Epoxidation reaction system and epoxidation reaction method

Abstract

The present invention relates to the field of olefin epoxidation reaction, and discloses an epoxidation reaction system and an epoxidation reaction method. The system comprises: an epoxidation reactor for carrying out epoxidation reaction; an epoxidation reaction feed heat exchange unit for heating and / or cooling the epoxidation reaction feed; a liquid heat transfer medium circulation unit for controlling the temperature of the epoxidation reaction; a control unit for controlling the temperature, flow, liquid level and pressure during the epoxidation reaction; wherein the epoxidation reaction feed heat exchange unit is provided with a first temperature control system; and the liquid heat transfer medium circulation unit is provided with a second temperature control system. The epoxidation reaction system and the epoxidation reaction method provided by the present invention effectively realize the stable control of the temperature during the epoxidation reaction, prolong the time of the epoxidation reaction process, and the method of the present invention is easy to operate, which is conducive to application in large-scale industrial automated production.

Description

Technical Field

[0001] The invention relates to the field of olefin epoxidation reaction, and in particular to an epoxidation reaction system and an epoxidation reaction method. Background Art

[0002] Epichlorohydrin is an important basic organic chemical raw material and intermediate, widely used in the synthesis of epoxy resins, chlorohydrin rubber, medicines, pesticides, surfactants, plasticizers and other products. At present, the high-temperature chlorination of propylene is the main method for producing epichlorohydrin, with mature technology and flexible production process. However, since the high-temperature chlorination of propylene includes two steps of chlorohydrinization and saponification, there are serious environmental protection problems such as huge wastewater discharge and large waste residue discharge and difficult treatment. It is urgent to develop a new green production technology for epichlorohydrin that can significantly reduce the discharge of wastewater and waste residue.

[0003] In the presence of titanium silicon molecular sieve catalyst, epichlorohydrin is synthesized by direct epoxidation of 3-chloropropylene with hydrogen peroxide. Compared with the traditional high-temperature chlorination of propylene, the two-step chlorohydrinization and saponification reactions that produce a large amount of wastewater and waste residue are eliminated, thereby significantly reducing the discharge of wastewater and waste residue. It is a green and environmentally friendly new epichlorohydrin synthesis technology.

[0004] CN101747296A discloses a method for producing epichlorohydrin, in which, in the presence of a titanium silicon molecular sieve catalyst, an alkaline additive and a solvent, 3-chloropropylene is directly contacted with hydrogen peroxide in a fixed bed reactor to produce epichlorohydrin, significantly extending the catalyst's one-way life. CN112209902A discloses an olefin epoxidation method, in which a liquid mixture containing 3-chloropropylene, hydrogen peroxide, a solvent and an alkaline additive is contacted with a titanium silicon molecular sieve catalyst in a fixed bed reactor with a height-to-diameter ratio of 100-1000, 3-chloropropylene is epoxidized to produce epichlorohydrin, and the catalyst's one-way reaction time is greatly extended.

[0005] Because the direct epoxidation of 3-chloropropene is a strong exothermic reaction, if the heat is not discharged in time, it is easy to produce a temperature rise, which will not only increase the invalid decomposition rate of hydrogen peroxide and the danger of the reaction process, but also significantly accelerate the rate at which epichlorohydrin further reacts with the reaction solvent and water, thereby significantly reducing the selectivity of 3-chloropropene to generate epichlorohydrin, and will accelerate the deactivation rate of the catalyst, shortening the single-pass reaction time of the catalyst. Therefore, when using a fixed-bed reactor, in the process of producing epichlorohydrin by the direct epoxidation of 3-chloropropene, it is necessary to strictly control the temperature of the epoxidation reaction. In the prior art, both the manual method can be adopted to control the temperature of the epoxidation reaction, the method of the instrumental program temperature rise can also be adopted to control, or the method of computer automatic control is adopted to realize the regulation of the epoxidation reaction temperature, but manual temperature control is time-consuming and labor-intensive, and the steady control of the temperature cannot be guaranteed.

[0006] CN101747296A adjusts the temperature of the epoxidation reactor by an automatic constant temperature oil bath flowing through the reactor jacket, and CN112209902A adjusts the temperature of the epoxidation reactor by an automatic constant temperature water bath flowing through the reactor jacket. However, the above two temperature control methods only consider how to timely remove the reaction heat through the heat-conducting medium in the reactor jacket and achieve stable control of the temperature of the heat-conducting medium. Even if the temperature of the heat-conducting medium can be controlled very stably, the existing temperature control method still cannot well achieve stable control of the temperature of the epoxidation reactor because the influence of the epoxidation reaction feed temperature on the epoxidation reaction process is not considered. Summary of the invention

[0007] The purpose of the present invention is to overcome the problem that the reaction temperature is difficult to control during the olefin epoxidation reaction process in the prior art, and to provide an epoxidation reaction system and an epoxidation reaction method, which can achieve stable control of the epoxidation reaction temperature, thereby prolonging the time of the epoxidation reaction process.

