WO2020057235A1 - 一种连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法 - Google Patents

一种连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法 Download PDF

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WO2020057235A1
WO2020057235A1 PCT/CN2019/095187 CN2019095187W WO2020057235A1 WO 2020057235 A1 WO2020057235 A1 WO 2020057235A1 CN 2019095187 W CN2019095187 W CN 2019095187W WO 2020057235 A1 WO2020057235 A1 WO 2020057235A1
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reaction
liquid
trimethyl
cyclohexene
reactor
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French (fr)
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毛建拥
潘洪
严宏岳
乔胜超
韦良
胡柏剡
邱金倬
黄国东
于凯
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浙江新和成股份有限公司
山东新和成维生素有限公司
山东新和成药业有限公司
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Publication of WO2020057235A1 publication Critical patent/WO2020057235A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
    • C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
    • C07C45/33—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties
    • C07C45/34—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties in unsaturated compounds
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2601/00—Systems containing only non-condensed rings
    • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
    • C07C2601/16—Systems containing only non-condensed rings with a six-membered ring the ring being unsaturated

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  • the invention relates to the field of synthesis of 2,6,6-trimethyl-2-cyclohexene-1,4-dione, and in particular relates to a continuous oxidation of 3,5,5-trimethyl-3-cyclohexene Method for preparing 2,6,6-trimethyl-2-cyclohexene-1,4-dione from 1-one.
  • 2,6,6-trimethyl-2-cyclohexene-1,4-dione is an important chemical and pharmaceutical intermediate. It can be used as a flavoring agent or flavor in food additives, and can also be used in synthetic cosmetics. 2,6,6-trimethyl-2-cyclohexene-1,4-dione is also an important intermediate for the preparation of vitamins and carotenoids.
  • US4046813, CN1923782 and US4970347 describe the use of lead, vanadium, chromium, manganese, iron, cobalt and other acetylacetone complexes or their ionic liquid complexes as catalysts in the presence of organic bases to catalyze the oxidation of 3,5,5- Method for preparing 2,6,6-trimethyl-2-cyclohexene-1,4-dione from trimethyl-3-cyclohexene-1-one. Although this method has a high conversion rate, it is also easy at the same time. Isomerization of 3,5,5-trimethyl-3-cyclohexen-1-one to 3,5,5-trimethyl-2-cyclohexen-1-one, and the reaction is easy The formation of highly polymerized by-products reduces the reaction selectivity.
  • CN102329202 and CN1271031, CN101417935B a binary catalytic system composed of N-hydroxyphthalimide and a metal salt, or an ionic liquid of [C n min] [X] and a halide of a transition metal is described, Method for catalytically oxidizing 3,5,5-trimethyl-2-cyclohexene-1-one to obtain 2,6,6-trimethyl-2-cyclohexene-1,4-dione with high selectivity .
  • the reaction is performed in a vented reactor.
  • the method has simple synthesis route, mild reaction conditions, high reaction conversion rate and selectivity. However, catalyst post-treatment was difficult after the reaction was completed.
  • CN101182288 describes the oxidation of 3,5,5-trimethyl-3-cyclohexen-1-one to 2,6 using a transition metal salt supported on a porous inorganic support modified by a nitrogen-containing compound as a catalyst. , 6-Trimethyl-2-cyclohexene-1,4-dione. The method has mild reaction conditions, easy separation and control of the catalyst, and fewer by-products of the two clusters.
  • CN1923783 the heterogeneous catalytic oxidation of 2,6,6-trimethyl-2-cyclohexene-1,4-dione using a supported transition metal salt as a catalyst at -30-150 ° C is described. method.
  • the reaction activity and selectivity of the method are greatly improved.
  • the reaction conditions are mild, the di-cluster by-products are less, and the catalyst is easy to separate and control, which is beneficial to the catalyst reuse.
  • the reaction efficiency and selectivity are inferior to that of homogeneous catalytic oxidation.
