A method for the high-value utilization of plant asphalt by-produced from biodiesel

Abstract

The present invention discloses a method for the high-value utilization of plant asphalt by-produced from biodiesel. The technological steps are as follows: Using the plant asphalt by-produced in the biodiesel production process as raw material, first carry out a high-temperature gasification reaction to produce syngas, and then successively go through cooling, purification, and component modulation to obtain high-purity syngas mainly composed of hydrogen and carbon monoxide. After being compressed by a compressor, it is stored in a high-pressure storage tank; the high-purity syngas in the high-pressure storage tank is introduced into a fixed-bed reactor filled with a catalyst for Fischer-Tropsch synthesis reaction, so that the syngas reacts and is converted into hydrocarbon liquid fuel. The technological method of the present invention can convert the plant asphalt with complex components and difficult to handle by-produced from biodiesel into hydrocarbon liquid fuel with high added value, can achieve the complete conversion of plant asphalt to the greatest extent, and can effectively improve the utilization value of plant asphalt and the production efficiency of biodiesel.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil chemical engineering, and particularly relates to a method for the high-value utilization of plant asphalt by-produced from biodiesel. Background Art

[0002] Biodiesel is a green and renewable energy source with excellent characteristics such as high energy density, safe storage and transportation, good anti-knock performance, and complete combustion. At present, biodiesel is generally produced from waste oils and fats by an acid-base two-step method or a glycerol esterification method in industry. During the production of biodiesel, a large amount of plant asphalt will remain in the bottom of the tower after the rectification of the crude product. Its components are mainly fatty acid methyl esters, phytosterols, natural vitamin E, etc. Plant asphalt has the characteristics of complex composition, high viscosity, and dark color, making it difficult to recycle and utilize. In industry, plant asphalt is often blended with matrix asphalt and used in road engineering, with a relatively low utilization value. Therefore, converting plant asphalt into high-value-added chemicals is beneficial to improving the economic benefits of biodiesel enterprises and promoting the development of the biodiesel industry.

[0003] Chinese Patent CN105001297 A extracts phytosterols from plant asphalt through processes such as hydrolysis, esterification, distillation, saponification, and solvent extraction. Chinese Patents CN103666769 A and CN104232324 A adopt a combination of esterification reaction and centrifugation / sedimentation separation to extract fatty acid methyl esters from plant asphalt. However, the above methods for extracting phytosterols or fatty acid methyl esters from plant asphalt cannot achieve the complete and full utilization of plant asphalt, resulting in partial waste of resources. Chinese Patent CN112552947 A obtains biodiesel and components such as white oil, liquid paraffin, lubricating oil base oil, bio-light oil, bio-aviation kerosene, and bio-heavy oil by a two-step hydrogenation process of plant asphalt. Chinese Patent CN110129086 B uses modified hydrotalcite as a catalyst to catalytically crack plant asphalt and prepares bio-aviation kerosene by distillation separation. However, the products of the above methods for converting plant asphalt into high-value-added chemicals through hydrogenation or cracking have complex compositions and also cannot achieve the complete conversion of raw materials. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies existing in the prior art and provide a method for the high-value utilization of plant asphalt by-produced from biodiesel, which is a new method for converting plant asphalt into high-value-added hydrocarbon liquid fuels.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The described method for the high-value utilization of plant asphalt by-produced from biodiesel has the following technological steps: Using the plant asphalt by-produced during the production of biodiesel as the raw material, first conduct a high-temperature gasification reaction to produce synthesis gas, and then successively go through cooling, purification, and composition modulation to obtain high-purity synthesis gas mainly composed of hydrogen and carbon monoxide. After being compressed by a compressor, it is stored in a high-pressure storage tank; the high-purity synthesis gas in the high-pressure storage tank is introduced into a fixed-bed reactor filled with a catalyst for the Fischer-Tropsch synthesis reaction, converting the synthesis gas into hydrocarbon liquid fuel.

[0007] Furthermore, the plant asphalt is derived from the by-product generated during the production of biodiesel from waste oil through the two-step acid-base method or the glycerol esterification method, that is, the plant asphalt remaining in the bottom of the column after the crude biodiesel product obtained from production is rectified; among them, the main components of the plant asphalt are fatty acid methyl esters, phytosterols, and natural vitamin E, and the mass content of fatty acid methyl esters is above 50%.

[0008] Furthermore, the high-temperature gasification reaction adopts the methods of fixed-bed gasification, fluidized-bed gasification, microwave heating gasification, plasma gasification, or molten salt gasification. The gasifying agent is air, oxygen, or steam. The mass ratio of the raw material to the gasifying agent is 1:1 to 1:3, and the gasification temperature is 500 to 1200 °C, preferably 800 to 1000 °C.

[0009] Furthermore, after the gas produced by the high-temperature gasification reaction is cooled, purified, and composition-modulated, the total volume content of hydrogen and carbon monoxide in the obtained high-purity synthesis gas exceeds 95%, the hydrogen sulfide content is lower than 100 ppb, and the volume ratio of hydrogen to carbon monoxide is 1:2 to 4:1.

