A method, system and purified cumene material

Abstract

The application discloses a method and system for purifying cumene material and purified cumene, and the method comprises the following steps: (1) introducing the cumene material into a recovery tower, discharging light components from the top of the tower, and discharging heavy components from the bottom of the tower; (2) adding water and / or water vapor into the light components discharged from the top of the tower, and separating the organic phase I by standing; and (3) performing alkali washing and / or water washing on the organic phase I. The cumene material is obtained from a hydrogenolysis unit for preparing propylene oxide by means of CHP method; in the step (3), the organic phase II is obtained by performing alkali washing on the organic phase I, and then the organic phase II is subjected to water washing, and the organic phase is recycled into the recovery tower after partial water washing, and the purified cumene is obtained by discharging the organic phase after the rest water washing. The cumene purified by the method and system has high purity, and has higher conversion rate and selectivity when used for oxidation reaction.

Description

Technical Field

[0001] This invention pertains to the purification process of cumene, and particularly relates to a method, system, and purified cumene. Background Technology

[0002] Propylene oxide (PO) is an important organic chemical raw material, mainly used in the production of polyether polyols, propylene glycol, and propylene glycol ethers, with polyether polyols accounting for approximately 70% of consumption. Currently, the main commercial production methods for PO include the chlorohydrin process, the co-oxidation process (PO / SM), and the cumene peroxide recycling process (CHP). The CHP process has the following advantages: the conversion rate and selectivity of the entire process are very high, the only product is PO, and cumene is recycled within the system, unaffected by fluctuations in the price of the byproduct styrene, bringing stable economic benefits to the production enterprise; the process flow is relatively simple, the fixed investment is 1 / 3 lower than the PO / SM process, and the CHP process has lower requirements for equipment corrosion resistance. In the CHP process for producing propylene oxide, a large amount of α,α-dimethylbenzyl alcohol (DMBA) is generated during the epoxidation of propylene, which needs to be converted into cumene through hydrogenolysis and re-entered into the reaction cycle.

[0003] At the beginning of this century, Sumitomo Chemical Co., Ltd. of Japan developed a new process for producing PO using CHP as an oxidant. This process mainly includes steps such as cumene oxidation, propylene epoxidation, propylene recovery and PO purification, α,α-dimethylbenzyl alcohol hydrogenolysis, and separation of harmful impurities. This process has the following advantages: the overall conversion rate and selectivity are very high; the product is only PO, with no co-products, and it is unaffected by fluctuations in by-product prices, providing manufacturers with more stable economic benefits. The process flow is relatively simpler than the ethylbenzene co-oxidation method, and it has lower requirements for equipment corrosion resistance.

[0004] However, the propylene epoxidation reaction involves several side reactions, including: CHP decomposition to phenol and acetone: In the epoxidation reactor, trace amounts of CHP decompose to produce phenol and acetone. The presence of organic acids or excessively high reaction temperatures can promote the decomposition of CHP into phenol and acetone. The presence of phenol further promotes the polymerization of PO, while the presence of acetone reduces the purity of PO. Therefore, it is crucial to strictly control the depth of cumene oxidation and the temperature of the epoxidation reaction, as well as the generation of organic acids, to avoid the excessive production of phenol and acetone.

[0005]

[0006] PO hydrolyzes to produce propylene glycol, which then polymerizes into low-molecular-weight polyether polyols. Trace amounts of PO react with water to hydrolyze and produce propylene glycol, which then polymerizes to form oligomers. The presence of water, phenol, and propylene glycol promotes the formation of PO polymers, which is a major byproduct affecting PO selectivity. The formation of PO oligomers not only increases propylene consumption but also reduces catalyst activity due to their coating on the catalyst surface. Reducing the water content in the material can significantly reduce the formation of PO oligomers.

[0007]

[0008] CHP decomposes into acetophenone and methanol: In the epoxidation reactor, trace amounts of CHP thermally decompose into acetophenone and methanol. Methanol is further oxidized to formaldehyde and even formic acid. Acetophenone is removed as a heavy component in the recovery tower; the generation of methanol, formaldehyde, and formic acid increases the difficulty of separating PO products.

[0009]

[0010] DMBA decomposes into α-methylstyrene (AMS) and water:

[0011] In the epoxidation reactor, a small amount of DMBA decomposes into AMS and water. AMS is then hydrogenated and converted into cumene in the subsequent DMBA hydrogenolysis reactor.

