JPH10298121A - Direct synthesis of methanol from methane and water - Google Patents

Abstract

(57) [Problem] To establish a new direct methanol synthesis method from methane and water with a simple reaction process (energy-friendly). SOLUTION: This is a method of synthesizing methanol from natural gas and water or methane and water by surface discharge according to a direct synthesis reaction shown in the following reaction formula. CH ₄ + H ₂ O → CH ₃ OH + H _2- △ H (-△ G) Since the reaction is completed in one step, the reaction process is greatly simplified, and the number of moles does not change before and after the reaction. In proceeding, there is no dependence on gas pressure, and the endothermic amount is ΔH = 121.2 kJ / CH ₄ 1 mol, which is about half that of the conventional method for practical use. A planar dielectric 1 is placed on one planar continuous electrode 2, and a linear or slit-shaped split electrode 3 is disposed on the planar dielectric 1. Natural gas and water or methane and water are disposed on the surface of the dielectric 1. A fluid flow path comprising: A plurality of units for directly synthesizing unit methanol may be stacked via the partition plate 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for directly synthesizing methanol from methane and water in natural gas.

[0002]

2. Description of the Related Art In order to make the most of the chemical energy that fossil fuels (hydrocarbon-based fuels) originally possess, fossil fuels are reformed into fuels with higher chemical energy rather than directly burning them. It is advantageous to burn it later.

Generally, the chemical energy of fuel is represented by the calorific value and exergy. Exergy here means the maximum work (power energy) that can be extracted from the heat generation amount.

Methane (CH ₄ ), which is a main component of natural gas
Table 1 shows a comparison of calorific values among chemical energies of the combustion components after reforming methane.

[Table 1]

The reaction formulas (1) to (1) in the remarks column of Table 1
(11) and the calorie balance of each are shown below. (A) Direct combustion reaction of natural gas (or methane) CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O-ΔH (−ΔG) (1) -74.5 0 -393.5 -285.8 × 2 ΔH = -890.6 (heat generation) ) -50.9 0 -394.5 -237.2 × 2 △ G = -817.9 Heat value 890.6 kJ / 1 mol CH ₄

(B) Partial reforming reaction of natural gas (or methane) CH ₄ + H ₂ O → CO + 3H ₂ -ΔH (−ΔG) (2) -74.5 -285.8 -110.6 0 ΔH = 249.7 (endothermic) -50.9 -237.2 -137.3 0 △ G = 150.8 CO + 1 / 2O ₂ → CO _2- △ H (-△ G) (3) -110.6 0 -393.5 △ H = -282.9 (heat generation) -137.3 0 -394.4 △ G = -257.1 3H ₂ + 3 / 2O ₂ → 3H ₂ O- △ H (-△ G) (4) 0 -285.8 × 3 △ H = -857.4 (heat generation) 0 0 -237.2 × 3 △ G = -711.6 Heat value 1143.3 kJ / 1 mol CH ₄

(C) Complete reforming reaction of natural gas (or methane) CH ₄ + H ₂ O → CO + 3H ₂ -ΔH (−ΔG) (5) -74.5 -285.8 -110.6 0 ΔH = 249.7 (endotherm) -50.9 -237.2 -137.3 0 △ G = 150.8 CO + H ₂ O → CO ₂ + H _2- △ H (-△ G) (6) -110.6 -285.8 -393.5 0 △ H = 2.9 (endothermic) -137.3 -237.2 -394.4 0 △ G = -19.9 4H ₂ + O ₂ → 4H ₂ O- △ H (-△ G) (7) 0 0 -285.8 × 4 △ H = -1143.2 (heat generation) 0 0 -237.2 × 4 △ G = -948.8 Heat value 1143.2 kJ / 1 mol CH ₄

