A method for producing a liquid wax rich in high carbon alpha-olefins by complexation

Abstract

This invention relates to a method for producing liquid wax rich in high-carbon α-olefins using a complexation process. Coking diesel fuel, after being treated with isopropanol and urea dewaxing technology, yields a liquid wax product rich in long-chain n-alkanes and high-carbon α-olefins. Further processing of the liquid wax product using separation technology separates the long-chain n-alkanes and high-carbon α-olefins. At a certain dewaxing depth, 12.57% high-carbon α-olefins can be obtained, while simultaneously lowering the pour point of the coking diesel fuel to -70°C. The method provided by this invention separates C8-C from coking diesel fuel. 20 Straight-chain α-olefins can not only improve the stability of diesel fuel, but also provide raw materials for fine chemicals and functional chemicals that are in short supply in the market, thus meeting the diversified market demand for high-performance products.

Description

Technical Field

[0001] This invention belongs to the technical field of production of special products such as lubricating oil, paraffin wax, and asphalt, and specifically relates to a method for producing liquid wax rich in high-carbon α-olefins by complexation. Background Technology

[0002] Alpha-olefins are important terminal olefin products with wide applications in polyolefin comonomers, plasticizers, surfactant synthesis intermediates, synthesis of high-grade lubricating oil base oils, and lubricating oil additives. 1-Octene is a crucial comonomer for producing high-performance high-density polyethylene and linear low-density polyethylene, and is also an important raw material for the production of fragrances, dyes, plasticizers, surfactants, fatty alcohols, and other fine chemicals. After years of development, the wax cracking method, mixed C4 separation method, ethylene oligomerization method, and vegetable oil method have become the main processes for producing alpha-olefins worldwide. Among these, the ethylene oligomerization method is the primary process for producing higher alpha-olefins such as 1-hexene and 1-octene.

[0003] (1) Paraffin cracking method: Paraffin cracking is divided into thermal cracking and catalytic cracking. Refined wax with a main distillation range of 350℃~480℃ is used as raw material. The cracking produces straight-chain α-olefins. The mass fraction of α-olefins in the product is 5%~30%, and the vast majority are straight-chain α-olefins.

[0004] (2) Mixed C4 Separation Method: This method is derived from a thermal cracking unit or a catalytic cracking unit. The process flow is as follows: butadiene is removed by extraction, isobutylene is removed by chemical method, and high-purity 1-butene is produced by precision distillation or catalytic extraction. When the C4 fraction from catalytic cracking is used as raw material, butadiene is removed first, followed by desulfurization, dehydration, hydrogenation to remove dienes and alkynes, and then residual isobutylene is removed by dimerization. Finally, high-purity 1-butene is obtained by distillation.

[0005] (3) Ethylene Oligomerization Method: The ethylene oligomerization method is a process that uses ethylene as a raw material to prepare α-olefins through oligomerization under the action of a catalyst. C4-C6 olefins can be produced using the ethylene oligomerization method. 40 Linear α-olefins with an even number of carbon atoms. The main processes for their production include the Gulf process, Ethyl process, SHOP process, and Linde process.

[0006] (4) The main process of the vegetable oil method is to hydrogenate vegetable oil to obtain fatty alcohols, which are then dehydrated to produce α-olefins. This technology was already industrialized before World War II. The carbon number of the product depends on the carbon number of the raw material. Most natural vegetable oils are C64-C ... 12 ~C 18 The range of fatty acid triglycerides, therefore, the α-olefins obtained generally have 10 C atoms. 12 ~C 18 .

[0007] (5) The Fischer-Tropsch synthesis process, also known as the extraction separation process, is a technique that separates high-quality α-olefins from the α-olefin-rich stream in the Fischer-Tropsch synthesis process of coal-to-oil through steps such as pre-separation, removal from oxygen-containing organic matter, superdistillation extraction distillation, drying, and refining. This process is the preferred option for coal-to-oil enterprises to produce α-olefins.

[0008] Currently, the main process for producing higher olefins such as 1-hexene and 1-octene is the ethylene oligomerization method. However, the products produced by this method are mostly low-carbon α-olefins, especially with higher selectivity for 1-butene. Although the product quality is very good, the catalyst recovery cost is high.

[0009] Therefore, the ethylene oligomerization method has the following problems:

[0010] (1) The copolymer of ethylene and a small amount of α-olefin generated by the oligomerization process needs to be cleaned manually. In order to avoid the high-temperature deactivation of the ethylene tetramerization catalyst and to improve the reaction efficiency, the reaction temperature is often lowered, which causes the copolymer to remain in the reactor and pipeline, thereby clogging the pipeline, affecting the heat transfer of the reactor, and reducing the reaction efficiency.

