Bio-oil light fraction-based bread-shaped porous activated carbon, method for preparing the same and use thereof
A bio-oil light fraction-based bread-shaped porous activated carbon, a method for preparing the same and use thereof are provided. A light fraction prepared by fast pyrolysis of a biomass coupled with molecular distillation is selected as a precursor; an activator is directly mixed with the light fraction and stirred to obtain a homogeneous liquid; then, the homogeneous liquid is subjected to one-step carbonization and activation at a two-stage temperature in an inert atmosphere; after the activation, the obtained solid was washed and filtered, the activator reaction products and impurities are removed, and then dried to obtain the activated carbon used as an electrode carbon material of a supercapacitor. The method fully utilizes the rich micromolecule compounds such as water, acids, ketones, aldehydes, monophenols and the like in the obtained light fraction, and the micromolecule compounds and water can interact with the activator.
1 . A method for preparing a bio-oil light fraction-based porous activated carbon, comprising the following steps of:
carrying out molecular distillation on bio-oil obtained by pyrolysis of biomass to obtain a light fraction, wherein the light fraction is in a liquid phase;
using the light fraction as a carbon precursor raw material, and mixing an activator with the light fraction to form a mixed solution, wherein the activator is a solid water-soluble active metal alkali or salt; and
subjecting the mixed solution to continuous thermal treatment in which carbonization and chemical activation of the carbon precursor occur concurrently to obtain the bio-oil light fraction-based porous activated carbon, wherein the bio-oil light fraction-based porous activated carbon has a three-dimensional porous internal structure with a density of 0.01-0.03 g/cm 3 .
2 . The method according to claim 1 , wherein the step of carbonization and chemical activation comprises multi-stage heating.
3 . The method according to claim 2 , specifically comprising the following steps:
S1, firstly, preparing bio-oil obtained by pyrolysis of biomass, carrying out molecular distillation on the bio-oil to obtain the light fraction, then mixing the activator with the light fraction according to a predetermined mass ratio and stirring for a predetermined time to obtain a mixed homogeneous liquid of the light fraction and the activator, subjecting the mixed homogeneous liquid to two-stage heating and one-step carbonization and activation under a protection of an inert gas, and cooling to room temperature to obtain an impurity-containing bio-oil light fraction-based porous activated carbon;
S2, grinding the impurity-containing bio-oil light fraction-based porous activated carbon obtained in step S1 and sieving for the first time, washing and stirring with a hydrochloric acid solution, then repeatedly washing and suction filtering with deionized water until a filtrate is neutral, so as to remove activator reaction products and impurities in the solid product, drying, grinding again and sieving for the second time, and obtaining the bio-oil light fraction-based porous activated carbon.
4 . The method according to claim 1 , wherein the mixed solution is stirred by a magnetic stirrer to obtain a uniform mixed solution.
5 . The method according to claim 1 , specifically comprising the following steps:
S1, firstly, preparing bio-oil obtained by pyrolysis of biomass, carrying out molecular distillation on the bio-oil to obtain the light fraction, then mixing the activator with the light fraction according to a predetermined mass ratio and stirring for a predetermined time to obtain a mixed homogeneous liquid of the light fraction and the activator, subjecting the mixed homogeneous liquid to two-stage heating and one-step carbonization and activation under a protection of an inert gas, and cooling to room temperature to obtain an impurity-containing bio-oil light fraction-based porous activated carbon;
S2, grinding the impurity-containing bio-oil light fraction-based porous activated carbon obtained in step S1 and sieving for the first time, washing and stirring with a hydrochloric acid solution, then repeatedly washing and suction filtering with deionized water until a filtrate is neutral, so as to remove activator reaction products and impurities in the solid product, drying, grinding again and sieving for the second time, and obtaining the bio-oil light fraction-based porous activated carbon.
6 . The method according to claim 5 , wherein in step S1, the mixed homogeneous liquid of the light fraction and the activator is obtained by adding the activator with a predetermined mass ratio to the light fraction, and stirring for 0.5-2 hours with a magnetic stirrer to obtain a uniform mixture.
7 . The method according to claim 5 , wherein in step S1, the inert gas is one or more selected from the group consisting of nitrogen, argon and helium.
8 . The method according to claim 5 , wherein conditions of the two-stage heating and the one-step carbonization and activation in step S1 are as follows: a first stage has a final heating temperature of 300-500° C., a heating rate of 2-10° C./min and a heating time of 0.5-3 hours, and a second stage has a final heating temperature of 700-900° C., a heating rate of 2-10° C./min and a heating time of 1-3 hours.
9 . The method according to claim 5 , wherein in step S2, after the sieving for the first time, the impurity-containing bio-oil light fraction-based porous activated carbon is washed with a 0.5-2 M hydrochloric acid solution, stirred by a magnetic force for 3-6 hours, and then repeatedly washed with deionized water and filtered by suction.
10 . The method according to claim 1 , wherein the step of carbonization and chemical activation comprises two-stage heating.
11 . The method according to claim 10 , specifically comprising the following steps:
S1, firstly, preparing bio-oil obtained by pyrolysis of biomass, carrying out molecular distillation on the bio-oil to obtain the light fraction, then mixing the activator with the light fraction according to a predetermined mass ratio and stirring for a predetermined time to obtain a mixed homogeneous liquid of the light fraction and the activator, subjecting the mixed homogeneous liquid to two-stage heating and one-step carbonization and activation under a protection of an inert gas, and cooling to room temperature to obtain an impurity-containing bio-oil light fraction-based porous activated carbon;
S2, grinding the impurity-containing bio-oil light fraction-based porous activated carbon obtained in step S1 and sieving for the first time, washing and stirring with a hydrochloric acid solution, then repeatedly washing and suction filtering with deionized water until a filtrate is neutral, so as to remove activator reaction products and impurities in the solid product, drying, grinding again and sieving for the second time, and obtaining the bio-oil light fraction-based porous activated carbon.
12 . The method according to claim 1 , wherein the light fraction is obtained by preparing bio-oil from a cellulose biomass by fast pyrolysis and then subjecting the bio-oil to the molecular distillation.
13 . The method according to according to claim 12 , wherein the cellulose biomass is one or more selected from the group consisting of fruit shell, sawdust, straw, bamboo, walnut shell, poplar sawdust and corn straw.
14 . The method according to according to claim 1 , wherein the molecular distillation adopts a molecular distillation pressure of 10-3,000 Pa and a working pressure of a short-range distiller of 0.001-1 mbar.
15 . The method according to according to claim 1 , wherein the light fraction comprises the following components in parts by mass: 15-50 parts of water, 20-30 parts of acids, 5-15 parts of ketones, 5-10 parts of aldehydes and 10-20 parts of monophenols.
16 . The method according to according to claim 1 , wherein the activator is one or more selected from the group consisting of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate and sodium bicarbonate.
17 . The method according to claim 1 , wherein a mass ratio of the activator to the light fraction is 1:22 to 1:3.