Nb-based monatomic catalyst for preparing hexadecane from palmitic acid and preparation method of Nb-based monatomic catalyst

Abstract

The invention belongs to the field of biomass energy utilization, and relates to an Nb-based monatomic catalyst for preparing hexadecane from palmitic acid and a preparation method of the Nb-based monatomic catalyst. The catalyst is synthesized by a hydrothermal method through a cocomplexation strategy of niobium ammonium oxalate and chloroplatinic acid, platinum atoms are introduced into a niobium oxide skeleton, the addition amount of platinum is only 0.54%, but the catalyst shows excellent selectivity and activity. The catalyst can effectively inhibit the decarboxylation side reaction, reduce the generation of by-products such as carbon dioxide, and improve the selectivity of long-chain alkane. According to the palmitic acid hydrogenation dehydration reaction method using the catalyst, high-selectivity and high-conversion-rate hexadecane production can be realized under specific reaction conditions (such as temperature, pressure, reaction time and the mass ratio of the catalyst to a substrate). The catalyst and the method have important application value in biomass energy utilization and reduction of carbon dioxide emission, especially in preparation of long-chain alkanes (such as diesel oil and aviation fuel).

Description

Technical Field

[0001] The invention belongs to the field of biomass energy utilization and relates to a Nb-based single-atom catalyst for preparing hexadecane from palmitic acid and a preparation method thereof. Background Art

[0002] Fatty acid hydrodeoxygenation is one of the key steps in extracting renewable fuels from biomass, especially in the preparation of long-chain alkanes (such as diesel and aviation fuel). However, traditional hydrodeoxygenation catalysts usually induce side reactions during the reaction, especially decarboxylation, which leads to carbon chain breakage and the production of a large amount of carbon dioxide and short-chain alkanes. The byproducts of such reactions not only reduce the selectivity of long-chain alkanes, but also bring unnecessary carbon losses, which have a negative impact on the economic and environmental performance of the process.

[0003] In recent years, precious metal catalysts such as palladium (Pd), platinum (Pt), and ruthenium (Ru) have shown excellent activity and selectivity in hydrodeoxygenation reactions, but their high prices and scarcity limit their large-scale application. 2 O 5 ) as a catalyst carrier has gradually become a research hotspot due to its good chemical stability and water resistance. Especially when single-atom-level platinum (Pt) active sites are loaded on its surface, this catalyst can inhibit decarboxylation reactions and avoid carbon chain breakage, thereby improving the selectivity of long-chain alkanes and reducing carbon dioxide generation. However, there are few studies on Nb-based single-atom catalysts, especially catalysts for efficient hydrodeoxygenation reactions of fatty acids. Summary of the invention

[0004] The purpose of the present invention is to provide a niobium oxide-supported single-atom platinum catalyst for efficient hydrodeoxygenation of fatty acids. The innovation of the catalyst is that it introduces Pt atoms into the Nb oxide framework through a co-complexation strategy of ammonium niobium oxalate and chloroplatinic acid through hydrothermal synthesis. The amount of platinum added is only 0.54%, but the catalyst has excellent selectivity and activity. While maintaining a high deoxygenation performance, the catalyst can effectively inhibit side reactions (such as decarboxylation reactions) and significantly reduce the generation of by-products such as carbon dioxide.

[0005] The technical solution provided by the present invention is as follows:

[0006] A preparation method of a Nb-based single-atom catalyst for preparing hexadecane from palmitic acid comprises the following steps: adding a hexadecyltrimethylammonium bromide solution and a chloroplatinic acid solution dropwise into an ammonium niobium oxalate solution, stirring and mixing the mixture, subjecting the mixture to a hydrothermal reaction, washing the product, filtering it, and drying it, extracting it with Soxhlet, and then washing it with methanol reflux, drying the product, and calcining it in a muffle furnace to obtain the Nb-based single-atom catalyst for preparing hexadecane from palmitic acid.

[0007] Specifically, the hexadecyltrimethylammonium bromide solution, the chloroplatinic acid precursor, and the niobium oxalate are mixed with CTAB and stirred at the same time and then added into the hydrothermal reactor.

[0008] Furthermore, the temperature of the hydrothermal reaction is 160-200° C., and the reaction time is 24 hours.

[0009] Furthermore, the calcination temperature is 350-550°C.

[0010] Furthermore, the heating rate of the calcination is 0.8~1.2℃ / min.

