JP3215680B1 - Catalyst for removing CO in hydrogen gas - Google Patents

Abstract

An object of the present invention is to provide a catalyst for removing CO in hydrogen gas which can efficiently remove CO in hydrogen gas in a wide temperature range. SOLUTION: A catalyst for removing CO is prepared by supporting at least platinum on a zirconia carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst for removing CO used for selectively converting and removing CO contained in a hydrogen-rich gas by a water gas shift reaction.

[0002]

2. Description of the Related Art A hydrogen-rich reformed gas obtained by subjecting a fuel to steam reforming with steam, such as a hydrocarbon gas, a liquid, a solid, or an alcohol such as methanol, is used in a fuel cell power generation system. Used as a source of Fuel cells are classified according to the type of fuel and electrolyte used, operating temperature, etc.Polymer fuel cells have low operating temperatures, high power densities, and can be expected to be smaller, lighter, and shorter in operating time. Therefore, use in automobiles, small generators, home cogeneration systems, and the like has been considered.

Here, the polymer electrolyte fuel cell uses a perfluorosulfonic acid-based polymer membrane as a proton-conductive solid electrolyte, and operates at a temperature of 50 to 100 ° C. However, since the polymer electrolyte fuel cell operates at a low temperature, it is easily poisoned by impurities contained in the hydrogen-rich reformed gas. In particular, the platinum used for the electrode is easily poisoned by CO, and if the reformed gas contains more than a predetermined concentration of CO, the power generation performance decreases.

Therefore, a CO remover is provided downstream of the reformer for reforming the fuel into a hydrogen-rich reformed gas, and CO is selectively converted and removed by a water gas shift reaction to reduce the CO concentration to 1% or less. Need to reduce. As a CO removal catalyst used for the CO removal, a Cu—Zn-based catalyst has been generally used conventionally.

[0005]

However, since the activity of the Cu-Zn catalyst is low, it is necessary to use a large amount to reduce CO to 1% or less, and the activity deteriorates with time. However, there is a problem that the catalyst needs to be replaced. Therefore, it is difficult to apply the conventional Cu—Zn-based catalyst to a small and portable fuel cell system in which starting and stopping are repeatedly performed.

The present invention has been made in view of the above points, and has as its object to provide a catalyst for removing CO in hydrogen gas which can efficiently remove CO in hydrogen gas over a wide temperature range. Is what you do.

[0007]

According to the first aspect of the present invention, there is provided a catalyst for removing CO in hydrogen gas, wherein at least platinum is supported on a zirconia carrier.

Further, the invention of claim 2 is characterized in that, in the above-mentioned claim 1, the amount of the supported platinum is 0.1 to 10% by weight based on the weight of the zirconia carrier.

A third aspect of the present invention is characterized in that the zirconia carrier carries rhenium in addition to the platinum.

The invention according to claim 4 is characterized in that the amount of rhenium supported is 0.1 to 10% by weight based on the weight of the zirconia carrier.

According to a fifth aspect of the present invention, the zirconia carrier has at least one metal selected from the group consisting of yttrium, calcium, chromium, samarium, cerium, tungsten, neodymium, praseodymium, magnesium, molybdenum, and lanthanum, in addition to platinum. It is characterized by comprising.

Further, the invention according to claim 6 is characterized in that the amount of the metal loaded in claim 5 is 0.1 to 0.1% based on the weight of the zirconia carrier.
It is characterized by being 10% by weight.

[0013]

Embodiments of the present invention will be described below.

In the present invention, a zirconia carrier is used as a catalyst carrier. The zirconia carrier can be prepared, for example, by calcining a starting material, zirconium hydroxide hydrate.

When platinum is supported on the zirconia support, an aqueous solution of a platinum salt is added to the zirconia support, the mixture is evaporated to dryness with stirring, and the resulting dry solid is dried by heating. It can be performed by baking after pulverizing the product. Then, this is pressed to form a pellet, and the obtained pellet is 0.5 to
By pulverizing to a particle diameter of 1.0 mm, the catalyst can be used as a CO removal catalyst in which platinum is supported on a zirconia carrier.

Here, in the CO removal catalyst, the amount of supported platinum is 0.1 to 10% based on the weight of the zirconia carrier.
A range of weight% is preferred. 0.1% by weight of platinum carried
Is less than C in H ₂ by the water gas shift reaction.
It is difficult to obtain sufficient catalytic activity when removing O by converting it to CO ₂ , and the amount of supported platinum is 10% by weight.
If the temperature exceeds the above, the catalytic activity is not further improved, and the cost is disadvantageous.

