Bio-oil oxidation-esterification simultaneous upgrading method
Through the bio-oil oxidation-esterification joint quality improvement method, the problems of low esterification efficiency and difficult product separation during the bio-oil quality improvement process are solved, efficient acid removal and quality improvement and product separation are achieved, and the stability and calorific value of bio-oil are improved.
Patent Information
- Application Number
- CN202510334074.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-20
- Publication Date
- 2025-04-29
AI Technical Summary
During the process of bio-oil quality improvement, the esterification efficiency is low, water is formed during the esterification process, and subsequent products are difficult to separate.
The bio-oil oxidation-equiregulation method is used to separate the aqueous bio-oil by water extraction, and then the oxidation treatment is carried out to convert the aldehydes into acids, and then the esterification and dehydration is carried out. Multi-step treatment is performed using a rotary evaporator and an oil bath pot, and finally the quality-improved oil is obtained by distillation separation.
The esterification reaction efficiency is improved, the acid removal and quality improvement is achieved to a maximum extent, the stability and calorific value of bio-oil are improved, and residual water and excess alcohol are effectively separated to obtain high-calorie, low acid value and low moisture quality enhancement oil.
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Figure CN119899729A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of biomass resource utilization, and in particular to a bio-oil oxidation-esterification combined quality improvement method. Background Art
[0002] Due to the rapid development of the world economy and society, the demand for energy is growing. According to the 2024 version of BP World Energy, the current energy consumption structure is very unreasonable, mainly relying on fossil energy such as coal, oil, and natural gas, while the proportion of renewable energy consumption is relatively small. Biomass energy is the only renewable carbon resource in the world and the fourth largest energy source after fossil energy. It has the characteristics of wide distribution and rich content, so it has attracted much attention.
[0003] Biomass can be processed into solid fuels, biofuels and liquid fuels through different technical means. Among them, the most promising is the rapid pyrolysis technology of biomass, which passes through a high-pressure and high-temperature reactor in a very short time, and then quickly condenses to obtain brown, odorous bio-oil. Compared with fossil fuels, this oil has the characteristics of low calorific value, high water content, high acidity, and high viscosity, and needs to be improved. Studies have shown that when the water content of bio-oil reaches 40~50%, it will be divided into two phases. The upper layer is the water phase, which is mainly polar compounds such as acids, aldehydes, ketones, sugars, etc.; the lower layer is the oil phase, which is mainly phenols, etc. After water extraction, the water phase has a lower calorific value and more acid than the oil phase, so we mainly improve the water phase.
[0004] At present, the methods for improving the quality of bio-oil are divided into physical methods and chemical methods. Physical methods such as filtration and emulsification have very limited effects on improving the quality of aqueous bio-oil, while catalytic reforming and catalytic hydrogenation in chemical methods are not highly reactive to acid compounds in aqueous bio-oil. In addition, since there are many unsaturated compounds in aqueous bio-oil, a large amount of hydrogen will be consumed, so it is not suitable for improving the quality of aqueous bio-oil. Catalytic esterification is the esterification of bio-oil by adding alcohols and acidic catalysts under mild conditions. This method has great application potential due to its significant deacidification effect, easy operation and economy, and the catalyst is not easily deactivated.
[0005] Relevant research on bio-oil esterification shows that the traditional direct esterification process involves many side reactions, such as acetal reaction and polymerization reaction of aldehydes. The generated acetals are unstable and form high molecular weight insoluble polymers, which is not conducive to the esterification quality improvement process. Summary of the invention
[0006] The object of the present invention is to provide a bio-oil oxidation-esterification combined quality improvement method to overcome the problems of low esterification efficiency, water formation during esterification, and difficulty in subsequent product separation.
