A method and system for purifying epoxy compound flow

Abstract

The present invention discloses a purification method and system for epoxy compound flow, the purification method comprising: (1) extracting and rectifying the epoxy compound flow to remove impurities therein, to obtain an epoxy compound product and an extractant containing impurities; (2) recovering the extractant containing impurities in step (1) to obtain a recovered extractant; (3) performing solid-liquid separation on the extractant recovered in step (2) to obtain a purified circulating extractant, which is recycled back to step (1); wherein, after step (3) and before step (1), fresh extractant is optionally supplemented. The method and system of the present invention can effectively remove impurities such as aldehyde compounds, ketone compounds, water and alcohol compounds in epoxy compounds, and can efficiently recover the used extractant, realize recycling, and greatly reduce costs.

Description

Technical Field

[0001] The invention belongs to the field of epoxy compound purification, and in particular relates to a method and system for purifying epoxy compound logistics. Background Art

[0002] Epoxides, especially propylene oxide, are the second largest propylene derivatives after polypropylene. They are mainly used to produce polyether polyols, propylene glycol, propylene glycol ether, dipropylene glycol ether, flame retardants, synthetic lubricants, surfactants, propylene carbonate, etc. Its application areas are spread across basic industries, national defense and all aspects of people's daily lives. At present, the mainstream production processes for propylene oxide are mainly chlorohydrin method, ethylbenzene co-oxidation method and hydrogen peroxide direct oxidation method (Hydrogene peroxidepropylene oxide, referred to as "HPPO"). In 2018, the proportion of each process type in the global propylene oxide production was: chlorohydrin method 56%, co-oxidation method 32%, and direct oxidation method 12%.

[0003] The ethylbenzene co-oxidation process was successfully developed in the 1960s. This process uses ethylbenzene as a raw material, oxidizes it to produce ethylbenzene peroxide, and then reacts with propylene to produce propylene oxide. Ethylbenzene peroxide is reduced to methylbenzyl alcohol, and methylbenzyl alcohol is dehydrated to obtain styrene. The ethylbenzene co-oxidation process has a production capacity of about 3 million tons in use worldwide. Internationally, companies that own patents for the co-oxidation process include LyondellBasell Industries (referred to as LyondellBasell), Shell Group (referred to as Shell Group), Repsol Chemical Company of Spain (referred to as Repsol), and Huntsman Company of the United States (referred to as Huntsman Company). Each patented technology has its own characteristics, and the difference between the processes is mainly in the catalyst for the epoxidation reaction. For example, LyondellBasell uses a molybdenum complex solution as a catalyst, which needs to be processed and recycled after the reaction; Shell Group uses TiO2 / SiO2 catalysts. Although it overcomes the disadvantage of the catalyst entering the reaction product and simplifies the separation process, the reactor structure is relatively complex due to the difficulty of heat transfer in the heterogeneous reaction system. Typical foreign co-oxidation propylene oxide technologies have been industrially applied in China. For example, LyondellBasell and China Petrochemical Corporation (Sinopec) jointly built a 285,000 t / a propylene oxide unit at Sinopec Zhenhai Branch using LyondellBasell's technology, and the second phase plans to add 360,000 t / a of production capacity. China National Offshore Oil Corporation (CNOOC) and Shell Group jointly built a propylene oxide project in Huizhou, with a total production capacity of 620,000 t / a for the two phases of propylene oxide units. Tianjin Bohai Chemical Group is building a 200,000 t / a propylene oxide unit using Repsol's technology. Sinochem Quanzhou Petrochemical Co., Ltd. also built a 200,000 t / a propylene oxide unit using Repsol's technology, and it is expected to start trial operation in 2020. Huntsman established a joint venture with Sinopec, and in 2016, it built and put into operation a 240,000 t / a co-oxidation process propylene oxide unit using isobutane as raw material in Nanjing. Yantai Wanhua Group also built a 240,000 t / a production unit through the technology license. In addition to the introduction of typical foreign process technologies, China has also had many years of experience in independently developing co-oxidation processes. The main companies that have made major breakthroughs in the current technology are Yantai Wanhua Group and Changzhou Ruihua Chemical Technology Co., Ltd. Wanhua Group has a 300,000 t / a propylene oxide unit using its own technology in the million-ton ethylene project that has been launched. Dongming CITIC Guoan Ruihua New Materials Co., Ltd. uses Ruihua Technology's technology to build an 80,000 t / a propylene oxide industrial unit. At the same time, Zhejiang Petrochemical Co., Ltd. Phase II project and Shandong Jingbo Petrochemical Co., Ltd. also plan to use Ruihua Technology's technology to build a 240,000 t / a unit and a 300,000 t / a unit respectively.

[0004] The HPPO process was successfully developed at the beginning of this century. This process uses propylene and industrial hydrogen peroxide as raw materials, and directly oxidizes them to produce propylene oxide under the catalysis of titanium silicon molecular sieve catalyst. The entire production process does not emit harmful gases, and the wastewater generated can meet the discharge standards after general treatment. The foreign patent holders of this process are mainly the consortium of Germany's Evonik Group and ThyssenKrupp Group and the consortium of BASF and Dow Chemical. Evonik Group can also provide its own high-concentration hydrogen peroxide (up to 70%) production process, which can be integrated with propylene oxide equipment to reduce energy consumption and save costs. The production capacity of hydrogen peroxide direct oxidation process in foreign countries has reached about 1.26 million t / a, of which the BASF / Dow Chemical consortium process accounts for about 80%. In 2011, the consortium of Evonik Group and ThyssenKrupp Group licensed its HPPO process technology to Jilin Shenhua Group, which invested 25×10 8 Yuan built the first domestic unit in Jilin, with an annual design capacity of 300,000 tons of propylene oxide. In July 2019, Evonik Group licensed its unique hydrogen peroxide process technology and the HPPO process shared with ThyssenKrupp Group to Shandong Qixiang Tengda Chemical Company, which plans to use the technology to build a 300,000 t propylene oxide unit. The domestic HPPO process development has also made major breakthroughs. Jiangsu Yida Chemical Co., Ltd. and Dalian University of Technology jointly established a research and development institution in 2005, and conducted in-depth research on the HPPO process. It is currently building a 150,000 t / a propylene oxide industrialization project in Taixing, Jiangsu, which is expected to be completed in 2020. At the same time, the second phase plans to continue to build a 200,000 t / a unit. Sinopec Petrochemical Research Institute and Changling Refining and Chemical Company cooperated to jointly develop the HPPO process with independent intellectual property rights in 2012 and invested 12.8×10 8 Yuan is building a 100,000 t / a propylene oxide industrial unit at Changling Refinery. Fujian Gulei Petrochemical Company, in which Sinopec holds a stake, also plans to use this technology to build a 300,000 t / a propylene oxide unit. Tianchen Chemical Engineering Company and its joint production enterprises have also achieved a breakthrough in HPPO technology and signed a contract with Shandong Jincheng Petrochemical Group to build a 300,000 t / a unit in Zibo.

[0005] With the acceleration of domestic research and development and large-scale application of propylene oxide production technology, my country's independent propylene oxide technology is catching up. Although the new process lacks long-term operation experience, it will gradually narrow the gap with the international level through continuous improvement and enhancement.