[0011] Furthermore, the template agent is a cationic surfactant hexadecyltrimethylammonium bromide.

[0012] The present invention also provides a Nb-based single-atom catalyst for preparing hexadecane from palmitic acid, which is prepared by the above-mentioned preparation method.

[0013] The present invention also provides the use of the catalyst in fatty acid hydrodeoxygenation reaction, the catalyst and palmitic acid are placed in a high-pressure reactor, and high-purity hydrogen is used to replace the gas in the reactor.

[0014] Furthermore, the reaction solvent is n-decane.

[0015] Furthermore, the hydrodeoxygenation reaction is carried out at 180-260° C. for 1-8 hours.

[0016] Furthermore, after high-purity hydrogen is used to replace the gas in the reactor, the pressure in the reactor is maintained at 0.1~3MPa.

[0017] Furthermore, the mass ratio of the catalyst to palmitic acid is 1:1-10.

[0018] Beneficial Effects

[0019] The present invention prepares a low-load, high-activity Nb-based single-atom high-efficiency catalyst through a co-complexation approach, which can be used for the reaction of preparing hexadecane from palmitic acid. The catalyst of the present invention has a low degree of cracking at a relatively high temperature. At 240°C and 3Mpa, the yield of pentadecane is only 1.3%. At low temperatures, the selectivity, conversion rate and yield of hexadecane are excellent. At 240°C and 3Mpa, the preferred catalyst is 0.5%wtPt-Nb 2O 5 ·H 2 The hexadecane yield of O-350 is 87.3, which is 85% higher than that of commercial 5%wtPt / C catalyst. 2 O 5 ·H 2 O-350, the hexadecane yield increased by 34.2%. Compared with the catalyst 2%wt Pt-Nb prepared by nonionic surfactant P123 2 O 5 ·H 2 O (P123), the hexadecane yield increased by 39.2%, and the catalyst still maintained high activity after multiple reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the XRD diagram of the catalyst with metal introduced, without metal introduced and after high temperature calcination;

[0021] Figure 2 This is the SEM of the catalyst with 0.5wt% Pt content; ad and il are microscopic morphologies, and fh and nq are mappings;

[0022] Figure 3 This is the TEM of the catalyst with 0.5wt% Pt content;

[0023] Figure 4 This is the TEM of the catalyst with 0.5wt% Pt content after the reaction;

[0024] Figure 5 This is a high-resolution spherical aberration electron microscope of a catalyst with a Pt content of 0.5wt%;

[0025] Figure 6 It is the adsorption-desorption curve of the catalyst with 0.5wt% Pt content and the catalyst without metal;

[0026] Figure 7 This is the pore size distribution curve of the catalyst with 0.5wt% Pt content. DETAILED DESCRIPTION

[0027] The following is a further description of the present invention, rather than a limitation of the present invention.

[0028] A Nb-based single-atom catalyst for preparing hexadecane from palmitic acid, the preparation method comprising the following steps:

[0029] Step 1. Dissolve 0.1 mol of ammonium niobium oxalate in 100 mL of deionized water heated to 75°C, referred to as solution A.

[0030] Step 2. Dissolve 2 g of CTAB (cetyltrimethylammonium bromide) in deionized water heated to 35°C, referred to as solution B.

[0031] Step 3. Dissolve a specified amount of chloroplatinic acid (0.5-1 wt% of loading, the loading amount is calculated by weighing the mass of the support in the parallel group that was pre-calculated without adding metal) in 5 mL of deionized water, recorded as solution C.

[0032] Step 4. Add solution B (the solution is transparent) and solution C, which have been stirred for a while, dropwise into solution A and stir vigorously for a while.

[0033] Step 5. After stirring, transfer to a hydrothermal reactor and perform hydrothermal reaction at 180°C for 24 hours.

[0034] Step 6. After washing and filtering the hydrothermal catalyst, place it in an oven at 60°C and dry it for 12 hours.

[0035] Step 7. The dried solid is refluxed and washed in a Soxhlet extractor for 48 hours, with methanol as the reflux solvent.

[0036] Step 8. The catalyst after reflux washing is placed in an oven at 60°C for drying.

[0037] Step 9. The dried catalyst is placed in a muffle furnace and calcined at a temperature of 350°C to obtain Pt-Nb 2 O 5 ·H 2 O catalyst.