(D) Natural gas (or methane) → natural gas (or methane) reforming gasification → methanol synthesis → methanol combustion CH ₄ + H ₂ O → CO + 3H ₂ −ΔH (−ΔG) (8) − 74.5 -285.8 -110.6 0 △ H = 249.7 (endothermic) -50.9 -237.2 -137.3 0 △ G = 150.8 CO + 2H ₂ → CH ₃ OH- △ H (-△ G) (9) -110.6 0 -239.1 △ H =- 128.5 (heat generation) -137.3 0 -166.4 △ G = -29.1 CH ₃ OH + 3 / 2O ₂ → CO ₂ + 2H ₂ O- △ H (-△ G) (10) -239.1 0 -393.5 -285.8 × 2 △ H =- 726.1 (heat generation) -166.4 0 -394.4 -237.2 × 2 ΔG = -702.4 H ₂ + 1 / 2O ₂ → H ₂ O-ΔH (−ΔG) (11) 0 0 -285.8 ΔH = -285.8 (heat generation 0 0 -237.2 ΔG = -237.2 Calorific value 1011.8 kJ / 1 mol CH ₄

The reaction (b) is carried out by a method generally referred to as "steam reforming of methane".
> 0. Since this endothermic amount is added to methane as the raw fuel, the generated gas (CO + 3H ₂ )
Produces more heat than methane.

However, the exergy change in equation (2) is ΔG
Since it is> 0, it is necessary to add high-quality energy to some extent in order to advance the reforming reaction. In order to react at atmospheric pressure, a temperature condition of about 700 ° C. is required even if a catalytic effect is utilized. Higher pressures require higher temperatures.

In the reaction of (c), carbon monoxide (CO) produced by the formula (5) “steam reforming of methane” is further converted to hydrogen by the reaction shown in the formula (6) (referred to as a shift reaction). . Since the reaction of the equation (6) is an endothermic reaction, the calorific value of the reformed gas finally generated from 1 mol of methane is 1
It is increased to 143.2 kJ.

The exergy change of the reaction of equation (6) is ΔG =
With the current technology, the reaction can be sufficiently advanced with low-quality energy of about 200 ° C. utilizing the catalytic effect.

The reaction (d) synthesizes methanol using CO and H ₂ generated by “steam reforming of methane” in the formula (8). Although the amount is reduced, the transportability is improved, and there is an advantage that the calorific value equivalent to the reaction (c) can be secured by a slight treatment at the fuel utilization place.

In general, the quality of fuel at atmospheric temperature and atmospheric pressure is evaluated by its calorific value and exergy. Exergy is called "effective energy" in JIS, and thermodynamically called "gibbs free energy". Exergy means the maximum work (power energy) that can be extracted from the calorific value. Therefore, it can be said that fossil fuels should be reformed and converted to fuels with higher effective energy.

Table 2 shows the calorific value, exergy and exergy rate of typical fuels. A high exergy fuel is a fuel that can have high conversion efficiency to power (or electric power) energy, and the characteristics of the fuel from the viewpoint of exergy are as follows.

[Table 2]

The exergy rate (100 × △ G / △ H) is
It changes in the order of solid fuel> liquid fuel> gas fuel, and a fuel with a high density can burn a fuel having the same calorific value in a narrower space. Therefore, the rate of pressure rise due to combustion increases, and the amount of conversion to motive power increases.

Since carbon has a higher molecular weight than that of hydrogen, a fuel having many carbon atoms has a high density, and a fuel having more carbon atoms (C) relative to hydrogen atoms (H) has a higher exergy ratio. The calorific value per volume is relatively high, and a large amount of power conversion is obtained. On the other hand, the exergy of hydrogen is low, and hydrogen becomes water when the combustion gas is 100 ° C or less,
Since it cannot be used as an energy source for extracting power, exergy is reduced. This is because when it becomes a liquid, it does not expand and power cannot be taken therefrom. Here, exergy means power or electricity (exergy rate = 100
%). Since oxygen is a non-flammable component, fuels containing oxygen atoms have low exergy. The combustible components of fossil fuels are hydrogen and carbon.

In order to extract more power / electrical energy from fossil fuels under the above premise, it is desirable to convert fossil fuels to fuels with higher exergy. Now, methane, which is a main component of natural gas, is subjected to reforming gas (CO + H ₂ ) or methanol (CH ₃ O).
H) and the like, the calorific value of the generated fuel and exergy are compared as shown in Table 3.

