A praseodymium-doped ceria-zirconia supported nickel-cobalt-copper trimetallic catalyst, a preparation method and application thereof

Abstract

This invention discloses a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst, its preparation method, and its application, belonging to the field of catalytic materials and hydrogen energy utilization technology. The catalyst disclosed in this invention uses a praseodymium-doped cerium oxide-zirconia composite oxide as a support, with nickel, cobalt, and copper as active components. By introducing praseodymium into the cerium oxide-zirconia composite support, this invention can regulate the defect structure of the support, improve oxygen vacancy concentration, oxygen migration capacity, and oxygen storage and release performance, and enhance the interaction between the support and the active metals. Simultaneously, the nickel, cobalt, and copper trimetallic components form a synergistic effect, which is beneficial to improving the activation capacity of ethanol molecules, the activation capacity of water molecules, and the conversion efficiency of surface intermediate species, thereby enhancing the catalytic performance of the ethanol steam reforming hydrogen production reaction. Under reaction conditions of 550 °C, this catalyst can achieve 100% ethanol conversion and 98.9% hydrogen yield, exhibiting high catalytic activity.

Description

Technical Field

[0001] This invention relates to the field of catalytic materials and hydrogen energy utilization technology, and more specifically to a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst, its preparation method, and its application in the ethanol steam reforming hydrogen production reaction. Background Technology

[0002] Hydrogen, as a clean and efficient secondary energy source, has broad application prospects in fuel cells, green chemical engineering, and distributed energy systems. Currently, there are many methods for hydrogen production, among which ethanol steam reforming is considered one of the more promising hydrogen production routes due to the wide availability of ethanol, ease of storage and transportation, low toxicity, and its availability via biomass.

[0003] The ethanol steam reforming process is complex, involving multiple continuous or parallel steps such as ethanol dehydrogenation, C / C bond breaking, water-gas shift reaction, and byproduct reforming. The composition, structure, and metal-support interactions of the catalyst have a significant impact on ethanol conversion, hydrogen yield, carbon deposition tendency, and catalytic lifetime.

[0004] While precious metal catalysts possess good low-temperature activity and resistance to carbon deposition, their high cost limits their large-scale application. Non-precious metal catalysts, especially nickel-based catalysts, have attracted widespread attention due to their low cost and high activity; however, traditional nickel-based catalysts still suffer from problems such as easy sintering, easy carbon deposition, and insufficient stability in ethanol reforming. Therefore, developing a praseodymium-doped cerium oxide-zirconia-supported nickel-cobalt-copper trimetallic catalyst with a rational structure, high activity, high hydrogen yield, and good resistance to carbon deposition is of great significance for promoting the development of ethanol steam reforming hydrogen production technology.

[0005] Therefore, providing a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst, its preparation method, and its application is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst, its preparation method and application, which solves the problems of insufficient activity, low hydrogen yield, easy carbon deposition and poor stability of existing ethanol steam reforming catalysts, and applies it to the ethanol steam reforming hydrogen production reaction to achieve a higher ethanol conversion rate and hydrogen yield.

[0007] The introduction of cobalt helps improve the activation of ethanol molecules and the conversion behavior of intermediate products, while the introduction of copper helps regulate the electronic structure and dispersion state of the metal surface, reducing the tendency for side reactions. Cerium oxide-zirconia composite oxide has good oxygen storage, oxygen release and oxygen migration performance, making it a high-performance catalytic support. Further doping with the rare earth element praseodymium further regulates the defect structure of the support, increases the number of oxygen vacancies, and enhances the metal-support interaction, thereby improving the catalyst activity and stability.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst, wherein the catalyst comprises a support and an active component supported on the support; the mass ratio of the support to the active component is 9:1; The support is a praseodymium-doped cerium oxide-zirconia composite oxide; the molar ratio of cerium, zirconium, and praseodymium in the support is 27:9:4; The active components are three metals: nickel, cobalt, and copper; the molar ratio of nickel, cobalt, and copper is 7:2:1.

[0010] Furthermore, the precursors for nickel, cobalt, and copper are nickel nitrate, cobalt nitrate, and copper nitrate, respectively.

[0011] Furthermore, a method for preparing a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst includes the following steps: (1) Dissolve cerium nitrate, zirconium nitrate and praseodymium nitrate in deionized water according to a set ratio to obtain a mixed salt solution; (2) Add an oxidizing precipitant to the mixed salt solution to cause co-precipitation and obtain a precipitate; after aging, filtering, washing, drying, grinding and calcining, the precipitate is obtained as praseodymium-doped cerium oxide-zirconia composite oxide. (3) Add nickel nitrate, cobalt nitrate and copper nitrate to deionized water to prepare an impregnation solution, and contact the praseodymium-doped cerium oxide-zirconia composite oxide for impregnation and stir for 12 hours to make it fully mixed; (4) After stirring, the mixture is placed directly into the oven for drying (the water in the impregnation liquid is removed by continuous heating and evaporation). The dried product is ground into powder and then calcined to obtain the precursor of praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst. (5) The catalyst precursor is reduced under a reducing atmosphere to obtain a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst.

