JPS61232201A - Method for decomposing methanol - Google Patents

Abstract

PURPOSE:To obtain economically a hydrogen-containing gas which has a high octane number and burns cleanly without lowering activity for a long period, by decomposing methanol having water by the use of a catalyst containing a specific metal (oxide). CONSTITUTION:For example, an aqueous solution of copper nitrate is blended with a mixed aqueous solution of Na2Cr2O7 and NH4OH to form precipitate, which is washed, dried and calcined to give a catalyst containing one or more metals(oxides) selected from copper, zinc and a metal of group VIII of the periodic table, e.g., catalyst such as CuO.CuCr2O4, etc., consisting essentially of copper oxide and chromium oxide. Then, 100mol methanol is mixed with 1-99mol water and subjected to a decomposition reaction shown by the formula (0<n<1) at 0-50kg/cm<2> at 150-600 deg.C by the use of the catalyst to form a hydrogen-containing gas over a long period.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a methanol decomposition method.

More specifically, in a method of producing a hydrogen-containing gas by decomposing methanol using a catalyst containing one or more metals or metal oxides of the group consisting of copper, zinc, and metals in group 1, it is possible to increase the This invention relates to a method for decomposing methanol in a time-stable manner.

(Prior art) Currently, crude oil and petroleum products refined from it are used as raw materials for producing gaseous fuel in liquid fuel and reducing gas used in power generation boilers, internal combustion engines, etc., but the recent rise in oil prices Therefore, as fuels are diversified, methanol, which is synthesized from fossil fuels other than oil, is attracting attention as a raw material for producing these fuels and reducing gases.

Furthermore, since methanol is decomposed into hydrogen-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 when water is present in a ratio of 1 to 99 moles per 100 moles of methanol is expressed by the following formula (1).

CP[sOH+nhorse0→(2+n)Fh+(1,n)C
O+nC01'' (1) where O< n < 1 The cracked gas generated in reaction (1) has the advantage that the calorific value of the cracked gas increases by the amount equivalent to the endothermic amount of the cracking reaction, and furthermore, this generated gas has a high octane number. When applied to internal combustion engines with high output design, it has many advantages such as increasing the compression ratio and improving thermal efficiency, and enabling clean combustion without emitting formaldehyde when burning methanol. It can be used as a pollution-free fuel.

Furthermore, hydrogen can be separated from the cracked gas produced by reaction (1) above, and this hydrogen can be used as a fuel for fuel cell power generation and as a hydrogen source for hydrogenation reactions of various organic compounds in petroleum refining and chemical industries. Additionally, carbon monoxide can be separated from cracked gas and used as a carbon monoxide source.

Conventionally, catalysts for decomposing methanol 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, and K. Catalysts containing one or more metals of the group consisting of copper, zinc, and group (1) metals or their oxides, such as copper-containing catalysts for methanol synthesis, have been proposed. In addition, 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. Mixed catalyst (Japanese Unexamined Patent Publication No. 57
-174138.174139), a catalyst in which platinum and palladium are supported on alumina coated with a basic oxide (Japanese Unexamined Patent Publication No. 57-6
No. 8140) and other patent applications have already been filed.

<Problems to be solved by the invention> However, when the above catalyst uses only methanol as a raw material,
There are problems in that low-temperature activity is insufficient and carbon precipitation is likely to occur, resulting in a short life.

The object of the present invention is to solve the above-mentioned problems and to provide a methanol decomposition method that is highly active at very low temperatures and has excellent durability.

<Means for Solving the Problems> In order to solve the above problems, the present inventors have conducted extensive experimental studies and found that 100 moles of methanol is mixed with 1 part of water.
It was discovered that methanol can be decomposed in the coexistence of water at a ratio of ~99 moles, and has a long life due to high low temperature activity and no carbon precipitation, leading to the present invention.

That is, in a method of producing a hydrogen-containing gas by decomposing metapool using a catalyst containing a metal of -fi or higher in the group consisting of copper, zinc, and metals of group 1 or an oxide thereof, water is added to 100 moles of methanol. Provided is a methanol decomposition method characterized by allowing water to coexist at a ratio of 1 to 99 moles.

The methanol decomposition method of the present invention is characterized in that water is allowed to coexist at a ratio of 1 to 99 moles per 100 moles of methanol.

