Method for non-metallic photo-driven oxidation of gaseous alkanes at room temperature

Abstract

The application discloses a method for non-metallic light-driven oxidation of gaseous alkane at room temperature. The application generates chlorine free radicals under ultraviolet light irradiation by reasonably selecting trichloroisocyanuric acid organic small molecules (TCCA), and realizes the activation and conversion of methane and other saturated alkanes at room temperature by hydrogen atom transfer (HAT) and methane oxidation, so as to obtain green methanol and formic acid liquid fuel. The organic small molecule catalyst generates chlorine free radicals and hydroxyl free radicals under ultraviolet light excitation, effectively accelerates saturated carbon hydrogen chemical reactions, the reaction condition is mild and efficient, the yield of methanol and formic acid products is high, the apparent quantum yield (AQY) is as high as 268%, the C 1 oxidation product selectivity is good, the catalyst is easy to recover, regenerate and reuse, and the application provides a practical solution for low-cost non-metallic light-driven activation and conversion of saturated C(sp 3 )‑H bonds.

Description

Technical Field

[0001] This invention belongs to the field of non-metallic photocatalysis technology, specifically relating to a method for non-metallic photo-driven oxidation of gaseous alkanes at room temperature. Background Technology

[0002] With rapid economic and social development, the consumption of traditional fossil fuels (such as oil, natural gas, and coal) is increasing daily, bringing non-renewable resources to the brink of depletion. Furthermore, the combustion of fossil fuels releases large amounts of harmful substances, endangering human health and causing a series of environmental problems, such as the greenhouse effect and air and water pollution. Therefore, carbon emissions and the energy crisis have become two major challenges to global development and progress. Developing efficient, clean, and low-cost methane activation and conversion technologies has become a global research hotspot. Since the greenhouse effect caused by methane emissions is more than 20 times that of the same amount of CO2, utilizing abundant solar energy to drive methane conversion will simultaneously meet the requirements of carbon-based green energy and dual-carbon goals, making it one of the most promising new unconventional strategies.

[0003] Carbon-hydrogen bond activation is a rapidly developing and popular field in recent years. Methane saturated C(sp...) 3 Direct functionalization reactions of C-H carbon-hydrogen bonds, due to their numerous advantages and immense challenges, are hailed as the "holy grail of chemistry" and have attracted increasing attention from scientists. The production of liquid fuels and basic chemicals using natural gas to replace petroleum has long been a key focus of scientific and industrial research. Methane, the main component of natural gas, is widely distributed in nature and is an abundant and readily available natural resource. It possesses tetrahedral symmetry and saturated C(sp...)... 3 The H-bond energy is as high as 435 kJ·mol⁻¹ -1 Methane is the most stable and cheapest small organic molecule in nature, and its selective activation and directional conversion have always been a global challenge. To date, the conversion and utilization of natural gas has basically remained at the level of traditional high-temperature reforming to produce syngas. Hydrogenation of syngas produces gray methanol, which not only involves large investments and high energy consumption with low carbon utilization, but also releases a large amount of carbon dioxide while obtaining the product, causing a huge impact on the ecological environment.

[0004] Photocatalysis is a promising technology and one of the ideal methods for driving CH4 conversion. Under the excitation of ultraviolet or visible light photons, photocatalysts are excited to a high-energy excited state, which alters the reaction pathway, lowers the activation energy, and even makes it possible for thermodynamic upslope reactions to occur under mild conditions. It can harvest solar energy and convert it into chemical energy, thus utilizing abundant and clean solar energy from nature to drive methane conversion, breaking thermodynamic limitations, providing green energy, and protecting the environment.

[0005] Currently, most photocatalytic methane oxidation systems require supported metals or noble metals as photocatalysts. These metal catalyst systems are prone to peroxidation to carbon dioxide, making it difficult to achieve the required selectivity for methane conversion and significantly increasing the cost of the methane conversion process. There are currently no reports of non-metallic photocatalytic conversion of methane to methanol and formic acid at room temperature. In the literature on metal-semiconductor photocatalytic methane oxidation, the simultaneous existence of small organic molecules such as methanol, formic acid, acetic acid, ethanol, peroxymethanol, and carbon dioxide has been observed, but the yields and selectivity of methanol and formic acid products are very low. The research goal of catalytic oxidation of methane to produce methanol and formic acid with high selectivity and high yield has not yet been achieved. More importantly, uncontrollable oxidation levels and over-oxidation pose significant challenges to CH4 activation and conversion. Therefore, developing a high-yield and highly selective non-metallic photocatalytic methane oxidation method and technology for the preparation of methanol and formic acid is of great significance. Summary of the Invention

