Environmentally friendly low aromatic hydrocarbon deoiled wax having low melting point, and preparation method therefor

Abstract

The present invention provides an environmentally friendly low aromatic hydrocarbon deoiled wax having a low melting point, and a preparation method therefor. The preparation method comprises: performing wax crystallization on a mixture of a deoiled wax raw oil and a non-aromatic environmentally friendly deoiling solvent to obtain a crystallized mixture, and then performing a solvent deoiling process to obtain an environmentally friendly low aromatic hydrocarbon deoiled wax having a low melting point, wherein the non-aromatic environmentally friendly deoiling solvent is a mixture containing a C4 ketone and cyclohexane, with the content of the C4 ketone being 45-95 wt%. By means of the present invention, the environmentally friendly low aromatic hydrocarbon deoiled wax having a low melting point can be produced, and the subsequent solvent separation effect and low-carbon environmental protection property can be improved.

Description

A low-melting-point, low-aromatic, environmentally friendly deoiled wax and its preparation method

[0001] Cross-reference information

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on November 30, 2023, with application number 202311628518.5 and invention name “A low-melting-point, low-aromatic, environmentally friendly deoiled wax and its preparation method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The invention relates to a low-melting-point, low-aromatic, environment-friendly deoiled wax and a preparation method thereof, belonging to the technical field of petroleum product processing. Background Art

[0004] Paraffin wax (also known as crystalline wax) generally refers to a mixture of hydrocarbons with approximately 18 to 30 carbon atoms. It is typically a white, odorless, waxy solid. It is soluble in non-polar solvents such as gasoline, carbon disulfide, xylene, ether, benzene, chloroform, carbon tetrachloride, and naphtha, but insoluble in polar solvents such as water and methanol. Paraffin wax is primarily composed of straight-chain alkanes, with small amounts of alkanes with individual branches and monocyclic cycloalkanes with long side chains. Paraffin wax can be used to make higher fatty acids, higher alcohols, matches, candles, waterproofing agents, ointments, and electrical insulation materials, and has a wide range of applications in industry and agriculture.

[0005] Paraffin wax is generally classified into different grades based on melting point, with grades ranging from 2°C to 52, 54, 56, and 58. The key performance indicators of paraffin wax are oil content, melting point, and stability. Excessive oil content can affect the color and storage stability of the wax, and also reduce its hardness. Therefore, the oil-containing wax paste extracted from the vacuum distillation fraction must be deoiled using a solvent method or sweating method to reduce its oil content.

[0006] Paraffin wax is generally obtained from the wax oil fraction obtained from atmospheric and vacuum distillation of crude oil, which is then subjected to solvent refining, solvent dewaxing, or wax freeze crystallization and squeeze dewaxing to produce wax paste, which is then solvent deoiled and refined to obtain flake or needle-shaped crystals. With the continuous development of oil refining and chemical process technology, dewaxing and deoiling technologies and methods have also been improved and developed in different directions due to differences in raw material properties and product requirements. The dewaxing and deoiling methods currently used in industry are generally as follows:

[0007] (1) Cold pressing dewaxing. Also known as crystallization dewaxing, this dewaxing method was only used in the early days and is rarely used now. This method is simple to operate and is suitable for the dewaxing of diesel and light lubricating oils. Its principle is to directly cool the oil to the low temperature required for wax precipitation, and then separate the wax oil by filter pressing to obtain dewaxed oil and crude wax respectively. For high-viscosity oils, this dewaxing method is not suitable for oils with high viscosity. Due to its high viscosity, the viscosity is even greater at low temperatures, resulting in smaller crystals of wax formed, which are not easy to filter. The oil and wax cannot be completely separated, and a good dewaxing effect cannot be achieved. It is difficult to ensure the dewaxing accuracy at low temperatures, the oil content in the crude wax is high, and the dewaxed oil yield is not very high. At the same time, the efficiency of the freezing crystallization and filter pressing equipment used in the process is high, which cannot meet the requirements of continuous production in industry. Therefore, this type of dewaxing method has almost been eliminated.

[0008] (2) Urea dewaxing. This method utilizes the ability of urea to form a complex with paraffin wax, which is then filtered out from the waxy crude oil to separate the paraffin wax from the oil. This method is suitable for waxy crude oils with low viscosity, such as light diesel fractions and light lubricating oils.

[0009] (3) Molecular sieve dewaxing. This method is to selectively adsorb oil and wax components under the action of molecular sieve to achieve the dewaxing effect. Generally, the pore size is Dewaxing is carried out by the adsorption of molecular sieves. Molecular sieves adsorb normal paraffins in petroleum products while not adsorbing isoparaffins and cycloparaffins, thereby separating normal paraffins from non-normal paraffins in waxy feedstocks. Due to their small pore size, molecular sieves are suitable for waxy feedstocks with lower viscosities. While adsorption dewaxing equipment is simple and inexpensive, the feedstock must be deeply refined to remove colloids, as molecular sieves cannot desorb these substances after adsorbing them.

[0010] (4) Bacterial dewaxing. This method involves mixing Candida lipolytica with waxy crude oil. The Candida lipolytica will consume the paraffin in the waxy crude oil and then float to the surface, where it is separated by centrifugation.

[0011] (5) Catalytic dewaxing. Also known as hydrodewaxing, this method uses a catalyst to cause the waxy crude oil to undergo hydroisomerization and selective hydrocracking reactions with hydrogen at higher temperatures and pressures, converting normal alkanes with higher freezing points into isoalkanes and small molecular alkanes with lower freezing points, thereby removing paraffin and lowering the freezing point of the waxy crude oil.

[0012] (6) Solvent dewaxing. The process principles of solvent dewaxing and solvent deoiling are basically the same. Generally, waxy raw oil is mixed with solvent. The difference in solubility is mainly used to make the oil in the raw oil dissolve in the solvent, while the wax cannot dissolve or dissolves in a very small amount in the solvent. Under low temperature conditions, the solvent itself has a low viscosity and a high solubility for oil, but a low solubility for wax. Ultimately, the viscosity of the oil is reduced, and the wax grows into coarse crystals. Then, by cooling, paraffin is precipitated. After the paraffin is precipitated, it can be filtered to separate the paraffin from the oil. This method is widely used and is applicable to various wax oil raw materials with different viscosities. It is the mainstream process for producing paraffin wax.

