AND AROMATICS

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority from U.S. Provisional Patent Application No.

62/618,745 entitled“METHOD OF CONVERTING ALKANES TO ALKANE HALIDES”, filed on January 18, 2018, the entire contents of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to low-temperature photochemical processes that convert methane or other alkanes to methanesulfonyl chloride (or other alkanesulfonyl halides) with the aid of LEDs as a light source, where the alkanesulfonyl halide may be further converted to alcohols, olefins, and aromatics, and apparatuses implementing the same.

BACKGROUND OF THE INVENTION

[0003] Natural gas productivity in the United States has increased substantially in recent years due in part to shale gas extraction. As predicted by the U.S. Energy Information

Administration, 46% of the United States’ natural gas supply will come from shale gas by 2035. Currently natural gas is primarily used for power generation. This growth in shale gas production calls for efficient and advanced processes to upgrade alkanes, especially methane, the primary component of natural gas, to value-added chemicals. Almost all the present commercial methane conversion processes take an“indirect conversion” route, requiring reforming methane to synthesis gas (CO and ¾) at 700-900 °C. The synthesis gas is then converted to long-chain hydrocarbons via the Fischer-Tropsch process, or also via methanol synthesis followed by methanol-to-olefin (MTO) processes. The reforming process is rather energy extensive and contributes to about 50% of the total cost for the conversion of methane to liquid products. Other components in the natural gas, including ethane, propane, and butane, can be converted to olefins at around 850 °C by steam cracking or catalytic dehydrogenation, which is also a high-temperature process that requires high energy input and operating cost. Therefore, a direct route for the conversion of alkanes to value-added chemicals, preferably at a low operating temperature, would be highly desirable.

[0004] Although alkane halogenation processes have been considered as an alternative for direct alkane conversion, the formation of undesirable polyhalogenates cannot be averted, and these side products complicates separation. Alkane sulfohalogenation, also known as the Reed process, is another alternative for alkane halogenation. The Reed process was first reported in 1936 (U.S. Patent No. 2,174,492). It is a photochemical transformation of hydrocarbons into aliphatic sulfonyl chlorides in the presence of sulfuryl chloride or sulfur dioxide and chlorine under mercury light illumination. The reaction occurs through the generation of free radicals, as follows:

R— H + Cl— > R +HCI (equation 1)

R +: S0 ₂ — > R— S0 ₂ (equation 2)

R— S0 ₂ +: Cl ₂ — > R— S0 ₂ — Cl + Cl (equation 3)

[0005] Ultra-violet mercury light sources were conventionally used to initiate the free radical chain reaction (U.S. Patent Nos. 4,997,535, 4,735,747 and 6,045,664). However, mercury lights have several drawbacks. First, they are usually not optimized for energy efficiency, using only a small portion of the spectrum to irradiate chemical molecules. Using these lights, the quantum efficiency, i.e. moles of products formed per mole of photon absorbed by the system, is usually less than 300%. Mercury light bulbs also have a short lifespan, ranging from 800 to 3000 hours. In addition, mercury is toxic. Therefore, accessibility and affordability of a continuously running alkanesulfonyl halide manufacturing process are severely restricted when using a mercury light source. [0006] As described below, an inventive process will be presented for alkane

sulfohalogenation using light emitting diodes (LEDs) for economical alkane conversion under mild conditions. LEDs emit light via the electroluminescence effect, resulting in brilliant light while consuming little energy. Advantageously, LED lights have a narrow spectral distribution centered around specific wavelengths, which may promote overall photon utilization. For UV/blue LEDs, the energy of the photons ranges from 250 kJ/mol to 328 kJ/mol, a range that may be desirable for initiating free radical reactions (for reference, bond energies for the following bonds are: Cl-Cl: 240 kJ/mol; Br-Br: 190 kJ/mol; and I-I: 150 kJ/mol). Also advantageously, LEDs have longer life expectancies (about 70,000 hours) and lower unit prices compared to conventional mercury lamps. Thus compared to photochemical processes using mercury lamps, LEDs’ lower energy consumption and longer lifespans may render them more suitable for the continuous manufacturing of alkanesulfonyl halides. Moreover, an LED light source may improve selectivity for the alkanesulfonyl halide product and the associated reaction quantum efficiency due to its narrow wavelength distribution.

