Photoactivated inverse Boodor process

Abstract

This invention discloses a photo-assisted photochemical process for converting carbonaceous materials and carbon dioxide into carbon monoxide under ambient operating conditions, as well as a system for such a process.

Description

[Technical Field]

[0001] The present invention relates to a method for synthesizing carbon monoxide gas from solid carbon or carbon dioxide gas using a light-driven reverse Boudouard reaction. According to the present invention, the reverse Boudouard reaction can proceed under more sustainable and viable conditions than currently used by methods using sunlight and / or light-emitting diodes, which can operate continuously (24 / 7) by silicon solar cells and / or lithium-ion batteries to provide the necessary light. The present invention is suitable for synthesizing carbon monoxide in a practical and environmentally friendly manner using carbon dioxide and various forms of carbonaceous materials, including but not limited to carbon black, biochar, and carbonaceous waste. [Background technology]

[0002] Syngas, or synthesis gas, is a fuel gas mixture primarily composed of hydrogen (H2), carbon monoxide (CO), and potentially carbon dioxide (CO2). It is used, for example, as an intermediate in the production of hydrocarbon fuels such as diesel fuel and methanol in the creation of synthetic natural gas, and in the production of industrial chemicals such as ammonia and methanol. Currently, industrial production of syngas is carried out through steam methane reforming and / or coal or coke steam gasification. Syngas can also be obtained from pyrolysis initiated from residues, biomass, and waste. All of these methods are energy-intensive and have a significant carbon footprint.

[0003] Conventional attempts at more environmentally considerate carbon monoxide production (manufacture) typically utilize the steam gasification of fossil fuels, biomass, and / or waste through the self-combustion of carbonaceous raw materials. In particular, scaling up this technology is limited by high required temperatures, ash melting, and tar fouling. Additionally, generally in steam gasification, the carbon footprint is large, injection of pure oxygen is required, and combustion-related contaminants such as dioxins and furans are produced.

[0004] The reverse Boudouard reaction is used to convert carbon and carbon dioxide to carbon monoxide under fully thermally driven conditions at temperatures up to 900 °C (in accordance with the reaction represented by the following formula (1)). Such high temperatures cause technical difficulties associated with large-scale high-temperature energy load operations, which limit the utilization of this reaction. C + CO2 → 2CO ΔH° 298K = +172 kJ / mol Alkali metal catalysts, alkaline earth metal catalysts, and transition metal catalysts have been shown to be able to reduce the required reverse Boudouard reaction temperature to a limited extent, but the degradation of the reactor due to catalyst melting and precipitation is an issue for the level of practical application.

[0005] The global CO market is expected to reach $6.643 billion by the end of 2026 and is growing at an annual growth rate of 2.7% in total between 2021 and 2026. SUMMARY OF THE INVENTION

[0006] The present invention encompasses a method and apparatus for the preparation of carbon monoxide-containing syngas by an improved inverse Boudor process, while avoiding the extremely high working temperatures required for carbon monoxide production (manufacturing) under fully thermally driven conditions. Surprisingly, the light-driven inverse Boudor process has been found to enable the effective conversion of carbonaceous materials to carbon monoxide using sunlight or LED-based lighting, with or without additional heating, and without the heating required in the prior art. The process of the present invention is carried out in either a batch or flow reactor in which a solid carbonaceous material is brought into contact with a gaseous medium containing carbon dioxide in an environment where the interface between the solid carbonaceous material and carbon dioxide is irradiated with light. The reaction occurs on the surface of the solid carbonaceous material and consumes nearly equimolar amounts of both carbon and carbon dioxide, consuming all carbon atoms and all carbon dioxide molecules to produce two carbon monoxide molecules.

[0007] While sunlight can be used to reduce the heat required for the reaction, its intermittency may limit its effectiveness. According to the solution proposed by this invention, CO can be produced by a photo-driven reverse Boudouard reaction using light-emitting diodes (LEDs) instead of natural light; the LEDs may be powered by the energy and production storage capacity of silicon solar cells and lithium-ion batteries. This photochemical reverse Boudouard reaction allows for continuous CO production under ambient conditions without interruption (24-7), even without sunlight or continuous power.