  • the production unit includes a 3,5,5-trimethyl-2-cyclohexene-1-one isomerization reaction unit and a 3,5,5-trimethyl-3-cyclohexene-1-one oxidation reaction unit , Low boiling impurities / solvent distillation unit, high boiling compound distillation unit and 2,6,6-trimethyl-2-cyclohexene-1,4-dione distillation unit.
  • the oxidation reaction unit uses a mechanically stirred reaction kettle. This process combines isomerization and oxidation reactions, has high conversion and selectivity, and the device avoids poisoning and inactivation of oxidation catalysts.
  • the stirring reaction kettle contains agitators, which has certain restrictions on the sealing performance and is not suitable for high pressure reactions. There is also a reaction time in actual production. Long, there are problems such as tail gas formation and solvent entrainment loss.
  • Zhang Qin et al. (Zhejiang Chemical Industry, 2014, 5, 17-19) studied the oxidation reaction of the isomer 3,5,5-trimethyl-3-cyclohexen-1-one. Method, the amount of catalyst, temperature, and oxygen content were studied. The reaction has good mass and heat transfer effects, but because the yield is less than 80%, 2,6,6-trimethyl-2 was synthesized by this method. -Cyclohexene-1,4-dione fails to meet industrial requirements.
  • the present invention provides a continuous and efficient oxidation production of 2,6,6-trimethyl- New method for 2-cyclohexene-1,4-dione.
  • a method for continuously and efficiently preparing 2,6,6-trimethyl-2-cyclohexene-1,4-dione including:
  • reaction liquid (1) The raw material liquid and the oxygen-containing gas are reacted by spray mixing to obtain a reaction liquid;
  • reaction liquid is subjected to gas-liquid separation, and then the temperature of the liquid phase is adjusted, and then reacted with the oxygen-containing gas in a spray mixing manner to obtain a reaction liquid;
  • the oxygen-containing gas in step (2) is a gas phase or a newly prepared gas obtained by gas-liquid separation
  • step (3) repeating the process of step (2) until the reaction is completed to obtain a 2,6,6-trimethyl-2-cyclohexene-1,4-dione product liquid;
  • the raw material liquid includes a catalyst, a reaction raw material (3,5,5-trimethyl-2-cyclohexene-1-one), and a solvent.
  • the invention adopts the gas-liquid mixed spraying method, which makes the mixing effect of the reaction liquid, gas and catalyst greatly better than the mechanical stirring reactor, the bubbles are more uniformly dispersed, the contact is more sufficient, and the ideal mass transfer effect is achieved. From the reaction process point of view, the reaction speed There is a significant improvement.
  • the spray mixing is performed in a two-stage spray reactor, and the reaction conditions and residence time in the first-stage reactor are controlled until the conversion reaches 85% -90%, and then the reaction is transferred to the second-stage reactor for reaction;
  • reaction conditions and residence time in the second-stage reactor were controlled until the conversion reached 99.5%, and the reaction was judged to be complete.
  • the reaction is performed under conditions of continuous steady state operation
  • the feed inlet of the first-stage reactor is continuously replenished with the raw material liquid and the oxygen-containing gas. After the reaction, gas-liquid separation is performed.
  • the gas phase returns to the feed inlet of the first-stage reactor for circulation. A part of the liquid phase returns to the first-stage after cooling.
  • the feed port of the reactor circulates, and the other part enters the feed port of the second-stage reactor after the temperature is lowered;
  • Oxygen-containing gas is replenished at the feed port of the second-stage reaction liquid. After the reaction, gas-liquid separation is performed. The gas phase is returned to the feed port of the second-stage reactor for circulation. A part of the liquid phase is returned to the feed of the second-stage reactor after cooling. The material port circulates, and the other part is continuously output as the product liquid.
  • the residence time of the reaction solution in the first set of reactors is 5-6 hours; the residence time in the second set of reactors is 3-4 hours.
  • the liquid velocity at the exit of the reactor ejector is 5-15 m / s, preferably 8-12 m / s.
