JPH0446130A - Production of ethane and ethylene by partial oxidation of methane - Google Patents

Abstract

PURPOSE:To efficiently obtain ethane and ethylene by partially oxidizing methane or natural gas containing the methane with O2 or an O2-containing gas by using a compound metallic oxide composed of two kinds of metals supporting an alkali metallic halide. CONSTITUTION:Methane or natural gas containing the methane is partially oxidized with oxygen or an oxygen-containing gas at 600-1,000 deg.C in the presence of a catalyst of an alkali metallic halide supported on a compound metallic oxide (especially perovskite type or ilmenite type compound metallic oxide is preferred) composed of two kinds of metals to afford ethane or ethylene. The yield of 2C compounds in oxidative coupling reaction of the methane is high according to the aforementioned method and the industrial value thereof is great.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides ethane,
The present invention relates to a method for producing ethylene.

[Prior art] Methane is a resource that exists in abundance around the world as the main component of natural gas, but due to its low reactivity, most of it is consumed as fuel, and it is difficult to produce useful substances. There are limited ways to use it as a raw material.

However, in 1982, Mr. Keller and Mr. Bergin reported in the Journal on Catalysis, published in the United States, that ethane and ethylene were produced when methane was partially oxidized in the presence of oxygen using various metal oxides as catalysts. ,
Since the report was published in Volume 73, pages 9-19, researchers around the world have focused on this reaction, which is called the oxidative camping reaction of methane, and many catalysts have been reported so far.

For example, Chemistry Letters, published by the Chemical Society of Japan in 1987, pages 483-484, states that lanthanide metal oxides, especially samarium oxide, are catalysts with excellent selectivity for ethane and ethylene in this reaction. It has been reported. However, the C2 yield is about 12 to 13%, which is still insufficient for industrialization. Furthermore, since the catalyst mainly uses rare earth elements, there is a drawback that the cost of raw materials is high.

Furthermore, according to JP-A No. 61-225141, alkaline and alkaline earth elements mb of the periodic table are used as catalysts.
It has been stated that when the chlorides, bromides and iodides of group elements, elements with atomic numbers 24-300, lanthanide elements, silver, cadmium, lead and bismuth are used alone or in mixtures, methane is converted to ethane/ethylene. There is. In this method, it is said that when these metal halides are used alone, a reduction in conversion rate frequently occurs, and therefore it is advantageous to use them preferably on a carrier such as pumice. It is stated that it is advantageous for the halide catalyst to be molten at the working temperature in order to obtain the desired yield (see Publication Box 3, bottom left column, line 10 to bottom left column, line 16).

However, even under these favorable conditions, the conversion of methane is low, below 20%, and therefore the 02 yield is at most 1
It is around 2%, which is not recognized as sufficient for industrialization. Furthermore, in order to increase the conversion rate, the reaction temperature is raised above the melting temperature of the halide, but as a result, halides and halogens are found in the effluent gas mixture, accompanied by deactivation of the catalyst. In order to prevent this, there is a disadvantage that continuous recirculation of the catalyst is required. Furthermore, although the same specification describes the use of a catalyst to which an alkali metal halide is added, there is no mention of specific means or that the addition of these increases the yield.
Such a fact is not recognized in the examples as well.

Further, according to JP-A No. 61-282323, cobalt; at least one metal selected from the group consisting of zirconium, zinc, niobium, indium, lead, and bismuth; phosphorus; at least one Group 1A metal; oxygen and It has been described that methane can be converted to ethane and ethylene, optionally using a catalyst consisting of a substance selected from the group consisting of halogens and sulfur, but this process is difficult despite the complexity of the catalyst system. According to the results of the examples, the C2 yield is as low as about 10%, which is still not recognized as being sufficient for industrialization. Additionally, this publication states that when a halogen, preferably chlorine, is added to the catalyst, the conversion rate of methane and the selectivity to higher hydrocarbons, particularly ethylene and ethane, are substantially improved (No. (See lines 3 to 6 of the 3rd column, lower left column, and lines 5 to 8 of the 4th negative upper left column), but no comparative examples are listed, so it is not possible to gauge the extent of the substantial improvement. .

Furthermore, according to the Chemical Society of Japan, published in 1988, Chemistry Letters, page 237, two types of metal A
, B is incorporated into the crystal lattice, and perovskide (
It has been reported that some perovskite) type oxides have catalytic activity in oxidative coupling reactions. However, the maximum C2 yield described in this publication is 5
This is 11.7% of rZrOs, which is still insufficient in terms of yield for industrializing ethane/ethylene production, and it is desired to improve the yield in this catalyst system.

[Problem to be solved by the invention]

The present inventor has focused on the fact that composite metal oxides called perovskide type and ilmenite type are prepared by firing two types of metal oxides or metal salts at high temperatures of 1000°C or higher. However, since these are considered to be desirable as heat-resistant and long-life catalysts, they are used in the partial oxidation reaction of methane for the production of ethane and ethylene. The present invention was achieved based on the finding that the conversion rate of methane and the yield of ethane/ethylene can be improved by using a catalyst carrying an alkali metal.

The object of the present invention is to, by using a specific catalyst,
The object of the present invention is to provide a method for efficiently producing ethane and ethylene.

[Means for Solving the Problems] The present invention produces ethane and ethylene by partially oxidizing methane using a catalyst in which an alkali metal halide is supported on a composite metal oxide consisting of two types of metals. It is characterized by

The present invention will be explained in detail below.

The catalyst used in the present invention is a catalyst in which an alkali metal halide is supported on a perovskide-type or ilmenite-type composite metal oxide, and it can be obtained as follows.

In general, if there is a difference in ionic valence between the metals constituting a composite metal oxide and metal B, the smaller one is A, and if the valence is the same, the larger ionic radius is A, then the ideal perovskite In the structure of a composite metal oxide, the following formula holds true.

(Ra+Ro)=f (Rb+Ro) where, Ra,
Rb: ionic radius (human) of metals A and B, Ro: ionic radius (human) of oxygen.

However, in reality, there is a permissible limit, and a coefficient is included as shown in the following equation. Usually, if the coefficient is in the range of 0.8 to 1.0, a perovskite structure is assumed, and if t is 0.8 or less, It is said to have an ilmenite structure.

(Ra+Ro) -t n (Rb+Ro) In the method of the present invention, it is necessary to select a metal in which t falls within the range of 0.75 to 1.0. In addition, the sum of the oxidation numbers of metal A and metal B must be +6 in order to maintain electrical neutrality as a whole crystal, so the metal ion ratio metal B ion is
It is necessary to use two types of metals, such as a combination of monovalent and pentavalent, divalent and tetravalent, or trivalent and trivalent, respectively.

Two types of metal oxides or salts that meet these conditions are mixed in a pestle at an atomic ratio of 1:1, and the mixture is heated to a concentration of 1000 to 15% in air or in a helium stream.
00°C 1 Preferably at a temperature of 1100-1300°C
Bake for ~30 hours, preferably 5-10 hours. After cooling the calcined product obtained by this operation to room temperature, it is crushed and confirmed to have a perovskide structure or an ilmenite structure by powder X-ray diffraction analysis, and then a catalyst is prepared by the following operation.

That is, the obtained perovskide-type or ilmenite-type composite metal oxide is suspended in an aqueous solution of an alkali metal halide, and while stirring the suspension,
The catalyst of the present invention is obtained by heating to 00° C. and evaporating to dryness. At this time, the alkali metal halide has an atomic ratio of 0.05 to 1.
0, preferably 0.1 to 0.3.

As the alkali metal halide, any combination of halogen elements such as fluorine, chlorine, bromine, and iodine and alkali metal elements such as lithium, sodium, potassium, and rubidium can be used, but preferably sodium fluoride, One selected from lithium chloride, sodium chloride, potassium chloride, lithium bromide, sodium bromide and potassium bromide is used.

The catalyst thus obtained can be pulverized and used as a powder of 100 meshes or more, but if necessary, it can be molded with a compression molding machine and then further pulverized, preferably into granules of 16 to 32 meshes. It can also be used as Moreover, these catalysts can also be used on a carrier.

When performing the oxidative coupling reaction of methane using the above catalyst, methane and oxygen are converted into CH.

10, (molar ratio) -1 to 10, preferably 1.5 to 3
Mix and use. At this time, helium is used as a diluent,
An inert gas such as argon or nitrogen may also be present. These mixed gases are supplied to a reaction tube filled with a catalyst, and the temperature is usually 600 to 1000°C, preferably 700 to 850°C.
The 0 reaction, which is a gas phase reaction at °C, is usually carried out under atmospheric pressure, but may be carried out under increased pressure if necessary.

Methane separated from natural gas is usually used in the reaction, but methane produced from coal or other materials may also be used. Furthermore, natural gas itself containing methane can also be used as a raw material. Oxygen that has been cryogenically separated from air or concentrated using a gas separation membrane can be used.

Furthermore, it is also possible to use oxygen in the air as it is.

Further, in the present invention, the catalyst can be used in a fixed bed, moving bed or fluidized bed mode.