[0006] This invention provides a method for the photo-driven oxidation of gaseous alkanes at room temperature using nonmetals. The method utilizes photo-irradiation of trichloroisocyanuric acid (TCCA) to generate chlorine radicals, which oxidize methane, achieving the synthesis of high-concentration methanol and formic acid solutions with a selectivity of 98%. This method avoids the peroxidation of CH4 to carbon dioxide, reducing the cost of separating the mixed liquid products. The highest yield of methanol in this method is 5919 μmol·h⁻¹. -1 The concentration can reach 0.296 M; the highest yield of formic acid is 10311 μmol·h⁻¹. -1 The concentration of formic acid can reach 0.5 M. After the catalyst is regenerated and the photocatalytic reaction is repeated 5 times, its production efficiency still remains above 93% of the highest production efficiency.

[0007] The present invention provides a method for non-metallic light-driven oxidation of gaseous alkanes at room temperature, comprising the following steps:

[0008] An aqueous solution of trichloroisocyanuric acid (TCCA) small molecule organic catalyst was prepared and added to a stainless steel high-pressure reactor. A mixed atmosphere of small molecule gaseous alkanes and oxygen in different proportions was introduced into the reactor. The reaction was carried out under closed and light-irradiated conditions for 1-12 hours to obtain the final product.

[0009] The small molecule gaseous alkane is a small molecule gaseous alkane such as methane, ethane, propane, or butane.

[0010] The pressure of gaseous alkanes is 2-60 atmospheres, and the pressure of oxygen is 1-20 atmospheres.

[0011] Furthermore, the total pressure inside the vessel is controlled to be 0.1-6.5 MPa. For example, 0.1 MPa, 1.0 MPa, 2.0 MPa, 3.0 MPa, 4.0 MPa, 5.0 MPa, 6.0 MPa, or 6.5 MPa.

[0012] The volume ratio of gaseous alkanes to oxygen is controlled between 3:1 and 6:1.

[0013] The amount of the trichloroisocyanuric acid organic small molecule catalyst (TCCA) used ranges from 0.2 to 5.8 mmol, for example, 0.9 mmol, 1.9 mmol, 3.7 mmol, 4.8 mmol or 5.7 mmol, corresponding to a concentration range of 22.5 to 145 mM.

[0014] The aqueous solution of the trichloroisocyanuric acid organic small molecule catalyst also contains a metal salt, which is one or more of NaCl, KCl, CsCl, RbCl, MgCl2, CaCl2, BaCl2, etc., with a concentration range of 0.1 M-0.8 M.

[0015] The wavelength range of the illumination is 200-450 nm, such as 254 nm, 365 nm, 390 nm, or 450 nm, and the optical power density is 10-4000 mW·cm⁻¹. -2 The distance between the light source and the reaction system is 0.5-10 cm. An LED light source with a wavelength of 365 nm and a power of 100 W is preferred; mercury lamps, xenon lamps, sunlight, etc., can also be selected as the light source.

[0016] Furthermore, the reaction temperature is 1-30℃.

[0017] Taking CH4 as an example, the catalytic reaction route is as follows:

[0018] .

[0019] The trichloroisocyanuric acid organic small molecule catalyst (TCCA) can be commercially available or prepared using conventional methods. The prepared TCCA is indistinguishable from commercially available high-purity TCCA.

[0020] The photocatalytic reaction system of the present invention includes a solid-liquid-gas three-phase system, a liquid-solid two-phase system, or a gas-solid two-phase system, preferably a solid-liquid-gas three-phase system.

[0021] This invention focuses on the conversion and utilization of carbon-based energy, providing an application for the room-temperature, non-metallic, photo-driven oxidation of methane to methanol and formic acid. It addresses key scientific issues related to the photo-driven activation and functionalization of low-carbon hydrogens such as methane at room temperature. By rationally selecting organic small-molecule photocatalysts, chlorine and hydroxyl radicals are generated under ultraviolet light excitation, efficiently achieving the catalytic oxidation of methane. The activation and conversion of low-carbon hydrogens such as methane are carried out at room temperature and in an aqueous phase. The reaction is mild and efficient, with high yields and good selectivity of methanol and formic acid products. This method is suitable for photo-driven oxidation of inert C(sp) hydrocarbons such as methane. 3 It provides practical solutions for the activation and transformation of H-bonds.

[0022] This invention uses trichloroisocyanuric acid as an organic small molecule catalyst, which can effectively utilize sunlight to drive the catalytic oxidation of alkanes. The energy source is clean and readily available. It can achieve saturated carbon-hydrogen bond activation under simple and mild conditions, and directly dehydrogenate. At room temperature, the selectivity for methanol and formic acid conversion can reach more than 90%. Attached Figure Description

[0023] Figure 1 This invention provides a trichloroisocyanuric acid organic small molecule catalyst, which is a white powder.

[0024] Figure 2 This is the XRD pattern of a trichloroisocyanuric acid organic small molecule catalyst. (Example:) Figure 2 As shown, the diffraction peaks of trichloroisocyanuric acid crystals conform to the standard PDF card #31-1956.

[0025] Figure 3 This is the infrared spectrum of the trichloroisocyanuric acid photocatalyst.

[0026] Figure 4 This is the standard curve for methanol. Sodium 3-trimethylsilyl-1-propanesulfonate (DSS) was used as an internal NMR standard. The methanol concentration was plotted on the ordinate, and the ratio of the integrated areas of the methyl hydrogen of methanol and the methyl hydrogen of DSS in the hydrogen NMR spectrum of D2O was plotted on the abscissa.

[0027] Figure 5 This is the standard curve for formic acid. Sodium 3-trimethylsilyl-1-propanesulfonate (DSS) was used as an internal NMR standard. The formic acid concentration was plotted on the ordinate, and the ratio of the integrated areas of the 1H NMR spectra of formic acid aldehyde hydrogen and DSS methyl hydrogen in D2O was plotted on the abscissa.

[0028] Figure 6 This is the standard curve for acetic acid. Sodium 3-trimethylsilyl-1-propanesulfonate (DSS) was used as an internal NMR standard. The acetic acid standard curve was plotted with the acetic acid concentration as the ordinate and the ratio of the integral area of ​​the methyl hydrogen of acetic acid and the methyl hydrogen of DSS in the hydrogen NMR spectrum of D2O as the abscissa.

[0029] Figure 7 This is the standard curve for ethanol. Sodium 3-trimethylsilyl-1-propanesulfonate (DSS) was used as an internal NMR standard. The methanol concentration was plotted on the ordinate, and the ratio of the integrated areas of the methyl hydrogen of ethanol and the methyl hydrogen of DSS in the hydrogen NMR spectrum of D2O was plotted on the abscissa.

[0030] Figure 8 This is the standard curve for acetone. Sodium 3-trimethylsilyl-1-propanesulfonate (DSS) was used as an internal NMR standard. The methanol concentration was plotted on the ordinate, and the ratio of the integrated areas of the methyl hydrogen of acetone and the methyl hydrogen of DSS in the hydrogen NMR spectrum of D2O was plotted on the abscissa.

[0031] Figure 9 This is the standard curve for propionic acid. Sodium 3-trimethylsilyl-1-propanesulfonate (DSS) was used as an internal NMR standard. The standard curve for propionic acid was plotted with methanol concentration as the ordinate and the ratio of the integrated areas of the methyl hydrogen of propionic acid and the methyl hydrogen of DSS in the hydrogen NMR spectrum of D2O as the abscissa.

[0032] Figure 10 It is the 1H NMR spectrum of nonmetallic light-driven methane activation to methanol and formic acid.

[0033] Figure 11 The image shows the purified methanol and formic acid products.

[0034] Figure 12 yes 13 1H NMR spectra of the carbon-13 isotopes of CH4 oxidized to methanol and formic acid ( 1 H NMR).

[0035] Figure 13 yes 13 Carbon-13 nuclear magnetic resonance spectra of the carbon-13 isotopes of CH4 after conversion to methanol and formic acid ( 13 C NMR).

[0036] Figure 14 This is a schematic diagram of the catalytic reaction mechanism of the present invention. Detailed Implementation

[0037] The technical solution of the present invention will be further analyzed and described below through specific embodiments. Unless otherwise stated, the raw materials and reagents used in the following embodiments are commercially available products, or can be prepared by known methods.

