How Biodiesel Produced || How Biodiesel Helps the Environment

How Biodiesel Produced || How Biodiesel Helps the Environment

Biodiesel refers to vegetable oils (such as rapeseed oil, soybean oil, peanut oil, corn oil, cottonseed oil, etc.), animal oils (such as fish oil, lard, tallow, sheep oil, etc.), waste oil or microbial oil, Fatty acid methyl ester or ethyl ester formed by ester conversion. 

biodiesel definition

Biodiesel is a typical “green energy”, which has the characteristics of good environmental performance, good engine starting performance, good fuel performance, a wide range of raw materials and renewable resources. 

Vigorously developing biodiesel has important strategic significance for sustainable economic development, promoting energy substitution, reducing environmental pressure, and controlling urban air pollution. 

Introduction to Biodiesel

Biodiesel is a typical “green energy”, which has the characteristics of good environmental performance, good engine starting performance, good fuel performance, a wide range of raw materials and renewable resources. 

In recent years, many studies have confirmed that whether it is a small, light diesel engine, a large, heavy diesel engine, or a tractor, after burning biodiesel, the hydrocarbons are reduced by 55% to 60%, the particulate matter is reduced by 20% to 50%, and the CO is reduced by more than 45%.

Polycyclic aromatic hydrocarbons are reduced by 75% to 85%. Biodiesel refers to vegetable oils (such as rapeseed oil, soybean oil, peanut oil, corn oil, cottonseed oil, etc.), animal oils (such as fish oil, lard, tallow, sheep oil, etc.), waste oil or microbial oil, and methanol or ethanol Fatty acid methyl ester or ethyl ester formed by ester conversion. 

Vegetable oils and animal fats with fatty acid glycerides (ie, triglycerides) with a certain structural symbol are often used as raw materials for biodiesel.

Fuel characteristics

The fuel performance of biodiesel is close to that of petroleum-based diesel, and it has unmatched performance.

(1) Good ignition performance. Cetane number is a quality index to measure the fuel performance of the fuel in compression ignition engines. Biodiesel has a higher cetane number, greater than 45 (45 for petrochemical diesel), and has better ignition performance than petrochemical diesel.

(2) More fuel. Biodiesel contains 11% more oxygen than petrochemical diesel, and requires less oxygen than petrochemical diesel during combustion, and burns more fully than petrochemical diesel.

(3) Wide applicability. In addition to being an alternative fuel for diesel engines such as buses and trucks, biodiesel can also be used as an alternative fuel for non-road diesel engines such as marine transportation, water power equipment, geological mining equipment, and fuel power plants.

(4) Protect power equipment. Biodiesel has a slightly higher kinematic viscosity than diesel. Without affecting the atomization of the fuel, it is easier to form an oil film on the inner wall of the cylinder, thereby improving the lubricity of the moving parts and reducing the wear of the parts.

(5) Good versatility. No need to modify the diesel engine, it can be directly added and used, and no additional fueling equipment, storage and transportation equipment and special technical training of personnel are required (usually other alternative fuels may need to modify the engine to be used).

(6) Safe and reliable. Biodiesel has a higher flash point than petrochemical diesel, which is conducive to the safe storage and use.

(7) Energy-saving and consumption reduction. Biodiesel itself is the fuel. Mixing it with petrochemical diesel at a certain ratio can reduce fuel consumption and improve power performance.

(8) Strong climate adaptability. Because biodiesel does not contain paraffin, it has good low-temperature fluidity and can be used in a wide range of applications.

(9) Many functions. Biodiesel can not only be used as fuel but also be used as an additive to promote the combustion effect, thus having dual functions.

(10) It has excellent environmental protection characteristics. The low sulfur content of biodiesel makes the emission of SO2 and sulfide low, which can reduce about 30% (70% when there is a catalyst); the biodiesel does not contain aromatic hydrocarbons, which will cause pollution to the environment. Low damage to the human body.

Catalyst-free conditions

In order to solve the problems of high cost, long reaction time, and difficulty in separating the reaction product from the catalyst in the transesterification reaction, a new process was developed without using a catalyst. M. Diasakou et al. studied the transesterification reaction of soybean oil and methanol under heating conditions, carried out a kinetic study, and obtained the characteristics of the reaction in the absence of a catalyst. 

Biodiesel

Alcohol-oil ratio 21: 1, reaction at 235 °C for 10h, methyl ester mass fraction exceeded 85%; alcohol-oil ratio 27: 1,220°C, reaction 8h, methyl ester content mass fraction reached 67%. It was also found that the conversion rate of diglyceride and triglyceride was significantly higher than that of monoglyceride, that is, the first two steps of the three-step reaction proceeded fast while the last step proceeded very slowly in the absence of the catalyst.

In 2001, Sake and Susiana proposed a supercritical one-step process for preparing biodiesel (see Figure 1 below). The reaction was performed in a pre-heated batch reactor. The reaction temperature was 350-400 ° C, the pressure was 45-65 MPa, and the raw material ratio of rapeseed oil to methanol was 1:42. 

The study found that supercritically treated methanol can transesterify with rapeseed oil in the absence of a catalyst, the yield is higher than that of ordinary catalytic processes, and the reaction temperature is lower while avoiding the necessity of using a catalyst The separation and purification process makes the transesterification process more simple, safe and efficient. 

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Hello Friends, My name is Sanjay Bhandari. I am a chemistry Teacher.

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