[0012]

[0013] CHP condenses with DMBA to form dicumyl peroxide: During the epoxidation reaction and distillation process, trace amounts of CHP will condense with DMBA to form dicumyl peroxide. The formation of this substance affects the effective utilization rate of CHP and increases the consumption of cumyl peroxide.

[0014]

[0015] Peroxides promote the formation of cumene-2-diisopropylbenzene (diisopropylbenzene): Peroxides, such as diisopropylbenzene peroxide, are effective free radical initiators. Under heating conditions, they can cause cumene to generate phenylisopropyl radicals, which further dimerize to obtain cumene-2-diisopropylbenzene (diisopropylbenzene). In this process, diisopropylbenzene peroxide is consumed and converted into DMBA. Therefore, the amount of cumene-2-diisopropylbenzene generated is comparable to the amount of peroxide. Once the peroxide is consumed, cumene-2-diisopropylbenzene will no longer be generated.

[0016]

[0017] In Sumitomo Chemical's patent CN 109415331A, the hydrogenolysis of α,α-dimethylbenzyl alcohol is divided into two steps: α,α-dimethylbenzyl alcohol is dehydrated to α-methylstyrene (dehydration reaction), and subsequently, α-methylstyrene reacts with hydrogen to produce cumene (hydrogenation reaction). Activated alumina is preferred as the dehydration catalyst, and Cu or Pd-based catalysts are preferred as the hydrogenation catalyst. To reduce the temperature difference between the bed inlet temperature and the hot spot, CO is used to reduce the hydrogen concentration, which also inhibits catalyst activity and suppresses the problem of over-hydrogenation of benzyl alcohol. However, too low a CO concentration will reduce the selectivity of cumene, while too high a concentration will lead to catalyst poisoning. Japanese patents JP2001-270880A and 2003-081886A report a technique for producing cumene from α,α-dimethylbenzyl alcohol using a copper-based catalyst. However, due to the high activation energy of the dimethylbenzyl alcohol hydrogenolysis, the cumene yield is low. US Patent 7442843 discloses a process for producing cumene. This technology uses a palladium-based catalyst and α,α-dimethylbenzyl alcohol and hydrogen as raw materials to produce cumene through hydrogenolysis or dehydration hydrogenation. The hydrogen used contains 0.1 to 10 vol% CO, which can significantly improve the conversion rate of dimethylbenzyl alcohol and the selectivity of cumene.

[0018] Indirect hydrogenolysis mechanism: A bifunctional catalyst with a hydrogenation metal supported on an acidic support is employed, and the hydrogenolysis reaction is dominated by an indirect hydrogenolysis mechanism. DMBA first undergoes dehydration at the acidic site of the catalyst to generate AMS, and then AMS undergoes hydrogenation at the metal site of the catalyst to generate cumene. The reaction process is shown below:

[0019]

[0020] The products of cumene produced by the hydrogenolysis or dehydration hydrogenation of benzyl alcohol contain, in addition to cumene, small amounts of organic acids, acetone, 1,2-propanediol, propylene glycol ethers, phenol, water, and other oxygen-containing compounds. Formic acid, acetic acid, propionic acid, and other organic acids, as well as acetone, have boiling points much lower than cumene and all enter the top of the recovery column. 1,2-propanediol, propylene glycol ethers, and cumene form a binary low-boiling-point azeotrope and also enter the top of the recovery column. The bottom of the column mainly contains heavy components such as dipropylene glycol, tripropylene glycol, phenylethyl alcohol, methylbenzyl alcohol, cumene, and gums. Phenol, with a boiling point lower than the heavy components in the bottom column, also mostly enters the top of the column. If impurities such as organic acids, phenol, alcohols, and ethers are not removed, it will adversely affect the downstream cumene oxidation unit, reducing the conversion rate and selectivity of the cumene oxidation reaction. Phenol has the greatest impact. Therefore, it is essential to treat the recovered cumene. Summary of the Invention

[0021] To overcome the problems existing in the prior art, the present invention provides a method, system and purified cumene material for purifying cumene. The method involves first removing the weight of the cumene material, followed by alkaline washing and water washing to obtain purified cumene. When the purified cumene is recycled back to the reaction system, the oxidation reaction conversion rate and selectivity can be significantly improved.

[0022] One objective of this invention is to provide a method for purifying cumene, the method comprising:

[0023] (1) First, introduce the cumene material into the recovery tower, draw out the light component from the top of the tower, and discharge the heavy component from the bottom of the tower;

[0024] (2) Add water and / or water vapor to the light component drawn from the top of the column, let it stand to separate the phases and take the organic phase I;

[0025] (3) The organic phase I is subjected to alkaline washing and / or water washing.

