Patent Description:
One way to ameliorate the adverse consequences of rising carbon dioxide levels is by transforming carbon dioxide into a useful product. Various processes have been described to transform carbon dioxide to carbon nanomaterials, such as carbon nanotubes, carbon nanofibers, carbon nano-onions, carbon scaffolds, carbon platelets, and graphene, by molten carbonate electrolysis (see, e.g., citations <NUM>-<NUM> listed herein). For example, carbon nanotubes may be formed by electrolysis in molten lithium carbonate (melting point <NUM>° C) or in related mixes including alkali or alkali earth carbonates, with or without oxides, borates, phosphates, sulfates, nitrates, chlorides or other inorganic salts. During this electrolysis, the carbon nanomaterials are typically deposited on the electrolysis cathode but are bound to the cathode with an excess of electrolyte.

Some processes explored to separate the carbon from the carbonate electrolyte in the resulting product include a variety of aqueous washes or drawing the molten.

electrolyte through a mesh with a BNZ (calcium aluminum silicate) firebrick (see, e.g., citation <NUM>). The aqueous washing methodologies require cooling and heat is reversibly lost from the electrolysis cell. Both the aqueous and molten firebrick extraction consumes large amounts of material, which is detrimental to sustainability of the overall carbon dioxide removal process. For example, the aqueous separations may be accomplished by the addition of copious amounts of water and additives such as ammonia sulfate, or formic or hydrochloric acid to facilitate dissolution of the carbonate into the aqueous phase for separation from the solid carbon product. For the (molten) solid carbon / electrolyte product the firebrick acts to draw the molten carbon electrolyte by chemical reaction with the aluminate or silicate component of the firebrick. These firebrick components are consumed during the separation, such as without being bound by any theory or specific equation, the reaction of lithium carbonate consuming firebrick materials exemplified by the consumption of alumina, and silicon dioxide respectively to lithium aluminate and lithium ortho or meta silicate:.

Li<NUM>CO<NUM> + Al<NUM>O<NUM> → LiAlO<NUM> + CO<NUM> (gas evolved)     (<NUM>).

2Li<NUM>CO<NUM> + SiO<NUM> → Li<NUM>SiO<NUM> + 2CO<NUM> (gas evolved)     (2a).

Li<NUM>CO<NUM> + SiO<NUM> → Li<NUM>SiO<NUM> + CO<NUM> (gas evolved)     (2b).

Carbon nanotubes are flexible and have the highest tensile strength of any material measured to date (see, e.g., citations <NUM> and <NUM> listed herein). Recently, it has been observed that the carbon product of molten carbonate electrolysis can consist of a matrix of intermingled carbon nanotubes (see, e.g., citation <NUM> listed herein).

There is therefore a need for new and efficient processes to separate electrolyte from the solid carbon nanomaterial formed at the cathode during electrolysis, thereby providing a more sustainable (e.g., preventing heat and electrolyte waste), more cost-effective process and providing a cleaner, more useful nanomaterial.

<CIT> relates to a system and process for producing macro length carbon nanotubes. A carbonate electrolyte including transition metal powder is provided between a nickel alloy anode and a nickel alloy cathode contained in a cell. The carbonate electrolyte is heated to a molten state. An electrical current is applied to the nickel alloy anode, nickel alloy cathode, and the molten carbonate electrolyte disposed between the anode and cathode. The resulting carbon nanotube growth is collected from the cathode of the cell.

<CIT> relates to methods and apparatus for forming graphitic material from a carbon oxide feedstock in an electroplating chamber containing molten inorganic carbonate as electrolyte. Carbon dioxide flows into a reaction chamber containing one or more cathodes, one or more anodes, and a molten carbonate electrolyte. The carbon dioxide and/or carbonate reduces at the cathode to form graphitic material, which may be removed from the surface of the cathode through various mechanisms. The graphitic material is then separated out from the electrolyte.

The present invention relates to an improved process for the separation of the carbon product from a solid carbon / molten electrolyte mixed product (a carbanogel) formed, e.g., on the cathode, during a carbonate electrolysis reaction according to claim <NUM>.

A variety of carbon nanomaterials can be deposited on the cathode by control of the electrolysis conditions. During deposition, the carbon formed at the cathode exhibits a strong affinity for electrolyte, and the cathode product contains a mix of solid carbon and molten electrolyte. The deposited cathode product is a paste or gel at temperatures above the melting point of the electrolyte, or when the cathode is removed and allowed to cool to room temperature, the cathode product is a solid mixture of the carbon and congealed electrolyte. In either case, the cathode deposition contains a majority of electrolyte by mass compared to carbon. The solid carbon product / electrolyte mix is spontaneously formed on the cathode in real time during the electrolysis, and not after the solid carbon is formed. Solid product is not dislodged from the cathode to subsequently form a slurry with the electrolyte. The paste is black in color (and red hot) and is clearly distinguished from the clear molten electrolyte between the electrodes and in the electrolysis chamber. The product is a thick paste layer on the cathode which grows as the electrolysis continues. Depending on the electrolysis conditions, the percentage of electrolyte in the paste which contains the cathode product ranges from <NUM> to <NUM> percent by weight and is typically in the range from <NUM> to <NUM> percent by weight.

The present inventor has surprisingly found that the solid carbon product can be separated from a solid carbon / molten electrolyte mixed product (carbanogel) by a compression process, and that carbanogels formed on the cathode during a molten carbon carbonate electrolysis reaction can be repeatedly compressed without any observed detrimental effect on the structure and/or stability of the resulting solid carbon nanomaterial, thereby allowing for efficient separation of the desired solid carbon product.