[0038] Example 1:

[0039] Synthesis of trichloroisocyanuric acid (TCCA) organic small molecule catalyst: 350 g urea was heated at 300 ℃ for 5 hours to dehydrate and generate cyanuric acid (CA); 96 g cyanuric acid and 90 g KOH were added to 1000 mL of aqueous solution (pH 14), and sonicated for 20 minutes until the cyanuric acid was completely dissolved. The solution was cooled to 0 ℃, and chlorine gas was passed through it for 1 hour with continuous stirring, producing a white precipitate and lowering the pH of the solution to 3; the pH of the solution was then adjusted to 14 with KOH, and chlorine gas was passed through it for 1 hour, producing a colorless precipitate and lowering the pH of the solution to 3; the pH of the solution was then adjusted to 14 with KOH, and chlorine gas was passed through it for 1 hour, producing a colorless precipitate. The precipitate was filtered, washed with cold water and acetonitrile, and dried under reduced pressure to obtain trichloroisocyanuric acid organic small molecule oxidant (white crystalline powder, yield 86%).

[0040] like Figure 1 The trichloroisocyanuric acid organic small molecule photocatalyst shown is a white powder, and its X-ray diffraction pattern is as follows. Figure 2 As shown, the infrared spectrum is as follows Figure 3 As shown.

[0041] Example 2:

[0042] 5.7 mmol TCCA was dispersed in 43 mL of deionized water to obtain a 132.6 mM TCCA aqueous solution. 0.3 M NaCl was then added, and the solution was transferred to a 130 mL high-pressure reactor. 9 atm O2 and 52 atm CH4 were introduced, and the reactor was continuously stirred under 100 W, 365 nm LED light at room temperature for 2 hours. D2O was used as the deuterated reagent, and sodium 3-trimethylsilyl-1-propanesulfonate (DSS) was used as the NMR internal standard. A standard curve was plotted with methanol and formic acid concentrations on the ordinate and the ratio of the integral areas of methanol, formic acid, and DSS in the 1H NMR spectra of D2O on the abscissa. Figure 4 , Figure 5 As shown. Nuclear magnetic resonance spectroscopy was used to analyze the target products methanol and formic acid, as follows. Figure 10 As shown, a chemical shift of 3.35 ppm corresponds to a hydrogen atom on the methyl group of methanol, confirming the product as methanol, with a maximum concentration of 0.23 M and a yield of 4858 μmol·h⁻¹. -1 A chemical shift of 8.23 ​​ppm corresponds to a hydrogen atom on the methyl group of formic acid, confirming the product as formic acid. Its highest concentration reaches 0.31 M, with a yield of 6749 μmol·h⁻¹. -1 The selectivity of the C1 products of methanol and formic acid is >98.8%, and the apparent quantum yield (AQY) is as high as 194%.

[0043] Example 3:

[0044] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a 142.5 mM TCCA aqueous solution. Then, 0.3 M NaCl was added. The solution was transferred to a 130 mL high-pressure reactor, and 9 atm O2 and 52 atm CH4 were introduced. The reactor was continuously stirred under 100 W, 365 nm LED light illumination at room temperature for 2 hours. The methanol product concentration reached 0.30 M, with a yield of 5919 μmol·h⁻¹. -1 The highest concentration of the formic acid product can reach 0.52 M, with a yield of 10311 μmol·h⁻¹. -1 The apparent quantum yield (AQY) of the methanol and formic acid products was as high as 268%. The reaction mixture was collected, and the products were further separated to obtain methanol with a purity of 99.5% and formic acid with a purity of 99.8%. Figure 11 As shown.

[0045] Example 4:

[0046] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a 142.5 mM TCCA aqueous solution. 0.3 M NaCl was then added, and the solution was transferred to a 130 mL high-pressure reactor. 5 atm O2 and 25 atm CH4 were introduced, and the reactor was continuously stirred under 100 W, 365 nm LED illumination at room temperature for 2 hours. The methanol product concentration was 0.14 M, and the yield was 2993 μmol·h⁻¹. -1 The formic acid product concentration was 0.19 M, and the yield was 4209 μmol·h⁻¹. -1 .

