JP2005225780A - Method for producing alcohol and / or ketone - Google Patents

Abstract

Provided is a method for producing a corresponding alcohol and / or ketone from an alkene that can stably operate the reaction process while maintaining high selectivity by using an oxide catalyst in a gas phase.
When an oxide catalyst containing oxides of molybdenum and tin is used and a reaction is performed in a fluidized bed system, a catalyst having Mo / (Sn + Mo) in the range of 0 ≦ X <0.50 is used.
[Selection] No selection

Description

  The present invention relates to a process for producing the corresponding alcohol and / or ketone from an alkene in the gas phase using an oxide catalyst in the presence of water vapor.

Examples of producing the corresponding alcohol and / or ketone from the alkene by gas phase reaction in the presence of water vapor include, for example, production of acetone from propylene, production of methyl ethyl ketone (MEK) from 1-butene or 2-butene, Examples include production of silohexanone from cyclohexene and production of tert-butanol from isobutene. All of these products are industrially extremely important chemical substances as chemical starting materials and solvents.
The prior art of the above reaction mainly includes a Wacker type reaction using a noble metal catalyst such as a palladium compound and a reaction using a complex oxide catalyst of a non-noble metal such as molybdenum, tungsten, tin or cobalt.

As an example of the former Wacker-type reaction, there is a method of producing a carbonyl compound in the presence of olefin, oxygen and water vapor using a catalyst in which palladium and / or a palladium compound and copper chloride are supported on a carrier such as silica and alumina. (For example, refer to Patent Document 1).
In the example of Patent Document 1, there is a description of producing MEK from 1-butene using a catalyst in which palladium chloride and copper chloride are supported on silica.
As another example in which chloride is not used as a catalyst, when producing acetaldehyde or ketones by gas phase oxidation of olefins with oxygen or an oxygen-containing gas in the presence of water vapor, palladium salts and vanadyl salts are converted to activated carbon as catalysts. There is a method of using a supported catalyst (for example, see Patent Document 2).

In the example of Patent Document 2, there is a description of producing acetone from propylene using a catalyst in which palladium sulfate and vanadyl sulfate are supported on activated carbon.
However, these catalysts use very expensive noble metals, and according to the inventors' additional tests, both catalysts were found to deteriorate in activity in a short time.
On the other hand, an example of the latter not using a noble metal catalyst is a method of reacting olefin and oxygen in the presence of water vapor using a catalyst comprising molybdenum oxide and finely divided tin oxide uniformly distributed on the support. (For example, refer to Patent Document 3).
In the example of Patent Document 3, there is a description of producing acetone from propylene using a catalyst in which tin dioxide and molybdenum trioxide are supported on silica.

Further, as an example using a similar catalyst, a method of reacting a mixture of olefin and steam using a catalyst in which molybdenum oxide, tin oxide, a specific amount of alkali metal and / or alkaline earth metal is supported on a carrier. There is. (For example, see Patent Document 4)
In the example of Patent Document 4, MEK is produced from transbutene using a catalyst in which tin dioxide, molybdenum trioxide, and sodium are supported on silica.
In addition, there is a method in which a similar catalyst is used and a gas comprising an olefin and water vapor containing a small amount of oxygen in the reaction raw material and a gas containing a large amount of oxygen are alternately brought into contact with the catalyst. (For example, refer to Patent Document 5).

In the example of Patent Document 5, there is a description of producing MEK from n-butene using a catalyst in which tin dioxide and molybdenum trioxide are supported on silica.
However, these are often carried out in fixed bed reactions and there is no disclosure of catalysts optimized for fluid bed reactions.
JP-A-49-72209 JP 59-163335 A Japanese Patent Publication No. 47-8046 JP 49-61112 A Japanese Patent Publication No.49-34652

  In the reaction for producing a corresponding alcohol and / or ketone from an alkene in the gas phase using an oxide catalyst in the presence of water vapor, the present invention has good fluidity when the reaction is carried out in a fluidized bed system. An object of the present invention is to provide a method for stably producing a target product with high activity and high selectivity by using a simple catalyst.

As a result of intensive studies to solve the above problems, the present inventors have (a) a catalyst having an atomic ratio of molybdenum and tin within a specific range, and (b) carrying out the reaction in a fluidized bed reaction system. Has been found to be suitable for the purpose, and the present invention has been made based on this finding.
That is, this invention relates to the manufacturing method shown below.
(1) A method for producing an alcohol and / or ketone corresponding to an alkene by reacting a raw material containing at least one alkene with an oxide catalyst in a gas phase in the presence of water vapor. The method for producing the alcohol and / or ketone is characterized by satisfying the requirements of (a) and (b).
(A) The oxide catalyst contains molybdenum and tin oxide, and the atomic ratio of molybdenum to tin X {Mo / (Sn + Mo); where Mo is the number of molybdenum atoms in the oxide catalyst, and Sn Is the number of tin atoms in the oxide catalyst. } Is in the range of 0 ≦ X <0.50,
(B) The reaction is carried out in a fluidized bed reaction system.

(2) The method according to (1), wherein unreacted alkene, alcohol and / or ketone is recovered from the reaction mixture obtained by the reaction, and the unreacted alkene is recycled as a part of the raw material.
(3) The method according to (1) or (2), wherein the reaction is performed in a manner of circulating between a fluidized bed reactor and a regenerator.
(4) The oxide catalyst contains molybdenum and tin oxide, and the atomic ratio of molybdenum and tin X {Mo / (Sn + Mo); where Mo is the number of molybdenum atoms in the oxide catalyst, and Sn Is the number of tin atoms in the oxide catalyst. } Is in the range of 0.01 ≦ X ≦ 0.24, the method according to any one of (1) to (3).
(5) The method according to any one of (1) to (4), wherein the alkene is 1-butene and / or 2-butene.
(6) The method according to any one of (1) to (5), wherein the reaction is performed under a condition in which molecular oxygen is not supplied.

  According to this production method, the reaction process can be stably operated while maintaining a high selectivity of the target substance.

Hereinafter, the present invention will be described in detail.
The catalyst used in the method of the present invention is a catalyst containing molybdenum and tin oxides.
These oxides are preferable because molybdenum oxide and tin oxide are mechanically mixed and / or used as a composite oxide because they have the effect of improving the catalytic activity and the selectivity of the target product. In addition, oxides of other elements can be added to further improve the catalytic activity and the selectivity of the target product. Elements belonging to Group 4, Group 5, Group 6, Group 8, Group 8, Group 10, Group 10, Group 11, Group 14 and Group 15 of the periodic table are preferred, and more preferably, Group 4 Group elements are titanium and zirconium, Group 5 elements are vanadium and niobium, Group 6 elements are tungsten and chromium, Group 8 elements are iron, Group 9 elements are cobalt, The Group 10 element is nickel, the Group 11 element is copper, the Group 14 element is lead, and the Group 15 element is bismuth, antimony, and phosphorus. The periodic table referred to here is a group 18 element periodic table described in I-56 page of Chemical Handbook Basic Edition I revised 4th edition (Edited by The Chemical Society of Japan, Maruzen, 1993). If it is a trace amount, an alkali metal such as sodium, potassium or rubidium or an oxide of an alkaline earth metal such as magnesium, calcium or barium may be further added.

Further, it is more preferable to use these oxides supported on an appropriate carrier. As the carrier, inorganic oxides such as silica, silica alumina, alumina, titania, silica titania, zirconia, and silica zirconia are preferable, and silica is particularly preferable. Furthermore, clay such as kaolin and talc may be added to increase the mechanical strength of the catalyst.
The atomic ratio of molybdenum and tin of the oxide catalyst X {Mo / (Sn + Mo); where Mo is the number of molybdenum atoms in the oxide catalyst and Sn is the number of tin atoms in the oxide catalyst . } Is in the range of 0 or more from the point of catalyst activity and less than 0.50 from the point of fluidity of the catalyst, more preferably in the range of 0.01 ≦ X ≦ 0.24, still more preferably 0. .05 ≦ X ≦ 0.24, particularly preferably 0.08 ≦ X ≦ 0.15.

In an actual fluidized bed reaction process, the fluidity of the catalyst is a very important factor in terms of operational stability. A catalyst having poor fluidity causes clogging of the catalyst in the piping and a single flow of the raw material gas.
In particular, when the reaction is carried out in such a manner that the catalyst described later is circulated between the fluidized bed reactor and the regenerator, this is an indispensable factor for stable operation.
Hereafter, the preparation method of the oxide catalyst used for this invention is described in detail.
The catalyst preparation mainly comprises 1) a catalyst raw material solution preparation step, 2) a raw material solution drying step, and a catalyst precursor calcination step.

1) Preparation process of catalyst raw material solution The chemical form of the raw material for forming molybdenum and tin oxides (hereinafter referred to as "oxide" also includes composite oxides) which are active species of the catalyst There is no limit. Preferably, a salt or a compound that forms an oxide at 200 to 1000 ° C. is used. For example, nitrate, sulfate, acetate, oxalate, ammonium salt, chloride, hydroxide and the like. Commercially available oxides can also be used as they are.
Usually, 1 or more types of raw materials are fully dissolved in water or a suitable solvent at 20-80 degreeC. At this time, in order to increase the solubility of the raw material, the liquidity of the solution may be controlled to be acidic or alkaline. In the case of poor solubility, hydrogen peroxide or the like may be added.
The raw material solution may be dried as it is, but it is preferably mixed well with powder, solution, sol, gel, etc. containing the carrier component so as to be supported on an appropriate carrier as described above.
At this time, when nitrate, sulfate, chloride, or the like is used as an oxide raw material, corrosive gas is generated in the subsequent firing step, so it is preferable to add ammonia water to convert it into a hydroxide. Further, in order to adjust the viscosity or the like, the liquid property of the mixed solution may be adjusted to be acidic or alkaline.

2) Catalyst raw material solution drying step / catalyst precursor firing step This step is performed by drying the catalyst raw material solution (hereinafter, the term “catalyst raw material solution” includes a carrier component) and drying the solvent. And a catalyst precursor is obtained, followed by a treatment such as calcination and conversion to an oxide catalyst.
There is no restriction | limiting in particular in the drying method of a catalyst raw material solution. The catalyst raw material solution can be sprayed and dried on vacuum-dried or heated plates. The dry powder is granulated into a spherical shape using a known granulation method. Industrially, drying by a spray dryer (hot air dryer) capable of simultaneous drying and molding is preferred. The spray dryer is a hot air dryer comprising a drying chamber, a raw material liquid spraying unit, a hot air intake / exhaust unit, and a dry powder recovery unit, and preferable spray drying conditions are to supply the catalyst raw material solution using a pump, Spray into the drying chamber using a rotary atomizer (centrifugal sprayer), pressurized nozzle, two-fluid nozzle (gas sprayer), etc. The sprayed droplets of the catalyst raw material solution are brought into contact with hot air controlled at an inlet temperature of 150 to 500 ° C. in countercurrent or cocurrent to evaporate the solvent and are recovered as a dry powder.

There is no particular limitation on the method for calcining the dried catalyst precursor thus obtained. Preferably, baking is performed at 400 to 1000 ° C. for 0.5 to 48 hours in an electric furnace under a flow of an inert gas such as nitrogen and / or an oxygen-containing gas.
Furthermore, in order to improve the dispersibility of molybdenum, it may be treated with water vapor at 150 to 500 ° C. for 0.5 to 48 hours before or after firing.
As will be described later, since the reaction of the present invention is carried out in a fluidized bed reaction format, the catalyst raw material solution is dried using a spray dryer to obtain a molded catalyst precursor, and while the oxygen-containing gas is circulated, A method of baking at ˜800 ° C. for 1 to 24 hours is particularly preferable.

Next, the method of the present invention will be described.
The method of the present invention is a reaction in which a raw material containing an alkene is brought into contact with an oxide catalyst in the gas phase in the presence of water vapor to produce a corresponding alcohol and / or ketone from the alkene.
Although the mechanism of the reaction is not clear, the inventors first generate an alcohol by a hydration reaction between an alkene and water vapor, and then generate the alcohol and gas phase molecular oxygen or solid phase oxygen (that is, oxidation). It is presumed that the lattice oxygen of the product catalyst undergoes an oxidative dehydrogenation reaction to produce a ketone.

The alkene contained in the reaction raw material is preferably propylene, 1-butene, 2-butene (cis and / or trans), pentene, hexene, cyclohexene, heptene, octene, cyclooctene and the like. More preferred are propylene, 1-butene, 2-butene (cis and / or trans) and cyclohexene, and particularly preferred is 1-butene and 2-butene (cis and / or trans). These may be used alone or in combination of two or more.
Gases inert to the reaction such as nitrogen gas, argon gas, carbon dioxide gas, methane gas, ethane gas, propane gas, and butane gas may be mixed and entrained as diluent gas and carrier gas in the reaction raw material.

The amount of water vapor relative to the alkene is 0.05 or more from the point of reaction rate and 10.0 mol or less from the point of effect, more preferably 0.2 to 5.0 mol, especially 1 mol of alkene. Preferably it is 0.5-2.0 mol.
Further, oxygen may or may not be present in the reaction raw material. As described above, the present inventors presume that when oxygen is not present in the gas phase, lattice oxygen of the oxide catalyst is used as an oxygen source for the reaction.
The amount of oxygen with respect to the alkene is preferably 0.0 to 0.5 mol, particularly preferably 0.0 to 0.3 mol, with respect to 1 mol of the alkene. As oxygen increases, the selectivity tends to decrease. 0.0 means that molecular oxygen is not supplied and lattice oxygen of the oxide catalyst is used for the reaction. Most preferably, this molecular oxygen is not supplied.

There is no restriction | limiting in particular in the supply amount (weight space velocity (WHSV)) of the alkene with respect to the catalyst. Preferably, a 0.01～10Hr ^-1, more preferably 0.05~5Hr ^-1. Most preferably, it is 0.1-2Hr- ¹ .
The weight space velocity (WHSV) is defined by the following equation.
WHSV (Hr ⁻¹ ) = alkene supply amount (Kg / Hr) / catalyst amount (Kg)
Although the reaction temperature has a preferable range depending on the raw material, it is generally preferably 130 to 500 ° C. More preferably, it is 200-450 degreeC, Most preferably, it is 230-350 degreeC. There is no restriction | limiting in particular in reaction pressure. Preferably it is 0.01-5 MPa, More preferably, it is 0.01-1 MPa, More preferably, it is 0.03-0.5 MPa, Most preferably, it is 0.05-0.3 MPa.

The reaction system used in the method of the present invention is a fluidized bed reaction system. Particularly preferably, the catalyst subjected to the fluidized bed reaction is continuously or intermittently extracted into a regenerator and regenerated in an oxygen-containing atmosphere, and then all or part of the catalyst is continuously or intermittently fluidized bed. This is a so-called catalyst circulation type fluidized bed reaction in which the operation of returning to the reactor is repeated.
FIG. 1 shows a schematic diagram of a fluidized bed reactor and a catalyst regenerator.
The catalyst circulation rate is determined so that the conversion rate is constant.
In the catalyst regeneration, regeneration treatment is performed in an atmosphere containing oxygen gas at a temperature and time required for catalyst regeneration. In particular, when the reaction for producing the corresponding alcohol and / or ketone from the alkene is carried out under the condition in which no molecular oxygen is present or in the condition having very little molecular oxygen, the lattice oxygen of the oxide catalyst is used as the oxygen source. Therefore, it is preferable because lattice oxygen can be replenished at the same time during catalyst regeneration.

From the reaction mixture containing alcohol and / or ketone obtained by the above reaction, alcohol and / or ketone can be recovered by known recovery, separation and purification operations such as cooling, distillation and extraction. Unreacted alkene can be separated from the reaction mixture and recycled as necessary to be used as a part of the reaction raw material.
For example, when manufacturing MEK from 1-butene and / or 2-butene, a reaction mixture is cooled and MEK and water vapor | steam are condensed. After gas-liquid separation, MEK is recovered from the condensate. All or part of the recovered water containing by-products such as acetic acid after recovering MEK is recycled again to the reactor as water vapor. The condensed gas phase is compressed and cooled to liquefy and recover MEK accompanying the gas phase, and unreacted 1-butene and / or 2-butene separates light gases such as carbon dioxide as necessary. Then, all or part of it is recycled to the reactor again.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to these examples.
The analysis equipment and analysis conditions used are described below.
(Reaction gas analysis)
Gas chromatography Shimadzu GC-17A, capillary column SPB-1 (φ0.25 × 60 m), INJ temperature 250 ° C., FID temperature 250 ° C., column temperature 40 ° C. × 10 min, 5 ° C./min temperature increase, 200 ° C. × 8 min hold ( Analysis of carbon dioxide and carbon monoxide in reaction gas)
Gas chromatography Shimadzu GC-8A, parallel column of PorapacQ (φ3 × 2m) and MS-5A (φ3 × 3m), INJ temperature 70 ° C., TCD temperature 70 ° C., column temperature 70 ° C. (catalytic chemical composition analysis)
EPMA (Scanning Electron Microanalyzer) X-650 manufactured by Hitachi, Ltd.

[Reference Example 1] (Preparation of catalyst A)
Dissolve 9380 g of stannic chloride pentahydrate in 60 L of pure water, add 3040 g of silica fine powder (trade name: Aerosil 200V manufactured by Nippon Aerosil Co., Ltd.), and stir at 500 rpm. It added until it became 5-7, and the white precipitation of a silica and a tin hydroxide was obtained. The white precipitate was filtered and washed thoroughly with pure water. An aqueous solution in which 660 g of ammonium molybdate was dissolved in 12.7 L of pure water was added to this cake to form a uniform slurry, and then concentrated nitric acid was added to adjust the pH of the slurry to 2-4. This slurry was spray-dried with a spray dryer to obtain a spherical shaped powder. The obtained compact powder was fired in an electric furnace at 650 ° C. for 1 hour in an air atmosphere. When the composition of this catalyst A was analyzed with an EPMA composition analyzer, it was 51% by mass of SnO ₂ , 7% by mass of MoO ₃ , and 42% by mass of SiO ₂ . The catalyst A had a Mo / (Sn + Mo) atomic ratio of 0.13, had a smooth spherical shape suitable for a fluidized bed catalyst, and had sufficient mechanical strength. An electron micrograph of catalyst A is shown in FIG.

[Reference Example 2] (Preparation of catalyst B)
Catalyst B having a different composition was prepared in substantially the same manner as in Reference Example 1. The composition of the catalyst B was 48% by mass of SnO ₂ , 11% by mass of MoO ₃ , and 41% by mass of SiO ₂ . The catalyst B had a Mo / (Sn + Mo) atomic ratio of 0.19, had a smooth spherical shape suitable for a fluidized bed catalyst, and had sufficient mechanical strength.

[Reference Example 3] (Preparation of catalyst C)
Catalyst C having a different composition was prepared in substantially the same manner as in Reference Example 1. The composition of the catalyst C was 65% by mass of SnO ₂ , 5% by mass of MoO ₃ , and 30% by mass of SiO ₂ . The catalyst C had a Mo / (Sn + Mo) atomic ratio of 0.07, had a smooth spherical shape suitable for a fluidized bed catalyst, and had sufficient mechanical strength.

[Reference Example 4] (Preparation of catalyst D)
Catalyst D was prepared in substantially the same manner as in Reference Example 1. The composition of this catalyst D was SnO ₂ 31% by mass, MoO ₃ 30% by mass, and SiO ₂ 39% by mass. The catalyst D had a Mo / (Sn + Mo) atomic ratio of 0.50, and the molded powder formed a lump and could not be fired uniformly. Precipitation of MoO ₃ crystals on the surface of the compact was observed by observation with an electron microscope.

[Reference Example 4] (Preparation of catalyst E)
Catalyst D was prepared in substantially the same manner as in Reference Example 1. The composition of this catalyst E was SnO ₂ 25% by mass, MoO ₃ 36% by mass, and SiO ₂ 39% by mass. The catalyst D had an Mo / (Sn + Mo) atomic ratio of 0.60, and the molded powder formed a lump and could not be fired uniformly. Precipitation of MoO ₃ crystals on the surface of the compact was observed by observation with an electron microscope. An electron micrograph of the catalyst E is shown in FIG.
For this reason, Mo / (Sn + Mo) is preferably less than 0.50 as a fluidized bed catalyst.

[Example 1]
Catalyst circulation in which the reaction and catalyst regeneration are continuously performed while the catalyst A is filled in a reaction apparatus comprising a fluidized bed reactor and a catalyst regenerator as shown in FIG. 1 and the catalyst A is circulated between the reactor and the regenerator. The fluidized bed reaction was carried out in the manner. The raw material at a ratio of 1-butene / water vapor / N ₂ = 20/40/40 (volume ratio) was supplied to the reactor at a weight hourly space velocity (WHSV) = 0.2 with respect to the amount of catalyst in the reactor. The reaction temperature was 250 ° C. The regenerator was fed a mixed gas of air and N _2. Table 1 shows a part of the result obtained by continuing the above reaction for about 10 hours.
Definitions are shown below. All are shown on a carbon basis.
Conversion of 1-butene and / or 2-butene = (F−L) / F × 100
Selectivity of each component (mol%) = P / (F−L) × 100
F: Feeded 1-butene and / or 2-butene amount (Cmol)
L: Unreacted 1-butene and / or 2-butene amount (Cmol)
P: amount of each component produced (Cmol)
Since 2-butene, which is a product of the isomerization reaction of 1-butene, can be reused as a raw material, it was treated as an unreacted product.
By-products in the table are CO ₂ , CO, acetone, acetic acid, butyl alcohol, oligomers having 5 or more carbon atoms, and the like.

[Comparative Example 1]
A fluidized bed reaction of the catalyst circulation system was carried out under substantially the same conditions as in Example 1 except that the catalyst E (outside the range of Mo / (Sn + Mo) of the present invention) was used. Table 1 shows a part of the result obtained by continuing the above reaction for about 10 hours.
From the comparison between Example 1 and Comparative Example 1, it is possible to stably produce the target substance with high selectivity by using a catalyst with good fluidity where Mo / (Sn + Mo) is 0 ≦ X <0.50. I understand.

[Example 2]
A fluidized bed reaction of the catalyst circulation system was carried out under substantially the same conditions as in Example 1 except that the catalyst B was used. Table 1 shows a part of the result obtained by continuing the above reaction for about 10 hours.

[Example 3]
A catalyst circulation type fluidized bed reaction was carried out under the same conditions as in Example 1 except that the catalyst C was used and WHSV was changed to 0.1. Table 1 shows a part of the result obtained by continuing the above reaction for about 10 hours.
In addition, even when the same reaction as in the example was performed by changing the alkene of the raw material from 1-butene to propylene and cyclohexene using the catalyst A, Mo / (Sn + Mo) was 0 ≦ X <0.50. It was confirmed that when a catalyst with good fluidity was used, the target substance could be stably produced with high selectivity.

  In the production method of the present invention, when the corresponding alcohol and / or ketone is produced from an alkene using an oxide catalyst in the presence of water vapor in the gas phase, the target substance is highly selective and the reaction process is stable. This is useful as the production method described above.

It is the schematic of the reactor and regenerator at the time of performing reaction of this invention by the fluidized bed reaction by a catalyst circulation system. 4 is an electron micrograph of catalyst A having Mo / (Sn + Mo) = 0.13 used in Example 1. FIG. 4 is an electron micrograph of catalyst E with Mo / (Sn + Mo) = 0.60 used in Comparative Example 1. FIG.

Explanation of symbols

a Catalyst extraction line b Catalyst recycling line

Claims (6)

A process for producing an alcohol and / or ketone corresponding to an alkene by reacting a raw material containing at least one alkene with an oxide catalyst in a gas phase in the presence of water vapor, A method for producing the above alcohol and / or ketone, which satisfies the requirements of a) and (b).
(A) The oxide catalyst contains molybdenum and tin oxide, and the atomic ratio of molybdenum to tin X {Mo / (Sn + Mo); where Mo is the number of molybdenum atoms in the oxide catalyst, and Sn Is the number of tin atoms in the oxide catalyst. } Is in the range of 0 ≦ X <0.50,
(B) The reaction is carried out in a fluidized bed reaction system. The method according to claim 1, wherein unreacted alkene, alcohol and / or ketone is recovered from the reaction mixture obtained by the reaction, and the unreacted alkene is recycled as a part of the raw material. The method according to claim 1 or 2, wherein the reaction is carried out by circulating between a fluidized bed reactor and a regenerator. The oxide catalyst contains an oxide of molybdenum and tin, the atomic ratio of molybdenum to tin X {Mo / (Sn + Mo); where Mo is the number of molybdenum atoms in the oxide catalyst, and Sn is the oxidation It is the number of tin atoms in the product catalyst. } Is in the range of 0.01 ≦ X ≦ 0.24. The method according to claim 1, wherein the alkene is 1-butene and / or 2-butene. The method according to any one of claims 1 to 5, wherein the reaction is carried out under conditions in which molecular oxygen is not supplied.