Method for participation of graphene catalyst in deep dewaxing of oil product
The graphene catalyst and urea form a network-like supramolecular structure to adsorb and separate the normal alkanes in the oil products, solving the problem of poor stability of traditional catalysts, achieving efficient and economical deep dewaxing effect of oil products, and the catalyst can be reused.
Patent Information
- Application Number
- CN202510668910.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-23
- Publication Date
- 2025-08-22
AI Technical Summary
In the existing catalytic dewaxing technology, the active sites of traditional catalysts are easily covered by carbon deposits, the pore size is limited, and the mass transfer efficiency is low, and the cost of precious metals is high, resulting in poor stability and increased operating costs, making it difficult to achieve efficient and stable deep dewaxing of oil products.
The graphene catalyst is used as the active component to form a network-like supramolecular structure by mixing with urea and water, increasing the specific surface area, adsorbing and separating the normal alkanes in the oil product, and using transition metal oxide modified nitrogen-doped graphene to improve the stability and activity of the catalyst, realizing the reuse of the catalyst.
It achieves efficient and stable deep dewaxing of oil products, reduces the oil product freezing point, and the catalyst can be recycled, improving the dewaxing effect and economy.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of oil dewaxing, and in particular to a method for deep dewaxing of oil using a graphene catalyst. Background Art
[0002] Deep oil dewaxing is a key process in petroleum refining and lubricant production. It aims to improve the low-temperature fluidity and stability of oil products by removing long-chain alkanes (waxes), meeting the needs of applications in cold regions and high-precision machinery. Traditional dewaxing technologies include solvent dewaxing, biodewaxing, and catalytic dewaxing. Solvent dewaxing is a key method for refining petroleum products. This involves diluting lubricating oil feedstock with a solvent and freezing it to crystallize the wax, thereby lowering the oil's freezing point. However, solvent dewaxing relies on low-temperature solvent crystallization to separate the wax, resulting in high energy consumption and complex solvent recovery. Biodewaxing, also known as bacterial dewaxing, is environmentally friendly, but its low reaction rate and limited bacterial adaptability make it difficult to commercialize. Catalytic dewaxing involves the conversion of paraffinic hydrocarbons in the feedstock into lower-boiling hydrocarbons through hydrocracking over a selective hydrodewaxing catalyst (such as platinum-loaded mordenite and ZSM-5 molecular sieve). The product, after flash evaporation, produces a lubricating oil with a low pour point. Byproducts include gasoline and petroleum gas. However, conventional catalysts (such as molecular sieves, metal oxides, or noble metal-supported catalysts) suffer from issues such as carbon deposition on active sites, limited pore size, and high precious metal costs, leading to poor stability and increased operating costs. Therefore, there is a need for a novel catalyst that offers improved stability and enhanced dewaxing performance compared to existing catalysts. Summary of the Invention
[0003] In view of this, the present invention provides a method for deep dewaxing of oil products using a graphene catalyst, which can achieve stable removal of normal alkanes in the oil products, the catalyst can be recycled, and the dewaxing effect is strong.
[0004] To achieve the above objectives, the present invention provides a method for deep dewaxing of oil products using a graphene catalyst, comprising the following steps: heating and melting urea to form liquid urea, mixing the oil product with the liquid urea, water, and a graphene catalyst for agitation and reaction, filtering after the reaction to obtain a purified oil product and a filter cake, and reusing the filter cake to dewax new oil products. The graphene catalyst is nitrogen-doped graphene modified with a transition metal oxide.
[0005] The graphene catalyst provided by the present invention has good hydrophilicity and can be stably dispersed in water for a period of time. After being added to a urea solution, the graphene mixes evenly with the water. After the urea is heated and melted, the graphene is evenly dispersed in the urea solution. During the process of mixing and stirring with the oil product, the urea solution slowly solidifies as the temperature changes. During the solidification process, a network-like supramolecular structure is formed. The network-like supramolecular structure has an extremely large specific surface area. At the same time, due to the uniform dispersion of the graphene catalyst, the specific surface area is further increased. The network-like supramolecular structure allows the normal alkanes in the oil product to fully react with the nitrogen element under the action of the graphene catalyst. The urea as a reaction product does not destroy the network-like supramolecular structure. The network-like supramolecular structure can also adsorb the normal alkanes in the oil product (lowering the pour point of the oil product). By filtration, a purified oil product with a low pour point can be separated, and a filter cake containing normal alkanes, urea, and the graphene catalyst can be obtained. By heating, the normal alkanes in the oil product can be melted, improving their affinity, and entering the normal alkanes phase, which can be relatively easily separated. The remaining urea complex and graphene catalyst can directly enter the next round of oil treatment. In addition, the graphene catalyst and urea complex can be easily melted and separated by water. The separated graphene catalyst can enter the next cycle after activation treatment, achieving the purpose of repeated use, good stability and strong dewaxing effect. Optionally, the urea is heated at a temperature of 105-115° C.; the temperature of the mixed stirring reaction is less than 80° C., and the time is 1.5-2.5 h.