[0013] The world's first acetone-benzene dewaxing unit using the solvent dewaxing process was built in 1927 and has been continuously improved and developed since then. Currently, the dewaxing and deoiling solvent commonly used in industry is primarily a methyl ethyl ketone-toluene mixture. The processes for solvent dewaxing and solvent deoiling are generally similar. Taking acetone-benzene dewaxing and deoiling as an example, they generally include crystallization, filtration, and solvent recovery. In industry, the raw materials and solvent are typically exchanged with the filtrate in a scraper-equipped double-tube crystallizer, and some solvent is added. The process is then cooled with ammonia and diluted with the solvent before filtration. The filtered filtrate and wax solution are then evaporated and stripped to recover the solvent. The composition and solvent ratio of the added solvent mixture vary depending on the raw material properties (boiling range, wax content, etc.) and the depth of dewaxing. Typically, the methyl ethyl ketone-toluene solvent contains 40%-60% methyl ethyl ketone. Adding the diluent solvent in several stages promotes good wax crystallization, reduces the dewaxing temperature difference (i.e., the difference between the freezing point and the dewaxing temperature of the dewaxed oil), and improves the dewaxed oil yield. The cooling rate of the raw materials in the tubular crystallizer should not be too fast to avoid the formation of too many fine wax crystals, which is not conducive to filtration. Filtration is generally carried out in a filter. Depending on the wax content of the raw materials, one or two stages of filtration are used, and the solvent is recovered from the filtrate and wax liquid.

[0014] Conventional solvent deoiling and dewaxing processes primarily aim to remove high-pour point paraffin components from the wax oil feedstock and meet the low-temperature fluidity requirements of the base oil. Co-production of oil and wax can be implemented as needed. Solvent deoiling processes are generally designed to produce high-quality paraffin wax. Modern refining and chemical companies typically use a two- or three-stage dewaxing and deoiling process to produce deoiled wax and dewaxed oil. If the wax oil content still does not meet the standard after two deoiling stages, a three-stage deoiling process can be used to produce deoiled wax. The three-stage deoiling process generally involves mixing the feedstock with a solvent, adjusting the temperature to the first deoiling temperature, and filtering to produce a first-stage deoiled wax paste. The first-stage deoiled wax paste is then mixed with a solvent, adjusted the temperature to the second deoiling temperature, and filtered to produce a second-stage deoiled wax paste. The second-stage deoiled wax paste is then mixed with a solvent, adjusted the temperature to the third deoiling temperature, and filtered to produce a third-stage deoiled wax paste. The solvent is then removed from the third-stage deoiled wax paste to produce deoiled wax. Using a three-stage deoiling process effectively reduces the oil content of the wax and meets product quality requirements.

[0015] The traditional industrial process for solvent deoiling and dewaxing is ketone-benzene deoiling and dewaxing, using a methyl ethyl ketone-toluene mixture as the primary solvent. This process offers excellent oil-wax selectivity and raw material dilution performance when producing conventional paraffin waxes (melting point ≥52°C). However, when using the traditional ketone-benzene process to produce low-melting-point paraffin waxes (<52°C), problems arise due to difficulties in subsequent separation of the wax and oil agents, as well as high aromatic content in the low-melting-point paraffin waxes. The production technology for high-quality low-melting-point paraffin waxes requires further improvement.

[0016] CN104109559A discloses a preparation method for producing a long-chain low-melting-point wax that is not a short-chain chlorinated paraffin, wherein the method comprises: (1) heating and melting raw oil, adding an ester solvent and a crystal modifier to the melted raw oil, and keeping the temperature at 45-65°C to obtain a mixture; (2) cooling and crystallizing the mixture obtained in step (1) until the crystallization temperature drops to -15 to -20°C to obtain a crystalline mixture; (3) filtering the crystalline mixture obtained in step (2) to obtain a filter cake and a filtrate, heating and distilling the filter cake to remove the ester solvent, and thus obtaining the long-chain low-melting-point wax.

[0017] CN110776955A discloses a method for producing low-melting-point wax for soap, comprising hydrocracking tail oil, furfural refining, ketone-benzene deoiling and dewaxing, selective deoiled wax, primary sweating, selective component mixing, secondary sweating, blending, cutting and deodorization, clay refining, ammonia cold molding, and product. The low-melting-point paraffin wax fraction enters a distillation tower for deodorization, is then refined with clay to improve its color and stability, and is then frozen, molded, and packaged.

[0018] CN107267213A discloses a method for producing low-melting-point wax for soap, which includes hydrocracking tail oil → furfural refining → ketone-benzene deoiling and dewaxing → selective deoiled wax → primary sweating → selective component mixing → secondary sweating → blending → cutting and deodorization → clay refining → ammonia cold molding → product. The low-melting-point paraffin wax fraction enters a distillation tower for deodorization, then undergoes clay refining to improve its color and stability, and is then frozen, molded, and packaged.

[0019] CN105802669A discloses a method for producing soap wax and low-melting-point paraffin wax, wherein the method includes adding a low-boiling-point liquid to the raw materials, and using air flow to carry out liquid oil through the wax layer during the heating and sweating process to forcibly separate the wax and oil, thereby enhancing the separation effect and accelerating the separation speed, thereby increasing the yield of the target product and shortening the production cycle.

[0020] CN105754657A discloses a method for preparing low-melting-point paraffin wax, which includes evenly spreading solid particles on the surface of a wax layer before the heating and sweating process, and forcing air flow through the wax layer during the heating and sweating process to carry out liquid oil, thereby accelerating the separation speed of the wax and oil and enhancing the separation effect of the wax and oil.

[0021] CN107523344A discloses a method for producing soap wax and low-melting-point paraffin wax by sweating, wherein the method includes forming stable tiny bubbles in the wax layer of the sweating raw material under the action of a bubble stabilizer on the basis of a conventional sweating deoiling process to facilitate the rapid discharge of oil, and at the same time, using air flow to carry out liquid oil through the wax layer during the sweating process to forcibly separate the wax and oil, thereby improving the yield of the target product and shortening the production cycle.

[0022] CN107513409B discloses a method for producing soap wax and low-melting-point paraffin wax, wherein the method includes, based on a conventional sweating deoiling process, using an air flow to carry out liquid oil through the wax layer during the sweating process to forcibly separate the wax and oil, and preferably emulsifying the raw materials with water or a salt solution, thereby improving the yield of the target product while shortening the production cycle.