Typically, individual carbon nanomaterials have a diameter of less than <NUM>. The present inventor has also surprisingly found that carbon nanotubes comprising a matrix of highly porous, intermingled carbon nanotubes that are greater than, for example, <NUM> height, can be repeatedly compressed to a small fraction of their initial volume without damage the structure of the carbon nanomaterials (see, e.g., citations <NUM>-<NUM> listed herein).

Typically, the desired carbon product develops as a thick paste on the cathode (it is not released into the free, circulating electrolyte) during the electrolysis reaction. The paste comprises solid carbon product and bound electrolyte. In the processes described herein, the paste containing solid carbon product is separated from the bound electrolyte. The electrolyte in the paste is stationary and is separate from the free electrolyte situated in the electrolysis chamber.

In one embodiment of any of the processes according to claim <NUM> steps (i) and (ii) are repeated one or more times, such as two, three or four times, prior to step (iii).

In certain embodiments of any of the processes described herein, the force (compression) is applied manually, pneumatically or hydraulically.

In certain embodiments of any of the processes described herein, the force (compression) is conducted at a pressure of between about <NUM> psi and about <NUM>,<NUM> psi, such as between about <NUM> psi and about <NUM>,<NUM> psi, or between at about <NUM> psi and about <NUM>,<NUM> psi.

In certain embodiments of any of the processes described herein, the electrolyte is removed through an interface with pores, such as, for example, a filter, a porous carbon felt, a graphite felt, a metal mesh, a porous or sieve ceramic, or any combination thereof.

In one embodiment, the pore size of the interface is smaller than the solid carbon matrix product size. For example, the pore size of the interface may be between about <NUM> and about <NUM>, such as between about <NUM> and about <NUM> or between about <NUM> and about <NUM>.

In one embodiment of any of the processes described herein, the process in conducted in vacuo (i.e., by applying a vacuum during the separation/extraction process). In one embodiment, the vacuum enhances removal of the electrolyte and separation of the solid carbon product.

In one embodiment of any of the processes described herein, the vacuum applied is between about <NUM> and about <NUM> atmospheres.

In another embodiment of any of the processes described herein, the vacuum applied is greater than about <NUM> atmospheres, or greater than about <NUM> atmospheres, such as between about <NUM> and about <NUM> atmospheres, or between about <NUM> and about <NUM> atmospheres.

In another embodiment of any of the processes described herein, the process is conducted at a pressure between about <NUM> and about <NUM> atmospheres, such as between about <NUM> and about <NUM> atmospheres.

In another embodiment of any of the processes described herein, the process is conducted at a pressure less than about <NUM> atmospheres, such as less than about <NUM> atmospheres.

In one embodiment of any of the processes described herein, the vacuum applied is between about <NUM> MPa and about <NUM> MPa, such as between about <NUM> MPa and about <NUM> MPa, such as about <NUM> MPa.

In another embodiment of any of the processes described herein, the process is conducted in the absence of oxygen, for example, under a blanket of gas that is free or substantially free of oxygen (an oxygen excluding gas). For example, in one embodiment, the oxygen excluding gas blankets the mixed product to protect the solid carbon product from oxidation.

In certain embodiments, the oxygen excluding gas is an inert non-oxidizing gas, such as, for example, nitrogen, carbon dioxide, argon, or a reducing gas, such as, for example, methane, ammonia, hydrogen and hydrogen sulfide, and any combination of any of the foregoing.

In another embodiment of any of the processes described herein, the process is conducted at a temperature between about <NUM> and about <NUM>, such as between about <NUM> and about <NUM>. In another embodiment of any of the processes described herein, the process is conducted at a temperature of about <NUM>, about <NUM> or about <NUM>, which correspond, respectively, to the melting points of eutectic lithium sodium potassium carbonate, lithium carbonate, and pure potassium carbonate.

In another embodiment of any of the processes described herein, the mixed product is cooled to below the point of solidification, such as below <NUM>, after its formation by electrolysis and then reheated/melted prior to the one or more compression step(s) in the processes described herein.

In other embodiments of any of the processes described herein, the solid carbon / molten electrolyte mixed product is compressed directly on the cathode in the electrolysis chamber.

In another embodiment of any of the processes described herein, the solid carbon / molten electrolyte mixed product is removed from the cathode in the electrolysis chamber, e.g. without pumping, into a separate extraction compression chamber prior to separation of the solid product.

In another embodiment of any of the processes described herein, the process does not involve a recirculation loop.

In another embodiment of any of the processes described herein, the resulting solid carbon product has an average thickness greater than <NUM>, such as greater than <NUM>, greater than <NUM> or greater than <NUM>.

In another embodiment, of any of the processes described herein, the resulting solid carbon product comprises greater than about <NUM>% carbon nano-materials, such as greater than about <NUM>%, greater than about <NUM>% or greater than about <NUM>% carbon nano-materials. In a preferred embodiment, the carbon nano-materials are carbon nanotubes, carbon nano-onions, carbon nano-platelets, carbon nano-scaffolds, graphene or any combination thereof.

In another embodiment, of any of the processes described herein, a morphological template is not present on the cathode during formation and/or separation (compression) of the solid carbon / molten electrolyte mixed product.

Disclosed is a chamber useful for conducting any of the process described herein.

Disclosed is an extraction chamber for separating electrolyte from a solid carbon / molten electrolyte mixed product formed during a carbonate electrolysis, the extraction chamber comprising.

In one embodiment, the extraction chamber is rectangular or circular.

In one embodiment, the extraction chamber is operated in the vertical mode.

In one embodiment, the extraction chamber is operated in the horizontal mode.

In one embodiment, the extraction chamber is operated in an angular mode.

In one embodiment, the extraction chamber is operated within a kiln.

In one embodiment, the extraction chamber is situated with an electrolysis chamber.