[0006] Optionally, the weight ratio of the oil, liquid urea, water, and graphene catalyst is 10:3~4:0.2~0.8:0.01~0.5.
[0007] Optionally, the following devices are also included: a circulating fluidized bed reaction device, an elevated tank, the elevated tank being connected to the circulating fluidized bed reaction device on one side and to a collecting device on the other side, and the elevated tank having an independent heating system and stirring system.
[0008] Optionally, the urea is heated and melted into liquid urea in the header tank, the urea is mixed with water and graphene catalyst in the header tank, and the oil product is mixed and reacted with the liquid urea, water and graphene catalyst in a circulating fluidized bed reactor.
[0009] Optionally, the filter cake is reused by placing the filter cake into a high-level tank, adding water and heating it to 60-70°C, collecting the upper liquid phase to a collection device after stratification, and then adding urea and heating it to melt it into liquid urea to start dewaxing of new oil products.
[0010] Optionally, the preparation of the transition metal oxide modified nitrogen-doped graphene comprises the following steps: S1. Mixing graphite fluoride, a nitrogen source, and N-methyl-2-pyrrolidone, grinding and dispersing the mixture using a sand mill, and then washing and filtering the mixture with distilled water and anhydrous ethanol to obtain nitrogen-doped graphite fluoride; S2. Mixing the nitrogen-doped fluorinated graphite with an organic base and water and subjecting the mixture to ultrasonic treatment to generate a hydrothermal reaction at high temperature, and then washing and filtering the mixture with distilled water and anhydrous ethanol in sequence to obtain hydroxylated nitrogen-doped graphene; S3. After mixing the hydroxylated nitrogen-doped graphene with a transition metal soluble salt and water, the pH is adjusted and the mixture is stirred evenly. After standing, the mixture undergoes a hydrothermal reaction at high temperature. The mixture is then washed and filtered with distilled water and anhydrous ethanol, and dried to obtain transition metal oxide-modified nitrogen-doped graphene.
[0011] Optionally, the weight ratio of the fluorinated graphite, the nitrogen source, and N-methyl-2-pyrrolidone is 1:2~3:15~25; the weight ratio of the nitrogen-doped fluorinated graphite, the organic base, and water is 1:10~15:80~120; and the weight ratio of the hydroxylated nitrogen-doped graphene, the transition metal soluble salt, and water is 1:1~4:350~450.
[0012] Optionally, the nitrogen source is a soluble ammonium salt containing only C, H, O, and N elements.
[0013] Optionally, the organic base is one or a combination of two or more of 4-methylpyridine, triethylenediamine, and triethylamine.
[0014] Optionally, the soluble transition metal salt is one or a combination of two or more of molybdenum salt, tungsten salt, vanadium salt, iron salt, and nickel salt.
[0015] Optionally, the conditions for sand mill grinding and dispersion in S1 are a rotation speed of 2000~4000rpm and a time of 5~7h; the conditions for hydrothermal reaction at high temperature in S2 are a temperature of 150~180℃ and a time of 40~60h; the conditions for hydrothermal reaction at high temperature in S3 are a temperature of 140~180℃ and a time of 15~20h; and the drying in S3 is vacuum drying at a temperature of 90~110℃.
[0016] Optionally, the S2 step is to mix ethanol and glycerol in a weight ratio of 1:1 to obtain a mixed solvent, add the nitrogen-doped fluorinated graphite to the mixed solvent, and react at a reaction temperature of 170-190° C. for 22-26 hours to obtain hydroxylated nitrogen-doped graphene.
[0017] The above technical solution of the present invention includes at least the following beneficial effects: The graphene catalyst provided by the present invention uses graphene as a carrier for the active component (transition metal oxide). Nitrogen doping can change the surface properties of the graphene, enhancing the interaction between the carrier and the active component, allowing the active component to be stably and evenly dispersed on the graphene surface, thereby improving the activity of the catalyst. Fluorinated graphene is hydrolyzed to produce oxygen-containing functional groups, making the distribution of oxygen-containing functional groups more uniform, facilitating subsequent modification with transition metal elements. The introduction of transition metal elements further enhances catalytic efficiency. The addition of the graphene catalyst to the dewaxing method provided by the present invention improves dewaxing efficiency and is reusable. DETAILED DESCRIPTION
[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.
