A method for producing naphthenic liquid fuel by hydrodeoxygenation of lignin phenolic derivatives

Abstract

The present application relates to a method for preparing cycloalkane liquid fuel by hydrodeoxygenation of lignin phenolic derivatives, which adopts a catalyst abbreviated as MN / S, wherein N is an additive, M is an active metal, S is a catalyst carrier hydroxyapatite (HAP), and M is loaded on the carrier, wherein the additive N is dispersed in the form of single-atom dispersion on the surface of the active metal M particles, the additive N is one or more of the following noble metals: Pt, Pd, Rh, Ru, Au, etc., and M is one or more of the following non-noble metals: Co, Ni. The single-atom catalyst not only greatly reduces the amount of noble metal, reduces the cost, and achieves 100% atom utilization rate, but also has excellent stability and selectivity. The method provides a way to mass-produce cycloalkane liquid fuel from non-fossil sources, has good application prospects, and is conducive to achieving the strategic goal of "carbon peak and carbon neutralization".

Description

Technical Field

[0001] This invention belongs to the field of catalytic conversion technology of lignin phenolic derivatives, and relates to a method for preparing cycloalkanes by highly efficient catalysis of lignin phenolic derivatives using a single-atom alloy catalyst. Background Technology

[0002] Lignin is the second most abundant organic compound in nature and the only renewable resource in nature that can provide aromatic hydrocarbon structures. It can effectively replace fossil fuels in the production of cycloalkane liquid fuels. Developing and utilizing lignin is one of the important ways to achieve clean and efficient utilization of biomass resources and "carbon peaking and carbon neutrality", which is in line with my country's strategic needs to vigorously develop biomass energy during the "14th Five-Year Plan" period. Due to the high oxygen content in lignin, directly using lignin and its phenolic derivatives as transportation fuel has defects such as high viscosity, poor stability, low calorific value and equipment corrosion (Chem.Rev., 2015, 115(21), 11559-11624). Therefore, deoxygenation treatment of lignin and its phenolic derivatives is beneficial to improving the quality of liquid fuels and preparing high-value-added chemicals. Among them, hydrodeoxygenation is considered to be one of the most effective methods. Currently, the research on the hydrodeoxygenation of lignin phenolic derivatives mainly uses noble metals as catalytic active centers, which has problems such as high metal loading, high catalyst preparation cost, low selectivity of cycloalkane products, and poor stability (Nat. Commun., 2017, 8, 16104-16112; J. Catal., 2019, 375, 202-212; Catal. Sci. Technol., 2018, 8(23), 6129-6136; Catal. Sci. Technol., 2018, 8(23), 6129-6136; Chinese Patent CN201510032509.9; Chinese Patent CN201810058249.6). In recent years, supported single-atom catalysts have shone brightly in the field of heterogeneous catalysis due to their theoretical metal atom utilization rate of 100%. The extremely high metal utilization rate of single-atom catalysts results in significantly higher reactivity per surface atom compared to nanocatalysts, and the interaction between the metal center and the support can influence the inherent electronic properties of the metal center by modulating the local environment. However, the development of single-atom catalysts has been extremely slow in the field of lignin conversion to produce cycloalkanes and other high-value-added products (Nat. Commun., 2021, 12, 416-424). The main reason is that the extremely low loading of single-atom active metal in the catalyst results in weak activation and dissociation of hydrogen, and there is competitive adsorption between substrate activation and hydrogen dissociation, which fails to meet the reaction requirements, leading to slow reaction rates and reduced product selectivity (Chem. Soc. Rev., 2020, 49, 3764-3782). Therefore, developing more stable and efficient single-atom catalysts for the hydrodeoxygenation of lignin phenolic derivatives to produce cycloalkanes as liquid fuels is of great significance. Summary of the Invention

[0003] This invention proposes a highly efficient catalytic method for preparing cycloalkanes from lignin phenolic derivatives. This method enables efficient CO bond cleavage in lignin phenolic derivatives, lignin, and native lignocellulose, ultimately achieving a one-pot, highly efficient production of cycloalkanes as liquid fuels. The prepared single-atom catalyst not only significantly reduces the amount of precious metals used, lowers costs, and achieves 100% atom utilization, but also exhibits excellent stability and selectivity. This method provides a non-fossil-derived route for the large-scale production of cycloalkanes as liquid fuels, showing promising application prospects and contributing to the strategic goal of "carbon peaking and carbon neutrality."

[0004] A method for efficiently catalyzing the preparation of cycloalkane liquid fuels from lignin phenolic derivatives using a single-atom catalyst, comprising the following steps:

[0005] First, the hydroxyapatite (HAP) support was calcined in air at 300-600℃ for 0.5-6 h. The catalyst was prepared by an equal-volume co-impregnation method, as follows: An active component M (M = Co, Ni) and an auxiliary agent N (N = Pt, Pd, Rh, Ru, Au) precursor solution were uniformly and equally impregnated onto 2-4 g of the HAP support. The loading of active metal M was 2-5 wt.%, preferably 3-5 wt.%; the loading of auxiliary agent N was 0.05-0.5 wt.%, preferably 0.2-0.5 wt.%; the average size of the active metal M nanoparticles was between 3-15 nm (particle size distribution range 2-20 nm), preferably 4-10 nm (particle size distribution range 3-12 nm), ensuring that the auxiliary agent N was uniformly dispersed in single-atom form on the active metal M nanoparticles and formed a surface alloy phase with M. The prepared catalyst was first freeze-dried (-45 to -50°C) for 3-6 hours, followed by calcination in air at 200-500°C for 1-4 hours, preferably at 300-400°C for 2-3 hours. The resulting catalyst was then reduced in hydrogen at 200-500°C for 1-4 hours, preferably at 300-400°C for 1-2 hours, to obtain the single-atom alloy catalyst MN / HAP. The molar ratio of the promoter N to the active metal M was between 0.02 and 0.2, preferably between 0.02 and 0.1.

[0006] The performance evaluation of the preparation of cycloalkanes by hydrogenation deoxygenation of lignin phenolic derivatives from native lignocellulose or biomass was carried out in an intermittent high-pressure autoclave reactor. The substrates included lignin phenolic derivatives such as 4-propylguaiacol, 4-methylguaiacol, guaiacol, phenol, and eugenol, as well as native lignocellulose from pine, miscanthus, and corn cob. The operating conditions were as follows: substrate concentration 1-10 wt.%, preferably 1-5 wt.%; reaction temperature 200-280℃, preferably 240-280℃; hydrogen pressure 0.1-5 MPa, preferably 2-5 MPa; reaction time 0.5-6 h, preferably 4-6 h; C8-C10 straight-chain alkanes as solvents, preferably n-decane; and n-dodecane as an internal standard.

[0007] Advantages of this invention:

[0008] (1) In the multifunctional catalyst prepared by this invention, the active component M is highly dispersed on the support surface, and the auxiliary agent N exists in the form of single atoms on the surface of the active metal M particles rather than on the support surface. The auxiliary agent and the active metal form a single-atom alloy phase on the surface, which greatly promotes the CO breakage step in the conversion of lignin phenolic derivatives. The catalyst is simple to prepare, easy to recover, the product is easy to separate, has high selectivity for propylcyclohexane, and the reaction process is green and environmentally friendly.

[0009] (2) Compared with the single-component M / HAP catalyst, the selectivity of propylcyclohexane is significantly improved after co-impregnation with N, and the N and active metal M form a single-atom alloy, which lays a good foundation for improving the stability of the catalyst.

