Preparation of a magnetic ternary metal catalyst, NiZr / CoOx, and method for catalytic hydrogenation of biomass-derived compounds

Abstract

The application adopts a co-precipitation method to prepare a NiZr / CoOx catalyst prepared by topological transformation of a layered double hydroxide (LDHs) precursor and a method for catalytic hydrogenation of biomass-derived compounds. The catalyst used is a NiZrCo catalyst prepared by a co-precipitation method. The method used is: adding unsaturated biomass-derived compounds into a reaction container containing a solvent, using isopropyl alcohol as a solvent and a hydrogen source, and realizing the hydrogenation reaction of aldehyde ketone compounds under the action of the NiZr / CoOx catalyst. In order to improve the catalytic activity of Co species in the hydrogenation reaction, Ni and Zr are doped in the cobalt salt to obtain the catalyst. The addition of Zr not only helps the dispersion of Ni and Co, but also provides acid sites for the catalytic system, the strong electronic interaction between metal species improves the catalytic activity, and the existence of oxygen vacancies provides adsorption sites for C=O in furfural, greatly improving the catalytic performance. The method for preparing the NiZr / CoOx catalyst doped with Ni, Zr and Co is simple, the process is easy to operate, the obtained catalyst has high activity, and exhibits good catalytic performance in the catalytic hydrogenation reaction of biomass-derived compounds. The catalyst has magnetism, and is convenient for recycling. In addition, the method uses an in-situ hydrogenation method to replace the traditional external hydrogen to provide a hydrogen source, and has high safety.

Description

Technical Field

[0001] This invention relates to the field of catalysts and their application technology, specifically to a method for preparing ternary metal NiZr / CoOx catalysts and their applications. Background Technology

[0002] In the context of excessive depletion of petrochemical reserves, emerging energy and economic problems, and the urgent need to achieve carbon neutrality, biomass, as the only renewable resource, is an ideal substitute for traditional petrochemical resources. It can be converted into a variety of sustainable production feedstocks, fuels, and platform chemicals. Among all platform molecules, furfural (FF) has attracted much attention as the only unsaturated, commercially available organic chemical prepared from biomass through hemicellulose dehydration and cyclization. Biomass fuels and platform chemicals often have a higher carbon-to-oxygen ratio; therefore, hydrogenation has become an important pathway to achieve high-value utilization of biomass chemicals. Furfural's unique abundance of functional groups (C=C, C=O) gives it strong reactivity, enabling the production of various chemicals such as furfuryl alcohol (FA), 2-methylfuran, cyclopentanone, and 1,4-pentanediol. Due to the numerous potential products, catalytic systems for the selective hydrogenation of furfural to specific products have significant research value. In furfural hydrogenation systems, FA can be used to synthesize biofuel molecules, resins, and adhesives, and has therefore been extensively studied.

[0003] Current research focuses on bimetallic catalysts composed of inexpensive and precious metals, or precious metal catalysts supported on carriers. Precious metals are scarce in the Earth's crust, and their extraction is costly, difficult, and biotoxic. Therefore, developing efficient non-precious metal catalysts is crucial for reducing catalyst costs and achieving excellent biocompatibility. Inexpensive metal oxides are a very promising option. Compared to single-metal oxides or bimetallic oxides, multi-metal alloying not only reduces the demand for precious metals but also optimizes the geometry and electronic structure of metal sites, often resulting in multiple active components and better controllability.