[Table 3]

Here, natural gas (or methane) shown in Table 3 is used.
→ Natural gas (or methane) reforming gasification → Methanol synthesis → Methanol reforming gasification → Gas combustion reaction formula is as follows. CH ₄ + H ₂ O → CO + 3H ₂ −ΔH (−ΔG) (12) -74.5 -285.8 -110.6 0 ΔH = 249.7 (endothermic) -50.9 -237.2 -137.3 0 ΔG = 150.8 CO + 2H ₂ → CH ₃ OH -△ H (-△ G) (13) -110.6 0 -239.1 △ H = -128.5 (heat generation) -137.3 0 -166.4 △ G = -465.2 CH ₃ OH + H ₂ O → CO ₂ + 3H _2- △ H (-△ G) (14) -239.1 -285.8 -393.5 0 △ H = 131.4 (endothermic) -166.4 -237.2 -394.4 0 △ G = 9.2 4H ₂ + 2O ₂ → 4H ₂ O- △ H (-△ G) (15) 0 0 -285.8 × 4 △ H = -1143.2 (heat generation) 0 0 -237.2 × 4 △ G = -948.8 Heat value 1143.2 kJ / 1 mol CH ₄

By converting methane to methanol (CH ₃ OH), the chemical energy originally possessed by methane increases the calorific value by about 14%, exergy by about 15%, and exergy rate by about 1.1 points. Thus, methane fuel can be used more effectively. This increase in chemical energy is not a sudden rise, but rather an endothermic component during the reaction added to the reformed fuel (if the reaction is an exothermic reaction, the chemical energy will decrease). ).

Further, as shown at the bottom of Table 3, by reforming methanol to hydrogen by the reaction of the formula (14), the calorific value is reduced by 2 compared to methane as the raw fuel.
8.4%, exergy can be increased by 16%. Therefore, the calorific value and exergy are maximized due to the transportability of methanol, which is a liquid fuel, and the simple reforming of hydrogen into hydrogen at the place where the fuel is used (the exhaust heat of about 200 ° C can be used as the supply energy for the reforming reaction) Considering that it can be increased to a value, the effectiveness of reforming methane to methanol can be understood.

However, a reactor is required to reform methane, and it is necessary to select an optimum reformer in consideration of transportability of reformed fuel, fuel quality (exergy), and the like. is necessary.

Therefore, a conventional method for producing methanol will be briefly described. [1] CO hydrogenation method Methanol (CH ₃ OH) can be obtained by using the formulas (16) and (17)
Hydrocarbon fuels such as natural gas and naphtha
Hydrogen and carbon monoxide obtained by steam reforming at 700 to 800 ° C. under normal pressure to several tens of atmospheres in the presence of a system catalyst
It is manufactured by synthesis at high pressure in the presence of a ₂ O ₃ catalyst or a Cu-based catalyst. The reaction formula and chemical energy change for methane, which is the main component of natural gas, are shown below. CH ₄ + H ₂ O → CO + 3H ₂ −ΔH (−ΔG) (16) -74.5 -285.8 -110.6 0 ΔH = 249.7 (endothermic) -50.9 -237.2 -137.3 0 ΔG = 150.8 CO + 2H ₂ → CH ₃ OH -△ H (-△ G) (17) -110.6 0 -239.1 △ H = -128.5 (heat generation) -137.3 0 -166.4 △ G = -29.1

Since the synthesis of methanol is a reaction in which the number of moles after the reaction decreases as shown in the formula (17), the higher the pressure, the more the reaction proceeds, but the problem is to reduce the pressure. As one of the measures, a Cu-based catalyst has high activity and excellent selectivity, but has a drawback that it is weak to reforming poison and heat (temperature). The conventional methanol production method that has been put into practical use requires a large amount of high-quality energy in the reaction of the formula (16), which is a steam reforming process, and the steam reforming process has a high exergy loss ratio (all processes). Exergy loss of 65.7
%). Further, in recent years, with the attention of methanol as a basic substance of Cl chemistry, development of a new catalyst and development of a synthesis method as described below are being studied.

[2] Methanol synthesis method by hydrogenation of CO ₂ The reaction formula is as shown in formulas (18) and (19). CH ₄ + 2H ₂ O → CO ₂ + 4H ₂ -ΔH (−ΔG) (18) -74.5 -285.8 × 2 -395.5 0 △ H = 252.6 (endothermic) -50.9 -237.2 × 2 -394.4 0 △ G = 130.9 CO + 3H ₂ → CH ₃ OH + H ₂ O-ΔH (−ΔG) (19) -393.5 0 -239.1 -285.8 ΔH = -164.6 (exothermic) -394.4 0 -166.4 -237.2 ΔG = -9.2 (easy to react ) (H ₂ : excess hydrogen produced)

This synthesis method has been put to practical use [1].
Is disadvantageous in terms of equilibrium because the change in ΔG is large as compared with the method for hydrogenating CO (carbon monoxide), but the reaction proceeds rapidly at around 200 ° C. when a Cu / ZnO catalyst is used. It is clear and development is underway for practical use.

[3] Low Temperature Liquid Phase Methanol Production Method by Partial Oxidation Method This method is based on the partial oxidation method with air, and the reaction formula is as shown in the following formula (20). CH ₄ + 1 / 2O ₂ → CH ₃ OH- △ H (-△ G) (20) -74.5 0 -239.1 ΔH = -164.6 (exothermic) -50.9 0 -166.4 ΔG = -115.5 (large reactivity)

As the catalyst, a volatile liquid is used.
The reaction proceeds at a low pressure of about 12.5 atm. [2]
There is a possibility that plant construction costs may be significantly reduced as compared with the reaction in the gas phase, and it is currently under consideration on a bench scale.

According to this method, from the viewpoint of easiness of the reaction,
G = -1155.5 kJ / mol, which is advantageous because the exergy change is small. However, in terms of energy utilization, a part of the raw fuel is burned to synthesize methanol, so that there is a disadvantage that the calorific value (-ΔH) of the product is reduced.

[0030]

In the conventional method for synthesizing methanol from methane, for example, the conventional method for producing methanol which has been put into practical use is represented by the formula (16) in the steam reforming step.
It is disadvantageous that a large amount of high-quality energy is required, and the other methods according to equations (18) to (20) are only in the stage of development. An object of the present invention is to establish a new method for directly synthesizing methanol from methane and water with a simple reaction process (energy-friendly).

[0031]

The above object of the present invention is attained by the following constitution. This is a method for directly synthesizing methanol from methane and water, which comprises synthesizing methanol directly from natural gas and water or methane and water by surface discharge.

In the present invention, a planar dielectric is placed on one of the planar electrodes, and a linear or slit-shaped divided electrode is arranged on or near the surface of the planar dielectric, and the divided electrode is An apparatus for directly synthesizing methanol from methane and water is provided, wherein a flow path of a fluid composed of natural gas and water or methane and water is provided on the surface of the dielectric to be arranged.

A planar dielectric is placed on one of the planar electrodes, and a linear or slit-shaped divided electrode is disposed on or near the surface of the planar dielectric, and the dielectric on which the divided electrode is disposed is disposed. A device for direct synthesis of methanol from methane and water, wherein a plurality of units for direct synthesis of unit methanol having a flow path of a fluid composed of natural gas and water or methane and water on the surface side are stacked via partition means. Are also within the scope of the present invention.

The reaction formula (21) of the direct methanol synthesis method of the present invention and its features will be described. CH ₄ + H ₂ O → CH ₃ OH + H ₂ −ΔH (−ΔG) (21) -74.5 -285.8 -239.1 0 ΔH = 121.2 (endothermic) -50.9 -237.2 -166.4 0 ΔG = 121.7

The direct synthesis of methanol from methane and water
The exergy change is a positive value (ΔG = 121.7 kJ / mole of methane), and thermal direct synthesis is not a practical process. However, if this method can be realized, it has the following significant advantages as compared with the conventional method, and is an effective technique. Since the reaction only needs to be performed in one step, the reaction process is greatly simplified. The conventional method requires at least two steps of a “natural gas reforming step” and a “methanol synthesis step”. As seen from the equation (21), there is no change in the number of moles before and after the reaction, so that there is no dependence on the gas pressure in promoting the reaction.

In the conventional method for producing methanol by hydrogenation of CO, the pressure condition in steam reforming of methane is increased in the number of moles in the formula (16). On the other hand, in methanol synthesis, the formula (1)
As seen in 7), high pressure is more desirable. Accordingly, the former is pressurized to normal pressure to several tens of atmospheres, and the latter is pressurized to several hundreds of atmospheres, which complicates the process. The heat absorption is ΔH = 121.2 kJ / CH ₄ 1 mol, which is about half that of the conventional method.

In the conventional method, endothermic (Equation (16)) during the natural gas reforming process, and exothermic (Equation (1)
7)), and ΔG = 15 in the reaction of the equation (16).
Since the positive value is as large as 0.8, high-quality (high-temperature) energy is required. In the reaction of the equation (17), low-quality (low-temperature) energy is sufficient because ΔG = -29.1. However, since the heat transfer of the reactions of the formulas (16) and (17) cannot be shared, in the actual plant, it is necessary to individually supply / remove each reaction heat. Since the method of the present invention is an endothermic reaction as compared with the partial oxidation method shown in the formula (20) having the feature of direct methanol synthesis similar to the synthetic method of the present invention, the energy input during the synthesis is chemical energy. (Calorific value) is added to the reaction product.

On the other hand, since the partial oxidation method represented by the formula (20) is an exothermic reaction, a part of the raw fuel is oxidized to progress the synthesis reaction. Therefore, the chemical energy of the reaction product (calorific value ΔH) is smaller than that of the raw fuel. However, in the reaction of equation (20), the exergy change is a negative value,
There is an advantage that direct synthesis is possible by a catalytic reaction.

When the method of the present invention is compared with other methanol production methods, the following can be said. (A) Comparison with other discharge methods In order to promote the reaction by discharge, the required requirements are as follows. Practically, it is desirable that methanol be continuously produced by a discharge reaction under a steady flow condition of a raw material gas at normal pressure. Generally, it is difficult to constantly maintain a high-energy non-equilibrium state, and metal electrodes tend to shift to arc discharge. When a transition is made to arc discharge, most of the discharge energy changes to heat energy and does not contribute to the reforming reaction of methane, resulting in lower energy efficiency. The methanol synthesis reaction is a reaction between radicals,
A higher pressure is desirable to increase the frequency of radical collisions. However, except for the creeping discharge (including the case of the ozonizer discharge), it is generally indispensable to reduce the pressure of the gas in order to maintain a stable discharge.

It is effective to carry out an extremely short pulse spark discharge. By using an extremely short pulse spark discharge, the transition to a continuous arc can be suppressed. Still, pressure conditions below atmospheric pressure are required. Further, the short pulse discharge has a disadvantage that the discharge area cannot be adjusted. The glow discharge is a stable continuous discharge mode, but requires sufficient pressure reduction conditions. In addition, since the discharge is continuous, unless the source gas supply rate corresponding to the discharge and reaction rate is sufficiently optimized, the loss of energy consumption increases. The glow discharge can adjust the discharge region, for example, the discharge light emission region increases with an increase in current, but requires about 100 times the input energy of the spark discharge. Ozonizer discharge is a technology that has been put to practical use as an ozone generator, and creeping discharge is one of the types, and it is easy to study the practical application.

As described above, general methods for effectively proceeding a chemical reaction without causing arc discharge by a discharge method other than the creeping discharge of the present invention include a glow discharge and an ultrashort pulse spark discharge. However, each has the disadvantages described above.

On the other hand, in the ozonizer discharge to which the surface discharge according to the present invention belongs, by covering the electrode surface with a dielectric material having a high insulating property, an unsteady current flows but a steady current does not flow to suppress the transition to arc discharge. Can be. In the ozonizer discharge, methane and hydrogen can be discharged from low pressure to normal pressure, and the discharge area can be expanded by using divided electrodes.

Further, the method of the present invention is compared with other methanol production methods and the chemical energies of the above [1] to [3], and the exergy change accompanying methanol production and the fuel (methanol) produced after the reaction are compared. Table 4 shows the calorific value of surplus hydrogen).
Put together. Here, it is desirable that the exergy change accompanying the reaction be small from the viewpoint of easiness of the reaction.
On the other hand, it is desirable that the calorific value of the reaction product be large.

[Table 4]

As described above, the method for directly synthesizing methanol from natural gas (or methane) by creeping discharge according to the present invention is comparable to other methods.