  • an external column-type heat exchanger is used to reduce the temperature of the separated liquid phase, and the temperature reduction range is 10-30 ° C, preferably 15-20 ° C; the liquid temperature after the temperature decrease is 25-50 ° C, preferably It is 30 to 45 ° C.
  • a cooling jacket is provided on the surface of the spray reactor.
  • the jacket and the external displacement heat exchanger are used to quickly transfer the heat generated by the oxidation reaction, ensure accurate control of the reaction temperature, and reduce the occurrence of side reactions.
  • an oxygen content tester is provided in the spray reactor;
  • the oxygen content (the oxygen content here refers to the volume content) in the jet reactor is 3-16%, preferably 6-12%.
  • the reaction is a pressurized reaction
  • the reactor pressure is 0.3-1.5 MPa, preferably 0.6-1.2 MPa.
  • the catalyst is a metal complex, wherein the metal cation is one or two of iron, cobalt, nickel, copper, zinc, and manganese, and the ligand is one of acetylacetone, Schiff base, and porphyrin. ;
  • the solvent is one or two of ethylenediamine, triethylamine, tripropylamine, and pyridine.
  • the liquid holding capacity in the reactor is 30-80%, preferably 40% -60%.
  • the present invention adopts a jet loop reaction method, and the gas-liquid mass transfer efficiency is greatly improved compared with the traditional stirred reactor, the reaction time is greatly reduced, and the reaction efficiency is significantly improved.
  • the temperature of the reaction solution can be accurately controlled by using a jacket and an external exothermic method.
  • the oxygen concentration is increased by pressurization, which ensures the matching of the reaction temperature and concentration, can limit the occurrence of side reactions, and is beneficial to improve Reaction selectivity.
  • the present invention uses two sets of jet loop reactors in series to control different reaction conditions in the two reactors in combination with different reaction states, compared to 2,6,6- Trimethyl-2-cyclohexene-1,4-dione was synthesized using other reactors to achieve a continuous reaction.
  • the total reaction residence time is shortened to less than 10 hours, the reaction conversion rate reaches more than 99.5%, and the reaction selectivity reaches more than 96%, which greatly improves the reaction efficiency and yield, and realizes exhaust gas through internal circulation of oxygen and external supplementation.
  • Zero emissions is a green and environmentally friendly process with the prospect of industrial application.
  • FIG. 1 is a schematic diagram of a reaction device of 2,6,6-trimethyl-2-cyclohexene-1,4-dione according to the present invention.
  • 1 jet reactor
  • 2 circulation pump
  • 3 change Heater
  • 4 thermometer
  • 5 ejector
  • 6 gas circulation pipe
  • 7 oxygen content meter
  • 8 pressure gauge
  • 9 Y-type filter
  • V-1 to 21 valve different types
  • I- 1 to 2 flow meter.
  • the reaction device of the present invention includes two sets of jet loop reactor systems connected in series.
  • Each jet loop reactor system includes a jet reactor 1, a circulation pump 2 and a tube-and-tube heat exchanger 3 connected in sequence.
  • the reaction liquid can be circulated inside the jet loop reactor system, or it can be reacted by the first jet loop reactor.
  • the reactor system flows into the second jet loop reactor system, which is controlled by the corresponding valve.
  • the spray reactor includes a feed port, a sprayer 5 in communication with the feed port, and a discharge port.
  • the feed port passes the reaction material into the ejector.
  • the reaction material includes fresh raw material liquid, fresh oxygen-containing gas, and circulating reaction liquid and circulating oxygen-containing gas.
  • the fresh raw material liquid is composed of the reaction raw material, the catalyst, and the solvent; fresh
  • the oxygen-containing gas is a mixture of oxygen and nitrogen, and the specific ratio is configured according to needs.
  • the ejector sprays the reaction material into the reactor, and a reaction occurs during the ejection process. After entering the ejector reactor, the material undergoes gas-liquid separation, and the liquid is output from the lower discharge port.
  • the output liquid can be returned to the spray reactor of the current stage for reaction as a circulating reaction liquid, or output to the spray reactor of the next stage or discharged as a product liquid.
