JPS6154771B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an oxygen-containing organic compound (hereinafter simply referred to as an oxygen-containing compound) in which a gas containing carbon oxide and hydrogen is brought into contact with a rhodium-based catalyst. More specifically, the present invention selectively produces oxygen-containing compounds containing 1 and 2 carbon atoms by contacting a gas containing carbon monoxide and/or carbon dioxide and hydrogen with a specific rhodium-based catalyst. Regarding the method. BACKGROUND ART Conventionally, methods for producing hydrocarbons or oxygen-containing organic compounds and hydrocarbons from carbon oxide, particularly carbon monoxide and hydrogen (synthesis gas method: Fischer-Tropsch synthesis method) have been widely studied and industrially adopted. For example, the synthesis of carbon monoxide and hydrogen in the range of 4:1 to 1:4 at a temperature of 150 to 450°C and a pressure of 1 to about 700 atmospheres using a hydrogenation catalyst consisting of a metal from the iron group or noble metal group. Methods for synthesizing various oxygen-containing organic compounds and hydrocarbons from gases are known [F. Fischer, H. Tropsch, Ber,
59 , 830, 832, 923 (1926); H. Pichler, Adv.
Catalysis, 271 (1952)]. However, in this method, the product is a mixture of oxygenated compounds with 1 to 20 carbon atoms and hydrocarbons, and the product distribution has poor selectivity, making it possible to efficiently produce low-carbon oxygenated compounds useful as industrial raw materials. I can't. Regarding the selectivity of the reaction of a mixed gas of carbon monoxide and hydrogen, that is, synthesis gas, using a rhodium-supported catalyst related to this method, the rhodium-supported catalyst or rhodium A method has been proposed for producing methane and _C2 - _C4 hydrocarbons in a proportion not exceeding 10% by contacting them with metal plates [MAVannice,
J. Catal. 37 , 449 (1975), B. Sexton, GA:
See Somorjai, ibid, 46 , 67 (1977)). In addition, regarding the selectivity of low carbon oxygen-containing compounds in the synthesis gas reaction using a rhodium-supported catalyst, the CO/H ₂ ratio is made sufficiently larger than 1 under the conditions of 35 to 350 atm and 290 to 325°C. A method for producing oxygenated compounds, in particular a mixture of acetic acid, acetaldehyde and ethanol, with a carbon efficiency of 50% relative to the consumed carbon monoxide, by carrying out the reaction at a flow rate of at least 10 ³ h ^-1 SV value ( Belgian Patent
No.824822, DT2503233 and JP-A-51-
(Refer to Publication No. 80806), methanol and ethanol are produced with approximately equal carbon efficiency by carrying out a synthesis gas reaction at a flow rate of 10 ³ h ^-1 or more at 50 to 300 atmospheres using a silica-supported catalyst containing rhodium and iron. Method of
-Refer to Publication No. 80807) has been proposed. However, although these methods produce methanol and ethanol in equimolar ratios, they also produce significant by-products of methane and hydrocarbons with 2 or more carbon atoms, making it difficult to achieve a low CO concentration synthesis gas composition (CO/H ₂ = 1.0 or less), low pressure (1 to 50 atm), or low flow rate (SV value of 10 ³ h ^-1 or less), hydrocarbon by-products tend to further increase, and ethanol etc., which are useful as industrial raw materials, tend to increase. The selectivity for producing oxygen-containing compounds having 1 to 2 carbon atoms is significantly reduced. According to a catalyst improvement method in which manganese is added to rhodium (see JP-A-52-14706), although an improvement in the CO conversion rate per rhodium weight can be seen, the addition of manganese
It has been pointed out that the selectivity for oxygen-containing compound production is hardly improved, and that adding an excessive amount of manganese actually causes an increase in hydrocarbon production and reduces the selectivity for oxygen-containing compound production. Furthermore, rhodium clusters and platinum clusters already disclosed by the present inventors are added to the periodic table.