[0006] At present, the domestic propylene oxide chlorohydrin production capacity is about 1800kt / a, accounting for more than 50%. As the country's control over environmental protection continues to increase, the PO industry will inevitably develop towards green environmental protection technology. my country's independently developed new propylene oxide process is expected to reach the international advanced level, and propylene oxide projects using domestic processes are also emerging. The 150kt / a CHP PO project of Sinopec Tianjin Branch also started on July 16, 2020. It uses the technology independently developed by Sinopec Shanghai Petrochemical Research Institute, which is the first application in China. Its process has the characteristics of low unit consumption in the production process, low energy consumption, no co-products, less three waste emissions, green environmental protection, and high safety of device operation. The 120kt / a propylene oxide project of Hongbaoli Group Taixing Chemical Co., Ltd. was successfully trial-produced in early 2019. Recently, the safety completion acceptance passed the review, indicating that the project has basically completed the review and assessment of the application for a safety production license. In addition, Wanhua Chemical Group Chemical Co., Ltd. plans to invest RMB 3.25 billion to build a 300kt / a propylene oxide and 650kt / a styrene unit using ethylbenzene co-oxidation technology, which is expected to be completed and put into operation in 2021. Shandong Binhua New Materials Co., Ltd.'s 300kt / a propylene oxide and 780kt / a tert-butyl alcohol projects are also scheduled to be completed and put into operation in 2021.

[0007] Patent CN1398262A discloses a method for refining propylene oxide products by extracting and distilling with polar solvents such as water, but it is still unable to effectively remove aldehyde impurities. Patent CN1714087A discloses a method for extracting and distilling propylene oxide with a compound containing an unsubstituted amine group (such as hydrazine), which can effectively remove aldehyde impurities in the product, but the hydrazone products generated by the compound and the aldehyde produce high-nitrogen wastewater, which is difficult to treat; Patent CN105906584A discloses a method for removing aldehyde impurities by combining resin and ethanolamine / hydrazine hydrate, but propylene oxide has a certain swelling effect on polymer resin, causing high propylene oxide loss, reduced resin strength and breakage. In addition, substances such as ethanolamine or hydrazine react with aldehydes to form hydrazones, producing nitrogen-containing wastewater, which greatly increases the difficulty of wastewater treatment. Patent CN106117165A discloses a method for adsorbing epoxypropane aldehyde impurities using modified molecular sieves. Although this method overcomes the problems of resin swelling and nitrogen-containing wastewater, the adsorption efficiency decays quickly and regeneration is frequent.

[0008] The crude propylene oxide generated by the reaction usually contains impurities such as water, formaldehyde, acetaldehyde, propionaldehyde, methanol, acetone, methyl formate, etc. Because these impurities form azeotropes with propylene oxide or have a relative volatility close to 1, it is difficult for ordinary distillation to reach the propylene oxide product standard. In order to obtain high-purity propylene oxide that meets the polymerization requirements, the impurities contained in the propylene oxide must be separated and removed. The method currently used in industrial devices is mostly to first use ordinary distillation to remove light components such as C3-C4 hydrocarbons, formaldehyde, acetaldehyde, methyl formate, etc., and then use ordinary distillation to remove heavy components such as water, propionaldehyde, methanol, acetone, propylene glycol, etc., and then use an extractive distillation method to extract the residual aldehydes, water, methyl formate and other oxygen-containing compound impurities, and remove them by washing with water. Extractive distillation generally uses C7-C20 straight-chain and branched hydrocarbons and (or) glycols as extractants.

[0009] During this separation process, chemical reactions are inevitable. The most common propylene oxide hydrolysis reaction produces 1,2-propylene glycol, and propylene oxide reacts with methanol to produce propylene glycol monomethyl ether. The newly generated impurities are stable in nature and are all heavy components. They can be separated by weight removal or removed during the extraction distillation process. Through precise control, the quality of the propylene oxide product can be guaranteed; the above method has the following technical risks: formaldehyde, acetaldehyde, and propionaldehyde can undergo aldol condensation reaction with methanol (the carbonyl group of the aldehyde is added by the hydroxyl group of the alcohol, and the original carbonyl carbon is connected to an alcohol hydroxyl group and an ether bond) to produce hemiacetals and / or acetals. The reaction products are heavier than the reactants, which reduces the difficulty of separation; but hemiacetals are unstable and either continue to produce acetals or decompose back to aldehydes and alcohols. That is to say, in the light component removal step, in the absence of chemical reaction, most of the formaldehyde and acetaldehyde can theoretically be removed as light components, but some of them react with alcohols such as methanol to form hemiacetal and acetal. As propylene oxide and heavy components enter the heavy component removal step, in the heavy component removal step, due to reasons such as increased temperature, the hemiacetal decomposes and decomposes back into aldehydes and alcohols. The light component aldehyde enters propylene oxide again, reducing the quality of the propylene oxide product.

[0010] In the separation process of the above methods, due to the inevitable chemical reaction or wastewater generation, the purification of epoxy compounds still has problems. Summary of the invention

[0011] The technical problem to be solved by the present invention is that in the process of removing aldehydes, ketones, water and alcohol in the prior art, the light components formaldehyde and acetaldehyde that should be removed in the light removal step undergo aldol condensation reaction with the extractant to generate heavy components (semi)acetal (ketone), and in the heavy removal process, the acetal, especially the hemiacetal, decomposes to regenerate the light components formaldehyde and acetaldehyde, which affects the quality of the propylene oxide product. Based on this, the present invention provides a purification method and system for epoxy compound logistics. The method and device have the advantages of simple process flow and low investment, and can be used for propylene oxide purification and propylene oxide waste recycling.

[0012] One of the objects of the present invention is to provide a method for purifying an epoxy compound stream, comprising:

[0013] (1) subjecting the epoxy compound stream to extractive distillation to remove impurities therein, thereby obtaining an epoxy compound product and an extractant containing impurities (the extractant containing impurities comprising impurities and products generated by the reaction of the impurities and the extractant);

[0014] (2) recovering the impurity-containing extractant of step (1) to obtain a recovered extractant;

[0015] (3) performing solid-liquid separation on the extractant recovered in step (2) to obtain a purified circulating extractant, which is recycled back to step (1);

[0016] Wherein, fresh extractant is optionally supplemented after step (3) and before step (1).

[0017] In a preferred embodiment, the epoxide compound stream comprises epoxide compounds, ketone compounds, aldehyde compounds, optional water, optional alcohol compounds, optional ester compounds (such as methyl formate), optional hydrocarbon compounds (such as C5-C6 hydrocarbons) and optional heavy components (such as ethylbenzene and / or isopropylbenzene, etc.).

[0018] In a further preferred embodiment,

[0019] Step 1 is carried out in a de-weighting tower: the extractant and the epoxy compound stream are introduced into the upper and lower parts of the de-weighting tower respectively, and after treatment, the epoxy compound product is taken out from the top of the de-weighting tower, the heavy component material I is taken out from the bottom, and the ketone compound material (such as acetone) is taken out from the lower side line;

[0020] The hydroxyl-containing alcohol ether is extracted and distilled in a deweighting tower to remove ketone compounds (such as acetone), aldehyde compounds, alcohol compounds and water. At the same time, the aldehyde compounds, ketone compounds (such as acetone) and the hydroxyl-containing alcohol ether also undergo an aldol condensation reaction during extraction to generate heavy components acetals and / or ketals (mostly) and hemiacetals and / or hemiketals (a small part);

[0021] and / or

[0022] Step 2 is carried out in a recovery tower: the heavy component material I is introduced into the recovery tower, and after treatment, a light component material I containing ketone compounds (such as acetone), aldehyde compounds, optional water and optional methanol is extracted from the top of the tower; at the same time, the material drawn out from the bottom of the recovery tower is vaporized to obtain a heavy component material II and a light component material II, respectively, the heavy component material II is discharged, and the light component material II is recycled back into the recovery tower, and the extractant is recovered from the bottom of the recovery tower;

[0023] and / or

[0024] Step 3 is performed as follows: the recovered extractant is subjected to cooling treatment and solid-liquid separation (to remove flocculent and / or fibrous and / or solid impurities therein) in sequence to obtain a purified circulating extractant, and the purified circulating extractant and the replenished fresh extractant are separately or mixedly introduced into the deweighting tower described in step 1 to achieve recycling of the extractant.

