An interface regulation based near zigzag single-walled carbon nanotube selective growth method

Abstract

This invention belongs to the field of nanomaterial preparation technology, specifically relating to a selective growth method for near-serrated single-walled carbon nanotubes based on interface regulation. The method involves loading a metal catalyst onto an inert support, depositing an amorphous carbon isolation layer on the surface of the catalyst particles in a carbon-containing atmosphere, and then physically mixing it with an oxygen-containing support capable of oxygen storage and release to construct a composite support catalyst system. During chemical vapor deposition, active oxygen is first released in situ from the oxygen-containing support under an inert atmosphere to oxygenate the catalyst particles. The rate-limiting mass transfer effect of the carbon isolation layer is used to achieve selective oxidation regulation of catalyst particles of different sizes. Then, the carbon source gas is switched for carbon nanotube growth. This invention decouples oxygen regulation from the growth stage through temporal separation and the synergy of the carbon isolation layer, achieving highly selective growth of near-serrated single-walled carbon nanotubes. The process is simple and easily scaled up.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a selective growth method for near-serrated single-walled carbon nanotubes based on interface regulation. Background Technology

[0002] Single-walled carbon nanotubes (SWCNTs) have shown great promise for applications in nanoelectronic devices, optoelectronic materials, sensors, and energy storage due to their superior electrical, optical, and mechanical properties. The performance of SWCNTs fundamentally depends on their chirality index (n, m). Different chiral structures correspond to vastly different band structures, directly determining whether they exhibit metallic or semiconducting properties. Therefore, achieving the controllable fabrication of SWCNTs with single or narrow chiral distributions is a fundamental scientific problem that must be solved to advance their application in high-end fields.

[0003] Chemical vapor deposition (CVD) is widely recognized as the most promising technology for achieving structure-controlled growth of near-zigzag carbon nanotubes (SWCNTs) due to its excellent controllability and scalability. However, in actual CVD growth, the products typically exhibit a wide chiral distribution, making precise control difficult. Among these, the directional synthesis of near-zigzag SWCNTs is particularly challenging. In their research entitled "Chemical vapor deposition synthesis of near-zigzag single-walled carbon nanotubes with stable tube-catalyst interface," Zhao et al. pointed out that zigzag carbon nanotubes, due to their extremely small helix angle, have a much higher ring-forming energy barrier than other chiral types such as armchair-shaped nanotubes, putting them at an inherent disadvantage in growth kinetics and resulting in extremely low abundance in the products. The researchers developed a method called "tandem plate CVD" to attempt to enrich near-zigzag carbon nanotubes by gradually approaching the thermodynamically stable interface through multiple periodic temperature variations. Although this study demonstrates the possibility of controllable growth of near-serrated SWCNTs, its high dependence on complex temperature programs and the resulting limitations in practical implementation, such as complex processes and poor scalability, mean that the chiral selectivity of the product is still far from reaching a level suitable for widespread application.

[0004] The root cause of the aforementioned chirality control dilemma lies in the dynamic instability of catalyst nanoparticles in the high-temperature environment of CVD. The ripening, migration, and aggregation of catalyst particles lead to a continuous widening of their size distribution, thereby giving rise to SWCNTs with different diameters and chirities. Existing control methods mostly focus on enhancing the binding force between the catalyst and the inert support to passively maintain particle dispersion and stability. This approach lacks the ability to dynamically and actively modulate catalyst particles of different sizes during the critical growth window to "turn on / off" their activity. Furthermore, there is a lack of mature technical solutions for utilizing the chemical effects at the support-catalyst interface to overcome the kinetic growth barrier of near-serrated SWCNTs.