In describing the illustrative, non-limiting embodiments illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in similar manner to accomplish a similar purpose. The invention is defined in the claims.

<CIT> and <CIT>, describe the synthesis of carbon nanomaterials via electrolysis in carbonate containing molten electrolytes.

As used herein, the term "carbanogel" refers to a product analogous to an aerogel in which the air in the aerogel is replaced by molten carbonate. For example, a carbanogel contains a majority of molten carbonate with an intermingled solid matrix component. For sustainable, effective carbon dioxide splitting the electrolyte trapped in the carbanogel product of molten carbonate electrolysis needs to be separated to be available for continued use in the electrolysis.

As used herein, a gas that is "substantially free of oxygen" means a gas than contains less that about <NUM> ppm of oxygen, such as less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, less than about <NUM> ppm, or less than about <NUM> ppm, of oxygen.

<FIG> is a diagram of an exemplary extraction system <NUM> that separates electrolyte from solid carbon in the solid carbon / electrolyte product formed at the cathode during a molten carbonate electrolysis reaction. The system <NUM> includes a force applicator <NUM>, a solid carbon / electrolyte product <NUM>, a cathode <NUM>, a filter or interface with pores <NUM>, and an electrolyte <NUM> pressed out of the solid carbon / electrolyte product. Although the interface with pores <NUM> is shown on the side of the solid carbon electrolyte product <NUM> in one embodiment of <FIG>, it is to be understood that the interface with pores <NUM> alternatively can be an integral part of the cathode, if the cathode comprises a porous material, in which case the pressed electrolyte <NUM> is then pushed through and out the backside of the cathode <NUM>.

More specifically, the system <NUM> can be a chamber, such as an extraction chamber. The chamber <NUM> can be formed as a single unitary housing or container <NUM> having an interior. As shown, the container <NUM> can be elongated with a bottom, two transverse sides or walls and two longitudinal sides or walls that have a substantially rectangular cross section and define a central longitudinal axis (extending along a length of the container <NUM>), though any suitable shape and size can be utilized. The top of the container <NUM> is open, though a cover with holes can optionally be placed over at least two side sections 101a, 101c of the container <NUM>. The transverse walls extend substantially orthogonal to the longitudinal axis and the longitudinal sides extend substantially parallel to the longitudinal axis.

One or more dividing panels or separators, such as filters, membranes or interfaces are received in the interior of the container <NUM>. Here, a first interface 108a has a first side and a second side opposite the first side. The first side of the first interface 108a faces one transverse side of the container <NUM> to define a first section 101a of the interior of the container <NUM> between the first side of the first interface 108a and the transverse side of the container <NUM>. A second interface 108b has a first side and a second side opposite the first side. The first side of the second interface 108b faces the second side of the first interface 108a to define a second section 101b of the interior of the container <NUM> between the first side of the second interface 108b and the second side of the first interface 108a. The second side of the second interface 108b faces the other transverse side of the container <NUM> to define a third section 101c of the interior of the container <NUM> between the second side of the second interface 108b and the other transverse side of the container <NUM>. The center section 101b forms an extraction chamber or container, and the two side sections 101a, 101c each form a collection chamber or container.

As shown, each section 101a, 101b, 101c can have a substantially square cross section, though any suitable shape and size can be utilized. The interfaces <NUM> are relatively thin and can form a plate (or two plates with filter material therebetween) with two opposite sides that are relatively flat and planar and can have multiple holes that allow material to pass from the center section 101b to one of the two outer sections 101a, 101c through the interface <NUM>. The interfaces <NUM> extend substantially transverse to the longitudinal axis of the container across the entire width and height, and parallel to the transverse sides of the container <NUM>, so that material in the center section 101b cannot pass to the outer sections 101a, 101c, except through one of the two interfaces 108a, 108b. The interfaces 108a, 108b can be any suitable device that separates material. Each section 101a, 101b, 101c has a respective interior space of the interior of the container <NUM>.

The middle or center section 101b of the container <NUM> receives the force applicator <NUM>, the cathode <NUM>, and the material <NUM>, such as a carbon / electrolyte product. The force applicator <NUM> is sized and shaped to the center section 101b, here shown as a compressor formed by a flat square or rectangular plate that extends the entire space between the two interfaces 108a, 108b and the two longitudinal sides of the container <NUM>. The cathode <NUM> can also be a flat square or rectangular plate that extends the entire space between the two interfaces 108a, 108b and the two longitudinal sides of the container <NUM>. The cathode <NUM> can be situated, for example at the bottom of the interior space of the center section 101b.

As illustrated by the large arrows in <FIG>, the cathode <NUM> and material <NUM> is placed in the center section 101b. The compressor <NUM> is located above the center section 101b and is forced downward into the center section 101b, such as by pneumatic operation. As the compressor <NUM> moves downward, it forces product <NUM> to separate. The first interface 108a can have a first filter mechanism (e.g., first porous material) that filters a first product (i.e., gas, liquid or material), and the second interface 108b can have a second filter mechanism (e.g., second porous material) that filters a second product (e.g., gas, liquid or material) which is the same or different from the first product. Here, both the first and second interfaces 108a, 108b filter carbon so that only an electrolyte <NUM> can pass through the interfaces 108a, 108b into the first and second sections 101a, 101c, respectively. As noted, the compressor <NUM> is sized and shaped to match the size and shape of the center section 101b so that material <NUM> doesn't escape around the sides of the compressor <NUM> as it compresses downward, but instead the material <NUM> presses through the interfaces 108a, 108b.