[0047] Example 5:

[0048] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a TCCA aqueous solution with a concentration of 142.5 mM. Then, 0.3 M NaCl was added. The solution was transferred to a 130 mL high-pressure reactor, and 3 atm O2 and 10 atm CH4 were introduced. The reactor was continuously stirred under LED light with a power of 100 W and a wavelength of 365 nm and reacted at room temperature for 2 hours. The methanol product concentration was 0.033 M, and the yield was 711 μmol·h⁻¹. -1 The formic acid product concentration was 0.087 M, and the yield was 1878 μmol·h⁻¹. -1 .

[0049] Example 6:

[0050] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a 142.5 mM TCCA aqueous solution. Then, 0.3 M CsCl was added. The solution was transferred to a 130 mL high-pressure reactor, and 9 atm O2 and 52 atm CH4 were introduced. The reactor was continuously stirred under 100 W, 365 nm LED illumination at room temperature for 2 hours. The methanol product concentration reached 0.18 M, with a yield of 3669 μmol·h⁻¹. -1 The formic acid product concentration can reach 0.32 M, with a yield of 6338 μmol·h⁻¹. -1 .

[0051] Example 7:

[0052] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a TCCA aqueous solution with a concentration of 142.5 mM. Then, 0.3 M KCl was added. The solution was transferred to a 130 mL high-pressure reactor, and 9 atm O2 and 52 atm CH4 were introduced. The reactor was continuously stirred under 100 W, 365 nm LED light and reacted at room temperature for 2 hours. The methanol product concentration reached 0.08 M, and the formic acid product concentration reached 0.19 M.

[0053] Example 8:

[0054] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a 142.5 mM TCCA aqueous solution. Then, 0.3 M MgCl2 was added. The solution was transferred to a 130 mL high-pressure reactor, and 9 atm O2 and 52 atm CH4 were introduced. The reactor was continuously stirred under 100 W, 365 nm LED illumination at room temperature for 2 hours. The methanol product concentration reached 0.14 M, with a yield of 2777 μmol·h⁻¹. -1 The formic acid product concentration can reach 0.15 M, with a yield of 3011 μmol·h⁻¹. -1 .

[0055] Example 9:

[0056] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a 142.5 mM TCCA aqueous solution. Then, 0.3 M CaCl2 was added. The solution was transferred to a 130 mL high-pressure reactor, and 9 atm O2 and 52 atm CH4 were introduced. The reactor was continuously stirred under 100 W, 365 nm LED illumination at room temperature for 2 hours. The methanol product concentration reached 0.14 M, with a yield of 2769 μmol·h⁻¹. -1The concentration of formic acid product can reach 0.17 M, with a yield of 3326 μmol·h⁻¹. -1 .

[0057] Example 10:

[0058] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a TCCA aqueous solution with a concentration of 142.5 mM. Then, 0.3 M NaCl was added. The solution was transferred to a 130 mL high-pressure reactor, and 9 atm O2 and 52 atm CH4 were introduced. Under 100 W, 365 nm LED illumination, the mixture was continuously stirred and reacted at room temperature for 1, 3, 4, 6, and 12 hours, respectively. The methanol product concentrations reached 0.11 M, 0.13 M, 0.09 M, 0.07 M, and 0.07 M, respectively. The formic acid product concentrations reached 0.15 M, 0.16 M, 0.15 M, 0.18 M, and 0.24 M, respectively.

[0059] Example 11: (Cyclic Experiment)

[0060] The cyanuric acid (CA) from the reaction in Example 3 was separated, washed with water, regenerated, and converted into trichloroisocyanuric acid for use in the recycling experiment. The regeneration method employed conventional sodium cyanurate chlorination to recover the CA from the reaction, yielding TCCA. Specific methods can be found in existing technologies, such as Monsanto Company. Process for preparing trichloro-cyanuric acid: US2956056[P]. 1960-10-11.

[0061] The regenerated 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a 142.5 mM TCCA aqueous solution. Then, 0.3 M NaCl was added, and the solution was transferred to a 130 mL high-pressure reactor. 9 atm O2 and 52 atm CH4 were introduced, and the mixture was continuously stirred under 100 W, 365 nm LED illumination at room temperature for 2 hours. After four cycles, the methanol product concentrations reached 0.29 M, 0.30 M, and 0.28 M. The formic acid product concentrations reached 0.50 M, 0.49 M, 0.48 M, and 0.49 M, with no significant decrease in yield.

