Biodiesel refers to a renewable diesel fuel that can replace petrochemical diesel oil by using oil crops, wild oil plants, engineering microalgae and other aquatic plant oils, as well as animal oils and restaurant garbage oils as raw materials. Biodiesel is a kind of biomass energy, which is a monoalkyl ester of long-chain fatty acids obtained by pyrolysis of biomass and other technologies. Biodiesel is a mixture of complex organic components with extremely high oxygen content. These mixtures are mainly some organic compounds with high molecular weight, including almost all kinds of oxygen-containing organic compounds, such as ethers, esters, aldehydes, ketones, phenols, organic acids and alcohols. Biodiesel is a kind of high-quality clean diesel oil, which can be extracted from various biomass, so it can be said to be an inexhaustible energy source, and it is expected to replace oil as an alternative fuel in today's increasingly exhausted resources.

Features:

1) The water content is high, up to 31%-45%. Moisture is beneficial to reduce the viscosity and improve the stability of oil, but it reduces the calorific value of oil;

2) The pH value is low, so the storage device is preferably made of acid-resistant materials;

3) The density is higher than that of water, and the ratio with water is about 1.2;

4) It has the tendency of "aging", and the heating temperature should not exceed 81℃, so it should be kept away from light and air.

5) Good lubrication performance.

6) Excellent environmental protection characteristics: low sulfur content, low emission of sulfur dioxide and sulfide, 98% biodegradability of biodiesel, and the degradation rate is twice that of ordinary diesel, which can greatly reduce the environmental pollution caused by accidental leakage;

7) Good low-temperature engine starting performance;

8) Good safety performance: high flash point and safe transportation, storage and use;

production method

a method for synthesizing biodiesel from oil raw materials; Biodiesel prepared from animal oil and its preparation method; Additives for biodiesel and biofuel oil; Emulsifier for light diesel oil produced from waste animal and vegetable oils and its application; Low-cost and pollution-free biomass liquefaction process and device; Low-energy-consumption biomass pyrolysis process and device; A method for preparing biodiesel by rapid pyrolysis of microalgae; Depolymerization kettle for extracting gasoline and diesel oil from waste plastics, waste oil and waste vegetable oil residues, method for preparing fuel gas by biomass gasification and gasification reaction device; Process for extracting petroleum products from vegetable oil residues; A method for preparing synthetic gas by plasma pyrolysis of gasified biomass, and a method for preparing biodiesel by hydrolyzing heterotrophic algae with amylase; A method for producing liquid fuel from biomass; The technological method of producing fuel oil from vegetable oil leftovers, the method of preparing bio-oil from biomass hydrolysis residues, and the production method of extracting gasoline and diesel oil from vegetable oil residues; Device and method for regenerating fuel oil from waste oil; The method of removing colloid from FCC diesel oil; A new environmentally-friendly process for refining fuel oil from waste rubber (waste plastics and waste engine oil), and a chemical refining method for removing total oxidized insoluble matter and colloid from diesel oil; Additives to prevent discoloration and gelation of diesel oil and gasoline; Flocculation separation treatment method of waste lubricating oil.

Application

Biodiesel can be used as fuel for boilers, turbines, diesel engines, etc. The main industrial application is fatty acid methyl ester.

Biodiesel is a kind of high-quality clean diesel oil, which can be extracted from various biomass, so it can be said to be an inexhaustible energy source, and it is expected to replace petroleum as an alternative fuel in today's increasingly exhausted resources.

diesel is the main power fuel for many large vehicles, such as trucks, diesel locomotives and generators. It has the advantages of great power and low price. There is a great demand for diesel in China, and the main problem of diesel application is "black smoke". We often see black smoke trucks on the road. The main cause of black smoke is incomplete combustion, which causes serious air pollution, such as a large amount of particulate dust and high CO2 emission. According to the American Fuel Institute, air pollution caused by engine fuel combustion has become the main problem of air pollution. For example, nitrogen oxides account for half of emissions from other industries, carbon monoxide accounts for two-thirds of emissions from other industries, and toxic hydrocarbons account for half of emissions from other industries. Nitrogen oxides and sulfides discharged from the tail gas can combine with water in the air to form acid rain. Too much carbon dioxide and carbon monoxide in the tail gas will raise the atmospheric temperature, which is often called the "greenhouse effect". In order to solve the problem of tail gas pollution of fuel and the worsening environmental pressure, people began to study the use of other fuels such as fuel alcohol instead of gasoline. At present, fuel alcohol has occupied a considerable proportion in North America such as the United States and Canada and South American countries such as Brazil and Argentina, and cars equipped with fuel alcohol engines have been put on the market. Fuel alcohol is not suitable for most high-powered vehicles that need diesel fuel, such as buses, diesel locomotives and agricultural vehicles such as tractors. Moreover, the tail gas pollution caused by diesel is much greater than that caused by gasoline, so people have developed a substitute for diesel-biodiesel.