[0010] (3) Compared with the currently reported literature and patents, this catalyst has a significantly reduced noble metal loading and a significantly lower catalyst preparation cost, while maintaining an excellent propylcyclohexane yield. The yield of propylcyclohexane per unit time and per unit mass of noble metal is much higher than the results reported so far (space-time yield = 315 g·g). Ru -1 ·h -1 It has excellent prospects for industrial applications. Attached Figure Description

[0011] Figure 1 Transmission electron microscopy (TEM) image (a), corresponding elemental surface scan (bd) and aberration-corrected TEM image (ef) of the CoRu / HAP single-atom alloy catalyst (the white circle in Figure e represents a Ru single atom).

[0012] Figure 2 Transmission electron microscopy (TEM) image (a) and line scan image (b) of the CoRu / HAP single-atom alloy catalyst (top: Co, bottom: Ru).

[0013] Figure 3Transmission electron microscopy image of the CoRu / HAP nanoparticle catalyst.

[0014] Figure 4 Stability test of 4-propylguaiacol to propylcyclohexane catalyzed by .CoRu / HAP single-atom alloy catalyst. Reaction conditions: 0.2 g 4-propylguaiacol, 10 g n-decane, 0.2 g n-dodecane (internal standard), 0.05 g 3Co0.2Ru / HAP, reaction temperature 260℃, reaction pressure 2 MPa, reaction time 4 h, rotation speed 500 rpm. Detailed Implementation

[0015] The specific embodiments of the present invention will be described in detail below with reference to the technical solutions and accompanying drawings.

[0016] Example 1

[0017] HAP carrier activation

[0018] 10g of HAP carrier was heated from room temperature to 500℃ in air at a heating rate of 5℃ / min and calcined for 2h. The white solid powder obtained after cooling was the activated HAP carrier.

[0019] Example 2

[0020] Preparation of single metal catalyst M / HAP

[0021] Taking the preparation of a single-metal catalyst of 3 wt.% Co / HAP as an example (abbreviated as 3Co / HAP, where the mass of Co on the catalyst is 3 wt.%, the same below): An appropriate amount of cobalt acetate solution (Co mass fraction: 9.45 wt.%) was impregnated onto the HAP support obtained in Example 1 by equal volume, and the loading of the active component Co in the catalyst was 3 wt.%. The catalyst was freeze-dried (-45℃) for 6 h, then dried in an oven at 120℃ for 2 h, followed by calcination at 400℃ in air for 2 h, and then further reduced at 400℃ in hydrogen atmosphere for 2 h. After cooling, it was passivated with 1% O2 / N2 (volume fraction) for 6 h, and the resulting catalyst was denoted as 3Co / HAP.

[0022] Example 3

[0023] Preparation of single-metal catalyst N / HAP

[0024] Taking the preparation of a single-metal catalyst of 0.2 wt.% Ru / HAP as an example (abbreviated as 0.2Ru / HAP, where the mass of Ru on the catalyst is 0.2 wt.%, the same below): An appropriate amount of ruthenium chloride solution (Ru mass fraction: 3.24 wt.%) was impregnated onto the HAP support obtained in Example 1 by equal volume, and the loading of the active component Ru in the catalyst was 0.2 wt.%. The catalyst was freeze-dried (-45℃) for 6 h, then dried in an oven at 120℃ for 2 h, followed by calcination at 400℃ in air atmosphere for 2 h, and then further reduced at 400℃ in hydrogen atmosphere for 2 h. After cooling, it was passivated with 1% O2 / N2 (volume fraction) for 6 h, and the resulting catalyst was denoted as 0.2Ru / HAP.

[0025] Example 4

[0026] Preparation of bimetallic single-atom alloy catalyst MN / HAP

[0027] Taking the preparation method of the single-atom alloy catalyst 3wt.%Co0.2wt.%Ru / HAP as an example (abbreviated as 3Co0.2Ru / HAP, where the numbers represent: the mass of Co on the catalyst is 3wt.%, and the mass of Ru on the catalyst is 0.2wt.%, the same below): An appropriate amount of cobalt acetate and ruthenium chloride precursor solution of equal volume was impregnated onto the HAP support in Example 1. The resulting catalyst was freeze-dried (-45℃) for 6 hours, then dried in an oven at 120℃ for 2 hours, followed by calcination at 400℃ in air for 2 hours, and then further reduced at 400℃ in hydrogen atmosphere for 2 hours. After cooling, it was passivated with 1% O2 / N2 (volume fraction) for 6 hours. The resulting catalyst is denoted as 3Co0.2Ru / HAP. (The numerical values ​​preceding the metals in the following examples all represent the same meaning, i.e., mass fraction). From Figure 1 High-resolution electron microscopy (HREM) revealed that Co nanoparticles were uniformly dispersed on the HAP support surface. Aberration-corrected transmission electron microscopy (TEM) with atomic resolution showed that the promoter Ru was uniformly dispersed on the surface of the active metal Co nanoparticles, exhibiting a single-atom dispersion without aggregation. Elemental surface mapping (TEM) further confirmed that Co was uniformly dispersed on the support surface, and Ru was uniformly dispersed on the Co particle surface, forming surface "single-atom alloy" (Co and Ru atoms) catalytic active centers (at which point the Ru / Co molar ratio was 0.04). The average Co nanoparticle size was approximately 7.2 nm, ranging from 5 to 9 nm.

[0028] The difference between Examples 5-6 and Comparative Examples 1-2 and Example 2 in Table 1 lies in the amount of cobalt acetate precursor used in the equal-volume impregnation solution; the other catalyst preparation conditions are the same as in Example 2. High-resolution transmission electron microscopy confirmed that Co was uniformly dispersed on the prepared catalyst. The average Co particle size (particle size distribution range) in Examples 5 and 6 were 4.2 nm (3-6 nm) and 9.2 nm (7-12 nm), respectively. The average Co particle size in Comparative Examples 1-2 were 1.1 nm (0.5-1.6 nm) and 2.1 nm (1.2-2.9 nm), respectively. The conditions for the conversion of lignin phenols 4-propylguaiacol by the Co / HAP catalyst in Examples 5-6 and Comparative Examples 1-2 and Example 2 were the same. Taking Example 2 as an example: 0.05 g 3Co / HAP catalyst, 0.2 g 4-propylguaiacol, 10 g n-decane solvent, 0.2 g n-dodecane internal standard, reaction temperature 260 °C, hydrogen pressure 2 MPa, reaction time 4 h. After the reaction was complete, the liquid products were collected by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by chromatography. The liquid products included propylcyclohexanol and propylcyclohexane. As can be seen from Examples 2 and 6 and Comparative Examples 1-2, the conversion rate of 4-propylguaiacol continuously increased with increasing Co content, and when the Co content increased to 3 wt.%, the conversion rate exceeded 85% (preferred Co content range). Simultaneously, with increasing Co content, the selectivity of propylcyclohexane continuously increased, while the selectivity of propylcyclohexanol continuously decreased.

[0029] The preparation methods of the single-metal catalyst M / HAP in Examples 7-9 are similar to those in Example 3, except that the amount of ruthenium chloride as the auxiliary precursor is different. High-resolution transmission electron microscopy confirmed that Ru is uniformly dispersed on the catalyst surface, with average particle sizes of approximately 0.3, 0.6, and 1.1 nm, respectively. The reaction conditions for the conversion of lignin phenols 4-propylguaiacol by the Ru / HAP catalyst in Examples 7-9 are the same as those in Example 3. Taking Example 3 as an example: 0.05 g of 0.2 g Ru / HAP catalyst, 0.2 g of 4-propylguaiacol, 10 g of n-decane solvent, 0.2 g of n-dodecane internal standard, reaction temperature 260 °C, hydrogen pressure 2 MPa, and reaction time 4 h. Table 1 shows that with the continuous increase of the Ru content, the conversion rate of 4-propylguaiacol and the selectivity of propylcyclohexane continuously increase.

