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Article

Carbon-Coated Cobalt-Catalyzed Hydrodeoxygenation of Lipids to Alcohols

by
Long Chen
1,
Jing Wu
2,
Ai Chang
1,
Guo-Ping Lu
1,* and
Chun Cai
1,*
1
School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
2
China Coal Technology and Engineering Group Huaibei Blasting Technology Research Institute Limited Company, Huaibei 235000, China
*
Authors to whom correspondence should be addressed.
Catalysts 2025, 15(3), 254; https://doi.org/10.3390/catal15030254
Submission received: 12 February 2025 / Revised: 2 March 2025 / Accepted: 5 March 2025 / Published: 6 March 2025
(This article belongs to the Special Issue Topical Advisory Panel Members' Collection Series: Biomass Catalytic Conversion)
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Abstract

:
The abundant metal-catalyzed selective hydrodeoxygenation of lipids to alcohols has great industrial application potential. Herein, a carbon-coated Co catalyst has been fabricated by a simple detonation-reduction method. This material exhibits outstanding performance for the selective hydrodeoxygenation of lipids to alcohols (200 °C, 5 h, 2 MPa H2, over 5 runs), which mainly benefits from the carbon layer on the Co surface. This carbon layer optimizes substrate adsorption, which enhances the H2 adsorption process. The carbon coating also inhibits the oxidation of Co particles, resulting in the co-existence of Co0 and CoO, which is beneficial for H2 activation. In addition, kinetic studies indicate that hydrogen activation should be included in the rate-determining step of this reaction.

1. Introduction

The development of renewable energy technologies has gained significant attention from researchers and policymakers due to the growing global energy and environmental crises. As conventional fossil fuels continue to pose significant challenges related to greenhouse gas emissions, air pollution, and resource depletion, alternative sources of energy are increasingly being explored. Among these, renewable energy has emerged as a promising solution to mitigate the negative environmental impacts while ensuring sustainable energy supply [1,2,3]. In this context, biomass-based energy has drawn considerable interest as a crucial component of renewable energy systems due to its carbon neutrality and the potential for effective carbon management [4,5,6,7]. Specifically, the efficient conversion of biomass into useful fuels and chemicals is considered one of the most viable pathways to ensure the sustainable utilization of renewable energy.
One of the key components of biomass, lipids, plays a crucial role in energy storage and metabolism in both animals and plants. Lipids are organic molecules that primarily function as energy reserves, serving as an efficient medium for energy storage and release in biological systems [8,9,10]. In 2021, global lipid production reached an astounding 600 million tons, further highlighting their widespread availability and importance in energy metabolism. Lipids are attractive feedstocks for renewable energy conversion due to their low cost, abundant availability, simple molecular structures, and low oxygen content, making them well-suited for selective conversion into high-value fuels and chemicals through relatively straightforward chemical processes [11,12,13]. Anna’s group developed a polymer-supported Pd and Ni nanoparticles catalyzed partially via hydrogenation of the fatty acid methyl ester mixture to produce the mono-unsaturated product known as Biodiesel [14].