[0025] The epoxy compound stream is derived from an epoxy compound material (e.g., propylene oxide material) obtained from a propylene and isopropylbenzene hydroperoxide (CHP) CHPPO route, an ethylbenzene hydroperoxide (EBHP) PO / SM route, or a tert-butyl hydroperoxide (TBHP) PO / MTBE route, preferably an epoxy compound material obtained from a tert-butyl hydroperoxide (TBHP) PO / MTBE route. The epoxy compound stream of the present invention may be directly derived from the PO production process, may be a material that is micro-processed after the PO production process, or may be a mixture obtained by mixing corresponding components.

[0026] In a preferred embodiment, in the epoxy compound logistics, the epoxy compound is selected from C3-C6 epoxy compounds, preferably C3-C5 epoxy compounds, such as propylene oxide; and / or the aldehyde compound is selected from at least one of formaldehyde, acetaldehyde and propionaldehyde, preferably acetaldehyde and / or propionaldehyde; and / or the ketone compound is acetone; and / or the alcohol compound is C1-C3 alcohol, preferably methanol.

[0027] In a further preferred embodiment, the epoxide stream comprises epoxide, acetone, acetaldehyde, propionaldehyde, optionally water and optionally methanol.

[0028] In a preferred embodiment, based on 100% of the total weight of the epoxide compound flow, the content of ketone compounds is 0.001-2%, the content of aldehyde compounds is 0.001-2%, the content of water is 0-8%, and preferably does not include 0, the content of alcohol compounds is 0-3%, and preferably does not include 0, the content of ester compounds is 0-2%, and preferably does not include 0, the content of hydrocarbon compounds is 0-1%, and preferably does not include 0, and the content of heavy components is 0-0.5%, and preferably does not include 0.

[0029] In a further preferred embodiment, based on 100wt% of the total weight of the epoxy compound flow, the content of ketone compounds is 0.001-1%, the content of aldehyde compounds is 0.001-1%, the content of water is 0-4%, and preferably does not include 0, the content of alcohol compounds is 0-1.5%, and preferably does not include 0, the content of ester compounds is 0.001-1%, the content of hydrocarbon compounds is 0.001-0.5%, and the heavy component is 0.001-0.1%.

[0030] In a further preferred embodiment, based on 100wt% of the total weight of the epoxy compound flow, the content of ketone compounds is 0.01-0.5%, the content of aldehyde compounds is 0.01-0.5%, the content of water is 0-1%, and preferably does not include 0, the content of alcohol compounds is 0-0.6%, and preferably does not include 0, the content of ester compounds is 0.01-0.8%, the content of hydrocarbon compounds is 0.01-0.3%, and the content of heavy components is 0.01-0.05%.

[0031] For example, the content of ketone compounds is 0.001%, 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%, 0.08% or 0.5%, and the content of ketone compounds can be a range composed of any two of the above point values; the content of aldehyde compounds is 0.01%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0 .45% or 0.5%, the content of aldehyde compounds can be a range consisting of any two of the above point values; the content of water is 0, 0.01%, 0.05%, 0.08%, 0.1%, 0.15%, 0.18%, 0.2%, 0.25%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, the content of water can be a range consisting of any two of the above point values; the content of alcohol compounds is 0, 0.01%, 0.05%, 0.06%, 0.08%, 0.09%, 0.1%, 0.15%, 0.18%, 0.2%, 0.25% , 0.3%, 0.4%, 0.5%, 0.6%, the content of alcohol compounds can be the range consisting of any two of the above points; ester compounds are 0.001%, 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%, 0.08%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, the content of ester compounds can be the range consisting of any two of the above points; hydrocarbon compounds are 0.001%, 0. 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.08% or 0.5%, and the content of hydrocarbon compounds can be a range consisting of any two of the above point values; the heavy components are 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09 or 0.1%, and the content of heavy components can be a range consisting of any two of the above point values.

[0032] In a preferred embodiment, the deweighting tower is optionally filled with a catalyst and / or a filler, preferably a mixture of a filler and a catalyst.

[0033] In a further preferred embodiment, the catalyst is selected from at least one of a solid acid catalyst, an alkaline catalyst and an acid-base catalyst; and / or the filler is selected from at least one of a perforated plate corrugated, a wire mesh corrugated, a high flux, and a mesh corrugated filler.

[0034] Among them, aldehyde compounds, ketone compounds, extractants and optional alcohol compounds mainly undergo uncatalyzed aldol condensation reactions in the de-weighting tower. However, under process conditions where the impurity content of aldehyde compounds and ketone compounds is high, it is preferred to load a catalyst in the de-weighting tower to utilize the catalytic reaction of the catalyst to convert aldehydes, ketones and alcohols into heavy component acetals (ketones) rather than staying at unstable hemiacetals (ketones). Stable acetals (ketones) are more conducive to the separation and purification of propylene oxide.

[0035] In a further preferred embodiment:

[0036] The solid acid catalyst is selected from at least one of (VO)2P2O7, α-VOHPO4, niobic acid and zeolite (e.g., MFI zeolite); at the cation active center of the acidic catalyst, the aldehyde carboxyl group is activated to form an enolate carbonium ion, thereby causing a condensation reaction;

[0037] The alkaline catalyst is selected from at least one of alkaline compounds (e.g., at least one of oxides, hydroxides, bicarbonates, carbonates and carboxylates of alkali metals or alkaline earth metals), organic amine compounds and anion exchange resins; since propylene oxide is hydrolyzed under the action of a strong base in the presence of water, a weakly alkaline catalyst and an anion exchange resin catalyst are preferred;

[0038] The acid-base catalyst has both acidic and basic active centers, and is preferably selected from binary oxides (Ni-P, Mn-P, Fe-P and vP) and / or hydrotalcite.

[0039] The general formula for the reaction of aldehydes (ketones) and alcohols to form hemiacetals (hemiketals) and acetals (ketals) is as follows:

[0040]

[0041] Therefore, if the feed contains alcohol compounds, the alcohol compounds can also condense with the aldehyde compounds in the feed to form heavy components. In the propylene oxide system, there are ketone compounds (such as acetone), which can also react with alcohol compounds (such as methanol) to form ketal (such as acetone acetal).

[0042] The following three examples illustrate that formaldehyde, acetaldehyde, propionaldehyde and substances containing hydroxyl groups such as methanol and ethylene glycol monomethyl ether undergo aldol condensation reactions.

