JPS632881B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a methanol catalytic cracking method for effectively producing hydrogen and carbon monoxide (hereinafter referred to as synthesis gas) using methanol as a raw material. (Prior Art) The catalytic cracking reaction of methanol is expressed by the following formula. CH ₃ OH→CO+2H ₂ ...() Equation () is the reverse reaction of the methanol synthesis reaction. In the past, when searching for a catalyst for methanol synthesis, Frolich et al. used methanol decomposition to test the catalyst instead of conducting a methanol synthesis experiment in order to get the results quickly. That is, when methanol is decomposed into CO and H ₂ , the decomposition rate is accelerated, and CO and H ₂ are
The experiment was conducted based on the idea that a catalyst that increases the yield of methanol can be used in methanol synthesis under pressure. As a result, ZnO−Cr ₂ O ₃ ,
CuO _{- Cr2O3} and ZnO- _{Cr2O3 -} CuO catalysts satisfied this idea. Therefore, it can be easily inferred that the methanol synthesis catalyst can be used for the catalytic cracking reaction of methanol. However, if conventional methanol synthesis catalysts are used as they are for decomposition reactions, the reaction temperature must be high to obtain the desired activity. (Objective of the Invention) The present invention was made against the background of conventional technical problems, and by applying an excellent catalyst with higher activity, the conversion rate of methanol to synthesis gas can be increased and CO ₂ can be reduced. The purpose of the present invention is to provide a methanol catalytic cracking method that produces fewer by-products. (Structure of the Invention) That is, the present invention involves heating methanol at 150 to 400°C in the presence of a catalyst containing copper, zinc, and vanadium as main components.
This is a methanol catalytic cracking method characterized by contacting at a temperature of . The present invention is based on CuO, which is a conventional methanol synthesis catalyst.
-The composition of the ZnO-based catalyst was changed and vanadium was added as a co-catalyst to further increase the activity, and a catalyst with excellent heat resistance and prevention of carbon deposition was adopted as the catalyst for methanol decomposition. As mentioned above, the catalyst in the present invention has copper, zinc, and vanadium as main components, and the copper component is metallic copper, CuO, or Cu ₂ O, the zinc component is metallic zinc, ZnO, and the vanadium component is metallic copper, CuO, or Cu 2 O.
V ₂ O ₅ can be mentioned, but in the present invention
_The combination CuOO-ZnO- _V2O5 is preferred. In the present invention, unless vanadium is added as a promoter to the copper-zinc catalyst, the activity will be low, the heat resistance of the catalyst itself will be insufficient, the catalyst life will be short, and the effect of preventing carbon precipitation will be low. The composition of copper, zinc and vanadium constituting the catalyst here is about 5 to 60% by weight as copper, preferably about 30 to 50% by weight, and about 5 to 60% by weight as zinc.
Preferably about 10-30% by weight, as vanadium
0.5-5% by weight, preferably about 2-3% by weight. If the copper content is less than about 5% by weight, the reaction rate will be slow, while if it exceeds about 60% by weight, the reaction rate will be slow. If the zinc content is less than about 5% by weight, the reaction rate will be slow, while if it exceeds about 60% by weight, the reaction rate will be slow. Furthermore, if vanadium is less than about 0.5% by weight, the effect of adding it as a co-catalyst will be poor, and the decomposition rate of the conversion reaction will be reduced, as well as the heat resistance of the catalyst itself will be reduced, and sintering will easily occur; Even if the amount is exceeded, the effect of addition as a co-catalyst will not be improved any further and the decomposition reaction will be hindered. Next, the methanol catalytic cracking method of the present invention is carried out in the presence of the copper-zinc-vanadium catalyst as described above, at a reaction temperature of about 150 to 400°C.
Preferably it is 200-320°C. In the catalyst system of the present invention, the reaction temperature is approximately 150°C.
Below 400°C, the reaction will not take place satisfactorily.
Exceeding this value may be advantageous in terms of equilibrium, but problems will arise in the heat resistance of the catalyst. The methanol catalytic cracking method of the present invention is affected by pressure, and the higher the pressure, the more disadvantageous it becomes. Therefore, it is desirable that the pressure be as low as possible. However, it is also possible to increase the pressure depending on the purpose of the generated synthesis gas. Further, the catalyst applicable to the present invention can be produced by a precipitation method, an impregnation method, an ion exchange method, a thermal decomposition method, a melting method, or a vapor deposition method according to conventional methods.
For example, as an example of a precipitation method, salts of metals constituting the catalyst (such as Cu(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ and
Add a precipitant (e.g. Na ₂ CO ₃ ) to an aqueous solution of NH ₄ VO ₃ )
After precipitating by adding an aqueous solution of and repeating filtration and washing, either as it is without molding, or after pressure molding or extrusion molding, dry at 60 to 200 °C, then calcined at 300 to 400 °C, as required. It can be obtained by grinding and adjusting the particle size according to the requirements. The ratio of CO and H ₂ in the synthesis gas obtained in the present invention is 1:2, but if you want to increase the ratio of H ₂ , you can add water to the raw material methanol and steam reform some or all of it. It is possible to vary the ratio of CO and H ₂ from 1:2 to 1:3. The present invention will be explained in more detail with reference to Examples below. Examples 1 to 4, Comparative Examples 1 to 2 Cu(NO ₃ ) ₂・3H ₂ O152g, Zn(NO ₃ ) ₂・
Dissolve 107g of 6H ₂ O in 2000ml of ion exchange water,
This is called liquid (i). Dissolve 6.7 g of NH ₄ VO ₃ in 100 ml of ion exchange water and use this as liquid (ii). Dissolve 212 g of Na ₂ CO ₃ in 2000 ml of ion-exchanged water and use this as liquid (iii). Liquid (i), liquid (ii), and liquid (iii) were each heated to 80°C and mixed with good stirring. After mixing, the mixture was stirred for about 2 hours, filtered, washed, and dried at 80°C for 12 hours. This was crushed and formed into a plate shape using a hydraulic press. This was fired at 300°C for 5 hours, and after firing, it was pulverized to have a uniform particle size of 16 to 32 meshes. Its composition is Cu: 39.9% by weight, Zn: 23.5% by weight,
V: 2.9% by weight, which is designated as catalyst A. 3 c.c. of Catalyst A was packed into a SUS316 reactor with an inner diameter of 19φ, and after reduction, the performance of the catalyst was examined by changing the reaction temperature under normal pressure. The results are shown in Table 1.