Among the various chemical processes, the selective conversion of lipids into long-chain fatty alcohols through hydrodeoxygenation (HDO) is particularly noteworthy. Fatty alcohols, which can be synthesized through HDO, have broad industrial applications in the production of plasticizers, surfactants, food additives, cosmetics, and pharmaceuticals [15,16,17]. This process is of increasing interest due to the continuous global rise in the consumption of long-chain fatty alcohols, which reached approximately 5 million tons in 2019 [18]. Given the substantial industrial demand for these alcohols, there is significant potential for the efficient and selective HDO of lipids to meet the growing market needs [19,20].
Over the past few years, researchers have developed a wide range of efficient heterogeneous metal-catalyzed HDO processes for converting lipids to fatty alcohols [21,22,23]. For example, Wu’s group developed a novel catalyst consisting of N-doped carbon nanotubes confined Co, which demonstrated a remarkable 97.4% yield in the hydrogenation of palmitic acid to palmityl alcohol at 220 °C [22]. Metals, especially those that are abundant, low-cost, and non-toxic, are often preferred for catalytic reactions due to their favorable properties, making them a focal point for research in this area [24,25,26]. In general, these catalysts require the combination of both metal sites for hydrogen activation and Lewis acid sites for the adsorption of oxygen-containing species from the lipids [27,28].
In this context, Cai and coworkers have introduced a highly efficient NiMo bimetallic catalyst for the HDO of lipids to alcohols [28]. In this system, H2 is primarily activated by the Ni sites, while the lipid molecules are adsorbed onto the Lewis acid sites (Mo), thus facilitating conversion. Similarly, cobalt-based catalysts have garnered considerable attention due to their unique combination of Lewis acidity and exceptional hydrogen activation properties, making them highly suitable for a variety of HDO reactions [29,30,31,32]. Wu’s group, for example, has designed a Co@SiO2 nanorattle catalyst that not only inhibits the hydrocracking of long-chain hydrocarbons but also promotes the HDO pathway, achieving high carbon atom economy in the process [31]. Reduced cobalt nanoparticles (Co-350) have also shown excellent catalytic performance in the transfer hydrogenation of oleic acid to octadecanol, where the co-existence of Coδ+ and Co0 species is thought to contribute to high catalytic activity [32].
In recent years, improving the stability of catalytic sites and enhancing the selectivity of alcohols has been an ongoing challenge. To address this, our group has employed a novel detonation method to coat NiMoOx catalysts with a carbon layer, which has been shown to enhance the catalytic performance and stability of the catalyst [33]. In a similar vein, Wang’s group introduced a unique core–shell structure for cobalt catalysts, where the CoO shell was modified with oxygen vacancies (Ov). This design greatly improved the catalytic performance for the HDO of 5-hydroxymethylfurfural by promoting both the activation of hydrogen and the adsorption of the substrate [34]. The oxygen vacancies in the CoO shell played a crucial role in activating H2 and enhancing the adsorption capacity for the substrate, further optimizing the reaction process.
Building on these advances, we envisioned the development of a novel carbon-coated cobalt (Co) catalyst. In this proposed catalyst, a CoO layer with oxygen vacancies (Ov) would be present on the surface of cobalt particles, thereby enhancing the HDO reaction. This design not only facilitates hydrogen activation but also improves the adsorption of lipids by adjusting the adsorption energy of the substrates. The carbon layer would further stabilize the CoO layer, ensuring that the catalyst remains highly active and selective over extended reaction periods. Herein, we present a newly developed carbon-coated Co catalyst for the HDO of lipids, which demonstrates superior catalytic performance primarily due to the synergistic effects of the carbon coating and the oxidation state of Co.

