JPH02252602A - Method for reforming methanol - Google Patents

Abstract

PURPOSE:To stably obtain H2 containing gas at low temperature for a long time by reacting methanol with a O2-containing gas using a catalyst in which Pt and/or Pd is carried on a support containing oxides of alkaline earth element and rare earth element. CONSTITUTION:A support containing an oxide (e.g. MgO or CaO) of alkaline earth element and oxide (e.g. La2O3 or CeO) of rare earth element at an amount of each preferably 10-98wt.% and further containing alumina, thitania and other binder ingredient, etc., is prepared. Then Pt and/or Pd is carried on the support according to a method used from hitherto to prepare the desired catalyst. Methanol is reacted with O2-containing gas using the above-mentioned catalyst under the following conditions: reaction temperature, 100-600 deg.C; feed molar ratio of air to 1mol methanol, 0.1-5; feed molar ratio of water to 1mol methanol, 0.01-10; methanol feed amount l/h to 1l catalyst, 0.1-10.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for reforming methanol, and more specifically to a method for producing hydrogen-containing gas stably at low temperatures and over a long period of time by reacting methanol with an oxygen-containing gas. The present invention relates to a method for modifying methanol.

[Conventional technology]

Methanol can be produced on a large scale from coal, natural gas, etc. via synthetic gas, and is easy to transport, so in the future it will become an energy source that replaces petroleum.
It is of great interest as a raw material for various chemical industries.

One of its uses is to reform methanol into a hydrogen-containing gas and use this as a pollution-free fuel for automobiles or fuel for fuel cells.

[Problem to be solved by the invention]

As a reaction to produce hydrogen-containing gas from methanol,
Generally the following reactions are used.

CIbOH, -+CO+ 2H2■ CIIJH+ H20→C02+ 3H2■ Since the above reaction is an endothermic reaction, a heat source is required. Therefore, a multitubular reactor is generally used, and the heat of reaction is supplied by filling the reaction tube with a catalyst and passing a heat medium outside the reaction tube, which has the drawback of low thermal efficiency. Furthermore, in terms of thermodynamic equilibrium, in order to achieve a conversion rate of 95% or higher, the reaction temperature must be set to 250° C. or higher, which also poses the problem of a long start-up time.

As a method for solving the above problems, a modification reaction using the following partial oxidation reaction can be considered.

CH8 Kano +1/202 (+2N2) → CO2+2)12
(+2N2) ■CLO)I + 1/4 0
2+ 1/2 H-ObN2) → CO2+5/2
H2 (+N-) ■Also, JP-A-52-156194
In publications such as the following, the following partial oxidation reaction (■) and a catalyst for the reaction (a catalyst in which Ni, Cr, and Cu are supported on T-alumina) have been proposed; It was found that there were problems in that the catalyst was not very good and the catalyst lacked long-term stability.

CH30H+0.1502+0.6N, →! ,
65H2+0.75CO+0.1C112+0.15t
f20+0.15CO2+0.6N2 ■ [Means for solving the problem] Therefore, the present inventors developed reactions (1) and (2) in which the amount of H2 generated per 1 mo1 of methanol was 2 mo1 or more (in the above reaction (2), 112 1.65 mol) selectively,
We also developed a catalyst that allows the process to proceed at low temperatures. Specifically, we focused on the fact that side reactions can be suppressed by making the carrier basic, and as a result of various experimental studies, we found that platinum and palladium were added to carriers containing alkaline earth metal elements and rare earth element oxides. The present inventors have discovered that catalysts supported with noble metals, such as the following, have extremely excellent activity, selectivity, and durability in methanol reforming reactions (1) and (2), leading to the completion of the present invention.

That is, the method of the present invention is a method for producing a hydrogen-containing gas by reacting methanol and an oxygen-containing gas, in which platinum and/or palladium is supported on a carrier containing an oxide of an alkaline earth element and a rare earth element. This is a methanol reforming method characterized by using a catalyst prepared by the following methods.

Preferred reaction conditions in the methanol reforming method of the present invention are as follows.

Reaction temperature = 100-600°C, particularly preferably 200-600°C
500℃ Air supply molar ratio to 1 mole of methanol: 0.1 to 5
, particularly preferably 0.5 to 2. Molar ratio of water to 1 mole of methanol: 0.01 to 10, particularly preferably 0.
1-2 Catalyst II! methanol supply amount β/h: 0.1~
10, particularly preferably 0.5~Rare earth element oxides are oxides of rare earth elements in the Ma group of the periodic table, such as lanthanum oxide (La-L), cerium oxide (CeL), etc.
), neodymium oxide (NdzOa), or a mixture thereof.

Further, examples of oxides of alkaline earth elements include magnesium oxide (MgO), calcium oxide (Can), barium oxide (Bad), and mixtures thereof.

