JP2007313487A - Water gas conversion reaction catalyst and water gas conversion reaction method using the same. - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst exhibiting high activity in a water gas conversion reaction for reacting carbon monoxide with water vapor to convert it into hydrogen and carbon dioxide.
SOLUTION: A catalyst having copper oxide, zinc oxide, zirconium oxide, aluminum oxide, alkali metal element and silicon oxide as essential components, and when the total amount of the catalyst is 100% by weight, the content of each component is as described above. 20 to 70% by weight, 10 to 60% by weight, 1 to 50% by weight, 1 to 50% by weight, 0.5 to 10% by weight and 0.5 to 2% by weight of the catalyst for water gas conversion reaction .
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Description

  The present invention relates to a catalyst for water gas conversion reaction, and more specifically, a catalyst used when carbon dioxide and water vapor are reacted to produce carbon dioxide and hydrogen (referred to as water gas shift reaction or CO shift reaction) and It relates to a water gas conversion reaction using the same.

これまでに、このような水性ガス転化反応用触媒としては、高温反応用として、鉄・クロム系触媒が、低温反応用として、銅／亜鉛／アルミニウムの酸化物からなる触媒あるいは銅／亜鉛／クロムの酸化物からなる触媒が開発され、工業的に実施されている（例えば非特許文献１参照）。また、酸化銅／酸化亜鉛系触媒に、特定量の酸化珪素を添加することにより、高活性で高耐久性・長期安定性に優れたものとすることも提案されている（特許文献１）。さらに、酸化銅、酸化亜鉛、酸化ジルコニウム、酸化アルミニウムおよび酸化マンガンを必須成分とする触媒もある（特許文献２）。 Conventionally, the water gas conversion reaction is known to be an important reaction for removing CO in hydrogen production from hydrocarbons or adjusting the H ₂ / CO ratio in methanol synthesis or oxo synthesis. Therefore, hydrogen having a low CO content for fuel cells is attracting attention as one of the main processes for producing hydrocarbons and the like.
This water gas conversion reaction is a reaction for generating H ₂ and CO ₂ from CO and H ₂ O as shown in the following reaction formula.

Up to now, as such a catalyst for water gas conversion reaction, an iron / chromium-based catalyst is used for a high temperature reaction, a catalyst made of a copper / zinc / aluminum oxide or a copper / zinc / chromium is used for a low temperature reaction. Catalysts comprising these oxides have been developed and implemented industrially (see, for example, Non-Patent Document 1). It has also been proposed to add a specific amount of silicon oxide to a copper oxide / zinc oxide catalyst to achieve high activity, high durability, and long-term stability (Patent Document 1). Furthermore, there is a catalyst having copper oxide, zinc oxide, zirconium oxide, aluminum oxide and manganese oxide as essential components (Patent Document 2).

However, the present situation is that the CO conversion rate of any catalyst is not yet satisfactory, and the development of a high-performance catalyst is an important technical development subject.
In order to improve the catalytic activity of the copper oxide / zinc oxide catalyst, the present inventors have tried various improvements, and already include copper oxide, zinc oxide, zirconium oxide, aluminum oxide and alkali metal elements as essential components. Has been found and has been filed (patent document 3).
"Catalyst Lecture" Vol. 8, pp. 251-262, Catalytic Society, published by Kodansha (1985) JP 2000-126597 A JP 2004-126597 A Japanese Patent Application No. 2005-58357

  However, according to subsequent studies by the present inventors, it has been found that it is necessary to improve the long-term stability of the catalyst activity in the high-performance catalyst of Patent Document 3 filed earlier. The present invention has been made in view of such circumstances, and in a water gas conversion reaction, the catalyst activity is extremely high, and the catalyst activity is excellent in long-term stability of the catalyst activity, and the water gas conversion reaction using the catalyst. The main purpose is to provide a method.

  As a result of various studies on a catalyst containing copper, the present inventor can solve the problem with a catalyst containing copper oxide, zinc oxide, zirconium oxide, aluminum oxide, alkali metal element and silicon oxide as essential components. I found out.