[0011] (2) During the oligomerization of ethylene to prepare 1-octene, when methylcyclohexane is used as a solvent, many oligomers adhere to the equipment during the polymerization process, and the solvent ratio is very high, about 50%-70%. Methylcyclohexane and 1-octene have similar boiling points, making the separation process complex.

[0012] Chinese invention patent CN102181305A discloses a continuous sedimentation full-fraction urea dewaxing method for waxy oil, a process used in the domestic production of low-pour-point diesel and liquid paraffin. This method can currently be used to produce coking liquid wax rich in high-carbon α-olefins. This complexation technology allows straight-chain compounds to react with urea at room temperature to form solid complexes. After filtration and separation, these complexes decompose into urea and straight-chain hydrocarbons (olefins and alkanes) at slightly above room temperature. The olefin content in coking diesel is mostly in the C60 range. 11 -C 20 Between these, for coking fractions, approximately 30% of straight-chain hydrocarbons can be separated using a complexation technique, of which the α-olefin content is between 16-17%, and all of them are high-carbon α-olefins. Summary of the Invention

[0013] To overcome the shortcomings of existing technologies, this invention provides a production method that maximizes the yield of high-carbon α-olefins and the yield of n-alkane.

[0014] The inventive concept of this invention is as follows: Coking diesel fuel, after being treated with isopropanol and urea dewaxing technology, yields a liquid wax product rich in long-chain n-alkanes and high-carbon α-olefins. Further processing of the liquid wax product using adsorption separation technology separates the long-chain n-alkanes and high-carbon α-olefins. This invention preferably uses full-fraction coking diesel fuel to maximize the yield of both high-carbon α-olefins and n-alkanes.

[0015] The present invention adopts the following technical solution:

[0016] Delayed coking is carried out using coking diesel as raw material. Through preliminary rough refining, coke powder and impurities in the coking diesel are removed. Isopropanol, urea and water are added to the reactor. After stirring and heating with a stirrer, the raw material oil is added to carry out a complexation reaction. After the complexation reaction is completed, the liquid wax rich in high carbon α-olefins and low pour point base oil are obtained by washing and distillation of crude liquid wax and dewaxing liquid.

[0017] Furthermore, the coking diesel is full-fraction coking diesel.

[0018] Furthermore, the reaction vessel contains a urea complexation reaction, with isopropanol, urea, and water added sequentially; wherein the mass ratio of urea:isopropanol:water is (36-43):(30-42):(18-25).

[0019] Furthermore, the agitator is stirred at a speed of 100-300 rpm, the temperature is raised to 50-70℃, and the temperature is maintained for 2-3 minutes before adding the raw material oil.

[0020] Furthermore, the urine-to-oil ratio is (6-8):1.

[0021] Furthermore, after the feed oil is added to the reactor, it is left to stand for 5-10 minutes to increase the contact time between the feed oil and the urine, and then the temperature is gradually reduced. After cooling to 20-30℃, the stirring rate is 100-300 rpm, and the reaction is carried out at a constant temperature for 30-90 minutes; then the stirring rate is 5-30 rpm, and the sedimentation is allowed for 10-60 minutes.

[0022] Furthermore, the complexation reaction cycle is 6-9 hours. Furthermore, in the complexation reaction, 2-4g of urea is required per gram of n-alkane.

[0023] As a preferred embodiment of the present invention, the mass ratio of urea:isopropanol:water in the reactor is (37-42):(32-40):(18-24).

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. This invention employs a complexation method to separate C8-C from coking diesel oil. 20The linear α-olefins can improve the stability of diesel fuel and provide raw materials for fine and functional chemicals that are in short supply in the market. This invention can obtain 12.57% high-carbon α-olefins at a certain dewaxing depth, while simultaneously lowering the pour point of coking diesel fuel to -70°C.

[0026] 2. Expanding the range of raw materials and product portfolio. Traditional isopropanol-water dewaxing processes mainly rely on specific waxy raw materials. This invention, through process optimization, explores incorporating more types of waxes, even non-traditional waxy raw materials, into the isopropanol-water dewaxing production process, thereby broadening the sources of urea dewaxing equipment and enhancing process adaptability. Simultaneously, this invention aims to deepen research on a complexation technology, striving to develop more high-end products with unique properties and broad application prospects, such as liquid wax products of high-carbon α-olefins, to meet the diversified market demand for high-performance products.