The reason for limiting the ratio of coexisting water is that if less than 1 mole of water is added to 100 moles of methanol, the effect of adding water to prevent carbon precipitation and improve durability is small. In addition, when water exceeds 99 moles, the usual steam reforming reaction (CH, OR + H, O → 5 Eh + c O
The endothermic amount is about the same as ``25℃=1t8kcat/mot), and the decomposition reaction (CH40H-+CO+21H
1.? This is because the advantage of increasing the calories of the generated gas is reduced compared to the endothermic amount of 5°C = 2t7kca7/mo7), and the disadvantage is that the amount of water or steam required is increased.

The method of making water coexist with methanol may be a method of mixing it in the liquid stage or a method of mixing water vapor with methanol vapor.

In addition, the reaction conditions of the present invention include pressures of 0 to 50, 97-
It is preferable to coexist water in a ratio of 1 to 99 moles per 100 moles of methanol at a temperature in the range of 150 to 600'C, particularly preferably in a ratio of 5 to 50 moles of water to 100 moles of methanol. It is to let

Catalysts containing one or more metals or oxides thereof from the group consisting of copper, zinc, and group (I) metals as used in the present invention include the following.

(1) Catalysts whose main components are copper oxide and chromium oxide, and also catalysts containing oxides such as manganese and barium (
(Japanese Patent Publication No. 54-11274) (2) A catalyst mainly composed of oxidized steel and zinc oxide, and further containing chromium oxide (Japanese Patent Publication No. 57-174158)
(Japanese Unexamined Patent Publication No. 151511), a catalyst further containing aluminum oxide, and a catalyst further containing fermented aluminum, manganese oxide, boron oxide, etc.
(3) Catalyst containing zinc oxide and chromium oxide as main components (
4) A catalyst in which nickel oxide is supported or mixed based on one or more oxides of the group consisting of copper, zinc and chromium (Japanese Patent Laid-Open No. 5
7-174158.174139) (5) Catalyst in which oxidized steel is supported on a carrier such as alumina or silica (JP-A-58-17elS6; Takezawa Nobutsune 2 surface, vom 20.mtOP, 555° (6) Catalyst with nickel oxide, chromium oxide, and copper oxide supported on alumina (Japanese Patent Publication No. 5B-46546, 45296) (7) Catalyst with nickel and potassium supported on alumina (Japanese Patent Application Laid-open No. 57-1440!51) (8) A catalyst supporting a platinum group metal, such as a catalyst in which platinum or palladium is supported on a carrier coated with an oxide of a basic substance (Japanese Unexamined Patent Publication No. 57-48140), or alumina. Catalyst supporting rhodium and potassium (Mizuno Hikaru-2
Surface, voL19. m9. P, 515.1?61
) The above are examples and do not particularly limit the present invention.

〔Example〕

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

Example 1 A preparation method called the Adkins method, that is, a mixed aqueous solution of sodium 11chromate and aqueous ammonia was added to an aqueous solution of nitrate steel, and the precipitate produced by mixing well was washed and dried. After 350℃
By firing at F), Catalyst 1 having a composition of CuO*CuCr104 was obtained.

The above catalyst 1 is v! When making 4, add glass a-'? Add 7 guns and get 1! Catalyst 2 made of Il (2CuO:Cr
Molar ratio of 30B:Mno==+10:10:1),
Add barium nitrate and p! Catalyst made by % 2CuO
:Cr103:BaO molar ratio=l O: 10:
1), and catalyst 4 prepared by adding manganese sulfate and palicum chromate (2CuO:Crzol:MnO
2: BaO molar ratio -10:10: (L5: cs
) was prepared in the same manner as Catalyst 1, and then a mixed aqueous solution selected from steel nitrate, zinc nitrate, aluminum nitrate, chromium nitrate, manganese nitrate, and an aqueous solution of sodium carbonate having a predetermined composition ratio were heated to 80°C, respectively. The precipitates produced by mixing with stirring were washed and dried, and then calcined at 350°C to obtain samples I & 5 to 9 having the compositions shown in Table 1. Catalyst again? Catalyst 10 was prepared in the same manner as Catalyst 9 except that zirconia powder was used in place of manganese nitrate.