  • the circulating pump and the tube-and-tube heat exchanger can reduce the temperature of the liquid that needs to be circulated once to avoid the occurrence of side reactions caused by high temperature.
  • the temperature drop range is generally 10-30 ° C.
  • At the exit of the tube-and-tube heat exchanger There is a thermometer 4.
  • gas circulation pipe 6 on the upper part of the jet reactor, which connects the upper space of the jet reactor and the feed port, and re-transports the oxygen-containing gas (from gas-liquid separation) in the upper space to the feed port for reaction.
  • the gas circulation pipe is provided with an oxygen content meter 7 for monitoring the oxygen content of the oxygen-containing gas used in the circulation.
  • the spray reactor is provided with a cooling jacket for passing cooling water; at the same time, in order to monitor the pressure of the reactor, a pressure gauge is provided on the spray reactor.
  • the catalyst iron acetylacetonate
  • the solvent triethylamine
  • the reaction raw material 3,5,5-trimethyl-3-cyclohexene-1- Ketone mixed liquid (mass ratio of 0.02: 2: 1) enters the two-tank series reaction system, and the reaction is controlled until the completion of the reaction conditions and the residence time.
  • the oxidation reaction liquid is continuously discharged from the discharge port, and samples are taken for detection.
  • the specific reaction parameters are as follows:
  • Reactor 1 oxygen content: 8%; pressure: 0.5MPA; liquid temperature in the reactor: 45 ° C; pump outlet temperature: 30 ° C; pump flow rate: 1m / s (equivalent to spray speed of 10m / s); residence time : 5h.
  • Reactor 2 6% oxygen content, pressure: 0.4MPA, reactor liquid temperature: 60 ° C; pump outlet temperature: 45 ° C; pump flow rate: 1.2m / s (equivalent to injection speed of 12m / s) stay Time: 4h.

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Abstract

