KR102259639B1 - Porous Metal-Organic Framework encapsulated with metal nanoparticles and method for preparing the same - Google Patents

Abstract

The present invention relates to a method for preparing a catalyst for hydrodeoxygenation reaction through surface modification of a porous metal-organic framework in which metal nanoparticles for increasing the activity of the catalyst are fixed inside the pores of the porous metal-organic framework. The catalyst for hydrodeoxygenation reaction according to the present invention comprises various functional sites such as Bronsted acid sites and Lewis acid sites. By using the catalyst, it is possible to efficiently remove oxygen by adding hydrogen to an organic oxygen compound, so as to effectively produce a biofuel that can replace petroleum with a high yield, and the catalyst of the present invention is reusable and has the effect of exhibiting excellent catalytic activity even when reused.

Description

Porous Metal-Organic Framework encapsulated with metal nanoparticles and method for preparing the same

The present invention relates to a porous metal-organic framework to which metal nanoparticles are fixed, and a method for manufacturing the same, and more particularly, to a porous metal-organic framework to which metal nanoparticles are immobilized, which enhances the activity of a catalyst in the pores of the porous metal-organic framework. It relates to a method for preparing a catalyst for hydrodeoxygenation reaction through surface modification of a metal-organic framework.

Recently, due to the depletion of fossil fuels, the sharp rise in oil prices, and the strengthening of the implementation of the Climate Change Convention, interest in the use of renewable biomass has increased rapidly due to restrictions on the use of fossil fuels. R&D is actively underway. Wood-based biomass, which is distinguished from food biomass composed mainly of cellulose, accounts for more than 95% of the total plant biomass and is receiving much attention as the next-generation biomass because it can utilize non-food resources and wastes. Cellulose, hemicellulose among the components of lignocellulosic biomass, cellulose and hemicellulose among lignin can be used as food resources, and lignin is a random phenolic polymer that has the potential to replace all aromatic carbon compounds derived from petroleum. Due to its complex structure, it is recognized as a simple by-product and discarded, so research and development to find a way to utilize it is actively underway.

Various chemical and biological methods for producing high-grade fuels from various biomass raw materials have been proposed, and pyrolysis is a method that can use all kinds of carbon compounds as raw materials. The pyrolysis or hydrothermal cracking method has the advantage that it can be used for various types of biomass, but has a disadvantage that the produced pyrolysis product or liquid pyrolysis oil is not suitable as an alternative fuel to petroleum due to its high oxygen content.

A metal-organic framework (MOF) is a three-dimensional framework composed of a metal bundle and an organic ligand. Various types of MOFs are formed by self-assembly depending on the type of metal and organic ligand and reaction conditions. The shape of the metal bundle varies depending on the preferred structure of the metal, and even with the same metal, different MOFs can be formed because the connection method varies depending on the type of ligand, the functional group of the ligand, and the reaction conditions. It forms micropores or mesopores depending on the ligand's connection method and length, and is used in various fields such as carbon dioxide capture, hydrogen storage, catalyst, hydrocarbon separation medium, magnetism, drug delivery medium, sensor, and nanomaterial synthesis. It is being actively studied for application.

MILl-101(Cr) (MIL, Material Institut Lavoisier) is ^{a MOF composed of a Cr 3+} metal bundle and a BDC bridging ligand. Metal bundles and bridging ligands combine to form a large tetrahedron, and these large tetrahedra form a Mobil Thirty-Nine (MTN) type structure. In addition to having a large specific surface area, MIL-101(Cr) has the advantage of being stable in the air and especially stable in moisture. Research has shown that functionalized MIL-101(Cr) does not collapse even after repeated water adsorption several times. has been reported

Accordingly, the present inventors impregnated the metal-organic framework catalyst in phosphoric acid, and as a result of fixing metal nanoparticles such as Pt inside the pores of the metal-organic framework, it contains various functional sites such as Bronsted acid sites and Lewis acid sites, When the catalyst is used, it has been confirmed that the hydrodeoxygenation conversion rate is high, it is reusable, and exhibits excellent catalytic activity even when reused, and the present invention has been completed.

Korean Patent Publication No. 10-2017-0133092

An object of the present invention is to provide a method for preparing a catalyst for hydrodeoxygenation.

Another object of the present invention is to provide a catalyst for hydrodeoxygenation reaction prepared by the above preparation method.

Another object of the present invention is _{to provide a method for reforming a C 3-40} oxygen-containing hydrocarbon compound into a saturated hydrocarbon.

Another object of the present invention is to provide a saturated hydrocarbon prepared by the above reforming method.

Another object of the present invention is to provide a biofuel containing the saturated hydrocarbon.