[0038] The amount of CTAB used in step 2 is 1 g, 3 g, 5 g, and the most preferred amount is 3 g. For comparison, a nonionic surfactant P123 (polyoxypropylene polyoxyethylene copolymer) is used instead of CTAB to prepare a comparative catalyst.

[0039] In step 3, different amounts of active metals were added, with loadings of 0.3 wt%, 0.5 wt%, 0.7 wt%, and 0.9 wt%, respectively, and the reaction was carried out at 240°C, 3 MPa, and 4 hours.

[0040] In step 7, ethanol or methanol can be used for the Soxhlet extraction of the catalyst, and methanol is most preferred.

[0041] The calcination temperature of the catalyst in step 9 is 350°C, and the heating rate is 1°C / min. In particular, the catalyst without metal addition is amorphous, and the catalyst with metal addition is between crystalline and amorphous. Figure 1 For XRD.

[0042] The catalyst has a platinum addition of 0.54% and has excellent selectivity and activity.

[0043] The physical property parameters of the preferred catalyst are shown in the following table:

[0044]

[0045] according to Figure 2 SEM observation shows that the rod-like units are interlaced with each other to form grid-shaped slit holes. Figure 6 The adsorption-desorption curves show that this pore structure becomes more obvious after the introduction of Pt. Figure 7 This is the pore size distribution curve. The average pore size of the catalyst is 12nm, which belongs to the mesoporous category.

[0046] The metal dispersion and particle size of the preferred catalyst are shown in the following table:

[0047]

[0048] Although Figure 3 Pt nanoclusters of about 3 nm were observed in TEM. Figure 5 The medium spherical aberration electron microscope EDS can clearly show the uniformly dispersed Pt on the carrier skeleton.

[0049] The metal content of the preferred catalyst is shown in the following table:

[0050]

[0051] Palmitic acid hydrogenation dehydration reaction:

[0052] Step 1. Weigh a certain amount of palmitic acid as a model compound. Weigh a certain amount of catalyst, and the mass ratio of reaction substrate to catalyst is 1:1-1:10.

[0053] Step 2. Use 10 ml of n-decane as the reaction solvent. Add the material in step 1 into a micro autoclave.

[0054] Step 3. Replace the gas in the high-pressure reaction with hydrogen at pressures of 0.1, 1, 2, 3, and 4 MPa.

[0055] Step 4: Carry out hydrogenation dehydration reaction at a temperature of 180-260°C.

[0056] Step 5. After the reaction is completed, the product is qualitatively and quantitatively analyzed by gas chromatography.

[0057] Example 1

[0058] Catalyst preparation: 0.1 mol of ammonium niobium oxalate was dissolved in 100 mL of deionized water heated to 75 ° C, recorded as solution A. CTAB was dissolved in deionized water heated to 35 ° C, recorded as solution B. Chloroplatinic acid with a loading of 0.5 wt% was dissolved in 5 mL of deionized water, recorded as solution C, and the loading amount was calculated by weighing the carrier mass of the parallel group that was pre-calcined without adding metal. Solution B and solution C, which had been stirred for a period of time, were added dropwise to solution A at the same time, and after vigorous stirring for a period of time, they were transferred to the hydrothermal reactor and hydrothermally reacted at 180 ° C for 24 hours. After washing and filtration of the hydrothermal catalyst, it was placed in a 60 ° C oven for 12 hours. The dried solid was refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent was methanol. The washed catalyst was placed in a 60 ° C oven for drying. The dried catalyst was placed in a muffle furnace and calcined at 350 ° C at a rate of 1 ° C / min for 6 hours. 0.5%wtPt-Nb 2 O 5 ·H 2 O-350 catalyst.

[0059] Catalyst evaluation: 0.5%wt Pt-Nb was weighed according to a mass ratio of 1:5. 2 O 5 ·H 2 The O-350 catalyst and palmitic acid were placed in a micro-high pressure reactor, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3 MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane is 87.3%.

