JPS5870839A - Catalyst for steam reforming of methanol - Google Patents

Abstract

PURPOSE:To obtain a catalyst excellent in low temp. activity, as the catalyst for steam reforming of methanol, by using one having a magnesium compound contained in a copper compound. CONSTITUTION:As a copper type catalyst for steam reforming of methanol, one obtained by containing a magnesium compound such as magnesium oxide or magnesium carbonate in a copper compound such as copper nitrate or copper sulfate is used. Thus obtained catalyst is high in a methanol conversion ratio at a relatively low temp. and reduces the generation of CO as a byproduct.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalyst for the steam I)7ohming of methanol to obtain hydrogen.

-Currently, hydrogen, which is used in large quantities in the chemical industry, is mostly produced by steam reforming of naphtha or natural gas. On the other hand, the method of producing hydrogen by steam reforming methanol has the following advantages: steam reforming is possible at relatively low temperatures, methanol is easy to store and handle, and high purity hydrogen is easy to obtain. It has attracted attention in recent years.

The steam reforming reaction of methanol is formally represented by equation (1). 'CH30H+H2O--
→C6□+3H2... (1) Also, major side reactions include (2) and the by-product of carbon monoxide represented by the following formulas: (2) (3).

As is clear from equation (2), the by-product of -carbon oxide is undesirable because it reduces the amount of hydrogen produced.

However, depending on the use of hydrogen, for example, as raw material hydrogen for fuel cells, the presence of carbon monoxide may be undesirable, and in such cases it is necessary to strictly limit the amount of carbon monoxide by-product. Therefore, methanol steam reforming catalysts are generally required to produce less carbon monoxide as a by-product. The reaction of equation (2) above is well known as the carbon monoxide shift reaction, and the lower the temperature, the more favorable the equilibrium is for the production of hydrogen. Therefore, in order to suppress the by-product of carbon oxide, steam refrigeration of methanol is It is desirable that the ohming catalyst has sufficient activity at as low a temperature as possible.

Also, from the point of view of the energy required for preheating the raw materials,
Low reaction temperatures are advantageous.

It is known that catalysts such as copper-zinc, copper-zinc-chromium, copper-chromium, copper-chromium-manganese-zinc, zinc-chromium, and zinc-cobalt-chromium are active in the methanol steam reforming reaction. be. Among these, copper-based catalysts, especially copper-zinc catalysts, have steam reforming activity at low temperatures, but in order to improve the economic efficiency of the hydrogen production process, there is a need to develop catalysts that are active at even lower temperatures. .

As a result of improving copper-based catalysts for methanol steam reforming reactions, the present inventors discovered that a catalyst containing a magnesium compound in a copper compound has excellent low-temperature activity. completed.

That is, the present invention is a methanol steam reforming catalyst characterized by having a copper compound and a magnesium compound.

The catalyst of the present invention contains a copper compound and a magnesium compound, and the content ratio of the copper compound and magnesium compound in the catalyst is 2 in terms of copper:magnesium atomic ratio.
=98-98:2.

The ratio of copper and magnesium 20 in the coprecipitated or kneaded catalyst is 1 to 5Q wt%, preferably 2 to 20 wt%, as a weight proportion of magnesium oxide calculated as /(Cu○+M20). The copper compound and magnesium mixture may be supported on a carrier such as alumina, silica-alumina, silica, titania, zirconia, cordierite, or mullite, if necessary.

The catalyst of the present invention can be prepared by a known catalyst manufacturing method. Generally, it is obtained by mixing an aqueous solution of a copper salt and a magnesium salt with a neutralizing agent, and washing the resulting precipitate with water, drying, and calcining. Raw material copper salts include nitrate,
Sulfates or various water-soluble organic acid salts are used. The use of chloride is not preferred because those prepared from chloride have low activity. As the raw material magnesium salt, nitrates and various water-soluble organic acid salts are used. As the neutralizing agent, alkali metal hydroxide, alkali metal carbonate, aqueous ammonia, ammonium carbonate, urea, etc. are used. The firing temperature is appropriately selected within the range of 200 to 500°C.

In addition to the above method, the catalyst of the present invention can also be obtained by a method in which a preformed magnesium compound carrier such as magnesium oxide, magnesium carbonate, magnesium hydroxide, etc. is impregnated with an aqueous copper salt solution. In the case of the impregnation method using a magnesium carrier, unlike the above coprecipitation method, MrO/(
The weight/proportion of magnesium oxide calculated as (Cuo-4-MfO) is preferably 70 to 96 wt%.

The catalysts of the present invention are typically oxides, but can also take the form of other compounds. When the calcination temperature is set low, raw materials such as nitrates and sulfates constitute the undecomposed catalyst, but such materials may be used.

The catalyst of the present invention is applied to a methanol steam reforming reaction in a gas phase, a flow system. The reaction temperature is 15
0~4oo℃, reaction pressure 0~10Kg/c17fG1
The water-to-methanol molar ratio is 1:
1 to 5:1, raw material supply rate is 5 to 500 hr/Ky-mol -) p 7
- preferably 10 to 200"hrAV-mo
I-methanol.

The catalyst of the present invention is characterized in that it has a higher methanol conversion rate at a relatively low temperature of 150 to 250 °C and produces less CO as a by-product compared to known catalysts, but it cannot be used at a relatively high temperature of 300 to 400 °C. Of course, it is also possible to do so.

