Method for Manufacturing a Pt-based Catalyst for bio-fuel

Abstract

The present invention relates to a method for manufacturing a platinum-based catalyst. The present invention provides, as an example, a method for manufacturing a platinum-based catalyst comprising: a first step of preparing a precursor solution by mixing a platinum precursor with a solvent; a second step of pre-treating a carrier by mixing an inorganic oxide carrier with a solvent; a third step of mixing the precursor solution prepared through the first step with the precursor solution obtained through the second step so that the platinum precursor is dispersed on the surface of the carrier; a fourth step of forming a platinum oxide on a carrier by drying and calcining the mixed solution after completing the third step; and a fifth step of forming platinum nanoparticles by reducing the carrier on which the platinum oxide has been formed through the fourth step in a hydrogen atmosphere.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a platinum-based catalyst, and more specifically, to a method for manufacturing a platinum-based catalyst suitable for the production of biofuel. Background Technology

[0002] Biofuels such as biodiesel and bioaviation fuel are produced using biomass, such as waste cooking oil or microalgae, and various catalysts are used in this process to efficiently generate hydrocarbon components.

[0003] Conventionally, platinum-based catalysts with platinum (Pt) as the active metal have been primarily manufactured by the impregnation method. In this process, the platinum precursor solution penetrates throughout the surface and internal pores of the support, resulting in a characteristic where the platinum is distributed evenly.

[0004] However, platinum located deep within the support does not allow for sufficient mass transfer of reactants, resulting in a low contribution to the actual catalytic reaction and consequently causing a decrease in activity relative to the catalyst volume. Additionally, platinum particles that have penetrated into the interior easily aggregate during the reaction or have reduced surface accessibility, which limits their efficiency as active sites.

[0005] Furthermore, traditional impregnation methods have limitations as they are not suitable for mass production processes due to the difficulty of process control and securing a uniform loading amount as production units increase. For this reason, there has been a continuous need for new manufacturing technologies that enable more uniform platinum dispersion, maintain high activity, and allow for mass production. Prior art literature

[0006] Republic of Korea Published Patent No. 10-2018-0050447 (May 15, 2018) The problem to be solved

[0007] The present invention provides a method for manufacturing a platinum-based catalyst that can improve the performance of the catalyst by controlling the size of platinum particles finely and uniformly to enhance the dispersion between particles and strengthening the bonding force between the platinum particles and the support.

[0008] In addition, by applying a carrier-based synthesis method that distributes a large amount of platinum on the surface of the carrier, we present a method for manufacturing a platinum-based catalyst that reduces platinum usage and facilitates mass production.

[0009] In addition, a platinum-based catalyst prepared according to the method for preparing such a platinum-based catalyst is presented.

[0010] Other detailed objectives of the present invention will be clearly understood and grasped by experts or researchers in the art through the specific details described below. means of solving the problem

[0011] To solve the above problem, the present invention provides, as an example, a method for manufacturing a platinum-based catalyst comprising: a first step of preparing a precursor solution by mixing a platinum precursor with a solvent; a second step of pre-treating a carrier by mixing an inorganic oxide carrier with a solvent; a third step of mixing the precursor solution prepared through the first step with the precursor solution obtained through the second step so that the platinum precursor is dispersed on the surface of the carrier; a fourth step of forming platinum oxide on the carrier by drying and calcining the mixed solution after completing the third step; and a fifth step of forming platinum nanoparticles by reducing the carrier on which platinum oxide has been formed through the fourth step in a hydrogen atmosphere.

[0012] At this time, in the second step above, the inorganic oxide carrier may be at least one selected from the group consisting of alumina, silica, and titania.

[0013] In addition, in the second step above, the solvent may be at least one selected from the group consisting of distilled water, ethanol, and n-hexane.

[0014] Meanwhile, in the above-mentioned fourth step, calcination may be performed at a temperature of 200 to 600°C, and in the above-mentioned fifth step, reduction may be performed at a temperature of 150 to 400°C.

[0015] Meanwhile, to solve the above problem, the present invention provides, as an example, a platinum-based catalyst manufactured according to the platinum-based catalyst manufacturing method described above, wherein the platinum content is 0.1 to 10 weight percent relative to the total weight of the catalyst and the average size of the platinum nanoparticles is 1 to 2 nm. Effects of the invention

[0016] According to an embodiment of the present invention, a platinum-based catalyst can be prepared in which the mass transfer pathway of reactants is shortened and activity is enhanced by distributing platinum particles in a highly dispersed form on the surface of a support. In addition, since the size of the prepared platinum particles is maintained to be fine and uniform, the number of active sites increases, and a high catalytic efficiency relative to the amount of platinum used can be obtained.

