阅读说明：本技术 一种4-甲基-1-戊烯的合成工艺 (Synthesis process of 4-methyl-1-pentene ) 是由 靳海波 杨索和 何广湘 郭晓燕 张荣月 王启维 江恒 于 2020-06-03 设计创作，主要内容包括：本发明公开了属于有机化工材料制备技术领域的一种4-甲基-1-戊烯的合成工艺。所述4-甲基-1-戊烯合成工艺包括在负载碱金属的碱性盐作为催化剂的条件下,使丙烯在脱水脱氧的基础上发生二聚反应,然后通过分离工艺制备4-甲基-1-戊烯。所述4-甲基-1-戊烯,纯度能达到99.5％,同时副产1-己烯等α-烯烃,满足了工业上对4-甲基-1-戊烯聚合反应的要求。(The invention discloses a synthesis process of 4-methyl-1-pentene, belonging to the technical field of organic chemical material preparation. The synthesis process of the 4-methyl-1-pentene comprises the steps of carrying out dimerization reaction on propylene on the basis of dehydration and deoxidation under the condition that alkali metal-loaded alkaline salt is used as a catalyst, and then preparing the 4-methyl-1-pentene through a separation process. The purity of the 4-methyl-1-pentene can reach 99.5 percent, and alpha-olefin such as 1-hexene and the like is produced as a byproduct, so that the requirement of the industrial polymerization reaction of the 4-methyl-1-pentene is met.)

1. a synthesis process of 4-methyl-1-pentene is characterized by comprising the following steps:

1) catalyst preparation

Adding talcum powder into alkaline salt, heating to a temperature A and stirring; adding alkali metal under the condition of temperature B, continuously stirring and loading, then cooling to room temperature and adding a solvent to obtain a catalyst; mixing a catalyst and inert pellets and filling the mixture into a reaction device; the step 1) is all at N₂The reaction is carried out under the atmosphere;

2) propylene dimerization

Dehydrating and deoxidizing propylene, adding the propylene into a reaction device for primary reaction, cooling, and performing secondary isomerization reaction to obtain a mixture;

3) separation process

And separating the mixture by adopting a separation tower to obtain the 4-methyl-1-pentene.

2. The synthesis process of claim 1, wherein the propylene space velocity is: 0.5-2.0h^-1。

3. The synthetic process according to claim 1, wherein in step 1),

the particle size of the alkaline salt is 200-400 mu m; talc powder: alkali metal: the mass ratio of the alkaline salt is 1: 4.3: 100, respectively;

the temperature A is 300-450 ℃, the stirring speed is 200-600 rpm, and the stirring time is 1-4 h;

the temperature B is 100-200 ℃, the stirring speed is 200-;

after the alkali metal is added under the condition of the temperature B, when the catalyst is dark blue and has metallic luster, the stirring speed is 200-800 r/min, and the stirring time is 1-4 h;

the solvent comprises anhydrous n-octane, n-hexane or n-pentane, and the ratio of the catalyst/g: the dosage ratio of the solvent to mL is 1: 1-5;

the alkali metal comprises Na, K and NaK alloy, wherein the proportion of the NaK alloy is 1: 0.5 to 2; the alkaline salt comprises carbonate and acetate;

the inert pellets comprise ceramic pellets and glass pellets; the volume ratio of the added catalyst to the added inert substance is 1: 0.5-3.

4. The synthesis process according to claim 1, wherein in the step 2), polymerization grade propylene is added into the reaction device through a advection pump;

the primary reaction temperature is 120-200 ℃; the primary reaction pressure is 1.0MPa-8.0 MPa; the temperature of the secondary isomerization reaction is 160-200 ℃; the pressure of the secondary isomerization reaction is 2.0MPa-10.0 MPa.

5. The process of claim 1, wherein the separation column in step 3) comprises a packed column.

6. The process of claim 1, wherein the product of step 3) further comprises an alpha-olefin, particularly 1-hexene.

7. The synthetic process according to any one of claims 1-6, wherein the purity of 4-methyl-1 pentene prepared by the synthetic process is not less than 99.5%, and the yield is not less than 85%.

Technical Field

The invention belongs to the technical field of organic chemical material preparation, and particularly relates to a synthesis process of 4-methyl-1-pentene.

Background

Propylene is an important raw material for modern chemical synthesis, and 4MP1 formed by dimerization of propylene has important industrial application value and serves as C with excellent performance₆Olefins are widely used in copolymerizations to form linear low density polyethylene resins (LLDPE) having excellent tensile and tear strength and good dielectric properties. Since the nineties, the tool monomer of linear low density polyethylene has been dominated by 1-hexene, and subsequent studies have found that hexene is changed to 4MP1 containing higher carbon number 1-octene or more branched chains as a comonomer, which has higher product properties, and is more and more emphasized because of the lower cost of 4MP 1. On the other hand, 4MP1 can also form poly 4MP1 resin by self-polymerization, and is widely applied to the field of manufacturing release paper, medical devices or electronics as high-performance thermoplastic plastics. Therefore, since the 70 s of the last century, foreign Polyethylene (PE) manufacturers such as BP, ICI, Phillips, and japan sumitomo chemical industry have made much effort to research catalysts and production processes of 4MP1 and to produce LLDPE and TPX. Therefore, from the international trend of LLDPE resins, 4MP1 as a comonomer for producing LLDPE resins will become the mainstream of the high-end LLDPE market.