[0008] In order to achieve the above object, the first aspect of the present invention provides an epoxidation reaction system, which comprises:

[0009] An epoxidation reactor, used for performing an epoxidation reaction;

[0010] An epoxidation reaction feed heat exchange unit, used for heating and / or cooling the epoxidation reaction feed;

[0011] Liquid heat transfer medium circulation unit, used to control the temperature of the epoxidation reaction;

[0012] A control unit for controlling temperature, flow, liquid level and pressure during the epoxidation reaction;

[0013] Wherein, the epoxidation reaction feed heat exchange unit is provided with a first temperature control system; and the liquid heat transfer medium circulation unit is provided with a second temperature control system.

[0014] A second aspect of the present invention provides a method for epoxidation reaction, the method comprising:

[0015] (1) providing an epoxidation reaction feed, wherein the epoxidation reaction feed contacts a catalyst in an epoxidation reactor to carry out an epoxidation reaction;

[0016] (2) During the epoxidation reaction, a liquid heat-conducting medium circulates in the jacket of the epoxidation reactor;

[0017] (3) controlling the temperature of the epoxidation reaction feed to be no higher than the temperature of the liquid heat transfer medium at the jacket inlet of the epoxidation reactor;

[0018] (4) detecting the temperature at the inlet and outlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat transfer medium at the inlet and outlet of the jacket of the epoxidation reactor, and adjusting the temperature of the epoxidation reaction feed and the temperature of the liquid heat transfer medium so that the difference between the temperature at the inlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat transfer medium at the inlet of the jacket of the epoxidation reactor is not higher than 10° C., and the temperature difference between the liquid material at the outlet of the inner tube or tube array of the epoxidation reactor and the liquid material at the inlet of the inner tube or tube array of the epoxidation reactor is not higher than 20° C.

[0019] Through the above technical scheme, the epoxidation reaction system and epoxidation reaction method provided by the present invention effectively realize the stable control of temperature during the epoxidation reaction process, prolong the time of the epoxidation reaction process, and the method of the present invention is easy to operate and is conducive to application in large-scale industrial automated production. DETAILED DESCRIPTION

[0020] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range 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 considered as specifically disclosed in this article.

[0021] A first aspect of the present invention provides an epoxidation reaction system, the system comprising:

[0022] An epoxidation reactor, used for performing an epoxidation reaction;

[0023] An epoxidation reaction feed heat exchange unit, used for heating and / or cooling the epoxidation reaction feed;

[0024] Liquid heat transfer medium circulation unit, used to control the temperature of the epoxidation reaction;

[0025] A control unit for controlling temperature, flow, liquid level and pressure during the epoxidation reaction;

[0026] Wherein, the epoxidation reaction feed heat exchange unit is provided with a first temperature control system; and the liquid heat transfer medium circulation unit is provided with a second temperature control system.

[0027] According to some embodiments of the present invention, preferably, the epoxidation reactor is a jacketed tubular fixed bed reactor and / or a shell-and-tube fixed bed reactor.

[0028] According to some embodiments of the present invention, preferably, the fixed bed reactor refers to a reactor in which the catalyst is present in the form of a fixed bed, and the reaction raw materials contact the catalyst bed during the flow process to achieve the epoxidation reaction of olefins and hydrogen peroxide.

[0029] According to some embodiments of the present invention, preferably, the jacketed tubular fixed bed reactor is provided with an inner tube, and the inner tube is used for carrying out the epoxidation reaction.

[0030] According to some embodiments of the present invention, preferably, the tube-in-tube fixed bed reactor is provided with tubes, and the tubes are used to carry out the epoxidation reaction.

[0031] According to some embodiments of the present invention, preferably, the inner tube and / or the tube array is filled with a catalyst, and more preferably, the catalyst is a titanium silicon molecular sieve catalyst.

[0032] According to some embodiments of the present invention, preferably, the liquid heat transfer medium circulation unit is communicated with the jacket of the epoxidation reactor so as to control the temperature of the epoxidation reaction by using the liquid heat transfer medium.

