TW201416492A - Anodes for the electrolytic production of nitrogen trifluoride and fluorine - Google Patents

Abstract

A process and an anode for the production of nitrogen trifluoride or fluorine where the anode in the electrolytic cell is made primarily from parallel ordered anisotropic carbon, including needle coke and/or mesocarbon microbeads. The parallel ordered anisotropic carbon anodes minimize the production of CF4 and improve the purity of the nitrogen trifluoride or fluorine gas produced. Additionally, the anodes may be molded, instead of extruded or machined, providing for improved dimensional and mechanical integrity of the anode.

Description

Anode for electrolytic production of nitrogen trifluoride and fluorine Cross-reference to related applications

This is a partial continuation of US Patent Application No. 131859,263 filed on April 9, 2013, which claims the priority of the earlier application under 35 USC § 119(e): 2012 U.S. Patent No. 611,716,259, filed on Oct. 19, and U.S. Patent Serial No. 61/790,810, filed on March 15, 2013. The entire contents of each priority are incorporated herein by reference.

The present invention relates generally to an electrolytic production process of nitrogen trifluoride or fluorine, and in particular to the use of an anode made of parallel arranged anisotropic carbon comprising needle coke and metaphase carbon, the display of which Certain physical properties used to produce nitrogen trifluoride and fluorine.

Nitrogen trifluoride (NF ₃ ) is a stable gas with a little reactivity at room temperature. On the other hand, fluorine (F ₂ ) is a gas which is reactive with most materials under ambient conditions. Both NF ₃ and F ₂ have been found to be used more and more in semiconductor manufacturing. For example, NF _{3 is} typically used as an etchant for tantalum or tantalum oxide layers on a semiconductor substrate or when the CVD chamber cleaning gas is activated in the field.

When it comes to industrial scale, NF ₃ can be manufactured by a fluorination process. There are two main methods of fluorination: direct fluorination (DF) and electrochemical fluorination (ECF). In the electrochemical fluorination process, the electrolyte can be electrolyzed in an electrolytic cell to produce NF ₃ . F ₂ is produced in an electrochemical process similar to the ECF process used to produce NF ₃ . For example, conventional electrolytic cells use a carbon steel cathode and an extruded carbonized anode made of carbon coke particles and a carbon asphalt binder. Conventional anodes are made of isotropic coke and exhibit high macroscopic porosity as a result of the use of large particle sizes, which are often greater than 100 microns. These conventional extruded carbon anodes are carbonized at temperatures below 1000 ° C and typically do not be graphitized, and graphitization requires temperatures in excess of 1500 ° C. However, there are many references to the literature, for example, in "Electrical Fluorine Generation" by Ellis, JF and GFMay, Fluorine, the First Hundred Years, REBanks, DWA Sharp, and JCTatlow, Eds., Elsevier Sequoia, 1986. The disadvantages associated with conventional extruded carbon anodes.

One problem associated with electrochemical fluorination processes is that NF ₃ or F ₂ produced by electrolysis is contaminated with CF ₄ (tetrafluoromethane or carbon tetrafluoride). Any kind of pollution is a concern because it is desirable for high purity NF ₃ or F ₂ and is required in many industries, such as the semiconductor industry. CF ₄ is not practically separated from NF ₃ , J. Massonne, CHEMIE INGENIEUR TECHNIK, v. 41, N 12, p. 695 (1969). Therefore, any CF ₄ contamination reduces the purity of the resulting NF ₃ and cannot be easily removed. Regarding F ₂ , although CF ₄ may be formed, it may be separated and removed, however, this requires an additional and expensive process step to purify and recover the purified F ₂ .

Another with traditional carbon anodes, such as carbon char and asphalt binders The problem with carbon anodes is that the anodes must be capable of being extruded, machined, or both to form the anode shape. However, such anodes may not have precise shape and design and may not function properly and may not be present. This causes poor dimensional and mechanical integrity of the anodes.

Another problem is that the anode is polarized when it is deactivated and no longer in effect. This state is indicated by a higher than normal battery voltage and is referred to as "polarization." When a carbon anode is used to make F ₂ or NF ₃ , the main cause of the decay of the polarized battery is. Extreme conditions are sometimes referred to as "anode effects." M. Jaccaud, R. Faron, D. Devilliers and R. Romano, "Fluorine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag, 2000. By preventing polarization, the battery can be operated longer between reassembly, thereby reducing production costs.

Therefore, there is still a need to form fewer by-products when electrolytically producing NF ₃ or F ₂ and thereby produce higher purity NF ₃ or F ₂ anodes, anodes with better dimensional integrity, and minimize polarization. A reduced or reduced anode.

The present invention provides a production process for producing nitrogen trifluoride, fluorine or both using an electrolytic cell, wherein the anode is made of anisotropic carbon or coke arranged in parallel, the anisotropic carbon or coke comprising needle coke, crystal Lenticular coke, mesocarbon and incipient mesophase carbon including mesocarbon microspheres are all defined by J. Speight, Handbook of Petroleum Product Analysis, John Wiley & Sons, 2002. This type of carbon exhibits substantially parallel arranged or layered regions of various sizes relative to irregularly layered or concentrically layered (onion-like) carbon, or amorphous or glassy carbon. It has been found that by using this anode comprising anisotropic carbon arranged in parallel, a lower battery voltage and higher than conventional amorphous or any isotropic coke layered by a sponge, a bullet, a concentric layer can be achieved. Current density. Furthermore, such displays are found in certain physical properties of the anode by-products, such as CF _4, and generation of reducing to a minimum; thus, greatly improved the purity of produced fluorine or nitrogen trifluoride. Physical properties that provide this advantage include small particle size, low open porosity, high density, and/or reduced mesoporous carbon such as those due to carbonization of oxygenated carbon precursors or the use of porous coke like sponge coke. In addition, the anodes can be molded, instead of being extruded or machined, to provide improved dimensional and mechanical integrity to the anode. In other words, unlike conventional anodes, which must be extruded and/or machined, the shape of the die-cast anode is tuned to make it more precise and reproducible, providing a higher quality and better functioning anode. This also allows the battery geometry to be more consistent, allowing electrolyte circulation and bubble separation to be more reproducible. The anode of the present invention also exhibits improved resistance to polarization that is accompanied by the benefits described herein.

Among the physical properties, carbon objects of the type described in this document usually use apparent density to characterize them. Because these materials consist of agglomerated and bonded or sintered particles, they are porous. The extent of this porosity, measured as a percentage of the total object volume, and characteristics such as average pore size, pore size distribution, and whether the pores are interconnected (open) or independent (closed) are associated with processing conditions and techniques. Pure crystalline graphite represents sp2 mixed carbon, such as the highest density fill seen in the carbon articles described herein. The appearance of pores reduces the apparent density from this theoretical maximum of about 2.23 g/cm ³ . Most carbon and graphite articles, including conventional and disclosed carbon anodes for the production of NF ₃ and F ₂ , have an apparent density of from about 1.5 g/cm ³ to 1.9 g/cm ³ .