To achieve the above object,

The present invention relates to metal-organic frameworks (MOFs) impregnated with a phosphorus precursor (step 1); And

fixing the metal nanoparticles to the micropores of the metal-organic framework impregnated with the phosphorus precursor (step 2); It provides a method for producing a catalyst for hydrodeoxygenation reaction comprising a.

In addition, the present invention provides a catalyst for hydrodeoxygenation reaction prepared by the method for preparing the catalyst for hydrodeoxygenation reaction.

Furthermore, the present invention provides a step of obtaining a saturated hydrocarbon compound by performing a hydrodeoxygenation reaction while introducing an oxygen-containing hydrocarbon compound _{of C 3-40} and hydrogen gas to the reactor including the catalyst for the _{hydrodeoxygenation reaction; C 3 including Provided is a method for reforming from a -40} oxygen-containing hydrocarbon compound to a saturated hydrocarbon.

Furthermore, the present invention provides a saturated hydrocarbon prepared by the above reforming method.

In addition, the present invention provides a biofuel containing the saturated hydrocarbon.

The catalyst for hydrodeoxygenation according to the present invention includes various functional sites such as Bronsted acid sites and Lewis acid sites, and by using the catalyst, it is possible to efficiently remove oxygen by adding hydrogen to an organic oxygen compound, so that petroleum It is possible to produce a biofuel that can be replaced with a high yield, and the catalyst prepared according to the production method of the present invention is reusable, and has the effect of exhibiting excellent catalytic activity even when reused.

1 is a result of confirming the XRD pattern of the Pt/P@MIL catalyst of the present invention.
2 shows the adsorption-desorption isotherms (a) and pore size (b) of the Pt/P@MIL catalyst of the present invention.
3 is a result of confirming the acid strength (acid strength) of the Pt / P@MIL catalyst of the present invention by NH ₃ temperature-programmed desorption (TPD).
4 is an XPS spectrum showing the O 1s core level for the Pt/P@MIL catalyst of the present invention.
Figure 5 shows the FE-TEM image of the Pt / P@MIL catalyst of the present invention and the particle size distribution by phosphoric acid treatment concentration (0 mM (a), 60 mM (b), 240 mM (c), 480 mM (d)).
6 shows the 4f XPS spectrum of the Pt/P@MIL catalyst of the present invention.
7 shows the oleic acid (OLA) conversion, HDO conversion and product content of the Pt/P@MIL catalyst of the present invention.
^{8 shows TOF(s −1} ) based on nC17 and nC18 products following phosphoric acid treatment.
9 shows the HDO conversion and product selectivity according to the reaction time of the Pt/P@MIL catalyst of the present invention.
Figure 10 shows the FE-TEM image and particle size distribution of the catalyst used 24 hours after the HDO reaction.
11 shows the thermogravimetric analysis of the Pt/P@MIL catalyst of the present invention.
12 is a reaction scheme showing possible bonding structures of phosphate molecules adsorbed to Lewis acid sites.
13 is a reaction scheme showing the hydrodeoxygenation route of oleic acid through the Pt/P@MIL catalyst of the present invention.

Hereinafter, the present invention will be described in detail.

Preparation method of catalyst for hydrodeoxygenation reaction

The present invention relates to metal-organic frameworks (MOFs) impregnated with a phosphorus precursor (step 1); And

fixing the metal nanoparticles to the micropores of the metal-organic framework impregnated with the phosphorus precursor (step 2); It provides a method for producing a catalyst for hydrodeoxygenation comprising a.

In the preparation method of the present invention, the phosphorus precursor is phosphoric acid (H ₃ PO ₄ ), ammonium phosphate ((NH ₄ )H ₂ PO ₄ ), diammonium phosphate ((NH ₄ ) ₂ HPO ₄ ) or triammonium phosphate ( (NH ₄ ) ₃ PO ₄ ) may be used, and preferably phosphoric acid (H ₃ PO ₄ ) may be used.

In the manufacturing method of the present invention, step 1 may be prepared by impregnating the phosphorus precursor at a concentration of 60 to 480 mM, preferably by impregnating at a concentration of 60 to 360 mM, more preferably 230 to It may be prepared by impregnation at a concentration of 380 mM, and even more preferably by impregnation at a concentration of 220 to 260 mM.

In an embodiment of the present invention, the Bronsted acid point increases the highest in the concentration range of the phosphorus precursor treatment concentration of 220 to 260 mM (see Table 2), and in the hydrodeoxygenation reaction of oleic acid, octadecane, a saturated hydrocarbon ( It can be seen that the conversion rates of octadecane) and heptadecane are the highest (see FIG. 7 ).

In one embodiment of the present invention, as the concentration of the phosphorus precursor treatment increases, the strength of the acid sites and the total amount of acid sites of the metal-organic framework increase, thereby causing the acyl C = of the organic oxygen compound in the hydrodeoxygenation reaction. The O bond is activated, and the O atom of the bond is activated to be easily attacked by the H supplied to the hydrodeoxygenation reaction. In addition, carbon monoxide (CO), a product of the decarbonylation reaction, has a negative effect on the metal nanoparticle active sites fixed in the micropores of the metal-organic framework (see Fig. 3, Table 1, Table 3). .