[0033] According to some embodiments of the present invention, preferably, after the epoxidation reaction feed is heated or cooled by the epoxidation reaction feed heat exchange unit, it is introduced from the inlet at the lower end of the epoxidation reactor, flows upward through the inner tube or tube array of the epoxidation reactor, contacts with the catalyst loaded inside the inner tube or tube array to carry out the epoxidation reaction, and then flows out from the outlet at the upper end of the epoxidation reactor, and at the same time, the epoxidation reaction flow exchanges heat with the liquid heat transfer medium circulating in the jacket through the reaction tube wall, thereby controlling the temperature of the epoxidation reaction. Preferably, the epoxidation reaction feed is delivered to the epoxidation reaction feed heat exchange unit by a delivery pump for heating or cooling, and the temperature of the epoxidation reaction feed is automatically controlled by a first temperature control system.

[0034] According to some embodiments of the present invention, preferably, the liquid heat-conducting medium circulation unit includes a circulation tank for storing the liquid heat-conducting medium, a circulation pump for conveying the liquid heat-conducting medium, a heater for heating the liquid heat-conducting medium, a cooler for cooling the liquid heat-conducting medium, a liquid flow control system for automatically controlling the circulation flow of the liquid heat-conducting medium, and a second temperature control system for automatically controlling the temperature of the liquid heat-conducting medium.

[0035] According to some embodiments of the present invention, preferably, the liquid heat-conducting medium stored in the circulation tank is heated or cooled, introduced from the inlet at the lower end of the jacket of the epoxidation reactor, flows upward in the jacket, and exchanges heat with the epoxidation reaction flow in the reactor through the reaction tube wall to control the temperature of the epoxidation reaction, and the liquid heat-conducting medium after heat exchange flows out from the outlet at the upper end of the jacket, and after cooling, circulates back to the circulation tank. Preferably, the liquid heat-conducting medium is transported to the jacket of the epoxidation reactor by a circulation pump.

[0036] According to some embodiments of the present invention, preferably, the epoxidation reaction feed heat exchange unit comprises a feed heater for heating the epoxidation reaction feed and a feed cooler for cooling the epoxidation reaction feed.

[0037] According to some embodiments of the present invention, preferably, the epoxidation reaction feed heat exchange unit further comprises a feed heat exchanger, and the feed heat exchanger is used to exchange heat between the feed of the epoxidation reactor and the liquid heat transfer medium flowing out of the jacket outlet of the epoxidation reactor.

[0038] According to some embodiments of the present invention, preferably, according to the logistics direction, the feed heat exchanger is arranged after the feed cooler.

[0039] According to some embodiments of the present invention, preferably, the control unit includes a DCS control system, and the DCS control system is used to receive signals of temperature, flow, liquid level and pressure from the epoxidation reaction process to achieve remote monitoring of the temperature, flow, liquid level and pressure in the epoxidation reaction process. Preferably, the control unit also includes a flow control system, a liquid level control system and a pressure control system. The DCS control system receives signals of temperature, flow, liquid level and pressure from the epoxidation reaction process through a first temperature control system, a second temperature control system, a flow control system, a liquid level control system and a pressure control system, and sends signals to the first temperature control system, the second temperature control system, the flow control system, the liquid level control system and the pressure control system according to the set control requirements, thereby achieving remote monitoring of the temperature, flow, liquid level and pressure in the epoxidation reaction process.

[0040] According to some embodiments of the present invention, preferably, the epoxidation reaction system further comprises a gas-liquid separation system for performing gas-liquid separation on the epoxidation reaction product and controlling the pressure at the outlet of the epoxidation reactor, and maintaining it by introducing an inert gas. Preferably, the inert gas is nitrogen, and the pressure of the epoxidation reaction system is maintained by nitrogen.

[0041] A second aspect of the present invention provides a method for epoxidation reaction, the method comprising:

[0042] (1) providing an epoxidation reaction feed, wherein the epoxidation reaction feed contacts a catalyst in an epoxidation reactor to carry out an epoxidation reaction;

[0043] (2) During the epoxidation reaction, a liquid heat-conducting medium circulates in the jacket of the epoxidation reactor;

[0044] (3) controlling the temperature of the epoxidation reaction feed to be no higher than the temperature of the liquid heat transfer medium at the jacket inlet of the epoxidation reactor;

[0045] (4) detecting the temperature at the inlet and outlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat transfer medium at the inlet and outlet of the jacket of the epoxidation reactor, and adjusting the temperature of the epoxidation reaction feed and the temperature of the liquid heat transfer medium so that the difference between the temperature at the inlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat transfer medium at the inlet of the jacket of the epoxidation reactor is not higher than 10° C., and the temperature difference between the liquid material at the outlet of the inner tube or tube array of the epoxidation reactor and the liquid material at the inlet of the inner tube or tube array of the epoxidation reactor is not higher than 20° C.

