Nickel-based catalyst based on template-free synthesis and preparation method and application thereof
Patent Information
- Application Number
- CN202611399909.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-10
- Publication Date
- 2026-10-16
Smart Images
Figure CN122912887A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a nickel-based catalyst synthesized by a template-free method, its preparation method, and its application. Background Technology
[0002] Sorbitol is a broad-spectrum chemical product widely used in the pharmaceutical and cosmetic fields. Current technologies primarily focus on the one-step preparation of sorbitol from cellulose. This reaction involves a two-step cascade reaction: cellulose hydrolysis and glucose hydrogenation. The former, as the rate-limiting step in the cascade reaction, requires high temperature and strong acid catalysis for hydrolysis; while the latter requires hydrogenation under metal catalysis at a relatively mild temperature.
[0003] Nickel phosphide exhibits significant advantages as a hydrogenation center in nickel-based catalysts. As noted in the literature (Applied Catalysis B: Environment and Energy, 2026, 381, 125855), compared to metallic nickel, it provides a more efficient homolytic cleavage of H2 molecules. Nickel phosphide produces H+ through heterolytic cleavage of H2 molecules. d+ and H d- This catalyst, while acting as a hydrogenation agent, also assists in the hydrolysis process, further improving the yield of sorbitol from cellulose. A previous report (ACS Catalysis 2026, 16, 504-518) described the preparation of a catalyst using gallic acid and Ni salt co-carbonation with the addition of F127 as a template agent, catalyzing a one-step process for sorbitol production from cellulose. However, the catalyst preparation process inevitably involves activation with KHCO3 and phosphating with sodium hypophosphite. Hypophosphite poses safety hazards during use; it decomposes explosively at the reduction temperature, producing large amounts of flammable and toxic phosphine gas that is difficult to fully utilize and is often released into the atmosphere, resulting in poor environmental friendliness.
[0004] Therefore, developing a greener, more environmentally friendly, template-free method for preparing sorbitol catalysts while simultaneously achieving in-situ accessibility to the active site is a current challenge. Summary of the Invention
[0005] The purpose of this invention is to provide a nickel-based catalyst synthesized by a template-free method, its preparation method, and its application, so as to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions: Phytic acid is dissolved in a solvent to obtain a phytic acid solution; The nickel salt is dissolved in a solvent to obtain a nickel salt solution; A nickel salt solution is added dropwise to a phytic acid solution while stirring, controlling the molar ratio of phytic acid to nickel salt at 1:(0.5-2), so that phytic acid and nickel ions form an unsaturated complex, yielding a nickel phytate solution; the mass of the phytic acid accounts for 5%-10% of the total mass of the nickel phytate solution; A nickel phytate solution and a lignin solution are mixed and dried to obtain a catalyst precursor; the lignin accounts for 5%-10% of the total mass of the lignin solution; the mass ratio of the nickel phytate solution to the lignin solution is 1:(0.5-2); The catalyst precursor was subjected to heat treatment in an oxygen-containing atmosphere and reduction treatment in a reducing atmosphere to obtain a phosphorus-doped porous carbon-confined nickel-based catalyst.
[0007] Furthermore, the nickel salt is one or more of nickel nitrate, nickel acetylacetonate, and nickel acetate.
[0008] Furthermore, the solvent is water and / or ethanol.
[0009] Furthermore, the lignin is extracted from agricultural and forestry waste using an alcohol-soluble method; the agricultural and forestry waste includes one or more of tobacco stalks, castor stalks, beech wood chips, camellia shells, corn cobs, and walnut shells.
[0010] Furthermore, the method for mixing the nickel phytate solution and the lignin solution is as follows: Under stirring at 50-60℃, lignin is added to the solvent and stirring is continued to obtain a lignin solution. Then, nickel phytate solution is added dropwise to the lignin solution and stirred.
