Precious metal catalyst, activation method thereof and methanol-to-hydrogen system

Abstract

The invention provides a noble metal catalyst, an activation method thereof and a methanol-to-hydrogen system, and the activation method comprises the following steps: a pre-activation step, a preliminary activation step and a deep activation step. The problems of structure collapse, insufficient formation of active sites, difficulty in byproduct control and the like in the activation process of a noble metal catalyst in the prior art are successfully solved, the methanol conversion rate is improved, the CO content is reduced, the industrial requirement on high conversion rate is met, the generation of byproducts is effectively controlled, the purity and production efficiency of hydrogen are improved, and the production cost is reduced. The service life of the noble metal catalyst is prolonged.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a noble metal catalyst and its activation method, and a methanol-to-hydrogen system. Background Technology

[0002] Noble metal catalysts play an irreplaceable role in chemical, energy, and environmental protection fields due to their excellent catalytic activity, selectivity, and stability. For example, in the methanol reforming process for hydrogen production, noble metal catalysts can efficiently convert methanol into hydrogen (noble metal catalysts generally have a higher CO content than Cu-based catalysts), thus meeting the demand for high-purity hydrogen in industries such as fuel cells and ammonia synthesis. Before use, supported metal catalysts generally require activation, i.e., a reduction process, to reduce the active metal component from its oxidized state to an activated state capable of adsorbing and dissociating hydrogen. Therefore, the activation method directly affects the catalyst's performance, namely its activity, selectivity, and stability.

[0003] Traditional activation methods for precious metal catalysts typically employ gas-phase reduction using reducing gases such as H2 / N2 mixtures. However, single reduction conditions (e.g., fixed temperature, reducing agent dosage, and space velocity) present the following problems: Structural collapse risk: Under high temperature and strong reduction conditions, the reduction rate of the catalyst support (such as oxides) is too fast, which leads to the collapse of the support structure, and the active sites are covered or destroyed, thereby reducing the long-term stability of the catalyst.

[0004] Insufficient formation of active sites: Single reduction conditions are insufficient to take into account the differences in reduction kinetics of various components in the catalyst, resulting in some metals or supports not being fully reduced, and an insufficient number of active sites, which affects the initial activity and selectivity of the catalyst.

[0005] Byproduct control is difficult: If the reduction conditions are not properly controlled during the activation process, excessive byproducts such as CO may form on the catalyst surface, affecting the hydrogen purity and product quality of subsequent reactions.

[0006] To address the above problems, some improvement methods have been proposed in the prior art, such as: Staged reduction: This method attempts to avoid structural collapse by gradually increasing the temperature or adjusting the proportion of reducing gas. However, these methods often lack precise control over reduction kinetics and thermodynamic processes, resulting in low efficiency in the formation of active sites.

[0007] Additives: Introducing additives (such as alkali metals and rare earth elements) can stabilize the support structure or promote metal dispersion. However, the addition of additives may introduce new impurities, affecting the purity and long-term stability of the catalyst.

[0008] Optimizing the carrier structure: Designing porous or composite carriers to enhance mechanical stability. However, optimizing the carrier structure cannot directly resolve the contradiction between reduction conditions and the formation of active sites during activation.

[0009] The above background information is disclosed only to assist in understanding the inventive concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical teachings. In the absence of clear evidence, the novelty and inventiveness of the above application shall be deemed to be incomplete. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention proposes a noble metal catalyst and its activation method, as well as a methanol-to-hydrogen system. Through a staged, multi-parameter synergistic control activation method, it successfully solves the problems of structural collapse, insufficient formation of active sites, and difficulty in controlling byproducts during the activation process of noble metal catalysts in existing technologies. This improves methanol conversion rate while reducing CO content, meeting industrial demands for high conversion rates, effectively controlling byproduct generation, improving hydrogen purity and production efficiency, and extending the lifespan of the noble metal catalyst.

[0011] To achieve the above objectives, the technical solution of the present invention is as follows: On one hand, the present invention provides a method for activating a noble metal catalyst, comprising the following steps: Pre-activation step: The methanol-water solution is vaporized to obtain methanol-water vapor, and methanol-water vapor or inert gas is introduced into the catalyst bed at a first space velocity. The temperature is maintained within a preset first temperature range for a first time to remove physical moisture and trace impurities and replace the entire system with a reducing environment. Preliminary activation step: The methanol-water solution is fed with a high water-to-carbon molar ratio, heated to a second temperature range at a second space velocity and a preset heating rate, and maintained for a second duration to achieve the preliminary reduction of the noble metal catalyst and the preliminary formation of metal-oxygen vacancy cooperative sites. Deep activation step: Reduce the water-carbon molar ratio of the methanol-water solution feed, heat to the third temperature range at the third space velocity and the preset heating rate, maintain for the third duration, and complete the deep reduction and structural rearrangement of the catalyst.

[0012] This invention proposes a noble metal catalyst and its activation method, as well as a methanol-to-hydrogen system. Through a staged, multi-parameter synergistic control activation method, it successfully solves the problems of structural collapse, insufficient formation of active sites, and difficulty in controlling by-products in the activation process of noble metal catalysts in the prior art. This improves the methanol conversion rate while reducing the CO content, meeting the industrial demand for high conversion rates, effectively controlling the generation of by-products, improving the purity and production efficiency of hydrogen, and helping to extend the life of the noble metal catalyst.

[0013] As a preferred technical solution, in the pre-activation step: The first temperature range is 115℃-175℃; The first airspeed is 1-2h -1 ; The first duration is 0.5-2 hours; The water-carbon molar ratio in the methanol-water solution is 2.

[0014] As a preferred technical solution, in the preliminary activation step: The second temperature range is 275℃-325℃; The second airspeed is 1-5h -1 ; The preset heating rate is ≤5℃ / min; The second duration is 3-24 hours; The water-carbon molar ratio in the methanol-water solution is 1.5-2.0.

[0015] As a preferred technical solution, in the deep activation step: The third temperature range is 375℃-425℃; The third airspeed is 11-15 h. -1 ; The preset heating rate is ≤50℃ / min; The third duration is 0.5-4 hours; The water-carbon molar ratio in the methanol-water solution is 1.0-1.5.

[0016] As a preferred technical solution, in the pre-activation step, the initial temperature of the methanol-water solution after vaporization treatment to obtain methanol-water vapor is 90℃-110℃.

[0017] As a preferred technical solution, in the preliminary activation step, the noble metal catalyst is initially reduced and forms a metal-oxygen vacancy structure with the cerium-zirconium solid solution. The initially reduced noble metal is anchored on the oxygen vacancy to form a metastable structure.

[0018] As a preferred technical solution, in the deep activation step, the noble metal catalyst is deeply reduced. Short-time high-temperature reduction is beneficial to repairing the order of oxygen vacancies in cerium oxide, and exposes more acidic sites on the alumina microsphere carrier to promote the formation of oxygen vacancies.

[0019] On the other hand, the present invention provides a noble metal catalyst activated by the method described in any of the preceding claims, the noble metal catalyst comprising: Alumina microsphere carriers; A cerium-zirconium solid solution coating layer loaded on the surface of an alumina microsphere carrier; Pt-In2O3-Ga2O3 catalyst coating layer supported on the surface of cerium-zirconium solid solution coating layer.

[0020] As a preferred technical solution, the alumina microsphere support has a diameter of 4-6 mm, and the noble metal catalyst, after activation, exhibits the following properties within the tested space velocity range: Methanol conversion rate ≥ 84.4%; CO content < 4.46%; The hydrogen production rate increases linearly with increasing mass space velocity.

[0021] Furthermore, the present invention provides a methanol-to-hydrogen system, comprising: a reactor and a noble metal catalyst as described in any of the preceding claims, wherein the system is configured to perform an activation method for the noble metal catalyst as described in any of the preceding claims.

[0022] The present invention provides a noble metal catalyst and its activation method, as well as a methanol-to-hydrogen system, which have the following beneficial effects: 1) The present invention provides a noble metal catalyst and its activation method, as well as a methanol-to-hydrogen system. Through a staged, multi-parameter synergistic control activation method, it successfully solves the problems of structural collapse, insufficient formation of active sites, and difficulty in controlling by-products in the activation process of noble metal catalysts in the prior art. It improves the methanol conversion rate and reduces the CO content, meets the industrial demand for high conversion rate, effectively controls the generation of by-products, improves the purity and production efficiency of hydrogen, and helps to extend the life of noble metal catalysts.

