A high calorific value biofuel and preparation method thereof

Abstract

The present invention provides a high calorific value biofuel and a preparation method thereof. The composite coating comprises the following raw materials by weight: 72-86 parts of industrial white oil, 6-8 parts of polyoxymethylene dimethyl ether, 25-29 parts of modified castor oil, 22-26 parts of modified palm oil, and 0.4-0.8 parts of antioxidant. The biofuel provided by the present invention has the advantages of good combustion performance and good antioxidant performance. Compared with biodiesel prepared from fatty acid methyl ester, it avoids the use of dangerous reagents such as methanol and is safer.

Description

Technical Field

[0001] The invention relates to the field of biofuels, in particular to a high calorific value biofuel. Background Art

[0002] As people pay more and more attention to environmental protection, finding renewable energy sources that can replace fossil fuels has become a research hotspot. Biodiesel is an important type of biofuel, which is composed of fatty acid methyl esters, which are produced by transesterification of fatty acid esters of plants and animals with methanol. Biodiesel has good combustion performance, but the raw material methanol used in its preparation is a hazardous reagent, which makes the production process of biodiesel dangerous. Industrial white oil, as a fuel oil, is a mixture of saturated alkanes. No hazardous reagents are used in its production process, so it can be used to replace fatty acid methyl esters to produce a safer biofuel.

[0003] The combustion performance of industrial white oil itself is average. By compounding with plant oils such as palm oil and castor oil, the combustion performance of the fuel can be improved, thereby producing a high calorific value biofuel. However, palm oil contains more unsaturated bonds, so it is easily oxidized, causing the fuel to deteriorate, thus affecting the shelf life of the biofuel. In addition, castor oil itself is not miscible with industrial white oil. This may be because castor oil itself has too high polarity, while the main component of industrial white oil is saturated alkanes, which have a lower polarity, so the two have poor solubility.

[0004] Patent CN202110490180 discloses a high calorific value coal-based biofuel. The biofuel prepared in this application is compounded with white oil and palm oil, thereby increasing the combustion calorific value of the fuel. However, it does not solve the problem that palm oil itself contains more unsaturated bonds and is therefore easily oxidized.

[0005] Therefore, there is an urgent need for a biofuel with good combustion performance and high oxidation resistance in the market. Summary of the invention

[0006] In view of the problems existing in the prior art, the object of the present invention is to provide a high calorific value biofuel and a preparation method thereof. The biofuel of the present invention is composed of industrial white oil, polyoxymethylene dimethyl ether, modified castor oil, modified palm oil and antioxidant, and has good combustion performance and oxidation resistance.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On one hand, the present invention provides a high calorific value biofuel, which comprises the following raw materials by weight: 72-86 parts of industrial white oil, 6-8 parts of polyoxymethylene dimethyl ether, 25-29 parts of modified castor oil, 22-26 parts of modified palm oil, and 0.4-0.8 parts of antioxidant.

[0009] In some embodiments of the present invention, the kinematic viscosity of the industrial white oil at 40°C is 12-20 mm 2 / s.

[0010] Different types of industrial white oil have different kinematic viscosities. When the kinematic viscosity is too high, the fluidity of the white oil is poor and it is inconvenient to transfer and transport; when the kinematic viscosity is too low, it may affect its combustion performance. The applicant selected a kinematic viscosity of 12-20 mm at 40 ° C. 2 / s of industrial white oil, which makes the fluidity and combustion properties of biofuel better.

[0011] The present invention does not impose any special restrictions on the source of the industrial white oil, which can be purchased commercially, including but not limited to the industrial white oil being 15# white oil purchased from Changzhou Heshili Chemical Co., Ltd.

[0012] In some embodiments of the present invention, the oxygen content of the polyoxymethylene dimethyl ether is 45%-50%.

[0013] Polyoxymethylene dimethyl ether is a commonly used fuel additive, which has a high oxygen content and cetane number and can promote the combustion of fuel. The applicant selects polyoxymethylene dimethyl ether with a specific oxygen content to make it better promote the combustion of fuel.