[0026] In a preferred embodiment, the cumene material comes from the α,α-dimethylbenzyl alcohol (DMBA) dehydration and hydrogenation (abbreviated as hydrogenolysis) unit of the CHP process for preparing propylene oxide.

[0027] In a further preferred embodiment, the cumene material is obtained by separating hydrogen and free water from the hydrogenolysis product of α,α-dimethylbenzyl alcohol. Specifically, if alkaline washing is performed directly, the organic acids, phenols, etc. in the light components will have fewer opportunities to come into contact with the alkaline solution, shorter residence time, and poorer reaction effect.

[0028] In a preferred embodiment, the cumene material contains cumene, organic acid, acetone, 1,2-propanediol, phenol, acetophenone, water, ethylbenzene, α-methylstyrene, dipropylene glycol, tripropylene glycol, and alcohol ethers.

[0029] In a further preferred embodiment, the cumene material contains 80-99% cumene, 0.001-0.1% organic acid, 0.001-0.1% acetone, 0.001-0.08% 1,2-propanediol, 0.01-1% phenol, 0.1-2% acetophenone, 0.001-0.05% water, 0.05-2% ethylbenzene, 0.005-0.5% α-methylstyrene, and 0.01-1% total polypropylene glycol and alcohol ethers.

[0030] In a further preferred embodiment, the cumene material contains 96-99% cumene, 0.001-0.01% organic acid, 0.0030-0.02% acetone, 0.005-0.02% 1,2-propanediol, 0.05-0.3% phenol, 0.3-1.1% acetophenone, 0.005-0.025% water, 0.1-0.8% ethylbenzene, 0.001-0.01% α-methylstyrene, and 0.05-0.5% total polypropylene glycol and alcohol ethers.

[0031] For example, in the cumene material, the content of cumene is 80%, 85%, 90%, 95%, or 99%, the content of organic acids is 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.05%, 0.08%, or 0.1%, and the content of acetone is 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, or 0.002%. The contents of 1,2-propanediol are 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.05%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.05%, or 0.08%, and the contents of phenol are 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.008%, 0.009%, 0.01%, 0.008%, 0.009%, 0.001%, 0.05%, or 0.008%, respectively. The following concentrations are specified: 8%, 0.09%, 0.1%, 0.5%, 0.8%, or 1%; acetophenone content is specified: 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, or 2%; water content is specified: 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, or 0.05%; ethylbenzene content is specified: 0.05%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, or 1%. 2%, 1.5%, 1.8% or 2%, α-methylstyrene content of 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, and total content of polypropylene glycol and alcohol ethers of 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%.

[0032] In this invention, the organic acid includes at least one of formic acid, acetic acid and propionic acid, the polypropylene glycol is selected from at least one of dipropylene glycol and tripropylene glycol, and the alcohol ether is selected from at least one of propylene glycol ether, dipropylene glycol methyl ether and tripropylene glycol methyl ether.

[0033] In a preferred embodiment, in step (1), the operating pressure at the top of the recovery tower is -50 to -100 kPaG, the operating temperature at the top of the tower is 50 to 120°C, and the operating temperature at the bottom of the tower is 120 to 180°C.

[0034] In a further preferred embodiment, in step (1), the operating pressure at the top of the recovery tower is -80 to -95 kPaG, the operating temperature at the top of the tower is 70 to 105°C, and the operating temperature at the bottom of the tower is 140 to 160°C.

[0035] For example, in step (1), the top operating pressure of the recovery tower is -50, -60, -70, -80, -90 or -100 kPaG, the top operating temperature is 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃ or 120℃, and the bottom operating temperature is 120℃, 130℃, 140℃, 150℃, 160℃, 170℃ or 180℃.

[0036] In this process, some heavy component impurities can be removed inside the recovery tower, and then a light component containing cumene is obtained at the top of the tower.

[0037] Alternatively, a two-tower process (two recovery towers) can be adopted. The pressure of the high-pressure recovery tower is increased (e.g., -50 kPaG), the isopropylbenzene in the bottom of the tower is kept at a certain concentration, the gas at the top of the tower is condensed to produce low-pressure steam, water vapor or water is sprayed into the condensate, the material in the bottom of the tower enters the low-pressure recovery tower (e.g., -10 kPaG), the bottom of the tower is deweighted, and the material containing isopropylbenzene in the top of the tower is recycled to the high-pressure recovery tower, which can save energy.