[0017] In addition, the alumina used as a carrier suppresses the aggregation of platinum nanoparticles through strong metal-carrier interaction (SMSI), ensuring high durability even during prolonged reactions; the simple process facilitates mass production and reduces the amount of platinum used.

[0018] Other effects of the present invention will be clearly grasped and understood by experts or researchers in the art through the specific details described below or during the process of implementing the present invention. Brief explanation of the drawing

[0019] FIG. 1 is a flowchart showing a method for manufacturing a platinum-based catalyst according to an embodiment of the present invention. FIG. 2 is a graph showing the component ratios of a liquid product prepared by applying a platinum-based catalyst according to an embodiment and a comparative example of the present invention. Specific details for implementing the invention

[0020] The features and effects of the present invention described above will become clearer through the following detailed description in conjunction with the attached drawings, and accordingly, a person skilled in the art to which the present invention pertains will be able to easily implement the technical concept of the present invention. Since the present invention is susceptible to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. The terms used in this application are used merely to describe specific embodiments and are not intended to limit the present invention.

[0021] Hereinafter, a method for manufacturing a platinum-based catalyst according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0022] FIG. 1 is a flowchart showing a method for manufacturing a platinum-based catalyst according to an embodiment of the present invention.

[0023] A method for manufacturing a platinum-based catalyst according to an embodiment of the present invention comprises: i) a first step (S10) of mixing a platinum precursor and a solvent; ii) a second step (S20) of pre-treating a carrier; iii) a third step (S30) of mixing a platinum precursor solution with a pre-treated carrier; iv) a fourth step (S40) of drying and calcining the carrier mixed in the platinum precursor solution; and v) a fifth step (S50) of reducing platinum supported on the calcined carrier. At this time, the first and second steps may be performed in a different order or simultaneously.

[0024] Each step is explained in detail below.

[0025] In the first step, a platinum precursor is mixed with a suitable solvent to provide platinum (Pt) particles to be supported on a carrier.

[0026] Platinum precursors are not limited to specific compounds, and various metal salts or metal acids such as chloroplatinic acid, acetylacetonate platinum(II) (Platinum(II) acetylacetonate), and tetraammineplatinum(II) chloride may be used.

[0027] Among these, platinum chloride is suitable for performing immobilization centered on the carrier surface while controlling the size of platinum particles, as it exhibits excellent solubility, facilitates reduction, and allows for easy control of nanoparticles due to uniform nucleation.

[0028] The platinum content is not particularly limited, but 0.1 to 10 weight percent relative to the total weight of the catalyst is preferred, and more preferably 0.5 to 2 weight percent is appropriate. If the platinum content is less than 0.1 weight percent, the activity per volume of the catalyst may be weak, and conversely, if the platinum content exceeds 10 weight percent, the aggregation of platinum particles may intensify, and the activity per weight of platinum may decrease.

[0029] Meanwhile, the solvent mixed with the platinum precursor is not limited to a specific solvent, but a solvent capable of uniformly mixing the platinum precursor is preferred. For example, the solvent may be selected from distilled water, ethanol, n-hexane, or a mixture thereof.

[0030] The mixing of the platinum precursor and the solvent can be carried out in a reactor such as a double-jacketed reactor, and if necessary, additives that aid in dissolution in the solvent can be introduced. The additives can be selected from ethanol, acids, bases, dispersants, etc.

[0031] In the mixing process, a platinum precursor of the target concentration is first slowly added to the solvent and completely dissolved. At this time, the stirring speed can be set to 200 to 1000 rpm. The temperature of the mixed solution should be 100°C or lower. If heated above 100°C, platinum particles may be reduced and aggregate. The concentration and volume of the solution in which the platinum precursor is dissolved can be determined based on the calculated platinum loading amount (e.g., final platinum content of 0.1 to 10 wt%).

[0032] In the second step, a carrier for supporting the platinum precursor is prepared and pretreated. The material used as the carrier is not specific, and any material capable of stably immobilizing platinum can be applied; however, it is preferable to use an inorganic oxide carrier.

[0033] Inorganic oxide carriers possess a large surface area and stable surface characteristics, making them suitable for the uniform adsorption and dispersion of platinum precursors on the carrier surface. Furthermore, their high thermal and mechanical stability results in minimal structural deformation even under process conditions such as drying, calcination, and reduction, making them suitable for ensuring reproducibility and durability in mass production processes.