[Table] Comparative Example 1 is a case where the reaction temperature is below the lower limit, and the methanol decomposition rate is too low to be put to practical use. On the other hand, Comparative Example 2 is a case where the reaction temperature is above the upper limit, and the methanol decomposition rate is 100%. CO ₂ and
This is undesirable because it produces a large amount of CH ₄ as a by-product, and is also undesirable in terms of the heat resistance of the catalyst. Comparative Examples 3 to 7 A methanol synthesis catalyst manufactured by Company T (ZnO-Cr ₂ O ₃ catalyst composition: Zn 49.0% by weight, Cr 17.9% by weight) was pulverized into 16 to 32 meshes, and the performance was the same as in the previous example. I looked it up. The results are shown in Table 2.

[Table] Therefore, it can be seen that Catalyst A of the present invention exhibits superior activity particularly at low temperatures. (Effects of the Invention) As described above, according to the present invention, (a) the conversion rate of methanol to synthesis gas is high at low temperatures, and (b) the heat resistance of the catalyst used is further excellent, so that the range of applicable reaction temperatures can be improved. It has the advantage of increasing the catalyst life and significantly extending the life of the catalyst.

Claims (1)

[Claims] 1. A method for catalytic cracking of methanol, which comprises contacting methanol at a temperature of 150 to 400°C in the presence of a catalyst containing copper, zinc and vanadium as main components. 2 The catalyst is 5-60% by weight of copper and 5-60% by weight of zinc.
and 0.5 to 5% by weight of vanadium as a main component.