[0008] Sunlight and LED light may be filtered to optimize the wavelength of light irradiated onto the carbonaceous material. The LEDs used to generate the LED light may be selected to produce the desired wavelength of light.

[0009] According to the chemical phenomena of this invention, carbonaceous waste or any carbonaceous material and greenhouse gas CO2 can be sustainably converted into value-added useful chemicals without complicating matters related to extreme operating temperatures. The viability of this platform represents a step towards decarbonization for many large-scale industries. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram showing one embodiment of a laboratory-scale batch reactor used to perform some of the tests described in this book. [Figure 2] Figure 2 is a schematic diagram showing one embodiment of a laboratory-scale continuous flow reactor used to perform some of the tests described in this book. A photoflow reactor is constructed of heatable stainless steel or glass and facilitates the flow of gas through a fixed reactant bed. [Figure 3] Figure 3 shows the CO production rates when using a photo-driven inverse Boodoo reaction with several carbon sources using a Xe lamp with an irradiation intensity of 12.7 W cm-2. [Figure 4] Figure 4 shows the CO production rate obtained during a power intensity study using a CnB CABOT sample to confirm the photochemical behavior of CO production rate at intensities lower than 21 W cm-2 (R2=0.998). [Figure 5] Figure 5 illustrates the CO generation rate used in the study of the wavelength dependence of ultra-high purity CnB and CABOT CnB samples when heated to 350°C (until the photothermal effect is neutralized) at a light intensity of 15 W cm-2. [Figure 6] Figure 6 shows the CO production rate under dark and light conditions in the temperature range of 500-560°C using a photoflow reactor. [Figure 7] Figure 7 illustrates the amount of CO produced and the decrease in mass of the carbonaceous material sample used in the photothermal inverse Boudouard reaction without external heating. The Xe lamp intensity was set to 34.1 W cm⁻². Measurements were performed three times. For tests a, b, d, and f, the irradiation time and reactor pressure were set to 5 minutes and 24-30 psig per CO₂, respectively, without external heating. [Figure 8] Figure 8 illustrates the CO production rates in the reverse Boodoa reaction at various light intensity levels, using natural sunlight irradiation and red LED lighting on a rooftop. [Figure 9] Figure 9 illustrates the effect of varying light intensity using several light filters on CO generation. [Figure 10a] Figure 10a shows the CO generation rate when using different colors of LED lighting at various light intensity levels. [Figure 10b] Figure 10b shows the CO generation rate when using different colors of LED lighting at various light intensity levels. [Figure 10c] Figure 10c shows the CO generation rate when using different colors of LED lighting at various light intensity levels. [Figure 10d] Figure 10d shows the CO generation rate when using different colors of LED lighting at various light intensity levels. [Figure 10e] Figure 10e shows the CO generation rate when using different colors of LED lighting at various light intensity levels. [Modes for carrying out the invention]

[0011] According to one embodiment of the present invention, when a carbonaceous material is exposed to and brought into contact with gaseous carbon dioxide, the use of high temperatures required to convert the carbonaceous material and the gas medium containing carbon dioxide to carbon monoxide can be avoided by irradiating the carbonaceous material with light. The gaseous carbon dioxide medium may optionally include an inert gas such as argon.

[0012] According to another embodiment of the present invention, the method of the present invention may be carried out at ambient temperature or with increased temperature. The method may be carried out with increased temperature to about 560°C, which is lower than the temperature required in conventional reverse Boodor processes. It has been shown that the CO2 production rate is increased by this method.

[0013] According to another embodiment of the present invention, the method of the present invention may be carried out in a batch or flow process at a pressure of about 24 to 30 psi or a pressure within the range of the skill and knowledge of those skilled in the art.

