CN104099120A - Method for preparing aviation liquid fuel by using biodiesel - Google Patents

Abstract

The invention relates to a method for preparing aviation liquid fuel by utilizing biodiesel (fatty acid methyl ester). Add 2 to 3 times the volume of water-methanol mixture to the raw material biodiesel, and add 1 to 5% of the weight of the biodiesel with alkali, hydrolyze at 30 to 100°C, and synthesize long carbon by electrolysis in an electrolytic cell after hydrolysis chain alkanes; the above-mentioned long carbon chain alkanes after electrolysis are subjected to catalytic cracking under normal pressure at 300 ° C ~ 450 ° C, through a catalyst, at a volume space velocity of 0.2 ~ 2.0h ^-1 ; and then in normal pressure Under 220°C~350°C, using mordenite as catalyst, the volume space velocity is controlled at 0.5~2.5h ^-1 isomerization reaction; the product after isomerization reaction is distilled, and the collection cutting temperature is 105~240° The fraction between C can be used to obtain refined aviation fuel blending components. The invention has simple and stable process, mild reaction conditions, low energy consumption and high product yield.

Description

A kind of method utilizing biodiesel to prepare aviation liquid fuel

technical field

The invention relates to the field of clean energy production, in particular to a method for preparing aviation liquid fuel by using biodiesel.

Background technique

At present, the air transport industry is playing an increasingly important role in the process of economic globalization. The number of air transport of personnel and cargo by air is increasing at an annual rate of 4.9% and 5.3%, and the use of aviation fuel also accounts for 8% of the total output of petroleum products. %. According to statistics, in 2008, the global air transport industry emitted 677 million tons of carbon dioxide. Although the air transport industry's carbon dioxide emissions accounted for only 2% of the global total, as a cross-regional global aviation industry, its impact is still significant. Can not be ignored. In order to reduce the impact of aviation emissions on the environment, the International Air Transport Association (IATA) has committed to achieve a 50% reduction in net carbon emissions by 2050 compared to 2005. From 2012, in order to meet the aviation emission reduction target, the European Union will impose a carbon emission tax on all commercial flights arriving and departing from the European Union. More than 2,000 airlines will be included in the EU ETS, including 35 Chinese companies. At that time, the annual cost of global airlines will increase by 3.5 billion euros, and airlines around the world, including China, are actively seeking solutions to cope with the dual pressures of sharp fluctuations in aviation fuel prices and aviation carbon emission reduction. Although improving aircraft combustion efficiency and airline operating efficiency can play a certain role, it cannot fundamentally reduce carbon emissions. Therefore, the development of the second generation of renewable aviation bio-alternative fuels is a major way out for the aviation industry to reduce emissions and fuel costs. According to the report of the International Air Transport Association, the second-generation biofuel is expected to be officially commercialized in the air transport industry in 2012, which can reduce greenhouse gas emissions by up to 96%.

The production capacity of EU biodiesel in 2005 was 6.07 million tons, and by 2010 the promotion of biodiesel reached 8.3 million tons. Since 1993, Japan has started research and experimentation on biodiesel, and in 1999, it established an industrial experimental device for producing biodiesel with frying oil as raw material, with a production capacity of 259L/d. At present, the annual production of biodiesel in Japan can reach 400,000 tons. my country's biodiesel industry officially started in 2001. At present, a number of production enterprises have been established, and the annual output of biodiesel can reach about 1 million tons. However, biodiesel cannot be directly used as aviation fuel due to its high oxygen content (about 10%) and high condensation point. At present, the production process of aviation fuel for oxygen-containing raw materials such as biodiesel is mainly catalytic decarboxylation process and hydrodeoxygenation process. The catalytic decarboxylation process is mainly based on gutter oil as raw material through filter residue, desalination, dehydration, and decolorization, and then adding a decarboxylation catalyst to react. Bio-jet fuel. However, the hydrodeoxygenation method has high reaction temperature, high operating pressure, low yield, and high requirements for the use of catalysts. Typical processes include the Bio-Synfining ^TM process technology developed by Syntroleum, and the Ecofining ^TM SPK process technology developed by Honeywell UOP. There is no report on the conversion of biodiesel (fatty acid methyl ester) into aviation liquid fuel by electrolytic deoxygenation technology.