When using a catalyst supported on the oxide of at least one metal selected from ab, ab, and ab, a mixture of methanol and ethanol containing oxygen from synthesis gas under conditions of 1 to 50 atmospheres and 150 to 300°C. Methods for producing the compounds (see JP-A-54-41291 and JP-A-54-44605) are also known. Although the catalyst used in this method is highly active, the catalyst must be prepared using a special and expensive noble metal carbonyl cluster compound as a raw material, and must be prepared under an inert atmosphere (vacuum or in the presence of an inert gas). There is still room for improvement as a practical application process, as it involves the operation process. Rhodium is suitable for selectively producing oxygen-containing compounds having one or two carbon atoms, especially oxygen-containing compounds whose main product is ethanol, with high carbon efficiency under mild low-pressure reaction conditions in view of the prior art. The development of catalysts is desired as an alternative technology to methanol synthesis from synthesis gas or ethylene production from naphtha feedstock. The present invention has been made in view of the above-mentioned current situation, and as a result of multifaceted studies on the so-called co-catalysts or carriers to be combined with rhodium, which is relatively easily available, the present inventors have developed a specific component. The present invention was completed by learning a method of producing an oxygen-containing compound having 1 to 2 carbon atoms from carbon oxide and hydrogen with high selectivity in the presence of a composite catalyst. That is, an object of the present invention is to provide a method for producing an oxygen-containing compound having 1 to 2 carbon atoms with high selectivity through a catalytic reaction between carbon oxide and hydrogen. A method for producing an oxygen-containing compound that achieves the above object of the present invention involves producing an oxygen-containing compound by bringing a gas containing carbon oxide, ie, carbon monoxide, and/or carbon dioxide and hydrogen into contact with a catalyst. ) Rhodium, (b) titanium oxide, and (c) silica are used as catalysts. The catalyst of the present invention basically has (b) titanium oxide present on the surface of (c) silica as a carrier in the form of a physical mixture or partially or wholly in the form of a composite oxide. It is. Furthermore, when an organometallic compound of titanium is used as the raw material for (b),
This includes the case where silicon and titanium are in a fixed oxide state in which silicon and titanium are chemically bonded via oxygen due to a chemical reaction between these and the hydroxyl groups on the silica surface. And (a)
It is believed that rhodium is dispersed and supported in a substantially metallic state on a solid material consisting of titanium oxide and silica. Although it is not necessarily theoretically clear whether the component (b) acts as a cocatalyst for the rhodium in (a) or as a carrier component together with the silica in (c),
The composite oxide (hereinafter referred to as carrier) composed of (b) titanium oxide and (c) silica has a surface area of 10 to
Preferably it is 1000 m ² /g. The ratio of rhodium (a) to titanium oxide (b) is 10:1 by weight.
The ratio is preferably 1:10 to 1:10. The ratio of titanium oxide (B) to silica (C) is 10:1 to 10:1 by weight.
1:10 is preferred. The component (a) is 0.01 to 25% by weight, more preferably 0.1% by weight based on the weight of the catalyst.
