HK1219090B - Process for pure carbon production, compositions, and methods thereof - Google Patents

Description

Process, composition and method for pure carbon production

Cross Reference to Related Applications

This application claims priority from U.S. provisional application No. 61/798,198, filed on 3/15/2013, which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure provides methods of oxidizing carbide anions or negative ions from salt-like carbides at a temperature of about 150 ℃ to about 750 ℃. In another aspect, the present disclosure provides a reaction with an intermediate transition metal carbide. In yet another aspect, the present disclosure provides a reaction system in which salt-like carbide anions and intermediate carbide anions are oxidized to produce pure carbon of various allotropes.

Background

Carbides are chemical compounds containing carbon and elements of lower electronegativity or weaker electron-withdrawing ability. Almost all elements react with the element carbon to produce carbides. They are further classified into 4 groups: salt-like carbides, covalent carbides, interstitial carbides, and intermediate transition metal carbides. The salt-like carbides react with water and dilute acid to produce ions and hydrocarbon gases. The intermediate transition metal carbides also react with dilute acid and sometimes water to produce metal cations, hydrocarbons and sometimes hydrogen.

The salt-like carbides are further broken down into methanides, acetylides and sesquicarbides. The methanate reacts with water to produce methane. Methane is one carbon atom bonded to four hydrogen atoms in an sp3 hybridization. Two examples of methanides are aluminum carbide (Al)₄C₃) And beryllium carbide (Be)₂C) In that respect The acetylide being the acetylide anion C₂ ^-2Salts and also have a triple bond between two carbon atoms. The triple bond carbon has sp1 hybridization and two examples of acetylides are sodium carbide (Na)₂C₂) And calcium carbide (CaC)₂). The sesquicarbides containing a polyatomic anion C₃ ^-4And contains a carbon atom with sp1 hybridization. Two examples of sesquicarbides are magnesium (Mg)₂C₃) And lithium (Li)₄C₃)。

U.S. patent No. 1,319,148 defines an oxidation reaction that produces potassium metal by reacting potassium cations (positive ions) with acetylide anions from calcium carbide. The reaction medium is potassium fluoride alkane (mp 876 ℃). This is shown in the reaction in scheme (1) below.

Scheme I

CaC₂+2KF→CaF₂+2K+2C_(graphite)Reaction T > 800 ℃ (1)

Other products of this reaction are calcium fluoride and graphite. Graphite is the thermodynamically most stable form of elemental carbon, and therefore is a favorable product at high temperatures. This reaction (reduction of potassium ions) occurs above 800 ℃, which will be considered as a high temperature, since 600 ℃ is red hot.

Alkali metals can be produced from the electrolysis of molten salts. However, U.S. patent No. 1,319,148 indicates the use of an oxidation reaction to prepare alkali metals. In addition, Concepts and Models of organic Chemistry; the company douglas b.mcdaniel d.1965xerox describes how they purify alkali metals before electrolysis with molten salts.

To produce the alkali metal, the temperature is above the melting point of KF (mp ═ 858 ℃), which is high enough to vaporize K. (bp ═ 744 ℃). The product is indicated as CaF₂Thermodynamically most stable form of K DEG and carbon (graphite, C)_(graphite))。

Disclosure of Invention

The present disclosure provides methods of oxidizing carbide anions and/or negative ions from carbides by oxidizing the carbide anions at a reaction temperature of about 150 ℃ to about 750 ℃, wherein the reaction produces an allotrope of carbon in an sp1 and/or sp3 configuration.

In another aspect, the present disclosure provides methods of producing pure elemental allotropes of carbon by oxidizing salt-like carbide anions and/or intermediate carbide anions at a reaction temperature of about 150 ℃ to about 750 ℃.

In yet another aspect, the present disclosure provides a method of producing diamond by reacting a carbide with a molten metal halide salt at a reaction temperature of about 150 ℃ to about 750 ℃.

The present disclosure also provides methods of controlling carbon allotropes by varying the reduction potential of cations and/or varying the temperature of the melt to control the reduction potential of low melting halide salt reactants.

In one aspect, the carbide anions are salt-like or intermediate carbide anions. In another aspect, the salt-like carbide anion is selected from the group consisting of methanides, acetylides, and sesquicarbides. In another aspect, the salt-like carbide anion is calcium carbide.

In one aspect, the methods described herein produce allotropes of carbon in the sp1 configuration. In yet another aspect, the methods described herein produce allotropes of carbon in the sp3 configuration.

The present disclosure also provides for the processes described herein, wherein the reaction temperature is less than about 150 ℃, less than about 200 ℃, less than about 250 ℃, less than about 300 ℃, less than about 400 ℃, less than about 500 ℃, less than about 600 ℃, less than about 700 ℃, or less than about 800 ℃.

In yet another aspect, the present disclosure provides a method of oxidizing carbide anions or negative ions from a salt-like carbide at a temperature in the range of: about 150 ℃ to about 200 ℃, about 150 ℃ to about 250 ℃, about 200 ℃ to about 300 ℃, about 200 ℃ to about 350 ℃, about 200 ℃ to about 400 ℃, about 250 ℃ to about 400 ℃, about 200 ℃ to about 500 ℃, about 250 ℃ to about 500 ℃, about 300 ℃ to about 600 ℃, about 400 ℃ to about 600 ℃, about 500 ℃ to about 700 ℃, about 200 ℃ to about 700 ℃, about 250 ℃ to about 750 ℃, about 150 ℃ to less than 800 ℃, about 250 ℃ to less than 800 ℃, about 300 ℃ to less than 800 ℃, about 400 ℃ to less than 800 ℃, about 500 ℃ to less than 800 ℃, or about 600 ℃ to less than 800 ℃.

Drawings

Fig. 1 is a graph providing enthalpies of formation for various allotropes of carbon.

Fig. 2 provides representative block flow diagrams for the formation of various allotropes of carbon, including (1) reaction preparation, (2) chemical reactions, (3) carbon separation, and (4) diamond purification aspects.

Detailed Description

In one aspect, the present disclosure provides a diamond production method comprising, consisting of, or consisting essentially of (1) a reaction preparation, (2) a chemical reaction, (3) a separation, and (4) a purification method described herein. A representative process is depicted in fig. 2.