公开了一种连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，包括：(1)将原料液与含氧气体以喷射混合的方式进行反应，得到反应液；(2)将反应液进行气液分离，然后调节液相的温度，再与含氧气体以喷射混合的方式进行反应得到反应液；步骤(2)中的含氧气体为气液分离得到的气相或者新配制的气体；(3)重复步骤(2)的过程至反应完全，得到2,6,6-三甲基-2-环己烯-1,4-二酮产品液。所述的原料液包含催化剂、反应原料和溶剂。其通过气液混合喷射，使得反应液和气体以及催化剂混合效果大大优于机械搅拌反应器，气泡分散更均匀，接触更充分，达到理想的传质效果，提高了反应速度。

Description

一种连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法 技术领域
本发明涉及2,6,6-三甲基-2-环己烯-1,4-二酮的合成领域，具体涉及一种连续氧化3,5,5-三甲基-3-环已烯-1-酮制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法。
背景技术
2,6,6-三甲基-2-环己烯-1,4-二酮是一种重要的化工医药中间体，可用作食品添加剂中的调味剂或香料，也可用于合成化妆品，2,6,6-三甲基-2-环己烯-1,4-二酮还是制备维生素和类胡萝卜素的重要中间体。
由于2,6,6-三甲基-2-环己烯-1,4-二酮在化工医药等领域中的重要性，长期以来，将3,5,5-三甲基-2-环已烯-1-酮或者3,5,5-三甲基-3-环已烯-1-酮氧化成2,6,6-三甲基-2-环己烯-1,4-二酮一直是化学化工领域研究的一个热点，特别是对于3,5,5-三甲基-3-环已烯-1-酮的氧化，目前已经报道的专利和文献很多。总的来说，目前对3,5,5-三甲基-3-环已烯-1-酮氧化的文献和专利大多都集中在溶剂或催化剂的筛选或改进上。如：
在US4046813、CN1923782和US4970347中描述了在有机碱存在下，使用铅、钒、铬、锰、铁、钴等的乙酰丙酮配合物或者其离子液体复合物为催化剂，催化氧化3,5,5-三甲基-3-环已烯-1-酮制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，该方法虽然转化率高，但同时还容易使3,5,5-三甲基-3-环已烯-1-酮向3,5,5-三甲基-2-环已烯-1-酮发生异构化，且反应中又容易形成高聚的副产物，所以使得反应选择性下降。
在US6297404、US6300521、CN1865210、CN100999453、US6166261和CN 1281844中，描述了在DMF或DMA以及三丙胺等有机碱存在下，使用不同类型席夫碱催化氧化3,5,5-三甲基-3-环已烯-1-酮制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，该方法一个最大的缺点是反应容易产生3,5,5-三甲基-环己-2-烯-4-羟基-1-酮，2,2,6-三甲基环己烷-1,4-二酮等副产物，由于这些副产物分子量以及性质等各方面与产物相似，其与2,6,6-三 甲基-2-环己烯-1,4-二酮的分离相当困难。
在US4898985中，描述了一种在三乙胺和乙二醇二甲醚存在下，使用铁、钴、酮、锰的卟啉或酞菁配合物为催化剂，催化氧化3,5,5-三甲基-3-环已烯-1-酮制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，该方法虽然具有很高的收率，但卟啉类的过渡金属催化剂相当昂贵，且在反应中还容易被破坏，使得该工艺成本较高。此外乙二醇二甲醚组合三乙胺形成的碱性环境在氧化操作上非常危险，因为该混合物的燃点很低，所以出于安全原因，尽管该方法具有很高的收率，其必须在非常安全的预防措施下才可在工业规模上实施。
在CN102329202和CN1271031，CN101417935B中，描述了以N-羟基邻苯二甲酰亚胺和金属盐，或者[C nmin][X]的离子液体和过渡金属的卤化物组成的二元催化系统，催化氧化3,5,5-三甲基-2-环已烯-1-酮高选择性地得到2,6,6-三甲基-2-环己烯-1,4-二酮的方法。该反应在通气反应釜中进行。该方法合成路线简单，反应条件温和，反应转化率、选择性高。但是反应完成后催化剂后处理存在困难。
