KR102075657B1 - regeneration method of deactivated bed for anaerobic methane coupling reaction in dielectric barrier discharge plasma reactor - Google Patents

Abstract

The present invention relates to a dielectric barrier discharge (DBD) plasma reactor including mesoporous dielectric particles in a discharge region, and more specifically, to a DBD plasma reactor designed to remove a coke formed on a mesoporous dielectric particle by a side reaction through plasma treatment in an oxidation atmosphere, and to a use thereof. Meanwhile, a method for producing C_2+ hydrocarbons from methane through non-oxidation coupling reaction of methane according to the present invention comprises: a first step of converting methane into C2 or more hydrocarbons including ethylene and/or ethane through non-oxidation coupling reaction of methane in a DBD plasma reactor having mesoporous dielectric particles in a discharge area; and a second step of removing coke by using low-temperature plasma under an oxidation atmosphere in the DBD plasma reactor having mesoporous dielectric particles which are deactivated by the coke formed during the reaction of the first step in the discharge area.

Description

Regeneration method of deactivated bed for anaerobic methane coupling reaction in dielectric barrier discharge plasma reactor

The present invention provides a method for regenerating a deactivated methane dimerization reaction bed in a dielectric barrier discharge plasma reactor; Or a method for regenerating mesoporous dielectric particles deactivated in a dielectric barrier discharge plasma reactor.

Traditionally, ethylene is obtained through petrochemical naphtha reforming, and acetylene is obtained by high temperature pyrolysis of coal or natural gas. However, it is true that oil has less reserves than gas resources such as natural gas and shale gas, and price fluctuations are more unstable. Coal reserves are much higher than those of petroleum and are highly available, but the cost and energy required for pretreatment are excessive, and dust and greenhouse gases are emitted during the process.

Therefore, researches to actively use natural gas resources, which are rich in reserves and cause relatively less environmental problems, have been continuously conducted. Since methane is a major component of natural gas resources, it is important to convert methane into more valuable hydrocarbons and fuels. In particular, if gas-based technology can be used to produce the basic oil needed in the chemical industry, the existing chemical industry infrastructure can be used almost as it is, and the ripple effect is expected to be enormous.

A lot of research resources have been invested in the synthesis of ethylene, which is a very important high value compound in the petrochemical industry and called petrochemical rice. Representative techniques include oxidative dimerization using oxygen, which is not yet commercialized due to low yields, and technically known to have severe exothermicity, pure oxygen production, separation of gas mixtures, and recycling.

Commercially available acetylene manufacturing processes use high temperature pyrolysis techniques of more than 1500 degrees Celsius, or Huels processes using high temperature plasma up to several thousand degrees. Due to the high temperature, it is difficult to construct a reactor or a process, energy consumption is high, and side reactions cause deposition of crystalline carbon which is difficult to remove.

On the other hand, when a non-oxidative coupling reaction of a typical methane producing C2 compounds is carried out in a conventional thermochemical reactor, very high temperatures (more than 1,000 ° C.) are usually required to thermally activate the CH bonds to produce methyl radicals. do.

In order to avoid such energy-intensive conversion reactions and high operating costs, non-thermal plasma technology that minimizes external heat flow has recently been intensively studied, using elevated electrons and ions directly and efficiently, at elevated temperatures. This is because even without heating all the reaction medium in the bed, it activates the CH bonds of the methane molecules at low temperatures. In non-thermal plasma reaction systems, the electron temperature increases to ~ 20000 K and electrons mainly contribute to the reaction. However, the bulk temperature, including positively charged ions and neutral molecules, is close to room temperature. For this reason, this kind of plasma is considered a non-thermal, non-balanced plasma (ie electron temperature >> gas temperature).

The present invention is to remove a method of removing carbon-containing by-products such as carbon deposits, hydrocarbons, etc. generated in the reaction bed during the reaction by using a dielectric barrier discharge (DBD) plasma, a kind of low-temperature plasma.

In addition, the present invention is to remove the carbon-containing by-products such as carbon deposits, hydrocarbons generated during the reaction while maintaining the mesoporous structure or the particle-specific crystal structure using DBD plasma, which is a kind of low-temperature plasma.