Alumina support is immersed in an aqueous solution of nitric acid steel and heated to 700°C after drying.
The catalyst 11 carrying 51i of CuO (hereinafter, the supported amount is expressed as 100 on the carrier) was calcined with a silica carrier, and the silica carrier was ion-exchanged with an aqueous solution of ammine copper nitrate, dried, and then calcined at 350°C. Especially l) CuO 5
A weight percent supported catalyst 12 was prepared. The alumina support is immersed in a mixed aqueous solution of potassium nitrate and nickel nitrate with a predetermined composition ratio, dried and then fired at 500% to give NiO and 80%
1s of catalysts each carrying CLS weight% were ￥AFJt.
,Ta.

Immersing catalysts 2 and 4 as carriers in an aqueous solution of nickel nitrate;
After drying and calcination at 500° C., a catalyst 14.15 was prepared in which 2% by weight of NiO was supported.

The above catalysts 1 to 15 were reduced at 200°C for 10 hours (only catalyst 13 was at 400°C for 3 hours) in a 2 tlJ hydrogen stream, and the pressure was 1 s kg / 51" (), LH3v (liquid hourly hourly velocity) 1 h-12 reaction. Activity evaluation (after 10 hours and 2000 hours) using methanol as a raw material at a reactivity of 270°C was first performed as a comparative example, and a mixture of methanol and water (
Activity evaluation (after 10 hours and 2000 hours) was conducted under the same conditions as above except that H, o/c OH molar ratio = 11) was used as the raw material.

The results are shown in Table 1. The molar ratio of H,O/CH,OH is S/
Abbreviated as C.

The composition of the generated gas (excluding h and O) is as follows for any catalyst: 58 to 65% Co, and 28 to 32% in the case of a molar ratio of O/CH30H.

Co,: 1~b'4 tOther:2~12 Chi horse 0
/C Horse OH molar ratio α1: -: 63 to 69 thi, Co: 25 to 31 thi.

Co: 2-4%; Others: 2-51%.

Example 2 An alumina support was immersed in an aqueous solution of magnesium nitrate, calcium nitrate, paricum nitrate, potassium nitrate, or diphosphorous nitrate, dried, and calcined at 550°C to obtain alumina) #O
, Cab, Bad, KzO or L~01 at a weight of 10% by weight, respectively, were supported on carriers 1 to 5. The supports 1 to 5 thus obtained were each immersed in a platinum nitrate aqueous solution, dried, and then calcined at 550°C to prepare catalysts 16 to 20 (v4) carrying platinum (L5tf%).

Further, the carrier 2 was immersed in an aqueous solution of palladium or rhodium chloride, dried, and then calcined at 550°C to produce palladium.
A catalyst 22 supported at 5% by weight was prepared.

The activity was evaluated under the same conditions as in Example 1, except that the catalysts 16 to 22 were reduced at 450°C for 3 hours in a hydrogen stream and the reaction temperature was 540°C. The results are shown in Table 2.

The composition of the produced gas (excluding H and O) is as follows for any catalyst: When the molar ratio of H, O/C is 0, E! , : 59-65%, CO: 28-32%,
Cot:, 1-6%, Others: 2-101% When the molar ratio of O/C chicken OH is 11, H: 65-68%, CO: 27-52%, C
o,: 2-6 chi, others: 2-5 arrogant.

Example S Catalysts 7 and 14 of Example 1 were reduced at 200° C. for 10 hours in a 2% hydrogen stream at a pressure of 2 s, kg/y.

LH3'/1h, H at reaction temperature 300℃! O/CH30
Activity evaluations (after 10 hours and 4000 hours) were conducted using mixtures of methanol and water with different H molar ratios as raw materials.

The results are shown in Table 3.

<Effects of the Invention> As is clear from the results of the Examples and Comparative Examples, the methanol decomposition method of the present invention in which water coexists is an extremely excellent method with little decrease in activity even during long-term operation.

Sub-agent: 1) Akira Sub-agent Ryo Hagi Hara -

Claims (1)

[Claims] In a method for producing hydrogen-containing gas by decomposing methanol using a catalyst containing one or more metals of the group consisting of copper, zinc, and group VIII metals or their oxides, A methanol decomposition method characterized by allowing water to coexist at a ratio of 1 to 99 moles.