KR102271431B1 - A catalyst for liquid phase reforming of biomass, the method for producing the same, and the method for producing high purity hydrogen - Google Patents

Abstract

In the present specification, the support; and an active ingredient supported on a support, wherein the active ingredient includes at least one of platinum (Pt) and cobalt (Co), and a heterogeneous catalyst for liquid phase reforming of biomass is provided. Also provided is a method for producing biogas including hydrogen by liquid-phase reforming reaction of saccharides or saccharide-derived compounds using the same.

Description

Heterogeneous alloy catalyst for liquid-phase reforming of biomass, manufacturing method thereof, and high-purity hydrogen production method using the same

Disclosed herein are a heterogeneous alloy catalyst for liquid phase reforming of biomass, a method for producing the same, and a method for producing hydrogen using a liquid phase reforming reaction of saccharides or a compound derived therefrom using the same.

Korea, which ranks among the top 10 in the world and consumes the most energy, is an energy resource poor country, and most major energy sources depend on imports. In addition, as large amounts of carbon dioxide and environmental pollutants, which cause the greenhouse effect, are released into the atmosphere due to the use of enormous energy sources, the development of next-generation energy sources is required. In order to solve environmental problems such as global warming and to reduce dependence on fossil fuel-based energy sources, hydrogen is in the spotlight as a next-generation energy carrier. In order to produce a large amount of hydrogen, a reforming reaction of natural gas or syngas generated through coal gasification is widely used. At this time, if hydrogen is produced from biomass obtained from sewage sludge or food waste by replacing the existing hydrogen production reaction, the upcycle process is possible and high value-added products can be produced from unused materials, so it is very economical. have.

Various processes may be used to produce biogas (H ₂ , CH _4, etc.) from biomass, but steam reforming, which is a catalytic reaction using high-temperature steam, is the most widely used. However, in this steam reforming process, when biogas is produced from biomass through a series of steam reforming reactions, various reaction by-products such as hydrogen, methane, carbon monoxide and carbon dioxide are produced together, and additional separation is required to use the produced hydrogen as an energy carrier. process is essential. In addition, since the steam reforming reaction proceeds at a high temperature, there is a disadvantage in that the thermal efficiency is relatively low. Accordingly, in recent years, interest in liquid-phase reforming as a method to solve this problem is increasing. Liquid-phase reforming is a catalytic reaction that proceeds at a low temperature of 300 degrees or less, and can convert biomass from a liquid phase reactant at high pressure. In particular, when biomass dispersed in aqueous solution is applied to hydrogen production through liquid phase reforming, carbon monoxide, which may be generated as a reaction by-product, can be converted into carbon dioxide and hydrogen through a water gas shift (WGS), so fuel cell It is possible to produce hydrogen that does not contain carbon monoxide, which can cause electrode poisoning based on rare metals.

The liquid phase reforming mechanism of biomass involves the selective cleavage of CC, CH, and CO bonds in hydrocarbons by a catalytic reaction. In order to further improve the selectivity of hydrogen, which is an energy carrier, dehydrogenation reaction is used instead of hydrogenation reaction. should be selectively promoted.

In one aspect of the present invention, the steam reforming reaction, which is a catalytic reaction using high-temperature steam using the liquid phase reforming reaction, requires separation of various reaction by-products through an additional separation process, and the thermal efficiency is relatively low because it proceeds at a high temperature. want to solve

In one embodiment according to the present invention to achieve the above object, a support; and an active ingredient supported on a support, wherein the active ingredient includes at least one of platinum (Pt) and cobalt (Co), and provides a heterogeneous alloy catalyst for liquid phase reforming of biomass.

In an exemplary embodiment, the active ingredient may be a platinum (Pt) and cobalt (Co) alloy.

In an exemplary embodiment, the active ingredient is a heterogeneous alloy catalyst, characterized in that represented by the formula (1).

[Formula 1]

Pt _x Co _y

(where 1<x<4 and 1<y<4)

In an exemplary embodiment, the molar ratio of platinum (Pt): cobalt (Co) may be 1:4 to 4:1.

In an exemplary embodiment, the active ingredient may be in an amount of 1 to 20 wt% based on the total mass of the heterogeneous alloy catalyst.

In an exemplary embodiment, the platinum (Pt) may be located on the outermost surface of the catalyst.

In an exemplary embodiment, the heterogeneous catalyst may include a first region in which platinum (Pt) is present and a second region in which cobalt oxide (CoO) is present on the surface.

