Methods of making fluoromethane from chloromethane and fluoromethane compositions

Abstract

A method for synthesizing fluoromethane from chloromethane and at least a 150% stoichiometric excess of hydrogen fluoride is provided, as is a fluoromethane product composition. The method includes contacting the reactants in gas phase in a reactor in the substantial absence of chromium but optionally in the presence of solid support particles; controlling conditions in the reactor to foster 3-30% reaction conversion of the reactants to form a reactor output stream; separating unreacted chloromethane and hydrogen fluoride out from the reactor output stream to form a recycle stream, with at least a portion of the remaining components of the reactor output stream forming a crude intermediate stream comprising fluoromethane product and hydrogen chloride by-product; recycling at least a portion of the recycle stream back to the reactor; removing by-product hydrogen chloride from the crude intermediate stream to form a fluoromethane product stream; and optionally purifying the fluoromethane product stream.

Description

[0001] METHODS OF MAKING FLUOROMETHANE FROM CHLOROMETHANE

[0002] AND FLUOROMETHANE COMPOSITIONS

[0003] FIELD

[0004] The invention relates to methods useful for making fluoromethane from chloromethane, as well as relatively pure fluoromethane compositions made by such methods.

[0005] BACKGROUND

[0006] Various publications ubiquitously teach catalytic fluorination of reactants to form fluoromethane. Some such select publications are listed below.

[0007] U.S. Patent No. 3,258,500 discloses fluorination substitution reactions on C1-C8 halogenated aliphatic hydrocarbons in the presence of an activated anhydrous chromium- containing fluorination catalyst.

[0008] U.S. Patent No. 4,139,568 discloses fluoromethane synthesized from methanol and hydrogen fluoride in the presence of steam and a catalyst.

[0009] PCT Publication No. WO 2006 / 030677 discloses contacting chloromethane reactant with a zeolite prior to reacting it with hydrogen fluoride in the presence of a fluorination catalyst.

[0010] Japanese Published Patent Application No. JP 2017036227 discloses fluoromethane synthesis from monohalomethane (non-fluoro-halomethanes) and hydrogen fluoride in the presence of a chromium fluorination catalyst. Similar publications include Japanese Patent Laid- Open Nos. 60-013726, 60-008234, 60-008235, and 60-016943.

[0011] Chinese Patent No. CN 106542959 discloses reaction of chloromethane with hydrogen fluoride in the gas phase in the presence of a high activity (chromium plus heavy metal) fluorination catalyst.

[0012] Chinese Patent No. CN 110283041 discloses fluoromethane synthesis from chloromethane and hydrogen fluoride in the presence of a chromium-containing catalyst.

[0013] Chinese Published Patent Application No. CN 110606797 discloses high conversion monofluoromethane synthesis from deeply dehydrated reactants chloromethane and hydrogen fluoride, as well as a deeply dehydrated oxygen-containing gas, in the presence of a chromium- containing catalyst.

[0014] In addition, Chinese Published Patent Application No. CN 103910600 discloses activated carbon as a mechanism for adsorptively removing impurities in crude fluoromethane product, while trying to attain very highly pure fluoromethane compositions.

[0015] It is extremely rare for fluoromethane synthesis reactions to be uncatalyzed. For instance, U.S. Patent Application Publication No. 2023 / 159415 discloses fluoromethane synthesis from various gas phase reactants (including chloromethane from one list and hydrogen fluoride from another) without a catalyst but promoted by causing electrical discharge, such as through the use of an externally applied electric voltage. Other similar disclosures include PCT Publication WO 2022 / 255120, Japanese Published Patent Application No.JP 2022184047, and PCT Publication WO 2021 / 241372, for example.

[0016] However, no publications have been found that disclose synthesis of fluoromethane without the presence of chromium and / or other catalytic metals, and no publications have been found that disclose uncatalyzed yields / selectivities that approach those of catalyzed systems.

[0017] SUMMARY

[0018] This disclosure of fluoromethane synthesis methods herein includes descriptions of process conditions / regimes which show a remarkable enhanced conversion in the substantial absence of chromium and / or other catalytic metals (such as iron). Indeed, by forgoing a traditional (chromium-containing) metal catalyst, one or more of the following benefits can be realized:

[0019] • Catalysts typically have a finite lifetime after which they must be either regenerated or replaced;

[0020] • Catalysts (precursors) require activation, which procedures can be quite complicated to achieve and maintain high catalytic activity

[0021] • With catalysts dynamically aging while in use, the reaction effluent profile can change overtime, sometimes dramatically causing the downstream purification and recycle streams to change over time, which can adversely affect product quality and plant operations;

[0022] • No need to have a reliable catalyst supply, nor the cost of buying or manufacturing added to the overall cost of the finished product;

[0023] • With most fluorination catalysts being based on transition metals, multiple by-product formation, especially at higher temperatures, can directly affect the purity of the final product and can require more elaborate purification schemes, thus increasing product cost; and

[0024] • A non-catalyzed process can allow for the more consistent and reliable reaction effluent and final product.

[0025] It has been unexpectedly found that commercially acceptable conversions of fluoromethane can be achieved from chloromethane and hydrogen fluoride reactants in the absence of chromium and / or other catalytic metals, and regardless of the presence or absence of solid particles (which are usually used as catalyst support materials and / or which are porous, believed to be functioning as reaction promoters, instead of chemical catalysts).

[0026] DETAILED DESCRIPTION

[0027] The term “comprising” as used herein may also encompass the phrases “consisting of’ and “consisting essentially of.”

[0028] Methods

[0029] An initial step in a method for synthesis of fluoromethane includes contacting the reactants in a reactor. In this case, the reactants can comprise (or consist essentially of) chloromethane (a.k.a. methyl chloride, HCC-40, and / or R-40) and hydrogen fluoride (a.k.a., HF; typically anhydrous, or “aHF”). Advantageously, both reactants can be introduced into the reactor in a gas phase, or, if introduced in other form such as liquid, can at least be converted into gases at or approaching reaction conditions.