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

Example 1 Aqueous sodium carbonate solution was added dropwise to a solution of nitrated copper trihydrate 273.3 fI and magnesium nitrate hexahydrate 6662 dissolved in 500 cc of water, and the resulting precipitate was washed with water, filtered, and washed with water.
After drying, it was calcined in air at 30[]°C for Ihr. The resulting composition containing 90 wt% CuO and 10 wt% MfO was pulverized and formed into a cylindrical tablet with a diameter of 6 mm.

Fill a reaction tube with an inner diameter of 24 mm with the shaped catalyst at 5° crd, and supply methanol-4) 1.0 mol e/
A methanol steam reforming test was conducted at normal pressure under the conditions of hr. Reaction temperature is 15o, 175.2
Measurements were made at three points at 00°C. H21, CO' in generated gas
Analysis of tCO2 and methanol and water in the reactor outlet condensate was performed using gas chromatography.

Co concentration and methanol conversion rate are Calculated by. The results are shown in Table 1.

Example 2 Mf
O content is 0.1.2,5.2'0°30.40,50.
60 and ioo catalysts were prepared. These catalysts were tested for activity in the same manner as in Example 1. The results are shown in Table 1.

Comparative example 1 CuQ 61 wt%, Zn033 wt% and At20
Example 1 A commercially available methanol synthesis catalyst consisting of 36 wt%
The activity was tested in the same manner. The results are shown in Table 2.

Comparative Example 2゜Magnesium nitrate hexahydrate was replaced with zinc nitrate hexahydrate 6652
The same method as in Example 1 was used except that CuO'90 w
t% and Zn0.10 wt%.

These catalysts were tested for activity in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 6 Japanese Patent Application Laid-Open No. 1983-1989, which is a prior document. No. 15786 discloses that a copper-chromium-manganese oxide catalyst exhibits excellent activity in the steam reforming reaction of methanol, so additional tests were conducted. To a solution of 126.1 F ammonium dichromate in 500 CC water, 150 c'c of 28 thiammonium water was added, and to this solution were added 241.6 f crystalline copper nitrate and 28.7 f crystalline manganese nitrate. A solution dissolved in 500 cc of water was added dropwise while stirring. The resulting precipitate was washed with water, dried, and pulverized, and then calcined at 350°C. The resulting copper-chromium-manganese oxide was placed in a mortar with 1002 and mixed with 40% chromic acid aqueous solution 7.
52 was gradually added, dried and ground.

Next, about 40 wt% of diatomaceous earth was mixed and the mixture was compressed into a 61RrR cylinder. This catalyst was tested for activity in the same manner as in Example 1. The results are shown in Table 2.

From a comparison of Examples 1 and 2 and Comparative Examples 1 to 3, the catalyst of the present invention exhibits a higher methanol conversion rate than the known methanol steam reforming catalyst. Especially when the MfO content is 2
Excellent activity is shown in the range of ~20 wt%.

Comparative Example 4 Example 1. CuO90w was prepared in the same manner as in Example 1 using an alkaline earth nitrate as a substitute for magnesium nitrate.
t% and 10 wt% alkaline earth oxide. These catalysts were tested for activity in the same manner as in Example 1, and the results are shown in Table 3.

This result indicates that the activity is lower than that of the copper-magnesium catalyst.
It can be seen that among the copper-alkaline earth catalysts, only copper-magnesium exhibits a specifically high activity.

Example 3 Precipitate produced by dropping an aqueous sodium carbonate solution into a solution of copper nitrate trihydrate 273.39 in 400 cc of water and a precipitate produced by dissolving magnesium nitrate hexahydrate 6362 in 100 cc of water. The precipitates produced by dropping an aqueous sodium carbonate solution were washed with water, filtered, mixed, and kneaded for 2 hours with a Nigu.

After drying this, it was fired in air at 300°C for 1 hour, and Cu
A set of acids containing 90 wt% O, MP, and 10 wt% was obtained. This was pulverized and formed into a cylindrical tablet with a diameter of 6 mm. The activity test was conducted in the same manner. The results are shown in Table 4.

Example 4 636.0 g of magnesium nitrate hexahydrate was added to 5 tons of water.
Add a sodium carbonate aqueous solution dropwise to the W4 solution, wash the formed precipitate with water, filter it, and then sinter at 300°C for 1 hour. This was pulverized and compressed into a cylindrical tablet with a diameter of 6 mm to produce a carrier. The obtained carrier was mixed with copper nitrate trihydrate 164. O
f in an aqueous solution of 300 cc of water, dried,
A catalyst was obtained by firing at 300°C for 1 hour. The ratio of copper to magnesium in the catalyst is Cuo 21. '6
wt%, and MfO' was 78.4 wt%.

This catalyst was tested for activity in the same manner as in Example 1, and the results are shown in Table 4.

Example 5 Yubas powder was obtained. This powder is commercially available γ of 4 to 6 φ
- The catalyst was placed in a dish-shaped granulator together with an alumina carrier, and a small amount of water was added to produce a catalyst in which the surface of the γ-alumina carrier was coated with a copper-magnesium composition. The coating amount of the copper-magnesium composition on the obtained catalyst was 27.9% as an oxide based on the total weight of the catalyst. This catalyst was tested for activity in the same manner as in Example 1, and the results are shown in Table 4.

Claims (1)

[Claims] 1) L-'i containing a copper compound and a magnesium compound
A methanol steam reforming catalyst characterized by: