Circulating production method for preparing biological aviation kerosene from waste oil

Abstract

The invention discloses a cyclic production method for preparing biological aviation kerosene from waste oil and fat. The method comprises the following steps: 1) removing solid impurities from the waste grease, mixing the waste grease with a heteropolyacid catalyst, a vulcanizing agent and H2, introducing the mixture into a suspended bed reactor, and carrying out a one-step hydrodeoxygenation-isomerization reaction to generate a product I; 2) separating a liquid phase I and a solid phase from the product I, introducing the liquid phase I into an oil-water separator, and separating an oil phase and a water phase; 3) returning the solid phase and the oil phase to the suspended bed reactor, and carrying out hydrodeoxygenation-isomerization again to generate a product II; and 3) separating a liquid phase II and a solid phase II from the product II, feeding the solid phase II into a reactor for recycling, and feeding the liquid phase II into a fractionating tower to separate out the biological aviation kerosene. According to the invention, the problem of frequent shutdown caused by catalyst deactivation in the traditional fixed bed process is solved, and the process also has the characteristics of wide raw oil adaptability, simple process flow, low equipment investment cost, high conversion rate, low coke yield and the like, and has great industrial application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic conversion of bio-oil, and in particular relates to a cyclic production process for preparing bio-jet fuel from waste oil. Background Art

[0002] The main methods for converting waste oils and fats into biofuels include transesterification, high-temperature pyrolysis, and hydrodeoxygenation. The transesterification method uses an acidic or alkaline catalyst (such as NaOH / KOH or solid acid) to esterify the free fatty acids in the oil with methanol / ethanol to produce fatty acid methyl or ethyl esters. However, it consumes high energy (approximately 15 kWh / kg) and requires the treatment of corrosive wastewater (containing glycerol and catalyst residues). High-temperature pyrolysis decomposes oils and fats into bio-oil under anaerobic conditions (300-500°C). However, the resulting bio-oil has a high oxygen content (30%-50%), requiring complex processing and poor economic efficiency. Hydrodeoxygenation involves hydrocracking oils and fats at high temperatures (200-350°C), high pressures (5-20 MPa), and hydrogen to produce hydrocarbon fuels (such as aviation kerosene and diesel), while removing oxygen, sulfur, and nitrogen impurities. However, this method is associated with catalyst deactivation and high equipment investment.

[0003] In summary, developing a new method for producing biodiesel and aviation fuel has important practical significance and broad application prospects. Summary of the Invention

[0004] This invention aims to address the complexities of existing processes and their difficulty in long-term stable operation. It provides a cyclic production process for producing bio-jet fuel from waste oils and fats. This process is stable and reliable, highly adaptable to feedstocks, and allows for the recycling of hydrogen and catalysts. Furthermore, requiring only a single reactor, a single-step hydrodeoxygenation-isomerization reaction can be achieved by varying reaction conditions, ensuring long-term system operation.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A recycling production process for preparing bio-jet fuel from waste oil and fat, comprising the following steps: (1) The waste oil is preheated and dissolved, and then passed through a filter 1 to filter out the solid residue. The waste oil is then subjected to a one-step hydrodeoxygenation-isomerization reaction with a sulfiding agent and a heteropolyacid catalyst HPA@SiO2 in a suspended bed reactor 2 to obtain a mixed product I. (2) The mixed product I is separated into a solid phase I and a liquid phase I through a solid-liquid separator 3. The liquid phase product I is passed into an oil-water separator 4 to separate the oil phase and the water phase. The solid phase and the oil phase are returned to the suspended bed reactor 2 and are subjected to hydrodeoxygenation-isomerization again to generate product II. (3) Product II is passed into the solid-liquid separator 3 to separate the liquid phase II and the solid phase II. The solid phase II is fed into the suspended bed reactor 2 for recycling, and the liquid phase II is passed into the fractionation tower 5 to separate the bio-jet fuel. Preferably, the waste oil in step (1) includes but is not limited to one of acidified oil, swill oil, and gutter oil.

[0006] Preferably, the vulcanizing agent in step (1) includes but is not limited to one of sulfur powder, carbon disulfide, dimethyl disulfide and H2S.

[0007] Preferably, the HPA in the heteropolyacid catalyst HPA@SiO2 in step (1) is a heteropolyacid (including but not limited to phosphotungstic acid and phosphomolybdic acid), and the specific synthesis steps are as follows: Preferably, (1) a heteropoly acid and CTAB in a mass ratio of 3:1 are mixed with a certain amount of anhydrous ethanol, deionized water, and ammonia water, and stirred for 2 hours; the volume ratio of anhydrous ethanol, deionized water, and ammonia water is 10:8:2.5.

[0008] (2) Tetraethyl silicate was added dropwise to the solution obtained in step (1), and the mixture was stirred for 48 h. The mixture was centrifuged, and the precipitate was washed with ethanol and water, dried overnight, and finally calcined at 550°C for 3 h to obtain HPA@SiO2; the amount of tetraethyl silicate used was such that the molar ratio of SiO2 in tetraethyl silicate to HPA was 1:2.

[0009] The amount of the heteropolyacid catalyst used in step (1) is 5-10 wt% of the waste oil.

[0010] The mass ratio of the vulcanizing agent to the waste oil in step (1) is (0.05~0.5):100.

[0011] The reaction pressure of the suspended bed reactor in step (1) is 2-6 MPa, the reaction temperature is 300-400 °C, and the liquid hourly space velocity is 0.5-8 h -1 , the hydrogen-to-oil ratio is 600~1200.

[0012] The operating temperature of the solid-liquid separator in steps (2) and (3) is 80-150°C, and the operating pressure is 0.5-2 MPa.

[0013] The operating temperature of the oil-water separator in step (2) is 20-40° C., and the operating pressure is 0.08-0.15 MPa.

[0014] The reaction pressure of the suspended bed reactor in step (2) is 4-8 MPa, the reaction temperature is 300-400°C, and the liquid hourly space velocity is 0.2-8 h -1 , the hydrogen-to-oil ratio is 600~1200.

[0015] The fractionation tower in step (3) is of sieve plate type or packed type, with a bottom temperature of 250-400°C and an operating pressure of 0.1-0.6 MPa.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The process flow of this technology is simple, stable and reliable, and the raw materials are highly adaptable. The use of a recycling process can greatly save equipment investment costs, solve the problem of catalyst deactivation caused by excessively high acid values, and achieve long-term stable operation of the system.

[0017] (2) The present invention has a good catalytic conversion efficiency of oil and fat, and a low coke rate (about 5%, see Figure 2 ), the alkane yield can reach more than 90%, of which the isoparaffin yield reaches more than 40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the process flow for preparing bio-jet fuel from waste oil.

[0019] Figure 2 This is the thermogravimetric analysis of the PTA@SiO2 catalyst after reaction in substrates dodecane and methyl palmitate. The comparative reactions confirmed that the catalyst has a low coke production rate in the hydrodeoxygenation reaction of methyl palmitate. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The exemplary implementation methods of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0021] The preparation process of the HPA@SiO2 catalyst in the following examples is as follows, taking phosphotungstic acid (PTA) as the raw material: (1) Mix 3 g of phosphotungstic acid (PTA) and 1 g of CTAB with 500 mL of anhydrous ethanol, 400 mL of deionized water, and 125 mL of 25% ammonia water in a 2 L beaker and stir for 2 h. (2) Add 6 mL of tetraethyl silicate dropwise and continue stirring for 48 h. After centrifugation, the product was washed once with ethanol, washed three times with water, and dried overnight. Finally, it was calcined at 550 °C for 3 h to obtain PTA@SiO2.

[0022] HPA@SiO2 catalyst can also choose phosphomolybdic acid (PMA) as raw material, and the synthesis steps are the same as PTA@SiO2 to obtain PMA@SiO2.