[0030] To drive the reaction, it has been found that a stoichiometric (molar) excess of hydrogen fluoride reactant may be needed, relative to chloromethane reactant. In various embodiments, there can be at least a 100% stoichiometric excess, e.g., at least a 150% stoichiometric excess, at least a 200% stoichiometric excess, at least a 250% stoichiometric excess, at least a 300% stoichiometric excess, at least a 350% stoichiometric excess, at least a 400% stoichiometric excess, at least a 450% stoichiometric excess, at least a 500% stoichiometric excess, at least a 550% stoichiometric excess, at least a 600% stoichiometric excess, at least a 700% stoichiometric excess, at least a 800% stoichiometric excess, at least a 900% stoichiometric excess, or at least a 1000% stoichiometric excess of HF, relative to CH3CI. Because a 1:1 molar ratio of HF:CH3C1 constitutes stoichiometry in the fluoromethane formation reaction, a 50% stoichiometric excess of HF should be understood to correspond to a 1.5:1 molar ratio of HF:CH3C1, and a 100% stoichiometric excess of HF should be understood to correspond to a 2:1 molar ratio of HFrCHgCl, for instance. Exemplary ranges of stoichiometric (molar) excess of hydrogen fluoride reactant, relative to chloromethane reactant, may include from 100% to 4900%, from 100% to 3900%, from 100% to 3400%, from 100% to 2900%, from 100% to 2400%, from 100% to 2150%, from 100% to 1900%, from 100% to 1650%, from 100% to 1400%, from 100% to 1200%, from 100% to 1000%, from 100% to 800%, from 100% to 600%, from 100% to 400%, from 150% to 4900%, from 150% to 3900%, from 150% to 3400%, from 150% to 2900%, from 150% to 2400%, from 150% to 2150%, from 150% to 1900%, from 150% to 1650%, from 150% to 1400%, from 150% to 1200%, from 150% to 1000%, from 150% to 800%, from 150% to 600%, from 150% to 400%, from 200% to 4900%, from 200% to 3900%, from 200% to 3400%, from 200% to 2900%, from 200% to 2400%, from 200% to 2150%, from 200% to 1900%, from 200% to 1650%, from 200% to 1400%, from 200% to 1200%, from 200% to 1000%, from 200% to 800%, from 200% to 600%, from 200% to 400%, from 300% to 4900%, from 300% to 3900%, from 300% to 3400%, from 300% to 2900%, from 300% to 2400%, from 300% to 2150%, from 300% to 1900%, from 300% to 1650%, from 300% to 1400%, from 300% to 1200%, from 300% to 1000%, from 300% to 800%, from 300% to 600%, from 300% to 400%, from 400% to 4900%, from 400% to 3900%, from 400% to 3400%, from 400% to 2900%, from 400% to 2400%, from 400% to 2150%, from 400% to 1900%, from 400% to 1650%, from 400% to 1400%, from 400% to 1200%, from 400% to 1000%, from 400% to 800%, from 400% to 600%, from 500% to 4900%, from 500% to 3900%, from 500% to 3400%, from 500% to 2900%, from 500% to 2400%, from 500% to 2150%, from 500% to 1900%, from 500% to 1650%, from 500% to 1400%, from 500% to 1200%, from 500% to 1000%, from 500% to 800%, from 500% to 600%, from 600% to 4900%, from 600% to 3900%, from 600% to 3400%, from 600% to 2900%, from 600% to 2400%, from 600% to 2150%, from 600% to 1900%, from 600% to 1650%, from 600% to 1400%, from 600% to 1200%, from 600% to 1000%, from 600% to 800%, from 700% to 4900%, from 700% to 3900%, from 700% to 3400%, from 700% to 2900%, from 700% to 2400%, from 700% to 2150%, from 700% to 1900%, from 700% to 1650%, from 700% to 1400%, from 700% to 1200%, from 700% to 1000%, from 700% to 800%, from 800% to 4900%, from 800% to 3900%, from 800% to 3400%, from 800% to 2900%, from 800% to 2400%, from 800% to 2150%, from 800% to 1900%, from 800% to 1650%, from 800% to 1400%, from 800% to 1200%, from 800% to 1000%, from 900% to 4900%, from 900% to 3900%, from 900% to 3400%, from 900% to 2900%, from 900% to 2400%, from 900% to 2150%, from 900% to 1900%, from 900% to 1650%, from 900% to 1400%, from 900% to 1200%, or from 900% to 1000%; in particular from 150% to 3400%, from 200% to 2900%, from 300% to 2400%, from 400% to 1900%, or from 500% to 1400%.

[0031] In many embodiments, it can be beneficial to specifically not comprise a monofunctional CH3R reactant other than chloromethane (R = Cl), such as but not necessarily limited to bromomethane (R = Br), iodomethane (R = I), methanol (R = OH), alkyl ethers (R = an oxyalkyl moiety), and the like, and combinations thereof.

[0032] The step of contacting the reactants in a reactor can occur, and can enable the reaction thereof to occur, in the substantial absence of chromium and / or other metals (particularly those known to have catalytic activity for the chloromethane to fluoromethane chemical reaction), nonlimiting examples of other metals including iron, zinc, nickel, cobalt, molybdenum, tungsten, osmium, indium, antimony, gallium arsenic, tin, and combinations thereof; in particular chromium, iron, or both. With regard to chromium and / or other metals, a “substantial absence” can indicate no intentionally added chromium and / or other metals. Additionally or alternatively, with regard to chromium and / or other metals, a “substantial absence” can indicate less than 500 wppm, less than 300 wppm, less than 200 wppm, less than 100 wppm, less than 75 wppm, less than 50 wppm, less than 40 wppm, less than 30 wppm, less than 20 wppm, less than 10 wppm, or no measurable chromium and / or other metal content; in particular less than 100 wppm, less than 50 wppm, or less than 10 wppm. Thus, in particular embodiments, the contacting can occur in the substantial absence (e.g., less than 100 wppm, less than 50 wppm, or less than 10 wppm) of chromium, in the substantial absence (e.g., less than 500 wppm, less than 100 wppm, less than 50 wppm, or less than 10 wppm) of iron, or in the substantial absence (e.g., less than 500 wppm combined, less than 100 wppm combined, less than 50 wppm combined, or less than 20 wppm combined) of chromium and iron.

[0033] Chromium and / or other metal content can be measured by any number of methods, e.g., x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray (EDX) spectroscopy (such as performed in an electron microscope and / or in an x-ray fluorescence, or XRF, spectroscope), Auger electron spectroscopy (AES), or UV-Vis spectrophotometry; in particular by XPS spectroscopy.

[0034] Without being bound by theory, it is therefore believed that the fluoromethane reaction disclosed herein, in the substantial absence of notably catalytic metals, can be considered a (chemically) non-catalytic reaction (and thus the method(s) according to the disclosure can be considered (chemically) non-catalytic method(s)).

[0035] The step of contacting the reactants in a reactor can occur, and can enable the reaction thereof to occur, whether in an empty reactor or in the presence of solid particles. Advantageously, when present, those solid particles can be porous, in some cases highly porous. Without being bound by theory, the porosity in the solid particles may act as a promoter (in a way different than that of a metal catalyst such as based on chromium) for the halogen exchange reaction to form fluoromethane. In such porous embodiments, the solid particles can have a BET surface area of at least 5 m2 / g, at least 10 m2 / g, at least 25 m2 / g, at least 50 m2 / g, at least 75 m2 / g, at least 100 m2 / g, at least 200 m2 / g, at least 300 m2 / g, at least 400 m2 / g, at least 500 m2 / g, at least 600 m2 / g, at least 700 m2 / g, at least 800 m2 / g, at least 900 m2 / g, or at least 1000 m2 / g, with maxima (if necessary) as high as 10000 m2 / g, as high as 5000 m2 / g, or as high as 3500 m2 / g, depending on the particular physico-chemical nature of the porous particles.

[0036] Additionally or alternatively, also advantageously when present, the solid particles can be made from support materials upon which surfaces catalytic metals may sometimes be deposited / associated (but on which they are typically not deposited / associated - hence the suggestion herein that this reaction is believed to be non-catalytic). Non-limiting examples of such solid support particles can include, but are not necessarily limited to, alumina, activated alumina, silica, activated carbon, aluminosilicates, borosilicates, aluminoborates, aluminophosphates, silicophosphates, silicoaluminophosphates, zeolites, alkali (e.g., sodium, potassium, lithium, or combinations thereof; in particular sodium and / or potassium) oxides, alkaline earth (e.g., magnesium, calcium, barium, beryllium, or combinations thereof; in particular magnesium, calcium, and / or barium) oxides, carbonates, or combinations thereof. Such solid (support) particles may include extrudates, as well as other configurations / shapes known to those in the particulate arts. As mentioned above, these solid particle surfaces may not comprise substantial amounts of certain metals (such as those known to be catalytic for this reaction, namely chromium but optionally others as well).

[0037] Due to the presence of the solid particles in an otherwise gas phase reaction system, when particles are present, the reactor can be a fixed bed reactor, in which one or more beds of (porous) particles can be pre-packed over and / or through which the gas phase reactants are flowed (e.g., to promote the reaction). In alternative particle-containing embodiments, other reactor designs can include, but are not necessarily limited to, fluidized bed reactors, ebullating bed reactors, trickle bed reactors, and the like, each of which may comprise a single bed or multiple beds of the solid particles (or which reactor can comprise a combination of different beds operating as distinct types of reactors). In embodiments where particles are not present, a simple gas phase reactor design can be employed.

[0038] If desired and / or necessary in order to create a fluidization reaction zone, whether or not in particle-containing environments, an additional diluent gas may be included during addition of the (gas phase) reactants. Such diluent gas, when present, may comprise or be nitrogen, air, carbon dioxide, carbon monoxide, helium, neon, argon, krypton, xenon, or combinations thereof; in particular comprising nitrogen, optionally including a noble gas. However, in some embodiments, it may be specifically desired not to include a diluent gas.

