KR20100093823A - Method for catalysts coating on microchannels - Google Patents

Abstract

PURPOSE: The coating layer can be formed uniformly in comparison with the catalyst layer using only the nickel-based catalyst on the micro channel. In the point of the coating solution, adjustment easies. It has no the phenomenon that the catalyst layer is cracked after the case of reacting methanol-reformate or chafing. CONSTITUTION: The catalyst-coating method at the micro channel of micro reactor comprises next steps. The step forming oxide layer in the top of the substrate having micro channel. With step of filling the micro channel it spills and it puts the catalyst-coating liquid in the micro channel of substrate. Step forming the catalyst layer in the inner wall of the micro channel by the surface tension of the solvent in which substrate is desiccated and which is included in the catalyst-coating liquid.

Description

Method for catalysts coating on microchannels

The present invention is a catalyst layer using only a Nigel-based catalyst by forming a catalyst coating solution by adding a mixture of acrylic acid or acrylic acid / acetic acid to a nickel-based catalyst used for liquefied natural gas steam reforming reaction on the inner wall of a microchannel made of silicon. Compared to the micro-channel catalyst coating method of the micro reactor capable of uniformly forming a coating layer in the micro-channel as compared.

Among the fuel cells that are in the spotlight as an alternative energy source of the future, polymer electrolyte membrane fuel cells (PEMFCs) have high energy density because they directly use hydrogen as a fuel. In order to supply hydrogen to the PEMFC, a fuel processing apparatus capable of generating hydrogen from hydrocarbons and thus removing carbon monoxide generated at the same time is essential. In particular, liquefied natural gas has a merit as a home PEMFC fuel because of the well-established infrastructure provided to the home, and the miniaturization of the fuel processing device is essential for the practical application of the home PEMFC power supply.

Based on the development of MEMS (micro electro mechanical system) technology, semiconductor processing technology and micro process technology, micro reactors using materials such as silicon, ceramic and stainless steel have been manufactured. . These microreactors exhibit a high energy density at the same volume because of their greater surface area-to-volume ratio than conventional reactors. However, one of the problems in the fabrication of microreactors is the loading of catalysts. When the catalyst is loaded in a micro reactor having a micro flow path, the catalyst activity decreases due to the pressure drop of the reaction gas. Therefore, the method of loading the catalyst in the fine flow path may be said to be the most efficient coating the catalyst on the inner wall of the flow path.

Accordingly, the present applicant and the inventor through the Republic of Korea Patent No. 10-0832040 through platinum (Pt), ruthenium (Ru), rhodium (Rh), nickel (Ni), cobalt (Co), iron (Fe), gold (Au ), A micro-reactor formed with a catalyst layer in the microfluidic path by filling-drying manganese (Mn), chromium (Cr), iridium (Ir), copper (Cu), zinc (Zn), magnesium (Mg) and alloys thereof The preparation method of the present invention was presented.

However, in the case of using a nickel-based catalyst for the microreactor for liquefied natural gas steam reforming reaction in the microreactor of the Republic of Korea Patent No. 10-0832040, the viscosity is low, and the side wall in the microchannel is about 25 μm, and the upper and lower walls are about 10 μm. There remains a problem that is difficult to control so that the coating layer of μm is uniformly formed.

Accordingly, the present inventors have invented a method for coating a catalyst in a micro flow path that can be uniformly coated with a viscosity control using a nickel-based catalyst for a micro reactor for liquefied natural gas steam reforming reaction.

Therefore, the present invention forms a catalyst coating solution by adding a mixture of acrylic acid or acrylic acid / acetic acid to a nickel-based catalyst used for liquefied natural gas steam reforming reaction on the inner wall of a micro-channel of a micro reactor made of silicon. It is to provide a micro channel catalyst coating method of a micro reactor capable of uniformly forming a coating layer in the micro channel compared to the used catalyst layer.

According to an aspect of the present invention, there is provided a method of forming an oxide layer on a substrate having a microchannel, filling the microchannel by pouring a catalyst coating solution into the microchannel of the substrate, and drying the substrate. In the conventional micro-reactor manufacturing method comprising the step of forming a catalyst layer only on the inner wall of the fine flow path by the surface tension of the solvent contained in the catalyst coating liquid,

The catalyst coating solution is characterized by adding a mixture of acrylic acid or acrylic acid and acetic acid to the pulverized nickel-based catalyst, distilled water.

