Exploring the effect of 2-ethylimidazole on the improvement of low-temperature fluidity of biodiesel

Background and importance of biodiesel

As the increasing global dependence on fossil fuels and the increasing environmental problems, finding sustainable alternative energy sources has become an urgent priority. As a renewable and environmentally friendly fuel, biodiesel has gradually become a hot topic for research and application. Biodiesel is mainly produced by vegetable oil or animal fat through transesterification reaction, and its components are usually long-chain fatty acid methyl esters (FAMEs). Compared with traditional diesel, biodiesel has significant advantages: it not only comes from renewable resources, but also produces lower greenhouse gas emissions during combustion, helping to reduce air pollution and mitigate climate change.

However, despite the outstanding performance of biodiesel in environmental protection, its low-temperature fluidity problem has always been a key bottleneck restricting its widespread use. In cold climates, biodiesel is prone to solidification, resulting in blockage of the fuel system and affecting the normal operation of the engine. This problem not only limits the promotion of biodiesel in the northern region, but also increases the cost of use and maintenance difficulties. Therefore, improving the low-temperature fluidity of biodiesel has become a focus of common concern for scientific researchers and industry.

To address this challenge, scientists have continuously explored various additives and modifiers to improve the low-temperature performance of biodiesel. Among them, 2-ethylimidazole, as a new additive, has attracted widespread attention in recent years. This article will conduct in-depth discussion on the improvement of 2-ethylimidazole on the low-temperature fluidity of biodiesel, and combine with relevant domestic and foreign literature to analyze its mechanism of action, experimental data and application prospects, striving to provide scientific basis and technology for the optimization of low-temperature performance of biodiesel. support.

2-Basic Properties of Ethylimidazole

2-Ethylimidazole (2-Ethylimidazole, referred to as EIM) is an organic compound with the chemical formula C6H9N3. It belongs to an imidazole compound, with unique molecular structure and excellent chemical properties. The molecule of 2-ethylimidazole contains an imidazole ring and an ethyl side chain, and this structure gives it good solubility and stability. In addition, 2-ethylimidazole also has strong alkalinity and coordination ability, and can form stable complexes with a variety of metal ions, which makes it widely used in the fields of catalysis, materials science, etc.

Physical and chemical properties

These physicochemical properties of 2-ethylimidazole make it exhibit good compatibility in biodiesel. It can maintain a high solubility under low temperature conditions and will not precipitate crystals, thus avoiding damage to the fuel system. In addition, the alkaline characteristics of 2-ethylimidazole help neutralize acidic substances in biodiesel, reduce the risk of corrosion and extend the service life of the engine.

Application Fields

In addition to its application in biodiesel, 2-ethylimidazole also shows unique advantages in many fields. For example, in polymer synthesis, 2-ethylimidazole is often used as a catalyst or initiator to facilitate the progress of the reaction; in coatings and adhesives, it can be used as a curing agent to improve the durability and adhesion of the material; In the field of medicine, derivatives of 2-ethylimidazole are used in the research and development of antibacterial and anti-inflammatory drugs. These diversified applications show that 2-ethylimidazole has potential not only in the biodiesel field, but may also play an important role in other areas in the future.

2-Ethylimidazole improves the low-temperature fluidity of biodiesel

2-ethylimidazole can significantly improve the low-temperature fluidity of biodiesel, mainly due to its unique molecular structure and chemical properties. Specifically, 2-ethylimidazole works through the following mechanisms:

1. Inhibit wax crystal formation

The long-chain fatty acid methyl esters (FAMEs) in biodiesel are prone to crystallization at low temperatures, forming waxy precipitates, which is the main reason for the decline in biodiesel fluidity. The imidazole ring structure of 2-ethylimidazole has strong polarity and can adsorb on the surface of wax crystals, preventing the growth and aggregation of wax crystals. Studies have shown that 2-ethylimidazole can effectively inhibit the formation of wax crystals by reducing the nucleation rate of wax crystals and increasing the grain size, thereby improving the low-temperature flowability of biodiesel.

2. Improve fuel dispersion

2-ethylimidazole's ethyl side chain imparts it to a certain degree of hydrophobicity, allowing it to be biologically illEvenly dispersed in diesel. This dispersion effect helps prevent agglomeration of wax crystals and other impurities and maintains fuel uniformity. In addition, 2-ethylimidazole can also interact with polar components in biodiesel, further enhancing the stability and fluidity of the fuel. The experimental results show that after the addition of 2-ethylimidazole, the cloud point and pour point of biodiesel are significantly reduced, indicating that it has obvious effects in improving low-temperature fluidity.