In one aspect, the process begins by preparing the reactor (1) in a controlled atmosphere free of moisture and oxygen. In one aspect, the chemical reaction (2) follows the reaction preparation section. In another aspect, the separation and purification aspect follows the chemical reaction (2). In yet another aspect, the separation and purification aspects follow the chemical reaction (2) in that the separation (3) is defined by a material that removes elemental carbon that is not a product from the chemical reaction (2), and the purification (4) is a material that removes any undesirable elemental carbon produced by the chemical reaction and any other trace materials remaining from the separation (3).

The (1) reaction preparation aspect of the process involves preparing reactants to control variables and reaction conditions; (2) chemical reaction of the respective reactants in the manner described herein; (3) the separation aspect includes the initial removal of unreacted carbides and metal salts, metal salts produced by the reaction, elemental metals produced by the reaction, and any/or metal oxides produced; and (4) the aspect of purification is the aspect of producing a product (e.g., diamond). In one embodiment, the (4) purification aspect of the process may include the removal of sp2 and mixed hybridized carbon produced by the reaction along with the removal of any residual carbides, metal salts, elemental metals, and metal oxides. In another aspect, the present disclosure provides a carbon production process comprising, consisting of, or consisting essentially of any of the subgroups recited in (1) the reaction preparation, (2) the chemical reaction, (3) the isolation and (4) the purification processes described herein.

While, in one aspect, the overall process of producing diamond may involve at least three parts in one aspect, the present disclosure also provides methods of streamlining the process by combining (3) the separation and (4) the purification aspects into a single aspect or single step. For example, in one aspect, the present disclosure provides a method comprising, consisting essentially of, or consisting of (1) a reaction preparation, (2) a chemical reaction, (3) an isolation, and (4) a purification method described herein.

(1)Reaction preparation:

reaction preparation in moisture free environment:

the various salt-like and intermediate carbides react with water and/or dilute acid to produce hydrocarbon gases and metal oxides. Almost all salt-like and intermediate carbides also react with moisture in the air. As the carbides are ground to a smaller particle size, the reaction rate increases due to the increased surface area exposed to the environment. Some reactants, such as aluminum carbide, will react with moisture in the air to produce alumina (aluminum oxide), which can complicate the separation process. In one aspect, the present disclosure provides a process for removing elemental metals and metal oxides from reaction products using dilute or concentrated acids while the elemental carbon produced by the reaction remains unchanged.

Additionally, metal salts such as halide reactants may also attract moisture from the air to form a solution of ions dissolved in the water. Any moisture that accumulates in the salt may enter the reactor and react with the carbides. Moisture can also vaporize at the reaction temperature, thereby increasing the pressure and changing the reaction conditions. Thus, in one aspect, the reactants may be loaded in a controlled atmosphere glove box. In another aspect, the reaction conditions include an environment free of any moisture and oxygen. To achieve such a moisture free environment, the atmosphere may be prepared by flushing the glove box multiple times with a dry inert gas (such as, but not limited to, argon). Additional steps may be taken to further reduce and control moisture in the glove box. These steps may include, for example, using a metal salt as a desiccant inside a glove box and a recycle system, which may include a fines separator and several moisture separators. In one aspect, the glove box loading procedure includes evacuating the transfer chamber several times to remove or minimize any moisture entering the controlled atmosphere.

In one aspect, the present disclosure provides a method of preparing reactants and a reactor in an inert environment, wherein the reactants remain chemically unchanged prior to initiating the reaction. In another aspect, the inert environment is free or substantially free of oxygen and moisture. In one aspect, the inert environment contains only trace amounts of oxygen and moisture. In yet another aspect, only the physical properties of the reactants are changed prior to initiating the reaction.

Reaction preparation in an oxygen-free environment:

in one aspect, the preparation in an anaerobic environment is similar to the preparation in a moisture free environment. The preparation can be effected in a glove box which has been flushed several times with dry inert gas. In one aspect, one difference of the reaction preparation in the "oxygen-free environment" relative to the reaction preparation in the "moisture-free environment" is the removal of any trace amounts of oxygen remaining in the glove box after the inert gas flush along with the trace amounts of oxygen entering from the transfer chamber as the material is loaded and unloaded. In one aspect, an oxygen scrubber or series of scrubbers may be added to the glove box circulation system to remove traces of oxygen, depending on the reactants used and other reaction conditions. The cycle may also be designed to add additional items or to bypass existing items to achieve the appropriate conditions for any carbides and metal salts to be analyzed as reactants.

Reducing the grain size of carbide:

many commercially available carbides have a grit size and therefore can generally reduce the particle size to the size required for the reaction. To reduce the particle size of the carbides, the present disclosure provides a method to be used inside a glove box. In one aspect of the method, the carbide is first cut into smaller pieces using a brick cutter, then crushed with a pair of channel lock pliers, and finally ground to the appropriate particle size. The crushed carbide is thereafter passed through a series of screens to collect carbide of the desired particle size for use in the process. As an alternative to the above method, a small hand roller mill or suitable comminution device, which can be adjusted to produce the desired particle size for the experiment, can be used to produce carbide particles of the appropriate size.

In one aspect, the reaction described herein is a diffusion controlled reaction. Thus, the rate of reaction will be controlled by the total surface area available for reaction. The reaction rate includes properties such as porosity of the carbide and viscosity of the liquid medium, not just the particle size of the reactants. In one aspect, the aluminum carbide has a particle size of-300 mesh (44 microns) and the calcium carbide is in the form of grit. In another aspect, the calcium carbide is ground to a particle size of-20 mesh to-6 mesh. In yet another aspect, the calcium carbide is from about 10 microns to about 5 millimeters, from about 30 microns to about 3 millimeters, from about 100 microns to about 2 millimeters, or from about 30 microns to about 200 microns in size.

Shape and orientation of the reactor:

through experiments and analysis of the materials produced by the reaction, it was determined that once the metal salt became molten and the reactants were in liquid solution and the contents of the reactor reached a steady state (this is also assumed that the reactor was not agitated), the different materials inside the reactor were separated into layers based on their respective specific gravities. The carbides are not dissolved in the molten salt. Thus, the reaction proceeds between a solid phase and a liquid phase. It is not homogeneous. The reaction takes place at the contact surface of the molten salt with the solid carbide. Such mechanisms further confirm that surface area can be the reason for important parameters to be considered in one respect. Thus, in one aspect, the reaction can occur at a vertical height at which the reactants can physically aggregate to react under appropriate conditions.

In one aspect, it is advantageous to limit the contact surface of our reactor configuration to have a limited contact area. This is another parameter that has an impact on the kinetics of the diffusion-controlled reaction in the reaction system described herein, which is non-turbulent inside the reactor. Limiting the contact area allows the reaction to proceed at a rate slow enough that the latent heat of crystallization does not increase the temperature of the contact area to the point of sp2 carbon generation. This parameter is therefore influenced by other reaction conditions. The importance of the parameters can also be reduced if we agitate the reactor. Any means having the ability to increase the contact area will achieve a higher effective reaction zone. This can also be achieved, for example, by changing the reactor orientation or by stirring. Thus, different reactor designs and orientations may be utilized in an attempt to maximize the surface area of the horizontal interface at which reaction may occur. In one aspect, the reactor prepared in the glove box is made of glass and the reactants are loaded inside. The glass reactor can be sealed in a stainless steel tube so that it can be removed from the glove box and controlled atmosphere conditions can be maintained inside throughout the reaction. Initially, the reactor comprised a simple glass test tube whose diameter varied based on the desired mass and ratio of reactants to be used.

To increase the surface area of the horizontal interface where the reaction takes place, the height of the reactor is reduced while maintaining the same amount of material that can be held by the reactor. One way to achieve this is by orienting the reactor in a horizontal direction rather than a vertical direction. However, an open top test tube type reactor may not be sufficient because the reaction takes place in a liquid medium. Thus, for some of the experiments described herein, ampoule type glass reactors were utilized. This design provides a design that is both simple and effective.

In one aspect, the present disclosure provides methods of varying the size and orientation of a chemical reaction vessel to control the surface area, shape, and thickness of a reaction interface.

In one aspect, several horizontally oriented reactors are carried out by the purification portion of the process. This produced unexpectedly good results. In another attempt to increase the interfacial surface area, in one aspect, multiple glass culture dishes are stacked one on top of the other in the same stainless steel tube. This allows for many large surface area reaction interfaces to be contained within the same stainless steel tube.

(2)Chemical reaction:

method for oxidizing carbide anions and/or anions from carbides

In one aspect, the present disclosure provides a method of oxidizing carbide anions or negative ions from salt-like carbides at low temperatures below about 600 ℃. In another aspect, the present disclosure provides methods of oxidizing carbide anions or anions from salt-like carbides at temperatures below about 150 ℃, below about 200 ℃, below about 250 ℃, below about 300 ℃, below about 400 ℃, below about 500 ℃, below about 600 ℃, below about 700 ℃, or below about 800 ℃. In yet another aspect, the present disclosure provides a method of oxidizing carbide anions or negative ions from a salt-like carbide at a temperature in the range of: about 150 ℃ to about 200 ℃, about 150 ℃ to about 250 ℃, about 200 ℃ to about 300 ℃, about 200 ℃ to about 350 ℃, about 200 ℃ to about 400 ℃, about 250 ℃ to about 400 ℃, about 200 ℃ to about 500 ℃, about 250 ℃ to about 500 ℃, about 300 ℃ to about 600 ℃, about 400 ℃ to about 600 ℃, about 500 ℃ to about 700 ℃, about 200 ℃ to about 700 ℃, about 250 ℃ to about 750 ℃, about 150 ℃ to less than 800 ℃, about 250 ℃ to less than 800 ℃, about 300 ℃ to less than 800 ℃, about 400 ℃ to less than 800 ℃, about 500 ℃ to less than 800 ℃, or about 600 ℃ to less than 800 ℃.

Oxidation means that ions are oxidized to give off electrons. The negative ion reaction of the salt-like carbide produces elemental carbon in various allotropes or crystal structures with sp1, sp2, and/or sp3 hybridization. In another aspect, the present disclosure provides a reaction with an intermediate transition metal carbide. In yet another aspect, the present disclosure provides a reaction system in which salt-like carbide anions and intermediate carbide anions are oxidized to produce pure carbon of various allotropes.

In one aspect of the present invention,the first step of the reaction system is to oxidize the carbide ions at the temperatures described herein. The reaction uses a low melting point salt (e.g., stannous chloride (SnCl) having a melting point less than 280 ℃₂) As a reactant). The reaction medium is a molten salt, for example, molten stannous chloride. This means that there is an excess of salt during the reaction that takes place in the molten salt liquid. Chemically, the cation (positive ion) of the salt is reduced to the elemental state. Thus, stannous ion Sn⁺²Will become elemental tin (Sn °). Stannous ion Sn⁺²The standard reduction potential of (a) is only about-0.136V. The reduction potential refers to the ability of a chemical substance to acquire electrons and thus have its charge reduced. Thus, excess energy is not required to reduce the stannous ion and the reaction is to completion. There is an excess of reduction potential in the carbide anions as they are shown to reduce potassium ions in equation (1) which requires-2.94V.

Nowhere in the literature is there any mention of acetylides or any carbides to anion Sn⁺²And (4) reducing. Only certain metal salts are suitable for this reaction. Preferably, the cations of the salt do not react directly with carbon at low or reducing temperatures to produce carbides. If the cations do produce carbides, pure carbon will not be produced. Examples of preferred salts include tin, lead, mercury and zinc. Furthermore, the salt must have a low melting point. The reaction temperature must be high enough to melt the salt, but low enough to control the electronic hybridization of the carbon. As mentioned in the background information, graphite is the thermodynamically most stable form of pure carbon. Thus, if the reaction temperature is too high, pure carbon will form crystalline graphite in sp2 hybridization rather than the desired sp1 or sp3 hybridization.

The next item in the reaction system is the low temperature oxidation of the methanide to produce diamond or carbon with sp3 hybridization. Aluminum carbide (Al)₄C₃) And beryllium carbide (Be)₂C) Are the only two known salt-like carbides that produce methane upon reaction with water. The methane molecule contains carbon atoms in the same sp3 hybridization state as diamond. The idea is to react the methanide anion in a controlled manner at a sufficiently low temperatureOxidation to maintain the electronic configuration or sp3 hybridization and produce diamond. Thus, controlled oxidation of aluminum carbide at sufficiently low temperatures will preferentially produce diamond. The reduction takes place at about 280 ℃ and atmospheric pressure.

