JPS6272501A - Method for decomposing methanol - Google Patents

Abstract

PURPOSE:To produce gas contg. CO by decomposing methanol stably for a long period with high activity at low temp. in the presence of water using a methanol decomposition catalyst. CONSTITUTION:Gas contg. CO is produced by decomposing methanol in the presence of 1-20mol water per 100mol methanol using methanol decomposition catalyst. If the amt. of water is <1mol per 100mol methanol, the effect of the added water is insufficient, insufficient effect for preventing deposition of carbon and for improving the life of the catalyst is obtd. If the amt. of water is >20mol, consumption of water or steam is increased and decomposed gas of high CO content is not produced. Preparation of a mixture of water with methanol may be executed by mixing methanol with water both being in the liquid state, or by mixing the vapor of methanol with steam.

Description

[Detailed description of the invention] Fields of commercial use> The present invention relates to a methanol decomposition method.

More specifically, methanol decomposition catalysts such as copper, zinc,
V Relating to a method for stably decomposing methanol over a long period of time in a method for producing carbon monoxide-containing gas by decomposing methanol using a catalyst containing one or more metals or metal oxides of the group consisting of In group metals 〇Conventional technology〉 Currently, in the chemical industry, there are
Crude oil and petroleum products refined from it are used as raw materials for carbon monoxide and mixed gases of carbon monoxide and hydrogen (oxo gas, etc.), but due to the recent rise in oil prices, raw materials are diversifying. methanol, which can be synthesized from fossil raw materials other than crude oil, is attracting attention as a raw material.

Furthermore, since methanol is decomposed into carbon monoxide-containing gas at a much lower temperature than naphtha, it has the advantage that waste heat can be used as a heat source for the decomposition reaction.

The decomposition reaction formula when water coexists with methanol is shown below (equation 0).

0H10H+nH10-+ (1-n) CO+(2
+n )H2+nc02 @-(1) Here, 0 (n
(1 In reaction (1), if n=o, Cu2O3→OO+211鵞−21,7
'Ih1l (2) If n = 1, 0130H+H
2O−+002 +! SH! -11.8 Kng (3) ・As the mouth becomes larger, the main metal content of CO decreases, and H
The molar ratio of 210O gradually becomes larger from 2.

In the chemical industry, which uses Cof, typified by alchemistry, the following synthetic reactions are carried out, for example.

Oxo reaction, ROI (=OH2+OO+H, →ROH2
・CH2・0HO(4) (e.g. R: alkyl group) Carbonylation reaction, 01 (30H+OO−+0H300
0H (5) In many cases, the gas required as a raw material has a H2/CO molar ratio of 0 to 1. Therefore, ideally, the reaction (2) that produces the largest amount of CO, i.e.,
The case where n=o is very satisfying.

Even in this case, hydrogen is removed from the cracked gas and H2
In order to obtain high-purity oxidized oxygen with a /CO molar ratio of 1 or less, a hydrogen separation step using a membrane or absorbent is usually required after the decomposed gas removal step. In internal combustion engines for power generation and automobiles, attention has been focused on increasing efficiency by improving the power of gas turbines, combined gas turbines/steam turbines, internal combustion engines, etc. using methanol decomposition. These n et al.
The aim is to achieve high efficiency by fully utilizing the endothermic reactions of reaction (2) and reaction (3).
The reaction is usually preferred.

As mentioned above, in industry, reaction (2), that is, n=
There are many fields that prefer to use case o.

Conventionally, catalysts for decomposing methanol (1) include catalysts in which platinum group elements such as platinum or base metal elements such as copper, nickel, chromium, and zinc or their oxides are supported on a carrier such as alumina, zinc, chromium, etc. For K, a catalyst containing one or more metals or oxides thereof from the group consisting of copper, zinc, and the VM-extended metal group, such as a copper-containing catalyst for methanol synthesis, has been proposed.

9. The inventors have developed a catalyst that has higher low-temperature activity than the conventionally known catalysts and is less likely to cause side reactions, and is based on oxides of one or more metals consisting of copper, zinc, and chromium. Fully supported or mixed nickel catalyst (Japanese Patent Application Laid-open No. 1983
7174138.174139), and a catalyst in which platinum or palladium is supported on a support of alumina coated with a basic oxide (Japanese Unexamined Patent Publication No. 57-68140) have already been proposed.