SUMMARY OF THE INVENTION

[0007] Herein we disclose a low-temperature and energy-efficient route for photochemical alkane halogenation, wherein the alkane is preferably methane, either by sulfuryl halides (SO2X2, where X = Cl, Br, I) or by halogen in the presence of sulfur dioxide, for the generation of alkanesulfonyl halides (RSX or RSO2X) and hydrogen halides (HX). RSX can decompose at a low temperature (<200 °C) and produce mono alkyl halides (RX) and sulfur dioxide, as disclosed by U.S. Pat. No. 8,916,734. By using LEDs for sulfohalogenation, the process described herein results in a higher yield towards RSX. Although it was expected that when an LED light source is employed, external quantum efficiency would be higher compared to conventional Reed processes that use mercury bulbs for light irradiation, the extent of the quantum efficiency improvement (from about 140% to about 1700%) was entirely unexpected.

[0008] Also disclosed is a process for converting a methane-containing gas to a methane sulfonyl halide that comprises reacting the methane-containing gas, under illumination by a light emitting diode (LED) source that has a wavelength in the range of 150 to 1000 nm (inclusive), with at least one of either a sulfuryl halide, or alternatively a halogen in the presence of sulfur dioxide. The methane sulfonyl halide thus obtained can be isolated or used to carry out further reactions.

[0009] In an embodiment, the wavelength of the light emitting diode (LED) source is in the range of 350 to 480 nm inclusive or any value within this range, or alternatively 445 to 455 nm inclusive or any value within this range. The illumination power density of the LED source when the reactor’s inner surface area is taken into account can range within about 3 to 1500 W/m ² in an embodiment. In alternative embodiments, the power density ranges from 30 to 300 W/m ² or 30 to 75 W/m ² , or any value within these ranges. It is an advantage to the present invention that the conversion occurs under mild temperatures compared to conventional processes, that is, within about 10 and 150 °C. The pressure ranges from about 0.1 to about 30 bar relative. The reactant mixture comprising the alkane-containing gas and other reactants can be supplied with a space velocity that ranges between 1 and 200 h ¹ . The reaction can take place in any number of reactor shapes and types, including a flask reactor with an immersion well, and the reactor can be made from a number of materials including glass, PTFE, or stainless steel, among others. In certain embodiments, the LED source illuminates from within the reactor. In other embodiments, the source illuminates from outside of the reactor. Very advantageously, the process can be run continuously up to the lifespan of the LED source, so long as there is supply of reactants and timely collection of the methanesulfonyl halide.

[0010] The further reaction may comprise contacting the methane sulfonyl halide with a catalyst complex to form a methane monohalide. The methane monohalide may be further converted catalytically to any number of value-added chemicals known in the art, including, though not limited to, alcohols, olefins, aromatic compounds, or derivatives of any of these, as well as mixtures thereof. Any hydrogen halide released from steps described thus far may be either released for collection, and further converted to a halogen, which may be re-introduced into the overall process, for example at the step of reacting the methane-containing gas with the halogen in the presence of sulfur dioxide. [0011] Also advantageously, the inventive process is suitable for not only batch but also continuous reaction since the LED light source has a much longer lifespan. The overall hardware and operational cost in the present direct alkane conversion process when optimized can be significantly lower compared to conventional processes. Further advantageously, the alkanesulfonyl halides decompose to monohalogenated alkanes, which can be converted to multiple high-value chemicals and fuels, such as alcohols, olefins, aromatics, and other derivatives.

[0012] The present invention according to an embodiment is also directed to a method for converting a methane-containing gas to a methane sulfonyl halide comprising the step of reacting the methane-containing gas, under illumination by a light emitting diode (LED) source having a wavelength in the range of 150 to 1000 nm inclusive, with at least one of (a) a sulfuryl halide; or (b) a halogen in the presence of sulfur dioxide; wherein the step of reacting occurs in a reactor comprising an illumination power density in the reactor of from 3 to 1500 W/m ² ; and wherein the methane sulfonyl halide is obtained for isolation or further reaction. In an embodiment, the step of reacting occurs under a pressure ranging from 0.1 to 30 bar relative, inclusive and a reacting temperature of between 10 °C and 150 °C inclusive.