[0023] Example 1 like Figure 1 As shown, a recycling production process for preparing bio-jet fuel from waste oil and fat includes the following steps: (1) 25 g of acidified oil raw material was preheated to 100 ° C and passed into filter 1. Solid impurities were removed by filtration at a temperature of 100 ° C and a pressure of 1 MPa. Then, it was mixed with 0.0212 g of sulfur powder and 1.2512 g of PTA@SiO2 catalyst and passed into suspension bed reactor 2. The reaction pressure was 5 MPa, the reaction temperature was 350 ° C, and the liquid hourly space velocity was 3 h -1 , a one-step hydrodeoxygenation-isomerization reaction was carried out under the condition of hydrogen-to-oil ratio of 800 to obtain a mixed product Ⅰ; (2) The mixed product I is separated into solid phase and liquid phase product I through solid-liquid separator 3. The operating temperature of solid-liquid separator 3 is 80℃ and the operating pressure is 1MPa. The obtained liquid phase product I is passed into oil-water separator 4. The oil phase and water phase are separated under the conditions of operating temperature of 30℃ and operating pressure of 0.1MPa. The solid phase and oil phase are returned to suspension bed reactor 2 for hydrodeoxygenation-isomerization reaction again to generate product II (alkane yield is 92%, including isoparaffin 43%). At this time, the reaction pressure of suspension bed reactor 2 is 6MPa, the reaction temperature is 400℃, and the liquid hourly space velocity is 6h. -1 , hydrogen-to-oil ratio 1000; (3) Product II is passed through the solid-liquid separator 3 again to separate solid phase II and liquid phase II. The operating temperature of the solid-liquid separator 3 is 80°C and the operating pressure is 1 MPa. The solid phase II is recycled into the suspended bed reactor 2 again, and the liquid phase II is passed through the sieve plate distillation tower 5. The bio-jet fuel is separated under the conditions of a bottom temperature of 300°C and an operating pressure of 0.5 MPa.

[0024] Through the detection of production indicators, the bio-jet fuel product finally obtained in this embodiment meets the CTSO-2C701 standard.

[0025] Example 2 like Figure 1 As shown, a recycling production process for preparing bio-jet fuel from waste oil and fat includes the following steps: (1) 25 g of acidified oil raw material was preheated to 100 ° C and passed into filter 1. Solid impurities were removed by filtration at a temperature of 100 ° C and a pressure of 1 MPa. Then, it was mixed with 0.0321 g of carbon disulfide and 1.2538 g of PTA@SiO2 catalyst and passed into suspension bed reactor 2. The reaction pressure was 3 MPa, the reaction temperature was 400 ° C, and the liquid hourly space velocity was 3 h -1 , a one-step hydrodeoxygenation-isomerization reaction was carried out under the condition of hydrogen-to-oil ratio of 800 to obtain a mixed product Ⅰ; (2) The mixed product I is separated into solid phase and liquid phase product I through solid-liquid separator 3. The operating temperature of solid-liquid separator 3 is 100℃ and the operating pressure is 1MPa. The obtained liquid phase product I is passed into oil-water separator 4. The oil phase and water phase are separated under the conditions of operating temperature of 30℃ and operating pressure of 0.1MPa. The solid phase and oil phase are returned to suspension bed reactor 2 for hydrodeoxygenation-isomerization reaction again to generate product II (alkane yield is 90%, including isoparaffin 42%). At this time, the reaction pressure of suspension bed reactor 2 is 6MPa, the reaction temperature is 400℃, and the liquid hourly space velocity is 6h. -1 , hydrogen-to-oil ratio 1000; (3) Product II is passed through the solid-liquid separator 3 again to separate solid phase II and liquid phase II. The operating temperature of the solid-liquid separator 3 is 100°C and the operating pressure is 1 MPa. The solid phase II is recycled into the suspended bed reactor 2 again, and the liquid phase II is passed through the sieve plate fractionation tower 5. The bio-jet fuel is separated under the conditions of a bottom temperature of 300°C and an operating pressure of 0.5 MPa.

[0026] Through the detection of production indicators, the bio-jet fuel product finally obtained in this embodiment meets the CTSO-2C701 standard.