2. Results and Discussion

A simple detonation strategy was applied for the synthesis of carbon-coated Co catalysts (Figure 1) [33]. Firstly, an emulsion matrix was prepared by a two-phase emulsification of the oil–water mixture with a micro-emulsifier, which will undergo rapid oxidation–reduction reactions, forming detonation under high temperature to yield CoOx@CD powder. This powder was transferred to the Muffle furnace, then reduced at 500 °C under H2 atmosphere for 2 h to afford the desired Co@CD-500. As a comparison, Co@CD-400, Co@CD-700, CoMoOx@CD-500, and Co/C were also synthesized.
Initially, the HDO of stearic acid to stearic alcohol was chosen as a model reaction to optimize the reaction conditions (Table 1). Both Co@CD-500 and CoMoOx@CD-500 provide the best results by comparing five synthesized cobalt catalysts (entries 1–5). The reaction temperature, H2 pressure, and time were also optimized, and the reaction condition combination of 200 °C, 2 MPa H2 pressure, and 5 h reaction time emerged the best option (entries 6–9). When the reaction time was shortened to 4 h, Co@CD-500 provided higher yield of stearic alcohol than CoMoOx@CD-500, so Co@CD-500 has better catalytic activity for the reaction (entries 9 vs. 10).
As shown in Table 2, the present catalyst Co@CD-500 exhibits the best catalytic performance for the HDO of stearic acid to stearic alcohol by a comparison of the catalytic activity of other reported Co catalysts.
In order to get insights into high HDO activity of Co@CD-500, we analyzed and characterized structures of these Co catalysts. As depicted in Figure 2a, the proportion of Co0 in Co catalysis gradually increases as the reduction temperature increases. There is no signal of CoO in Co@CD-700, while Co@CD-500 has both signals of Co and CoO, and Co@CD-400 only has CoO signals. Compared with Co@CD-Y, Co/C has smaller Co and CoO signals, indicating that Co particles in Co/C are smaller and have lower crystallinity. The BET surface areas of Co@CD-400, Co@CD-500, and Co@CD-700 are 9.2 m2/g, 78.7 m2/g, and 21.1 m2/g, respectively (Table S1 and Figure S1). Co@CD-500 has the highest BET surface area and pore volume than other two catalysts. These results indicate that higher carbonization temperature (500 °C) promotes the formation of a well-developed mesoporous framework. However, further increasing the temperature to 700 °C results in a notable reduction in surface area and pore volume, while the average pore diameter expands to 7.41 nm, likely due to partial pore collapse or coalescence under extreme thermal conditions.
The N2 adsorption–desorption isotherms of Co@C-500 and Co@C-700 display typical type-IV curves with H3 hysteresis loops, confirming their mesoporous nature. The H3 loop, often associated with slit-shaped pores or aggregated plate-like particles, aligns with the observed increase in pore diameter and structural rearrangement at higher temperatures. The superior textural properties of Co@C-500 (high surface area, balanced pore volume, and moderate pore size) likely enhance mass transfer efficiency and active site accessibility, making it a promising candidate for catalytic applications. In contrast, the structural degradation in Co@C-700 and the underdeveloped porosity of Co@C-400 may limit their catalytic performance due to restricted reactant diffusion and reduced active surface exposure.
According to TEM images (Figure 2b–d), it is found that (1) Co mainly exists as amorphous particles in Co@CD-500, which are coated with a layer of carbon with a thickness of about 4 nm. (2) The crystal plane spacings of 0.217, 0.205, and 0.246 nm were measured, which are assigned to Co (100), Co (111), and CoO (111), respectively [32]. Raman and thermogravimetric analysis (TGA) results also confirm the existence of carbon in Co@CD-500, with a content of approximately 19.72% (Figures S2 and S3). Based on the TEM image of Co/C (Figure S4), no coating carbon layer was observed on its surface, whose Co particles have a smaller particle size, higher dispersion than that of Co@CD-500, and are only simply adsorbed on the surface of active carbon.
In order to further understand the chemical composition and valence states in the surface of Co catalysts, Co/C, Co@CD-700, Co@CD-500, and Co@CD-400 were charactered by X-ray photoelectron spectroscopy (XPS). All the Co catalysts showed a satellite peak of Co 2p3/2 at 787.1 eV, indicating the presence of CoO on the surface [34] (Figure 3a). As the reduction temperature increased, the signals of Co0 became strong, and the Co0 signal of Co@CD-400 became very weak [40], which is consistent with the XRD results. C 1s XPS results suggest that the preparation–reduction temperature is negatively correlated with the C-O signals (Figure 3b).