[0039] The method can also advantageously include a step of controlling conditions in the reactor to foster reaction of the reactants (whether or not in the presence of the solid support particles, inter alia) to form a reactor output stream. For instance, the conditions in the reactor can advantageously comprise substantially no electrical discharge and / or no intentionally applied external voltage. Thus, unlike the disclosure of non-catalytic chloromethane-to-fluoromethane reaction in U.S. Patent Application No. 2023 / 0159415, the method(s) according to this disclosure can include control of the reactor conditions without electrical discharge and / or intentionally applied external voltage, and indeed in the absence of plasmas in general. It should be understood that the phrase “no intentionally applied external voltage,” as used herein, was meant to refer to intentional application of an external voltage to a reaction zone of a reactor, for example (as disclosed in U.S. Patent Application No. 2023 / 0159415, which can lead to electrical discharge of the gas to promote reaction), and was not meant to reference the application of an external voltage to enable use of electrically-powered equipment to control flow, temperature, pressure, etc., in a reaction zone of a reactor.

[0040] Another of the controlled conditions can include the reactant (molar) conversion, which can be at least 3% and no more than 30% (e.g, at least 3% and no more than 25%, at least 3% and no more than 23%>, at least 3% and no more than 20%, at least 3% and no more than 18%, at least 3% and no more than 16%, at least 3% and no more than 14%, at least 3% and no more than 12%, at least 3% and no more than 10%, at least 5% and no more than 30%, at least 5% and no more than 25%, at least 5% and no more than 23%, at least 5% and no more than 20%, at least 5% and no more than 18%, at least 5% and no more than 16%, at least 5% and no more than 14%, at least 5% and no more than 12%, at least 5% and no more than 10%, at least 7% and no more than 30%, at least 7% and no more than 23%, at least 7% and no more than 25%, at least 7% and no more than 20%, at least 7% and no more than 18%, at least 7% and no more than 16%, at least 7% and no more than 14%, at least 7% and no more than 12%, at least 7% and no more than 10%, at least 8% and no more than 30%, at least 8% and no more than 25%, at least 8% and no more than 23%, at least 8% and no more than 20%, at least 8% and no more than 18%, at least 8% and no more than 16%, at least 8% and no more than 14%, at least 8% and no more than 12%, at least 8% and no more than 10%, at least 9% and no more than 30%, at least 9% and no more than 25%, at least 9% and no more than 23%, at least 9% and no more than 20%, at least 9% and no more than 18%, at least 9% and no more than 16%, at least 9% and no more than 14%, at least 9% and no more than 12%, at least 9% and no more than 10%, at least 10% and no more than 30%, at least 10% and no more than 25%, at least 10% and no more than 23%, at least 10% and no more than 20%, at least 10% and no more than 18%, at least 10% and no more than 16%, at least 10% and no more than 14%, or at least 10% and no more than 12%; in particular at least 3% and no more than 30%, at least 5% and no more than 25%, at least 7% and no more than 23%, or at least 9% and no more than 20%).

[0041] Given the incomplete conversion, the reactor output stream can obviously comprise or consist essentially of unreacted reactants chloromethane and hydrogen fluoride, as well as fluoromethane product and hydrogen chloride by-product, and optionally any impurities included in the reactants that cannot be converted under the reaction conditions to form fluoromethane product and / or hydrogen chloride by-product (and / or, if convertible to some other impurity under the reaction conditions, then optionally additionally such reacted impurities).

[0042] In various embodiments, the conditions in the reactor can be controlled to comprise one, some, or all of the following: a reactor temperature from about 200°C to about 550°C (e.g, from about 200°C to about 500°C, from about 200°C to about 450°C, from about 200°C to about 400°C, from about 200°C to about 350°C, from about 200°C to about 300°C, from about 250°C to about 550°C, from about 250°C to about 500°C, from about 250°C to about 450°C, from about 250°C to about 400°C, from about 250°C to about 350°C, from about 250°C to about 300°C, from about 280°C to about 550°C, from about 280°C to about 500°C, from about 280°C to about 450°C, from about 280°C to about 400°C, from about 280°C to about 350°C, from about 280°C to about 300°C, from about 300°C to about 550°C, from about 300°C to about 500°C, from about 300°C to about 450°C, from about 300°C to about 400°C, from about 300°C to about 350°C; in particular from about 200°C to about 550°C, from about 250°C to about 400°C, or from about 280°C to about 450°C); a reactor pressure from about 10 psia to about 300 psia (e.g., from about 10 psia to about 270 psia from about 10 psia to about 240 psia, from about 10 psia to about 200 psia, from about 10 psia to about 180 psia, from about 10 psia to about 160 psia, from about 10 psia to about 140 psia, from about 10 psia to about 120 psia, from about 10 psia to about 100 psia, from about 10 psia to about 80 psia, from about 10 psia to about 60 psia, from about 10 psia to about 50 psia, from about 10 psia to about 40 psia, from about 15 psia to about 300 psia, from about 15 psia to about 270 psia, from about 15 psia to about 240 psia, from about 15 psia to about 200 psia, from about 15 psia to about 180 psia, from about 15 psia to about 160 psia, from about 15 psia to about 140 psia, from about 15 psia to about 120 psia, from about 15 psia to about 100 psia, from about 15 psia to about 80 psia, from about 15 psia to about 60 psia, from about 15 psia to about 50 psia, from about 15 psia to about 40 psia, from about 20 psia to about 300 psia, from about 20 psia to about 270 psia, from about 20 psia to about 240 psia, from about 20 psia to about 200 psia, from about 20 psia to about 180 psia, from about 20 psia to about 160 psia, from about 20 psia to about 140 psia, from about 20 psia to about 120 psia, from about 20 psia to about 100 psia, from about 20 psia to about 80 psia, from about 20 psia to about 60 psia, from about 20 psia to about 50 psia, from about 20 psia to about 40 psia, from about 25 psia to about 300 psia, from about 25 psia to about 270 psia, from about 25 psia to about 240 psia, from about 25 psia to about 200 psia, from about 25 psia to about 180 psia, from about 25 psia to about 160 psia, from about 25 psia to about 140 psia, from about 25 psia to about 120 psia, from about 25 psia to about 250 psia, from about 25 psia to about 80 psia, from about 25 psia to about 60 psia, from about 25 psia to about 50 psia, from about 25 psia to about 40 psia, from about 30 psia to about 300 psia, from about 30 psia to about 270 psia, from about 30 psia to about 240 psia, from about 30 psia to about 200 psia, from about 30 psia to about 180 psia, from about 30 psia to about 160 psia, from about 30 psia to about 140 psia, from about 30 psia to about 120 psia, from about 30 psia to about 300 psia, from about 30 psia to about 80 psia, from about 30 psia to about 60 psia, from about 30 psia to about 50 psia, or from about 30 psia to about 40 psia; in particular from about 10 psia to about 300 psia, from about 15 psia to about 270 psia, from about 20 psia to about 240 psia, or from about 30 psia to about 300 psia); a residence time of not more than 150 seconds (e.g., not more than 120 seconds, not more than 105 seconds, not more than 90 seconds, not more than 75 seconds, not more than 60 seconds, not more than 45 seconds, not more than 30 seconds, not more than 20 seconds, not more than 15 seconds, or not more than 10 seconds, with a minimum (if necessary) of 0.5 seconds or 1 second; in particular not more than 150 seconds, not more than 120 seconds, or not more than 30 seconds, with a minimum (if necessary) of 1 second); and a ratio of recycled (unreacted) chloromethane to fresh chloromethane and / or a ratio of recycled (unreacted) hydrogen fluoride to fresh hydrogen fluoride from about 1 :4 to about 24:1 (e.g., from about 1:4 to about 19:1, from about 1:4 to about 16:1, from about 1:4 to about 13:1, from about 1 :4 to about 10:1, from about 1 :4 to about 9:1, from about 1:4 to about 8:1, from about 1 :4 to about 7:1, from about 1:4 to about 6:1, from about 1 :4 to about 5:1, from about 1 :4 to about 4:1, from about 1 :2 to about 24: 1 , from about 1 :2 to about 19:1, from about 1 :2 to about 16:1, from about 1 :2 to about 13:1, from about 1 :2 to about 10:1, from about 1:2 to about 9:1, from about 1 :2 to about 8:1, from about 1:2 to about 7:1, from about 1:2 to about 6:1, from about 1 :2 to about 5:1, from about 1:2 to about 4:1, from about 1:1 to about 24:1, from about 1:1 to about 19:1, from about 1 :1 to about 16:1, from about 1 :1 to about 13:1, from about 1:1 to about 10:1, from about 1:1 to about 9:1, from about 1:1 to about 8:1, from about 1 : 1 to about 7:1, from about 1 : 1 to about 6:1, from about 1 : 1 to about 5 : 1 , from about 1:1 to about 4:1, from about 2:1 to about 24:1, from about 2:1 to about 19:1, from about 2:1 to about 16:1, from about 2:1 to about 13:1, from about 2:1 to about 10:1, from about 2:1 to about 9:1, from about 2:1 to about 8:1, from about 2:1 to about 7:1, from about 2:1 to about 6:1, from about 2:1 to about 5:1, from about 2:1 to about 4:1, from about 3:1 to about 24:1, from about 3:1 to about 19:1, from about 3:1 to about 16:1, from about 3:1 to about 13:1, from about 3:1 to about 10:1, from about 3:1 to about 9:1, from about 3:1 to about 8:1, from about 3:1 to about 7:1, from about 3:1 to about 6:1, from about 3:1 to about 5:1, from about 3:1 to about 4:1, from about 4:1 to about 24:1, from about 4:1 to about 19:1, from about 4:1 to about 16:1, from about 4:1 to about 13:1, from about 4:1 to about 10:1, from about 4:1 to about 9:1, from about 4:1 to about 8:1, from about 4:1 to about 7:1, from about 4:1 to about 6:1, from about 4:1 to about 5:1; in particular from about 1 :4 to about 24:1, from about 1:1 to about 19:1, or from about 4:1 to about 16:1).

[0043] As mentioned above, due to incomplete reaction conversion, it can often be advantageous to separate unreacted reactants, in particular chloromethane and hydrogen fluoride, out from the reactor output stream to form a recycle stream, at least a portion (in preferred embodiments, substantially all) of which for recycle to the reactor, with at least a portion (in preferred embodiments, substantially all) of the remaining components of the reactor output stream forming a crude intermediate stream comprising fluoromethane product and hydrogen chloride by-product. If desired, any remaining portion of the recycle stream can be used in one or more other reactions and / or can be further separated for various alternative purposes. The separation to form the recycle stream can advantageously be accomplished through distillation (which can manifest as a single distillation step or multiple distillation steps - if the latter, then the ultimate distillation product should be understood to be the crude intermediate stream, and the multiple distillation / fractionated streams should be understood to collectively represent the recycle stream).

[0044] In some cases, the separation (distillation) conditions should be chosen so that no or only very small amounts of unreacted chloromethane and unreacted hydrogen fluoride (in particular no more than 100 wppm, no more than 50 wppm, or no more than 10 wppm of unreacted chloromethane; and in particular no more than 300 wppm, no more than 100 wppm, no more than 50 wppm, or no more than 10 wppm of unreacted hydrogen fluoride) may remain in the crude intermediate stream (which again comprises fluoromethane product and hydrogen chloride by-product). According to PCT Publication No. WO 2005 / 009933, some or all of the crude intermediate stream can be comprised of an azeotrope of fluoromethane product and hydrogen chloride by-product. Additionally or alternatively, some or all of the crude intermediate stream can be comprised of a near-azeotrope of fluoromethane product and hydrogen chloride byproduct.

[0045] The step of recycling the (portion or all of the) separated out unreacted reactants (in the recycle stream) can include heating the unreacted reactants (in the recycle stream) prior to reintroduction to the reactor, e.g., so that the lower-temperature components (typically occurring from the temperature(s) of the separation(s) being lower than the reaction temperature in the reactor) do not unfavorably affect the temperature stability of the reaction by their “colder” reintroduction. In such cases, the heating of the unreacted reactants can bring them to a temperature no less than 10°C below an average temperature of the reactor and / or of an inlet temperature of the reactor, in particular to no less than 5°C below an average temperature of the reactor and / or of an inlet temperature of the reactor, with a maximum (if necessary) of no more than 10°C above an average temperature of the reactor and / or of an inlet temperature of the reactor or no more than 5°C above an average temperature of the reactor and / or of an inlet temperature of the reactor.

[0046] The step of recycling the (portion or all of the) separated out unreacted reactants (in the recycle stream) can optionally also include adjusting a pressure of the unreacted reactants (in the recycle stream) prior to reintroduction to the reactor, e.g., so that the lower-pressure components (typically occurring from the pressure(s) of the separation(s) being lower than the reaction pressure in the reactor) do not unfavorably affect the pressure stability of the reaction by their reintroduction. In such cases, the pressure adjustment of the unreacted reactants can bring them to a pressure no less than 15 psi below an average pressure of the reactor and / or of an inlet pressure of the reactor, in particular to no less than 7 psi below an average pressure of the reactor and / or of an inlet pressure of the reactor, with a maximum (if necessary) of no more than 15 psi above an average pressure of the reactor and / or of an inlet pressure of the reactor or no more than 7 psi above an average pressure of the reactor and / or of an inlet pressure of the reactor.

[0047] In order to better isolate the desired fluoromethane, the method can advantageously include removing by-product hydrogen chloride from the crude intermediate stream, so as to form a fluoromethane product stream. Although there can be various ways to isolate hydrogen chloride from fluoromethane (such as exist together in the crude intermediate stream), one way is first to treat the fluoromethane / hydrogen chloride combination (crude intermediate stream) with caustic (e.g., comprising a hydroxide moiety and an alkali metal or alkaline earth metal such as including Na, Li, K, Rb, Cs, Be, Ba, Mg, Sr, and Ca; in particular comprising Na, K, Li, Ca, Mg, or mixtures thereof, or comprising Na and / or K, which caustic may optionally further include water), possibly in a scrubber, to neutralize the acidic hydrogen chloride, e.g., into a salt that can precipitate out and be easily separated from the fluoromethane (in the crude intermediate stream; which separation may occur naturally, such as by gravity and / or phase separation, or may include a physical separation such as by filtration and / or an aid to natural separation such as centrifugation), and second to dry the caustic-treated combination (crude intermediate again), so as to limit content of water that can typically be formed by reaction of the acid and neutralizing agent (and / or by the use of aqueous caustic in the neutralization treatment). In various embodiments, the drying may be effectuated by altering temperature / pressure and / or by introduction (and then later separation) of a heterogeneous moisture trap (which can be a solid hygroscopic agent such as molecular sieve or the like, or a liquid that can selectively pull water into its heterogeneous phase).

[0048] If those steps do not sufficiently isolate the desired fluoromethane, the method can optionally include (further) purification of the fluoromethane product stream, thereby forming a purified fluoromethane product stream. In various embodiments, the fluoromethane product stream further purification can include additional distillation. In some such embodiments, the distillation to purify the fluoromethane product stream can be conducted at a pressure of at least 15 psi higher (e.g., at least 30 psi higher, at least 40 psi higher, at least 50 psi higher, at least 60 psi higher, at least 70 psi higher, at least 80 psi higher, at least 90 psi higher, or at least 100 psi higher; in particular at least 30 psi higher, at least 50 psi higher, or at least 70 psi higher) than a pressure of the separation (distillation) of unreacted reactants out from the reactor output stream.

[0049] Although product specifications from the above method(s) can be changeable, for instance depending on an ultimate desired use of fluoromethane product (and optionally other products or by-products), on whether product streams are further treated / purified, and / or on various factors, the fluoromethane product stream and / or the purified fluoromethane product stream from the disclosed methods can individually comprise at least 98.5 wt% e.g., at least 98.8 wt%, at least 99.0 wt%, at least 99.2 wt%, at least 99.4 wt%, at least 99.6 wt%, at least 99.8 wt%, at least 99.9 wt%, or at least 99.95 wt%, with maxima (if necessary) of up to 99.99 wt%, up to 99.999 wt%, or up to 99.9999 wt%; in particular at least 98.5 wt%, at least 99 wt%, or at least 99.9 wt%, optionally up to 99.999 wt%) fluoromethane, at most 1.4 wt% (e.g, at most 1.1 wt%, at most 1.0 wt%, at most 0.8 wt%, at most 0.6 wt%, at most 0.5 wt%, at most 0.4 wt%, at most 0.2 wt%, at most 0.1 wt%, or at most 0.05 wt%, with minima (if necessary) of 0.01 wt%, 0.005 wt%, 0.001 wt%, or no measurable; in particular at most 1.1 wt%, at most 1.0 wt%, or at most 0.5wt%, or at most 0.1 wt%, optionally extending to no measurable) methane, no more than 200 wppm (e.g., no more than 100 wppm, no more than 80 wppm, no more than 60 wppm, no more than 50 wppm, no more than 40 wppm, no more than 20 wppm, no more than 10 wppm, no more than 5 wppm, no more than 1 wppm, or no measurable; in particular, no more than 200 wppm, no more than 100 wppm, no more than 20 wppm, or no measurable) difluoromethane, no more than 200 wppm (e.g., no more than 100 wppm, no more than 80 wppm, no more than 60 wppm, no more than 50 wppm, no more than 40 wppm, no more than 20 wppm, no more than 10 wppm, no more than 5 wppm, no more than 1 wppm, or no measurable; in particular, no more than 200 wppm, no more than 100 wppm, no more than 50 wppm, or no more than 10 wppm) by-products collectively possessing more than one carbon atom.