[0014] According to yet another embodiment of the present invention, the method of the present invention is about 10 W cm -2 Light intensity exceeding or approximately 12 to 90 W / cm² -2 This may be carried out using a wide range of light intensities. It has been shown that the conversion of carbonaceous materials and carbon dioxide to carbon monoxide occurs at the aforementioned intensities. The light intensity may be increased in the case of sunlight by using a magnifying lens to collect light incident on a smaller surface, or in the case of light-emitting diodes by increasing the power of the LED.

[0015] According to yet another embodiment of the present invention, the wavelength of light used in the light-assisted reverse-Boudouard process of the present invention may be selected or adjusted to improve the efficiency of the conversion of carbonaceous material and carbon dioxide to carbon monoxide. Alternatively, the wavelength of light generated by the LED may be selected or adjusted by selecting an LED that generates wavelengths of light directed towards the red tip of the visible light spectrum.

[0016] The viability of the Photochemical Reverse Boudouard Process may be verified by a comparative techno - economic analysis. Table 1 below summarizes the CO production rates in conventional methods using heat and microwave radiation, compared with the sunlight and LED methods of the present invention. The results clearly show that sunlight and light - emitting diodes enable a sustainable path for the reverse Boudouard reaction under environmentally - considerate conditions to effectively produce renewable and valuable raw material CO. The results of heat and microwave of the prior art shown in Table 1 are cited from Hunt, J et al. "Microwave - Specific Enhancement of the Carbon - Carbon dioxide Boudouard Reaction" J. Phys. Chem. C 117, 26871 - 26880 (2013).

[0017]

Table 1

[0018] To examine the effect of light irradiation on carbonaceous materials for the conversion of carbonaceous materials to carbon monoxide and the simultaneous conversion of carbon dioxide to carbon monoxide, the experiments were carried out in a laboratory - scale reactor schematically shown in Figures 1 and 2.

[0019] For carbon black (C n B), it was purchased from CABOT Corporation (VULCAN XC72R GP - 3921) and used as received. This material was found to have a surface area of 216 m 2 g -1 . Carbon nanotubes, natural graphite, carbon black ( 13 C n B) and carbon 13 C carbon dioxide ( 13For CO2 (99%), we purchased it from Sigma-Aldrich and used it as is. For ultra-high purity carbon black, we purchased it from AlfaAesar. For carbon dioxide (99.9% purity, purchased from Praxair), we passed it through a dry alumina column before use. For the carbon black sample, we suspended it in diluted water, allowed it to stand in an ultrasonic bath for 30 minutes, and then dropped it onto a glass fiber filter under vacuum using a Pasteur pipette. After drying this sample in a vacuum oven at 60°C for 1 hour, we exposed it to simulated solar light or natural sunlight with or without external heating. For the natural sunlight test, C n B pellets were prepared with a thickness of 2-3 mm and varying diameters (4-13 mm) using a commercial pellet press at 2 tons for 5 minutes. Biochar was produced by slow thermal decomposition of wood chips in a fluidized bed furnace at 200°C for 6 hours under an N2 atmosphere. During this process, the temperature was increased at a rate of 20°C / min to 400°C and maintained for 12 hours. The wood sample was monitored during this time to ensure the completion of thermal decomposition. Depending on the size of the chips, extensions of the time and intermediate grinding were necessary to ensure biochar formation.

[0020] Figure 1 shows a schematic diagram of one embodiment of a laboratory-scale batch-type reactor used. The reactor may include a stainless steel reactor body A with quartz glass windows arranged around it, and valves B that control the inflow of gas into and outflow of gas from the reactor body. The quartz glass windows in the reactor allow light from a Xe lamp, which is simulated or simulated solar light, to irradiate the surface of the carbonaceous material inside the reactor and promote the generation of carbon monoxide. The reactor has a volume of 11.8 mL and utilizes quartz windows, a thermocouple thermometer, and a pressure gauge. The reactor was used with a 300W Xe lamp from Perfect Light®'s solar simulator. A Newport® power meter with a detector spot diameter of 18 mm was used. By manually changing the power of the Xe lamp (adjusting the current between 10 and 20 amps), light intensities from 7.00 W to 27.05 W were produced. By adjusting the light spot diameter (6 to 10 mm using a focusing lens), the net output of 12.7 W cm used in this study was achieved. -2 From 34.4 W cm -2 We were able to achieve a light intensity of up to this level.