[0013] In an additional embodiment, the present invention is directed to a method for converting a methane-containing gas to a methane sulfonyl halide comprising the step of reacting the methane-containing gas, under illumination by a light emitting diode (LED) source having a wavelength in the range of 150 to 1000 nm inclusive, with at least one of (a) a sulfuryl halide; or (b) a halogen in the presence of sulfur dioxide; wherein the step of reacting occurs in a reactor comprising an illumination power density in the reactor of from 3 to 1500 W/m ² ; and wherein the methane sulfonyl halide is obtained for isolation or further reaction; wherein the step of reacting occurs under a pressure ranging from 0.1 to 30 bar relative, inclusive and a reacting temperature of between 10 °C and 150 °C inclusive; and wherein the method further comprises contacting the methane sulfonyl halide with a catalyst complex to form a methane monohalide; and catalytically converting the methane monohalide to an alcohol, an olefin, an aromatic, or mixtures thereof. [0014] These and other features of the invention are described below in more detail.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is process design diagram for the conversion from alkane to olefins.

[0016] FIG. 2 is a diagram of the photochemical reactor using an LED source for reacting

CH ₄ , Ch and S0 ₂ .

[0017] FIG. 3 is a plot showing quantum efficiency (QE) for reactions vs. moles of S0 ₂ supplied per 1 mole of CH ₄ and 1 mole of Ch at two temperatures (25 °C and 65 °C).

DETAILED DESCRIPTION

[0018] Definitions

[0019] Conversion% or conversion means moles of carbon transformed from reactants to products, converted to a percentage. For example, in the methane sulfochlorination reaction, conversion is calculated as follows: CH ₄ conversion% = (moles of reacted methane / moles of initial methane) * 100%.

[0020] Product selectivity or product selectivity % means product 1 divided by product 2, wherein product 1 is moles of a product times the number of carbon in that product molecule, and product 2 is the moles of the reacted carbon-containing reactant times the number of carbon in that reactant molecule. For example, in the methane sulfochlorination reaction, selectivity of the primary product methanesulfonyl chloride (MSC) is calculated as follows: MSC selectivity% = (moles of MSC * number of carbon in one MSC molecule) / (moles of reacted methane * 1) * 100%.

[0021] Product yield or product yield % means product 1 divided by product 2, wherein product 1 is moles of a product times the number of carbon in that product molecule, and product 2 is the moles of the initial carbon-containing reactant times the number of carbon in that reactant molecule. For example, in the methane sulfochlorination reaction, yield of the primary product methanesulfonyl chloride (MSC) is calculated as follows: MSC yield% = (moles of MSC * number of carbon in one MSC molecule) / (moles of initial methane * 1) *

100%.

[0022] (External) Quantum Efficiency (QE or EQE) means moles of the alkanesulfonyl halide product times the number of carbon in that product molecule divided by the moles of

P*t

emitted photon, as a percent, wherein moles of emitted photon = (wherein P is the power of the light source, t the reaction time, h the Planck constant, v the frequency of the photon, and NA the Avogadro constant). EQE is a measurement of the effectiveness of energy utilization in the photochemical process. For example, for MSC, EQE% = (moles of MSC * number of carbon in one MSC molecule / moles of emitted photon) * 100%.

[0023] Catalytic conversion means at least one kind of catalyst is used to accelerate the conversion of a reactive substance.

[0024] Space velocity means the volumetric flow rate of reactant(s) divided by the reactor volume. The space velocity defines how many reactor volumes of reactant(s) are processed per unit time.

[0025] The invention describes a process for the manufacturing of alkanesulfonyl halides from a reactive gas stream containing at least an alkane, a halogen (X ₂ , where X is chlorine, bromine, or iodine), and sulfur dioxide (SO2). Alternatively, the reactive gas stream contains at least an alkane and a sulfuryl halide (SO2X2). The reactive gas stream is passed through a conversion apparatus equipped with at least one source of LED light. In an embodiment, the conversion apparatus is a flask reactor with an immersion well. The reactor can be tubular or spherical. In certain embodiments, the reactor can be made from any of various materials, including glass, stainless steel, or polytetrafluoroethylene (PTFE). In one embodiment, the reactor comprises an outer shell and a transparent inner shell wherein the LED light is placed inside or on the surface of the inner shell to emit light outward towards the interior of the outer shell. The configuration of one conversion apparatus is shown in Fig 2. The light emitting diode (LED) source is configured into an illumination configuration such that illumination can occur from within the reactor, from outside the reactor onto the reactor (either from above or below the reactor), or combinations thereof. [0026] The effluent gas stream consists of alkane sulfonyl halides (considered the primary product), alkyl halides (considered the byproduct), and unreacted products: alkane, halogen, and S0 ₂ . In one embodiment, the reactive gas stream comprises methane (CH ₄ ), chlorine (Ck), and SO2, and the corresponding effluent gas stream comprises methanesulfonyl chloride (CH3SO2CI, MSC), methyl chloride (CH3CI), methylene chloride (CH2CI2), chloroform (CHC1- 3), carbon tetrachloride (CCU), and unreacted CH ₄ , Ck, and SO2. It is accepted in the art that CH ₄ is the most difficult alkane to convert. The embodiment described herein is an

advantageous method of converting CH ₄ into liquefied and transportable chemicals.

[0027] The composition of SO2 and X2 in the gas mixture may be adjusted according to different starting alkanes. Typically, 1 part of alkane is mixed with 0.2-5 parts of X2 and 1-20 parts of SO2 in the reactive gas stream. In a preferred embodiment, 1 part of CH ₄ is mixed with 0.8-1.2 parts of Ck and 3-15 parts of SO2. In another preferred embodiment, 1 part of CH ₄ is mixed with 0.9- 1.1 parts of Ck and SO2 being a range that is greater than 5 parts but less than 10 parts, or alternatively 6-8 parts. The sensitivity of the present inventive process wherein illumination is by an LED source (within a wavelength region of greater than 365 nm and less than 480 nm preferably) to changes in reactant ratio, especially with respect to the SO2 component, was surprising. A dramatic increase in EQE, two- to three-fold, when the

S0 ₂ :CH ₄ :Cl ₂ ratio was within a narrow range around 6.5: 1: 1, compared to 6:1:1 or less and 8:1:1 or greater, was greatly unexpected (see Fig. 3). This EQE improvement occurs within at least about 25 to 65 °C. In an additional preferred embodiment, 1 part of CH ₄ is mixed with 1 part of CI2 and 6.5 parts of SO2. SO2 and X2 can be mixed first to produce SO2X2 before being introduced to mix with the alkane gas. Alternatively, a source of SO2X2 produced in any suitable manner known in the art can be directly introduced for reaction.

[0028] The space velocity of the reactive gas stream ranges from 1 to 200 h ^-1 . In a preferred embodiment, the residence time of the reactive gas stream ranges from 10 to 100 h ¹ . In another preferred embodiment, the residence time of the reactive gas stream ranges from 20 to 40 h ¹ .

[0029] The LEDs used as the source of irradiation in this invention are monochromatic, and have a wavelength between 150 to 1000 nm. In a preferred embodiment, the LEDs have a wavelength between 350 to 480 nm. In another preferred embodiment, the LEDs have a wavelength between 445 to 455 nm.

[0030] The LEDs used in this invention can be discrete LEDs, surface mounted device (SMD) LEDs, chip-on-board (COB) LED modules, LEDs with primary and/or secondary optics (lenses, reflectors, TIR optics, etc.), LED lamps in different designs or shapes (bulbs, LED filament bulbs, tubes, corn cobs, etc.) or LED strips.

[0031] The illumination power density in the photo reactor, which is calculated by the power of LED light divided by the inner surface area of the reactor, ranges from 3 to 1500 W/m ² . In a preferred embodiment, the illumination power density ranges from 30 to 300 W/m ² . In another preferred embodiment, the illumination power density ranges from 30 to 75 W/m ² .

[0032] The internal pressure is controlled by a back-pressure regulator. The pressure ranges from 0.1 to 30 bar. In a preferred embodiment, the internal pressure is between 1 to 15 bar. In another preferred embodiment, the internal pressure is between 2 to 10 bar.

[0033] The reaction temperature ranges from 10 to 150 °C. In a preferred embodiment, the reaction temperature is controlled to be between 20 to 80 °C. In another preferred embodiment, the reaction temperature is controlled to be between 35 to 65 °C.