Although there is no ASTM standard test for the porosity of carbon materials today, it is customary to be applied to several known techniques in this art. For example, mercury porosimeter and gas absorption data can be analyzed using the Washburn equation and the BET (Brunauer-Emmett-Teller) theory, respectively. Most of the synthetic carbon and graphite articles made from bonded or sintered carbon powder exhibit an open porosity of from about 8% to about 20% using a mercury porosimeter. The literature describes the higher density of a particular carbon material, which necessarily indicates a reduced total porosity, and also corresponds to a lower open porosity and fewer small pores (Properties and Characteristics of Graphite, RG Sheppard, Dwayne Morgan, DMMathes, DJBray Editor, POCO Graphite Ltd., 2002).

Without wishing to be bound by a particular theory, it is believed that the reduced porosity results in a lower surface area which is easier to pass through the liquid electrolyte. It is believed that the formation of CF ₄ can be minimized by reducing the accessible surface area and eliminating electrolyte trapping in small pores.

In a specific embodiment, the present invention provides a method of producing nitrogen trifluoride or fluorine comprising electrolysis by using anisotropic carbon (eg, mesocarbon, such as mesocarbon microspheres) comprising parallel arrangements The anode is subjected to electrolysis of an electrolyte to obtain nitrogen trifluoride or fluorine. For example, the anode may have an active geometric surface area of up to about 70,000 cm ² or greater. In the case of interphase carbon microspheres, the interphase carbon microspheres may be isostatically pressed mesocarbon microbeads. In a specific embodiment, the anode is molded and sintered only by molding and consisting of sintered meta-carbon microspheres and without the inclusion of binders or other additives. The intermediate carbon microspheres are preferably also not graphitized. In a specific embodiment, the anode made of the molded interphase carbon microspheres has a high density, for example, a density of 1.7 g/cm ³ or higher, and a porosity of less than about 20% or less. About 15%. Further, the intermediate carbon microspheres can have an average particle diameter of from about 1 to 5 microns in diameter.

In another embodiment, the invention provides a method of producing nitrogen trifluoride or fluorine comprising: electrolyzing an electrolyte by using an electrolytic anode comprising needle coke. The needle coke can be bonded together with a suitable binder, such as a highly aromatic asphalt binder or a metaphase-forming asphalt, which may contain a small amount of oxygen. Furthermore, the anode may comprise particles of less than 50 microns, or more preferably less than 20 microns, and may have greater than 1.6 g/cm ³ , or more preferably greater than 1.7 g/cm ³ and most preferably greater than 1.8 g/cm. The density of ³ . The anode is preferably baked to a temperature not higher than about 1600 °C. The needle coke in this embodiment can also be replaced by other parallel arranged cokes, such as crystalline coke. In another embodiment, the coke or binder may be replaced by a mesophase, primary interphase coke or bitumen, or an amorphous but interbedded bitumen.

Compared to traditional extruded carbon anodes, is adapted by using carbon as the anode material of the present invention to produce high purity and little or substantially lower nitrogen trifluoride and fluorine CF _4. For example, the method can make pure fluorine or nitrogen trifluoride product gas produces less than 100ppm of CF _4, preferably less than 75ppm of CF _4, CF 50ppm and more preferably less than _4. The electrolysis method for producing nitrogen trifluoride or fluorine may have a selectivity of 70% or more, preferably 80% or more. Suitable electrolytes can be selected by those of ordinary skill in the art. To produce nitrogen trifluoride, the electrolyte can be a binary electrolyte or a ternary electrolyte, for example. The binary electrolyte can include HF and NH ₄ F or other suitable binary electrolytes known in the art. The ternary electrolyte may include one of HF, NH ₄ F and KF, LiF or CsF, or the like, or other suitable ternary electrolytes known in the art. For instance, there is a Electrolyte composition may comprise from about 35 to 45 wt% HF, about 15 to 25 wt% NH ₄ F and from about 40 to 45 wt% KF. To produce fluorine, the electrolyte can be a binary electrolyte, including, for example, HF and KF.

The nitrogen trifluoride method and the fluorine method can be carried out under appropriate conditions and operating process parameters, including temperature and current density, which are generally selected by those skilled in the art. For example, nitrogen trifluoride can be produced at a temperature of about 120 to 140 ° C and a current density of about 250 mA/cm ² . Fluorine can be produced at a temperature of about 80 to 90 ° C and a current density of about 350 mA / cm ² .

In another embodiment, the present invention provides an electrolytic cell for producing nitrogen trifluoride or fluorine, comprising: an anode comprising an anisotropic carbon disposed in parallel, a cathode, and comprising HF, optionally KF, and optionally An electrolyte composition of NH ₄ F. The electrolysis cell is operated to produce nitrogen trifluoride or fluorine of high purity with little or no CF ₄ contamination. In an exemplary embodiment, the anode consists of self-sintering, isostatically pressed, interphase carbon microspheres. In another exemplary embodiment, the anode consists of a die-cast carbon microsphere arbitrarily blended with a phenolic resin sintering aid. In another exemplary embodiment, the anode by the use of highly aromatic needle coke binder adhesive composition and exhibit low porosity (e.g., less than 20% porosity) and greater than 1.7g / cm ³ of density, by It is formed by isostatic molding.

11‧‧‧Anode product discharge pipe

12‧‧‧ Feeding tube

13‧‧‧Cathode product extraction tube

14‧‧‧Anode current wiring

15‧‧‧Cathode current wiring

16‧‧‧ Feeding tube

17‧‧‧anode compartment

18‧‧‧Cathode compartment

19‧‧‧ gas separation skirt

20‧‧‧Anode

21‧‧‧ cathode

22‧‧‧Separator

23‧‧‧ Electrolytes

25‧‧‧Electrolysis battery

26‧‧‧Electrolysis cell body

27‧‧‧ Electrolyte level

28‧‧‧Upper cover

29‧‧‧temperature adjustment device

30‧‧‧Temperature Detector

31‧‧‧Level indicator

32‧‧‧High liquid level adjustment point

33‧‧‧Low liquid level adjustment point

39‧‧‧ Current controller

41‧‧‧ Electrolyte samples埠

51‧‧‧ side

52‧‧‧ side

53‧‧‧Bottom surface of electrolytic cell

100‧‧‧Intermediate ball

100a‧‧‧ fragment of the media ball

110‧‧‧Extreme

120‧‧‧ Traces in the direction of the thin layer

130‧‧‧round edge

The invention may be best understood from the following detailed description. It is emphasized that, by convention, many different features of the drawings are not to scale. In contrast, the size of various features is expanded or reduced arbitrarily for clarity. The drawings include the following figures: Figure 1 shows two schematic diagrams: (a) a mesocarbon ball and (b) a segment of the mesophase ball shown in (a); Figure 2 is one of the electrolytic cells that can be used in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 3 is a schematic cross-sectional view of another embodiment of an electrolytic cell useful in the present invention; and Fig. 4 is an X-ray diffraction with respect to a mesophase carbon suitable for forming an anode according to the present invention. Figure.