[0046] According to some embodiments of the present invention, the temperature of the epoxidation reaction feed is controlled not to be higher than the temperature of the liquid heat transfer medium at the jacket inlet of the epoxidation reactor. Preferably, the temperature difference between the epoxidation reaction feed and the liquid heat transfer medium at the jacket inlet of the epoxidation reactor is controlled to be 0-10°C.

[0047] According to some embodiments of the present invention, in order to effectively achieve stable temperature control during the epoxidation reaction and extend the time of the epoxidation reaction process, preferably, before the start of the epoxidation reaction, when the set starting temperature of the epoxidation reaction is higher than the temperature of the epoxidation reaction feed, the epoxidation reaction feed is heated so that the temperature of the epoxidation reaction feed is not higher than the set starting temperature of the epoxidation reaction and the difference with the set starting temperature of the epoxidation reaction is not higher than 10°C; when the set starting temperature of the epoxidation reaction is lower than the temperature of the epoxidation reaction feed, the epoxidation reaction feed is cooled so that the temperature of the epoxidation reaction feed is not higher than the set starting temperature of the epoxidation reaction and the difference with the set starting temperature of the epoxidation reaction is not higher than 10°C;

[0048] According to some embodiments of the present invention, in order to effectively achieve stable temperature control during the epoxidation reaction and extend the time of the epoxidation reaction process, preferably, during the epoxidation reaction, the temperature at the inlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat-conducting medium at the inlet of the jacket of the epoxidation reactor are detected. When the temperature at the inlet of the inner tube or tube array of the epoxidation reactor is higher than the temperature of the epoxidation feed and not higher than the temperature of the liquid heat-conducting medium at the inlet of the jacket of the epoxidation reactor, the epoxidation feed is heated so that the difference between the temperature at the inlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat-conducting medium at the inlet of the jacket of the epoxidation reactor is not higher than 10°C; when the temperature at the inlet of the inner tube or tube array of the epoxidation reactor is lower than the temperature of the epoxidation feed, the epoxidation feed is cooled so that the difference between the temperature at the inlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat-conducting medium at the inlet of the jacket of the epoxidation reactor is not higher than 10°C.

[0049] According to some embodiments of the present invention, preferably, the epoxidation reaction feed is heated using a heater, and the epoxidation reaction feed is cooled using a cooler.

[0050] According to some embodiments of the present invention, in order to effectively achieve stable temperature control during the epoxidation reaction and extend the time of the epoxidation reaction process, preferably, before the start of the epoxidation reaction, when the set starting temperature of the epoxidation reaction is higher than the temperature of the liquid heat-conducting medium at the jacket inlet of the epoxidation reactor, the liquid heat-conducting medium is heated so that the difference between the liquid heat-conducting medium and the set starting temperature of the epoxidation reaction is not higher than 5°C, more preferably not higher than 1°C; when the set starting temperature of the epoxidation reaction is lower than the temperature of the liquid heat-conducting medium at the jacket inlet of the epoxidation reactor, the liquid heat-conducting medium is cooled so that the difference between the liquid heat-conducting medium and the set starting temperature of the epoxidation reaction is not higher than 5°C, more preferably not higher than 1°C.

[0051] According to some embodiments of the present invention, in order to effectively achieve stable temperature control during the epoxidation reaction and extend the time of the epoxidation reaction process, preferably, during the epoxidation reaction, the temperature of the liquid heat-conducting medium at the jacket inlet and outlet of the epoxidation reactor is detected. When the temperature of the liquid heat-conducting medium at the jacket outlet of the epoxidation reactor is higher than the set epoxidation reaction temperature, the liquid heat-conducting medium is cooled so that the difference between the temperature of the liquid heat-conducting medium at the jacket inlet of the epoxidation reactor and the set epoxidation reaction temperature is not higher than 5°C, preferably not higher than 1°C.

[0052] According to some embodiments of the present invention, preferably, the liquid heat-conducting medium is heated by a heater, and the liquid heat-conducting medium is cooled by a cooler.

[0053] According to some embodiments of the present invention, preferably, the temperature difference between the liquid material at the outlet of the inner tube or tube array of the epoxidation reactor and the liquid material at the inlet of the inner tube or tube array of the epoxidation reactor is not higher than 20° C., preferably not higher than 10° C., and more preferably not higher than 5° C. The use of this preferred embodiment is more conducive to reducing the rate at which epichlorohydrin further reacts with the reaction solvent and water, improving the selectivity of 3-chloropropene to generate epichlorohydrin, reducing the rate of catalyst deactivation, and increasing the single-pass epoxidation reaction time of the catalyst.