[0034] The reactor can be utilized for either batch or continuous flow processing. When continuous flow processing is adopted, the effluent gas can be cycled back to the reactor, or treated by for example absorption by base solutions. The liquid products, including the alkanesulfonyl halide and all forms of alkyl halides (C _a H _b X _c , X = Cl, Br or I), can be collected and subsequently separated. As is described in U.S. Patent No. 8,916,734 by Tang and Zhou, which is herein incorporated by reference in its entirety, alkanesulfonyl halides can decompose to alkyl halides and SO2 under mild conditions. SO2 can be re-utilized in the reaction, while CH ₃ CI can be converted by known methods in the art to ethylene or other high-value chemicals using zeolites as catalysts (U.S. Patent No. 2,899,473; and Jaumain and Su). In particular, the alkyl halide in the present inventive process can be further converted into different chemicals and fuels, such as alcohols, olefins and aromatics (U.S. Patent Nos. 7,091,391 and 5,001,293). Hydrogen halide is produced during the photochemical reaction as well as in the alkyl halide decomposition. The halides in the HX can be recovered by the catalytic oxidation of HX with molecular oxygen to produce halides and water, which is commonly known as the Deacon Process (Jones et al.). The HX can also be converted to halogen and hydrogen by electrolysis upon contact with a proton-exchange membrane (Sivasubramanian et al.), or be adsorbed by sodium hydroxide followed by electrolysis to form halogen and hydrogen.

[0035] EXAMPLES

[0036] The following examples illustrate the excellent reaction performance of the present alkane sulfohalogenation invention. These examples should in no way be read to limit or define the entire scope of the invention.

[0037] Quantification method: A gas chromatograph equipped with a flame ionization detector (FID) and a thermal conductivity detector (TCD) was used to analyze the effluent gas composition. The effluent gas was flowed through a xylene solution to remove the

alkanesulfonyl halide and alkyl halides. This was followed by treatment with an NaOH solution to absorb the unreacted Ch and S0 ₂ . The amount of CH ₄ and argon (or Ar) (internal standard) was analyzed online by FID and TCD. The liquid products in the xylene solution trapped from the reactor were analyzed offline to quantify the alkanesulfonyl halide and alkyl halides.

[0038] INVENTIVE EXAMPLE 1

[0039] A flask reactor configured as depicted in Figure 2 was used. A 3x1 W LED lamp with a wavelength of 455 nm was placed inside the immersion well of the flask. The corresponding power density is 30 W/m ² . The 3 LEDs were attached to every other side of a hexagonal base. Each LED illuminated a 180-degrees wide area, such that there was light coverage for the entire reactor. The LEDs were inserted and positioned to be at the center of the reactor. A mixture comprising the three reactants, with a mole ratio of CH ₄ :Cl ₂ :S0 ₂ = 1: 1:6.5, was flowed through the reactor. The space velocity for the reactants was 27 h ¹ . The reactor pressure was controlled at 3 bar by connecting the reactor outlet to a back-pressure regulator, and temperature was maintained at 25 °C. The LED lamp was turned on for 60 min for continuous reaction for the production of MSC. The effluent gas composition was analyzed by GC-FID and GC-TCD. Separately, the liquid products from the reactor collected in a xylene solution was analyzed by gas chromatography. The reaction performance is summarized in the following table.

Product Selectivity % External

MSC

CH ₄ conversion % Quantum

CH ₃ Cl CH2CI2 CHCb CCl ₄ MSC Yield %

Efficiency %

0.3 7.7 7.5 1.2 83.3 63.5 52.9 1684

[0040] INVENTIVE EXAMPLE 2 (Temperature)

[0041] In the flask reactor used in example 1, a 3x1 W LED lamp (455 nm wavelength) was positioned in the same manner as described in Inventive Example 1. The corresponding power density is 30 W/m ² . A mixture of the three reactants, having a molar ratio of CPL^ChiSCk = 1:1:6.5, was flowed through the reactor. The space velocity for the reactants was 27 h ¹ . The reactor pressure was controlled at 3 bar by connecting the reactor outlet to a back-pressure regulator. The reactor was heated and the temperature was kept at 65 °C during the reaction. The LED lamp was turned on for 60 min for continuous reaction for the production of MSC.