The present invention provides a process for producing high purity nitrogen trifluoride and fluorine using an anode comprising anisotropic carbon arranged in parallel. In particular, a method of producing nitrogen trifluoride or fluorine includes electrolyzing an electrolyte by using an electrolytic anode comprising mesocarbon, mesocarbon microspheres, needle coke or other parallel arranged anisotropic carbon to obtain Highly selective and with reduced or minimal amounts of CF ₄ nitrogen trifluoride or fluorine.

As used herein, "anode" means the electrochemically active portion of the electrode, wherein nitrogen trifluoride or fluorine is produced in the cell when current is applied to the cell.

As used herein and in the context of the claims, the word "comprising" and "comprising" includes the singular or singular, and does not exclude other elements, components, or method steps that are not recited. Therefore, the terms "comprising" and "including" include the words "consisting essentially of" and "consisting of". All values provided herein are intended to include and include the specified endpoints, and the components or components of such compositions are expressed as weight percent or weight percent of each component in the composition, unless otherwise indicated.

Anisotropic carbon arranged in parallel

The present invention provides a process for producing high purity nitrogen trifluoride and fluorine using an anode comprising parallel disposed anisotropic carbon or coke. The anode for the production of nitrogen trifluoride or fluorine comprises anisotropic carbon arranged in parallel, such as mesocarbon microbeads (or MCMB) or needle coke. As used herein, relative to layered carbon, concentrically layered (onion-like) carbon, amorphous carbon or disordered glassy carbon, "parallelly arranged anisotropic carbon" or "parallel arrangement of orientations" Heterochromatic coke "is intended to include carbon that exhibits substantially parallel or layered regions. The anisotropic carbon or coke disposed in parallel may include needle coke, crystalline coke, mesocarbon, primary interphase carbon, and mesocarbon microspheres, for example, such as J. Speight, Handbook of Petroleum Product Analysis, John. As defined by Wiley & Sons, 2002.

As used herein, "intermediate carbon" or "intermediate carbon" is derived from the optically anisotropic, graphitizable carbon phase of a fusible organic compound. Needle coke and associated parallel anisotropic carbon are sometimes referred to as "intermediate" carbon, but the two terms often indicate different physical form carbons that exhibit similar microstructural properties. The interphase carbon can be separated from the optically isotropic material in the form of small particles, often referred to as mesocarbon microspheres. Therefore, the interphase carbon is intended to contain carbon having an optically anisotropic phase. In other words, the carbon exhibits optical anisotropy when viewed under a polarizing microscope (for example, an optical microscope using polarized light).

As used herein, "needle coke" is the optically anisotropic carbon, needle coke comprising disposed parallel layers or carbon, or any "Recommended Terminology for the Description of Carbon as a Solid," IUPAC, Pure The needle coke proposed in & Appl. Chem., Vol. 67, No. 3, pp. 473-506, 1995 defines a consistent carbon. It is known to change the physical properties of needle coke by grinding or shrinking the size, even to a particle size close to 1 micron.

In an exemplary embodiment, the anode primarily comprises anisotropic carbon disposed in parallel. As used herein, "mainly" indicates that the component is present in greater amounts than any other component of the associated composition, for example, the anode is mostly or completely parallel anisotropic carbon. In other words, the parallel arrangement of anisotropic carbon constitutes the majority of the anode, more than any other component. In particular, the anode may comprise at least 40%, at least 50%, at least 60%, at least 75%, at least 90%, at least 95% or at least 99% of anisotropic carbon arranged in parallel. In an exemplary embodiment, the anode is a substantially pure parallel arrangement of anisotropic carbon. In other words, with coke or carbonized bitumen or occasionally contain some amount In contrast to the anodes of the anisotropic carbon arranged in parallel, the anodes are mostly or substantially all of anisotropic carbon arranged in parallel. Moreover, contrary to the binders, fillers or other auxiliaries known in the art, the anodes are mostly anisotropic carbon arranged in parallel.

In a specific embodiment, the anode primarily comprises a meta-carbon, such as a meta-carbon microsphere. For example, the anode is mostly or completely metaphase carbon. In other words, the interphase carbon constitutes the majority of the anode, more than any other component. In particular, the anode can comprise at least 40%, at least 50%, at least 60%, at least 75%, at least 90%, at least 95% or at least 99% of the interphase carbon. In an exemplary embodiment, the anode is a substantially pure mesophase carbon. In other words, in contrast to coke or carbonized bitumen or an anode that occasionally contains some amount of interphase carbon, the anode is mostly or substantially all interphase carbon. Moreover, contrary to the binders, fillers or other auxiliaries known in the art, the anode is mostly interphase carbon.

In a specific embodiment, the anode for producing nitrogen trifluoride or fluorine comprises interphase carbon microspheres. Figure 1 depicts a meta-carbon microsphere comprising the following description: (a) a media phase sphere 100 and (b) a segment 100a passing through the media phase sphere. The media ball 100 can include two extremes 110, a thin layer direction trace 120, and a circular planar edge 130 of the media phase ball 100. Although the interphase carbon microspheres shown in FIG. 1 have a layered configuration, the interphase carbon microspheres made by other routes may have other forms. The intervening carbon microspheres may be spherical in shape or may have an elongated or irregular shape, for example.

The microspheres can have a spherical diameter of up to about 100 [mu]m (e.g., a diameter of about 1 to 100 [mu]m). In an exemplary embodiment, the intermediate carbon microspheres can have an average particle size ranging from about 1 to 5 microns in diameter. The intermediate carbon microspheres may have a high specific surface area of from 1,000 to 4,000 m ² /g, for example. Similarly, in another embodiment, the anode for producing nitrogen trifluoride or fluorine comprises needle coke and binder, and a particle size of 20 microns or more preferably less than 10 microns, above 1.6 g/cm ³ or more preferably higher than 1.7 g/cm ³ and less than 15% porosity or more preferably less than 10% porosity. The needle coke and binder can be molded into a desired shape.

Figure 4 depicts an X-ray diffraction (XRD) pattern for a suitable type of interphase carbon. The peak with the indicator mark on the top is from ZnO, which is added during the analysis when the calibration standard is added and is not part of the carbon anode. It turns out that there is no graphite peak in the XRD, indicating that the crystallized graphite does not exist. The XRD showed only one broad peak between 25 and 30°, indicating a graphene type carbon plane with insufficient strength. The absence of a peak at a lower angle indicates that the interphase carbon does not contain any crystalline or otherwise well-formed graphite or other crystal structure.

In another embodiment, the anode is comprised primarily of a parallel arrangement of anisotropic coke, such as needle coke, bonded with a suitable binder that results in a minimum amount of porosity. Aromatic asphalt, mesophase pitch and coal tar pitch are preferred binders, while oxygen-containing binders such as polyfuran methanol or phenolic resins are less preferred. In all cases, the anode was not graphitized.

