阅读说明：本技术 一种环氧氯丙烷的制备方法 (Preparation method of epichlorohydrin ) 是由 王漫 于 2019-11-15 设计创作，主要内容包括：本发明公开了一种环氧氯丙烷的制备方法,其以氯丙烯和双氧水为原料,甲醇为溶剂,钛硅分子筛为催化剂,季铵盐为表面活性剂,通过固定床制备,包括如下步骤：a、将氯丙烯与季铵盐、甲醇按一定的比例混合均匀后,制备成混合液,备用；b、将双氧水与所述混合液通过计量泵同时打入固定床,反应空速为0.5h<Sup>-1</Sup>～25h<Sup>-1</Sup>。本发明的一种环氧氯丙烷的制备方法,其延长了钛硅分子筛在固定床中的使用寿命,从而延长催化剂的循环周期,提高生产效率；同时具有反应条件温度温和,副产物少,环氧氯丙烷选择性及收率高等优点。(The invention discloses a preparation method of epichlorohydrin, which takes chloropropene and hydrogen peroxide as raw materials, methanol as a solvent, a titanium silicalite molecular sieve as a catalyst and quaternary ammonium salt as a surfactant, and the method is prepared by a fixed bed, and comprises the following steps: a. mixing chloropropene, quaternary ammonium salt and methanol uniformly according to a certain proportion to prepare a mixed solution for later use; b. simultaneously pumping hydrogen peroxide and the mixed solution into a fixed bed through a metering pump, wherein the reaction airspeed is 0.5h ‑1 ～25h ‑1 . The preparation method of epichlorohydrin prolongs the service life of the titanium silicalite molecular sieve in the fixed bed, thereby prolonging the cycle period of the catalyst and improving the production efficiency; meanwhile, the method has the advantages of mild reaction condition temperature, few byproducts, high selectivity and yield of the epichlorohydrin and the like.)

1. A preparation method of epichlorohydrin takes chloropropene and hydrogen peroxide as raw materials, methanol as a solvent, a titanium silicalite molecular sieve as a catalyst, and quaternary ammonium salt as a surfactant, and comprises the following steps:

a. mixing chloropropene, quaternary ammonium salt and methanol uniformly to prepare a mixed solution for later use;

b. simultaneously pumping hydrogen peroxide and the mixed solution into a fixed bed through a metering pump, wherein the reaction airspeed is 0.5h^-1～25h^-1。

2. Process for the manufacture of epichlorohydrin according to claim 1, characterized in that: methanol in step a: quaternary ammonium salts: the chloropropene molar ratio is 4-20: 0.001-0.1: 1.

3. process for the manufacture of epichlorohydrin according to claim 2, characterized in that: in the step a, the quaternary ammonium salt is one or more of dodecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium bromide, didodecyl gamma-double ammonium bromide, N, N, N-trimethyl adamantyl ammonium bromide and N, N-dimethyl-N-ethyl adamantyl ammonium bromide.

4. Process for the manufacture of epichlorohydrin according to claim 3, characterized in that: the concentration of hydrogen peroxide in hydrogen peroxide is 10-90%.

5. Process for the manufacture of epichlorohydrin according to claim 4, characterized in that: the molar ratio of the hydrogen peroxide to the chloropropene is 0.2-5: 1.

6. process for the manufacture of epichlorohydrin according to any of claims 1 to 5, characterised in that: the system temperature in the fixed bed in the step b is 10-60 ℃.

7. Process for the manufacture of epichlorohydrin according to claim 4, characterized in that: and in the step b, the temperature of the system in the fixed bed is 15-35 ℃.

8. Process for the manufacture of epichlorohydrin according to claim 1, characterized in that: the titanium silicalite molecular sieve is one or more of a titanium silicalite molecular sieve with an MFI structure, a titanium silicalite molecular sieve with an MEL structure, a titanium silicalite molecular sieve with a BEA structure, a titanium silicalite molecular sieve with an MWW structure, a titanium silicalite molecular sieve with an MOR structure, a titanium silicalite molecular sieve with a TUN structure and a titanium silicalite molecular sieve with a two-dimensional hexagonal structure.