[0054] According to some embodiments of the present invention, preferably, the average flow rate of the liquid heat-conducting medium in the jacket of the epoxidation reactor is 0.1-10 m / s, preferably 0.1-2 m / s, and more preferably 0.15-1 m / s. The average flow rate of the liquid heat-conducting medium in the jacket of the epoxidation reactor is controlled within the above range, which can ensure that the reaction heat released by the epoxidation reaction is taken away in time, effectively control the temperature rise of the epoxidation reaction, thereby inhibiting side reactions to improve the selectivity of epichlorohydrin and increase the single-pass epoxidation reaction time of the catalyst, and avoid a large increase in the energy consumption required for circulating the liquid heat-conducting medium when using an excessively high flow rate.

[0055] According to some embodiments of the present invention, preferably, as the epoxidation reaction temperature increases, the average flow rate of the liquid heat-conducting medium gradually increases, thereby gradually reducing the temperature rise of the epoxidation reaction, so that a higher epichlorohydrin selectivity and a longer single-pass epoxidation reaction time of the catalyst are obtained when the reaction temperature is high; more preferably, the average flow rate of the liquid heat-conducting medium increases from 0.1-0.3 m / s to 0.5-1 m / s.

[0056] According to some embodiments of the present invention, during the epoxidation reaction, in order to maintain the epoxidation reaction activity of the catalyst, the temperature of the epoxidation reaction needs to be gradually increased. Preferably, the temperature of the liquid heat-conducting medium gradually increases with the extension of the epoxidation reaction time. More preferably, the temperature of the liquid heat-conducting medium increases from 20-50°C to 55-85°C.

[0057] According to some embodiments of the present invention, preferably, the heating rate of the liquid heat-conducting medium is 0.002-0.2° C. / h, more preferably 0.005-0.1° C. / h.

[0058] According to some embodiments of the present invention, preferably, the heating rate of the liquid heat-conducting medium is on a downward trend. The heating rate of the liquid heat-conducting medium is on a downward trend means that the heating rate of the liquid heat-conducting medium at a later time is not greater than the heating rate of the liquid heat-conducting medium at an earlier time. In order to smoothly control the temperature of the epoxidation reaction and increase the single-pass epoxidation reaction time of the catalyst, preferably, the heating rate of the liquid heat-conducting medium is reduced from 0.03-0.1°C / h to 0.005-0.03°C / h.

[0059] According to some embodiments of the present invention, unless otherwise specified, the “gradually increase”, “gradually decrease” and “gradually rise” all represent the overall changing trend of the numerical value. When the starting value and the ending value are determined, it is sufficient to ensure that the overall trend shows an increase, decrease or increase.

[0060] According to some embodiments of the present invention, preferably, the liquid heat transfer medium is water and / or heat transfer oil, preferably water. Preferably, the heat transfer oil is selected from at least one of silicon-based heat transfer oil, alkylbenzene-type heat transfer oil, alkylnaphthalene-type heat transfer oil, alkylbiphenyl-type heat transfer oil and alkylbiphenyl ether-type heat transfer oil.

[0061] According to some embodiments of the present invention, in order to save resources and reduce production costs, preferably, the method further comprises: before step (1), exchanging heat between the liquid heat-conducting medium flowing out of the jacket outlet of the epoxidation reactor and the epoxidation reaction feed to heat the epoxidation reaction feed. Specifically, part or all of the liquid heat-conducting medium flowing out of the jacket outlet of the epoxidation reactor is exchanged with the epoxidation reaction feed through a feed heat exchanger.

[0062] According to some embodiments of the present invention, preferably, the epoxidation reaction comprises contacting a mixture comprising olefin, hydrogen peroxide and a solvent with a titanium silicalite catalyst.

[0063] According to some embodiments of the present invention, preferably, the olefin is selected from at least one of propylene, 3-chloropropylene, 1-butene, 1-pentene and 1-hexene, preferably 3-chloropropylene.

[0064] According to some embodiments of the present invention, preferably, the solvent is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, acetone, acetonitrile and propionitrile, preferably methanol.

[0065] According to some embodiments of the present invention, preferably, the hydrogen peroxide is a pure product and / or an aqueous solution of hydrogen peroxide. In order to improve economy and safety, preferably, the hydrogen peroxide is an aqueous solution of hydrogen peroxide, wherein the mass percentage of hydrogen peroxide is 5-90%, preferably 20-60%.

[0066] According to some embodiments of the present invention, preferably, the epoxidation reaction comprises contacting a mixture comprising 3-chloropropylene, hydrogen peroxide and methanol with a titanium silicalite catalyst.

[0067] According to some embodiments of the present invention, preferably, the starting temperature of the epoxidation reaction is 10-60°C, preferably 30-55°C.

[0068] According to some embodiments of the present invention, preferably, the conditions of the epoxidation reaction include: a temperature of 10-100° C., preferably 30-70° C.; and a pressure of 0.1-2 MPa, preferably 0.2-1 MPa.

[0069] According to some embodiments of the present invention, preferably, in the epoxidation reaction feed, the feed molar ratio of olefin to hydrogen peroxide is 1-10:1, preferably 1.5-6:1.

[0070] According to some embodiments of the present invention, preferably, in the epoxidation reaction feed, the feed mass ratio of the solvent to the olefin is 0.5-20:1, preferably 1-5:1.

[0071] According to some embodiments of the present invention, preferably, based on the mass of the titanium silicon molecular sieve catalyst, the feed mass hourly space velocity of hydrogen peroxide is 0.01-1h -1 , preferably 0.05-0.3h -1 .

[0072] According to a particularly preferred embodiment of the present invention, the epoxidation reaction method comprises:

[0073] (a) providing an epoxidation reaction feed, wherein the epoxidation reaction feed is contacted with a catalyst in an epoxidation reactor to carry out an epoxidation reaction;

[0074] (b) during the epoxidation reaction, a liquid heat-conducting medium circulates in the jacket of the epoxidation reactor; the average flow rate of the liquid heat-conducting medium is 0.1-10 m / s;

[0075] (c) controlling the temperature of the epoxidation reaction feed to be no higher than the set starting temperature of the epoxidation reaction and the difference between the temperature and the set starting temperature of the epoxidation reaction is no more than 10° C., and the difference between the temperature of the liquid heat transfer medium and the set starting temperature of the epoxidation reaction is no more than 5° C.; the starting temperature of the epoxidation reaction is 10-60° C.;

[0076] (d) detecting the temperature at the inlet and outlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat-conducting medium at the inlet and outlet of the jacket of the epoxidation reactor, and adjusting the temperature of the epoxidation reaction feed and the temperature of the liquid heat-conducting medium so that the difference between the temperature at the inlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat-conducting medium at the inlet of the jacket of the epoxidation reactor is not higher than 10° C., and the temperature difference between the liquid material at the outlet of the inner tube or tube array of the epoxidation reactor and the liquid material at the inlet of the inner tube or tube array of the epoxidation reactor is not higher than 20° C.

[0077] In the present invention, the temperature at the inlet of the inner tube or tube array of the epoxidation reactor is the temperature of the epoxidation reaction feed; the temperature at the outlet of the inner tube or tube array of the epoxidation reactor is the temperature of the liquid material at the outlet of the inner tube or tube array of the epoxidation reactor; the liquid material at the inlet of the inner tube or tube array of the epoxidation reactor is the epoxidation reaction feed; the liquid material at the outlet of the inner tube or tube array of the epoxidation reactor is the epoxidation reaction product.

[0078] The present invention will be described in detail below through examples.

[0079] In the following examples, the epoxidation reaction of 3-chloropropylene and hydrogen peroxide was carried out in a jacketed tubular fixed-bed reactor with an inner tube diameter of 24 mm, wherein the titanium silicalite catalyst used was produced by Sinopec Catalyst Branch, 3-chloropropylene was industrial chloropropylene with a 3-chloropropylene mass content of 99% produced by Sinopec Baling Petrochemical Co., Ltd., hydrogen peroxide was industrial hydrogen peroxide with a mass content of 27.5% produced by Sinopec Baling Petrochemical Co., Ltd., methanol was industrial methanol, and ammonia water was an analytically pure reagent.

[0080] The loading amount of titanium silicalite catalyst is 3.4L, the pressure of epoxidation reaction is 0.5MPa, the temperature of epoxidation reaction is 35.0-65.4℃; the feed molar ratio of 3-chloropropylene to hydrogen peroxide is 2.5:1, the feed mass ratio of methanol to 3-chloropropylene is 2.1:1, and the feed mass space velocity of hydrogen peroxide is 0.11-0.14h -1 .

[0081] Example 1

[0082] The starting temperature of the epoxidation reaction is 35°C, and the pressure at the reactor outlet is controlled at 0.50MPa by the gas-liquid separation system. Before the epoxidation reaction begins, the reaction system and the gas-liquid separation system are first filled with nitrogen and the pressure of the gas-liquid separation tank is controlled at 0.50MPa; then the circulating pump of the reactor jacket circulating water is turned on, and the average flow rate of the circulating water in the reactor jacket is controlled at 0.15m / s, so that the circulating water is transported from the circulating tank to the lower inlet of the epoxidation reactor jacket, flows upward in the jacket, and then flows out from the outlet at the upper end of the jacket and circulates back to the circulating tank, and then the circulating water heater is turned on to heat the water in the circulating tank from 21°C to 35°C and keep it constant.

[0083] When the epoxidation reaction starts, methanol, 3-chloropropylene, aqueous hydrogen peroxide solution and ammonia water stored in a raw material storage tank at room temperature (21° C.) are respectively fed into the epoxidation reaction feed heat exchange unit through respective delivery pumps according to the feed flow rate determined by the epoxidation reaction feed ratio, and the epoxidation reaction feed is heated from room temperature to 35° C. and sent to the inlet at the lower end of the epoxidation reactor, flows upward through the inner tube of the epoxidation reactor, contacts with the titanium silicon molecular sieve catalyst for epoxidation reaction, and then flows out from the outlet at the upper end of the epoxidation reactor. At the same time, the heat released by the epoxidation reaction is transferred to the circulating water in the jacket through the reaction tube wall. The circulating water flowing out from the outlet at the upper end of the jacket of the epoxidation reactor is cooled to 35° C. by a circulating water cooler and then circulated back to the circulating water circulation tank.

[0084] After the epoxidation reaction starts, the temperature of the circulating water in the circulation tank is first gradually increased from the starting temperature of the epoxidation reaction to 36°C at a heating rate of 0.0417°C / h. At the same time, the circulating water cooler and the heater are automatically adjusted by the DCS control system and the second temperature control system so that the difference between the actual temperature of the circulating water in the circulation tank and the set temperature does not exceed 0.3°C. The epoxidation reaction feed heater is adjusted by the DCS control system and the first temperature control system so that the difference between the temperature of the epoxidation reaction feed and the temperature of the circulating water at the reactor jacket inlet does not exceed 1°C, thereby making the temperature at the inlet of the inner tube of the epoxidation reactor and the circulating water at the reactor jacket inlet not exceed 1°C. The temperature difference of the circulating water at the inlet of the oxidation reactor jacket is not higher than 1°C; in the subsequent epoxidation reaction process, according to the result of the epoxidation reaction, the heating rate of the circulating water in the circulation tank and the average flow rate of the circulating water in the jacket of the epoxidation reactor are adjusted in time, and at the same time, through the DCS control system and the first temperature control system, the temperature difference between the epoxidation reaction feed and the temperature of the circulating water at the inlet of the jacket of the epoxidation reactor is not more than 1°C, and the temperature difference between the liquid material at the outlet of the inner tube of the epoxidation reactor and the liquid material at the inlet of the inner tube of the epoxidation reactor is not higher than 5°C. The above process is repeated until the epoxidation reaction process is terminated.

[0085] During the epoxidation reaction, the temperature of the circulating water, the heating rate of the circulating water, the average flow rate of the circulating water in the jacket, and the temperature difference between the inlet and outlet of the reactor vary with the epoxidation reaction time as shown in Table 1.

[0086] Table 1

[0087]

[0088]

[0089] Example 2

[0090] The method of Example 1 is followed, except that the hydrogen peroxide is industrial hydrogen peroxide with a mass content of 30.0% produced by Sinopec Baling Petrochemical Co., Ltd., the room temperature at the start of the epoxidation reaction is 29° C., and the temperature difference between the liquid material at the inner tube outlet of the epoxidation reactor and the liquid material at the inner tube inlet of the epoxidation reactor is not higher than 10° C. During the epoxidation reaction, the temperature of the circulating water, the heating rate of the circulating water, the average flow rate of the circulating water in the jacket, and the temperature difference between the inlet and outlet of the reactor as a function of the epoxidation reaction time are shown in Table 2.

[0091] Table 2

[0092]

[0093] Comparative Example 1

[0094] The method of Example 1 is followed, except that the epoxidation reactor is a medium-sized tube-in-tube fixed bed reactor comprising three tubes with a diameter of 20 mm, the loading amount of the titanium silicon molecular sieve catalyst is 7.2 L, the room temperature at the start of the epoxidation reaction is 28° C., and the epoxidation reaction feed is not heated by the epoxidation reaction feed heat exchange unit.

[0095] During the epoxidation reaction, the temperature of the circulating water, the heating rate of the circulating water, the average flow rate of the circulating water in the jacket, and the temperature difference between the inlet and outlet of the reactor vary with the epoxidation reaction time as shown in Table 3.

[0096] Table 3

[0097]

[0098] It can be seen from the above results that the epoxidation reaction system and epoxidation reaction method provided by the present invention can conveniently control the inlet and outlet temperature difference of the fixed bed epoxidation reactor within 10° C., thereby ensuring long-term continuous operation of the epoxidation reaction process.

[0099] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for epoxidation reaction, characterized in that: The method includes: (1) providing an epoxidation reaction feed, wherein the epoxidation reaction feed contacts a catalyst in an epoxidation reactor to carry out an epoxidation reaction; (2) During the epoxidation reaction, a liquid heat-conducting medium circulates in the jacket of the epoxidation reactor; (3) controlling the temperature of the epoxidation reaction feed to be no higher than the temperature of the liquid heat transfer medium at the jacket inlet of the epoxidation reactor; (4) detecting the temperature at the inlet and outlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat-conducting medium at the inlet and outlet of the jacket of the epoxidation reactor, and adjusting the temperature of the epoxidation reaction feed and the temperature of the liquid heat-conducting medium so that the difference between the temperature at the inlet of the inner tube or tube array of the epoxidation reactor and the temperature of the liquid heat-conducting medium at the inlet of the jacket of the epoxidation reactor is not higher than 10° C., and the temperature difference between the liquid material at the outlet of the inner tube or tube array of the epoxidation reactor and the liquid material at the inlet of the inner tube or tube array of the epoxidation reactor is not higher than 20° C.; Wherein, the heating rate of the liquid heat-conducting medium is 0.002-0.2°C / h; Wherein, the temperature of the liquid heat-conducting medium increases from 20-50°C to 55-85°C; Wherein, the heating rate of the liquid heat-conducting medium is reduced from 0.03-0.1°C / h to 0.005-0.03°C / h.

2. The method according to claim 1, wherein: The temperature difference between the epoxidation reaction feed and the temperature of the liquid heat transfer medium at the jacket inlet of the epoxidation reactor is 0-10°C.

3. The method according to claim 1, wherein: The temperature difference between the liquid material at the outlet of the inner tube or tube array of the epoxidation reactor and the liquid material at the inlet of the inner tube or tube array of the epoxidation reactor is not higher than 10°C.

4. The method according to claim 1, wherein: The average flow rate of the liquid heat-conducting medium in the jacket of the epoxidation reactor is 0.1-10 m / s.

5. The method according to claim 3, wherein: The temperature difference between the liquid material at the outlet of the inner tube or tube array of the epoxidation reactor and the liquid material at the inlet of the inner tube or tube array of the epoxidation reactor is not higher than 5°C.

6. The method according to claim 4, wherein: The average flow rate of the liquid heat-conducting medium in the jacket of the epoxidation reactor is 0.1-2 m / s.

7. The method according to claim 6, wherein: The average flow rate of the liquid heat-conducting medium in the jacket of the epoxidation reactor is 0.15-1 m / s.

8. The method according to claim 1, wherein: The liquid heat-conducting medium is water and / or heat-conducting oil.

9. The method according to claim 1, wherein: The heating rate of the liquid heat-conducting medium is 0.005-0.1°C / h.

10. The method according to claim 8, wherein: The liquid heat-conducting medium is water.

11. The method according to claim 1, wherein: The method further comprises: before step (1), exchanging heat between the liquid heat transfer medium flowing out of the jacket outlet of the epoxidation reactor and the epoxidation reaction feed.

12. The method according to any one of claims 1 to 11, wherein: The epoxidation reaction includes contacting a mixture comprising an olefin, hydrogen peroxide, and a solvent with a titanium silicate molecular sieve catalyst.

13. The method according to any one of claims 1 to 11, wherein: The starting temperature of the epoxidation reaction is 10-60°C.

14. The method according to any one of claims 1 to 11, wherein: The temperature of the epoxidation reaction is 10-100°C.

15. The method according to any one of claims 1 to 11, wherein: The pressure of the epoxidation reaction is 0.1-2 MPa.

16. The method according to claim 12, wherein: In the epoxidation reaction feed, the feed molar ratio of olefin to hydrogen peroxide is 1-10:1; the feed mass ratio of solvent to olefin is 0.5-20:1; based on the mass of the titanium silicon molecular sieve catalyst, the feed mass space velocity of hydrogen peroxide is 0.01-1h -1 .

17. The method according to claim 13, wherein: The starting temperature of the epoxidation reaction is 30-55°C.

18. The method according to claim 14, wherein: The temperature of the epoxidation reaction is 30-70°C.

19. The method according to claim 15, wherein: The pressure of the epoxidation reaction is 0.2-1 MPa.

20. The method according to claim 16, wherein: In the epoxidation reaction feed, the feed molar ratio of olefin to hydrogen peroxide is 1.5-6:

1.

21. The method according to claim 16, wherein: In the epoxidation reaction feed, the feed mass ratio of solvent to olefin is 1-5:

1.

22. The method according to claim 16, wherein: In the epoxidation reaction feed, based on the mass of the titanium silicon molecular sieve catalyst, the feed mass hourly space velocity of hydrogen peroxide is 0.05-0.3h -1 .

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