[0060] Example 2

[0061] Catalyst preparation: 0.1 mol of ammonium niobium oxalate was dissolved in 100 mL of deionized water heated to 75 ° C, recorded as solution A. CTAB was dissolved in deionized water heated to 35 ° C, recorded as solution B. Chloroplatinic acid with a loading of 0.5 wt% was dissolved in 5 mL of deionized water, recorded as solution C, and the loading amount was calculated by weighing the mass of the carrier in the parallel group that was pre-calcined without adding metal. Solution B and solution C, which had been stirred for a period of time, were added dropwise to solution A at the same time, and after vigorous stirring for a period of time, they were transferred to the hydrothermal reactor and hydrothermally reacted at 160 ° C for 24 hours. After washing and filtration of the hydrothermal catalyst, it was placed in a 60 ° C oven for 12 hours. The dried solid was refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent was methanol. The washed catalyst was placed in a 60 ° C oven for drying. The dried catalyst was placed in a muffle furnace and raised to 350 ° C at a rate of 1 ° C / min and calcined for 6 hours. 0.5%wtPt-Nb 2 O 5 ·H 2 O-350 catalyst.

[0062] Catalyst evaluation: 0.5%wt Pt-Nb was weighed according to a mass ratio of 1:5. 2 O 5 ·H 2 The O-350 catalyst and palmitic acid were placed in a micro-high pressure reactor, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3 MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane was 71.2%.

[0063] Example 3

[0064] Catalyst preparation: 0.1 mol of ammonium niobium oxalate was dissolved in 100 mL of deionized water heated to 75 ° C, recorded as solution A. CTAB was dissolved in deionized water heated to 35 ° C, recorded as solution B. Chloroplatinic acid with a loading of 0.5 wt% was dissolved in 5 mL of deionized water, recorded as solution C, and the loading amount was calculated by weighing the mass of the carrier in the parallel group that was pre-calcined without adding metal. Solution B and solution C, which had been stirred for a period of time, were added dropwise to solution A at the same time, and after vigorous stirring for a period of time, they were transferred to the hydrothermal reactor and hydrothermally reacted at 200 ° C for 24 hours. After washing and filtration of the hydrothermal catalyst, it was placed in a 60 ° C oven for 12 hours. The dried solid was refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent was methanol. The washed catalyst was placed in a 60 ° C oven for drying. The dried catalyst was placed in a muffle furnace and calcined at 350 ° C at a rate of 1 ° C / min for 6 hours. 0.5%wtPt-Nb 2 O 5 ·H 2 O-350 catalyst.

[0065] Catalyst evaluation: 0.5%wt Pt-Nb was weighed according to a mass ratio of 1:5. 2 O 5 ·H 2 The O-350 catalyst and palmitic acid were placed in a micro-autoclave, and the gas was replaced ten times with high-purity hydrogen and the pressure was maintained at 3MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane is 60.8%.

[0066] Example 4

[0067] Catalyst preparation: 0.1 mol of ammonium niobium oxalate was dissolved in 100 mL of deionized water heated to 75 ° C, recorded as solution A. CTAB was dissolved in deionized water heated to 35 ° C, recorded as solution B. Chloroplatinic acid with a loading of 0.3 wt% was dissolved in 5 mL of deionized water, recorded as solution C, and the loading amount was calculated by weighing the mass of the carrier in the parallel group that was pre-calcined without adding metal. Solution B and solution C, which had been stirred for a period of time, were added dropwise to solution A at the same time, and after vigorous stirring for a period of time, they were transferred to the hydrothermal reactor and hydrothermally reacted at 180 ° C for 24 hours. After washing and filtration of the hydrothermal catalyst, it was placed in a 60 ° C oven for 12 hours. The dried solid was refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent was methanol. The washed catalyst was placed in a 60 ° C oven for drying. The dried catalyst was placed in a muffle furnace and raised to 350 ° C at a rate of 1 ° C / min and calcined for 6 hours. 0.3Pt-Nb 2 O 5 ·H 2 O-350 catalyst.

[0068] Catalyst evaluation: Weigh 0.3Pt-Nb in a mass ratio of 1:5 2 O 5 ·H 2 The O-350 catalyst and palmitic acid were placed in a micro-autoclave, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3 MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane is 68.4%.