[0007] To achieve the above object, the present invention adopts the following technical solution: A bio-oil oxidation-esterification combined quality improvement method comprises the following steps: 1) The bio-oil and deionized water were mixed in a mass ratio of 3:2. In order to extract thoroughly, the mixture was placed in an ultrasonic cleaner for ultrasonic treatment, and then transferred to a centrifuge for centrifugal treatment. At this time, two phases appeared in the centrifuge tube, and the upper aqueous phase was obtained; 2) The upper aqueous bio-oil obtained in step 1) is transferred to a single-necked flask, and a portion of the water is distilled off under reduced pressure using a rotary evaporator, and then naturally cooled to room temperature to obtain an upgraded raw material, which is called aqueous bio-oil WSF; 3) The aqueous bio-oil WSF obtained in step 2) was mixed with hydrogen peroxide in a mass ratio of 10:2 and added to a three-necked flask, and oxidized in an oil bath at atmospheric pressure to obtain an oxidized product, which is called oxidized aqueous bio-oil OWSF; 4) The oxidized aqueous bio-oil OWSF obtained in step 3) was mixed with n-butanol and added to a three-necked flask, the condenser was connected to the water separator, and the esterification and dehydration were carried out in an oil bath at atmospheric pressure to obtain an upgraded oleyl alcohol mixture; 5) The upgraded oil-alcohol mixture obtained in step 4) is distilled to separate residual water and excess alcohol to obtain upgraded oil.
[0008] Furthermore, in step 1), the ultrasonic temperature is 25-35°C and the time is 15-20 min.
[0009] Furthermore, the centrifugal speed in step 1) is 8000 rpm / min, and the time is 10-15 min.
[0010] Furthermore, in step 2), the temperature of the reduced pressure distillation is 80-90° C. and the pressure is 0.8-0.9 Mpa.
[0011] Furthermore, in step 3), the oxidation temperature is 50-100°C and the time is more than 1-2h.
[0012] Furthermore, the concentration of the oxidant hydrogen peroxide in step 3) is 30wt%.
[0013] Furthermore, in step 4), the esterification dehydration temperature is 120-140°C and the time is 1-2 h.
[0014] Furthermore, in the esterification and dehydration combined treatment process of step 4), the solid acid catalyst used is Amberlyst-70, and the amount used is 1-7wt% of the total mass of the substrate; the water removal agent is petroleum ether.
[0015] Furthermore, the mass ratio of the oxidized aqueous phase bio-oil, n-butanol and petroleum ether in step 4) is 1:(0.5-2):(0.1-0.3).
[0016] Furthermore, the distillation tower used for distillation in step 5) is a packed distillation tower, which is about 1.5 m high and is filled with glass spring fillers.
[0017] Furthermore, the distillation temperature in step 5) is 130-140°C, and the time is 0.5-1h.
[0018] The present invention has the following beneficial effects: The principle of the present invention is as follows: polar compounds in bio-oil are easily soluble in water and can be separated by water extraction; aldehyde compounds are converted into acid compounds by oxidation with a strong oxidant H2O2; water present in the oxidized aqueous phase bio-oil and water generated by the esterification reaction can produce an azeotropic reaction with n-butanol, and the boiling point of the mixture can be reduced by a dehydrating agent, petroleum ether, which is then distilled and condensed into a water separator for removal, thereby promoting the forward progress of the esterification reaction and increasing the acid value conversion rate to 95%; residual water and n-butanol have low boiling points, and the final improved bio-oil can be obtained by distillation separation.
[0019] Compared with the prior art, the present invention has the following advantages: (1) Effective separation of polar compounds in bio-oil is achieved through water extraction.
[0020] (2) Carboxylic acid, aldehyde and ketone components in the aqueous bio-oil make the aqueous bio-oil highly corrosive and unstable. The method of the present invention first performs oxidation pretreatment on the aqueous bio-oil raw material to convert the aldehyde and ketone components in the aqueous bio-oil into carboxylic acids; then, the carboxylic acid components are converted into neutral esters through esterification and dehydration, and a large amount of water is removed at the same time to promote the forward esterification reaction, thereby improving the efficiency of the esterification reaction and achieving a greater degree of acid removal and quality improvement. At the same time, the stability and calorific value of the aqueous bio-oil are improved.
[0021] (3) By distilling the residual phase, the residual water and excess alcohol are effectively separated to obtain an upgraded oil with high calorific value, low acid value and low moisture content. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a flow chart of bio-oil oxidation-esterification dehydration combined quality improvement and separation; Figure 2 GC-MS diagram of each oil product during the upgrading process; Figure 3 FT-IR images of various oil products during the upgrading process; Figure 4 H-NMR diagram of each oil product during the upgrading process; Figure 5This is the GC analysis chart of the sample prepared in Example 3. DETAILED DESCRIPTION
[0023] A bio-oil oxidation-esterification combined quality improvement method, comprising the following steps: 1) Mix bio-oil and deionized water in a mass ratio of 3:2. For thorough extraction, place in an ultrasonic cleaner for ultrasonic treatment at a temperature of 25-35 °C for 15-20 min. Then transfer to a centrifuge for centrifugation at a rate of 8000 rpm / min for 10-15 min. At this point, there are two phases in the centrifuge tube, and 120-132 g of the upper aqueous phase is obtained; 2) Take 80 g of the upper aqueous bio-oil obtained in step 1) and transfer it to a single-necked flask. Use a rotary evaporator to distill off 40-45 g of the components under reduced pressure, of which 93-95 wt% are H2O. After the distillation, naturally cool to room temperature to obtain the upgraded raw material we need, which is called aqueous bio-oil WSF; 3) The aqueous bio-oil WSF obtained in step 2) was mixed with hydrogen peroxide in a mass ratio of 10:2 and added to a three-necked flask, and oxidized in an oil bath at atmospheric pressure to obtain an oxidized product, which is called oxidized aqueous bio-oil OWSF; 4) The oxidized aqueous bio-oil OWSF obtained in step 3) was mixed with n-butanol and added to a three-necked flask, the condenser was connected to the water separator, and the esterification and dehydration were carried out in an oil bath at atmospheric pressure to obtain an upgraded oleyl alcohol mixture; 5) The upgraded oil-alcohol mixture obtained in step 4) is distilled to separate residual water and excess alcohol to obtain the final upgraded oil.
[0024] Furthermore, in step 2), the temperature of the reduced pressure distillation is 80-90° C. and the pressure is 0.8-0.9 Mpa.
[0025] Furthermore, in step 3), the oxidation temperature is 50-100°C and the time is more than 1-2h.
[0026] Furthermore, the concentration of the hydrogen peroxide in step 3) is 30wt%.
[0027] Furthermore, in step 4), the esterification temperature is 120-140°C and the time is 1-2 h.
[0028] Furthermore, in the esterification and dehydration combined treatment process of step 4), the solid acid catalyst used is Amberlyst-70, and the amount used is 1-7wt% of the total mass of the substrate; the water removal agent is petroleum ether.
[0029] Furthermore, the mass ratio of the oxidized aqueous phase bio-oil, n-butanol and petroleum ether in step 4) is 1:(0.5-2):(0.1-0.3).
[0030] Furthermore, the distillation tower used for distillation in step 5) is a packed distillation tower, which is about 1 m high and is filled with glass spring fillers.
[0031] Furthermore, the distillation temperature in step 5) is 130-140°C, and the time is 0.5-1h.
[0032] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.
[0033] Example 1 18 g of bio-oil raw material (BTG, Netherlands) was fully mixed with 12 g of deionized water and stirred vigorously for 30 min. The mixture was then transferred to an ultrasonic cleaner for ultrasonic treatment (40 kHz) at 25°C for 15 min. The mixture was then transferred to a centrifuge for centrifugal treatment at a rate of 8000 rpm / min for 10 min. At this point, the centrifuge tube was two-phase, and 120-132 g of the upper aqueous phase was obtained (20-22 g per centrifuge tube, 120-132 g at a time); Take 80 g of water-phase bio-oil into a single-necked flask, use a rotary evaporator to distill off 40 g of the components under reduced pressure, and remove 93-95 wt% of the components, which are all water. After the end, naturally cool to room temperature to obtain the quality-improved raw material we need, called water-phase bio-oil WSF; Content of main components of bio-oil raw materials
[0034] Example 2 20 g of aqueous bio-oil and 4 g of hydrogen peroxide (concentration 30 wt%) were fully mixed and added to a three-necked flask. The three-necked flask was transferred to an oil bath, and the temperature of the oil bath was set to 80 °C and maintained for 1 h. Then the three-necked flask was taken out and cooled to room temperature to obtain oxidized aqueous bio-oil OWSF.