在CN101182288中，描述了以含氮化合物改性的活性多孔无机载体支载的过渡金属盐为催化剂，氧化3,5,5-三甲基-3-环已烯-1-酮生成2,6,6-三甲基-2-环己烯-1,4-二酮的方法。该方法反应条件温和，催化剂容易分离和控制，二聚类副产物较少。在CN1923783中，描述了以固载过渡金属盐为催化剂，在-30-150℃下异相催化氧化生成2,6,6-三甲基-2-环己烯-1,4-二酮的方法。该方法相比于一般异相催化剂反应活性和选择性大大提高，相比于均相催化剂，反应条件温和，二聚类副产物少，催化剂易于分离和控制，有利于催化剂再利用。但是采用非均相催化剂，反应效率和选择性都不如均相催化氧化。
在US6410797中，描述了一种生产2,6,6-三甲基-2-环己烯-1,4-二酮及其衍生物的方法及一种搅拌反应釜装置。该方法在有机羧酸存在的溶剂中，以N,N'-二亚水杨基二胺的过渡金属配合物为催化剂，环状碱为助催化剂，催化氧化3,5,5-三甲基-3-环已烯-1-酮生成2,6,6-三甲基-2-环己烯-1,4-二酮。该生产装置包含搅拌反应单元及分离纯化单元。在US6346651中，描述了一种2,6,6-三甲基-2-环己烯-1,4-二酮的生产工艺及装置。该生产装置包含3,5,5-三甲基-2-环已烯-1-酮异构反应单元，3,5,5-三甲基-3-环 已烯-1-酮氧化反应单元，低沸杂质/溶剂精馏单元，高沸化合物精馏单元及2,6,6-三甲基-2-环己烯-1,4-二酮精馏单元。氧化反应单元采用机械搅拌反应釜。该工艺将异构反应和氧化反应联合在一起，具有高的转化率和选择性，且该装置避免了氧化催化剂的中毒失活。
从上述专利总结的情况来看，这些专利主要是对3,5,5-三甲基-2-环已烯-1-酮氧化反应的催化剂或溶剂(助剂)进行的改进和优化，但是反应基本都是在机械搅拌反应釜中进行的。通过研究发现，对于2,6,6-三甲基-3-环己烯-1,4-二酮的氧化反应，除了催化剂及助剂的因素，传质和传热也对反应具有极其重要的影响。而采用传统的机械搅拌反应釜存在搅拌速度不快，对反应器内的气液混合程度有一定的限制，传质效果一般；同时对于传统的带搅拌器的反应釜，其内部换热面积受限，对氧化反应热量的移除不够及时，这是副反应产生的重要原因；再则搅拌反应釜内包含搅动件，对密封性能存在一定制约，不适合高压反应；在实际生产中还存在反应时间长，有尾气形成及溶剂夹带损失等问题。
张琴等(浙江化工，2014，5，17-19)研究了同分异构体3,5,5-三甲基-3-环已烯-1-酮的氧化反应，采用喷射氧化反应的方式，对催化剂用量、温度及氧含量等进行了研究，反应具备良好的传质和传热效果，但是因为收率低于80％，采用此方法合成2,6,6-三甲基-2-环己烯-1,4-二酮达不到产业化要求。
发明内容
针对上述氧化合成2,6,6-三甲基-2-环己烯-1,4-二酮存在的问题，本发明提供了一种连续高效氧化生产2,6,6-三甲基-2-环己烯-1,4-二酮的新方法。
本发明的技术方案如下：
一种连续高效制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，包括：
(1)将原料液与含氧气体以喷射混合的方式进行反应，得到反应液；
(2)将反应液进行气液分离，然后调节液相的温度，再与含氧气体以喷射混合的方式进行反应得到反应液；
步骤(2)中的含氧气体为气液分离得到的气相或者新配制的气体；
(3)重复步骤(2)的过程至反应完全，得到2,6,6-三甲基-2-环己烯 -1,4-二酮产品液；
所述的原料液包含催化剂、反应原料(3,5,5-三甲基-2-环已烯-1-酮)和溶剂。
针对3,5,5-三甲基-2-环已烯-1-酮的氧化，发现本反应是传质控制的，如何提高传质效果是反应的关键点之一。本发明通过气液混合喷射方式，使得反应液和气体以及催化剂混合效果大大优于机械搅拌反应器，气泡分散更均匀，接触更充分，达到理想的传质效果，从反应过程来看，反应速度有明显提升。
作为优选，喷射混合在两级串联的喷射反应器中进行，控制第一级反应器内反应条件和停留时间至转化率达到85％-90％时，转入第二级反应器进行反应；
控制第二级反应器内反应条件和停留时间至转化率达到99.5％以上，判定反应进行完全。
作为优选，反应在连续稳态操作的条件下进行；
在第一级反应器的进料口连续补充原料液与含氧气体，反应后进行气液分离，气相返回第一级反应器的进料口进行循环，液相一部分经过降温后返回第一级反应器的进料口循环，另一部分降温后进入第二级反应器的进料口；