The fitting results of the O 1s XPS spectra of these Co catalysts (Figure 3c) indicate that lattice oxygen was not detected in the case of Co@CD-700, which is consistent with the XRD results. The Ovacancy content order is Co@CD-700 > Co@CD-500 > Co@CD-400, indicating that increasing the reduction temperature is beneficial for the formation of oxygen vacancies [34]. EPR results also suggest that both Co@CD-700 and Co@CD-500 contains Ovacancy (Figure S7).
The hydrogen temperature programmed desorption (H2-TPD) experiments on Co/C, Co@CD-500, and Co@CD-700 were also performed to determine the H2 adsorption and activation ability of these catalysts (Figure 3d). These three catalysts all have two main hydrogen desorption peaks: (1) The desorption peaks below 100 °C belong to the physical desorption of H2; (2) the desorption peaks above 350 °C are attributed to reverse H spillover [41,42]. The desorption peak of Co@CD-500 at high temperature is larger than that of Co/C and Co@CD-700, so Co@CD-500 has better H2 activation ability than Co/C and Co@CD-700 [43,44,45].
Kinetic studies were also carried out to obtain more information on the reaction mechanism (Figure 4a,b). The initial reaction rate was a negative correlation with the concentration of stearic acid, while there was a positive correlation with H2 pressure. Therefore, the rate-determining step (RDS) should include the H2 adsorption and activation process [6,7,46], and there may be competition between H2 and acid adsorption on catalyst surfaces [33].
NH3- and CO2-TPD results (Figures S5 and S6) suggest that Co@CD-700 should have more Lewis acid and base sites than that of Co@CD-500 [47,48]. Thus, Co@CD-700 should have a stronger adsorption capacity for lipids than Co@CD-500, but it actually inhibits the process of H2 adsorption and activation, which is not conducive to the HDO reaction. These results are consistent with the conclusions of kinetic studies.
According to the above results, the excellent catalytic performance of Co@CD-500 can be attributed to carbon coating and Co valence state. (1) The carbon layer can optimize the adsorption energy between the catalyst and lipids, making it easier to undergo desorption after conversion to alcohol. (2) The carbon coating inhibits the oxidation of Co particles, and both Co0 and CoO co-exist on the surface of Co particles. (3) CoO with oxygen vacancies is beneficial for the adsorption and activation of H2, which is the RDS of this HDO reaction, thereby exhibiting excellent HDO catalytic activity [34]. (4) The co-existence of CoO and Co0 over the cobalt particles might be responsible for its high performance for HDO of lipids to alcohols [32].
Compared with Co@CD-500, Co/C does not have a carbon coating while Co@CD-700 has a low CoO content, so the HDO catalytic performance of these two catalysts are inferior compared to Co@CD-500. The HDO catalytic activity of Co@CD-400 is low owing to the lack of Co0 on the surface of Co particles.
Other lipids including palmitic acid, glyceryl tristearate, and methyl stearate could be also applied in the Co@CD-500-catalyzed system (Figure 4c). Both glyceryl tristearate and palmitic acid could be converted into corresponding alcohols with excellent yields. In the case of methyl stearate, only a moderate yield (43%) of stearyl alcohol was observed. Finally, the recycling studies for Co@CD-500 was carried out (Figure 4d). This catalyst was separated via filtration and reused for the next run after n-heptane washing. There is still an 83% yield of stearyl alcohol after 5 runs. However, the yields of stearyl alcohol decreased to 76% and 35%, respectively, during the 6th and 7th runs of catalyst recycling. The tentative reaction pathway of the HDO is illustrated in Scheme 1. Carboxylic acids generally undergo two HDO processes to generate corresponding alcohols, while the main function of catalysts is to adsorb and activate substrates and H2 [28,34,45].
Given the importance of the Co valence state for catalytic activity, we compared the Co 2p XPS data before and after catalyst recovery. The results indicate that there was a red shift in the Co signal shift after 6 runs, suggesting an increase in the Co valence state and the oxidation of more Co0 on the Co surface (Figure S8). Although no significant agglomeration of the catalyst was found during the recycling process, the recovered catalyst particles have a certain degree of aggregation at the micro level according to TEM images (Figure S9). Therefore, we believe that the oxidation of the Co particle surface and the agglomeration of the catalyst may be the main cause of catalytic deactivation.

3. Materials and Methods

3.1. Chemical

Co(NO3)2·6H2O (purity, 99.0%), (NH4)6Mo7O24·4H2O (purity, 99.9%), urea (purity, 99.0%), stearic acid (purity, 99.0%), palmitic acid (purity, 99.0%), methyl stearate (purity, 99.0%), and glyceryl tristearate (purity, 99.0%) were purchased from Macklin (Shanghai, China). Activated carbon, white oil (mixtures of C16~C31 alkanes), and sorbitan monooleate were purchased from commercial sources. All chemicals were used without further purification.

3.2. The Synthesis of Co@CD-Y

As shown in Figure 5, 3.99 g of Co(NO3)2.6H2O was dissolved in 6 mL of deionized water, designated as the water phase, for later use. 2.36 g of sorbitol monooleate as the emulsifier was mixed with 4 g of 32# white oil as the oil phase. The water phase was slowly dropped and mixed with the oil phase by a micro-emulsifier to prepare the emulsion matrix at 55 °C under 800 r/min stirring speed for 5 min. The emulsion matrix is rapidly dedetonation (<1 s) in a crucible to yield CoOx@CD at ~350 °C. CoOx@CD was reduced at Y °C (Y = 400, 500, 700) under H2 atmosphere for 2 h to afford Co@CD-Y.
The preparation procedures of CoMoOx@CD-500 are the same with Co@CD-500, but the additional molar ratio of Co to Mo salts is 2:1.

3.3. The Synthesis of Co/C

5.0 g of urea, 1.49 g of Co(NO3)2.6H2O, and 1 g of activated carbon were stirred in 30 mL of deionized water for 30 min. Then, the solution was transferred to a high-pressure reactor, and heated at 140 °C for 9 h to yield CoOx/C. CoOx/C was reduced to 500 °C under H2 atmosphere for 2 h to obtain Co/C.

3.4. The Procedures for the HDO of Lipids to Alcohols

As shown in Scheme 2, 1 mmol of lipid, 30 mg of Co@CD-500, and 10 mL of heptane were placed in a 50 mL high pressure reactor. After sealing the reaction vessel, high-purity hydrogen gas was continuously filled into the reactor three times to discharge the original air in the reactor. Then, H2 was filled into the reactor to maintain an initial hydrogen pressure of 2.0 MPa. The reaction was performed at 200 °C for 5 h under 1000 rpm stirring. After the reaction was completed, the catalyst was separated by centrifugation and washed by n-heptane. Then, the recycled catalyst could be reused for another reaction cycle directly. The liquid phase was analyzed by GC and GC-MS to determine the reaction conversion and selectivity.

3.5. The H2-TPD Experiments

The H2-TPD experiments were recorded on an AutoChem II 2920 instrument. The catalyst sample was pre-reduced for 1 h in a flow of H2 at 773 K, purged by Ar at the same temperature for 0.5 h, and then cooled down to 323 K. The H2 uptake of the reduced catalyst could be determined by pulse-injecting 10% H2-Ar until saturation. After the H2 adsorption testing, the catalyst bed was purged again by He for 30 min at 323 K, before the temperature was linearly increased from 323 K to 1073 K at 10 K/min.

3.6. Material Characterization

BET surface areas of the Co@CD-400, Co@CD-500, and Co@CD-700 were determined by N2 adsorption using a Quantachrome NOVA 1000e apparatus (Quantachrome, Boynton Beach, FL, USA). NH3-and CO2-TPD were performed on an ASAP 2920 instrument (Micromeritics, Norcross, GA, USA). The samples were pretreated in He flow at 200 °C with a rate of 15 mL/min for 30 min and cooled to 50 °C, before being swept in NH3 (CO2) flow with a rate of 15 mL/min for 40 min. After treatment in He flow for 50 min to remove physical adsorption, the samples were raised at a heating rate of 10 °C/min to 800 °C, while the signals were monitored by a TCD detector.
GC-MS analyses were performed on an ISQ Trace 1300 (Thermo Fisher Scientific, Waltham, MA, USA) in the electron ionization (EI) mode. GC analyses are performed on an Agilent 7890A instrument (Agilent Technologies, Santa Clara, CA, USA, Column: Agilent 19091J413: 30 m × 320 μm × 0.25 μm, carrier gas: H2, FID detection).
The transmission electron microscopy (TEM) images were recorded using a PHILIPS Tecnai 12 microscope (Philips Electron Optics, Eindhoven, The Netherlands) operating at 120 kV. X-ray photoelectron spectroscopy (XPS) was performed on an ESCALAB 250Xi spectrometer (Thermo Fisher Scientific, East Grinstead, UK) using an Al Kα X-ray source (1486.6 eV of photons) and calibrated by setting the C 1s peak to 284.80 eV.
XRD analysis was performed on a Shimadzu X-ray diffractometer (XRD-6000, Shimadzu Corporation, Kyoto, Japan) with Cu Kα irradiation. The electron paramagnetic resonance (EPR) spectra were recorded on a Bruker A300 Instrument (Bruker Corporation, Billerica, MA, USA) operating at 77 K by using an X-band (9.65 GHZ and 0.94 m). The carbon content in the catalyst was quantified by thermogravimetry (DTG-60H, Shimadzu Corporation, Kyoto, Japan). The Raman spectra of the catalyst was obtained using a Horiba LabRam HR (Horiba, Kyoto, Japan).

4. Conclusions

In summary, a carbon-coated Co catalyst (Co@CD-500) has been developed by a detonation strategy, which can achieve the selective HDO of lipids to alcohols at 200 °C with 2 MPa H2. The excellent catalytic performance of Co@CD-500 can be attributed to carbon coating and Co valence state. The carbon layer can optimize the adsorption energy between the catalyst and lipids, making it easier to undergo H2 absorption. The carbon coating inhibits the oxidation of Co particles, and both Co0 and CoO co-exist on the surface of Co particles. CoO with oxygen vacancies is beneficial for the adsorption and activation of H2, which is the RDS of this HDO reaction, thereby exhibiting excellent HDO catalytic activity. The co-existence of CoO and Co0 over the cobalt particles might be responsible for its high performance of HDO of lipids to alcohols. Furthermore, this catalyst can be recycled for at least 5 runs without obvious loss of activity.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/catal15030254/s1, Figure S1: Nitrogen adsorption isotherms for Co@CD-400, Co@CD-500, and Co@CD-700; Table S1: BET analysis data of Co@CD-400, Co@CD-500, and Co@CD-700; Figure S2: The Raman spectra of Co NPs, Co@CD-400, Co@CD-500, and Co@CD-700; Figure S3: The TGA spectra of Co@CD-500; Figure S4: TEM images of Co/C; Figure S5: NH3-TPD spectra of Co@CD-500 and Co@CD-700; Figure S6: CO2-TPD spectra of Co@CD-500 and Co@CD-700; Figure S7: EPR spectra of Co@CD-500 and Co@CD-700; Figure S8: Co 2p XPS spectra of Co@CD-500 and Co@CD-500 recycled after 6 runs. Figure S9: TEM images of Co@CD-500 recycled after 6 runs.

Author Contributions

L.C.: conceptualization, methodology, formal analysis, writing—review and editing. J.W.: validation, formal analysis, investigation. A.C.: investigation, data curation. G.-P.L.: supervision, writing—review and editing, funding acquisition. C.C.: writing—review and editing, supervision, funding acquisition. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data are available in the main text.

Conflicts of Interest

Jing Wu was employed by the company China Coal Technology and Engineering Group Huaibei Blasting Technology Research Institute Limited Company. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Catalysts 15 00254 g001
Figure 1. The procedures for the synthesis of Co@CD-500.
Figure 1. The procedures for the synthesis of Co@CD-500.
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Catalysts 15 00254 g002
Figure 2. (a) XRD patterns of Co catalysts; (b) TEM image of Co@CD-500; (c,d) HRTEM images of Co@CD-500.
Figure 2. (a) XRD patterns of Co catalysts; (b) TEM image of Co@CD-500; (c,d) HRTEM images of Co@CD-500.
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Catalysts 15 00254 g003
Figure 3. XPS spectra of (a) Co 2p, (b) C 1s, and (c) O 1s of different Co catalysts; (d) H2-TPD spectra of Co/C, Co@CD-500, and Co@CD-700.
Figure 3. XPS spectra of (a) Co 2p, (b) C 1s, and (c) O 1s of different Co catalysts; (d) H2-TPD spectra of Co/C, Co@CD-500, and Co@CD-700.
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Catalysts 15 00254 g004
Figure 4. Initial reaction rate at different (a) concentrations of stearic acid and (b) H2 pressures. (c) The HDO of different lipids. Conditions: Co@CD-500, 30 mg; lipid, 1 mmol; n-heptane, 10 mL; 2 MPa H2; 5 h. (d) Recycle studies. Conditions: Co@CD-500, 30 mg; stearic acid, 1 mmol; n-heptane, 10 mL; 2 MPa H2; 200 °C; 5 h.
Figure 4. Initial reaction rate at different (a) concentrations of stearic acid and (b) H2 pressures. (c) The HDO of different lipids. Conditions: Co@CD-500, 30 mg; lipid, 1 mmol; n-heptane, 10 mL; 2 MPa H2; 5 h. (d) Recycle studies. Conditions: Co@CD-500, 30 mg; stearic acid, 1 mmol; n-heptane, 10 mL; 2 MPa H2; 200 °C; 5 h.
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Catalysts 15 00254 sch001
Scheme 1. The tentative reaction pathway of the HDO of fatty acid.
Scheme 1. The tentative reaction pathway of the HDO of fatty acid.
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Figure 5. The procedures for the synthesis of Co@CD-Y.
Figure 5. The procedures for the synthesis of Co@CD-Y.
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Catalysts 15 00254 sch002
Scheme 2. Schematic of the hydrodeoxygenation process from lipids to alcohols.
Scheme 2. Schematic of the hydrodeoxygenation process from lipids to alcohols.
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Table 1. Optimization reaction conditions a.
Table 1. Optimization reaction conditions a.
Catalysts 15 00254 i001
EntryCatalystConversion (%)Selectivity b
n-C17H36n-C18H38n-C18H38OHTON g
1Co@CD-400500>990.12
2Co@CD-500>9900>992.39
3Co@CD-7002400>990.58
4CoMoOx@CD-500>9900>992.39
5Co/C00000
6Co@CD-500 c5100>991.22
7Co@CD-500 d5920981.41
8Co@CD-500 e6900>993.31
9Co@CD-500 f9400>990.12
10CoMoOx@CD-500 f8600>992.39
a Conditions: catalyst, 30 mg; stearic acid, 1 mmol; n-heptane, 10 mL; 200 °C; 2 MPa H2; 5 h. b The conversions and selectivity are determined by GC, using chlorobenzene as the internal standard. c 190 °C; d 1 MPa H2; e 15 mg; f 4 h. g Assuming that all cobalt sites are active centers.
Table 2. Comparison of Co catalysts for the HDO of stearic acid to stearic alcohol.
Table 2. Comparison of Co catalysts for the HDO of stearic acid to stearic alcohol.
EntryCatalyst (g/mol)ConditionsC/S aRef.
1Co-350 (41)200 °C, iPrOH, 4 h100/92[32]
2CoAl-LDO600 (162)200 °C, iPrOH, 3 h100/94[35]
3Co/HAP (200)290 °C, MeOH, 5 h95/68[36]
4Co/Al2O3 (57)300 °C, 5 MPa H2, 15 h91/73[23]
5Co3O4-573 (67)200 °C, 2 MPa H2, 3 h100/98[37]
6Co@C (128)200 °C, 4 MPa H2, 1 h98/97[38]
7Co@CN-900 (128)220 °C, 4 MPa H2, 0.5 h90/97[22]
8hcp-Co@G400 (50)220 °C, 5 MPa H2, 24 h>99/91[39]
9Co@C-500 (30)200 °C, 2 MPa H2, 5 h>99/>99This work
a C means conversion, and S means selectivity.
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Chen, L.; Wu, J.; Chang, A.; Lu, G.-P.; Cai, C. Carbon-Coated Cobalt-Catalyzed Hydrodeoxygenation of Lipids to Alcohols. Catalysts 2025, 15, 254. https://doi.org/10.3390/catal15030254

AMA Style

Chen L, Wu J, Chang A, Lu G-P, Cai C. Carbon-Coated Cobalt-Catalyzed Hydrodeoxygenation of Lipids to Alcohols. Catalysts. 2025; 15(3):254. https://doi.org/10.3390/catal15030254

Chicago/Turabian Style

Chen, Long, Jing Wu, Ai Chang, Guo-Ping Lu, and Chun Cai. 2025. "Carbon-Coated Cobalt-Catalyzed Hydrodeoxygenation of Lipids to Alcohols" Catalysts 15, no. 3: 254. https://doi.org/10.3390/catal15030254

APA Style

Chen, L., Wu, J., Chang, A., Lu, G.-P., & Cai, C. (2025). Carbon-Coated Cobalt-Catalyzed Hydrodeoxygenation of Lipids to Alcohols. Catalysts, 15(3), 254. https://doi.org/10.3390/catal15030254

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