Single mode microwave device for producing exfoliated graphite
A device for producing exfoliated graphite from graphite flakes, intercalated graphite, or expanded graphite by means of microwave heating using single mode microwave cavities, a method of producing such materials and products from such methods.
1. A method of exfoliating a nanomaterial said method comprising:
A. providing a nanomaterial;
B. placing the nanomaterial in a hollow cavity of a device, said device being a single mode microwave device, said single mode microwave device comprising:
a stainless steel housing comprised of a top, a bottom, two side walls, a front, and a moveable back wall, all forming a hollow cavity; said moveable wall having a back surface, and fixedly attached to said back surface, a control rod;
contained within said housing, an exfoliation tray, said exfoliation tray supported by at least two support rods, which rods are supported at predetermined levels by the side walls, said exfoliation tray being electrically non-conducting;
said bottom, front wall, and side walls having a cooling jacket mounted on outside surfaces;
an adapter surmounting the top of the housing;
said moveable back wall having at least one gas inlet port therethrough;
said bottom of said housing containing therein, an exhaust port;
fingerstock gaskets attached to the edges of the moveable back wall to retain electrical contact between the moveable back wall and the housing;
a microwave generator to deliver microwave energy to the hollow cavity using a rectangular waveguide that is connected to said adapter;
C. moving the moveable back wall of the device such that the nanomaterial is in resonance with the microwave frequency inside the cavity;
D. heating the cavity until the nanomaterial is exfoliated;
E. removing the yield of exfoliated nanomaterial from the hollow cavity.
2. A method for preparing exfoliated graphene, said method comprising:
A. using a single mode microwave device, said device being a single mode microwave device, said single mode microwave device comprising:
a stainless steel housing comprised of a top, a bottom, two sidewalls, a front, and a moveable back wall, all forming a hollow cavity;
said moveable wall having a back surface, and fixedly attached to said back surface, a control rod;
contained within said housing, an exfoliation tray, said exfoliation tray supported by at least two support rods, which rods are supported at predetermined levels by the side walls, said exfoliation tray being electrically non-conducting;
said bottom, front wall, and side walls having a cooling jacket mounted on outside surfaces;
an adapter surmounting the top of the housing;
said moveable back wall having at least one gas inlet port therethrough;
said bottom of said housing containing therein, an exhaust port;
fingerstock gaskets attached to the edges of the moveable back wall to retain electrical contact between the moveable back wall and the housing;
a microwave generator to deliver microwave energy to the hollow cavity using a rectangular waveguide that is connected to said adapter;
B. while the single mode microwave device is operating, delivering intercalated graphite at a controlled rate to the exfoliation tray through the delivery chute while controlling the microwave frequencies at a frequency selected from the group consisting of: a. 915 MHz and, b. 2.45 GHz.
3. A product prepared by the method as claimed in claim 1 .
4. Exfoliated graphite produced by the method of claim 1 having a bulk density of 0.012-0.035 grams/cm 3 .
5. Exfoliated graphite produced by the method of claim 1 having BET ranges from 50-300 m 2 /gr.
6. The method of providing exfoliated graphite as claimed in claim 1 wherein the yield ranges from 0.5 to 10.0 Kg/hr.
7. The method as claimed in claim 6 wherein the yield of exfoliated graphite ranges from 1 to 4 Kg/hr.
8. The method as claimed in claim 1 , wherein, in addition, there is a gas flow rate ranging from 1 to 10 CFM through the at least one gas inlet port.
9. The method as claimed in claim 1 , wherein a residence time ranges from less than a second up to several seconds.