[0062] Example 12: (Isotope Experiment)

[0063] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a TCCA aqueous solution with a concentration of 142.5 mM. Then, 0.3 M NaCl was added. The solution was transferred to a 130 mL high-pressure reactor, and 5 atm O2 and 5 atm O2 were introduced. 13 CH4 ( 13 C isotope methane) and 20 atm 12 CH4 was reacted under continuous stirring at room temperature for 2 hours under 100 W, 365 nm LED illumination. The methanol product concentration was 0.15 M, and the yield was 2968 μmol·h⁻¹. -1 The formic acid product concentration was 0.27 M, and the yield was 5267 μmol·h⁻¹. -1 . 1 H NMR and 13 C NMR indicates that the carbon atoms in both methanol and formic acid originate from methane. Figure 12 , Figure 13 As shown. The reaction mechanism for the conversion of methane to methanol and formic acid is shown in [reference needed]. Figure 14 .

[0064] Example 13:

[0065] 4.8 mmol TCCA was dispersed in 40 mL of deionized water to obtain a 120 mM TCCA aqueous solution. Then, 0.3 M NaCl was added. The solution was transferred to a 130 mL high-pressure reactor, and 9 atm O2 and 38 atm ethane were introduced. The reactor was continuously stirred under 100 W, 365 nm LED illumination at room temperature for 2 hours. The ethanol product concentration was 0.032 M, and the yield was 678 μmol·h⁻¹. -1 The concentration of the acetic acid product was 0.102 M, and the yield was 2199 μmol·h⁻¹. -1 .

[0066] Example 14:

[0067] 3.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a 92.5 mM TCCA aqueous solution. Then, 0.3 M NaCl was added, and the solution was transferred to a 130 mL high-pressure reactor. 3 atm O2 and 8 atm propane were introduced, and the mixture was continuously stirred under 100 W, 365 nm LED illumination at room temperature for 2 hours. DSS was used as an internal standard for NMR, and the target product, acetone, was quantitatively analyzed using NMR spectroscopy. According to the standard curve, the acetone product concentration was 0.13 M, and the yield was 2502 μmol·h⁻¹. -1 The concentration of propionic acid product was 0.05 M, and the yield was 1038 μmol·h⁻¹. -1.

[0068] Example 15:

[0069] 1.9 mmol TCCA was dispersed in 40 mL of deionized water to obtain a 47.5 mM TCCA aqueous solution. 0.3 M NaCl was then added, and the solution was transferred to a 130 mL high-pressure reactor. 10 atm O2 and 50 atm CH4 were introduced, and the reaction was carried out under full-spectrum illumination with a 300 W xenon lamp without filters for 2 h at room temperature with continuous stirring. Using DSS as an internal standard for NMR, NMR spectroscopy confirmed that the product was methanol with a concentration of 6.84 mM and a yield of 137 μmol·h⁻¹. -1 .

[0070] Example 16:

[0071] 5.7 mmol TCCA was dispersed in 40 mL of deionized water to obtain a TCCA aqueous solution with a concentration of 142.5 mM. Then, 0.3 M NaCl was added, and 2 atm O2 and 10 atm natural gas were bubbled through. The mixture was continuously stirred under 100 W, 365 nm LED light and reacted at room temperature for 2 hours. The product concentrations were: methanol 5 mM, formic acid 13 mM, acetic acid 35 mM, and acetone 9 mM.

[0072] Example 17:

[0073] 5.7 mmol TCCA was dispersed in 40 mL of seawater and transferred to a 130 mL high-pressure reactor. 9 atm O2 and 52 atm CH4 were introduced, and the mixture was continuously stirred under 100 W, 365 nm LED illumination at room temperature for 2 hours. The methanol product concentration reached 0.11 M, and the formic acid product concentration reached 0.16 M.

[0074] Example 18:

[0075] 5.7 mmol TCCA was dispersed in 40 mL of seawater and transferred to a 130 mL high-pressure reactor. 9 atm O2 and 52 atm CH4 were introduced, and the mixture was continuously stirred under 100 W, 365 nm LED illumination at a low temperature of 1°C for 2 hours. The methanol product concentration reached 0.14 M, and the formic acid product concentration reached 0.17 M.

[0076] Example 19:

[0077] 5.7 mmol TCCA was dispersed in 43 mL of seawater and transferred to a 130 mL high-pressure reactor. 9 atm O2 and 52 atm CH4 were introduced, and the mixture was continuously stirred under 100 W, 365 nm LED illumination at room temperature for 1 hour. The methanol product concentration reached 0.19 M, and the formic acid product concentration reached 0.18 M.