Much research has been done on the dimerization of propylene to 4MP1, with the ultimate aim of applying propylene dimerization to practical industrial production. In 1961 Schramm examined the effect of alkali metal catalysts on propylene dimerization in two reaction systems. The reaction result of the high-pressure batch kettle type reactor shows that the reaction effect of the alkali metal simple substance dispersed by the inert solvent on propylene dimerization is not ideal, and the selectivity of 4MP1 can only reach about 50 percent, which belongs to the primary attempt of the alkali metal catalyst in the reaction direction. Then, the catalyst is used in a different reaction system, namely a fixed bed reactor, the dispersion type of the catalyst is changed, blocky alkali metal is changed into a supported alkali metal catalyst, and the mixture of propylene and propane is catalyzed in the fixed bed reactor to react at a lower mass space velocity, so that the selectivity of the obtained final 4MP1 is about 50 percent. This attempt opens the door of solid superbase in the propylene polymerization direction, and then Wilkes is dedicated to study the dispersion property of alkali metal on the carrier and study the specific reaction process of propylene on the surface of the catalyst in detail, so that the activity of the obtained supported catalyst is related to the size of crystal grains formed by the alkali metal supported on the surface of the carrier, and the surface crystal grains with moderate size can rapidly and stably catalyze the propylene dimerization reaction. He also studied the solvent-dispersed alkali metal catalyst and realized the dimerization catalytic process of propylene in a slurry bubble bed with a selectivity of 4MP1 of 81%. Hamgling in 1968 performed industrial production on propylene dimerization reaction by using a supported metal Na catalyst on the basis of the conclusion of predecessors, built the first 2000t/a 4MP1 production device in the world, and obtained the selectivity of once-through 4MP1 higher than 87%.

Meanwhile, the catalyst system of British oil company and the production process of 4MP1 were used by Mitsui oil chemical company in Japan, and a 2500t/a 4MP1 production plant was built in Japan, and the composition of the product outlet was similar to that of British oil company. In the 80 s, Phillips, USA, introduced a novel solid super-strong base catalyst, which changed single-component carrier into multi-component mixture and dissolved and mixed instead of pure mechanical mixing, added alkali metal Na for melt loading, then added a small amount of cocatalyst and diluted by inert solid to reduce initial dimerization activity, the catalyst was successfully applied to industrial production, built the ten thousand t/a 4MP1 production process, obtained export product 4MP1 purity up to 99% above, laid solid foundation for 4MP1 large-scale production.

At present, the research on the catalyst for catalyzing propylene dimerization is quite few at home, and the Sunwhong of the research institute of petrochemical engineering has been on the K loaded with alkali metal₂CO₃The particle size distribution of the carrier is researched, and the catalyst finds that a certain particle size range of 300-400 nm is required for keeping high catalytic activity, so that the catalytic effect of propylene dimerization to 4MP1 is good under a certain condition, and the selectivity can reach about 85%. Zhang Mingsen, Beijing institute of chemical engineering, mentions vector K in its patent₂CO₃The pore size, the pore channel distribution and the pore volume of the catalyst have great influence on the catalytic performance of the final solid base catalyst, and the further isomerization reaction of the product can be effectively inhibited and the conversion effect of the reaction can be increased only by increasing the large pore channel volume of 100-105 nm. Under the condition, the catalyst can catalyze propylene dimerization to rapidly react and maintain the selectivity of 4MP1 of not less than 90 percent. The method belongs to the initial exploration of propylene synthesis 4MP1 by domestic scholars, has a longer distance to the realization of industrialization, does not build a set of production chain of 4MP1 at home, but has increasing demand for LLDPE synthesized by 4MP1 copolymerization, and the LLDPE produced at home is mainly synthesized by copolymerization of 1-hexene at present, so that the production cost is higher, and the method is lack of competitiveness compared with foreign products. So that the use of LLDPE comes from import more and greatly limits the development space of high-quality polyolefin films in China.

Disclosure of Invention

Aiming at the problems, the invention provides a synthesis process of 4-methyl-1-pentene, which comprises the following steps:

1) catalyst preparation

Adding talcum powder into alkaline salt, heating to a temperature A and stirring; adding alkali metal under the condition of temperature B, continuously stirring and loading, then cooling to room temperature, adding a solvent to obtain a catalyst, and filling the catalyst into a reaction device; the step 1) is all at N₂The reaction is carried out under the atmosphere;

2) propylene dimerization

Dehydrating and deoxidizing propylene, adding the propylene into a reaction device for primary reaction, cooling, and performing secondary isomerization reaction to obtain a mixture;

3) separation process

And separating the mixture by adopting a separation tower to obtain the 4-methyl-1-pentene.

