JPH0541630B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing dimethyl sulfide from raw materials containing methanol and carbon disulfide. More specifically, the present invention relates to improvements in catalysts used in producing dimethyl sulfide from raw materials containing methanol and carbon disulfide. [Prior Art] A method for producing dimethyl sulfide by bringing methanol and carbon disulfide into contact with a catalyst at elevated temperature in a gaseous state has been known for a long time. For example, the method described in Japanese Patent Publication No. 7419 using a thorium oxide catalyst or an alumina sulfide catalyst;
There is a method described in the specification of No. 24652, etc. However, these conventional methods require a large amount of catalyst because the activity of the catalyst used is insufficient, and it is necessary to recover unreacted raw materials or reaction intermediates. There are many reaction by-products. These problems were not necessarily satisfactory. [Problems to be Solved by the Invention] An object of the present invention is to provide a catalyst having high activity and selectivity for efficiently producing dimethyl sulfide from methanol and carbon disulfide. [Means for Solving the Problems] The present invention provides SiO ₂ /
This is a method for producing dimethyl sulfide characterized by using a catalyst containing crystalline aluminosilicate zeolite having an Al ₂ O ₃ ratio of 8 mol/mol or more. In the present invention, crystalline aluminosilicate zeolite is used as a catalyst. As is well known in crystalline aluminosilicate zeolite, SiO ₄ tetrahedron and AlO ₄ tetrahedron are 0/(Si+Al)=
It has a structure in which a skeleton arranged in an atomic ratio of 2 (atomic ratio) is used as a base, and the negative charges generated from the skeleton are saturated with cations such as alkali metal ions. In this skeleton, there are pores of molecular size that communicate with the outside, and the shape and size of the pores vary depending on the type of crystalline aluminosilicate zeolite. The crystalline aluminosilicate zeolite used in the present invention has pores through which both methanol and carbon disulfide, which are raw materials, and ditotylsulfide, which is a product, can diffuse. Examples of such zeolites include offretite, zeolite L, mordenite, faugiasite, zeolite Ω, ZSM-5 described in Japanese Patent Publication No. 46-10064, and ZSM described in Japanese Patent Publication No. 52-16079. −12, Japanese Patent Application Publication No. 1983-
ZSM-20 described in Publication No. 80717, JP-A-Sho
Examples include pentasil type zeolite described in No. 58-91032. In the method of the present invention, a crystalline aluminosilicate zeolite having pores through which methanol, carbonized disulfide, and dimethyl sulfide can diffuse is used, and from the viewpoint of stability of catalyst activity, the SiO ₂ /Al ₂ O ₃ ratio is 8 mol. /mol or more of crystalline aluminosilicate zeolite is used. Particularly preferably used crystalline aluminosilicate zeolites include mordenite, ZSM-5, and the zeolite described in JP-A-58-91032. As described above, the crystalline aluminosilicate zeolite contains cations such as alkali metal ions, and these cations can be ion-exchanged. The method of the present invention does not limit the types of cations contained in the crystalline aluminosilicate zeolite; protons, alkali metal ions,
Alkaline earth metal ions and other metal cations are possible. Among these cations, alkali metal ions and alkaline earth metal ions are preferred from the viewpoint of reaction selectivity and stability of activity, and alkaline earth metal ions are particularly preferably used. Methods known to those skilled in the art of working with zeolites can be used to introduce the desired cations into the crystalline aluminosilicate zeolite. Usually, crystalline aluminosilicate zeolite is brought into contact with an aqueous solution containing a water-soluble salt of the cation or cation precursor 1 to 10 times at room temperature to 150°C for ion exchange, thereby converting the cation into crystalline aluminosilicate zeolite. Introduced into silicate zeolite. In the present invention, crystalline aluminosilicate zeolite is usually used as a molded body. The molding method is not particularly limited, and may include rolling method, compression method,
Known methods such as extrusion can be applied. It is also possible to add a binder such as alumina sol or clay if necessary during molding. Note that the ion exchange treatment can be performed at any stage before or after molding the crystalline aluminosilicate zeolite. This molded body is usually
It is activated and used as a catalyst by firing at 300-700℃. The present invention applies a feedstock containing methanol and carbon disulfide to the catalyst thus prepared.
This is a method for producing dimethyl sulfide by contacting it in the gas phase at ℃. A mixture of methanol and carbon disulfide is used as a raw material for the production of dimethyl sulfide used in the present invention. The mixing ratio of methanol and carbon disulfide is not particularly limited, but a stoichiometric ratio of methanol/carbon disulfide=4/1 (mol/mol) is preferred. If necessary, dimethyl sulfide, methyl mercaptan, hydrogen sulfide and/or carbonyl sulfide can be used as raw materials together with methanol and carbon disulfide. It is effective to add dimethyl ether, methyl mercaptan, hydrogen sulfide, and/or carbonyl sulfide, which are normally produced in small amounts as reaction by-products, to the raw material and recycle them to improve the economic efficiency of the process. In the present invention, the reaction temperature is 200-500°C, preferably 350-450°C. If the temperature is lower than 200°C, no reaction will occur, and if the temperature is higher than 500°C, many side reactions will occur, which is not preferable. In the present invention, the weight hourly space velocity of the feedstock is preferably 0.1 to 10.0 hr ^-1 , particularly 0.2 to 5.0 hr ^-1 based on the zeolite in the catalyst. Although the reaction pressure is not particularly limited, the reaction is usually carried out at a pressure close to atmospheric pressure. The reaction method can be carried out in the same manner as when using a conventional catalyst. It is recommended for convenience to use the fixed bed flow method. The present invention will be explained below based on Examples. [Example] Example 1 Na-type synthetic mordenite powder (SiO ₂ /Al ₂ O ₃ =
10mol/mol) in terms of Al ₂ O ₃
Add 15wt%, knead, extrude into 1mmφ noodles, tumble granulate, and bake in air at 550℃ for 2 hours.
A Na type model night catalyst was obtained. Using this catalyst, carbon disulfide and methanol mixed raw materials were reacted in the gas phase using a glass fixed bed flow reactor with an inner diameter of 26 mm. The reaction conditions are shown below. Feed liquid composition: carbon disulfide/methanol = 1/
4mol/mol WHSV (zeolite standard): 0.28hr ^-1 Reaction temperature (highest part): 400℃ Reaction pressure: Atmospheric pressure When the reaction product was analyzed by gas chromatography, the dimethyl sulfide production rate was 91.9mol
It was %. Dimethyl sulfide production rate = dimethyl sulfide production amount (mol/hr)/carbon disulfide supply amount (mol/hr) x 2 x 100 Comparative example Activated alumina "Neobeat C" manufactured by Mizusawa Chemical Industry Co., Ltd.
-5" was crushed into 14 to 32 meshes, and the reaction was carried out under the same conditions as in Example 1. Analysis of the reaction product by gas chromatography revealed that the dimethyl sulfide production rate was 83.3 mol based on the carbon disulfide starting material. Example 2 A Na-type mordenite granulated calcined product prepared in the same manner as in Example 1 was ion-exchanged eight times using a 10wt% calcium chloride aqueous solution (solid-liquid ratio 2.0/Kg, at about 90°C). A Ca-type mordenite catalyst was obtained by thoroughly washing with water, drying, and calcining in air at 550°C for 2 hours. Using this catalyst, a reaction was carried out under the same conditions as in Example 1. The reaction product was analyzed by gas chromatography. Analysis revealed that the dimethyl sulfide production rate was
It was 92.5 mol%. Example 3 White according to the specification of JP-A No. 58-91032.
An aqueous mixture consisting of 66.0 g of carbon (hydrated silicic acid), 17.47 g of sodium aluminate, 9.22 g of caustic soda, 12.5 g of tartaric acid, and 344.2 g of water was crystallized by keeping it at 160°C for 72 hours to determine the SiO ₂ /Al ₂ O ₃ ratio. 25.2mol/
mol of zeolite powder was synthesized. To this zeolite powder, 15 wt% of alumina sol was added in terms of Al ₂ O ₃ , and after kneading, it was extruded into noodles of 1 mm diameter, and after rolling granulation, it was calcined in air at 550° C. for 2 hours to obtain a Na-type zeolite catalyst. The reaction was carried out under the same conditions as in Example 1 using this catalyst. When the reaction product was analyzed by gas chromatography, the dimethyl sulfide production rate was 92.4 mol%.
It was hot. Example 4 A granulated calcined Na-type zeolite product prepared in the same manner as in Example 3 was ion-exchanged 8 times using a 10wt% calcium chloride aqueous solution (solid-liquid ratio 2.0/Kg, at about 90°C), and thoroughly washed with water. After drying, it was calcined in air at 550°C for 2 hours to obtain a Ca-type zeolite catalyst. In a similar manner, ion exchange was performed using a 10 wt% strontium nitrate aqueous solution and a 10 wt% barium nitrate aqueous solution to obtain Sr type zeolite and Ba type zeolite catalysts. The test was carried out under the same conditions as in Example 1 for each of the above three types of catalysts. The results are shown in the table below.

〔Effect of the invention〕

methanol and carbon disulfide at elevated temperature,
When producing dimethyl sulfide by contacting it with a catalyst in the gas phase, the catalyst containing the crystalline aluminosilicate zeolite according to the present invention has higher dimethyl sulfide production activity and selectivity than conventional catalysts, Moreover, it maintains this high activity and selectivity for a long time. Therefore, according to the method of the present invention, dimethyl sulfide can be obtained in high yield with few by-products, and only a small amount of catalyst can be used.

Claims (1)

[Claims] 1. When producing dimethyl sulfide by contacting a feedstock containing methanol and carbon disulfide with a catalyst in a gas phase at 200 to 500°C, SiO ₂ /Al ₂ O ₃
A method for producing dimethyl sulfide, characterized by using a catalyst containing crystalline aluminosilicate zeolite having a ratio of 8 mol/mol or more. 2. The method according to claim 1, wherein at least some of the exchangeable cations of the crystalline aluminosilicate zeolite are alkaline earth metals.