[0034] In addition, since the surface of the inorganic oxide provides various surface-active sites that are advantageous for forming a highly dispersed state of metal particles, it can be utilized as an effective carrier for maintaining the surface-centered platinum support structure and catalytic activity required in the present invention. As the inorganic oxide carrier, alumina, silica, titania, or mixtures thereof may be used.

[0035] Among these, alumina is widely used as a catalyst support, and due to strong metal-support interaction (SMSI), it can stably maintain activity when applied as a catalyst. Meanwhile, although the size of the alumina is not particularly limited, it is preferable to use spherical alumina with a diameter of 2 to 4 mm.

[0036] The carrier prepared in this manner is immersed in a solvent and mixed uniformly. The solvent is not limited to the same solvent as the one mixed with the platinum precursor, and a solvent that mixes well with the surface of the carrier is preferred. For example, the solvent may be selected from distilled water, ethanol, n-hexane, or a mixture thereof.

[0037] Among these, hexane is a non-polar solvent that does not penetrate deeply into the micropores inside the carrier but mainly wets the surface of the carrier, thus creating conditions in which the platinum precursor can be uniformly adsorbed on the surface rather than inside the carrier in subsequent steps.

[0038] In addition, hexane has high volatility, so when the solvent is removed through a sieve after pretreatment, the amount of residue is small, and no excessive solution remains on the surface of the carrier, which is advantageous for improving the dispersion of the platinum precursor.

[0039] In addition, hexane has weak interaction with inorganic oxide carriers such as alumina, so it provides a physical wetting effect without changing the chemical properties of the carrier surface, thereby providing a basis for the platinum precursor to be stably adsorbed onto the carrier surface in a subsequent step.

[0040] Meanwhile, the mixing of the carrier and the solvent can be carried out in a reactor such as a double-jacketed reactor. At this time, the stirring speed can be 10 to 100 rpm.

[0041] After mixing the carrier and the solvent, a sieve smaller than the carrier can be used to separate the wet carrier from the solvent. For example, a 16 mesh (1.13 mm) sieve can be used to obtain a pretreated carrier.

[0042] The carrier that has undergone the pretreatment process comes into sufficient contact with the solvent, resulting in a uniformly wet surface; consequently, it becomes a state where the precursor can be evenly adsorbed when subsequently mixed with the platinum precursor solution.

[0043] In addition, by removing excess solvent using a sieve, the amount of unnecessary solution remaining on the surface and pores of the carrier is reduced, thereby creating conditions for the platinum precursor to be more uniformly dispersed on the surface of the carrier.

[0044] In the third step, a platinum precursor solution is added to the pretreated carrier and mixed uniformly. This allows the platinum precursor to be evenly adsorbed and dispersed on the surface of the carrier.

[0045] The device used to perform the mixing is not limited to a specific device, but it is suitable to use a stirring device such as a ribbon-type stirrer or a double-jacketed reactor so that the platinum precursor can be spread uniformly throughout the carrier.

[0046] The mixed solution may undergo an aging process. Aging is a process of maintaining the mixed state for a certain period of time so that the platinum precursor solution can be sufficiently adsorbed and stabilized on the surface of the carrier, and can be performed for 8 to 24 hours.

[0047] The stable mixing and aging process in this stage helps the platinum precursor to be effectively distributed on the surface of the carrier rather than inside, providing a foundation for forming highly dispersed and uniform platinum nanoparticles during the subsequent drying, calcination, and reduction stages.

[0048] In the fourth step, the mixture of the platinum precursor solution and the carrier is dried and calcined to evenly distribute the platinum onto the carrier.

[0049] First, it is preferable to perform drying near the boiling point of the commonly used solvent. As the solvent gradually evaporates during the drying process, the movement of platinum adsorbed on the surface of the support is restricted, allowing the platinum to be evenly distributed on the support. The drying device is not limited, but a dryer, vacuum dryer, double-jacketed reactor, etc., may be used.

[0050] Next, the dried carrier is calcined at 200–600°C to remove ligands within the precursor and stably fix evenly distributed platinum in the form of an oxide on the surface of the carrier. At temperatures below 200°C, it is difficult to sufficiently remove ligands from the platinum precursor, making oxide formation difficult; if the temperature exceeds 600°C, agglomeration between platinum particles intensifies, reducing dispersibility and consequently leading to a decrease in catalyst performance.