In a further embodiment, an oxygen excluding gas (e.g., a gas that is free or substantially free of oxygen) <NUM> may optionally be used to blanket (e.g., completely cover) the system <NUM>, for example, to prevent oxidation of the solid carbon during electrolyte separation from the solid carbon / electrolyte product <NUM>. In this embodiment, the system <NUM> can include a main housing that encloses the compressor <NUM> and the container <NUM>, such as shown for example in <FIG> (see. , e.g., main housing <NUM>). The gas <NUM> can be pumped into the main housing around the container <NUM> to contact the product <NUM> and/or electrolyte <NUM> in any of the sections 101a, 101b, 101c.

The chamber <NUM> of <FIG> has sections 101a, 101b, 101c arranged in a side-by-side relationship, and with electrolyte being filtered into the two outer sections 101a, 101c. However, the sections <NUM> can be arranged in any suitable manner, and only a single section (or compartment) is needed to hold the product <NUM> and another section (or compartment or container) is needed to receive the filtered electrolyte <NUM>.

<FIG> is a diagram of an exemplary system <NUM> that separates electrolyte from solid carbon in a solid carbon / electrolyte product in an extraction chamber. Using similar components as labeled in <FIG>, the solid carbon / electrolyte product <NUM> is first removed from the cathode of the electrolysis chamber (not shown) and placed as a gel (hot) or initially solid (frozen gel, then reheated to a molten gel) into the electrolyte pressing extraction reservoir or chamber <NUM>. As a further embodiment, an optional vacuum <NUM> can be applied to the pressing chamber to provide a pull of electrolyte through the interface with pores <NUM>.

More specifically, the extraction chamber <NUM> has a housing <NUM> with four sides or walls <NUM> forming a container with an interior space and a square or rectangular cross section. The housing <NUM> has an open top and an open bottom. The interface <NUM> is provided at the bottom of the housing <NUM> and closes the open bottom of the housing <NUM>. Product <NUM> is placed in the interior of the housing <NUM>. The lower container or extraction chamber <NUM> is located beneath the housing <NUM> and interface <NUM>. The compressor <NUM> is sized and shaped to match the size and shape of the interior of the housing <NUM>, and pushes downward on the product <NUM>, forcing electrolyte through the interface <NUM> and into the extraction reservoir, such as a square or rectangular chamber <NUM>. In addition, an optional vacuum <NUM> can be provided with or instead of the compressor <NUM> to further facilitate electrolyte passing through the interface <NUM>; though it is also noted that some electrolyte may pass through the interface <NUM> by force of gravity without the use of a compressor <NUM> and/or vacuum <NUM>. The vacuum <NUM> can also operate as a drain to collect separated electrolyte, or a separate drain (e.g., a hose or line) can be provided. The interface <NUM> prevents carbon from passing, so only electrolyte enters the extraction chamber <NUM>. Though not shown, a cathode <NUM> can also be located in the housing <NUM>.

<FIG> show other embodiments. The system can have any suitable size or shape and be configured vertically, horizontally or at an angle. Turning to <FIG>, <FIG>, a horizontal configuration of the extractor system <NUM> is shown. The system <NUM> has an extraction container or chamber <NUM>, an electrolyte collection chamber <NUM>, and a filter <NUM> between the container <NUM> and the collection chamber <NUM>. The extraction chamber <NUM> has a top, bottom and at least two sides or walls, here shown as longitudinal walls extending along the length of the chamber <NUM>. One side can be open to receive the plate of the compressor <NUM>. In the embodiment shown, the chamber <NUM> is elongated and the compressor <NUM> is received at an open proximal transverse end of the chamber <NUM>. The compressor <NUM> extends along the longitudinal axis of the chamber <NUM> from a proximal end of the chamber <NUM>. Raw product <NUM> can enter through an opening in a side wall or the top.

The interface or filter <NUM> is located at the open distal transverse end of the extraction chamber <NUM>, and the collection chamber <NUM> is connected to the distal transverse end of the extraction chamber <NUM>. A heat zone <NUM> can be provided at a portion of the container <NUM>, such as at a proximal portion and immediately adjacent to the interface or filter <NUM>. The compressor <NUM> pushes inward from the proximal end to the distal end so that heated product passes through the filter <NUM> and into the electrolyte collection reservoir or chamber <NUM>. The vacuum <NUM> can be connected to the electrolyte collection reservoir <NUM> to facilitate electrolyte passing through the filter <NUM> into the reservoir <NUM>. The vacuum <NUM> can be coupled on a side of the reservoir <NUM> opposite the filter <NUM>. The vacuum acts to both pull electrolyte from the carbon nanogel and to protect it from oxidations.

As shown in <FIG>, <FIG>, the compressor <NUM> and container <NUM> can be circular, and <FIG>, <FIG> show that the compressor <NUM> can engage or attach to a main housing <NUM>. Turning to <FIG>, the container <NUM> can have a support shelf or ledge <NUM> extend inwardly from one or more of the side walls <NUM>. A steel support plate <NUM> can be placed on the ledge <NUM>. The support plate <NUM> has a plurality of openings, such as forming a honeycomb pattern. The plate <NUM> can support an interface <NUM> that is placed on top of the plate <NUM>, such as a filtering membrane, mesh screen, felt material or the like.

<FIG> shows a chamber <NUM> for use with a molten paste material from an electrode that contains carbon product and electrolyte. The paste is on top of a mesh screen <NUM> on a porous support <NUM>. The compressor pushes down on the paste and electrolyte passes through the mesh screen <NUM> into a separate container or the bottom of the chamber. The chamber <NUM> can be gas tight, and oxygen-free gas (e.g., Ar, N<NUM>, CO<NUM>) or a vacuum can be applied inside the container around the paste material.

<FIG> shows that instead of an internal support ledge <NUM>, a grating support can be provided to support the porous mesh support <NUM>. In addition, a mesh screen <NUM> can be provided on top of the mesh support <NUM>, and the sample is placed on top of the mesh screen <NUM>. A heater can be provided to heat the system, for example the system can be inside a kiln or coupled to a kiln.