In fact, Diesel, the inventor of the engine, said in the report of the Missouri Engineering Conference in the United States in 1912 that "using rapeseed oil as engine fuel does not seem to have much significance today, but it will become as important as oil and coal in the future". In 1983, American scientists first used rapeseed oil methyl ester in engines and burned it for 1111 hours. The renewable fatty acid monoester is defined as biodiesel. In 1984, scientists in the United States and Germany studied the use of fatty acid methyl ester or ethyl ester instead of diesel oil as fuel, that is, using fatty acid monoesters from animals or plants, including fatty acid methyl ester, fatty acid ethyl ester and fatty acid propyl ester, to replace diesel oil for combustion. Compared with traditional petroleum diesel, biodiesel has the following advantages: < P > Using renewable animal and plant fatty acid monoesters as raw materials can reduce the demand and import of petrochemical fuel oil; The environment is good, that emission of toxic organic matt in the tail gas of biodiesel is only one tenth, the particulate matter is 21% of that of ordinary diesel, the emission of carbon monoxide and carbon dioxide is only 11% of that of petroleum diesel, and there is no emission of sulfide, lead and toxic substance; Blending biodiesel can reduce the sulfur concentration from 511PPM(PPM to 5PPM.

there is no need to replace the engine, and the engine is protected.

worldwide application of biodiesel

at present, all countries in the world, especially developed countries, are committed to developing efficient and pollution-free biomass energy utilization technologies. Europe has become the main producer of biodiesel in the world. The United States, Italy and France have successively built dozens of biodiesel production devices.

the United States is the first country to study biodiesel. The total production capacity is 1.3 million tons. The tax rate for biodiesel is 1%. The 611,111-kilometer driving test conducted by the United States in Yellowstone National Park showed no coking phenomenon, and the air pollutant emission was reduced by more than 81%. Moreover, the use of biodiesel also attracted brown bears from 311 kilometers away to the park. B21 in the United States uses 21% biodiesel, and the emission of exhaust pollutants can be reduced by more than 51%. In 1992, both the US Energy Department and the Environmental Protection Agency proposed biodiesel as a clean fuel. In 1999, US President Bill Clinton signed a decree to develop biomass energy, among which biodiesel was listed as one of the key clean energy sources, and the state did not levy taxes on biodiesel. In 1995, Japan began to study the production of biodiesel from the leftover frying oil in restaurants. In 1999, an industrial experimental device with 259 liters/day of frying oil was established to produce biodiesel, which can reduce the raw material cost. At present, the annual output of biodiesel in Japan can reach 411,111 tons.

At present, Germany has eight biodiesel factories, more than 311 biodiesel gas stations, and has set standards for biodiesel, which is tax-free. In 2116, the output of biodiesel reached 1 million tons.

France, Italy and other European countries have established biodiesel enterprises. The French Citroen Group has carried out the experiment of biodiesel, and through the combustion test of 11111 kilometers, it is proved that biodiesel can be used in ordinary diesel engines. Its standard is to add 5% biodiesel to ordinary petroleum diesel.

It can be predicted that biodiesel, as an important clean fuel, will play an important role in the driving of large vehicles.

■ Chemical production of biodiesel

The chemical production of biodiesel is to use bio-oil and low-carbon alcohols such as methanol or ethanol, and use sodium hydroxide (accounting for 1% of the weight of the oil) or Sodium methoxide as a catalyst, and make transesterification reaction under acidic or alkaline catalyst and high temperature (231 ~ 251℃) to generate corresponding fatty acids. Methanol or ethanol can be recycled in the production process, and the production equipment is the same as the general oil-making equipment, and about 11% by-product glycerol is produced in the production process.

However, the chemical synthesis of biodiesel has the following disadvantages: high reaction temperature and complicated process; Excessive methanol is used in the reaction process, and the subsequent process must have corresponding alcohol recovery device, which has complicated treatment process and high energy consumption; Water and free fatty acids in oil raw materials will seriously affect the yield and quality of biodiesel; The product purification is complicated, and the esterification product is difficult to recover; It is difficult to remove the by-products produced by the reaction, and the use of acid-base catalysts produces a lot of wastewater, and the discharge of waste alkali (acid) solution is easy to cause secondary pollution to the environment.

There is also a cost problem that cannot be ignored in chemical production: the use of alkaline catalysts in the production process requires that raw materials must be crude oil, such as unrefined rapeseed oil and soybean oil, and the raw material cost accounts for 75% of the total cost. Therefore, using cheap raw materials and improving the conversion to reduce the cost are the keys to the practical application of biodiesel. Therefore, the United States has begun to study plants with high oil content through genetic engineering (see the "engineering microalgae" method below), Japan uses industrial waste oil and waste frying oil, and Europe grows oil-rich crops on land that is not suitable for growing food.