Contents of the invention

The purpose of the present invention is to provide a method for preparing aviation liquid fuel by using biodiesel.

The technical scheme that the present invention adopts for realizing the above object is:

A method for preparing aviation liquid fuel by using biodiesel, comprising electrolytically synthesizing biodiesel, catalytic cracking/isomerization, and atmospheric distillation, specifically:

Electrolytic synthesis: Add 2 to 3 times the volume of water-methanol mixture to the raw material biodiesel (fatty acid methyl ester, C ₁₄ -C ₂₀ ), and add alkali with a mass percentage of 1 to 5% of the raw material, at 30 to 100° C is hydrolyzed, and electrolytically synthesized in an electrolytic cell to obtain long carbon chain alkanes after hydrolysis;

Catalytic cracking/isomerization reaction: Catalytic cracking is performed on the above-mentioned long carbon chain alkanes after electrolysis at 300°C-450°C under normal pressure with a catalyst at a volume space velocity of 0.2-2.0h ^-1 ; Then at 220°C-350°C under normal pressure, using mordenite as a catalyst, the volume space velocity is controlled at 0.5-2.5h ^-1 isomerization reaction;

Atmospheric distillation: the product after the isomerization reaction is distilled, and the fraction with a cutting temperature between 105 and 240°C is collected to obtain refined aviation fuel blending components.

Catalytic cracking reaction is carried out again for the fraction with the above-mentioned cut-off temperature higher than 240°C.

Keep the biodiesel with the oxygen content at 10-15%, and completely remove the oxygen in the raw material biodiesel through electrolytic synthesis.

The catalytic cracking catalyst is zeolite molecular sieve, ZSM-5, ZSM-11, ZSM-22, ZSM-23, HY molecular sieve or NaY molecular sieve.

The current density in the electrolytic synthesis process is higher than 50mA/cm ² ; the anode material is platinum, glassy carbon or stainless steel.

The processes of hydrolysis and electrolysis of biodiesel are carried out simultaneously in the same reaction device; catalytic cracking and isomerization reactions can be carried out simultaneously in the same reactor.

The advantages of the present invention: compared with the existing hydrocracking technology, the present invention has simple and stable process, mild reaction conditions, low energy consumption, high product yield, good safety, stability and combustion performance, and can significantly Solve the problems of high freezing point, high oxygen content and easy oxidation of biodiesel. The prepared aviation fuel product has low sulfur content, the condensation point can reach below -40°C, the viscosity meets the requirements, the combustion is complete, and the pollution is small, so it can be used as a blending component of current commercial aviation fuel. The process of adopting the process of the present invention does not discharge pollutants and wastes in the production process, which meets the current domestic environmental protection requirements. At the same time, high-quality hydrogen, paraffin, propylene, etc. are produced by-products in the production process, which is suitable for large-scale industrial production.

Description of drawings

Fig. 1 is a process flow diagram provided by an embodiment of the present invention.

Detailed ways

Example 1

Electrolytic synthesis: Add 2 times the volume of water-methanol mixture to the raw material biodiesel (fatty acid methyl ester, C ₁₄ -C ₂₀ ), and add 3% by weight of raw material sodium hydroxide to maintain the temperature at 45°C, so that Hydrolysis of fatty acid methyl esters in biodiesel to fatty acids/fatty acid salts. Then electrolyze the mixed solution after hydrolysis, the anode uses a platinum electrode, and the current density is controlled at 150mA/cm ² , the alkanes with long carbon chains will be precipitated on the surface of the platinum electrode, and the oxygen in the raw material will escape in the form of carbon dioxide . At the same time, the high value-added hydrogen precipitated on the electrode surface can be widely used in related chemical industries. Wherein, the volumes of water and methanol in the water-methanol mixture are the same.

Composition list of fatty acid methyl esters in biodiesel feedstock in this example

Methyl ester component Percentage wt.% C ₁₄ :0 6.37 C ₁₆ :0 -- C ₁₆ :1 5.26 C ₁₈ :0 3.92 C ₁₈ :1 55.73 C ₁₈ :2 26.98 C ₂₀ :0 1.74

Catalytic cracking/isomerization reaction: Catalytic cracking of the long carbon chain alkanes after electrolysis at 350°C under normal pressure, using ZSM-5 molecular sieve as a catalytic cracking catalyst, at a volume space velocity of 0.5h ^-1 , the liquid product after the reaction mainly contains hydrocarbons with a carbon number of 5 to 20, and the gas product is mainly propylene and butene; the liquid product collected from the catalytic cracking reaction is subjected to an isomerization reaction to reduce the condensation point of the product, that is Mordenite was used as the isomerization catalyst, the reaction temperature was controlled at 350°C, and the volume space velocity was controlled at 1.5h ^-1 . The liquid product after the reaction still contains carbon number between 5 and 20, and the gas product is very little.

Atmospheric distillation: The product after the isomerization reaction is rectified, and the fraction with a cutting temperature between 105 and 240°C is collected, which is the blending component of aviation fuel (that is, hydrocarbon compounds, C5-C16). The fraction at 240°C is subjected to catalytic cracking reaction again. The reaction conditions of the recycled material are exactly the same as those of the raw material for catalytic cracking, and the recycled material is mixed with the biodiesel feedstock. The aviation fuel product has a conversion rate of 60% from biodiesel feedstock.

Example 2

Electrolytic synthesis: add 3 times the volume of water-methanol mixture to the raw material biodiesel, and add 5% by weight of raw material sodium hydroxide to maintain the temperature at 60°C, so that the fatty acid methyl ester in the biodiesel is hydrolyzed into fatty acid/fat salt. Then the mixed solution after hydrolysis is electrolyzed. The anode uses a platinum electrode, and the current density is controlled to 200mA/cm ² . Long carbon chain alkanes will be precipitated on the surface of the platinum electrode, and the oxygen in the raw material will escape in the form of carbon dioxide. Wherein, the volume ratio of water and methanol in the water-methanol mixture is 2:1.

Composition list of fatty acid methyl esters in biodiesel feedstock in this example

Methyl ester component Percentage wt.% C ₁₄ :0 0.71 C ₁₆ :0 0.66 C ₁₆ :1 1.00 C ₁₈ :0 1.43

C ₁₈ :1 34.23 C ₁₈ :2 61.31 C ₂₀ :0 0.59

Catalytic cracking/isomerization reaction: Catalytic cracking of the long carbon chain alkanes after electrolysis at 410°C under normal pressure, with HY molecular sieves as catalytic cracking catalysts, under the action of a volume space velocity of 0.8h ^-1 , the reaction The final liquid product mainly contains hydrocarbons with a carbon number of 5 to 20, and the gas products are mainly propylene and butene; the liquid product collected from the catalytic cracking reaction is then subjected to an isomerization reaction to reduce the condensation point of the product, that is, using mercerizing Zeolite is used as an isomerization catalyst, the reaction temperature is controlled at 320°C, and the volume space velocity is controlled at 1.0h ^-1 . The liquid product after the reaction contains carbon numbers still kept between 5 and 20.

Atmospheric distillation: The product after the isomerization reaction is rectified, and the fraction with a cutting temperature between 105 and 240°C is collected, which is the blending component of aviation fuel. The fraction with a cutting temperature higher than 240°C is subjected to catalytic cracking reaction again. The reaction conditions of the recycled material are exactly the same as those of the raw material for catalytic cracking, and the recycled material is fed separately. The aviation fuel product has a conversion rate of 55% from biodiesel feedstock.

Example 3

Electrolytic synthesis: Add 2 times the volume of water-methanol mixture to the raw material biodiesel, and add 2.5% by weight of raw material sodium hydroxide to maintain the temperature at 70°C, so that the fatty acid methyl ester in the biodiesel is hydrolyzed into fatty acids/fats salt. Then electrolyze the hydrolyzed mixed solution. The anode uses a glassy carbon electrode, and the current density is controlled at 180mA/cm ² . Alkanes with long carbon chains will be precipitated on the surface of the platinum electrode, and the oxygen in the raw material will escape in the form of carbon dioxide. Wherein, the volume ratio of water and methanol in the water-methanol mixture is 1.5:1.

Composition list of fatty acid methyl esters in biodiesel feedstock in this example

Methyl ester component Percentage wt.% C ₁₄ :0 -- C ₁₆ :0 -- C ₁₆ :1 0.92 C ₁₈ :0 3.56 C ₁₈ :1 82.60 C ₁₈ :2 12.62 C ₂₀ :0 0.30

Catalytic cracking/isomerization reaction: Catalytic cracking of the above-mentioned long carbon chain alkanes after electrolysis at 450°C under normal pressure, using ZSM-11 molecular sieve as a catalytic cracking catalyst, under a volume space velocity of 1.2h ^-1 , the liquid product after the reaction mainly contains hydrocarbons with a carbon number of 5 to 20, and the gas products are mainly propylene and butene; the liquid product collected from the catalytic cracking reaction is subjected to an isomerization reaction to reduce the condensation point of the product, that is Mordenite was used as the isomerization catalyst, the reaction temperature was controlled at 300°C, and the volume space velocity was controlled at 0.8h ^-1 . The liquid product after the reaction contains carbon numbers still kept between 5 and 20.

Atmospheric distillation: The product after the isomerization reaction is rectified, and the fraction with a cutting temperature between 105 and 240°C is collected, which is the blending component of aviation fuel. The fraction with a cutting temperature higher than 240°C is subjected to catalytic cracking reaction again. The reaction conditions of the recycled material are exactly the same as those of the raw material for catalytic cracking, and the recycled material is fed separately. The aviation fuel product has a conversion rate of 55% from biodiesel feedstock.

After testing: the overall conversion rate of aviation liquid fuel prepared in each of the above examples is above 55%, and its physical properties are: density (15°C) 794.9kg/m ³ , freezing point -52°C, flash point 46°C , acid value 0.086mg KOH/g, viscosity (-20°C) 1.30mm ² /s, net calorific value 49.1MJ/kg, colloid content 6.5mg/100ml, good low temperature fluidity and combustion performance .

The technical solutions of the present invention are not limited within the scope of the embodiments described in the present invention. The technical contents not described in detail in the present invention are all known technologies.

Claims (6)

1. utilize biofuel to prepare a method for aviation liquid fuel, biofuel, through electrolytic synthesis, catalytic cracking/isomerization reaction, air distillation, be is characterized in that:

Electrolytic synthesis: to raw material biofuel (fatty acid methyl ester, C ₁₄-C ₂₀) in add the water-methanol mixture of its 2～3 times of volumes, and add the alkali of raw materials quality per-cent 1～5%, in 30～100 ° of C hydrolysis, after hydrolysis, in electrolyzer, electrolytic synthesis obtains the alkane of long carbochain;

Catalytic cracking/isomerization reaction: by the alkane of long carbochain after above-mentioned electrolysis under normal pressure in 300 ° of C～450 ° C, through catalyzer, with 0.2～2.0h ^-1volume space velocity under effect carry out catalytic cracking; Then be the lower 220 ° of C～350 ° C of normal pressure, using mordenite as catalyzer, volume space velocity is controlled at 0.5～2.5h ^-1isomerization reaction;

Air distillation: the product after isomerization reaction is processed through distillation, collects the cut of cutting temperature between 105～240 ° of C and can obtain refining aviation fuel blend component.

2. by the method for utilizing biofuel to prepare aviation liquid fuel claimed in claim 1, it is characterized in that: the cut catalytic cracking reaction again by cutting temperature higher than 240 ° of C.

3. by the method for utilizing biofuel to prepare aviation liquid fuel claimed in claim 1, it is characterized in that: described oxygen level is remained on to 10～15% biofuel, by electrolytic synthesis, the oxygen in raw material biofuel is removed completely.

4. by the method for utilizing biofuel to prepare aviation liquid fuel claimed in claim 1, it is characterized in that: the catalyzer of described catalytic cracking is zeolite molecular sieve, ZSM-5 ZSM-11, ZSM-22, ZSM-23, HY molecular sieve or NaY molecular sieve.

5. by the method for utilizing biofuel to prepare aviation liquid fuel claimed in claim 1, it is characterized in that: in described electrolytic synthesis process, current density is higher than 50mA/cm ²; Anode material is platinum, glass carbon, graphite or stainless steel.

6. by the method for utilizing biofuel to prepare aviation liquid fuel claimed in claim 1, it is characterized in that: the hydrolysis of described biofuel and the process of electrolysis are carried out in same reaction unit simultaneously; Catalytic cracking and isomerization reaction can be carried out in same reactor simultaneously.