[0014] The present invention does not impose any special restrictions on the source of the polyoxymethylene dimethyl ether, which can be purchased commercially, including but not limited to polyoxymethylene dimethyl ether having an oxygen content of 47%-50%, purchased from Jinan Zhiheng Zhiyuan Chemical Technology Co., Ltd.

[0015] In some embodiments of the present invention, the method for preparing the modified castor oil comprises the following steps:

[0016] Add n-decanoic acid and concentrated sulfuric acid to castor oil, stir for 18-25 minutes, react at 78-88° C. for 4-6 hours, separate by column chromatography, and obtain modified castor oil.

[0017] Castor oil is a common vegetable oil with good combustion performance. It can be used in combination with other fuel oils to make the fuel have better combustion performance. However, castor oil and industrial white oil have poor compatibility. This may be because castor oil contains multiple hydroxyl groups and other functional groups in its structure, which has a higher polarity, while the main component of industrial white oil is saturated hydrocarbons with a lower polarity. Therefore, the polarity of the two is quite different, resulting in poor compatibility. The applicant modified castor oil by using decanoic acid. The carboxyl group of decanoic acid can undergo esterification reaction with the hydroxyl group of castor oil. On the one hand, the modification reaction converts the hydroxyl functional group with a larger polarity into the ester functional group with a relatively smaller polarity, thereby reducing the polarity of the modified castor oil. On the other hand, the modification also introduces an alkyl chain with a smaller polarity, thereby further reducing the polarity of the modified castor oil, so that the modified castor oil and industrial white oil have better compatibility. In addition, the applicant unexpectedly discovered that the modification reaction reduced the viscosity of the fuel. This may be because the modification reaction removed the hydroxyl groups in the castor oil structure, reducing the hydrogen bond content between molecules, resulting in a weakening of the intermolecular forces, thereby reducing the viscosity of the fuel and making the fuel easier to transfer and use.

[0018] The present invention does not impose any special restrictions on the source of the castor oil, which can be purchased commercially, including but not limited to the castor oil purchased from Jinan Huifengda Chemical Co., Ltd.

[0019] In some embodiments of the present invention, the mass ratio of castor oil to n-decanoic acid in the step is 1:(0.5-0.7).

[0020] Preferably, in the step, the mass ratio of castor oil to n-decanoic acid is 1:0.63.

[0021] The applicant adjusts the mass ratio of castor oil and n-decanoic acid to make the modified castor oil have good compatibility with industrial white oil and make the fuel have lower viscosity.

[0022] In some embodiments of the present invention, the method for preparing the modified palm oil comprises the following steps:

[0023] (1) adding 26-30 wt% aqueous hydrogen peroxide solution, glacial acetic acid and concentrated sulfuric acid to palm oil, stirring for 15-20 min, reacting at a temperature of 55-65° C. for 7-8 h, standing to separate layers, taking the upper oil phase, washing, and drying to obtain epoxidized palm oil;

[0024] (2) Add malonic acid to the epoxidized palm oil obtained in step (1), and react at a temperature of 88-93° C. for 4-5 hours to obtain modified palm oil.

[0025] The compound use of palm oil and industrial white oil can improve the combustion performance of white oil, but palm oil contains a large number of double bonds, which makes it easy to be oxidized, thereby reducing the shelf life of the fuel. The applicant first uses hydrogen peroxide aqueous solution and glacial acetic acid to react with palm oil. Hydrogen peroxide will oxidize glacial acetic acid to peracetic acid. Under the action of concentrated sulfuric acid as a catalyst, peracetic acid reacts with the double bonds of palm oil to form epoxidized palm oil. Malonic acid is then used to open the epoxy ring. One of the carboxyl groups of the malonic acid will form an ester bond to one of the carbon atoms of the epoxy group. At the same time, the epoxy ring opening will form a hydroxyl group on another carbon atom. On the one hand, the modification reaction removes most of the double bonds in palm oil, making it less susceptible to oxidation, thereby extending the shelf life of the fuel; on the other hand, the applicant unexpectedly discovered that the modification reaction improves the combustion performance of the fuel. This may be because only one carboxyl group of malonic acid participates in the ring-opening reaction, and the other carboxyl group and the hydroxyl group formed by the ring-opening significantly improve the chelating ability of the modified palm oil, which will react with the metal impurities in the industrial white oil to form organic metal salts, which not only removes the metal impurities, but also acts as a combustion promoter, thereby improving the combustion performance of the fuel.