That is, according to the present invention, firstly, it exhibits extremely high catalytic activity in a water gas conversion reaction comprising copper oxide, zinc oxide, zirconium oxide, aluminum oxide, alkali metal element and silicon oxide as essential components, A catalyst having excellent long-term stability of catalytic activity is provided.
Second, in the first invention, a catalyst containing copper oxide, zinc oxide, zirconium oxide, aluminum oxide, alkali metal element and silicon oxide as essential components, and when the total amount of the catalyst is 100% by weight, each component The content of is 20 to 70% by weight, 10 to 60% by weight, 1 to 50% by weight, 1 to 50% by weight, 0.5 to 10% by weight and 0.5 to 2% by weight in the above order. A catalyst for water gas conversion reaction is provided.
Third, there is provided a water gas conversion reaction method characterized by contacting carbon monoxide and water vapor with the first catalyst.

  The catalyst of the present invention exhibits extremely high catalytic activity in the water gas conversion reaction, and also has excellent long-term stability of catalytic activity. Accordingly, the water gas conversion reaction conversion reaction can be carried out industrially advantageously.

  The water gas conversion reaction catalyst of the present invention is characterized by containing copper oxide, zinc oxide, zirconium oxide, aluminum oxide, alkali metal element and silicon oxide as essential components. The catalyst of the present invention is obtained by adding silicon oxide to the catalyst of the previous application (Patent Document 3). The effect of silicon oxide is to stabilize the catalyst activity by suppressing the crystal growth of the catalyst component. It is to become.

  The ratio of each catalyst component is not particularly limited, but when the total catalyst is 100% by weight, copper oxide is 20 to 70% by weight, zinc oxide is 10 to 60% by weight, zirconium oxide is 1 to 50% by weight, oxidation Aluminum is 1 to 50% by weight, alkali metal element is 0.5 to 10% by weight, and silicon oxide is 0.5 to 2% by weight. In such a quantitative range, by appropriately determining the composition according to the reaction conditions, catalyst performance suitable for the reaction conditions can be obtained. In particular, when the amount of silicon oxide, which is a feature of the present invention, is less than 0.5% by weight, the effect of stabilizing the above enzyme activity is small, and when it exceeds 2% by weight, the activity decreases. Come on.

  Moreover, in this invention, the other substance may be included in the range which does not impair the meaning of this invention. Examples of such a substance include calcium oxide, magnesium oxide, lanthanum oxide, cerium oxide, and graphite.

As raw materials for copper oxide, zinc oxide, zirconium oxide, and aluminum oxide, which are catalyst components of the present invention, respective nitrates, hydrochlorides, sulfates, organic acid salts, hydroxides, and the like can be used.
In addition, hydroxides such as lithium, sodium, potassium, rubidium, and cesium, carbonates, bicarbonates, nitrates, organic acid salts, and the like can be used as raw materials for elements belonging to alkali metals.
Furthermore, colloidal silica is most preferable as a raw material for silicon oxide, but is not limited to colloidal silica, and dissolved silica, silicic acid, various silicates, and the like can also be used.

The method for producing the catalyst of the present invention is not particularly different from the currently well-known method for producing a copper oxide-zinc oxide-based water gas conversion reaction catalyst, and various current production methods can be applied. .
For example, a catalyst precursor is prepared by a method such as a coprecipitation method, an impregnation method, a mixing method, a sequential precipitation method, an alkoxide method, or a combination of these methods, and then the catalyst precursor is calcined in air. Can be manufactured. Although the calcination temperature of a catalyst precursor is not specifically limited, The range of 300-650 degreeC is preferable and 350 degreeC-600 degreeC is especially preferable. The catalyst thus produced is used as it is or after being granulated or tableted by an appropriate method. The particle diameter and shape of the catalyst can be arbitrarily selected depending on the reaction system and the shape of the reactor. That is, the catalyst according to the present invention can be used in any reaction system such as a fixed bed and a fluidized bed.
Or after obtaining what consists of other structural components except the alkali metal element which is a component which constitutes a catalyst of the present invention by the above-mentioned method, an alkali metal element is added to the oxide after the firing, It can be dried and calcined again to form a catalyst.

  The catalyst after calcination may be obtained by previously reducing copper oxide in the catalyst to metallic copper before use in the reaction. However, even when this reduction is not performed, the copper oxide is naturally reduced by carbon monoxide or hydrogen in the reaction gas, and therefore a prior reduction operation is not essential.

  The reaction conditions in the water gas conversion reaction method of carbon monoxide and water vapor using the catalyst according to the present invention may vary depending on the concentration of carbon monoxide and hydrogen in the raw material gas, the content of the catalyst component, and the like.