[0019] Example 1 The present invention provides a method for deep dewaxing of oil products using a graphene catalyst, comprising the following steps: In a circulating fluidized bed reactor, 10 parts by mass of an oil product are added, and in an elevated tank, 5 parts of urea, 0.5 parts of de-distilled water, and 0.1 parts of a graphene catalyst are added. The elevated tank is heated to 110° C. to melt the urea into a liquid. The elevated tank material is then placed in the circulating fluidized bed reactor, where the oil product is stirred and reacted in a reciprocating manner. The mixed reaction temperature is within 80° C., and the reaction time is 1 hour. After the reaction, the purified oil product and a filter cake are obtained by filtration. The filter cake contains normal alkanes, urea complexes, and graphene catalyst. The filter cake is then placed in an elevated tank, 0.5 parts of distilled water is added, stirred, and heated to 65° C. to completely melt the normal alkanes remaining in the filter cake, causing stratification. The upper liquid phase is collected by a collection device to achieve separation. 0.6-1.5 parts of new urea are added to the remaining material, which is further heated to 110° C. to melt the urea into a liquid. The urea is then placed in the circulating fluidized bed reactor to process a new batch of oil product. This process is repeated for 10 batches of oil.
[0020] The preparation of transition metal oxide modified nitrogen-doped graphene includes the following steps: S1. Take 1 part of fluorinated graphite, 3 parts of ammonium carbamate, and 25 parts of N-methyl-2-pyrrolidone, stir them evenly, and process them in a sand mill at 3000 rpm for 6 hours. Then wash and filter them with distilled water and anhydrous ethanol several times to remove impurities, and concentrate them to obtain nitrogen-doped fluorinated graphene slurry; S2, taking a slurry containing 1 part of nitrogen-doped fluorinated graphene, 15 parts of 4-methylpyridine, and 120 parts of distilled water, stirring evenly, ultrasonically treating, reacting at 180°C for 20 hours, then washing and filtering with distilled water and anhydrous ethanol multiple times to remove impurities, and concentrating to obtain a hydroxylated nitrogen-doped graphene slurry; S3 Take a slurry containing 1 part of hydroxylated nitrogen-doped graphene, 4 parts of molybdenum salt, and 450 parts of distilled water, adjust the pH to 9.5 with ammonia water, stir evenly, let it stand for 36 hours, and then add it to a polytetrafluoroethylene-lined high-pressure reactor, react at 180°C for 20 hours, then wash and filter with distilled water multiple times to remove impurities, and vacuum dry at 90°C to obtain transition metal oxide-modified nitrogen-doped graphene, i.e., graphene catalyst.
[0021] Example 2 Compared to Example 1, the only difference is that a mixed solvent of ethanol and glycerol in a weight ratio of 1:1 is used. The nitrogen-doped fluorinated graphite is added to the mixed solvent and reacted at a reaction temperature of 170-190°C for 22-26 hours to obtain hydroxylated nitrogen-doped graphene. The remaining steps and raw materials are the same as in Example 1.
[0022] Comparative Example 1 Compared with Example 1, the only difference is that no graphene catalyst is added, and the remaining steps and raw materials are the same as those in Example 1.
[0023] Comparative Example 2 Compared with Example 1, the only difference is that graphene oxide is used instead of fluorinated graphene for modification. The remaining steps and raw materials are the same as those in Example 1.
[0024] Comparative Example 3 Compared with Example 1, the only difference is that sodium percarbonate is used instead of urea for dewaxing treatment, and the remaining steps and raw materials are the same as those in Example 1.
[0025] The pour point / condensation point of the purified oil products obtained by the dewaxing methods of Example 1 and Comparative Examples 1 to 3 were tested, and the results are shown in Table 1.
[0026] Table 1 Condensation point / pour point table of purified oil products of Example 1 and Comparative Examples 1-2
[0027] Table 2 Pour point reduction efficiency of purified oil products recycled in Example 1
[0028] It can be seen from Tables 1 and 2 that the pour point of the purified oil product in Example 1 is lower than that of the purified oil product in the comparative example, and the pour points of the purified oil products subjected to recycling treatment are similar, that is, the graphene catalyst in the dewaxing method of the present application can be recycled, and the normal alkanes in the oil product can be stably removed, while the dewaxing effect is strong.