[0026] The present invention does not impose any special restrictions on the source of the palm oil, which can be purchased commercially, including but not limited to the palm oil purchased from Hefei Tianjian Chemical Co., Ltd.

[0027] In some embodiments of the present invention, the mass ratio of palm oil, aqueous hydrogen peroxide solution and glacial acetic acid in step (1) is 1:(0.6-0.7):(0.2-0.4).

[0028] Preferably, in step (1), the mass ratio of palm oil, aqueous hydrogen peroxide solution and glacial acetic acid is 1:0.64:0.29.

[0029] The applicant minimizes the by-products of the epoxidized palm oil and maximizes the degree of epoxidation by adjusting the addition ratio of palm oil, aqueous hydrogen peroxide solution and glacial acetic acid.

[0030] In some embodiments of the present invention, the mass ratio of epoxidized palm oil to malonic acid in step (2) is 1:(0.8-1).

[0031] Preferably, in step (2), the mass ratio of epoxidized palm oil to malonic acid is 1:0.92.

[0032] The applicant adjusted the addition ratio of epoxidized palm oil and malonic acid to make the modified palm oil have better antioxidant properties and combustion performance.

[0033] In some embodiments of the present invention, the antioxidant is butylated hydroxyanisole or 6-tert-butyl-2,4-dimethylphenol.

[0034] Butylated hydroxyanisole or 6-tert-butyl-2,4-dimethylphenol is a commonly used antioxidant that can competitively bind oxygen, thereby delaying the oxidation process of the fuel bulk.

[0035] Another aspect of the present invention provides a method for preparing high calorific value biofuel, comprising the following steps:

[0036] Modified castor oil and modified palm oil are added to industrial white oil, and the mixture is stirred for 26-30 minutes. Polyoxymethylene dimethyl ether and an antioxidant are then added, and the mixture is stirred for 16-20 minutes to obtain the high calorific value biofuel.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The present invention compounds industrial white oil, modified castor oil and modified palm oil to improve the combustion performance of industrial white oil, and then adds polyoxymethylene dimethyl ether and an antioxidant to prepare a high calorific value biofuel. Compared with the production process of biodiesel, the biofuel is safer and avoids the use of dangerous reagents such as methanol. It also has the advantages of good combustion performance and high antioxidant performance.

[0039] (2) The present invention utilizes n-decanoic acid to modify castor oil. On the one hand, the modification converts the hydroxyl groups with a larger polarity into the ester groups with a relatively smaller polarity, and introduces the alkyl chains with a lower polarity, thereby significantly reducing the polarity of the modified castor oil and significantly improving its compatibility with industrial white oil. On the other hand, the applicant unexpectedly discovered that the viscosity of the fuel was reduced, which may be because the modification reaction removed a large number of hydroxyl groups, thereby significantly reducing the content of intermolecular hydrogen bonds, reducing the intermolecular interaction force, and thus reducing the viscosity of the fuel, making the fuel easier to transfer and use.