<FIG> show that the compressor <NUM> can be formed as a plate and a threaded bar. The threaded bar can extend through a threaded opening in the top plate of the main housing <NUM> and the threaded bar can be rotated in the opening to extend the bar and plate further into the container <NUM>. <FIG> shows another embodiment in which the compressor <NUM> has a press plate and a scissor-type hydraulic jack mounted to the press plate. The jack presses against the top plate of the main housing <NUM>, and a threaded bar in the jack can be rotated to extend the jack and move the press bar or rod and press plate further into the container <NUM>. <FIG> also shows a molten paste product in the container <NUM> from the electrode. The molten paste product contains carbon product and electrolyte. The press plate forces electrolyte out of the paste product, through a mesh screen <NUM> positioned on a porous support <NUM>, into a collection reservoir at the bottom of the container <NUM>. In addition, a divider <NUM> is provided in the main housing <NUM>. The divider <NUM> is a plate that extends across the main housing <NUM> and around the compressor <NUM>, such as the rod of the compressor <NUM>. The divider <NUM> forms a gas-tight seal and encloses the container <NUM>. An oxygen-free gas can be introduced into the sealed enclosure. The gas comes into contact with the product when the paste product from the electrode is introduced prior to placement of the press plate, or during pressing through any leaks in the seal between the press plate and the paste product from the electrode.

<FIG> show a collection chamber <NUM> positioned with respect to an electrolysis chamber <NUM> and operating to remove product. In <FIG>, the electrolysis chamber <NUM> is shown with a cathode electrode positioned between two anode electrodes, surrounded by electrolyte. The collection chamber <NUM> is integrally formed with our coupled to the electrolysis chamber <NUM>. The collection chamber <NUM> is above the level of the electrolyte in the electrolysis chamber <NUM>. A transport apparatus is coupled to the cathode, such as by a wire, bar or solid rod, and configured to move the cathode from the electrolysis chamber <NUM> to the collection chamber <NUM>. Here, the transport apparatus includes a conveyor device that is located above the electrolysis chamber <NUM> and the collection chamber <NUM>. When carbon is attached to the cathode, one or more transport motors are operated to vertically raise the cathode out of the electrolysis chamber <NUM>, <FIG>, and then move the cathode horizontally over the collection chamber <NUM>, <FIG>. The compressor <NUM> is withdrawn from the collection chamber <NUM>, and the cathode is lowered by the transport apparatus into an opening in the collection chamber <NUM>.

Raw product is then released from the cathode into the collection chamber. For example, the collection chamber <NUM> can have one or more scraper blades <NUM> positioned in the opening of the collection chamber <NUM>. A scraper channel or opening is formed between the one or more blades <NUM>. The cathode is lowered into the scraper channel between the scraper blades <NUM>, which forces the raw product off of the cathode and into the collection chamber <NUM>. The compressor then extends into the collection chamber and compresses the raw product. Electrolyte from the product passes through the interface of the collection chamber and returns directly into the electrolysis chamber, while carbon remains in the collection chamber. The extracted carbon product is removed together with the collection chamber. It is further noted that any of the systems of <FIG>, <FIG> can be utilized for the collection chamber <NUM> of <FIG>. in addition, while the collection chamber <NUM> is shown at an angle with respect to the electrolysis chamber <NUM>, the collection chamber <NUM> can be positioned vertically or horizontally with respect to the electrolysis chamber <NUM>.

<FIG> shows a product extractor or collection chamber <NUM> and vacuum system <NUM> in a vertical arrangement. A vacuum system <NUM> can optionally be attached to the collection chamber <NUM>. The collection chamber <NUM> can be a container with walls, here shown as a cube with rectangular or square sides and an open bottom. The vacuum system <NUM> includes an extraction chamber <NUM>, gasket or sealant <NUM>, and vacuum line <NUM>. The extraction chamber <NUM> can be a container or reservoir that retains electrolyte that is drawn out of the extractor <NUM>. The extraction chamber <NUM> is shown as a cube with square or rectangular sides and an open top. The seal <NUM> is provided at the top edge of the extraction chamber <NUM> and bottom edge of the collection chamber <NUM> to form an air-tight seal between the collection chamber <NUM> and the extraction chamber <NUM>. The vacuum line <NUM> is coupled to the extraction chamber <NUM> and in gas communication therewith. Once the seal is formed, the vacuum line <NUM> can create a vacuum or negative pressure in the extraction chamber <NUM>, that in turn pulls electrolyte out of the product contained in the collection chamber <NUM>. The extraction chamber <NUM> can then be removed, the electrolyte emptied, and the extraction chamber replaced. The vacuum system <NUM> shown in <FIG> can be utilized with any of the systems <NUM>, <NUM>, <NUM> of <FIG>. The drain tube or pipe <NUM> drains accumulation of excess electrolyte that has been separated from the paste product from the electrode.

<FIG>, <FIG> show the extraction chamber <NUM> having a vertical configuration. As noted above with respect to <FIG>, the extraction chamber <NUM> can be enclosed in a main housing <NUM> that forms a complete enclosure around the extraction chamber <NUM>. <FIG>, <FIG> show that the main housing <NUM> can be a frame <NUM> that extends over the extraction chamber <NUM>. The frame <NUM> has two elongated vertical support members and a horizontal cross-member connecting the two vertical members. The vertical members can be fixed to the ground or to a horizontal base or platform <NUM>. The extraction chamber <NUM> can be positioned on the base <NUM>. As further shown in <FIG>, the extraction chamber <NUM> can be located within a kiln to control the temperature in the extraction chamber <NUM>. <FIG>, <FIG> show the compressor <NUM> having a threaded rod attached to the frame cross-member and a press plate, and <FIG> shows the compressor <NUM> having a scissor-type jack mechanism coupled to the cross-member of the frame <NUM>. <FIG> also show round electrolyte from a product extraction unit.

<FIG> show another embodiment of the invention. Here, the extraction system <NUM> is shown. The system <NUM> includes an electrolysis and extraction chamber <NUM>, transport assembly <NUM>, housing <NUM>, and a compressor and collection assembly <NUM>. The electrolysis and extraction chamber <NUM> is a container having one or more vertical side walls <NUM>, a bottom, and a top that is at least partially open. The container receives an anode electrode, a cathode electrode, and a liquid electrolyte that surrounds the anode and cathode. An opening <NUM> is provided along the at least one wall <NUM>, at a position above the level of electrolyte in the chamber <NUM>.

The housing <NUM> at least partly encloses the electrolysis chamber <NUM>. Here, the housing <NUM> can be a frame having an elongated support frame member extending horizontally over the electrolysis chamber <NUM>. The support frame member can connect with other frame features, such as vertical support beams that are connected to a base, as in <FIG>, <FIG>.

The transport assembly <NUM> is used to raise the cathode out of the electrolyte to remove the raw product, and then lower the cathode back into the electrolyte after the raw product is removed. That can be accomplished by any suitable mechanism(s), such as for example a motor, a gear or wheel, and a line. The motor and rotational wheel can be connected to the horizontal support frame <NUM>. The line is coupled with the wheel and the cathode. The motor is operated to rotate the wheel, which in turn raises and lowers the cathode. The anode can also be separately connected to the transport assembly <NUM> by a separate line and wheel and have a separate or shared motor.

The compressor and collection assembly <NUM> has an extension rod <NUM>, press plate <NUM>, press wall <NUM>, and collection device <NUM>. The extraction assembly <NUM> is received in an opening <NUM> in the one or more side walls of the electrolysis chamber <NUM>, and the entirety of the extraction assembly <NUM> is positioned above the electrolyte in the electrolysis chamber <NUM>. The press plate <NUM> is positioned vertically inside the electrolysis chamber <NUM>, and the rod <NUM> extends horizontally through the wall opening <NUM> to the exterior of the electrolysis chamber <NUM>. The press wall <NUM> is a vertical plate or wall with a proximal end that is coupled to and extends downward from the horizontal support frame member <NUM>. The wall <NUM> has a distal end that extends downward into the electrolysis chamber <NUM>. In the embodiment shown, the distal end of the wall <NUM> stops above the electrolyte, so that the wall does not touch the electrolyte at the bottom portion of the electrolysis chamber <NUM>. The press wall <NUM> can have other support members, such as horizontal beams that connect with the frame at the bottom end of the wall <NUM>. The press wall <NUM> has two sides each with a respective opposite outwardly-facing surface. A first wall surface faces toward the compressor <NUM> and a second wall surface faces away from the compressor <NUM>. The first wall surface is aligned with and faces an inward facing surface of the press plate <NUM>. The rod <NUM> moves the press plate <NUM> horizontally forward and inward into the container <NUM> toward the press wall <NUM>. Of course, other suitable means can be provided to move the press plate forward, such as a scissor-like jack positioned on the wall of the container <NUM>.

The collection device <NUM> is situated at the bottom end of the press plate <NUM>. As shown, the collection device <NUM> can be a shelf that extends horizontally outward from the bottommost edge of the press plate <NUM>, substantially orthogonal to the inwardly facing surface of the press plate <NUM>. The collection device <NUM> is sized to collect carbon (graphene) that is removed from the cathode. The collection device <NUM> can be received in a channel formed in the bottom end of the press plate <NUM>, or attached to the bottom edge of the press plate <NUM>. However, other suitable collection means can be provided, for example the collection device <NUM> need not be connected to the press plate <NUM>, but instead can be connected to the at least one chamber wall <NUM> of the electrolysis chamber <NUM>, and extend outward from the chamber wall <NUM> and inwardly toward the press wall <NUM>.

Starting at <FIG>, operation of the extraction system <NUM> begins with the anode and electrode lowered by the transport mechanism <NUM> into the electrolyte inside the electrolysis and extraction chamber <NUM>. The compression rod <NUM> is fully receded so that the press plate <NUM> is withdrawn and can be against the one or more walls <NUM>. At that point, electrolysis begins. In <FIG>, gas is emitted from the reaction at the anode and product begins to accumulate on the cathode. In <FIG>, the reaction continues, and more and more paste product is formed on the cathode.

At <FIG>, the cathode is saturated with paste product. Accordingly, the motor of the transport assembly <NUM> is operated, and the cathode is lifted out of the electrolyte, <FIG>. At this point, the cathode and paste product are substantially aligned with, and parallel to, the first surface of the press wall <NUM> facing the press plate <NUM>. The press wall <NUM> is positioned between the cathode and the anode. Accordingly, the paste product mostly accumulates on the side of the cathode that faces the press wall <NUM>. Once the cathode is full raised, the press rod <NUM> is operated, moving the press plate <NUM> inwardly toward the press wall <NUM>, as shown by the arrow. In <FIG>, the press plate <NUM> contacts the cathode, which in turn applies a compression force to the paste product, forcing the paste product down along the press wall <NUM> between the press wall <NUM> and the cathode.

The expelled product reaches the collection device <NUM>. The collection device <NUM> can be a plate with openings or pores and can have a mesh screen or other filter mechanism situated on the porous plate. The distal end of the collection device <NUM> can contact the press wall <NUM> and / or extend under the press wall <NUM>. The paste product expelled by the compression enters the collection device <NUM>, which collects clean product (such as carbon or graphene), and allows clean electrolyte to pass through and return to the bottom of the electrolysis chamber <NUM>. When pressed, electrolyte is pressed and separated from the paste through the supported screen. At <FIG>, the clean electrolyte has returned to the electrolysis chamber <NUM>, and the clean product is in the collection device <NUM>. At <FIG>, the press rod <NUM> is operated to withdraw the press plate <NUM> outward away from the press wall <NUM> and return to its initial position adjacent the chamber wall <NUM>. The transport device then lowers the cathode back into the electrolyte for further electrolysis, and the clean product is removed from the collection device <NUM>.

It is further noted that when the paste product is removed from the electrolyte, <FIG>, it will begin to cool and might solidify. A heat can be applied during the compression, <FIG>, to facilitate separation of the carbon and electrolyte. In addition, a scraper can be utilized to fully remove product from the press plate surface and the surface of the cathode, <FIG>. And as shown, the solid carbon / molten electrolyte mixed product is compressed directly on the cathode in the electrolysis chamber. In addition, it is also noted that some product may be present on both sides of the cathode, in which case product may also be directly compressed between the press plate and the cathode, and separated and collected. The invention is useful for a paste product that forms at the cathode during a carbonate electrolysis reaction, and comprises a solid carbon nanomaterial product bound with some of the molten liquid electrolyte in which the reaction is performed (i.e., the paste is a solid carbon plus molten liquid electrolyte). When the paste is compressed, the bound molten electrolyte is separated from the solid desired carbon nanomaterial product. The electrolyte is not diluted, destroyed or otherwise rendered unusable as a result of the separation process. Accordingly, the electrolyte can be recycled (e.g., returned to the electrolysis chamber) or discarded, and the solid carbon product remains. These electrolysis reactions are performed in molten electrolytes at <NUM> + degrees C. The compression can be performed in the electrolysis chamber or outside the electrolysis chamber, and can be done while the paste is on the cathode or after it is removed from the cathode. If the compression/separation process is performed in a separate extraction chamber (i.e., not in the electrolysis chamber in which the reaction was carried out) the product can be cooled below the melting point of the electrolyte to form a solid carbon / solid electrolyte product that can be removed from the cathode, placed in the separate extraction chamber, then heated to re-melt the electrolyte so the liquid electrolyte can be removed from the desired solid carbon product in that separate chamber.

And, while the invention is illustrated for use with a paste product to separate electrolyte and carbon product, the system can be utilized for separating other suitable materials. In addition, the system utilized to apply the force to a product can be any suitable configuration, and the systems shown in the figures are only for illustrative purposes and do not limit the invention. For example, the figures illustrate that any number of containers or chambers can be utilized. In <FIG>, a single chamber can be utilized for electrolysis, compression and separation. In <FIG>, a chamber is provided for compression and separation that is separate from the chamber where electrolysis occurs. In <FIG>, three chambers can be utilized for compression and separation, and in <FIG> two chambers can be utilized. The chambers can be arranged horizontally or vertically, and can have any suitable shape, such as for example rectangular, square and circular. The force can be imparted by any suitable apparatus, such as a press plate and rod or hydraulic mechanism, pneumatically or manually. A compression force is applied, removed, and then applied again (and repeated), or a compression force is applied, followed by a difference force, such as torque. Still further, the compression can be applied while the product is on the cathode, or after the product is removed from the cathode.

It is noted that high temperature presses might be thought to expose and oxidize (combust) the carbon product. However, the inventors recognized that the electrolyte itself protects the product from combustion during the pressing process. In addition, nanomaterials are too small to be separated by presses since the presses intrinsically depend on greater than micron or greater than millimeter filters, and therefore the nanomaterials are too small to be separated by the filters. However, the inventors recognized that the agglomeration and aggregation of the carbon nanotube product during electrolysis allows for filtering of nanomaterials with larger filters, such as micron and millimeter sized filters. That is, the individual carbon nanomaterial product has nanoscopic dimensions, but the carbon agglomerates, and the agglomerated product has micron and millimeter dimensions.

In another embodiment of any of the processes described herein, the electrolyte is removed through an interface with pores <NUM>. In one embodiment, the interface with pores <NUM> comprises a foam, such as, for example, a porous carbon felt, a graphite felt, a metal mesh, a porous or sieve ceramic, or any combination thereof. In one embodiment, the pore size of the interface with pores is between about <NUM> and about <NUM>, such as between about <NUM> and about <NUM> or between about <NUM> and about <NUM>. In a further embodiment, any of the processes described herein further comprises applying a vacuum, such as vacuum <NUM>, during the separation/extraction process, for example, to enhance removal of the electrolyte and separation of the solid carbon product.

In another embodiment, an oxygen excluding gas (e.g., a gas that is free or substantially free of oxygen), such as, for example, nitrogen, carbon dioxide, argon, or a reducing gas, such as, for example, methane, ammonia, hydrogen and hydrogen sulfide, and any combination of any of the foregoing, is used to blanket the carbon product during the separation, for example, to minimize any loss by oxidation of the carbon product during exposure to oxygen at elevated temperatures.

In other embodiments of any of the processes described herein, the molten electrolyte cathode product mix is compressed directly on the cathode in the electrolysis chamber.

In another embodiment of any of the processes described herein, the electrolyte cathode product mix is removed from the cathode in the electrolysis chamber, e.g. without pumping, into a separate extraction compression chamber prior to separation of the solid product.

In further embodiments of any of the processes described herein, the mixed product is separated without cooling from the molten stage, for example, for reinclusion in the electrolysis without loss of heat. In further embodiments of any of the processes described herein, the mixed product is cooled, and the cooled congealed product is reheated above the electrolyte melting point prior to compression (separation). In either case, the molten mix may be compressed through the application of pressure and pressed through the interface <NUM> with pores smaller than the carbon matrix size. The macroscopic (greater than micron) pore size is larger than the nm dimensions of nanomaterials in the carbon product, but smaller than the carbon matrix size. Product compression draws electrolyte out of the product while solid carbon is restrained by the pores and retained in the product.

A solid carbon / molten electrolyte mixed product (carbonogel), removed from the cathode of a brass cathode and formed on the cathode by electrolysis in a molten alkali carbonate electrolyte at <NUM> at an applied current density of <NUM> A cm-<NUM> between an Inconel anode and the brass cathode for <NUM> hours, was separated into carbon nanotubes and clear electrolyte using the product extractor <NUM> shown in <FIG>. Carbon felt was placed on a <NUM>/<NUM>" honeycomb structured steel plate that acts as a support during the subsequent pressing stage. On top of the carbon felt, respective layers of <NUM> x <NUM>, <NUM> x <NUM> and finally <NUM> x <NUM> Monel mesh were placed. Carbon dioxide flowed into the top of the extractor to prevent oxidation of the carbonogel and subsequent separated carbon product. <NUM> of carbonogel product grown by electrolysis in a pure lithium carbonate electrolyte, and previously analyzed as containing <NUM>% carbon nanomaterials and <NUM>% electrolyte (comprising of <NUM> of carbon and <NUM> of electrolyte) was removed from the cathode and placed at <NUM>° C on top of the uppermost (<NUM> mesh) Monel layer. Above the carbonogel was placed subsequent layers of <NUM> x <NUM> Inconel mesh and <NUM> x <NUM> Monel mesh. The press plate shown on the left side of <FIG> was placed on top of the uppermost mesh layer and a pressure of <NUM> tonnes was applied for <NUM> hours. A vacuum <NUM> of <NUM> MPa was applied through the metal tube shown on the left side of <FIG>. The vacuum was applied in the electrolyte collection chamber at the bottom of the extractor. Finally, the extractor was cooled, the press plate removed, the carbon product retained, and the clear extracted electrolyte removed and weighed. <NUM> % of the electrolyte in the carbonogel was removed and recovered by this procedure.

A solid carbon / molten electrolyte mixed product (carbonogel), removed from the cathode of a brass cathode and formed on the cathode by electrolysis in a molten alkali carbonate electrolyte at <NUM> at an applied current density of <NUM> A cm-<NUM> between an Inconel anode and the brass cathode for <NUM> hours, was separated into carbon nanotubes and clear electrolyte using the product extractor shown on the middle and right sides of <FIG>. No carbon felt was used. Use of a larger press minimized leakage at the press plate edges, and decreased the press time, both improving extraction efficiency even in the absence of a vacuum draw.

On the honeycomb structured steel support plate was placed respective layers of (<NUM>) <NUM> x <NUM> Inconel mesh, (<NUM> and <NUM>) two layers of <NUM> x <NUM> Monel mesh, and finally (<NUM>) another <NUM> x <NUM> Inconel mesh. Carbon dioxide flowed into the top of the extractor to prevent oxidation of the carbonogel and subsequent separated carbon product. <NUM> of carbonogel product grown by electrolysis in a <NUM> wt. % sodium carbonate and <NUM> wt. % lithium carbonate electrolyte, and previously analyzed as containing <NUM>% carbon nanomaterials and <NUM>% electrolyte (comprising of <NUM> of carbon and <NUM> of electrolyte), was removed from the cathode and placed at <NUM>° C on top of the uppermost mesh layer. Above the carbonogel was placed subsequent layers of <NUM> x <NUM> Inconel mesh and <NUM> x <NUM> Monel mesh. The press plate was placed on top of the uppermost mesh layer and a pressure of <NUM> tons was applied for <NUM> hours. A vacuum of <NUM> MPa was applied through the metal tube shown on the left side of <FIG>. The vacuum draw was applied in the electrolyte collection chamber at the bottom of the extractor. Finally, the extractor was cooled, the press plate removed, the carbon product retained and the clear extracted electrolyte removed and weighed. <NUM> % of the electrolyte in the carbonogel was removed and recovered by this procedure.

It is further noted that the description and claims use several geometric or relational terms, such as planar, elongated, circular, parallel, perpendicular, orthogonal, transverse, longitudinal, and flat. In addition, the description and claims use several directional or positioning terms and the like, such as horizontal, vertical, top, bottom, left, right, up, down, distal, and proximal. Those terms are merely for convenience to facilitate the description based on the embodiments shown in the figures. Those terms are not intended to limit the invention. Thus, it should be recognized that the invention can be described in other ways without those geometric, relational, directional or positioning terms. In addition, the geometric or relational terms may not be exact. For instance, walls may not be exactly perpendicular or parallel to one another but still be considered to be substantially perpendicular or parallel because of, for example, roughness of surfaces, tolerances allowed in manufacturing, etc. And, other suitable geometries and relationships can be provided without departing from the scope of the invention.

(<NUM>) <NPL>); (<NUM>)<NPL>); (<NUM>) <NPL>); (<NUM>) <NPL>); (<NUM>) <NPL>); (<NUM>) <NPL>); (<NUM>) <NPL>); (<NUM>) <NPL>); (<NUM>) <NPL>); (<NUM>) <NPL>); (<NUM>) <NPL>).

Claim 1:
A process for preparing a solid carbon product by separating an electrolyte from a solid carbon/molten electrolyte mixed product removed from a cathode of a carbonate electrolysis, the process comprising steps of:
(i) applying a force to compress the solid carbon/molten electrolyte mixed product to remove the electrolyte;
(ii) removing the force; and
(iii) isolating the solid carbon product.