[0030] In Example 4, a 3Co0.2Ru / HAP catalyst was prepared using a co-impregnation method. High-resolution transmission electron microscopy and aberration-corrected transmission electron microscopy confirmed that Co particles were uniformly dispersed on the surface of the HAP support, while Ru was uniformly dispersed in single-atom form on the surface of the Co particles, forming a unique surface single-atom alloy catalyst. Figure 1 (As shown). Figure 2These are high-resolution electron microscopy (SEM) and line scan images of the CoRu alloy on the 3Co0.2Ru / HAP single-atom alloy catalyst. The images clearly show that Ru single atoms are completely dispersed on the surface of the Co nanoparticles rather than the HAP support, laying the foundation for the synergistic effect between Co and Ru, and also for the stable existence of Ru single atoms on the Co particle surface without migration to the support surface, thus improving catalyst stability. The catalyst preparation methods in Comparative Examples 3 and 4 are similar to those in Example 4, except that Comparative Examples 3 and 4 are prepared using a stepwise impregnation method. For example, in Comparative Example 3, 0.2Ru / HAP was first prepared by equal-volume impregnation, followed by freeze-drying (-45°C) for 6 hours, drying in an oven at 120°C for 2 hours, calcining at 400°C in air for 2 hours, and then further reduction at 400°C in hydrogen atmosphere for 2 hours. After cooling, it was passivated with 1% O2 / N2 (volume fraction) for 6 hours. The obtained catalyst was further impregnated with cobalt acetate precursor in equal volumes, then freeze-dried (-45℃) for 6 h, dried in an oven at 120℃ for 2 h, calcined at 400℃ in air for 2 h, and then reduced at 400℃ in hydrogen atmosphere for 2 h. After cooling, it was passivated with 1% O2 / N2 (volume fraction) for 6 h to finally obtain the 3Co / 0.2Ru / HAP catalyst. The difference between Comparative Example 4 and Comparative Example 3 is that the impregnation order of ruthenium chloride and cobalt acetate precursors is reversed, while the rest of the process is the same. High-resolution electron microscopy results confirmed that the metal active components were uniformly dispersed on the support surface. In Comparative Examples 3 and 4, Co and Ru did not completely form a single-atom alloy, and some Ru (30-45%) was dispersed on the support surface, with metal particle sizes of approximately 9.8 nm (particle size between 4-11.2 nm) and 10.3 nm (particle size between 6.5-13.4 nm), respectively. As can be seen from Table 1, in Example 4, the conversion of 4-propylguaiacol on the 3Co0.2Ru / HAP catalyst reached 100%, the selectivity of propylcyclohexane reached 100%, and the space-time yield of propylcyclohexane was as high as 315 g·g⁻¹. Ru -1 ·h -1 This is significantly higher than that of similar catalysts with the same composition, CoRuNx / NC (space-time yield of only 1.1 g·g⁻¹), reported in the literature. Ru -1 ·h -1 (260℃, Fuel 308(2022)121979-121989). In Comparative Examples 3 and 4, although the conversion rate of 4-propylguaiacol exceeded 89%, the selectivity of propylcyclohexanol was low. It should be noted that the bimetallic CoRu / HAP catalytic performance was significantly better than that of the monometallic catalyst, which means that there is a synergistic effect between Co and Ru.

[0031] Table 1. Conversion performance of lignin phenol 4-propylguaiacol catalyzed by NM / HAP

[0032]

[0033]

[0034] Note: 4-propylguaiacol was 0.2 g, n-decane was 10 g, n-dodecane was 0.2 g, catalyst was 0.05 g, reaction temperature was 260 °C, reaction pressure was 2 MPa, and reaction time was 4 h; Comparative Examples 3 and 4 were prepared by stepwise impregnation method.

[0035] As can be seen from Table 1, the conversion rate of 4-propylguaiacol is greater than 85% when the Co content exceeds 3 wt.%. Therefore, we further investigated the effect of different Ru contents on the catalytic hydrodeoxygenation performance of 4-propylguaiacol when the Co content is constant, as shown in Table 2.

[0036] Table 2. Effect of different Ru contents on the catalytic conversion performance of 4-propylguaiacol

[0037]

[0038] Note: 0.2g of 4-propylguaiacol, 10g of n-decane, 0.2g of n-dodecane (internal standard), 0.05g of catalyst, reaction temperature 260℃, reaction pressure 2MPa, reaction time 4h.

[0039] The catalyst preparation methods in Examples 10-12 of Table 2 are similar to those in Example 4, except for the different contents of the ruthenium chloride solution used as the auxiliary metal precursor. High-resolution electron microscopy (HEM) results confirmed that Co particles were uniformly dispersed on the HAP support surface in Examples 10-12, and aberration-corrected electron microscopy results confirmed that Ru metal was dispersed in single-atom form on the surface of Co nanoparticles rather than the support surface in Examples 10-12, forming an alloy phase with Co. The average particle size of the Co nanoparticles was approximately 7.2 nm, with particle sizes ranging from 5 to 9 nm. The reaction was carried out using Example 10 as an example: 0.05 g of 3Co0.05Ru / HAP single-atom alloy catalyst, 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of internal standard n-dodecane, reaction temperature 260 °C, hydrogen pressure 2 MPa, and reaction time 4 h. After the reaction was complete, the liquid products were separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. The main liquid products included propylcyclohexane and propylcyclohexanol. As can be seen from Examples 10-12 in Table 2, as the loading of the auxiliary agent Ru metal gradually increased from 0.05 wt.% to 0.5 wt.%, the conversion rate of 4-propylguaiacol gradually increased from 87.5% to 100%. Simultaneously, the selectivity of the fully deoxygenated product propylcyclohexane significantly improved, increasing from 32.6% to 100%. When the loading of the auxiliary agent Ru metal was within the range of 0.2-0.5 wt%, the conversion rate and selectivity of 4-propylguaiacol reached 100%. Example 2 shows that in the absence of the auxiliary agent Ru, the selectivity of the fully deoxygenated product propylcyclohexane was extremely low, indicating that the addition of the auxiliary agent Ru can significantly promote the breaking of the CO bond in propylcyclohexanol, thereby improving the selectivity of propylcyclohexane. To highlight the advantages of the Ru single-atom catalyst, a nanoparticle catalyst 3Co3Ru / HAP was further prepared by co-impregnation and used for performance evaluation of the catalytic hydrodeoxygenation of 4-propylguaiacol (Comparative Example 5). The catalyst preparation method is similar to that in Example 2, except that the cobalt acetate and ruthenium chloride precursor solutions are simultaneously impregnated on the support HAP, with the mass fractions of Co and Ru both being 3.0 wt.%, and the rest of the process is the same. Figure 3 This is an electron microscopy image of the 3Co3Ru / HAP catalyst. The image shows that the CoRu nanoparticles are approximately 22 nm in size, typical of nanoparticles, meaning that at higher concentrations, they tend to aggregate to form Ru particles. Simultaneously, due to the high Ru coverage on the Co particle surface, the interaction between the Co and substrates is weakened, resulting in a slight decrease in propylcyclohexane selectivity to 89.6%. Table 2 shows that increasing the Ru loading did not significantly improve the propylcyclohexane yield; in fact, when the Ru loading increased to 3 wt.%, the space-time yield of propylcyclohexane decreased to 22.7 g·g⁻¹. Ru -1 ·h -1The space-time yield of propylcyclohexane on the single-atom alloy catalyst 3Co0.2Ru / HAP reached as high as 315 g·g⁻¹. Ru -1 ·h -1 This means that the single-atom alloy catalyst 3Co0.2Ru / HAP exhibits optimal catalytic activity, which helps reduce the amount of precious metals used and decreases the catalyst preparation cost, highlighting the significant advantages of single-atom catalysts.

[0040] Table 3 Effect of different Ru / Co molar ratios on the conversion performance of 4-propylguaiacol

[0041]

[0042] Note: 0.2g of 4-propylguaiacol, 10g of n-decane, 0.2g of n-dodecane (internal standard), 0.05g of catalyst, reaction temperature 260℃, reaction pressure 2MPa, reaction time 4h.

[0043] As mentioned above, for bimetallic catalysts, within a certain range of promoter and active metal content, a suitable Ru / Co molar ratio can effectively promote the conversion of 4-propylguaiacol. Therefore, the effect of different Co / Ru molar ratios on the conversion of 4-propylguaiacol was further investigated when the Ru content was 0.2 wt%, as shown in Table 3. The catalyst preparation methods in Comparative Examples 6-9 and Examples 13-15 in Table 3 are similar to those in Example 4, except for the amount of cobalt acetate, the active metal Co precursor. Electron microscopy results confirmed that in the catalysts prepared in Examples 13-15, Co was uniformly dispersed in particulate form on the HAP support surface, and Ru single atoms were uniformly dispersed on the surface of Co nanoparticles rather than the support surface. The average sizes of the Co nanoparticles were approximately 4.2 nm (3-6 nm), 8.1 nm (6-11 nm), and 9.2 nm (7-12 nm), respectively, falling between 4-10 nm (the particle size distribution range is in parentheses). This suitable Co particle size provides an excellent substrate for Ru single atoms, which is beneficial for Ru to be dispersed in single-atom form on the surface of Co nanoparticles. In Comparative Examples 6 and 7, the Co content is low, and Co forms smaller clusters or particles with average particle sizes of 1.1 nm (particle size distribution range between 0.5-1.6 nm) and 2.1 nm (particle size distribution range between 1.2-2.9 nm), respectively. It is difficult to ensure that all Ru is uniformly dispersed in single-atom form on the surface of Co clusters and forms a single-atom alloy. Some Ru is dispersed on the surface of the HAP support, which is not conducive to the synergistic catalytic effect between Co and Ru. In Comparative Examples 8 and 9, the Co content is over 5 wt.%, and the average particle size of Co is approximately 15.5 nm (particle size distribution range 10-18 nm) and 17.9 nm (particle size distribution range 13-23 nm), respectively. Although the larger Co particles provide a sufficient substrate for Ru atom dispersion, some Ru atoms are covered by the larger Co particles, and Ru atoms may be dispersed at the edge of the Co nanoparticles, weakening the interaction between Ru and Co. Therefore, the selectivity of propylcyclohexane in Comparative Examples 8 and 9 decreases. Taking Example 13 as an example: 0.05g of single-atom alloy catalyst 2Co0.2Ru / HAP, 0.2g of 4-propylguaiacol, 10g of n-decane, 0.2g of internal standard n-dodecane, reaction temperature 260℃, hydrogen pressure 2MPa, reaction time 4h. After the reaction was completed, the liquid products were separated by centrifugation and qualitatively analyzed by mass spectrometry and quantitatively detected by gas chromatography. The liquid products mainly included propylcyclohexane and propylcyclohexanol, with a selectivity of 82.6% for propylcyclohexane.

[0044] In Comparative Example 6, the Ru / Co atomic ratio was 0.23. At this level, the extremely low levels of Co and Ru made it difficult to activate and dissociate hydrogen, resulting in low 4-propylguaiacol conversion and propylcyclohexane selectivity. Compared to Example 3, the bimetallic catalyst 0.5Co0.2Ru / HAP exhibited superior 4-propylguaiacol conversion and propylcyclohexane selectivity, highlighting the advantages of bimetallic catalysts. For Comparative Example 7, the Ru / Co atomic ratio was 0.12, achieving a 38.4% 4-propylguaiacol conversion and a 46.9% propylcyclohexane selectivity. As the Ru / Co atomic ratio further decreased (Example 13, Ru / Co = 0.06; Example 4, Ru / Co = 0.04; Example 14, Ru / Co = 0.03; Example 15, Ru / Co = 0.02), the conversion continuously increased, reaching 100% at Ru / Co = 0.04, while the propylcyclohexane selectivity also reached 100%. In Comparative Examples 8 and 9, the Ru / Co atomic ratios were 0.015 and 0.01, respectively. The table shows that when the Co content is high and the Ru / Co atomic ratio is less than 0.02, the process of hydrodeoxygenating the intermediate product 4-propylcyclohexanol to propylcyclohexane is inhibited. Combining Tables 2 and 3, within the selected range of auxiliaries and active metal contents, a catalyst with a suitable Ru / Co atomic ratio can provide Co nanoparticles of appropriate size as a substrate to disperse Ru single atoms and form a single-atom alloy. Through a suitable synergistic effect between Ru and Co, the process of hydrodeoxygenating 4-propylguaiacol to propylcyclohexane can be effectively promoted; that is, the Ru / Co atomic ratio should be between 0.02 and 0.2, preferably between 0.02 and 0.1.

[0045] Table 4 shows Examples 16-19, which investigated the effects of different types of single-atom promoters on the catalytic performance of 4-propylguaiacol hydrodeoxygenation. The catalyst preparation methods in Examples 16-19 were similar to those in Example 4, except for the different types of promoter metal precursors (chloroplatinic acid, palladium chloride, rhodium chloride, chloroauric acid). Electron microscopy results confirmed that Examples 16-19 were single-atom alloy catalysts, with an average Co nanoparticle size of approximately 7.2 nm, ranging from 5-9 nm. Promoters such as Pt, Pd, Rh, and Au were dispersed in single-atom form on the surface of the Co nanoparticles rather than the support surface, forming a surface single-atom alloy phase. For example, in Example 16: 0.05 g of the single-atom alloy catalyst 3Co0.2Pt / HAP, 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of internal standard n-dodecane, reaction temperature 260 °C, hydrogen pressure 2 MPa, and reaction time 4 h. After the reaction was complete, the liquid products were separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography, respectively. The table shows that the different noble metal promoters within the selected range all exhibited good catalytic activity, with 100% conversion of 4-propylguaiacol and a selectivity for propylcyclohexane greater than 93%. Among them, the 3Co0.2Ru / HAP single-atom alloy catalyst showed the best catalytic activity, indicating that Ru has the best hydrogenolysis performance and can significantly promote the hydrogenolysis of the intermediate propylcyclohexanol to prepare propylcyclohexane. Furthermore, compared with platinum group metals such as Pt, Pd, and Rh, Ru is cheaper, which helps reduce the cost of catalyst preparation. The catalyst preparation methods in Comparative Examples 10-14 are similar to those in Example 4, except for the selection of different additives. In Comparative Examples 12-14, the additives are bimetallic additives with a total mass fraction of 0.2 wt.% and a bimetallic molar ratio of 1:1. Electron microscopy results confirm that Comparative Examples 10-14 are single-atom alloy catalysts. The average particle size of Co nanoparticles is approximately 7.2 nm, with particle sizes ranging from 5 to 9 nm. The additives are dispersed on the surface of Co nanoparticles in a single-atom form, forming a single-atom alloy phase. As shown in Table 4, the Ir, Re, and bimetallic additive catalysts in Comparative Examples 10-14 all exhibit excellent catalytic performance, with propylcyclohexane selectivity reaching approximately 85%. This indicates that the single-atom alloy catalysts constructed using this method possess excellent hydrodeoxygenation performance and are universally applicable.

