A method for synthesizing a highly dispersed catalytic combustion catalyst

Abstract

The application belongs to the technical field of organic liquid hydrogen storage and provides a high-dispersion catalytic combustion catalyst synthesis method, which comprises the following steps: carrier pretreatment, atomic layer deposition, liquid phase loading, drying, calcination and reduction. By coupling the atomic layer deposition technology and the liquid phase loading method, the self-limiting surface reaction characteristics of the atomic layer deposition are utilized to realize the atomic dispersion and accurate anchoring of the active components on the carrier surface, and then the active metal is further introduced through the liquid phase loading to form a catalyst with high dispersion and high stability. The catalyst prepared by the method has high dispersion of the active components, high utilization rate of the noble metal, good low-temperature activity, high high-temperature stability, low process cost, good reproducibility, is suitable for various complex carriers, and has a wide application prospect in the field of hydrogen catalytic combustion.

Description

Technical Field

[0001] This invention belongs to the field of organic liquid hydrogen storage and release technology, and particularly relates to a method for synthesizing a highly dispersed catalytic combustion catalyst. Background Technology

[0002] In recent years, researchers have been dedicated to developing novel structured catalytic systems. Among them, hydrogen catalytic combustion technology, with its advantages of mild reaction conditions, high energy conversion efficiency, and clean, pollution-free products, has become a research hotspot in the field of safe utilization and efficient energy conversion of hydrogen energy, showing broad application prospects in scenarios such as fuel cell system heating, hydrogen purification and deoxygenation, and exhaust gas treatment in hydrogen-related sites.

[0003] Currently, while noble metal-based catalytic combustion catalysts (such as Pt, Pd, and their alloys) exhibit excellent performance in terms of low-temperature activity and selectivity for hydrogen oxidation, their high cost and limited reserves make it difficult to meet the large-scale application requirements for long-term operation of hydrogen energy equipment. Existing non-noble metal catalysts generally suffer from problems such as a limited number of active sites, insufficient low-temperature activity, easy sintering of metal particles at high temperatures, limited activation capacity for hydrogen-oxygen mixtures, and stability degradation due to thermal sintering or hydrothermal aging during long-term operation. While atomic layer deposition (ALD) technology can achieve atomic-level film thickness control and uniform coating of complex support surfaces, playing a key role in inhibiting metal particle migration and agglomeration and enhancing thermal stability, it has limitations such as low growth rate, high precursor cost, and difficulty in large-scale preparation when preparing high-load, high-specific-surface-area catalyst layers. Conversely, wet chemical synthesis (such as impregnation, sol-gel, and hydrothermal methods) is simple, inexpensive, and easy to prepare in large quantities, enabling the introduction of high-load active components and the control of multi-level pore structure, but it has inherent defects in precise film thickness control, atomic-level dispersion of active sites, and uniform coverage of complex structure surfaces. Summary of the Invention

[0004] The purpose of this invention is to provide a method for synthesizing a highly dispersed catalytic combustion catalyst, thereby addressing the problems mentioned in the background section.

[0005] The present invention is implemented as follows: a method for synthesizing a highly dispersed catalytic combustion catalyst includes the following steps: Step 1: Pre-treat the vector; Step 2: Place the pretreated carrier into the deposition reactor and use atomic layer deposition to controllably deposit the active components on the carrier surface; Step 3: After removing the support obtained in Step 2, the active metal component is further loaded onto the support using a liquid phase loading method; Step 4: Dry the catalyst obtained in Step 3; Step 5: The catalyst obtained in Step 4 is subjected to calcination and reduction treatment.

[0006] In a further technical solution, in step 1, the carrier is one or more of α-alumina, γ-alumina, amorphous alumina, silicon carbide, silicon nitride, cerium dioxide, stainless steel, copper, and nickel. The carrier is in one or more of the following forms: 0.5-6mm spherical, Raschig ring, Pall ring, foam, honeycomb, powder, cylindrical, or irregular.

[0007] In a further technical solution, in step 1, the carrier pretreatment method is one or more of acid treatment, alkali treatment, oxide treatment, plasma treatment, and high temperature treatment.