Parallelly arranged anisotropic coke, including needle coke and mesocarbon or mesocarbon microspheres, can be produced in the following manner, for example, by heating asphaltene precursors such as coal tar, coal tar pitch, petrochemical Heavy oil, decant oil, pyrolysis residue, petrochemical asphalt, emulsion polymerized plastic, synthetic asphalt, A surfactant or a small molecule to cause a small molecule material to be converted into a polymer material by a repeated polycondensation reaction. Parallelly arranged anisotropic coke and mesophase carbon can also be produced synthetically from aromatic molecules such as naphthalene. For example, the precursor material can be heated at 200 to 600 ° C (depending on the precursor) to produce a "medium phase" carbon particle green body. The isotropic carbon can optionally be removed by solvent extraction to produce pure interphase carbon. The carbon green bodies are then molded or pressed into a desired shape and can then be baked to sinter and remove volatiles. There are various methods for producing mesocarbons, such as those taught and described in the world patents WO 2006/109497 and Korean Patent No. 10-2006-0138731.

Needle coke, metaphase carbon, metaphase carbon microspheres or other forms of parallel layered anisotropic coke can be used by any suitable supplier or distributor, for example, the company's CR Tech in Korea, the company in New York State MWI in Chester, Graftech International in Bama, Ohio, Y-Carbon in Bristol, Pennsylvania, and Timcal Graphite and Carbon in Bodhi, Switzerland. The company is located in Qinhuangdao Huarui Coal Chemicals Co., Ltd., Tangshan, China, the company's Asbury Carbons Co., Ltd. in Aberdeen, New Jersey, the company's MTI Co., Ltd. in Richmond, California, and the company's Linyi Gelon in Shandong, China. New Battery Materials Co., Ltd., Osaka Gas Chemicals Co., Ltd. in Osaka, Japan, SGL Carbon SE in Wibarden, Germany, and Sinosteel Chemical Co., Ltd. in Kaohsiung, Taiwan, The company produces or obtains from ROC, SEC Carbon, Inc., or other suppliers of anisotropic carbon in Nikko, Japan.

The parallel arrangement of anisotropic carbon is used to create the anode. Lift For example, the anode can be obtained by blending the parallel disposed anisotropic coke with a suitable asphalt binder or by interposing carbon microspheres. The anode can be molded using any suitable mold and molding techniques known in the art. In a specific embodiment, the coke/asphalt blend or interphase carbon microspheres are isostatically pressed (eg, cold isostatically pressed) to form the anode. Cold isostatic pressing (CIP) involves applying pressure to a mold at substantial room temperature (e.g., using a fluid at a temperature of about 20 to 25 ° C as a medium for applying pressure to the mold). The part may be optionally heated in the mold during forming or at the same time softened by the applied pressure. The part may or may not be heated or sintered after demolding. In an exemplary embodiment, the molded body is sintered. If a binder such as asphalt is used, the binder will soften and then melt, filling the voids between the coke particles before carbonization to bring the shaped bodies together. In contrast, due to the nature of the intermediate carbon microspheres, the intermediate carbon microspheres can be self-sintered at low temperatures (eg, about 400 to 600 ° C). Self-sintering means that the microspheres are pressed together and fused and sintered or heated, but no binder, resin or filler is required to mold and sinter the anode part. In a specific embodiment, the anode consists solely of molded and self-sintered meta-carbon microspheres. The parallel arrangement of anisotropic carbon or mesophase carbon can also be formed using other techniques known in the art including, but not limited to, isostatic pressing, uniaxial pressing or extrusion.

In another embodiment, at least one stabilizer or sintering aid, such as a phenolic resin, may be added for the purpose of achieving stabilization of the shaped parallel arranged anisotropic carbon without or causing oxidation. The stabilizer may contain oxygen or sulfur. For example, a small amount of stabilizer or sintering aid, such as a phenolic resin, can be used to introduce oxygen, which is responsible for oxygen when the shaped body is heated during the carbonization process. The anisotropic carbons arranged in parallel crosslink and impart deformation resistance. The anode may comprise 10% or less, 8% or less, 5% or less, 3% or less or 1% or less of a stabilizer or sintering aid.

In a preferred embodiment, the binder, pore filler or sintering aid comprises aromatic asphalt, aromatic synthetic asphalt or other known carbon precursors to facilitate the production of graphitized carbon upon heating.

The shaped green body can be arbitrarily exemplified by exposure to air at elevated temperatures, and oxidized to stabilize the physical shaped body and reduce or eliminate deformation upon subsequent heating. In other words, the green body can be oxidized by heating in air or an oxygen-containing gas. Conditions suitable for oxidizing a mesocarbon formed body are known in the art. In the literature, for example, "On the chemistry of the oxidative stabilization and carbonization of carbonaceous mesophase." Fuel. 2002 Nov; 81(16): 2061-70, edited by F. Fanjul, M. Granda, R. Santamaria, and R. Menendez. A number of different methods for the stabilization of interphase carbon articles by oxidation have been described.

The sintering treatment may also be carried out in a densification heat treatment, for example, at a temperature of about 500 to 1500 ° C, after that. The density or apparent density of the die cast anode can be a low density of between about 1.60 and 1.65 g/cm ³ . In a specific embodiment, the anode made of parallel-arranged anisotropic carbon (e.g., mesocarbon microbeads) preferably has a high density of about 1.7 g/cm ³ or higher. The anodes comprising parallel anisotropic carbons preferably also have a low porosity (e.g., less than 20% porosity, preferably less than 15% porosity, and more preferably, less than 10%). Porosity).

The anode can have electrolytic electricity as is commonly used in the art. The pool may be suitable for size and shape. For example, the flat and wide portion of the anode can be between about 1.5 to 2.5 inches long, about 6 to 10 inches wide, and about 1 to 3 inches thick. The flat and wide portion of the anode may be flat and/or may include other surface features including grooves, ridges, serrations and pyramids to improve surface area or other flat and wide portions of the anode for producing a wide geometric surface area. The features are known in the art, for example, as described in U.S. Patent Nos. 5,290,413 and 4,511,440. The anode can have any suitable active surface area. The shape and physical characteristics of the anode may be formed during the molding process or it may be machined using conventional assembly techniques at any time after formation of the green body.

The anode of the present invention is preferably ungraphitized. Graphitized carbon materials, including needle coke, mesocarbon microspheres, and conventional extruded carbon anodes, often baked after molding, extrusion or forming to remove volatile materials and sinter or bond loose carbon Material. This baking operation can take place at temperatures up to about 1300 °C. At higher temperatures, typically above 1500 ° C but depending on the type of carbon material, the carbon begins to form larger areas of graphite and the electrical resistance decreases. This is called graphitization. Many types of carbon objects are partially or completely graphitized. The anode used to produce NF ₃ and F ₂ is preferably not graphitized, as this can result in insufficient performance of the electrolytic cell (for example, graphite is attacked by fluorine products and also disintegrates due to inclusion of many different components in the electrolyte) .

Compared with conventional extruded anode, arranged in parallel comprises an anisotropic coke, needle coke comprising carbon and mesophase microspheres, the anode of the present invention provide many benefits, for example: (1) CF ₄ reduction forming, therefore, Provide higher purity of NF ₃ and F ₂ ; (2) shorter manufacturing time (for example, no additional separation step when producing F ₂ ); (3) less anode machining is required to create the anode product; 4) regarding the lower manufacturing cost of the anode, which in turn becomes lower NF ₃ and F ₂ production costs; (5) improved resistance to polarization; (6) ability to operate at higher current densities; (7) Reduced operating battery voltage.

By forming the anode using parallel anisotropic carbon, higher purity NF ₃ and F ₂ can be produced, and there is little or substantially less CF ₄ than conventional extruded anodes. For example, the process can be produced in less than 100 ppm (by volume), preferably less than 75 ppm (by volume), and more preferably less than 50 ppm (by volume) in pure NF ₃ or F ₂ . , and most preferably below 25ppm (by volume) of CF _4. Thus, 25 ppm corresponds to NF ₃ 25 molecules of CF ₄ per million molecules or 25 ml of CF ₄ per million ml of NF ₃ . The selectivity of the process for producing NF ₃ or F ₂ is preferably also high and may be 70% or higher, preferably 80% or higher, and more preferably 85% for NF ₃ or F ₂ . Or higher or even 90% or higher selectivity.

Carbon articles made from parallel anisotropic coke, including needle coke and mesocarbon microsphere anodes, may also exhibit improved wetting characteristics without the addition of conventional wetting aids. Conventional carbon anodes often because of its production and the electrolyte during the electrochemical production of NF ₃ or F ₂ species, such as fluorine, the result of interaction and the development of low energy surfaces. The effect of the anode surface being wetted by the electrolyte becomes insufficient, resulting in a higher battery operating voltage and an increased tendency to be polarized. For example, using known geometric surface area of the anode via three yuan KF-HF-NH ₄ F molten salt electrolyte, having a 40 wt% HF, by weight of the composition 18% NH ₄ F and 42 wt% KF, and at or near 130 after electrolysis ℃ NF ₃ production least 150 hours at 70mA / cm ² or more preferably a current density of 180mA / cm ² in. Upon removal from the melt and cooling to about room temperature, the anode can be washed with water without physically consuming the active surface and drying. The surface energy of the active surface can then be determined using known surface addition inks or labels ("Dyne").

The anode of the present invention was found to exhibit a surface energy of 65 dynes/cm or more after traversing at least 30% of the active surface at 70 mA/cm ² for more than 150 hours. In other words, the anode of the present invention comprising parallel arranged anisotropic carbon exhibits long lasting wettability without the need for a wetting agent. In contrast, conventional extruded anodes exhibit surface energies below this value, for example, often below 55 dynes/cm and require a wetting agent to improve wettability. For example, from Electrochemistry in the Preparation of Fluorine and its Compounds, P. Hough, "Fluorine Production and Use-An Ovewiew", edited by W. Childs and T. Fuchigami, The Electrochemical Society, 1997, it is known to add an additive to the carbon. To enhance the moisturizing effect. Similarly, U.S. Patent No. 7,608,235 uses MgF ₂ or AlF _{3 to be} added to a conventional carbon anode to improve the wetting effect. However, additives such as those described above add cost to the anodes and may contaminate the electrolyte and the anode manufacturing equipment.

It has been surprisingly found that, unlike other carbon shaped bodies, the parallel arrangement of anisotropic carbons forming such anodes, such as interphase carbon microspheres, resists the formation of low energy surfaces without the need for such moist additives, resulting in lower batteries. Operating voltage and ability to operate at higher current densities than conventional carbon anodes. Lower battery voltages result in reduced energy losses during the manufacture of NF ₃ or F ₂ , while increased current density enables a particular battery to produce more NF ₃ or F ₂ . Furthermore, the removal of conventional wetting aids from the anode composition reduces cost and contamination of the manufacturing process.

Other attempts have been made to improve conventional extruded carbon anode materials. US Application No. 2010/0193371 describes the use of a conductive diamond film on a glassy carbon. It is known from US Application No. 2010/0252425 to use a phase carbon as a filler or binder for a more desirable carbonaceous component having a specified X-ray diffraction pattern. It also implies that a high degree of porosity is desirable, and that the specified carbonaceous material requires a conductive diamond coating to perfectly function as an anode. The invention does not require an expensive diamond film. Instead, the present invention demonstrates that a suitably prepared parallel arrangement of anisotropic carbon material is beneficial as an anode material. The parallel arrangement of anisotropic carbon may exhibit low porosity, for example, less than 15% or less than 10% porosity. Furthermore, the parallel arrangement of the anisotropic carbon material of the present invention does not show the diffraction pattern of the perfectly formed graphite or other crystal phase which has been crystallized as specified in U.S. Application No. 2010/0252425. As discussed above, the parallel arrangement of anisotropic carbon materials of the present invention does not have a clear diffraction peak outside of the broad peak between 25 and 30°, indicating that the parallel arrangement of anisotropic carbon does not have any perfectly shaped graphite or Other crystal structures.

Electrolytic battery

In a specific embodiment, the present invention provides an electrolytic cell for producing nitrogen trifluoride or fluorine comprising an anode, a cathode and an electrolyte composition comprising anisotropic carbon (eg, mesocarbon microspheres) arranged in parallel. . The electrolysis cell is operated to produce nitrogen trifluoride or fluorine. The method of forming nitrogen trifluoride or fluorine includes electrolyzing an electrolyte, for example, using an electrolytic cell. Any suitable electrolytic cell known in the art can be selected by those of ordinary skill in the art.

For example, the electrolysis cell can include a container or housing that contains a wall that is inert to the electrolyte and that holds the electrolyte. The anode and cathode can be connected to a DC power source. For example, the electrode can be disposed in the container to be immersed in the electrolyte such that the electrodes become electrochemical anodes and cathodes when current is applied. When fluorine or nitrogen trifluoride is generated at the anode during the electrolysis reaction and hydrogen is generated at the cathode, a partition wall or a separation skirt may be provided in order to prevent mixing of fluorine or nitrogen trifluoride with hydrogen. Generally, the partition wall may be arranged vertically.

Any material can be used to construct the components of the battery as long as the materials are exposed to the corrosive conditions of the battery. Materials that can be used for the battery body and the separation skirt are iron, stainless steel, nickel or nickel alloys such as MONEL® and TEFLON®, as is known to those skilled in the art. The construction material of the cathode is not specifically limited as long as the cathode is made of materials which can be used for the purposes known to those skilled in the art, such as nickel, carbon steel and iron.

Figure 2 shows a schematic of one example of an electrolytic cell device that may be suitable for the production of nitrogen trifluoride or fluorine in accordance with the present invention. The electrolytic cell apparatus can include an electrolytic cell 25 having an electrolytic cell body 26, sides 51, 52, and an upper cover or cover 28. The battery 25 is divided into an anode compartment 17 and a cathode compartment 18 by a vertically disposed gas separation skirt 19 and a diaphragm 22. An anode 20 is disposed in the anode compartment 17, and a cathode 21 is disposed in the cathode compartment 18. The electrolyte 23 is placed on the electrolytic cell 25 and the liquid level 27 of the electrolyte 23 is higher than the height of the electrolyte 23 of the bottom surface 53 of the electrolytic cell 25. The liquid level of the electrolyte 23 can be measured by the liquid level indicator 31, and the liquid level 27 can be controlled to the high liquid level setting point 32 and the low liquid level setting point 33. Between, for example. Further, the composition of the electrolyte 23 can be sampled via the electrolyte sample crucible 41.

The electrolytic cell 25 may include feed tubes 12 and 16 for injecting a raw material or a component constituting the electrolyte 23. Typically, the feed tubes 12 and 16 are mounted to the cathode compartment 18. The anode compartment 17 can have an anode product discharge tube 11 for extracting a product gas mixture (e.g., NF ₃ or F ₂ ) from the electrolytic cell 25. The cathode compartment 18 may have a cathode product outlet pipe 13 for extracting gas from the electrolytic cell 25. The electrolytic cell 25 can include a temperature detector 30 and a temperature regulating device 29 to facilitate control of appropriate process parameters during electrolysis.

If necessary, the electrolysis unit of the present invention may additionally comprise other components, such as purge gas pipe connections in the anode and cathode compartments 17, 18. A source of purge gas, such as, for example, nitrogen, can be coupled to the anode compartment 17 and/or cathode compartment 18 (not shown) of the electrolytic cell 25 for cleaning the electrolytic cell 25 for safety to provide clogging. The blowing means of the tube, or the use of the introduction tube and the discharge tube, suitably function and other appliances.

When the battery 25 is operated, a gas containing nitrogen trifluoride or fluorine is generated at the anode 20 and hydrogen is generated at the cathode 21. When used to produce nitrogen trifluoride, the gas produced in the anode compartment 17 may contain nitrogen trifluoride (NF ₃ ), nitrogen (N ₂ ), and fluorine (F ₂ ), for example. When used to produce fluorine, the gas produced in the anode compartment 17 may contain fluorine (F ₂ ), for example. Further, HF may be arbitrarily present in the gas leaving both the anode compartment 17 and the cathode compartment 18.

3 shows an electrolytic cell 25 similar to that shown in FIG. 2 except that the battery 25 shown in FIG. 3 includes only one anode compartment 17 and one cathode compartment 18. Sectional drawing. The anode compartment 17 has an anode 20 and the cathode compartment 18 has a cathode 21. Similar components in Figures 2 and 3 are numbered the same.

The battery 25 shown in FIG. 3 is supplied to the anode 20 through the anode current wiring 14 and through the cathode current wiring 15 at a potential which can be raised or lowered within the range specified by the arithmetic unit or the control program of the electrolytic battery 25. A current is supplied to the current controller 39 of the cathode 21.

Although a particular electrolytic cell 25 has been described and illustrated herein, the battery 25 may still include any known or later developed battery design. For example, the battery type can be included in the ICI fluorine cell design described by Fluorine, The First Hundred Years, R. E. Banks, D. W. A. Sharp and J. C. Tatlows, Elsevier Sequoia, Netherlands, 1986.

Production of NF ₃ or F ₂

The electrolysis cell can have the potential to produce NF ₃ , F ₂ or both, and the processes are substantially similar. A few differences between the production of NF ₃ or F ₂ include the use of different electrolyte solutions and different operating conditions. Otherwise, the two processes are essentially the same. The cells are exchanged with each other, and the anodes used are both as described herein and are based on an anisotropic carbon of the same parallel arrangement. As particularly mentioned above, two processes have produced undesired byproduct CF _4. The only difference is that CF ₄ and F ₂ can be separated by distillation, while CF ₄ and NF ₃ are practically inseparable. In any case a two, preferably no production of CF _4, because then the need to further separate process step.

(a) Production of NF ₃

Nitrogen trifluoride can be produced by using the electrolysis apparatus of the present invention together with any known electrolytes which can be used to produce nitrogen trifluoride. For example, suitable electrolytes can include ternary electrolytes (eg, ammonium fluoride (NH ₄ F), potassium fluoride (KF), and HF-containing molten salts of hydrogen fluoride (HF)). Further, the molten salt electrolyte may also contain other additives such as cesium fluoride and lithium fluoride. In an exemplary embodiment, the Electrolyte composition may comprise from about 35 to 45 wt% HF, about 15 to 25 wt% NH ₄ F and from about 40 to 45 wt% KF. The concentration can be expressed as the angle of the molar % NH ₄ F and HF ratio. The HF ratio is defined by the following equation: HF ratio = (HF moles titrated to neutral pH) / (NH ₄ F (mole) + KF (mole)).

The HF ratio represents the ratio of solvent to salt in the electrolyte. In some embodiments utilizing the ternary electrolyte, it is preferably utilized at 14% by weight and 24% by weight, more preferably between 16% by weight and 21% by weight, most preferably between 17.5% by weight and Operating the electrolysis cell with a NH ₄ F concentration in the range between 19.5 wt%; and the HF ratio is preferably between 1.3 and 1.7, more preferably between 1.45 and 1.6, optimally between 1.5 Between 1.55. In other embodiments, the preferred concentration range can vary depending on operating conditions such as applied current and electrolyte temperature. We would like to select this concentration range for the balance between the high efficiency and safe operation of the electrolysis cell.

The invention is not limited to any of the specified electrolyte compositions, and any reference herein to, for example, the description of the ternary electrolyte is merely convenient. For any electrolyte salt may be used in the manufacture of NF ₃ substituents can join this description and included within the present invention.

The nitrogen trifluoride electrolysis process can be carried out under suitable conditions known in the art, including temperature and current density. For example, nitrogen trifluoride can be produced at a temperature of from about 100 to 140 ° C, preferably from about 120 to 130 ° C, and a current density of up to 250 mA/cm ² .

In the case of fluorine, the fluorine-producing electrolyte may include a binary electrolyte. For example, the binary electrolyte can include a melt of hydrogen fluoride (HF) of HF and KF. Further, the HF-containing molten salt electrolyte may also contain other additives such as ammonium fluoride, cesium fluoride, lithium fluoride, and the like.

The HF ratio can be similar to those described above to achieve a balance between high efficiency and safe operation of the electrolytic cell and can be defined as: HF ratio = (HF moles titrated to neutral pH) / (KF (mole) ).