A first aspect of the present invention is a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles in a discharge region, wherein the coke formed on the mesoporous dielectric particles by side reaction is removed by plasma treatment in an oxidizing atmosphere. It provides a DBD plasma reactor characterized.

The second aspect of the present invention is characterized in that in the dielectric barrier discharge (DBD) plasma reactor of the first aspect, mesoporous is characterized by removing coke with a cold plasma under an oxidizing atmosphere from mesoporous dielectric particles deactivated due to coke formed by side reactions. A method of regenerating dielectric particles is provided.

A third aspect of the invention provides a method for producing C ₂₊ hydrocarbons from methane through non-oxidative coupling reaction of methane, the methane in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles in the discharge region. Converting methane to C2 or more hydrocarbons including ethylene and / or ethane via a non-oxidative coupling reaction of; And a second step of removing the coke with a low temperature plasma under an oxidizing atmosphere in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles deactivated due to coke formed during the reaction of the first step in the discharge region. It provides a method for producing a C ₂₊ hydrocarbon, characterized in that the first and second steps are repeated one or more times.

A fourth aspect of the present invention provides a method for producing hydrogen from methane through a non-oxidative coupling reaction of methane, the method of producing methane in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles in the discharge region. Generating a hydrogen from methane through an oxidative coupling reaction; And a second step of removing the coke with a low temperature plasma under an oxidizing atmosphere in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles deactivated due to coke formed during the reaction of the first step in the discharge region. It provides a method for producing hydrogen, characterized in that the first and second steps are repeated one or more times.

Hereinafter, the present invention will be described in detail.

We describe the non-oxidative coupling reaction of methane in a DBD plasma bed at atmospheric and ambient temperature in a dielectric barrier discharge (DBD) plasma reactor with a bed of dielectric material such as regular mesoporous silica (KIT-6). It has been found that, in the following, it is possible to successfully activate CH bonds without additional thermal energy and oxidant molecules to produce methyl radicals and light hydrocarbons.

However, in the case of highly porous dielectric particles, the amount of carbon deposition was significant. Carbon species were also deposited in the pores. In addition, as the size of the dielectric particles increased, the amount of carbon deposition increased due to the increased intensity micro discharge. TG / DTA analysis confirmed that two different carbon species were deposited, and through XRD analysis, most carbon species were identified as amorphous. In addition, the FT-IR spectra indicated that the carbon species were classified as carbon deposits with long chain hydrocarbons.

In order to solve the above problem, the present invention has been experimented with a low-temperature dielectric barrier discharge plasma reactor system for producing hydrogen and mainly C2 compounds such as ethane, ethylene, acetylene through dimerization and dehydrogenation from methane, side reaction during the reaction It was found that the inevitable carbon deposition mixture can be removed using the same plasma as the type used in the reaction. Accordingly, the present invention has been completed by devising a method of regenerating in situ without lifting the filling in the bed in regenerating a bed that has undergone significant deactivation as a reaction.

In addition, in order to solve the above problem, in the case of the regeneration reaction using the muffle kiln affect the structural stability of the packing, while the oxygen-free methane coupling reaction and the charge regeneration reaction using the DBD plasma does not affect the structural stability of the packing. (Example 6, Example 7, Table 3). The present invention is based on this.

Thus, a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles in the discharge region in accordance with one aspect of the present invention is adapted to remove coke formed on the mesoporous dielectric particles by side reaction through plasma treatment in an oxidizing atmosphere. It is designed.

For example, in the DBD plasma reactor according to one aspect of the present invention, the coke that is inevitably accompanied by side reactions during the reaction in the DBD plasma reactor is removed by utilizing the same plasma as the kind used in the reaction, but the reaction mixture during the regeneration process to remove the coke It may instead be designed to supply an oxygen containing mixture.

In addition, the method for regenerating mesoporous dielectric particles according to an aspect of the present invention is to coke a low temperature plasma under an oxidizing atmosphere from mesoporous dielectric particles deactivated due to coke formed by side reaction in the above-described dielectric barrier discharge (DBD) plasma reactor. It is characterized by removing it. In the regeneration method of the present invention, the mesoporous dielectric particles regenerated through low temperature plasma treatment may maintain a regular mesoporous structure or a crystal structure inherent in the dielectric particles before use. Thus, the DBD plasma reaction and / or regeneration method of the present invention is particularly useful for regenerating regular mesoporous dielectric particles.