[0023] CN107523348B discloses a method for producing soap wax and low-melting-point paraffin wax, wherein the method includes, on the basis of a conventional sweating and deoiling process, preferably emulsifying the raw materials and aqueous solutions of two or more substances that can react to generate gas, and then sweating, and using air flow to carry out liquid oil through the wax layer during the sweating process to forcibly separate the wax and oil, thereby improving the yield of the target product while shortening the production cycle.

[0024] CN107523346A discloses a method for sweating and preparing soap wax and low-melting-point paraffin wax. The method comprises the following steps: dissolving an oil-soluble emulsifier and an oil-soluble acid in a sweating raw material as an oil phase material, and using an inorganic salt solution as an aqueous phase material on the basis of a conventional sweating and deoiling process; sweating is performed after emulsification; bubbles and salt solution generated by the reaction of the oil-soluble acid and the inorganic salt are discharged to form micro spaces, thereby forming channels for discharging oil and promoting rapid discharge of the oil; and simultaneously, during the sweating process, air flow is used to carry out liquid oil through the wax layer to forcibly separate the wax and oil, thereby improving the yield of the target product and shortening the production cycle.

[0025] CN1472255A discloses a method for preparing a low-melting-point heat-sensitive wax, which comprises mixing 45-99% of a base soft wax, 0.2-10% of a crystal modifier, 0.5-30% of a tackifier, and 0.3-15% of a heat conductor. The low-melting-point heat-sensitive wax is obtained by mixing the base soft wax, 0.2-10% of a crystal modifier, 0.5-3% of a tackifier, and 0.3-15% of a heat conductor at 100-150°C, stirring for 20-300 minutes, and then cooling.

[0026] Liu Huizhen et al. (Liu Huizhen, Chen Wenyi, Liu Ying, Yao Erwei. Research and development of special wax with low melting point and high hardness [J]. Petroleum Refining and Chemical Industry, 2016, (02): 79-83.) used polyethylene wax and lauric acid as paraffin wax modifiers and investigated the effects of modification process conditions and modifier addition amount on the properties of paraffin wax. The results show that the optimal process conditions are modification time 3h, modification temperature 130℃, stirring rate 600r / min, polyethylene wax addition amount (w) of 5%, and lauric acid addition amount (w) of 8%; by blending the above two additives, a modified paraffin product with a low drop melting point and appropriate hardness was prepared; on this basis, a certain amount of stearic acid was added, that is, when the polyethylene wax addition amount (w) was 5%, the lauric acid addition amount (w) was 8%, and the stearic acid was 0-25%, a modified wax with a lower drop melting point and improved hardness can be obtained; and SPSS software was used for linear regression to obtain the relationship between the addition amount of polyethylene wax, lauric acid and stearic acid and the drop melting point and needle penetration (25℃) of paraffin.

[0027] Zheng Lihui (Zheng Lihui. Research on the Preparation of Low-Melting-Point Paraffin Wax by Urea Inclusion Method [J]. Fine Petrochemicals, 2002, (06): 11-13.) used commercial paraffin as raw material and prepared paraffin wax with a suitable phase transition temperature (melting range of 26-26.6°C) by urea inclusion method. Experiments showed that the main and secondary factors affecting the reaction were inclusion temperature, mass ratio of urea to paraffin, reaction time, and mass ratio of ethanol to urea. When the reaction temperature was 70°C, the mass ratio of urea to paraffin was 3:1, the reaction time was 2.5h, and the mass ratio of ethanol to urea was 0.2, paraffin wax with an initial melting point of 26°C and a final melting point of 26.6°C was obtained.

[0028] Feng Tao (Feng Tao. Using low melting point oily wax to select appropriate production process to produce high quality paraffin wax [J]. Guangdong Chemical Industry, 2012, (04): 265-266.) uses the rich low melting point wax of ketone benzene dewaxing unit as the main raw material, combined with the use of four-line oily wax, adopts sweating narrow fraction cutting deoiling process and solvent deoiling process to pretreat the raw material, and combines white clay refining process to produce high quality semi-refined wax.

[0029] Wang Shixin et al. (Wang Shixin, Liu Huiqing, Lin Zhenfa. Production of lubricant base oil and low-melting-point food paraffin using MHUG tail oil [J]. Petroleum Refining and Chemical Industry, 1996, (01): 32-36.) used MHUG tail oil to produce lubricant base oil and low-melting-point food paraffin. By using the method of methyl ethyl ketone-toluene (MEK-TOL) dewaxing and deoiling and white clay refining, high-quality lubricant base oil and high-yield food paraffin can be produced from medium-pressure hydrogenation (MHUG) tail oil. The dewaxed oil can also be used as a raw material for high-quality white oil.

[0030] However, the problems of high aromatic content in the low-melting-point paraffin wax product, difficulty in subsequent solvent separation, and insufficient low-carbon and environmental protection in the process when producing low-melting-point paraffin wax using the ketone-benzene process have not been fundamentally solved, and the preparation of low-melting-point environmentally friendly paraffin wax is limited. Therefore, there is a need to provide a method for preparing low-melting-point, low-aromatic, environmentally friendly deoiled wax using a non-aromatic environmentally friendly mixed solvent.

[0031] Summary of the Invention

[0032] To address the above technical problems, the present invention aims to provide a low-melting-point, low-aromatic, environmentally friendly deoiled wax and a method for preparing the same. By using a non-aromatic, environmentally friendly deoiling solvent in the solvent deoiling process, a dewaxed oil with low aromatic content, a low melting point, and low oil content is produced.

[0033] To achieve the above-mentioned purpose, the present invention provides a method for preparing low-melting-point, low-aromatic, environmentally friendly deoiled wax, wherein the preparation method comprises: subjecting a mixture of deoiled wax feedstock oil and a non-aromatic environmentally friendly deoiling solvent to wax crystallization to obtain a crystalline mixed material, and then subjecting the mixture to a solvent deoiling process to obtain the low-melting-point, low-aromatic, environmentally friendly deoiled wax.

[0034] According to a specific embodiment of the present invention, preferably, the non-aromatic environmentally friendly deoiling solvent is a mixture of C4 ketone and cyclohexane, wherein, based on the total mass of the mixture of C4 ketone and cyclohexane, the content of C4 ketone accounts for 45-95wt%, and the content of cyclohexane accounts for 5-55wt%.

[0035] According to a specific embodiment of the present invention, preferably, the deoiled wax feedstock oil is a light wax oil fraction.

[0036] In some specific embodiments, preferably, the light wax oil fraction is selected from crude oil primary processing minus second-line distillate oil, or other waxy oils with similar distillation range components.

