referenced, or commercially available finished catalysts can be used.

[0017] Furthermore, the catalyst can be selected from one or more of zinc-modified ZSM-5, copper-zinc-modified ZSM-5, and phosphorus-modified ZSM-5 molecular sieve catalysts. Preferably, the metal loading in zinc-modified ZSM-5 and copper-zinc-modified ZSM-5 is 3-6%, and the phosphorus loading in phosphorus-modified ZSM-5 molecular sieve is 2-5%. More preferably, to achieve a high conversion rate of 2,6-di-tert-butylphenol, zinc-modified ZSM-5 molecular sieve catalyst is selected for the alkyl transfer reaction.

[0018] Furthermore, the temperature of the fixed-bed reactor can be adjusted according to the molecular sieve catalyst selected, such as 100℃-150℃.

[0019] Furthermore, the residence time of the material in the reactor can be selected as 0.5-1 h. A shorter residence time cannot guarantee the conversion rate of 2,6-di-tert-butylphenol, while a longer residence time will cause p-tert-butylphenol to be over-converted into heavy tar, resulting in a decrease in the recovery rate of the target product.

[0020] The alkyl transfer reaction in step S1 of this invention yields the target products phenol, o-tert-butylphenol, p-tert-butylphenol, 2,4-di-tert-butylphenol, and the heavy component tar, etc. A specific reaction pathway example is shown below:

[0021]

[0022] Furthermore, in step S2, the operating conditions of the phenol recovery tower include: top pressure 1-2 kPaA, top temperature 75-85°C, bottom pressure 4-6 kPaA, bottom temperature 137-142°C. Preferably, the bottom of the tower is heated by S10 steam, and phenol is collected from the top. Preferably, the alkyl transfer reactor effluent is fed into the upper layer of the phenol recovery tower to ensure complete phenol removal.

[0023] Furthermore, a portion of the phenol obtained from the top of the phenol recovery tower is recycled to the alkyl transfer reactor for continued use, while the other portion is returned to the feedstock system of the p-tert-butylphenol production unit for the production of p-tert-butylphenol.

[0024] Furthermore, the bottom material of the phenol recovery tower includes o-tert-butylphenol, p-tert-butylphenol, 2,4-di-tert-butylphenol, and heavy fraction tar, etc., which enter the refining system of the p-tert-butylphenol production unit for conventional distillation treatment in p-tert-butylphenol production. The obtained p-tert-butylphenol, o-tert-butylphenol, and 2,4-di-tert-butylphenol are used as the quality-improving and yield-increasing products of this invention. The obtained heavy fraction is sent to the incinerator for processing, and the remaining products... The specific refining system of the p-tert-butylphenol production unit can refer to the post-processing technology for p-tert-butylphenol production in existing technologies (such as CN115121186B, CN115286489A, etc.), and will not be elaborated here.

[0025] The present invention provides a process for recovering p-tert-butylphenol wastewater. This process utilizes p-tert-butylphenol wastewater containing excessive levels of 2,6-di-tert-butylphenol generated in a p-tert-butylphenol production unit. By conducting an alkyl transfer reaction with phenol, the p-tert-butylphenol wastewater is further treated, reducing the 2,6-di-tert-butylphenol content in the wastewater to below 15 ppm. This transforms the wastewater into a valuable resource, improving the quality and yield of p-tert-butylphenol production and achieving efficient resource utilization.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. The method of the present invention uses the waste liquid generated by the p-tert-butylphenol unit as raw material. After recovering the product, the amount of waste liquid discharged from the original unit is reduced, and the material consumption is reduced.

[0028] 2. The process provided by this invention can control the content of 2,6-di-tert-butylphenol in the p-tert-butylphenol product to ≤15ppm, thereby improving the purity of p-tert-butylphenol.

[0029] 3. In this invention, after the alkyl transfer reaction of the p-tert-butylphenol waste liquid, the generated phenol, o-tert-butylphenol, p-tert-butylphenol, 2,4-di-tert-butylphenol, etc. are all materials in the original p-tert-butylphenol device system, with no new substances added and no impact on the operation of the original system.