In an exemplary embodiment, the surface composition (at%) of the heterogeneous catalyst may include 20 to 80% of Pt and 20 to 80% of Co when the composition is analyzed by an EDS elemental analyzer.

In an exemplary embodiment, the support may include Al ₂ O ₃ or SiO ₂ .

In an exemplary embodiment, the heterogeneous alloy catalyst may further include an oxide film located on the surface of the active ingredient.

One embodiment according to the present invention, the step of supporting the active ingredient on a support; and reducing and activating the active ingredient, wherein the active ingredient includes at least one of platinum (Pt) and cobalt (Co), and provides a method for preparing a heterogeneous alloy catalyst.

In an exemplary embodiment, the supporting step may be wet impregnation by mixing the dispersion solution and the active ingredient precursor.

In an exemplary embodiment, the activation step may be to change the chemical properties of the surface of the heterogeneous alloy catalyst by adjusting the reducing conditions including the activation temperature or the atmosphere gas composition.

In an exemplary embodiment, the activation step may be reduction at a temperature of 300 to 500 °C for 2 to 5 hours.

In an exemplary embodiment, the passivation step may be performed in a gas atmosphere containing oxygen and argon.

One embodiment according to the present invention, i) through the reaction of the heterogeneous alloy catalyst to form carbon monoxide (CO) and hydrogen (H ₂ ) from the liquid phase reactants; And ii) carbon monoxide (CO) and water are reacted to convert to hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) by a water gas shift reaction (Water gas shift); Containing, the heterogeneous alloy catalyst is a support , and a metal catalyst supported on a support, wherein the metal catalyst includes at least one of platinum (Pt) and cobalt (Co).

In addition, one embodiment according to the present invention, i ') methane (CH ₄ ) and carbon dioxide (CO ₂ ) in biogas to react with a heterogeneous alloy catalyst to form a synthesis gas; and ii') converting carbon monoxide (CO) contained in the synthesis gas with water vapor to convert it to _{hydrogen (H 2} ) and carbon dioxide (CO _{2 );} A supported metal catalyst is provided, wherein the metal catalyst includes at least one of platinum (Pt) and cobalt (Co).

In an exemplary embodiment, the heterogeneous alloy catalyst selectively decomposes CC and C—OH bonds included in the liquid phase reactant to form carbon monoxide (CO) and hydrogen (H ₂ ).

In an exemplary embodiment, steps i) and i') may be performed at a temperature of 200 to 300° C. and a pressure of 20 to 50 bar.

In an exemplary embodiment, the liquid reactant may be a liquid mixture in which xylitol or xylose is uniformly dissolved.

In an exemplary embodiment, steps ii) and ii') may be converted through a heterogeneous alloy catalyst.

A reaction having higher hydrogen selectivity may be implemented through a liquid phase reforming reaction of biomass using the heterogeneous alloy catalyst developed according to an embodiment of the present invention. Accordingly, it is possible to produce a greater amount of hydrogen from the same amount of biomass, and it is possible to minimize the separation process for selectively purifying hydrogen from the reaction by-products in the future, so that it is possible to develop an economical process.

In addition, the conversion rate of biomass can be maximized through the liquid-phase reforming system of biomass according to an embodiment of the present invention, and a new process can be developed that can convert unused saccharides into high value-added compounds.

Accordingly, the hydrogen produced using the developed heterogeneous alloy catalyst can be applied to a polymer electrolyte fuel cell (PEMFC) sensitive to carbon monoxide poisoning, etc., and can be utilized in various industrial fields.

1 is a schematic diagram of a liquid phase reforming reactor for hydrogen production using a heterogeneous alloy catalyst (Pt-Co) synthesized according to an embodiment of the present invention.
2 is a flowchart of a method for synthesizing a heterogeneous alloy catalyst (Pt-Co) according to an embodiment of the present invention.
3A and 3B are results of analyzing the crystal structures of a heterogeneous alloy catalyst (Pt-Co) and a homogeneous catalyst (Pt, Co) synthesized according to an embodiment of the present invention using an X-ray diffraction analyzer.
4A and 4B are results of analyzing the properties of the surface of the heterogeneous alloy catalyst (Pt-Co) synthesized according to an embodiment of the present invention using an X-ray photoelectron spectrometer.
5 is a result showing a transmission electron microscope image and elemental analysis of a heterogeneous alloy catalyst (Pt-Co) synthesized according to an embodiment of the present invention.
6a and 6b are liquid phases of xylitol over time using a heterogeneous catalyst (PtCo 5wt%, FIG. 6a) and a heterogeneous catalyst (PtCo 20wt%, FIG. 6b) synthesized according to an embodiment of the present invention; It is the result of reforming change.
7a and 7b are xylose using the homogeneous catalyst (Pt 5wt%, FIG. 7b) and the homogeneous catalyst (Pt 2.5wt%, FIG. 7a) synthesized according to an embodiment of the present invention. It is the result of liquid reforming change.
8a and 8b are xylose using a heterogeneous alloy catalyst (Pt-Co 20wt%, FIG. 8b) and a heterogeneous alloy catalyst (Pt-C0 5wt%, FIG. 8a) synthesized according to an embodiment of the present invention; xylose) is the result of liquid-phase reforming with time.
9 is a liquid-phase reforming result according to 100 hours of xylose using a heterogeneous alloy catalyst (Pt-Co 5wt%) synthesized according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail.