Here, the carrier containing an oxide of an alkaline earth element and an oxide of a rare earth element means at least 1% by weight or more, preferably 10 to 98% by weight of an oxide of an alkaline earth element and an oxide of a rare earth element. (Based on the total amount of one unit) This refers to a carrier that contains alumina, titania, zirconia, silica, and other binder components as substances other than alkaline earth element oxides and rare earth element oxides.

Examples include MgO, Can, one or more oxides of aO, LaJ*, CeO2, NdJs, Pr
One or more oxides of 5O++ and Al2O3,T
ie,.

There is a combination of one or more oxides of ZrO2, 5i02.

The preparation method is explained using the MgO-La2O5Al2O3 carrier as an example. (1) MgO, La20a powder is mixed with alumina sol. (2) An alkali is added to a mixed solution of an aqueous solution containing an Mg compound and an aqueous solution containing a La-containing compound to form a precipitate. (3) Add an alkali such as soda carbonate to the above mixed solution and an aqueous solution containing the compound to form a precipitate. After any of the above steps, drying and baking can be done easily. can be obtained.

Next, the method of supporting platinum and/or palladium on the carrier obtained in this way can be any conventionally used method, such as an aqueous solution of a compound such as a nitrate or chloride of these metals, or an ammine complex. After the carrier is immersed in the solution, it is calcined and further subjected to hydrogen reduction treatment to obtain a catalyst on which platinum and/or baradium is supported.

The supported amount of Pt and Pd (carrier layer weight) is 0.01 to 10
A weight percent range is preferred.

The catalyst obtained as described above has high selectivity and activity in the reaction of producing hydrogen-containing gas by reacting methanol with oxygen-containing gas, and has extremely excellent durability. It has the following.

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

[Example 1] Potassium hydroxide aqueous solution was added to a mixed aqueous solution of magnesium nitrate and lanthanum nitrate to form a precipitate, and then alumina sol was added and molded, dried and fired at 500°C to form MgO.
, MgO, La2O5, Al2O2 carriers with a weight ratio of La2O3 and Al2O3 of 70:20:10 were obtained.

The support thus obtained was immersed in an aqueous solution of tetraammine and platinum dichloride [chemical formula Pt (NH3) 4C12], dried, and then calcined at 500°C for 3 hours to obtain a catalyst with 0.5% platinum supported. 1 was prepared.

This catalyst was reduced at 400° C. for 3 hours in a 4% hydrogen stream, and an activity evaluation test was conducted under the conditions shown in Table 1, and the results shown in Table 2 were obtained. As a comparison catalyst, a conventional T-Δ120. Comparative catalyst 1 was prepared in which 0.5% by weight of platinum was supported on a carrier, and comparative catalyst 2 was prepared in which 18% by weight of Cu0, 9% by weight of NiO, and 3% by weight of CrJs (based on the carrier) were supported on the same carrier, and the reaction temperature was 300°C. The results of the activity evaluation test are also shown in Table 2.

Table [Example 2] The carrier shown in Table 3 was prepared in the same manner as Catalyst 1 prepared in Example 1, immersed in a chloroplatinic acid aqueous solution, and subjected to hydrogen reduction treatment to reduce the amount of platinum by 0.3 weight. Catalysts 2 to 6 were prepared in which the catalysts were supported at a concentration of 10%.

Regarding these catalysts, an activity evaluation test was conducted under the conditions shown in Table 1 except that the reaction temperature was 300°C, and the results shown in Table 3 were obtained.

An alumina support was immersed in an aqueous solution of cerium nitrate and calcium nitrate, and dried and fired to support CeO2 and Can at a concentration of 10% by weight (based on the total amount of the support).
-Can-AI20a carrier was immersed in dinitrodiammine platinum nitric acid acidic solution and subjected to hydrogen reduction treatment to give platinum concentrations of 0.1 and 0.3.

Catalysts 7 to 10 were supported to a concentration of 0.5.1% by weight, and the palladium concentration was 0.1° to 0.5% by weight in a similar manner.
Catalyst 13 was prepared by supporting catalysts 11 and 12 so as to have a platinum concentration of 0.3% by weight and a palladium concentration of 0.2% by weight.

An activity evaluation test was conducted on these catalysts under the same conditions as shown in Table 1, except that the reaction temperature was 300°C.
I got the result.

=8- A durability test for about 4000 hours was conducted on Catalyst 9, but no decrease in activity was observed.

〔Effect of the invention〕

As is clear from the above examples, by using the present invention, it is possible to stably produce a hydrogen-containing gas from a gas containing methanol and oxygen at a low temperature for a long time with good selectivity due to the hydrogen concentration. can.

Claims (1)

[Claims] A method for producing a hydrogen-containing gas by reacting methanol and an oxygen-containing gas, characterized by using a catalyst in which platinum and/or palladium is supported on a carrier containing an oxide of an alkaline earth element and a rare earth element. methanol reforming method.