A NOVEL METHOD FOR CARBONIZING LIGNOCELLUOSIC MATERIAL AS A POWDER

Abstract

The present invention provides a novel cost efficient method for carbonizing lignocellulosic material to carbonized particles or agglomerates, preferably carbon powder. Also uses of said particles or agglomerates are disclosed.

Claims

1. A method for manufacturing carbonized particles or agglomerates, wherein said method is continuous or semi-continuous, comprising the following steps: a) providing a dried raw material in powder form emanating from a ligno-cellulosic material, and suspending and/or diluting said raw material in a fluidic medium, and b) carbonization of the raw material in said fluidic medium, at a temperature range of from about 600 to about 2500° C., thus providing one or more carbonized particles or agglomerates c).

2. The method according to claim 1 wherein the carbonization of step b) comprises conveying the raw material in the fluidic medium, in an inert gas mix, into a hot chamber, and continuously thermally treating said raw material in the fluidic medium during a time period of from about one millisecond up to about a quarter of an hour, thereby providing carbonized particles or agglomerates.

3. The method according to claim 2 wherein the inert gas mix consists of nitrogen and carbon-dioxide.

4. The method according to claim 1 wherein the raw material of step a) is above 90% dry solids.

5. A method according to claim 1 wherein the raw material in step a) has been pre-treated, such as homogenized, milled, crushed and/or impregnated with a fluidic medium.

6. The method according to claim 1 wherein the raw material of step a) has been milled to a defined particle size, involving also treatment with aiding agents, namely impregnation with a liquid, solvent, salt, water, or a mixture thereof.

7. A method according to claim 18 wherein the resulting carbonized particles or agglomerates from step b) are separated, wherein said separation involves extraction and/or collection, from the fluidic medium before step c) post-treatment.

8. The method according to claim 18 wherein the post-treatment of step c) includes milling, impregnating and/or coating of said carbonized particles or agglomerates to defined particle size, surface properties, surface polarization and/or affinity for certain substances.

9. A method according to claim 1 yielding carbonized particles or agglomerates having a BET surface area of above 100 m.sup.2/g.

10. A method according to claim 9 wherein the carbonized particles or carbonized agglomerates therein exhibit dimensions from about 1 nm to about 1 mm.

11. Carbonized particles or agglomerates obtainable by the method according to claim 1.

12. (canceled)

13. The method according to claim 1, wherein said carbonized particles or agglomerates are in the form of a carbon powder.

14. The method according to claim 1, wherein said carbonized particles or agglomerates are in the form of an electrically conductive carbon powder.

15. The method according to claim 1, wherein the ligno-cellulosic material of step a) is lignin.

16. The method according to claim 1, wherein the carbonization of the raw material in said fluidic medium of step c) is at a temperature range from about 900 to about 1800° C.

17. The method according to claim 1, wherein the carbonization of the raw material in said fluidic medium of step c) is at a temperature range from about 1000 to about 1400° C.

18. The method according to claim 1, further comprising, c) a post treatment step.

19. The method according to claim 2, wherein the hot chamber is a furnace system.

20. The method according to claim 2, wherein the carbonized particles are in the form of a carbon powder.

21. The method according to claim 8, wherein the carbonized particles or agglomerates are in the form of a carbon powder.

22. A method according to claim 1 yielding carbonized particles or agglomerates having a BET surface area from about 130 to about 1000 m.sup.2/g.

23. A method according to claim 9 wherein the carbonized particles or carbonized agglomerates therein exhibit dimensions from about 10 nm to about 500 μm.

24. A method according to claim 9 wherein the carbonized particles or carbonized agglomerates therein exhibit dimensions from about 10 nm to about 250 μm.

25. Carbonized carbon powder obtainable by the method according to claim 1.

Description

BRIEF DESCRIPTION OF FIGURES

[0046] FIG. 1 depicts the process flow of the present invention.

[0047] FIG. 2 illustrates a schematic overview of the present method in a first embodiment

[0048] FIG. 3 illustrates a schematic overview of the present method in a second embodiment

[0049] FIG. 4 illustrates a schematic overview of the present method in a third embodiment

[0050] FIG. 5a shows a SEM scan of the obtained product

[0051] FIG. 5b shows a SEM scan of the obtained product

[0052] FIG. 6a shows a SEM scan of the obtained product

[0053] FIG. 6b shows a SEM scan of the obtained product

[0054] FIG. 7a shows a TEM analysis of the obtained product

[0055] FIG. 7b shows a TEM analysis of the obtained product

[0056] FIG. 8 shows a TEM analysis of the obtained product

[0057] FIG. 9 illustrates a schematic overview of the presented method whereby also the product thereof is further used in plastic parts.

EXAMPLE

[0058] The present invention according to the first aspect was realized in a form as depicted in FIG. 4. The process direction in this case was from bottom to top upwards. The biomass used as solid feedstock was a kraft lignin from softwood. The approximately 95 wt % dry content lignin was mixed into a dilute phase state with nitrogen and fed continuously by injection of a second gas into the stream and directly onward into the heat treatment chamber—in this case a circular shaped tube. The injection gas employed was a carbon dioxide. Thus a gas mixture of 50 vol % nitrogen and 50 vol % carbon dioxide was mixed with the lignin continuously. This mixture was conveyed into the hot furnace tube and the resulting solid as well as gaseous products were exiting the tube at the top end.

[0059] The process temperature was set to 1400° C. in the middle level of the tube. The solid feeding was dosed in steps between 5 g/min to 15 g/min. The time span in the hot zone was an estimated average of maximum 3 seconds.

[0060] The exiting material stream consisting of a gas-solid-mix, was cooled by an injected inert gas flow which was at room temperature (ca. 20° C.). The cooled gas-solid-mix was pumped through a ceramic filter cloth, on which surface the solid, particulate product was collected.

[0061] FIG. 5a to FIG. 8 show SEM as well as TEM analysis of the results. It is clearly visible that the products, which emanated from kraft lignin from softwood treated with the presented carbonization method, are mainly spherical carbon particles. The yielding materials are carbon spheres in the range of a few nm in diameter up to approximately 100 μm. Agglomerated state of tiny particles is also evident.

[0062] FIG. 5b shows examples of the resulting spherical particles in a collapsed as well as open structure form. Clearly visible is thus the hollow nature of these larger spheres.

[0063] FIG. 7a and FIG. 7b show scanning transmission electron microscopy analysis of the lower diameter fraction of the product. Here the dimensions on the lower diameter range of several nm to dozens of nm are clearly visible. Also the tendency of the individual spheres or particles to form agglomerates is evident.

[0064] FIG. 8 shows a high resolution transmission electron microscopy analysis of such a smaller particle. It is clearly visible that there is some regular spacing between the molecular structures which have little or no apparent preferred orientation. The analysis of the yielded product also suggests that there are domains with aromatic stacking inside the crystalline structure. The spacing of these crystalline structures is in the range of so called graphitic stacking or layering.

[0065] The BET Surface area for the product obtainable from the method according to the first aspect was 138.18 m.sup.2/g.

[0066] Various embodiments of the present invention have been described above but a person skilled in the art realizes further minor alterations, which would fall into the scope of the present invention. The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. For example, any of the above-noted methods may be combined with other known methods. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.