[0051] In the fifth step, platinum ions are reduced from the dried support to form metallic platinum nanoparticles. Through this process, a platinum-based catalyst can be obtained.

[0052] The reduction reaction can be carried out by heat-treating the dried carrier using hydrogen (H2). At this time, 1 to 10 volume% of hydrogen can be used, and more preferably 2 to 5 volume% of hydrogen can be used.

[0053] For example, platinum precursors such as platinum(IV) chloride (PtCl4) or chloroplatinic acid (H2PtCl) undergo reduction of platinum ions into metallic platinum particles under a hydrogen atmosphere, and through this process, the platinum on the catalyst surface is converted into an active site.

[0054] The reduction temperature should be in the range of 150 to 400°C. If the reduction temperature is below 150°C, the reduction of platinum ions proceeds incompletely, and sufficient nucleation of platinum particles may not occur. Conversely, if it exceeds 400°C, growth is accelerated by aggregation between platinum particles, which may reduce the catalytic active area and cause a decrease in catalytic activity.

[0055] Meanwhile, in the present invention, the size of platinum nanoparticles formed during the reduction process directly affects the catalytic performance, and it is desirable to maintain a particle size in the range of 1 to 2 nm. If the size exceeds 2 nm, there is a concern that the catalytic active area will decrease, leading to a decrease in performance, and if the particle size is excessively small (less than 1 nm), it may result in reduced durability due to thermal instability.

[0056] Through a series of processes like this, a platinum-based catalyst with a size of platinum nanoparticles in the range of 1 to 2 nm and high dispersion can be produced.

[0057] The platinum-based catalyst prepared according to the manufacturing method of the present invention has a structure in which platinum nanoparticles are uniformly distributed in a high dispersion state on an inorganic oxide support. In addition, the platinum content is 0.1 to 10 weight percent relative to the total weight of the catalyst, and the average size of the platinum nanoparticles is controlled to 1 to 2 nm.

[0058] In particular, this carrier-based synthesis method, which immobilizes and reduces platinum ions on a carrier surface, results in a high distribution of platinum on the surface, thereby reducing platinum usage and facilitating mass production. These structural characteristics shorten the mass transfer pathways of reactants, thereby enhancing catalytic activity, and by reducing platinum usage, the catalyst exhibits high activity per catalytic volume and high activity per platinum weight.

[0059] Furthermore, the alumina used as a support prevents the aggregation of metal nanoparticles through strong metal-support interactions (SMSI), ensuring that particle size and distribution remain stable even during prolonged use. Consequently, the platinum-based catalyst produced in this way can achieve high activity and durability, thereby reducing the amount of platinum used.

[0060] As such, the platinum-based catalyst of the present invention has platinum uniformly and highly dispersed on the surface of a support and maintains a stable particle size of 1 to 2 nm, resulting in high accessibility to active sites for hydrogenation and deoxygenation reactions and excellent selectivity. In addition, platinum aggregation during the reaction is suppressed by metal-support interactions with inorganic oxide supports, thereby ensuring durability and exhibiting performance particularly suitable for the production of high-quality biofuels such as bio-aviation fuel.

[0061] Next, an example of manufacturing a platinum-based catalyst according to one embodiment of the present invention will be described in detail. The following example is merely illustrative of one form of the present invention, and the scope of the present invention is not limited by the following example.

[0062] Examples

[0063] A platinum precursor solution was prepared using chloroplatinic acid as a platinum (Pt) precursor. Meanwhile, alumina (Al2O3) was prepared as a carrier and introduced into a double-jacketed reactor. An n-hexane solvent was added to the double-jacketed reactor and stirred for 1 hour, after which only the liquid phase was separated from the bottom of the reactor. Subsequently, the prepared platinum precursor solution was introduced into the double-jacketed reactor. At this time, the temperature of the double-jacketed reactor was set to 25 ℃, and the platinum precursor solution was introduced to ensure that 1 wt% of platinum was supported. The stirring speed was set to 10 rpm. To ensure uniform platinum support, the solution was aged for 12 hours to produce a carrier with the platinum precursor dispersed on its surface. Afterward, the produced carrier was dried at 80 ℃ for 8 hours using the double-jacketed reactor. A platinum catalyst was prepared by calcining the dried carrier at 400°C in a heat treatment furnace and then reducing it with a 5% hydrogen / nitrogen mixed gas.