[0005] Therefore, there is an urgent need to develop a novel catalyst design concept and interface control method to break through the technical bottleneck of passive control of catalyst particle size in existing technologies. This would enable selective activation of catalyst particles of specific sizes during CVD reactions, thereby achieving efficient and directional growth of near-serrated SWCNTs to meet the urgent demand of high-end applications for narrowly chiral carbon nanomaterials. Summary of the Invention

[0006] The purpose of this invention is to provide a selective growth method for near-serrated single-walled carbon nanotubes based on interface regulation. By introducing an oxygen-containing support with oxygen storage and release capabilities, active oxygen is released in situ during the CVD reaction, and selective oxidation regulation is performed on catalyst particles of different sizes, thereby overcoming the kinetic barrier to the growth of near-serrated carbon nanotubes and significantly improving its selectivity.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A selective growth method for near-zigzag single-walled carbon nanotubes based on interface regulation includes the following steps: (1) Dissolve the metal catalyst precursor in an organic solvent to obtain a catalyst precursor solution; (2) The first part of the support is mixed with the catalyst precursor solution, and the metal component is loaded onto the first part of the support by impregnation. After drying, the supported catalyst is obtained. (3) The supported catalyst is heat-treated in a carbon-containing atmosphere to deposit an amorphous carbon isolation layer on the surface of the catalyst particles, thereby obtaining a supported catalyst with a carbonaceous isolation layer. (4) The supported catalyst with a carbonaceous isolation layer is mixed with the second support to obtain a composite supported catalyst system; the second support is an oxygen-containing support with oxygen storage and release capabilities; (5) The composite support catalyst system is placed in a chemical vapor deposition furnace, heated under an inert atmosphere, first treated with oxygen, and then switched to carbon source gas for reaction; (6) After the reaction is complete, switch to an inert atmosphere and cool to room temperature to obtain near-serrated single-walled carbon nanotubes.

[0008] Further, in step (1), the metal catalyst precursor is a salt or complex containing at least one metal selected from Rh, Ru, Fe, and Co; the organic solvent is selected from acetone, toluene, and ethylene glycol.

[0009] Furthermore, in step (2), the first portion of the carrier is selected from at least one of SiO2, Al2O3, CaO, and MgO.

[0010] Further, in step (2), the mass ratio of the metal element in the first part of the support to the metal catalyst precursor is 1:(0.02~0.06).

[0011] Further, in step (3), the carbon-containing atmosphere is a mixture of C2H4 and an inert gas, wherein the volume fraction of C2H4 is 5%~20%; the heat treatment temperature is 300~500℃, and the heat treatment time is 5~30min.

[0012] This invention modulates the reactive oxygen species (ROS) mass transfer rate by introducing an amorphous carbon barrier layer on the surface of catalyst particles. The amorphous carbon barrier layer allows small gas molecules to diffuse through, but its own mass transfer resistance transforms the arrival rate of ROS from an uncontrollable, large-scale supply to a slow, continuous, rate-limited supply. This rate-limiting effect enhances the sensitivity of the oxidation process to catalyst particle size; smaller particles, due to their higher chemical potential, are preferentially oxidized and dissolved even under low ROS flux, while larger target particles maintain activity under limited oxygen supply conditions. Furthermore, the carbonaceous barrier layer can be partially consumed by ROS during the subsequent CO growth stage, thus thinning and not continuously inhibiting growth. The carbonaceous barrier layer transforms the non-selective and violent oxidation of the catalyst by ROS into a controllable selective oxidation, further improving the precision of catalyst size selection.

[0013] Further, in step (4), the second carrier is selected from at least one of CeO2, TiO2, Tb2O3, Tb4O7, MnO, Mn3O4, Mn2O3, and MnO2.

[0014] Further, in step (4), the mass ratio of the supported catalyst with the carbonaceous isolation layer to the second part of the support is 1:(0.3~1); the mixing is a grinding and mixing process.

[0015] Furthermore, in step (5), the heating rate is 15~25℃ / min; the gas flow rate of the inert atmosphere is 200~500sccm.

[0016] Furthermore, in step (5), the oxygen treatment temperature is 600~800℃ and the oxygen treatment time is 5~20min.

[0017] Furthermore, in step (5), the carbon source gas is carbon monoxide, the reaction temperature is 700~900℃, and the reaction time is 10~30min.