[0010] Furthermore, the purification and composition modulation process of the gas produced by the gasification reaction includes one process or a combination of several processes such as water washing, organic solvent washing, CO2 absorption, activated carbon adsorption, dust removal, and steam reforming reaction; among them, the steam reforming reaction is carried out under an excessive steam environment and catalyzed by a nickel-based catalyst, and the catalytic reaction temperature is 700 to 900 °C.

[0011] Furthermore, the Fischer-Tropsch synthesis reaction is carried out in a fixed-bed, fluidized-bed, or slurry-bed reactor, the reaction temperature is 200 to 350 °C, and the reaction pressure is 1 to 4 MPa.

[0012] Furthermore, the active components of the catalyst for the Fischer-Tropsch synthesis reaction are one or several of iron, cobalt, nickel, ruthenium, and rhodium, and the catalyst carrier is molecular sieve, aluminosilicate, or carbon functional material.

[0013] Furthermore, the hydrocarbon liquid fuel is a mixed hydrocarbon with different carbon atom numbers, and the content of hydrocarbon fuels with carbon atoms above C5 is above 85%, and it can be further divided into gasoline, diesel, and kerosene.

[0014] By adopting the above technologies, compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] 1. The complex and difficult-to-treat plant asphalt by-produced from biodiesel is converted into syngas through high-temperature gasification, and then high-value-added hydrocarbon liquid fuels are obtained through the Fischer-Tropsch synthesis reaction, which can effectively improve the utilization value of plant asphalt and the production efficiency of biodiesel.

[0016] 2. Using gasification technology to treat plant asphalt can achieve the complete conversion of plant asphalt to the greatest extent, obtaining syngas with relatively high purity. The syngas can be used as the feed gas for the Fischer-Tropsch synthesis reaction after simple purification and component modulation.

[0017] 3. The hydrocarbon liquid fuel produced by the Fischer-Tropsch synthesis reaction from syngas has a relatively high calorific value, and gasoline, diesel, or kerosene single-range hydrocarbon fuels can be obtained by regulating the Fischer-Tropsch synthesis reaction conditions or product fractionation, further improving the product value. Specific Embodiments

[0018] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0019] Example 1:

[0020] The main component of the plant asphalt by-produced from biodiesel is fatty acid methyl ester, with a content of 70%. In addition, it also contains 10% of phytosterols, 5% of natural vitamin E, and a small amount of other high-boiling compounds and impurities.

[0021] The steps for the high-value utilization of plant asphalt are as follows:

[0022] (1) High-temperature gasification: 10 kg of plant asphalt raw material and a gasifying agent are fed into a fluidized bed gasifier for gasification reaction. The gasification temperature is 850 °C. Steam is used as the gasifying agent and fluidization medium, and the mass ratio of steam to plant asphalt raw material is 2:1. Finally, 10.5 m 3 of syngas is obtained. The syngas contains 49% hydrogen, 34% carbon monoxide, 12% carbon dioxide, 4.5% methane, 0.1% hydrogen sulfide, and a small amount of other impurities;

[0023] (2) Purification and component modulation: After the syngas is cooled, it undergoes processes such as water washing, methanol washing, steam reforming (carried out under an excessive steam environment and catalyzed by a 5% Ni / Al2O3 catalyst at a reaction temperature of 800 °C), calcium lime absorption, activated carbon adsorption, and dust removal. The hydrogen content in the syngas is 68%, the carbon monoxide content is 31%, and the hydrogen sulfide content is less than 40 ppb. The final syngas is compressed by a compressor and stored in a high-pressure storage tank;

[0024] (3) Fischer-Tropsch synthesis reaction: The syngas in the high-pressure storage tank is introduced into a fixed-bed reactor for Fischer-Tropsch synthesis reaction. The catalyst is 20% Co / SiO2, the reaction temperature is 220 °C, and the reaction pressure is 2 MPa. Hydrocarbon liquid fuels can be obtained. The final CO conversion rate is 68%, and the selectivity of hydrocarbons with C5 and above is 89%. The gasoline (C5~C 12 ), kerosene (C8~C 16 ), and diesel (C 10 ~C 20 ) component contents in the obtained hydrocarbon fuels are 30%, 47%, and 56% respectively.

[0025] Through the above steps, the biodiesel by-product plant asphalt can be converted into high-value-added hydrocarbon liquid fuels. Based on the plant asphalt, the mass yield of the obtained syngas can reach 90%, and the single-pass mass yield of the hydrocarbon liquid fuel is 54%.

[0026] Example 2:

[0027] The main component of the biodiesel by-product plant asphalt is fatty acid methyl ester, with a content of 70%. In addition, it also contains 10% of phytosterol, 5% of natural vitamin E, and a small amount of other high-boiling compounds and impurities.

