KR100807730B1 - Enhancement method of adhesion between the surface of microreactor and catalyst particles - Google Patents

Abstract

The present invention relates to a method of increasing adhesion between a substrate and a catalyst, and more particularly, in the step of attaching a catalyst of a different material to the substrate, removing contaminants on the surface of the substrate, It relates to a method of increasing the adhesion between the substrate and the catalyst comprising the step of forming the same material as the adhesive layer between the interface.

In the present invention, by using an atomic vapor deposition (ALD) or chemical vapor deposition (CVD) on the surface of the substrate to form an adhesive layer of the same material as the catalyst or a material having the same surface characteristics as the catalyst at the interface between the substrate and the catalyst as an adhesive layer Since the adhesion can be increased to form a thin film of a desired component uniformly to a desired thickness regardless of the type or shape of the substrate, it is very advantageous for forming an adhesive layer.

Description

Enhancement method of adhesion between the surface of microreactor and catalyst particles}

1 is a conceptual diagram showing a process of forming Al ₂ O ₃ and bonding with a metal surface by atomic layer deposition (ALD)

FIG. 2A is a view showing a bonding layer of an Al ₂ O ₃ buffer layer formed on a surface of a metal support, and a catalyst-alumina sol mixture attached to the bonding layer.

Figure 2b is a diagram showing a state in which the catalyst-alumina sol mixture is attached to the surface of the metal support.

FIG. 3 is a scanning electron microscope (SEM) photograph of a stainless steel microchannel to which a catalyst is attached without an Al ₂ O ₃ adhesive layer.

FIG. 4 is a scanning electron microscope (SEM) photograph of a stainless steel microchannel to which an Al ₂ O ₃ adhesive layer is formed by ALD and then to which a catalyst is attached.

5 is a substrate-catalyst cross-sectional scanning electron microscope (SEM) photograph of a catalyst-attached sample after forming an Al ₂ O ₃ adhesive layer by ALD method

Figure 6 is a substrate-catalyst cross-sectional scanning electron microscope (SEM) photograph attached catalyst without Al ₂ O ₃ adhesive layer

Figure 7 (a) (b) is a graph showing the change over time of the methanol-aqueous conversion of the micro reactor with or without the Al ₂ O ₃ adhesive layer.

The present invention relates to a method of increasing adhesion between a substrate and a catalyst, and more particularly, in the step of attaching a catalyst of a different material to the substrate, removing contaminants on the surface of the substrate, It relates to a method of increasing the adhesion between the substrate and the catalyst comprising the step of forming the same material as the adhesive layer between the interface.

In the present invention, the substrate means a structure in which the catalyst is present in the reactor, and the substrate may be processed into various shapes and may be made of various materials. On the other hand, the substrate is not only a structure in which the catalyst is present inside the reactor, but the reactor itself may be one substrate.

The catalyst consists of the active ingredient and the carrier on which the active ingredient is carried. That is, since the active material is evenly distributed in small amounts in a carrier having a large surface area such as alumina, silica, titania, zirconia, etc., most of the catalyst is occupied by the carrier. Therefore, if the catalyst is to be attached to the surface of the substrate, adhesion between the carrier of the catalyst and the surface of the substrate is very important.

As mentioned above, the substrate may be processed into various shapes and may have various materials, but when the catalyst and the surface properties of the inorganic components are different, it is difficult to attach the catalyst. For example, when a catalyst using alumina (Al ₂ O ₃ ) as a carrier is attached to a surface of a substrate made of stainless steel, the catalyst may not be attached to the substrate because the material is different between the catalyst and the substrate.

As such, when the substrate and the catalyst are made of different materials or have different surface properties, the surface of the substrate support is treated with an acid or a base to remove contaminants, and the catalyst is dispersed in an alumina sol to dissolve the catalyst-alumina sol. sol) mixture, and the catalyst-alumina sol mixture is applied to the desired substrate surface, dried and calcined to increase the adhesion between the substrate and the catalyst.