[0030] 4. The method described in this invention allows for the introduction of a single phenol stream, eliminating the need for further replenishment. Excess phenol generated in the reactor can be recycled and returned to the raw material system of the device to continue serving as a raw material, thereby reducing the material consumption of the device.

[0031] 5. The recycling process for p-tert-butylphenol waste liquid provided by this invention recovers and utilizes the thermal energy of the material, thereby reducing energy consumption. Attached Figure Description

[0032] Figure 1 A process flow diagram of the recovery process of tert-butylphenol waste liquid according to an embodiment of the present invention;

[0033] The components include: 1. Phenol, 2. p-tert-butylphenol waste liquid, 3. Static mixer, 4. Preheater, 5. Alkyl transfer reactor, 6. Reactor pressure control valve, 7. Phenol recovery tower, 8. Condenser, 9. Reflux tank, 10. Reboiler, 11. Phenol, and 12. Tower bottom material. Detailed Implementation

[0034] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. The following embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0035] The main sources of raw materials and equipment are as follows:

[0036] The p-tert-butylphenol waste liquid comes from the waste liquid of Wanhua Chemical's p-tert-butylphenol unit, and its composition includes 98.2 wt% p-tert-butylphenol, 1 wt% 2,4-di-tert-butylphenol, and 1000 ppm 2,6-di-tert-butylphenol.

[0037] Zinc-modified ZSM-5 molecular sieve (silicon-aluminum ratio 16, zinc loading 4wt%), copper-zinc modified ZSM-5 molecular sieve (silicon-aluminum ratio 15, total metal loading 5wt%), and phosphorus-modified ZSM-5 molecular sieve (silicon-aluminum ratio 20, phosphorus loading 3wt%) were all purchased from Shanghai Petrochemical Research Institute; the gel resin was purchased from Xi'an Lanxiao sulfonic acid group gel resin.

[0038] The static mixer is from Shandong Pucheng Fluid Technology Co., Ltd., model SV, with an inner diameter of 0.5m, a length of 1m, and is horizontal.

[0039] The preheater is from Changzhou Fengkai Heat Exchanger Manufacturing Co., Ltd., with an inner diameter of 1m, a tube length of 4m, and a design temperature of 200℃.

[0040] The alkyl transfer reactor was supplied by Jiangnan Boiler & Pressure Vessel Co., Ltd., with a design pressure of 2MPa and a design temperature of 250℃.

[0041] The phenol recovery tower is from Beijing Zehua Chemical Engineering Co., Ltd. The tower has an inner diameter of 1m and a height of 15m, with a total of 36 trays in the rectification section and the stripping section.

[0042] Example 1

[0043] like Figure 1 As shown, 100 kg / h of p-tert-butylphenol wastewater is mixed with 10 kg / h of phenol, preheated to 80°C, and then fed into an alkyl transfer reactor. The reactor contains 500 kg of zinc-modified ZSM-5 molecular sieve catalyst. The reactor temperature is raised to 130°C via electric heating to ensure a material residence time of 30 min. The effluent contains 2 wt% o-tert-butylphenol and 20 ppm 2,6-di-tert-butylphenol.

[0044] The material at the reactor outlet exchanges heat with the material at the inlet to 110°C and then enters the phenol recovery tower. The phenol recovery tower controls the pressure at the top of the tower at 1 kPaA and the temperature at 75°C, and the operating temperature and pressure at the bottom of the tower at 4 kPaA and the temperature at 137°C. After the material entering the tower is vaporized, it is rapidly separated. The recovered phenol is separated from the top of the tower in liquid phase. Part of the phenol (10 kg / h) is recycled to the alkyl reactor, and another part of the phenol (15 kg / h) is recycled to the feed system of the p-tert-butylphenol production unit. A total of 85 kg / h of o-tert-butylphenol, p-tert-butylphenol, 2,4-di-tert-butylphenol, and heavy component tar is separated from the bottom of the tower and sent to the refining system of the p-tert-butylphenol unit.

[0045] After refining, 5 kg / h of the reconstituted tar is discharged as waste liquid for incineration, with a calorific value 100 kJ / kg higher than that of the original p-tert-butylphenol waste liquid.

[0046] This process was verified through equipment experiments. After treating the p-tert-butylphenol waste liquid, the p-tert-butylphenol, which had been treated by the purification system, was finally reused. The increase in p-tert-butylphenol was 35 kg / h, and the content of 2,6-di-tert-butylphenol in the reused p-tert-butylphenol stream was 10 ppm, the increase in o-tert-butylphenol was 15 kg / h, and the increase in 2,4-di-tert-butylphenol was 30 kg / h. After the phenol was reused in the equipment's feed system, it continued to react, reducing the unit consumption by 0.002 t / t and the waste liquid generation by 95%. The generated heavy component waste liquid was incinerated as high-calorific-value tar.

[0047] Example 2

[0048] 100 kg / h of p-tert-butylphenol wastewater was mixed with 45 kg / h of phenol, preheated to 90°C, and then fed into an alkyl transfer reactor. The reactor contained 500 kg of copper-zinc modified ZSM-5 molecular sieve catalyst. The reactor temperature was raised to 150°C via electric heating to ensure a material residence time of 35 min. The effluent contained 2.3 wt% o-tert-butylphenol and 18 ppm 2,6-di-tert-butylphenol.

[0049] The material at the reactor outlet exchanges heat with the material at the inlet to 110°C and then enters the phenol recovery tower. The phenol recovery tower controls the top pressure at 1 kPaA and the operating temperature at 80°C, and the bottom operating temperature and pressure at 6 kPaA and the operating temperature at 140°C. After the material enters the tower, it is rapidly separated after gasification. The recovered phenol is separated from the top of the tower in liquid phase. Part of the phenol (45 kg / h) is recycled to the alkyl reactor, and another part of the phenol (25 kg / h) is recycled to the feedstock system of the p-tert-butylphenol production unit. A total of 75 kg / h of o-tert-butylphenol, p-tert-butylphenol, 2,4-di-tert-butylphenol, and heavy component tar is separated from the bottom of the tower and sent to the refining system of the p-tert-butylphenol unit.

[0050] After refining, 10 kg / h of the heavy fraction tar is discharged as waste liquid for incineration, with a calorific value 100 kJ / kg higher than that of the original p-tert-butylphenol waste liquid.

[0051] This process has been experimentally verified. After treating the p-tert-butylphenol waste liquid, the p-tert-butylphenol that has been treated by the purification system is finally reused. The increase in p-tert-butylphenol is 27 kg / h, and the content of 2,6-di-tert-butylphenol in the reused p-tert-butylphenol stream is 12 ppm, the increase in o-tert-butylphenol is 14 kg / h, and the increase in 2,4-di-tert-butylphenol is 24 kg / h. After the phenol is reused in the raw material system of the unit, it continues to react, reducing the unit consumption by 0.0016 t / t and reducing the waste liquid generation by 90%. The generated heavy component waste liquid is incinerated as high-calorific-value tar.

[0052] Example 3

[0053] 100 kg / h of p-tert-butylphenol wastewater was mixed with 30 kg / h of phenol, preheated to 80°C, and then fed into an alkyl transfer reactor. The reactor contained 500 kg of phosphorus-modified ZSM-5 molecular sieve catalyst. The reactor temperature was raised to 100°C via electric heating to ensure a material residence time of 60 min. The effluent contained 1.8 wt% o-tert-butylphenol and 19 ppm 2,6-di-tert-butylphenol.

[0054] The material at the reactor outlet undergoes heat exchange with the inlet material to reach 80°C before entering the phenol recovery tower. The phenol recovery tower maintains a top pressure of 1 kPaA and an operating temperature of 82°C, while the bottom operating temperature and pressure are 4 kPaA and the operating temperature is 140°C. After gasification, the material entering the tower is rapidly separated, and the recovered phenol is separated from the top of the tower in liquid phase. A portion of the phenol (30 kg / h) is recycled to the alkyl transfer reactor, and another portion (30 kg / h) is recycled to the feedstock system of the p-tert-butylphenol production unit. A total of 70 kg / h of o-tert-butylphenol, p-tert-butylphenol, 2,4-di-tert-butylphenol, and heavy component tar is separated from the bottom of the tower and sent to the p-tert-butylphenol unit refining system.