The effluent gas composition was analyzed by GC-FID and GC-TCD. Separately, the liquid products from the reactor collected in a xylene solution was analyzed by gas chromatography. The reaction performance is summarized in the following table.

Product Selectivity % External

MSC

CH ₄ conversion % Quantum

CH3CI CH2CI2 CHCb CCl ₄ MSC Yield %

Efficiency %

0.9 14.8 10.7 1.5 72.1 76.1 54.9 2019

[0042] INVENTIVE EXAMPLE 3 (Gas reactant ratio) [0043] In a flask reactor set up as in Inventive Example 1, a 3x1 W LED lamp (455 nm wavelength) was used. The corresponding power density is 30 W/m ² . A mixture of the three reactants, having a molar ratio of CH ₄ :Cl ₂ :S0 ₂ = 1:1:5, was flowed through the reactor. The space velocity for the reactants was 27 h ¹ . The reactor pressure was controlled at 3 bar by connecting the reactor outlet to a back-pressure regulator, and the temperature was kept at 25°C. The LED lamp was turned on for 60 min for continuous reaction to produce MSC. The effluent gas composition was analyzed by GC-FID and GC-TCD. Separately, the liquid products from the reactor collected in a xylene solution was analyzed by gas chromatography. The reaction performance is summarized in the following table.

Product Selectivity % External

MSC

CH ₄ conversion % Quantum

CH ₃ Cl CH2CI2 CHCb CCl ₄ MSC Yield %

Efficiency %

0.4 8.9 4.8 0.4 85.5 22.4 19.2 594

[0044] INVENTIVE EXAMPLE 4 (Gas reactant ratio)

[0045] In a flask reactor set up as in Inventive Example 1, a 3x1 W LED lamp (455 nm wavelength) was used. The corresponding power density is 30 W/m ² . A mixture of three reactants, having a molar ratio of CPL^ChiSCk = 1:1:10, was flowed through the reactor. The space velocity for the reactants is 27 h ¹ . The reactor pressure was controlled at 3 bar by connecting the reactor outlet to a back-pressure regulator, and the temperature was kept at 25°C. The LED lamp was turned on for 60 min for continuous reaction to produce MSC. The effluent gas composition was analyzed by GC-FID and GC-TCD. Separately, the liquid products from the reactor collected in a xylene solution was analyzed by gas chromatography. The reaction performance is summarized in the following table. Product Selectivity % External

MSC

CH ₄ conversion % Quantum

CH ₃ Cl CH2CI2 CHCb CCl ₄ MSC Yield %

Efficiency %

0.4 5.7 2.0 0 91.9 19.1 17.5 506

[0046] INVENTIVE EXAMPLE 5 (Wavelength)

[0047] In a flask reactor set up as in Inventive Example 1, a 3x1 W LED lamp (365 nm wavelength) was used. The corresponding power density is 30 W/m ² . A mixture of the three reactants, having a molar ratio of CH ₄ :Cl ₂ :S0 ₂ = 1:1:6.5, was flowed through the reactor. The space velocity for the reactants was 27 h ^-1 . The reactor pressure was controlled at 3 bar by connecting the reactor outlet to a back-pressure regulator, and the temperature was kept at 25°C. The LED lamp was turned on for 60 min for continuous reaction to produce MSC. The effluent gas composition was analyzed by GC-FID and GC-TCD. Separately, the liquid products from the reactor collected in a xylene solution was analyzed by gas chromatography. The reaction performance is summarized in the following table.

Product Selectivity % External

MSC

CH ₄ conversion % Quantum

CH ₃ CI CH ₂ CI ₂ CHCb CCl ₄ MSC Yield %

Efficiency %

0.6 9.8 4.9 0 84.7 19.8 16.8 655

[0048] INVENTIVE EXAMPLE 6 (Wavelength)

[0049] In a flask reactor set up as in Inventive Example 1, a 3x1 W LED lamp (480 nm wavelength) was used. The corresponding power density is 30 W/m ² . A mixture of the three reactants, having a molar ratio of CH ₄ :Cl ₂ :S0 ₂ = 1:1:6.5, was flowed through the reactor. The space velocity for the reactants was 27 h ¹ . The reactor pressure was controlled at 3 bar by connecting the reactor outlet to a back-pressure regulator, and the temperature was kept at 25°C. The LED lamp was turned on for 60 min for continuous reaction to produce MSC. The effluent gas composition was analyzed by GC-FID and GC-TCD. Separately, the liquid products from the reactor collected in a xylene solution was analyzed by gas chromatography. The reaction performance is summarized in the following table.