[0021] The reaction was carried out in a batch-type reactor using an average sample mass of ~0.3 to 1.1 mg, placed on a borosilicate filter. Alternatively, 13 mm diameter pellets were placed in a reactor with a quartz window and pressurized to 24 to 30 psi per CO2.

[0022] The carbonaceous material pellets are placed in a reactor, which is then sealed. The gas is removed by a vacuum pump and replaced with pure carbon dioxide or a mixture of carbon dioxide and an inert gas. The reactor is then sealed again by closing valve B. Light from a light source shines onto the surface of the carbonaceous material through a quartz glass window fixed to the sealed part of the stainless steel reactor. During and after the reaction, one valve may be opened to sample the gas from the reactor and analyze it by known means, including gas chromatography-flame ionization detection (GC-FID).

[0023] As shown in Figure 2, the photoflow reactor allows for the continuous flow of a gaseous medium containing carbon dioxide through a carbonaceous material. The photoflow reactor is constructed of a heatable stainless steel body and facilitates the flow of gas through a fixed reaction bed. Light is shone onto the bed through a quartz glass window. The body of the continuous flow photoflow reactor is connected to gas inlet and outlet lines, but may be configured by known means to allow gas to flow through the reactor while preventing particle movement. The reactor body may be partially covered with heating elements and insulation to allow irradiation of a material selected for the reaction in the tube.

[0024] Sampling for analysis of the output stream of a photoflow or continuous flow reactor was performed by directly connecting to the output gas stream. A GCMS spectrometer (Agilent 7890B-5977A MAD, using He as the carrier gas) with an automated injection gas sampling valve spanning three capillary columns was used. 12 CO / 13 We analyzed the amount of CO produced.

[0025] Using natural sunlight, 15-90 W cm² -2Each sample in the reaction apparatus was able to be irradiated for 10 minutes at the measured intensity. In several experiments, sunlight simulations were performed during preliminary and wavelength tests (Figure S9) using a 300W Xe arc lamp from Perfect Light (registered trademark). Subsequently, measurements were taken using the flame ionization detector (FID) of the SRI8610 GC instrument.

[0026] The selection of a suitable carbonaceous material for CO generation via the reverse Boudor process is generally based on its activity (i.e., the rate at which it is likely to generate CO). This activity can be determined by TGA experiments and often depends on the metal content of the carbonaceous material. However, since biochar can originate from many sources and therefore may contain a wide range of metals, industrial carbon black was chosen as the material for consideration.

[0027] First, conventional analytical tests were performed, including characterization by ultraviolet-visible (UV-Vis) spectroscopy, elemental analysis, powder X-ray diffraction (PXRD) (Figure S3), Raman spectroscopy (Figure 1c), and X-ray photoelectron spectroscopy (XPS), using two types of carbon black: one ultra-high purity and the other containing low levels of metallic impurities (ultra-high purity C n B and C n The analysis (referred to as B CABOT) was performed both before and after light irradiation. This characterization provided a good understanding of the intrinsic properties of the selected material, but it is not necessary for implementing the novel processes disclosed in this document.

[0028] CO2 atmosphere C n Sample B (Ultra-high purity C n B, Cabot Corporation C n B and C of biochar nThe TGA experiment conducted for B) showed the effect of metal impurities on CO production. The conversion was in the order of ultra-high purity alpha azer < cabot < biochar, with an increase observed in CO production from metal impurities. Several reported studies of the reverse Boudouar reaction using metals as catalysts have shown that such use leads to an improvement in the CO ratio and a significant decrease in the activation energy.