■ Bio-enzymatic synthesis of biodiesel

In order to solve the above problems, people began to study the bio-enzymatic synthesis of biodiesel, that is, animal fats and low-carbon alcohols were esterified by lipase to prepare the corresponding fatty acid methyl esters and ethyl esters. Enzymatic synthesis of biodiesel has the advantages of mild conditions, low alcohol consumption and no pollution discharge. In 2111, immobilized Rhizopus oryzae cells were used to produce biodiesel in Japan. The conversion rate was about 81%, and microbial cells could be used continuously for 431 hours.

On June 4th, 2115, China Environmental News reported that the pilot plant of bio-diesel produced by biological enzyme method in Tsinghua University was successful, and the yield of bio-diesel reached over 91% in the pilot plant with new technology. The technical indicators of the pilot products meet the biodiesel standards of the United States and Germany, and meet the 1 # excellent diesel standard in China. The engine bench test of the pilot product shows that compared with the commercial petrochemical diesel oil, the concentration of main toxic components such as carbon monoxide, hydrocarbons and smoke in the exhaust gas emitted by the engine is significantly reduced by using the mixed diesel oil containing 21% biodiesel as fuel, and the engine power characteristics are basically unchanged.

People pay more and more attention to biodiesel synthesis by bio-enzymatic method because it has the advantages of mild reaction conditions, low alcohol consumption, no pollutant emission and so on. However, there are some problems to be solved urgently in the preparation of biodiesel by biological enzyme method: lipase is effective in esterification or transesterification of long-chain fatty alcohols, but the conversion rate of short-chain fatty alcohols (such as methanol or ethanol) is low, generally only 41%-61%; Methanol and ethanol are toxic to the enzyme, which is easy to inactivate it. By-products glycerol and water are difficult to recover, which not only form consistency with products, but also are toxic to enzymes. The existence of short-chain fatty alcohol and glycerol affects the reactivity and stability of the enzyme, which greatly shortens the service life of the immobilized enzyme. These problems are the main bottlenecks in the industrial production of biodiesel by biological enzyme method.

■ "engineering microalgae" method of biodiesel

"engineering microalgae" is used to produce diesel oil, which opens up a new technical way for diesel oil production. The National Renewable Laboratory (NREL) of the United States has built "engineering microalgae" through modern biotechnology, that is, an "engineering microcystis" of diatoms. Under laboratory conditions, the lipid content of "engineered microalgae" can be increased to more than 61%, and outdoor production can also be increased to more than 41%, while the lipid content of microalgae is 5%-21% in general natural state. The increase of lipid content in "engineered microalgae" is mainly due to the high expression of acetyl-CoA carboxylase (ACC) gene in microalgae cells, which plays an important role in controlling lipid accumulation. At present, we are studying the selection of appropriate molecular vectors to make ACC gene fully expressed in bacteria, yeast and plants, and further introduce the modified ACC gene into microalgae to obtain more efficient expression. Using "engineering microalgae" to produce diesel oil has important economic and ecological significance, and its advantages are: high microalgae production capacity, saving agricultural resources by using seawater as natural culture medium; It is dozens of times higher than that of terrestrial plants. The biodiesel produced does not contain sulfur, does not emit toxic gases when burning, can be degraded by microorganisms when discharged into the environment, and does not pollute the environment. It is a major trend to develop oily microalgae or "engineering microalgae" to produce biodiesel.

■ Current biodiesel standard

Many countries in the world have drawn up biodiesel standards, thus ensuring the quality of diesel oil and ensuring users to use biodiesel with more confidence.

the international standard of biodiesel is ISO 14214A and the other is ASTM D 6751, which is a standard adopted by the United States and legally confirmed by the United States environmental protection agency in part 211(b) of the Clean Air Act in 2116. Another widely recognized standard is DIN biodiesel series in Germany, which is the most detailed and systematic biodiesel standard so far. The standard system has different DIN standards for different manufacturing raw materials: the RME(rapeseed methyl ester) and PME(vegetable methyl ester) biodiesel DIN E 51616 standards with rapeseed and vegetable seeds as raw materials, and the biodiesel DIN V 51616 standards with vegetable oil and animal fat as mixed raw materials. In October 2113, the European Union also promulgated the standard EN14241 biodiesel fuel. In addition, Austria, Australia, Czech Republic, France, Italy, Sweden and other countries have also drawn up biodiesel fuel specifications.

■ german DIN V 51616 biodiesel standard

the standard of biodiesel mainly evaluates the following components: the whole reaction process of manufacturing, the removal of glycerol, the removal of catalyst, the removal of alcohol, and ensuring that it does not contain free fatty acids. The production standard evaluation indicators of biodiesel include specific gravity, dynamic viscosity, flash point, sulfur content, residue, cetane number, ash, moisture, total impurities, triglyceride, free glycerol and so on. The standardization of biodiesel standards is greatly promoting the formal application and legalization of biodiesel in the automobile industry of these countries. At the same time, the recognition of biodiesel in a large number of countries is also promoting the internationalization of biodiesel as a new renewable bioenergy.

At present, biodiesel is mainly a mixture of biodiesel and petrochemical diesel.