[0028] The steps for the high-value utilization of plant asphalt are as follows:

[0029] (1) High-temperature gasification: 10 kg of plant asphalt raw material and the gasifying agent are introduced into a fluidized-bed gasifier for gasification reaction. The gasification temperature is 950 °C. Steam is used as the gasifying agent and fluidization medium. The feeding mass ratio of steam to plant asphalt raw material is 2:1. Finally, 11.2 m 3 of syngas is obtained. The syngas contains 52% of hydrogen, 31% of carbon monoxide, 12.5% of carbon dioxide, 4% of methane, 0.1% of hydrogen sulfide, and a small amount of other impurities;

[0030] (2) Purification and component modulation: After the syngas is cooled, it undergoes processes such as water washing, methanol washing, steam reforming (carried out under the catalysis of a 5% Ni / Al2O3 catalyst in an excessive steam environment, with a reaction temperature of 800 °C), calcium lime absorption, activated carbon adsorption, and dust removal. The hydrogen content in the syngas is 72%, the carbon monoxide content is 27%, and the hydrogen sulfide content is less than 30 ppb. The final syngas is compressed by a compressor and stored in a high-pressure storage tank;

[0031] (3) Fischer-Tropsch synthesis reaction: The syngas in the high-pressure storage tank is introduced into the slurry bed reactor for the Fischer-Tropsch synthesis reaction. The catalyst is 25% Co - 0.5% Ru / HZSM-5, the reaction temperature is 220 °C, and the reaction pressure is 2 MPa. Hydrocarbon liquid fuels can be obtained. The final CO conversion rate is 79%, and the selectivity of hydrocarbons with C5 and above is 93%. The component contents of gasoline (C5~C 12 ), kerosene (C8~C 16 ), and diesel (C 10 ~C 20 ) in the obtained hydrocarbon fuels are 34%, 49%, and 53% respectively.

[0032] Through the above steps, the by-product plant asphalt of biodiesel can be converted into high-value-added hydrocarbon liquid fuels. Based on the plant asphalt, the mass yield of the obtained syngas can reach 95%, and the single-pass mass yield of the hydrocarbon liquid fuel is 70%.

[0033] The content described in this specification is only a list of the implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments.

Claims

1. A method for the high-value utilization of biodiesel by-product plant asphalt, characterized in that The process steps are as follows: Using the plant asphalt by-produced in the biodiesel production process as raw material, first conduct a high-temperature gasification reaction to produce syngas, and then successively pass through cooling, purification, and composition modulation to obtain high-purity syngas composed of hydrogen and carbon monoxide. After being compressed by a compressor, it is stored in a high-pressure storage tank; the high-purity syngas in the high-pressure storage tank is introduced into a fixed-bed reactor filled with a catalyst for Fischer-Tropsch synthesis reaction, so that the syngas reacts to be converted into hydrocarbon liquid fuel. The plant asphalt is a by-product generated in the process of producing biodiesel from waste oil through the two-step acid-base method or glycerol esterification method, that is, the plant asphalt remaining in the bottom of the tower after the crude biodiesel product obtained by production is rectified; among them, the main components of the plant asphalt are fatty acid methyl esters, phytosterols, and natural vitamin E, and the mass content of fatty acid methyl esters is more than 50%. After the gas produced by the high-temperature gasification reaction is cooled, purified, and composition-modulated, the total volume content of hydrogen and carbon monoxide in the obtained high-purity syngas exceeds 95%, the hydrogen sulfide content is lower than 100 ppb, the hydrogen content in the syngas is 68%, and the carbon monoxide content is 31%. The purification and composition modulation process of the gas produced by the gasification reaction includes one process or a combination of several processes such as water washing, organic solvent washing, CO2 absorption, activated carbon adsorption, dust removal, and steam reforming reaction; among them, the steam reforming reaction is carried out under an excessive steam environment and catalyzed by a nickel-based catalyst, and the catalytic reaction temperature is 700-900 °C.

2. The high-value utilization method of plant asphalt by-produced from biodiesel according to claim 1, characterized in that The high-temperature gasification reaction adopts the methods of fixed-bed gasification, fluidized-bed gasification, microwave heating gasification, plasma gasification, or molten salt gasification. The gasifying agent is air, oxygen, or steam, the mass ratio of the raw material to the gasifying agent is 1:1-1:3, and the gasification temperature is 500-1200 °C.

3. The method for high-value utilization of plant asphalt by-produced from biodiesel according to claim 2, characterized in that The gasification temperature is 800-1000 °C.

4. The high-value utilization method of plant asphalt by-produced from biodiesel as described in claim 1, wherein The Fischer-Tropsch synthesis reaction is carried out in a fixed-bed, fluidized-bed, or slurry-bed reactor, the reaction temperature is 200-350 °C, and the reaction pressure is 1-4 MPa.

5. The method for high-value utilization of plant asphalt by-produced from biodiesel according to claim 4, characterized in that The active components of the catalyst for the Fischer-Tropsch synthesis reaction are one or several of iron, cobalt, nickel, ruthenium, and rhodium, and the catalyst carrier is molecular sieve, aluminosilicate, or carbon functional material.

6. The method for high-value utilization of plant asphalt by-produced from biodiesel according to claim 1, characterized in that The hydrocarbon liquid fuel is a mixed hydrocarbon with different carbon atom numbers, and the content of hydrocarbon fuel with carbon atoms above C5 is more than 85%.