[0027] 3. Optimizing the Product Structure of Traditional Refineries. Faced with fierce competition in the refining industry and changing market demands, this invention not only optimizes the product structure of traditional refineries but also significantly improves refining economic efficiency. Through precise process control and technological innovation, such as adopting advanced separation technologies and optimizing catalyst systems, the added value and market competitiveness of products are enhanced. Simultaneously, the method provided by this invention ensures the active development of new refining product lines, enriching the product structure of refineries and meeting market demands for high-quality, high-performance products. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0029] To more clearly illustrate the objectives, technical solutions, and advantages of this invention, the following detailed description of the invention will be provided in conjunction with embodiments. It should be understood that the following description of the embodiments is intended to explain and illustrate the overall concept of the invention and should not be construed as limiting this disclosure.

[0030] In the description of this disclosure, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are used solely for the convenience and simplicity of describing this disclosure, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only to distinguish different components and should not be construed as indicating or implying relative importance. The word "a" or "an" does not exclude multiple components. Words such as "including" or "comprising" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0031] Furthermore, the technical features involved in the different embodiments of this disclosure described below can be combined with each other as long as they do not conflict with each other.

[0032] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure pertains.

[0033] The high-carbon α-olefins in this invention are high-end polyolefins, specifically α-olefins with 5 or more carbon atoms, generally less than 20 carbon atoms. Common examples include C6 and C8 α-olefins, such as 1-hexene and 1-octene. 1-Hexene is primarily used as a polyethylene comonomer, a raw material in the production of dyes, detergents, and pharmaceuticals, and as an additive in lubricants and fuels. It accounts for 20% of the α-olefin market and is the most common high-end α-olefin. 1-Octenene is primarily used as a polyethylene comonomer, a raw material in the production of plasticizers, surfactants, and synthetic lubricants. It accounts for 15% of the α-olefin market and is another common high-carbon α-olefin besides 1-hexene.

[0034] Examples 1-5

[0035] Step 1:

[0036] Delayed coking refers to heating the raw material to the temperature required for the coking reaction within a short period of time, controlling the raw material to essentially prevent cracking reaction in the furnace tubes, and delaying the cracking reaction to a dedicated coke tower, hence the name delayed coking. The principle of delayed coking is to utilize thermal cracking reactions under high temperature and high pressure conditions to convert heavy petroleum fractions into more valuable products, such as gasoline, diesel, and liquefied petroleum gas. In this embodiment, the raw material is full-fraction coking diesel. Through preliminary rough refining, coke powder and impurities are removed from the coking diesel. The laboratory complexation reaction is a batch operation. Isopropanol, urea, and water are added sequentially to the reactor, with a urea-to-liquid ratio (urea:isopropanol:water) of (36-43):(30-42):(18-25). The agitator speed is 100-300 rpm, the temperature is raised to 50-70℃, held for 2-3 minutes, and then the raw material oil is added, with a feed-to-liquid ratio of (6-8):1. Step 2:

[0037] After the feedstock oil is added to the reactor, it is held for 5-10 minutes to increase the contact time between the feedstock oil and the urine, followed by gradient cooling. The complexation reaction time depends on the length of the induction period, which in turn depends on the size of the urea crystals, the contact efficiency of the reactants, and other factors. Larger crystals require a longer contact time. Stirring is the most common method to promote contact between reactants, increasing the number of collisions between urea crystals and activator molecules, resulting in the removal of inhibitor molecules from the urea surface. Under vigorous stirring, the rate of phase interface formation is greater than the rate at which inhibitors adsorbed on the phase interface are covered. This increases the size of the inhibitor-free phase interface and shortens the induction period of the complexation process. The longer the contact time, the shorter the time required for the complexation reaction.

[0038] The cooling process in this embodiment is shown below:

[0039] Cooling temperature Duration of stay 60-50℃ Stay for 15 minutes 50-40℃ Stay for 15 minutes 40-35℃ Stay for 15 minutes 35-27℃ Stay for 15 minutes

[0040] Step 3:

[0041] After the reactor temperature drops to 20-30℃, the stirring rate is 100-300 rpm, and the reaction is maintained at a constant temperature for 30-90 minutes; then the stirring rate is 5-30 rpm, and the sedimentation time is 10-60 minutes. The complexation reaction takes 1-3 hours to complete. The ratio of urea solution added depends on the concentration used and the required dewaxing depth. Since the concentration of the remaining urea after the reaction must be balanced with the concentration of the remaining n-alkanes in the feed oil, the amount of solid urea added must exceed the theoretical requirement for n-alkane complexation (2-4 g urea / g n-alkanes). In our experiment, the complexation reaction approached equilibrium after about 1-3 hours, at which point stirring was stopped.

[0042] Step 4:

[0043] The complexation reaction specifically includes the following steps: mixing feedstock oil (coking diesel) with urea to form a crystalline complex, washing the complex, heating and decomposing the complex, and washing and distilling the crude wax and dewaxing solution. The entire complexation cycle takes 6-9 hours.