[0040] (3) The present invention firstly utilizes aqueous hydrogen peroxide solution, glacial acetic acid and concentrated sulfuric acid to react with palm oil so that most of the double bonds form epoxy groups, and then utilizes malonic acid to open the epoxy groups. On the one hand, the modification reaction removes most of the double bonds in the palm oil structure, thereby significantly improving its antioxidant properties; on the other hand, the applicant unexpectedly discovered that the combustion performance of the fuel is improved. This may be because another carboxyl group in the malonic acid structure and the hydroxyl group formed by the ring opening enhance the chelating ability of the modified palm oil, which combines with the metal impurities in the industrial white oil to form an organic metal salt, which not only removes the impurities, but also acts as a combustion accelerator, thereby improving the combustion performance of the fuel. DETAILED DESCRIPTION

[0041] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0042] In the following examples, except for modified castor oil and modified palm oil, the other compound monomers and related reagents used can be purchased from the market. Among them, the kinematic viscosity of industrial white oil at 40°C is 13.5-16.5 mm 2 / s, purchased from Changzhou Heshili Chemical Co., Ltd.; polyoxymethylene dimethyl ether with an oxygen content of 47%-50% was purchased from Jinan Zhiheng Zhiyuan Chemical Technology Co., Ltd.; castor oil was purchased from Jinan Huifengda Chemical Co., Ltd.; palm oil was purchased from Hefei Tianjian Chemical Co., Ltd.

[0043] Preparation Example 1

[0044] The preparation method of modified castor oil A comprises the following steps:

[0045] 3.3 g of n-decanoic acid and 0.6 ml of 80 wt % concentrated sulfuric acid were added to 5 g of castor oil, stirred for 20 min, reacted at 85° C. for 5 h, and separated by column chromatography to obtain modified castor oil A.

[0046] Preparation Example 2

[0047] Modified castor oil B is prepared in the same manner as modified castor oil A, except that 2 g of n-decanoic acid is added in the step.

[0048] Preparation Example 3

[0049] The preparation method of modified palm oil A comprises the following steps:

[0050] (1) Add 6.4 g of 30 wt% aqueous hydrogen peroxide solution, 2.9 g of glacial acetic acid and 0.4 ml of 85 wt% concentrated sulfuric acid to 10 g of palm oil, stir for 20 min, react at 62° C. for 8 h, stand for stratification, take the upper oil phase, wash with deionized water, dehydrate and dry to obtain epoxidized palm oil;

[0051] (2) Add 4.6 g of malonic acid to 5 g of the epoxidized palm oil obtained in step (1), and react at 90° C. for 5 h to obtain modified palm oil A.

[0052] Preparation Example 4

[0053] Modified palm oil B is prepared in the same manner as modified palm oil A, except that the mass of the aqueous hydrogen peroxide solution added in step (1) is 4.5 g.

[0054] Preparation Example 5

[0055] Modified palm oil C was prepared in the same manner as modified palm oil A, except that the mass of the aqueous hydrogen peroxide solution added in step (1) was 8.5 g.

[0056] Preparation Example 6

[0057] Modified palm oil D is prepared in the same manner as modified palm oil A, except that the mass of glacial acetic acid added in step (1) is 1.1 g.

[0058] Preparation Example 7

[0059] Modified palm oil E is prepared in the same manner as modified palm oil A, except that the mass of glacial acetic acid added in step (1) is 4.9 g.

[0060] Preparation Example 8

[0061] Modified palm oil F is prepared in the same manner as modified palm oil A, except that the mass of malonic acid added in step (2) is 3.1 g.

[0062] Example 1

[0063] A high calorific value biofuel comprises the following raw materials, measured by weight: 80 parts of industrial white oil, 7 parts of polyoxymethylene dimethyl ether, 27 parts of modified castor oil A, 24 parts of modified palm oil A and 0.6 parts of butylated hydroxyanisole.

[0064] Among them, modified castor oil A is prepared by Preparation Example 1, and modified palm oil A is prepared by Preparation Example 3.

[0065] The method for preparing high calorific value biofuel in this embodiment comprises the following steps:

[0066] Modified castor oil A and modified palm oil A are added to industrial white oil, and the mixture is stirred for 28 minutes. Polyoxymethylene dimethyl ether and butyl hydroxyanisole are then added, and the mixture is stirred for 18 minutes to obtain the high calorific value biofuel.