~10% by weight. The method for preparing the catalyst is to impregnate a solution of an inorganic or organic metal compound of titanium dissolved in water or an organic solvent with silica (powder, pellet, lump, or granule) in a predetermined proportion to produce a carrier. After that, the solvent is removed, and titanium oxide is supported on silica by thermal decomposition in air or an inert gas (N ₂ , Ar, He or CO ₂ ) atmosphere, and optionally pulverized or granulated. . Examples of inorganic or organometallic compounds of titanium include their inorganic or organometallic salts such as chlorides, nitrates, carbonates, oxalates, acetates, acetylacetonates, metal alkoxides [general formula M(OR) ₄
In the formula, M represents Ti, R represents CH ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ or the like. ], dicyclopentadienyl [general formula
MCp ₂ X ₂ , where M represents Ti, Cp ₂ represents a dicyclopentadienyl group, and X represents halogen, hydrogen, CO, or the like. ], π-aryl metal complexes, arene metal complexes, and the like. To further specifically illustrate these compounds, titanium nitrate [Ti
(NO ₃ ) ₄・6H ₂ O], titanium oxyacetate [TiO
(CH ₃ COO) ₂ ], titanium oxychloride (TiOCl ₂ ), titanium tetrachloride (TiCl ₄ ), titanium acetate [Ti(CH ₃ COO) ₄ ], titanium ethoxide [Ti(OEt) ₄ ], titanium isopropoxy [Ti(isoPrO) ₄ ], titanium n-propoxide [Ti(n-PrO) ₄ ], titanium ptoxide [Ti(n-OC ₄ H ₉ ) ₄ ], dicyclopentadienyl titanium chloride (Cp ₂ TiCl ₂ ), dicarbonyldicyclopentadienyl titanium [CP ₂ Ti
(CO) ₂ ], titanium acetylacetonate [Ti
(acac) ₄ ] etc. Depending on the solubility of these titanium compounds, water and nonpolar or polar organic solvents such as methanol, hexane, benzene, and tetrahydrofuran are appropriately used as the solvent. The method of supporting rhodium (a) on the carrier is to impregnate a solution of the inorganic or organic metal compound in a solvent with a predetermined ratio of the carrier, remove the solvent, and then add hydrogen gas or synthetic gas. Performing a heat treatment in an atmosphere (for example, heating at a temperature of 150° to 500°C for several hours to several days) or a chemical ring-forming treatment to disperse and support the rhodium described in (a) above in a metallic form on the surface of the carrier. This is done by The chemical reduction treatment mentioned above can be performed using formaldehyde, hydrazine, hydride salts such as NaBH ₄ , LiAlH ₄ , NaH, KH
etc. Examples of inorganic or organometallic compounds of rhodium in (a) include inorganic or organometallic salts such as chlorides, nitrates, oxalates, acetates, acetylacetonate salts, dicyclopentadienyl complexes, π-aryl metal Examples include complexes and allene metal complexes. As a solvent, depending on the raw material compound, water, alcohol such as methanol and ethanol, hexane,
Non-polar and polar organic solvents such as benzene and tetrahydrofuran are mentioned. In addition to the above preparation method, (c) silica, (a) and
The component (b) can be added and impregnated sequentially or simultaneously, and after thermal decomposition, a heating hydrogen reduction treatment in a hydrogen stream can be performed directly. In carrying out the present invention, a closed circulation reactor,
After filling the above catalyst into a normal pressure and pressurized flow fixed bed reactor, mixing a mixed gas of carbon oxide and hydrogen at a predetermined mixing ratio, and introducing it under reduced pressure or increased pressure (1 to about 150 atmospheres), Contact is made at a space velocity of 10 to 10 ⁶ (/h ^-1 ), preferably 10 ² to ^{10 5} h ^-1 , and substantially 50
The reaction is carried out in a temperature range of ~450°C, preferably 100~350°C, and an oxygen-containing product containing ethanol as a main component is collected. Depending on the shape of the catalyst, it can also be applied to a batch reactor in which the catalyst is dispersed in a solvent. The mixing ratio of carbon oxide can be varied widely, usually carbon monoxide:hydrogen = 20:1 ~
The ratio is 1:20, preferably within the range of 5:1 to 1:5. These source gases may be diluted with an inert gas. In the present invention, the oxygen-containing compound having 1 to 2 carbon atoms refers to compounds such as methanol, ethanol, acetaldehyde, acetic acid, etc., but the present invention is characterized by the production of oxygen-containing compounds mainly using ethanol. There is. It is easy to distill and separate ethanol from the mixed oxygenated compound whose main product is ethanol obtained by the method of the present invention, and it is not only practical as a process for producing ethanol from synthesis gas, but also a potential future alternative fuel. It is expected that blending oxygen-containing compounds produced mainly from ethanol into fuel gas or gasoline will greatly help conserve petroleum resources. EXAMPLES Next, the present invention will be specifically explained by showing Examples, Reference Examples, and tables related thereto, but the present invention is not limited thereto in any way. The meanings of the terms in the table are as follows. SV: Feed gas (ml/h)/catalyst (ml) [h ^-1 ] Feed: Feed gas (ml/h) C ₁ : CH ₄ , C ₂ : C ₂ H ₄ +C ₂ H ₆ , C ₃ : C ₃ H ₆ +C ₃ H ₈ C ₄ :C ₄ H ₈ +C ₄ H ₁₀ Tr: Trace amount CE: Carbon efficiency of oxygenated compounds

[Table] Oxygen-containing compounds
Space-time yield of oxygen-containing compound [STY] (weight of oxygen-containing compound produced by kg of catalyst per unit time) = weight of oxygen-containing compound produced (g) / weight of catalyst (Kg) / time (h) Example 1 Titanium tetraiso Propoxide Ti (O-iso-
5.3 g of Pr) ₄ was dissolved in 100 ml of n-hexane, and 20 g of silica gel (Davison #57) was added and immersed in the solution. After distilling off the solvent, it is first dried in an air drying oven.