 At this time, the coke removed by the low temperature plasma treatment may be amorphous carbonaceous and / or graphite carbonaceous materials (graphitic carbonaceous materials).

On the other hand, a DBD plasma reactor according to one aspect of the present invention can be described using micro-electrode concepts as shown in FIG.

Micro electrodes are induced between the dielectric particles charged by an external electric field. High voltages and dielectric barriers cause streamers and micro discharges. These streamers and micro discharges reach the top surface of one particle, which is positively charged due to polarization. At this moment, the lower surface is negatively charged. The top and bottom surfaces become anode-like and cathode-like surfaces, respectively. This phenomenon starts with particles near the outer cathode and continues from particle to particle and in the direction of the opposite electrode. As the streamer wraps the dielectric particles, electrons are scattered like seeds from the bottom surface of the particles because the photo-ionization enhances the strength of the local electric field. Electrons sown like seeds cause another avalanche and start new streamers. At this moment, the reaction molecules collide with the accelerated electrons, resulting in positively charged ions. The cations generated under the enhanced electric field accelerate and move to the cathode surface and collide with the surface. This collision creates secondary electrons to sustain the streamer. Thus, the induced local electric field and the charged surface of the induced particles can be seen as micro electric field and micro electrodes, respectively.

Therefore, the gap distance between the dielectric particles provided in the discharge region may be adjusted to have a low breakdown voltage in the DBD plasma reactor, and the average gap distance of the dielectric particles may be 1 to 20 μm. Through experiments, the gap distance between the dielectric particles may be determined by their sizes, and the average particle diameter of the dielectric particles may be in the microscale range of 10 to 200 μm.

In addition, the DBD plasma reactor and / or method for regenerating mesoporous dielectric particles according to one aspect of the present invention can be described using the micro-electrode concepts described below.

(1) micro electrodes are induced between dielectric particles charged by an external electric field, and a local micro electric field is induced between the dielectric particles;

(2) from outside Streamer and micro-discharge propagated between polarized micro electrodes due to high voltage and dielectric barrier;

(3) The streamer and micro discharge reach the top surface of one particle, the particles are positively charged due to polarization, and at this moment the bottom surface is negatively charged, so the top surface and the bottom surface are each anode type. like and cathode-like surfaces, starting from particles near the outer cathode and continuing from particle to particle in the direction of the opposite electrode;

(4) As the streamer surrounds the dielectric particles, the electrons are scattered like seeds from the lower surface of the particles because the photoelectric ionization enhances the local electric field's intensity, and the electrons scattered like seeds cause another avalanche At the moment, nitrogen and methane molecules collide with the accelerated electrons, positively charged ions are generated, and cations generated under an enhanced electric field accelerate and move to the cathode surface, and collide with the surface. This collision creates secondary electrons to sustain the streamer;

(5) The induced local electric field and the charged surface of the induced particles are viewed as micro electric fields and micro electrodes, respectively, as if the surface with induced charges are micro-cathode and micro-anode, between adjacent particles. Apply the modified Paschen's equation of Equation 1 to the induced local micro electric field.

[Equation 1]

here,

ΔV _{B, micro} : threshold electric potential difference between micro-electrodes to initiate plasma discharges.

d _micro : gap distance between two micro-electrodes

d _{min, micro} : minimum gap distance between two micro-electrodes

γ: second Townsend ionization coefficient; Second Townsend Ionization Coefficient (secondary electron emission coefficient of micro-cathode)

σ: collision cross-sectional area of the gas molecule

E _micro : electric field strength between two micro-electrodes

U _i : ionization potential of the gas molecule

k _B : Boltzmann constant

T: gas temperature

p: gas pressure

A: ionization characteristic constant of the gas molecule (Equivalent to σ / k _B T)

B: ionization characteristic constant of the gas molecule. (Equivalent to U _i σ / k _B T)

The non-oxidative coupling reaction of methane in a DBD plasma reactor is a reaction for synthesizing ethane, ethylene, acetylene, hydrogen, etc. while dimerizing methane at room temperature, whereby a small amount of C3, C4 gas mixture is obtained, Carbon deposits, tar-like mixtures of hydrocarbons are formed in the bed, reducing the performance of the plasma conversion reaction.

Dielectric barrier discharge plasma reactors for non-oxidative coupling reactions of methane control hydrocarbon selectivity by controlling size or gap distance, regardless of the type and porosity of the dielectric particles in the packed-bed. Can be. For example, the composition of ethane, ethylene and acetylene can be controlled by adjusting the size or gap distance of the dielectric particles in a packed-bed.

The average gap distance of the dielectric particles may be 1 to 20 μm. Since the gap distance between the dielectric particles through the experiment can be determined by their sizes, the average particle diameter of the dielectric particles may be in the micro-scale range of 10 to 200 μm.

On the other hand, experiments on non-oxidative coupling of methane in a DBD plasma reactor show that for small dielectric particles, dehydrogenated species such as CH ₂ and CH are more likely to collide with each other, and are continuously coupled and unsaturated. Seemed to be a C2 compound. In contrast, when the particle size was large and the space between the particles was large, the dehydrogenation reaction appeared to occur more frequently than the coupling reaction, which resulted in additional carbon deposition. The increased carbon deposit due to the dehydrogenation reaction appeared to be the result of the increased capacitance of the large particles. This is because the discharge intensity between the large particles increases and increases with the capacitance of the particles, and the specific surface area decreases to increase the amount of charge transferred by the individual micro discharges, although the number of discharges decreases.

The DBD plasma reactor according to one embodiment of the present invention may be designed such that a non-oxidative coupling reaction of methane occurs in a plasma bed with mesoporous dielectric particles. At this time, during the non-oxidative coupling reaction of methane, C-H bonds can be activated without additional thermal energy and oxidant molecules to produce methyl radicals and direct C2-C4 light hydrocarbons. Mesoporous dielectric particles can serve as catalysts for the non-oxidative coupling reaction of methane. For example, the mesoporous dielectric particles may further carry a catalytically active component for the non-oxidative coupling reaction of methane.

In addition, a method for producing a C ₂₊ hydrocarbon from methane through a non-oxidative coupling reaction of methane according to one embodiment of the present invention

Converting methane to C2 or more hydrocarbons, including ethylene and / or ethane, through a non-oxidative coupling reaction of methane in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles in the discharge region; And

And a second step of removing the coke with a low temperature plasma in an oxidizing atmosphere in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles deactivated due to coke formed during the reaction of the first step in the discharge region.

The C ₂₊ hydrocarbon may be used as a raw material for conversion into high value added chemicals and high calorie fuels.

The first and second steps may be repeated one or more times. The DBD plasma reactor forms a low temperature plasma as an energy source, so no additional heat supply is required when performing the first and / or second steps.

The first and second steps may be performed in different DBD plasma reactors, but are preferably performed in the same dielectric barrier discharge (DBD) plasma reactor. This is because the carbon deposition mixture, which is inevitably accompanied by side reactions, can be removed by using the same plasma as the kind used in the reaction, and an oxygen-containing mixture is used instead of a methane-containing reaction mixture during the regeneration process. That is, the present invention can be decomposed and removed by activating carbon-containing deposits using a DBD plasma while injecting an oxygen-containing mixture (eg air) instead of supplying a methane mixture for regeneration.

On the other hand, since the non-oxidative coupling reaction of methane is accompanied by a dehydrogenation reaction, the dielectric barrier discharge plasma reactor and / or regeneration method for the non-oxidative coupling reaction of methane according to the present invention can also be applied to generate hydrogen from methane. Can be.

Thus, a method for producing hydrogen from methane through a non-oxidative coupling reaction of methane according to one embodiment of the present invention

Generating hydrogen from methane through a non-oxidative coupling reaction of methane in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles in the discharge region; And

And a second step of removing the coke with a low temperature plasma in an oxidizing atmosphere in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles deactivated due to coke formed during the reaction of the first step in the discharge region.

The first and second steps may be repeated one or more times. The DBD plasma reactor forms a low temperature plasma as an energy source, so no additional heat supply is required when performing the first and / or second steps.