[0064] Comparative example

[0065] A platinum precursor solution was prepared using chloroplatinic acid as a platinum (Pt) precursor, and alumina (Al2O3) was prepared as a support and placed in a double-jacketed reactor, after which the prepared platinum precursor solution was introduced into the double-jacketed reactor. Subsequently, a platinum catalyst was prepared by stirring, aging, drying, and reduction under the same conditions and procedures as in the example.

[0066] Evaluation example

[0067] Waste cooking oil or microalgae-based bio-oil was supplied to a reactor, and hydrogenation, deoxygenation (HDO), hydrotreatment, and hydrocracking reactions were carried out in a hydrogen atmosphere using platinum-based catalysts of the examples and comparative examples, respectively. During this process, water generated by the reaction of oxygenated compounds with hydrogen was removed, and the structure of the hydrocarbon chains was adjusted to convert them into liquid hydrocarbons in the aviation fuel and diesel ranges. The resulting mixture was separated and distilled to be classified into naphtha, bio-aviation fuel, and diesel, and the proportion of each component was measured. This is shown in Figure 2.

[0068] When the catalyst of the example was applied, a structure in which a platinum precursor was uniformly dispersed on the surface of a support and active sites with a fine particle size (1–2 nm) efficiently contacted the reactants exhibited high hydrogenation and deoxygenation activity. As a result, the total liquid product was confirmed to be 88.2%, of which 60.0% was aviation fuel range hydrocarbons, indicating excellent selectivity and reaction efficiency for converting bio-oil into aviation fuel.

[0069] On the other hand, the catalyst in the comparative example had a structure in which platinum was supported deep inside the carrier by directly applying the precursor solution without carrier pretreatment, and it was analyzed that this limited the mass transfer of reactants and resulted in a lack of active sites on the catalyst surface. As a result, the total liquid product was only 86.4% and the aviation fuel production rate was only 31.9%, showing that both reaction efficiency and selectivity were lower compared to the example.

[0070] As such, the catalyst of the example can produce aviation fuel-range products at a high rate due to its surface-centered platinum high dispersion structure, which provides high reactant accessibility and excellent utilization efficiency of active sites. In contrast, the comparative example was analyzed to have exhibited a relatively low aviation fuel yield because the platinum was dispersed within the carrier, resulting in a low contribution to activity.

[0071] Therefore, it can be confirmed that the catalyst of the embodiment to which the platinum-based catalyst manufacturing method of the present invention is applied exhibits excellent activity and selectivity even under general biofuel manufacturing process conditions, and is particularly suitable for the production of high-quality bio-aviation fuel.

[0072] Although the detailed description of the present invention described above has been explained with reference to preferred embodiments of the invention, those skilled in the art or those with ordinary knowledge in the relevant technical field will understand that various modifications and changes can be made to the present invention without departing from the spirit and technical scope of the invention as described in the claims set forth below.

Claims

Claim 1 A method for manufacturing a platinum-based catalyst for biofuel production comprises: a first step of preparing a precursor solution by mixing a platinum precursor with a solvent; a second step of pretreating a carrier by mixing an inorganic oxide carrier with a solvent; a third step of mixing the precursor solution prepared through the first step with the pretreated carrier obtained through the second step so that the platinum precursor is dispersed on the surface of the carrier; a fourth step of drying the mixed solution after the third step and calcining it to form platinum oxide on the carrier; and a fifth step of reducing the carrier on which platinum oxide has been formed through the fourth step in a hydrogen atmosphere to form platinum nanoparticles, wherein in the second step, the inorganic oxide carrier is pretreated by mixing with hexane, and an excess amount of hexane is separated from the pretreated inorganic oxide carrier to obtain an inorganic oxide carrier with a surface wetted by hexane, and in the third step, the precursor solution is mixed with the inorganic oxide carrier with a surface wetted by hexane, and the mixed solution of the precursor solution and the inorganic oxide carrier A method for preparing a platinum-based catalyst in which the platinum precursor is adsorbed and stabilized on the surface of an inorganic oxide carrier by aging for 8 to 24 hours. Claim 2 A method for manufacturing a platinum-based catalyst according to claim 1, wherein in the second step, the inorganic oxide carrier is at least one selected from the group consisting of alumina, silica, and titania. Claim 3 A method for manufacturing a platinum-based catalyst according to claim 1, wherein in the fourth step, calcination is performed at a temperature of 200 to 600°C, and in the fifth step, reduction is performed at a temperature of 150 to 400°C. Claim 4 delete Claim 5 delete

Images