A catalyst for removing CO can be obtained by supporting other metals besides platinum on the zirconia carrier. Other metals include rhenium, yttrium, calcium, chromium, samarium, cerium, tungsten, neodymium, praseodymium, magnesium, molybdenum,
Lanthanum can be used, and one or more of these can be selected and supported on a zirconia carrier.

In preparing a CO removal catalyst in which the above metal is supported on a zirconia carrier in addition to platinum, yttrium, calcium, chromium, samarium, cerium, tungsten, neodymium, praseodymium, magnesium, molybdenum, lanthanum are used as metals. When using, an aqueous solution of these metal salts was added together with an aqueous solution of chloroplatinic acid, and the mixture was evaporated to dryness with stirring, and the obtained dry solid was dried by heating, and the dried product was pulverized. This can be performed by baking later. Then, this is pressed to form a pellet, and the obtained pellet is pulverized to a particle size of 0.5 to 1.0 mm to be used as a CO removal catalyst in which platinum and these metals are supported on a zirconia carrier. Is what you can do.

When preparing a catalyst for removing CO in which rhenium as a metal in addition to platinum is supported on a zirconia support, first, an aqueous solution of a rhenium salt is added to the zirconia support, and this is evaporated to dryness with stirring. The resulting dried solid is heated and dried, and the dried product is pulverized and then fired, whereby rhenium is supported on the zirconia carrier. After supporting rhenium on the zirconia carrier in this manner, by supporting platinum on the zirconia carrier in the same manner as described above, a CO removal catalyst in which platinum and rhenium are supported on the zirconia carrier can be obtained. is there.

[0020] By addition to the above metal of the platinum is supported on the zirconia support, it is possible to increase the catalytic activity of the CO removal, in removing by conversion of CO in H ₂ to CO _2, CO Can react with H ₂ to prevent methanation reaction from occurring. In particular, by using rhenium as the metal, it is possible to obtain a high effect of increasing the catalytic activity for removing CO. Here, in the CO removal catalyst, the amount of the metal supported is preferably in the range of 0.1 to 10% by weight in terms of metal, based on the weight of the zirconia carrier. When the amount of the metal supported is less than 0.1% by weight, it is difficult to sufficiently obtain the effect of preventing the methanation reaction,
Further, even if the amount of the metal supported exceeds 10% by weight, the effect of preventing the methanation reaction is not further improved, which is disadvantageous in cost.

[0021]

Next, the present invention will be described specifically with reference to examples.

(Examples 1 to 5) The temperature of zirconium hydroxide n-hydrate (manufactured by Mitsui Chemicals, Inc.) was raised to 500 ° C. for 1 hour in an air stream at 60 ml / min using a firing furnace. Then, a baking treatment was performed at the same temperature for one hour to obtain zirconium oxide, which was used as a zirconia carrier.

A predetermined amount of the zirconia carrier obtained as described above was placed in an evaporating dish on a hot water bath, and mixed with pure water to be familiarized. An aqueous solution of chloroplatinic acid hexahydrate (manufactured by Nacalai Tesque, Inc.) was added thereto, and pure water was further added to adjust the concentration to a predetermined concentration. While stirring this on a hot water bath,
The metal salt adhering to the wall surface of the evaporating dish with the evaporation of water was washed off with pure water, evaporated to dryness for 1 hour, and the obtained dry solid was dried at about 100 ° C. for 15 hours or more. After the dried product was crushed into a powder form in an agate mortar, it was baked in a baking oven for 60 m.
In a liter / min air flow, the temperature was raised to 500 ° C. for 1 hour, and calcination was performed under the condition of maintaining the temperature at the same temperature for 1 hour. Then, using a manual hydraulic compressor, about 3600 kg / cm ²
And the resulting pellets were pressed for 0.5 seconds.
The catalyst was pulverized to a particle size of about 1.0 mm to obtain a CO removal catalyst in which platinum was supported on a zirconia carrier.

Here, by adjusting the amount of the chloroplatinic acid aqueous solution to be added, the catalysts for removing CO of Examples 1 to 5 in which the supported amount of platinum was as shown in Table 1 were prepared.