[0043] The reaction equation for the reaction of formaldehyde and methanol to form hemiacetal and acetal is as follows:

[0044]

[0045] The reaction equation for the reaction of acetone and methanol to form hemiketal and ketal is as follows:

[0046]

[0047] The reaction formula for the reaction of propionaldehyde and ethylene glycol monomethyl ether to form hemiacetal and acetal is as follows:

[0048]

[0049] In a preferred embodiment, the operating pressure of the deweighting tower is 20-140 kPaG, preferably 40-120 kPaG; and / or the operating temperature of the top of the deweighting tower is 40-60°C, preferably 45-55°C.

[0050] Among them, the temperature of the deweighting tower should not be too high, otherwise the formed hemiacetal and / or acetal will be decomposed again, thereby affecting the purity of the top product.

[0051] In a preferred embodiment, the extractant is selected from hydroxyl-containing alcohol ethers, preferably at least one selected from ethylene glycol methyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol tert-butyl ether, and propylene glycol butyl ether.

[0052] Wherein, hydroxyl alcohol ether is used as extraction agent because of its hydrophilicity, affinity to ketone, affinity to alcohol and other oxides. The reason why alcoholic solvent (for example propylene glycol) is not adopted is that propylene glycol undergoes dehydration condensation at high temperature (temperature is higher when the present invention reclaims the extraction agent so it is not suitable to adopt propylene glycol), therefore, the present invention adopts hydroxyl alcohol ether. In addition, hydroxyl alcohol ethers such as ethylene glycol monomethyl ether and propylene glycol monomethyl ether differ greatly from the boiling point of propylene oxide, and azeotrope can not be formed yet, and separation and recovery are simple.

[0053] In the present invention, in step 1, the extractant enters from the upper part of the deweighting tower, and the hydroxyl-containing alcohol ether is extracted and distilled to remove acetone, aldehyde, methanol and water. At the same time, aldehydes, ketones and hydroxyl-containing alcohol ethers also undergo aldol condensation reaction during extraction to generate heavy component acetals (ketones). Therefore, the extraction section is also a reaction section.

[0054] In the prior art, the reaction is generally carried out in a reactor first, and then the weight removal treatment is carried out, that is, two devices are required for aldol condensation and weight removal. However, the present invention does not require a reactor, and the aldol condensation and weight removal are carried out directly in a weight removal tower, which saves energy consumption and reduces costs. In addition, a qualified propylene oxide product can also be obtained under the method or mode of the present invention.

[0055] In a preferred embodiment, in step 1, the weight ratio of the extractant to the epoxide compound stream is (0.05-0.80):1, preferably (0.10-0.45):1.

[0056] For example, the weight ratio of the extractant to the epoxide stream is 0.05:1, 0.1:1, 0.2:1, 0.05:1, 0.3:1, 0.4:1, 0.45:1, 0.5:1, 0.6:1, 0.7:1 or 0.8:1.

[0057] in, Figure 1 The extractant 2 and logistics 3 shown in the figure first need to meet the minimum solvent ratio requirement of the extractive distillation, preferably the sum of the solvent ratio requirement of the extractive distillation and the stoichiometric ratio of the aldol condensation reaction. If it is lower than the above minimum value, the removal of aldehydes and ketones cannot meet the design requirements, especially aldehydes.

[0058] In the present invention, an excess amount of extractant is used because: (1) sufficient extractant can promote the aldehyde condensation of aldehydes and ketones in the feed as much as possible; (2) it plays an extraction role and can extract impurities such as water, alcohol, ketone, etc. from the epoxy compound to a large extent; (3) the reason why the present invention can use a large amount of extractant is that the extractant will be recovered and purified later and will not cause waste.

[0059] In a preferred embodiment, in step 1, the heavy component I comprises acetal and / or ketal, hemiacetal and / or hemiketal, an extractant, a ketone compound (such as acetone), an aldehyde compound, an optional alcohol compound (such as methanol) and optional water.

[0060] In a preferred embodiment, in step 1, an acetone-rich material is side-drawn at a position below the feed of the epoxide stream.

[0061] If acetone is not collected from the side line, it will lead to the enrichment of acetone in the de-weighting tower, (1) affecting the purity of the propylene oxide product at the top of the tower, that is, the acetone content in the propylene oxide product is relatively high; (2) the enriched acetone will undergo aldol condensation reaction to form hemiacetal (ketone). Direct collection of the enriched acetone is beneficial to the separation process and can reduce the load of the extractive distillation and aldol condensation reaction.

[0062] In a preferred embodiment, in step 2, the top temperature of the recovery tower is 50-110°C, and the bottom temperature of the recovery tower is 120-185°C.

[0063] In a further preferred embodiment, in step 2, the top temperature of the recovery tower is 60-100°C, and the bottom temperature of the recovery tower is 130-175°C.

[0064] For example, the top temperature of the recovery tower is 50°C, 60°C, 70°C, 80°C, 90°C, 100°C or 110°C, and the bottom temperature is 125°C, 135°C, 145°C, 155°C, 160°C, 170°C or 175°C.

[0065] Among them, in the present invention, by increasing the tower operating pressure and operating temperature of the recovery tower, most of the hemiacetal (and / or ketone) and acetal (and / or ketone) generated in the deweighting tower are decomposed, and the extractant and aldehydes and ketones are regenerated, and the aldehydes and ketones are removed from the top of the recovery tower as light components, and the extractant is recycled. Specifically, the hemiacetal (and / or ketone) can be basically completely decomposed, and the acetal (and / or ketone) can be partially decomposed.

[0066] The pressure of the vaporization treatment is 30-350 kPaG, preferably 50-250 kPaG; and / or the temperature is 125-200°C, preferably 135-180°C.

[0067] For example, the vaporization process has a pressure of 30, 50, 100, 150, 200, 250, 300 or 350 kPaG; and / or a temperature of 120, 130, 140, 150, 160, 170, 180°C, 190 or 200°C.

[0068] Among them, in the process of vaporization treatment, the kettle reboiler is the position with the highest system temperature. High temperature is conducive to the decomposition of hemiacetal (ketone) and / or acetal (ketone). The alcohol ether is recovered and used as the extractant again. On the one hand, it can promote the further decomposition of hemiacetal (ketone) and / or acetal (ketone). On the other hand, the undecomposed hemiacetal (ketone) and / or acetal (ketone) and other heavy components with higher boiling points than the extractant can be discharged and removed (for post-treatment such as as fuel). In this way, the extractant recovered at the top of the recovery tower is further purified.

[0069] The present invention utilizes a kettle-type reboiler as a reboiler and utilizes the separation performance of a single flash evaporation, which is more energy-efficient.

[0070] In a preferred embodiment, in step 3, the recovered extractant is cooled to 30-70°C, preferably 40-60°C, which is the optimal operating temperature through theoretical calculation and experimental verification, taking into account factors such as cooling medium.

[0071] For example, the temperature is lowered to 30°C, 40°C, 50°C, 60°C or 70°C.

[0072] In a further preferred embodiment, in step 3, the temperature reduction treatment is performed sequentially by heat integrated heat exchange and cooling water cooling.

[0073] Among them, the heat exchange network and heat integration are not the research objects of the present invention, and the heat integration carried out based on the extension of the present invention belongs to the expansion of the present invention.

[0074] In a preferred embodiment, in step 3, solid-liquid cyclone is used to perform solid-liquid separation to remove flocculent and / or fibrous and / or solid impurities in the recovered extractant.

[0075] Wherein, in the propylene oxide reaction and separation process, due to the presence of organic acid (the organic acid generated in the propylene epoxidation reaction process, see the following analysis for details), it is inevitable to generate a mixture of inorganic substances such as propylene glycol oligomers (when there is water, propylene oxide and water contact to generate propylene glycol by hydrolysis reaction, and when there is acid and alkali, the hydrolysis reaction can be promoted) and metal oxides or metal salts (metal is mainly iron), flocculent fibrous impurities, which have little power, long natural sedimentation time, and are difficult to separate. The present invention, after cooling the recovered extractant, removes flocculent and / or fibrous and / or solid impurities therein by solid-liquid cyclone treatment, and then circulates back to the deweighting tower. The recovered extractant is treated with solid-liquid cyclone.

[0076] Propylene is oxidized into formaldehyde and acetaldehyde, which are further oxidized into formic acid and acetic acid.

[0077] In the epoxidation reactor, trace amounts of propylene are oxidized by CHP into formaldehyde and acetaldehyde, which are then further oxidized into formic acid and acetic acid, respectively. The production of formaldehyde and acetaldehyde affects propylene consumption on the one hand, and increases the energy consumption of product refining on the other hand. In addition to increasing propylene consumption, formic acid and acetic acid can also cause equipment corrosion. These impurities must be removed during the PO separation and refining process.

[0078]

[0079] In the present invention, if the solid-liquid separation is not performed and the liquid is directly recycled to the deweighting tower, flocculent and / or fibrous and / or solid impurities will accumulate in the deweighting tower, resulting in a decrease in or even disappearance of the extraction efficiency of the extractant. Long-term accumulation will gradually block the heat exchanger (including the reboiler, condenser), tower plates, measuring instruments, and cause a malfunction and shutdown.

[0080] In the prior art, the extractant is generally discharged, but the market price of the extractant, especially the hydroxyl-containing alcohol ether, is relatively high. If it is directly discharged, it will cause a lot of waste and increase the cost. In the present invention, the discharge amount of the extractant can be greatly reduced, the loss of the extractant can be reduced, and the cost can be effectively reduced.

[0081] In a preferred embodiment, in step 3, the solid removal rate after the solid-liquid separation reaches 99.0%.

[0082] The fresh extractant can be supplemented intermittently or continuously according to the enterprise's operating mode. No matter which method is used, the fresh extractant supplemented is a small amount or a trace amount compared with the recycled extractant after purification. Unless a large amount of flocculent matter is generated and needs to be discharged in large quantities, a large amount of extractant needs to be supplemented. The present invention is to solve this problem.

[0083] A second object of the present invention is to provide a purification system for epoxy compound streams, the system comprising:

[0084] De-weighting tower, used for extractive distillation to remove impurities;

[0085] A recovery tower for recovering the extractant;

[0086] Solid-liquid separation device for purifying the recovered extractant.

[0087] In a preferred embodiment, an extractant inlet is provided at the upper portion of the deweighting tower, and an inlet for the material to be processed is provided at the lower portion.

[0088] Wherein, the material to be treated in the present invention is epoxy compound logistics.

[0089] In a further preferred embodiment, a product outlet is provided at the top of the deweighting tower, a heavy component outlet I is provided at the bottom of the deweighting tower, and a side line outlet is provided at the lower part of the deweighting tower.

[0090] Among them, the product outlet is used to produce the epoxy compound product, the heavy component outlet I is used to produce the heavy component material I, and the side line production outlet is used to produce rich acetone and prevent acetone from accumulating in the tower.

[0091] In a further preferred embodiment, the side line outlet is located below the inlet of the material to be processed.

[0092] In a preferred embodiment, an inlet for the material to be recovered is provided in the middle of the recovery tower, a light component outlet I is provided at the top of the recovery tower, and an outlet for recovering the extractant is provided at the bottom of the recovery tower.

[0093] In a further preferred embodiment, the inlet of the material to be recovered is connected to the heavy component outlet I of the deweighting tower.

[0094] In a preferred embodiment, an extractant regenerator and at least one reboiler (used as a normal reboiler to maintain the normal operation of the deweighting tower) are provided in the bottom of the recovery tower, wherein the extractant regenerator is used to vaporize the bottom material (or to regenerate the extractant).

[0095] The bottom of the recovery tower, the extractant regenerator and the middle and lower part of the recovery tower form a cycle. Specifically, the bottom liquid of the recovery tower enters the extractant regenerator, and the light component (regenerated extractant) is circulated back to the recovery tower after vaporization treatment, and the heavy component (component heavier than the extractant, such as acetal and / or ketone, oligomer, etc.) is discharged from the bottom of the extractant for post-treatment such as as fuel.

[0096] In a further preferred embodiment, the reboiler is a forced circulation type reboiler, and the extractant regenerator is a kettle reboiler.

[0097] In a preferred embodiment, the bottom of the recovery tower is connected to the solid-liquid separation device.

[0098] In a further preferred embodiment, a heat exchanger and / or a cooler is provided between the recovery tower and the solid-liquid separation device.

[0099] In a further preferred embodiment, the solid-liquid separation device is connected to the deweighting tower, preferably connected to the extractant inlet of the deweighting tower, so as to circulate the purified extractant back to the deweighting tower.

[0100] In a preferred embodiment, the solid-liquid separation device is a cyclone device, and a solid impurity outlet is provided at the bottom of the cyclone device for separating flocculent and / or fibrous and / or solid impurities in the recovered extractant, and the removal rate can reach 99.0%.

[0101] The endpoints and any values ​​of the scope disclosed in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, the endpoint values ​​of each scope, the endpoint values ​​of each scope and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be regarded as specifically disclosed in this article.

[0102] Compared with the prior art, the present invention has the following beneficial effects:

[0103] (1) The method and system of the present invention can effectively remove impurities such as aldehyde compounds, ketone compounds, water and alcohol compounds from epoxy compounds;

[0104] (2) The method and system of the present invention can efficiently recover the used extractant, realize recycling, and greatly reduce the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0105] Figure 1A schematic diagram showing the structure of an embodiment of the system of the present invention is shown, wherein the deweighting tower is a plate tower, wherein there is no filler and catalyst;

[0106] Figure 2 A schematic structural diagram of another embodiment of the system of the present invention is shown, wherein the deweighting tower is a packed tower, and the packing and the catalyst are mixed and packed (preferably in bundles).

[0107] Description of reference numerals:

[0108] A-deweighting tower, B-recovery tower, C-bottom reboiler, D-extractant regenerator, E-heat exchanger, F-cooler, G-solid-liquid separator.

[0109] 1-supplementary extractant, 2-deweighting tower extractant feed, 3-epoxide compound flow, 4-epoxide compound product, 5-ketone compound, 6-heavy component material I, 7-light component material I containing ketone compound (such as acetone), aldehyde compound, optional water and optional methanol, 8-light component material II, 9-heavy component material II, 10-recovered extractant, 11-heat exchange medium feed, 12-heat exchange medium discharge, 13-circulating cooling water feed water, 14-circulating cooling water return water, 15-flocculated and / or fibrous and / or solid impurities, 16-purified circulating extractant.

[0110] by Figure 1 For example:

[0111] (1) An extractant 2 and an epoxy compound stream 3 are introduced from the upper and lower parts of the de-weighting tower A, respectively. After treatment, an epoxy compound product 4 is taken out from the top of the de-weighting tower A, a heavy component material I 6 is taken out from the bottom, and a ketone compound material 5 (such as acetone) is taken out from the lower side line. In the de-weighting tower, extractive distillation is performed to remove ketone compounds (such as acetone), aldehyde compounds (such as propionaldehyde and / or formaldehyde), alcohol compounds (such as methanol) and water. At the same time, aldehydes, ketones, alcohols and the extractant undergo aldol condensation reaction in the extraction section to generate heavy component acetals (ketones) and a small amount of hemiacetals (ketones). Therefore, the extraction section is also a reaction section.

[0112] (2) introducing the heavy component material I 6 into the recovery tower B, and after treatment, extracting a light component material I 7 containing ketone compounds (such as acetone), aldehyde compounds, optional water, and optional methanol from the top of the tower; at the same time, vaporizing the material drawn out from the bottom of the recovery tower B to obtain a heavy component material II 9 and a light component material II 8, respectively, the heavy component material II 9 is discharged, and the light component material II 8 is recycled back into the recovery tower, and the extractant is recovered from the bottom of the recovery tower B;

[0113] (3) The recovered extractant 10 is cooled by a heat exchanger and a cooler in sequence, and then enters a solid-liquid separator for solid-liquid separation to remove flocculent and / or fibrous and / or solid impurities 15. The purified circulating extractant 16 is mixed with the replenished fresh extractant 1 to form extractant 2, which enters a deweighting tower A. DETAILED DESCRIPTION

[0114] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0115] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0116] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0117] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0118] [Example 1]

[0119] use Figure 1 The system shown is carried out.

[0120] In this Example 1, the composition of the epoxy compound stream to be treated is shown in Table 1:

[0121] Table 1:

[0122] Components Quality composition water 0.1598％ Methanol 0.0697％ Acetaldehyde 0.0755％ acetone 0.0436％ Propionaldehyde 0.1453％ PO 98.7941％ Methyl formate 0.5811％ C5~C6 hydrocarbons 0.1162％ Ethylbenzene or cumene and other heavy components 0.0145％

[0123] In this Example 1, EGME ethylene glycol methyl ether is used as the extractant.

[0124] (1) An extractant 2 and an epoxy compound stream 3 are introduced from the upper and lower parts of the de-weighting tower A, respectively. After treatment, an epoxy compound product 4 is taken out from the top of the de-weighting tower A, a heavy component material I 6 is taken out from the bottom, and a ketone compound material 5 (such as acetone) is taken out from the lower side line. In the de-weighting tower, extractive distillation is performed to remove ketone compounds (such as acetone), aldehyde compounds (such as propionaldehyde and / or formaldehyde), alcohol compounds (such as methanol) and water. At the same time, aldehydes, ketones, alcohols and the extractant undergo aldol condensation reaction in the extraction section to generate heavy component acetals (ketones) and a small amount of hemiacetals (ketones). Therefore, the extraction section is also a reaction section.

[0125] (2) introducing the heavy component material I 6 into the recovery tower B, and after treatment, extracting a light component material I 7 containing ketone compounds (such as acetone), aldehyde compounds, optional water and optional methanol from the top of the tower; at the same time, vaporizing the material drawn from the bottom of the recovery tower B (in a kettle reboiler) to obtain a heavy component material II 9 and a light component material II 8, respectively, the heavy component material II 9 is discharged, and the light component material II 8 is recycled back to the recovery tower, and the extractant is recovered from the bottom of the recovery tower B;

[0126] (3) The recovered extractant 10 is cooled to 50° C. by a heat exchanger and a cooler in sequence, and then enters a solid-liquid separator for solid-liquid separation to remove flocculent and / or fibrous and / or solid impurities 15. The purified circulating extractant 16 is mixed with the replenished fresh extractant 1 to form extractant 2, which enters a deweighting tower A.

[0127] in:

[0128] The mass composition of ethylene glycol monomethyl ether in the extractant stream 2 is 99.7900%, heavy impurities such as propylene glycol (produced by hydrolysis of propylene oxide during separation) is 0.1000%, and water is 0.1100%;

[0129] The weight flow ratio of the extractant 2 to the epoxy compound stream 3 is 0.25:1.0;

[0130] The operating pressure of the deweighting tower top is 45kPaG, and the operating temperature of the tower top is 45℃;

[0131] The operating temperature of the recovery tower top is 77°C, and the operating temperature of the tower bottom is 133°C;

[0132] The pressure of the kettle reboiler is 30 kPaG and the temperature is 136 °C;

[0133] The recovered extractant was treated by solid-liquid cyclone, and the removal rate of flocculent and fibrous impurities reached 99.05%, and the loss rate of the extractant EGME was 0.445%.

[0134] In this Example 1, the composition of the obtained propylene oxide product is shown in Table 2:

[0135] Table 2

[0136] Components Quality composition water 0.0044％ Methanol 0.0147％ Acetaldehyde 0.0029％ acetone 0.0000％ Propionaldehyde 0.0015％ PO 99.3337％ Methyl formate 0.5282％ C5~C6 hydrocarbons 0.1144％ Ethylbenzene or cumene and other heavy components 0.0002％

[0137] In this embodiment, the removal rate of acetaldehyde reaches 96.16%, the removal rate of propionaldehyde reaches 98.97%, and the removal rate of acetone reaches 100%.

[0138] [Example 2]

[0139] The process of Example 1 was repeated, except that:

[0140] In this Example 2, the composition of the epoxy compound stream to be treated is shown in Table 3:

[0141] Table 3:

[0142] Components Quality composition water 0.1453％ Methanol 0.0727％ Acetaldehyde 0.0814％ acetone 0.0465％ Propionaldehyde 0.1395％ PO 98.8228％ Methyl formate 0.5522％ C5~C6 hydrocarbons 0.1221％ Ethylbenzene or cumene and other heavy components 0.0174％

[0143] The mass composition of ethylene glycol monomethyl ether in the extractant stream 2 is 99.7800%, heavy impurities such as propylene glycol are 0.1100%, and water is 0.1100%;

[0144] The weight flow ratio of the extractant 2 to the epoxy compound stream 3 is 0.23:1.0;

[0145] The recovered extractant was treated by solid-liquid cyclone, and the removal rate of flocculent and fibrous impurities reached 99.05%, and the loss rate of the extractant EGME was 0.45%.

[0146] In this Example 2, the composition of the obtained propylene oxide product is shown in Table 4:

[0147] Table 4:

[0148]

[0149]

[0150] In this embodiment, the removal rate of acetaldehyde reaches 96.07%, the removal rate of propionaldehyde reaches 98.71%, and the removal rate of acetone reaches 100%.

[0151] [Example 3]

[0152] The process of Example 1 was repeated, except that:

[0153] In this Example 3, the composition of the epoxy compound stream to be treated is shown in Table 5:

[0154] Table 5:

[0155] Components Quality composition water 0.1308％ Methanol 0.0668％ Acetaldehyde 0.0872％ acetone 0.0523％ Propionaldehyde 0.1598％ PO 98.8027％ Methyl formate 0.5521％ C5~C6 hydrocarbons 0.1308％ Ethylbenzene or cumene and other heavy components 0.0174％

[0156] The mass composition of ethylene glycol monomethyl ether in the extractant stream 2 is 99.7850%, heavy impurities such as propylene glycol are 0.1050%, and water is 0.1100%;

[0157] The weight flow ratio of the extractant 2 to the epoxy compound stream 3 is 0.25:1.0;

[0158] The operating pressure of the deweighting tower top is 60kPaG, and the operating temperature of the tower top is 47℃;

[0159] The operating temperature of the recovery tower top is 85℃, and the operating temperature of the tower bottom is 142℃;

[0160] The pressure of the kettle reboiler is 66 kPaG and the temperature is 145 °C;

[0161] The recovered extractant was treated with solid-liquid cyclone, and the removal rate of flocculent and fibrous impurities reached 99.1%, and the loss rate of extractant EGME was 0.44%.