[0037] According to a specific embodiment of the present invention, preferably, the C4 ketone is methyl ethyl ketone; based on the total mass of the mixture of methyl ethyl ketone and cyclohexane, the content of methyl ethyl ketone is 45-95 wt%, and the content of cyclohexane is 5-55 wt%.

[0038] In some specific embodiments, preferably, the content of the methyl ethyl ketone is 55-85 wt %, and the content of the cyclohexane is 15-45 wt %.

[0039] According to a specific embodiment of the present invention, preferably, the wax crystallization is performed by multi-point dilution.

[0040] In some specific embodiments, preferably, the multi-point dilution is a two-point dilution, and the dilution conditions include: the first-point dilution temperature is 20-60°C, and the second-point dilution temperature is 3-25°C; more preferably, the first-point dilution temperature is 23-55°C, and the second-point dilution temperature is 6-20°C.

[0041] According to a specific embodiment of the present invention, preferably, the dilution conditions also include: when performing the first dilution, the mass ratio of the non-aromatic environmentally friendly deoiling solvent to the deoiled wax feedstock oil is 0.2-7.5:1; when performing the second dilution, the mass ratio of the non-aromatic environmentally friendly deoiling solvent to the deoiled wax feedstock oil is 0.5-7.5:1.

[0042] In some specific embodiments, preferably, when performing the first dilution, the mass ratio of the non-aromatic environmentally friendly deoiling solvent to the deoiled wax feedstock oil is 0.5-4.5:1, and when performing the second dilution, the mass ratio of the non-aromatic environmentally friendly deoiling solvent to the deoiled wax feedstock oil is 0.8-4.5:1.

[0043] According to a specific embodiment of the present invention, preferably, the solvent deoiling process includes: under the first-stage deoiling conditions, subjecting the mixture of the crystallized mixed material and the first-stage deoiling dilution solvent to the first-stage solvent deoiling to obtain a first-stage deoiled wax paste and a first-stage deoiled filtrate; under the second-stage deoiling conditions, subjecting the mixture of the first-stage deoiled wax paste and the second-stage deoiling dilution solvent to the second-stage solvent deoiling to obtain a second-stage deoiled wax paste and a second-stage deoiled filtrate; under the third-stage deoiling conditions, subjecting the mixture of the second-stage deoiled wax paste and the third-stage deoiling dilution solvent to the third-stage solvent deoiling to obtain a third-stage deoiled wax paste and a third-stage deoiled filtrate; after the third-stage deoiling wax paste is solvent separated, a low-melting-point, low-aromatic, environmentally friendly deoiled wax is obtained.

[0044] According to a specific embodiment of the present invention, preferably, the process of the first stage solvent deoiling is: filtering the mixture of the crystallized mixed material and the first stage deoiling dilution solvent under the first stage deoiling conditions to obtain a first stage deoiled wax paste and a first stage deoiled filtrate.

[0045] According to a specific embodiment of the present invention, preferably, the first-stage solvent deoiling process further comprises washing the first-stage deoiled wax paste with a first-stage deoiling washing solvent under the first-stage deoiling conditions.

[0046] According to a specific embodiment of the present invention, preferably, the first-stage deoiling dilution solvent includes one or a combination of two or more of a non-aromatic environmentally friendly deoiling solvent, a second-stage deoiling filtrate, and a third-stage deoiling filtrate, and is preferably a non-aromatic environmentally friendly deoiling solvent; wherein the second-stage deoiling filtrate and the third-stage deoiling filtrate are equivalent to the reuse of the products of the second-stage solvent deoiling and the third-stage solvent deoiling, respectively.

[0047] According to a specific embodiment of the present invention, preferably, the first-stage deoiling washing solvent includes one or a combination of two or more of a non-aromatic environmentally friendly deoiling solvent, a second-stage deoiling filtrate, and a third-stage deoiling filtrate.

[0048] According to a specific embodiment of the present invention, preferably, the first stage solvent deoiling conditions include: the first stage solvent deoiling temperature T1 is -25°C to 20°C, preferably -20°C to 15°C, more preferably -15°C to 12°C. The solvent deoiling temperature includes the filtration temperature and the washing temperature during solvent deoiling.

[0049] According to a specific embodiment of the present invention, preferably, the first stage solvent deoiling conditions further include: a mass ratio of the first stage deoiling dilution solvent to the deoiled wax feedstock oil is 0.5-4.0:1, preferably 1.0-3.5:1.

[0050] According to a specific embodiment of the present invention, preferably, the mass ratio of the first-stage deoiling washing solvent to the deoiled wax feedstock oil is 0.1-3.0:1, preferably 0.3-1.0:1.

[0051] According to a specific embodiment of the present invention, preferably, the process of the second stage solvent deoiling is: filtering the mixture of the first stage deoiled wax paste and the second stage deoiling dilution solvent under the second stage deoiling conditions to obtain the second stage deoiled wax paste and the second stage deoiling filtrate.

[0052] According to a specific embodiment of the present invention, preferably, the second-stage solvent deoiling process further comprises washing the second-stage deoiled wax paste with a second-stage deoiling washing solvent under the second-stage deoiling conditions.

[0053] According to a specific embodiment of the present invention, preferably, the second stage deoiling conditions include: the second stage solvent deoiling temperature is T2, T2-T1=-6°C to 20°C, preferably -3°C to 15°C, more preferably 0°C to 10°C. The solvent deoiling temperature includes the filtration temperature and the washing temperature during solvent deoiling.

[0054] According to a specific embodiment of the present invention, preferably, the second stage deoiling conditions further include: a mass ratio of the second stage deoiling dilution solvent to the deoiled wax feedstock oil is 0.5-4.0:1, preferably 1.0-3.5:1.

[0055] According to a specific embodiment of the present invention, preferably, the mass ratio of the secondary deoiling washing solvent to the deoiled wax feedstock oil is 0.1-3.0:1, preferably 0.3-1.0:1.

[0056] According to a specific embodiment of the present invention, preferably, the process of the third stage solvent deoiling is: filtering the mixture of the second stage deoiled wax paste and the third stage deoiling dilution solvent under the third stage deoiling conditions to obtain the third stage deoiled wax paste and the third stage deoiling filtrate.

[0057] According to a specific embodiment of the present invention, preferably, the third stage solvent deoiling process further comprises washing the third stage deoiled wax paste with a third stage deoiling washing solvent under the third stage deoiling conditions.