However, the adhesion between the substrate and the catalyst is not strong in such an attachment method, so that the catalyst and the substrate are easily separated from each other when used at a high temperature or for a long time. In order to prevent separation between the catalyst and the substrate, an adhesive layer may be introduced at the interface between the substrate and the catalyst.

In order to introduce such an adhesive layer, when the main component of the catalyst is alumina, an alloy of a special material that forms alumina (Al ₂ O ₃ ) on a metal surface when heat treated at 1000 ° C. may be used (P. Reuse et al., Chem. Eng). J , 101 (2004) 133). However, if the main component of the catalyst is not Al ₂ O ₃ TiO ₂ , ZrO _2, etc., such a special alloy can not be used. That is, there is a disadvantage that the material of the metal that can be used according to the type of catalyst is very limited.

In addition, vapor deposition using aluminum isopropoxide (Al (OiPr) ₃ ) as a precursor was used to introduce the Al ₂ O ₃ adhesive layer onto the metal substrate when the main component of the catalyst was Al ₂ O ₃ (MT Janicke et. al., J. Catal. , 191 (2000) 282). However, when the surface of the complex metal substrate has an uneven microchannel, it is difficult to uniformly coat the Al ₂ O ₃ thin film on the microchannel surface.

Meanwhile, in order to manufacture a metal monolithic catalyst module consisting of the following three steps in Korean Patent Application No. 2002-0068210 as a related art, 1) forming a metal layer by coating metal particles on the surface of the metal structure, 2) Performing partial sintering of the metal particles at a high temperature in a vacuum or inert atmosphere, 3) firing the metal structure coated with the heat-treated metal particles at a high temperature to form a metal oxide film on the metal particle surface layer to form a metal on the metal structure surface. There is a description of the coating method of the metal oxide layered particle layer and the catalyst attachment method

However, since the prior art forms a metal layer on the surface of the metal structure, and forms a metal oxide on the surface of the metal layer again at high temperature, it is cumbersome to form an adhesive layer on the surface of the metal structure.

In the present invention, in attaching a catalyst of a substance different from a substrate to a substrate, the same surface properties as the catalyst or the same material as the carrier of the catalyst, more preferably the catalyst carrying the active ingredient in the catalyst, are applied to the substrate surface to which the catalyst is attached. It is an object of the present invention to provide a method of increasing adhesion between a substrate and a catalyst which can form a material having an adhesive layer to improve adhesion between the catalyst and the substrate.

In the present invention, by using an atomic vapor deposition (ALD) or chemical vapor deposition (CVD) on the surface of the substrate to form an adhesive layer of the same material as the catalyst or a material having the same surface characteristics as the catalyst at the interface between the substrate and the catalyst as an adhesive layer Since the adhesion can be increased to form a thin film of a desired component uniformly to a desired thickness regardless of the type or shape of the substrate, it is very advantageous for forming an adhesive layer.

In order to achieve the above-mentioned object, the method of increasing adhesion between the substrate and the catalyst of the present invention, in the case of attaching a catalyst of a different material from the substrate to the substrate, more preferably the active ingredient in the catalyst Forming an adhesive layer between the carrier of the supported catalyst and the interface of the substrate with the same material as the carrier of the catalyst or with the same surface properties as the carrier of the catalyst.

In the present invention, the substrate to which the catalyst carrier is attached is a structure in which the catalyst is present in the reactor. In the present invention, the substrate may use a metal support or an inorganic support.

As an example of the substrate in the present invention it may be used a metal support made of any one metal or metal alloy selected from stainless steel, iron, aluminum.

As an example of the substrate in the present invention, any one inorganic support selected from alumina (Al ₂ O ₃ ), silica (SiO ₂ ), titania (TiO ₂ ), zirconia (ZrO ₂ ) may be used.

Most catalysts are made of metals such as platinum, gold, copper, zinc, or metals with active materials evenly distributed in small amounts (less than 10wt%) on carriers with large surface areas such as alumina, silica, titania, zirconia, etc. Most of the catalyst is occupied by the carrier. Therefore, if the catalyst is to be attached to the surface of the substrate, adhesion between the carrier of the catalyst and the surface of the substrate is very important.

