Synthesis and application of lignin-based carbon materials
AssigneeUniversity of Tennessee Research Foundation
InventorsLu YU, David Paul Harper, David Keffer
Life of this patent
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Abstract
This application relates to the development and use of lignin-based carbon materials which can be used for energy storage and environmental applications. Included are methods of preparing microporous activated carbon having a controlled, often high surface area and a controlled often high mesopore ratio, and a method of preparing carbon dots, for example carbon quantum dots.
Claims23
A method of preparing microporous activated carbon having a controlled surface area, comprising the steps of:
- providing a lignin including one or more of softwood lignin, hardwood lignin, and herbaceous lignin;
- carbonizing the lignin at an elevated temperature of at least about 700° C. to produce a carbonized lignin;
- and
- activating the carbonized lignin by mixing it with potassium hydroxide at a mass ratio of about 1:3 to about 1:5 and an elevated temperature of at least about 700° C. to yield the microporous activated carbon;
- wherein the microporous activated carbon has a controlled surface area of about 50 to about 3500 m2/g and a controlled mesopore ratio of about 10% to about 80%.
A method of preparing carbon dots, comprising the steps of:
- providing a lignin;
- carbonizing the lignin at an elevated temperature of at least about 700° C. in an inert environment for at least about 0.5 hour to produce a carbonized lignin;
- physically activating the carbonized lignin at a temperature of about 700° C. to about 800° C. in the presence of steam for at least about 0.5 hour, followed by exposing the activated carbon to carbon dioxide to a temperature of at least about 700° C. for at least about 0.5 hour, to yield activated carbon;
- treating the activated carbon with concentrated nitric acid;
- washing the activated carbon to obtain neutralized activated carbon;
- mixing the neutralized activated carbon with hydrogen peroxide and solvent to yield a mixture;
- heating the mixture to at least about 110° C. for at least about 1.5 hours to yield the carbon dots;
- and
- separating the carbon dots from the mixture.
A method of preparing microporous activated carbon having a high surface area, comprising the steps of:
- providing a softwood lignin;
- mixing the softwood lignin with potassium hydroxide at a mass ratio of about 1:3 to about 1:5 and an elevated temperature of about 700° C. to about 900° C. for about 1 hour to about 3 hours to activate the lignin;
- simultaneously carbonizing the lignin at the elevated temperature yield the microporous activated carbon;
- wherein the microporous activated carbon has a surface area of at least about 2500 m2/g and a mesopore ratio of at least about 70%.
Dependencies are inferred from the claim text.