[0069] Example 5

[0070] Catalyst preparation: 0.1 mol of ammonium niobium oxalate was dissolved in 100 mL of deionized water heated to 75 ° C, recorded as solution A. CTAB was dissolved in deionized water heated to 35 ° C, recorded as solution B. Chloroplatinic acid with a loading of 0.5 wt% was dissolved in 5 mL of deionized water, recorded as solution C, and the loading amount was calculated by weighing the mass of the carrier of the parallel group that was pre-calcined without adding metal. Solution B and solution C, which had been stirred for a period of time, were added dropwise to solution A at the same time, and after vigorous stirring for a period of time, they were transferred to the hydrothermal reactor and hydrothermally reacted at 180 ° C for 24 hours. After washing and filtration of the hydrothermal catalyst, it was placed in a 60 ° C oven for 12 hours. The dried solid was refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent was methanol. The washed catalyst was placed in a 60 ° C oven for drying. The dried catalyst was placed in a muffle furnace and raised to 450 ° C at a rate of 1 ° C / min and calcined for 6 hours. 0.5Pt-Nb 2 O 5 ·H 2 O-450 catalyst.

[0071] Catalyst evaluation: Weigh 0.5Pt-Nb in a mass ratio of 1:5 2 O 5 ·H 2 O-450 catalyst and palmitic acid were placed in a micro-autoclave, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane was 1.6%.

[0072] Example 6

[0073] Catalyst preparation: 0.1 mol of ammonium niobium oxalate was dissolved in 100 mL of deionized water heated to 75 ° C, recorded as solution A. CTAB was dissolved in deionized water heated to 35 ° C, recorded as solution B. Chloroplatinic acid with a loading of 0.5 wt% was dissolved in 5 mL of deionized water, recorded as solution C, and the loading amount was calculated by weighing the mass of the carrier in the parallel group that was pre-calcined without adding metal. Solution B and solution C, which had been stirred for a period of time, were added dropwise to solution A at the same time, and after vigorous stirring for a period of time, they were transferred to the hydrothermal reactor and hydrothermally reacted at 180 ° C for 24 hours. After washing and filtration of the hydrothermal catalyst, it was placed in a 60 ° C oven for 12 hours. The dried solid was refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent was methanol. The washed catalyst was placed in a 60 ° C oven for drying. The dried catalyst was placed in a muffle furnace and raised to 550 ° C at a rate of 1 ° C / min and calcined for 6 hours. 0.5Pt-Nb 2 O 5 ·H 2 O-550 catalyst.

[0074] Catalyst evaluation: Weigh 0.5Pt-Nb in a mass ratio of 1:5 2 O 5 ·H 2 O-550 catalyst and palmitic acid were placed in a micro-high pressure reactor, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane is 5.4%.

[0075] Example 7

[0076] Catalyst preparation: 0.1 mol of ammonium niobium oxalate was dissolved in 100 mL of deionized water heated to 75 ° C, recorded as solution A. CTAB was dissolved in deionized water heated to 35 ° C, recorded as solution B. Chloroplatinic acid with a loading of 0.7 wt% was dissolved in 5 mL of deionized water, recorded as solution C, and the loading amount was calculated by weighing the mass of the carrier in the parallel group that was pre-calcined without adding metal. Solution B and solution C, which had been stirred for a period of time, were added dropwise to solution A at the same time, and after vigorous stirring for a period of time, they were transferred to the hydrothermal reactor and hydrothermally reacted at 180 ° C for 24 hours. After washing and filtration of the hydrothermal catalyst, it was placed in a 60 ° C oven for 12 hours. The dried solid was refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent was methanol. The washed catalyst was placed in a 60 ° C oven for drying. The dried catalyst was placed in a muffle furnace and raised to 350 ° C at a rate of 1 ° C / min and calcined for 6 hours. 0.7Pt-Nb 2 O 5 ·H 2 O-350 catalyst.

[0077] Catalyst evaluation: Weigh 0.7Pt-Nb in a mass ratio of 1:5 2 O 5 ·H 2 The O-350 catalyst and palmitic acid were placed in a micro-autoclave, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3 MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane is 86.8%.

[0078] Example 8

[0079] Catalyst preparation: 0.1 mol of ammonium niobium oxalate was dissolved in 100 mL of deionized water heated to 75 ° C, recorded as solution A. CTAB was dissolved in deionized water heated to 35 ° C, recorded as solution B. Chloroplatinic acid with a loading of 0.9 wt% was dissolved in 5 mL of deionized water, recorded as solution C, and the loading amount was calculated by weighing the mass of the carrier in the parallel group that was pre-calcined without adding metal. Solution B and solution C, which had been stirred for a period of time, were added dropwise to solution A at the same time, and after vigorous stirring for a period of time, they were transferred to the hydrothermal reactor and hydrothermally reacted at 180 ° C for 24 hours. After washing and filtration of the hydrothermal catalyst, it was placed in a 60 ° C oven for 12 hours. The dried solid was refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent was methanol. The washed catalyst was placed in a 60 ° C oven for drying. The dried catalyst was placed in a muffle furnace and raised to 350 ° C at a rate of 1 ° C / min and calcined for 6 hours. 0.9Pt-Nb 2 O 5 ·H 2 O-350 catalyst.