在第二级反应液的进料口补充含氧气体，反应后进行气液分离，气相返回第二级反应器的进料口进行循环，液相一部分经过降温后返回第二级反应器的进料口循环，另一部分作为产品液连续输出。
作为优选，反应液在第一套反应器内停留时间为5-6h；在第二套反应器内停留时间为3-4h。
作为优选，所述反应器喷射器出口液体流速为5-15m/s，优选为8-12m/s。
由于3,5,5-三甲基-2-环已烯-1-酮反应位点多，且氧化过程是放热反应，所以在反应中控制氧含量以及控制反应速度，确保反应活化过程与氧分子结合过程相匹配是反应收率提升的关键。本发明人发现反应速度过快，活化氧浓度偏低是副产物生成的主要原因，控制反应温度和氧气压力对反应影响较大。
作为优选，采用外置列管式换热器对分离出的液相进行降温处理，降 温幅度为10-30℃，优选为15-20℃；降温后的液相温度为25～50℃，优选为30～45℃。
作为优选，喷射反应器的表面设置冷却夹套，此时，通过夹套加外置换热器，使得氧化反应产生的热快速转移，保证反应温度精准控制，减少了副反应的发生。
作为优选，喷射反应器内设有氧含量测试仪；
喷射反应器内的氧含量(此处的氧含量指的是体积含量)为3-16％，优选为6-12％。
作为优选，所述反应是加压反应，反应器压力为0.3-1.5MPa，优选0.6-1.2MPa。
作为优选，所述催化剂为金属配合物，其中金属阳离子为铁、钴、镍、铜、锌、锰中的一种或两种，配体为乙酰丙酮、席夫碱、卟啉中的一种；
所述溶剂为乙二胺、三乙胺、三丙胺、吡啶中的一种或两种。
作为优选，反应器内持液量为30-80％，优选40％-60％。
同现有技术相比，本发明的有益效果体现在：
(1)本发明采用喷射环流反应方式，气液传质效率相比于传统搅拌式反应器大幅度提升，反应时间大幅度减少，反应效率明显提升。
(2)本发明采用夹套加外置放热的方式可以精确的控制反应液温度，同时通过加压提升氧浓度，确保了反应温度和浓度的匹配，可以限制副反应的发生，有利于提高反应选择性。
(3)针对本反应不同底物浓度下速度差别大，本发明通过两套喷射环流反应器串联，结合不同的反应状态控制两反应器内不同的反应条件，相比于2,6,6-三甲基-2-环己烯-1,4-二酮合成采用其他的反应器形式，实现了连续反应。总反应停留时间缩短到10小时以内，反应转化率达到99.5％以上，反应选择性达到96％以上，大幅度提升了反应效率和收率，并且通过氧气内部循环，外部补充的方式，实现了尾气零排放，是绿色环保的工艺，具备工业化应用的前景。
附图说明
图1为本发明的2,6,6-三甲基-2-环己烯-1,4-二酮的反应装置示意图，图中：1：喷射反应器、2：循环泵、3：换热器、4：温度表、5：喷射器、 6：气体循环管、7：氧含量仪、8：压力表、9：Y型过滤器、V-1～21阀门(不同类型)、I-1～2：流量计。
具体实施方式
由图1所示的反应装置示意图可知，本发明的反应装置包括两套以串联方式相连接的喷射环流反应器系统。每个喷射环流反应器系统包括依次连接的喷射反应器1、循环泵2和列管式换热器3，反应液可以在喷射环流反应器系统内部循环流动，也可以由第一个喷射环流反应器系统流入到第二个喷射环流反应器系统，具体由相应的阀门控制。
喷射反应器包括进料口、与进料口相连通的喷射器5、和出料口。进料口将反应物料通入喷射器，反应物料包括新鲜的原料液、新鲜的含氧气体以及循环的反应液和循环的含氧气体，新鲜的原料液由反应原料、催化剂和溶剂组成；新鲜的含氧气体由氧气和氮气混合而成，具体比例根据需要进行配置。喷射器将反应物料喷射到反应器内部，喷射过程中发生反应，进入喷射反应器内部后物料发生气液分离，液体从下部出料口输出。该输出液根据反应程度的不同，可以作为循环的反应液返回到本级喷射反应器进行反应，或者输出到下一级喷射反应器或者作为产品液出料。
循环泵和列管式换热器可以将需要进行循环反应的液体进行一次降温操作，以避免高温导致的副反应的发生，降温幅度一般为10～30℃，在列管式换热器的出口处设有温度计4。
同时，在喷射反应器上部还有气体循环管6，连接喷射反应器的上部空间和进料口，将上部空间的含氧气体(来自于气液分离)重新输送至进料口进行反应，在该气体循环管上设置有氧含量仪7，用来监测循环套用的含氧气体的氧含量。
为了进一步控制反应的温度，喷射反应器设有冷却夹套，用来通入冷却水；同时，为了监测反应器的压力，在喷射反应器上设有压力表。
下面结合具体实施例对本发明做进一步的描述。
实施例1：