[0011] Furthermore, the oxygen-containing atmosphere is air or oxygen, and the heat treatment temperature is 250-300℃; the reducing atmosphere is hydrogen or a hydrogen-containing mixture, and the reduction treatment temperature is 650-700℃.
[0012] Another object of the present invention is to provide a nickel-based catalyst prepared by the above preparation method, wherein the nickel-based catalyst has a PCO defect structure, and the Ni2P nanoparticles contained therein are uniformly dispersed in phosphorus-doped porous carbon.
[0013] Another object of the present invention is to provide the application of the above-mentioned nickel-based catalyst in the catalytic preparation of sorbitol.
[0014] Furthermore, the method for preparing sorbitol includes the following steps: The nickel-based catalyst, cellulose and / or the remaining components from lignin extraction, and water are mixed and reacted at 150-210°C in a hydrogen atmosphere to obtain sorbitol.
[0015] The present invention provides a method for preparing nickel-based catalysts based on template-free synthesis. This method does not require additional acid-base activation or template agents. It only utilizes the complexation of lignin, phytic acid and nickel ions, followed by heat treatment under different atmospheres and temperatures, to construct in situ a highly dispersed nickel-based catalyst with phosphorus doped porous carbon confinement.
[0016] This invention utilizes the strong chelating effect of phytic acid to complex nickel ions with lignin. By selecting an appropriate molar ratio of phytic acid to nickel and a mass ratio of nickel phytate to lignin, high dispersion of Ni2P is achieved while constructing a PCO defect structure. This enables efficient activation of water molecules and promotes water dissociation. It can be used to catalyze the preparation of sorbitol from cellulose and / or the extraction of residual lignin components. In particular, controlling the excess of phytic acid can generate more defect sites during high-temperature decomposition, thereby forming a richer pore structure. Attached Figure Description
[0017] Figure 1 The image shows a transmission electron microscope (TEM) image of the nickel-based catalyst CAT-1 prepared in Example 1.
[0018] Figure 2 Transmission electron microscopy (TEM) image of the nickel-based catalyst CAT-6 prepared in Comparative Example 1.
[0019] Figure 3 Transmission electron microscopy (TEM) image of the nickel-based catalyst CAT12 prepared in Comparative Example 7.
[0020] Figure 4 The XRD patterns are those of the nickel-based catalysts CAT-1, CAT-6, and CAT12 prepared in Example 1, Comparative Example 1, and Comparative Example 7. Detailed Implementation
[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0022] In one embodiment of the present invention, a nickel-based catalyst synthesized by a template-free method is provided, which has a PCO defect structure, wherein Ni2P nanoparticles are uniformly dispersed in phosphorus-doped porous carbon; the preparation method of the nickel-based catalyst specifically includes the following steps: S1. Extract lignin from agricultural and forestry waste using the existing alcohol-soluble method, and dry it for later use; S2. Under stirring at 10-20℃, solid phytic acid is dissolved in a solvent to obtain a phytic acid solution; nickel salt is dissolved in the same solvent to obtain a nickel salt solution; then, the nickel salt solution is slowly added dropwise to the phytic acid solution while stirring to obtain a nickel phytate solution; wherein, the molar ratio of phytic acid to nickel salt is 1:(0.5-2), and the amount of phytic acid is controlled to be in excess relative to nickel salt, so that phytic acid and nickel ions form an unsaturated complex; the mass of phytic acid accounts for 5%-10% of the total mass of the nickel phytate solution; the solvent is water and / or ethanol, preferably a mixed solvent of ethanol and water in a mass ratio of (6-8):(2-4); S3. Under stirring at 50-60℃, the above lignin is added to the same solvent and stirring is continued to obtain a lignin solution. Then, the above nickel phytate solution is slowly added dropwise to the lignin solution and stirred. The solution is then dried at 50-60℃ to obtain the catalyst precursor. The lignin accounts for 5%-10% of the total mass of the lignin solution. The mass ratio of nickel phytate solution to lignin solution is 1:(0.5-2). S4. The above catalyst precursor is heat-treated sequentially in an oxygen-containing atmosphere (such as air or oxygen) to 250-300℃, then switched to a flowing nitrogen atmosphere. After the oxygen-containing atmosphere is removed, it is switched to a flowing reducing atmosphere (such as hydrogen or a hydrogen-containing mixture). The temperature is then raised to 650-700℃ for reduction treatment under the reducing atmosphere, followed by nitrogen purging and cooling to room temperature to obtain a phosphorus-doped porous carbon-confined nickel-based catalyst; wherein the gas hourly space velocity is 60-80 h⁻¹. -1 .