9. Process for the manufacture of epichlorohydrin according to claim 1, characterized in that: the titanium-silicon molecular sieve is of an MFI structure, crystal grains are of a hollow structure, the radial length of a cavity part of the hollow structure is 5-300 nanometers, and a hysteresis ring exists between an adsorption isotherm and a desorption isotherm of low-temperature nitrogen adsorption of the titanium-silicon molecular sieve.

Technical Field

The invention relates to the technical field of preparation of epoxy chloropropane, in particular to a preparation method of epoxy chloropropane.

Background

Epichlorohydrin is an important organic chemical raw material and is widely applied to industries such as medicine, fine chemical industry, petrochemical industry and the like. The current industrial production method of epichlorohydrin mainly comprises the following steps: the propylene process is classified into a chlorohydrin process and a direct epoxidation process.

The propylene high-temperature chlorination method is also called chloropropene method, and comprises three steps of propylene high-temperature chlorination, chloropropene hypochlorination and dichloropropanol saponification to generate epoxy chloropropane, and the saponified crude epoxy chloropropane is distilled to obtain an epoxy chloropropane finished product; the method is the main method for producing epichlorohydrin in the world at present, and the production process is mature. The allyl acetate method is also called allyl alcohol method, and consists of four reaction units, namely, propylene catalytic synthesis of allyl acetate, hydrolysis of the allyl acetate to prepare allyl alcohol, chlorination synthesis of dichloropropanol by the allyl alcohol and saponification of dichloropropanol to generate epichlorohydrin; the method avoids high-temperature chlorination, and has the advantages of mild reaction conditions, easy control, few byproducts and the like. The glycerin chlorination saponification method consists of two steps of hydrochlorination and saponification, and comprises four procedures of hydrochlorination of glycerin, separation of dichloropropanol, saponification of dichloropropanol and refining of epichlorohydrin; the method has the advantages of simple process, short flow, renewable raw materials and the like.

The processes generate a large amount of salt-containing wastewater, the environmental pollution is serious, the sustainable development requirement of ecological environment is not met, and the development of a new energy-saving environment-friendly green process is a necessary trend. At present, the method for preparing epoxy chloropropane by directly epoxidizing chloropropene with hydrogen peroxide as an oxidant in the presence of a catalyst has become the key point of research of domestic and foreign scientists, and has the advantages of short process flow, small waste residue and water amount, low energy consumption, environmental protection and the like.

Patents related to the method for synthesizing epichlorohydrin by catalyzing heteropolyacid salt include CN102746257A, CN102477018B, CN108395418A and the like, and the characteristic of catalyzing epoxidation by heteropolyacid salt is that after the reaction is finished, the catalyst is separated out from the reaction system and can be recycled. There is a problem in that reaction by-products enter or adsorb on the catalyst, resulting in deactivation of the catalyst.

The method for preparing epichlorohydrin by using titanium silicalite molecular sieve catalysis (CN103121983A) has the advantages of high catalytic activity and selectivity, mild reaction conditions and the like. At present, when a titanium silicalite molecular sieve is used as a catalyst, the problem of catalyst deactivation generally exists, namely, after the catalyst runs for a certain time, by-products in a system are accumulated and act on an active center of the catalyst, so that the activity and the selectivity of the catalyst are reduced. When the catalytic activity of the titanium silicalite molecular sieve is obviously reduced in a fixed bed, the titanium silicalite molecular sieve needs to be regenerated in a reactor or outside the reactor, the process is complicated, the production efficiency is influenced, and the operation cost of the device is increased.