[0004] Catalytic systems for hydrogenation reactions typically use hydrogen or formic acid as the hydrogen source. Molecular hydrogen inevitably presents safety concerns during transportation, use, and storage, and its use under high temperature and pressure requires specific equipment. Using formic acid as a hydrogen source not only corrodes the reactor but also generates CO2, which can negatively impact the reaction. Therefore, developing alcohols as hydrogen donors and solvents for efficient catalysis of furfural to femtocarbonyl (FA) conversion at atmospheric pressure is crucial. The aforementioned catalysts exhibit harsh reaction conditions in the selective hydrogenation of furfural, including long reaction times, high temperatures, and low selectivity. Therefore, designing and constructing inexpensive metal catalysts, reducing reaction conditions, improving product selectivity, and minimizing byproduct formation are of great significance. Summary of the Invention

[0005] Based on the above background technology, this invention employs a co-precipitation method to prepare a NiZr / CoOx catalyst from a layered double hydroxide (LDH) precursor through a structural topological transformation, and a method for its application in the catalytic hydrogenation of biomass-derived compounds. The catalyst used is a NiZr / CoOx catalyst prepared by the co-precipitation method. The method involves adding biomass-derived compounds to a reaction vessel containing a solvent, using isopropanol as both the solvent and hydrogen source, and achieving the hydrogenation reaction of these biomass-derived aldehydes and ketones under the action of the NiZr / CoOx catalyst. To improve the catalytic activity of Co species in the hydrogenation reaction, Ni and Zr are doped into the cobalt salt to obtain the desired catalyst. The addition of Zr not only helps disperse Ni and Co but also provides acidic sites for the catalytic system. The strong electronic interactions between metal species enhance the catalytic activity, and the presence of oxygen vacancies provides adsorption sites for C=O in furfural, greatly improving the catalytic performance.

[0006] The technical solution of the present invention is as follows:

[0007] A ternary metal catalyst NiZr / CoOx prepared by co-precipitation method is described in the following steps:

[0008] 1) Dissolve a certain amount of Co(NO3)3·6H2O and Ni(NO3)2·6H2O and ZrOCl·8H2O in the corresponding Ni:Zr molar ratio in deionized water and stir to form a mixed solution.

[0009] 2) Using a mixed solution of NaOH and Na₂CO₃ as the precipitant, based on the required molar amount of alkali for metal precipitation, the resulting mixed metal solution is added dropwise to the alkali solution. After filtering the obtained solid, it is washed with deionized water until neutral. The separated solid is then dried in an oven.

[0010] 3) After drying, the obtained solid is calcined in a muffle furnace at high temperature for a certain time to obtain NiZr. α / CoOx-β precursor, where α represents the molar ratio of Zr in the catalyst and β represents different reduction temperatures. All samples were reduced at their respective reduction temperatures prior to catalytic testing.

[0011] 4) In addition, CoOx, NiO, ZrO2, Ni / CoOx and Zr / CoOx were synthesized using the same synthesis method.

[0012] The application of the ternary metal catalyst in the catalytic hydrogenation of biomass-derived compounds.

[0013] The biomass-derived compounds are unsaturated aldehydes and ketones such as furfural;

[0014] The specific applications are as follows:

[0015] An unsaturated aldehyde-ketone compound, the ternary metal catalyst, and isopropanol are added to a pressure-resistant tube. The amount of substrate added is 1-5 mmol, and the mass of the catalyst is 80-160 mg. The reaction is carried out under a nitrogen atmosphere at a temperature of 120-190 °C for 0.5-14 h. The solvent is isopropanol.

[0016] Beneficial effects: Compared with existing technologies, the advantages of this invention include: the preparation method of the ternary metal catalyst NiZr / CoOx provided by this invention is simple, exhibits high hydrogenation activity, and can produce hydrogenation effects similar to those of noble metals. Moreover, all metals are non-noble metals, making them relatively inexpensive. Doping with multiple metals not only increases catalytic activity but also improves catalyst stability and product selectivity. The catalyst exhibits high stability. Furthermore, due to its magnetic properties, the catalyst is easily recyclable. Attached Figure Description

[0017] Figure 1 These are TEM and HRTEM images of the ternary metal catalyst NiZr1 / CoOx-400 prepared in Example 1, as well as corresponding elemental mapping images of Ni, Zr, Co, and mixtures.

[0018] Figure 2 This is the X-ray diffraction pattern of the ternary metal catalyst NiZr / CoOx prepared in Example 1.

[0019] Figure 3 The stability test of the catalyst prepared in Example 1. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0021] Example 1

[0022] 1. Preparation of NiZr1 / CoOx-400 catalyst:

[0023] 1.454 g Ni(NO3)2·6H2O, 1.611 g ZrOCl·8H2O, and 2.9103 g Co(NO3)3·6H2O were added to 50 ml of deionized water and then magnetically stirred for 6 h. A mixed solution of 0.05 mol NaOH and 0.025 mol Na2CO3 was used as a precipitant, and the resulting mixed metal solution was added dropwise to an alkaline solution. The resulting solid was filtered and washed with deionized water until neutral. The separated solid was dried in an oven at 80 °C. After drying, the solid was calcined in a muffle furnace at 450 °C for 2 h and then reduced in a tube furnace at 400 °C for 2 h to obtain the catalyst.

[0024] 2. NiZr1 / CoOx-400 catalyst catalyzes the hydrogenation reaction of furfural:

[0025] 1 mmol of furfural, 0.12 g of NiZr1 / CoOx-400 catalyst, and 5 ml of isopropanol were added to a pressure-resistant tube. The reaction was carried out at 180 °C under normal pressure (N2) for 12 h. After the reaction was completed, the mixture was cooled to room temperature, and the liquid was analyzed by gas chromatography. The furfural conversion rate was 100%, and the furfuryl alcohol yield was 99.12%.

[0026] Example 2

[0027] The reaction steps are exactly the same as in Example 1, except that:

[0028] In the catalyst preparation step, NiZr was prepared. 0.5 / CoOx. The furfural conversion rate was 96.55%, and the yield of the main product, furfuryl alcohol, was 91.57%.

[0029] Example 3

[0030] The reaction steps are exactly the same as in Example 1, except that:

[0031] In the catalyst preparation step, NiZr was prepared. 1.5 / CoOx. The furfural conversion rate was 97.72%, and the yield of the main product, furfuryl alcohol, was 94.02%.

[0032] Example 4

[0033] The reaction steps are exactly the same as in Example 1, except that:

[0034] In the catalyst preparation step, Ni / CoOx was prepared. The furfural conversion rate was 11.36%, and the yield of the main product, furfuryl alcohol, was 5.5%.

[0035] Example 5

[0036] The reaction steps are exactly the same as in Example 1, except that:

[0037] In the catalyst preparation step, Zr / CoOx was prepared. The furfural conversion rate was 94.21%, and the yield of the main product, furfuryl alcohol, was 87.44%.

[0038] Example 6

[0039] The reaction steps are exactly the same as in Example 1, except that:

[0040] In the catalyst preparation step, NiZr1 / CoOx-200 was prepared. The furfural conversion rate was 100%, and the yield of the main product, furfuryl alcohol, was 96.40%.

[0041] Example 7

[0042] The reaction steps are exactly the same as in Example 1, except that:

[0043] In the catalyst preparation step, NiZr1 / CoOx-300 was prepared. The furfural conversion rate was 98.97%, and the yield of the main product, furfuryl alcohol, was 94.04%.

[0044] Example 8

[0045] The reaction steps are exactly the same as in Example 1, except that:

[0046] In the catalyst preparation step, NiZr1 / CoOx-500 was prepared. The furfural conversion rate was 55.75%, and the yield of the main product, furfuryl alcohol, was 41.92%.

[0047] Example 9

[0048] The catalyst preparation is exactly the same as in Example 1, except that:

[0049] In the reaction step, furfural reacted for 0.5 h, the furfural conversion rate was 29.11%, and the yield of the main product furfuryl alcohol was 20.92%.

[0050] Example 10

[0051] The catalyst preparation is exactly the same as in Example 1, except that:

[0052] In the reaction step, furfural reacted for 1 hour, the furfural conversion rate was 40.79%, and the yield of the main product, furfuryl alcohol, was 32.21%.

[0053] Example 11

[0054] The catalyst preparation is exactly the same as in Example 1, except that:

[0055] In the reaction step, furfural reacted for 2 hours, the furfural conversion rate was 83.47%, and the yield of the main product furfuryl alcohol was 76.57%.

[0056] Example 12

[0057] The catalyst preparation is exactly the same as in Example 1, except that:

[0058] In the reaction step, furfural reacted for 4 hours, the furfural conversion rate was 92.36%, and the yield of the main product furfuryl alcohol was 76.57%.

[0059] Example 13

[0060] The catalyst preparation is exactly the same as in Example 1, except that:

[0061] In the reaction step, furfural reacted for 6 hours, the furfural conversion rate was 97.78%, and the yield of the main product furfuryl alcohol was 94.38%.

[0062] Example 14

[0063] The catalyst preparation is exactly the same as in Example 1, except that:

[0064] In the reaction step, furfural was reacted for 8 hours, the furfural conversion rate was 99.26%, and the yield of the main product furfuryl alcohol was 95.52%.

[0065] Example 15

[0066] The catalyst preparation is exactly the same as in Example 1, except that:

[0067] In the reaction step, furfural reacted for 10 hours, the furfural conversion rate was 99.58%, and the yield of the main product furfuryl alcohol was 98.63%.

[0068] Example 16

[0069] The catalyst preparation is exactly the same as in Example 1, except that:

[0070] In the reaction step, furfural reacted for 14 hours, the furfural conversion rate was 100%, and the yield of the main product furfuryl alcohol was 94.64%.

[0071] Example 17

[0072] The catalyst preparation is exactly the same as in Example 1, except that:

[0073] In the reaction step, the reaction temperature was 150℃, and the furfural conversion rate was 81.43%. The yield of the main product, furfuryl alcohol, was 74.12%.

[0074] Example 18

[0075] The catalyst preparation is exactly the same as in Example 1, except that:

[0076] In the reaction step, the reaction temperature was 160℃, and the furfural conversion rate was 84.12%. The yield of the main product, furfuryl alcohol, was 79.17%.

[0077] Example 19

[0078] The catalyst preparation is exactly the same as in Example 1, except that:

[0079] In the reaction step, the reaction temperature was 170℃, and the furfural conversion rate was 99.41%. The yield of the main product, furfuryl alcohol, was 95.52%.

[0080] Example 20

[0081] The catalyst preparation is exactly the same as in Example 1, except that:

[0082] In the reaction step, the reaction temperature was 190℃, and the furfural conversion rate was 100%. The yield of the main product, furfuryl alcohol, was 88.35%.

[0083] Example 21

[0084] The catalyst preparation is exactly the same as in Example 1, except that:

[0085] In the reaction step, 1 mmol of benzaldehyde was measured, and the conversion rate of benzaldehyde was 100%. The yield of the product benzyl alcohol was 100%.

[0086] Example 22

[0087] The catalyst preparation is exactly the same as in Example 1, except that:

[0088] In the reaction step, 1 mmol of phenylacetaldehyde was measured, and the conversion rate of phenylacetaldehyde was 100%. The yield of the product phenylethanol was 100%.

[0089] Example 23

[0090] The catalyst preparation is exactly the same as in Example 1, except that:

[0091] In the reaction step, 1 mmol of cyclohexanone was measured, and the conversion rate of cyclohexanone was 100%. The yield of the product cyclohexanol was 100%.

[0092] Example 24

[0093] The catalyst preparation is exactly the same as in Example 1, except that:

[0094] In the reaction step, 1 mmol of ethyl levulinate was measured, and the conversion rate of ethyl levulinate was 61.97%. The yield of the product γ-valerolactone was 53.47%.

[0095] Example 25

[0096] The catalyst preparation is exactly the same as in Example 1, except that:

[0097] In the reaction step, 1 mmol of p-nitrosaldehyde was measured, and the conversion rate of p-nitrosaldehyde was 92.02%. The yield of the product p-nitrobenzyl alcohol was 82.09%.

[0098] Example 26

[0099] The catalyst preparation is exactly the same as in Example 1, except that:

[0100] In the reaction step, 1 mmol of n-heptanal was measured, and the conversion rate of n-heptanal was 78.93%. The yield of the product n-heptanol was 77.02%.

[0101] Example 27

[0102] The catalyst preparation is exactly the same as in Example 1, except that:

[0103] In the reaction step, 1 mmol of cinnamaldehyde was measured, and the conversion rate of cinnamaldehyde was 74.18%. The yield of the product cinnamyl alcohol was 56.98%.

[0104] Example 28

[0105] The catalyst preparation is exactly the same as in Example 1, except that:

[0106] In the reaction step, 1 mmol of 5-methylfurfural was measured, and the conversion rate of 5-methylfurfural was 46.05%. The yield of the product 5-methylfurfural was 45.54%.

[0107] Figure 1 These are TEM and HRTEM images of the ternary metal catalyst NiZr1 / CoOx-400 prepared in Example 1, along with corresponding elemental mapping images of Ni, Zr, Co, and mixtures. A TEM image of the Co-based catalyst is also shown. Except for CoOx, the other catalysts exhibit a layered porous structure with interconnected nanosheets, indicating that the layered framework of the LDH structure is retained in the reduced sample, providing numerous exposed active sites for the adsorption and full reaction of more reactant molecules. The addition of Zr promotes the distribution of Co species and inhibits their sintering. HRTEM images show that the three phases in Ni-Zr / CoOx-400 are in close contact, forming a mixed crystalline phase. Elemental mapping images show a high distribution trend of Ni, Zr, and Co species in NiZr / CoOx-400, as perfect overlap is observed between Ni, Co, and Zr species, further confirming the close contact between the ternary metals in the Ni-Zr / CoOx-400 catalyst.

[0108] Figure 2 This is the X-ray diffraction pattern of the ternary metal catalyst NiZr / CoOx prepared in Example 1.

[0109] The XRD pattern of the NiZr / CoOX catalyst is as follows: Figure 2As shown in a and b, the reduced CoOx exists in the form of Co3O4 (JCPDS 74-1657) and CoO (JCPDS 74-2391) phases. Co3O4 exhibits five XRD characteristic peaks located at 31.3, 36.9, 44.9, 59.5, and 65.4°, respectively, assigned to the (220), (311), (400), (422), and (440) cobalt-based crystal planes. Diffraction peaks at 36.4, 42.3, and 61.4° belong to the (111), (200), and (220) crystal planes of the CoO phase. Compared with CoOx, Ni / CoOx exhibits NiO (2θ = 43.3) and NiO (2θ = 43.3). 0 (2θ = 51.8, 76.3°). The Co3O4 diffraction peak with 2θ of approximately 36.9° in Ni / CoOx shifts to higher angles because the atomic radius of Ni is smaller than that of Co, resulting in a smaller lattice constant. Although the addition of Zr causes a shift of 2θ to a smaller angle, the amount of Zr doping is limited, and the effect of Ni doping on shifting 2θ to a higher angle is more pronounced.

[0110] Furthermore, the Zr / CoOx catalyst exhibits characteristics of cobalt oxide spinel, with the Co3O4 diffraction peak shifted towards a smaller 2θ. No zirconium oxide phase signal was detected, which is attributed to lattice expansion caused by Zr incorporation into the Co3O4 lattice, leading to an increase in the lattice constant. Compared to catalysts prepared in previous literature, this catalyst has a smaller lattice constant, indicating that more Zr material is incorporated into the Co3O4 lattice, thus forming more oxygen vacancies. Even after reaching the maximum amount of dopant that can be incorporated into the lattice, the excess Zr species remain highly dispersed, indicating successful incorporation of some Zr into the Co3O4 lattice and the high dispersion of ZrO2. Zr doping weakens or broadens the signal, indicating reduced crystallinity and smaller Co3O4 crystallite size, which will promote catalytic activity. In the NiZr / CoOx catalyst, the Co3O4 peak intensity decreases with increasing Zr doping concentration, and the NiZr... 1.5 / CoOx-400 exhibits the weakest and broadest diffraction peaks, corresponding to the smallest Co3O4 crystallite size of 6.5 nm. Appropriate Zr content contributes to the formation of a more uniform ternary solid solution, corresponding to a reduction in crystal size and lattice parameters.

[0111] It is noteworthy that at lower reduction temperatures, only a Co3O4 diffraction peak appears at 36.9°C. When the reduction temperature increases from 200°C to 300°C, the grain size rapidly decreases from 10.7 nm to 7.5 nm, and the lattice constant of the sample also increases from 8.0852 to 8.0889. Further increasing the temperature to 400°C, the grain size decreases to 6.9 nm, but after reduction at 500°C, the grain size increases to 11.4 nm. This is due to the formation of larger microcrystals caused by the sintering of Co species, resulting in a significant increase in diffraction peak intensity and a sharper peak pattern, indicating the emergence of the ZrO2 monoclinic phase.

[0112] Figure 3 The stability test of the catalyst prepared in Example 1 was repeated three times, and its catalytic effect remained basically unchanged.

[0113] Table 1 shows the conversion rate and yield of major products of the NiZr / CoOx ternary metal catalysts prepared in Examples 1-8 for the hydrogenation of furfural. It can be seen from Table 1 that NiZr1 / CoOx-400 has the best catalytic performance.

[0114] Table 2 shows the effect of different reaction times on Examples 1, 9-16. As can be seen from the table, the catalyst exhibits the best catalytic performance when the reaction time is 12 hours, resulting in complete conversion of furfural. The yield of the main product, furfuryl alcohol, is as high as 99.12%.

[0115] Table 3 shows the effect of different reaction temperatures on Examples 1, 17-20. It can be seen that the highest catalytic effect can be achieved at a reaction temperature of 180°C.

[0116] Table 4 shows the reaction effects of different substrates on the NiZr1 / CoOx-400 catalyst for hydrogenation in Examples 21-27.

[0117] Table 1 shows the catalytic effects of different NiZr / CoOx metal catalysts prepared in Examples 1-8 on the hydrogenation reaction of furfural.

[0118]

[0119] Table 2 shows the effect of different reaction times on Examples 1, 9-16.

[0120]

[0121] Table 3 shows the effect of different reaction temperatures on Examples 1, 17-20.

[0122]

[0123]

[0124] Table 4 shows the reaction effects of different substrates on the NiZr1 / CoOx-400 catalyst for hydrogenation in Examples 21-27.

[0125]

[0126] The above embodiments are implementation methods adopted by the present invention, but the implementation methods of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for the catalytic hydrogenation of biomass-derived compounds, characterized in that, A catalytic hydrogenation reaction is achieved by adding an unsaturated biomass-derived compound as a substrate, isopropanol as a solvent and hydrogen donor, and a ternary metal catalyst to a pressure-resistant tube, and then introducing a certain amount of N2. The amount of the substrate is 1-5 mmol, the mass of the catalyst is 80-160 mg, the reaction is carried out under a nitrogen atmosphere, the reaction temperature is 120-190℃, and the reaction time is 0.5-14 h. The unsaturated biomass-derived compound is an unsaturated aldehyde or ketone compound. The specific steps for preparing the ternary metal catalyst are as follows: 1.454 g Ni(NO3)2·6H2O, 1.611 g ZrOCl·8H2O, and 2.9103 g Co(NO3)3·6H2O were added to 50 ml of deionized water and then magnetically stirred for 6 h. A mixed solution of 0.05 mol NaOH and 0.025 mol Na2CO3 was used as a precipitant, and the resulting mixed metal solution was added dropwise to an alkaline solution. The obtained solid was filtered and washed with deionized water until neutral. The separated solid was dried in an oven at 80 °C. After drying, the obtained solid was calcined in a muffle furnace at 450 °C for 2 h and reduced in a tube furnace at 400 °C for 2 h to obtain the catalyst NiZr1 / CoOx-400.

Images