[0029] [Example 1] Investigation test of optically driven inverse Boodor reactivity To assist in selecting a suitable carbonaceous material for the studies reported in this book, a 300W Xe lamp (irradiation intensity 12.7 W cm) was used at room temperature. -2 , 0.1 W cm -2 Using light equivalent to one day of sunlight (sunlight), investigation tests were conducted to select the optimal carbonaceous material (CM). These investigation tests were initial screening tests conducted to screen the activity of the carbonaceous materials being tested. Each sample of the material used was placed in the reaction apparatus shown in Figure 1, irradiated with light, and the CO production rate was measured. As shown in the results illustrated in Figure 3, ultra-high purity C n B-black (manufactured from acetylene by Alpha-Azer) and carbon nanotubes (Sigma-Aldrich) were found to be stable in the presence of CO2 and light, with low carbon monoxide production rates. Natural graphite samples were the most stable in the presence of light, regardless of irradiation intensity or duration, due to their lack of oxidation function and surface defects. Cabot's C n Sample B and the biochar sample showed the highest carbon monoxide production under light irradiation. Biochar showed the highest CO production rate, but due to its distinct composition, size, structure, aggregation state, porosity, commercial availability and surface features, Cabot's C n B was selected for further consideration.

[0030] [Example 2] Effect of light intensity on CO generation Various light intensities from a 300W Xe lamp, namely 15.3, 18.2, 20.9, 24.2, and 34.1 W / cm² 2 Using Cabot Corporation's C n The photoresponsiveness of CO production in B was measured, and its photochemical and photothermal behavior was evaluated. The experiment was conducted in the reaction apparatus shown in Figure 1, without external heating, at ambient temperature. These results are shown in Figure 4, demonstrating that the amount of CO produced increases with increasing light intensity. These results indicate that the highly endothermic inverse Boudor process can be photochemically driven, at 21 W cm². -2 The following studies have shown that, at lower intensities, high light intensity and dominant photochemical behavior suggest a dominant photothermal contribution. In addition, metal impurities, surface defects, and C and O deficiencies have been shown to significantly increase CO production rates at low light intensities without intervening in the photochemical behavior.

[0031] [Example 3] Elimination of the thermal effect of LED lighting To minimize photothermal effects under high light intensity conditions and to confirm the presence of a photochemical contribution to the reverse Boudor process, the temperature at which carbonaceous material in the reactor would be heated under known light intensities was measured using the determined photon flux of the sample. 21 W cm -2 The results at the following light intensities showed a line correlation with respect to CO formation rates, suggesting photochemical behavior. Therefore, as a further experiment, at 15 W cm -2 Select the light intensity, C n The role of light in CO2 reduction in sample B was measured. The sample surface was heated using an unfiltered Xe arc lamp set to a constant light intensity. An infrared (IR) camera was used to measure the temperature generated on the sample surface under CO2 conditions in a photoreactor equipped with a CaF2 window. The measured temperature was 350°C, due to the expected high optical absorption by the black carbon material. Therefore, assuming that the contribution of heat from the Xe lamp could be ignored, all systems were heated to this temperature in subsequent experiments.n B pellets and Cabot's C n B pellets (13 mm in diameter, 2-3 mm thick) were placed in separate batch reactors for each experiment. After several vacuum / CO2 purges, the photoactivity was tested under CO2 conditions using the above-described method. The Xe lamp intensity was set to 15 W cm² on the surface of all samples, regardless of wavelength. -2 The incident photon flux was set to be such that it had the following characteristics. The result is shown in Figure 5. When using unfiltered light from a Xe lamp ("pure Xe"), ultra-high purity C n B and Cabot's C n For B, the amounts are 1.5 and 5.3 mmol / cm³, respectively. -2 h -1 The CO generation rate was observed. The "dark" column is for comparison and shows the CO generation rate when the temperature was moderately raised to 350°C without irradiation from the Xe light source.

[0032] To further this comparison, the wavelength dependence of the reaction was evaluated using a bandpass filter. The test was repeated with AM 1.5G, 420, 495, and 595 nm highpass filters attached to a Xe lamp. The intensity was measured at 15 W cm⁻¹ on the surface of all samples, regardless of the wavelength used. -2 It was adjusted to have an incident photon flux of [value].

