JPH02212437A - Method for reacting methane - Google Patents

Abstract

PURPOSE:To simultaneously produce effective hydrocarbons and steam reforming gas while effectively utilizing reaction heat and by-product CO2 by carrying out oxidative coupling and steam reforming of methane in the same reaction apparatus. CONSTITUTION:Oxidative coupling using methane or a methane-containing gas and oxygen-containing gas as raw materials and steam reforming using the methane-containing gas and steam-containing gas as raw materials are carried out in the same reaction apparatus utilizing the reaction heat of the former for the latter reaction to afford a mixed gas of >=2C hydrocarbons, CO and H2. A multitubular type reactor (e.g. internal heat exchange type reactor, such as shell and tube reactor) is preferably used as the apparatus from the viewpoint of facilitated separation of products, manifestation of catalyst activity, etc. The reaction is carried out at 500-1000 deg.C and 30-400000/hr space velocity under 0.1-100kg/cm<2> pressure.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for reacting methane, and more specifically,
Steam reforming gas (C
The present invention relates to a novel methane reaction method that can simultaneously and effectively produce a mixed gas containing O and Ht as main components) and useful hydrocarbons having 2 or more carbon atoms such as ethylene and ethane.

[Conventional technology]

A reaction method in which an exothermic reaction and an endothermic reaction are combined in the same reactor and the positive and negative reaction heats are compensated for each other to effectively utilize the reaction heat is disclosed in Japanese Patent Application Laid-Open No. 63-1290.
This reaction method is known from Japanese Patent Application No. 02, etc., but in order to make this reaction method practically effective, it is important to decide what kind of reactions to combine.

However, there is no known example of such a reaction method limited to a combination of methane oxidative coupling reaction and steam reforming.

By the way, this oxidative coupling reaction of methane is a method for producing hydrocarbons having two or more carbon atoms, such as ethylene and ethane, from methane or a methane-containing gas such as natural gas in the presence of oxygen. As L i /
Method using M g O [Journal of Catalysis Society 27.6. P
199 (1985) ], Mn, Sn, Pb,
Sb.

Method using B15Tl, Cd, etc. (J, Catal
ysis+ 73°949-1982), 5tatu
s, Lutes, etc. (CheIl,
Letters, (4), 499. 1985
), a method using Pb/AlzO1 (West German Patent Publication No. 323079), a method using a catalyst containing an alkali metal and a first transition series element (JP-A-62-23
8220) and a method using a catalyst containing one or more metal elements selected from calcium, barium, and strontium (Japanese Patent Application Laid-Open No. 62-267243). However, this reaction is exothermic and generates a relatively large amount of CO□ as a by-product due to complete combustion, so it generates a large amount of heat and requires a special reaction device and cooling mechanism to recover the reaction heat. There are problems such as a large loss of carbon source due to the by-product of carbon dioxide, which increases manufacturing costs.

On the other hand, methane steam reforming is intended to produce a mixed gas of hydrogen and carbon monoxide, which is useful as a raw material for various chemical syntheses, through the reaction of methane and water vapor. Methods using various catalysts containing transition metals such as nickel and cobalt, including catalysts based on nickel and cobalt, are known.

However, in this method, the main reaction is the following [
1] Formula % Formula % (1) is an endothermic reaction that requires the supply of a large amount of heat, and the molar ratio of H2 and CO in the resulting product gas (CO/l is usually 1 from the above formula (1). The value is around /3, so when used as a raw material for producing methanol or mixed alcohol, the reaction formula is (GO+2)1z→CH30H;
mcO+2ml□→ COHzs. +OH+ (m-
1) HzO), so its molar ratio (CO/l1z
), it is necessary to adjust the composition so that it is about 1/2 of the public opinion ratio. In addition, as a method of supplying the heat, a method is sometimes adopted in which oxygen is supplied to the reaction system to completely burn a considerable portion of methane, and the heat of reaction is used to supplement the amount of heat supplied. Since the product is CO2 from complete combustion, problems such as increased loss of carbon sources occur.

That is, when the oxidative coupling reaction and the steam reforming are performed separately in separate reaction apparatuses, the above-mentioned problems arise.

[Problem to be solved by the invention]

The present invention has been made in view of the above circumstances.

An object of the present invention is to solve the above-mentioned problems and effectively utilize the reaction heat in a manner that supplements the heat generated in the oxidative coupling with the heat absorbed in the steam reforming, while It is possible to efficiently produce a steam reforming product gas (mixed gas of CO and H! or a mixed gas containing CO and H! as the main components) which is useful as a raw material for synthesis of useful hydrocarbons and various compounds. CO as a by-product in the oxidative coupling of
! and a part of H2 generated by the steam reforming are converted into useful CO using the reaction expressed by the following [2] formula % formula % (2) to suppress the loss of carbon source and , it is possible to adjust the molar ratio (CO/L) in the steam reforming gas to be close to 1/2, which is the stoichiometric ratio suitable as a raw material for methanol, mixed alcohol, etc., which is a novel technology that is extremely advantageous in practical terms. The purpose of the present invention is to provide a method for reacting methane.

[Means to solve the problem]

As a result of extensive research, the present inventors have discovered that methane oxidative coupling and steam reforming are carried out in the same reactor by supplying the reaction heat in the oxidative coupling to the steam reforming system. We have discovered that by using a reaction method that combines specific reactions, the above-mentioned problems in each reaction can be effectively solved and the above-mentioned object can be easily achieved, and based on this knowledge, we have completed the present invention. Ta.

That is, the present invention provides a methane reaction method characterized by performing methane oxidative coupling and steam reforming in the same reaction apparatus.

In the present invention, the oxidative coupling of the methane is carried out in the presence of a suitable catalyst using at least a methane-containing gas and an oxygen-containing gas as feed reaction materials, while the steam reforming of the methane is carried out in the presence of a suitable catalyst. is carried out using at least a methane-containing gas and a water vapor-containing gas as feed reaction raw materials, and the oxidative coupling and the steam reforming are carried out in such a way that the reaction heat of the former, which is an exothermic reaction, is used for the latter, which is an endothermic reaction. It is carried out in the same reactor to produce a mixed gas of a hydrocarbon having 2 or more carbon atoms such as ethylene or ethane, CO, and H7, or a mixed gas containing the same as the main component.

In the present invention, the oxidative coupling and steam reforming may be carried out in separate reactors, or may be carried out in separate reaction zones within the same reactor, as long as they are carried out in the above-mentioned manner. Among these various reaction methods, the methane-containing gas, the oxygen-containing gas, and the water vapor-containing gas may be mixed simultaneously or in stages in the same reactor. ,
For example, a multi-tubular reaction such as a concentric or similar double-tube reactor is used because it is easy to separate the products and the performance of the catalyst used in each of the above reactions can be fully demonstrated. It is preferable to carry out each of the above reactions in separate reaction zones using a reactor or multi-tubular reactor. A system in which each of the reactions described above is performed in separate reaction regions using a multitubular reactor such as a tubular reactor can be suitably employed.

Specifically, an internal heat exchange type reactor such as a shell and tube reactor is used.

Examples of the methane-containing gas include pure methane, natural gas, petroleum-based methane-containing gas, coal-based methane-containing gas, digestion gas-based methane-containing gas, methane-containing gas obtained by other methanation reactions, and recovered methane-containing gas. A mixed gas containing methane as a main component can be used. Among these, natural gas and the like are particularly preferably used.

As the oxygen-containing gas, a gas containing oxygen such as pure oxygen or air can be used.

As the water vapor-containing gas, water vapor or a mixed gas containing water vapor can be used.

In the present invention, the reaction may be carried out by diluting with an inert gas such as nitrogen, helium, or argon, if necessary, and other substances other than the above may be used within the range that does not interfere with the purpose of the present invention. Other components may also be included. Specifically, for example, the oxidative coupling can be carried out by adding, for example, a halogen-containing compound such as halogenated methane, hydrogen halide, or halogen to the reaction raw material,
In addition, in the steam reforming, CO is added to the reaction raw material.
It can also be carried out by appropriately adding or containing 1. By carrying out the reaction by including COz in this manner, it is also possible to appropriately adjust the CO/H2 ratio in the steam reforming gas. Note that when the reaction is carried out by adding COt, CO□, which is a by-product of the oxidative coupling, can be effectively used as the COt.

In the present invention, the molar ratio (island/C
Ha), which is usually within the range of about 0.01 to 10. .

In the present invention, the ratio of methane and steam to be supplied when performing the steam reforming is preferably within the range of about 1 to 10, preferably about 2 to 7, in terms of molar ratio (HtO/CH4). Appropriate.

In the present invention, the catalyst used for the oxidative coupling is not particularly limited as long as it is effective for the oxidative coupling, and various known catalysts can be appropriately selected and used. Among these, known catalysts include, for example, the above-mentioned document [Journal of Catalysis Society, revised edition, 6. P199
(1985)), i.e., Li/MgO
et al. (J, Catalysis, 73.
9-19.1982), that is, Mn5
Catalysts containing one or more of Sn, Pb, Sb, Bi, TI, Cd, etc., as described in the above literature (Ches,
Letters, (4), 499.1985), i.e., 511203. Catalysts described in JP-A-61-165340, such as Lu2O3, ie,
A catalyst containing at least one of rare earth elements such as scandium, yttrium, lanthanum, neodymium, samarium, europium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, especially an oxide of the rare earth element. A supported oxide catalyst supported on a support such as a single oxide catalyst or a composite oxide catalyst containing at least one of these, or an oxide support such as silica, alumina, magnesia, titania, or zirconia, or further calcium oxide. , various catalysts added with alkali metal and/or alkaline earth metal oxides such as magnesium oxide, sodium oxide, potassium oxide, etc.
Al□0. Catalysts described in JP-A-62-238220, such as lithium, sodium, potassium,
Catalysts containing one or more alkali metals such as rubidium and cesium and one or more first transition series elements such as titanium, manganese, cobalt, and nickel, especially halides of these alkali metals, and carbonic acid. Catalysts consisting of one or more salts, nitrates, hydroxides, etc., especially lithium chloride, lithium nitrate, lithium carbonate, etc., and one or more oxides of the first transition series elements, etc. The catalyst described in Publication No. 62-267243, that is,
Catalysts containing one or more metal elements selected from calcium, barium, and strontium, especially catalysts containing at least one of oxides and carbonates of these metal elements, or lithium, sodium, potassium, rubidium, etc. Examples include various catalysts to which alkali metals are added.

In addition, these catalysts can also be used in combination of two or more types as required.

In the present invention, the catalyst used for the steam reforming is not particularly limited as long as it can be effectively used for the steam reforming, and various catalysts such as known catalysts can be used. Specifically, commercially available catalysts based on nickel-alumina such as G-56HI catalyst manufactured by Girdler, ICl37-3 catalyst manufactured by IC1, and RKS-1 catalyst manufactured by Tobso are preferably used. be able to.

The reaction conditions for the oxidative coupling and steam reforming cannot be specified as they vary depending on other conditions such as the type of catalyst used and the composition of the reaction gas, but the reaction temperature is usually 500 to 1000. ℃, and the space velocity (GH3V) is usually 30 to 400.
．． It is appropriate to set it within the range of OO0hr-'.

If the reaction temperature is less than 500°C, the reaction rate may be insufficient, and if it exceeds 1000°C, catalyst deterioration may increase.0Reaction pressure may be under reduced pressure, normal pressure, or elevated pressure. Possible, but usually 0.1-100kg/
It is preferable to set it within a range of approximately ciiG.

In the present invention, one of the important points is that the oxidative coupling and the steam reforming are performed in a reactor in such a way that the reaction heat of the oxidative coupling is used as the amount of heat supplied to the steam reforming, as described above. It is a point. It is known that in the above-mentioned oxidative coupling, in addition to producing hydrocarbons having two or more carbon atoms such as ethylene and ethane, a by-product of CO is produced by complete oxidation of methane. Considering these points, the heat balance between oxidation coupling and steam reforming is set to 0 to 0 below.
The basic reaction represented by the formula % is considered as follows.

In other words, Figure 1 shows the heat balance at an absolute temperature of 1000°K for the three reactions represented by equations 0 to 0 above, and shows the conversion rate of methane in the methane oxidation reaction (■ and ■ above). 2 as parameters, the conversion rate of methane X in steam reforming (■ above) and the selectivity to ethylene in the oxidation reaction of methane (■ and ■) y (
It is a graph showing the relationship between ■ and the proportion of ■ in the reactions of ■ expressed as a percentage. From Figure 1, for example, if the conversion rate of methane in the oxidation reaction of methane is z = 40% and the selectivity to ethylene is y = 50%, the heat value of this reaction is used to steam reform the methane. If (■) is performed, the amount of heat equivalent to X-83% can be provided. However, the equilibrium conversion rate of steam reforming (■) of methane at an absolute temperature of 1000'K and a pressure of 1 atm is 81.4%, so if the reaction heat is fully utilized as described above, the reaction This means that the equilibrium conversion rate will be reached by heat alone.

By the way, in steam reforming of methane, CO/L (molar ratio) is 1/3 or 1/3 from the above formula 0.
Products with similar compositions are obtained. Therefore, when attempting to synthesize methanol or mixed alcohol from the steam reforming product gas with this composition, the reaction formula for these synthesis reactions is (CO+2Hffi4C■sOH;
sco + 2■H3→C,Hz--+OH+ (
II+-1)HzO), the raw material molar ratio (CO
/Hz) to 1/2 or around 1/2 of the stoichiometric ratio, for example, by using the reaction expressed by the following formula [2].

At that time, in the conventional method, this CO! However, in the present invention, COt produced as a by-product during the oxidative coupling of methane can be effectively utilized.

As described above, according to the present invention, ethylene, ethylene,
It is possible to advantageously produce a mixed gas of CO and H2, or a mixed gas containing the same, which is useful as a raw material for synthesis of various compounds such as useful hydrocarbons having two or more carbon atoms such as ethane, methanol, and mixed alcohols. .

〔Example〕

Example 1 A predetermined amount of manganese oxide powder was added to a lithium chloride aqueous solution, evaporated to dryness, dried at 120°C, and then calcined in air at 700°C for 3 hours to obtain 20 mol% lithium chloride. A catalyst containing the following was prepared.

1 g of this catalyst was packed inside a double reaction tube made of quartz glass, and the outside was filled with steam reforming catalyst G-56H.
1 (manufactured by Gertler) Ig was filled.

Next, while heating this reaction tube to 750"C in an electric furnace, a mixed gas of methane, oxygen, and helium was supplied to the inside of the double reaction tube. Methane partial pressure was 0.05 a [m, oxygen partial pressure was 0.025atm and total pressure of 1atm, and this mixed gas was supplied at a rate of 100Nate/main.Methane partial pressure of 0.1atm was supplied to the outside of the double reaction tube.
m, steam partial pressure 0.6aLrn.

100Nd/gas mixed so that the total pressure is 1atm
The reaction was carried out by supplying at a sin ratio. After 2 hours, the gas inside and outside the double tube was analyzed by gas chromatography. The results are shown below.

Inside (oxidative coupling of methane) Conversion rate: (CH4) 44.8% Selectivity = (ethylene) 55% (ethane) 5.8% (COz) 38.5% (Co) 0.7% Outside (methane) steam reforming) conversion rate 1 cH
4) 99% Selectivity: (o2) 77% (CO) 13% (C(h) 10% [Effects of the Invention] According to the present invention, methane oxidation capping and steam reforming are performed in the same reactor, so While effectively utilizing the reaction heat from methane or methane-containing gas such as natural gas, CO
While making effective use of carbon atoms such as ethylene and ethane,
The above useful hydrocarbons and CO and H2, which are useful as raw materials for the synthesis of various compounds such as methanol and mixed alcohols.
It is possible to provide a novel methane reaction method that can advantageously produce a mixed gas containing the same or a mixed gas containing the same.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the heat balance of the reaction according to the reaction method of the present invention. The numerical value (parameter 2) shown for each straight line in the figure represents the conversion rate (%) of methane in the methane oxidation reaction,
The horizontal axis (X) represents the conversion rate (%) of methane in steam reforming, and the vertical axis (y) represents the selectivity to ethylene in the oxidation reaction of methane.

Claims (1)

[Claims] 1. A methane reaction method characterized by performing methane oxidative coupling and steam reforming in the same reaction apparatus.