[0023] 2) This invention provides a noble metal catalyst and its activation method, as well as a methanol-to-hydrogen system. Methanol-water solution was chosen as the reducing agent, which is the same as the reactant. This is not only convenient, but also the activation of Al2O3 microsphere carrier in a water vapor atmosphere is beneficial to the increase of Lewis acid site density on its surface, which meets the requirements of methanol reforming to produce hydrogen for a weak acid and strong base environment. Pre-activation step: Methanol-water vapor or inert gas is introduced into the catalyst bed at a first space velocity and kept at a first temperature for a first duration within a preset first temperature range to remove physical moisture and trace impurities and replace the entire system with a reducing environment. This step provides a pure catalyst surface for the subsequent activation step and avoids the interference of impurities on the activation process. Preliminary activation step: A methanol-water solution with a high water-to-carbon molar ratio is fed into the catalyst. The temperature is increased to a second temperature range at a second space velocity and a preset heating rate, and maintained for a second duration to achieve preliminary reduction of the noble metal catalyst and initial formation of active sites. This step, through low temperature, high water-to-methanol ratio, and long reaction time, enables the oxides in the coated structure to achieve preliminary reduction at a lower reduction rate, reducing the agglomeration of small particles, avoiding structural collapse, and lowering the activation energy for further deep activation. Simultaneously, it forms metal-oxygen vacancy synergistic sites, improving metal-support interactions and enhancing catalyst stability. The prolonged flushing with activating gas promotes the connectivity of the Al2O3 support pores, increases the support mesoporosity, reduces diffusion limitations, and improves catalyst performance. The deep activation step involves reducing the water-to-carbon molar ratio of the methanol-water solution feed, heating to the third temperature range at a third space velocity and a preset heating rate, and maintaining this temperature for the third duration to complete the deep reduction and structural rearrangement of the catalyst. This step, under a short-duration, high-temperature, and strong-reduction environment, promotes the rapid and complete reduction of the initially reduced metastable active sites, further improving the dispersion of the active metal. Simultaneously, the short-duration, high-temperature reduction helps restore the order of cerium oxide oxygen vacancies, while the exposure of more acidic sites on the Al2O3 support promotes the formation of oxygen vacancies, increases oxygen storage capacity, improves the catalyst's resistance to sintering, and contributes to the long-term stability of the catalyst.

[0024] 3) This invention provides a noble metal catalyst and its activation method, as well as a methanol-to-hydrogen system. The activated noble metal catalyst exhibits the following excellent properties within the tested space velocity range: Methanol conversion rate ≥84.4%: This indicates that the activated noble metal catalyst has a high methanol conversion efficiency, which can meet the industrial demand for high conversion rate. CO content < 4.46% indicates that the noble metal catalyst effectively controlled the generation of byproducts during the activation process and improved the purity of hydrogen. The hydrogen production rate increases linearly with increasing mass hourly space velocity (MHSV): This indicates that the activated noble metal catalyst has high initial activity and maintains the high hydrogen production efficiency of the noble metal catalyst. Attached Figure Description

[0025] Figure 1 The graphs show the methanol conversion rates of the activated noble metal catalysts in Example 1 and Comparative Example 1 provided by this invention. Figure 2 The CO content spectra of the activated noble metal catalysts of Example 1 and Comparative Example 1 provided by the present invention; Figure 3 The graphs show the hydrogen production rates of the activated noble metal catalysts in Example 1 and Comparative Example 1 provided by the present invention. Detailed Implementation

[0026] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] Since the full reduction of precious metals (such as Pt) requires strong reduction conditions, high temperature can easily lead to sintering. Modification of the carrier and addition of additives can improve stability and dispersibility to a certain extent, but there is still a risk of sintering when exposed to high temperature conditions for a long time.