The present invention can remove carbon-containing by-products such as carbon deposits and hydrocarbons generated in the reaction bed during the reaction by using a dielectric barrier discharge (DBD) plasma, which is a kind of low-temperature plasma. In particular, energy efficiency can be improved by suppressing or avoiding crystalline coke produced by the high temperature coupling process and realizing a low temperature methane coupling process and / or a low temperature regeneration process through a low temperature plasma.

1 illustrates one embodiment of an experimental apparatus for dielectric barrier discharge plasma.
Figure 2 shows the results after the TGA is performed on the charges collected after Example 1, Example 2, Comparative Example 1.
Figure 3 shows the results after the FT-IR analysis for the collected material collected after Preparation Example 2, Example 1, Example 2, Comparative Example 1.
Figure 4 shows the results after the TEM analysis for the collected material collected after Example 1, Example 2, Comparative Example 1.
Figure 5 shows the results after the small angle X-ray scattering (SAXS) analysis for the packing collected after Preparation Example 2, Example 1, Example 2, Comparative Example 1.
6 is a conceptual diagram showing streamers and reactive intermediates between dielectric particles due to induced micro electric fields.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are intended to illustrate the present invention more specifically, but the scope of the present invention is not limited by these examples.

Production Example  One:

The experimental apparatus of the dielectric barrier discharge plasma is shown in FIG. The plasma reactor used an alumina tube having a length of 700 mm, an outer diameter of 10 mm, and an inner diameter of 6 mm, which served as a dielectric barrier. A stainless steel rod with a diameter of 3 mm was used as a high voltage electrode, and a wire of 0.5 mm thickness was wound around the alumina tube by a spring shape of 150 mm and used as a ground electrode. A transformer (0 to 20 kV, 1000 Hz) was connected to the AC power supply (0 to 220 V, 60 to 1000 Hz), and an oscilloscope and high voltage probe were used to measure the voltage. In addition, by connecting a 1 uF capacitor in series to the reactor was measured the amount of charge in the plasma reactor by measuring the potential difference across the capacitor.

Quantitative analysis of the reactants was carried out using on-line Gas Chromatography (6500GC Young Lin Instrument Co., Korea). The detectors used FID and TCD detectors, and Porapak-N and Molecular Sieve 13x were used as columns for the thermal conductivity detector (TCD), and a metasizer was used as the flame ionization detector (FID). TCD detected H ₂ , N ₂ and CH ₄ , and FID detected CH ₄ , C ₂ H ₂ , C ₂ H ₄ , C ₂ H ₆ , C3 and C4 hydrocarbons.

Production Example  2: Packed bed  Material Used Porous Silica KIT-6

Mesoporous silica KIT-6 was prepared according to the following procedure. In order to form a three-dimensional structure of mesoporous silica KIT-6, a copolymer pluronic p-123 was used as a structure inducing agent. The copolymer forms micelles inside the aqueous solution and forms mesoporous silica structures through self-assembly and interaction with silicon ions. 6g of pluronic p-123 was added to an aqueous solution mixed with 217.64 ml of distilled water and 11.16 g of 37% by weight hydrochloric acid, and stirred rapidly at a temperature of about 35 ° C. until pluronic p-123 was completely dissolved. Thereafter, 6 g of n-butanol was added to the above mixed solution to form an Ia3d structure, which is an intrinsic structure of KIT-6, and further stirred for 2 hours while maintaining the temperature. Thereafter, 12.77 g of tetraethoxysilane (TEOS) was slowly added dropwise to the stirring solution, and stirred rapidly at a temperature of about 35 ° C. for 24 hours. After this process, the white silica precipitate formed solution was transferred to a polypropylene container and transferred to a hydrothermal synthesis apparatus, and the hydrothermal synthesis reaction was performed at about 100 ° C. for one day without stirring. Thereafter, a washing process was performed to remove the solvent remaining in the reaction solution. After 30 minutes of distilled water washing, filtration and 30 minutes of ethanol washing were performed three times to remove pluronic p-123 and residual impurities. Then, it was dried in an oven at 110 ℃ for one day. After drying, the white silica powder was heated up to 400 ° C. at a heating rate of 2 ° C./min, maintained for 3 hours, and then heated to 550 ° C. at a heating rate of 1 ° C./min, and maintained for 5 hours. Proceeded. The white silica powder, which had been calcined, was subdivided into 100-150 um using a sieve.