[0038] In a preferred embodiment, the recovery tower is a packed tower.

[0039] In this invention, since the cumene material contains heat-sensitive substances such as propylene glycol, dipropylene glycol, tripropylene glycol, and other heavy components (such as AMS polymer), the recovery tower is preferably a packed tower with low pressure drop, low bottom temperature, forced circulation in the bottom, and a falling film reboiler to reduce the residence time in the bottom and prevent chemical reactions such as polymerization and decomposition from occurring, which would generate heavier components.

[0040] In a further preferred embodiment, the recovery tower employs forced circulation.

[0041] In a further preferred embodiment, a reboiler is provided in the bottom of the recovery tower, and the reboiler is a falling film reboiler.

[0042] In a preferred embodiment, in step (2), the mass flow rate ratio of the water and / or water vapor to the light component is (0.1 to 5):100.

[0043] Adding water and / or steam to the light components drawn from the top of the tower can dissolve water-soluble components such as oxygen-containing compounds, which is beneficial for phase separation in the reflux tank and subsequent alkaline washing and water washing processes.

[0044] For example, in step (2), the mass flow rate ratio of the water and / or water vapor to the light component is 0.1:100, 0.2:100, 0.5:100, 0.8:100, 1:100, 1.2:100, 1.5:100, 1.8:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100, or 5:100.

[0045] In a further preferred embodiment, in step (2), the mass flow rate ratio of the water and / or water vapor to the light component is (0.5 to 2):100.

[0046] In particular, since the boiling point of 1,2-propanediol in cumene is significantly higher than that of cumene, those skilled in the art generally believe that 1,2-propanediol can be removed as a heavy component during the recovery tower. However, after extensive experiments, the inventors discovered that 1,2-propanediol appears in the top material of the recovery tower. Thermodynamic analysis and pilot-scale experiments revealed that 1,2-propanediol undergoes an azeotrope with cumene, resulting in a low-boiling-point azeotrope that exits from the top of the tower together. Additionally, 1,2-propanediol ethers (such as propylene glycol methyl ether) also undergo an azeotrope with cumene and are collected from the top of the tower.

[0047] Meanwhile, the inventors discovered through experiments that the mixture formed by azeotropic reaction of 1,2-propanediol and / or its ether with cumene can undergo liquid-liquid phase separation upon cooling. Therefore, 1,2-propanediol and / or its ether can be separated from cumene using inexpensive methods such as natural sedimentation.

[0048] If water is not added to the light component at the top of the column, the separation efficiency of 1,2-propanediol and / or its ether will decrease. This is because 1,2-propanediol is a water-soluble substance, and alcohol ethers such as propylene glycol monomethyl ether contain hydroxyl groups and ether bonds, making them both lipophilic and hydrophilic. Direct alkali washing and water washing will lead to emulsification of the solution, resulting in poorer alkali and water washing effects.

[0049] In addition, adding water and / or steam to the light component at the top of the column can promote the dissolution of oxygen-containing compounds such as organic acids, acetone, 1,2-propanediol, propylene glycol ether, and phenol into the water, thereby enhancing the dissolution process of oxygen-containing compounds in cumene.

[0050] In a preferred embodiment, in step (2), water and / or steam are added to the light component drawn from the top of the tower and then cooled down, and then allowed to stand for phase separation and organic phase I is taken.

[0051] In a further preferred embodiment, the temperature after the cooling treatment is reduced by 5 to 20°C, preferably by 5 to 15°C, compared to the operating temperature at the top of the tower.

[0052] For example, compared to the operating temperature at the top of the tower, the temperature is reduced by 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 18°C, or 20°C after the cooling treatment. Among these, further temperature reduction is more conducive to natural settling.

[0053] In a further preferred embodiment, the cooling process is carried out in the top condenser of the tower.

[0054] Among them, the inventors discovered through a large number of experiments that cooling treatment at low temperatures is more conducive to liquid-liquid phase separation.

[0055] In a preferred embodiment, in step (3), an alkaline solution is used for alkaline washing, wherein the alkaline solution is selected from at least one of sodium hydroxide aqueous solution and potassium hydroxide aqueous solution.

[0056] In a further preferred embodiment, the weight concentration of the alkaline solution is 1–30 wt%, preferably 5–20 wt%.

[0057] For example, the weight concentration of the alkaline solution is 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%.

[0058] In a further preferred embodiment, the organic phase I in step (2) contains an organic acid, and the molar ratio of the alkali in the alkaline solution to the organic acid in the organic phase I in step (2) is (105-180):100, preferably (120-150):100.

[0059] For example, the organic phase in step (2) contains organic acids, and the molar ratio of the alkali in the alkaline solution to the organic acids in the organic phase in step (2) is 105:100, 110:100, 115:100, 120:100, 125:100, 130:100, 135:100, 140:100, 145:100, 150:100, 155:100, 160:100, 165:100, 170:100, 175:100, or 180:100. In step (2), alkaline washing can remove the organic acids from the cumene material.

[0060] In a preferred embodiment, in step (3), organic phase I is alkali washed to obtain organic phase II, and then organic phase II is washed with water (preferably demineralized water). After partial water washing, the organic phase is recycled back into the recovery tower, and the remaining water-washed organic phase is collected to obtain purified cumene.

[0061] In a further preferred embodiment, the weight ratio of the water used for washing to the organic phase II is (80-150):100, preferably (100-125):100.

[0062] For example, the weight ratio of the water used for washing to the organic phase II is 80:100, 90:100, 100:100, 110:100, 120:100, 130:100, 140:100 or 150:100.

[0063] In a preferred embodiment, the alkaline washing and water washing in step (3) are both carried out in a high-efficiency liquid-liquid separation device.

[0064] In conventional extraction using alkali and / or water, emulsification occurs, leading to an increase in the cumene content in the aqueous phase and a significant increase in wastewater COD. Therefore, to enhance the alkali washing and water washing process, high-efficiency liquid-liquid separation equipment and filter elements are preferred for alkali washing and water washing to improve the removal rate of organic acids and phenols, the recovery rate of cumene, reduce the amount of alkali used in alkali washing and the amount of water used in water washing, and reduce the sodium ion content in the organic phase after alkali washing and water washing.

[0065] In a preferred embodiment, the water and / or water vapor in step (2) and the alkaline washing water in step (3) are preferably water and / or water vapor at 65-80°C (e.g., 65°C, 70°C, 75°C or 80°C), and preferably fully atomized water and / or water vapor.

[0066] Phenol has a melting point of 40.9℃. At lower temperatures, it crystallizes into a white substance. The melting and freezing points of phenol are significantly lowered by trace amounts of water. Figure 1 Adding water significantly lowers the melting point of phenol, facilitating its entry into the aqueous phase. The miscibility of phenol with water is shown in [link to relevant documentation]. Figure 2 As the temperature increases, the solubility of phenol in water increases; therefore, the present invention preferably uses water and / or steam at 65-80°C for washing, which can promote the entry of phenol into the aqueous phase; and fully atomized water and / or steam can further significantly increase the contact probability between phenol molecules and water molecules, so that phenol can be fully dissolved and enter the aqueous phase.

[0067] In the method described in this invention:

[0068] (1) Isopropylbenzene material containing oxygen-containing compounds such as cumene, organic acids, acetone, 1,2-propanediol, propylene glycol ether, phenol, and water enters the recovery tower, and the light components are drawn out from the top of the tower.

[0069] (2) Add water and / or steam to the light components at the top of the recovery tower to dissolve the organic acids, acetone, 1,2-propanediol, propylene glycol ether, phenol, water and other oxygen-containing compounds mixed in cumene in the water, let it stand to dissolve completely, and remove the aqueous phase by liquid-liquid phase separation.

[0070] (3) After liquid-liquid phase separation, an alkaline solution is added to the upper organic phase for alkaline washing. The alkaline-washed organic phase is then washed with water (preferably demineralized water). A portion of the washed organic phase is recycled back to the upper part of the recovery tower as reflux liquid, and another portion is collected and used as raw material for the production of cumene hydroperoxide in the cumene oxidation unit. In this invention, the demineralized water is water with metal ions removed, which is well known to those skilled in the art.

[0071] A second objective of this invention is to provide a system for purifying cumene, preferably for carrying out the method described in one objective of this invention. The system comprises a recovery tower, a settling unit, an alkaline washing unit, and a water washing unit connected in sequence.

[0072] In a preferred embodiment, the operating pressure at the top of the recovery tower is -50 to -100 kPaG, the operating temperature at the top of the tower is 50 to 120°C, and the operating temperature at the bottom of the tower is 120 to 180°C.

[0073] In a further preferred embodiment, the operating pressure at the top of the recovery tower is -80 to -95 kPaG, the operating temperature at the top of the tower is 70 to 105°C, and the operating temperature at the bottom of the tower is 140 to 160°C.