[0008] In a further technical solution, in step 2, the precursor selected for atomic layer deposition is one or more of the following: platinum acetylacetonate, (methylcyclopentadienyl)trimethylplatinum, bis(cyclopentadienyl)nickel, bis(tert-butyldiazabutadienyl)nickel, bis(N,N-di-tert-butylacetamidinium)iron, carbonylnitrosoimidazolylphosphinecobalt, and copper acetylacetonate. The atomic layer deposition temperature is 200-300 ℃, and the deposition pressure is 0.01-200 kPa; the carrier gas is one or more of nitrogen, argon, and helium, with a carrier gas volume of 10-200 sccm, a precursor delivery volume of 5-100 sccm, a delivery time of 0.1-10 s, and a deposition time of 1-100 s; the purging nitrogen flow rate is 10-200 sccm, and the purging time is 1-100 s; the oxidizing gas is one or more of oxygen and ozone, with a delivery time of 0.1-10 s and a delivery flow rate of 10-200 sccm; and the cycle deposition time is 1-100 times.

[0009] In a further technical solution, in step 3, the liquid phase loading method is one or more of the following: saturated impregnation method, supersaturated impregnation method, ethylene glycol method, and sol-gel method, with a reaction temperature of 10-200 ℃. More specifically, the impregnation method and ethylene glycol method are used, with a reaction temperature of 100-180 ℃. The metal components supported by the liquid phase loading method are one or more of Pt, Ni, Co, Cu, Sn, W, Pd, and Fe.

[0010] In a further technical solution, in step 4, the drying method is one or more of natural drying, vacuum drying, and oven drying; the drying time is 1-18 hours; the drying temperature is 0-100 ℃; and the air velocity above is 0-300 m. 3 / h.

[0011] In a further technical solution, in step 5, the calcination environment is one or more of air, vacuum, chlorine, nitrogen, and argon, the calcination temperature is 200-800 ℃, and the calcination time is 1-24 h; the reducing gas composition is a mixture of 1%-100% hydrogen and one or more of nitrogen, argon, and chlorine, the reduction temperature is 200-800 ℃, and the reduction time is 1-24 h.

[0012] The present invention provides a method for synthesizing a highly dispersed catalytic combustion catalyst, the advantages of which are as follows: (1) This invention employs a coupled process of atomic layer deposition (ALD) technology and liquid-phase loading method. The ALD self-limiting surface reaction mechanism enables atomic-level dispersion and precise positioning of active metals on the support surface, forming isolated active sites or ultrafine nanoclusters with high specific surface area. Simultaneously, ALD pre-modification regulates the metal-support electronic interaction, optimizing the hydrogen adsorption and dissociation energy barrier. This structure-electron synergy allows the catalyst to achieve complete hydrogen conversion at temperatures below 100 °C, reducing the ignition temperature by 50-100 °C compared to traditional impregnation catalysts, while also reducing the amount of precious metals used by 30%-50%, significantly improving atom utilization.

[0013] (2) The sub-nanometer oxide coating or spatially confined structure constructed by the ALD process effectively anchors the active metal and inhibits migration and agglomeration under high-temperature conditions. Combined with the core-shell structure or alloy phase formed by subsequent controllable heat treatment, the catalyst maintains its narrow particle size distribution and stable specific surface area even after long-term operation above 600 °C. In addition, ALD achieves precise control of film thickness and metal loading (error < ±5%) based on the digital deposition mechanism of cycle number, eliminating the dependence of traditional methods on empirical parameters such as solution concentration and impregnation time. The catalysts of different batches have high reproducibility of activity, meeting the quality stability requirements of large-scale industrial production.

[0014] (3) This method is applicable to various materials such as oxides, non-oxides, and metals, as well as complex geometric carriers such as foams, honeycomb, and irregular structures, breaking through the bottleneck of large pressure drop and limited mass transfer of powder catalysts; the integrated structured catalyst can be directly filled into the reactor without secondary molding, simplifying the process flow. The synergistic design of high thermal conductivity carrier and uniformly dispersed active sites realizes rapid heat removal and spatial uniform distribution of reaction heat, eliminates local hot spots and runaway temperature risks, ensures the inherent safety of the device, and adapts to the modular integration requirements of distributed energy systems. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a method for synthesizing a highly dispersed catalytic combustion catalyst according to an embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0017] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0018] like Figure 1 The diagram illustrates a method for synthesizing a highly dispersed catalytic combustion catalyst according to an embodiment of the present invention. This method achieves high dispersion and anchoring of active metals on the surface of a complex-structured support through a coupled process of atomic layer deposition and liquid-phase loading. The resulting catalyst exhibits high activity at low temperatures, high thermal stability, and high atomic utilization. The loading amount is precisely controllable, the support has wide adaptability, and it can be directly loaded into the reactor, simplifying the process and enhancing mass and heat transfer. It is suitable for the efficient and safe conversion of hydrogen catalytic combustion. The specific steps include: Step 1: Pre-treat the vector; Step 2: Place the pretreated carrier into the deposition reactor and use atomic layer deposition to controllably deposit the active components on the carrier surface; Step 3: After removing the support obtained in Step 2, the active metal component is further loaded onto the support using a liquid phase loading method; Step 4: Dry the catalyst obtained in Step 3; Step 5: The catalyst obtained in Step 4 is subjected to calcination and reduction treatment.

[0019] In a preferred embodiment of the present invention, in step 1, the carrier is one or more of α-alumina, γ-alumina, amorphous alumina, silicon carbide, silicon nitride, cerium dioxide, stainless steel, copper, and nickel; in a further embodiment, it is one or more of α-alumina, γ-alumina, amorphous alumina, silicon carbide, and silicon nitride.

[0020] In a preferred embodiment of the present invention, in step 1, the carrier is one or more of the following: 0.5-6mm spherical, Raschig ring, Pall ring, foam, honeycomb, powder, cylindrical, and irregular shape; more specifically, it is one or more of the following: 0.5-6mm spherical, Raschig ring, Pall ring, foam, honeycomb, and cylindrical shape.

[0021] In a preferred embodiment of the present invention, in step 1, the pretreatment of the carrier is one or more of acid treatment, alkali treatment, oxide treatment, plasma treatment, and high temperature treatment; more specifically, it is one or more of acid treatment, alkali treatment, oxide treatment, and plasma treatment.

[0022] In a preferred embodiment of the present invention, in step 2, the precursor selected for atomic layer deposition is one or more of the following: platinum acetylacetonate, (methylcyclopentadienyl)trimethylplatinum, bis(cyclopentadienyl)nickel, bis(tert-butyldiazabutadienyl)nickel, bis(N,N-di-tert-butylacetamidinium)iron, carbonylnitrosoimidazolylphosphinecobalt, and copper acetylacetonate.

[0023] In a preferred embodiment of the present invention, in step 2, the atomic layer deposition temperature is 200-300 ℃, the deposition pressure is 0.01-200 kPa; the carrier gas is one or more of nitrogen, argon, and helium, the carrier gas volume is 10-200 sccm, the precursor delivery volume is 5-100 sccm, the delivery time is 0.1-10 s, and the deposition time is 1-100 s; the purging nitrogen flow rate is 10-200 sccm, and the purging time is 1-100 s; the oxidizing gas is one or more of oxygen and ozone, the delivery time is 0.1-10 s, and the delivery flow rate is 10-200 sccm; the cyclic deposition time is 1-100 times.

[0024] In a preferred embodiment of the present invention, in step 3, the liquid phase loading method is one or more of the following: saturated impregnation method, supersaturated impregnation method, ethylene glycol method, and sol-gel method, and the reaction temperature is 10-200 ℃. More specifically, the impregnation method or ethylene glycol method is used, and the reaction temperature is 100-180 ℃.

[0025] In a preferred embodiment of the present invention, in step 3, the metal component loaded by the liquid phase loading method is one or more of Pt, Ni, Co, Cu, Sn, W, Pd, and Fe.

[0026] In a preferred embodiment of the present invention, in step 4, the drying method is one or more of natural drying, vacuum drying, and oven drying; the drying time is 1-18 hours; the drying temperature is 0-100 ℃; and the overhead air velocity is 0-300 m / s. 3 / h; In a further embodiment, the drying method is one or more of natural drying, vacuum drying, and oven drying, the drying time is 1-12 h, the drying temperature is 0-80 ℃, and the air velocity above is 0-300 m. 3 / h.

[0027] In a preferred embodiment of the present invention, in step 5, the calcination environment is one or more of air, vacuum, chlorine, nitrogen, and argon, the calcination temperature is 200-800 ℃, and the calcination time is 1-24 h; the reducing gas composition is a mixture of 1%-100% hydrogen and one or more of nitrogen, argon, and chlorine, the reduction temperature is 200-800 ℃, and the reduction time is 1-24 h.

[0028] The following are several specific examples used to verify the reaction performance of the catalyst prepared by this method: Example 1: 20 g of 2 mm spherical γ-Al₂O₃ support was placed in the ALD reaction chamber and pretreated with nitrogen purging at 200℃ and 0.1 kPa for 30 min. Using platinum acetylacetone as the precursor, the deposition temperature was controlled at 250℃, the deposition pressure at 1 kPa, the carrier gas nitrogen flow rate at 50 sccm, the precursor pulse time at 2 s, the purging time at 10 s, and the oxidizing gas oxygen pulse time at 2 s. After 50 cycles of deposition, an ALD-Pt / Al₂O₃ precursor with a Pt loading of 0.5 wt% was obtained.

[0029] The above precursor was placed in 40.2 ml of ethylene glycol solution, and 1.5 g of nickel nitrate was added. The reaction temperature was controlled at 150 °C, and the mixture was stirred and refluxed for 4 h to achieve liquid-phase loading of Ni. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, and the resulting solid was dried under vacuum at 80 °C for 12 h with a gas flow rate controlled at 100 m³ / h. 3 / h. It was then placed in a tube furnace and calcined at 500 °C for 4 h in an air atmosphere, and then reduced at 400 °C for 4 h with a 10% hydrogen / nitrogen mixture to obtain a Pt-Ni bimetallic catalyst, which is recorded as Example 1.

[0030] Example 2: A SiC foam carrier with a pore density of 20 ppi was cut into cylinders of Φ20 mm × 10 mm, acid-washed with 10% nitric acid solution at 60 °C for 2 h, washed with deionized water until neutral, and then dried. The pretreated SiC foam was placed in an ALD reaction chamber, using (methylcyclopentadienyl)trimethylplatinum as a precursor, at a deposition temperature of 280 °C, a deposition pressure of 0.5 kPa, and an argon carrier gas flow rate of 80 sccm, for 30 cycles of deposition to form an ultrathin PtO layer on the SiC surface. x Modification layer.

[0031] The ALD-modified carrier was immersed in a saturated impregnation solution containing 3.0 g of cobalt nitrate at a controlled impregnation temperature of 60 °C for 2 h. After removal, the carrier was drained and centrifuged at 1000 rpm for 2 min to remove residual liquid phase from the surface. It was then dried in an oven at 60 °C for 18 h with an air flow rate of 200 m / s. 3 / h. After drying, the sample was calcined at 600 °C for 3 h under nitrogen protection, and then reduced at 350 °C for 6 h with a 5% hydrogen / argon mixture to obtain the Pt-Co / SiC catalyst, which is recorded as Example 2.

[0032] Example 3: 50 g of a 400 cpsi honeycomb α-Al₂O₃ support was placed in an ALD reaction chamber after plasma treatment for 10 min. In the first stage, di(cyclopentadienyl)nickel was used as the precursor, with a deposition temperature of 220 °C, a deposition pressure of 0.01 kPa, and a carrier gas nitrogen flow rate of 100 sccm. The deposition was repeated 20 times to form NiO nanoisland anchoring points. In the second stage, the precursor was switched to platinum acetylacetonate, and the deposition was repeated 40 times at the same temperature and pressure to achieve selective growth of Pt at NiO sites.

[0033] The ALD-treated support was placed in a sol-gel solution containing 0.8 g of copper acetylacetonate, and the reaction temperature was controlled at 120 °C for 12 h. After gelation, it was freeze-dried under vacuum at -40 °C for 24 h, then calcined at 400 °C for 6 h under an argon atmosphere, and then reduced at 300 °C for 8 h with a 20% hydrogen / nitrogen mixture to obtain a Ni-Pt-Cu ternary catalyst, which is referred to as Example 3.

[0034] Example 4: 30 g of Φ5 mm × 5 mm Pall ring γ-Al2O3 support was treated with 10% oxalic acid solution at 70 ℃ for 3 h, washed with deionized water until neutral, and dried at 120 ℃. The pretreated support was placed in the ALD reaction chamber, using di(tert-butyldiazabutadiene)nickel as the precursor, at a deposition temperature of 260 ℃, a deposition pressure of 5 kPa, a carrier gas helium flow rate of 120 sccm, a precursor pulse time of 3 s, and a purge nitrogen flow rate of 150 sccm for 15 s. The deposition cycle was repeated 25 times to form a NiO seed layer.

[0035] Switching to copper acetylacetone precursor, and under the same deposition temperature and pressure, the carrier gas was changed to a nitrogen / argon mixture (volume ratio 1:1) at a flow rate of 100 sccm, and cyclic deposition was performed 35 times to achieve selective coating of Cu at NiO sites. The ALD-treated support was immersed in a supersaturated impregnation solution containing 0.6 g of palladium nitrate, with the impregnation temperature controlled at 25 °C and the impregnation time at 30 min, followed by ultrasonic-assisted dispersion for 10 min. After removal, it was allowed to drain naturally and then placed in a vacuum drying oven at 40 °C for 24 h, maintaining a vacuum of 0.01 MPa.

[0036] After drying, the sample was placed in a tube furnace and calcined at 450 °C for 5 h in a chlorine / nitrogen mixed gas atmosphere (volume ratio 5:95). Then it was reduced at 500 °C for 3 h with a 50% hydrogen / nitrogen mixed gas to obtain the Pd-Cu-Ni / Al2O3 catalyst, which is recorded as Example 4.

[0037] Comparative Example 1: 2.45 g of chloroplatinic acid and 1.04 g of nickel nitrate were dissolved in 24.4 g of deionized water. 0.23 g of oxalic acid was added as a competitive adsorbent, and the pH was adjusted to 3 with sodium hydroxide. The mixture was stirred to form a homogeneous impregnation solution. 20 g of 2 mm spherical γ-Al₂O₃ support was placed in a porous container, immersed in the above solution for 1 min, and then quickly removed and placed in a draining basket for centrifugation at 1000 rpm for 2 min. Subsequently, it was dried in an oven at 60 ℃ for 12 h with an air flow rate of 200 m³ / h. 3 / h; After drying, the sample was reduced in a tube furnace with a 5% hydrogen / nitrogen mixture at 300 °C for 4 h to obtain a Pt-Ni / Al2O3 catalyst, which is designated as Comparative Example 1.

[0038] Comparative Example 2: 20 g of 2 mm spherical γ-Al₂O₃ support was pretreated with nitrogen at 200 °C, and ALD deposition was performed using platinum acetylacetone as the precursor only. The deposition temperature was 250 °C, the deposition pressure was 1 kPa, the carrier gas nitrogen flow rate was 50 sccm, the precursor pulse time was 2 s, the purging time was 10 s, the oxygen pulse time was 2 s, and the deposition cycle was repeated 150 times to achieve the target Pt loading (1.5 wt%). After deposition, the sample was calcined in air at 400 °C for 2 h and reduced with 5% hydrogen / nitrogen at 300 °C for 4 h to obtain the Pt / Al₂O₃ catalyst, which was designated as Comparative Example 2.

[0039] Table 1

[0040] The catalysts prepared in Examples 1-4 and Comparative Examples 1-2 were tested for catalytic performance. The results are shown in Table 1. It can be seen that the catalyst synthesized by the ALD+ wet method has a lower ignition temperature, indicating that it has higher reactivity. It still has high activity at low temperatures and the conversion rate is close to 100%. In contrast, the catalyst synthesized by the impregnation method has a higher ignition temperature and insufficient conversion rate, which proves the superiority of the ALD+ wet method.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for synthesizing a highly dispersed catalytic combustion catalyst, characterized in that, Includes the following steps: Step 1: Pre-treat the vector; Step 2: Place the pretreated carrier into the deposition reactor and use atomic layer deposition to controllably deposit the active components on the carrier surface; Step 3: After removing the support obtained in Step 2, the active metal component is further loaded onto the support using a liquid phase loading method; Step 4: Dry the catalyst obtained in Step 3; Step 5: The catalyst obtained in Step 4 is subjected to calcination and reduction treatment.

2. The method for synthesizing a highly dispersed catalytic combustion catalyst according to claim 1, characterized in that, In step 1, the carrier is one or more of α-alumina, γ-alumina, amorphous alumina, silicon carbide, silicon nitride, cerium dioxide, stainless steel, copper, and nickel. The carrier is in one or more of the following forms: 0.5-6mm spherical, Raschig ring, Pall ring, foam, honeycomb, powder, cylindrical, or irregular.

3. The method for synthesizing a highly dispersed catalytic combustion catalyst according to claim 1, characterized in that, In step 1, the carrier pretreatment method is one or more of the following: acid treatment, alkali treatment, oxide treatment, plasma treatment, and high temperature treatment.

4. The method for synthesizing a highly dispersed catalytic combustion catalyst according to claim 1, characterized in that, In step 2, the precursor selected for atomic layer deposition is one or more of the following: platinum acetylacetonate, (methylcyclopentadienyl)trimethylplatinum, bis(cyclopentadienyl)nickel, bis(tert-butyldiazabutadienyl)nickel, bis(N,N-di-tert-butylacetamidinium)iron, carbonylnitrosoimidazolylphosphinecobalt, and copper acetylacetonate.

5. The method for synthesizing a highly dispersed catalytic combustion catalyst according to claim 1, characterized in that, In step 2, the atomic layer deposition temperature is 200-300 ℃, the deposition pressure is 0.01-200 kPa; the carrier gas is one or more of nitrogen, argon, and helium, the carrier gas volume is 10-200 sccm, the precursor delivery volume is 5-100 sccm, the delivery time is 0.1-10 s, and the deposition time is 1-100 s; the purging nitrogen flow rate is 10-200 sccm, and the purging time is 1-100 s; the oxidizing gas is one or more of oxygen and ozone, the delivery time is 0.1-10 s, and the delivery flow rate is 10-200 sccm; the cycle deposition time is 1-100 times.

6. The method for synthesizing a highly dispersed catalytic combustion catalyst according to claim 1, characterized in that, In step 3, the liquid phase loading method is one or more of the following: saturated impregnation method, supersaturated impregnation method, ethylene glycol method, and sol-gel method, and the reaction temperature is 10-200 ℃. The loaded metal components are one or more of Pt, Ni, Co, Cu, Sn, W, Pd, and Fe.

7. The method for synthesizing a highly dispersed catalytic combustion catalyst according to claim 1, characterized in that, In step 4, the drying method is one or more of natural drying, vacuum drying, and oven drying; the drying time is 1-18 hours; the drying temperature is 0-100 ℃; and the air velocity above is 0-300 m. 3 / h.

8. The method for synthesizing a highly dispersed catalytic combustion catalyst according to claim 1, characterized in that, In step 5, the calcination environment is one or more of air, vacuum, chlorine, nitrogen, and argon, the calcination temperature is 200-800 ℃, and the calcination time is 1-24 h; the reducing gas composition is a mixture of 1%-100% hydrogen and one or more of nitrogen, argon, and chlorine, the reduction temperature is 200-800 ℃, and the reduction time is 1-24 h.

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