In the manufacturing method of the present invention, as the metal nanoparticles of step 2, palladium (Pd), platinum (Pt), ruthenium (Ru), copper (Cu), silver (Ag) or gold (Au) nanoparticles may be used. and preferably, it can be prepared using platinum (Pt) nanoparticles.

In the production method of the present invention, the metal-organic framework is a MIL (Materials Institute Lavoisier)-based metal-organic framework, and the MIL-based metal-organic framework is MIL-47, MIL-53, MIL-100, MIL. -101, MIL-102, MIL-110, MIL-125, MIL-127 or a mixture thereof may be used, and preferably MIL-101 may be used.

In one embodiment of the present invention, the MIL-101 is added with stirring lithium acetate dihydrate to terephthalic acid dissolved in deionized water, followed by mixing the metal salt powder. Then, it can be prepared by performing a crystallization reaction.

In one embodiment of the present invention, the crystallization reaction may use electric heating, ultrasonic waves, electromagnetic waves or electrochemical methods.

In an embodiment of the present invention, Fe, Al, Cr, Ti, Sc, Cu, or V may be used as the metal salt individually or in combination.

In an embodiment of the present invention, after immobilizing the metal nanoparticles of step 2, the method may further include reducing them in a hydrogen atmosphere.

In the manufacturing method of the present invention, the phosphorus precursor is Brønsted acid sites, and the metal-organic framework functions as Lewis acid sites.

In one embodiment of the present invention, as the concentration of the phosphorus precursor increases, the Bronsted acid point increases, and as the central metal of the metal-organic framework and the phosphorus precursor bind, the Lewis acid point decreases (Table 1). see 2).

In addition, the present invention provides a catalyst for hydrodeoxygenation reaction prepared by the above production method.

In one embodiment of the present invention, the catalyst for the hydrodeoxygenation reaction may be used in the hydrodeoxygenation reaction using an organic oxygen compound as a starting material.

C _3-40 A method of reforming from oxygen-containing hydrocarbon compounds of

The present invention is a saturated hydrocarbon compound by performing a hydrodeoxygenation reaction while introducing a _{C 3-40} oxygen-containing hydrocarbon compound and hydrogen gas to a reactor containing a catalyst for hydrodeoxygenation reaction prepared according to the production method of the present invention _{It provides a method for reforming from a C 3-40} oxygen-containing hydrocarbon compound to a saturated hydrocarbon comprising the step of obtaining.

In the manufacturing method of the present invention, the flow rate of the hydrogen gas may be supplied at 10 to 100 mL/min. The hydrogen acts as a very important factor to activate the hydrodeoxygenation catalyst, and when it is out of the above range, the catalyst is not activated because the supply of hydrogen is not made sufficiently, or a sufficient contact time cannot be secured due to the fast flow rate. This can happen.

In the manufacturing method of the present invention, the hydrodeoxygenation reaction may be prepared by performing the hydrodeoxygenation reaction for 90 to 150 minutes under a hydrogen pressure of 250 to 350 ℃, 1 to 3 MPa. In the range of 250 to 350 °C _{, oxygen contained in the C 3-40} oxygen-containing hydrocarbon compound is removed by decarboxylation, decarbonylation, and hydrodeoxygenation to obtain saturated hydrocarbons as the main product.

In one embodiment of the present invention, the C _3-40 oxygen-containing hydrocarbon compound is at least one selected from the group consisting of palm oil, corn oil, sunflower oil, olive oil, soybean oil, rapeseed oil, cottonseed oil, rice bran oil and palm oil or its vegetable oils in the mixture; Animal fats and oils of one or a mixture thereof selected from the group consisting of tallow, pork, brisket and fish oil; Alternatively, one selected from the group consisting of oleic acid, palmitoleic acid and erucic acid, or a mixture thereof, may be used.

In addition, the present invention provides a saturated hydrocarbon prepared by the above reforming method.

In addition, the present invention provides a biofuel containing the saturated hydrocarbon.

The present invention will be described in more detail through the following examples. However, the following examples are only for embodiing the contents of the present invention, and the present invention is not limited thereto.

<Example 1> Preparation of Pt/P@MIL catalyst reduced by phosphoric acid treatment

<1-1> Preparation of MIL-101 (Cr)

MIL-101 (Cr) was synthesized by hydrothermal synthesis using acetate. More specifically, after adding 0.664 g of terephthalic acid (98%, Sigma Aldrich) to 25 mL of deionized water and 0.025 g of lithium acetate dihydrate (Sigma Aldrich) with stirring, 1.6 g of Cr (NO ₃ ) ₃ ·9H ₂ O (99%, Sigma Aldrich) was added and dispersed under ultrasound for 15 minutes. The mixture was then transferred to a Teflon liner autoclave and heated in a convection oven at 200° C. for 12 hours to perform a crystallization reaction. After the crystallization reaction, the obtained green solid sample was treated with deionized water at 80 °C three times, N,N-dimethylformamide (DMF) at 80 °C for 8 hours (3 times), and finally with hot ethanol. After washing for 8 hours (3 times) and centrifugation, the solid product was isolated and MIL-101 (Cr) was obtained. The obtained product was dried at 100° C. overnight.

<1-2> H ₃ PO ₄ Preparation of @MIL-101(Cr) (P@MIL)

MIL-101 (Cr) prepared in Example 1-1 was treated with phosphoric acid. More specifically, MIL-101 (Cr) 70 in a DMF solvent (30 mL) containing _{ortho-phosphoric acid (H 3} PO ₄ , 89%, TCI, Japan, PA) at a concentration of 30 to 480 mM It was prepared by immersing it at ℃ with slow stirring for 5 hours. After phosphoric acid soaking was completed, it was filtered, washed with DMF and ethanol under vacuum conditions, and dried at 100° C. overnight. It is denoted as P@MIL-xmM (xmM is the acid concentration of 30-480 mM).

<1-3> Pt/H ₃ PO ₄ Preparation of @MIL-101(Cr) (Pt/P@MIL)

Using the double solvent method (DSM), Pt was immobilized. First, P@MIL prepared in Example 1-2 was added to n-hexane as a hydrophobic solvent while stirring at room temperature for 2 hours. Thereafter, an aqueous solution of a metal precursor H ₂ PtCl _{6 as a} hydrophilic solvent was slowly added dropwise to the mixture solution while continuously stirring for 2 hours. The obtained solid product was dried at 100° C. for 12 hours and then reduced at _{250° C. with H 2 .} The final product was expressed as Pt/P@MIL-xmM (xmM is an acid concentration of 30-480 mM).

<Experimental Example 1> X-ray diffraction peak (XRD) confirmation of the catalyst

For the X-ray diffraction pattern, a powder X-ray diffraction spectrometer (PXRD; MAC-18XHF, Rigaku, Japan) was used using a Cu Kα radiation source (λ=1.54 Å).

As a result of checking XRD to confirm the crystal structure of the Pt/P@MIL catalyst, as shown in FIG. 1, the diffraction peak of MIL-101(Cr) was detected before and after fixing phosphoric acid and Pt metal, and MIL- It was confirmed that the crystal structure of 101(Cr) remained even before and after heat treatment. On the other hand, in the case of the phosphoric acid-treated catalyst of Example 1, the peak intensity decreased as the phosphoric acid concentration increased, and it was confirmed that the position of the diffraction peak was moved to a higher 2 Theta position, which -101 (Cr) represents the interaction between Cr + ³ and the phosphate of the structure.

<Experimental Example 2> Texture properties of catalyst

The texture properties of the Pt/P@MIL catalyst of Example 1 _{were analyzed using N 2} porosimetry (TriStar, Micromeritics, USA) at 77K. Prior to analysis, the catalyst was degassed at 150° C. for 12 hours. The specific surface area and N ₂ adsorption-desorption isotherms were measured using the Brunaune-Emmet-Teller (BET) method. _{The total pore volume was confirmed by N 2} adsorption at a relative pressure of 0.98, and the pore size distribution was obtained by the Barrett-Joyner-Halenda (BJH) algorithm.

The texture properties of the Pt/P@MIL catalyst are shown in FIG. 2 and Table 1. As shown in Fig. 2a, the Pt/MIL catalyst without phosphoric acid and the Pt/P@MIL catalyst treated with phosphoric acid correspond to type I isotherms according to the IUPAC classification, which means that the catalyst has a microporous structure. indicates that In addition, MIL-101(Cr) has an excellent BET surface area ^{of 3,521 m 2} /g and a high pore volume of ^{2.39 cm 3 /g.}

In addition, the decrease in the surface area and pore volume of the Pt/P@MIL catalyst with increasing phosphate concentration means that phosphate molecules (d=0.61 nm) enter the pore system of the MIL-101(Cr) framework. . Also, as shown in FIG. 2b, the pore size distribution curve of the catalyst shows a decrease in pore volume at pore diameters centered at 0.7, 1.6 and 2.4 nm after acid addition. Thus, the strong reduction of porous molecules (reduction of surface area and pore volume) is due to the fact that at a much better acid concentration (480 mM), the acid molecules pass through the porous window (referred to as open sites in the porous structure) and occupy part of the pores. Occurs because it covers the skeleton.

catalyst BET,
m ² /g pore volume,
cm ³ /g CO uptake,
mmol/g % metal dispersion
(metal dispersion) TOF
(s ^-1 ) MIL-101(Cr) 3521 2.39 - - 1%Pt/MIL-101 3475 2.35 8.25 32.1 0.06 1%Pt/P@MIL-30mM 3234 2.12 8.82 34.3 0.105 1%Pt/P@MIL-60mM 3109 2.04 7.54 30.2 0.465 1%Pt/P@MIL-120mM 3048 2.02 7.01 27.2 0.566 1%Pt/P@MIL-240mM 2937 1.8 3.12 12.1 1.491 1%Pt/P@MIL-480mM 1544 1.1 0.34 1.3 9.25

<Experimental Example 3> Confirmation of acidity property of the catalyst

Acidity property of the catalyst was confirmed using _{NH 3 -TPD.} The equipment used in the experiment was a Micromeritics AutoChem II 2920 automatic analyzer equipped with a thermal conductivity detector (TCD). TPD (Temperature Programmed Desorption) is a method to analyze the components of the desorbed gas while raising the sample temperature at a constant rate. The thermal stability of MIL-101 (Cr) determined by Thermogravimetric Analysis (TGA) 11) is based.

First, the sample was pretreated in a helium stream at 250° C. for 2 hours to remove surface impurities. Then, after cooling to 100° C., the sample was saturated with ammonia in _{10% NH 3} /He (50 cm ^{3 /min) for 1 hour. In the ammonia desorption step, 50 cm 3} /min of helium was used up to 400° C. at a heating rate of 2° C./min.

As a result of measuring the acidity of the catalyst, as shown in Figure 3 and Table 2, MIL-101 (Cr) and Pt / P@MIL were exposed to three peaks in the 250 ℃, 290 to 340 ℃ and 385 ℃ region, This is due to the weak Lewis scattering, the medium Lewis scattering and the medium Brönsted scattering, respectively.

catalyst Amount of acid site
(μmol/g) total of scattering
(Total amount of acid sites)
(μmol/g) acid density
(Acid density)
(μmol/m ² ) Weak
(< 250 ^o C) Moderate
(250 - 350 ^o C) Moderate
(> 350 ^o C) 1Pt/MIL101 28.0 49.5 75.0 152.5.0 0.050 1Pt/P@MIL-60mM 32.4 69.7 76.0 178.1 0.057 1Pt/P@MIL-120mM 15.3 61.4 86.4 163.3 0.054 1Pt/P@MIL-240mM 12.0 25.0 144.0 181.0 0.062 1Pt/P@MIL-480mM - 46.0 160.0 206.0 0.133

Compared with the existing MIL-101 (Cr), as the phosphoric acid treatment concentration increases, it can be confirmed that the acid sites are moved to the strong acid site regions, which means an increase in the Bronsted acidity. In addition, the decrease of the weak Lewis acid site according to the phosphoric acid treatment concentration is because the Lewis acid site partially covers the framework ^{of Cr 3 + , which is an unsaturated metal ion, by bonding with a phosphorous series.} Phosphoric acid can be formed depending on the Lewis and Brønsted acidity of the surface of the scaffold, and can introduce Brønsted acid sites through some -OH groups.

To confirm this, the O 1s core level and XPS spectrum for the Pt/P@MIL catalyst were analyzed. XPS measurements were performed using a Thermo Scientific K-Alpha spectrometer to determine the oxide state of elements in a sample. The binding energy was adjusted using a carbon C (1s) line with a binding energy at 284.6 eV as a reference. The reduced catalyst was passivated in Ar with 3% gas mixture at room temperature for 2 hours and then exposed to air.

As a result, as shown in Fig. 4, the unseparated peak is located at 530.1 eV and assigned to Cr-O, which is slightly higher than that of Pt/MIL(Cr) without phosphate treatment (529.7 eV). On the other hand, in the case of the Pt/P@MIL catalyst, a peak appeared at 531.6 eV, which is P-O-Cr, P=O … Corresponds to Cr and surface Cr-OH bonds.

<Experimental Example 4> Confirmation of catalyst shape and particle size distribution

The particle size and distribution of metal particles were analyzed by FE-TEM (JEM-2100F, JEOL, Japan).

The shape and particle size distribution of the Pt/P@MIL catalyst according to the phosphoric acid treatment concentration is shown in FIG. 5 . The FE-TEM image (top of Fig. 5) showed the octahedral structure of MIL-101(Cr), the Pt metal was uniformly dispersed on the support (MIL-101(Cr) catalyst), and most of the Pt particles were MIL- It is distributed in the size range of 1.5-2.5 nm, corresponding to the porous cavities of 101 (1.6 nm to 2.4 nm), and the average size of unphosphated Pt/MIL-101 is reported to be 1.72 nm.

The FE-TEM result showed that the Pt metal particle size distribution was changed to a higher value by the phosphoric acid treatment, and the average size was increased by 1.5 times and 2.3 times, respectively, in the case of 240 mM and 480 mM. On the other hand, no Pt particles were observed on the outer surface of the catalyst due to the electrostatic interaction with the support (MIL-101(Cr) catalyst), which was on the support (MIL-101(Cr) catalyst) due to the dual solvent approach. It represents the effective introduction of a noble metal phase.

In addition, Pt dispersion was confirmed using a CO adsorption experiment using a Micromeritics AutoChem II 2920 micro-flow reactor equipped with a thermal conductivity detector (TCD). More specifically, a sample (0.1 g) was loaded into a U-tube quartz reactor and the reduction of the catalyst was carried out at 250° C. for 3 hours with 10% H ₂ /Ar (50 cm ³ /min), and at 50° C. under Ar. Cool and hold for 1 hour at this temperature for stabilization before pulsing 10% CO/He into the reactor. CO uptake was measured by gassing 500 mL of 10% CO/He until the sample was completely saturated.

As a result of the CO adsorption, as shown in Table 1, in the case of Pt/MIL not treated with phosphoric acid, the Pt dispersion was 32.1%, and the Pt dispersion was significantly reduced to 12.1% and 1.3% at the phosphoric acid treatment concentrations of 240 mM and 480 mM, respectively. The above results confirmed that phosphoric acid tends to complement and block the CO site adsorbed onto the active site of Pt introduced into the pores of the MIL-101(Cr) catalyst.

Therefore, the Pt particle size is shown in Table 3 by CO chemisorption and TEM measurement. There was no significant difference in the average size of the Pt metal in the case of no phosphate treatment or treatment with a low concentration of phosphoric acid. However, the difference between the Pt particle size determined by CO adsorption (7.8 nm) versus the Pt particle size measured by TEM (3.08 nm) becomes large for the phosphoric acid treatment concentration of 360 mM.

This reduction in metal dispersion is because the specific surface area and pore volume decrease by 15-55% as the acid concentration increases to 60-480 mM. Another reason may be that, as shown in FIG. 6, ^{when the reduction process from Pt 4+} to Pt metal reached 38-42%, the reduction of the catalyst was not completed.

catalyst D _CO, determined by CO chemisorption
Pt particle size, nm D _TEM , determined by TEM
Pt particle size, nm 1%Pt/MIL-101 1.95 1.72 1%Pt/P@MIL-30mM 1.97 2.07 1%Pt/P@MIL-60mM 2.05 2.15 1%Pt/P@MIL-120mM 2.31 2.27 1%Pt/P@MIL-240mM 2.95 2.53 1%Pt/P@MIL-360mM 7.8 3.08 1%Pt/P@MIL-480mM - 3.89

<Experimental Example 5> Measurement of catalyst activity (hydrodeoxygenation, HDO activity measurement)

The HDO conversion of oleic acid was carried out in a continuous fixed-bed reactor. Before the reaction, the catalyst was reduced with a gas mixture _{of H 2} /Ar (60/20 cm ³ /min) at 250 °C for 3 hours. For each run, 5 wt % of oleic acid (98%, Aldrich) in decane (>99%, Aldrich) was fed using a high pressure pump at a flow rate of 0.15 mL/min and preheated at 250°C.

The resulting mixture vapor was _{mixed with a H 2} stream (60 mL/min) before entering the tubular reactor. The HDO reaction was carried out at 300° C. and a hydrogen pressure of 2 MPa for 2 hours. An ethyl-glycol-cooled condenser system was used to condense the vapor product to a liquid phase at about -10°C. The mass balance was determined to be 86.2% ± 1% by weight of the liquid product to the reactants entering the reactor after condensation. Mass loss occurred due to non-condensing products, liquid retention in the condenser and coke deposition on the catalyst.

The liquid product was collected every 20 min and analyzed by GC-MS (Agilent 7890B, USA) using a capillary column-HP 5MS (30 m x 0.25 mm x 0.25 mm). The detector temperature was set at 280°C, and the heating rate of the GC analysis was heated at an initial temperature of 100°C at 8°C/min, and maintained at 250°C for 1 minute. Quantitative data can be obtained by measuring only the relative content of each substance.

The conversion rate of oleic acid, deoxygenation degree (XGOD) and product distribution were calculated as (1), (2) and (3) below.

where C _0OLA is the initial oleic acid concentration (mol/L), C _OLA is the oleic acid concentration at different reaction times (t, h), and C _i is the concentration of product i in the HDO product stream.

