JP4565277B2 - Lower hydrocarbon aromatization catalytic reaction method, aromatization catalytic reactor, aromatic compound and hydrogen production method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aromatic compound mainly composed of benzene and naphthalene used as a raw material in a chemical industry, a pharmaceutical industry, etc., from a gas containing methane such as natural gas or biogas, a fuel for a fuel cell, Or it relates to the catalytic reaction for efficiently producing hydrogen used in the semiconductor industry, from the field of synthesis of aromatic compounds, the field of reforming to produce hydrogen from methane, and thus not discharging process CO ₂ This invention relates to the environmental conservation field.
[0002]
[Prior art]
Conventionally, as a catalyst for directly aromatizing methane by one-step reaction, as shown in Patent Documents 1 to 6, methane is directly aromatized by optimizing the pore size of the porous metallosilicate and the supported metal species. The inventors have developed a catalyst for producing hydrogen in parallel and a method for producing the aromatic compound and hydrogen.
In these patent documents, a raw material gas such as methane or natural gas is directly introduced into a catalytic reaction vessel, and an aromatic compound and hydrogen are simultaneously generated by catalytic reaction. However, when such an organic compound is reacted at a high temperature, in addition to the target reaction, a reaction in which the organic substance is thermally decomposed into carbon and hydrogen occurs in parallel. There was a problem of lowering. In order to solve such problems, a method has been proposed in which carbon monoxide or carbon dioxide is added to the raw material gas in an amount of 0.01 to 30%, thereby reducing the formation and deposition of carbon and extending the life of the catalyst. (Patent Documents 3 to 5).
[0003]
Similarly, Zhang et al. Have reported that deterioration of a catalyst can be suppressed by introducing raw material methane and hydrogen alternately into a reactor in a reaction in which aromatics and hydrogen are produced together (non-patent document). 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-272366 [Patent Document 2]
Japanese Patent Laid-Open No. 11-47606 [Patent Document 3]
Japanese Patent Laid-Open No. 11-60514 [Patent Document 4]
JP 2001-334151 A [Patent Document 5]
JP 2001-334152 A [Patent Document 6]
JP 2002-336704 A [Non-Patent Document 1]
12th Hokkaido University Catalysis Center International Symposium, November 18-20, 2001, Sapporo. Proceedings p15-16
[0005]
[Problems to be solved by the invention]
However, among these conventional techniques, in the method of reacting the raw material gas as it is on the catalyst, the catalyst performance deteriorated over time as described above, and there was a great practical problem. On the other hand, the method of adding carbon monoxide and carbon dioxide to the raw material gas has the effect of extending the catalyst life, but it is very sensitive to the amount of carbon monoxide and carbon dioxide to be added. Since the reaction characteristics and life characteristics of the catalyst change greatly only by changing the amount, when applied to a full-scale plant, the addition amount must be strictly controlled, which causes operational difficulties. Further, when an additive containing oxygen such as carbon monoxide or carbon dioxide is used, -carbon oxide is contained in the generated gas. When the generated hydrogen is used as fuel for fuel cells, the concentration of carbon monoxide that poisons fuel cell electrodes must be kept as low as possible, so this method produces aromatics and hydrogen. However, in order to use this hydrogen as a fuel for fuel cells, it was necessary to add a device for removing carbon monoxide.
[0006]
On the other hand, the method of alternately introducing the raw material methane and hydrogen into the reactor is not only complicated, but it seems to be effective in extending the catalyst life, but it was reacted with methane for a short time. Immediately after that, there is only a regeneration step for removing carbon produced on the catalyst with hydrogen, and the regeneration step is less than the amount of aromatics produced per hour and the amount of hydrogen gas produced in the target reaction. Because it consumes a lot of hydrogen, it is hard to say that it is a practical method.
[0007]
The present invention has been made to solve the problems such as the deterioration of the catalyst performance by the conventional method as described above, the incorporation of carbon monoxide into the product gas, and the consumption of hydrogen of the product. In addition, it is possible to suppress degradation of catalyst performance due to carbon deposition, and a lower hydrocarbon comprising methane or a methane-containing lower hydrocarbon aromatization catalytic reaction method and aromatic that can be applied to a large-scale actual plant. It is an object of the present invention to provide a chemical catalyst reaction apparatus and a method for producing an aromatic compound and hydrogen.
[0008]
[Means for Solving the Problems]
The conventional method of adding CO ₂ or the like to the raw material gas or the method of alternately introducing hydrogen is a method of removing carbon as a gaseous substance from the catalyst surface by oxidizing carbon generated by a thermal decomposition reaction of methane. However, when CO ₂ or the like is added, it is difficult to control the reaction, and carbon monoxide is contained in the product gas. Further, the method of frequently regenerating by alternately introducing hydrogen is not practical because it consumes a large amount of hydrogen, and the reaction efficiency for producing aromatic compounds and hydrogen is greatly reduced. On the other hand, the inventors have prepared a reaction for producing the target aromatic and hydrogen; a thermal decomposition reaction of 6CH ₄ → C ₆ H ₆ + 9H ₂ and methane; and hydrogen as a product of CH ₄ → C + 2H ₂ The present invention has been completed by paying attention to the reaction with the carbon generated on the catalyst surface by the reverse reaction of methane pyrolysis, even during the target reaction.
[0009]
That is, among the lower hydrocarbon aromatization catalytic reaction methods of the present invention, the invention according to claim 1 is a lower carbonization comprising methane using a catalyst in which a metal element or a metal element compound is supported on a porous metallosilicate. in the catalytic reaction method of co-producing directly an aromatic hydrogen from a lower hydrocarbon gas containing hydrogen or methane, said raw lower hydrocarbon gas to the hydrogen added 1 to 20 vol% is subjected to the catalytic reaction Features.
[0010]
The invention of the lower hydrocarbon aromatization catalytic reaction method according to claim 2 is the invention according to claim 2, wherein a part or all of the hydrogen is produced by a catalytic reaction of the lower hydrocarbon gas. It is characterized by being.
[0011]
The invention of the lower hydrocarbon aromatization catalytic reaction method according to claim 3 is the invention according to claim 2, wherein hydrogen is separated from the gas that has undergone the catalytic reaction of the lower hydrocarbon gas, and the hydrogen is used as a raw material hydrocarbon. It is characterized by adding to gas.
[0012]
The invention of a lower hydrocarbon aromatization catalytic reaction method according to claim 4 is characterized in that, in the invention of claim 3, the hydrogen remains in the unreacted lower hydrocarbon gas.
[0013]
The invention of the lower hydrocarbon aromatization catalytic reaction method according to claim 5 is the catalytic reaction method according to any one of claims 1 to 4, wherein the metal element or the metal element compound is molybdenum, rhenium, tungsten, It is characterized by being a metal selected from zinc, gallium, iron, copper and cobalt, a compound thereof or a mixture thereof .
The invention of claim 6 aromatics and method for producing hydrogen as claimed is Oite the catalytic reaction method according to any one of claims 1 to 5 to obtain an aromatic compound and hydrogen from said lower hydrocarbon gas Features.
[0014]
The aromatization catalytic reactor according to claim 7 has a raw material lower hydrocarbon gas introduction part and a gas discharge part into which a lower hydrocarbon composed of methane or a lower hydrocarbon containing methane is introduced, and is porous inside A catalytic reaction vessel containing a metal element or metal element compound-supported catalyst on a metallosilicate; a product separation means connected to the discharge part and capable of separating hydrogen from the exhaust gas; and the product separation means The raw material lower hydrocarbon to introduce hydrogen or the lower hydrocarbon gas containing 1 to 20% by volume of hydrogen separated into the catalyst reaction vessel A gas reflux path for mixing with the gas is provided.
An aromatization catalytic reaction apparatus according to claim 8 is the invention according to claim 7, wherein the metal element or metal element compound is a metal selected from molybdenum, rhenium, tungsten, zinc, gallium, iron, copper and cobalt. Or a compound thereof or a mixture thereof .
[0015]
That is, according to the present invention, by adding an appropriate amount of hydrogen gas to the raw material methane gas in advance, there is an effect of hindering the progress of the target catalytic reaction, but it does not significantly reduce the reaction rate, There is an effect of suppressing the coating of the catalyst surface with the produced carbon which causes a decrease in the catalytic activity.
[0016]
Further, when the action is specifically observed, for example, when the product hydrogen is mixed in the raw material methane, the target reaction represented by the reaction formula; 6CH ₄ → C ₆ H ₆ + 9H ₂ is Since the equilibrium shifts to the left side due to the presence, the progress of the reaction is suppressed. On the other hand, the progress of an undesirable reaction that causes catalyst performance deterioration; CH ₄ → C + 2H ₂ can also be suppressed. In equilibrium, the time required for catalyst degradation can be extended by suppressing the progress of both reactions, that is, by allowing the reactions to proceed slowly. On the other hand, when an actual catalytic reaction tower is considered, the raw material gas is introduced from the negative side of the layer packed with the catalyst, and the reacted gas is discharged from the other outlet. For this reason, in the initial stage of the reaction, the reaction proceeds actively in the vicinity of the gas inlet, and the catalyst is deteriorated as time passes, and the active reaction zone gradually moves toward the outlet. When only methane gas is used as a raw material, the catalyst deteriorated by carbon deposition remains as it is, but when hydrogen-added methane gas is used, the hydrogen reacts with the deposited carbon to form methane gas. Thus, it is possible to remove carbon from the catalyst surface and extract the catalytic activity again. The gas that has become methane in this region can cause the target reaction together with the raw material methane at the later stage of the more active catalyst layer, so the overall reaction rate of the catalyst reaction tower is greatly reduced. Without this, the catalyst life can be greatly extended. For this reason, the catalytic reaction efficiency is improved as a whole, and the reaction efficiency is stable over a long period of time.
[0017]
Compared to the conventional method of adding CO ₂ or the like, this method is less dependent on the addition amount of the reaction rate, so it is not necessary to set the addition amount strictly. There is also an effect that can be easily performed. Further, the operation is simpler than the conventional method of alternately introducing the raw material methane and hydrogen, and the amount of depletion of hydrogen is small, which is a more economical method for improving the catalyst life. Further, generally, when the reaction does not proceed 100% in the catalytic reaction, a circulation type reaction apparatus is used in which the product is removed from the obtained reaction gas and the unreacted raw material gas is returned to the reaction tower again. In the catalytic reaction for producing aromatics and hydrogen, a method is used in which aromatics and hydrogen as products are separated from the reaction tower outlet gas, and the remaining unreacted methane is recycled as a raw material gas to the reaction tower again. . Considering this separation of reactive organisms, aromatics such as benzene and naphthalene have low boiling points, so they can be easily separated and removed by cooling, but a large-scale apparatus is needed to completely separate methane and hydrogen. Will be required, which will increase the cost of plant construction and operation. However, according to the present invention, since hydrogen is added to the raw material methane for the purpose of improving the catalyst life, it is not necessary to completely separate methane and hydrogen in the reaction gas, and a simple PSA (Pressure Swing) can be used. There is an effect that hydrogen can be added to the raw material methane by circulating the methane rich gas containing hydrogen using Adsorption) or the like. For this reason, by adding a part of the generated hydrogen gas, it is not necessary to prepare an additional gas separately, and there is an effect that the apparatus cost and the operation cost can be reduced by suppressing the degree of separation of the gas after the reaction. .
[0018]
In the present invention, porous metallosilicate is used as a catalyst carrier. As the porous metallosilicate, it is possible to use a porous carrier made of silica and alumina having various compositions, a porous carrier mainly composed of phosphoric acid, and a titanosilicate composed of silica and titania. it can. The porous metallosilicate has micropores and mesopores, and is substantially exemplified by a diameter of 4.5 to 5.5 mm.
[0019]
The porous silicate carries a metal element or a metal element compound as a catalyst material. Examples of the catalyst material include metals such as molybdenum, rhenium, tungsten, zinc, gallium, iron, copper and cobalt, or compounds thereof, and may be a mixture thereof.
In the present invention, the amount of the catalyst material supported on the metallosilicate is not particularly limited, and an appropriate amount may be selected according to the type of the catalyst material.
[0020]
Examples of the method of supporting the catalyst material on the metallosilicate include a method of impregnating and supporting a precursor of the catalyst material or the like on the metallosilicate or by an ion conversion method. However, in the present invention, the method for supporting the catalyst material is not particularly limited.
[0021]
The catalyst of the present invention obtained as described above may be in the form of powder, pellets, or other shapes, and the shape is not particularly limited. The catalyst is usually accommodated in a catalytic reaction vessel and brought into contact with a lower hydrocarbon composed of methane or a lower hydrocarbon gas containing methane for the catalytic reaction. The above action can be obtained by subjecting methane to be reacted with the catalyst or raw material lower hydrocarbon containing methane to a catalytic reaction by mixing with an appropriate amount of hydrogen. In addition, as the hydrogen added to the raw material lower hydrocarbon containing methane or methane, it is possible to preferably use hydrogen produced by the target catalytic reaction. In this case, hydrogen other than the above product can be used, and hydrogen in the product and other hydrogen can be mixed and added. Furthermore, hydrogen is always continuously may be mixed in the raw material lower hydrocarbon containing methane or methane and subjected to catalytic reaction, intermittently added to the raw material lower hydrocarbon containing methane or methane catalysis You may make it use for.
When hydrogen is added to methane or a raw material lower hydrocarbon containing methane , the addition amount is in the range of 1 to 20% by volume. If it is less than 1% by volume, the effect of suppressing the coating of the catalyst surface with the produced carbon that causes a decrease in the catalyst activity cannot be obtained sufficiently, and the deterioration of the catalyst performance over time cannot be sufficiently suppressed. On the other hand, if the amount of hydrogen added exceeds 20% by volume, the effect of hindering the progress of the target catalytic reaction becomes strong, and sufficient reaction efficiency cannot be obtained. Therefore, the amount of hydrogen added is limited to the above range. For the same reason as described above, it is desirable that the lower limit is 5% by volume and the upper limit is 15% by volume.
[0022]
As the lower hydrocarbon to be used for the catalytic reaction, methane having 1 carbon is typically shown, but other hydrocarbons having 1 to 5 carbon can be used as the reaction target.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the aromatization catalyst reaction apparatus in the present invention will be described with reference to FIG.
The catalyst reaction vessel 10 contains a catalyst 20 in which a predetermined catalyst material is supported on a porous metallosilicate. The catalyst reaction vessel 10 contains a lower hydrocarbon composed of methane or a lower hydrocarbon containing methane. A gas introduction part 11 and a gas discharge part 12 to be introduced are provided. The gas discharge part 12 is provided with a separation means 29 for separating the produced aromatic compound and a gas discharge part 28 for discharging the gas therefrom, and the gas discharge part 28 uses PSA (pressure fluctuation adsorption). A product separation means 30 is connected to the product separation means 30, and a reactant delivery path 31 for sending hydrogen and a reflux pipe 40 for sending unreacted raw material hydrocarbons containing hydrogen are connected to the product separation means 30. ing. The reflux pipe 40 is connected to the gas introduction unit 11 via a flow rate control valve 41, and can supply hydrogen and unreacted raw material hydrocarbons to the gas introduction unit 11.
[0024]
Next, a method of aromatizing catalytic reaction of methane or lower hydrocarbons containing methane using the aromatizing catalytic reactor will be described. Methane or raw material lower hydrocarbon containing methane is introduced into the catalytic reaction vessel 10 through the gas introduction unit 11 and brought into contact with the catalyst 20 to cause a catalytic reaction. By this reaction, methane or a lower hydrocarbon containing methane generates an aromatic compound and hydrogen, and these products are discharged from the gas discharge section 12 through the catalytic reaction vessel 10 and reach the aromatic separation means 29. In the aromatic separation means 29, the aromatic compound is taken out through the reactant delivery path 27. The product gas separated from the aromatic compound by the aromatic separation means 29 passes through the gas discharge unit 28 and reaches the product separation means 30. On the other hand, in the product separation means 30, hydrogen gas is sent to the reactant delivery path 31, and unreacted lower hydrocarbon and a part of hydrogen are sent to the reflux path 40. In the reflux path 40, the flow rate is controlled by the flow rate control valve 41, and hydrogen is mixed into the gas introduced into the catalytic reaction vessel 10 through the gas introduction unit 11 at a rate of 1 to 20% by volume.
[0025]
In the catalytic reaction vessel 10, the target aromatic compound and hydrogen are produced by the catalytic reaction, and some lower hydrocarbons generate carbon and adhere to the catalyst surface along with the reaction. There is a phenomenon. However, if hydrogen is mixed in the raw material gas, the reaction of generating carbon is suppressed, and the action of reducing the carbon generated by the above reaction and removing it from the catalyst surface in the form of hydrocarbon is obtained. The deterioration of the catalyst with time is suppressed. In addition, although the reaction in which an aromatic compound and hydrogen are produced due to the mixing of hydrogen is suppressed, the reaction efficiency is improved as a whole by the action of suppressing catalyst deterioration.
[0026]
【Example】
Examples of the present invention will be described below in comparison with comparative examples.
(Catalyst preparation and experimental conditions)
Honeycomb type ZSM-5 (pore diameter 5.4 to 5.6 mm), which was baked at 450 ° C. for 5 hours to remove water, was immersed in an ammonium molybdate aqueous solution to carry Mo, weighed, and then vacuum dried. A catalyst was prepared by calcination at 500 ° C. for 5 hours. 10 g of this 6 wt% Mo / HZSM-5 catalyst was put into a SUS reaction tube having an inner diameter of 20 mm and a height of 130 mm, carbonized at 650 ° C. for 30 minutes, 750 ° C., 3 atm, methane SV = 2520 ml MFl / g / h. The reaction was started.
[0027]
Example 1
In the above experiment, a catalytic reaction was carried out for 10 hours using a mixed gas obtained by adding 3.6% by volume of hydrogen to methane as a reaction raw material gas. Under the present circumstances, the production | generation rate of benzene which is the main aromatic to produce | generate was measured by analyzing the gas of the reaction tube exit.
[0028]
(Example 2)
In the same experiment as in Example 1, a catalytic reaction was performed for 10 hours using a mixed gas obtained by adding 6% by volume of hydrogen to methane as a reaction raw material gas. Under the present circumstances, the production | generation rate of benzene which is the main aromatic to produce | generate was measured by analyzing the gas of the reaction tube exit.
[0029]
(Comparative Example 1)
In the same experiment as in Example 1, a catalytic reaction was performed for 10 hours using pure methane to which hydrogen was not added as a raw material gas. Under the present circumstances, the production | generation rate of benzene which is the main aromatic to produce | generate was measured by analyzing the gas of the reaction tube exit.
[0030]
Based on the test results of Example 1, Example 2, and Comparative Example 1, changes over time in the production rate of benzene, which is an index indicating the reaction activity of the catalyst, are shown together in FIG. By adding hydrogen to the raw material methane, the maximum reaction rate is reduced by about 20% in the case of Example 2, but the performance is stably exhibited for a long time, and the benzene production rate after 10 hours is a comparative example. In Example 2, the benzene production rate after 10 hours was able to maintain 90% of the maximum value, compared with 25% of the maximum value.
[0031]
【The invention's effect】
As described above, according to the present invention, aromatics and hydrogen are produced from a lower hydrocarbon comprising methane or a lower hydrocarbon gas containing methane using a catalyst in which a metal element or a metal element compound is supported on a porous metallosilicate. In the catalytic reaction method for directly co-producing hydrogen, 1 to 20% by volume of hydrogen is added to the raw material lower hydrocarbon comprising methane or the raw material lower hydrocarbon gas containing methane, and used for the catalytic reaction. The carbon produced as a side reaction in the catalytic reaction to produce the catalyst can be removed from the surface of the catalyst, the catalyst life can be improved without greatly reducing the reaction rate, and aromatic compounds and hydrogen can be efficiently removed. Can be manufactured.
In addition, according to the aromatization catalyst reaction apparatus of the present invention, the above-described action can be easily and reliably realized.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an aromatization catalytic reactor according to an embodiment of the present invention.
FIG. 2 is a graph showing test results (change in benzene production rate over time) in Examples of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Catalytic reaction container 11 Gas introduction part 12 Gas discharge part 20 Catalyst 27 Reactant delivery path 28 Gas discharge part 29 Aromatic separation means 30 Product separation means 31 Reactant delivery path 40 Reflux pipe 41 Flow control valve

Claims (8)

In the catalytic reaction method of co-producing an aromatic hydrogen directly from a lower hydrocarbon gas on a porous metallosilicate containing lower hydrocarbons or methane consists of methane using a catalyst carrying a metal element or a metal element compound, wherein A lower hydrocarbon aromatization catalytic reaction method, wherein 1 to 20% by volume of hydrogen is added to a raw material lower hydrocarbon gas and used for the catalytic reaction. 2. The lower hydrocarbon aromatization catalytic reaction method according to claim 1, wherein a part or all of the hydrogen is produced by a catalytic reaction of the lower hydrocarbon gas. 3. The method for aromatizing catalytic reaction of a lower hydrocarbon according to claim 2, wherein hydrogen is separated from the gas that has undergone the catalytic reaction of the lower hydrocarbon gas, and the hydrogen is added to the raw material lower hydrocarbon gas. 4. The method for catalytic aromatization of lower hydrocarbons according to claim 3, wherein the hydrogen remains in the unreacted lower hydrocarbon gas. The metal element or metal element compound is a metal selected from molybdenum, rhenium, tungsten, zinc, gallium, iron, copper, and cobalt, a compound thereof, or a mixture thereof. A process for aromatizing catalytic reaction of a lower hydrocarbon according to claim 1 . Aromatics and method for producing hydrogen, characterized in that to obtain the aromatic compound and hydrogen from said lower hydrocarbon gases by catalytic reaction method of any of claims 1-5. It has a raw material lower hydrocarbon gas introduction part and a gas discharge part into which a lower hydrocarbon comprising methane or a lower hydrocarbon containing methane is introduced, and carries a metal element or metal element compound on a porous metallosilicate inside A catalyst reaction vessel containing the catalyst, a product separation means connected to the discharge section and capable of separating hydrogen from the exhaust gas, hydrogen separated from the product separation means or hydrogen and unreacted lower carbonization A gas recirculation path for mixing hydrogen gas with the raw material lower hydrocarbon gas so as to introduce the lower hydrocarbon gas containing 1 to 20% by volume of hydrogen into the catalytic reaction vessel by sending hydrogen gas to the gas introduction section. An aromatization catalytic reactor. 8. The aromatic according to claim 7, wherein the metal element or metal element compound is a metal selected from molybdenum, rhenium, tungsten, zinc, gallium, iron, copper, and cobalt, a compound thereof, or a mixture thereof. Catalyst reactor.

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