[0027] Example 3 like Figure 1 As shown, a recycling production process for preparing bio-jet fuel from waste oil and fat includes the following steps: (1) 25 g of acidified oil raw material was preheated to 100 ° C and passed into filter 1. Solid impurities were removed by filtration at a temperature of 100 ° C and a pressure of 1 MPa. Then, it was mixed with 0.02371 g of sulfur powder and 1.2534 g of PTA@SiO2 catalyst and passed into suspension bed reactor 2. The reaction pressure was 6 MPa, the reaction temperature was 350 ° C, and the liquid hourly space velocity was 3 h -1 , a one-step hydrodeoxygenation-isomerization reaction was carried out under the condition of a hydrogen-to-oil ratio of 1000 to obtain a mixed product Ⅰ; (2) The mixed product I is separated into solid phase and liquid phase product I through solid-liquid separator 3. The operating temperature of solid-liquid separator 3 is 80℃ and the operating pressure is 2MPa. The obtained liquid phase product I is passed into oil-water separator 4. The oil phase and water phase are separated under the conditions of operating temperature of 30℃ and operating pressure of 0.1MPa. The solid phase and oil phase are returned to suspension bed reactor 2 for hydrodeoxygenation-isomerization reaction again to generate product II (alkane yield is 96%, including isoparaffin 43%). At this time, the reaction pressure of suspension bed reactor 2 is 8MPa, the reaction temperature is 400℃, and the liquid hourly space velocity is 6h. -1 , hydrogen-to-oil ratio 1200; (3) Product II is passed through the solid-liquid separator 3 again to separate solid phase II and liquid phase II. The operating temperature of the solid-liquid separator 3 is 80°C and the operating pressure is 2 MPa. The solid phase II is recycled into the suspended bed reactor 2 again, and the liquid phase II is passed through the sieve plate fractionation tower 5. The bio-jet fuel is separated under the conditions of a bottom temperature of 300°C and an operating pressure of 0.5 MPa.

[0028] Through the detection of production indicators, the bio-jet fuel product finally obtained in this embodiment meets the CTSO-2C701 standard.

[0029] Example 4 like Figure 1 As shown, a recycling production process for preparing bio-jet fuel from waste oil and fat includes the following steps: (1) 25 g of acidified oil raw material was preheated to 100 ° C and passed into filter 1. Solid impurities were removed by filtration at a temperature of 100 ° C and a pressure of 1 MPa. Then, it was mixed with 0.0221 g of sulfur powder and 1.2522 g of PMA@SiO2 catalyst and passed into suspended bed reactor 2. The reaction pressure was 3 MPa, the reaction temperature was 350 ° C, and the liquid hourly space velocity was 4 h -1 , a one-step hydrodeoxygenation-isomerization reaction was carried out under the condition of hydrogen-to-oil ratio of 800 to obtain a mixed product Ⅰ; (2) The mixed product I is separated into solid phase and liquid phase product I through solid-liquid separator 3. The operating temperature of solid-liquid separator 3 is 80℃ and the operating pressure is 1MPa. The obtained liquid phase product I is passed into oil-water separator 4. The oil phase and water phase are separated under the conditions of operating temperature of 35℃ and operating pressure of 0.1MPa. The solid phase and oil phase are returned to suspension bed reactor 2 for hydrodeoxygenation-isomerization reaction again to generate product II (alkane yield is 92%, including isoparaffin 45%). At this time, the reaction pressure of suspension bed reactor 2 is 6MPa, the reaction temperature is 400℃, and the liquid hourly space velocity is 6h. -1 , hydrogen-to-oil ratio 1000; (3) Product II is passed through the solid-liquid separator 3 again to separate solid phase II and liquid phase II. The operating temperature of the solid-liquid separator 3 is 80°C and the operating pressure is 1 MPa. The solid phase II is recycled into the suspended bed reactor 2 again, and the liquid phase II is passed through the sieve plate fractionation tower 5. The bio-jet fuel is separated under the conditions of a bottom temperature of 400°C and an operating pressure of 0.3 MPa.

[0030] Through the detection of production indicators, the bio-jet fuel product finally obtained in this embodiment meets the CTSO-2C701 standard.

[0031] Example 5 like Figure 1 As shown, a recycling production process for preparing bio-jet fuel from waste oil and fat includes the following steps: (13) 25 g of acidified oil raw material was preheated to 100 °C and passed into filter 1. Solid impurities were removed by filtration at a temperature of 100 °C and a pressure of 1 MPa. Then, it was mixed with 0.0211 g of sulfur powder and 1.2535 g of PTA@SiO2 catalyst and passed into suspension bed reactor 2. The reaction pressure was 5 MPa, the reaction temperature was 350 °C, and the liquid hourly space velocity was 3 h -1 , a one-step hydrodeoxygenation-isomerization reaction was carried out under the condition of a hydrogen-to-oil ratio of 1000 to obtain a mixed product Ⅰ; (14) The mixed product I is separated into a solid phase and a liquid phase I through a solid-liquid separator 3. The operating temperature of the solid-liquid separator 3 is 80°C and the operating pressure is 1 MPa. The obtained liquid phase I is passed into an oil-water separator 4. The oil phase and the water phase are separated under the conditions of an operating temperature of 30°C and an operating pressure of 0.15 MPa. The solid phase and the oil phase are returned to the suspension bed reactor 2 for another hydrodeoxygenation-isomerization reaction to generate product II (the yield of alkanes is 96%, including 45% of isoalkanes). At this time, the reaction pressure of the suspension bed reactor 2 is 8 MPa, the reaction temperature is 350°C, and the liquid hourly space velocity is 6 h. -1 , hydrogen-to-oil ratio 1200; (15) Product II is passed through the solid-liquid separator 3 again to separate solid phase II and liquid phase II. The operating temperature of the solid-liquid separator 3 is 80°C and the operating pressure is 1 MPa. The solid phase II is recycled into the suspended bed reactor 2 again, and the liquid phase II is passed through the sieve plate distillation tower 5. The bio-jet fuel is separated under the conditions of a bottom temperature of 400°C and an operating pressure of 0.3 MPa.

[0032] Through the detection of production indicators, the bio-jet fuel product finally obtained in this embodiment meets the CTSO-2C701 standard.

[0033] Example 6 like Figure 1 As shown, a recycling production process for preparing bio-jet fuel from waste oil and fat includes the following steps: (1) 25 g of acidified oil raw material was preheated to 100 ° C and passed into filter 1. Solid impurities were removed by filtration at a temperature of 100 ° C and a pressure of 1 MPa. Then, it was mixed with 0.0287 g of carbon disulfide and 1.2583 g of PTA@SiO2 catalyst and passed into suspension bed reactor 2. The reaction pressure was 5 MPa, the reaction temperature was 300 ° C, and the liquid hourly space velocity was 3 h -1 , a one-step hydrodeoxygenation-isomerization reaction was carried out under the condition of hydrogen-to-oil ratio of 800 to obtain a mixed product Ⅰ; (2) The mixed product I is separated into solid phase and liquid phase product I through solid-liquid separator 3. The operating temperature of solid-liquid separator 3 is 100℃ and the operating pressure is 1.5MPa. The obtained liquid phase product I is passed into oil-water separator 4. The oil phase and water phase are separated under the conditions of operating temperature of 30℃ and operating pressure of 0.1MPa. The solid phase and oil phase are returned to suspension bed reactor 2 for hydrodeoxygenation-isomerization reaction again to generate product II (alkane yield is 93%, including 43% isoparaffin). At this time, the reaction pressure of suspension bed reactor 2 is 6MPa, the reaction temperature is 400℃, and the liquid hourly space velocity is 8h. -1 , hydrogen-to-oil ratio 1000; (3) Product II is passed through the solid-liquid separator 3 again to separate solid phase II and liquid phase II. The operating temperature of the solid-liquid separator 3 is 100°C and the operating pressure is 1.5 MPa. The solid phase II is recycled into the suspended bed reactor 2 again, and the liquid phase II is passed through the sieve plate fractionation tower 5. Bio-jet fuel is separated under the conditions of a bottom temperature of 300°C and an operating pressure of 0.5 MPa.