[0028] This invention provides a method for activating a noble metal catalyst, comprising the following steps: Pre-activation step: The methanol-water solution is vaporized to obtain methanol-water vapor, and methanol-water vapor or inert gas is introduced into the catalyst bed at a first space velocity. The temperature is maintained within a preset first temperature range for a first time to remove physical moisture and trace impurities and replace the entire system with a reducing environment. Preliminary activation step: The methanol-water solution is fed with a high water-to-carbon molar ratio, heated to a second temperature range at a second space velocity and a preset heating rate, and maintained for a second duration to achieve the preliminary reduction of the noble metal catalyst and the preliminary formation of metal-oxygen vacancy synergistic sites, thereby improving the diffusion performance of the Al2O3 microsphere carrier. Deep activation step: Reduce the water-carbon molar ratio of the methanol-water solution feed, heat to the third temperature range at the third space velocity and the preset heating rate, maintain for the third duration, and complete the deep reduction and structural rearrangement of the catalyst.

[0029] This invention proposes a noble metal catalyst and its activation method, as well as a methanol-to-hydrogen system. Through a staged, multi-parameter synergistic control activation method, it successfully solves the problems of structural collapse, insufficient formation of active sites, and difficulty in controlling by-products in the activation process of noble metal catalysts in the prior art. This improves the methanol conversion rate while reducing the CO content, meeting the industrial demand for high conversion rates, effectively controlling the generation of by-products, improving the purity and production efficiency of hydrogen, and helping to extend the life of the noble metal catalyst.

[0030] Pre-activation step: Before activation, all active components of the noble metal catalyst are metal oxides. Before heating, methanol-water vapor with an initial feed temperature of 90℃-100℃ is introduced into the catalyst bed at a first space velocity. The bed is then kept at this preset temperature for a first duration. This serves two purposes: firstly, to purge and clean the catalyst surface before activation, removing physical moisture and trace impurities. These trace impurities include trace amounts of Cl that may be introduced into the noble metal catalyst due to the alumina microsphere support. - On the other hand, replacing the entire system with a reducing environment is beneficial for subsequent heating and activation. Here, methanol-water vapor can also be replaced with other (or hydrogen-containing) inert gases. Preliminary activation steps: Low-temperature, long-duration reduction reduces small particle agglomeration and avoids sintering; low temperature (275℃-325℃) and low space velocity (1-5h) are used. -1The reduction process, lasting 3-24 hours, proceeds gradually and uniformly from the surface towards the bulk phase. Low temperature and a high water-to-ethanol ratio (1.5-2.0 water-to-carbon molar ratio in methanol-water solution) result in a low reduction rate. At this stage, the oxide formation rate is lower than the diffusion rate, achieving a gentle reduction and effectively preventing structural collapse. This induces the formation of metastable active states in the active components, reducing the activation energy for subsequent deep activation and promoting the increase of the proportion of dominant crystal faces of the active components. Simultaneously, it induces strong interactions between the active components and the cerium-zirconium solid solution. The initially reduced active components anchor in the oxygen vacancies of the cerium-zirconium solid solution, forming metastable structures and improving catalyst stability. The prolonged scouring with activation gas facilitates the connectivity of the Al2O3 support channels, increasing the support's mesoporosity, reducing diffusion limitations, and improving catalyst performance. In the initial activation step, the noble metal catalyst reacts for a long time under low temperature and high water-to-ethanol ratio conditions, allowing the noble metal oxides in the catalyst to be reduced at a low reduction rate, preventing structural collapse, forming metastable active sites, and reducing diffusion limitations on the support.

[0031] Deep activation step: High-temperature, short-time, rapid reduction activation stabilizes active sites and improves the catalyst's resistance to sintering. This involves short-time (0.5-4 h) high-temperature (375℃-425℃) high-space-velocity (11-15 h) activation. -1 The low water-to-ethanol molar ratio (1.0-1.5 in methanol-water solution) provides ample reducing agent, ensuring sufficient reduction of the active component at higher reduction temperatures and forming stable active crystal faces. Simultaneously, the high-temperature reduction environment promotes rearrangement between the support and the noble metal active component, restoring the order of oxygen vacancies in cerium oxide, exposing more acidic sites on the alumina microsphere support, promoting oxygen vacancy formation, increasing oxygen storage capacity, and improving the catalyst's resistance to sintering. The short-term exposure to a high-temperature, strong-reduction environment during the deep activation step facilitates the rapid and complete reduction of the initially reduced metastable active sites, while also promoting rearrangement of atoms in the noble metal and support, enhancing the oxygen storage capacity of the noble metal catalyst and extending its lifespan.