<Problems to be solved by the invention> However, when the above catalyst uses methanol as the only raw material, that is, when n=0, low-temperature activity is insufficient and carbon precipitation tends to occur, resulting in a short lifespan. There is a problem.

Is the purpose of the present invention to solve the problem '1' mentioned above? : We have solved the problem and provided a complete methanol decomposition method that suppresses the amount of carbon monoxide production as low as possible compared to the amount of carbon monoxide produced when methanol is the only raw material, has high activity at low temperatures, and has excellent durability. be.

Means for solving all the problems> In order to solve all the problems mentioned above, the inventors of the present invention have carried out extensive experimental studies and found that by adding 1 mol of water to 100 mol of methanol.
By decomposing methanol in the coexistence of water at a ratio of ~20 moles, it is possible to obtain a cracked gas with a high content of carbon monoxide, which is the target product, and which has high low-temperature activity and carbon content, which led to the present invention. Ta.

That is, the present invention is a method for decomposing methanol to produce carbon monoxide-containing gas in the presence of a methanol decomposition catalyst, characterized in that water is allowed to coexist with water at a ratio of 1 to 20 moles per 100 moles of methanol. This is a methanol decomposition method.

The methanol decomposition method of the present invention requires coexistence of water at a ratio of 1 to 20 moles with respect to 100 moles of methanol.
This is a characteristic feature.

The reason why the proportion of water and gold in coexistence is limited is that when water is less than 1 mole per 100 moles of methanol, the effect of adding 4 is small and the effect of preventing carbon precipitation and improving the overall durability is small. When the number of moles exceeds 20 moles, the disadvantage is that water or steam consumption increases, the target product, cracked gas with a high carbon monoxide content, cannot be obtained, and the normal steam reforming reaction ( C) 130H 10H20→5
H2+OO2, ΔH25℃= 11.8 Kcal/
mot)'s endothermic view Vr approaching, noon'MA filF
Prisoner II! M, n IJ-+(! 0-1- Z
I H, ΔTJ 7 'IT', = 21, 7 K(E
This is because it has the disadvantage that the advantage of increasing the calories of the generated gas is reduced compared to the amount of heat absorbed by the gas.

Methods for making water coexist with methanol include mixing it in the liquid stage and mixing methanol vapor with water vapor.

In addition, the anti-nuisance conditions of the present invention include 97c at a pressure of 0 to 50.
m”, temperature range of 150 to 600°C, methanol 100
It is preferable to coexist water at a ratio of 1 to 20 moles per mole of water, particularly preferably water to coexist at a ratio of 1 to 10 moles per 100 moles of methanol.

The methanol decomposition catalyst used in the present invention may be any known catalyst, and for example, a catalyst containing one or more metals from the group consisting of copper, zinc, and VItI group metals or oxides thereof is used. Examples include:

(1) A catalyst whose main components are oxidized steel and chromium oxide.
Furthermore, catalysts containing oxides of metals such as manganese and barium (Japanese Patent Publication No. 11274/1983) (2) Catalysts whose main components are copper oxide and zinc oxide, and catalysts containing chromium oxide (% Showa 57-174138
(Japanese Unexamined Patent Publication No. 151501/1989), catalysts further containing aluminum oxide, catalysts further containing aluminum oxide, manganese oxide, boron oxide, etc.
(3) Catalyst containing zinc oxide and chromium oxide as main components (4)
Friendly catalyst supported or mixed with nickel oxide based on oxides of one or more metals from the group consisting of copper, zinc, and chromium (Japanese Unexamined Patent Publication No. 57-174138.174139) (5) Support for alumina, silica, etc. Catalyst supported on oxidized steel pipe (JP-A-58-17836; Takezawa Nobutsune 1
Surface, vo420, No, 10 F, 55
5゜(6) Nine catalysts with nickel oxide, chromium oxide, and copper oxide supported on alumina (Japanese Patent Publication No. 58-46346)
．． 45286) (7) A secondary catalyst in which nickel and potassium are supported on alumina (JP-A-57-144031) (8) A secondary catalyst in which all platinum group metals are supported, for example, an oxide of a basic substance in advance of alumina gold A catalyst in which platinum and palladium are supported on a carrier coated with (LP5 1986-68140),
Catalyst with rhodium and potassium supported on solid alumina (
Water seal light-2 surface, vom 19, No. 9.
P, 515° or more is an example and does not particularly limit the present invention.