[0078] Example 20:

[0079] 5.7 mmol TCCA was dispersed in 43 mL of seawater and transferred to a 130 mL high-pressure reactor. 9 atm O2 and 52 atm CH4 were introduced, and the mixture was continuously stirred under 100 W, 365 nm LED illumination at a low temperature of 1°C for 2 hours. The methanol product concentration reached 0.18 M, and the formic acid product concentration reached 0.29 M.

[0080] Example 21:

[0081] 5.7 mmol TCCA was dispersed in 40 mL of deionized water and transferred to a 130 mL high-pressure reactor. 0.3 M CsCl was added, and 9 atm O2 and 52 atm CH4 were introduced. The mixture was continuously stirred under 100 W, 365 nm LED illumination and reacted at 1 °C for 2 hours. The methanol product concentration reached 0.11 M, and the formic acid product concentration reached 0.15 M.

[0082] Examples 2-3 investigated the effect of H2O volume on the yield of C1 products; Examples 3-5 investigated the optimal ratio of methane to oxygen under low, medium, and high pressure conditions; Examples 6-9 investigated the effect of adding different metal salts on the yield of C1 products; Example 10 investigated the effect of different reaction times on the yield of C1 products; Example 11 conducted four recycling experiments with the recovered TCCA to investigate the feasibility of TCCA recycling; Example 12 used a portion of... 13 CH4 substitution 12 Isotope tracing experiments of CH4 were conducted and confirmed that the C1 product originated from methane; Examples 13-14 investigated the reactivity of gaseous alkanes other than methane, such as ethane and propane; Example 15 studied the reactivity under a xenon lamp of all wavelengths; Example 16 studied the reactivity of commercially available natural gas; Examples 17-20 studied the yield of C1 product in different volumes of seawater at different temperatures; Example 21 studied the reactivity at low temperatures when NaCl was replaced with CsCl in deionized water.

[0083] Based on the data comparison of the above embodiments, the amount of the trichloroisocyanuric acid organic small molecule catalyst used is 5 mM-145 mM, preferably 50 mM-140 mM. The reaction temperature is 1-30℃, preferably 1-25℃, and the reaction time is 0.5-12 h, preferably 1-4 h. The aqueous solution is a salt aqueous solution such as NaCl, KCl, CsCl, RbCl, MgCl2, CaCl2, or BaCl2, with a concentration of 0.1 M-0.8 M, preferably 0.15 M-0.35 M. The methane pressure is 2-60 atm, preferably 15-52 atm. The oxygen pressure is 1-20 atm, preferably 3-9 atm.

[0084] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for non-metallic photo-driven oxidation of gaseous alkanes at room temperature, characterized in that... Includes the following steps: An aqueous solution of trichloroisocyanuric acid organic small molecule catalyst was prepared and added to a stainless steel high-pressure reactor. The reactor was then filled with a mixed atmosphere of small molecule gaseous alkanes and oxygen. The reaction was carried out under sealed and light-illuminated conditions for 1-12 hours to obtain the final product.

2. The method according to claim 1, characterized in that: The small molecule gaseous alkane is methane, ethane, propane, or butane.

3. The method according to claim 1, characterized in that: The pressure of gaseous alkanes is 2-60 atmospheres, and the pressure of oxygen is 1-20 atmospheres.

4. The method according to claim 3, characterized in that: The total pressure inside the vessel is controlled between 0.1 and 6.5 MPa.

5. The method according to claim 4, characterized in that: The volume ratio of gaseous alkanes to oxygen is controlled between 3:1 and 6:

1.

6. The method according to claim 1, characterized in that: In the reaction system, the concentration range of the trichloroisocyanuric acid organic small molecule catalyst is 22.5-145 mM.

7. The method according to claim 1, characterized in that: The aqueous solution of the trichloroisocyanuric acid organic small molecule catalyst also contains a metal salt, which is one or more of NaCl, KCl, CsCl, RbCl, MgCl2, CaCl2, and BaCl2.

8. The method according to claim 7, characterized in that: The concentration of the metal salt in the reaction system ranges from 0.1 M to 0.8 M.

9. The method according to claim 1, characterized in that: The wavelength range of the illumination is 200-450 nm, and the optical power density is 10-4000 mW·cm⁻¹. -2 The distance between the light source and the reaction system is 0.5-10 cm.

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