The invention is not limited to any of the specified electrolyte compositions, and any reference herein to, for example, the description of the binary electrolyte is merely convenient. For any electrolyte salt may be used in the manufacture of F ₂ substituents can join this description and included within the present invention.

The fluorine electrolysis process can be carried out under suitable conditions known in the art, including temperature and current density. For example, fluorine can be produced at a temperature of about 80 to 90 ° C and a current density of up to 250 mA / cm ² .

Example Example 1 - Production of NF ₃ using a mesophase carbon anode

So having the composition 40 wt% HF, 19.5 wt% NH ₄ F and 40.5 wt.% KF ternary electrolyte in the electrolytic cell to produce 250mL laboratory NF _3. The cathode is carbon steel and the battery is equipped with a Cu/CuF ₂ reference electrode. The anode is an isostatically pressed mesocarbon microbead having an active area of 2.25 cm ² . The anode and cathode product gases are separated by a TEFLON® skirt that extends below the liquid line. The battery was operated at 130 °C. Electrolysis system using galvanostatic mode in accordance with the applied current density of 70mA / cm ² in. The anode gas system and the like are analyzed by a gas chromatograph after the battery reaches a steady state.

The anode gas contained 71 ppm CF ₄ based on pure NF ₃ . The selectivity for NF ₃ is 70.7%, as defined below: NF ₃ selectivity = (produced NF ₃ moles) / (produced NF ₃ moles + produced N ₂ moles).

After operating for more than 150 hours in accordance with the anode at 70 mA/cm ² , the anode was removed from the electrolyte, cooled to room temperature, washed with water without abrading the active surface, and ink by 70 dynes/cm. The liquid (high surface energy ink) thoroughly wets the surface by 50%, indicating that the surface energy is above this value. The remaining surface is wetted by an ink of 58 dynes/cm.

Comparative Example 1 - Conventional Anode

The electrolysis reaction described in Example 1 was repeated except that the anode was replaced with a conventional extruded carbon anode. The active anode area was maintained at 2.25 cm ² . The anode gas contained 341 ppm CF ₄ (based on pure NF ₃ ) and had a selectivity to NF ₃ of 89.9%. The anode was removed after more than 150 hours of operation and the same test as in Example 1 was performed, during which the anode was only wetted by 50 dynes/cm of ink without any higher surface energy ink.

Example 2 - Production of NF ₃ using a mesophase carbon anode

So having the composition 37.5 wt.% HF, 18.3 wt% NH ₄ F and 44.2 wt.% KF ternary electrolyte in an electrolytic cell to generate a laboratory 250mL NF _3. The cathode is carbon steel and the battery is equipped with a Cu/CuF ₂ reference electrode. The anode is an isostatically pressed mesocarbon microbead having an active area of 2.25 cm ² . The anode and cathode product gases are separated by a TEFLON® skirt that extends below the liquid line. The battery was operated at 139 °C. The electrolysis system was carried out in a constant current mode using an applied current density of 100 mA/cm ² . The anode gas system and the like are analyzed by a gas chromatograph after the battery reaches a steady state.

The anode gas contained 20 ppm CF ₄ based on pure NF ₃ . The selectivity for NF ₃ was 77.6%.

Comparative Example 2 - Conventional Anode

The electrolysis reaction described in Example 2 was repeated except that the anode was replaced with a conventional extruded carbon anode. The active anode area was maintained at 2.25 cm ² . The anode gas contained 70 ppm CF ₄ (based on pure NF ₃ ) and had a selectivity to NF ₃ of 87.0%.

Example 3A - Production of NF ₃ using a low density mesocarbon anode

So having HF, NH ₄ F and ternary electrolyte KF in 250mL laboratory electrolytic cell to generate NF _3. The cathode is carbon steel and the battery is equipped with a Cu/CuF ₂ reference electrode. The anode has an active area of 2.25 cm ² and a low density (1.60 g/cm ³ ) of isostatically pressed mesocarbon microbeads. The anode and cathode product gases are separated by a Teflon skirt that extends below the liquid line. The battery was operated at 130 °C. The electrolysis system was carried out in a constant current mode using an applied current density of 70 mA/cm ² . The anode gas system and the like are analyzed by a gas chromatograph after the battery reaches a steady state. The anode gas contained 61 ppm CF ₄ based on pure NF ₃ . The selectivity for NF ₃ was 82.3%. The anode was evaluated for surface energy in the manner described in Example 1, and wetted by about 40% of the surface by 70 dynes/cm of ink, and the remaining area was wetted by ink of 58 dynes/cm. .

Example 3B - Production of NF ₃ using high density mesophase carbon anodes

In addition to utilizing high density ( 1.70 g/cm ³ ) The electrolytic reaction described in Example 3A was repeated except that the anode was replaced by isostatically pressed mesocarbon microbeads. The anode gas contained <25 ppm CF ₄ (based on pure NF ₃ ) and had a selectivity to NF ₃ of 84.7%. The anode was evaluated for surface energy in the manner described in Example 1, and wetted by about 40% of the surface by 70 dynes/cm of ink, and the remaining area was wetted by ink of 58 dynes/cm. .

Comparative Example 3A - Conventional Anode

The electrolysis reaction described in Example 3A was repeated except that the anode was replaced with a conventional extruded carbon anode. The anode gas contained 341 ppm CF ₄ (based on pure NF ₃ ) and had a selectivity to NF ₃ of 89.9%. The anode was evaluated for surface energy in the manner described in Example 1 and wetted with 50 dyne/cm of ink but without any higher surface energy ink.

Comparative Example 3B - Conventional Anode Pressed by Isobaric Pressure

The electrolysis reaction described in Example 3A was repeated except that the anode was replaced by an isostatically pressed non-intermediate carbon anode. The composition of this anode is similar to conventional extruded carbon (i.e., based on carbonized coke and asphalt rather than interphase carbon). The anode gas contained 212 ppm CF ₄ (based on pure NF ₃ ) and had a selectivity to NF ₃ of 88.3%. The anode was evaluated for surface energy in the manner described in Example 1 and was wetted by 48 dyne/cm of ink but without any higher surface energy ink.

Example 4A - Production of NF ₃ using an anode based on needle coke

The electrolysis reaction described in Example 1 was repeated using an anode mainly comprising needle coke and an asphalt-based binder. The anode had an apparent density of 1.75 g/cm ³ and a total porosity of 15%. The anode was not graphitized. The battery was operated at a current density of 70 mA/cm ² . The battery temperature was 130 °C. The anode potential during the test was 88% selective for NF ₃ compared to 5.15 V for the Cu/CuF ₂ reference, and the CF ₄ content of the NF ₃ product was 30 ppm.

Example 4B - Production of NF ₃ using a needle-based coke-based anode at high current densities

The electrolysis reaction described in Example 4 was repeated at a current density of 178 mA/cm ² . The battery temperature was 140 °C. The anode potential during the test was 8.8% for the Cu/CuF ₂ reference, 88% for NF ₃ , and the CF ₄ content for the NF ₃ product was 20 ppm.