  Usually, the reaction temperature is 150 to 300 ° C., the reaction pressure is 1 to 100 atm (absolute pressure), the molar concentration of carbon monoxide in the raw material gas (excluding water vapor) is 1 to 30%, one in the water vapor and the raw material gas. The molar ratio of carbon oxide is suitably 1 to 100, and the space velocity of the raw material gas (excluding water vapor) is suitably in the range of 1,000 to 100,000 (1 / h).

  Hereinafter, the features of the present invention will be further clarified by giving examples.

Example 1
Copper nitrate trihydrate 35.1 g, zinc nitrate hexahydrate 25.3 g, zirconium oxynitrate dihydrate 12.5 g, aluminum nitrate nonahydrate 8.5 g and colloidal silica (Snow manufactured by Nissan Chemical Industries, Ltd.) 1.0 g (Tex O, silica concentration 20% by weight) was dissolved in distilled water to prepare a 300 ml aqueous solution, which was designated as solution A. On the other hand, 36.3 g of anhydrous sodium carbonate was dissolved in distilled water to prepare a 300 ml aqueous solution, which was designated as solution B. Liquid A and liquid B were each added dropwise simultaneously to 800 ml of room temperature distilled water that was well stirred at a rate of 8 ml / min to obtain a precipitate. The precipitate was aged at room temperature for 1 day, and then filtered and washed to remove sodium in the precipitate. Thereafter, the precipitate was dried at 105 ° C. and calcined in air at 600 ° C. for 2 hours. The composition of the oxide after firing was 45.1% by weight of copper oxide, 27.1% by weight of zinc oxide, 22.5% by weight of zirconium oxide, 4.5% by weight of aluminum oxide and 0.8% by weight of silicon oxide. there were. Next, 1.9 g of 0.8 wt% potassium hydroxide aqueous solution is added to 1.5 g of the calcined oxide whose particle size is adjusted to 250 to 600 μm, dried at 105 ° C., and calcined at 400 ° C. in the air. After that, a catalyst was obtained. The composition of this catalyst was 44.7% by weight of copper oxide, 26.8% by weight of zinc oxide, 22.3% by weight of zirconium oxide, 4.4% by weight of aluminum oxide, 1% by weight of potassium hydroxide and 0.8% of silicon oxide. % By weight.

0.56 g of the obtained catalyst was filled into a reaction tube, and a mixed gas of helium and hydrogen (90% by volume of helium, 10% by volume of hydrogen) was supplied at a flow rate of 300 ml / min. Reduction was performed. After reduction of the catalyst, the reaction tube, the raw material gas (CO 10 vol%, _CO 2 18 volume%, of hydrogen 72% by volume) and supplying the water vapor, were water gas shift reaction. The reaction conditions were temperature, 240 ° C., pressure, 1 MPa, raw material gas flow rate, 100 ml / min, volume ratio of water vapor and raw material gas, 0.25. The reaction product gas was analyzed by gas chromatography. As a result, the CO conversion rate was 82% at a reaction elapsed time of 50 hours, and the CO conversion rate was 82% at a reaction elapsed time of 500 hours (see Table 1). From this result, it is clear that the catalyst of the present invention has high activity and excellent long-term stability.

(Example 2)
A precipitate was obtained in the same manner as in Example 1 except that the amount of colloidal silica was 1.5 g, and the precipitate was dried and fired in the same manner as in Example 1. The composition of the oxide after firing was 45.0% by weight of copper oxide, 27.0% by weight of zinc oxide, 22.4% by weight of zirconium oxide, 4.4% by weight of aluminum oxide and 1.2% by weight of silicon oxide. there were. Next, 1.9 g of 0.8 wt% potassium hydroxide aqueous solution is added to 1.5 g of the calcined oxide whose particle size is adjusted to 250 to 600 μm, dried at 105 ° C., and calcined at 400 ° C. in the air. After that, a catalyst was obtained. The composition of this catalyst was 44.6% copper oxide, 26.7% zinc oxide, 22.2% zirconium oxide, 4.3% aluminum oxide, 1% potassium hydroxide and 1.2% silicon oxide. % By weight.

  0.56 g of the obtained catalyst was charged into a reaction tube, and a water gas conversion reaction was performed in the same manner as in Example 1. As a result, the CO conversion rate was 82% at a reaction elapsed time of 50 hours, and the CO conversion rate was 83% at a reaction elapsed time of 500 hours (see Table 1). From this result, it is clear that the catalyst of the present invention has high activity and excellent long-term stability.