[0025]

[Table 1]

With respect to the CO removing catalysts of Examples 1 to 5, the CO removing performance was evaluated. The evaluation experiment was performed as follows. First, 0.7 ml of a CO removal catalyst was charged into a reaction tube, and the temperature was raised to 500 ° C. for 1 hour while flowing hydrogen, and then the reduction treatment was performed at the same temperature for 1 hour. Next, 200 ° C for 1 hour while flowing helium
After the temperature dropped to, the supply of helium was stopped, and H ₂ O and CO
Was fed under the conditions of H ₂ and O / CO = 1.3 CO-containing gas mixture in a molar ratio of 3650SV [1 / h] (CO standard), the experiment was started the CO removal reaction at a reaction temperature of 200 ° C.. After the reaction was stabilized, samples at the inlet and outlet of the reaction tube were collected and analyzed by gas chromatography (thermal conductivity detector) to determine the CO conversion at which CO was converted to CO ₂ . The reaction temperature is set at 250 ° C, 300 ° C, 350 ° C.
, And a sample after the reaction was similarly stabilized was collected and analyzed to determine the CO conversion.

As a comparative example, an experiment for removing CO was performed in the same manner except that the reduction treatment was performed at 300 ° C. using a Cu / ZnO catalyst (“N211” manufactured by JGC Chemicals, Inc.).

FIG. 1 shows the results. As can be seen from the results of FIG. 1, the Pt / ZrO ₂ catalysts of the respective examples are comparable to those of the comparative example.
It is confirmed that the activity is higher than that of the / ZnO catalyst.

Next, the change with time of the activity of the catalyst was measured. The experiments were performed on the catalysts of Example 3, Example 4, and Comparative Example. First, after performing the above-mentioned reduction treatment, the temperature was lowered to 250 ° C. in one hour while flowing helium, the helium was stopped, and a CO-containing gas was supplied in the same manner as above, and the reaction was stabilized. Samples at the inlet and outlet of the tube were taken and analyzed by gas chromatography to determine the CO conversion.

FIG. 2 shows the results. As can be seen from the results in FIG. 2, the activity of the Cu / ZnO catalyst of the comparative example gradually deteriorated immediately after the start of the experiment, whereas the activity of the Pt / ZrO ₂ catalyst of Examples 3 and 4 deteriorated. Will be confirmed.

(Example 6) A predetermined amount of the zirconia carrier prepared in (Examples 1 to 5) was placed in an evaporating dish on a hot water bath.
This was mixed with pure water and blended. An aqueous solution of chloroplatinic acid hexahydrate (manufactured by Nacalai Tesque Co., Ltd.) and an aqueous solution of lanthanum nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) are added thereto, and pure water is further added so as to have a predetermined concentration. I made it. While stirring this in a hot water bath, metal salts adhering to the wall surface of the evaporating dish as the water evaporates are washed away with pure water, and evaporated to dryness for 1 hour. Let dry for more than an hour. After the dried product is crushed into a powder in an agate mortar, the temperature is raised to 500 ° C. for 1 hour in an air stream of 60 ml / min using a firing furnace, and the firing is performed under the condition of maintaining the temperature for 1 hour. Thus, platinum was loaded on the zirconia support at a loading of 3.0% by weight, and lanthanum was loaded at a loading of 5.0% by weight. Next, using a manual hydraulic compressor, the mixture was pressed at a pressure of about 3600 kg / cm ² for 10 seconds, and the obtained pellets were crushed to a particle size of 0.5 to 1.0 mm, and platinum and lanthanum were added to the zirconia carrier. Was obtained.

(Examples 7 to 16) In the same manner as in the above (Example 6) except that the supported metal raw materials shown in Table 2 were used instead of lanthanum nitrate hexahydrate, other metals shown in Table 3 were used in addition to platinum. Was supported on a zirconia support to obtain a CO removal catalyst.

[0033]

[Table 2]

[0034]

[Table 3]

The catalysts of Examples 6 to 16 and Example 3 obtained as described above were subjected to an experiment for removing CO in the same manner as described above. The results are shown in FIG. FIG. 3 shows the reaction temperature 3
At the time of converting CO to CO ₂ at 50 ° C. to remove it, the reaction selectivity is a rate at which CO is converted to CO ₂ without being converted to CH ₄ , and the catalysts of Examples 6 to 16 are: It is confirmed that the reaction selectivity is higher than that of Example 3 supporting only platinum.

(Example 17) A predetermined amount of the zirconia carrier prepared in the above (Examples 1 to 5) was put in an evaporating dish on a hot water bath, and mixed with pure water to make it familiar. An aqueous solution of ammonium perrhenate (manufactured by Mitsui Chemicals, Inc.) was added thereto, and pure water was further added to adjust the concentration to a predetermined value. While stirring this in a hot water bath, the metal salt adhering to the wall surface of the evaporating dish with the evaporation of water was washed away with pure water, dried at about 100 ° C. for 15 hours or more, and rhenium was supported on the zirconia carrier. Next, using this zirconia carrier carrying rhenium, platinum was carried in the same manner as in the above (Examples 1 to 5), and platinum was carried at 3.0 wt% and rhenium was added at 1.0 wt%. % Of the zirconia carrier, to obtain a catalyst for CO removal.