[0055] After refining, 25 kg / h of the reconstituted tar is discharged as waste liquid for incineration, with a calorific value 100 kJ / kg higher than that of the original p-tert-butylphenol waste liquid.

[0056] This process was verified through equipment experiments. After treating the p-tert-butylphenol waste liquid, the p-tert-butylphenol that has been treated by the purification system is finally reused. The increase in p-tert-butylphenol is 20 kg / h, and the content of 2,6-di-tert-butylphenol in the reused p-tert-butylphenol is 15 ppm, the increase in o-tert-butylphenol is 10 kg / h, and the increase in 2,4-di-tert-butylphenol is 15 kg / h. After the phenol is reused in the equipment's feed system, it continues to react, reducing the unit consumption by 0.001 t / t and the waste liquid generation by 75%. The generated heavy component waste liquid is incinerated as high-calorific-value tar.

[0057] Comparative Example 1

[0058] Compared to Example 1, the catalyst in the reactor was replaced with 500 kg of gel resin, and the reactor temperature was raised to 80°C by electric heating. A small-scale simulation showed an increase in p-tert-butylphenol of 20 kg / h, but the content of 2,6-di-tert-butylphenol in p-tert-butylphenol was 35 ppm, the increase in o-tert-butylphenol was 5 kg / h, and the increase in 2,4-di-tert-butylphenol was 10 kg / h. Wastewater generation only decreased by 10%, and tar consumption and raw material consumption remained largely unchanged. Uncracked materials were still discharged as tar, resulting in low economic efficiency.

[0059] As can be seen from the above, the yields of p-tert-butylphenol, o-tert-butylphenol, and 2,4-di-tert-butylphenol in the examples, the consumption of raw material phenol, the amount of waste liquid generated, and the impact on the original equipment are all superior to those of the comparative example, which greatly improves the production efficiency of the equipment.

[0060] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A process for recovering p-tert-butylphenol waste liquid, characterized in that: S1. Mix p-tert-butylphenol waste liquid with phenol to carry out alkyl transfer reaction; S2. The reaction outlet material is sent to the phenol recovery tower. The top material of the tower yields phenol, and the bottom material enters the p-tert-butylphenol unit purification system.

2. The process according to claim 1, characterized in that: The waste liquid of p-tert-butylphenol contains 98-99.5% p-tert-butylphenol, 0.5-1.2% 2,4-di-tert-butylphenol, and 800-1500 ppm 2,6-di-tert-butylphenol, based on the total mass of the waste liquid.

3. The process according to claim 1 or 2, characterized in that: In step S1, the amount of phenol added is 10wt%-50wt% of the p-tert-butylphenol content in the p-tert-butylphenol waste liquid.

4. The process according to any one of claims 1-3, characterized in that: In step S1, the alkyl transfer reaction is carried out in an alkyl transfer reactor, preferably a fixed-bed reactor, and the reactor is filled with a catalyst, which includes one or more of zinc-modified ZSM-5, copper-zinc modified ZSM-5, and phosphorus-modified ZSM-5 molecular sieve catalysts.

5. The process according to claim 4, characterized in that: In step S1, the alkyl transfer reaction temperature is 100-150℃; and / or the residence time of the material in the alkyl transfer reactor is 0.5-1h.

6. The process according to claim 1, characterized in that: In step S2, the pressure at the top of the phenol recovery tower is 1-2 kPaA, the temperature at the top of the tower is 75-85°C, the pressure at the bottom of the tower is 4-6 kPaA, and the temperature at the bottom of the tower is 137-142°C.

7. The process according to claim 6, characterized in that: In step S2, phenol is obtained from the top of the phenol recovery tower. Part of it is recycled to step S1 for alkyl transfer reaction, and part of it is returned to the feed system of the tert-butylphenol production unit.

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