根据示意图流程，在连续稳态操作的条件下，将含有催化剂(乙酰丙酮铁)，溶剂(三乙胺)和反应原料(3,5,5-三甲基-3-环已烯-1-酮)的混合 液(质量比为0.02:2:1)进入两釜串联反应系统，控制条件和停留时间进行反应直至完成，氧化反应液连续从出料口排出，取样进行检测。其中具体反应参数如下：
反应器1：氧含量：8％；压力：0.5MPA；反应器内液体温度：45℃；泵出口温度：30℃；泵流速：1m/s(相当于喷射速度为10m/s)；停留时间：5h。
反应器2：氧含量为6％，压力为：0.4MPA，反应器液体温度：60℃；泵出口温度：45℃；泵流速为：1.2m/s(相当于喷射速度为12m/s)停留时间：4h。
检测结果：釜1转化率：86.5％；选择性：97.3％；
釜2转化率：99.8％；选择性：96.4％
Figure PCTCN2019095187-appb-000001

Claims (10)

  1. 一种连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，其特征在于，包括：
    (1)将原料液与含氧气体以喷射混合的方式进行反应，得到反应液；
    (2)将反应液进行气液分离，然后调节液相的温度，再与含氧气体以喷射混合的方式进行反应得到反应液；
    步骤(2)中的含氧气体为气液分离得到的气相或者新配制的气体；
    (3)重复步骤(2)的过程至反应完全，得到2,6,6-三甲基-2-环己烯-1,4-二酮产品液；
    所述的原料液包含催化剂、反应原料和溶剂。
  2. 根据权利要求1所述的连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，其特征在于，喷射混合在两级串联的喷射反应器中进行，在第一级反应器中的转化率达到85％-90％时，转入第二级反应器继续进行反应。
  3. 根据权利要求2所述的连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，其特征在于，反应在连续稳态操作的条件下进行；
    在第一级反应器的进料口连续补充原料液与含氧气体，反应后进行气液分离，气相返回第一级反应器的进料口进行循环，液相一部分经过降温后返回第一级反应器的进料口循环，另一部分降温后进入第二级反应器的进料口；
    在第二级反应液的进料口补充含氧气体，反应后进行气液分离，气相返回第二级反应器的进料口进行循环，液相一部分经过降温后返回第二级反应器的进料口循环，另一部分作为产品液连续输出。
  4. 根据权利要求3所述的连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，其特征在于，所述反应器喷射器出口的液体流速为5-15m/s，优选为8-12m/s。
  5. 根据权利要求1～3任一项所述的连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，其特征在于，采用外置列管式换热器对分离出的液相进行降温处理，降温幅度为10-30℃，优选为15-20℃。
  6. 根据权利要求1～3任一项所述的连续高效氧化制备2,6,6-三甲基-2- 环己烯-1,4-二酮的方法，其特征在于，喷射反应器的表面设置冷却夹套。
  7. 根据权利要求1～3任一项所述的连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，其特征在于，喷射反应器内设有氧含量测试仪；
    喷射反应器内的氧含量为3-16％，优选为6-12％。
  8. 根据权利要求1～3任一项所述的连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，其特征在于，所述反应是加压反应，反应器压力为0.3-1.5MPa，优选0.6-1.2MPa。
  9. 根据权利要求1所述的连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，其特征在于，所述催化剂为金属配合物，其中金属阳离子为铁、钴、镍、铜、锌、锰中的一种或两种，配体为乙酰丙酮、席夫碱、卟啉中的一种；
    所述溶剂为乙二胺、三乙胺、三丙胺、吡啶中的一种或两种。
  10. 根据权利要求1～3任一项所述的连续高效氧化制备2,6,6-三甲基-2-环己烯-1,4-二酮的方法，其特征在于，反应器内持液量为30-80％，优选40％-60％。
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