[0018] In existing methods, oxygen release from the oxygen-containing support occurs simultaneously with CO decomposition and carbon nanotube growth, with active oxygen acting on both the catalyst particles and the growing carbon nanotubes. This invention separates these two processes sequentially. First, under an inert atmosphere, the oxygen-containing support releases active oxygen in a concentrated manner. Utilizing the size dependence of small-sized catalyst particles (high surface energy, high chemical potential, and easier oxidation), unwanted small particles are selectively dissolved. After the catalyst size distribution has been screened, CO is then switched to promote carbon nanotube growth. At this point, the catalyst group is mainly composed of particles of the target size. This avoids interference from active oxygen in the carbon nanotube growth process, achieving precise control of screening the catalyst before growing carbon nanotubes, and significantly improving the selectivity ratio of near-serrated carbon nanotubes.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: (1) Highly selective growth of near-serrated single-walled carbon nanotubes was achieved. This invention introduces a carbonaceous isolation layer and adopts a time-separation strategy to separate the release of active oxygen from the oxygen-containing support from the carbon nanotube growth process in time. First, the catalyst particle size is selectively screened during the oxygen treatment stage, and then carbon nanotubes are synthesized in a directional manner during the growth stage. This effectively overcomes the inherent problem of unfavorable growth kinetics of near-serrated carbon nanotubes and significantly improves the selectivity ratio of near-serrated and adjacent chiral carbon nanotubes in the product.

[0020] (2) Precise selective control of catalyst particle size is achieved. This invention constructs an amorphous carbon isolation layer on the surface of catalyst particles, which transforms the effect of active oxygen on the catalyst from non-selective and violent oxidation to slow and controllable selective oxidation through its mass transfer resistance. Based on the size dependence of small-sized particles, which have high surface energy and are more easily oxidized, selective ablation of unwanted small-sized catalyst particles is achieved under rate-limited mass transfer conditions, while protecting the activity of target-sized particles, thereby achieving precise screening of catalyst size distribution during the reaction process.

[0021] (3) The catalyst system can be flexibly combined and has strong versatility. This invention adopts a stepwise independent preparation and physical combination method of metal and oxygen-containing support loaded on inert support. The type and loading conditions of metal catalyst and the type and amount of oxygen-containing support can be optimized independently. By changing different types of oxygen-containing support or metal components, the catalyst system can be adjusted for different target chiral carbon nanotubes, which has good versatility and scalability.

[0022] (4) The process is simple and suitable for large-scale application. The present invention uses conventional impregnation method, carbon atmosphere heat treatment and physical mixing to prepare catalyst, and chemical vapor deposition process to grow carbon nanotubes. The whole process does not require complicated equipment or harsh conditions. The process flow is simple and controllable, easy to scale up, and has potential industrial promotion value. Attached Figure Description

[0023] Figure 1 Transmission electron microscope (TEM) image of the product prepared in Example 1.

[0024] Figure 2 The image shows the Raman spectrum of the product prepared in Example 1.

[0025] Figure 3 The UV-Vis-NIR absorption spectrum of the product prepared in Example 1 is shown.

[0026] Figure 4 The UV-Vis-NIR absorption spectrum of the product prepared for Comparative Example 1 is shown.

[0027] Figure 5 The Raman spectrum of the product prepared in Comparative Example 2 is shown.

[0028] Figure 6 The UV-Vis-NIR absorption spectrum of the product prepared in Comparative Example 3 is shown. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the embodiments are all commercially available products.

[0030] Example 1 This embodiment provides a selective growth method for near-zigzag single-walled carbon nanotubes based on interface regulation, including the following steps: (1) Dissolve 0.1g of cobalt nitrate (Co(NO3)2·6H2O) in 10mL of ethylene glycol and stir until completely dissolved to obtain a catalyst precursor solution; (2) Mix 1.0 g of silica (SiO2) support with the catalyst precursor solution obtained in step (1), impregnate and stir at room temperature for 2 h, and then dry at 80 °C for 12 h to obtain a supported catalyst; (3) The supported catalyst obtained in step (2) is placed in a tube furnace and a mixture of C2H4 and Ar is introduced, wherein the volume fraction of C2H4 is 10% and the gas flow rate is 300 sccm. The temperature is raised to 400℃ at 10℃ / min and held for 15 min to deposit an amorphous carbon isolation layer on the surface of the Co catalyst particles. Then, it is cooled to room temperature in an Ar atmosphere to obtain a supported catalyst with a carbonaceous isolation layer. (4) Grind and mix 1g of the supported catalyst with carbonaceous isolation layer obtained in step (3) with 0.5g of cerium dioxide (CeO2) to obtain a composite supported catalyst system; (5) Place the composite support catalyst system obtained in step (4) in a quartz boat, place the quartz boat in the heating zone of the chemical vapor deposition furnace, heat it to 700°C at a heating rate of 20°C / min under Ar atmosphere, with an Ar gas flow rate of 300 sccm, and keep it at this temperature for 10 min to allow CeO2 to release active oxygen in situ to treat the catalyst particles with oxygen; then turn off Ar and switch to CO gas with a CO gas flow rate of 300 sccm, and react at 700°C for 20 min. (6) After the reaction is complete, turn off CO and switch to Ar atmosphere. Cool the chemical vapor deposition furnace to room temperature in Ar atmosphere, take out the product, and obtain near-serrated single-walled carbon nanotubes.

[0031] Figure 1 The image shows a transmission electron microscope (TEM) image of the product prepared in Example 1. It clearly shows that the product exhibits a uniform diameter, regular morphology, and few defects in single-walled carbon nanotubes, with no obvious amorphous carbon or multi-walled carbon nanotube impurities. The nanotubes have a uniform diameter distribution and good dispersion, without significant aggregation or entanglement. This image demonstrates that the catalyst prepared by the interface control strategy of this invention can achieve efficient growth of single-walled carbon nanotubes with regular morphology and pure structure, verifying the effectiveness of the preparation method of this invention in controlling the morphology of the product.

[0032] Figure 2 The image shows the Raman spectrum of the product prepared in Example 1, with values ​​in the range of 100-400 cm⁻¹. -1 The presence of a distinct radial breathing pattern (RBM) characteristic peak in the region confirms that the product is high-purity single-walled carbon nanotubes; at 1340 cm⁻¹... -1 The presence of weak D peaks on both sides indicates a high degree of graphitization and low structural defects in the product; at 1580 cm⁻¹ -1 Strong G peaks appear on both sides, corresponding to the sp peaks of carbon nanotubes. 2The in-plane vibrations of the hybrid carbon framework, with a sharp and high-intensity G peak, further demonstrate the excellent crystallinity of the product. The stable position and intensity of the characteristic peaks under different excitation wavelengths indicate that the method of this invention can prepare single-walled carbon nanotubes with uniform structure and high crystallinity, providing a structural basis for chiral selectivity.

[0033] Figure 3 The UV-Vis-NIR absorption spectrum of the product prepared in Example 1 is shown in the figure. As can be seen from the figure, characteristic absorption peaks of typical near-zigzag chiral structures, such as (9,1), are present in the spectrum. Simultaneously, absorption peaks of adjacent near-zigzag chiral structures, such as (10,2), (8,3), and (7,3), are also present, and these peaks have relatively high intensities. In addition, a small number of weak absorption peaks of non-zigzag chiral structures, such as (6,5), (6,4), and (5,4), are also observed in the spectrum. Furthermore, a significant Sg concentration can be observed in the spectrum. 11 With S 22 The characteristic absorption peaks of semiconductors indicate that the obtained product is mainly composed of semiconducting single-walled carbon nanotubes, with the proportion of near-zigzag and adjacent chiral carbon nanotubes being significantly higher than that of other chiral types. This proves that the method of the present invention can achieve highly selective growth of near-zigzag and adjacent chiral single-walled carbon nanotubes.

[0034] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: Step (5) is as follows: The composite support catalyst system obtained in step (4) is placed in a quartz boat, and the quartz boat is placed in the heating zone of a chemical vapor deposition furnace. It is heated to 700°C at a heating rate of 20°C / min under an Ar atmosphere, with an Ar gas flow rate of 300 sccm. Then, Ar is turned off directly and CO gas is switched to CO gas at a flow rate of 300 sccm. The reaction is carried out at 700°C for 30 min. The remaining steps are the same as in Example 1.