Example  1: Oxygen-free methane coupling reaction with a charge

A dielectric barrier discharge plasma reactor (FIG. 1) prepared in Preparation Example 1 was used. It stylized generate a plasma in the length of 150 mm by a high-voltage electrode and the ground electrode is wound in an alumina tube, a 3.181 cm ³ are high-voltage electrodes within the alumina tube other than the occupied volume The filling made through Preparation Example 2 was filled. The oxygen-free methane coupling reaction was carried out at room temperature and atmospheric pressure. MFCs for CH ₄ and N ₂ were connected to a DBD plasma bed and injected at a ratio of CH ₄ : N ₂ = 1: 1, and GHSV (Gas Hourly Space Velocity) was reacted with 2,500 mL · g ⁻¹ · h ⁻¹ . The experiment was carried out while maintaining a voltage of 15 kV and a frequency of 1000 Hz. The oxygen free methane coupling reaction was run for 1000 minutes.

The product was analyzed by on-line Gas Chromatography 20 minutes after the start of the reaction, the repeat analysis interval was performed for 40 minutes.

Example  2: low temperature Plasma  Use regeneration method

After Example 1, the deactivated charge was regenerated using DBD plasma. Plasma reactor configuration was configured in the same manner as shown in Figure 1, the experiment was carried out by filling the filling with the same volume as in Example 1. In addition, regeneration is the MFC were conducted under normal conditions is connected to a DBD plasma bed (bed plasma) was injected into the Air, GHSV (Gas Hourly Space Velocity) is the regeneration reaction to the 1,250 mL · g ^-1 · h ^-1 Proceeded. The experiment was carried out while maintaining a voltage of 15 kV and a frequency of 1000 Hz. The regeneration reaction was run for 720 minutes.

Comparative example  1: Regeneration by heat treatment

After Example 1, the deactivated packing was heated to 700 ° C. at a rate of 5 ° C./min using a muffle furnace, and maintained for 5 hours under a condition of 50 sccm of Air.

Example  3: deactivated filling, for regenerated filling TGA  practice

Example 1, Example 2, Comparative Example 1 after the TGA proceeded to the collected and the results are shown in Figure 2, the mass loss and total coke amount and removal rate is summarized in Table 1. When comparing the total amount of coke of Example 2 and Comparative Example 1, the effect of Example 2 may not seem obvious, but looking at the removal ratio, it can be seen that the difference between Example 2 and Comparative Example 1 is only 3.23% p. there was. This shows that Comparative Example 1 removed most of the coke, but Example 2 also removed the coke to a similar level.

Mass loss
(%) Total cork
(Coke per weight of filling (g-coke / g-SiO ₂ )) Removal rate ^a
(%) Remarks Example 1 37.32 0.60 - Generated by reaction
Check the amount of coke Example 2 2.30 0.02 96.67 Removed with plasma
Coke sheep Comparative Example 1 0.06 0.0006 99.90 Coke removed by heat treatment

^a amount of coke removed / total amount of coke of Example 1

Example  4: Confirm coke removal by FT-IR

FT-IR analysis was performed on the packings collected after Preparation Example 2, Example 1, Example 2, and Comparative Example 1, and the results are shown in FIG. 3. In the case of Example 1, it was confirmed that three vibration modes were found. ▲ is CH ₃ stretch vibration mode, ■ is asymmetrical C = C stretching mode, and ● is asymmetrical CH bending mode of methylene groups in a long aliphatic chain. On the other hand, in Example 2 and Comparative Example 1, the above vibration modes were not found. In the case of Preparation Example 2, Example 2, and Comparative Example 1, a similar peak was found at 1630 cm ⁻¹ , but this was an OH bending mode in which drying was sufficiently performed but adsorbed.

In addition, in Preparation Example 2, Example 1, and Example 2, Si-O-Si bonding was found at 806 cm ⁻¹ , while in Comparative Example 1, it was found at 816 cm ⁻¹ .

Example  5: TEM  Coke position analysis through images

Example 1, Example 2, Comparative Example 1 After the TEM analysis of the collected material was collected and the results are shown in Figure 4 the diagram. The TEM image of the filler after Example 1 is shown in FIG. 4-A, the TEM image of the filler after Example 2 is shown in FIG. 4-B, and the TEM image of the filler after Comparative Example 1 is represented by 4-C. It can be seen from Figure 4-A that the coke is stacked in a stacked form on the surface of the filler, but in the case of Figures 4-B and 4-C, the coke of the stacked structure was found to disappear a lot.

4 shows the results of EDX mapping analysis. In Table 2, the mass percent of carbon is reduced by 19.12% p in FIG. 4-B and the mass percent of carbon is reduced by 31.01% p in FIG. This shows that the low temperature DBD plasma and muffle kiln can effectively remove the coke of the inactivated charge.

Mass percent (%) C O Si 4-A (Example 1) 60.60 12.98 26.42 4-B (Example 2) 41.48 25.73 32.79 4-C (Comparative Example 1) 29.59 30.23 40.18

Example  6: XRD  Structural Stability through Characterization

After the preparation of Example 2, Example 1, Example 2, Comparative Example 1 and the small angle X-ray scattering (SAXS) analysis of the collected material is shown in Figure 5 the results. It was confirmed that the SAXS graph of the fillers collected after Example 1 and Example 2 was the same as the SAXS graph of the existing fresh filler. It was confirmed that the oxygen free methane coupling reaction and the charge regeneration reaction using the DBD plasma did not affect the structural stability of the charge. On the other hand, it was confirmed that the SAXS graph of the filler collected after Comparative Example 1 is different from the SAXS graph of the fresh filler. This confirms that the regeneration reaction using muffle kiln affects the structural stability of the packing.

Example  7: Structural Stability through BET Characterization

Table 3 shows BET surface areas, pore volumes, and pore sizes of Preparation Example 2, Example 2, and Comparative Example 1, respectively. Table 3 shows that in the case of the regeneration reaction using a muffle kiln, it is more difficult to maintain structural stability than the regeneration using a plasma.

BET Surface Area
(m ² / g) Pore volume
(cm ³ / g) Pore size
(nm) Preparation Example 2 774.92 1.12 6.40 Example 2 749.04 0.91 6.05 Comparative Example 1 546.68 0.76 6.01

Example  8: plasma  Review of reactivity of regenerated charge

Table 4 shows the results when the TOS was 60 minutes after the reactivity test was performed on the collected fresh KIT-6 and Example 2. The reaction conditions are the same as in Example 1. When comparing the reactivity of Fresh KIT-6 and Example 2 with the pre-reaction filler, the conversion of methane was slightly increased, but the selectivity of C2 hydrocarbon was slightly decreased. It is believed that traces of coke that were not completely removed remain as if coated on the surface of KIT-6, thus affecting the performance somewhat. However, the overall light hydrocarbon yield was similar to that of Fresh KIT-6 and was considered to be sufficient as a plasma bed for methane coupling.

CH ₄
Conversion (%) Selectivity (%) acetylene ethylene ethane C3
hydrocarbon C4
hydrocarbon Fresh KIT-6 41.80 15.53 6.39 21.64 10.74 11.54 Plasma-treated KIT-6 48.85 10.15 3.81 16.13 10.57 9.08

Claims (15)

A dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles in a discharge region, said DBD plasma reactor being designed to remove coke formed on the mesoporous dielectric particles by side reaction by plasma treatment in an oxidizing atmosphere. The method of claim 1, wherein the coke that is inevitably accompanied by side reactions during the reaction in the DBD plasma reactor is removed by utilizing the same plasma as the type used in the reaction, and the oxygen-containing mixture is supplied instead of the reaction mixture during the coke removal process. DBD plasma reactor characterized in that. The DBD plasma reactor of claim 1, wherein the mesoporous dielectric particles are regular mesoporous dielectric particles. The DBD plasma reactor of claim 1, wherein the DBD plasma reactor is designed to allow a non-oxidative coupling reaction of methane to occur in a plasma bed with mesoporous dielectric particles. 5. The DBD plasma reactor of claim 4, wherein during the non-oxidative coupling reaction of methane, C-H bonds are activated to produce methyl radicals and direct C 2 -C 4 light hydrocarbons without additional thermal energy and oxidant molecules. 5. The DBD plasma reactor according to claim 4, wherein the mesoporous dielectric particles serve as a catalyst for the non-oxidative coupling reaction of methane. 5. The DBD plasma reactor according to claim 4, wherein the mesoporous dielectric particles further carry a catalytically active component for the non-oxidative coupling reaction of methane. 8. The DBD plasma reactor of claim 1, wherein the DBD plasma reactor is characterized using at least one of the micro-electrode concepts described below. 9.
(1) micro electrodes are induced between dielectric particles charged by an external electric field, and a local micro electric field is induced between the dielectric particles;
(2) from outside Streamer and micro-discharge propagated between polarized micro electrodes due to high voltage and dielectric barrier;
(3) The streamer and micro discharge reach the top surface of one particle, the particles are positively charged due to polarization, and at this moment the bottom surface is negatively charged, so the top surface and the bottom surface are each anode type. like and cathode-like surfaces, starting from particles near the outer cathode and continuing from particle to particle in the direction of the opposite electrode;
(4) As the streamer surrounds the dielectric particles, the electrons are scattered like seeds from the lower surface of the particles because the photoelectric ionization enhances the local electric field's intensity, and the electrons scattered like seeds cause another avalanche At the moment, nitrogen and methane molecules collide with the accelerated electrons, positively charged ions are generated, and cations generated under an enhanced electric field accelerate and move to the cathode surface, and collide with the surface. This collision creates secondary electrons to sustain the streamer;
(5) The induced local electric field and the charged surface of the induced particles are viewed as micro electric fields and micro electrodes, respectively, as if the surface with induced charges are micro-cathode and micro-anode, between adjacent particles. Apply the modified Paschen's equation of Equation 1 to the induced local micro electric field.
[Equation 1]

here,
ΔV _{B, micro} : threshold electric potential difference between micro-electrodes to initiate plasma discharges.
d _micro : gap distance between two micro-electrodes
d _{min, micro} : minimum gap distance between two micro-electrodes
γ: second Townsend ionization coefficient; Second Townsend Ionization Coefficient (secondary electron emission coefficient of micro-cathode)
σ: collision cross-sectional area of the gas molecule
E _micro : electric field strength between two micro-electrodes
U _i : ionization potential of the gas molecule
k _B : Boltzmann constant
T: gas temperature
p: gas pressure
A: ionization characteristic constant of the gas molecule (Equivalent to σ / k _B T)
B: ionization characteristic constant of the gas molecule. (Equivalent to U _i σ / k _B T) In the dielectric barrier discharge (DBD) plasma reactor according to any one of claims 1 to 7, characterized in that the coke is removed from the mesoporous dielectric particles deactivated due to the coke formed by the side reaction with a low temperature plasma under an oxidizing atmosphere. Regeneration method of mesoporous dielectric particles. 10. The method of claim 9, wherein the coke removed by cold plasma treatment is amorphous carbonaceous, graphite carbonaceous materials, or both. 10. The method of claim 9, wherein the regenerated mesoporous dielectric particles maintain a regular mesoporous structure or a crystal structure inherent to the dielectric particle prior to use. In a process for producing C ₂₊ hydrocarbons from methane through a non-oxidative coupling reaction of methane,
Converting methane to C2 or more hydrocarbons, including ethylene and / or ethane, through a non-oxidative coupling reaction of methane in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles in the discharge region; And
A second step of removing the coke with a low temperature plasma under an oxidizing atmosphere in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles deactivated due to coke formed during the reaction of the first step in the discharge region;
C ₂₊ hydrocarbon production process characterized in that the first step and the second step is repeated one or more times. 13. The method of claim 12, wherein the first step and the second step is characterized by a method for producing C ₂₊ hydrocarbon is carried out in the same dielectric barrier discharge (DBD) plasma reactor. In a process for producing hydrogen from methane through a non-oxidative coupling reaction of methane,
Generating hydrogen from methane through a non-oxidative coupling reaction of methane in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles in the discharge region; And
A second step of removing the coke with a low temperature plasma under an oxidizing atmosphere in a dielectric barrier discharge (DBD) plasma reactor having mesoporous dielectric particles deactivated due to coke formed during the reaction of the first step in the discharge region;
Hydrogen production method characterized in that the first step and the second step is repeated one or more times. 15. The method of claim 14, wherein the first and second steps are performed in the same dielectric barrier discharge (DBD) plasma reactor.

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