[0162] In this Example 3, the composition of the obtained propylene oxide product is shown in Table 6:

[0163] Table 6:

[0164] Components Quality composition water 0.0040％ Methanol 0.0141％ Acetaldehyde 0.0028％ acetone 0.0000％ Propionaldehyde 0.0016％ PO 99.3199％ Methyl formate 0.5285％ C5~C6 hydrocarbons 0.1291％ Ethylbenzene or cumene and other heavy components 0.0000％

[0165] In this embodiment, the removal rate of acetaldehyde reaches 96.79%, the removal rate of propionaldehyde reaches 99.00%, and the removal rate of acetone reaches 100%.

[0166] [Example 4]

[0167] The process of Example 1 was repeated, except that:

[0168] In this Example 4, the composition of the epoxy compound stream to be treated is shown in Table 7:

[0169] Table 7:

[0170]

[0171]

[0172] The mass composition of ethylene glycol monomethyl ether in the extractant stream 2 is 99.7950%, heavy impurities such as propylene glycol are 0.0950%, and water is 0.1100%;

[0173] The weight flow ratio of the extractant 2 to the epoxy compound stream 3 is 0.25:1.0;

[0174] The operating pressure of the deweighting tower top is 80kPaG, and the operating temperature of the tower top is 51℃;

[0175] The operating temperature of the recovery tower top is 89°C, and the operating temperature of the tower bottom is 145°C;

[0176] The pressure of the kettle reboiler is 80 kPaG and the temperature is 148 °C;

[0177] The recovered extractant was treated with solid-liquid cyclone, and the removal rate of flocculent and fibrous impurities reached 99.15%, and the loss rate of extractant EGME was 0.435%.

[0178] In this Example 4, the composition of the obtained propylene oxide product is shown in Table 8:

[0179] Table 8:

[0180]

[0181]

[0182] In this embodiment, the removal rate of acetaldehyde reaches 96.93%, the removal rate of propionaldehyde reaches 98.62%, and the removal rate of acetone reaches 100%.

[0183] [Example 5]

[0184] The process of Example 1 was repeated, except that:

[0185] In this Example 5, the composition of the epoxy compound stream to be treated is shown in Table 9:

[0186] Table 9:

[0187] Components Quality composition water 0.1744％ Methanol 0.0872％ Acetaldehyde 0.0872％ acetone 0.0523％ Propionaldehyde 0.1598％ PO 98.8130％ Methyl formate 0.5522％ C5~C6 hydrocarbons 0.1744％ Ethylbenzene or cumene and other heavy components 0.0174％

[0188] The mass composition of ethylene glycol monomethyl ether in the extractant stream 2 is 99.6700%, heavy impurities such as propylene glycol are 0.2200%, and water is 0.1100%;

[0189] The weight flow ratio of the extractant 2 to the epoxy compound stream 3 is 0.25:1.0;

[0190] The operating pressure of the deweighting tower top is 60kPaG, and the operating temperature of the tower top is 47℃;

[0191] The operating temperature of the recovery tower top is 80℃, and the operating temperature of the tower bottom is 138.5℃;

[0192] The pressure of the kettle reboiler is 53 kPaG and the temperature is 142 °C;

[0193] The recovered extractant was treated by solid-liquid cyclone, and the removal rate of flocculent and fibrous impurities reached 99.0%, and the loss rate of the extractant EGME was 0.45%.

[0194] In this Example 5, the composition of the propylene oxide product obtained is shown in Table 10:

[0195] Table 10:

[0196] Components Quality composition water 0.0053％ Methanol 0.0176％ Acetaldehyde 0.0038％ acetone 0.0000％ Propionaldehyde 0.0020％ PO 99.2704％ Methyl formate 0.5279％ C5~C6 hydrocarbons 0.1730％ Ethylbenzene or cumene and other heavy components 0.0000％

[0197] In this embodiment, the removal rate of acetaldehyde reaches 95.64%, the removal rate of propionaldehyde reaches 98.75%, and the removal rate of acetone reaches 100%.

[0198] [Example 6]

[0199] The process of Example 1 was repeated, except that:

[0200] In this Example 6, the composition of the epoxy compound stream to be treated is shown in Table 11:

[0201] Table 11:

[0202]

[0203]

[0204] The mass composition of ethylene glycol monomethyl ether in the extractant stream 2 is 99.8000%, heavy impurities such as propylene glycol are 0.1000%, and water is 0.1000%;

[0205] The weight flow ratio of the extractant 2 to the epoxy compound stream 3 is 0.23:1.0;

[0206] The operating pressure of the deweighting tower top is 140kPaG, and the operating temperature of the tower top is 62℃;

[0207] The operating temperature of the recovery tower top is 96°C, and the operating temperature of the tower bottom is 152°C;

[0208] The pressure of the kettle reboiler is 122 kPaG and the temperature is 155 °C;

[0209] The recovered extractant was treated with solid-liquid cyclone, and the removal rate of flocculent and fibrous impurities reached 99.2%, and the loss rate of extractant EGME was 0.43%.

[0210] In this Example 5, the composition of the propylene oxide product obtained is shown in Table 12:

[0211] Table 12:

[0212] Components Quality composition water 0.0038％ Methanol 0.0117％ Acetaldehyde 0.0023％ acetone 0.0000％ Propionaldehyde 0.0021％ PO 99.3370％ Methyl formate 0.5286％ C5~C6 hydrocarbons 0.1145％ Ethylbenzene or cumene and other heavy components 0.0000％

[0213] In this embodiment, the removal rate of acetaldehyde reaches 96.04%, the removal rate of propionaldehyde reaches 98.19%, and the removal rate of acetone reaches 100%.

[0214] [Example 7]

[0215] The process of Example 3 was repeated, and the raw material feed was the same as in Example 3, except that:

[0216] use Figure 2 In the system shown, the deweighting tower is filled with fillers and catalysts, wherein the fillers are regular metal corrugations, the catalyst is solid acid (VO)2P207, and the solid acid catalyst is encapsulated in the regular corrugated fillers, and the filling amount is 15% of the porosity of the corrugated fillers.

[0217] The mass composition of ethylene glycol monomethyl ether in the extractant stream 2 is 99.8100%, heavy impurities such as propylene glycol are 0.0900%, and water is 0.1000%;

[0218] The weight flow ratio of the extractant 2 to the epoxy compound stream 3 is 0.30:1.0;

[0219] The operating pressure of the deweighting tower top is 120kPaG, and the operating temperature of the tower top is 59℃;

[0220] The operating temperature of the recovery tower top is 108℃, and the operating temperature of the tower bottom is 166℃;

[0221] The pressure of the kettle reboiler is 220 kPaG and the temperature is 170 °C;

[0222] The recovered extractant was treated with solid-liquid cyclone, and the removal rate of flocculent and fibrous impurities reached 99.2%, and the loss rate of extractant EGME was 0.42%;

[0223] In this Example 7, the composition of the propylene oxide product obtained is shown in Table 13:

[0224] Table 13:

[0225] Components Quality composition water 0.0040％ Methanol 0.0006％ Acetaldehyde 0.0006％ acetone 0.0000％ Propionaldehyde 0.0003％ PO 99.3371％ Methyl formate 0.5286％ C5~C6 hydrocarbons 0.1288％ Ethylbenzene or cumene and other heavy components 0.0000％

[0226] In this embodiment, the removal rate of acetaldehyde reaches 99.31%, the removal rate of propionaldehyde reaches 99.81%, and the removal rate of acetone reaches 100%.

[0227] [Comparative Example 1]

[0228] The process of Example 7 was repeated, except that glycerol was used as the extraction agent.

[0229] The inventors have found through experiments that propylene oxide system extractant is not suitable, because its boiling point is as high as 290°C, which will lead to polymerization of propylene oxide to form propylene oxide polymer, resulting in a significant increase in the loss rate of propylene oxide.

[0230] [Comparative Example 2]

[0231] The process of Example 7 was repeated, except that no side-line acetone was taken out in the deweighting tower.

[0232] The results are shown in Table 14:

[0233] Table 14

[0234] Components Quality composition water 0.0038％ Methanol 0.0008％ Acetaldehyde 0.0010％ acetone 0.0005％ Propionaldehyde 0.0008％ PO 99.3358％ Methyl formate 0.5282％ C5~C6 hydrocarbons 0.1284％ Ethylbenzene or cumene and other heavy components 0.0000％

[0235] In this embodiment, the removal rate of acetaldehyde reaches 98.85%, the removal rate of propionaldehyde reaches 99.50%, the removal rate of acetone reaches 99.04%, and the separation energy consumption increases by about 5%.

[0236] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for purifying an epoxy compound stream, comprising: (1) introducing the extractant and the epoxy compound stream from the upper and lower parts of the de-weighting tower respectively, and after treatment, taking out the epoxy compound product at the top of the de-weighting tower, taking out the heavy component material I at the bottom, and taking out the ketone compound material at the side line at the lower part of the de-weighting tower; The epoxy compound stream contains epoxy compounds, ketone compounds, aldehyde compounds, optional water, optional alcohol compounds, optional ester compounds, optional hydrocarbon compounds and optional heavy components, wherein the heavy components are ethylbenzene and / or isopropylbenzene; the extractant is selected from at least one of ethylene glycol methyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol tert-butyl ether and propylene glycol butyl ether; in step (1), the weight ratio of the extractant to the epoxy compound stream is (0.05-0.80):1; (2) introducing the heavy component material I into a recovery tower, and after treatment, extracting a light component material I containing ketone compounds, aldehyde compounds, optional water and optional methanol from the top of the tower, and obtaining a recovered extractant at the bottom of the tower; vaporizing the material drawn out from the bottom of the recovery tower to obtain a heavy component material II and a light component material II, respectively, the heavy component material II is discharged, and the light component material II is recycled back into the recovery tower; (3) performing solid-liquid separation on the extractant recovered in step (2) to obtain a purified circulating extractant, which is recycled back to step (1); wherein, after step (3) and before step (1), fresh extracting agent is optionally supplemented; The operating pressure of the deweighting tower is 20~140kPaG, and the operating temperature of the top of the deweighting tower is 40~60℃; the top temperature of the recovery tower is 50~110℃, and the bottom temperature is 120~185℃; the pressure of the vaporization treatment is 30~350kPaG, and the temperature is 125~200℃.

2. The purification method according to claim 1, characterized in that Step (3) is performed as follows: the recovered extractant is subjected to cooling treatment and solid-liquid separation in sequence to obtain a purified circulating extractant, and the purified circulating extractant and the replenished fresh extractant are separately or mixedly introduced into the deweighting tower described in step 1 to achieve recycling of the extractant.

3. The purification method according to claim 1, characterized in that In the epoxy compound logistics, the epoxy compound is selected from C3~C6 epoxy compounds, and / or the aldehyde compound is selected from at least one of formaldehyde, acetaldehyde and propionaldehyde, and / or the ketone compound is acetone, and / or the alcohol compound is C1~C3 alcohol.

4. The purification method according to claim 3, characterized in that Based on 100% of the total weight of the epoxy compound flow, the content of ketone compounds is 0.001-2%, the content of aldehyde compounds is 0.001-2%, the content of water is 0-8%, the content of alcohol compounds is 0-3%, the content of ester compounds is 0-2%, the content of hydrocarbon compounds is 0-1%, and the recombinant fraction is 0-0.5%.

5. The purification method according to claim 1, characterized in that The deweighting tower is optionally filled with a catalyst and / or a filler.

6. The purification method according to claim 5, characterized in that The catalyst is selected from at least one of a solid acid catalyst, an alkaline catalyst and an acid-base catalyst; and / or the filler is selected from at least one of a perforated plate corrugation, a wire mesh corrugation and a mesh corrugated filler.

7. The purification method according to claim 1, characterized in that In step (1), the weight ratio of the extractant to the epoxide compound stream is (0.10-0.45):

1.

8. The purification method according to claim 1, characterized in that In step (1), an acetone-rich material is taken from a side line below the epoxy compound feed stream.

9. The purification method according to claim 1, characterized in that The operating pressure of the deweighting tower is 40-120 kPaG; and / or, the operating temperature of the top of the deweighting tower is 45-55° C.; and / or, The top temperature of the recovery tower is 60-100°C, and the bottom temperature is 130-175°C; and / or, The pressure of the vaporization treatment is 50-250 kPaG; and / or the temperature is 135-180°C.

10. The purification method according to claim 1, characterized in that In step (3), the recovered extractant is cooled to 30-70°C; and / or, In step (3), solid-liquid cyclone is used for solid-liquid separation.

11. The purification method according to claim 1, characterized in that In step (3), the recovered extractant is cooled to 40-60°C.

12. A system for purifying an epoxy compound stream, the system comprising: De-weighting tower, used for extractive distillation to remove impurities; A recovery tower for recovering the extractant; and, A solid-liquid separation device for purifying the recovered extractant; An extractant inlet is provided at the upper part of the deweighting tower, and an inlet for materials to be processed is provided at the lower part; a product outlet is provided at the top of the deweighting tower, a heavy component outlet is provided at the bottom, and a side line production outlet is provided at the lower part; An inlet for materials to be recovered is arranged in the middle of the recovery tower, a light component outlet is arranged at the top, and an outlet for recovering extractant is arranged at the bottom; an extractant regenerator and at least one reboiler are arranged in the bottom of the recovery tower, wherein the extractant regenerator is used to vaporize the materials in the bottom of the tower; The bottom of the recovery tower is connected to the solid-liquid separation device; the solid-liquid separation device is connected to the extractant inlet of the deweighting tower, so as to circulate the purified extractant back to the deweighting tower.

13. The purification system according to claim 12, characterized in that The side line extraction outlet is located below the inlet of the material to be processed.

14. The purification system according to claim 12, characterized in that: The inlet of the material to be recycled is connected to the outlet of the heavy component of the deweighting tower.

15. The purification system according to claim 12, characterized in that: The reboiler is a forced circulation type reboiler, and the extractant regenerator is a kettle type reboiler.

16. The purification system according to any one of claims 12 to 15, characterized in that: A heat exchanger and / or a cooler is provided between the recovery tower and the solid-liquid separation device.

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