These results are summarized in the table below, where IP = isostatically pressed, MCMB = mesocarbon microspheres, LD = low density and HD = high density.

Comparative Example 4 - Production of NF ₃ using an anode based on graphitized needle coke

The electrolysis reaction of Example 4B was repeated using the same composition as in Example 4B except that the graphitized anode was heated by heating to a temperature higher than 2000 °C. The selectivity and CF ₄ concentration are the same, but the anode is not stable with an anode potential that varies between 6 and 7V.

Example 5 - Production of F ₂ using a mesophase carbon anode

So having 40 wt.% HF and 60 wt% KF binary electrolyte in the electrolytic cell to produce 250mL laboratory F _2. The cathode is carbon steel and the battery is equipped with a Cu/CuF ₂ reference electrode. The anode is an isostatically pressed mesocarbon microbead having an active area of 2.25 cm ² . The anode and cathode product gases are separated by a TEFLON® skirt that extends below the liquid line. The battery was operated at 88 °C. The electrolysis system was carried out in a constant current mode using an applied current density of 80 mA/cm ² . The battery operates stably, discharges fluorine gas, and has a battery voltage of 6.4 volts.

Comparative Example 5 - Production of F ₂ with a conventional anode

The electrolysis reaction described in Example 5 was repeated except that the anode was replaced with a conventional extruded carbon anode. The battery operates steadily, venting fluorine gas, but with a higher battery voltage of 7.0 volts.

Example 6 - Production of F ₂ using a mesophase carbon anode at high current density

The electrolysis reaction described in Example 5 was repeated except that a smaller battery containing 25 mL of an electrolyte was used. The isostatically pressed mesocarbon anode has an active area of 0.5 cm ² . The battery was operated at a current density of 225 mA/cm ² . The anode discharges fluorine gas and operates stably at a battery voltage of 6.8 volts.

Comparative Example 6 - Production of F ₂ by conventional anode at high current density

The electrolysis reaction described in Example 6 was repeated except that the anode was a conventionally extruded carbon anode. The battery in the same 225mA / cm ² at a current density operation. The battery vents fluorine gas but has an unstable battery voltage of 7.7 to 8.5 volts.

Although the specific embodiments and examples have been illustrated and described above, the invention is not intended to be limited to the details shown. Instead, various modifications may be made without departing from the spirit and scope of the invention. It is expressly intended that, for example, all ranges broadly recited in this document include all narrow ranges that fall within the scope thereof and fall within the broader scope. Furthermore, features of a particular embodiment can be incorporated in another specific embodiment. All publications, patents, and other documents referred to in this document are hereby incorporated by reference in their entirety for all purposes in the extent of the disclosure of the disclosure.

100‧‧‧Intermediate ball

100a‧‧‧ fragment of the media ball

110‧‧‧Extreme

120‧‧‧ Traces in the direction of the thin layer

130‧‧‧round edge

Claims (32)

A method of producing nitrogen trifluoride or fluorine, comprising: electrolyzing an electrolyte to obtain nitrogen trifluoride or fluorine by using an electrolytic anode comprising anisotropic carbon disposed mainly in parallel. The method of claim 1, wherein the parallel arrangement of anisotropic carbon comprises needle coke. The method of claim 2, wherein the anode comprises: at least 60% needle coke; and optionally, 0 to 40% binder. The method of claim 3, wherein the anode comprises the binder and the binder is asphalt. The method of claim 2, wherein the anode comprises the binder, and the needle coke and the binder are pressed to form a shaped body. The method of claim 2, wherein the anode comprises the binder, and the needle coke and binder have an average particle size of less than 25 microns. The method of claim 2, wherein the needle coke is not graphitized. The method of claim 1, wherein the parallel arrangement of anisotropic carbon comprises interphase carbon microspheres. The method of claim 8, wherein the intermediate carbon microspheres are isostatically pressed mesocarbon microbeads. The method of claim 8, wherein the intermediate carbon microspheres have an average particle size of from about 1 to 5 microns. The method of claim 8, wherein the intermediate carbon microspheres are not graphitized. The method of claim 1, wherein the parallel disposed anisotropic carbon comprises a metaphase carbon, and the anode comprises: at least 40% mesophase carbon; and optionally, up to 10% of a stabilizer. The method of claim 1, wherein the anode has a density of 1.7 g/cm ³ or higher. The method of claim 1, wherein the anode is composed of a mold and self-sintered mesocarbon microbeads and optionally a sintering aid. The method of claim 1, wherein the anode has an active area of up to about 70,000 cm ² . The method of claim 1, wherein the method produces less than 100 ppm of CF ₄ in pure nitrogen trifluoride or fluorine. The method of claim 1, wherein the method produces less than 25 ppm of CF ₄ in pure nitrogen trifluoride or fluorine. The method of claim 1, wherein the method produces nitrogen trifluoride or fluorine having a selectivity of 70% or higher. The method of claim 1, wherein the method produces nitrogen trifluoride or fluorine having a selectivity of 80% or higher. The method of claim 1, wherein the nitrogen trifluoride is produced and the electrolyte comprises a ternary electrolyte composition of HF, NH ₄ F and KF. The method of claim 20, wherein the ternary electrolyte composition comprises 35 to 45% by weight of HF, 15 to 25% by weight of NH ₄ F, and 40 to 45% by weight of KF. The method of claim 1, wherein the fluorine is produced and the electrolyte is a binary electrolyte composition comprising HF and KF. The method of claim 1, wherein the nitrogen trifluoride is produced and the electrolyte is electrolyzed at a temperature of about 120 to 140 °C. The method of claim 1, wherein the fluorine is produced and the electrolyte is electrolyzed at a temperature of about 80 to 90 °C. The method of claim 1, wherein the method is operated at a current density of about 70 to 250 mA/cm ² . The method of claim 1, wherein the nitrogen trifluoride is produced and the method is operated at a current density of about 100 to 250 mA/cm ² . The method of claim 1, wherein the fluorine is produced and the method is operated at a current density of about 120 to 250 mA/cm ² . An electrolytic cell for producing nitrogen trifluoride or fluorine, comprising: an anode comprising anisotropic carbon arranged in parallel; a cathode; and an electrolyte composition comprising HF, optionally KF and optionally NH ₄ F, wherein the electrolysis cell is operated to produce nitrogen trifluoride or fluorine. An electrolytic cell according to claim 28, wherein the anode is composed of a mesophase carbon microsphere which is isostatically pressed from sintering and optionally a sintering aid. An electrolytic cell according to claim 28, wherein the anode is composed of needle coke and an asphalt binder. An electrolytic cell according to claim 30, wherein the asphalt binder and the needle coke are first blended and then ground prior to pressing. An electrolytic cell according to claim 28, wherein the anode exhibits a long-lasting wettability without the addition of a wetting agent.