[0023] Preferably, the nickel salt is one or more of nickel nitrate, nickel acetylacetonate, and nickel acetate; the agricultural and forestry waste includes, but is not limited to, one or more of tobacco stalks, castor stalks, beech wood chips, camellia shells, corn cobs, and walnut shells.
[0024] In another embodiment of the present invention, a method for preparing sorbitol using the above-mentioned nickel-based catalyst is also provided, specifically including the following steps: The above-mentioned nickel-based catalyst, cellulose and / or the remaining components of lignin extraction, and water are mixed and reacted at 150-210°C in a hydrogen atmosphere to obtain sorbitol.
[0025] This invention successfully prepared a phosphorus-doped carbon-confined nickel-based catalyst. The entire preparation process does not require the use of template agents such as P123 and F127, nor does it rely on activators such as acids and bases, which is significantly different from the traditional lignin porous carbon preparation method. Moreover, the phosphorus source selected in this invention is phytic acid, which avoids the operational hazards of using hypophosphite at high temperatures and the environmental hazards of releasing gases.
[0026] This invention strictly limits the molar ratio of phytic acid (PA) to nickel salt to ensure that phytic acid is always in excess. Phytic acid molecules can not only react with the hydroxyl groups in lignin, acting as a crosslinking agent, but also highly dispersedly complex nickel ions. During subsequent heat treatment and reduction processes, the high-temperature decomposition of phytic acid provides a phosphorus source, reacting with nickel to form nickel phosphide, and its own decomposition can also form defect-rich phosphorus-oxygen co-doped carbon (POC). Experiments have shown that the PCO defect structure in POC materials can efficiently activate water molecules and promote water dissociation. Controlling the excess of phytic acid aims to generate more defect sites during high-temperature decomposition, thereby forming a richer pore structure.
[0027] Specifically, since phytic acid molecules have a strong complexing ability, and each phytic acid molecule can complex up to six nickel ions, in the embodiments of the present invention, when preparing the nickel phytate solution, the nickel salt solution must be slowly added dropwise to the excess phytic acid solution. This operation aims to avoid the phytic acid and nickel ions reaching a completely saturated complexing state, so that the phytic acid is always in an unsaturated complexing state, thereby effectively inhibiting the aggregation of nickel ions, which is conducive to the formation of highly dispersed nickel phosphide and further promotes the formation of rich pore structures.
[0028] This invention also specifies a specific mass ratio of phytic acid solution to lignin solution to precisely control the amount of lignin used. Insufficient lignin will result in insufficient carbon content in the catalyst, affecting the dispersibility of nickel phosphide; while excessive lignin will cause an excess of carbon, leading to problems such as a decrease in the specific surface area of the catalyst, pore blockage, and coating of active sites of metallic nickel phosphide.
[0029] Furthermore, in this embodiment of the invention, the catalyst precursor is first subjected to low-temperature heat treatment in an oxygen-containing atmosphere to introduce more oxygen elements, which is beneficial to subsequent pore expansion and the formation of PCO defect structures. Then, it is subjected to reduction treatment in a reducing atmosphere at 650-700°C. If the reduction temperature is lower than 650°C, although nickel phosphide can still be generated, the carbon content is high at low temperatures, which easily covers the active sites of metallic nickel phosphide, thereby affecting the catalytic performance.
[0030] Example 1: This example provides a nickel-based catalyst synthesized using a template-free method. The preparation method specifically includes the following steps: S1. Lignin is extracted from tobacco straw using the existing alcohol-soluble method and then dried for later use. S2. Under stirring at 20°C, solid phytic acid is dissolved in a mixed solvent (ethanol and water mixed in a 7:3 mass ratio) to obtain a phytic acid solution; nickel nitrate is dissolved in the same mixed solvent (ethanol and water mixed in a 7:3 mass ratio) to obtain a nickel nitrate solution; then, the nickel nitrate solution is slowly added dropwise to the phytic acid solution while stirring for 1 hour to obtain a nickel phytate solution; wherein, the molar ratio of phytic acid to nickel nitrate is 1:2, and the mass of phytic acid accounts for 10% of the total mass of the nickel phytate solution; S3. Under stirring at 50°C, the above lignin was added to the same mixed solvent (ethanol and water mixed in a 7:3 mass ratio), and stirring was continued for 1 hour to obtain a lignin solution. Then, the above nickel phytate solution was slowly added dropwise to the lignin solution and stirred for 6 hours. After drying at 60°C, the catalyst precursor was obtained. The lignin accounted for 10% of the total mass of the lignin solution, and the mass ratio of the nickel phytate solution to the lignin solution was 1:1. S4. The above catalyst precursor was loaded into a tube furnace and heat-treated to 300°C for 3 hours under flowing air. Then, the flow was switched to nitrogen gas, and after the air was purged, it was switched to hydrogen gas. The temperature was then raised to 650°C for reduction treatment for 2 hours. Afterward, the temperature was lowered to room temperature by nitrogen purging to obtain a phosphorus-doped porous carbon-confined nickel-based catalyst, designated CAT-1. The gas hourly space velocity (GHSV) was 60 h⁻¹. -1 .
[0031] Example 2: The preparation steps of this example are basically the same as those of Example 1, except that the tobacco straw in step S1 is replaced with castor straw, and the resulting nickel-based catalyst is numbered CAT-2.
[0032] Example 3: The preparation steps of this example are basically the same as those of Example 1, except that the molar ratio of phytic acid to nickel nitrate in step S2 is changed to 1:0.5, and the resulting nickel-based catalyst is numbered CAT-3.
[0033] Example 4: The preparation steps of this example are basically the same as those of Example 1, except that the mass ratio of nickel phytate solution and lignin solution in step S3 is changed to 1:2, and the resulting nickel-based catalyst is numbered CAT-4.
[0034] Example 5: The preparation steps of this example are basically the same as those of Example 1, except that the lignin content in step S3 is changed from 10% to 5% of the total mass of the lignin solution, and the resulting nickel-based catalyst is numbered CAT-5.
[0035] Comparative Example 1: This example is intended to compare with Example 1 to illustrate the effect of adding F127 in step S3 on the nickel-based catalyst, as follows: The preparation steps of Comparative Example 1 are basically the same as those of Example 1, except that: after adding lignin to the mixed solvent in step S3, F127 is added and stirred for 1 hour; the resulting nickel-based catalyst is designated CAT-6.
[0036] Comparative Example 2: This example is intended to compare with Example 1 to illustrate the effect of adding phytic acid in step S2 on the nickel-based catalyst, as follows: The preparation steps of Comparative Example 2 are basically the same as those of Example 1, except that the step of dissolving phytic acid in the mixed solvent in step S2 is removed, and only the step of dissolving nickel nitrate in the mixed solvent is retained; the resulting nickel-based catalyst is numbered CAT-7.
[0037] Comparative Example 3: This example is intended to compare with Example 1 to illustrate the effect of phytic acid dosage on the nickel-based catalyst in step S2, as follows: The preparation steps of Comparative Example 3 are basically the same as those of Example 1, except that the molar ratio of phytic acid to nickel nitrate in step S2 is changed to 1:3; the resulting nickel-based catalyst is numbered CAT-8.
[0038] Comparative Example 4: This example is intended to compare with Example 1 to illustrate the effect of other phosphorus sources on the nickel-based catalyst in step S2, as follows: The preparation steps of Comparative Example 4 are basically the same as those of Example 1, except that the phytic acid in step S2 is replaced with diamine hydrogen phosphate, and the molar ratio with nickel nitrate is kept unchanged; the resulting nickel-based catalyst is numbered CAT-9.
[0039] Comparative Example 5: This example is intended to compare with Example 1 to illustrate the effect of the dropwise addition direction of nickel salt and phytic acid on the nickel-based catalyst in step S2, as follows: The preparation steps of Comparative Example 5 are basically the same as those of Example 1, except that in step S2, instead of slowly adding nickel nitrate solution to phytic acid solution to form nickel phytate solution, phytic acid solution is slowly added to nickel nitrate solution to form nickel phytate solution; the resulting nickel-based catalyst is numbered CAT-10.
[0040] Comparative Example 6: This example is intended to compare with Example 1 to illustrate the effect of lignin dosage on the catalyst in step S3, as follows: The preparation steps of Comparative Example 6 are basically the same as those of Example 1, except that the mass ratio of nickel phytate solution and lignin solution in step S3 is 1:5; the resulting nickel-based catalyst is numbered CAT-11.
[0041] Comparative Example 7: The purpose is to compare with Example 1 to illustrate the effect of low-temperature heat treatment in air in step S4 on the nickel-based catalyst, as follows: The preparation steps of Comparative Example 7 are basically the same as those of Example 1, except that the step of "heating to 300°C for 3 hours under flowing air" in step S4 is removed; the resulting nickel-based catalyst is numbered CAT-12.
[0042] Comparative Example 8: The purpose is to compare with Example 1 to illustrate the necessity of the hydrogen reduction step in step S4, as follows: The preparation steps of Comparative Example 8 are basically the same as those of Example 1, except that the step of "then switching to flowing nitrogen, and after the air is driven away, switching to flowing hydrogen, and continuing to heat to 650°C for reduction treatment for 2 hours" in step S4 is removed; the obtained nickel-based catalyst is numbered CAT-13.
[0043] Example 6: This example provides an application of the above-mentioned nickel-based catalyst in the reaction of cellulose to sorbitol. The specific method and conditions are as follows: 0.1 g of cellulose and nickel-based catalyst were added to a stainless steel needle valve reactor containing 30 mL of deionized water. After placing a magnetic spool and sealing the reactor, the air inside was purged with hydrogen. Then, 2 MPa of hydrogen was introduced and the reactor was sealed. The reactor was then heated to 210 °C with stirring and maintained for 3 h. After the reaction was completed, the reactor was allowed to cool naturally to room temperature. The product was detected by liquid chromatography and the yield of sorbitol was calculated.
[0044] Example 7: The application method and steps of this example are basically the same as those of Example 6, except that the nickel-based catalyst CAT-1 prepared in Example 1 is used, and cellulose is replaced with the remaining component after lignin extraction in step S1 of Example 1 while keeping the mass unchanged. The product is detected by liquid chromatography and the sorbitol yield is calculated. The sorbitol yield is 74.1%.
[0045] Following the method of Example 6, sorbitol was prepared using different nickel-based catalysts prepared above, and the yield of sorbitol was calculated. The results are shown in Table 1. Table 1
[0046] In addition, the transmission electron microscopy (TEM) images of catalysts CAT-1, CAT-6, and CAT12 prepared in Example 1, Comparative Example 1, and Comparative Example 7 are shown below. Figure 1 , Figure 2 , Figure 3 As shown. The XRD patterns of catalysts CAT-1, CAT-6, and CAT12 prepared in Example 1, Comparative Example 1, and Comparative Example 7 are shown in the figure. Figure 4 As shown. A comparison of Example 1 and Comparative Example 1 demonstrates that even without the addition of the F127 template agent, a highly dispersed Ni2P catalyst can still be obtained in the embodiments of the present invention, and the catalyst exhibits a higher yield for the preparation of sorbitol from cellulose. A comparison of Example 1 and Comparative Example 7 reveals the effect of low-temperature heat treatment in air in step S4 on the nickel-based catalyst. The catalyst without low-temperature heat treatment has excessive carbon covering more catalyst active sites, resulting in lower catalyst activity.
[0047] In summary, the preparation method provided by the embodiments of the present invention successfully prepared a highly dispersed, defect-rich nickel-based catalyst under conditions that do not require template agents, acid-base activators, or hazardous phosphorus sources, through the synergistic effect of phytic acid excess complexation, a specific dropwise order, air pre-oxidation, and hydrogen reduction. This nickel-based catalyst can significantly improve the yield of sorbitol in the one-step cellulose preparation of sorbitol reaction.
[0048] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.
Claims
1. A method for preparing nickel-based catalysts based on template-free synthesis, characterized in that, Includes the following steps: Phytic acid is dissolved in a solvent to obtain a phytic acid solution; The nickel salt is dissolved in a solvent to obtain a nickel salt solution; A nickel salt solution is added dropwise to a phytic acid solution while stirring, controlling the molar ratio of phytic acid to nickel salt at 1:(0.5-2), so that phytic acid and nickel ions form an unsaturated complex, yielding a nickel phytate solution; the mass of the phytic acid accounts for 5%-10% of the total mass of the nickel phytate solution; A nickel phytate solution and a lignin solution are mixed and dried to obtain a catalyst precursor; the lignin accounts for 5%-10% of the total mass of the lignin solution; the mass ratio of the nickel phytate solution to the lignin solution is 1:(0.5-2); The catalyst precursor was subjected to heat treatment in an oxygen-containing atmosphere and reduction treatment in a reducing atmosphere to obtain a phosphorus-doped porous carbon-confined nickel-based catalyst.
2. The method for preparing the nickel-based catalyst based on template-free synthesis according to claim 1, characterized in that, The phytic acid accounts for 5%-10% of the total mass of the nickel phytate solution; the nickel salt is one or more of nickel nitrate, nickel acetylacetone, and nickel acetate.
3. The method for preparing the nickel-based catalyst based on template-free synthesis according to claim 1, characterized in that, The solvent is water and / or ethanol.
4. The method for preparing the nickel-based catalyst based on template-free synthesis according to claim 1, characterized in that, The lignin is extracted from agricultural and forestry waste using an alcohol-soluble method; the agricultural and forestry waste includes one or more of tobacco stalks, castor stalks, beech wood chips, camellia shells, corn cobs, and walnut shells.
5. The method for preparing the nickel-based catalyst based on template-free synthesis according to claim 1, characterized in that, The method for mixing nickel phytate solution and lignin solution is as follows: Under stirring at 50-60℃, lignin is added to the solvent and stirring is continued to obtain a lignin solution. Then, nickel phytate solution is added dropwise to the lignin solution and stirred.
6. The method for preparing the nickel-based catalyst based on template-free synthesis according to claim 1, characterized in that, The oxygen-containing atmosphere is air or oxygen, and the heat treatment temperature is 250-300℃; the reducing atmosphere is hydrogen or a hydrogen-containing mixture, and the reduction treatment temperature is 650-700℃.
7. A nickel-based catalyst prepared by any one of claims 1-6, characterized in that, The nickel-based catalyst has a PCO defect structure, in which Ni2P nanoparticles are uniformly dispersed in phosphorus-doped porous carbon.
8. The application of the nickel-based catalyst as described in claim 7 in the catalytic preparation of sorbitol.
9. The application according to claim 8, characterized in that, The method for preparing sorbitol includes the following steps: The nickel-based catalyst, cellulose and / or the remaining components from lignin extraction, and water are mixed and reacted at 150-210°C in a hydrogen atmosphere to obtain sorbitol.