[0029] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for deep dewaxing of oil products using a graphene catalyst, characterized in that: The following steps are involved: Urea is heated and melted into liquid urea, and the oil product is mixed with the liquid urea, water and graphene catalyst for stirring and reacting. After the reaction, the purified oil product and filter cake are obtained by filtration. The filter cake is reused to dewax the new oil product. The graphene catalyst is transition metal oxide-modified nitrogen-doped graphene.
2. The method for deep dewaxing of oil products using a graphene catalyst according to claim 1, wherein: The urea is heated at a temperature of 105-115° C.; the temperature of the mixing and stirring reaction is less than 80° C., and the time is 1.5-2.5 hours.
3. The method for deep dewaxing of oil products using a graphene catalyst according to claim 1, wherein: The weight ratio of the oil product, liquid urea, water and graphene catalyst is 10:3-4:0.2-0.8:0.01-0.
5.
4. The method for deep dewaxing of oil products using a graphene catalyst according to claim 1, wherein: It also includes the following devices: a circulating fluidized bed reaction device, an elevated tank, wherein one path of the elevated tank is connected to the circulating fluidized bed reaction device, and the other path is connected to the collecting device, and the elevated tank has an independent heating system and a stirring system.
5. The method for deep dewaxing of oil products using a graphene catalyst according to claim 4, wherein: The urea is heated and melted into liquid urea in the high-level tank, the urea is mixed with water and graphene catalyst in the high-level tank, and the oil product is mixed with liquid urea, water and graphene catalyst in the circulating fluidized bed reactor for reaction.
6. The method for deep dewaxing of oil products using a graphene catalyst according to claim 1, wherein: The filter cake is recycled by placing the filter cake into a high-level tank, adding water and heating it to 60-70°C, collecting the upper liquid phase to a collection device after stratification, and then adding urea and heating it to melt it into liquid urea to start dewaxing new oil products.
7. The method for deep dewaxing of oil products using a graphene catalyst according to claim 1, wherein: The preparation of the transition metal oxide modified nitrogen-doped graphene comprises the following steps: S1. Mixing graphite fluoride, a nitrogen source, and N-methyl-2-pyrrolidone, grinding and dispersing the mixture using a sand mill, and then washing and filtering the mixture with distilled water and anhydrous ethanol to obtain nitrogen-doped graphite fluoride; S2. Mixing the nitrogen-doped fluorinated graphite with an organic base and water and subjecting the mixture to ultrasonic treatment to generate a hydrothermal reaction at high temperature, and then washing and filtering the mixture with distilled water and anhydrous ethanol in sequence to obtain hydroxylated nitrogen-doped graphene; S3. After mixing the hydroxylated nitrogen-doped graphene with a transition metal soluble salt and water, the pH is adjusted and the mixture is stirred evenly. After standing, the mixture undergoes a hydrothermal reaction at high temperature. The mixture is then washed and filtered with distilled water and anhydrous ethanol, and dried to obtain transition metal oxide-modified nitrogen-doped graphene.
8. The method for deep dewaxing of oil products using a graphene catalyst according to claim 7, wherein: The weight ratio of the fluorinated graphite, the nitrogen source, and N-methyl-2-pyrrolidone is 1:2-3:15-25; the weight ratio of the nitrogen-doped fluorinated graphite, the organic base, and water is 1:10-15:80-120; and the weight ratio of the hydroxylated nitrogen-doped graphene, the transition metal soluble salt, and water is 1:1-4:350-450.
9. The method for deep dewaxing of oil products using a graphene catalyst according to claim 7, wherein: The conditions for the sand mill grinding and dispersion in S1 are a rotation speed of 2000~4000rpm and a time of 5~7h; the conditions for the hydrothermal reaction at high temperature in S2 are a temperature of 150~180℃ and a time of 40~60h; the conditions for the hydrothermal reaction at high temperature in S3 are a temperature of 140~180℃ and a time of 15~20h; and the drying in S3 is vacuum drying at a temperature of 90~110℃.
10. The method for deep dewaxing of oil products using a graphene catalyst according to claim 7, wherein: The S2 step comprises mixing ethanol and glycerol in a weight ratio of 1:1 to obtain a mixed solvent, adding the nitrogen-doped fluorinated graphite to the mixed solvent, and reacting at a reaction temperature of 170-190° C. for 22-26 hours to obtain hydroxylated nitrogen-doped graphene.