[0032] Preferably, in the pre-activation step: The first temperature range is 115℃-175℃, and the first temperature range is preferably 125℃, 145℃, or 165℃. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the protection range. The first airspeed is 1-2h -1 The first airspeed is preferably 1h -1 1.5h -1 or 2h -1 Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the scope of protection. The first duration is 0.5-2h, preferably 0.5h, 1h or 2h. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the scope of protection. The water-carbon molar ratio in the methanol-water solution is 2.

[0033] Preferably, in the preliminary activation step: The second temperature range is 275℃-325℃, and the second temperature range is preferably 275℃, 300℃ or 325℃. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the protection range. The second airspeed is 1-5h -1 The second airspeed is preferably 1.5 h. -1 3h -1 or 5h -1 Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the scope of protection. The preset heating rate is ≤5℃ / min, and the preset heating rate is preferably 5℃ / min, 4℃ / min, 3℃ / min, 2℃ / min or 1℃ / min. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the protection scope. The second duration is 3-24h; the second duration is preferably 5h, 9h, 16h or 24h. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the scope of protection. The water-carbon molar ratio in the methanol-water solution is 1.5-2.0, preferably 1.5, 1.7 or 2.0. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the scope of protection.

[0034] Preferably, in the deep activation step: The third temperature range is 375℃-425℃, preferably 375℃, 400℃, or 425℃. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the protection range. The third airspeed is 11-15 h. -1 The third airspeed is preferably 11h. -1 12.5h -1 or 15 hours -1 Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the scope of protection. The preset heating rate is ≤50℃ / min, and the preset heating rate is preferably 45℃ / min, 35℃ / min, 25℃ / min or 15℃ / min. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the scope of protection. The third duration is 0.5-4h, preferably 0.5h, 1h, 2h, 3h or 4h. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the scope of protection. The water-carbon molar ratio in the methanol-water solution is 1.0-1.5, preferably 1.0, 1.3 or 1.5. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the scope of protection.

[0035] Preferably, in the pre-activation step, the initial temperature of the methanol-water solution after vaporization treatment to obtain methanol-water vapor is 90℃-110℃. The initial temperature of the methanol-water solution after vaporization treatment to obtain methanol-water vapor is preferably 90℃, 100℃ or 110℃. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the scope of protection.

[0036] Preferably, in the preliminary activation step, the noble metal catalyst forms a cerium-zirconium solid solution oxygen vacancy structure, and the noble metal is initially reduced and anchored in the cerium-zirconium solid solution oxygen vacancy to form a metastable structure.

[0037] Preferably, in the deep activation step, the noble metal in the noble metal catalyst is deeply reduced, and the noble metal and support are rearranged.

[0038] On the other hand, the present invention provides a noble metal catalyst activated by the method described in any of the preceding claims, the noble metal catalyst comprising: Alumina microsphere carriers; A cerium-zirconium solid solution coating layer loaded on the surface of an alumina microsphere carrier; Pt-In2O3-Ga2O3 catalyst coating layer supported on the surface of cerium-zirconium solid solution coating layer.

[0039] The method for preparing the noble metal catalyst includes the following steps: using alumina microspheres as a carrier, coating the surface of the alumina microsphere carrier with a cerium-zirconium solid solution slurry to form a cerium-zirconium solid solution coating layer; and coating the surface of the cerium-zirconium solid solution coating layer with a Pt-In2O3-Ga2O3 slurry to form a Pt-In2O3-Ga2O3 noble metal coating layer.

[0040] Preferably, the alumina microsphere support has a diameter of 4-6 mm, and more preferably 5 mm. After activation, the noble metal catalyst exhibits the following properties within the tested space velocity range: Methanol conversion rate ≥ 84.4%; CO content < 4.46%; The hydrogen production rate increases linearly with increasing mass space velocity.