[0050] Aside from characterization of reaction output streams, reactions can additionally or alternatively be characterized by product selectivity(ies). A “selectivity”, or a “raw selectivity” as used herein, can be defined for a product or by-product in a given stream (in methods according to the disclosure, desirably for product fluoromethane), as a percentage weight content of the specific product / by-product in the given stream, relative to the weight of other products and byproducts measured in that stream, typically ignoring unreacted reactants (e.g., from incomplete conversion), solid particles (when present, e.g., support particles / porous promoters such as included in the methods described herein), already reacted products / by-products (such as from a recycle step / stream), and any other species that transform into reactants under the reaction conditions. A “reaction-specific selectivity” as used herein for a product or by-product in a given stream (in methods according to the disclosure, desirably for product fluoromethane), can additionally adjust to also ignore (unreactive) diluents in the given stream (like those introduced into the reactor, whether specifically as a reaction diluent, perhaps with a non-reactive function such as heat transfer agent or the like, or as an impurity in a reactant). Therefore, a “reactionspecific selectivity” for a product or by-product in a given stream can be defined as the “raw selectivity” plus the collective percentage weight contents, relative to the weight of other products and by-products measured in that stream, of impurities in the (chloromethane and hydrogen fluoride) reactants and / or other streams added to the reactor that cannot participate in the conversion of reactants into (fluoromethane) product under reaction conditions (e.g, including inerts in the chloromethane such as methane and the like, reactive species in the chloromethane like dichloromethane that can only become difluoromethane or chlorofluoromethane by-products but never fluoromethane product, inerts in the hydrogen fluoride such as water, and reactive species in the hydrogen fluoride that cannot react with the chloromethane reactant to form fluoromethane such as carbon tetrachloride, hydrogen bromide, and the like). This effectively results in a further exclusion of such inerts and unproductive reactive impurities in the reactants that were overlooked (presumed not to exist or as having very minor impact on reaction kinetics and / or product / by-product formation) in the definition of “selectivity” / ”raw selectivity”.

[0051] Indeed, in the method(s) according to the disclosure, the chloromethane reactant in particular can contain some measurable amount of methane and / or other impurities (that cannot be converted into fluoromethane product under the conditions in the reactor). When present, the chloromethane reactant can contain from 10 wppm to 1.4 wt% (e.g., from 10 wppm to 1.2 wt%, from 10 wppm to 1.0 wt%, from 10 wppm to 0.8 wt%, from 10 wppm to 0.6 wt%, from 10 wppm to 0.4 wt%, from 10 wppm to 0.2 wt%, from 10 wppm to 0.1 wt%, from 20 wppm to 1.4 wt%, from 20 wppm to 1.2 wt%, from 20 wppm to 1.0 wt%, from 20 wppm to 0.8 wt%, from 20 wppm to 0.6 wt%, from 20 wppm to 0.4 wt%, from 20 wppm to 0.2 wt%, from 20 wppm to 0.1 wt%, from 30 wppm to 1.4 wt%, from 30 wppm to 1.2 wt%, from 30 wppm to 1.0 wt%, from 30 wppm to 0.8 wt%, from 30 wppm to 0.6 wt%, from 30 wppm to 0.4 wt%, from 30 wppm to 0.2 wt%, from 30 wppm to 0.1 wt%, from 50 wppm to 1.4 wt%, from 50 wppm to 1.2 wt%, from 50 wppm to 1.0 wt%, from 50 wppm to 0.8 wt%, from 50 wppm to 0.6 wt%, from 50 wppm to 0.4 wt%, from 50 wppm to 0.2 wt%, from 50 wppm to 0.1 wt%, from 70 wppm to 1.4 wt%, from 70 wppm to 1.2 wt%, from 70 wppm to 1.0 wt%, from 70 wppm to 0.8 wt%, from 70 wppm to 0.6 wt%, from 70 wppm to 0.4 wt%, from 70 wppm to 0.2 wt%, from 70 wppm to 0.1 wt%, from 100 wppm to 1.4 wt%, from 100 wppm to 1.2 wt%, from 100 wppm to 1.0 wt%, from 100 wppm to 0.8 wt%, from 100 wppm to 0.6 wt%, from 100 wppm to 0.4 wt%, from 100 wppm to 0.2 wt%, or from 100 wppm to 0.1 wt%; in particular from 10 wppm to 1.4 wt%, from 100 wppm to 1.0 wt%, from 20 wppm to 0.8 wt%, or from 30 wppm to 0.6 wt%) methane and optionally up to 2.0 wt% e.g.. up to 1.9 wt%, up to 1.8 wt%, up to 1.7 wt%, up to 1.6 wt%, up to 1.5 wt%, up to 1.4 wt%, up to 1.3 wt%, up to 1.2 wt%, up to 1.1 wt%, up to 1.0 wt%, up to 0.9 wt%, up to 0.8 wt%, up to 0.7 wt%, up to 0.6 wt%, up to 0.5 wt%, up to 0.4 wt%, up to 0.3 wt%, up to 0.2 wt%, or up to 0.1 wt%, with minima (if necessary) of 100 wppm, 10 wppm, or no measurable content; in particular up to 1.9 wt%, up to 1.0 wt%, or up to 0.3 wt%, with a minimum, if necessary, of zero / no measurable content) of other impurities (that cannot be converted into fluoromethane product under the conditions in the reactor). In such situations, the conditions in the reactor can be controlled so as to achieve a fluoromethane product reaction-specific selectivity of at least 98.5 wt%, e.g., at least 98.8 wt%, at least 99.0 wt%, at least 99.2 wt%, at least 99.4 wt%, at least 99.5 wt%, at least 99.6 wt%, at least 99.8 wt%, or at least 99.9 wt% (with an optional maximum, if necessary, of 99.9999 wt% or 99.999 wt%); in particular at least 99.0 wt% or at least 99.5 wt% (with an optional maximum, if necessary of 99.999 wt%).

[0052] The method may be continuous or semi continuous, or batch or semi-batch.