[0012] Furthermore, the oxidizing precipitant in step (2) is a mixed aqueous solution of hydrogen peroxide and ammonia; the volume ratio of hydrogen peroxide, ammonia and deionized water is 1:4:5; and the pH of the precipitation endpoint is 10.

[0013] Furthermore, in step (2), the aging temperature is 70℃ and the aging time is 1h; the drying temperature is 80℃ and the drying time is 12h; the calcination temperature is 600℃ and the calcination time is 4h.

[0014] Furthermore, the drying temperature in step (4) is 80°C and the drying time is 12h; the calcination temperature is 600°C and the calcination time is 4h.

[0015] Furthermore, the reducing atmosphere in step (5) is a mixture of 10% hydrogen and 90% nitrogen; the reduction temperature is 600℃ and the reduction time is 1h.

[0016] Furthermore, the application of the praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst in the ethanol steam reforming hydrogen production reaction.

[0017] Praseodymium doping enhances the oxygen vacancy concentration and oxygen migration capacity of the support, while the synergistic effect among nickel, cobalt, and copper improves the activation capacity of ethanol molecules, the activation capacity of water molecules, and the conversion efficiency of surface intermediate species, thereby enhancing the ethanol reforming hydrogen production performance of the catalyst.

[0018] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst, its preparation method, and its application, which has the following beneficial effects: 1. The use of praseodymium-doped cerium oxide-zirconia composite support can effectively control the defect structure of the support, increase the number of oxygen vacancies and oxygen storage and release capacity, which is conducive to promoting the oxidation and removal of carbon-containing intermediate species on the surface during the reaction process and reducing carbon deposition; 2. The introduction of nickel, cobalt, and copper trimetallic active components can form a synergistic effect in the activation of ethanol molecules, the breaking of C-C bonds, the activation of water molecules, and the conversion of intermediate products, thereby improving the ethanol conversion rate and hydrogen yield; 3. There is a strong interaction between the composite support and the trimetallic active components, which is conducive to improving the dispersion of active metals and inhibiting particle sintering under high temperature conditions; 4. Under the conditions of ethanol steam reforming reaction at 550 ℃, the ethanol conversion rate reaches 100% and the hydrogen yield reaches 98.9%, which has high catalytic activity; 5. The preparation process is relatively simple and the raw material cost is low, making it suitable for application in the reforming of bioethanol to produce hydrogen. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is the XRD pattern of the catalyst of the present invention.

[0021] Figure 2 The image shows the XRD pattern of cerium oxide. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 A method for preparing a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst includes the following steps: (1) Preparation of praseodymium-doped cerium oxide-zirconia composite support 1.61 g of cerium nitrate, 0.53 g of zirconium nitrate, and 0.28 g of praseodymium nitrate were dissolved in 50 mL of deionized water to prepare a mixed salt solution. A mixed aqueous solution of hydrogen peroxide and ammonia (volume ratio of hydrogen peroxide, ammonia, and deionized water 1:4:5) was added dropwise to this mixed salt solution, controlling the pH to 10, and the solution was aged at 70 °C for 1 h. The resulting precipitate was filtered, washed, and dried at 80 °C for 12 h. After complete drying, the catalyst was ground into powder and then calcined at 600 °C for 4 h to obtain praseodymium-doped cerium oxide-zirconia composite oxide.

[0024] (2) Preparation of nickel-cobalt-copper trimetallic catalysts 0.35 g of nickel nitrate, 0.10 g of cobalt nitrate, and 0.04 g of copper nitrate were dissolved in 30 mL of deionized water to prepare an impregnation solution. The impregnation solution was loaded onto praseodymium-doped cerium oxide-zirconia composite oxide using an impregnation method. After stirring for 12 h, the mixture was directly placed in an oven and dried at 80 °C for 12 h. The dried product was ground into powder and calcined at 600 °C for 4 h to obtain the catalyst precursor. The obtained catalyst precursor was then reduced at 600 °C for 1 h in a mixed atmosphere of 10% hydrogen and 90% nitrogen to obtain the catalyst.

[0025] The XRD pattern of the catalyst is shown in the figure. Figure 1 The XRD pattern of cerium oxide is shown in [reference needed]. Figure 2 .

[0026] X-ray diffraction (XRD) results show that the catalyst of this invention exhibits distinct diffraction peaks near 2θ of 28.6°, 33.1°, 47.5°, 56.3°, 59.1°, 69.4°, 76.7°, and 79.1°, corresponding to the (111), (200), (220), (311), (222), (400), (331), and (420) crystal planes of cubic fluorite-structured cerium oxide, respectively. This result indicates that after introducing Zr and Pr and loading Ni, Co, and Cu, the catalyst still maintains the CeO2-based fluorite crystal framework structure. Meanwhile, no distinct independent diffraction peaks for NiO, Co oxides, CuO, ZrO2, or Pr oxide impurities are observed in the spectra, indicating that Zr and Pr have entered the CeO2 lattice to form a stable composite oxide structure, while the active components Ni, Co, and Cu are highly dispersed on the surface of the composite support or exist in the form of small grains. The above results demonstrate that the catalyst prepared by this invention is not a simple mechanical mixture, but a multi-component composite catalytic system with a stable structure and high dispersion of active components.

[0027] Example 2 Catalyst Performance Evaluation The catalyst prepared in Example 1 was loaded into a fixed-bed reactor at a loading rate of 6 g and evaluated under ethanol steam reforming conditions. The reactants were ethanol and water, with a water-to-ethanol molar ratio of 12:1. The liquid feed rate was 3.72 mL / h, nitrogen was used as the carrier gas, and the reaction temperature was 550 °C. The reaction products were analyzed online, and the ethanol conversion rate and hydrogen yield were calculated. The test results showed that at 550 °C, after the reaction reached stability, the catalyst achieved a 100% ethanol conversion rate and a 98.9% hydrogen yield, indicating that the prepared catalyst has high hydrogen production performance from ethanol steam reforming.

[0028] Formula for calculating ethanol conversion rate:

[0029] Among them, X EtOH,in n represents the conversion rate of ethanol. EtOH,in n represents the amount of ethanol that participates in the reaction. EtOH,out This represents the amount of ethanol remaining after the reaction.

[0030] Hydrogen yield calculation formula: Theoretically, each molecule of ethanol can produce a maximum of six molecules of hydrogen gas, so the hydrogen yield should be the actual hydrogen production ( n H2 (unit: mol / min) and six times the ethanol feed rate ( n E The ratio of (unit: mol / min) is:

[0031] In the formula, n E It can be directly based on the actual ethanol-water solution feed rate (L) E (unit: mL / min), solution density (ρ) E (unit: g / mL) and ethanol concentration x E calculate:

[0032] n H2 Based on the real-time measured hydrogen flow rate (G) in the reaction tail gas H2 Calculate (unit: mL / min):

[0033] During the experiment, nitrogen gas (G) was introduced using a mass flow controller. N2 (Unit: mL / min); the gas composition in the exhaust gas was analyzed using gas chromatography. G H2 Alternatively, it can be based on the hydrogen concentration x in the exhaust gas. H2 Nitrogen concentration x N2 Direct conversion:

[0034] In this invention, the praseodymium-doped cerium oxide-zirconia composite support can improve the defect structure and oxygen migration performance of the support, providing a favorable interfacial environment for the ethanol reforming reaction; at the same time, the synergistic effect of nickel, cobalt and copper is beneficial to improving the dispersion and reactivity of the active components, thereby achieving a higher ethanol conversion rate and hydrogen yield.

[0035] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst, characterized in that, The catalyst contains a support and an active component supported on the support; the mass ratio of the support to the active component is 9:

1. The support is a praseodymium-doped cerium oxide-zirconia composite oxide; the molar ratio of cerium, zirconium, and praseodymium in the support is 27:9:4; The active components are three metals: nickel, cobalt, and copper; the molar ratio of nickel, cobalt, and copper is 7:2:

1.

2. The praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst according to claim 1, characterized in that, The precursors for nickel, cobalt, and copper are nickel nitrate, cobalt nitrate, and copper nitrate, respectively.

3. The method for preparing a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst according to claim 2, characterized in that, Includes the following steps: (1) Dissolve cerium nitrate, zirconium nitrate and praseodymium nitrate in deionized water according to a set ratio to obtain a mixed salt solution; (2) An oxidizing precipitant is added to the mixed salt solution to obtain a precipitate; The precipitate was aged, filtered, washed, dried, ground and calcined to obtain praseodymium-doped cerium oxide-zirconia composite oxide; (3) Add nickel nitrate, cobalt nitrate and copper nitrate to deionized water to prepare an impregnation solution, and contact the praseodymium-doped cerium oxide-zirconia composite oxide for impregnation and stir for 12 hours to make it fully mixed; (4) After stirring, the mixture is placed directly into an oven for drying. The dried product is ground into powder and then calcined to obtain a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst precursor. (5) The catalyst precursor is reduced under a reducing atmosphere to obtain a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst.

4. The method for preparing a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst according to claim 3, characterized in that, The oxidizing precipitant in step (2) is a mixed aqueous solution of hydrogen peroxide and ammonia; the volume ratio of hydrogen peroxide, ammonia and deionized water is 1:4:5; the pH of the precipitation endpoint is 10.

5. The method for preparing a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst according to claim 3, characterized in that, The aging temperature in step (2) is 70℃ and the aging time is 1h; the drying temperature is 80℃ and the drying time is 12h; the calcination temperature is 600℃ and the calcination time is 4h.

6. The method for preparing a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst according to claim 3, characterized in that, The drying temperature in step (4) is 80℃ and the drying time is 12h; the calcination temperature is 600℃ and the calcination time is 4h.

7. The method for preparing a praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst according to claim 3, characterized in that, The reducing atmosphere in step (5) is a mixture of 10% hydrogen and 90% nitrogen; the reduction temperature is 600℃ and the reduction time is 1h.

8. The application of the praseodymium-doped cerium oxide-zirconia supported nickel-cobalt-copper trimetallic catalyst as described in claim 1 or 2 in the hydrogen production reaction of ethanol steam reforming.

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