[0067] Example 2

[0068] A high calorific value biofuel comprises the following raw materials, measured by weight: 72 parts of industrial white oil, 6 parts of polyoxymethylene dimethyl ether, 27 parts of modified castor oil A, 24 parts of modified palm oil A, and 0.4 parts of 6-tert-butyl-2,4-dimethylphenol.

[0069] Among them, modified castor oil A is prepared by Preparation Example 1, and modified palm oil A is prepared by Preparation Example 3.

[0070] The method for preparing high calorific value biofuel in this embodiment comprises the following steps:

[0071] Modified castor oil A and modified palm oil A are added to industrial white oil, and the mixture is stirred for 26 minutes. Polymethoxy dimethyl ether and 6-tert-butyl-2,4-dimethylphenol are then added, and the mixture is stirred for 16 minutes to obtain the high calorific value biofuel.

[0072] Example 3

[0073] A high calorific value biofuel comprises the following raw materials, measured by weight: 86 parts of industrial white oil, 8 parts of polyoxymethylene dimethyl ether, 27 parts of modified castor oil A, 24 parts of modified palm oil A, and 0.8 parts of 6-tert-butyl-2,4-dimethylphenol.

[0074] Among them, modified castor oil A is prepared by Preparation Example 1, and modified palm oil A is prepared by Preparation Example 3.

[0075] The method for preparing high calorific value biofuel in this embodiment comprises the following steps:

[0076] Modified castor oil A and modified palm oil A are added to industrial white oil, and the mixture is stirred for 30 minutes. Polyoxymethylene dimethyl ether and 6-tert-butyl-2,4-dimethylphenol are then added, and the mixture is stirred for 20 minutes to obtain the high calorific value biofuel.

[0077] Example 4

[0078] A high calorific value biofuel comprises the following raw materials, measured by weight: 78 parts of industrial white oil, 6.5 parts of polyoxymethylene dimethyl ether, 25 parts of modified castor oil A, 26 parts of modified palm oil A and 0.5 parts of butylated hydroxyanisole.

[0079] Among them, modified castor oil A is prepared by Preparation Example 1, and modified palm oil A is prepared by Preparation Example 3.

[0080] The method for preparing high calorific value biofuel in this embodiment is the same as that in Embodiment 1.

[0081] Example 5

[0082] A high calorific value biofuel comprises the following raw materials, measured by weight: 82 parts of industrial white oil, 7.5 parts of polyoxymethylene dimethyl ether, 29 parts of modified castor oil A, 22 parts of modified palm oil A, and 0.7 parts of butylated hydroxyanisole.

[0083] Among them, modified castor oil A is prepared by Preparation Example 1, and modified palm oil A is prepared by Preparation Example 3.

[0084] The preparation method of high calorific value biofuel in this example is the same as that in Example 1.

[0085] Example 6

[0086] A high calorific value biofuel and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that modified castor oil A is replaced by modified castor oil B in equal amounts, wherein modified castor oil B is prepared by Preparation Example 2.

[0087] Example 7

[0088] A high calorific value biofuel and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that modified palm oil A is replaced by modified palm oil B in equal amounts, wherein modified palm oil B is prepared by Preparation Example 4.

[0089] Example 8

[0090] A high calorific value biofuel and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that modified palm oil C is used to replace modified palm oil A in equal amounts, wherein modified palm oil C is prepared by Preparation Example 5.

[0091] Example 9

[0092] A high calorific value biofuel and a preparation method thereof. The specific implementation method is the same as Example 1, except that modified palm oil A is replaced by modified palm oil D in equal amounts, wherein modified palm oil D is prepared by Preparation Example 6.

[0093] Example 10

[0094] A high calorific value biofuel and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that modified palm oil A is replaced by modified palm oil E in equal amounts, wherein the modified palm oil E is prepared by Preparation Example 7.