[0053] Fluoromethane Product Compositions

[0054] Fluoromethane product compositions can be comprised of the fluoromethane product stream and / or the purified fluoromethane product stream from the synthesis method(s) disclosed herein. Regardless of how made, fluoromethane product compositions can comprise at least 98.5 wt% (e.g., at least 98.8 wt%, at least 99.0 wt%, at least 99.2 wt%, at least 99.4 wt%, at least 99.5 wt%, at least 99.6 wt%, at least 99.8 wt%, at least 99.9 wt%, or at least 99.95 wt%, with maxima (if necessary) of up to 99.99 wt%, up to 99.999 wt%, or up to 99.9999 wt%; in particular at least 98.5 wt%, at least 99.0 wt%, at least 99.5 wt%, or at least 99.9 wt%, optionally up to 99.999 wt%) fluoromethane, at most 1.4 wt% (e.g., at most 1.1 wt%, at most 1.0 wt%, at most 0.8 wt%, at most 0.6 wt%, at most 0.5 wt%, at most 0.4 wt%, at most 0.2 wt%, at most 0.1 wt%, or at most 0.05 wt%, with minima (if necessary) of 0.01 wt%, 0.005 wt%, 0.001 wt%, or no measurable; in particular at most 1.1 wt%, at most 1.0 wt%, or at most 0.5wt%, or at most 0.1 wt%, optionally extending to no measurable) methane, no more than 200 wppm (e.g., no more than 100 wppm, no more than 80 wppm, no more than 60 wppm, no more than 50 wppm, no more than 40 wppm, no more than 20 wppm, no more than 10 wppm, no more than 5 wppm, no more than 1 wppm, or no measurable; in particular, no more than 200 wppm, no more than 100 wppm, no more than 20 wppm, or no measurable) difluoromethane, no more than 200 wppm (e.g. , no more than 100 wppm, no more than 80 wppm, no more than 60 wppm, no more than 50 wppm, no more than 40 wppm, no more than 20 wppm, no more than 10 wppm, no more than 5 wppm, no more than 1 wppm, or no measurable; in particular, no more than 200 wppm, no more than 100 wppm, no more than 50 wppm, or no more than 10 wppm) by-products collectively possessing more than one carbon atom, other than methane, optionally no more than no more than 200 wppm (e.g, no more than 100 wppm, no more than 80 wppm, no more than 60 wppm, no more than 50 wppm, no more than 40 wppm, no more than 20 wppm, no more than 10 wppm, no more than 5 wppm, no more than 1 wppm, or no measurable; in particular, no more than 200 wppm, no more than 100 wppm, no more than 50 wppm, or no more than 10 wppm) water / moisture content, optionally no more than no more than 200 wppm (e.g, no more than 100 wppm, no more than 80 wppm, no more than 60 wppm, no more than 50 wppm, no more than 40 wppm, no more than 20 wppm, no more than 10 wppm, no more than 5 wppm, no more than 1 wppm, or no measurable; in particular, no more than 200 wppm, no more than 100 wppm, no more than 50 wppm, or no more than 10 wppm) hydrogen chloride content, and optionally no more than no more than 200 wppm (e.g, no more than 100 wppm, no more than 80 wppm, no more than 60 wppm, no more than 50 wppm, no more than 40 wppm, no more than 20 wppm, no more than 10 wppm, no more than 5 wppm, no more than 1 wppm, or no measurable; in particular, no more than 200 wppm, no more than 100 wppm, no more than 50 wppm, or no more than 10 wppm) hydrogen fluoride content. In some embodiments, the fluoromethane product composition can be used as an etch gas composition, or as a component of an etch gas composition, e.g., for use in semiconductor etching.

[0055] Various Embodiments

[0056] Additionally or alternatively, the invention may include, but is not necessarily limited to, the following non-limiting embodiments.

[0057] Embodiment 1. A method for synthesis of fluoromethane comprising: contacting reactants comprising chloromethane and at least a 150% stoichiometric excess of hydrogen fluoride, relative to chloromethane, in gas phase in a reactor in the substantial absence of chromium but optionally in the presence of solid support particles; controlling conditions in the reactor to foster reaction of the reactants optionally in the presence of the solid support particles to form a reactor output stream comprising fluoromethane at a reactant conversion of at least 3% and no more than 30%, wherein the conditions the reactor comprise substantially no electrical discharge and / or no intentionally applied external voltage; separating unreacted chloromethane and hydrogen fluoride out from the reactor output stream to form a recycle stream, with at least a portion of the remaining components of the reactor output stream forming a crude intermediate stream comprising fluoromethane product and hydrogen chloride by-product; recycling at least a portion of the recycle stream comprising the unreacted chloromethane and hydrogen fluoride back to the reactor; removing by-product hydrogen chloride from the crude intermediate stream to form a fluoromethane product stream; and optionally purifying the fluoromethane product stream to form a purified fluoromethane product stream, wherein the fluoromethane product stream and / or the purified fluoromethane product stream comprises at least 98.5 wt% fluoromethane, at most 1.1 wt% methane, no more than 200 wppm difluoromethane, and no more than 200 wppm by-products collectively possessing more than one carbon atom.

[0058] Embodiment 2. The method of embodiment 1, wherein the stoichiometric excess of hydrogen fluoride, relative to chloromethane, is from 200% to 2900%, in particular from 300% to 1900% or from 400% to 1400%.

[0059] Embodiment 3. The method of embodiment 1 or embodiment 2, wherein the solid support particles are present and are porous.

[0060] Embodiment 4. The method of any of embodiments 1-3, wherein the solid support particles are present and comprise alumina, activated alumina, silica, activated carbon, aluminosilicates, borosilicates, aluminoborates, zeolites, alkali oxides, alkaline earth oxides, carbonates, or combinations thereof.

[0061] Embodiment 5. The method of any of embodiments 1-4, wherein the contacting of reactants in the reactor occurs further in the substantial absence of iron.

[0062] Embodiment 6. The method of any of embodiments 1-5, wherein the conditions in the reactor are controlled to comprise: a reactor temperature from about 200°C to about 550°C, in particular from about 250°C to about 400°C or from about 280°C to about 450°C; a reactor pressure from about 10 psiato about 300 psia, in particular from about 15 psia to about 270 psia; and a residence time of not more than 150 seconds, in particular not more than 120 seconds.

[0063] Embodiment 7. The method of any of embodiments 1-6, wherein the reactant conversion is at least 5% and not more than 25%. Embodiment 8. The method of any of embodiments 1-7, wherein separation of unreacted reactants comprises distillation.

[0064] Embodiment 9. The method of any of embodiments 1 -8, wherein the recycling of unreacted reactants includes, after separation, heating the unreacted reactants to no less than 10°C below an inlet temperature of the reactor, in particular to no less than 5°C below an inlet temperature of the reactor.

[0065] Embodiment 10. The method of any of embodiments 1-9, wherein the removing of hydrogen chloride from the crude intermediate stream includes treatment of the crude intermediate stream with caustic, followed by a drying step.

[0066] Embodiment 11. The method of any of embodiments 1-10, wherein the fluoromethane product stream is purified using distillation.

[0067] Embodiment 12. The method of embodiment 11, wherein the distillation to purify the fluoromethane product stream is conducted at a pressure of at least 30 psi higher, in particular at least 50 psi higher or at least 70 psi higher, than a pressure of the separation of unreacted reactants out from the reactor output stream.

[0068] Embodiment 13. The method of any of embodiments 1-12, wherein the fluoromethane product stream and / or the purified fluoromethane product stream comprises at least 99.0 wt% fluoromethane, at most 1.0 wt% methane, no more than 20 wppm difluoromethane, and no more than 50 wppm by-products collectively possessing more than one carbon atom, other than methane.

[0069] Embodiment 14. The method of any of embodiments 1-13, wherein the chloromethane reactant comprises from 100 wppm to 1.0 wt% methane and optionally up to 1.9 wt% of other impurities that cannot be converted into fluoromethane product under the conditions in the reactor, and wherein the conditions in the reactor are controlled to have a fluoromethane product reaction-specific selectivity of at least 99.0 wt%, in particular at least 99.5 wt%.

[0070] Embodiment 15. A fluoromethane product composition, optionally made according to the method of any of embodiments 1-13, consisting of: at least 99 wt%, in particular at least 99.9 wt%, fluoromethane; at most 0.5 wt%, in particular at most 0.1 wt% methane; no more than 20 wppm, in particular no measurable, difluoromethane; no more than 50 wppm by-products collectively possessing more than one carbon atom, other than methane; optionally no more than 10 wppm water content; optionally no more than 10 wppm hydrogen chloride content; and optionally no more than 10 wppm hydrogen fluoride content.

[0071] EXAMPLES

[0072] Comparative Examples 1 -9

[0073] In a ~1” diameter Hastelloy® (C-276) reactor with a length of —16”, ~80 mL (Comparative Examples 1-2) or ~30 mL (Comparative Examples 3-9) of bulk chromium oxide catalyst (E 410 T 1 / 8", obtained from BASF) was activated under a flow of aHF and nitrogen at ~300°C. After each catalyst activation, the reactor was maintained at ~300°C at a pressure of ~25 psig. The supply of nitrogen was stopped, and aHF was introduced at a variety of flow rates ranging from ~4 g / h to ~32 g / h with temperature maintained at ~300°C. Commercially available chloromethane was introduced at a variety of flow rates ranging from ~1.2 g / h to -17 g / h, at a variety of HFiCHjCl molar ratios ranging from ~4:1 to —17:1. Each reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online gas chromatograph (GC). The conversions of chloromethane to fluoromethane, the raw selectivities for fluoromethane, and the approximate residence times for each reaction, as well as the other variables described above, are shown in Table 1 below.

[0074] Table 1.

[0075] Comparative Examples 10-12 In a ~1” diameter Hastelloy® (C-276) reactor with a length of -16”, ~30 mL of bulk chromium oxide catalyst (Pricat™ 62-3M, obtained from Johnson Matthey) was activated under a flow of aHF and nitrogen at ~300°C. After each catalyst activation, the reactor was maintained at ~300°C at a pressure of -25 psig. The supply of nitrogen was stopped, and aHF was introduced at a flow rate of -30 g / h with temperature maintained at -300°C. Commercially available chloromethane was introduced at a variety of flow rates ranging from -9.8 g / h to ~17 g / h, at a variety of HFiCHsCl molar ratios ranging from -4:1 to -8: 1. Each reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online GC. The conversions of chloromethane to fluoromethane, the raw selectivities for fluoromethane, and the approximate residence times for each reaction, as well as the other variables described above, are shown in Table 2 below.

[0076] Table 2.

[0077] Comparative Examples 13-20

[0078] In a -1” diameter Hastelloy® (C-276) reactor with a length of -16”, -10 mL of alumina- supported chromium oxide catalyst (PBN1, obtained from Arkema) was activated under a flow of aHF and nitrogen at ~300°C. After each catalyst activation, the reactor was maintained at ~300°C at a pressure of -25 psig. The supply of nitrogen was stopped, and aHF was introduced at a variety of flow rates ranging from -5 g / h to -50 g / h with temperature maintained at ~300°C. Commercially available chloromethane was introduced at a variety of flow rates ranging from -1.6 g / h to -17 g / h, at a variety of HF:CH3C1 molar ratios ranging from -4:1 to -8:1. Each reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online gas chromatograph (GC). The conversions of chloromethane to fluoromethane, the raw selectivities for fluoromethane, and the approximate residence times for each reaction, as well as the other variables described above, are shown in Table 3 below. Table 3.

[0079] Examples 21-25

[0080] In a ~1” diameter Hastelloy® (C-276) reactor with a length of —16”, ~10 mL of ~5% FeCh supported on activated carbon was activated under a flow of aHF and nitrogen at ~300°C. After each catalyst activation, the reactor was maintained at a temperature of ~300°C (Examples 21-22) or ~335°C (Examples 23-25) at a pressure of ~25 psig. The supply of nitrogen was stopped, and aHF was introduced at a variety of flow rates ranging from ~2.4 g / h to ~30 g / h with temperature maintained at ~300QC or ~335°C, respectively. Commercially available chloromethane was introduced at a variety of flow rates ranging from ~1.5 g / h to -8 g / h, at a variety of HFiCHsCl molar ratios ranging from -4:1 to -9:1. Each reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online gas chromatograph (GC). The conversions of chloromethane to fluoromethane, the raw selectivities for fluoromethane, and the approximate residence times for each reaction, as well as the other variables described above, are shown in Table 4 below.

[0081] Table 4.

[0082] Examples 26-28

[0083] In Example 26, a —3 / 8” diameter Hastelloy® (C-276) reactor with a length of ~16” was heated to ~450°C at a pressure of ~150 psig under a flow of nitrogen for ~24 hours. The supply of nitrogen was stopped, and aHF was introduced at a flow rate of -40 g / h with temperature maintained at ~450°C. Commercially available chloromethane was then introduced at a flow rate of ~20 g / h, at an HFiCHaCl molar ratio of -5:1. Residence time was -5.4 seconds. Reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online GC. The residence time was ~5.4 seconds, and the conversion of chloromethane to fluoromethane was -3%.

[0084] In Example 27, Example 26 was repeated, but with an aHF flow rate of -19 g / h and a chloromethane flow rate of ~1.9 g / h, and at an HFiCHsCl molar ratio of -25:1. Residence time was -17 seconds, and conversion was -3.8%.

[0085] In Example 28, Example 26 was repeated, but in a -1” diameter Hastelloy® (C-276) reactor at a pressure of -100 psig (temperature of ~450°C), with a flow rate of -30 g / h of aHF and -17 g / h of chloromethane, at an HFrCHsCl molar ratio of -5:1. Residence time was -156 seconds, and conversion was -1% with >99% raw selectivity for fluoromethane.

[0086] In Example 29, Example 28 was repeated, but at a temperature of ~300°C (pressure of -100 psig), with a flow rate of -67 g / h of aHF and -32 g / h of chloromethane (HF:CH3C1 molar ratio of -5:1). Residence time was -89 seconds, and the conversion was <1% but with >99% raw selectivity for fluoromethane.

[0087] Examples 30-33

[0088] In a~l” diameter Hastelloy® (C-276) reactor with a length of -16”, -80 mL of low surface area alumina (corundum, -5 m2 / g, obtained from Panadyne) was heated to ~300°C (Examples 30-31) or ~335°C (Examples 32-33) at a pressure of -25 psig under a flow of nitrogen for -24 hours. The supply of nitrogen was stopped, and aHF was introduced at a flow rate of -10 g / h with temperature maintained at ~300°C or ~335°C, respectively. Commercially available chloromethane was introduced at a flow rate of -3.3 g / h (Examples 30 and 33) or -1.6 g / h (Examples 31-32), at an HF:CH3C1 molar ratio of -8:1 (Examples 30 and 33) or -16:1 (Examples 31-32). Each reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online GC. The conversions of chloromethane to fluoromethane, the raw selectivities for fluoromethane, and the approximate residence times for each reaction, as well as the other variables described above, are shown in Table 5 below.

[0089] Table 5.

[0090] Examples 34-36

[0091] In Example 34, in a —1 / 2” diameter Hastelloy® (C-276) reactor with a length of —16”, ~13 mL of porous alumina (Alum-SAS200™-sphere-l / 8”, ~350 m2 / g, obtained from BASF) was heated to ~300°C at a pressure of —150 psig under a flow of nitrogen for ~24 hours. The supply of nitrogen was stopped, and aHF was introduced at a flow rate of -30 g / h with temperature maintained at ~300°C. An exotherm was observed, but, when the temperature was stable at ~300°C, commercially available chloromethane was introduced at a flow rate of ~10 g / h, at an HFiCHsCl molar ratio of ~7.6: 1. Reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online GC. The residence time was between 6 and 7 seconds. The conversion of chloromethane to fluoromethane was ~2%, and the raw selectivity for fluoromethane was >99%.

[0092] In Example 35, Example 34 was repeated but at a temperature of ~325°C. Conversion was -6%, with residence time and raw selectivity remaining the same.

[0093] In Example 36, Example 34 was repeated but at a temperature of ~350°C. Conversion was —10%, with residence time and raw selectivity remaining the same.

[0094] Examples 37-48

[0095] In Example 37, in a —1 / 2” diameter Hastelloy® (C-276) reactor with a length of ~16”, ~13 mL of coal -based activated carbon granules (obtained from Calgon Carbon) was heated to ~300°C at a pressure of ~150 psig under a flow of nitrogen for ~24 hours. The supply of nitrogen was stopped, and aHF was introduced at a flow rate of ~30 g / h with temperature maintained at ~300°C. Commercially available chloromethane was introduced at a flow rate of ~10 g / h, at an HFrCHsCl molar ratio of ~7.6: 1. Reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online GC. The residence time was -6.7 seconds. The conversion of chloromethane to fluoromethane was -9.7%, and the raw selectivity for fluoromethane was >99%.

[0096] In Examples 38-47, Example 37 was repeated but at temperatures of ~100°C, ~125°C, ~150°C, ~175°C, ~200°C, ~225°C, ~250°C, ~275°C, ~325°C, and ~350°C, respectively. Conversion at temperatures at or below ~200°C were all <0.5%. Conversion at ~225°C was ~1%, with raw selectivity for fluoromethane of >99%. Conversion at ~250°C was —3.5%, with raw selectivity for fluoromethane of >99%. Conversion at ~275°C was -7.6%, with raw selectivity for fluoromethane of >99%. Conversion at ~325°C was -10%, with raw selectivity for fluoromethane of >99%. Conversion at ~350°C was -11%, with raw selectivity for fluoromethane of >99%.

[0097] In Example 48, in a -1” diameter Hastelloy® (C-276) reactor, -120 mL of coal-based activated carbon granules (obtained from Calgon Carbon) was heated to ~300°C at a pressure of -100 psig under a flow of nitrogen for -24 hours. The supply of nitrogen was stopped, and aHF was introduced at a flow rate of -50 g / h with temperature maintained at ~300°C. Commercially available chloromethane was introduced at a flow rate of -17 g / h, at an HFiCHjCl molar ratio of -7.4:1. Reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online GC. Residence time was -11 seconds; conversion was -10%; and raw selectivity for fluoromethane was >99%.

[0098] Examples 49-51

[0099] In Example 49, in a -1 / 2” diameter Hastelloy® (C-276) reactor with a length of —16”, -13 mL of activated carbon extrudate (coconut-based, -1000 m2 / g, obtained from Johnson Matthey) was heated to ~300°C at a pressure of -150 psig under a flow of nitrogen for -24 hours. The supply of nitrogen was stopped, and aHF was introduced at a flow rate of -30 g / h with temperature maintained at ~300°C. Commercially available chloromethane was introduced at a flow rate of -10 g / h, at an HF iCH Cl molar ratio of -7.6:1. Reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online GC. The residence time was between 6 and 7 seconds. The conversion of chloromethane to fluoromethane was -8%, and the raw selectivity for fluoromethane was >99%. In Example 50, Example 49 was repeated but at a temperature of ~325°C. Conversion was ~10%, with residence time and raw selectivity remaining the same.

[0100] In Example 51, Example 49 was repeated but at a temperature of ~350°C. Conversion was ~11%, with residence time and raw selectivity remaining the same.

[0101] Examples 52-54

[0102] In Example 52, in a —1 / 2” diameter Hastelloy® (C-276) reactor with a length of -16”, -13 mL of activated carbon extrudate (coal-based, -4 mm, -1050-1200 m2 / g, obtained from Carbon Activated Corporation) was heated to ~300°C at a pressure of -150 psig under a flow of nitrogen for -24 hours. The supply of nitrogen was stopped, and aHF was introduced at a flow rate of -30 g / h with temperature maintained at ~300°C. Commercially available chloromethane was introduced at a flow rate of -10 g / h, at an HFrCHjCl molar ratio of -7.6:1. Reactor outlet gas was passed through a caustic scrubber and drying column, and then a cut of the outlet gas was introduced to an online GC. The residence time was between 6 and 7 seconds, and the conversion of chloromethane to fluoromethane was -5%.

[0103] In Example 53, Example 52 was repeated but at a temperature of ~325°C. Conversion was -6%, with residence time remaining the same.

[0104] In Example 51, Example 49 was repeated but at a temperature of ~350°C. Conversion was -7%, with residence time remaining the same.

[0105] Within this specification, embodiments and / or Examples have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without departing from the disclosure. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the disclosure herein.

[0106] In some embodiments, the disclosure herein can be construed as excluding any element of process step that does not materially affect the basic and novel characteristics of the compositions, materials, products, and articles prepared therefore and methods for making and using such compositions, materials, products, and articles. Additionally, in some embodiments, the disclosure can be construed as excluding any element or process step not specified herein.

[0107] Although the disclosure is illustrated and described herein with reference to specific embodiments and / or Examples, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details and the scope and range of equivalents of the claims and without departing from the invention.

Claims

CLAIMSWhat is claimed is:

1. A method for synthesis of fluoromethane comprising: contacting reactants comprising chloromethane and at least a 150% stoichiometric excess of hydrogen fluoride, relative to chloromethane, in gas phase in a reactor in the substantial absence of chromium but optionally in the presence of solid support particles; controlling conditions in the reactor to foster reaction of the reactants optionally in the presence of the solid support particles to form a reactor output stream comprising fluoromethane at a reactant conversion of at least 3% and no more than 30%, wherein the conditions the reactor comprise substantially no electrical discharge and / or no intentionally applied external voltage; separating unreacted chloromethane and hydrogen fluoride out from the reactor output stream to form a recycle stream, with at least a portion of the remaining components of the reactor output stream forming a crude intermediate stream comprising fluoromethane product and hydrogen chloride by-product; recycling at least a portion of the recycle stream comprising the unreacted chloromethane and hydrogen fluoride back to the reactor; removing by-product hydrogen chloride from the crude intermediate stream to form a fluoromethane product stream; and optionally purifying the fluoromethane product stream to form a purified fluoromethane product stream, wherein the fluoromethane product stream and / or the purified fluoromethane product stream comprises at least 98.5 wt% fluoromethane, at most 1.1 wt% methane, no more than 200 wppm difluoromethane, and no more than 200 wppm by-products collectively possessing more than one carbon atom.

2. The method of claim 1, wherein the stoichiometric excess of hydrogen fluoride, relative to chloromethane, is from 200% to 2900%, in particular from 300% to 1900% or from 400% to 1400%.

3. The method of claim 1 or claim 2, wherein the solid support particles are present and are porous.

4. The method of any of claims 1-3, wherein the solid support particles are present and comprise alumina, activated alumina, silica, activated carbon, aluminosilicates, borosilicates, aluminoborates, zeolites, alkali oxides, alkaline earth oxides, carbonates, or combinations thereof.

5. The method of any of claims 1-4, wherein the contacting of reactants in the reactor occurs further in the substantial absence of iron.

6. The method of any of claims 1-5, wherein the conditions in the reactor are controlled to comprise: a reactor temperature from about 200°C to about 550°C, in particular from about 250°C to about 400°C or from about 280°C to about 450°C; a reactor pressure from about 10 psia to about 300 psia, in particular from about 15 psia to about 270 psia; and a residence time of not more than 150 seconds, in particular not more than 120 seconds.

7. The method of any of claims 1-6, wherein the reactant conversion is at least 5% and not more than 25%.

8. The method of any of claims 1-7, wherein separation of unreacted reactants comprises distillation.

9. The method of any of claims 1-8, wherein the recycling of unreacted reactants includes, after separation, heating the unreacted reactants to no less than 10°C below an inlet temperature of the reactor, in particular to no less than 5°C below an inlet temperature of the reactor.

10. The method of any of claims 1-9, wherein the removing of hydrogen chloride from the crude intermediate stream includes treatment of the crude intermediate stream with caustic, followed by a drying step.

11. The method of any of claims 1-10, wherein the fluoromethane product stream is purified using distillation.

12. The method of claim 11 , wherein the distillation to purify the fluoromethane product stream is conducted at a pressure of at least 30 psi higher, in particular at least 50 psi higher or at least 70 psi higher, than a pressure of the separation of unreacted reactants out from the reactor output stream.

13. The method of any of claims 1-12, wherein the fluoromethane product stream and / or the purified fluoromethane product stream comprises at least 99.0 wt% fluoromethane, at most 1.0 wt% methane, no more than 20 wppm difluoromethane, and no more than 50 wppm by-products collectively possessing more than one carbon atom, other than methane.

14. The method of any of claims 1-13, wherein the chloromethane reactant comprises from 100 wppm to 1.0 wt% methane and optionally up to 1.9 wt% of other impurities that cannot be converted into fluoromethane product under the conditions in the reactor, and wherein the conditions in the reactor are controlled to have a fluoromethane product reaction-specific selectivity of at least 99.0 wt%, in particular at least 99.5 wt%.

15. A fluoromethane product composition consisting of: at least 99 wt%, in particular at least 99.9 wt%, fluoromethane; at most 0.5 wt%, in particular at most 0.1 wt% methane; no more than 20 wppm, in particular no measurable, difluoromethane; no more than 50 wppm by-products collectively possessing more than one carbon atom, other than methane; optionally no more than 10 wppm water content; optionally no more than 10 wppm hydrogen chloride content; and optionally no more than 10 wppm hydrogen fluoride content.

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