[0035] Take 20 g of the above-obtained oxidized aqueous bio-oil OWSF, 30 g of n-butanol, and 4 g of petroleum ether, mix and add into a three-necked flask, connect the condenser to the water separator, and then transfer to an oil bath pot, set the heating temperature to 130 °C, add 5wt% Amberlyst-70 catalyst of the total mass of substrate (oxidized aqueous bio-oil OWSF + n-butanol) when the reaction solution reaches 95 °C, start timing, and continuously remove the lower aqueous phase in the water separator during the reaction. After 1-2 h, until the liquid level of the aqueous phase in the water separator no longer rises, stop heating and end the reaction. Cool naturally to room temperature to obtain an upgraded oleyl alcohol mixture.
[0036] In this example, the above method was used to improve the quality of bio-oil by oxidation and esterification. The results were as follows: During the oxidation process, the content of H2O2 could not be quantified, so the progress of the oxidation reaction was determined by measuring the total acid value of the solution; the initial total acid value of the aqueous bio-oil was 68 mg KOH / g, and after 1 hour, the total acid value of the solution rose to 200~220 mg KOH / g, indicating that the acidity was significantly enhanced. During the esterification and dehydration process, 14 g H2O was removed, and the total acid value of the final solution was 5~7 mg KOH / g, and the acid value conversion rate could reach 93~95%, indicating that the esterification and dehydration process had a significant deacidification effect.
[0037] Acid value determination formula:
[0038] Acid value conversion rate calculation formula: Example 3
[0039] Take 50 g of the upgraded oil-alcohol mixture and add it to the distillation tower kettle. Set the tower kettle heating temperature to 140°C. During the distillation process, continuously remove the components with boiling points below 120°C (mainly residual water and excess alcohol) in the solution, and collect the liquid in the top condenser with a beaker. After 30 minutes, stop heating until no more liquid is distilled out, and end the reaction. Cool naturally to room temperature to obtain upgraded oil.
[0040] In this embodiment, the above method is used to distill and separate the upgraded oil-alcohol mixture, butyl acetate is used as the internal standard, and the alcohol content in the product is determined by GC, and the water content of the upgraded oil is determined by the Karl-Fischer method. The situation is as follows: after distillation and separation, the alcohol content in the upgraded oil is 0%, and the water content is 0.76 wt%. Excess alcohol and residual water are almost completely removed.
[0041] 1. The sample prepared in Example 1 was characterized by GC-MS. The results are as follows: Figure 2 As shown. Figure 2It can be seen that the water extraction experiment can effectively separate polar compounds (such as acetic acid, hydroxyacetone, etc.) in bio-oil into the aqueous phase bio-oil.
[0042] 2. The sample prepared in Example 1 was subjected to FT-IR analysis, and the results were as follows: Figure 3 As shown. Figure 3 It can be seen that the infrared spectra of the aqueous phase bio-oil and the bio-oil are similar, indicating that the components in the bio-oil are effectively separated into the aqueous phase.
[0043] 3. The sample prepared in Example 2 was subjected to H-NMR analysis, and the results were as follows: Figure 4 As shown. Figure 4 It can be seen that the shift interval of 9-10 ppm is the aldehyde hydrogen chemical shift peak of aldehyde substances in bio-oil. The characteristic peaks in this interval are integrated, and the peak area of aldehyde substances is reduced by about 80%. This shows that after oxidation, the aldehyde substances in the aqueous phase bio-oil are effectively converted into acids.