[0033] As shown in Figure 5, the observed CO production rates were, respectively, ultra-high purity C n For B, the concentrations were 0.16 (in darkness), 1.63, 2.93, 2.29, and 2.14 mmol / cm³. -2 h -1 So, Cabot Corporation's C n For B, the concentrations were 1.16 (in darkness), 5.53, 7.43, 8.43, and 9.24 mmol / cm³. -2 h -1A linear increase in CO production rate was observed for each filter, and the photochemical behavior was similar to that of Cabot's C n In the case of B, it varies depending on the spectral wavelength range, but ultra-high purity C n In B, a decreasing trend was observed as nm increased. For the inverse Boudor process, which has high endothermic properties, Cabot's C under irradiation at wavelengths higher than 595 nm n The unique photochemical behavior of B was demonstrated by irradiation with a Xe lamp whose intensity was increased through a 595 nm high-pass filter. It showed the highest activity toward CO, and the linear trend of CO formation observed at that light intensity supports its contribution to the sun-driven inverse Boudoar reaction.

[0034] [Example 4] Effect of light intensity on temperature increase Additional experiments to evaluate the photochemical activity of the reverse Boudouor reaction under dark versus light conditions were conducted using the photoflow reactor schematically shown in Figure 2 above. In each experiment, the total gas flow rate was 0.126 cm³. 2 The surface area of ​​the irradiated samples was set to 6 sccm (1 sccm of CO2:5 sccm of Ar); each sample weighed approximately 2-3 mg. The LED pseudo-white light intensity was 4.8 W cm². -2 A new sample was used for each test condition. As shown in Figure 6, the CO production rate increased with the photo-assisted reaction compared to the dark process. This confirmed the contribution of light to the process and suggested that the photo-driven reaction is more likely to proceed than the thermal reaction through a different mechanism.

[0035] [Example 5] Dynamic experiment Dynamic experiments were conducted assuming a non-equilibrium batch reaction system, i.e., a batch system in which chemical equilibrium has not been achieved. In other words, although not all of the reagents were consumed, the total conversion of CO2 did not exceed 5%. In these experiments, the samples were subjected to a CO2 pressure of approximately 24-30 psig and 34.1 W cm² without external heating. -2 Light irradiation was performed for reaction times of 1, 2, 3, 4, and 5 minutes, but the reaction time was 34.1 W cm⁻¹. -2 After 5 minutes of irradiation under simulated sunlight intensity, the total CO2 conversion was less than 2%. The results are plotted as a graph in Figure 7.

[0036] [Example 6] Inverse Boodoo reaction of natural sunlight To confirm the reactivity observed under LED lighting in sunlight, a light-driven inverse Boodor experiment was conducted using natural sunlight, rather than the Xe lamp used in the previous experiment which simulated sunlight. Several C13mm in diameter and 1-2mm thick were used. n B pellets are processed using a commercial pellet press under a pressure of 2 tons for 5 minutes. n Material B was prepared by compression. The pellets were infused with 43, 63, and 90 W cm⁻¹. -2 To achieve the desired intensity, natural sunlight was focused to a spot diameter of 2-4 mm using lenses with diameters of 7.5 cm and 12.7 cm in a CO2 atmosphere. The intensity of typical unfocused natural sunlight is 0.070-0.088 W / cm². -2 This was within the range. In particular, Xe arc lamps and natural sunlight have similarities in their spectra and photon flux, and were expected to produce comparable large-scale generation rates.

[0037] Approximately 20 W cm² without external heating. -2 It was found that irradiation with sunlight produced a higher CO production rate than the reported 850°C thermal process. The incident light intensity was 43 W cm⁻¹. -2Increasing the temperature to this level yielded a rate exceeding that reported for microwave radiation at 813°C and 75 W. As expected, the CO production rate increased with natural light intensity, and the high conversion rate indicated a linear trend characteristic close to a photochemical reaction pathway or photothermal-photochemical equilibrium. The results are shown in Figure 8.

