JP2009131741A - Selective oxidation catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a selective oxidation catalyst capable of producing 2 or above number of C hydrocarbon. <P>SOLUTION: The selective oxidation catalyst used in the production of 2 or above number of C hydrocarbon is constituted by supporting an organic cyclic compound, which contains an element of the Group XIV, on the surface of tin oxide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a selective oxidation catalyst and a method for producing the same, and more particularly to a selective oxidation catalyst for producing hydrocarbons.

  In the 20th century, the oil industry has played a central role in response to the increase in demand for fuels such as gasoline and light oil accompanying the dramatic increase in transportation equipment such as automobiles and aircraft. However, since oil itself is a limited resource, development of alternative fuels for oil is desired. As the petroleum substitute fuel, for example, ethanol (ethyl alcohol) or methanol (methyl alcohol) from wood or the like, methyl ester or the like from edible oil, etc., which is used as a fuel for transportation equipment, so-called “biofuel”, GTL technology (Gas To Liquid) such as C1 chemistry is attracting attention as a favorite technology, and research and development are being conducted worldwide.

  In particular, GTL technology is a multi-stage process that produces methanol using synthesis gas, which is a mixed gas of carbon monoxide and hydrogen, and produces hydrocarbons, especially olefins, that are used as gasoline feedstock via dimethyl ether. Those that use the reaction, those that use the Fischer-Tropsch reaction (FT method), which is a series of processes for synthesizing liquid hydrocarbons using a catalytic reaction from synthesis gas, which is a mixed gas of carbon monoxide and hydrogen, etc. Since synthetic gas has the advantage that it can be easily produced using natural gas, biomass, coal, garbage, etc. as a raw material, the development of GTL technology can be a national strategy especially for countries without resources.

  Examples of such GTL technology include Patent Documents 1 to 3 described below. Patent Document 1 discloses a catalyst in which a transition metal compound such as manganese and sodium and an alkali metal compound are supported on an oxide superacid such as tungstic acid-supported zirconia (Patent Documents 1 “0007” and “0008”). , "0012" and Example 1).

  Patent Literature 2 discloses lithium compound-supported oxide super strong acids (tables described in paragraphs “0031” to “0032” in Patent Literature 2) such as lithium / sulfate radical-supporting zirconia catalyst and lithium / tin sulfate catalyst.

Patent Document 3 discloses a catalyst in which an alkali metal such as sodium is supported on an oxide of an alkaline earth metal such as magnesium.
Japanese Patent Laid-Open No. 11-253806 JP-A-10-101585 Japanese Patent Publication No. 6-69969

  However, in the catalysts of Patent Documents 1 and 2, only small amounts of C3, C4 and benzene are detected (Patent Document 1, paragraph “0032”, Patent Document 2 “0033”), and the yield of hydrocarbons of C3 or higher is obtained. However, the effectiveness of the catalysts of Patent Documents 1 and 2 is unclear. Further, in the catalyst of Patent Document 3, only C2 hydrocarbons are generated, and C3 or higher hydrocarbons are not generated.

In addition, the known methods for producing C3 and higher hydrocarbons from methane using GTL technology are as follows:
(1) Preparation of synthesis gas (CO + H ₂ ) by steam reforming reaction of methane (reaction temperature 800 ° C., catalyst: nickel), (2) Preparation of methanol from the synthesis gas (reaction temperature 250 to 300 ° C., reaction pressure) 5 to 10 MPa, catalyst Cu / ZnO), and (3) production of C3 and C4 from the methanol (reaction temperature 400 to 500 ° C., catalyst: zeolite) required three complicated steps.

  In addition, products such as C3 and C4 produced in multiple stages are disadvantageous in terms of cost compared to those produced by petroleum cracking. On the other hand, since the price of C3 and C4 products has been increased due to the recent rise in oil prices, a new method that does not cost to produce C3 and C4 from resource-rich methane is required.

  Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a catalyst capable of producing a hydrocarbon having 2 or more carbon atoms.

  Accordingly, an object of the present invention is to provide a selective oxidation catalyst for methane used for producing hydrocarbons, in which an organic cyclic compound containing a Group 14 element is supported on the surface of tin oxide.

When a catalyst formed by supporting an organic cyclic compound containing a Group 14 element of the present invention on the surface of tin oxide, particularly a Ge / SnO ₂ catalyst, hydrocarbons, particularly olefins (C3, C4 hydrocarbons) can be synthesized.

  The first of the present invention is a methane selective oxidation catalyst used for the production of hydrocarbons, comprising an organic cyclic compound containing a Group 14 element supported on the surface of tin oxide.

  By using tin oxide as a catalyst, an effect of high methane oxidation activity can be obtained at a low temperature. Furthermore, by disposing an organic cyclic compound containing a group 14 element on the surface of tin oxide, dissociated oxygen on the surface of tin oxide. It is thought that the movement of can be suppressed.

In other words, the reaction formula (1) in which one proton is extracted from methane is a rate-limiting reaction, but as long as oxygen is present, the reaction formulas (2) to (4) proceed in succession like a cascade reaction. Eventually, methane changes to carbon monoxide (see FIG. 12). FIG. 13 shows the state of oxygen atoms on the SnO ₂ ((110) plane) surface. FIG. 14 shows the state of oxidation and adsorption of CO in the SnO ₂ step. FIG. 15 shows the state of CO oxidation and adsorption on SnO ₂ ((110) plane).

  However, since the transfer of dissociated oxygen present on the surface of tin oxide is suppressed by supporting an organic cyclic compound containing a group 14 element on the surface of tin oxide, the surface of tin oxide is converted to methyl radicals from which protons are extracted from methane. It is considered that the probability that the dissociated oxygen present in the reaction reacts extremely decreases, and hydrocarbons having 2 or more carbon atoms are easily generated by the LH mechanism.

Also shows the movement of adsorbed oxygen on the SnO ₂ in FIGS. 16 17 movement of adsorbed oxygen on (Fig. 16) and Ge substituted SnO ₂ (Figure 17). Furthermore, it is a figure which shows a tin oxide surface state in FIGS.

  The hydrocarbon according to the present invention is preferably a hydrocarbon having 2 to 4 carbon atoms, more preferably ethane, propane, butane, ethylene, propylene, butene, isobutylene, acetylene, butadiene, and 2 or more carbon atoms. Olefins, that is, ethylene, propylene, butene, isobutylene, butadiene and the like are more preferably produced, and hydrocarbons such as propylene, butene, isobutylene and butadiene having 3 and 4 carbon atoms are particularly preferably produced.

  The organic cyclic compound containing a Group 14 element formed on the surface of tin oxide according to the present invention preferably has a gas intake space inside the organic cyclic compound.

  That is, the organic cyclic compound containing a Group 14 element has a gas intake space inside the organic cyclic compound, so that the organic cyclic compound containing a Group 14 element formed on the surface of tin oxide according to the present invention Gas, such as methane, acts as a “guest” in the “host”, and gas such as methane enters the interior (space) of the organic cyclic compound, and the gas such as methane directly attaches and adsorbs to tin oxide. Can do.

  In the case where the organic cyclic compound containing a Group 14 element according to the present invention has a structure represented by the following chemical formula (A), for example, the gas intake space has a distance between facing oxygen atoms-oxygen atoms of 2.566 mm, facing germanium The pores have an atom-germanium atom distance of 2.486Å and an adjacent germanium distance of 1.154Å (see FIG. 2).

  FIG. 27 shows the results showing the relationship between the amount of germanium and the total pore volume.

  The gas intake space according to the present invention is so-called pores, and the diameter of the gas intake space (average value of the maximum length of the intake space) is preferably 0.1 to 5 nm, more preferably 0.2 to 1 nm. Still more preferably, it is 0.2-0.8 nm, Most preferably, it is 0.2-0.5 nm.

  If the gas uptake space is less than 0.1 nm, methane molecules in the methane-containing gas cannot be taken into the uptake space, and if it exceeds 5 nm, the gas uptake space is large, so the dissociated oxygen inside the uptake space already exists. This is because the number increases.

  Further, the diameter of the gas intake space according to the present invention can be measured by a known method, and the measuring method is not particularly limited. For example, TEM (transmission electron microscope), SEM (scanning electron microscope) ), X-ray diffraction, and the like are considered preferable. However, the technique at the time of filing of the present invention cannot accurately measure the diameter, and in fact, simulation (density functional method CASTEP) The diameter of the gas intake space is calculated in combination with SEM. In addition, the “diameter of the gas intake space” in the present specification includes a method of measuring the gas intake space observed in several to several tens of fields for a representative sample from a transmission electron microscope image. In this measurement method, a significant difference occurs in the diameter of the gas intake space depending on the sample to be observed and the visual field.

  The gas uptake space of the organic cyclic compound containing the Group 14 element formed on the surface of the tin oxide of the present invention measures all the maximum diameters of the gas uptake space observed in 8 fields of the transmission electron microscope image, The measurement is performed under the condition that the median diameter is the diameter of the gas intake space.

  Moreover, the organic cyclic compound containing a Group 14 element formed on the surface of tin oxide according to the present invention has a gas intake space containing methane gas that is partitioned by a cyclic energy barrier, and oxygen exceeds the energy barrier. Preferably not.

As described above, tin oxide having high methane oxidation activity at low temperature is used as a catalyst. In general, on the surface of tin oxide, oxygen is dissociated on the outermost surface, and is dissociated oxygen and freely moves on the surface of tin oxide. However, when the dissociated oxygen moves freely on the surface of tin oxide, the activated methane is sequentially oxidized by this oxygen. In fact, if tin oxide is used as a catalyst as it is, the product is all carbon dioxide. The present inventors investigated the possibility of suppressing such sequential oxidation using computational chemistry. As a result, when a part of surface tin ions of tin oxide was replaced with a group 14 element such as germanium ions, the surface migration of oxygen was reduced. We found that there is a possibility of being suppressed. From the results of this simulation, when a cyclic germanium having a nanometer level pore (gas intake space) is uniformly supported on the surface of active tin oxide, a nano-reaction field of tin oxide separated by germanium oxide can be formed. Overcoming this, I think that oxygen may not move on the surface of tin oxide from outside a single nanosize reaction field. In other words, it is thought that the number of oxygen ions involved in the oxidation of methane adsorbed on the nanosize tin oxide reaction field can be reduced. As a result, it is expected that the methanol yield in the sequential oxidation of methane will be improved. The Ge / SnO ₂ catalyst thus prepared has nano-sized pores on the surface. At the same time, it is known from the reports of previous researchers that the surface solid acidity increases when silica is supported on the surface of tin oxide. For this reason, the present inventors believe that solid acidity may be enhanced even when a germanium compound is supported on the surface of tin oxide. These two points are considered to be effective for producing C3 and C4 compounds from methane.

  In addition, the energy at which dissociated oxygen moves freely on the tin oxide surface (around 10 to 20 Kcal / mol in an atmosphere of 300 to 400 ° C.) and the energy for extracting protons from methane (around 15 Kcal / mol in an atmosphere of 300 to 400 ° C.) For example, when an organic cyclic germanium compound having the structure of the chemical formula (A) is formed on the surface of tin oxide, energy required for transfer of dissociated oxygen on the germanium oxide compound (70 Kcal / Therefore, it is difficult for the dissociated oxygen to enter the nano-reaction field (gas intake space) beyond the germanium oxide because the dissociated oxygen is much larger than the energy when the dissociated oxygen moves freely. Therefore, the number of oxygen ions involved in the oxidation of methane adsorbed in the nano-reaction field of tin oxide existing under the organic cyclic germanium compound can be reduced through the gas intake space inside the ring of the organic cyclic germanium compound. Conceivable.

  Therefore, it can be considered that the energy of dissociated oxygen on the surface of tin oxide cannot enter the gas intake space because it is smaller than the energy barrier formed by the organic cyclic compound containing the Group 14 element formed on the surface of tin oxide. .

  Moreover, it is preferable that the catalyst which concerns on this invention contains the compound which has an organic cyclic compound containing a tin oxide and a 14th group element, and also has a Mn atom if needed.

  The compound possessed by the Mn atom may be a Mn atom itself or a compound containing a Mn atom, and the catalyst according to the present invention contains a Group 14 element on the surface of a solid solution of tin oxide and manganese. It is preferable that an organic cyclic compound is formed.

  The solid solution of tin oxide and manganese according to the present invention may be a commercially available product or a synthesized solution. When the solid solution is obtained by synthesis, a compound having Mn atoms by a sol-gel method. By adding the precursor to the solvent simultaneously with the tin oxide precursor, tin and manganese form a solid solution, and it is possible to produce hydrocarbons having 2 or more carbon atoms, particularly hydrocarbons having 2 carbon atoms, without NO. .

  The amount of Mn atoms in the solid solution of tin oxide and manganese according to the present invention is preferably 1 to 15% by mass, more preferably 5 to 15% by mass, and particularly preferably 5 to 10% by mass with respect to tin atoms.

  If it is less than 1% by mass, the effect of the doped manganese atom cannot be expected because there are too few manganese atoms in the system, and if it exceeds 15% by mass, it becomes difficult to form a solid solution of tin oxide and manganese. is there.

  The amount of tin oxide in the entire catalyst according to the present invention is preferably 85 to 95% by mass, and more preferably 85 to 90% by mass.

  The supported amount of the organic cyclic compound containing a Group 14 element with respect to tin oxide according to the present invention is preferably 0.5 to 10% by mass, and 1 to 7.5% by mass with respect to tin oxide in terms of Group 14 element. More preferred is 1.5 to 7.5% by mass.

  If the supported amount of the organic cyclic compound containing the Group 14 element with respect to tin oxide according to the present invention is less than 0.5% by mass, the organic cyclic compound containing the Group 14 element cannot cover the entire surface of the tin oxide. This is because if the content exceeds%, the surface area of tin oxide having active sites is reduced and the activity is reduced.

  The group 14 element conversion calculation method according to the present invention uses known methods such as EPMA such as EDX and WDX, ICP, ESCA and SIMS, and is not particularly limited.

  The catalyst according to the present invention may have any shape and is not particularly limited, and examples thereof include powder, pellets, rods, tablets, and membranes. The catalyst according to the above may be supported, and the supporting method is not particularly limited.

  The size of the catalyst according to the present invention is appropriately selected depending on the method of using the catalyst. For example, the catalyst according to the present invention is distributed in the form of a powder as in the examples described later. As for the particle diameter when using for a type | formula reaction apparatus, 200-300 nm is preferable. The particle diameter of the catalyst according to the present invention can be measured by a known method, and the measurement method is not particularly limited. For example, TEM (transmission electron microscope), SEM (scanning electron microscope), X It is preferable to use line diffraction or the like, and in the present invention, measurement is performed using TEM (transmission electron microscope) and X-ray diffraction.

  The catalyst according to the present invention may be primary particles, secondary particles, or an aggregate of primary particles and secondary particles, and the size of the catalyst is an average size of a mixture of primary particles and secondary particles. Therefore, the particle diameter of the catalyst is an average particle diameter of a mixture of primary particles and secondary particles.

The BET specific surface area of the catalyst according to the present invention is preferably 20 to 35 m ² / g, and a value measured according to a known BET specific surface area measuring method can be used as the specific surface area. For _example, N 2 BET specific surface area. The N ₂ -BET specific surface area is obtained by first putting a sample into a sample tube, evacuating it, cleaning the surface, and then measuring the weight of the sample. The adsorption cell is attached to the apparatus again, the sample is cooled to the liquid nitrogen temperature (about 77 K), and nitrogen gas is sent into the cell. When nitrogen gas is adsorbed on the sample surface and the amount of gas blown is increased, the sample surface is covered with gas molecules. The state in which the gas molecules are adsorbed in a multiple manner is plotted as a change in the adsorption amount with respect to a change in pressure. From this graph, the adsorption amount of gas molecules adsorbed only on the sample surface is obtained from the BET adsorption isotherm. The surface area of the sample can be measured from the amount of adsorbed gas because the adsorption occupation area of nitrogen molecules is known in advance.

  The organic cyclic compound according to the present invention is not particularly limited as long as it has a cyclic structure. For example, even if the organic cyclic compound has a random structure as shown in the following chemical formula (3), the regularity A three-dimensional structure, that is, a sesqui skeleton in which M is bonded to three oxygens and oxygen is bonded to two Ms, for example, silsesquioxane, etc. The thing of the three-dimensional structure (T8, T10, T12) expressed may be sufficient.

  In the formula (3), each R is independent and is an alkyl group having 1 to 10 carbon atoms, and each M is independent and is selected from the group consisting of a silicon atom, a germanium atom, and a tin atom. Preferably, the atom is at least one atom.

  The organic cyclic compound containing a Group 14 element according to the present invention has the following chemical formula (1):

(In the above formula, R ₃ , R ₅ , and R ₇ are each independently an alkyl group having 1 to 10 carbon atoms,
Each R ₁ is independently a single bond or an alkyl group having 1 to 10 carbon atoms;
Each R ₈ is independently a single bond, a hydrogen atom, a halogen atom, a hydroxyl group, or a carboxyl group;
R ₂ , R ₄ , and R ₆ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, or a carboxyl group,
M is each independently at least one atom selected from the group consisting of a silicon atom, a germanium atom, and a tin atom;
r is an integer of 1 to 10,
n, m, l and p are each independently an integer of 0 to 4 and n + m + l + p = an integer of 3 to 16, and the following chemical formula (2):

(In the formula (2), each R ₉ is independent and has an alkyl group having 1 to 10 carbon atoms,
M is each independently at least one atom selected from the group consisting of a silicon atom, a germanium atom, and a tin atom, and M in the chemical formula (2) binds to three oxygens; Oxygen has a structure having a sesqui skeleton bonded to two M, and has the following T unit:

Is preferably at least one selected from the group consisting of compounds having 4 to 12.

  In the formula of the chemical formula (1) according to the present invention, each M is independent and is preferably at least one atom selected from the group consisting of a silicon atom, a germanium atom, and a tin atom. Even more preferred is an atom, and especially preferred is a germanium atom.

In the formula of the chemical formula (1) according to the present invention, R ₃ , R ₅ , and R ₇ are each independent, and R ₃ , R ₅ , and R ₇ are each an alkyl group having 1 to 10 carbon atoms. Preferably, it is an alkyl group having 1 to 4 carbon atoms, and specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, and a t-butyl group.

In the formula of the chemical formula (1) according to the present invention, each R ₁ is preferably independently a single bond or an alkyl group having 1 to 10 carbon atoms, and is preferably a single bond or 1 to 4 carbon atoms. An alkyl group is more preferable, and specific examples include a single bond, a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, and a t-butyl group.

R ₈ in the chemical formula (1) according to the present invention is preferably independently a single bond, a hydrogen atom, a halogen atom, a hydroxyl group, or a carboxyl group, and more preferably a single bond or a hydroxyl group. preferable.

R ₂ , R ₄ , and R ₆ in the chemical formula (1) according to the present invention are each independently preferably a hydrogen atom, a halogen atom, a hydroxyl group, or a carboxyl group, and more preferably a hydroxyl group. preferable.

It is preferable that r in the formula of the chemical formula (1) according to the present invention is independently an integer of 1 to 10, and r in the formula of the chemical formula (1) according to the present invention is an organic according to the present invention. Represents a repeating unit of a cyclic compound, preferably an integer of 1 to 10. When r is 2, it is a dimer, when r is 3, it is a trimer. It becomes the structure where the repeating unit of an organic cyclic compound connects. In addition, when r is 2, any one of R ₁ and R _{8 in} the chemical formula (1) is a single bond.

  N, m, l, and p in the formula of the chemical formula (1) according to the present invention are each independently a repeating unit of each unit, and each of n, m, l, and p is an integer of 0 to 4 In addition, n + m + l + p = an integer of 3 to 16 is preferable, n + m + l + p = an integer of 3 to 12 is more preferable, and an integer of 4 to 12 is particularly preferable.

In the chemical formula (2) according to the present invention, each R ₉ is independent and preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, Specific examples include a single bond, a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, and a t-butyl group.

  In the chemical formula (2) according to the present invention, M in the chemical formula (2) is bonded to three oxygens, oxygen is a sesqui skeleton bonded to two Ms, and the T unit is 4 to 12 It is preferable that it is, it is more preferable that it is 6-12, and it is especially preferable that it is 6-10.

  In the chemical formula (2) according to the present invention, M is bonded to three oxygens, and the sesqui skeleton in which oxygen is bonded to two Ms includes, for example, the following cubic shape, and the following chemical formula ( In 4), the T unit is 8.

  In the above formula (4), each R is preferably independently an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. Examples include a bond, a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, and a t-butyl group. M is independent and is preferably at least one atom selected from the group consisting of a carbon atom, a silicon atom, a germanium atom, a tin atom, and a lead atom. For example, M in the chemical formula (3) Is silicon, it is called T8 silsesquioxane or the like.

  Generally, the main chain is composed of “—M—O—” which is a bond between any one of the group 14 elements and oxygen (for example, a siloxane bond when the group 14 element is silicon). Can be represented by the following four groups.

Moreover, said Chemical formula (4) is T8, T6, T10, T12 other than the said Chemical formula (4) etc. can be used suitably as an organic cyclic compound containing the group 14 element concerning this invention. In the formulas of the M unit, D unit, T unit, and Q unit, M is the same condition as in the chemical formula (1), and the Ra, Rb, and Rc have 1 to 10 carbon atoms. The alkyl group is the same as in the chemical formula (1), and is omitted here.
"Catalyst production method"
In the second aspect of the present invention, an organic cyclic compound containing a Group 14 element is supported on the surface of tin oxide, and after a firing treatment and / or a drying treatment step, a powder made of the organic cyclic compound-supported tin oxide is obtained. This is a method for producing a selective oxidation catalyst for methane used for producing hydrocarbons having 2 or more carbon atoms.

The tin oxide according to the present invention may be a commercially available one or a synthesized one. As a method for synthesizing tin oxide according to the present invention, a known method can be used and is not particularly limited. For example, tetraethoxytin Sn (OC ₂ H ₅ ) ₄ , tetra-i-propoxytin approx . _{Sn (O-i-C 3} H 7) 4, tetra -n- butoxy tin _{Sn (O-n-C 4} H 9) 4 precursor of tin oxide, such as an inert gas (Ar, He, Ne, etc.) A solution having a concentration of 0.1 to 125 g / l, which is added to a solvent under an atmosphere and stirred and mixed to be completely dissolved, is dried up for 1 to 10 days. Subsequently, it was dried using a dryer at 60 ° C to 100 ° C for 3 days to 7 days. Then, after baking in the air at 600-1000 degreeC for 6 to 48 hours, it can cool and can obtain a tin oxide. The tin oxide precursors may be used alone or in combination. In addition, since the said solution should just melt | dissolve, it does not restrict | limit in particular.

  Furthermore, when adding a compound containing Mn atoms in tin oxide, that is, when forming a solid solution of tin oxide and manganese, 5 to 20% by mass with respect to the tin oxide precursor together with the tin oxide precursor. Then, a compound containing Mn atoms or a precursor thereof is added to the solvent under the inert gas atmosphere.

  The compound containing Mn atom or a precursor thereof is not particularly limited as long as it can form a solid solution of tin oxide and manganese, and examples thereof include tetraisopropoxy manganese.

  Examples of the solvent include lower alcohols such as methanol, ethanol, propanol and isopropanol, dehydrated alcohols such as dehydrated methanol, dehydrated ethanol, dehydrated propanol and dehydrated isopropanol, THF and acetone.

  The preparation method of tin oxide carrying an organic cyclic compound containing a Group 14 element according to the present invention includes a solid phase method, a liquid phase method, or a gas phase method, and an organic cyclic compound containing a Group 14 element is added to a solvent. Although the method of apply | coating the prepared solution directly to the surface of tin oxide and drying (60-100 degreeC) and baking (600-1000 degreeC) etc. are mentioned, It does not restrict | limit in particular.

  An organic cyclic compound containing a group 14 element according to the present invention is preferably used as an organic solvent solution, supported on tin oxide under an inert gas atmosphere, and calcined at 600 to 1000 ° C. More preferably, it comprises baking at 700 to 1000 ° C., particularly preferably baking treatment at 700 to 900 ° C.

  The tin oxide carrying the organic cyclic compound containing the Group 14 element of the present invention can be carried by a solid phase method, a liquid phase method, a gas phase method or other methods, and the liquid phase method is preferred among them.

  Hereinafter, preferred examples (liquid phase method, so-called sol-gel method) for preparing tin oxide carrying an organic cyclic compound containing a Group 14 element according to the present invention will be described, but the scope of the present invention is limited to these. It is not something.

  The tin oxide according to the present invention (optionally containing 1 to 15% by mass of Mn atoms with respect to tin in the tin oxide) is added to the solvent under an inert gas atmosphere, and the mixture is stirred and mixed. After preparing a completely dissolved solution having a concentration of 0.1 to 125 g / l, a predetermined amount of a precursor of an organic cyclic compound containing a Group 14 element was added to the solution, and the mixture was stirred and mixed to produce tin oxide ( If necessary, a solution containing 1-15% by mass of Mn) and a precursor of an organic cyclic compound containing a Group 14 element is prepared. Subsequently, it dries up over 1-10 days, stirring further. Next, using a dryer, after drying at 60 ° C. to 100 ° C. for 3 to 7 days, firing at 600 to 1000 ° C. in the air for 6 to 48 hours, and then cooling to obtain an organic cyclic compound containing a Group 14 element A supported tin oxide can be obtained.

The precursor of the organic cyclic compound containing a Group 14 element according to the present invention is appropriately selected depending on the organic cyclic compound containing a Group 14 element formed on the tin oxide surface. In the case of forming an organic cyclic compound containing silicon, a known silane coupling agent can be used and is not particularly limited, and a silane coupling agent represented by Xa-Si (ORg) ₃ is preferable. Specifically, Si (C ₂ H ₅ O) ₃ C ₂ H ₅ , Si (CH ₃ O) ₃ CH ₃ , Si (C ₃ H ₇ O) ₃ C ₃ H ₇ , Si (C ₄ H ₉ O ) ₃ C ₄ H ₉ , Si (C ₂ H ₅ O) _4, etc., and in the above Xa-Si (ORg) ₃ , Rg may be the same, partially the same, or all different. , Methyl, et Til, propyl, butyl, cyclohexyl, hexyl, octyl, phenyl, benzyl, naphthyl, methoxy, ethoxy, propoxy and the like, and these hydrocarbon groups may be branched or linear, and Xa is C1-C10 alkyl group (methyl, ethyl, propyl, butyl, cyclohexyl, hexyl, octyl, etc.), methyl acrylate group, acrylate group, epoxy group (glycidyl group), amino group, hydroxyamino group, vinyl group, acetylene Group, carbonyl group, dicarbonyl group, acid anhydride group, aldehyde group, isocyanate group, mercapto group, alkyl mercapto group, chloro group, bromo group, fluoro group, iodo group, formamide group, acetamide group, cyano group, amide group Reactivity of imide group, hydroxyl group, oxazoline group, etc. And these groups substituted with substituted alkyl hydrocarbon group include substituted alkenyl groups.

Moreover, when forming the organic cyclic compound containing germanium on the surface of tin oxide, a precursor represented by Xa-Ge (ORg) ₃ is preferable, and specifically Ge (C ₂ H ₅ O) ₃ C _{2. H 5, Ge (CH 3 O} ) 3 CH 3, Ge (C 3 H 7 O) 3 C 3 H 7, Ge (C 4 H 9 O) 3 C 4 H 9, Ge (C 2 H 5 O) 4 In the above Xa-Ge (ORg) ₃ , Rg may be the same, partly the same or all different, and methyl, ethyl, propyl, butyl, cyclohexyl, hexyl, octyl, phenyl , Benzyl, naphthyl, methoxy, ethoxy, propoxy, etc., and these hydrocarbon groups may be branched or linear, and Xa is an alkyl group having 1 to 10 carbon atoms (methyl, ethyl, Propyl, butyl, cyclohexyl, hexyl, octyl, etc.), methyl acrylate group, acrylate group, epoxy group (glycidyl group), amino group, hydroxyamino group, vinyl group, acetylene group, carbonyl group, dicarbonyl group, acid anhydride Product group, aldehyde group, isocyanate group, mercapto group, alkyl mercapto group, chloro group, bromo group, fluoro group, iodo group, formamide group, acetamide group, cyano group, amide group, imide group, hydroxyl group, oxazoline group, etc. Examples thereof include a reactive group and a substituted alkyl or substituted alkenyl group in which these groups are substituted with a hydrocarbon group.

Moreover, when forming the organic cyclic compound containing tin on the tin oxide surface, for example, a precursor represented by Xa-Sn (ORg) ₃ , specifically Sn (C ₂ H ₅ O) ₃ C _{2 H 5, Sn (CH 3 O} ) 3 CH 3, Sn (C 3 H 7 O) 3 C 3 H 7, Sn (C 4 H 9 O) 3 C 4 H 9, Sn (C 2 H 5 O) 4 Tetraethoxytin Sn (OC ₂ H ₅ ) ₄ , tetra-i-propoxytin approx. It may be used in combination with Sn (Oi-C ₃ H ₇ ) ₄ , tetra-n-butoxytin Sn (On-C ₄ H ₉ ) _4, etc. In the above Xa-Ge (ORg) ₃ , Rg, and Xa are the same as above, and are omitted here.

  Moreover, the precursor of the organic cyclic compound containing the said group 14 element may be used independently or may be mixed and used. Furthermore, since the said solvent can use the thing similar to what was used by the suitable synthesis method of tin oxide, it abbreviate | omits here.

  A gas phase method other than those described in the above preferred examples can be used as a method for preparing tin oxide carrying an organic cyclic compound containing a Group 14 element according to the present invention. There is no particular limitation, and for example, an organic ring containing a group 14 element under a low pressure as used in a physical vapor phase method such as a vacuum deposition method, a sputtering method, or an ion plating method. Examples include a method of forming a compound on a tin oxide surface by heating and evaporating or sublimating the compound.

  The third aspect of the present invention is a method for producing hydrocarbons comprising reacting a raw material gas containing methane and molecular oxygen at a temperature of 400 to 700 ° C. in the presence of the catalyst according to the present invention. Moreover, it is preferable to make the said raw material gas react at the temperature of 500-700 degreeC, and it is more preferable to make the said raw material gas react at the temperature of 500-600 degreeC.

  Tin oxide formed on the surface of an organic cyclic compound containing a Group 14 element, which is a catalyst according to the present invention (If necessary, Mn atoms may be contained in an amount of 1 to 15% by mass with respect to tin in the tin oxide. ) As an active component of the catalyst, it may be used as it is supported on a carrier, or may be used as it is, and its usage is not limited. For example, the catalyst according to the present invention is a powder. In some cases, the catalyst can be obtained by molding into pellets, spheres, rings, or irregular shapes as necessary.

"Olefin production method"
The catalyst obtained by the above method is used for the production of C ₃ and / or C ₄ hydrocarbons having 2 or more carbon atoms from a methane-containing gas. For example, if necessary for methane containing a molecular oxygen-containing gas, it is passed through a raw material gas to which nitrogen monoxide and an inert gas are added and a catalyst layer, and is 400 to 700 ° C., preferably 500 to 600 ° C. It is preferable to make it react on condition of space velocity 20000-100,000h- ^{1 at} temperature.

  In addition, the conversion rate and selectivity in this specification are based on the following definition.

  The methane-containing gas according to the present invention is a gas containing methane and oxygen, and further containing NO and He as necessary. The methane gas is preferably contained in an amount of 50 to 70% by mass with respect to the total mass of the methane-containing gas. The oxygen gas is preferably contained in an amount of 20 to 30% by mass with respect to the total mass of the contained gas, and the He gas containing 3% of NO with respect to the mass of the entire methane-containing gas is preferably contained in an amount of 0 to 22% by mass. .

  Hereinafter, the present invention will be specifically described based on examples. In addition, this invention is not limited only to these Examples.

"Catalyst preparation method"
1) Synthesis of tin oxide After weighing 25 g of Sn (Oi-C ₃ H ₇ ) ₄ , it was put into a beaker containing 500 ml of dehydrated ethanol in an Ar atmosphere glove box, and stirred and mixed to be completely dissolved. . Subsequently, after completely dissolving, it was taken out from the glove box and dried up for 7 days while mixing in air. Furthermore, it was dried for 3 days using a dryer. Then, after baking in the air at 700 degreeC for 24 hours, it cooled and it was set as the tin oxide sample (surface area 31.6m < ² > / g).

2) Synthesis of germanium-supported tin oxide (0.75 wt% Ge / SnO ₂ ) After weighing 5 g of the tin oxide sample prepared as described above, it was added to a beaker containing 100 ml of dehydrated ethanol in an Ar atmosphere glove box. did. Further, 1.10 ml of Ge (C ₂ H ₅ O) ₃ C ₂ H ₅ was added to this mixed solution and mixed with stirring. Next, after sufficiently stirring and mixing in the glove box, the beaker was taken out into the atmosphere and further dried for 3 to 7 days while stirring. Then, it dried for 1 day using the dryer. Then, after baking in the air at 700 ° C. for 24 hours, the sample was cooled to obtain a germanium-supported tin oxide sample.

Also shows synthesis of germoxane catalyst is germanium-bearing tin oxide _{(0.25 wt% Ge / SnO 2} ) to a flow chart (FIG. 4).

"TOF-MASS measurement"
As prepared in the column of “Catalyst Preparation Method”, TOF-MASS measurement of EtGe (OEt) ₃ used for the germanium-supported tin oxide sample was performed. The result is shown in FIG.

The EtGe (OEt) ₃ was a gel-like sample prepared by dissolving EtGe (OEt) ₃ in dehydrated ethanol.

As shown in FIG. 3, it was confirmed from the experimental results of TOF-MASS that EtGe (OEt) ₃ was dehydrated in the solution. After the stirring reaction and dry-up for 7 days, it is considered that tetragermanol is coated on the SnO ₂ surface in the same manner as tetracinol. The amount of the germanium monolayer calculated from the size of tetrageranol on the SnO ₂ surface was defined as 1 ML.

"SEM and HRTEM measurement"
FIG. 5 shows an SEM image using a SEM (comment: if you know the machine name, manufacturer, etc.) of the germanium-supported tin oxide germanium catalyst (0.25 wt% Ge / SnO ₂ ). An HRTEM image using HRTEM is shown in FIG.

From these results, it is confirmed that the surface of the germanium-supported tin oxide (0.25 wt% Ge / SnO ₂ ) of the present invention has innumerable pores as gas intake spaces.

“Method for producing hydrocarbons having 2 or more carbon atoms using a germanium-supported tin oxide catalyst using a fixed-bed flow reactor”
FIG. 7 shows the results of a methane selective oxidation reaction using a 7.5 wt% Ge / SnO ₂ sample. FIG. 8 is an enlarged view of the selectivity of the C ₃ H ₆ and C2 components.

A germanium-supported tin oxide (7.5 wt% Ge / SnO ₂ sample) catalyst (powder) 0.3 g was inserted into a quartz tube so as to be sandwiched between quartz wool, and a methane-containing gas ( The reaction gas was CH ₄ : O ₂ : NO = 2: 1: 0.5, and a hydrocarbon having 2 or more carbon atoms was produced under the conditions of a total flow rate of 285 ml / min. According to this, at 723 K, the methane conversion was 2.3%, and the selectivity for C ₃ H ₆ was about 3%.

FIG. 11 shows a gas phase reaction in the absence of a catalyst. FIG. 22 shows the results showing the change in the CH ₃ OH conversion rate.

"Analysis by gas chromatography"
The gas obtained by the above production method was analyzed using gas chromatography. The result is shown in FIG. As CO and CO ₂ , TCD (Shimadzu Corporation GC8A Column Gas Chro back 54 4 m) was used, and for others, FID (G14A column SHIN carbon 2 m) was used.

FIG. 29 shows the results of analysis using gas chromatography.
"XRD measurement"
FIG. 20 shows the result of XRD measurement.

(Comparative example)
"Selectivity with SnO ₂ catalyst and GeO ₂ catalyst using fixed bed flow reactor"
Using the same fixed bed flow reactor as in the Examples using SnO ₂ catalyst obtained by the synthesis of tin oxide of 1) and GeO ₂ catalyst (manufactured by Wako Pure Chemical Industries, Ltd.), 55.6 volumes of methane %, Oxygen gas 27.7 vol%, nitric oxide 0.5 vol% and helium 16.2 vol% are circulated at a flow rate of 240 ml / min and reacted at temperature to react with the oxidation activity of methane (methane The conversion rate) and the selectivity of the product such as propylene were examined. The results shown in FIG. 10 were obtained. In addition, the analysis of each product at this time was performed using the gas chromatography.

  Propane gas, which is necessary for adjusting the calorific value of a gas company that supplies natural gas, can be produced in-house without purchasing it from an oil company. A chemical company that synthesizes propane and propylene from petroleum can produce C3 hydrocarbons from methane, which is abundant and stable in price.

FIG. 1 is a schematic view in which an organic cyclic compound containing a Group 14 element is supported on the surface of tin oxide. It is a figure which shows the structure of an example of the organic cyclic compound containing the 14th group element of this invention. It is a figure which shows the experimental result of TOF-MASS of the germanium compound which is an example of the organic cyclic compound containing the group 14 element of this invention. It is a flowchart which shows the experimental method of the germanium catalyst which is an example of the catalyst of the tin oxide of this invention, and the organic cyclic compound containing a Group 14 element. It is a SEM image of a germoxane catalyst which is an example of the catalyst of the tin oxide of this invention and the organic cyclic compound containing a 14th group element. It is a HRTEM image of the germanium catalyst which is an example of the catalyst of the tin oxide of this invention, and the organic cyclic compound containing a Group 14 element. It is an experimental result which shows the relationship between the selectivity and temperature in a present Example. It is an experimental result which shows the relationship between the selectivity and temperature in a present Example. The experimental result of the gas chromatography in a present Example is shown. It is a diagram showing a is SnO _2, GeO ₂ alone oxide selectivity of the experimental results of methane oxidation activity and the product of Comparative Example. It is an experimental result which shows the gas phase reaction in the absence of a catalyst. It is a figure which shows the reaction mechanism considered at the time of the application of this invention. It is a schematic diagram showing a state of oxygen atoms of the SnO ₂ ((110) plane) surface. It is a schematic diagram which shows the oxidation and adsorption state of CO in SnO ₂ step. It is a schematic diagram which shows the state of oxidation and adsorption of CO in SnO ₂ ((110) plane). Is a diagram illustrating the movement of adsorbed oxygen on the SnO _2. Ge is a diagram illustrating the movement of adsorbed oxygen on the substituted SnO _2. It is a figure which shows the tin oxide surface state. It is a figure which shows the tin oxide surface state. It is a figure which shows the experimental result (relationship between a selectivity and temperature) of this invention. The result of a XRD measurement is shown. It is a figure which shows the relationship between reaction temperature and the conversion rate of methanol. It is a diagram showing a relationship between dV _p / dr _p and _r p / nm. The measurement results of Ge / SnO ₂ by the MP method. It is a figure which shows the relationship between formation ratio and temperature. It is a figure which shows the experimental result (relationship between a selectivity and temperature) of this invention. It is a figure which shows the relationship between the amount of germanium and total pore volume. It is a figure which shows the experimental result (relationship between a selectivity and temperature) of this invention. The experimental result of the gas chromatography in a present Example is shown. It is a figure which shows the experimental result (relationship between a selectivity and temperature) of this invention.

Claims (7)

  A selective oxidation catalyst for methane, which is used for producing a hydrocarbon having 2 or more carbon atoms, comprising an organic cyclic compound containing a Group 14 element supported on the surface of tin oxide.   2. The catalyst according to claim 1, wherein the organic cyclic compound containing a Group 14 element formed on the surface of the tin oxide has a gas intake space for taking a methane-containing gas into the organic cyclic compound. . The organic cyclic compound containing the Group 14 element has the following chemical formula (1):
(In the above formula, R ₃ , R ₅ , and R ₇ are each independently an alkyl group having 1 to 10 carbon atoms,
Each R ₁ is independently a single bond or an alkyl group having 1 to 10 carbon atoms;
Each R ₈ is independently a single bond, a hydrogen atom, a halogen atom, a hydroxyl group, or a carboxyl group;
R ₂ , R ₄ , and R ₆ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, or a carboxyl group,
M is each independently at least one atom selected from the group consisting of a silicon atom, a germanium atom, and a tin atom;
r is an integer of 1 to 10,
n, m, l and p are each independently an integer of 0 to 4 and n + m + l + p = an integer of 3 to 16, and the following chemical formula (2):
(In the formula (2), each R ₉ is independent and has an alkyl group having 1 to 10 carbon atoms,
M is each independently at least one atom selected from the group consisting of a silicon atom, a germanium atom, and a tin atom, and M in the chemical formula (2) binds to three oxygens; Oxygen has a structure having a sesqui skeleton bonded to two M, and has the following T unit:
The catalyst according to claim 1 or 2, which is at least one selected from the group consisting of compounds having 4 to 12).   The catalyst of any one of Claims 1-3 whose load of the organic cyclic compound containing the 14th group element with respect to the said tin oxide is 0.5-10 mass% in conversion of 14th group element.   Carbon obtained by supporting an organic cyclic compound containing a Group 14 element on the surface of tin oxide and performing a firing treatment and / or a drying treatment step, and then obtaining a powder comprising the organic cyclic compound-supported tin oxide. A method for producing a selective oxidation catalyst for methane used for the production of hydrocarbons of several or more.   The method according to claim 3, comprising using an organic cyclic compound containing the Group 14 element as an organic solvent solution, supporting tin oxide in an inert gas atmosphere, and performing a baking treatment at 600 to 1000 ° C. 5.   Production of a hydrocarbon having 2 or more carbon atoms, comprising reacting a raw material gas containing methane and molecular oxygen in the presence of the catalyst according to any one of claims 1 to 3 at a temperature of 400 to 700 ° C. Method.