Preferably, the nickel-based catalyst is characterized in that the nickel-alumina hybrid catalyst.

Preferably, the nickel-based catalyst and distilled water are mixed at a ratio of 1:10 to 1: 2, and the acrylic acid is mixed at a ratio of 1: 0.05 to 1: 0.2 with respect to the nickel-based catalyst.

Preferably, the nickel-based catalyst and distilled water are mixed at a ratio of 1: 4, and the acrylic acid is mixed at a ratio of 1: 0.1 with respect to the nickel-based catalyst.

Preferably, the nickel-based catalyst and distilled water are mixed at a ratio of 1:10 to 1: 2, and the acrylic acid / acetic acid mixture is mixed at a ratio of 1: 0.1 to 1: 0.3 with respect to the nickel-based catalyst. It features.

Preferably, the nickel-based catalyst and distilled water are mixed at a ratio of 1: 4, and the acrylic acid / acetic acid mixture is mixed at a ratio of 1: 0.2 with respect to the nickel-based catalyst.

Since the micro channel catalyst coating method of the microreactor of the present invention mixes a nickel-based catalyst and a mixture of acrylic acid or acrylic acid / acetic acid, the coating layer may be uniformly formed in the micro channel as compared with the catalyst layer using only the nickel-based catalyst. It has the advantage of easy viscosity control.

In addition, in the case of methanol reforming reaction using a micro reactor having a catalyst layer, it can be seen that the adhesion of the catalyst layer to the walls of the micro-channel is excellent even after the reaction without cracking or peeling off the catalyst layer.

Hereinafter, with reference to the accompanying drawings will be described the present invention in detail.

First, as shown in Figure 1 as a micro reactor for the liquefied natural gas steam reforming reaction, a micro reactor having a width of 600 μm, a depth of 240 μm, and a length of 37.5 cm is manufactured.

The method of manufacturing such a micro-reactor is shown in detail in Korean Patent No. 10-0832040 registered in advance by the present inventors, and thus a detailed description thereof is omitted.

In the micro reactor used for the liquefied natural gas steam reforming reaction, a silicon oxide film (SiO ₂ ) is formed in a fine flow path, and a catalyst layer is formed in the silicon oxide film. The silicon oxide film may be formed by placing the manufactured micro reactor in a blast furnace (furnace) by heat treatment at 300 ℃ for 3 hours.

On the other hand, the catalyst layer is made of a solid slurry of the coating liquid in the form of a liquid coating and formed by a fill-dry method (fill and dry coating). At this time, the catalyst layer is physical vapor deposition (chemical vapor deposition), chemical vapor deposition (chemical vapor deposition), anodic oxidation method (anodic oxidation method), packing (sol-gel method), dip coating (dip) It can also be formed by coating and wash coating.

The coating solution is a nickel-based catalyst, distilled water and acrylic acid or a mixture of acrylic acid / acetic acid as a binder is added. The coating liquid is a nickel-based catalyst is preferably a nickel-alumina hybrid catalyst, and is used in powder form. In addition, after mixing the catalyst, distilled water and the binder and put in a ball mill to prepare a catalyst coating liquid in the form of slurry through ball milling for about 5 days using a ball mill (ball miller).

The nickel-based catalyst and distilled water are mixed in a ratio of 1:10 to 1: 2, preferably 1: 4, and acrylic acid is 1: 0.05 to 1: 0.2, preferably 1: 0.1, in proportion to the nickel-based catalyst. The mixture of acrylic acid / acetic acid is mixed in a ratio of 1: 0.1 to 1: 0.3, preferably 1: 0.2, with respect to the nickel-based catalyst. At this time, if the mixed amount of distilled water is small or the addition amount of the mixture of acrylic acid and acrylic acid / acetic acid is high, the viscosity of the coating liquid becomes high, and the catalyst layer becomes thick and nonuniform. If the addition amount of the mixture of acetic acid is low, the concentration of the coating layer is low, there is a problem that the catalyst layer is small.

Meanwhile, in the present embodiment, only distilled water was used as a solvent for preparing the catalyst coating liquid, but if necessary, any one selected from the group consisting of alumina sol, silica sol, isopropyl alcohol (IPA), acetic acid, and polyvinyl alcohol (PVA) was used. One may be added.

The catalyst coating liquid thus prepared is poured into the microchannel of the micro reactor, thereby filling the channel with the catalyst coating liquid.

Subsequently, the catalyst coating liquid inside the microchannel is dried for 2 to 5 days at room temperature so as to slowly dry to form a catalyst layer. In order to completely dry and increase adhesion between the catalyst layer and the adhesive layer, a heat treatment process may be performed at 300 ° C. for 3 hours to form the catalyst layer only on the silicon oxide film, which is an adhesive layer on the inner wall of the microchannel.

≪ Example 1 >

Nickel-based catalyst, distilled water and acrylic acid were prepared in a catalyst coating solution mixed with a ratio of 1: 4: 0.1, respectively, and the shear rate and viscosity thereof are shown in FIG. 2. In addition, after filling the catalyst coating liquid into the inside of the flow path of the liquefied natural gas steam reforming reaction having a micro-flow path having a width of 600㎛, 240㎛ depth and a length of 37.5cm (fill and dry) The catalyst layer was formed by coating), and the cross section of the catalyst coating layer was observed by electron scanning microscope (FESEM), and is shown in 3a.

<Example 2>

Nickel-based catalysts, distilled water and acrylic acid / acetic acid were prepared in a catalyst coating solution mixed at a ratio of 1: 4: 0.2, respectively, and the shear rates and the viscosity thereof are shown together in FIG. 2. In addition, after filling the catalyst coating liquid into the inside of the flow path of the liquefied natural gas steam reforming reaction having a micro-flow path having a width of 600㎛, 240㎛ depth and a length of 37.5cm (fill and dry) The cross section of the catalyst coating layer was observed with an electron scanning microscope (FESEM) and shown in 3b.

Comparative Example 1

A catalyst coating solution was prepared in which only a nickel-based catalyst and distilled water were mixed at a ratio of 1: 4. The shear rate and viscosity thereof were also shown in FIG. 2.

Comparative Example 2

A nickel-based catalyst, distilled water, and acetic acid were mixed at a ratio of 1: 4: 0.1, respectively, to prepare a catalyst coating solution, and the shear rate and viscosity thereof were also shown in FIG. 2. In addition, after filling the catalyst coating liquid into the inside of the flow path of the liquefied natural gas steam reforming reaction having a micro-flow path having a width of 600㎛, 240㎛ depth and a length of 37.5cm (fill and dry) The catalyst layer was formed by coating), and the cross section of the catalyst coating layer was observed with an electron scanning microscope (FESEM), and is shown in 3c.

Comparative Example 3

A catalyst coating solution was prepared in which only a nickel-based catalyst and distilled water were mixed in a ratio of 1: 2. The micro-coupling for liquefied natural gas steam reforming having a microchannel having a width of 600 μm, a depth of 240 μm, and a length of 37.5 cm After the catalyst coating liquid was introduced into the flow path of the reactor, the catalyst layer was formed by fill and dry coating, and the cross section of the catalyst coating layer was observed by electron scanning microscope (FESEM) and shown in 3d.

Comparative Example 4

A catalyst coating solution was prepared in which only a nickel-based catalyst and distilled water were mixed at a ratio of 3: 4. After the catalyst coating liquid was flowed into the reactor passage, a catalyst layer was formed by fill and dry coating, and the cross section of the catalyst coating layer was observed in an electron scanning microscope (FESEM), and is shown in 3e.

<Experiment Result>

As shown in FIG. 2, the catalyst coating solution mixed with acetic acid or acetic acid / acetic acid of Example 1 and Example 2 is a catalyst coating solution containing only distilled water of Comparative Example 1 and a nickel-based catalyst of distilled water and ace It can be seen that the viscosity is increased compared to the catalyst coating liquid mixed with the tic acid.

