Shaped catalyst body for removing high-concentration slipped hydrogen

Abstract

The present invention relates to a shaped catalyst body for removing high-concentration slipped hydrogen, wherein catalyst slurries having different precious metal compositions are applied to multiple zones of a honeycomb molded body, respectively. In the shaped catalyst body, the precious metal content in the catalyst slurry applied to a front end zone is lower than the precious metal content in the catalyst slurry applied to a rear end zone, thereby solving a heating problem caused by a high-concentration hydrogen oxidation reaction and a toxicity problem of moisture as a by-product, and reducing the use of expensive platinum.

Description

Catalyst molded body for high-concentration slip hydrogen removal

[0001] The present invention relates to a catalyst body for oxidizing and removing high-concentration slip hydrogen, and more particularly, to a honeycomb molded body in which a catalyst material is applied in a zone.

[0002] As the hydrogen industry ecosystem becomes more visible, interest in the hydrogen economy, which uses hydrogen as a primary energy source, is growing. As hydrogen use increases, the need for safe hydrogen use is also emerging. If the concentration of hydrogen slipping into the atmosphere exceeds 4%, explosions and flames can occur. To prevent this risk, there is a need for a passive system that removes hydrogen solely using a hydrogen oxidation catalyst, without the need for additional power sources such as heat or electricity.

[0003] Korean Patent Publication No. 10-2013-0082272 discloses a method for manufacturing a Pt / TiO2 catalyst for hydrogen removal and a method for removing hydrogen using the same. Furthermore, Korean Patent Publication No. 10-2016-0073797 discloses a platinum-based catalyst capable of removing hydrogen at room temperature.

[0004] The present inventors have focused on the problems encountered when applying a ceramic honeycomb coated with a conventional Pt / TiO2 catalyst material for hydrogen removal to oxidize and remove hydrogen at room temperature. As is known, the Pt / TiO2 catalyst material is manufactured in the form of a powder slurry and then processed into a honeycomb structure or applied to the inner wall of an already processed honeycomb molded body for use. However, such a catalyst molded body cannot avoid the problems of heat generation due to the hydrogen oxidation reaction, especially at high concentrations of hydrogen, the problem of water toxicity as a byproduct, and the cost problem due to the expensive platinum. To solve the above problems, the present inventors propose a high-concentration slip hydrogen removal catalyst molded body in which different contents of precious metal are loaded in each zone.

[0005] The present invention relates to a catalyst molded body for high-concentration slip hydrogen removal, wherein catalyst slurries having different precious metal compositions are applied to each of multiple zones of the honeycomb molded body. Although not limited thereto, the multiple zones of the catalyst molded body according to the present invention are characterized in that they are composed of a front zone and a rear zone, and the precious metal content of the catalyst slurry applied to the front zone is lower than the precious metal content of the catalyst slurry applied to the rear zone. In addition, the total amount of precious metals included in the catalyst slurries applied to the front zone and the rear zone of the catalyst molded body according to the present invention is characterized in that they are determined at a point where the calorific value of the honeycomb molded body is minimized. For example, the precious metal included in the catalyst slurry applied in the present invention is platinum, and the total amount of precious metals is 50 to 70 g / ft at which the calorific value of the honeycomb molded body is minimized. 3 It can be. The catalyst molded body of the present invention can be used particularly for removing high-concentration hydrogen having a concentration of slip hydrogen of 4% by volume or more, and can be installed at the rear end of a hydrogen tank or the rear end of a fuel cell or other hydrogen-using device to oxidize and remove high-concentration hydrogen.

[0006] The catalyst molded body for high-concentration slip hydrogen removal according to the present invention can reduce the problem of heat generation due to high-concentration hydrogen oxidation reaction, the problem of water toxicity as a byproduct, and the expensive platinum by applying zone coating.

[0007] Figure 1 shows the catalyst temperature and slip concentration (%) according to the loading amount of precious metal platinum.

[0008] Figure 2 shows catalyst molded bodies of various cell densities (total platinum loading (60 g / ft)) applied to high concentration hydrogen oxidation systems of 20 and 30 vol%. 3 )) shows the catalyst temperature and hydrogen conversion rate.

[0009] In the present invention, high-concentration hydrogen refers to a case where the hydrogen concentration is 4 vol% or more, and this is hydrogen that can spontaneously ignite. The term "whole coating" is defined as coating the entire inner wall or cell wall of a molded body with a catalyst slurry of the same composition, and is used to contrast with zone coating, which coats each section of the molded body with a catalyst slurry of a different composition. In the present invention, the terms "catalyst body" and "catalyst molded body" are used interchangeably, and refer to an article in which a catalyst material or a catalyst composition is molded into a certain shape or applied to a certain shape of a carrier.

[0010] First, the inventors of the present invention focused on the issue of moisture toxicity as a factor causing catalyst deterioration in hydrogen oxidation catalysts. Specifically, in conventional hydrogen oxidation catalysts, it was understood that catalytic reactivity increases as the precious metal loading increases. However, the inventors of the present invention discovered that when the precious metal loading exceeds a certain level, moisture toxicity occurs due to moisture, an oxidation byproduct.

[0011] Figure 1 shows the catalyst temperature and slip concentration (%) according to the platinum loading amount of precious metal, with the platinum loading amount being 50 to 70 g / ft. 3 , preferably 60g / ft 3 At this point, the catalytic reactivity rapidly decreases. This indicates catalyst deterioration due to moisture toxicity, which leads to a decrease in reactivity. Consequently, the oxidation reaction heat generation and the catalyst downstream temperature decrease. Therefore, to minimize the problem of catalytic reactivity reduction due to moisture, a byproduct of hydrogen oxidation, an optimal noble metal loading amount exists, and this loading amount is proposed to be the point where the catalytic heat generation is minimal.

[0012] To address the high cost of catalyst production by reducing the amount of expensive platinum used, the inventors of the present invention performed zone coating on honeycomb molded bodies. Specifically, by performing zone coating with less precious metal than the optimal precious metal loading applicable to a monolithically coated molded body, the inventors were able to achieve optimal hydrogen oxidation reaction while simultaneously addressing the cost issue.

[0013] A honeycomb molded body is a catalyst material carrier in which a plurality of penetrating cells having a roughly square cross-section are regularly formed along the length direction, and each penetrating cell is separated from one another by a thin cell wall. A catalyst material is coated or supported on the surface or inside the pores of the cell walls, and the density of the cells is expressed in cpsi (cell per square inch). When arranging a honeycomb molded body in the direction of hydrogen inflow, the part of the molded body into which hydrogen flows is defined as a front zone, and the part where moisture, a byproduct after hydrogen oxidation, is discharged is defined as a rear zone. In the present invention, a zone is a part of the entire molded body from the front end to the rear end divided into several sections, and although multiple zones may exist, in order to avoid complicated explanation, only two front and rear zones are formed, and slurries having different precious metal compositions are applied to the two zones. According to the present invention, it was surprisingly found that substantially the same hydrogen oxidation effect can be obtained by loading precious metals of different compositions in the front and rear ends of the molded body while reducing the precious metal loading content compared to the case where precious metals of the same composition are loaded throughout the entire cell wall of the molded body. Specifically, it was found that 60 g / ft of precious metals were loaded across the front cell wall of the molded body. 3 Platinum is loaded and 60g / ft is applied across the cell wall at the rear end of the molded body. 3 Honeycomb molded body in which platinum is loaded, i.e. 60 g / ft throughout the entire molded body cell wall section 3The hydrogen oxidation capacity of the honeycomb molded body containing platinum and 30 g / ft across the shear zone cell wall of the molded body 3 Platinum is loaded and 60g / ft is applied across the cell wall of the rear section of the molded body. 3 The hydrogen oxidation capacity of the honeycomb molded body on which platinum was loaded was practically the same. In addition, 60 g / ft was measured over the entire cell wall of the molded body. 3 The hydrogen oxidation capacity of the honeycomb molded body on which platinum is loaded, and 10 g / ft3 of platinum is loaded across the front cell walls of the molded body and 60 g / ft3 across the rear cell walls of the molded body. 3 The hydrogen oxidation capacity of the honeycomb molded body containing platinum was also substantially the same.

[0014] Shear Pt loading (g / ft) 3 ) Rear end Pt loading (g / ft) 3 )HIDEN mass H 2 Detection (I)60604.97e -12 30604.56e -12 10604.92e -12

[0015] The present inventors have confirmed that the problem of moisture toxicity caused by the oxidation reaction of high-concentration hydrogen of 4 vol% or more can be solved through zone coating of a honeycomb molded body. That is, while conventional oxidation catalysts are designed to quickly initiate the catalytic function and oxidation reaction by increasing the noble metal loading in the front zone, the molded body according to the present invention, on the contrary, proposes a system in which the noble metal loading in the front section is designed to be minimal to minimize the amount of H2O generated in the catalyst front zone in order to prevent moisture toxicity occurring under high-concentration H2 oxidation conditions, and a higher content of noble metal is loaded in the rear section than in the front section to compensate for this. Meanwhile, since the higher the density of honeycomb cells, the lower the heat generation at the exit of the molded body (Fig. 2), by optimizing the density of the zone-coated molded body, a system can be manufactured in which the heat generation at the exit is reduced compared to an integrally coated molded body. Example

[0016] Similar to the method disclosed in Patent Publication No. 10-2013-0082272, Pt / Al2O3 powder was prepared, then a slurry was formed, and the slurry was applied to the cell walls of the front and rear zones of a honeycomb molded body using a conventional coating method to produce a high-concentration slip hydrogen removal catalyst molded body. Table 1 summarizes the hydrogen oxidation capacity of molded bodies with different precious metal loadings applied to the front and rear zones.

[0017] Experimental example

[0018] In order to evaluate the hydrogen removal ability of the Pt / Al2O3 catalyst molded body according to the present invention, mixed gases containing moisture at a relative humidity of 100% (based on 25°C) and hydrogen by volume of 20 and 30%, respectively, were injected into a device in which the catalyst molded body was inserted, and the initial reaction temperature was maintained at 25°C, and the reaction was carried out at a space velocity of 120,000 / hour. The composition of the exhausted gas was measured using gas chromatography, and the temperature change at the rear end of the catalyst due to the heat generated by the hydrogen oxidation reaction was measured (Fig. 2).

Claims

1. A catalyst molded body for high-concentration slip hydrogen removal, wherein catalyst slurries having different precious metal compositions are applied to each of multiple zones of a honeycomb molded body.

2. A catalyst molded body in paragraph 1, wherein the multi-zone is composed of a front zone and a rear zone.

3. In the second paragraph, a catalyst molded body in which the precious metal content of the catalyst slurry applied to the front section is lower than the precious metal content of the catalyst slurry applied to the rear section.

4. In the third paragraph, a catalyst molded body, wherein the total amount of precious metal included in the catalyst slurries applied to the front section and the rear section is determined at a point where the heat generation of the honeycomb molded body is minimized.

5. A catalyst molded body in paragraph 4, wherein the precious metal is platinum.

6. In paragraph 4, the total amount of the precious metal is 50 to 70 g / ft 3 In, catalyst molded body.

7. A catalyst molded body according to any one of claims 1 to 6, wherein the concentration of the slip hydrogen is 4% or more.

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