[0046] Table 4. 4-Propylguaiacol Conversion Performance Catalyzed by 3Co0.2N / HAP

[0047]

[0048] Note: 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of n-dodecane (internal standard), 0.05 g of catalyst, reaction temperature 260℃, reaction pressure 2 MPa, reaction time 4 h. (Note: The total content of additives in Comparative Examples 12-14 was 0.2 wt%, and the molar ratio of bimetallic additives was 1:1.)

[0049] Table 5 examines the effects of different types of active metals M (Fe, Co, Ni, and Cu, etc.) on the catalytic performance of 4-propylguaiacol hydrodeoxygenation at a constant Ru content. The catalyst preparation methods for Examples 20 and Comparative Examples 15-18 are similar to those for Example 4, except for the different types of active metals used. Electron microscopy results confirm that the active metals in the prepared catalysts exhibit a nanoparticle distribution. The average particle sizes of the active metals in Examples 20 and Comparative Examples 15-18 are approximately 6.2 nm (particle size distribution range 3-9 nm), 7.9 nm (particle size distribution range 4-10 nm), 8.6 nm (particle size distribution range 7-11 nm), 7.8 nm (particle size distribution range 6-10 nm), and 9.4 nm (particle size distribution range 7-12 nm), respectively. The promoter Ru is dispersed in single-atom form on the surface of the active metal particles rather than on the support surface. Taking Example 20 as an example: 0.05g of single-atom alloy catalyst 3Ni0.2Ru / HAP, 0.2g of 4-propylguaiacol, 10g of n-decane, 0.2g of internal standard n-dodecane, reaction temperature 260℃, hydrogen pressure 2MPa, reaction time 4h. After the reaction was completed, the liquid products were separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. As shown in Table 5, the single-atom alloy catalysts formed by the active metals Ni and Co with the auxiliary agent Ru both exhibited excellent performance in the catalytic hydrodeoxygenation of 4-propylguaiacol, with a conversion rate of over 86% and a propylcyclohexane selectivity of over 82%. Among them, when Co was used as the active metal, it showed the best hydrodeoxygenation performance, with both substrate conversion and propylcyclohexane selectivity reaching 100%. This is mainly because Co has a strong affinity for oxygen, which is beneficial to promoting the breaking of CO bonds in the substrate. In contrast, the synergistic effect between the active metal and Ru in Comparative Examples 15-18 was weak, which was not conducive to the conversion of the substrate and the deoxygenation of the intermediate product propylcyclohexanol.

[0050] Table 5. 4-Propylguaiacol Conversion Performance Catalyzed by 3M0.2Ru / HAP

[0051]

[0052] Note: 0.2g of 4-propylguaiacol, 10g of n-decane, 0.2g of n-dodecane (internal standard), 0.05g of catalyst, reaction temperature 260℃, reaction pressure 2MPa, reaction time 4h.

[0053] Table 6 shows Comparative Examples 19-28, which investigated the effect of the support on the conversion of 4-propylguaiacol. The preparation methods were similar to those in Example 4, except for the choice of support. Electron microscopy results confirmed that the average particle size of the Co nanoparticles in the prepared catalysts ranged from 4.5 to 25 nm. Taking Comparative Example 19 as an example: 0.05 g of 3Co0.2Ru / Al2O3 catalyst, 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of internal standard n-dodecane, reaction temperature 260 °C, hydrogen pressure 2 MPa, and reaction time 4 h. After the reaction was complete, the liquid products were separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. Table 6 shows that the support has a significant effect on the conversion of the lignin phenolic derivative 4-propylguaiacol. Both acidic and basic supports can promote the conversion of 4-propylguaiacol and obtain the target product propylcyclohexane. When HAP was used as the support, both the substrate conversion and propylcyclohexane selectivity reached 100%. However, when using low specific surface area oxides such as La₂O₃, MoO₃, and CeO₂ as supports, the conversion was lower. This is likely because low specific surface area supports are not conducive to the dispersion of Co nanoparticles, leading to severe aggregation of Co nanoparticles. Electron microscopy results confirmed that the average size of Co nanoparticles on these low specific surface area supports was between 15-25 nm. The HAP support has abundant specific surface area and defect sites, which is beneficial for dispersing and anchoring active metals to form Co nanoparticles of suitable size. It also facilitates the construction of single-atom alloy catalysts with the promoter Ru, achieving 100% Ru atom utilization.

[0054] Table 6. Effect of the support on the hydrodeoxygenation performance of 4-propylguaiacol

[0055]

[0056] Note: 0.2g of 4-propylguaiacol, 10g of n-decane, 0.2g of n-dodecane (internal standard), 0.05g of catalyst, reaction temperature 260℃, reaction pressure 2MPa, reaction time 4h.

[0057] The single-atom alloy catalyst 3Co0.2Ru / HAP prepared in this invention achieved excellent results in the conversion of lignin phenolic derivative 4-propylguaiacol. Therefore, the conversion performance of this catalyst in other lignin phenolic derivatives was further investigated, as shown in Table 7, Examples 21-26. The catalysts used in Examples 21-26 were all the 3Co0.2Ru / HAP single-atom alloy catalyst prepared in Example 4 (electron microscopy confirmed that the average particle size of Co nanoparticles was approximately 7.2 nm, with a particle size ranging from 5-9 nm, and Ru was dispersed in single-atom form on the surface of the Co particles). Taking Example 21 as an example: 0.2 g 4-methylguaiacol, 10 g n-decane, 0.2 g internal standard n-dodecane, 0.05 g single-atom 3Co0.2Ru / HAP catalyst, reaction temperature 260℃, reaction pressure 2 MPa, reaction time 4 h. After the reaction was completed and cooled to room temperature, the liquid products were separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. As can be seen from Examples 21-26 in Table 7, the single-atom alloy catalyst 3Co0.2Ru / HAP can achieve efficient hydrodeoxygenation of lignin phenolic derivatives to prepare cycloalkane liquid fuels, with a cycloalkane product selectivity of 100%. Examples 27-29 are hydrodeoxygenation conversion tests of native lignocellulosic biomass. For pine, miscanthus, and corn cob, the cycloalkane selectivity is above 24% (the lignin content in native lignocellulosic is 15-35 wt%), demonstrating excellent hydrodeoxygenation performance. This lays the foundation for the direct one-step catalytic preparation of cycloalkane liquid fuels from native biomass and has a wide range of applications.

[0058] Table 7. Catalytic conversion performance of different lignin phenolic derivatives and native lignocellulose biomass

[0059] Example Substrate Conversion rate (%) Cycloalkanes selectivity (%) Example 4 4-Propylguaiacol 100 100 (propylcyclohexane) Example 21 4-Methylguaiacol 100 100 (methylcyclohexane) Example 22 4-Ethylguaiacol 100 100 (Ethylcyclohexane) Example 23 Guaiacol 100 100 (cyclohexane) Example 24 phenol 100 100 (cyclohexane) Example 25 Eugenol 100 100 (propylcyclohexane) Example 26 p-Cresol 100 100 (methylcyclohexane) Example 27 pine wood 56.8 33.1 Example 28 Miscanthus 63.5 25.5 Example 29 corn cob 49.8 24.1

[0060] Note: In Examples 21-26, the substrate mass was 0.2 g, n-decane 10 g, internal standard n-dodecane 0.2 g, 0.05 g 3Co0.2Ru / HAP, the reaction temperature was 260℃, the reaction pressure was 2 MPa, and the reaction time was 4 h. In Examples 27-29, the substrate mass was 0.1 g, the catalyst 3Co0.2Ru / HAP mass was 0.1 g, the reaction pressure was 4 MPa, and the other conditions were the same as in Examples 21-26. The main cycloalkanes in Examples 27-29 were: cyclohexane, methylcyclohexane, ethylcyclohexane, and propylcyclohexane.

[0061] Table 8 shows Examples 30-33 and Comparative Examples 29-30, using the single-atom alloy catalyst 3Co0.2Ru / HAP prepared in Example 4 as the research object (electron microscopy confirmed that the average particle size of Co nanoparticles was approximately 7.2 nm, with a particle size ranging from 5 to 9 nm, and Ru was dispersed in single-atom form on the surface of the Co particles), to investigate the effect of different reaction temperatures on the hydrodeoxygenation performance of 4-propylguaiacol. Taking Example 30 as an example: 0.2 g 4-propylguaiacol, 10 g n-decane, 0.2 g internal standard n-dodecane, 0.05 g single-atom alloy catalyst 3Co0.2Ru / HAP, reaction temperature 200℃, reaction pressure 2 MPa, reaction time 4 h. After the reaction was completed and cooled to room temperature, the liquid products were separated by centrifugation, and qualitative analysis was performed by mass spectrometry and quantitative analysis by gas chromatography. Table 8 shows that the reaction temperature has a significant effect on the hydrodeoxygenation performance of 4-propylguaiacol. When the reaction temperature is below 200℃, the conversion and propylcyclohexane selectivity are low, mainly due to the high energy barrier for CO bond dissociation in the substrate (C0). sp2 -OH,C sp2 -OCH3,C sp3 The dissociation energies of -OAr are 466 kJ / mol, 409 kJ / mol, and 262 kJ / mol, respectively (where Ar represents the benzene ring). Steric hindrance exists between the methoxy and phenolic hydroxyl groups, making conversion difficult. With further increases in reaction temperature, the conversion rate of 4-propylguaiacol and the selectivity for propylcyclohexane continuously increase. When the reaction temperature reaches 240℃, 4-propylguaiacol is completely converted, and the selectivity for propylcyclohexane reaches 85.6%. Further increasing the temperature to 260℃, the selectivity for propylcyclohexane reaches 100%. Therefore, within a suitable temperature range (240-280℃), highly selective propylcyclohexane can be obtained.

[0062] Table 8. Effect of reaction temperature on the conversion performance of 4-propylguaiacol

[0063]

[0064]

[0065] Note: 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of n-dodecane (internal standard), 0.05 g of 3Co0.2Ru / HAP single-atom alloy catalyst, reaction pressure 2 MPa, reaction time 4 h. Other products are mainly propylphenol.

[0066] Hydrogen pressure is also an important parameter affecting reaction performance. Table 9 shows the comparison of the catalytic performance of the single-atom alloy catalyst 3Co0.2Ru / HAP (prepared in Example 4, electron microscopy confirmed that the average particle size of Co nanoparticles is about 7.2 nm, with a particle size between 5-9 nm, and Ru is dispersed in single-atom form on the surface of Co particles) for the hydrodeoxygenation of 4-propylguaiacol under different hydrogen pressures in Examples 34-35 and Comparative Examples 31-32. For example, Example 34 used 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of internal standard n-dodecane, 0.05 g of single-atom alloy catalyst 3Co0.2Ru / HAP, a reaction temperature of 260 °C, a reaction time of 4 h, and a hydrogen pressure of 1 MPa. After the reaction was completed and cooled to room temperature, the liquid product was separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. Table 9 shows that at a hydrogen pressure of 0.1 MPa, the conversion rate of 4-propylguaiacol is only 5.6%, and the selectivity for propylcyclohexane is 1.2%. When the hydrogen pressure increases to 1 MPa, the substrate conversion rate and propylcyclohexane selectivity increase rapidly, but still do not exceed 80%. When the hydrogen pressure reaches 2 MPa, the substrate conversion rate and propylcyclohexane selectivity reach 100%, which means that hydrogen pressure plays an important role in the hydrodeoxygenation process; high-pressure hydrogen is beneficial to promoting substrate conversion and deoxygenation. Within the selected hydrogen pressure range of 2-5 MPa, the conversion rate of 4-propylcyclohexane and the selectivity for propylcyclohexane reach as high as 100%.

[0067] Table 9. Effect of reaction hydrogen pressure on the conversion performance of 4-propylguaiacol

[0068]

[0069] Note: 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of n-dodecane (internal standard), 0.05 g of 3Co0.2Ru / HAP single-atom alloy catalyst, reaction temperature 260℃, reaction time 4 h. Other products are mainly propylphenol and propylbenzene.

[0070] Table 10 shows the comparison of the catalytic performance of the single-atom alloy catalyst 3Co0.2Ru / HAP (prepared in Example 4, with an average Co nanoparticle size of approximately 7.2 nm under electron microscopy, ranging from 5 to 9 nm, and Ru dispersed in single-atom form on the surface of the Co particles) on the hydrodeoxygenation of 4-propylguaiacol in Examples 36-40, with different reaction times. Example 36 is as follows: 0.2 g 4-propylguaiacol, 10 g n-decane, 0.2 g internal standard n-dodecane, 0.05 g single-atom alloy catalyst 3Co0.2Ru / HAP, reaction temperature 260 °C, reaction time 0.5 h, hydrogen pressure 2 MPa. After the reaction was completed and cooled to room temperature, the liquid product was separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. Table 10 shows that when the reaction time is less than 4 hours, although the conversion rate of 4-propylguaiacol exceeds 85%, the selectivity for the completely deoxygenated product propylcyclohexane is low. This means that when the reaction time is short, the main reaction pathway is the demethoxylation of 4-propylguaiacol and the hydrogenation of the aromatic ring to propylcyclohexanol. As the reaction time increases, the intermediate product completely undergoes complete hydrogenation and deoxygenation to propylcyclohexane, and the selectivity for the target product reaches 100% at 4 hours.

[0071] Table 10. Effect of reaction time on the conversion performance of 4-propylguaiacol

[0072]

[0073] Note: 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of n-dodecane (internal standard), 0.05 g of 3Co0.2Ru / HAP catalyst, hydrogen pressure 2 MPa, reaction temperature 260℃. Other products are mainly propylphenol and propylbenzene.

[0074] Table 11 shows the conversion performance of the 3Co0.2Ru / HAP single-atom alloy catalyst prepared in Example 4 (electron microscopy confirmed that the average particle size of Co nanoparticles was approximately 7.2 nm, with particle sizes ranging from 5 to 9 nm, and Ru was dispersed in single-atom form on the surface of Co particles) at different concentrations of 4-propylguaiacol in Examples 41-44. For example, Example 44 contained 10 wt.% 4-propylguaiacol, 10 g of n-decane, 0.2 g of internal standard n-dodecane, 0.05 g of the single-atom alloy catalyst 3Co0.2Ru / HAP, a reaction temperature of 260 °C, a reaction pressure of 2 MPa, and a reaction time of 4 h. After the reaction was completed and cooled to room temperature, the liquid product was separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. As shown in Table 11, the 3Co0.2Ru / HAP single-atom alloy catalyst still exhibits excellent performance within the selected concentration range of 4-propylguaiacol (1-10 wt.%). Within the preferred concentration range (1-5 wt.%), both substrate conversion and propylcyclohexane selectivity reach 100%. Although the propylcyclohexane selectivity begins to decrease at a substrate concentration of 8 wt.%, it remains above 82%, indicating that the 3Co0.2Ru / HAP single-atom alloy catalyst can still achieve efficient hydrodeoxygenation of 4-propylguaiacol to cycloalkanes under high-concentration reaction conditions, demonstrating excellent application prospects.

[0075] Table 11. Effect of 4-propylguaiacol concentration on catalytic performance

[0076]

[0077]

[0078] Note: The reaction mixture consisted of 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of n-dodecane (internal standard), 0.05 g of 3Co0.2Ru / HAP catalyst, a reaction temperature of 260℃, a reaction pressure of 2 MPa, and a reaction time of 4 h. Other products were mainly propylphenol and propylbenzene.

[0079] Table 12 shows Examples 45-47, which investigated the effect of different calcination temperatures on the catalytic production of propylcyclohexane from 4-propylguaiacol by the single-atom alloy catalyst 3Co0.2Ru / HAP (calcined followed by hydrogen reduction at 400℃ for 2 h). Electron microscopy results showed that the average particle sizes of Examples 45-47 were 6.2 nm (particle size distribution range between 4.6-8.5 nm, the same below), 6.8 nm (5.2-8.9 nm), and 8.9 nm (7.5-10.3 nm), respectively. Taking Example 45 as an example, the reaction consisted of 0.05 g of the single-atom alloy catalyst 3Co0.2Ru / HAP calcined at 200℃ and then reduced at 400℃, 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of internal standard n-dodecane, a reaction temperature of 260℃, a hydrogen pressure of 2 MPa, and a reaction time of 4 h. After the reaction was complete, the liquid products were separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. The liquid products include propylcyclohexane and propylcyclohexanol. As can be seen from Examples 45-47 and Example 4 in the table, as the calcination temperature of the support gradually increases, the substrate conversion and propylcyclohexane selectivity gradually increase. This means that appropriately increasing the calcination temperature is beneficial for constructing the interface between the single-atom promoter Ru and the active metal Co. Within a suitable calcination temperature range, the propylcyclohexane selectivity is greater than 71%, especially within the preferred calcination range (300-400℃), where the substrate conversion reaches 100% and the propylcyclohexane selectivity is greater than 96%. However, when the calcination temperature reaches 500℃, the excessively high temperature is not conducive to the dispersion of Ru single atoms on the surface of Co nanoparticles, leading to Ru aggregation and the formation of Co and Ru nanoparticles, which in turn results in a decrease in catalytic activity.

[0080] Table 12. Effect of catalyst calcination temperature on the conversion performance of 4-propylguaiacol

[0081]

[0082] Note: 4-propylguaiacol mass 0.2g, n-decane 10g, internal standard n-dodecane 0.2g, 0.05g 3Co0.2Ru / HAP catalyst, reaction temperature 260℃, reaction pressure 2MPa, reaction time 4h.

[0083] Table 13. Effect of calcination time on the conversion performance of 4-propylguaiacol at a calcination temperature of 400℃

[0084]

[0085]

[0086] Note: The reaction mixture consisted of 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of n-dodecane (internal standard), 0.05 g of 3Co0.2Ru / HAP catalyst, a reaction temperature of 260℃, a reaction pressure of 2 MPa, and a reaction time of 4 h. Other products were mainly propylphenol and propylbenzene.

[0087] Table 13 shows the effects of different calcination times at 400℃ on the preparation of propylcyclohexane from 4-propylguaiacol catalyzed by 3Co0.2Ru / HAP in Examples 48-50 and Comparative Examples 33-35. Electron microscopy results showed that the average particle sizes of Examples 48-50 were 5.6 nm (particle size distribution range between 4.5-7.5 nm, the same below), 5.8 nm (4.2-8.1 nm), and 8.7 nm (7.7-10.5 nm), respectively. The average particle sizes of Comparative Examples 33-35 were 4.6 nm (3-6.5 nm), 12.5 nm (9.5-15.6 nm), and 16.9 nm (10.5-20.6 nm). Taking Comparative Example 33 as an example, 0.05 g of the single-atom alloy catalyst 3Co0.2Ru / HAP, calcined at 400℃ for 0.5 h and then reduced at 400℃, 0.2 g of 4-propylguaiacol, 10 g of n-decane, and 0.2 g of internal standard n-dodecane were used. The reaction temperature was 260℃, the hydrogen pressure was 2 MPa, and the reaction time was 4 h. After the reaction was completed, the liquid products were separated by centrifugation and qualitative analysis was performed by mass spectrometry and quantitative analysis by gas chromatography. As can be seen from Examples 48-50 and Comparative Examples 33-35 in the table, as the calcination time of the support gradually increases, the substrate conversion and propylcyclohexane selectivity gradually increase. This means that appropriately increasing the calcination time is beneficial to constructing the interface between the single-atom auxiliary agent Ru and the active metal Co. Within the suitable calcination time range (1-4 h), the propylcyclohexane selectivity is greater than 75%. Especially within the preferred calcination time (2-3 h), the substrate conversion reaches 100% and the propylcyclohexane selectivity reaches 100%. However, when the calcination time reached 6 hours, the excessively long calcination was detrimental to the dispersion of Ru single atoms on the surface of Co nanoparticles, leading to Ru aggregation and the formation of CoRu nanoparticles. This, in turn, resulted in a decrease in catalytic activity, causing the conversion rates to drop to 65.3% and 32.9% after calcination for 6 hours and 8 hours, respectively. Simultaneously, the selectivity for propylcyclohexane decreased. Furthermore, prolonged calcination may cause partial volatilization of RuO2, which is also detrimental to the catalytic reaction.

[0088] The reduction temperature of the catalyst is also one of the important factors affecting the catalyst performance. Table 14 shows the effect of different reduction temperatures on the conversion performance of 4-propylguaiacol catalyzed by 3Co0.2Ru / HAP (reduction after calcination at 400℃ for 2 h). Electron microscopy results showed that the average particle sizes of Examples 51-53 were 5.5 nm (particle size distribution range between 4.4-7.4 nm, the same below), 6.8 nm (4.1-9.1 nm), and 9.7 nm (7.7-13.5 nm), respectively. Taking Example 51 as an example: 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of internal standard n-dodecane, and 0.05 g of 3Co0.2Ru / HAP catalyst calcined at 400℃ for 2 h were used. The catalyst was then reduced at 200℃ for 2 h, the reaction temperature was 260℃, the reaction pressure was 2 MPa, and the reaction time was 4 h. After the reaction was completed and cooled to room temperature, the liquid products were separated by centrifugation and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. As shown in Table 14, within the reduction temperature range of 200-500℃, the selectivity of propylcyclohexane is greater than 60%. With increasing reduction temperature, the conversion of 4-propylguaiacol and the selectivity of propylcyclohexane continuously increase, reaching 100% at 400℃. Further increasing the reduction temperature to 500℃, the conversion decreases to 89.6% and the selectivity of propylcyclohexane decreases to 84.6%. In Comparative Example 35, when the reduction temperature is further increased to 600℃, the substrate conversion and the selectivity of propylcyclohexane decrease to 67.3% and 71.5%, respectively. This is mainly because the excessively high reduction temperature leads to the formation of Co and Ru nanoparticles. When the reduction temperature is below 200℃, Co exists in an oxidized state, mainly as Co3O4 and CoO, making it difficult to form an alloy with Ru metal, thus hindering the single-atom dispersion of Ru atoms on the surface of Co nanoparticles. Within the preferred reduction temperature range (300-400℃), the substrate conversion is greater than 95%, and the selectivity of propylcyclohexane is greater than 93%. The target product, propylcyclohexane, achieved the highest selectivity of 100% after reduction at 400℃. At this point, a single-atom alloy is formed between Co particles and Ru atoms. The synergistic effect between Co and Ru is beneficial to promoting the efficient conversion of 4-propylguaiacol to propylcyclohexane.