[Equation 1]

[Equation 2]

[Equation 3]

To compare the intrinsic activity of catalysts at different acid concentrations, the turnover frequency (s ⁻¹ ) was calculated using Equation 4 below:

[Equation 4]

The oleic acid conversion and HDO conversion of the Pt/P@MIL catalyst prepared in Example 1 are shown in FIG. 7 . As shown in FIG. 7 , the non-phosphating Pt/P@MIL catalyst exhibits very low catalytic performance with an HDO conversion of less than 5%, and 80% of oleic acid is converted to stearic acid as an intermediate product.

On the other hand, the conversion of HDO was significantly improved by the presence of phosphoric acid as a source providing the Brønsted acid site. When the concentration of phosphoric acid (H ₃ PO ₄ ) was increased from 30 to 60 mM, the HDO conversion of oleic acid was increased by about 42% from 15% (phosphoric acid concentration 30 mM) to 57% (phosphate concentration 60 mM). When the concentration of phosphoric acid was increased to 120 mM and 240 mM, the HDO conversion increased by 11% and 18.5%. The highest HDO conversion of 75% was reached at 240 mM with a nC17/nC18 ratio of 3.7. However, at too high phosphoric acid concentrations (360 and 480 nm), the HDO conversion tends to decrease rapidly due to partial loss of surface properties of MIL-101 and reduction of metal active sites on the catalyst.

There are two main routes for the deoxygenation of oleic acid on Pt/P@MIL catalysts based on product distribution. The first route is the direct hydrogen-deoxygenation of oleic acid, i.e., the oxygen atom of the acyl C=O bond is adsorbed to the center of the electrophilic acid support and is hydrogenated by the H atom dissociated at the metal active site to form octadecanol and then hydrogenated. Produces octadecane (nC18). The second route is hydrogenation-decarbonylation/decarboxylation to produce heptadecane (nC17). The -OH group of oleic acid is first hydrogenated by an H atom separated from _{the H 2 molecule of the metal moiety to form H 2} O and octadecane as intermediates. Subsequent compounds were recorded as final product streams, but their content was negligible. Subsequently, the intermediate is further converted to heptadecane by a decarbonylation step. This pathway can occur concurrently with the direct hydro-decarboxylation of oleic acid or stearic acid to form _{heptadecane and CO 2 .} The hydrogen deoxygenation pathway of oleic acid is shown in FIG. 13 .

In order to explain the effect of phosphoric acid treatment on the metal active sites for the HDO reaction of oleic acid, the turnover frequencies (TOF) for the metal active sites in the HDO conversion of oleic acid were calculated, as shown in Table 1. CO uptake (μmol/g) was used to define HDO conversion per metal.

The TOF of the Pt/P@MIL catalyst without phosphate treatment was 0.06s ^-1 , which is the same as or similar to the value in other literatures. TOF(s-1) of other single metal (Co, Ni, Pt, Pd)-based catalysts ranged from 0.01 to 0.27. Compared to the non-phosphating Pt/P@MIL catalyst, the phosphated catalyst exhibited 1.5 to 25 times higher TOF (0.105 to 1.49 s ⁻¹ ) at acid concentrations of 30-240 mM. In particular, the TOF of the catalyst treated with phosphoric acid at a concentration of 480 mM has a high value (9.25 s −1 ) as the appearance of Pt active sites and acid sites decreases. Therefore, the product distribution is more dependent on the acid site than the type of noble metal.

As shown in Figure 8, the ratio of nC17/nC18 yields increases in a phosphating concentration-dependent manner, indicating that the decarboxylation reaction dominates the hydrodeoxygenation reaction across the intermediate Brønsted acid site. Acyl C=O bond activation is a key step in the HDO reaction and is highly dependent on the intensity and distribution of acid sites. Therefore, the increase in acid sites by phosphate treatment activates the O atom in the acyl bond and is easily attacked by the H atom. This is consistent with the results of several studies on Pt-based catalysts with different types of acid supports, as shown in Table 4.

On the other hand, the decarbonylation product CO adversely affects the Pt metal sites. The presence of phosphoric acid can prevent CO adsorption at the Pt active site, as shown in the CO adsorption measurement result. According to the experimental results and catalyst properties results, it can be seen that the HDO performance and selectivity of the Pt-based catalyst are greatly affected by the treated acid concentration.

Catalyst type Condition Conversion rate, %
(Conversion) Heptadecane selectivity, %
(Hepadecane selectivity) 5%Pd/C 300 ^o C, 1.5 MPa 58 75 1%Pt/γAl ₂ O ₃ 340 ^o C, 1.6 MPa 98 76.6 5%Pt/γAl ₂ O ₃ 325 ^o C, 2 MPa 46.2 65 5%Pt/Ga-MOF 320 ^o C, 2 MPa 92 76.6 5%Pt/Al-MOF 320 ^o C, 2 MPa 90 - 5%Pt/Cu-MOF 320 ^o C, 2 MPa 46 - 1%Pt/P@MIL-101(Cr) 300 ^o C, 2 MPa 95 75.5

<Experimental Example 6> Catalyst stability evaluation

The catalyst stability of the Pt/P@MIL catalyst for the hydrodeoxygenation of oleic acid was performed at 300° C., 2 MPa of hydrogen, and 24 hours.