Disclosure of Invention

The embodiment of the invention aims at the problems in the prior art and provides a method for continuously preparing epichlorohydrin, which prolongs the service life of a titanium silicalite molecular sieve in a fixed bed, thereby prolonging the cycle period of a catalyst and improving the production efficiency; meanwhile, the method has the advantages of mild reaction condition temperature, few byproducts, high selectivity and yield of the epichlorohydrin and the like.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a preparation method of epichlorohydrin takes chloropropene and hydrogen peroxide as raw materials, methanol as a solvent, a titanium silicalite molecular sieve as a catalyst, and quaternary ammonium salt as a surfactant, and comprises the following steps:

a. mixing chloropropene, quaternary ammonium salt and methanol uniformly according to a certain proportion to prepare a mixed solution for later use;

b. simultaneously pumping hydrogen peroxide and the mixed solution into a fixed bed through a metering pump, wherein the reaction airspeed is 0.5h^-1～25h^-1Preferably 6h^-1～12h^-1；

In the step a, the quaternary ammonium salt is one or more of dodecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium bromide, didodecyl gamma-double ammonium bromide, N, N, N-trimethyl adamantyl ammonium bromide and N, N-dimethyl-N-ethyl adamantyl ammonium bromide, preferably one or two of N, N, N-trimethyl adamantyl ammonium bromide and N, N-dimethyl-N-ethyl adamantyl ammonium bromide;

methanol in step a: quaternary ammonium salts: the chloropropene molar ratio is 4-20: 0.001-0.1: 1, preferably 6 to 10: 0.005-0.01: 1;

the concentration of the hydrogen peroxide in the step b is not particularly required, and for the invention, the concentration of the hydrogen peroxide in the hydrogen peroxide is preferably 10-90%, such as 30 wt% and 50 wt% of hydrogen peroxide sold in the market.

In the step b, the molar ratio of the hydrogen peroxide to the chloropropene is 0.2-5: 1, preferably 1-2: 1;

the temperature of the system in the fixed bed in the step b is 10-60 ℃, preferably 15-35 ℃;

the titanium silicalite molecular sieve is at least one of a titanium silicalite molecular sieve with an MFI structure, a titanium silicalite molecular sieve with an MEL structure, a titanium silicalite molecular sieve with a BEA structure, a titanium silicalite molecular sieve with an MWW structure, a titanium silicalite molecular sieve with an MOR structure, a titanium silicalite molecular sieve with a TUN structure and a titanium silicalite molecular sieve with a two-dimensional hexagonal structure.

Preferably, the titanium silicalite molecular sieve is of an MFI structure, the crystal grains are of a hollow structure, the radial length of a cavity part of the hollow structure is 5-300 nm, the benzene adsorption capacity of the titanium silicalite molecular sieve is at least 70 mg/g measured under the conditions that the temperature is 25 ℃, the P/P0 is 0.10 and the adsorption time is 1 hour, and a hysteresis loop exists between the adsorption isotherm and the desorption isotherm of low-temperature nitrogen adsorption of the titanium silicalite molecular sieve.

The invention has the beneficial effects that:

according to the preparation method of the epichlorohydrin, the quaternary ammonium salt surfactant, especially the adamantane quaternary ammonium salt, is added into the reaction system, so that the cycle use period of the titanium silicalite molecular sieve catalyst is prolonged, the production efficiency and the equipment use efficiency are improved, and the preparation method is suitable for continuous production; meanwhile, the method has the advantages of mild reaction condition temperature, few byproducts, high selectivity and yield of the epichlorohydrin and the like.

Detailed Description

The following further describes the embodiments of the present invention. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

A method for continuously preparing epichlorohydrin by directly epoxidizing chloropropene comprises the following steps: under the condition of oxidation reaction, in the presence of quaternary ammonium salt, chloropropene, aqueous hydrogen peroxide, a titanium silicalite molecular sieve catalyst and an organic solvent are subjected to contact reaction in a fixed bed reactor.

The technical scheme of the application has no special requirements on the type of the fixed bed reactor and can be the conventional type in the field.

The oxidation reaction conditions in the fixed bed can be changed within a wide range, and can be reaction conditions of a conventional oxidation system using a titanium silicalite molecular sieve as a catalyst; preferably, an aqueous hydrogen peroxide solution is used as the oxidizing agent to avoid the risk of gaseous hydrogen peroxide. According to one embodiment of the invention, the fixed bed reactor is operated in a continuous mode, and the conditions of the oxidation reaction may include: the mol ratio of chloropropene to hydrogen peroxide is 1: 1-5, preferably 1: 1-2; the mol ratio of the organic solvent to the surfactant to the chloropropene is 4-20: 0.001-0.1: 1, preferably 6 to 10: 0.005-0.01: 1; the contact temperature is 10-60 ℃, preferably 15-35 ℃; there is no particular requirement for pressure.