Product Selectivity % External

MSC

CH ₄ conversion % Quantum

CH ₃ Cl CH2CI2 CHCb CCl ₄ MSC Yield %

Efficiency % 0.6 5.6 1.4 0 92.4 12.0 11.1 301

[0050] INVENTIVE EXAMPLE 7 (Illumination power density)

[0051] In a flask reactor set up as in Inventive Example 1, a 3x2 W LED lamp (455 nm wavelength) was used. The corresponding power density is 60 W/m ² . A mixture of the three reactants, having a molar ratio of CH ₄ :Cl ₂ :S0 ₂ = 1:1:6.5, was flowed through the reactor. The space velocity for the reactants was 27 h ¹ . The reactor pressure was controlled at 3 bar by connecting the reactor outlet to a back-pressure regulator, and the temperature was kept at 25°C. The LED lamp was turned on for 60 min for continuous reaction to produce MSC. The effluent gas composition was analyzed by GC-FID and GC-TCD. Separately, the liquid products from the reactor collected in a xylene solution was analyzed by gas chromatography. The reaction performance is summarized in the following table.

Product Selectivity % External

MSC

CH ₄ conversion % Quantum

CH3CI CH2CI2 CHCb CCl ₄ MSC Yield %

Efficiency %

0.3 7.3 3.1 0.7 88.6 77.9 69.0 1033

[0052] COMPARATIVE EXAMPLE 1 (Conventional light) [0053] In a flask reactor set up as in Inventive Example 1, a 30 W ultra-violet mercury lamp was inserted and positioned to be at the center of the reactor. The corresponding power density is 300 W/m ² . A mixture of the three reactants, having a molar ratio of CH ₄ :Cl ₂ :S0 ₂ = 1: 1:6.5, was flowed through the reactor. The space velocity for the reactants was 27 h ¹ . The reactor pressure was controlled at 3 bar by connecting the reactor outlet to a back-pressure regulator, and the temperature was kept at 25 °C. The mercury light was turned on for 60 min for continuous reaction to produce MSC. The effluent gas composition was analyzed by GC-FID and GC-TCD. Separately, the liquid products from the reactor collected in a xylene solution was analyzed by gas chromatography. The reaction performance is summarized in the following table.

Product Selectivity % External

MSC

CH ₄ conversion % Quantum

CH ₃ Cl CH2CI2 CHCb CCl ₄ MSC Yield %

Efficiency % 2.5 3.6 6.0 3.8 84.1 51.5 43.3 137

[0054] COMPARATIVE EXAMPLE 2 (No S0 ₂ )

[0055] In a flask reactor set up as in Inventive Example 1, a 3x1 W LED lamp (455 nm wavelength) was used. The corresponding power density is 30 W/m ² . A mixture of CH ₄ and CI2 having a molar ratio of CH ₄ :Cl2 = 1:1 was flowed through the reactor. The space velocity for the reactants was 6 h ¹ . The reactor pressure was controlled at 3 bar by connecting the reactor outlet to a back-pressure regulator, and the temperature was kept at 25 °C. The LED lamp was turned on for 60 min for continuous reaction to produce MSC. The effluent gas composition was analyzed by GC-FID and GC-TCD. Separately, the liquid products from the reactor collected in a xylene solution was analyzed by gas chromatography. The reaction performance is summarized in the following table. This example shows SO2 to be an essential reactant for the generation of MSC. Product Selectivity % External

MSC

CH ₄ conversion % Quantum

CH ₃ Cl CH2CI2 CHCb CCl ₄ MSC Yield %

Efficiency %

3.5 50.5 39.0 7.0 85.5 0

[0056] Accordingly, it will be appreciated that the above-described embodiments are merely examples and should not be construed to narrow the scope or spirit of the invention in any way. The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention.