JPS6144847B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses iridium and molybdenum as a catalyst when producing lower alcohols such as methanol, ethanol, and propanol from synthesis gas (a mixture of carbon monoxide and hydrogen) in the presence of a catalyst.
Alternatively, the present invention relates to a method characterized in that a supported catalyst containing iridium, molybdenum and cobalt is used. Alcohols such as methanol, ethanol and propanol are valuable industrial products, and methods for producing them from synthesis gas are known. For example, the dino method uses an iron catalyst for ammonia synthesis to produce alcohols by reacting synthesis gas at a high space velocity at 8 to 25 atmospheres and a temperature of 190 to 225°C, and the dino method uses an iron catalyst to which a large amount of alkali is added. The oxyl method, which is a combination of the reaction used and the oxo method, has been known for a long time. Recently, a methanol synthesis method using a zinc oxide/copper oxide catalyst has also been implemented industrially. However, in the diol method and the oxyl method, the alcohol obtained is a mixture of a wide range of alcohols from C ₁ to C ₁₈ , and has poor selectivity.In addition, in the methanol synthesis method, the product is limited to methanol alone, and the product is a mixture of alcohols with a wide range of C 1 to C 18. and propanol are not produced. On the other hand, methods of synthesizing C ₂ oxygen-containing compounds such as ethanol using rhodium-based catalysts have recently been studied. For example, a method for producing C2 oxygen _- containing compounds using a rhodium catalyst (Japanese Unexamined Patent Publication No. 51-80806), a method for producing ethanol using a rhodium-iron catalyst (Japanese Unexamined Patent Publication No. 51-80807), rhodium/zirconium oxide / Methods for producing ethanol using a silica catalyst (Japanese Unexamined Patent Publication No. 147730/1983) are known, but rhodium, which is used as a catalyst in these methods, is produced in very small quantities among all metals and is expensive. Therefore, there is a strong desire to develop a relatively inexpensive and high-performance catalyst to replace these as an industrial catalyst. In general, various attempts have been made to combine two or more metals as a way to improve the activity and selectivity of solid catalysts containing metals as active components. It is extremely difficult to specifically find a suitable combination, as there are many cases in which the activity and selectivity of the reaction mixture decreases, and even in cases where the reaction is improved, the activity is only active at the initial stage of the reaction. The present inventors have conducted intensive research to develop a catalyst with improved selectivity in a method for producing lower alcohols such as methanol, ethanol, and propanol by reacting carbon monoxide and hydrogen. The present invention was completed based on the discovery that a supported catalyst containing iridium and molybdenum, or iridium, molybdenum, and cobalt as components exhibits high selectivity for the production of lower alcohols such as methanol, ethanol, and propanol. . The method of the present invention will be explained in more detail below. As mentioned above, the catalyst of the present invention is a catalyst that combines iridium and molybdenum or iridium, molybdenum, and cobalt, but although the true catalytic active species under the reaction conditions are not necessarily clear, the core of the activity is essentially Basically, they are metal species that coexist with each other, and therefore there are no restrictions on the form of the catalyst itself or the form of each component in the catalyst. Usually, the above catalyst components are used as supported. The catalyst used in the present invention is preferably prepared by impregnating a catalyst support with a solution of salts of iridium, molybdenum, and optionally cobalt, and then drying. At that time, these metal salts can be supported on the carrier simultaneously or sequentially. The metal salts include soluble salts,
For example, nitrates, halides, organic acid salts, ammonium salts, clusters, etc. are used, and the types thereof are not particularly limited. These metal salts are dissolved in a suitable solvent. Any solvent can be used as long as it dissolves the metal salt. After drying, the catalyst obtained as described above is subjected to a reduction treatment using a suitable reducing agent such as hydrogen. In this case, the reduction temperature is suitably in the range of 200 to 600°C. Furthermore, before the catalyst is subjected to the reduction treatment, it may be calcined with a suitable gas such as air, and the temperature at that time is suitably in the range of 200 to 600°C. In the catalyst of the present invention, the amount of each catalyst component used is not necessarily strictly limited, but the iridium content in the supported catalyst is 0.01 to 15% by weight, preferably 0.1 to 10% by weight, and the content of iridium in the supported catalyst is 0.01 to 15% by weight, preferably 0.1 to 10% by weight, The ratios of the components molybdenum, cobalt and iridium (Mo/Ir, Co/Ir) are each at an atomic ratio of 0.001~
5, preferably 0.1-2, 0.001-5, preferably
It is in the range of 0.1 to 2. The carrier used for this catalyst is 1 to 1000 m ² /g.
A carrier having a specific surface area of 2 is preferred, and silica, alumina, titania, thoria, activated carbon, zeolite, etc. are used, and silica-based carriers are particularly preferred.
These carriers can be used in any form such as powder or pellet. The reaction is usually carried out in the gas phase, for example, a raw material gas containing carbon monoxide and hydrogen is passed through a fixed bed reactor filled with a catalyst. In this case, in addition to carbon monoxide and hydrogen, the raw material gas includes carbon dioxide,
It may also contain other components such as nitrogen, argon, helium, water vapor, and methane. Further, the catalytic reactor is not limited to a fixed bed type, but may be of other types such as a moving bed type or a fluidized bed type. In some cases, a liquid phase reaction may also be carried out in which the catalyst is suspended in a suitable solvent and the raw material gas is passed therethrough. Although reaction conditions can be varied within a wide range,
The molar ratio of carbon monoxide and hydrogen is 30:1 to 1:10, preferably 10:1 to 1:5, and the reaction temperature is 100 to 450.
℃, preferably 150~350℃, pressure 1~
300atm, preferably 10~200atm, SV is 50~
A suitable value is 100,000 hr ^-1 , preferably about 100 to 10,000 hr ^-1 . Hereinafter, the present invention will be explained in more detail with reference to Examples, but these Examples are intended to facilitate understanding of the present invention, and the present invention is not limited to these Examples in any way. . In addition, the meanings of the terms in the table are as follows. CO reaction rate (%) = A-B/A x 100 A: Number of moles of carbon monoxide supplied B: Number of moles of recovered carbon monoxide Selectivity (%) = C x D/A-B x 100 C : Number of moles of the product D: Number of carbon atoms of the product A, B: Same meaning as above In addition, each symbol shown below means the following. MeOH...methanol, EtOH...ethanol, n-PrOH...n-propanol, CH ₄ ...
Methane, C ₂ ⁺ ……C ₂ or higher hydrocarbons, CO ₂ ……
carbon dioxide. Example 1 Iridium chloride _{( IrCl4.H2O} ) _1.92g , ammonium molybdate [( _{NH4 ) 6Mo7O24.4H2O ]}
Dissolve 0.5g in pure water to make 9.6ml, and add this solution to 8.00g of Dabilin #57 silica gel (12-20 mesh).
impregnated with. After standing for 1 hour, it was dried under reduced pressure using an evaporator at 80°C for 1 hour and at 110°C for 1 hour. Next, this was reduced at 500° C. for 3 hours in a stream of steam to prepare an iridium-molybdenum supported on silica catalyst. The supported amount is iridium 13.1
% by weight, and the mole ratio of molybdenum to iridium is 0.61. Take 1.68 g of the catalyst thus prepared, fill it in a high-pressure flow reactor, and add 6N of synthesis gas (carbon monoxide/hydrogen = 0.5).
The reaction was carried out by flowing at a flow rate of /hr (space velocity 1500hr ^-1 ). The reaction results are shown in Table 1 as Example 1. Comparative Examples 1 and 2 In the same manner as in Example 1, supported catalysts containing iridium alone and molybdenum alone were prepared, and the results of reacting these catalysts are also shown in Table 1 as Comparative Examples 1 and 2. A catalyst supported solely on iridium had a very low activity, and a catalyst supported solely on molybdenum had a low activity and the main product was hydrocarbons, but as shown in Example 1, a catalyst containing both iridium and molybdenum had no activity. It can be seen that there is a significant improvement and that alcohols such as ethanol and propanol are produced with good selectivity.

[Table] Examples 2 to 7 Catalysts were prepared and reactions were carried out in the same manner as in Example 1, except that the amount of iridium supported was fixed at 6.5% by weight and the amount of molybdenum supported was varied. The reaction results are shown in Table 2 as Examples 2 to 7.

【table】

[Table] Examples 8 to 10 The amount of iridium supported was fixed at 6.5% by weight, and the amount of molybdenum supported was varied, and the hydrogen reduction temperature was
The reaction was carried out in the same manner as in Example 1 except that the temperature was 300°C. The reaction results are shown in Examples 8 to 10.
It is shown in Table 3. Examples 11 to 13 Catalysts with fixed iridium loading of 6.5% by weight and varying molybdenum loading were tested before hydrogen reduction.
The reaction was carried out in the same manner as in Example 1 except that the air calcination treatment was carried out at 500° C. for 3 hours. The reaction results are also shown in Table 3 as Examples 11-13. Table 3 shows that lower alcohols can be produced in good yield even if the pretreatment conditions for catalyst preparation are changed.

[Table] Examples 14-21 1.79 g of iridium chloride (IrCl ₄ .H ₂ O) was dissolved in pure water to make 16.5 ml, and 15.00 g of Davison #57 silica gel (12-20 mesh) was impregnated with this solution. After being left for 1 hour, it was dried using an evaporator under reduced pressure at 80°C for 1 hour and at 110°C for 1 hour, and then reduced in a hydrogen stream at 500°C for 3 hours to obtain iridium supported on silica with a supported amount of 6.5% by weight. A catalyst was prepared. Next, 5.17 g of this catalyst was taken and ammonium molybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ .
4H ₂ O] was dissolved in pure water to make 5.5 ml and impregnated. After being left for 1 hour, it was dried under reduced pressure using an evaporator at 80°C for 1 hour and 110°C for 1 hour, and further subjected to reduction treatment at 500°C for 3 hours in a hydrogen stream to prepare a two-stage iridium-molybdenum supported catalyst.
The mole ratio of molybdenum to iridium is
It is 0.031-1.4. The results of reactions conducted using this catalyst are shown in Table 4 as Examples 14 to 21.

[Table] Examples 22-25 Contrary to Examples 14-21, the amount of molybdenum supported was 3.2
A two-stage supported catalyst was prepared in which iridium was added at a fixed % in advance and iridium was added later. The molar ratio of iridium to molybdenum is between 0.12 and 0.98. The results of reactions conducted using this catalyst are shown in Table 5 as Examples 22 to 25.

[Table] Example 26 Iridium chloride (IrCl ₄・H ₂ O) 0.60 g, ammonium molybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄・4H ₂ O)
0.030g, cobalt nitrate [Co(NO ₃ ) ₂・6H ₂ O]
Dissolve 0.049 g in pure water to make 6.0 ml, and add this solution to Davison #57 silica gel (12 to 20 mesh) 5.00 g.
It was impregnated with g. After standing for 1 hour, it was dried under reduced pressure using an evaporator at 80°C for 1 hour and at 110°C for 1 hour. Next, this was reduced at 500° C. for 3 hours in a hydrogen stream to prepare a silica-supported iridium-molybdenum-cobalt catalyst. The supported amount is 6.5% by weight of iridium, the molar ratio of molybdenum to iridium is 0.1, and the molar ratio of cobalt to iridium is 0.1. The results obtained using this catalyst are shown in Table 6 as Example 26. Examples 27 to 28 Iridium-molybdenum with different amounts of molybdenum and cobalt supported in the same manner as in Example 26
A cobalt-supported catalyst was prepared and the reaction was carried out. The results are also shown in Table 6 as Examples 27 and 28. Comparative Example 3 In the same manner as in Example 26, an iridium-molybdenum supported catalyst containing no cobalt was prepared and a reaction was carried out. The results are also shown in Table 6 as Comparative Example 3. From Table 6, it is clear that when cobalt is further supported on iridium-molybdenum, the yield and selectivity of alcohols are further improved.

[Table] Examples 29 to 31 Cobalt acetate [Co
An iridium-molybdenum-cobalt supported catalyst was prepared in the same manner as in Example 26 except that (CH ₃ CO ₂ ) _{2.4H 2} O] was used, and the reaction was carried out by changing the reaction temperature. The results are shown in Examples 29 to 29. It is shown in Table 7 as 31. The supported amount is 6.5% by weight of iridium, the molar ratio of molybdenum to iridium is 0.5, and the molar ratio of cobalt to iridium is 0.5.

【table】

Claims (1)

[Claims] 1. A method for producing lower alcohols from carbon monoxide and hydrogen, which comprises using a supported catalyst containing iridium and molybdenum as a catalyst. 2. A method for producing lower alcohols from carbon monoxide and hydrogen, which comprises using a supported catalyst containing iridium, molybdenum, and cobalt as a catalyst.