In the technical scheme of the application, the invention can be realized by only enabling a system in which chloropropene, aqueous hydrogen peroxide and a catalyst containing a titanium silicalite molecular sieve are contacted in an organic solvent to contain a surfactant, and the addition mode of the surfactant has no special requirement, for example, the surfactant can be added into the solvent in advance and then introduced together with the solvent, or the surfactant can be introduced finally (i.e. all reactant raw materials are mixed and then added), or can be introduced after part of the reactant raw materials are added. The object of the present invention can be achieved by any of the above-mentioned methods of introducing a surfactant, and the effects are comparable. For simplification of the actual operation process, the surfactant may be added to the liquid (e.g., organic solvent) in advance and then introduced into the contacted system together with the liquid.

According to the invention, the surfactant is quaternary ammonium salt with more specific surface properties, and the surfactant is selected from one or more of long-chain quaternary ammonium salt, adamantane quaternary ammonium salt and biquaternary ammonium salt, such as: dodecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium bromide, didodecyl gamma-bis ammonium bromide, N, N, N-trimethyl adamantyl ammonium bromide, N, N-dimethyl-N-ethyl adamantyl ammonium bromide; preferably, it is one or two of N, N, N-trimethyladamantylammonium bromide and N, N-dimethyl-N-ethyladaminoalkyl ammonium bromide.

The conditions for the oxidation reaction are not particularly required in the present invention, and may be reaction conditions of a conventional oxidation system using a titanium silicalite as a catalyst, since hydrogen peroxide is easily explosive when it exists in a gaseous form, and thus it is preferable that hydrogen peroxide is supplied as an aqueous hydrogen peroxide solution in the present invention.

The concentration of hydrogen peroxide in the aqueous hydrogen peroxide solution is not particularly limited in the present invention, and for the present invention, the concentration of hydrogen peroxide in the aqueous hydrogen peroxide solution is preferably 20 to 80% by weight, preferably 30 to 50% by weight. For example, 30 wt%, 50 wt%, or 70 wt% of hydrogen peroxide may be commercially available. In the invention, the catalyst containing the titanium silicalite molecular sieve can be a titanium silicalite molecular sieve. The particle size of the titanium silicalite molecular sieve can be 1000 μm or less, for example 800 μm or less, 600 μm or less, or 400 μm or less.

According to the method of the present invention, the titanium silicalite molecular sieve of the present invention can be a titanium silicalite molecular sieve of MFI structure (e.g., TS-1), the titanium silicalite molecular sieve can be obtained commercially or prepared, and the method for preparing the titanium silicalite molecular sieve is well known to those skilled in the art and will not be described herein again.

The following examples further illustrate the invention but do not limit the scope of the invention. In the examples and comparative examples, the reagents used were all commercially available, chemically pure reagents.

The titanium silicalite (TS-1) catalyst used was a sample of (TS-1) molecular sieve prepared as described in the literature [ Zeolite, 1992, Vol.12, pp. 943-950 ] with a titanium oxide content of 2.5 wt.%.

In the invention, the content of each component in the obtained reaction liquid is analyzed by adopting a gas chromatography, and on the basis, the evaluation indexes such as the chloropropene conversion rate, the effective utilization rate of an oxidant, the selectivity of epichlorohydrin and the like are respectively calculated by adopting the following formulas.

In comparative examples and examples:

percent chloropropene conversion [ (% moles chloropropene added-moles chloropropene not reacted)/moles chloropropane added ]

Effective utilization ratio of oxidant [% moles of epichlorohydrin generated by reaction/(moles of oxidant added-moles of oxidant not reacted) ]

Epichlorohydrin selectivity [ (% of moles of epichlorohydrin formed by reaction/(moles of chloropropene added-moles of chloropropene not reacted) ]