[0074] In a preferred embodiment, the top of the recovery tower is connected to the settling unit via pipeline I.

[0075] In a further preferred embodiment, a water and / or water vapor inlet is provided on the pipeline I.

[0076] In a preferred embodiment, a circulation pipeline II and an external sampling pipeline III are connected to the organic phase outlet of the water washing unit.

[0077] In a further preferred embodiment, the circulation line II is connected to the upper part of the recovery tower for recycling a portion of the organic phase back to the recovery tower.

[0078] In a preferred embodiment, the settling unit is a reflux tank.

[0079] In a preferred embodiment, a cooling unit, preferably a condenser, is provided between the top of the recovery tower and the settling unit.

[0080] In a further preferred embodiment, the temperature of the material after being processed by the cooling unit is 5 to 20°C lower than the temperature at the top of the recovery tower, preferably 5 to 15°C lower.

[0081] In a preferred embodiment, both the alkaline washing unit and the water washing unit are high-efficiency liquid-liquid separation devices.

[0082] A third objective of this invention is to provide cumene obtained by purification using the method described in one objective of this invention or the system described in another objective of this invention.

[0083] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0084] Compared with the prior art, the present invention has the following beneficial effects: the cumene purified by the method or system described in the present invention is relatively pure and has a higher conversion rate and selectivity when undergoing oxidation reaction. Attached Figure Description

[0085] Figure 1 The graph shows the relationship between the melting point of phenol and water content.

[0086] Figure 2 The graph shows the relationship between the miscibility of phenol and water and temperature.

[0087] Figure 3 A schematic diagram of the system described in this invention is shown.

[0088] Figure label:

[0089] A is the recovery tower, B is the top condenser, C is the settling unit (e.g., reflux tank), D is the alkaline washing unit, and E is the water washing unit. 1-Cumene material, 2-Liquid phase discharge (heavy component), 3-Light component, 4-Water and / or water vapor, 5-Condensate, 6-Aqueous phase I, 7-Organic phase I, 8-Alkali solution, 9-Mixed liquid I, 10-Organic phase II, 11-Aqueous phase II, 12-Water, 13-Mixed liquid II, 14-Aqueous phase III, 15-Organic phase III, 17-Reflux liquid, 16-Collected material.

[0090] The cumene material 1, containing a large amount of cumene and small amounts of organic acids, acetone, 1,2-propanediol, propylene glycol ether, phenol, water and other oxygen-containing compounds, enters the recovery tower A. The bottom of the tower is the liquid phase discharge 2, and the top of the tower is the light component 3. Water and / or steam 4 are added to the top gas of the recovery tower. The light component mixed with water is cooled or condensed in the cooling unit B. The condensate 5 is fully dissolved in the settling unit C. The liquid phases are separated, and the aqueous phase I 6 and organic phase I 7 are removed. Alkali solution 8 is added to the organic phase I 7 to form a mixed liquid I 9, which enters the alkaline washing unit D for alkaline washing. After alkaline washing, the organic phase II 10 is removed and the aqueous phase II 11 is removed. Water (preferably demineralized water) 12 is added to the alkaline washed organic phase II 10 to form a mixed liquid II 13, which enters the water washing unit E for water washing. After water washing, the aqueous phase III 14 is removed. A portion of the water-washed organic phase III 15 is recycled back to tower A as reflux liquid 17, and a portion of the material 16 is collected as raw material for the production of cumene hydroperoxide in the cumene oxidation unit. Detailed Implementation

[0091] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0092] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0093] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0094] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0095]

Example 1

[0096] like Figure 3As shown, the feed composition of the recovery tower is as follows: 98.9% cumene, 0.0030% organic acid, 0.0050% acetone, 0.0050% 1,2-propanediol, 0.1000% phenol, 0.3500% acetophenone, 0.0050% water, 0.1500% ethylbenzene, 0.0015% α-methylstyrene, and 0.0600% (dipropylene glycol, tripropylene glycol, and alcohol ethers). Other components are neutralized.

[0097] The operating pressure at the top of the recovery tower is -80 kPaG, the operating temperature is 102℃ (condensate temperature is 90℃), and the operating temperature at the bottom of the tower is 160℃.

[0098] The recovery tower is a packed tower with forced circulation in the bottom, and the reboiler in the bottom is a falling film reboiler.

[0099] The ratio of the mass flow rate of deionized water added to the overhead gas to the mass flow rate of the overhead gas phase is 0.5:100.

[0100] The alkaline solution used in the alkaline washing unit is a 20wt% sodium hydroxide solution. The molar ratio of the amount of sodium hydroxide solution added (calculated as sodium hydroxide) to the organic acid in the condensate is 150:100. The mass ratio of the amount of demineralized water added to the organic phase in the alkaline washing unit is 125:100.

[0101] The recovery rate of cumene at the top of the tower was 99.987%, the organic acid content was ≤1ppm, the sodium ion content was ≤1ppm, and the phenol removal rate reached 97.0%.

[0102]

Example 2

[0103] Same as in Example 1, the operating pressure at the top of the recovery tower is -85 kPaG, the operating temperature is 94°C (condensate temperature is 85°C), and the operating temperature at the bottom of the tower is 154°C.

[0104] The ratio of the mass flow rate of water vapor added to the top gas to the mass flow rate of the top gas phase is 0.75:100.

[0105] The alkaline solution used in the alkaline washing unit is a 15wt% sodium hydroxide solution. The molar ratio of the amount of sodium hydroxide solution added (calculated as sodium hydroxide) to the organic acid in the condensate is 130:100. The mass ratio of the amount of demineralized water added to the organic phase in the alkaline washing unit is 115:100.

[0106] The recovery rate of cumene at the top of the tower was 99.985%, the organic acid content was ≤1ppm, the sodium ion content was ≤1ppm, and the phenol removal rate reached 97.5%.

[0107]

Example 3

[0108] Same as in Example 1, the operating pressure at the top of the recovery tower is -90 kPaG, the operating temperature is 81°C (condensate temperature is 75°C), and the operating temperature at the bottom of the tower is 140°C.

[0109] The ratio of the mass flow rate of deionized water added to the overhead gas to the mass flow rate of the overhead gas phase is 0.80:100.

[0110] The alkaline solution used in the alkaline washing unit is a 10wt% sodium hydroxide solution. The molar ratio of the amount of sodium hydroxide solution added (calculated as sodium hydroxide) to the organic acid in the condensate is 120:100. The mass ratio of the amount of demineralized water added to the organic phase in the alkaline washing unit is 105:100.

[0111] The recovery rate of cumene at the top of the tower was 99.986%, the organic acid content was ≤1ppm, the sodium ion content was ≤1ppm, and the phenol removal rate reached 97.8%.

[0112]

Example 4

[0113] Same as in Example 1, the operating pressure at the top of the recovery tower is -92 kPaG, the operating temperature is 80°C (condensate temperature is 70°C), and the operating temperature at the bottom of the tower is 136°C.

[0114] The ratio of the mass flow rate of deionized water added to the overhead gas to the mass flow rate of the overhead gas phase is 0.95:100.

[0115] The alkaline solution used in the alkaline washing unit is a 10wt% sodium hydroxide solution. The molar ratio of the amount of sodium hydroxide solution added (calculated as sodium hydroxide) to the organic acid in the condensate is 120:100. The mass ratio of the amount of demineralized water added to the organic phase in the alkaline washing unit is 100:100.

[0116] The recovery rate of cumene at the top of the tower was 99.987%, the organic acid content was ≤1ppm, the sodium ion content was ≤1ppm, and the phenol removal rate reached 98.0%.

[0117]

Example 5

[0118] Same as in Example 1, but with a different feed composition for the recovery tower: 97.5% cumene, 0.0080% organic acid, 0.0095% acetone, 0.0050% 1,2-propanediol, 0.1000% phenol, 0.3500% acetophenone, 0.0050% water, 0.1500% ethylbenzene, 0.0015% α-methylstyrene, 0.0600% dipropylene glycol, tripropylene glycol, and alcohol ethers, with other components neutralized.

[0119] The operating pressure at the top of the recovery tower is -95 kPaG, the operating temperature is 70℃ (condensate temperature is 65℃), and the operating temperature at the bottom of the tower is 130℃.

[0120] The recovery tower is a packed tower with forced circulation in the bottom, and the reboiler in the bottom is a falling film reboiler.

[0121] The ratio of the mass flow rate of water vapor added to the top gas to the flow rate of the top gas phase is 0.5:100.

[0122] The alkaline solution used in the alkaline washing unit is a 20wt% sodium hydroxide solution. The molar ratio of the amount of sodium hydroxide solution added (calculated as sodium hydroxide) to the organic acid in the condensate is 145:100. The mass ratio of the amount of demineralized water added to the organic phase in the alkaline washing unit is 120:100.

[0123] The recovery rate of cumene at the top of the tower was 99.989%, the organic acid content was ≤1ppm, the sodium ion content was ≤1ppm, and the phenol removal rate reached 98.1%.

[0124]

Example 6

[0125] Similar to Example 5, the feed composition for the recovery tower is as follows: 96.5% cumene, 0.0180% organic acid, 0.0195% acetone, 0.0180% 1,2-propanediol, 0.2800% phenol, 1.0500% acetophenone, 0.0250% water, 0.7500% ethylbenzene, 0.0100% α-methylstyrene, 0.4800% dipropylene glycol, tripropylene glycol, and alcohol ethers, with other components neutralized.

[0126] The operating pressure at the top of the recovery tower is -95 kPaG, the operating temperature is 70℃ (condensate temperature is 60℃), and the operating temperature at the bottom of the tower is 130℃.

[0127] The recovery tower is a packed tower with forced circulation in the bottom, and the reboiler in the bottom is a falling film reboiler.

[0128] The ratio of the mass flow rate of deionized water added to the overhead gas to the mass flow rate of the overhead gas phase is 0.5:100.

[0129] The alkaline solution used in the alkaline washing unit is a 20wt% sodium hydroxide solution. The molar ratio of the amount of sodium hydroxide solution added (calculated as sodium hydroxide) to the organic acid in the condensate is 145:100. The mass ratio of the amount of demineralized water added to the organic phase in the alkaline washing unit is 120:100.

[0130] The recovery rate of cumene at the top of the tower was 99.988%, the organic acid content was ≤1ppm, the sodium ion content was ≤1ppm, and the phenol removal rate reached 98.1%.

[0131] Comparative Example 1

[0132] The process of Example 1 was repeated, except that water was not added to the top gas of the recovery tower; that is, the top gas was directly condensed, alkali washed, and water washed after it came out of the tower.

[0133] The recovery rate of cumene at the top of the tower was 99.965%, the organic acid content was ≤1ppm, the sodium ion content was ≤20ppm, and the phenol removal rate reached 96.0%.

[0134] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for purifying cumene, the method comprising: (1) First, introduce the cumene material into the recovery tower, draw out the light component from the top of the tower, and discharge the heavy component from the bottom of the tower; The cumene feedstock comes from the α,α-dimethylbenzyl alcohol dehydration and hydrogenation unit of the CHP process for preparing propylene oxide; the cumene feedstock contains cumene, organic acids, acetone, 1,2-propanediol, phenol, acetophenone, water, ethylbenzene, α-methylstyrene, dipropylene glycol, tripropylene glycol, and alcohol ethers; the operating pressure at the top of the recovery tower is -50 to -100 kPaG, the operating temperature at the top of the tower is 50 to 120°C, and the operating temperature at the bottom of the tower is 120 to 180°C; (2) Add water and / or water vapor to the light component drawn from the top of the tower, wherein the mass flow rate ratio of the water and / or water vapor to the light component is (0.1~2):100, allow to stand and separate phases, and take organic phase I; (3) The organic phase I is washed with alkali and water. The organic phase I is washed with alkali to obtain organic phase II. The organic phase II is then washed with water. After partial water washing, the organic phase is recycled to the recovery tower. The remaining organic phase is washed with water and then collected to obtain purified cumene. The weight ratio of water used for washing to organic phase II is (80~150):

100.

2. The method according to claim 1, characterized in that, In step (2), water and / or steam are added to the light component drawn from the top of the tower and then cooled down. The components are then allowed to stand and separate into phases, and the organic phase I is taken.

3. The method according to claim 2, characterized in that, Compared to the operating temperature at the top of the tower, the temperature is reduced by 5-20°C after the cooling treatment.

4. The method according to claim 1, characterized in that, In step (3), alkaline washing is performed using an alkaline solution.

5. The method according to claim 4, characterized in that, The alkaline solution is selected from at least one of sodium hydroxide aqueous solution and potassium hydroxide aqueous solution.

6. The method according to claim 4, characterized in that, The weight concentration of the alkaline solution is 1~30wt%; The organic phase I in step (2) contains organic acids, and the molar ratio of alkali to organic acid in the organic phase I in step (2) is (105~180):

100.

7. The method according to claim 6, characterized in that, The weight concentration of the alkaline solution is 5-20 wt%. The organic phase I in step (2) contains organic acids, and the molar ratio of alkali to organic acid in the organic phase I in step (2) is (120~150):

100.

8. The method according to claim 1, characterized in that, In step (3), the weight ratio of the water used for washing to the organic phase II is (100~125):100.

Images