[0041] Furthermore, the present invention provides a methanol-to-hydrogen system, comprising: a reactor and a noble metal catalyst as described in any of the preceding claims, wherein the system is configured to perform an activation method for the noble metal catalyst as described in any of the preceding claims.

[0042] Example 1 This invention provides a method for activating a noble metal catalyst, comprising the following steps: Pre-activation step: Methanol and water are mixed in a mixer at a water-to-carbon molar ratio of 2, then vaporized in an evaporator into methanol-water vapor (initial temperature 100℃), and then discharged at a first space velocity of 1.5 h⁻¹. -1 Enter the catalyst bed, set the first temperature range to 125℃ and keep it at that temperature for a first time of 1 hour; Monitoring the composition of the outlet gas: No hydrogen production reaction occurs during the pre-activation step; Preliminary activation step: Maintain the water-to-carbon molar ratio of the methanol-water solution feed at 1.7, and use a second space velocity for 3 hours. -1 The temperature was increased to 300℃ at a preset heating rate of 2℃ / min and maintained for a second duration of 16h to achieve the initial reduction of the noble metal catalyst and the initial formation of active sites. The composition of the outlet gas was monitored during the initial activation step, and the experimental data of the outlet gas composition during the initial activation step are shown in Table 1 below: Table 1. Experimental data on monitoring the composition of the outlet gas during the preliminary activation stage. Table 1 shows that under higher water-to-methanol ratios, lower space velocities, and lower reaction temperatures, the methanol conversion rate of the noble metal catalyst is >97.0%, the CO content is <1.5%, and the hydrogen production is stable. A longer reduction environment at 300℃ is beneficial for the initial reduction of the noble metal catalyst. The noble metal (e.g., Pt) anchors in the oxygen vacancies of the cerium-zirconium solid solution to form a metastable structure, effectively reducing the activation energy for further reduction and improving catalyst stability. Deep activation step: Reduce the water-to-carbon molar ratio of the methanol-water solution feed to 1.3, and use a third space velocity of 12.5 h⁻¹. -1The temperature was increased to the third temperature range of 400℃ at a preset heating rate of 25℃ / min and maintained for a third duration of 1 hour to complete the deep reduction and structural rearrangement of the catalyst. The composition of the outlet gas was monitored during the deep activation step, and the experimental data for monitoring the outlet gas composition during the deep activation step are shown in Table 2 below. Table 2. Experimental data on the composition of the outlet gas during the deep activation step. From Table 2, we can observe that a low water-to-methanol ratio, high space velocity, and high reaction temperature, while preventing carbon deposition, ensure that the methanol conversion rate of the noble metal catalyst is between 90% and 95%, the CO content is between 3.4% and 3.5%, and the hydrogen production is high and stable, which is conducive to the deep reduction of noble metals (such as Pt). At the same time, the high reduction temperature is conducive to the rearrangement of the catalyst and support, increasing the oxygen storage capacity, improving the catalyst's resistance to sintering, and helping to extend the catalyst life.

[0043] Example 2 The rest of the technical solution is the same as the above embodiment, except for the preliminary activation step: maintaining the water-carbon molar ratio of the methanol-water solution feed at 1.5, and using a second space velocity for 3 hours. -1 The temperature was increased to the second temperature range of 275℃ at a preset heating rate of 2℃ / min and maintained for a second duration of 24h. The experimental data for monitoring the composition of the outlet gas during the preliminary activation step are shown in Table 3 below: Table 3. Experimental data on monitoring the composition of the outlet gas during the preliminary activation stage. From Table 3, we can observe that under moderate water-to-methanol ratio, high space velocity, and low reaction temperature, the methanol conversion rate of the noble metal catalyst is between 80% and 85%, the CO content is <1%, and the hydrogen production is stable. The relatively long reduction environment at 275℃ may have enabled the initial reduction of the noble metal catalyst and the formation of the metal-oxygen vacancy metastable structure. The difference lies in the deep activation step: the water-carbon molar ratio of the methanol-water solution feed is reduced to 1.0, and the feed is activated at a third space velocity of 15 h⁻¹. -1 The temperature was increased to the third temperature range of 375℃ at a preset heating rate of 15℃ / min and maintained for a third duration of 3 hours. The experimental data on the composition of the outlet gas during the deep activation step are shown in Table 4 below. Table 4. Experimental data on monitoring the composition of the outlet gas during the deep activation step. From Table 4, we can observe that with a low water-to-methanol ratio, high space velocity, and high reaction temperature, the methanol conversion rate is low, ranging from 59% to 69%, and the CO content is between 3% and 3.5%. The hydrogen production is not high but stable. The relatively high temperature for a long period of time may not have achieved deep reduction of precious metals (such as Pt), and there is considerable room for improvement in catalyst activity.