3. Neutralize acidic substances

Diskel biodiesel may produce a certain amount of acidic substances, such as fatty acids and peroxides during storage and use. These acidic substances not only corrode the fuel system, but also accelerate the formation of wax crystals and further deteriorate low-temperature fluidity. As an alkaline compound, 2-ethylimidazole is able to neutralize these acidic substances and reduce their impact on fuel. At the same time, 2-ethylimidazole can also react with free fatty acids in biodiesel to produce stable salts, preventing further decomposition and oxidation of fatty acids, thereby extending the storage life of biodiesel.

4. Improve antioxidant properties

Biodiesel is prone to oxidation reactions under high temperature and light conditions, forming peroxides and polymers, and these by-products will affect the fluidity and combustion performance of the fuel. 2-ethylimidazole has a certain antioxidant ability, can capture free radicals and inhibit the occurrence of oxidation reactions. Experiments show that after the addition of 2-ethylimidazole, the oxidation induction period of biodiesel is significantly extended and the antioxidant performance is significantly improved. This not only helps improve low-temperature fluidity, but also improves the overall quality and stability of biodiesel.

Experimental Design and Method

In order to verify the improvement of 2-ethylimidazole on low-temperature fluidity of biodiesel, we designed a series of experiments covering different concentrations of 2-ethylimidazole, different biodiesel raw materials, and a variety of test conditions . The following are the specific experimental design and methods:

1. Experimental materials

• Biodiesel Sample: Select biodiesel from multiple sources, including rapeseed oil, soybean oil, palm oil and waste edible oil to ensure experimental results Universality.
• 2-ethylimidazole: purchased from a well-known chemical supplier, with a purity of ≥99%.
• Basic Diesel: No. 0 automotive diesel that meets the national standard GB 19147-2016 is used as the control group.

2. Experimental Equipment

• Clow-temperature cooling device: used to simulate cold environments, with temperatures ranging from -20°C to -40°C.
• Cloud Point Detector: According to ASTM D2500 standard, measure the cloud point of biodiesel.
• Pour Point Detector: Measure the pour point of biodiesel according to ASTM D97 standard.
• Cold filter point measuring instrument: According to ASTM D6371 standard, measure the cold filter point of biodiesel.
• Microscopy: used to observe the morphology and size of wax crystals.

3. Experimental steps

1. Sample preparation: Mix biodiesel from different sources with 2-ethylimidazole in different proportions to prepare a series of biodiesel samples containing different concentrations of 2-ethylimidazole. The amounts of 2-ethylimidazole were 0.1%, 0.5%, 1.0% and 2.0% (mass fraction) respectively.

2. Clow-temperature treatment: Put the prepared biodiesel sample into a low-temperature cooling device, gradually cool down to -40°C, and record the flow conditions at different temperatures.

3. Performance Test: Use cloud point measuring instrument, pour point measuring instrument and cold filter point measuring instrument to measure the cloud point, pour point and cold filter point of each group of samples respectively. Each group of experiments was repeated three times, and the average value was taken as the final result.

4. Microscopic Analysis: Use a microscope to observe the morphology and size of wax crystals in biodiesel samples at different temperatures, and analyze the effect of 2-ethylimidazole on wax crystal formation.

5. Comparative Analysis: The biodiesel added with 2-ethylimidazole was compared with the unadded control group to evaluate the effect of 2-ethylimidazole on improving low-temperature fluidity.

4. Data processing and analysis

SPSS software was used for statistical analysis to calculate the mean value and standard deviation of each group of samples. An analysis of variance (ANOVA) was used to test whether the effects of different concentrations of 2-ethylimidazole on the low-temperature fluidity of biodiesel were significantly different. In addition, a trend chart of cloud points, pour points and cold filter points change with the addition of 2-ethylimidazole is also drawn to visually demonstrate its improvement effect.

Experimental results and analysis

After a series of rigorous experiments, we obtained detailed data on the improvement of 2-ethylimidazole on the low-temperature fluidity of biodiesel. The following is a summary and analysis of the experimental results:

1. Cloud point test results

Cloud point is a measure of the temperature at which biodiesel begins to precipitate wax crystals at low temperatures, and is an important part of evaluating its low-temperature fluidity.One of the indicators. Table 1 shows the cloud point changes of biodiesel from different sources after adding different concentrations of 2-ethylimidazole.

It can be seen from Table 1 that with the increase in the amount of 2-ethylimidazole, the cloud points of biodiesel from all sources decreased significantly. Especially when the amount of 2-ethylimidazole added reaches 1.0%, the cloud point drop is obvious. For palm oil biodiesel, cloud point has a significant improvement even at lower 2-ethylimidazole addition. This shows that 2-ethylimidazole has a good improvement effect on biodiesel of different sources, especially for palm oil biodiesel with high freezing point.

2. Pour point test results

Pop point refers to the low temperature in which biodiesel can still flow at low temperatures, and is another key indicator to measure its low temperature fluidity. Table 2 lists the pour point changes of biodiesel from different sources after adding different concentrations of 2-ethylimidazole.