The propylene airspeed is as follows: 0.5-2.0h^-1。

In the step 1), the particle size of the alkaline salt is 200-400 μm; talc powder: alkali metal: the mass ratio of the alkaline salt is 1: 4.3: 100, respectively;

the temperature A is 300-450 ℃, the stirring speed is 200-600 rpm, and the stirring time is 1-4 h;

the temperature B is 100-200 ℃, the stirring speed is 200-;

after the alkali metal is added under the condition of the temperature B, when the catalyst is dark blue and has metallic luster, the stirring speed is 200-800 r/min, and the stirring time is 1-4 h;

the solvent comprises anhydrous n-octane, n-hexane or n-pentane, and the ratio of the catalyst/g: the dosage ratio of the solvent to mL is 1: 1-5;

the alkali metal comprises Na, K and NaK alloy, wherein the proportion of the NaK alloy is 1: 0.5 to 2; the alkaline salt comprises carbonate and acetate;

the inert substances comprise ceramic pellets and glass pellets; the volume ratio of the added catalyst to the added inert substance is 1: 0.5-3.

Adding polymerization-grade propylene into the reaction device through a constant-flow pump in the step 2);

the primary reaction temperature is 120-200 ℃; the primary reaction pressure is 1.0MPa-8.0 MPa; the temperature of the secondary isomerization reaction is 160-200 ℃; the pressure of the secondary isomerization reaction is 2.0MPa-10.0 MPa.

The separation tower in the step 3) comprises a packed tower.

The product in the step 3) also comprises alpha-olefin, in particular 1-hexene.

The purity of the 4-methyl-1 pentene prepared by the synthesis process is more than or equal to 99.5 percent, and the yield is more than or equal to 85 percent.

The invention has the beneficial effects that:

1. the method adopts industrial propylene as a raw material, has rich sources and mild reaction conditions, and adopts separation technologies such as dehydration deoxidation, dimerization reaction, isomerization reaction, rectification and the like to separate and refine the target product 4-methyl-1-pentene, so that high-purity 4-methyl-1-pentene can be directly obtained; the supported alkali metal is used as a catalyst, under the conditions of the temperature of 120-.

Drawings

FIG. 1 is a schematic diagram of a synthesis process of 4-methyl-1-pentene according to the invention;

Detailed Description

The invention is described in further detail below with reference to the following figures and specific examples:

FIG. 1 shows a scheme of the synthesis process of 4-methyl-1-pentene according to the present invention. A dehydration and deoxidation unit: introducing N under reduced pressure₂Removing oxygen from the gas; in the presence of Al₂O₃The dehydration and deoxidation unit removes trace water and trace oxygen.

A reaction unit: carrying out dimerization reaction in a propylene dimerization reaction unit I under a certain reaction condition by using a catalyst; then entering into an isomerization reaction unit II to carry out isomerization reaction under the conditions of catalyst and reaction.

A separation unit: the mixture after the reaction is passed through a gas-liquid separation unit to separate unreacted propylene and the like, and then is fed into a separation unit to sequentially separate 4-methyl-1-pentene, 4-methyl-2-pentene, 1-hexene and the like.

The synthesis process of 4-methyl-1-pentene comprises the following steps:

1) catalyst preparation method

Taking alkaline salt particles with a certain mesh number as a carrier, sieving to obtain particles with the particle size of 200-; cooling to 100-200 ℃, adding about 4.3 wt% of alkali metal in the nitrogen atmosphere, stirring at a high speed for dispersion to avoid agglomeration, stirring at a low speed for loading for 1-4h when the catalyst is dark blue and has metallic luster, cooling to room temperature, adding a solvent to immerse the surface of the catalyst, and removing the catalyst out of a storage tank for later use. Mixing a catalyst and inert glass beads according to a volume ratio of 1: 0.5-3 is added into the reaction device.

2) Propylene dimerization

The propylene dimerization reaction belongs to a high-pressure reaction process, and after a solvent is removed, the polymerization-grade propylene is pumped into a reaction device through an advection pump to react at a certain temperature, pressure and airspeed. And condensing the product through a low-temperature constant-temperature tank, and carrying out GC analysis on the condensate to determine the conversion rate of the propylene reaction, the selectivity of 4MP1 and the distribution of the isomerization products.

3) Isomerization process

At high temperatures, the isomerization rate reached 35.6% of the main reaction rate. The low temperature and high space velocity can inhibit the isomerization reaction activity of the catalyst. Propylene feed tends to compete with 4MP1 for adsorption on the active sites during reaction, making 4MP1 isomerization weaker at high pressure, while 4MP1 feed increases the rate of isomerization.

4) Separation process

Conventional separation towers, including packed towers, are used to ensure high separation efficiency and accurate separation precision of the plates.

Industrial propylene is adopted as a raw material, the source is rich, the reaction condition is mild, and separation technologies such as dehydration deoxidation, dimerization reaction, isomerization reaction, rectification and the like are adopted to separate and refine the target product 4-methyl-1-pentene, so that high-purity 4-methyl-1-pentene can be directly obtained; the supported alkali metal is used as a catalyst, under the conditions of the temperature of 120-.