〔Example〕

Hereinafter, the methanol decomposition method of the present invention will be specifically explained with reference to Examples.

(Preparation of catalyst) An alumina carrier is immersed in a mixed aqueous solution of potassium nitrate and nickel nitrate at a predetermined composition ratio, dried, and then calcined at SOO°C.
A catalyst 1 was prepared in which 15% by weight of O, L) was supported.

Next, carbonic acid is added to a mixed water bath solution of nitric acid steel, zinc nitrate, and chromium nitrate at a predetermined acid ratio).
The precipitate produced by mixing with stirring was washed and dried at 350°C and then heated to 350°C.
Cub: molar ratio of zno:at-2o = 20:50
:5(lt-tokubun.

1g1l called the Adkins method!
In other words, a mixed bath solution of sodium dichromate and aqueous ammonia is added to an aqueous solution of copper nitrate, manganese nitrate is further added, and the precipitate formed by mixing well is washed, dried, and heated at 350°C.
(20uO:0r2)
03: MnO2 molar ratio = 10:10:, 1) Immersed in an aqueous solution of nickel nitrate as a t-carrier, dried, 500°C
Alumina carrier was immersed in an aqueous solution of calcium nitrate, dried and calcined at 550°C, and cut into alumina to prepare a carrier with a weight of CaO1-IQ supported. The carrier thus obtained was immersed in an aqueous solution of platinum nitrate, dried, and then calcined at 550°C to prepare 4 tons of catalysts supported with platinum ?l-α5 weight at 200°C. for 10 hours, 2 hours hydrogen flow (
Only catalyst 4 was reduced at 450° C. for 3 hours in a cumulative water stream) at a pressure of 15 KCf/cm2G.

Ll (BYC liquid space velocity) 1 h-', reaction temperature 2
Activity evaluation was performed at 70°C (640°C for catalyst 4 only) using methanol as the entire raw material.

In addition, various mixed liquids of methanol and water (57a=H20/
Molar ratio of CHSOH=0. [Lol, α05°α1. (12, (14)' is the raw material Toshitomo.

q! The reaction rate for r type conditions is shown in Table 1.

Only t1 methanol (S/
When decomposition is carried out at C=0), the reaction rate begins to decrease rapidly after about 1,500 hours, and after 2,500 hours, the reaction rate decreases to 50
Even though the reaction rate was accelerated by increasing the reaction temperature by 20°C, the catalyst did not recover to 8096 or higher, and the catalyst deteriorated significantly.

On the other hand, when a small amount of water is added to the methanol raw material, the decrease in reaction rate is suppressed even in the case of the catalyst of Isu, and the catalyst 3 has a reaction rate of 57
a=α05. Q.1. α2. Izun of α4 is also 4
A reaction rate of over 85% can be maintained even after 1,000 hours. However, when 510=α4, the amount of CO produced is small, and there is little practical advantage. Man, the reaction temperature is 10~
I decided to raise the temperature by 20℃ to speed up the reaction rate.
It has also been confirmed that the reaction rate can be recovered to 100%, and that unreacted methanol can be recycled to the reaction yarn and decomposed.

Table 2 shows the average amount (mol) of carbon monoxide and hydrogen produced per mol of methanol 10 hours after the start of the reaction. Regardless of the catalyst, there was no significant difference, so the average value was used. It was found that as the value of B/C increases, the amount of n,-carbon oxide produced decreases □

Claims (1)

[Claims] A methanol decomposition method for producing carbon monoxide-containing gas by decomposing methanol in the presence of a methanol decomposition catalyst, characterized by coexisting water at a ratio of 1 to 20 moles per 100 moles of methanol. .