Oxidation of the methide (aluminum carbide) anion in the molten tin halide salt blend produces diamond. There is no reference to the reduction of aluminum carbide and certainly no reference to the reaction producing diamond or sp3 hybridized carbon. Stannous fluoride (SnF) having melting points of 214 ℃ and 235 ℃ respectively has been used₂) And stannous chloride (SnCl)₂) Experiments were conducted for this reaction. These reactions can be seen in equations (2) and (3) below:

reaction formula 2

Al₄C₃+6SnF₂→6Sn°+4AlF₃+3C°_(Diamond)Reaction at 235 deg.C (2)

Reaction formula 3

Al₄C₃+6SnCl₂→6Sn°+4AlCl₃+3C°_(Diamond)Reaction at 280 ℃ T ═ 3

X-ray diffraction patterns were used to confirm the evidence of diamond produced or carbon material with sp3 hybridization. Early diamond production investigated certain metal catalysts required to produce diamond. The fact that diamond was produced using the conditions described herein was unexpected and provided support for the methods described herein.

Since the chemical assumption of maintaining sp3 hybridization of pure carbon was confirmed with the generation of diamond, it can be extended to include a potential superconducting material to maintain sp1 hybridization of pure carbon. Many different attempts have been made to prepare such materials, but none have been successful. The process starts with carbides containing carbon in an sp1 hybrid state. As mentioned in the background information, acetylides have the ability to meet this requirement. The most common example is calcium carbide (CaC)₂). However, even the sp1 carbon in the acetylide anionTo be reconfigurable at very low energies or low temperatures. A more desirable reactant is one that has a tendency to maintain an sp1 configuration throughout the stringent requirements of the reaction. The present disclosure provides two compounds with the ability to act as sufficient reactants: magnesium sesquicarbide (Mg)₂C₃) And lithium sesquicarbide (Li)₄C₃) They are also mentioned in the background information. Structural analysis using X-ray diffraction has been accomplished from literature, e.g., "Crystal Structure of Magnesium sesquacarbde," Fjellvaag, h. and Karen, p.organic Chemistry, volume 31 (1992):3260-3263, which is incorporated herein by reference in its entirety, and shows that the two carbon atoms are equivalent, having a configuration sp 1. Using the hydrolysis reaction, methylacetylene (CH) is produced₃C₂H) In that respect One terminal carbon, i.e. methyl Carbon (CH)₃) The end is sp3 in nature, while the other two carbons maintain their sp1 character. The goal is to polymerize the carbon atoms while maintaining the sp1 configuration. This will produce a new allotrope of carbon with sp1 configuration. Due to the electronic nature of such materials, it may be a high temperature superconductor.

In another aspect, less than about 0.5%, less than about 1%, less than about 2%, less than about 3%, less than about 4%, less than about 5%, less than about 7.5%, less than about 10%, less than about 15%, less than about 20%, less than about 25%, less than about 30%, less than about 35%, less than about 40%, less than about 45%, less than about 50%, less than about 60%, or less than about 75% of the total yield includes material having a diamond structure (e.g., sp3 carbon structure). In another aspect, about more than 0.5%, about more than 1%, about more than 2%, about more than 3%, about more than 4%, about more than 5%, about more than 7.5%, about more than 10%, about more than 15%, about more than 20%, about more than 25%, about more than 30%, about more than 35%, about more than 40%, about more than 45%, about more than 50%, about more than 60%, or about more than 75%, about more than 85%, or about more than 95% of the total yield includes material having a diamond structure. In yet another aspect, about 0.1% to about 1%, about 0.5% to about 2%, about 1% to about 2%, about 2% to about 5%, about 2% to about 7.5%, about 0.5% to about 10%, about 3% to about 10%, about 5% to about 25%, about 0.1% to about 35%, about 0.1% to about 40%, about 0.1% to about 50%, about 1% to about 50%, about 5% to about 50%, about 10% to about 50%, about 15% to about 50%, about 25% to about 50%, or about 1% to about 95% of the total yield includes material having a diamond structure. In one aspect, the yield of diamond is relative to the "possible" products described in fig. 1.

In another aspect, about less than 0.5%, about less than 1%, about less than 2%, about less than 3%, about less than 4%, about less than 5%, about less than 7.5%, about less than 10%, about less than 15%, about less than 20%, about less than 25%, about less than 30%, about less than 35%, about less than 40%, about less than 45%, about less than 50%, about less than 60%, or about less than 75% of the yield relative to the amount of graphene and amorphous carbon also recovered includes materials having a diamond structure. In another aspect, about more than 0.5%, about more than 1%, about more than 2%, about more than 3%, about more than 4%, about more than 5%, about more than 7.5%, about more than 10%, about more than 15%, about more than 20%, about more than 25%, about more than 30%, about more than 35%, about more than 40%, about more than 45%, about more than 50%, about more than 60% or about more than 75%, about more than 85% or about more than 95% of the yield relative to the amount of graphene and amorphous carbon also recovered includes materials having a diamond structure. In yet another aspect, about 0.1% to about 1%, about 0.5% to about 2%, about 1% to about 2%, about 2% to about 5%, about 2% to about 7.5%, about 0.5% to about 10%, about 3% to about 10%, about 5% to about 25%, about 0.1% to about 35%, about 0.1% to about 40%, about 0.1% to about 50%, about 1% to about 50%, about 5% to about 50%, about 10% to about 50%, about 15% to about 50%, about 25% to about 50%, or about 1% to about 95% of the yield relative to the amount of graphene and amorphous carbon also recovered includes a material having a diamond structure.

In another aspect, the present disclosure provides a process wherein the yield from the carbide starting material is greater than about 5% pure carbon, greater than about 10% pure carbon, greater than about 20% pure carbon, greater than about 30% pure carbon, greater than about 40% pure carbon, greater than 50% pure carbon, greater than 60% pure carbon, greater than 70% pure carbon, greater than about 80% pure carbon, greater than 90% pure carbon, or greater than 95% pure carbon.

As discussed in the chemical reaction section, in one aspect, diamond growth occurs at a vertical level inside the reactor, e.g., in a steady state without agitation, where the reactants meet under appropriate conditions. The reaction that takes place is exothermic, which means that it releases heat. As the reaction proceeds, more heat is generated and transferred through the remainder of the reactor. Heat is generated at the reaction site at a rate greater than that transferred away from the reaction site using reaction conditions such as those described in examples 1-3. This means that as the reaction proceeds and the diamond crystals grow, the temperature of this region inside the reactor will continue to increase. If the temperature at the reaction site is increased above a certain level, the thermodynamics of the reaction will change. Specifically, if the temperature becomes too high, the reaction will stop producing diamond and begin producing sp2 carbon. When this new reaction proceeds, the sp2 carbon will seal the diamond and the crystal growth will terminate. The diamond crystal will then have a cladding (jacket) of sp2 carbon at the surface.

Inert materials are used to alter the heat and mass transfer of the reaction and increase the area of the reaction zone:

in addition to carbides and metal salts, in one aspect, additional materials may be added to the reactor to alter heat and mass transfer during the chemical reaction step of the process. In one aspect, the additional material may be any material that is inert with respect to the respective reactants and that can withstand the conditions (e.g., temperature, molten salts) inside the reactor. Examples include ceramic beads or stainless steel ball bearings. These materials may also increase the total surface area or volume of the physical region in the reactor where the chemical reaction takes place. These materials are inert and therefore remain unaltered by chemical reactions. In one aspect, the present disclosure provides for the addition of excess reactants or otherwise remain untouchedA method of reacting chemically altered inert materials to alter heat and mass transfer properties inside a reactor. In another aspect, additionally, carbides and metal salts to be used as reactants, inert materials, catalysts (e.g., FeCl)₃) And additives that alter the properties of the resulting diamond, such as dopants, are added to the reactor and may be utilized with the methods described herein.

(3)And (3) product separation:

reduction of elemental metal from the reaction product:

the product of the carbon-producing reaction includes elemental metal that can be removed. In one aspect, these metals can be removed from other reaction products by using a reducing agent such as hydrochloric acid (HCl). In another aspect, any acid that oxidizes the elemental metal produced can be used for the separation. One key feature is to oxidize the metal and thus remove it while maintaining the diamond (sp3 carbon) unchanged. The acid may also maintain sp2 and mixed hybridized carbon unchanged to leave an opportunity to check for sp2 and mixed hybridized carbon produced in the future by additional products from the process. One potential application of non-diamond products is in supercapacitors. Once the reaction was complete and the stainless steel transfer tube was opened, the reaction product was transferred to a separate vessel made of polypropylene. In one aspect, the separation vessel is made of any material that is inert to the acid used to remove the elemental metals and metal oxides, as well as any other solvents required for the separation process. In addition, the container should also be able to withstand the increased gravitational forces of the centrifuge that is also used in the separation process.

Use of surfactants in the separation process:

during the separation process, the salt, as well as the sp2 and mixed hybrid carbon, act as a glue holding the particles together. The liquid used to dissolve away the salt, which is mainly water and alcohol and acid, produces films and agglomerates that hold together particles, particularly very fine-grained diamond. The addition of the surfactant serves to rupture any membranes and to aid in the separation of particles so they can be more easily dissolved or dispersed by the liquid. In addition to separating the particles for dissolution, the surfactant solution also acts like a soap and forces any undesirable material away from the surface of the diamond. Another advantage of the surfactant solution in the separation process is that the settling rate of the fine material is reduced or increased. After the acid removes the elemental metal, the most dense material remaining is diamond. Thus, diamond settles first based on particle size. The finer particle size diamond remains suspended in solution due to Brownian motion. The surfactant solution changes the surface tension of the water used to dissolve the salt. This lower surface tension allows finer grained diamond to settle out of solution at different rates.

On the other hand, surfactants may also allow for better separation of diamond from other materials. In another aspect, different surfactants or surfactant mixtures can be used to separate out various products and even the diamonds produced in the reaction into various populations of different particle sizes. In another aspect, silicone-based surfactants can be used with the methods described herein. Suitable Surfactants for use with the method include those described in "Surfactants: APracial Handbook," Lange, Robert K.Philadelphia, PA: Hanser Gardner publications, 1999, the contents of which are incorporated herein by reference in their entirety.

In one aspect, the present disclosure provides a method of recovering a fine particle size of a desired product from water, an alcohol, a surfactant solution, a heavy medium, or an acid used in a separation process by filtering fines from the solution.

Gravity separation of diamond using dense or dense media:

the diamond produced in the reaction may be separated from other reaction products based on the difference in specific gravity of the materials. For example, the chemical reaction product may be added to perchloroethylene liquid having a specific gravity of about 1.6, dibromomethane having a specific gravity of 2.4 and/or halogenated organic compounds having a specific gravity >2.0 for gravity separation. Diamond with a specific gravity of about 3.3 will sink in the liquid and separate from any material with a specific gravity of less than 1.6 that will float on the surface of perchloroethylene. Gravity separation can be used to separate the composite particles in the step and to purify the diamond in the step. In another aspect, any chemical material or chemical compound may be used during this step based on the specific gravity difference between the target composition (e.g., diamond) and the chemical material or chemical compound to be separated.

Removal of unreacted carbides:

it will not be possible for all of the reactants in the process to be completely consumed by the reaction and converted to products, especially under reaction conditions optimized for the economics of the process. Thus, unreacted carbides will remain in the reaction product and have to be removed or separated. Unreacted carbides readily react with water to produce hydrocarbon gases and metal oxides. In many cases, the metal oxide is readily reacted away using an acid. Thus in the transfer step from the reactor to the separation vessel using the acid, water reacts with the carbide to produce acetylene and metal oxide, which is then reacted by the acid. If any residual unreacted carbides are present in the acid treated reaction product, they may react with water or water in the surfactant solution. Due to the subsequent treatment with acid in the subsequent step, the resulting metal oxide will eventually be reacted and removed from the reaction product.

In one aspect, the present disclosure provides a method of removing unreacted carbides from a corresponding target reaction product by reacting the carbides with water and further reacting the resulting metal oxides with an acid.