[0035] Figure 4 The UV-Vis-NIR absorption spectrum of the product prepared in Comparative Example 1 is shown in the figure. As can be seen from the figure, characteristic absorption peaks of near-zigzag and adjacent chiral structures, such as (9,1), (8,3), (10,2), and (9,2), and absorption peaks of non-zigzag chiral structures, such as (6,4), (6,5), and (7,5), are observed in the spectrum. Simultaneously, a significant Sg concentration can be observed in the spectrum. 11 With S 22 The characteristic absorption peaks of semiconductors indicate that the obtained product is mainly composed of semiconducting single-walled carbon nanotubes. Compared with Example 1, the product of Comparative Example 1 has a wider chiral distribution and a lower enrichment of dominant chiral structures, indicating that the selective growth effect of near-zigzag single-walled carbon nanotubes is significantly reduced when no pre-oxidation treatment is performed.

[0036] Comparative Example 2 The difference between this comparative example and Example 1 is that no carbonaceous isolation layer is introduced, that is, no carbonaceous atmosphere heat treatment is performed in step (3). Specifically, after obtaining the supported catalyst in step (2), the carbonaceous atmosphere heat treatment in step (3) is not performed. Instead, the supported catalyst and CeO2 are directly ground and mixed in the manner of step (4) to obtain a composite support catalyst system without a carbonaceous isolation layer. The remaining steps are the same as in Example 1.

[0037] Figure 5 The figure shows the Raman spectrum of the product prepared in Comparative Example 2. As can be seen from the figure, under 532 nm excitation, the spectrum is in the range of 100-400 cm⁻¹. -1 The region exhibits characteristic peaks of the radial respiratory pattern (RBM), with a peak at approximately 1340 cm⁻¹. -1 and 1580 cm -1 D and G peaks appeared at the excitation wavelengths, with the D peak signal being more prominent and the G peak having a sharper shape. Under 633 nm excitation, the radial breathing mode region showed extremely weak signals with no obvious characteristic peaks. Although the D and G peaks were identifiable, the overall baseline noise level was high, and the peak shape clarity was inferior to that under 532 nm excitation. This spectrum indicates that although the product prepared in Comparative Example 2 contains single-walled carbon nanotubes, its RBM characteristic peak response is not uniform under different excitation wavelengths, and the D peak signal is relatively strong, reflecting a high level of structural defects and relatively low crystallinity of the product.

[0038] Comparative Example 3 This comparative example provides a method for growing single-walled carbon nanotubes, including the following steps: (1) Dissolve 0.1g of cobalt nitrate (Co(NO3)2·6H2O) in 10mL of ethylene glycol and stir until completely dissolved to obtain a catalyst precursor solution; (2) Mix 1.0 g of cerium dioxide (CeO2) support with the catalyst precursor solution obtained in step (1), impregnate and stir at room temperature for 2 h, and then dry at 80 °C for 12 h to obtain a supported catalyst; wherein the mass ratio of CeO2 to Co metal element in cobalt nitrate is 1:0.04; (3) The supported catalyst obtained in step (2) is placed in a tube furnace and a mixture of C2H4 and Ar is introduced, wherein the volume fraction of C2H4 is 10% and the gas flow rate is 300 sccm. The temperature is raised to 400℃ at 10℃ / min and held for 15 min to deposit an amorphous carbon isolation layer on the surface of the Co catalyst particles. Then, it is cooled to room temperature in an Ar atmosphere to obtain a supported catalyst with a carbonaceous isolation layer. (4) Place the supported catalyst with carbonaceous isolation layer obtained in step (3) in a quartz boat, place the quartz boat in the heating zone of the chemical vapor deposition furnace, heat it to 700°C at a heating rate of 20°C / min under Ar atmosphere, with an Ar gas flow rate of 300 sccm, and hold it at this temperature for 10 min to allow CeO2 to release active oxygen in situ to treat the catalyst particles with oxygen; then turn off Ar and switch to CO gas with a CO gas flow rate of 300 sccm, and react at 700°C for 20 min; (5) After the reaction is complete, turn off CO and switch to Ar atmosphere. Cool the chemical vapor deposition furnace to room temperature in Ar atmosphere, take out the product, and obtain single-walled carbon nanotubes.