[0089] Table 14. Effect of catalyst reduction temperature on the conversion performance of 4-propylguaiacol

[0090]

[0091] Note: 4-propylguaiacol mass 0.2g, n-decane 10g, internal standard n-dodecane 0.2g, 0.05g 3Co0.2Ru / HAP catalyst, reaction temperature 260℃, reaction pressure 2MPa, reaction time 4h.

[0092] Table 15. Effect of reduction time on the conversion performance of 4-propylguaiacol at a reduction temperature of 400℃

[0093]

[0094] Note: The reaction mixture consisted of 0.2 g of 4-propylguaiacol, 10 g of n-decane, 0.2 g of n-dodecane (internal standard), 0.05 g of 3Co0.2Ru / HAP catalyst, a reaction temperature of 260℃, a reaction pressure of 2 MPa, and a reaction time of 4 h. Other products were mainly propylphenol and propylbenzene.

[0095] Table 15 shows the effects of different reduction times at a reduction temperature of 400℃ on the preparation of propylcyclohexane from 4-propylguaiacol catalyzed by 3Co0.2Ru / HAP (hydrogen reduction after calcination at 400℃). Electron microscopy results showed that the average particle sizes in Examples 54-55 were 5.7 nm (particle size distribution range between 3.5-8.5 nm, the same below) and 9.8 nm (7.2-14.1 nm), respectively. The average particle sizes in Comparative Examples 38-39 were 4.9 nm (3.1-6.8 nm) and 13.9 nm (9.5-17.5 nm), respectively. Taking Comparative Example 38 as an example, 0.05 g of catalyst 3Co0.2Ru / HAP after reduction at 400℃ for 0.5 h, 0.2 g of 4-propylguaiacol, 10 g of n-decane, and 0.2 g of internal standard n-dodecane were used. The reaction temperature was 260℃, the hydrogen pressure was 2 MPa, and the reaction time was 4 h. After the reaction was completed, the liquid products were separated by centrifugation and qualitatively analyzed by mass spectrometry and quantitatively analyzed by gas chromatography. The liquid products included propylcyclohexane and propylcyclohexanol. As can be seen from Examples 54-55 and Comparative Examples 38-39 in the table, when the reduction temperature is less than 1 h, the conversion rate of 4-propylguaiacol is only 48.9%. At this time, Co and Ru mainly exist in the oxidized state, making it difficult for hydrogen to promote the reaction. When the reduction time is in the range of 1-4 h, the substrate conversion rate is greater than 91%, and the selectivity of propylcyclohexane is greater than 85%. In particular, the preferred reduction time is in the range of 1-2 h, where the substrate conversion rate exceeds 95%. For Comparative Example 39, when the reduction time was 6 h, the conversion rate was 84.6% and the propylcyclohexane selectivity was only 65.3%, which means that excessively long reduction time may cause Ru to aggregate on the surface of Co particles, thereby leading to a decrease in catalytic activity.

[0096] Example 56 is a stability test of the 3Co0.2Ru / HAP single-atom alloy catalyst prepared in Example 4 catalyzing the hydrodeoxygenation of 4-propylguaiacol. The specific operation steps are as follows: 0.2g 4-propylguaiacol, 10g n-decane, 0.2g n-dodecane (internal standard), 0.05g 3Co0.2Ru / HAP single-atom alloy catalyst, reaction temperature 260℃, reaction pressure 2MPa, reaction time 4h. After each reaction, the catalyst was centrifuged, washed three times with ethanol, and freeze-dried (-45℃) for 6h. Then, it was added to the reactor along with 0.2g 4-propylguaiacol, 10g n-decane, and 0.2g n-dodecane (internal standard). Hydrogen gas was introduced at 2MPa, and the temperature was raised to 260℃ for the next cycle reaction. The liquid products after each reaction were centrifuged and analyzed qualitatively by mass spectrometry and quantitatively by gas chromatography. The reaction results are shown in [Figure 56]. Figure 4 As can be seen from the figure, the substrate conversion and propylcyclohexane selectivity of the 3Co0.2Ru / HAP single-atom alloy catalyst prepared in this invention remained essentially unchanged after 10 cycles, maintaining at 100%, indicating that the single-atom alloy catalyst has excellent stability and good prospects for industrial application.

Claims

1. A method for producing cycloalkanes liquid fuel by hydrogenation and deoxygenation of lignin phenolic derivatives, characterized in that: The catalyst used is abbreviated as MN / S, where N is the promoter, M is the active metal, S is the catalyst support hydroxyapatite (HAP), and M is supported on the support. The additive N is dispersed on the surface of the active metal M particles in a single-atom dispersion state. The additive N is one or more of the noble metals Pt, Pd, Rh, Ru, and Au, and the additive content is 0.1-0.5 wt% of the total mass of the catalyst M, N, and support S. M is a non-noble metal Co or Ni, and the active metal M content is 3-5 wt% of the total mass of the catalyst M, N, and support S. The nanoparticles formed by the active metal M have an average particle size of 4-10 nm and a particle size distribution range of 3-12 nm. The lignin phenolic derivative is one or more of 4-methylguaiacol, 4-ethylguaiacol, 4-propylguaiacol, phenol, and p-cresol. The required catalyst preparation method is a co-impregnation method, in which a precursor solution containing active component M and promoter N is impregnated onto a support HAP, and the resulting catalyst is prepared at -45~-50°C. o After freeze-drying at C for 3-6 hours, the temperature is increased to 200-500°C in air. o Calcination at C for 1-4 hours; then the obtained catalyst is calcined at 200-500 °C under a hydrogen atmosphere. o C reduction takes 1-4 hours.

2. The method according to claim 1, characterized in that: Additive N forms a single-atom alloy with active metal M. Additive N is dispersed in single-atom form on the surface of M particles to form a surface alloy. Active metal M is dispersed on the surface of carrier S. Ensure that the additive N is uniformly dispersed in single-atom form on the active metal M nanoparticles and forms an alloy phase with M; within the selected range of additive and active metal content, the N / M atomic ratio is between 0.02 and 0.

04.

3. The method according to claim 1, characterized in that: The selected precursor M is one of the acetate or nitrate of the active metal M; the selected precursor N is one or more of the chloride or nitrate of the auxiliary agent N.

4. The method according to claim 1, characterized in that: The reaction was carried out in a batch high-pressure autoclave reactor under the following operating conditions: lignin phenolic derivative concentration 1-10 wt.%; reaction temperature 200-280°C. o C; hydrogen pressure 0.1-5 MPa; reaction time 0.5-6 h; C8-C10 straight-chain alkanes as solvent.

5. The method according to claim 4, characterized in that: The reaction was carried out in a batch high-pressure autoclave reactor under the following operating conditions: lignin phenolic derivative concentration 1-5 wt.%; reaction temperature 240°C. o C-280 o C; hydrogen pressure 2-5 MPa; reaction time 4-6 h; n-decane as solvent.

6. The method according to claim 1, characterized in that: The cycloalkane liquid fuel is one or more of methylcyclohexane, ethylcyclohexane, propylcyclohexane, or cyclohexane.

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