[0044] Example 3 The rest of the technical solution is the same as the above embodiment, except for the preliminary activation step: maintaining the water-carbon molar ratio of the methanol-water solution feed at 2.0, and using a second space velocity of 5 h⁻¹. -1 The temperature was increased to the second temperature range of 325℃ at a preset heating rate of 4℃ / min and maintained for a second duration of 9 hours. The experimental data for monitoring the composition of the outlet gas during the preliminary activation step are shown in Table 5 below: Table 5. Experimental data on monitoring the composition of the outlet gas during the preliminary activation stage. Table 5 shows that under high water-to-methanol ratio, low space velocity, and relatively high reaction temperature, the methanol conversion rate of the noble metal catalyst is close to 100%, the CO content is between 1.19% and 1.22%, and the hydrogen production is low and stable. The relatively long reduction environment at 325℃ is conducive to the initial reduction of the noble metal catalyst. The noble metal (e.g., Pt) anchors in the oxygen vacancies of the cerium-zirconium solid solution to form a metastable structure, which effectively reduces the activation energy for further reduction and improves the stability of the catalyst. The difference lies in the deep activation step: the water-carbon molar ratio of the methanol-water solution is reduced to 1.5 in the feed, and the feed is fed at a third space velocity of 11 h⁻¹. -1 The temperature was increased to the third temperature range of 425℃ at a preset heating rate of 35℃ / min and maintained for a third duration of 0.5h. The experimental data on the composition of the outlet gas during the deep activation step are shown in Table 6 below: Table 6. Experimental data on monitoring the composition of the outlet gas during the deep activation step. From Table 6, we can observe that a higher water-to-methanol ratio, lower space velocity, and higher reaction temperature ensure a higher methanol conversion rate (96%), a CO content of 3.06%, and a higher hydrogen production (0.161 mmol / (gcat·s)) for the noble metal catalyst while preventing carbon deposition. These reaction conditions are conducive to the deep reduction of noble metals (such as Pt) and promote the rearrangement of the catalyst and support, increasing the oxygen storage capacity. However, excessively high reaction temperatures may cause carbon deposition and reduce the reaction performance of the catalyst.

[0045] Comparative Example 1 Comparative Example 1 provides a method for activating a noble metal catalyst, comprising the following steps: A methanol-water solution with a water-to-carbon molar ratio of 1.5 was gasified and fed into the catalyst bed, and reacted at 325°C for 1.5 hours. -1 Activate at space velocity for 32 hours, and periodically sample and monitor each catalytic performance index. At this time, the change rate of each performance index tends to zero (the change is not significant), indicating that the activation is complete.

[0046] like Figure 1 As shown in the graphs, the methanol conversion rates of the activated noble metal catalysts of Example 1 and Comparative Example 1 provided by this invention are as follows: From the graphs, we can observe that the methanol conversion rates of the activated noble metal catalysts of Example 1 and Comparative Example 1 decrease continuously with increasing space velocity. Moreover, the methanol conversion rate of the activated noble metal catalyst of Example 1 is consistently higher than that of the activated noble metal catalyst of Comparative Example 1. The methanol conversion rate of the activated noble metal catalyst of Example 1 is ≥84.38%, indicating that the activated noble metal catalyst still has a high methanol conversion capacity even with low support diffusion efficiency and low thermal conductivity, which can meet the industrial demand for high conversion rates.