[0058] According to a specific embodiment of the present invention, preferably, the second-stage deoiling dilution solvent is a non-aromatic environmentally friendly deoiling solvent and / or a third-stage deoiling filtrate, preferably a non-aromatic environmentally friendly deoiling solvent; wherein the third-stage deoiling filtrate is equivalent to the reuse of the product of the third-stage solvent deoiling.

[0059] According to a specific embodiment of the present invention, preferably, the three-stage deoiling dilution solvent is a non-aromatic environmentally friendly deoiling solvent and / or a three-stage deoiling filtrate, preferably a non-aromatic environmentally friendly deoiling solvent.

[0060] According to a specific embodiment of the present invention, preferably, the second-stage deoiling washing solvent is a non-aromatic environmentally friendly deoiling solvent and / or a third-stage deoiling filtrate.

[0061] According to a specific embodiment of the present invention, preferably, the three-stage deoiling washing solvent is a non-aromatic environmentally friendly deoiling solvent and / or a three-stage deoiling filtrate.

[0062] According to a specific embodiment of the present invention, preferably, the third stage deoiling conditions include: the temperature of the third stage solvent deoiling is T3, T3-T2=-6°C to 20°C, preferably -3°C to 15°C, more preferably 0°C to 10°C. The solvent deoiling temperature includes the filtration temperature and the washing temperature during solvent deoiling.

[0063] According to a specific embodiment of the present invention, preferably, the third stage deoiling conditions further include: a mass ratio of the third stage deoiling solvent to the deoiled wax feedstock oil is 0.5-4.0:1, preferably 1.0-3.5:1.

[0064] According to a specific embodiment of the present invention, preferably, the mass ratio of the three-stage deoiling washing solvent to the deoiled wax feedstock oil is 0.1-3.0:1, preferably 0.3-1.0:1.

[0065] The present invention also provides a low-melting-point, low-aromatic, environment-friendly deoiled wax obtained by the above-mentioned preparation method.

[0066] According to a specific embodiment of the present invention, preferably, the melting point of the deoiled wax is less than 52°C, preferably 40°C-50°C.

[0067] According to a specific embodiment of the present invention, preferably, the benzene content of the deoiled wax is 0-0.49 μg·g -1 , preferably 0.1614-0.2091 μg·g -1 , toluene content is 0-4.9μg·g -1 , preferably 0 μg·g -1 .

[0068] According to a specific embodiment of the present invention, preferably, the oil content of the deoiled wax is 0.3%-2.0%, preferably 0.51%-0.8%.

[0069] The inventors discovered that when producing low-melting-point paraffin wax (<52°C) using a conventional ketone-benzene solvent de-oiling and dewaxing process using light wax oil fractions as raw materials, the toluene in the methyl ethyl ketone-toluene mixed solvent is poorly separated during the subsequent wax separation process. This allows toluene to be easily carried over into the wax, resulting in a high aromatic content in the de-oiled wax and a less environmentally friendly paraffin product. The presence of toluene also contributes to the process's lack of low-carbon and environmental friendliness.

[0070] Compared with the prior art, the present invention has the following beneficial effects:

[0071] (1) The present invention provides a novel non-aromatic environmentally friendly deoiling solvent. Since the entire process does not involve the participation of aromatic solvents, it not only improves the low carbonization level of the production process, but also enables the production of low aromatic environmentally friendly low melting point (<52°C) deoiled wax.

[0072] (2) The present invention uses a new type of non-aromatic environmentally friendly deoiling solvent for solvent deoiling. When the deoiled wax is subsequently subjected to solvent distillation separation, the solvent separation effect can be significantly improved because the atmospheric boiling point of the new non-aromatic solvent is significantly lower than that of the conventional industrial methyl ethyl ketone-toluene solvent. Under the same three-stage deoiling process conditions, the use of the new non-aromatic solvent can reduce energy consumption by about 8% compared to the use of the traditional methyl ethyl ketone-toluene solvent. Therefore, this preparation method can not only improve solvent recovery efficiency and reduce energy consumption, but also improve the product quality of low-melting-point (<52°C) low-aromatic environmentally friendly paraffin wax.

[0073] (3) The present invention adopts a new type of non-aromatic environmentally friendly deoiling solvent for three-stage solvent deoiling, which can achieve sufficient separation of low-melting-point paraffin and oil. On the premise of achieving low aromatic content in low-melting-point environmentally friendly paraffin, the oil content of low-melting-point paraffin is further reduced to meet the low oil content standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] FIG1 is a simplified flow chart of a process for preparing low-melting-point deoiled wax according to an embodiment of the present invention. DETAILED DESCRIPTION

[0075] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0076] According to the present invention, the method includes: subjecting a mixture of a light wax oil fraction and a non-aromatic environmentally friendly deoiling solvent to wax crystallization to obtain a crystallized mixed material, and then subjecting the mixture to a solvent deoiling process; the solvent deoiling process includes: subjecting the crystallized mixed material and a first-stage deoiling dilution solvent to a first-stage solvent deoiling under first-stage deoiling conditions to obtain a first-stage deoiled wax paste and a first-stage deoiled filtrate; subjecting the first-stage deoiled wax paste and a second-stage deoiling dilution solvent to a second-stage solvent deoiling under second-stage deoiling conditions to obtain a second-stage deoiled wax paste and a second-stage deoiled filtrate, wherein the temperature of the second-stage deoiling is generally not lower than the deoiling temperature of the first stage; subjecting the second-stage deoiled wax paste and a third-stage deoiling dilution solvent to a third-stage solvent deoiling under third-stage deoiling conditions to obtain a third-stage deoiled wax paste and a third-stage deoiled filtrate, wherein the temperature of the third-stage deoiling is generally not lower than the deoiling temperature of the second stage; after solvent separation, the three-stage deoiled wax paste obtains a low-melting-point, low-aromatic environmentally friendly deoiled wax.

[0077] The present invention will be described in detail below through specific embodiments:

[0078] Example 1

[0079] This embodiment provides a method for preparing a low-melting-point, low-aromatic, environmentally friendly dewaxed oil, which comprises the following steps:

[0080] The feedstock oil was 1# minus second-line distillate oil, the specific properties of which are shown in Table 1. A three-stage deoiling process was employed. The dilution solvent and wash solvent used in the wax crystallization and three-stage solvent deoiling processes were both a mixture of methyl ethyl ketone and cyclohexane, with a methyl ethyl ketone content of 85% by weight and a cyclohexane content of 15% by weight. The dilution ratio (the mass ratio of dilution solvent to feedstock oil) of the dilution solvent and the cold wash ratio (the mass ratio of wash solvent to feedstock oil) of the wash solvent were both relative to the feedstock oil.