(Example 3)
A precipitate was obtained in the same manner as in Example 1 except that the amount of colloidal silica was 2.0 g. The precipitate was dried and fired in the same manner as in Example 1. The composition of the oxide after firing was 44.8% by weight of copper oxide, 26.9% by weight of zinc oxide, 22.3% by weight of zirconium oxide, 4.4% by weight of aluminum oxide and 1.6% by weight of silicon oxide. there were. Next, 1.9 g of 0.8 wt% potassium hydroxide aqueous solution is added to 1.5 g of the calcined oxide whose particle size is adjusted to 250 to 600 μm, dried at 105 ° C., and calcined at 400 ° C. in the air. After that, a catalyst was obtained. The composition of this catalyst was 44.4% by weight copper oxide, 26.6% by weight zinc oxide, 22.1% by weight zirconium oxide, 4.3% by weight aluminum oxide, 1% by weight potassium hydroxide and 1.6% silicon oxide. % By weight.

  0.56 g of the obtained catalyst was charged into a reaction tube, and a water gas conversion reaction was performed in the same manner as in Example 1. As a result, the CO conversion rate was 80% at a reaction elapsed time of 50 hours, and the CO conversion rate was 80% at a reaction elapsed time of 500 hours (see Table 1). From this result, it is clear that the catalyst of the present invention has high activity and excellent long-term stability.

(Comparative Example 1)
A precipitate was obtained in the same manner as in Example 1 except that colloidal silica was not used. The precipitate was dried and fired in the same manner as in Example 1. The composition of the oxide after firing was 45.5% by weight of copper oxide, 27.3% by weight of zinc oxide, 22.7% by weight of zirconium oxide, and 4.5% by weight of aluminum oxide. Next, 1.9 g of 0.8 wt% potassium hydroxide aqueous solution is added to 1.5 g of the calcined oxide whose particle size is adjusted to 250 to 600 μm, dried at 105 ° C., and calcined at 400 ° C. in the air. After that, a catalyst was obtained. The composition of this catalyst was copper oxide 45.0% by weight, zinc oxide 27.0% by weight, zirconium oxide 22.5% by weight, aluminum oxide 4.5% by weight, and potassium hydroxide 1% by weight.

  0.56 g of the obtained catalyst was charged into a reaction tube, and a water gas conversion reaction was performed in the same manner as in Example 1. As a result, the CO conversion rate was 83% at a reaction elapsed time of 50 hours, and the CO conversion rate was 80% at a reaction elapsed time of 500 hours (see Table 1). From this result, it is clear that the catalyst containing no silicon oxide is not sufficiently stable in activity.

(Comparative Example 2)
Firing comprising 44.8% by weight of copper oxide, 26.9% by weight of zinc oxide, 22.3% by weight of zirconium oxide, 4.4% by weight of aluminum oxide and 1.6% by weight of silicon oxide obtained in Example 3. The particle size of the subsequent oxide was adjusted to 250 to 600 μm, and the catalyst was used as it was without adding an aqueous potassium hydroxide solution.

  0.56 g of the obtained catalyst was charged into a reaction tube, and a water gas conversion reaction was performed in the same manner as in Example 1. As a result, the CO conversion rate was 72% at a reaction elapsed time of 50 hours, and the CO conversion rate was 72% at a reaction elapsed time of 500 hours (see Table 1). From this result, it is clear that the catalyst containing no alkali metal element has a significantly low activity.

The catalyst for water gas conversion reaction of the present invention exhibits its high catalytic activity and is excellent in long-term stability of its catalytic activity, so that CO removal, methanol synthesis and the like in hydrogen production from hydrocarbons and biomass can be performed. This is useful for adjusting the H ₂ / CO ratio in oxo synthesis or for producing hydrogen with a low CO content for fuel cells.

Claims (3)

  A catalyst for water gas conversion reaction comprising copper oxide, zinc oxide, zirconium oxide, aluminum oxide, alkali metal element and silicon oxide as essential components.   A catalyst comprising copper oxide, zinc oxide, zirconium oxide, aluminum oxide, alkali metal element and silicon oxide as essential components, and when the total catalyst is 100% by weight, the content of each component is 20 to 20 in the above order. 2. An aqueous solution according to claim 1, characterized in that it is 70%, 10-60%, 1-50%, 1-50%, 0.5-10% and 0.5-2% by weight. Catalyst for gas conversion reaction. A water gas conversion reaction method comprising contacting carbon monoxide and water vapor with the catalyst according to claim 1 or 2.