CN108085039A - A kind of method that biomass by hydro-thermal liquefaction bio oil is modified - Google Patents

Abstract

The invention belongs to environmental protections and field of new energy technologies, and in particular to a kind of method that bio oil is modified；This method is using metallic aluminium and the aqueous portion reaction production hydrogen of biomass by hydro-thermal liquefaction bio oil, for bio oil modifying process, a kind of new bio oil method of modifying is provided, that is, improves the quality of bio oil, and realizes the recycling of hydrothermal liquefaction bio oil aqueous portion.

Description

A method for modifying biomass hydrothermally liquefied bio-oil

technical field

The invention belongs to the technical fields of environmental protection and new energy, and in particular relates to a method for modifying biomass hydrothermally liquefied bio-oil.

Background technique

Excessive consumption of fossil energy has caused global energy crisis and environmental problems, and renewable energy has attracted extensive attention of researchers. Biomass is the only renewable energy source that can be converted into liquid fuels, and has become the most promising alternative energy source due to its abundant resources, low cost, and _CO2 balance. Biomass mainly obtains liquid fuel-bio-oil through pyrolysis and hydrothermal liquefaction. Compared with pyrolysis technology, hydrothermal liquefaction has the advantages of wide application range of raw materials, low energy consumption, high calorific value of products, and environmental friendliness. It is considered to be the most promising bio-oil preparation method.

Although the biomass raw materials for preparing bio-oil are different, the main chemical components of bio-oil are relatively similar, mainly composed of hundreds of compounds, including alkanes, phenols, aldehydes, ketones, acids, esters, ethers, alcohols, etc. The presence of oxygen-containing compounds makes bio-oil have poor fuel properties, mainly manifested as high viscosity, low calorific value, poor stability and strong corrosion. For example, aldehydes are very prone to polycondensation reactions, making bio-oil unstable, and the presence of aldehydes makes bio-oil hydrophilic, resulting in high water content and difficult removal of bio-oil; the content of phenolic substances in bio-oil Higher, with a mass fraction as high as 35%, phenolic substances are easily oxidized, reducing the calorific value of bio-oil, and some phenolic compounds (such as guaiacol) can also reduce the stability of bio-oil. Therefore, bio-oils must be modified to improve their stability and chemical properties.

The key to bio-oil modification is to remove oxygen from bio-oil with minimum hydrogen consumption while retaining carbon in it. At present, the commonly used bio-oil modification methods include catalytic cracking, catalytic esterification, and catalytic hydrogenation. The reaction temperature of catalytic cracking is high (500-700° C.), which easily causes coking and deactivation of the catalyst, and the yield of modified bio-oil is low. Catalytic esterification can only convert carboxylic acids and some aldehydes into esters to a certain extent, but the oxygen content in the upgraded bio-oil is still high, which requires further hydrogenation and upgrading.

Catalytic hydrogenation is considered to be the most promising bio-oil modification method. According to the hydrogen supply method, it can be divided into direct hydrogen supply and in-situ hydrogen supply. However, the hydrogenation process consumes a large amount of hydrogen, and every kilogram of bio-oil is completely hydrodeoxygenated. Need to consume 600-1000L of hydrogen. Direct hydrogen supply can greatly reduce the oxygen content of bio-oil, but at present the main source of industrial hydrogen is hydrogen production from fossil fuels or hydrogen production from electrolyzed water. This requires a large amount of energy consumption, resulting in higher costs, and the hydrogenation process is highly dangerous. In the in-situ hydrogen supply, the generation of hydrogen and the modification process of bio-oil are carried out in the same reaction vessel, which avoids the harsh conditions of hydrogen preparation, storage, transportation and hydrogenation for direct external hydrogen supply. Therefore, in-situ hydrogen supply is a more economical and safer hydrogen supply method. The metal hydrolysis reaction is a promising hydrogen production method. The active metals that can react with water include Be, Al, Zn, Mg, Ca, Li, Na, K, etc. Aluminum is the most abundant metal resource on the earth. The theoretical hydrogen production is large (1244mL/g), and the synergy between the aluminum hydrolysis reaction and the bio-oil modification process is strong. Therefore, it can be used as a hydrogen source in the in situ hydrogen modification process of bio-oil.