[0038] Overall, the CO production rate of the Xe arc lamp under simulated sunlight was consistent with the CO production rate in natural sunlight experiments. The light-driven inverse Boodor process was proven to be usable with sunlight. Thus, the experimental results in this invention demonstrate that the solar-powered inverse Boodor reaction is readily implementable.

[0039] Similar to the Xe lamp pseudo-sunlight irradiation experiments, the use of sunlight irradiation through a 595 nm bandpass filter, when using the full spectrum, showed a higher CO rate than irradiation of the same intensity, suggesting that the performance of the optical inverse Boudor process can be optimized mainly by using the infrared photon flux. The CO formation and production rates ranged from 65 to 90 W cm⁻¹. -2 This was consistent with the predicted experiments conducted under natural light of up to this intensity (Figure 8). To demonstrate that the inverse Boodor system can be driven using a high-intensity LED system to eliminate the intermittency of natural sunlight, a high-intensity red LED (95 W cm²) was used. -2 The experiment was conducted using 625 nm. The results are shown in Figure 8.

[0040] [Example 7] Effect of filtering sunlight without adjusting intensity The wavelength dependence of the light-driven inverse Boudoar reaction is also 75 W cm -2 The evaluation was performed using unfiltered sunlight and sunlight with ultraviolet (UV), visible, and infrared (IR) bandpass filters (Figure 9). When filters were used, the total irradiation power was 75 W cm². -2 From 62, 42 and 34 W cm -2 The concentrations decreased to 3706, 1814, 161, and 176 mmol CO₂ cm⁻, respectively. -2 h -1The corresponding CO production rate was generated.

[0041] [Example 8] Dependence on LED wavelength To further measure the dependence of CO conversion on LED wavelength, tests were conducted using LEDs that emit specific colors. UV-vis spectroscopy and the black nature of carbonaceous materials suggested that the selected carbon samples would strongly absorb light across a broad wavelength range. The wavelength dependence of the light-driven inverse Boudouard reaction was investigated using UV (365 nm), blue (470 nm), white (440-600 nm), green (525 nm), and red (625 nm) LEDs.

[0042] CO production under blue LED light was found to follow Arrhenius behavior, suggesting that the blue wavelength contributes photothermally to the solar inverse Boudoar reaction. In the green LED-driven inverse Boudoar reaction, 1.8 W cm was required for CO formation. -2 A higher intensity was required. For red LEDs, a linear relationship was observed between power intensity and CO formation rate. As shown in Figures 10a-10e, the red LED produced the highest CO generation rate when the bandpass filter experiment in Example 3, which used simulated sunlight, was confirmed. Based on this result, subsequent experiments used red LED light as the main light source, compared to the natural sunlight irradiation experiment. I compared them.

[0043] [Example 9] Isotope 13 C-light-driven reverse boomerang reaction To confirm that the CO generated in the reaction chamber originates from the carbonaceous material and carbon dioxide within the reaction chamber, isotope labeling was performed. 13 CO2, CABOT 12 C n It was reacted with sample B. GC-MS measurement revealed that an equal amount of each sample was present in the reaction chamber. 12 CO and 13CO was observed, which proved that carbon monoxide was formed in equal amounts from each precursor, confirming the role of carbon dioxide in the reaction induced by natural sunlight irradiation.

[0044] The light-assisted inverse Boudoar process in this invention overcomes the challenges of conventional high-temperature inverse Boudoar processes and demonstrates operation at ambient temperature. Compared to thermochemical and microwave inverse Boudoar processes that require temperatures above 900°C, the solar-powered or light-powered process operates at lower activation energies and without external heating. The light-driven inverse Boudoar reactions described in this document reveal details of different carbon sources and methods for converting CO2 to CO.

[0045] Solar or light-assisted reverse boudor processes are technically and economically feasible, especially with advancements in battery efficiency, solar concentrators, and LEDs, as well as the reduction of associated costs. Such methods will enable CO generation from waste carbon and carbon dioxide, generating value-added raw materials for a wide range of chemicals and chemical precursors.

Claims

1. A method for producing carbon monoxide, comprising reacting one or more carbonaceous materials with a supply stream of gaseous carbon dioxide, A method for producing carbon monoxide, characterized in that the carbonaceous material is irradiated with light at the same time as it comes into contact with the carbonaceous material by the gaseous carbon dioxide source.

2. The method according to claim 1, characterized in that the method is carried out at a temperature ranging from ambient temperature to approximately 560 degrees Celsius.

3. The method according to claim 1, characterized in that the method is carried out at a temperature ranging from ambient temperature to approximately 280 degrees Celsius.

4. The method according to any one of 1 to 3, characterized in that the gaseous carbon dioxide source includes carbon dioxide and an inert gas.

5. The method according to claim 4, characterized in that the inert gas is argon.

6. The method according to claim 1, characterized in that the light is sunlight.

7. The method according to claim 1, characterized in that the light is derived from a light-emitting diode.

8. The light intensity measured on the surface of the carbonaceous material is 0.1 to 95 W cm². －２ The method according to 1, 6, or 7, characterized in that it is up to the specified point.

9. The light intensity measured on the surface of the carbonaceous material ranges from 1.0 to 95 W / cm². －２ The method according to 1, 6, or 7, characterized in that it is up to the specified point.

10. The light intensity measured on the surface of the carbonaceous material is 1.5 to 95 W cm². －２ The method according to 1, 6, or 7, characterized in that it is up to the specified point.

11. The light intensity measured on the surface of the carbonaceous material is 10 to 95 W cm². －２ The method according to 1, 6, or 7, characterized in that it is up to the specified point.

12. The light intensity measured on the surface of the carbonaceous material is 15 to 95 W cm². －２ The method according to 1, 6, or 7, characterized in that it is up to the specified point.

13. The method according to any one of 1 to 10, characterized in that the light source is amplified by optical or electronic means to reach a desired intensity.

14. The method according to any one of 1 to 11, characterized in that the wavelength of the light irradiated onto the carbonaceous material is greater than about 420 nm.

15. The method according to any one of 1 to 11, characterized in that the wavelength of the light irradiated onto the carbonaceous material is greater than approximately 495 nm.

16. The method according to any one of 1 to 11, characterized in that the wavelength of the light irradiated onto the carbonaceous material is greater than about 595 nm.

17. A method for producing carbon monoxide, comprising reacting one or more carbonaceous materials with a supply stream of gaseous carbon dioxide, The carbonaceous material contains at least 0.1 W cm －２ A method for producing carbon monoxide, characterized in that sunlight is irradiated at an intensity measured on the surface of the carbonaceous material.

18. A method for producing carbon monoxide, comprising reacting one or more carbonaceous materials with a supply stream of gaseous carbon dioxide, The carbonaceous material contains at least 1 W cm －２ A method for producing carbon monoxide, characterized in that sunlight is irradiated at an intensity measured on the surface of the carbonaceous material.

19. A method for producing carbon monoxide, comprising reacting one or more carbonaceous materials with a supply stream of gaseous carbon dioxide, The carbonaceous material contains at least 15 W cm －２ A method for producing carbon monoxide, characterized in that sunlight is irradiated at an intensity measured on the surface of the carbonaceous material.

20. A method for producing carbon monoxide, comprising reacting one or more carbonaceous materials with a supply stream of gaseous carbon dioxide, a. The carbonaceous material is irradiated with light from one or more light-emitting diodes; and b. The intensity of the light measured on the surface of the carbonaceous material is at least 15 W cm －２ is A method for producing carbon monoxide, characterized by the following features.

21. A method for producing carbon monoxide, comprising reacting one or more carbonaceous materials with a supply stream of gaseous carbon dioxide, a. The carbonaceous material is irradiated with light from one or more light-emitting diodes; and b. The light intensity measured on the surface of the carbonaceous material is at least 15 W cm². －２ and c. The wavelength of light originating from the light-emitting diode exceeds approximately 400 nm. A method for producing carbon monoxide, characterized by the following features.

Images