[0080] Catalyst evaluation: Weigh 0.9Pt-Nb in a mass ratio of 1:5 2 O 5 ·H 2 The O-350 catalyst and palmitic acid were placed in a micro-autoclave, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3 MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane is 87.1%.

[0081] Example 9

[0082] Catalyst preparation: Same as Example 1

[0083] Catalyst evaluation: Weigh 0.5Pt-Nb according to the mass ratio of 1:1, 1:2, 1:3, 1:4, 1:5, 1:10 2 O 5 ·H 2 The O-350 catalyst and palmitic acid were placed in a micro-high pressure reactor, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3 MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yields of hexadecane were 86.8%, 86.4%, 86.6%, 86.7%, 87.3% and 35.7%, respectively.

[0084] Example 10

[0085] Catalyst preparation: Same as Example 1

[0086] Catalyst evaluation: Weigh 0.5Pt-Nb in a mass ratio of 1:5 2 O 5 ·H 2 O-350 catalyst and palmitic acid were placed in a micro-autoclave, and the gas was replaced ten times with high-purity hydrogen and maintained at 0.1, 1, 2, and 3 MPa pressures. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yields of hexadecane were 31.8%, 51.2%, 68.3%, and 87.3%, respectively.

[0087] Embodiment 11

[0088] Catalyst preparation: Same as Example 1

[0089] Catalyst evaluation: Weigh 0.5Pt-Nb in a mass ratio of 1:10 2 O 5 ·H 2The O-350 catalyst and palmitic acid were placed in a micro-autoclave, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3 MPa. The reaction was carried out at 240°C for 1, 2, 3, 4, 6, and 8 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yields of hexadecane were 10.3%, 11.2%, 30.2%, 35.7%, 58.6%, and 82.2%, respectively.

[0090] Example 12

[0091] Catalyst preparation: Same as Example 1

[0092] Catalyst evaluation: Weigh 0.5Pt-Nb in a mass ratio of 1:5 2 O 5 ·H 2 O-350 catalyst and palmitic acid were placed in a micro-high pressure reactor, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3MPa. The reaction was carried out at 180°C, 200°C, 220°C, 240°C, and 260°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yields of hexadecane were 5.1%, 17.9%, 61.6%, 87.3%, and 86.4%, respectively. The mass yields of pentadecane were 1.4%, 2.6%, 1.8%, 1.3%, and 2.2%, respectively.

[0093] Example 13

[0094] Catalyst preparation: Same as Example 1

[0095] Catalyst evaluation: Weigh 0.5Pt-Nb in a mass ratio of 1:10 2 O 5 ·H 2 The O-350 catalyst and palmitic acid were placed in a micro-autoclave, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. After 25 reactions, the selectivity of palmitic acid was still 99.1%.

[0096] Comparative Example 1

[0097] Catalyst: Commercial Pd / C catalyst with a loading of 5 wt%.

[0098] Catalyst evaluation: 0.5%wt Pd / C catalyst and palmitic acid were weighed in a mass ratio of 1:5 and placed in a micro-autoclave. High-purity hydrogen was used to replace the gas ten times and the pressure was maintained at 3MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane was 2.3%.

[0099] Comparative Example 2

[0100] Catalyst preparation: Use 0.1 mol of ammonium niobium oxalate to dissolve in 100 mL of deionized water heated to 75°C, recorded as solution A. Dissolve CTAB in deionized water heated to 35°C, recorded as solution B. Dissolve 2 wt% of chloroplatinic acid in 5 mL of deionized water, recorded as solution C, and the loading amount is calculated by weighing the mass of the carrier in a parallel group that has been pre-calcined without adding metal. Solution B is placed in a 180°C hydrothermal reaction for 24 hours. After the hydrothermal reaction, the catalyst is washed and filtered, and then placed in a 60°C oven to dry for 12 hours. The dried solid is refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent is methanol. The washed catalyst is placed in a 60°C oven to dry. The dried catalyst is placed in a muffle furnace and raised to 350°C at a rate of 1°C / min and calcined for 6 hours. Obtain Nb 2 O 5 ·H 2 O-350 catalyst, Nb 2 O 5 ·H 2 The O-350 catalyst was placed in the C solution and stirred at 75 °C for 24 hours to obtain 2%wt Pt / Nb 2 O 5 ·H 2 O-350.