Heat treatment was performed at 200°C for 1.5 hours and then at 500°C overnight.
10 g of this carrier was immersed in a solution of 1.2 g of rhodium chloride dissolved in 100 ml of methanol to support rhodium. The solvent was distilled off using a rotary evaporator, and the mixture was dried and then filled into a Pyrex glass normal pressure flow reactor (φ18 x 500 mm). The top and bottom of the catalyst layer were filled with glass beads with a diameter of 2 mm. H ₂ (1
The temperature was gradually raised from room temperature while flowing gas (atmospheric pressure), and finally hydrogen reduction was performed at 350°C overnight.
The reaction is carried out using a mixed gas of CO and _H2 diluted with He (CO:
H ₂ :He=20:40:20 ml/min) was reacted by flowing at a total pressure of 1 atm, and the amount of oxygen-containing compounds and hydrocarbons produced at around 150 to 250°C was investigated. The main oxygen-containing compound is ethanol, and the others are methanol, acetaldehyde, acetic acid ester, and trace amounts of propyl alcohol and butyl alcohol. The outlet gas was then bubbled into 50 ml of distilled water (collector) every hour to absorb and trap the oxygenated compounds produced. Qualitative and quantitative analysis of the product was carried out using a Polapack Q-column (4 m, 200°C,
The analysis was performed using an FID gas chromatography analyzer (Shimadzu 7A) using a _N2 gas carrier). For calibration, acetone was used as an internal standard substance. Of the by-product hydrocarbons, methane, CO ₂ and CO were analyzed using activated carbon (1 m, r.
t) column; for _C2 - _C4 hydrocarbons, an _{Al2O3 -} DMF (38% wt loading) column (4
Qualitative and quantitative analyzes were performed using a TCD gas chromatography analyzer (Shimadzu 4B) using a 100-m, r-t). normal pressure
The performance of this catalyst in the CO-H ₂ reaction is shown in Table 1 below.
Complete analysis results, CO conversion, and conversion of the products shown in
It was demonstrated by the carbon efficiency (selectivity) of oxygenates on a CO basis and the selectivity of ethanol among oxygenates. Reference Example For comparison, normal pressure CO-H _{2 reaction activity was measured using 10 g of a hydrogen-reduced catalyst in the same manner as in Example 1, except that 1.2 g of rhodium chloride was supported on 10 g of silica gel (Davison #57} ) from a methanol solution. were investigated, and the results are also listed in Table 1.

【table】

[Table] As is clear from Table 1, the silica-supported rhodium catalyst containing titanium oxide has a marked increase in CO conversion activity and improved oxygen-containing compound selectivity, especially when compared to the silica-supported rhodium catalyst that does not contain titanium oxide. An improvement in selectivity was observed.

Claims (1)

[Claims] 1. In producing an oxygen-containing compound by contacting a gas containing carbon oxide and hydrogen with a catalyst, a catalyst comprising (a) rhodium, (b) titanium oxide, and (c) silica is used. Method for producing oxygen-containing compounds.