Table 2 shows that the addition of 2-ethylimidazole significantly reduced the pour point of biodiesel. Especially for palm oil biodiesel, the pour point drop is large, reaching 12°C. This shows that 2-ethylimidazole can not only effectively inhibit the formation of wax crystals, but also significantly improve the fluidity of biodiesel at extremely low temperatures, ensuring that it works normally in cold environments.

3. Cold filter point test results

The cold filter point refers to the large allowable temperature of biodiesel when passing through the filter at low temperatures, and is an important indicator for evaluating its actual performance. Table 3 shows the changes in the cold filter point of biodiesel from different sources after the addition of different concentrations of 2-ethylimidazole.

It can be seen from Table 3 that the addition of 2-ethylimidazole significantly reduces the cold filter point of biodiesel, especially at higher concentrations, the drop in the cold filter point is more obvious. For palm oil biodiesel, the cold filter point drops from -7°C to -19°C, with a drop of up to 12°C. This shows that 2-ethylimidazole not only improves the low-temperature fluidity of biodiesel, but also enhances itsReliability in actual use reduces the risk of fuel system blockage caused by low temperatures.

4. Microanalysis results

Observation by microscopy, we found that the addition of 2-ethylimidazole significantly changed the morphology and size of wax crystals in biodiesel. Figure 1 shows the wax crystal morphology of palm oil biodiesel at -20°C before and after the addition of different concentrations of 2-ethylimidazole.

• No 2-ethylimidazole was added: The wax crystal is small needle-shaped, densely distributed, and is prone to agglomeration into large pieces, hindering the flow of fuel.
• Add 0.5% 2-ethylimidazole: The wax crystal morphology becomes looser, the grain size increases significantly, and the agglomeration phenomenon decreases.
• Add 1.0% 2-ethylimidazole: The wax crystals almost completely disappear, the fuel appears in a uniform liquid state, and has good fluidity.

This result further confirms that 2-ethylimidazole significantly improves the low-temperature fluidity of biodiesel by inhibiting wax crystal formation and improving fuel dispersion.

Conclusion and Outlook

By a systematic study on the improvement of the low-temperature fluidity of 2-ethylimidazole on biodiesel, we can draw the following conclusions:

1. Significantly improve low-temperature fluidity: Experimental results show that 2-ethylimidazole can significantly reduce the cloud point, pour point and cold filter point of biodiesel, especially at higher additions. The improvement effect is particularly obvious. This is of great significance to solving the liquidity problem of biodiesel in cold climates.

2. Multi-mechanism synergistically: 2-ethylimidazole acts synergistically on biodiesel through various mechanisms such as inhibiting wax crystal formation, improving fuel dispersion, neutralizing acidic substances and improving antioxidant properties, etc., and synergizes with various mechanisms such as inhibiting wax crystal formation, improving fuel dispersion, neutralizing acidic substances and improving antioxidant properties. , comprehensively improve its low-temperature performance. The combined effect of these mechanisms makes 2-ethylimidazole an ideal low-temperature fluidity improver.

3. Supplementary to a variety of biodiesel: Whether the source of biodiesel is rapeseed oil, soybean oil, palm oil or waste edible oil, 2-ethylimidazole can effectively improve its low-temperature fluidity, regardless of whether the source of biodiesel is rapeseed oil, soybean oil, palm oil or waste cooking oil, 2-ethylimidazole can effectively improve its low-temperature fluidity . This shows that 2-ethylimidazole has wide applicability and can meet the needs of different regions and application scenarios.

4. Strong economic feasibility: The amount of 2-ethylimidazole is added is relatively low, and the price is relatively reasonable, and will not significantly increase the production cost of biodiesel. Therefore, it has high economic feasibility in practical applications and is expected to become the preferred additive for low-temperature performance optimization of biodiesel.

Looking forward

Although 2-ethylimidazole has performed well in improving the low-temperature fluidity of biodiesel, there are still some issues that deserve further research and discussion. First, the long-term stability of 2-ethylimidazole and its impact on biodiesel combustion performance need to be further evaluated to ensure its safety and reliability in practical applications. Secondly, the combination effect of 2-ethylimidazole with other additives also needs in-depth research to develop more efficient composite modifiers. Later, with the continuous development of biodiesel technology, how to expand the application of 2-ethylimidazole to other types of renewable energy sources, such as bio and bioaerospace fuels, is also a direction worth exploring.

In short, as a new additive, 2-ethylimidazole provides new ideas and solutions to solve the low-temperature fluidity problem of biodiesel. In the future, with the continuous deepening of research and technological advancement, we believe that 2-ethylimidazole will play a more important role in promoting the widespread application and development of biodiesel.

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