[0044] 4. The samples prepared in Examples 2 and 3 were subjected to FT-IR analysis. The results are as follows: Figure 3 As shown. In the FT-IR image, 1710 cm -1 The absorption peak of the C=O bond of carboxylic acid is 3369 cm -1 The absorption peak of OH bond is at Figure 3 It can be seen that after oxidation, the absorption peak of the C=O bond of carboxylic acid is enhanced, indicating that the acidity is enhanced. After esterification and dehydration, the absorption peak at 1710 cm -1 The carboxylic acid absorption peak at 1725 cm -1 The ester C=O bond appears at 3369cm due to the removal of a large amount of water. -1 The OH bond absorption peak at the bottom was significantly weakened, indicating that the acid and water removal effects were significant.
[0045] 5. The sample prepared in Example 3 was subjected to GC analysis. The results are as follows: Figure 5 As shown. The absorption peak of n-butanol is at 2.2-2.5min in the GC graph, and n-butanol is quantified using butyl acetate as the internal standard. Figure 5 It can be seen that after distillation, there is almost no peak at 2.2-2.5min, indicating that n-butanol has been completely separated.
[0046] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.
Claims
1. A bio-oil oxidation-esterification combined quality improvement method, characterized in that: The steps include: 1) The bio-oil and deionized water were mixed in a mass ratio of 3:
2. In order to extract thoroughly, the bio-oil was placed in an ultrasonic cleaner for ultrasonic treatment, and then transferred to a centrifuge for centrifugal treatment. At this time, two phases appeared in the centrifuge tube, and the upper aqueous phase was obtained; 2) The upper aqueous phase obtained in step 1) is transferred to a single-necked flask, and a portion of the water is distilled off under reduced pressure using a rotary evaporator. After the distillation, the evaporator is naturally cooled to room temperature to obtain an upgraded raw material, which is called aqueous bio-oil WSF; 3) The aqueous bio-oil WSF obtained in step 2) is mixed with hydrogen peroxide in a mass ratio of 10:2 and added into a three-necked flask, and oxidized in an oil bath under atmospheric pressure to obtain an oxidized product, which is called oxidized aqueous bio-oil OWSF; 4) The oxidized aqueous bio-oil OWSF obtained in step 3) is mixed with n-butanol and added into a three-necked flask, a condenser is connected to a water separator, and esterification and dehydration are carried out in an oil bath under atmospheric pressure to obtain an upgraded oleyl alcohol mixture; 5) The upgraded oil-alcohol mixture obtained in step 4) is distilled to separate residual water and excess alcohol to obtain upgraded oil.
2. The method according to claim 1, characterized in that: In step 1), the ultrasonic temperature is 25-35°C and the time is 15-20 min.
3. The method according to claim 1, characterized in that: In step 1), the centrifugation speed is 8000 rpm / min and the time is 10-15 min.
4. The method according to claim 1, characterized in that: The temperature of the reduced pressure distillation in step 2) is 80-90°C and the pressure is 0.8-0.9 Mpa.
5. The method according to claim 1, characterized in that: In step 3), the oxidation temperature is 50-100°C and the time is 1-2h.
6. The method according to claim 1, characterized in that: In step 3), the concentration of hydrogen peroxide is 30wt%.
7. The method according to claim 1, characterized in that: In step 4), the esterification temperature is 120-140°C and the time is 1-2 h.
8. The method according to claim 1, characterized in that: In the esterification and dehydration combined treatment process of step 4), the solid acid catalyst used is Amberlyst-70, and the amount used is 1-7wt% of the total mass of the substrate, and the dehydrating agent is petroleum ether.
9. The method according to claim 8, characterized in that: In step 4), the mass ratio of the oxidized aqueous phase bio-oil, n-butanol, and petroleum ether is 1:(0.5-2):(0.1-0.3).
10. The method according to claim 1, characterized in that: The distillation tower used for distillation in step 5) is a packed distillation tower with a height of 1.5 m. The packing used is a glass spring packing. The distillation temperature is 130-140 °C and the time is 0.5-1h.