[0081] Deoiled wax is prepared according to the process flow shown in Figure 1. The specific process is as follows: multi-point dilution is adopted (the raw oil is first melted at 60°C, and then multi-point dilution is performed during the solvent deoiling process by adding a dilution solvent multiple times), the melted raw oil is sequentially mixed with the dilution solvent, and the temperature is programmed to perform paraffin crystallization; when performing the first-point dilution, the mass ratio of the non-aromatic environmentally friendly deoiling solvent to the deoiled wax raw oil is 0.5:1, and the first-point dilution temperature is 33°C. When performing the second-point dilution, the mass ratio of the non-aromatic environmentally friendly deoiling solvent to the deoiled wax raw oil is 1.2:1, and the second-point dilution temperature is 10°C.

[0082] The total dilution ratio of the first stage deoiling dilution solvent is 0.8:1, the filtration temperature of the first stage solvent deoiling is -5°C, the wax cake is cold washed with a -5°C first stage deoiling washing solvent, and the cold washing ratio is 0.5:1. After filtration, a first stage deoiled wax paste and a first stage deoiled filtrate are obtained.

[0083] The total dilution ratio of the second-stage deoiling dilution solvent is 1.5:1. The second-stage deoiling dilution solvent is added to the first-stage deoiling wax paste and mixed evenly. The temperature is adjusted. The filtration temperature of the second-stage solvent deoiling is 0°C. The wax cake is cold-washed with 0°C second-stage deoiling washing solvent. The cold washing ratio is 0.5:1. After filtration, the second-stage deoiling wax paste and the second-stage deoiling filtrate are obtained.

[0084] The total dilution ratio of the three-stage deoiling dilution solvent is 1.5:1. The three-stage deoiling dilution solvent is added to the two-stage deoiling wax paste and mixed evenly. The temperature is adjusted. The third-stage deoiling filtration temperature is 3°C. The wax cake is cold-washed with a 3°C three-stage deoiling washing solvent. The cold washing ratio is 0.5:1. After filtration, the three-stage deoiling wax paste and the three-stage deoiling filtrate are obtained.

[0085] After distillation and separation, the three-stage deoiled wax paste was obtained to obtain a low-melting-point, low-aromatic, environmentally friendly deoiled wax. The deoiled wax had an oil content of 0.66%, a yield of 27.3%, a melting point of 43°C, and a benzene content of 0.1785 μg·g -1 , toluene content 0μg·g -1 .

[0086] Example 2

[0087] This embodiment provides a method for preparing a low-melting-point, low-aromatic, environmentally friendly deoiled wax, which comprises the following steps:

[0088] The feedstock oil was 2# minus second-line distillate, the specific properties of which are shown in Table 1. A three-stage deoiling process was employed. The dilution solvent and wash solvent used during wax crystallization and three-stage solvent deoiling were both a mixture of methyl ethyl ketone and cyclohexane, with the methyl ethyl ketone content being 80% by weight and the cyclohexane content being 20% ​​by weight. The dilution ratio (the mass ratio of dilution solvent to feedstock oil) of the dilution solvent and the cold wash ratio (the mass ratio of wash solvent to feedstock oil) of the wash solvent were both relative to the feedstock oil.

[0089] Deoiled wax is prepared according to the process flow shown in Figure 1. The specific process is as follows: multi-point dilution is adopted (the raw oil is first melted at 60°C, and then multi-point dilution is performed during the solvent deoiling process by adding a dilution solvent multiple times), the melted raw oil is sequentially mixed with the dilution solvent, and the temperature is programmed to perform paraffin crystallization; when performing the first-point dilution, the mass ratio of the non-aromatic environmentally friendly deoiling solvent to the deoiled wax raw oil is 0.4:1, and the first-point dilution temperature is 30°C. When performing the second-point dilution, the mass ratio of the non-aromatic environmentally friendly deoiling solvent to the deoiled wax raw oil is 1.1:1, and the second-point dilution temperature is 8°C.

[0090] The total dilution ratio of the first stage deoiling dilution solvent is 0.8:1, the filtration temperature of the first stage solvent deoiling is -9°C, the wax cake is cold washed with a -9°C first stage deoiling washing solvent, and the cold washing ratio is 0.5:1. After filtration, a first stage deoiled wax paste and a first stage deoiled filtrate are obtained.

[0091] The total dilution ratio of the second-stage deoiling dilution solvent is 1:1. The second-stage deoiling dilution solvent is added to the first-stage deoiling wax paste and mixed evenly. The temperature is adjusted. The filtration temperature of the second-stage solvent deoiling is 0°C. The wax cake is cold-washed with 0°C second-stage deoiling washing solvent. The cold washing ratio is 0.5:1. After filtration, the second-stage deoiling wax paste and the second-stage deoiling filtrate are obtained.

[0092] The total dilution ratio of the three-stage deoiling dilution solvent is 1:1. The three-stage deoiling dilution solvent is added to the two-stage deoiled wax paste and mixed evenly. The temperature is adjusted. The filtration temperature of the third-stage solvent deoiling is 3°C. The wax cake is cold-washed with a 3°C three-stage deoiling washing solvent. The cold washing ratio is 0.5:1. After filtration, the three-stage deoiled wax paste and the three-stage deoiling filtrate are obtained.

[0093] After distillation and separation, the three-stage deoiled wax paste is separated to obtain a low-melting-point, low-aromatic, environmentally friendly deoiled wax. The deoiled wax has an oil content of 0.75%, a yield of 21.4%, a melting point of 41°C, and a benzene content of 0.1801 μg·g -1 , toluene content 0μg·g -1 .

[0094] Example 3

[0095] Unless otherwise specified, the feedstock oil, process, and other process conditions in this example are the same as those in Example 1. The differences are that the filtration temperature for the first stage of solvent deoiling is -1°C, and the temperature for the first stage of solvent deoiling and washing is -1°C. The oil content of the prepared deoiled wax is 0.51%, the yield is 25.6%, the melting point is 44°C, and the benzene content is 0.1633 μg·g -1 , toluene content 0μg·g -1 .