[0095] Embodiment 11

[0096] A high calorific value biofuel and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that modified palm oil F is used to replace modified palm oil A in equal amounts, wherein modified palm oil F is prepared by Preparation Example 8.

[0097] Comparative Example 1

[0098] A biofuel and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the modified castor oil A is replaced by an equal amount of commercially available conventional castor oil.

[0099] Comparative Example 2

[0100] A biofuel and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that the modified palm oil A is replaced by an equal amount of commercially available conventional palm oil.

[0101] Performance Testing

[0102] (1) Combustion performance

[0103] The combustion performance of a fuel is evaluated by measuring the combustion calorific value of the fuel using an oxygen bomb calorimeter. The greater the combustion calorific value, the better the combustion performance of the fuel.

[0104] (2) Antioxidant properties

[0105] The induction period of the fuel is measured using the fully automatic oil oxidation stability tester EN14112 (product model: KD-R2223). The induction period refers to the time that the fuel is in a stable state under specified oxidation conditions. The longer the induction period, the better the fuel's antioxidant properties.

[0106] (3) Viscosity

[0107] The kinematic viscosity of the fuel is measured according to the test method of standard GB / T 265-1988. The greater the kinematic viscosity, the greater the viscosity of the fuel.

[0108] The combustion performance, antioxidant performance and viscosity of the biofuels prepared in Examples 1-11 and Comparative Examples 1-2 were tested according to the above test methods. The test results are shown in Table 1.

[0109] Table 1

[0110] Group Combustion heat value (kJ / kg) Induction period (h) <![CDATA[Kinematic viscosity (mm 2 / s)]]> Example 1 46809 14.5 18.3 Example 2 46792 14.4 18.5 Example 3 46787 14.3 18.6 Example 4 46771 14.4 18.8 Example 5 46773 14.2 18.7 Example 6 46689 13.5 20.8 Example 7 46713 12.3 19.1 Example 8 46725 13.9 19.3 Example 9 46705 12.1 19.3 Example 10 46721 13.8 19.4 Embodiment 11 46702 13.8 19.5 Comparative Example 1 46513 13.1 21.9 Comparative Example 2 46685 10.8 19.7

[0111] As shown in Table 1, the biofuels in Examples 1-5 of the present invention have the advantages of good combustion performance and good antioxidant performance, and have low viscosity. Among them, Example 6 reduces the amount of n-decanoic acid used, which affects the progress of the modification reaction, so that there are still more hydroxyl groups in the structure of the modified castor oil, resulting in insufficient decrease in the polarity of the modified castor oil, and the miscibility with industrial white oil is general, which makes the combustion of the fuel uneven, the combustion performance is reduced, and because the miscibility of the system is reduced, its stability is also reduced, so that the antioxidant performance of the fuel is slightly reduced. In addition, because the modified castor oil contains more unreacted hydroxyl groups, intermolecular hydrogen bonds will be formed, thereby increasing the viscosity of the fuel; in Example 7, the amount of hydrogen peroxide aqueous solution is not enough, so that the epoxidation reaction is not carried out thoroughly, and more double bonds are still retained in the modified palm oil, which significantly reduces the viscosity of the fuel. The antioxidant performance of the fuel is reduced, and due to the insufficient degree of epoxidation, the amount of carboxyl and hydroxyl groups formed by the ring-opening of malonic acid is reduced, and the chelating ability with metal ions is weakened, which makes the effect of the organic metal salt as a combustion promoter worse, thereby reducing its combustion performance; in Example 8, the amount of hydrogen peroxide aqueous solution is too much, although most of the double bonds are consumed by the reaction, the by-products of the epoxidation reaction are increased, the content of epoxidized palm oil that can react with the ring-opening of malonic acid is reduced, thereby reducing the chelating ability of the modified palm oil, and the effect of the organic metal salt as a combustion promoter is worse, thereby reducing its combustion performance; in Example 9, the amount of glacial acetic acid used is too little, which makes the epoxidation reaction The reaction was not carried out thoroughly, and the modified palm oil still contained a large number of double bonds, thereby reducing the antioxidant performance of the fuel. In addition, due to the insufficient degree of epoxidation, the amount of carboxyl and hydroxyl groups formed by the ring-opening of malonic acid was reduced, and the chelating ability with metal ions was weakened, thereby reducing its combustion performance; in Example 10, the amount of glacial acetic acid used was too much. Although most of the double bonds were completely reacted, the by-products of the reaction increased, thereby reducing the chelating ability of the modified palm oil, making the effect of the organic metal salt as a combustion promoter worse, thereby reducing its combustion performance; in Example 11, the amount of malonic acid used was too little, so the ring-opening reaction was not carried out thoroughly, thereby reducing the chelating ability of the modified palm oil, thereby reducing its Combustion performance; Comparative Example 1 uses commercially available conventional castor oil to replace modified castor oil, which makes it very poorly miscible with industrial white oil, resulting in uneven combustion of the fuel, significantly reducing its combustion calorific value, and due to the poor miscibility of the system, the stability is reduced, thereby slightly reducing the antioxidant performance, and conventional castor oil contains a large number of hydroxyl groups, forming a large number of hydrogen bonds between molecules, thereby increasing the viscosity of the fuel; Comparative Example 2 uses commercially available conventional palm oil to replace modified palm oil, which significantly reduces the antioxidant performance of the fuel, and since no modification reaction is performed, it is difficult to chelate metal impurities in industrial white oil and cannot play the role of a combustion accelerator, thereby reducing the combustion performance of the fuel.