The embodiments of the present invention disclosed in the text are illustrated for the purpose of explanation only, and the embodiments of the present invention may be embodied in various forms and should not be construed as being limited to the embodiments described in the text. .

The present invention is not intended to limit the present invention to a specific disclosed form, but is not intended to limit the present invention to a specific disclosed form, as various changes may be made and may have various forms, and all changes, equivalents or substitutes included in the spirit and scope of the present invention should be understood as including

The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

As used herein, the term “synthesis gas” refers to a mixed gas containing _{hydrogen (H 2} ), carbon monoxide (CO), and carbon dioxide (CO _{2 ) as main components.}

Heterogeneous catalyst for liquid phase reforming of biomass

Accordingly, the present inventors introduced a heterogeneous alloy catalyst for liquid phase reforming of biomass in order to solve the above problems, and applied it to the production of high-purity hydrogen.

One embodiment according to the present invention, a support; and an active ingredient supported on a support, wherein the active ingredient includes at least one of platinum (Pt) and cobalt (Co), and provides a heterogeneous alloy catalyst for liquid phase reforming of biomass.

In one embodiment, the active ingredient may include platinum (Pt) and/or cobalt (Co), for example, platinum (Pt) and cobalt (Co). Specifically, the active component may act as a metal catalyst, for example, Pt or Pt-Co may be supported on a support as a catalyst component.

Also in one embodiment, the active ingredient may include an alloy of platinum (Pt) and cobalt (Co). For example, when platinum (Pt) and cobalt (Co) simply coexist physically rather than as an alloy, the roles of the two metals act separately, so that Co is not active in reforming, and in the case of Pt, it is lower than the Pt-Co alloy. It can show about 20% selectivity. Therefore, when an alloy of platinum (Pt) and cobalt (Co) is included as an active ingredient, it may be effective for a liquid phase reforming reaction for producing high-purity hydrogen. For example, the cobalt (Co) alone may not be active in the biomass liquid phase reforming reaction, for example, the xylose liquid phase reforming reaction, and platinum (Pt) may have less activity than the alloy catalyst. Therefore, the heterogeneous catalyst for liquid phase reforming of biomass according to an embodiment of the present invention may be effective for liquid phase reforming by including an alloy of platinum (Pt) and cobalt (Co) as active ingredients.

In one embodiment, the active ingredient may be represented by Formula 1.

[Formula 1]

Pt _x Co _y

(where 1<x<4 and 1<y<4)

In one embodiment, x representing the composition (at%) of platinum (Pt) has a range of 1<x<4, and y representing the composition (at%) of cobalt (Co) is in the range of 1<y<4 may have, and when x is 1 or less or y is 4 or more, an alloy cannot be formed, and a two-metal catalyst (bimetal) in which Co is excessively supported can be formed, and when x is 4 or more or y is 1 or less, an alloy is formed It is not possible to form a two-metal catalyst (bimetal) on which Pt is excessively supported.

In one embodiment, the molar ratio of platinum (Pt): cobalt (Co) may be 1:4 to 4:1, preferably 1:3 to 3:1, when the composition is analyzed by the EDS elemental analyzer. . For example, when the molar ratio is less than 1:4, it is possible to form a bimetal in which Co, but not an alloy, is supported in excess, and when it is more than 4:1, a bimetal in which Pt, not an alloy, is supported in excess can be formed. .

In one embodiment, the active ingredient may be in an amount of 1 to 20 wt% based on the total mass of the heterogeneous alloy catalyst. When the active ingredient is contained in the range of 1 to 20% by weight, excellent biomass conversion can be obtained.