In the present invention, any catalyst can be used as long as it can be used by being attached to the surface of the substrate. As an example of such a catalyst in the present invention, platinum-supported alumina (Pt / Al ₂ O ₃ ), copper and zinc-supported alumina (Cu / ZnO / Al ₂ O ₃ ), gold-supported titania (Au / TiO ₂₎ ), Silica loaded with platinum (Pt / SiO ₂ ), alumina loaded with platinum and ruthenium (Pt-Ru / Al ₂ O ₃ ), titania (Pt-Ru / TiO ₂ ) loaded with platinum and ruthenium, Ruthenium-supported silica (Pt-Ru / SiO ₂ ), platinum and palladium-supported alumina (Pt-Pd / Al ₂ O ₃ ), platinum and palladium-supported titania (Pt-Pd / TiO ₂ ), platinum and Any one or more selected from palladium-supported silica (Pt-Pd / SiO ₂ ) may be used.

In the present invention, before forming the adhesive material having the same material or the same surface characteristics as the carrier of the catalyst on the substrate, it is possible to first remove the contaminants of the substrate so that the adhesive layer is better bonded to the substrate.

In this case, the surface of the substrate may be treated with at least one material selected from a base, an acid, or an organic solvent to remove contaminants from the substrate.

As to remove the contaminants, the acid may be any one or more selected from nitric acid (HNO ₃ ), hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ), the base is sodium hydroxide (NaOH) aqueous solution, potassium hydroxide (KOH ) Any one or more selected from an aqueous solution and ammonia water (NH ₄ OH) may be used, and the organic solvent may be selected from benzene (C ₆ H ₆ ), toluene (CH ₃ C ₆ H ₅ ), and hexane (C ₆ H ₁₄ ). You can use more than one.

In the present invention, the adhesive layer formed on the surface of the substrate from which the contaminant is removed and the catalyst is attached is formed of the same material or catalyst as the carrier of the catalyst attached to the substrate by using atomic vapor deposition (ALD) or chemical vapor deposition (CVD). It can be carried out to form a material having the same surface properties as the carrier.

In this case, when the carrier of the catalyst adhered to the substrate is alumina, an alumina may be formed as an adhesive layer on the portion where the catalyst is adhered to the surface of the substrate, and when the carrier of the catalyst adhered to the substrate is titania (TiO ₂ ), Titania (TiO ₂ ) may be formed as an adhesive layer on a portion to which the catalyst is bonded.

In the present invention, the adhesive layer formed on the surface of the substrate may be formed by using atomic vapor deposition (ALD) or chemical vapor deposition (CVD), as mentioned above, wherein atomic vapor deposition (ALD) or chemical vapor deposition ( CVD) conditions can be adjusted so that the thickness of the adhesive layer formed on the surface of the substrate is 1 to 100 nm.

On the other hand, if an adhesive layer is formed on the surface of the substrate with the same material as the carrier of the catalyst or the same material with the surface of the catalyst, the catalyst is coated on the surface of the substrate at high temperature and then calcined at high temperature to improve the adhesion between the catalyst and the substrate. Can be improved. At this time, after the catalyst is coated on the substrate, the firing conditions may be adjusted differently according to the catalyst, and may be generally performed at a temperature of 300 to 700 ° C. for 5 to 15 hours.

Hereinafter, the content of the present invention will be described in detail through examples and test examples. However, these are intended to explain the present invention in more detail, and the scope of the present invention is not limited thereto.

Example 1 Adhesion of Catalysts Supported with Copper and Zinc on Alumina on Stainless Steel Surface

(1) A metal support of stainless steel was used as a support to which the catalyst was attached. The stainless surface was etched to form an uneven microchannel, and the inside of the stainless channel was treated with an acid, a base, or a solvent to remove contaminants present on the stainless steel surface.

(2) Adhesion layer of Al ₂ O ₃ thin film is formed on the surface of micro flow path of stainless steel by ALD method using trimethyl aluminum (TMA, Al (CH ₃ ) ₃ ) and water (H ₂ O) as precursor It was.

At this time, the ALD method using trimethyl aluminum (TMA, Al (CH ₃ ) ₃ ) and water (H ₂ O) as a precursor was used as follows.

The first step is to supply the TMA to the stainless steel surface. The supplied TMA reacts with a hydroxyl group (-OH) present on the metal surface to form an -O-Al bond on the metal surface. The second step is to wash away the excess TMA and byproduct CH ₄ with an inert gas of nitrogen or argon. The third step is to supply water, where the unreacted methyl groups present on the metal surface react with the water that is subsequently supplied to form Al-OH. The fourth step is the same as the second step, using inert gas to remove unreacted water and reaction by-product CH ₄ . Through these four steps, a film having a monolayer or less is formed, which can be defined as one cycle, and the first to fourth steps are shown in FIG. 1.

In the next step, the supplied TMA and Al-OH react to form Al-O-Al bonds. Therefore, the metal surface and the Al ₂ O ₃ thin film as a chemical bond is not a simple physical bond to form the thin film is formed of stainless an adhesive layer on the metal surface a thin film of Al ₂ O 50nm thickness ₃ film thickness hayeoseo adjust the cycle number of the ALD process of the It formed on the steel surface.

The reaction temperature for forming the Al ₂ O ₃ thin film is possible under all conditions between room temperature and 500 ° C., but mainly between 200 and 400 ° C. During the ALD process, the injection amount of TMA, which is an Al source, is controlled by the TMA injection temperature and the injection time.The injection temperature is maintained between room temperature and 30 ℃ for effective use of TMA. For effective use an injection time between 0.1 and 1.0 seconds is sufficient. The process of washing out unreacted TMA or reaction by-product methane using inert gas depends on the washing time using inert gas, and washing within 10 seconds is optimal considering Al ₂ O ₃ thin film formation and productivity. . In this experiment, H ₂ O was used as the oxygen source, and the injection time was set to 1 to 10 seconds for efficient use of H ₂ O. In addition to H ₂ O, various precursors such as ozone (O ₃ ) and isopropyl alcohol can be used. After supplying Oxygen source, it is necessary to wash with inert gas and wash within 10 seconds as described above.

On the other hand, the adhesive layer thickness of the Al ₂ O ₃ thin film formed on the metal surface can be adjusted between 1 _~ 100nm by controlling the cycle number of the ALD process.

(3) Apply a solution containing a mixture of catalyst particles (Cu / ZnO / Al ₂ O ₃ ) and alumina sol to the inside of the fine flow path on the surface of the stainless steel on which the adhesive layer of the Al ₂ O ₃ thin film is formed, and then dried at room temperature to make a gel. Firing at a temperature of 500 ° C. for 12 hours allowed the catalyst-alumina sol to adhere to the stainless steel surface. This is shown in the figure of Figure 2 (a).

As shown in FIG. 2 (a), an alumina buffer layer is formed as an adhesive layer on a stainless surface microchannel, which is a metal support, and a mixture of catalyst-alumina sol is attached to the alumina buffer layer as an adhesive layer, and as a result, the metal support and the catalyst are free from interfacial defects. It can be seen that it is attached well.

<Example 2>

A catalyst in which platinum particles were supported on alumina on the stainless steel surface was adhered to the stainless steel surface in the same manner as in Example 1 except that the catalyst was used as Pt / Al ₂ O ₃ .

Example 3 Catalyst Adhesion Supported with Cracked Titania on Stainless Steel Surface

1) A metal support of stainless steel was used as a support to which the catalyst was attached. The surface of the stainless steel was etched to form an uneven microchannel, and the inside of the microchannel of the stainless steel surface was treated with an acid, a base, or a solvent to remove contaminants present on the surface of the stainless steel.

(2) An adhesive layer of a TiO ₂ thin film was formed in a microchannel on a stainless steel surface by using the ALD method using tetrachloro titanate (TiCl ₄ ) and water (H ₂ O) as precursors.

The first step is to supply TiCl ₄ to the stainless steel surface. The TiCl ₄ is reacted with hydroxyl groups (—OH) present on the metal surface to form -O-Ti bonds on the metal surface. The second step is to wash away the excess TiCl ₄ and reaction by-product hydrogen chloride (HCl) with an inert gas such as nitrogen or argon. The third step is to supply water. The unreacted chloride group (-Cl) present on the metal surface reacts with the supplied water to form Ti-OH. The fourth step is to remove unreacted water and reaction by-product HCl using inert gas as in the second step. Through these four steps, a film of less than a monolayer is formed in the microchannel on the stainless surface, which can be defined as 1 cycle.

In the next step, the supplied TiCl ₄ and Ti-OH react to form Ti-O-Ti bonds on the metal surface. Therefore, the adhesive layer of the TiO ₂ thin film formed on the metal surface and the metal surface is formed by chemical bonding, not merely physical adhesion. The reaction temperature for the formation of the TiO ₂ thin film is possible under all conditions between 500 ° C. and room temperature, but mainly between 200 and 400 ° C. During the ALD process, the Ti source TiTi ₄ injection amount is controlled by the injection temperature and the injection time. The injection temperature is maintained between room temperature and 30 ° C. for effective use of TiCl ₄ and the injection time is 0.1 seconds or more, preferably 0.1 to More than 10 seconds is possible, but an injection time between 0.1 and 1.0 seconds is sufficient for effective use of TiCl ₄ . The process of washing the unreacted TiCl ₄ or the reaction by-product HCl with inert gas depends on the time of washing with inert gas, and washing within 10 seconds is optimal considering the formation of TiO ₂ thin film and productivity. In addition to TiCl ₄ , various precursors such as Ti (OCH (CH ₃ ) ₄ , titanium isopropoxide, Ti (OC ₂ H ₅ ) ₄ , and titanium ethoxide) can be used as the Ti source. In this experiment, H ₂ O was used as the oxygen source, but various precursors such as ozone (O ₃ ) can be used. After supplying oxygen source, it is necessary to rinse with inert gas and wash within 10 seconds as described above. Meanwhile, the thickness of the adhesive layer of the TiO ₂ thin film formed on the metal surface can be controlled between 1 and 100 nm by controlling the cycle number of the ALD process.

(3) After applying a solution containing a mixture of catalyst particles (Au / TiO ₂ ) and titania sol to the inside of the microchannel on the surface of the stainless steel on which the adhesive layer of the TiO ₂ thin film is formed, dried at room temperature to make a gel, and then to 500 ° C. The catalyst-titania sol was adhered to the stainless steel surface by firing at a temperature of 12 hours.

Comparative Example Alumina Catalyst Adhesion to Stainless Steel Surface

 (1) The stainless steel surface was etched to form an uneven microchannel, and the inside of the microchannel on the stainless steel surface was treated with an acid, a base, or a solvent to remove contaminants present on the stainless steel surface.

(2) Dispersing the catalyst alumina particles in an alumina sol to form a catalyst-alumina sol mixture, coating the catalyst-alumina sol mixture in a microchannel on a desired stainless steel surface and drying at room temperature It was then calcined at a temperature of 500 ° C. for 12 hours to attach the catalyst-alumina sol to the stainless steel surface. This is shown in the photograph of Figure 2 (b).

As shown in FIG. 2 (b), the mixture of the catalyst-alumina sol is directly attached to the stainless surface micro-channel, which is the metal support, but the surface of the metal support and the catalyst are different from each other, indicating that interfacial defects are generated around the metal support.

<Test Example 1>

In the comparative example, without forming an adhesive layer, alumina was mainly coated with a catalyst inside a fine flow path on a stainless steel surface, and then measured by scanning electron microscope (SEM), and the results are shown in FIG. 3. It was found that the catalyst did not adhere well to the inside of the micro flow path and was present inside the micro flow path.

Meanwhile, in Example 1, after forming an adhesive layer of an Al ₂ O ₃ thin film by ALD on the surface of stainless steel, the catalyst was coated and observed with SEM. It was observed that the catalyst adhered to the inside of the flow path on the stainless steel surface and adhered well.

<Test Example 2>

Cross sections of the catalyst coated on the stainless steel surfaces of Example 1 and Comparative Example were observed by FIB-SEM, and the results are shown in FIGS. 5 and 6.

FIG. 5 shows that in the embodiment in which an adhesive layer of an Al ₂ O ₃ thin film is formed on a stainless steel surface and the catalyst is bonded, the catalyst has a continuous structure without defects between the catalyst and the metal surface.

FIG. 6 shows that in the comparative example in which a catalyst without an adhesive layer is adhered to a stainless steel surface, bubbles or interface defects are generated on the stainless steel surface as a cross section between the catalyst and the metal surface.

<Test Example 3>

According to Example 1, an adhesion layer of an Al ₂ O ₃ thin film was formed in a microchannel on the surface of a stainless steel, and a methanol / steam reforming was performed after attaching a Cu / ZnO / Al ₂ O ₃ catalyst, which is a methanol-steam reforming catalyst, to the adhesion layer. The reaction was carried out and the results of methanol conversion and hydrogen production were shown in FIG. 7 (a). The reaction temperature was 270 ° C, methanol flow was 0.114 ml / hr, water flow was 0.066 ml / hr, and carrier gas was He. The total flow rate was maintained at 10.0 ml / hr.

According to the comparative example, a Cu / ZnO / Al ₂ O ₃ catalyst, which is a methanol-steam reforming catalyst, was attached to a microchannel on the surface of stainless steel, and then a methanol-steam reforming reaction was carried out. b).

When methanol-steam reforming reaction was carried out by introducing a Cu / ZnO / Al ₂ O ₃ catalyst to the adhesive layer on the surface of the metal support by introducing an adhesive layer of the catalyst on the surface of the metal support, there was no significant difference in methanol conversion rate and hydrogen generation rate over time. (See FIG. 7 (a)).

On the other hand, when the methanol / steam reforming reaction was carried out by attaching a Cu / ZnO / Al ₂ O ₃ catalyst to the surface of the metal support without introducing an adhesive layer of the catalyst onto the surface of the metal support, the methanol conversion rate and hydrogen formation rate were 25% or more than the initial reaction. It was confirmed that the decrease (see Fig. 7 (b)).

This phenomenon was due to the presence or absence of the catalyst firmly adhered to the surface of the metal microfluid. It was confirmed that the introduction of the adhesive layer enhanced the adhesion between the metal support and the catalyst and showed stable reactivity in the microfluidic reactor. It can be seen that the introduction of the adhesive layer strengthens the bond between the catalyst and the surface of the metal support.

As can be seen from the results of the above examples and test examples, in the present invention, when the same material as the catalyst or the same material as the surface property of the catalyst is formed as an adhesive layer on the surface of the substrate and the catalyst is adhered to the adhesive layer, It can be seen that the adhesion of the substrate is improved.

Since the adhesion between the catalyst and the substrate is improved, it can be seen that the reaction efficiency can be increased even in the reaction using the catalyst.

Meanwhile, in the present invention, the substrate may form an adhesive layer regardless of the type or form of the support, such as not only the metal support but also the inorganic support.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be appreciated that it can be changed.

Claims (6)

In attaching a catalyst of a different material to the substrate, The catalyst is attached to the substrate surface which is a metal support made of any one metal or metal alloy selected from stainless steel, iron or aluminum, or the substrate surface which is an inorganic support selected from alumina, silica, titania and zirconia. A method of increasing adhesion between a substrate and a catalyst comprising forming an adhesive layer of the same material as the support of the catalyst or the material having the same surface properties as the support of the catalyst by using an atomic vapor deposition method (ALD) between the support and the interface of the substrate. . delete delete The catalyst of claim 1, wherein the catalyst is Pt / Al ₂ O ₃ , Cu / ZnO / Al ₂ O ₃ , Au / TiO ₂ , Pt / SiO ₂ , Pt-Ru / Al ₂ O ₃ , Pt-Ru / TiO ₂ , Pt-Ru / SiO ₂ , Pt-Pd / Al ₂ O ₃ , Pt-Pd / TiO ₂ , Pt-Pd / SiO ₂ Any one or more selected from the method of increasing the adhesion between the substrate and the catalyst. delete The method of claim 1, wherein the adhesive layer has a thickness of 1 to 100 nm.

Images