[0096] Example 4

[0097] Unless otherwise specified, the feedstock oil, process, and other process conditions in this example are the same as those in Example 1. The differences are that the filtration temperature for the first stage of solvent deoiling is -9°C, and the temperature for the first stage of solvent deoiling and cold washing is -9°C. The prepared deoiled wax has an oil content of 0.78%, a yield of 29.1%, a melting point of 42°C, and a benzene content of 0.1791 μg·g -1 , toluene content 0μg·g -1 .

[0098] Example 5

[0099] Unless otherwise specified, the raw oil, process and other process conditions in this example are the same as those in Example 1. The difference is that the filtration temperature of the second stage solvent deoiling is -5°C, and the temperature of the second stage deoiling solvent cold wash is -5°C. The oil content of the prepared deoiled wax is 0.79%, the yield is 30.7%, the melting point is 42°C, and the benzene content is 0.1899 μg·g -1 , toluene content 0μg·g -1 .

[0100] Example 6

[0101] Unless otherwise specified, the raw oil, process and other process conditions in this example are the same as those in Example 1. The difference is that the filtration temperature of the second stage solvent deoiling is 5°C, and the temperature of the second stage deoiling solvent cold wash is 5°C. The oil content of the prepared deoiled wax is 0.51%, the yield is 25.3%, the melting point is 44°C, and the benzene content is 0.1614 μg·g -1 , toluene content 0μg·g -1 .

[0102] Example 7

[0103] Unless otherwise specified, the feed oil, process, and other process conditions in this example are the same as those in Example 1. The differences are that the filtration temperature for the third stage of solvent deoiling is -1°C, and the temperature for the three-stage deoiling and washing solvent cold wash is -1°C. The prepared deoiled wax has an oil content of 0.76%, a yield of 28.4%, a melting point of 43°C, and a benzene content of 0.1766 μg·g -1 , toluene content 0μg·g -1 .

[0104] Example 8

[0105] Unless otherwise specified, the feed oil, process, and other process conditions in this example are the same as those in Example 1. The differences are that the filtration temperature for the third stage solvent deoiling is 7°C, and the temperature for the three-stage deoiling solvent cold wash is 7°C. The prepared deoiled wax has an oil content of 0.62%, a yield of 23.6%, a melting point of 44°C, and a benzene content of 0.1998 μg·g -1 , toluene content 0μg·g -1 .

[0106] Example 9

[0107] Unless otherwise specified, the raw oil, process and other process conditions in this example are the same as those in Example 2. The difference is that the filtration temperature of the second stage solvent deoiling is 5°C, and the temperature of the second stage deoiling solvent cold wash is 5°C. The oil content of the prepared deoiled wax is 0.70%, the yield is 16.77%, the melting point is 44°C, and the benzene content is 0.1694 μg·g -1, toluene content 0μg·g -1 .

[0108] Example 10

[0109] Unless otherwise specified, the feedstock oil, process, and other process conditions in this example are the same as those in Example 2. The differences are that the mass content of methyl ethyl ketone is 85%, the mass content of cyclohexane is 15%, the filtration temperature of the first stage of solvent deoiling is -5°C, and the temperature of the first stage of deoiling solvent cold wash is -5°C. The prepared deoiled wax has an oil content of 0.89%, a yield of 19.6%, a melting point of 42°C, and a benzene content of 0.2091 μg·g -1 , toluene content 0μg·g -1 .

[0110] Example 11

[0111] Unless otherwise specified, the raw material oil, process and other process conditions in this comparative example are all referenced to Example 2. The differences are that the mass content of methyl ethyl ketone is 85%, the mass content of cyclohexane is 15%, the filtration temperature of the first stage solvent deoiling is -5°C, and the temperature of the first stage deoiling washing solvent cold wash is -5°C. The total dilution ratio of the second stage deoiling dilution solvent is 1.5:1. The prepared deoiled wax has an oil content of 0.80%, a yield of 18.8%, a melting point of 44°C, and a benzene content of 0.1623 μg·g -1 , toluene content 0μg·g -1 .

[0112] Table 1 Properties of deoiled wax feedstock

[0113] It can be seen from the above Examples 1-11 that the technical solution of the present invention is suitable for producing low-melting-point, low-aromatic, environmentally friendly deoiled wax using reduced-pressure light wax oil as raw material through a solvent deoiling process. The use of a new low-boiling-point non-aromatic environmentally friendly deoiling solvent obtained by mixing methyl ethyl ketone and cyclohexane can achieve efficient separation of subsequent solvents; the deoiled wax obtained by the three-stage solvent deoiling process has the characteristics of low aromatics, low oil content, and low melting point (<52°C).

Claims

1. A preparation method of a low-melting-point and low-aromatic-hydrocarbon environmentally friendly dewaxing wax, wherein, the preparation method includes: performing wax crystallization on a mixture of a dewaxing wax raw material oil and a non-aromatic-hydrocarbon environmentally friendly dewaxing solvent to obtain a crystallized mixed material, and then performing a solvent dewaxing process to obtain the low-melting-point and low-aromatic-hydrocarbon environmentally friendly dewaxing wax; the non-aromatic-hydrocarbon environmentally friendly dewaxing solvent is a mixture of a C4 ketone and cyclohexane, wherein, based on the total mass of the mixture of the C4 ketone and cyclohexane, the content of the C4 ketone accounts for 45-95 wt%, and the content of cyclohexane accounts for 5-55 wt%.

2. The preparation method according to claim 1, wherein, the dewaxing wax raw material oil is a light wax oil fraction.

3. The preparation method according to claim 2, wherein, the light wax oil fraction is selected from the second reduced-line fraction oil of the primary processing of crude oil.

4. The preparation method according to claim 1, wherein, the C4 ketone is methyl ethyl ketone; based on the total mass of the mixture of methyl ethyl ketone and cyclohexane, the content of methyl ethyl ketone is 45-95 wt%, and the content of cyclohexane is 5-55 wt%.

5. The preparation method according to claim 1, wherein, the wax crystallization is performed by multi-point dilution for wax crystallization.

6. The preparation method according to claim 5, wherein, the multi-point dilution is two-point dilution, and the dilution conditions include: the first-point dilution temperature is 20-60 °C, and the second-point dilution temperature is 3-25 °C.

7. The preparation method according to claim 6, wherein, the dilution conditions further include: when performing the first-point dilution, the mass ratio of the non-aromatic-hydrocarbon environmentally friendly dewaxing solvent to the dewaxing wax raw material oil is 0.2-7.5:1, and when performing the second-point dilution, the mass ratio of the non-aromatic-hydrocarbon environmentally friendly dewaxing solvent to the dewaxing wax raw material oil is 0.5-7.5:

1.

8. The preparation method according to any one of claims 1-4, wherein, the solvent dewaxing process includes: under the first-stage dewaxing conditions, performing the first-stage solvent dewaxing on the mixture of the crystallized mixed material and the first-stage dewaxing dilution solvent to obtain a first-stage dewaxing wax paste and a first-stage dewaxing filtrate; under the second-stage dewaxing conditions, performing the second-stage solvent dewaxing on the mixture of the first-stage dewaxing wax paste and the second-stage dewaxing dilution solvent to obtain a second-stage dewaxing wax paste and a second-stage dewaxing filtrate; under the third-stage dewaxing conditions, performing the third-stage solvent dewaxing on the mixture of the second-stage dewaxing wax paste and the third-stage dewaxing dilution solvent to obtain a third-stage dewaxing wax paste and a third-stage dewaxing filtrate; after the third-stage dewaxing wax paste undergoes solvent separation, a low-melting-point and low-aromatic-hydrocarbon environmentally friendly dewaxing wax is obtained.

9. The preparation method according to claim 8, wherein, the process of the first-stage solvent dewaxing is: filtering the mixture of the crystallized mixed material and the first-stage dewaxing dilution solvent under the first-stage dewaxing conditions to obtain a first-stage dewaxing wax paste and a first-stage dewaxing filtrate.

10. The preparation method according to claim 9, wherein, the process of the first-stage solvent dewaxing further includes washing the first-stage dewaxing wax paste with a first-stage dewaxing washing solvent under the first-stage dewaxing conditions.

11. The preparation method according to claim 8, wherein, The first-stage deoiling dilution solvent includes one or a combination of two or more of non-aromatic hydrocarbon environmentally friendly deoiling solvents, second-stage deoiling filtrate, and third-stage deoiling filtrate.

12. According to the preparation method described in claim 10, wherein, The first-stage deoiling washing solvent includes one or a combination of two or more of non-aromatic hydrocarbon environmentally friendly deoiling solvents, second-stage deoiling filtrate, and third-stage deoiling filtrate.

13. According to the preparation method described in claim 8, wherein, The conditions for the first-stage solvent deoiling include: the temperature T1 of the first-stage solvent deoiling is -25°C to 20°C.

14. According to the preparation method described in claim 8 or 13, wherein, The conditions for the first-stage solvent deoiling further include: the mass ratio of the first-stage deoiling dilution solvent to the deoiled wax raw material oil is 0.5 - 4.0:

1.

15. According to the preparation method described in claim 10, wherein, The mass ratio of the first-stage deoiling washing solvent to the deoiled wax raw material oil is 0.1 - 3.0:

1.

16. According to the preparation method described in claim 8, wherein, The process of the second-stage solvent deoiling is: filtering the mixture of the first-stage deoiled wax paste and the second-stage deoiling dilution solvent under the second-stage deoiling conditions to obtain the second-stage deoiled wax paste and the second-stage deoiling filtrate.

17. According to the preparation method described in claim 16, wherein, The process of the second-stage solvent deoiling further includes washing the second-stage deoiled wax paste with the second-stage deoiling washing solvent under the second-stage deoiling conditions.

18. According to the preparation method described in claim 13, wherein, The conditions for the second-stage deoiling include: the temperature of the second-stage solvent deoiling is T2, and T2 - T1 = -6°C to 20°C.

19. According to the preparation method described in any one of claims 16 - 18, wherein, The conditions for the second-stage deoiling further include: the mass ratio of the second-stage deoiling dilution solvent to the deoiled wax raw material oil is 0.5 - 4.0:

1.

20. According to the preparation method described in claim 17, wherein, The mass ratio of the second-stage deoiling washing solvent to the deoiled wax raw material oil is 0.1 - 3.0:

1.

21. According to the preparation method described in claim 8, wherein, The process of the third-stage solvent deoiling is: filtering the mixture of the second-stage deoiled wax paste and the third-stage deoiling dilution solvent under the third-stage deoiling conditions to obtain the third-stage deoiled wax paste and the third-stage deoiling filtrate.

22. According to the preparation method described in claim 21, wherein, The process of the third-stage solvent deoiling further includes washing the third-stage deoiled wax paste with the third-stage deoiling washing solvent under the third-stage deoiling conditions.

23. According to the preparation method described in claim 16 or 17, wherein, The second-stage deoiling dilution solvent is a non-aromatic hydrocarbon environmentally friendly deoiling solvent and / or the third-stage deoiling filtrate.

24. According to the preparation method described in claim 21 or 22, wherein, The third-stage deoiling dilution solvent is a non-aromatic hydrocarbon environmentally friendly deoiling solvent and / or the third-stage deoiling filtrate.

25. According to the preparation method described in claim 17, wherein, The second-stage deoiling washing solvent is a non-aromatic hydrocarbon environmentally friendly deoiling solvent and / or the third-stage deoiling filtrate.

26. According to the preparation method described in claim 22, wherein, The three-stage deoiling washing solvent is a non-aromatic hydrocarbon environmentally friendly deoiling solvent and / or three-stage deoiling filtrate.

27. According to the preparation method described in claim 18, wherein, The conditions for the third-stage deoiling include: the temperature of the third-stage solvent deoiling is T3, and T3 - T2 = -6°C to 20°C.

28. According to the preparation method described in any one of claims 21-22 and 27, wherein, The conditions for the third-stage deoiling further include: the mass ratio of the third-stage deoiling dilution solvent to the feedstock oil is 0.5-4.0:

1.

29. According to the preparation method described in claim 22, wherein, The mass ratio of the three-stage deoiling washing solvent to the deoiled wax feedstock oil is 0.1-3.0:

1.

30. A low-melting-point, low-aromatic-hydrocarbon environmentally friendly deoiled wax, which is obtained by the preparation method described in any one of claims 1-29.

31. According to the deoiled wax described in claim 30, wherein, The melting point of the deoiled wax is less than 52°C.

32. According to the deoiled wax described in claim 30, wherein, The benzene content of the dewaxed oil is 0 - 0.49 μg·g -1 , and the toluene content is 0 - 4.9 μg·g -1 .

33. According to the deoiled wax described in claim 30, wherein, The oil content of the deoiled wax is 0.3%-2.0%.

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