Example 18 The procedure of Example 17 was repeated except that the amount of the aqueous solution of ammonium perrhenate (manufactured by Mitsui Chemicals, Inc.) was adjusted. At a loading of 0.0% by weight, rhenium was added at 3.
A catalyst for CO removal supported on a zirconia carrier at a supported amount of 0% by weight was obtained.

The catalysts of Examples 17 and 18 and Example 3 and Comparative Example obtained as described above were subjected to an experiment for removing CO in the same manner as described above. FIG. 4 shows the results. As shown in FIG. 4, it is confirmed that the catalysts of Examples 17 and 18 have high activity, and particularly high activity at a low temperature of 250 ° C. or lower.

[0039]

As described above, the catalyst for removing CO in hydrogen gas according to the first aspect of the present invention is characterized in that at least platinum is supported on a zirconia carrier, and the water gas shift reaction is carried out. CO in hydrogen gas by C
When converting to O ₂ for removal , C in hydrogen gas
O can be efficiently removed in a wide temperature range, and can be easily applied to a small and portable fuel cell power generation system that repeatedly starts and stops.

Further, according to the invention of claim 2, in the above-mentioned claim 1, the amount of supported platinum is based on the weight of the zirconia carrier.
0.1 to 10% by weight, and it is possible to effectively obtain catalytic activity for removing CO by platinum.
One in which possible.

Further, the invention of claim 3 is characterized in that the zirconia carrier carries rhenium in addition to the above platinum, so that the catalytic activity for removing CO can be enhanced and the methanation reaction can be carried out. Can be prevented from occurring.

Further, the invention of claim 4 is characterized in that the amount of rhenium supported is 0.1 to 10% by weight based on the weight of the zirconia carrier, and the effect of preventing methanation reaction is provided. It can be obtained effectively.

According to a fifth aspect of the present invention, at least one metal selected from the group consisting of yttrium, calcium, chromium, samarium, cerium, tungsten, neodymium, praseodymium, magnesium, molybdenum, and lanthanum is supported on the zirconia carrier. It is characterized in that the catalyst activity for removing CO can be enhanced and the methanation reaction can be prevented from occurring.

According to a sixth aspect of the present invention, the amount of the metal of the fifth aspect is 0.1 to 0.1% based on the weight of the zirconia carrier.
The content is 10% by weight, and an effect of preventing a methanation reaction can be effectively obtained.

[Brief description of the drawings]

FIG. 1 shows the reaction temperature and C in Examples 1 to 5 and Comparative Example.
It is a graph which shows the relationship of O conversion.

FIG. 2 shows the reaction time and C in Examples 3, 4 and Comparative Example.
It is a graph which shows the relationship of O conversion.

FIG. 3 is a graph showing the reaction selectivity in Example 3 and Examples 6 to 16.

FIG. 4 is a graph showing the relationship between the reaction temperature and the CO conversion in Examples 3, 17, 18 and Comparative Example.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C01B 3/56 B01J 23/64 104M (72) Inventor Noboru Hashimoto 1048 Ojidoma, Kadoma-shi, Osaka Matsushita Electric Works, Ltd. (56) References JP-A-8-217406 (JP, A) JP-A-50-84490 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-38/74 C01B 3/00- 3/58 H01M 8/00-8/24

Claims (6)

(57) [Claims] 1. A water gas shift reaction characterized in that at least platinum is supported on a zirconia carrier .
To remove CO by converting CO in hydrogen gas to CO ₂
O removal catalyst. 2. The catalyst for removing CO in hydrogen gas according to claim 1, wherein the supported amount of the platinum is 0.1 to 10% by weight based on the weight of the zirconia carrier. 3. A zirconia carrier comprising rhenium supported thereon in addition to the platinum.
3. The catalyst for removing CO in hydrogen gas according to item 1. 4. The catalyst for removing CO in hydrogen gas according to claim 3, wherein the amount of rhenium supported is 0.1 to 10% by weight based on the weight of the zirconia carrier. 5. A zirconia carrier comprising at least one metal selected from the group consisting of yttrium, calcium, chromium, samarium, cerium, tungsten, neodymium, praseodymium, magnesium, molybdenum and lanthanum, in addition to platinum. The catalyst for removing CO in hydrogen gas according to any one of claims 1 to 4. 6. The method for removing CO in hydrogen gas according to claim 5, wherein the supported amount of the metal of the fifth aspect is 0.1 to 10% by weight based on the weight of the zirconia carrier. catalyst.