JPS6132302B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for synthesizing corresponding esters from nitriles. More specifically, it relates to a method for directly synthesizing a corresponding ester by reacting a nitrile with water and an alcohol. Esters, especially acrylic esters and methacrylic acid methyl esters, are extremely useful substances industrially. For example, acrylic esters are widely used in fibers, paints, adhesives, etc., and methacrylic esters are widely used as raw materials for synthetic resins. . Methods for synthesizing these carboxylic acid esters include methods for synthesizing them from nitrile; for example, when synthesizing acrylic acid esters from acrylonitrile, a liquid phase method in which acrylonitrile, alcohol, and sulfuric acid are reacted is generally used. This method involves first producing acrylamide sulfate from acrylonitrile, sulfuric acid, and water, and then adding alcohol to produce an acrylic ester, but it has the drawback that the reaction is divided into two stages. In addition, in this method, the sulfuric acid used is used in an amount equal to or more than the mole of acrylonitrile,
In addition, since highly concentrated sulfuric acid is applied at high temperatures, special consideration must be given to the material of the reactor. Furthermore, this reaction has problems such as a decrease in yield due to side reactions such as polymerization, and a large amount of economically inexpensive ammonium sulfate as a by-product. Recently, as a method to solve these problems, a method described in JP-A-51-25120 has been proposed in which acrylic acid ester is synthesized from acrylonitrile in one step in the gas phase using a catalyst containing boron trioxide. It was done. This method does not use sulfuric acid and catalytically reacts acrylonitrile, water, and alcohol in the gas phase to synthesize an acrylic ester in one step, so it is preferable in that there is no problem of ammonium sulfate by-products. The conversion rate to acrylic acid ester is low and the catalyst activity is not satisfactory. In view of these circumstances, the present inventors have conducted various studies on catalysts for the method of directly synthesizing the corresponding ester from nitrile, and have found that an oxide catalyst containing titanium, silicon, or a specific metal element as an active ingredient is suitable for nitrile synthesis. The present invention was achieved based on the discovery that the compound exhibits excellent activity for the conversion of from to ester. That is, the present invention provides a method for synthesizing esters that not only has a high conversion rate of nitrile but also has excellent selectivity to esters when nitrile is reacted with water and alcohol to directly synthesize the corresponding ester. This objective is achieved by using an oxide catalyst containing titanium, silicon, or a specific metal element as an active ingredient. The method of synthesizing the corresponding esters from nitriles according to the invention comprises converting a mixture of nitriles, water and alcohols into titanium and silicon or additionally silver, gold, magnesium, zinc, tin, lead, zirconium, vanadium, antimony, sutmus, chromium. , molybdenum, tungsten, manganese, iron,
It is characterized in that the reaction is carried out at a temperature of 100°C or higher in the presence of an oxide catalyst containing as an active ingredient at least one metal element selected from the group consisting of cobalt and nickel. In the method of the present invention, an oxide catalyst containing titanium and silicon or the above-mentioned specific elements as active ingredients is effectively used, but the preferred ratio of the active ingredients in the catalyst is 1 part titanium to 1 part silicon in an atomic ratio. 0.01-200, total amount of the above specific elements 0-10
The amount of silicon is preferably within the range of 0.01 to 80, and the total amount of the specific elements is preferably within the range of 0 to 7. The oxide catalyst used in the method of the present invention can be produced by any method known in this type of technical field. For example, in the case of a catalyst containing titanium, silicon, and nickel, titanium tetrachloride and ethyl silicon were added to water, and this aqueous solution was neutralized with aqueous ammonia to form a coprecipitate, to which nickel nitrate was added and mixed well. after,
It can be manufactured by molding and firing. As another method, it can also be produced by adding a nickel hydroxide precipitate obtained by neutralizing an aqueous solution of nickel nitrate to the coprecipitate, mixing well, and then molding and firing. Note that catalytic activity is improved by firing the catalyst in the method of the present invention, so the catalyst raw material composition prepared to the desired composition is finally heated at a temperature of 300°C to 750°C.
It is preferable to use it after baking for 0.5 to 48 hours. The catalyst may be formed into any shape such as spheres or pellets. Further, in the method of the present invention, the catalyst may be supported on a carrier.
As the carrier, for example, α-alumina, carborundum, etc. are used. The starting materials for each component constituting the catalyst can be selected from among many types, such as oxides, hydroxides, chlorides, nitrates, and organic acid salts of each component. Further, materials that can be converted into oxides or hydroxides by chemical treatment, firing treatment, etc. can also be used. Although it is not clear what form the catalyst components are in in the catalyst produced in this way, it is thought to be an oxide, various hydrated oxides, or hydroxides. In the present invention, such a catalyst is referred to as an oxide catalyst. The reactants in the process of the invention are nitrile, water and alcohol. Examples of the nitrile include various nitriles such as acetonitrile, propionitrile, acrylonitrile, methacrylonitrile, benzonitrile, glycolonitrile, and lactonitrile. Further, examples of the alcohol include various alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and ter-butyl alcohol, and the alcohol is selected from these alcohols depending on the desired ester. The reaction in the method of the present invention can be carried out by either a gas phase method or a liquid phase method, but the gas phase method is preferred. This method can be carried out by any method such as a fixed bed method or a fluidized bed method. The amounts of nitrile, water and alcohol subjected to the reaction can be varied within a wide range;
1 to 20 moles of water, preferably 1.5 to 10 moles
mol, alcohol is 1 to 10 mol, preferably 1 to 5
It is better to use moles. The reaction temperature is preferably 100°C or higher, preferably 150 to 400°C. If the reaction temperature is less than 100°C, the reaction rate is too low to be practical. The space velocity of the reactant gas is 10~
It is preferable to contact the catalyst at 10.000 hr ⁻¹ , preferably from 10 to 5.000 hr ⁻¹ . Although it is generally sufficient to carry out the reaction under atmospheric pressure, it can also be carried out under elevated or reduced pressure if necessary. In addition, during the reaction, it is sufficient to bring the reaction gas into contact with the catalyst under the conditions described above, but it is preferable to dilute the reaction gas with a gas that does not harm the reaction, such as an inert gas such as nitrogen, to suppress side reactions and prevent formation. It is good because it is effective in inhibiting polymerization of substances and improving conversion rate and selectivity. Hereinafter, the method of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited only to these Examples. The test method is as follows. Fill a reaction tube with an inner diameter of 17 mmφ with 50 ml of catalyst, and heat it to a predetermined temperature. A gas having the following composition is fed into the reactor at a predetermined space velocity. The reaction pressure is normal pressure. The reaction gas is analyzed and quantified using a gas chromatograph. Water/nitrile = 4 (mole ratio) Alcohol/nitrile = 3 (mole ratio) Nitrogen/nitrile = 5 (mole ratio) Preparation of catalyst The following catalysts 1 to 18 are the catalysts of the present invention, and 19 to 26 is a comparative catalyst for clarifying the significance of the present invention. Each catalyst was prepared as follows. Furthermore, assuming that the catalyst is in the form of an oxide, the experimental formula for the catalyst composition is shown. Catalyst 1 190 g of titanium tetrachloride was gradually added to 2000 ml of water. Next, ethyl silicate Si was added to this aqueous solution.
After adding 20.8 g of (OEt) ₄ and raising the temperature of the aqueous solution to 80°C, aqueous ammonia was added to neutralize it. The generated precipitate was separated and obtained, thoroughly washed with pure water, and then dried at 150°C for 10 hours. Next, water was added to this Ti/Si-containing dried material, mixed well, formed into pellets of 5 mm x 5 mmφ, and heated at 400°C.
It was baked for 4 hours. _The experimental formula for the composition of _this catalyst is Ti ₁ Si _0.1 O _2.2 . Catalyst 2 100 g of α-alumina and 150 ml of water were added as a carrier to a Ti/Si-containing dry product prepared from 19 g of titanium tetrachloride and 20.8 g of ethyl silicate by the same method as Catalyst 1, and after mixing well, a 5 mm×5 mmφ
The pellets were molded into pellets, dried and then fired at 500°C for 2 hours. The composition of this catalyst can be expressed as an empirical formula:
Ti _0.1 Si _{0.1 O 0.4 ・}(α _{− Al 2} O ₃ ). Catalyst 3 After adding 3.8 g of titanium tetrachloride to 300 g of silica sol (SiO ₂ content 20% by weight), aqueous ammonia was added to neutralize the mixture. This is then concentrated and
The resulting precipitate was separated, washed thoroughly with pure water, and then dried at 110°C for 8 hours. This Ti・Si
After adding water to the dry matter and mixing well,
The pellets were molded into 5 mm diameter pellets, dried and then calcined at 400°C for 4 hours. The composition of this catalyst can be expressed as an empirical formula:
Ti ₁ Si ₅₀ O ₁₀₂ . Catalyst 4 A Ti/Si-containing dry product was prepared in the same manner as Catalyst 1 using 19 titanium tetrachloride and 208.3 g of ethyl silicate. After dissolving 2.6 g of stannous chloride SnCl ₂ .2H ₂ O in 200 ml of water, this was neutralized by adding aqueous ammonia. The above Ti/Si-containing dry matter 68.1 is added to the generated slurry.
Add g, mix well while heating, and make a 5mm x 5mm
After molding into φ pellets, they were fired at 400°C for 4 hours. The composition of this catalyst can be expressed as an empirical formula:
Ti ₁ Si ₁₀ Sn ₁ O ₂₃ . Catalyst 5 190g of titanium tetrachloride and 208.3g of ethyl silicate
A Ti/Si-containing dried product was prepared in the same manner as for Catalyst 1. Ammonium tungstate 5 (NH ₄ ) ₂ 0.12WO ₃・5H ₂ O 26.1 g to 140 g of this dry material
After adding a small amount of water and mixing well, 5mm
The pellets were formed into pellets of 5 mm in diameter, dried, and then fired at 400°C for 4 hours. The composition of this catalyst can be expressed as an empirical formula:
Ti ₁ Si _{1 W 0.1} O _{4.3 .} Catalysts 6-14, 16-18 Catalysts 6-14 and Catalysts 16-18 were prepared in the same manner as Catalyst 5. The compositions of these catalysts and catalyst calcination conditions are shown in the table. As raw materials, Au is primary gold chloride, Mg is magnesium nitrate, Pb is lead nitrate, Zr is zirconium nitrate, Bi is bismuth nitrate,
Manganese nitrate was used for Mn, iron nitrate for Fe, cobalt nitrate for Co, nickel nitrate for Ni, silver nitrate for Ag, antimony trioxide for Sb, zinc nitrate for Zn, and chromium nitrate for Cr. Catalyst 15 4.5 g of vanadium pentoxide was added to 150 ml of an aqueous solution containing 3 g of oxalic acid and dissolved by heating. To this, 68.1 g of a Ti/Si-containing dried material prepared by the same method as Catalyst 1 and 1.8 g of ammonium molybdate (NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O were added and mixed well while heating, and then 5 mm The pellets were molded into 5 mm diameter pellets, dried, and fired at 600°C for 2 hours. _The experimental formula for the composition of this catalyst is Ti ₁ Si _{10 Mo 0.1} V ₁ O _24.8 . Catalyst 19 After concentrating silica gel (SiO ₂ content 20% by weight), the concentrate was formed into pellets of 5 mm x 5 mm diameter, dried and calcined at 500°C for 2 hours to obtain a SiO ₂ catalyst. Catalyst 20 Add water to silica/alumina powder (Al ₂ O ₃ content 26% by weight) and mix well, then 5 mm x 5 mm.
It was molded into φ pellets. After drying, this was baked at 500°C for 2 hours. _The experimental formula for the composition of _this silica-alumina catalyst is Si _2.4 Al _1.0 O _{6.3 .} Catalyst 21 Ammonium Tungstate 5
(NH ₄ ) ₂ 0.12WO ₃・5H ₂ 52.2g of silica/alumina powder as a carrier (alumina content 26% by weight)
Mix 100g, add water, mix well, form into pellets of 5mm x 5mmφ, and dry at 500℃.
The mixture was fired for 2 hours to obtain a WO ₃ -(SiO ₂ .Al ₂ O ₃ ) catalyst. Catalysts 22-27 Catalysts 21-26 supported on silica-alumina were prepared in the same manner as Catalyst 21. The composition of these catalysts and catalyst calcination conditions are as shown in the table. As raw materials, Mn is manganese nitrate, Fe is iron nitrate, Co is cobalt nitrate, Ni is nickel nitrate, and V
used vanadium pentoxide. Activity tests were conducted on the catalysts 1 to 27 using the test method described above. The results are shown in the table.

【table】

【table】

Claims (1)

[Claims] 1. A mixture of nitrile, water and alcohol,
Titanium and silicon, or at least one metal selected from the group consisting of silver, gold, magnesium, zinc, tin, lead, zirconium, vanadium, antimony, bismuth, chromium, molybdenum, tungsten, manganese, iron, cobalt and nickel. A method for synthesizing a corresponding ester from a nitrile, which is characterized by carrying out the reaction at a temperature of 100°C or higher in the presence of an oxide catalyst containing the element as an active ingredient. 2. The reaction is carried out in the presence of a catalyst in which the ratio of active ingredients in the catalyst is in the range of 0.01 to 200 silicon to 1 titanium in atomic ratio and 0 to 10 in total amount of metal elements. A method for synthesizing the corresponding ester from the nitrile described in Section 1.