[0101] Catalyst evaluation: weigh 2%wt Pt / Nb at a mass ratio of 1:5 2 O 5 ·H 2 O-350 catalyst and palmitic acid were placed in a micro-high pressure reactor, and the gas was replaced ten times with high-purity hydrogen and maintained at a pressure of 3MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted using gas chromatography. The mass yield of hexadecane was 53.1%.

[0102] Comparative Example 3

[0103] Catalyst preparation: 0.1 mol of ammonium niobium oxalate was dissolved in 100 mL of deionized water heated to 75 ° C, recorded as solution A. P123 was dissolved in deionized water heated to 35 ° C, recorded as solution B. 2 wt% of chloroplatinic acid was dissolved in 5 mL of deionized water, recorded as solution C, and the loading amount was calculated by weighing the carrier mass of the parallel group that was pre-calcined without adding metal. Solution B and solution C, which had been stirred for a period of time, were added dropwise to solution A at the same time, and after vigorous stirring for a period of time, they were transferred to the hydrothermal reactor and hydrothermally reacted at 180 ° C for 24 hours. After washing and filtration of the hydrothermal catalyst, it was placed in a 60 ° C oven for 12 hours. The dried solid was refluxed and washed in a Soxhlet extractor for 48 hours, and the reflux solvent was methanol. The washed catalyst was placed in a 60 ° C oven for drying. The dried catalyst was placed in a muffle furnace and calcined at 350 ° C at a rate of 1 ° C / min for 6 hours. 2%wt Pt-Nb 2 O 5 ·H 2 O(P123) catalyst.

[0104] Catalyst evaluation: 2%wt Pt-Nb was weighed according to a mass ratio of 1:5. 2 O 5 ·H 2 O (P123) catalyst and palmitic acid were placed in a micro-high pressure reactor, and the gas was replaced ten times with high-purity hydrogen and the pressure was maintained at 3MPa. The reaction was carried out at 240°C for 4 hours. After the reaction, the mass yield of the product (the theoretical yield of n-hexadecane is 88.3%) was counted by gas chromatography. The mass yield of hexadecane is 48.1%.

Claims

1. A method for preparing a Nb-based single-atom catalyst for preparing hexadecane from palmitic acid, characterized in that: The hexadecyltrimethylammonium bromide solution and the chloroplatinic acid solution are added dropwise to the ammonium niobium oxalate solution, and after being fully stirred and mixed, the mixed solution is subjected to a hydrothermal reaction, the product is washed, filtered and dried, and then Soxhlet extraction is performed and the product is refluxed and washed with methanol. The product is dried and calcined in a muffle furnace to obtain a Nb-based single-atom catalyst for preparing hexadecane from palmitic acid.

2. The method for preparing a Nb-based single-atom catalyst for preparing hexadecane from palmitic acid according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 160-200° C., and the reaction time is 24 hours.

3. The method for preparing a Nb-based single-atom catalyst for preparing hexadecane from palmitic acid according to claim 1, characterized in that: The calcination temperature is 350-550°C.

4. The method for preparing a Nb-based single-atom catalyst for preparing hexadecane from palmitic acid according to claim 3, characterized in that: The heating rate of calcination is 0.8~1.2℃ / min.

5. A Nb-based single-atom catalyst for preparing hexadecane from palmitic acid, characterized in that: Prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the catalyst according to claim 5 in the hydrodeoxygenation reaction of fatty acids, characterized in that: The catalyst and palmitic acid are placed in a high-pressure reactor, and high-purity hydrogen is used to replace the gas in the reactor.

7. The use according to claim 6, characterized in that: The reaction solvent is n-decane.

8. The use according to claim 6, characterized in that: The hydrodeoxygenation reaction is carried out at 180-260°C for 1-8 hours.

9. The use according to claim 6, characterized in that: After replacing the gas in the reactor with high-purity hydrogen, the pressure in the reactor is maintained at 0.1~3MPa.

10. The use according to claim 6, characterized in that: The mass ratio of the catalyst to palmitic acid is 1:1-10.

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