[0034] Through the detection of production indicators, the bio-jet fuel product finally obtained in this embodiment meets the CTSO-2C701 standard. Taking Example 1 as an example, the thermogravimetric analysis of the PTA@SiO2 catalyst after reaction in substrates dodecane and methyl palmitate is as follows: Figure 2 It can be seen that the thermal weight loss phenomenon at 400~545℃ is attributed to the sulfide in the catalyst. For the reaction with methyl palmitate as the substrate, the additional thermal degradation peak at 545~683℃ is attributed to the weight loss of coke (about 5%), which confirms that the catalyst has a low coke formation rate in the hydrodeoxygenation reaction of methyl palmitate.

[0035] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A recycling production method for producing bio-jet fuel from waste oils and fats, characterized by: The following steps are involved: (1) The waste oil is preheated and dissolved, and then passed through a filter 1 to filter out the solid residue. The waste oil is then subjected to a one-step hydrodeoxygenation-isomerization reaction with a sulfiding agent and a heteropolyacid catalyst HPA@SiO2 in a suspended bed reactor 2 to obtain a mixed product I. (2) The mixed product I is separated into a solid phase I and a liquid phase I through a solid-liquid separator 3. The liquid phase I is passed into an oil-water separator 4 to separate the oil phase and the water phase. The solid phase I and the oil phase are returned to the suspended bed reactor 2 and are subjected to hydrodeoxygenation-isomerization again to generate product II. (3) Product II is passed into the solid-liquid separator 3 to separate the liquid phase II and the solid phase II. The solid phase II enters the suspended bed reactor 2 for recycling, and the liquid phase II is passed into the fractionation tower 5 to separate the bio-jet fuel.

2. The cyclic production method according to claim 1, characterized in that: The waste oil and fat in step (1) includes one or more of acidified oil, swill oil, and gutter oil; the vulcanizing agent includes one of sulfur powder, carbon disulfide, dimethyl disulfide, and H2S.

3. The cyclic production method according to claim 1, characterized in that: The HPA in the HPA@SiO2 in step (1) is a heteropoly acid, including phosphotungstic acid and phosphomolybdic acid. The specific synthesis steps are as follows: (1) Mix heteropoly acid and CTAB in a mass ratio of 3:1 with a certain amount of anhydrous ethanol, deionized water, and ammonia water, and stir for 2 h; the volume ratio of anhydrous ethanol, deionized water, and ammonia water is 10:8:2.5; (2) Tetraethyl silicate was added dropwise to the solution obtained in step (1), and the mixture was stirred for 48 h. The mixture was centrifuged, and the precipitate was washed with ethanol and water, dried overnight, and finally calcined at 550°C for 3 h to obtain HPA@SiO2; the amount of tetraethyl silicate used was such that the molar ratio of SiO2 in tetraethyl silicate to HPA was 1:

2.

4. The cyclic production method according to claim 1, characterized in that: The amount of the heteropolyacid catalyst used in step (1) is 5-10 wt% of the waste oil.

5. The cyclic production method according to claim 1, characterized in that: The mass ratio of the vulcanizing agent to the waste oil and fat described in step (1) is (0.05-0.5):

100.

6. The cyclic production method according to claim 1, characterized in that: The reaction pressure of the suspended bed reactor in step (1) is 2-6 MPa, the reaction temperature is 300-400°C, and the liquid hourly space velocity is 0.5-8 h -1 , the hydrogen-to-oil ratio is 600~1200.

7. The cyclic production method according to claim 1, characterized in that: The operating temperature of the solid-liquid separator in steps (2) and (3) is 80-150° C., and the operating pressure is 0.5-2 MPa.

8. The cyclic production method according to claim 1, characterized in that: The operating temperature of the oil-water separator in step (2) is 20-40° C., and the operating pressure is 0.08-0.15 MPa.

9. The cyclic production method according to claim 1, characterized in that: The reaction pressure of the suspended bed reactor in step (2) is 4-8 MPa, the reaction temperature is 300-400°C, and the liquid hourly space velocity is 0.2-8 h -1 , the hydrogen-to-oil ratio is 600~1200.

10. The cyclic production method according to claim 1, characterized in that: In step (3), the fractionation tower is of sieve plate type or packed type, the bottom temperature is 250-400° C., and the operating pressure is 0.1-0.6 MPa.

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