As a result of evaluation of catalyst stability, as shown in FIG. 9 , the HDO conversion reached 75% after 2 hours of reaction, and was maintained at 75-79% for 24 hours. 75% of the product stream was heptadecane and octadecane (n-paraffins) and 5-6% of the cracking products, including shorter hydrocarbons (C9-C16), are the result of cracking reactions at the acid point. The oxygen-containing product consists primarily of non-deoxygenated compounds such as stearic acid and octadecanol, comprising 18% in the product stream. It can be seen that the HDO conversion and product distribution are stable in the range of 4% change during the reaction time.

As shown in FIG. 10 , after the catalyst stability evaluation, the average particle size of the spent catalyst increased from 2.53 to 3.25 nm, which is due to aggregation of Pt nanoparticles under severe reaction conditions.

So far, the present invention has been looked at around its preferred embodiments. Those of ordinary skill in the art to which the present invention pertains will be able to understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative point of view rather than a limiting point of view. The scope of the present invention is indicated in the claims rather than in the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (20)

Pre-treating MIL (Materials Institute Lavoisier)-based metal-organic frameworks (MOF) with a phosphoric acid (H ₃ PO ₄ ) solution (step 1); and
Platinum (Pt) aqueous solution is added dropwise to a solution prepared by adding the MIL-based metal-organic framework pretreated with the phosphoric acid solution to a hydrophobic organic solvent, and stirring, so that the platinum nanoparticles are formed in the micropores of the MIL-based metal-organic framework Including the step of fixing to (step 2);
The method for producing a catalyst for hydrodeoxygenation, characterized in that the concentration of the phosphoric acid solution in step 1 is 60 mM to 360 mM. The method of claim 1,
The concentration of the phosphoric acid solution is a manufacturing method, characterized in that 220 mM to 260 mM. delete delete delete delete The method of claim 1,
The metal-organic framework is MIL-47, MIL-53, MIL-100, MIL-101, MIL-102, MIL-110, MIL-125, MIL-127 or a mixture thereof. The method of claim 7,
The metal-organic framework is a manufacturing method, characterized in that MIL-101. The method of claim 8,
The MIL-101 is prepared by adding lithium acetate dihydrate to terephthalic acid dissolved in deionized water with stirring, mixing the metal salt powder, and performing a crystallization reaction. A manufacturing method, characterized in that. The method of claim 9,
The crystallization reaction is a manufacturing method, characterized in that using electric heating, ultrasonic waves, electromagnetic waves or electrochemical methods. The method of claim 9,
The metal salt is a manufacturing method, characterized in that it comprises at least one metal selected from the group consisting of Fe, Al, Cr, Ti, Sc, Cu and V. The method of claim 1,
After step 2, the method further comprising the step of reducing it in a hydrogen atmosphere. A catalyst for hydrodeoxygenation reaction prepared by the method of claim 1. The method of claim 13,
The catalyst for hydrodeoxygenation reaction is a catalyst for hydrodeoxygenation reaction, characterized in that it is used in the hydrodeoxygenation reaction using an organic oxygen compound as a starting material. 15. A method comprising: obtaining a saturated hydrocarbon compound by performing a hydrodeoxygenation reaction while introducing an oxygen-containing hydrocarbon compound and hydrogen gas _{of C 3-40} into a reactor containing the catalyst of claim 13; A method of reforming from a C _3-40 oxygen-containing hydrocarbon compound containing a saturated hydrocarbon. The method of claim 15,
_{The flow rate of the hydrogen gas is a method of reforming from a C 3-40} oxygen-containing hydrocarbon compound to saturated hydrocarbon, characterized in that 10 to 100 mL / min. The method of claim 15,
_{The hydrodeoxygenation reaction is a method of reforming from a C 3-40} oxygen-containing hydrocarbon compound to a saturated hydrocarbon, characterized in that it is carried out for 90 to 150 minutes under a hydrogen pressure of 250 to 350 ° C. and 1 to 3 MPa. The method of claim 15,
The C _3-40 oxygen-containing hydrocarbon compound is selected from the group consisting of palm oil, corn oil, sunflower oil, olive oil, soybean oil, rapeseed oil, cottonseed oil, rice bran oil and palm oil, or a vegetable oil of a mixture thereof; Animal fats and oils of one or a mixture thereof selected from the group consisting of tallow, pork, brisket and fish oil; Or a method of modifying a saturated hydrocarbon from oleic acid, palmitoleic oxygen-containing hydrocarbon compounds, and C _3-40 resan according to one or characterized in that the mixture thereof selected from the group consisting of erucic acid in a glass therefrom. delete delete

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