JPH03249943A - Methanol reforming catalyst - Google Patents

Abstract

PURPOSE:To obtain the catalyst having high activity and selectivity at low temp. and having a long service life by incorporating the oxides of >=1 kind among copper, zinc and chromium and nickel oxide into a porous carrier. CONSTITUTION:The oxides of >=1 kind among copper, zinc and chromium and nickel oxide are incorporated into a porous carrier to obtain the desired catalyst. Diatomaceous earth, alumina, silica, etc., are used for the porous carrier. An aq. soln. of the metal compds. and porous carrier is mixed with the hydroxides of alkali metal elements as a precipitant to form the precipitate, and the precipitate is dried and calcined to prepare the desired catalyst.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a methanol reforming catalyst, and more specifically, a method for producing hydrogen-containing gas using methanol or a mixture of methanol and water as a raw material. This invention relates to a highly active, highly selective, and long-life methanol reforming catalyst.

[Conventional technology]

In an effort to diversify fuels, methanol, which can be synthesized from fossil fuels other than crude oil, is attracting attention. 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 methanol decomposition reactions and steam reforming reactions.

The methanol decomposition reaction is as shown in the following formulas (1) and (2).

CHsOH-CD + 2L ΔH25℃= 21.7kcal/rnol
・(1) CHsO)1 + nl(20→ (2+n)L + (1-n)CD +nCL・(2) where 0<n<1 In addition, the methanol steam reforming reaction is expressed by the following equation (3). That's right.

CI(,DH1H,0→COa+3)! 2Δ825℃
= 11.8 kcal/mol ・(3) Conventional catalysts for reforming methanol include platinum metal elements such as platinum or base metal elements such as copper, nickel, chromium, and zinc and their oxides on a carrier such as alumina. Catalysts with supported ions have been proposed, but these catalysts have poor low-temperature activity and produce many dimethyl ether and methane by-products.
Until now, many problems remain.

In addition to the above-mentioned metal support method, there is also a precipitation method, and a typical example of a catalyst prepared by this method is a methanol reforming catalyst containing zinc, chromium, and even copper. .

However, although the above-mentioned catalyst has relatively high low-temperature activity, it still has the problem of poor heat resistance.

[Problem to be solved by the invention]

Conventionally, when decomposition or steam reforming reactions are carried out using methanol or a mixture of methanol and water as a raw material using the sensible heat of exhaust gas from engines, gas turbines, etc. as a heat source, the exhaust gas temperature ranges from 200°C to 700°C, as is well known. Because of this, it can be reformed over a wide temperature range with a small amount of catalyst that can be installed in internal combustion engines, and it is stable and does not deteriorate its reforming performance even if it is exposed to high temperatures of about 700°C as mentioned above. A catalyst is required.

Conventional catalysts for reforming methanol have been proposed using the aforementioned metal support method or precipitation method, but these catalysts lack low-temperature activity and are susceptible to thermal deterioration. Many problems remain.

[Means to solve the problem]

In order to solve the above problem, the present inventors previously discovered a catalyst consisting of an oxide or hydroxide of one or more of the group consisting of copper, zinc, and chromium and an oxide or hydroxide of nickel. , has already been proposed. (Tokuko Sho 62-4757
(No. 8) However, there was room for improvement in the heat resistance of this catalyst, so the inventors of the present invention conducted extensive experimental studies, and found that it was possible to improve the heat resistance of this catalyst, and as a result, the present inventors found that it was possible to improve the heat resistance of this catalyst. The inventors have discovered that a catalyst containing an oxide in a porous carrier has high activity and excellent selectivity in the methanol reforming reaction, and has a long life, leading to the present invention.

That is, the present invention is a methanol reforming catalyst comprising a porous carrier containing one or more oxides of the group consisting of copper, zinc, and chromium and an oxide of nickel.

Here, the porous carrier is diatomaceous earth, alumina, silica, titania, zeolite, etc., and has a specific surface area of 0.1.
〜500m''/g.

To prepare the methanol reforming catalyst of the present invention, a hydroxide or carbonate of an alkali metal element or an alkaline earth metal element is added as a precipitant to an aqueous solution of the above-mentioned metal compound and a porous carrier, either as is or in an aqueous solution. A method is used in which a precipitate is formed by mixing aluminum or alumonia water, followed by drying and firing.

The composition of the catalyst component of the present invention is Cub/Nip in the combination of one or more oxides of the group consisting of copper, zinc, and chromium and nickel oxide.

10/90-9 for ZnO/NiO, Cr2O5/NiO
A range of 0/10 (hereinafter expressed as molar ratio) is appropriate,
Particularly preferred is a range of 20/80 to 60/40. CuO
, ZnO.

In combination with two or more types of CuO
・ZnO, CuO・CrJs, ZnO・CrzOs
The ratio of ZnO to NiO is preferably in the range of 10:90 to 90:10, and in combination with CuO, ZnO, and CrzOs, the ratio to NiO is preferably 10:90 to 90:1.
A range of 0 is preferred.

The composition of the catalyst of the present invention is the above catalyst component (CuO.

The weight ratio of ZnO, a mixture of one or more of Cr2es and NiO) to the porous carrier is preferably in the range of 20+80 to 95:5, particularly preferably in the range of 40:60 to 80:20.

Note that methanol or a mixed solution of methanol and water as used in the present invention has a molar ratio of H20/CH,OH in the range of 0 to 100, and the reaction conditions for the methanol reforming reaction using the catalyst of the present invention are as follows. A pressure range of 0-50 is preferred.

〔Example〕 Hereinafter, the present invention will be specifically explained with reference to Examples.

[Example 1] 1 mol/j! copper, zinc nitrate aqueous solution, or 2 m
l mol/into each 11 aqueous solution of chromium nitrate in ol/β
! Aqueous solution 11 of nickel nitrate of
of sodium carbonate aqueous solution was added and mixed with stirring for 30 minutes. The resulting hydroxide precipitate was dried at 110°C, and then calcined at 300°C for 3 hours. (NiO/ZnO-based) catalyst 3 (NrO/Cr2
Ds system) was prepared.

Further, catalysts 4. each having a different composition using the same method as above.
5. 9 (NiO/CuO system), catalyst 6゜7 (N
1 (L ZnO system), catalyst 8 (NxO/CrJs system)
was prepared.

After subjecting the above catalysts 1 to 9 to water-hydrogen light treatment at 350°C for 12 hours, methanol (purity 99%) or a mixture of methanol and water (H20/CH, OH = 1, 0 mol/mol
l) as raw material, normal pressure, LH8V C liquid hourly space velocity) 5h-
', an activity evaluation test was conducted at a reaction temperature of 300°C. The results are shown in Table 1.

Table 1 The composition of the generated gas (mol 1% - dry paste excluding unreacted methanol, the same applies hereinafter) was as follows.

: 0.1-2%, CH, : 0.02-2% (2) Methanol/water temperature mixture raw material 1 (2: 66-71%, CO: 14-33%, C'[]
2200.5-14% C11, +0.01-1% [Example 2] Catalysts 10 to 13 shown in Table 2 were prepared in the same manner as in Example 1. After subjecting these catalysts to water-hydrogen light treatment at 350°C for 12 hours, a mixture of methanol and water (H20/CH
, DH = 2.0 mol/mol) as raw material, pressure 1
0kg/cdG, LH8V5 h-1, reaction temperature 250
Activity evaluation tests were conducted at ~350°C. The results are shown in Table 2.

The composition of the generated gas at each temperature was as follows.

(1) Reaction temperature 250°C, 300°C H,+: 68-72%, CO: 13-33%, CO: 1
~15%, CH,: 0.01~1% (2) Reaction temperature 3
50℃ Ha: 66-73%, CO: 8-33%, CO21-1
9%, CH,: 0.01-1% Furthermore, as a result of conducting a continuous test on the above catalyst for 1000 hours under the above reaction conditions (reaction temperature 350°C), the methanol conversion rate was constant at 100%.

[Example 3] In the preparation process of catalyst 1 in Example 1, alumina, silica, or zeolite powder (Y-type zeolite or offretite/erionite mixed crystal system Na-type zeolite) was used instead of diatomaceous earth as the porous carrier. Catalysts 14 to 18 (NiO:CuO50:50 molar ratio,
A porous carrier content of 50% by weight in the catalyst was prepared.

These catalysts were subjected to hydrogen reduction in the same manner as in Example 1, and then their activity was evaluated. The results are shown in Table 3.

Table 3 The composition of the generated gas was as follows.

(1) Methanol raw material Ha: 63-67%, Cal: 30-32%, CO2 0.5-3%, CH: 0.1-3% (2) Methanol/water mixture raw material Ha: 64-32% 71%, Cal: 14-32%, CD2:
1 to 14%, CH: 0.05 to 2% [Effects of the invention] As is clear from the results of the examples and comparative examples,
The methanol reforming catalyst of the present invention is an extremely excellent catalyst that has high activity, high selectivity, and long life at low temperatures in reactions that produce hydrogen-containing gas from methanol or a mixture of methanol and water as a raw material. .

Claims (1)

[Claims] A methanol reforming catalyst comprising a porous carrier containing one or more oxides of the group consisting of copper, zinc, and chromium and an oxide of nickel.