[0045]

The feature of the methanol synthesizing method of the present invention is that methanol is directly synthesized from natural gas (or methane) and water by creating a high-energy non-equilibrium state on the dielectric surface by creeping discharge. The chemical reaction of the present invention by creeping discharge proceeds as follows. In the discharge region, a large difference occurs between the stored energy of electrons and the stored energy of neutral particles and ions. Reactive species (radicals, CH ₃ , OH) are generated from stable molecules (CH ₄ , H ₂ O) by some high-energy electrons, and the reaction rate of certain chemical reactions is selectively increased. Get higher. For this reason, it becomes possible to relatively easily advance the reaction in which the exergy change, which is substantially impossible by the thermochemical reaction, becomes a positive value.

For effective production of methanol, OH radicals and CH ₃ radicals are rapidly generated from methane (CH ₄ ) and water (H ₂ O) by discharge, and OH + CH ₃ → CH ₃ O
After the reaction of H is performed, it is necessary to quench immediately and converge the reaction while the non-equilibrium is high.

Creepage discharge is a kind of ozonizer discharge. However, since discharge along an insulating surface is more likely to occur than discharge in a gas, transition to an arc is suppressed even when the gas pressure is high. Therefore, discharge is possible, and is distinguished from spark discharge as creeping discharge.

As shown in FIG. 1, an electrode is provided on the surface of a dielectric 1, one of which is a continuous electrode 2, and the other is a line-shaped or slit-shaped divided electrode 3.
Discharge A occurs on the surface of the dielectric 1 in a direction perpendicular to the direction A. Although the discharge A is along the surface of the dielectric 1, it is substantially a discharge in a gas, and the effect on the reaction is the same as that of a spark discharge.

According to the experimental results, it was confirmed that methanol having a concentration of 0.5 to 0.7 mol% can be directly synthesized by spark discharge A. This value is about four orders of magnitude higher than the equilibrium concentration of methanol. In order to maintain the discharge A, it is necessary to remove a charge by applying a reverse voltage and repeat the same, and an alternating current is used as a power supply.

[0050]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A configuration example of a reactor for direct synthesis of methanol by creeping discharge according to an embodiment of the present invention will be described with reference to the drawings. An example of the structure of the reactor is shown in the sectional view of FIG. The dielectric 1 is integrally formed on the planar continuous electrode 2, and a plurality of divided electrodes 3 formed on the surface thereof by coating, thermal spraying or the like are laminated via a partition plate 4.

The shape of the divided electrode 3 affects the firing voltage, and FIG. 3A to FIG.
The discharge can be started at a low voltage by making the reactor thin and having small projections as shown in a partial sectional view of the reactor.

The interval between two adjacent divided electrodes 3 is set to a value that does not interfere with the discharge range between the adjacent electrodes.
In addition, since the current that can flow in one discharge is limited by the amount of electric charge stored in the dielectric 1, it is desirable to use a material of the dielectric 1 having a high dielectric constant.

The dielectric material 1 having a high dielectric constant includes barium titanate (relative dielectric constant: 5000) and lithium niobate (8).
4.6), glass (about 7.0), alumina (8.
5) and mica (7.0).

Since the discharge in each gas channel in the reactor occurs on the surface of the derivative 1, the lower the gas channel height, the higher the volume efficiency. Further, by using the flat continuous electrode 2 in common,
It is possible to have a laminated structure. Further, a gas cooling structure for quenching the synthesized methanol, a catalyst device on the surface of the dielectric 1 for promoting the synthesis, and the like may be provided.

Next, the energy consumption of the direct synthesis of methanol by creeping discharge in this embodiment using a small reactor will be described. FIG. 4 (FIG. 4 (a) is a plan view, FIG. 4 (b) is a side view), and the shape of the split electrode 3 is based on the discharge performed using the one shown in FIG. 3 (d). The energy consumption of direct methanol synthesis from methane and water is shown in Table 5. The columnar divided electrode 3 is mounted on a dielectric 1 made of barium titanate (size 40 × 40 mm), and the dielectric 1 is a planar continuous electrode 2 (size 40 × 40 mm).
40 mm). Further, a reactive gas flow path is formed on the dielectric 1 by the partition plate 4.

As shown in Table 5, in addition to the surface discharge, glow discharge and spark discharge are the small reactors shown in FIG. 5 (FIG. 5 (a) is a plan view and FIG. 5 (b) is a side view). And compared with creeping discharge. A flat continuous electrode 2 (size 40 × 40 mm) in a reaction gas flow path formed by the partition plate 4
A plurality of insulators 6 are arranged at predetermined intervals at positions adjacent to each other, and a columnar split electrode 3 is arranged above the intervals. The interval between the insulators 6 is divided electrode 3
This is for specifying the position of the spark discharge B between the electrode and the flat continuous electrode 2.

[0057]

[Table 5]

In the description of Table 5, the term “discharge power” means the energy consumption (k) with respect to the amount of methanol produced (mole number).
J / CH ₃ OH (1 mol), and the discharge ratio refers to the ratio of the discharge time.

As shown in Table 5, when creeping discharge is adopted, stable discharge can be performed even at atmospheric pressure (760 torr) or higher. Is easy to progress. In addition, the discharge voltage is reduced by improving the electrode shape,
Current and discharge rate (ie, AC frequency and pulse sustain time)
The conversion of methanol was optimized by optimizing the reaction conditions, such as optimization of gas flow rate, gas flow rate and gas temperature, and combined use of catalysts.
(> 0.8 mol%). This conversion was about 5-7 mol% at the reactor outlet in current large-scale utility plants.

Further, the energy consumption of methanol production by reforming and synthesizing natural gas (or methane), which has been put to practical use, is reduced by a large-scale methanol production apparatus of 1,000 tons / day class, in terms of raw material unit (for methanol production). The required energy) is 7.2 × 10 ⁶ kcal / ton (=
55 kJ / CH ₃ OH), whereas the energy consumption of the reaction due to the surface discharge at the laboratory level shown in Table 5 above is 38 kJ / CH ₃ OH. Considering this, there is a possibility that the discharge method according to the present invention can be sufficiently advantageous in terms of energy consumption at the stage of practical use over existing technologies. In addition, the unit consumption of raw materials of the actual large-scale methanol production equipment of 1000 tons / day is a numerical value achieved as a result of energy saving measures since the oil shock in 1973. Considering that 14,000 kW to 15400 kW / 1000 tons / day are required, the usefulness of the method of the present invention can be understood.

[0061]

According to the present invention, the reaction is completed in one step as compared with the steam reforming method of methane which has been put into practical use, so that the reaction process is greatly simplified, and before and after the reaction. Since there is no change in the number of moles, there is no dependence on the gas pressure in promoting the reaction. In addition, the heat absorption can be reduced to about half.
It also has the characteristic of low energy consumption of the reaction.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of creeping discharge to which the present invention is applied.

FIG. 2 is a sectional view of a reactor for directly synthesizing methanol from natural gas by creeping discharge according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an example of the shape of a split electrode of a reactor for direct synthesis of methanol from natural gas by surface discharge according to an embodiment of the present invention.

FIG. 4 is a diagram of a reactor for direct synthesis of methanol from natural gas by surface discharge according to an embodiment of the present invention.

FIG. 5 is a diagram of a reactor for direct synthesis of methanol from natural gas by spark discharge according to a comparative example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric 2 Plane continuous electrode 3 Split electrode 4 Divider

Claims (4)

[Claims] 1. A method for directly synthesizing methanol from methane and water, comprising directly synthesizing methanol from natural gas and water or methane and water by surface discharge. 2. A planar dielectric is placed on one planar electrode, and a linear or slit-shaped divided electrode is disposed on or near the surface of the planar dielectric, and the dielectric on which the divided electrode is disposed is disposed. An apparatus for directly synthesizing methanol from methane and water, wherein a flow path for a fluid comprising natural gas and water or methane and water is provided on the surface side. 3. A planar dielectric is placed on one planar electrode, and a linear or slit-shaped divided electrode is disposed on or near the surface of the planar dielectric, and the dielectric on which the divided electrode is disposed is disposed. A device for direct synthesis of methanol from methane and water, wherein a plurality of units for direct synthesis of unit methanol having a flow path of a fluid composed of natural gas and water or methane and water on the surface side are stacked via partition means. . 4. The apparatus for directly synthesizing methanol from methane and water according to claim 2, wherein the shape of the split electrode is such that discharge starts at a low voltage and the electric field intensity increases. .