In one embodiment, the platinum (Pt) may be located on the outermost surface of the catalyst. Specifically, the heterogeneous catalyst may include a first region in which platinum (Pt) is present and a second region in which cobalt oxide (CoO) is present on the surface. Accordingly, the heterogeneous catalyst according to embodiments of the present invention has a bulk region including an alloy of platinum (Pt) and cobalt (Co), and a first region on which platinum (Pt) is present and cobalt oxide It may have a structure in which ^{Pt and Co +2} coexist, including the second region in which (CoO) exists.

In one embodiment, the surface composition (at%) of the heterogeneous catalyst may include 20 to 80% of Pt and 20 to 80% of Co when the composition is analyzed by an EDS elemental analyzer. When the Pt composition and the Co composition are within the above-described ranges, an alloy of platinum and cobalt may be formed.

In one embodiment, the heterogeneous alloy catalyst may further include an oxide film located on the surface of the active ingredient. The oxide film may be formed by passivating the surface of the heterogeneous alloy catalyst. The oxide film may prevent contamination of the surface of the heterogeneous alloy catalyst, for example, may be included to prevent contamination on the surface of the reduction-treated catalyst.

Method for manufacturing heterogeneous alloy catalyst for liquid phase reforming of biomass

One embodiment according to the present invention, the step of supporting the active ingredient precursor on a support; and reducing and activating the active ingredient precursor, wherein the active ingredient precursor includes at least one of a platinum (Pt) precursor and a cobalt (Co) precursor. It provides a method for preparing a heterogeneous alloy catalyst.

2 is a schematic diagram showing a method for synthesizing a heterogeneous alloy catalyst for realizing an embodiment of the present invention, which will be described with reference to FIG.

First, the active ingredient precursor may be supported on a support.

In one embodiment, the supporting step may be wet impregnation by mixing the dispersion solution and the active ingredient precursor.

For example, the active ingredient precursor may be a platinum (Pt) precursor or a cobalt (Co) precursor, specifically, a platinum salt precursor or a cobalt salt precursor.

Specifically, a precursor containing an active metal may be mixed together in an aqueous solution in which the support is uniformly dispersed and supported by stirring, for example, may be stirred for about 12 hours.

In one embodiment, the support may be an oxide support.

Optionally, the wet impregnated catalyst can be dried.

In one embodiment, after wet impregnation, the residual dispersion solution may be evaporated to dryness at a temperature of 60 to 130 °C for 1 to 24 hours, for example, the residual dispersion solution after the supporting process is at a temperature of about 105 °C for about 12 hours. It can be evaporated to dryness while (see Figure 2).

Next, it can be activated by reducing the supported active ingredient precursor.

In one embodiment, the activation step may be to change the chemical properties of the heterogeneous alloy catalyst surface by adjusting the reduction conditions including the activation temperature or the atmosphere gas composition.

In one embodiment, the atmosphere gas may include H ₂ gas and may be reduced to _{the H 2 atmosphere gas.} In addition, the atmosphere gas may include Air and N ₂ gas, and may be calcined with the Air and N _{2 atmosphere gas.}

In one embodiment, the activation step may be reduction at a temperature of 300 to 500 ℃ for 2 to 5 hours. When the temperature of the activation step is less than 300 ° C., an oxide catalyst can be formed, and when it is more than 500 ° C., degardation of the two metals occurs, and may exist as a two metal catalyst, thereby reducing catalytic activity. In addition, if the time of the activation step is less than 2 hours, it may exist as a catalyst having the same structure as Pt-CoO, and if it is more than 5 hours, sintering occurs and the activity may be reduced by giving a change in the catalyst structure.

In one embodiment, the active ingredient precursor supported in the activation step may be converted into an active ingredient. Specifically, in the activation step, platinum (Pt) may be formed on the outermost surface of the catalyst by changing the chemical properties of the surface of the heterogeneous alloy catalyst. Accordingly, the heterogeneous catalyst may include a first region in which platinum (Pt) is present and a second region in which cobalt oxide (CoO) is present on the surface, and the prepared heterogeneous catalyst is platinum (Pt) and cobalt. Having a bulk region containing an alloy of (Co), including a first region in which platinum (Pt) is present and a second region in which cobalt oxide (CoO) is present, Pt and Co ⁺² coexist on the surface can have a structure that

Therefore, it can be efficiently applied to the liquid phase reforming reaction for producing high-purity hydrogen by chemically changing the chemical properties of the surface of the heterogeneous catalyst through the activation step.

Next, the heterogeneous alloy catalyst may be passivated (passivation).

Specifically, the passivation step may include forming an oxide film on the surface of the metal active ingredient by exposing it to the atmosphere at room temperature.

In one embodiment, the passivation step may be performed in a gas atmosphere containing oxygen and argon. Specifically, passivation may be performed to prevent contamination of the surface of the heterogeneous alloy catalyst, and since the alloy catalyst may cause contamination in the atmosphere, a gas atmosphere containing oxygen and argon, such as 10% oxygen, argon or inert Contamination of the catalyst surface can be prevented by flowing a gas atmosphere made up of 90% of the carrier gas.

Hydrogen production method

One embodiment according to the present invention, i) through the reaction of the heterogeneous alloy catalyst to form carbon monoxide (CO) and hydrogen (H ₂ ) from the liquid phase reactants; And ii) carbon monoxide (CO) and water are reacted to convert to hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) by a water gas shift reaction (Water gas shift); Containing, the heterogeneous catalyst is a support, and a metal catalyst supported on a support, wherein the metal catalyst includes at least one of platinum (Pt) and cobalt (Co).

_{First, carbon monoxide (CO) and hydrogen (H 2} ) may be formed from the liquid phase reactants through the reaction of the heterogeneous alloy catalyst.

In one embodiment, step i) may include two or more heterogeneous alloy catalysts, and an excellent liquid phase reforming reaction effect may be obtained by appropriately charging two or more heterogeneous alloy catalysts.

In one embodiment, the liquid reactant may be a saccharide or a saccharide-derived compound. Specifically, the liquid reactant may include pentose sugar, hexose sugar, or a compound derived therefrom, for example, xylitol, xylose, glucose or sorbitol. For example, the liquid reactant may be a liquid mixture in which xylitol or xylose is uniformly dissolved. Here, xylose (C ₅ H ₁₀ O ₅ ) is a representative pentose, and xylitol (C ₅ H ₁₂ O ₅ ) may be a compound derived therefrom, but is not limited thereto.

In one embodiment, the heterogeneous alloy catalyst may selectively decompose CC and C—OH bonds included in the liquid phase reactant to form carbon monoxide (CO) and hydrogen (H ₂ ).

For example, when the liquid reactant is xylose, the reaction to form carbon monoxide (CO) and hydrogen (H ₂ ) may be as follows.

[Formula 2]

C ₅ H ₁₀ O ₅ + 5H ₂ O ↔ 5CO ₂ + 10H ₂

In addition, when the liquid reactant is xylitol, _{the reaction to form carbon monoxide (CO) and hydrogen (H 2} ) may be as follows.

[Formula 3]

C ₅ H ₁₂ O ₅ + 5H ₂ O ↔ 5CO ₂ + 11H ₂

In one embodiment, step i) may be performed at a temperature of 200 to 300 °C and a pressure of 20 to 50 bar.

Next, carbon monoxide (CO) and water may react to be converted into hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) by a water gas shift (step ii)).

In one embodiment, the generated carbon monoxide may additionally react with liquid water to be converted into hydrogen and carbon dioxide by a water gas shift reaction, and specifically, the water gas shift reaction may be as follows.

[Formula 4]

CO + H ₂ O ↔ CO ₂ + H ₂

In one embodiment, step ii) may be converted through a heterogeneous catalyst. Specifically, the water gas shift reaction can use the same heterogeneous catalyst of step i), and other catalyst components can be added to further improve the reaction rate.

In addition, one embodiment according to the present invention, i ') methane (CH ₄ ) and carbon dioxide (CO ₂ ) in biogas to react with a heterogeneous alloy catalyst to form a synthesis gas; and ii') converting carbon monoxide (CO) contained in the synthesis gas with water vapor _{to convert it to hydrogen (H 2} ) and carbon dioxide (CO ₂ ); wherein the heterogeneous catalyst is supported on a support, and a support It provides a method for producing hydrogen, comprising at least one of platinum (Pt) and cobalt (Co).

First, methane (CH ₄ ) and carbon dioxide (CO ₂ ) in biogas may be reacted with a heterogeneous alloy catalyst to form a synthesis gas (step i')). Specifically, syngas may be formed by directly reacting methane and carbon dioxide in biogas.

In one embodiment, the heterogeneous alloy catalyst may be the same as the catalyst described above, and a specific configuration overlapping therewith will not be described.

In one embodiment, step i') may include two or more heterogeneous alloy catalysts, and an excellent liquid phase reforming reaction effect can be obtained by appropriately charging two or more heterogeneous alloy catalysts.

In one embodiment, step i') may be performed at a temperature of 200 to 300 °C and a pressure of 20 to 50 bar.

Next, by reacting carbon monoxide (CO) contained in the synthesis gas with water vapor, it may be converted into _{hydrogen (H 2} ) and carbon dioxide (CO _{2 ).}

In one embodiment, step ii') may be converted through a heterogeneous alloy catalyst.

In one embodiment, the converted carbon dioxide (CO ₂ ) may be removed by capture.

Example

Hereinafter, the configuration and effect of the present invention will be described in more detail by way of examples. However, these examples are provided only for the purpose of illustration to help the understanding of the present invention, and the scope and scope of the present invention are not limited by the following examples.

Example 1: Preparation of Homogeneous Catalyst (Pt/SiO ₂ )

Platinum (Pt) loading was carried out by a wet impregnation method, and the amount was adjusted so that the active ingredient was about 5% of the total catalyst mass. To this end, 1.515 g (2.5wt%), 2.564 g (5wt%) of a platinum salt precursor (chloroplatinic acid hydrate, H ₂ PtCl _{6 ) and 10 g of a silica carrier were added to 200 mL of water, and then stirred at room temperature for 24 hours.} did.

Thereafter, water was slowly removed in a rotary vacuum concentrator, and then dried in an oven at 105° C. for 12 hours to obtain a catalyst powder. Finally, after calcining at 400° C. for 5 hours in an air atmosphere, the Pt/SiO ₂ catalyst was activated by reduction at 300° C. for 2 hours in a hydrogen flow atmosphere. After reduction, passivation treatment was performed for 2 hours at room temperature while flowing argon (Ar) gas containing a trace amount of oxygen at a concentration of 0.5%.

Example 2 : non-uniform system Catalyst preparation (Pt-Co/ SiO ₂ )

A catalyst was prepared in the same manner as the homogeneous catalyst of Example 1, except that the reduction temperature was carried out at 500 °C instead of 300 °C for 2 hours, but Pt and Co were supported together as active ingredients. At this time, the molar ratio of Pt and Co was 1:3. For synthesis, 0.3205 g (5wt%), 1.282 g (20wt%), Cobalt nitrate hexahydrate, Co(NO ₃ ) ₂ ) 0.617 g of platinum salt precursor (Chloroplatinic acid hydrate, H ₂ PtCl _{6 ) in 25 mL of water for synthesis.} (5wt%), 2.468 g (20wt%) silica carrier (SiO ₂ ) Wet impregnation was carried out using a mixed solution in a ratio of 2.5 g.

Experimental Example 1: Confirmation of surface properties

XRD analysis

In order to evaluate the alloy composition of Examples 1 and 2, X-ray diffraction analysis (XRD) was performed on the catalyst. The results are as shown in Figs. 3a and 3b. As can be seen in Figure 3a (Pt 5wt%), the Pt / SiO ₂ prepared catalyst (Example 1) was _{confirmed that the characteristic peaks of SiO 2} and Pt were detected, and Pt-Co/SiO ₂ prepared catalyst (Example 2) showed similar results to Pt/SiO ₂ , but a peak shifted to the right by 0.5 theta was detected. This was confirmed as a result of the increase of the lattice constant by forming an alloy as Co entered the lattice of Pt. In the case of Co, a peak was detected as shown in Fig. 3b (Co 5 wt%), but since the peak of Co was not detected in Fig. 3a (Pt-Co), the surface characteristics were identified through additional analysis to clearly identify the characteristics.

XPS analysis

X-ray photoelectron spectroscopy (XPS) was used to determine the surface characteristics of the prepared Pt-Co/SiO ₂ catalyst (Example 2), and the results are as shown in FIGS. 4A and 4B . In the case of the Pt-Co catalyst, in the as prepared state, both Pt and Co metal components were mainly present on the surface in an oxide state, but by reducing treatment in a hydrogen atmosphere at 300 ° C and 500 ° C, Pt oxide is in a metallic state, and Co oxide is Co ₃ It was reduced from _{O 4 to CoO.} As a result, it was confirmed that the bulk of the heterogeneous catalyst Pt-Co/SiO ₂ existed as an alloy, but metal Pt and Co ^{+2 coexisted on the surface.} This shows that it is possible to change the surface properties of the catalysts prepared through the examples under certain conditions.

TEM analysis

Transmission electron microscopy (TEM) was used to more clearly understand the influence of the surface properties presented in the previous example, and the results are shown in FIG. 5 . Both the Pt/SiO ₂ and Pt-Co/SiO ₂ catalysts were _{confirmed that the catalyst components were supported relatively uniformly on the SiO 2} support, and Co coexisted around the Pt active components to form an alloy. could be further verified. As a result of confirming the change in surface properties according to the reducing conditions, the catalysts prepared in Examples can change the surface chemical properties of the catalyst under specific conditions.

Experimental Example 2: Liquid-phase reforming reaction of xylitol

Example 1 (heterogeneous catalyst Pt-Co/SiO ₂ ) to evaluate the response

Using Example 2, the liquid phase reforming reaction of xylose was simulated through an experiment. To proceed with the experiment, 0.3 g of a catalyst was charged in the reaction part, and then the _{temperature was raised to 300 degrees in an N 2} atmosphere, and then a reduction treatment was performed for about 2-3 hours while flowing Ar mixed gas mixed with 10 vol% hydrogen. did it After that, the temperature inside the reactor was lowered to 225 degrees, which is the reaction temperature. After the temperature inside the reactor was stabilized, a liquid reactant in which 10 wt% was uniformly dissolved was injected at a space velocity ^{of 0.25 min -1.} At this time, the reactants generated through the reaction were smoothly moved to the gas-liquid separator, and N ₂ was constantly injected at a flow rate of 30 ml/min to determine the flow rate of the generated gas. At this time, the generated gas product passed through a gas-liquid separator and a condenser, and then the composition was determined using a gas chromatograph (GC).

In the liquid phase reforming reaction, the hydrogen selectivity can be calculated using the following equation.

Hydrogen selectivity (H ₂ selectivity; %) = (total number of moles of hydrogen contained in gas phase) / carbon compound (total number of moles of carbon dioxide, carbon monoxide, methane, etc.) contained in gas phase) / reforming ratio x 100%

At this time, the reforming ratio is a variable that corrects according to the difference in the amount of hydrogen generated depending on the injected biomass, and the reforming ratio of xylitol is 11/5 and the reforming ratio of xylose is 10/5.

Looking at the liquid-phase reforming results of xylitol over time shown in FIGS. 6A and 6B , it was found that only hydrogen and carbon dioxide were present in the gas phase as the reaction proceeded using _{Example 2 (Pt-Co/SiO 2 ), which is the liquid phase.} It can be understood that the carbon monoxide compound produced through the reforming was completely converted into hydrogen and carbon dioxide by the water gas shift reaction. In addition, the hydrogen selectivity according to the heterogeneous catalyst over time (5wt%, FIG. 6a) was calculated to be about 70%, and the initial hydrogen selectivity according to the heterogeneous catalyst (20wt%, FIG. 6b) with different catalyst loading was calculated to be 78%, but After 60 minutes, it was confirmed that 58% was maintained.

Experimental Example 3: Liquid-phase reforming reaction of xylose

Example 1 (homogeneous catalyst Pt/SiO ₂ ) to evaluate the response

The xylose liquid phase reforming reaction was simulated through the experiment using the catalyst 1 prepared in the previous experimental example. The experimental method is the same as the previous liquid-phase reforming reaction of xylitol except that 3 wt% of xylose aqueous solution was used as a reactant, so the detailed method will be omitted below. As shown in FIG. 7a (2.5 wt%), when the xylose liquid phase reforming reaction was carried out using the prepared catalyst 1, it was confirmed that hydrogen and carbon dioxide were formed as gas products. At this time, the initial hydrogen selectivity was about 42%. decreased by 22%. 7b (5 wt%) with different catalyst loadings, it was confirmed that the initial hydrogen selectivity reached about 40%, but decreased to 17%.

Example 2 (heterogeneous catalyst Pt-Co/SiO ₂ ) to evaluate the response

A liquid-phase reforming experiment using xylose as a reactant was conducted in the same manner as in Example 2, and the results were examined. As a result, as shown in Fig. 8a (5 wt%), the hydrogen selectivity achieved 40% and this value was kept constant. In addition, as shown in FIG. 8b (20 wt%), as the loading amount was increased to 20 wt%, the hydrogen selectivity was calculated to be 50%, which increased by 10%. As a result of the experiment, it was confirmed that although the amount of Pt supported was reduced compared to the production catalyst 1, the efficiency of liquid phase reforming of xylose could be increased by adding Co.

Example 2 (heterogeneous catalyst Pt-Co/SiO ₂ ) to evaluate the long-term response of

The results of a long-term (100 hours) liquid-phase reforming experiment using xylose as a reactant were examined using Example 2 (5 wt%). As shown in FIG. 9, it was confirmed that the hydrogen selectivity was kept constant at 50% for 100 hours. Compared to the homogeneous catalyst (Pt), the heterogeneous catalyst (Pt-Co) is characterized as a structure in which the catalyst surface coexists with Pt and Pt-Co alloy by heat treatment, thereby enhancing durability and is more effective in reforming xylose. is showing

The embodiments of the present invention described above should not be construed as limiting the technical spirit of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can improve and change the technical idea of the present invention in various forms. Accordingly, such improvements and modifications will fall within the protection scope of the present invention as long as they are apparent to those of ordinary skill in the art.

Claims (22)

As a heterogeneous catalyst for liquid phase reforming of biomass,
support; and an active ingredient supported on a support;
The active ingredient includes an alloy of platinum (Pt) and cobalt (Co),
The heterogeneous catalyst is a heterogeneous catalyst for liquid phase reforming of biomass comprising a first region in which platinum (Pt) is present and a second region in which cobalt oxide (CoO) is present on the surface. delete According to claim 1,
The active ingredient is a heterogeneous catalyst, characterized in that represented by the formula (1).
[Formula 1]
Pt _x Co _y
(where 1<x<4 and 1<y<4) According to claim 1,
The platinum (Pt): cobalt (Co) molar ratio is 1:4 to 4:1, characterized in that the heterogeneous catalyst. According to claim 1,
The active component is a heterogeneous catalyst, characterized in that the content of 1 to 20% by weight based on the total mass of the heterogeneous catalyst. According to claim 1,
The platinum (Pt) is a heterogeneous catalyst, characterized in that located on the outermost surface of the catalyst. delete According to claim 1,
The heterogeneous catalyst, characterized in that the surface composition (at%) of the heterogeneous catalyst comprises 20 to 80% of Pt and 20 to 80% of Co when the composition is analyzed by an EDS elemental analyzer. According to claim 1,
The support is Al ₂ O ₃ or SiO ₂ Characterized in that it comprises a, heterogeneous catalyst. According to claim 1,
The heterogeneous catalyst is an oxide film located on the surface of the active ingredient; characterized in that it further comprises a heterogeneous catalyst. A method for preparing a heterogeneous catalyst for liquid phase reforming of biomass, comprising:
supporting the active ingredient on a support; and
and activating the active ingredient by reducing it.
The active ingredient includes an alloy of platinum (Pt) and cobalt (Co),
Wherein the heterogeneous catalyst comprises a first region in which platinum (Pt) is present and a second region in which cobalt oxide (CoO) is present on the surface, a method for preparing a heterogeneous catalyst for liquid phase reforming of biomass. 12. The method of claim 11,
The supporting step is a heterogeneous catalyst manufacturing method, characterized in that wet impregnation by mixing the dispersion solution and the active ingredient precursor. 12. The method of claim 11,
The activation step is a heterogeneous catalyst preparation method, characterized in that by adjusting the reduction conditions including the activation temperature or atmosphere gas composition to change the chemical properties of the heterogeneous catalyst surface. 12. The method of claim 11,
The activation step is characterized in that the reduction for 2 to 5 hours at a temperature of 300 to 500 ℃, heterogeneous catalyst preparation method. 12. The method of claim 11,
The heterogeneous catalyst preparation method is a heterogeneous catalyst preparation method, characterized in that it further comprises a; passivation (passivation) of the heterogeneous catalyst. 16. The method of claim 15,
The passivation step is a heterogeneous catalyst preparation method, characterized in that it is performed in a gas atmosphere containing oxygen and argon. i) forming _{carbon monoxide (CO) and hydrogen (H 2} ) from a liquid phase reactant of biomass through the reaction of a heterogeneous catalyst; and
ii) carbon monoxide (CO) and water react to be converted into hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) by a water gas shift reaction; including;
The heterogeneous catalyst includes a support, and a metal catalyst supported on the support,
The metal catalyst includes an alloy of platinum (Pt) and cobalt (Co),
The heterogeneous catalyst comprises a first region in which platinum (Pt) is present on a surface and a second region in which cobalt oxide (CoO) is present. delete 18. The method of claim 17,
The heterogeneous catalyst selectively decomposes CC and C-OH bonds included in the liquid phase reactant to form carbon monoxide (CO) and hydrogen (H ₂ ), Hydrogen production method. 18. The method of claim 17,
Step i) is characterized in that it is carried out at a temperature of 200 to 300 ℃ and a pressure of 20 to 50 bar, hydrogen production method. 18. The method of claim 17,
The liquid reactant is a liquid mixture in which xylitol or xylose is uniformly dissolved, the hydrogen production method. 18. The method of claim 17,
Step ii) is characterized in that the conversion through the heterogeneous catalyst, hydrogen production method.

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