As a by-product of hydrothermal liquefaction of biomass, the water phase contains more organic matter, including small molecule organic acids, small molecule alcohols, and ketones. Both water and small molecule organic acids in the water phase can react with active metals to generate hydrogen. . By using the water phase to react with metal aluminum, hydrogen can be efficiently produced, used for bio-oil modification, and the resource utilization of the water phase can be realized.

Contents of the invention

The purpose of the present invention is to provide a new type of biomass hydrothermal liquefaction biotechnology in view of the large amount of industrial wastewater produced in the hydrothermal liquefaction process and the current situation of high risk and high cost of external hydrogen supply in the existing bio-oil hydrodeoxygenation modification process. Oil modification method.

The method is realized through the following technical scheme: a method for modifying biomass hydrothermally liquefied bio-oil, which is characterized in that it comprises the following steps:

(1) Put rice straw and deionized water into a high-temperature and high-pressure pilot reactor at a mass ratio of 1:10, and obtain hydrothermally liquefied bio-oil and water phase at a reaction temperature of 320 °C and a residence time of 60 min. ; In the hydrothermal liquefaction process of biomass, the main functions of water are: dispersing raw materials; inhibiting the re-condensation reaction of intermediate products; providing hydrogen source as a hydrogen donor. Appropriately increasing the ratio of rice straw/deionized water can increase the yield of bio-oil, but when the ratio is greater than 1/10, the degree of solubility of biomass in deionized water decreases, the yield of bio-oil shows a downward trend, and the amount of residue increases .

(2) Put aluminum powder, catalyst, hydrothermally liquefied bio-oil and water phase obtained in step (1) into a batch-type high-temperature and high-pressure reactor in a certain proportion, seal the reactor, and then replace the liquid in the reactor with inert gas Air;

(3) Turn on the power to heat up the intermittent high-temperature and high-pressure reactor to the reaction temperature, and maintain a certain reaction time;

(4) After the reaction is over, remove the jacket, and cool the intermittent high-temperature and high-pressure reactor to room temperature with the help of an electric fan, then open the exhaust valve and collect the gas with an air bag;

(5) Open the intermittent high-temperature and high-pressure reaction kettle, pour out the water phase product and part of the residue, and clean the reaction kettle and the pipeline in the kettle with an organic solvent to obtain a mixture of the liquid phase and the residue;

(6) The solid-liquid mixture obtained in step (5) is washed with acetone and filtered under reduced pressure to obtain solid and liquid products, and the liquid product is put into a rotary evaporator to remove absolute ethanol and acetone to obtain an oil-water mixture, and the solid product is subjected to constant temperature Residue after drying;

(7) The oil-water mixture obtained in step (6) is extracted and separated by dichloromethane to obtain a dichloromethane soluble phase and an aqueous phase respectively; the dichloromethane soluble phase is removed from the dichloromethane in a constant temperature rotary evaporator, and A modified bio-oil is obtained.

The catalyst in the step (2) is a dispersed catalyst NiS-MoS; the inert gas is high-purity nitrogen.

In the step (3), turn on the power to raise the temperature of the intermittent high-temperature and high-pressure reactor to 310-370° C., keep the reaction time for 60 minutes, and keep the total pressure at 5-30 MPa.

The organic solvent described in step (5) is the mixture of dehydrated alcohol and acetone.

The temperature of the rotary evaporator described in step (6) is 85° C., the temperature of constant temperature drying is 105° C., the drying time is 12 hours, and the pore size of the organic filter membrane is 0.45 μm.

Beneficial effects of the present invention

1. The present invention mainly modifies the bio-oil, improves its stability and chemical properties, and makes the modified bio-oil available for power equipment.

2. The present invention realizes resource utilization of hydrothermal liquefaction wastewater, which is beneficial to its subsequent treatment.

3. The water phase contains more small molecular organic matter, which decomposes at high temperature to generate hydrogen gas, which is used for hydrogenation of bio-oil.

4. The present invention uses aluminum and water phase reaction to supply hydrogen in situ, which has strong operability and high safety, and avoids the problems of harsh hydrogen preparation, storage, transportation and hydrogenation conditions faced by direct external hydrogen supply.

5. The present invention is an innovation of bio-oil hydrogenation modification technology, and is a beneficial improvement and supplement to this technology;

6. The hydrolysis product (boehmite) of metal aluminum under the condition of bio-oil modification can be used as a high-temperature-resistant insulation material, which is energy-saving and environmentally friendly.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is the reaction flowchart of method for the present invention;

Detailed ways

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Example 1:

A large amount of hydrothermally liquefied bio-oil is prepared by using rice straw in a high-temperature and high-pressure pilot test reactor; the oxygen content of the hydrothermally liquefied bio-oil is 25.62%, and the calorific value is 29.51MJ/kg.

Put 4g of aluminum powder, 10g of hydrothermally liquefied bio-oil, 100g of water phase and 0.3wt% NiS-MoS catalyst (total mass of reactants) into a 500mL intermittent high-temperature and high-pressure reactor, seal the reactor, and then use high-purity nitrogen to Replace the air in the kettle; turn on the power to raise the temperature of the reaction kettle to 310°C, and the reaction time is 60min. After the reaction is over, remove the jacket, cool the reactor to about 30°C with the help of an electric fan, then open the exhaust valve, and collect the gas with an air bag; open the reactor, pour out the water phase product and part of the residue, and use absolute ethanol and The acetone mixed solvent was used to clean the reaction kettle and the pipeline in the kettle to obtain the total solid-liquid mixture; the above mixture was filtered under reduced pressure, and the pore size of the organic filter membrane was 0.45 μm to obtain solid and liquid products, and the liquid products were placed in a constant temperature of 85°C The absolute ethanol and acetone were removed in a rotary evaporator to obtain an oil-water mixture, and the solid product was dried at a constant temperature of 105°C for 12 hours to become a residue. The oil-water mixture obtained above is extracted and separated by dichloromethane to obtain the dichloromethane soluble phase and the water phase respectively; the dichloromethane soluble phase is removed from the dichloromethane in a constant temperature rotary evaporator at 45°C to obtain the modified organism Oil. In this experiment, the oxygen content rate of the modified bio-oil is 19.44%, and the calorific value is 31.58MJ/kg.

Example 2:

Put 4g of aluminum powder, 10g of hydrothermally liquefied bio-oil, 100g of water phase and 0.3wt% NiS-MoS catalyst (total mass of reactants) into a 500mL intermittent high-temperature and high-pressure reactor, seal the reactor, and then use high-purity nitrogen to Replace the air in the kettle; turn on the power to raise the temperature of the reaction kettle to 340°C, and the reaction time is 60min. After the reaction is over, remove the jacket, cool the reactor to about 30°C with the help of an electric fan, then open the exhaust valve, and collect the gas with an air bag; open the reactor, pour out the water phase product and part of the residue, and use absolute ethanol and The acetone mixed solvent was used to clean the reaction kettle and the pipeline in the kettle to obtain the total solid-liquid mixture; the above mixture was filtered under reduced pressure, and the pore size of the organic filter membrane was 0.45 μm to obtain solid and liquid products, and the liquid products were placed in a constant temperature of 85°C The absolute ethanol and acetone were removed in a rotary evaporator to obtain an oil-water mixture, and the solid product was dried at a constant temperature of 105°C for 12 hours to become a residue. The oil-water mixture obtained above is extracted and separated by dichloromethane to obtain the dichloromethane soluble phase and the water phase respectively; the dichloromethane soluble phase is removed from the dichloromethane in a constant temperature rotary evaporator at 45°C to obtain the modified organism Oil. In this experiment, the oxygen content rate of the modified bio-oil is 18.05%, and the calorific value is 32.4MJ/kg.

Example 3:

Put 4g of aluminum powder, 10g of hydrothermally liquefied bio-oil, 100g of water phase and 0.3wt% NiS-MoS catalyst (total mass of reactants) into a 500mL intermittent high-temperature and high-pressure reactor, seal the reactor, and then use high-purity nitrogen to Replace the air in the kettle; turn on the power to raise the temperature of the reaction kettle to 370°C, and the reaction time is 60min. After the reaction is over, remove the jacket, cool the reactor to about 30°C with the help of an electric fan, then open the exhaust valve, and collect the gas with an air bag; open the reactor, pour out the water phase product and part of the residue, and use absolute ethanol and The acetone mixed solvent was used to clean the reaction kettle and the pipeline in the kettle to obtain the total solid-liquid mixture; the above mixture was filtered under reduced pressure, and the pore size of the organic filter membrane was 0.45 μm to obtain solid and liquid products, and the liquid products were placed in a constant temperature of 85°C The absolute ethanol and acetone were removed in a rotary evaporator to obtain an oil-water mixture, and the solid product was dried at a constant temperature of 105°C for 12 hours to become a residue. The oil-water mixture obtained above is extracted and separated by dichloromethane to obtain the dichloromethane soluble phase and the water phase respectively; the dichloromethane soluble phase is removed from the dichloromethane in a constant temperature rotary evaporator at 45°C to obtain the modified organism Oil. In this experiment, the oxygen content rate of the modified bio-oil is 16.23%, and the calorific value is 33.36MJ/kg.

The key to bio-oil modification is to remove oxygen from bio-oil with minimum hydrogen consumption while retaining carbon in it, and temperature is a key factor affecting bio-oil modification. It can be seen from the examples that, when the bio-oil is modified by the method of the present invention, the oxygen content of the bio-oil is significantly reduced and the calorific value is increased with the increase of the modification temperature.

The invention belongs to the technical field of environmental protection and new energy, and specifically relates to a method for bio-oil modification; the method adopts partial reaction of metal aluminum and biomass hydrothermal bio-oil to produce hydrogen, and is used in the bio-oil modification process , providing a novel bio-oil modification method, which not only improves the quality of bio-oil, but also realizes the resource utilization of the water phase of bio-oil.

Although the present invention has been illustrated in conjunction with the preferred embodiments thereof, those skilled in the art will understand that various modifications, substitutions and alterations can be made to the present invention without departing from the spirit and scope of the invention. Accordingly, the invention should not be limited by the above-described embodiments, but by the appended claims and their equivalents.

Claims (5)

1. A method for biomass hydrothermal liquefaction bio-oil modification, is characterized in that, comprises the steps: (1) Put rice straw and deionized water into a high-temperature and high-pressure pilot reactor at a mass ratio of 1:10, and obtain hydrothermally liquefied bio-oil and water phase at a reaction temperature of 320 °C and a residence time of 60 min. ; (2) Put aluminum powder, catalyst, hydrothermally liquefied bio-oil and water phase obtained in step (1) into a batch-type high-temperature and high-pressure reactor in a certain proportion, seal the reactor, and then replace the liquid in the reactor with inert gas Air; (3) Turn on the power to heat up the intermittent high-temperature and high-pressure reactor to the reaction temperature, and maintain a certain reaction time; (4) After the reaction is over, remove the jacket, and cool the intermittent high-temperature and high-pressure reactor to room temperature with the help of an electric fan, then open the exhaust valve and collect the gas with an air bag; (5) Open the intermittent high-temperature and high-pressure reaction kettle, pour out the water phase product and part of the residue, and clean the reaction kettle and the pipeline in the kettle with an organic solvent to obtain a mixture of the liquid phase and the residue; (6) The solid-liquid mixture obtained in step (5) is washed with acetone and filtered under reduced pressure to obtain solid and liquid products, and the liquid product is put into a rotary evaporator to remove absolute ethanol and acetone to obtain an oil-water mixture, and the solid product is subjected to constant temperature Residue after drying; (7) The oil-water mixture obtained in step (6) is extracted and separated by dichloromethane to obtain a dichloromethane soluble phase and an aqueous phase respectively; the dichloromethane soluble phase is removed from the dichloromethane in a constant temperature rotary evaporator, and A modified bio-oil is obtained. 2. the method for a kind of biomass hydrothermal liquefaction bio-oil modification according to claim 1, is characterized in that, the catalyzer in described step (2) is dispersive catalyst NiS-MoS; Described inert gas is High-purity nitrogen. 3. A method for modifying biomass hydrothermally liquefied bio-oil according to claim 1, characterized in that, in the step (3), the power is turned on to heat up the intermittent high-temperature and high-pressure reactor to 310-370°C, Keep the reaction time at 60min and the total pressure at 5-30MPa. 4. a kind of method for biomass hydrothermal liquefaction bio-oil modification according to claim 1, is characterized in that, the organic solvent described in step (5) is the mixture of dehydrated alcohol and acetone. 5. A method for the modification of biomass hydrothermal liquefaction bio-oil according to claim 1, characterized in that the temperature of the rotary evaporator described in step (6) is 85°C, and the temperature of constant temperature drying is 105 °C, the drying time is 12 hours, and the pore size of the organic filter membrane is 0.45 μm.