[0112] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A high calorific value biofuel, characterized in that: The raw materials include the following in parts by weight: 72-86 parts of industrial white oil, 6-8 parts of polyoxymethylene dimethyl ether, 25-29 parts of modified castor oil, 22-26 parts of modified palm oil, and 0.4-0.8 parts of antioxidant; The preparation method of the modified castor oil comprises the following steps: Adding n-decanoic acid and concentrated sulfuric acid to castor oil, stirring for 18-25 minutes, reacting at a temperature of 78-88° C. for 4-6 hours, and separating by column chromatography to obtain modified castor oil; in the step, the mass ratio of castor oil to n-decanoic acid is 1:(0.5-0.7); The preparation method of the modified palm oil comprises the following steps: (1) adding 26-30 wt% aqueous hydrogen peroxide solution, glacial acetic acid and concentrated sulfuric acid to palm oil, stirring for 15-20 min, reacting at 55-65° C. for 7-8 h, standing to separate layers, taking the upper oil phase, washing, and drying to obtain epoxidized palm oil; (2) Add malonic acid to the epoxidized palm oil obtained in step (1), and react at a temperature of 88-93° C. for 4-5 hours to obtain modified palm oil; in step (2), the mass ratio of epoxidized palm oil to malonic acid is 1:(0.8-1).

2. A high calorific value biofuel according to claim 1, characterized in that: The kinematic viscosity of the industrial white oil at 40°C is 12-20 mm 2 / s.

3. A high calorific value biofuel according to claim 1, characterized in that: The oxygen content of the polyoxymethylene dimethyl ether is 45%-50%.

4. The high calorific value biofuel according to claim 1, characterized in that: In the step (1), the mass ratio of palm oil, aqueous hydrogen peroxide solution and glacial acetic acid is 1:(0.6-0.7):(0.2-0.4).

5. The high calorific value biofuel according to claim 1, characterized in that: The antioxidant is butylated hydroxyanisole or 6-tert-butyl-2,4-dimethylphenol.

6. A method for preparing a high calorific value biofuel according to any one of claims 1 to 5, characterized in that: The steps include: Modified castor oil and modified palm oil are added to industrial white oil, and the mixture is stirred for 26-30 minutes. Polyoxymethylene dimethyl ether and an antioxidant are then added, and the mixture is stirred for 16-20 minutes to obtain the high calorific value biofuel.