Removal of unreacted metal salt and metal salt produced in the reaction:

removal of the metal salt resulting from the reaction can be achieved using water or a surfactant solution, an alcohol or an acid. During the separation process, the reaction product is transferred to a separation vessel. A liquid that dissolves unreacted metal salt and metal salt produced in the reaction may be added to a separation vessel and agitated for a period of time. The separation vessel may then be allowed to settle by standing and the liquid in which the metal salt is dissolved is decanted or removed. To accelerate the process and also to perform a better separation in which the solid material is forced out of solution, the separation vessel is placed in a bucket centrifuge (bucket centrifuge). In one aspect, the liquid in the separation vessel still contains dissolved salts that can now be removed.

In one aspect, the present disclosure provides a method of removing unreacted metal salt and metal salt produced by the reaction from a reaction product by dissolving the unreacted product in water, alcohol, a surfactant solution, or an acid.

In another aspect, the present disclosure provides methods of separating and dispersing individual solid particles from respective reaction products using a surfactant solution. In another aspect, the method of separating and dispersing individual solid particles from respective reactions further comprises removing undesired, non-target or trace amounts of reaction products by dissolving and/or reacting and then removing undesired, non-target or trace amounts of products from the mixture. In yet another aspect, the desired product remains unchanged by the reaction chemistry and can be purified and classified as a different product.

In another aspect, the present disclosure provides methods for separating, removing, and/or classifying undesired reaction products by specific gravity using a dense medium liquid and/or a surfactant solution.

Separating the elemental metal from the reaction product by reaction:

other materials (e.g., dibromomethane) that diffuse into the composite particles and react with any elemental metal produced in the reaction can also be used to remove the elemental metal produced in the reactions described herein. For example, dibromomethane has the ability to diffuse into the composite particles of the reaction product and react with the enclosed metal. This method allows for the removal of all the elemental metal produced in a single step before the removal of the sp2 carbon, thereby separating any remaining composite particles. In one aspect, the reaction product is exposed to a material (e.g., dibromomethane) for a sufficient resonance time to allow diffusion into the composite particles and reaction with the elemental metal. Examples of sufficient resonance are hours to days. In another aspect, examples of sufficient resonance are about 2 hours or more, about 5 hours or more, about 12 hours or more, about 1 hour or more, about 2 days or more, about 3 days or more, or about 5 days or more. In another aspect, examples of sufficient resonance are from about 1 hour to about 4 hours, from about 2 to about 12 hours, from about 2 hours to about 1 day, from about 6 hours to about 2 days, from about 12 hours to about 2 days, or from about 1 hour to about 3 days. This rate of the reaction is governed by the diffusion of species into the composite particle. Thus, the sufficient resonance time will depend primarily on the size of the composite particles and/or the viscosity of the liquid reaction medium.

In one aspect, the present disclosure provides a method of removing elemental metal from reaction products of other materials (e.g., dibromomethane) that have the ability to diffuse into the composite particles and reduce the elemental metal.

Removing the metal oxide from the reaction product:

many of the reactants used herein produce metal oxides that can be reacted by various acids. However, there are reactants that produce metal oxides that do not react with the acid, e.g., aluminum carbide. In the case of alumina, it produces a product known as alumina or alumina. Alumina is very stable and does not react with acids. But it can be reacted with a potassium hydroxide solution. This is a more difficult separation due to the use of potassium hydroxide solution, as keeping potassium hydroxide in solution requires the addition of heat.

Recovery of fine-grained solids during separation:

although the reacted elemental metal and dissolved metal salts are separated from the elemental carbon, the removed liquid still contains a small percentage of solid composite particles. In one aspect, the liquid removed contains, for example, less than about 0.5%, less than about 1%, less than about 2%, less than about 3%, less than about 4%, less than about 5%, less than about 7.5%, less than about 10%, less than about 15%, less than about 20%, less than about 25% of the solid composite material. In another aspect, the liquid removed contains, for example, about 0.1% to about 1%, about 0.5% to about 2%, about 1% to about 2%, about 2% to about 5%, about 2% to about 7.5%, about 0.5% to about 10%, about 3% to about 10%, about 5% to about 25%, or about 0.1% to about 35% of the solid composite. In one aspect, the solid composite contains diamond along with other reaction products. These composite particles can be recovered from the supernatant liquid using filtration or gravity separation. The recovered material may be further processed to recover the produced diamond.

Recovery of alcohol solvent:

in one aspect, the present disclosure provides a system for recovering alcohol and a dense medium liquid. When scaling up to accommodate commercialization, solvent recovery may become important. An exemplary recovery system for alcohol is described herein.

(4)And (3) purifying a product:

the aspect of diamond purification is an additional step in the process of removing reaction products that are not sp3 carbon (diamond). This step begins with the removal of sp2 carbon from the reaction product. In one aspect, removal of sp2 and mixed-hybridized carbon can be accomplished using two different oxidation procedures, namely oxidation of sp2 and mixed-hybridized carbon in a hot furnace and/sp 2 and mixed-hybridization in a strong oxidizing solution such as H₂O₂Or HNO₃Oxidation in (1). Both methods can be used to completely remove sp2 carbon, depending on the initial reactants and reaction conditions used in the process.

After removal of sp2 and mixed hybridized carbon, the purification part of the process will be similar to the separation part, which is why we believe we will eventually be able to combine them into one part of the process. Very good results have been achieved in the purification part of the process, especially in terms of removal of sp2 and mixed hybridized carbon.

In one aspect, the present disclosure provides a method of reacting sp2 hybridized carbon from residual elemental carbon while maintaining the residual elemental carbon unchanged using a concentrated acid. The present disclosure further provides methods of removing sp2 hybridized carbon from residual elemental carbon while maintaining the residual elemental carbon unchanged by dispersing sp2 carbon in a surfactant solution. In yet another aspect, the present disclosure provides methods of removing sp2 hybridized carbon from residual elemental carbon and classifying the residual elemental carbon by particle size using a dense medium liquid or a combination of dense medium liquids.

Chemical reaction to remove sp2 carbon:

the factor in removing sp2 and mixed hybridized carbon from the reaction product is to do this task while maintaining the diamond (or sp3 carbon) unaltered by the process. In addition to oxidizing sp2 carbon to remove it, another option is to react the sp2 carbon using one or more chemicals under appropriate reaction conditions. One example is the use of trifluoroacetic acid and concentrated hydrogen peroxide.

Use of surfactant in the purification step:

in one aspect, the use of the surfactant in the purification process is nearly the same as the use of the "surfactant in the separation step". One difference is the reduction in particle size of the material in the purification step and the absence of sp2 and mixed hybridized carbon, which would alter the conditions created by the surfactant or surfactant mixture.

Recovery of fine-grained diamond during purification:

this project is similar to "recovery of fine particle size solids during the separation step". One difference is that at this point in the process, the solid material to be recovered is diamond rather than composite particles. In addition, the particle size of the solids will be reduced. In one aspect, the recovery process will comprise filtration or gravity separation.

Examples

Example 1

In an oxygen-free moisture environment, aluminum carbide Al₄C₃Grinding to less than 20 meshes. Adding a certain amount of anhydrous stannous chloride SnCl₂Blended with ground aluminum carbide in twice the stoichiometric ratio for the following reaction

Al₄C₃+6SnCl₂→4AlCl₃+6Sn+3C

The blend was poured into a glass ampoule which was then placed in a stainless steel tube. The stainless steel tube was sealed and removed from the controlled environment. The tube and its contents were heated to 280 ℃ and held for 2 hours. The contents of the ampoule were washed with 6M HCl to remove all aluminum chloride, excess stannous chloride and Sn metals. The residual carbon is in two forms: (1) a graphene-like compressed platelet set and (2) a cubic diamond/orthorhombic diamond-like structure. The predominant carbon product is the latter structure.

Example 2

In an environment without oxygen and moisture, adding calcium carbide CaC₂Grinding to less than 20 meshes. A certain amount of anhydrous zinc chloride ZnCl is added₂Blended with ground aluminum carbide in twice the stoichiometric ratio for the following reaction

3CaC₂+3ZnCl₂→3CaCl₂+3Zn+6C

The blend was poured into a glass ampoule which was then placed in a stainless steel tube. The stainless steel tube was sealed and removed from the controlled environment. The tube and its contents were heated to 425 ℃ and held for 2 hours. The contents of the ampoule were washed with 6M HCl to remove all zinc chloride, calcium chloride and Zn metal. The residual carbon is in two forms: (1) a graphene-like compressed platelet set and (2) a cubic diamond/orthorhombic diamond-like structure. The predominant carbon product is the latter structure.

Example 3

In an environment without oxygen and moisture, adding calcium carbide CaC₂Grinding to less than 20 meshes. Adding a certain amount of anhydrous stannous chloride SnCl₂Blended with ground aluminum carbide in twice the stoichiometric ratio for the following reaction

3CaC₂+3SnCl₂→3CaCl₂+3Sn+6C

The blend was poured into a glass ampoule which was then placed in a stainless steel tube. The stainless steel tube was sealed and removed from the controlled environment. The tube and its contents were heated to 280 ℃ and held for 2 hours. The contents of the ampoule were washed with 6M HCl to remove all stannous chloride, calcium chloride and Sn metals. The residual carbon is only in one form, namely graphene-like compressed platelet groups.

Claims (70)

1. A method of producing an elemental allotrope of carbon, the method comprising: anionically oxidizing a salt-like carbide at a reaction temperature in a range of 150 ℃ to 750 ℃, wherein the oxidation reaction produces an allotrope of carbon in a sp2 and/or sp3 configuration, wherein the oxidation reaction is carried out with at least one molten metal halide salt reactant, the metal halide salt having a melting point of less than 280 ℃, the salt being used in excess relative to the carbide, and forming an elemental metal from the metal halide in the oxidation reaction, wherein the reaction occurs at atmospheric pressure and in an environment free or substantially free of oxygen and/or moisture.

2. The method of claim 1, wherein the salt-like carbide anions are selected from the group consisting of methanides and acetylides.

3. The method of claim 1, wherein the salt-like carbide anion is an acetylide.

4. The method of claim 1, wherein the reaction produces an allotrope of carbon in an sp3 configuration.

5. The method of claim 1, wherein the reaction temperature is in a range selected from the group consisting of: 150 ℃ to 200 ℃, 150 ℃ to 250 ℃, 200 ℃ to 300 ℃, 200 ℃ to 350 ℃, 200 ℃ to 400 ℃, 250 ℃ to 400 ℃, 200 ℃ to 500 ℃, and 250 ℃ to 500 ℃.

6. The method of claim 1, wherein the reaction temperature is in a range selected from the group consisting of: 300 ℃ to 600 ℃, 400 ℃ to 600 ℃, 500 ℃ to 700 ℃, 200 ℃ to 700 ℃, and 250 ℃ to 750 ℃.

7. The method of claim 1, wherein the carbide anions are from calcium carbide.

8. The method of claim 1, wherein the metal halide salt has a melting point of less than 250 ℃.

9. The method of claim 1, wherein the reaction produces an allotrope of carbon in an sp2 configuration.

10. The method of claim 1, wherein the reaction produces carbon in the form of graphene.

11. The method of claim 1, wherein the reaction produces carbon in the form of graphene-like compressed flakes.

12. The method of claim 1, wherein the reacting produces amorphous carbon.

13. The method of claim 1, wherein the reaction produces mixed hybrid carbon.

14. The method of claim 1, wherein the yield of pure carbon from the carbide starting material is greater than 70%.

15. The method of claim 4, wherein the product of the reaction is in the form of particles.

16. The method of claim 1, wherein the carbide anions are from calcium carbide or aluminum carbide.

17. The method of claim 1, wherein the carbide anions are derived from calcium carbide having a particle size of 10 microns to 5 millimeters.

18. The method of claim 1, wherein the carbide anions are derived from calcium carbide having a particle size of 30 to 200 microns.

19. The method of claim 1, wherein the reaction is carried out with the use of a dopant.

20. The process of claim 1, wherein the oxidation reaction is carried out at a temperature of 150 ℃ to 600 ℃.

21. The process of claim 1, wherein the oxidation reaction is carried out at a temperature of 150 ℃ to 500 ℃.

22. The process of claim 1, wherein the oxidation reaction is carried out at a temperature of 150 ℃ to 400 ℃.

23. The process of claim 1, wherein the oxidation reaction is carried out at a temperature of 150 ℃ to 300 ℃.

24. The method of claim 1, wherein the salt is used at twice the stoichiometric ratio relative to the carbide.

25. The method of claim 4, wherein the product of the reaction is isolated using a surfactant.

26. The method of claim 4, wherein the products of the reaction are separated using gravity separation.

27. The process of claim 4 wherein after the reaction, the reaction product is oxidized in a hot furnace or a strong oxidizing solution.