In particular, it can be seen that the catalyst coating liquid mixed with acetic acid / acetic acid maintains the best viscosity at regular intervals to form the coating layer despite the increased amount.

In addition, as shown in Figures 3a to 3e, the catalyst coating solution mixed with acetic acid or acetic acid / acetic acid of Examples 1 and 2 formed a coating layer of a constant thickness, but the nickel-based catalyst and distilled water of Comparative Example 2 And the catalyst coating liquid mixed with acetic acid has a weak viscosity almost no thickness of the coating layer. In addition, as in the case where the mixing ratio of the nickel-based catalyst and distilled water of Comparative Example 3 and Comparative Example 4 is 1: 2, 3: 4, the viscosity increases as the amount of the nickel-based catalyst powder increases in the slurry, and accordingly, the thickness of the catalyst layer Thickens and increases further, it can be seen that the flow is blocked.

Although the embodiments of the present invention have been described as described above, the present invention is not limited to the above embodiments, and it is apparent that many modifications can be made by those skilled in the art within the technical spirit of all the related fields. Do.

1 is a cross-sectional photograph of a cross section of a micro-reactor microchannel according to the present invention with an electron scanning microscope (FESEM).

2 is a graph measuring the slurry viscosity of Examples 1 and 2 and Comparative Examples 1 and 2 according to the present invention.

3A is a cross-sectional photograph of a cross section of a catalyst coating layer in which acrylic acid is added to a nickel-based slurry according to Example 1 of the present invention with an electron scanning microscope (FESEM).

Figure 3b is a cross-sectional photograph of a cross section of the catalyst coating layer added acrylic acid / acetic acid to the nickel-based slurry in accordance with Example 2 of the present invention with an electron scanning microscope (FESEM).

3c is a cross-sectional photograph of a cross section of a catalyst coating layer in which acetic acid is added to a nickel-based slurry in accordance with Comparative Example 2 of the present invention with an electron scanning microscope (FESEM).

3d is a cross-sectional photograph of a cross section of a catalyst coating layer in which acetic acid is added to a nickel-based slurry in accordance with Comparative Example 2 of the present invention with an electron scanning microscope (FESEM).

3E is a cross-sectional photograph of a cross section of a catalyst coating layer in which acetic acid is added to a nickel-based slurry according to Comparative Example 2 of the present invention with an electron scanning microscope (FESEM).

Claims (7)

Forming an oxide layer on a substrate having a microchannel, filling the microchannel by pouring a catalyst coating solution into the microchannel of the substrate, and drying the substrate to reduce the surface tension of the solvent contained in the catalyst coating solution. In the conventional micro-reactor manufacturing method comprising the step of forming a catalyst layer only on the inner wall of the fine flow path, The catalyst coating solution is a catalyst coating method in a fine flow path, characterized in that the addition of a mixture of acrylic acid or acrylic acid and acetic acid to the crushed nickel-based catalyst, distilled water. The method of claim 1, wherein the nickel-based catalyst is a nickel-alumina hybrid catalyst. The method of claim 1, wherein the nickel-based catalyst and distilled water are mixed at a ratio of 1:10 to 1: 2, and acrylic acid is mixed at a ratio of 1: 0.05 to 1: 0.2 with respect to the nickel-based catalyst. Catalyst coating method in a fine flow path. The method of claim 3, wherein the nickel-based catalyst and distilled water are mixed at a ratio of 1: 4, and acrylic acid is mixed at a ratio of 1: 0.1 with respect to the nickel-based catalyst. . The method of claim 1, wherein the nickel-based catalyst and distilled water are mixed at a ratio of 1:10 to 1: 2, and the acrylic acid / acetic acid mixture is at a ratio of 1: 0.1 to 1: 0.3 with respect to the nickel-based catalyst. Catalyst coating method in a fine flow path, characterized in that mixed. The method of claim 5, wherein the nickel-based catalyst and distilled water is mixed in a ratio of 1: 4, acrylic acid / acetic acid mixture is mixed in a ratio of 1: 0.2 with respect to the nickel-based catalyst fine passage Catalyst coating method in The method of claim 1, wherein the catalyst layer is formed by a fill-drying method.

Images