[0039] Figure 6 The image shows the UV-Vis-NIR absorption spectrum of the product prepared in Comparative Example 3. As can be seen from the image, the spectrum contains near-zigzag absorption peaks (8,3), (9,1), and (11,1), as well as a pure zigzag peak (10,0). It also shows characteristic absorption peaks of various other chiral structures, including (6,4), (6,5), (7,3), (7,5), (8,4), (7,6), and (9,2). A significant Sg concentration is also observed in the spectrum. 11 With S 22 Semiconductor characteristic absorption peaks. Compared with Example 1, the chiral distribution of the product in this spectrum is significantly broader, with a large number of various chiral carbon nanotubes coexisting, making it difficult to effectively enrich the target chiral structure. This indicates that the preparation method cannot achieve highly selective growth of near-zigzag single-walled carbon nanotubes.

[0040] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A selective growth method for near-zigzag single-walled carbon nanotubes based on interface control, characterized in that, Includes the following steps: (1) Dissolve the metal catalyst precursor in an organic solvent to obtain a catalyst precursor solution; (2) The first part of the support is mixed with the catalyst precursor solution, and the metal component is loaded onto the first part of the support by impregnation. After drying, the supported catalyst is obtained. (3) The supported catalyst is heat-treated in a carbon-containing atmosphere to deposit an amorphous carbon isolation layer on the surface of the catalyst particles, thereby obtaining a supported catalyst with a carbonaceous isolation layer. (4) The supported catalyst with a carbonaceous isolation layer is mixed with the second support to obtain a composite supported catalyst system; the second support is an oxygen-containing support with oxygen storage and release capabilities; (5) The composite support catalyst system is placed in a chemical vapor deposition furnace, heated under an inert atmosphere, first treated with oxygen, and then switched to carbon source gas for reaction; (6) After the reaction is complete, switch to an inert atmosphere and cool to room temperature to obtain near-serrated single-walled carbon nanotubes.

2. The selective growth method for near-zigzag single-walled carbon nanotubes based on interface regulation according to claim 1, characterized in that, In step (1), the metal catalyst precursor is a salt or complex containing at least one metal selected from Rh, Ru, Fe, and Co; the organic solvent is selected from acetone, toluene, and ethylene glycol.

3. The selective growth method for near-serrated single-walled carbon nanotubes based on interface regulation according to claim 1, characterized in that, In step (2), the first carrier is selected from at least one of SiO2, Al2O3, CaO, and MgO.

4. The selective growth method for near-serrated single-walled carbon nanotubes based on interface regulation according to claim 1, characterized in that, In step (2), the mass ratio of the metal element in the first part of the support to the metal catalyst precursor is 1:(0.02~0.06).

5. The selective growth method for near-serrated single-walled carbon nanotubes based on interface regulation according to claim 1, characterized in that, In step (3), the carbon-containing atmosphere is a mixture of C2H4 and an inert gas, wherein the volume fraction of C2H4 is 5% to 20%; the heat treatment temperature is 300 to 500°C, and the heat treatment time is 5 to 30 minutes.

6. The selective growth method for near-zigzag single-walled carbon nanotubes based on interface regulation according to claim 1, characterized in that, In step (4), the second carrier is selected from at least one of CeO2, TiO2, Tb2O3, Tb4O7, MnO, Mn3O4, Mn2O3, and MnO2.

7. The selective growth method for near-zigzag single-walled carbon nanotubes based on interface regulation according to claim 1, characterized in that, In step (4), the mass ratio of the supported catalyst with the carbonaceous isolation layer to the second part of the support is 1:(0.3~1); the mixing is a grinding and mixing process.

8. The selective growth method for near-zigzag single-walled carbon nanotubes based on interface regulation according to claim 1, characterized in that, In step (5), the heating rate is 15~25℃ / min; the gas flow rate of the inert atmosphere is 200~500sccm.

9. The selective growth method for near-zigzag single-walled carbon nanotubes based on interface regulation according to claim 1, characterized in that, In step (5), the oxygen treatment temperature is 600~800℃ and the oxygen treatment time is 5~20min.

10. The selective growth method for near-zigzag single-walled carbon nanotubes based on interface regulation according to claim 1, characterized in that, In step (5), the carbon source gas is carbon monoxide, the reaction temperature is 700~900℃, and the reaction time is 10~30min.

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