28. The method of claim 4, wherein after the reacting, the carbon is classified according to particle size.

29. The method of claim 1, wherein as part of producing carbon allotropes, the method further comprises removing material that is not elemental carbon from products of the oxidation reaction, and removing any undesirable elemental carbon produced by the oxidation reaction.

30. The method of claim 1, wherein the metal halide salt is a halide salt of tin, lead, mercury, or zinc.

31. A method of producing pure elemental allotropes of carbon, comprising: anionically oxidizing a salt-like carbide at a reaction temperature in the range of 150 ℃ to 750 ℃, wherein the oxidation reaction is conducted with at least one molten metal halide salt reactant, the metal halide salt having a melting point of less than 280 ℃, the salt being used in excess relative to the carbide, and forming an elemental metal from the metal halide in the oxidation reaction, wherein the metal halide salt is a halide salt of tin, lead, mercury, or zinc.

32. The method of claim 31, wherein the salt-like carbide anions are selected from the group consisting of methanides and acetylides.

33. The method of claim 31, wherein the reaction produces a pure elemental allotrope of carbon having an sp2 or sp3 configuration.

34. The method of claim 31, wherein the reaction produces a pure elemental allotrope of carbon having an sp3 configuration.

35. The method of claim 31, wherein the reaction temperature is in a range selected from the group consisting of: 150 ℃ to 200 ℃, 150 ℃ to 250 ℃, 200 ℃ to 300 ℃, 200 ℃ to 350 ℃, 200 ℃ to 400 ℃, 250 ℃ to 400 ℃, 200 ℃ to 500 ℃, and 250 ℃ to 500 ℃.

36. The method of claim 31, wherein the reaction temperature is in a range selected from the group consisting of: 300 ℃ to 600 ℃, 400 ℃ to 600 ℃, 500 ℃ to 700 ℃, 200 ℃ to 700 ℃, and 250 ℃ to 750 ℃.

37. The method of claim 31, wherein the reaction occurs in an environment free or substantially free of oxygen and/or moisture.

38. The method of claim 31, wherein the reaction produces a pure elemental allotrope of carbon having an sp2 configuration.

39. The method of claim 31, wherein the reaction produces carbon in the form of graphene.

40. The method of claim 31, wherein the reaction produces carbon in the form of graphene-like compressed flakes.

41. The method of claim 31, wherein the reacting produces amorphous carbon.

42. The method of claim 31, wherein the reaction produces mixed hybrid carbon.

43. The method of claim 31, wherein the yield of pure carbon from the carbide starting material is greater than 70%.

44. The method of claim 34, wherein the product of the reaction is in the form of particles.

45. The method of claim 31, wherein the carbide anions are from calcium carbide or aluminum carbide.

46. The method of claim 31, wherein the carbide anions are derived from calcium carbide having a particle size of 10 microns to 5 millimeters.

47. The method of claim 31, wherein the carbide anions are derived from calcium carbide having a particle size of 30 microns to 200 microns.

48. The method of claim 31, wherein the reaction is performed with a dopant.

49. The method of claim 31, wherein the oxidation reaction is conducted at a temperature of 150 ℃ to 600 ℃.

50. The method of claim 31, wherein the oxidation reaction is conducted at a temperature of 150 ℃ to 500 ℃.

51. The method of claim 31, wherein the oxidation reaction is conducted at a temperature of 150 ℃ to 400 ℃.

52. The method of claim 31, wherein the oxidation reaction is conducted at a temperature of 150 ℃ to 300 ℃.

53. The method of claim 34, wherein the product of the reaction is isolated using a surfactant.

54. The method of claim 34, wherein the products of the reaction are separated using gravity separation.

55. The process of claim 34 wherein after the reaction, the reaction product is oxidized in a heated furnace or a strong oxidizing solution.

56. The method of claim 34, wherein after the reacting, the carbon is classified according to particle size.

57. The method of claim 31, wherein the method further comprises removing material that is not elemental carbon from the product of the oxidation reaction, and removing any undesirable elemental carbon produced by the oxidation reaction.

58. The method of claim 31, wherein the reaction occurs at atmospheric pressure.

59. A method of producing diamond by reacting a carbide with a molten metal halide salt reactant at a reaction temperature in the range of 150 ℃ to 750 ℃, the metal halide salt having a melting point of less than 280 ℃, wherein an elemental metal is formed from the metal halide in the reaction, wherein the reaction occurs at atmospheric pressure and in an environment that is free or substantially free of oxygen and/or moisture.

60. The method of claim 59, wherein the reaction temperature is in a range selected from the group consisting of: 150 ℃ to 200 ℃, 150 ℃ to 250 ℃, 200 ℃ to 300 ℃, 200 ℃ to 350 ℃, 200 ℃ to 400 ℃, 250 ℃ to 400 ℃, 200 ℃ to 500 ℃, and 250 ℃ to 500 ℃.

61. The method of claim 59, wherein the reaction temperature is in a range selected from the group consisting of: 300 ℃ to 600 ℃, 400 ℃ to 600 ℃, 500 ℃ to 700 ℃, 200 ℃ to 700 ℃, and 250 ℃ to 750 ℃.

62. The method of claim 59, wherein the reaction further produces an elemental allotrope of carbon having an sp2 configuration.

63. The method of claim 59, wherein the reaction also produces carbon in the form of graphene.

64. A method according to claim 59, wherein the yield of diamond from carbide starting material is over 70%.

65. The method of claim 59, wherein the carbide is selected from calcium carbide or aluminum carbide.

66. The method of claim 59, wherein the carbide is calcium carbide having a particle size of 30 to 200 microns.

67. The method of claim 59, wherein the reaction is carried out at a temperature of 150 ℃ to 500 ℃.

68. The method of claim 59, wherein the reaction is carried out at a temperature of 150 ℃ to 400 ℃.

69. The method of claim 59, wherein the reaction is carried out at a temperature of 150 ℃ to 300 ℃.

70. The method of claim 59, wherein the metal halide salt is a halide salt of tin, lead, mercury, or zinc.