[Examples] The present invention will be described below based on Examples, but the present invention is not limited thereto.

Example 1 (1) Preparation of catalyst 0.80 g of sodium carbonate (special grade reagent) and 2.00 g of niobium pentoxide (special grade reagent) (metal ion ratio 1:1) were mixed in a pestle, and heated in the air and with electricity. It was fired in a furnace at 1100°C for 110 hours. It was confirmed by chi-ray diffraction measurement that the fired product was N a N b 03 having a perovskite structure. Next, 0.094 g of sodium chloride was dissolved in 10 ml of distilled water, 31 g of NaNbO was added, and the mixture was dried to dryness in a steam bath.

(2) Reaction test Fill an alumina reaction tube with 1 g of the above catalyst and heat at 780°C.
Under 1 atmospheric pressure, CH-: Oz: He = 10:
Flow a mixed gas of 5:85 at a flow rate of 1QQd/win,
Made it react.

The reaction product obtained by the above operation was introduced into a gas chromatograph using a sampling loop attached to the outlet of the reaction tube and analyzed. The analysis results are shown in Table 1. In Table 1, the methane conversion rate and the oxygen conversion rate are the proportions of reacted methane and oxygen, the selectivity is the production rate of the reaction products COCot, C2H, and czH6, and the C2 yield is the target value. The product CzH+, C2
It represents the total amount of H4 yield.

Comparative Example 1 N a N b O:l was synthesized by the method described in Example 1 (1), and 51 g of NaNbO was used as it was without supporting an alkali metal halide such as sodium chloride, and the reaction temperature was raised to 800 ml. A reaction test was conducted under the same conditions as in Example 1 except that the temperature was changed to .degree. The results are shown in Table 1.

Example 2 (]) Preparation of catalyst 30 g of metallic lead (special grade reagent) and titanium oxide (special grade reagent)
11.58 g was mixed in a mortar and baked under the same conditions as in Example 1. The fired product was confirmed to be PbTi○ with a perovskite structure by X-ray diffraction measurement. next,
2.34 g of sodium chloride was dissolved in 1'OOd of distilled water, 30 g of PbTiOs was added, and the mixture was evaporated to dryness in a steam bath.

(2) Reaction test Using 1 g of the above catalyst, CH=: 02: He=1
A mixed gas of 0:5:85 was flowed at a flow rate of 100 af/win to cause a reaction. The results are shown in Table 1.

Comparative Example 2 1 g of PbTiO was synthesized by the method described in Example 2 (1), 1 g of PbTiOx was directly used without supporting an alkali metal halide such as sodium chloride, and the reaction temperature was set to 800°C. A reaction test was conducted under the same conditions as in Example 2 except for the following. The results are shown in Table 1.

Example 3 Using 30 g of the catalyst prepared in Example 2 (1), CH.

:Oz:He=10:5:85 mixed gas at 135
The reaction was carried out by flowing at a flow rate of Idl/sin. Results first
Shown in the table.

Example 4 (1) Preparation of catalyst Barium carbonate (reagent grade) Ig and titanium oxide (reagent grade) 0.405 g were mixed in a mortar and calcined under the same conditions as in Example 1. WJR confirmed that the fired product was BaTiO3 with a perovskite structure by X-ray diffraction measurement.

Next, 0.05 g of sodium chloride was dissolved in 10 d of distilled water, 31 g of BaTiO was added, and the mixture was evaporated to dryness in a steam bath.

(2) Reaction test The reaction was carried out under the same conditions as in Example 1 except that the reaction temperature was 800°C. The results are shown in Table 1.

Example 5 (1) Preparation of catalyst KNb
O, was synthesized. 0.325 g of sodium chloride was supported on 5 g of KNbOz in the same manner as in Example 1.

(2) Reaction test A reaction test was conducted under the same conditions as in Example 1 using 5 g of the above catalyst. The results are shown in Table 1.

Example 6 (1) Preparation of catalyst P b T i Ox was synthesized by the method described in Example 2 (1).

Next, 0.42 g of lithium chloride was dissolved in 30 g of distilled water, 3 g of PbTiO was added thereto, and the mixture was evaporated to dryness in a steam bath.

(2) Reaction test A reaction test was conducted under the same conditions as in Example 1 except that 3 g of the above catalyst was used and the reaction temperature was 700°C. The results are shown in Table 1.

Example 7 (1) Preparation of catalyst Lithium carbonate (reagent grade) 0.67g and tantalum oxide (
Mix 4g of reagent (special grade) in a pestle and heat in air in an electric furnace.
It was fired at 100'C for 110 hours. The fired product was determined by X-ray diffraction measurements to be LiTa0. It was confirmed that Next, add 0.05 g of sodium chloride to 1
It was dissolved in 0 d of distilled water, 51 g of LiTaO was added thereto, and the mixture was evaporated to dryness in a steam bath.

(2) Reaction test A reaction test was conducted under the same conditions as in Example 1 except that 1 g of the above catalyst was used and the reaction temperature was 750"C. The results are shown in Table 1.

Example 8 (1) Preparation of catalyst PbTiO3 was synthesized by the method described in Example 2 (1).

Next, 0.246 g of potassium chloride was dissolved in 30 d of distilled water, 35 g of PbTiO was added thereto, and the mixture was evaporated to dryness in a steam bath.

(2) Reaction test A reaction test was conducted under the same conditions as in Example 1 except that 1 g of the above catalyst was used and the reaction temperature was 800°C. The results are shown in Table 1.

Example 9 (1) Preparation of catalyst P b T i 03 was synthesized by the method described in Example 2 (1).

Next, 139 g of sodium fluoride O was dissolved in 30 d of distilled water, 055 g of PbTi was added thereto, and the mixture was evaporated to dryness in a steam bath.

(2) Reaction test A reaction test was conducted using 1 g of the above catalyst under the same conditions as on the day of the example. The results are shown in Table 1.

〔Effect of the invention〕

According to the method of the present invention, the yield of the 02 compound is high in the methane oxidation cup-1-Nong reaction, and its industrial value is great.

Claims (9)

[Claims] (1) In the presence of a metal oxide as a catalyst, 600-1
A method for producing ethane and ethylene by partially oxidizing methane or methane-containing natural gas with oxygen or oxygen-containing gas at 000°C, consisting of two metals supported on an alkali metal halide as a catalyst Characterized by the use of composite oxide,
A method for producing ethane and ethylene by partial oxidation of methane. (2) The two types of metals constituting the composite metal oxide are 1
The method for producing ethane and ethylene by partial oxidation of methane according to claim 1, wherein the ions are any one of group A metal ions and any one of group 5A metal ions. (3) The two types of metals constituting the composite metal oxide are 2
2. The method for producing ethane and ethylene by partial oxidation of methane according to claim 1, wherein the metal ion is any one of group A, group 4B, or lanthanide metal ions and any one of group 4A, group 4B, or lanthanide metal ions. (4) The two metals constituting the composite metal oxide are 3
2. The method for producing ethane and ethylene by partial oxidation of methane according to claim 1, wherein the metal ions are any one of group A, 3B, 4A, 6A, and 8 metal ions and any one of group 3A and lanthanide metal ions. (5) In the combination of any one of the group 1A metal ions and any one of the group 5A metal ions, the group 1A metal ion is Li^+, Na^+, K^+, and 5
3. The method for producing ethane and ethylene by partial oxidation of methane according to claim 2, wherein the group A metal ions are Ta^5^+ and Nb^5^+. (6) In the combination of any one of the group 2A, group 4B, or lanthanide metal ions and any one of the group 4A, group 4B, or lanthanide metal ions, the group 2A metal ion is Ca^2^+, S
r^2^+, Ba^2^+, 4B group metal ion is Pb
^2^+, the lanthanide metal ion is Eu^2^+, and the group 4A metal ions are Ti^4^+, Hf^4^+, Z
The production of ethane and ethylene by partial oxidation of methane according to claim 3, wherein the r^4^+, 4B group metal ion is Sn^4^+, and the lanthanide group metal ion is Ce^4^+, Pr^4^+. Method. (7) In the combination of any one of the above-mentioned group 3A, 3B, 4A, 6A, or 8 metal ions and any one of the group 3A or lanthanide metal ions, the group 3A metal ion is Y^
3^+, Sc^3^+, 3B metal ion is Ga^3^+
, Al^3^+, In^3^+, 4A metal ions are Ti
^3^+, the 6A metal ion is Cr^3^+, the group 8 metal ion is Fe^3^+, and the group 3A metal ion is Y^3
^+, lanthanide metal ions are Sm^3^+, Nd^3
5. The method for producing ethane and ethylene by partial oxidation of methane according to claim 4, wherein methane is ^+, Ce^3^+, and La^3^+. (8) The composite metal oxide has a perovskite structure, PbTiO_3, BaTiO_3, SrTiO_3
, NaNbO_3, KNbO_3, NaTaO_3. The method for producing ethane and ethylene by partial oxidation of methane according to claim 1. (9) The method for producing ethane and ethylene by partial oxidation of methane according to claim 1, wherein the composite metal oxide is LiNbO_3 or LiTaO_3 having an ilmenite structure.