[0044] Table 1. Data from the urea complexation experiment.

[0045]

[0046] The pour point of coking diesel is -10℃. After being complexed with urea, the pour point of dewaxed oil is significantly reduced, reaching as low as -70℃.

[0047] Step 5:

[0048] Through washing and distillation of crude liquid wax and dewaxing solution, liquid wax rich in high-carbon α-olefins and low-pour-point base oil were obtained, and isopropanol urea dewaxing experiments were completed. The coking wax contained 28.83% olefins and 12.57% high-carbon α-olefins.

[0049] Using Example 5 as the preferred embodiment, different reaction conditions were compared, and the yields of liquid wax and low-pour-point base oils (low-pour-point diesel or dewaxed oil) are shown in the table below:

[0050] Table 2. Liquid wax yield and low-pour-point base oil (low-pour-point diesel) yield

[0051]

[0052] Examples 6-10

[0053] The raw material in this embodiment is whole-fraction coking diesel. Through preliminary rough refining, coke powder and impurities are removed from the coking diesel. The laboratory complexation reaction is a batch operation, with urine added sequentially to the reactor. The urine mass ratio (urea:isopropanol:water) = (36-43):(30-42):(18-25). Taking 1200g of urine as an example, in Example 7, 516g of urea, 473g of isopropanol, and 211g of water were added; the urine composition in other examples follows the same principle.

[0054] The agitator is used at a stirring speed of 100-300 rpm. The temperature is raised to 50-70℃ and held for 2-3 minutes. 150g of coking diesel oil is added, with a urea-to-oil ratio of 8:1. The coking diesel oil and urea are mixed to form a crystalline complex. The complex is washed and heated to decompose, with the final reaction temperature at 28℃. The entire complexation cycle takes 6-9 hours. Then, the crude liquid wax and dewaxing solution are washed and distilled to obtain liquid wax rich in high-carbon α-olefins and low-pour-point base oil.

[0055] Table 3. Content of n-alkanes in liquid wax

[0056]

[0057]

[0058] Application examples

[0059] High-carbon α-olefin liquid wax was produced using the method of Example 1. The α-olefin content in coking diesel was 8.39%. Using the method of Example 1 of this invention, the liquid wax obtained through a complexation technique contained 28.88% olefins, of which 12.56% were high-carbon α-olefins. Based on a coking diesel production capacity of 300,000 tons, the coking diesel contains 25,100 tons of α-olefins. Based on a liquid wax yield of 20%, the product contains 7,542 tons of α-olefins. At 12,000 yuan per ton for α-olefin (1-hexene), the annual economic value could be 12,000 * 7,542 = 90.5 million yuan.

[0060] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for producing liquid wax rich in high-carbon α-olefins via complexation, characterized in that, Delayed coking is carried out using coking diesel as raw material. Through preliminary rough refining, coke powder and impurities in the coking diesel are removed. Isopropanol, urea and water are added to the reactor. After stirring and heating with a stirrer, the raw material oil is added to carry out a complexation reaction. After the complexation reaction is completed, the liquid wax rich in high carbon α-olefins and low pour point base oil are obtained by washing and distillation of crude liquid wax and dewaxing liquid.

2. The method according to claim 1, characterized in that, Coking diesel is full-fraction coking diesel.

3. The method according to claim 1, characterized in that, The reaction vessel contains a urea complexation reaction, with isopropanol, urea, and water added sequentially; the mass ratio of urea:isopropanol:water is (36-43):(30-42):(18-25).

4. The method according to claim 1, characterized in that, Stir at 100-300 rpm, heat to 50-70℃, hold for 2-3 minutes, and then add the raw oil.

5. The method according to claim 1, characterized in that, The urine-to-oil ratio is (6-8):

1.

6. The method according to claim 1, characterized in that, After the raw oil is added to the reactor, it is left to stand for 5-10 minutes to increase the contact time between the raw oil and the urine, and then the temperature is gradually reduced.

7. The method according to claim 6, characterized in that, After cooling to 20-30℃, stir at 100-300 rpm and react at a constant temperature for 30-90 minutes; then stir at 5-30 rpm and allow to settle for 10-60 minutes.

8. The method according to claim 1, characterized in that, The complexation reaction cycle is 6-9 hours.

9. The method according to claim 1, characterized in that, In the complexation reaction, 2-4g of urea is required for every gram of n-alkane.

10. The method according to claim 1, characterized in that, The mass ratio of urea, isopropanol and water in the reactor is (37-42):(32-40):(18-24).

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