[0047] like Figure 2 As shown in the graphs, the CO content of the activated noble metal catalysts of Example 1 and Comparative Example 1 provided by the present invention is as follows: From the graphs, we can observe that the CO content of the activated noble metal catalyst of Example 1 decreases with increasing space velocity; the CO content of the activated noble metal catalyst of Comparative Example 1 increases with increasing space velocity; and the CO content of the activated noble metal catalyst of Example 1 is consistently lower than that of the activated noble metal catalyst of Comparative Example 1, with the CO content of the activated noble metal catalyst of Example 1 being <4.46%. This indicates that the noble metal catalyst of Example 1 effectively controls the generation of byproducts and improves the purity of hydrogen during the activation process.

[0048] like Figure 3 As shown in the figure, the hydrogen production rate of the noble metal catalysts activated in Example 1 and Comparative Example 1 provided by the present invention is plotted. From the figure, we can observe that the initial hydrogen production rate of the noble metal catalyst activated in Example 1 is 0.0621 mmol / (gcat•s), and it increases linearly with the increase of mass hourly space velocity. This is consistent with the trend of hydrogen production rate of the noble metal catalyst activated in Comparative Example 1, indicating that the noble metal catalyst described in the present invention has high initial activity. The high-temperature deep activation step in Example 1 did not lead to catalyst carbon deposition or sintering deactivation, thus maintaining the high hydrogen production efficiency of the noble metal catalyst.

[0049] The activation method for the noble metal catalyst provided in Example 1 of this invention employs a three-step reduction method. During the initial reduction at low temperature, a metastable state of the active component is formed, which not only lowers the activation energy of the reduction reaction, facilitating subsequent deep reduction, but also improves the stability of the catalyst and enhances the diffusion capacity of the support. During the deep reduction at high temperature, the active component is fully reduced in a relatively short time to form a stable active crystal face. At the same time, the high-temperature reduction environment promotes rearrangement between the support and the metal, enhances the metal-support interaction, exposes more acidic sites, promotes the formation of oxygen vacancies, improves the catalyst's resistance to sintering, and helps extend the catalyst's lifespan.

[0050] Therefore, the activation method for the noble metal catalyst provided in Example 1 of this invention, which employs a three-step reduction method, compared to the activation method for the noble metal catalyst provided in Comparative Example 1, which employs a one-step reduction method, not only shortens the reduction time but also improves various performance indicators of the catalyst (such as...). Figures 1-3 As shown in the figure, this is beneficial for extending the lifespan of precious metal catalysts.

[0051] It is understood that this invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are protected by this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of this invention.

Claims

1. A method for activating a noble metal catalyst, characterized in that, Includes the following steps: Pre-activation step: The methanol-water solution is vaporized to obtain methanol-water vapor, and methanol-water vapor or inert gas is introduced into the catalyst bed at a first space velocity. The temperature is maintained within a preset first temperature range for a first time to remove physical moisture and trace impurities and replace the entire system with a reducing environment. Preliminary activation step: The methanol-water solution is fed with a high water-to-carbon molar ratio, heated to a second temperature range at a second space velocity and a preset heating rate, and maintained for a second duration to achieve the preliminary reduction of the noble metal catalyst and the preliminary formation of metal-oxygen vacancy cooperative sites. Deep activation step: Reduce the water-carbon molar ratio of the methanol-water solution feed, heat to the third temperature range at the third space velocity and the preset heating rate, maintain for the third duration, and complete the deep reduction and structural rearrangement of the catalyst.

2. The activation method for the noble metal catalyst according to claim 1, wherein in the pre-activation step: The first temperature range is 115℃-175℃; The first airspeed is 1-2h -1 ; The first duration is 0.5-2 hours; The water-carbon molar ratio in the methanol-water solution is 2.

3. The activation method for the noble metal catalyst according to claim 1, characterized in that, In the preliminary activation step: The second temperature range is 275℃-325℃; The second airspeed is 1-5h -1 ; The preset heating rate is ≤5℃ / min; The second duration is 3-24 hours; The water-to-carbon molar ratio in the methanol-water solution is 1.5-2.

0.

4. The activation method for the noble metal catalyst according to claim 1, characterized in that, In the deep activation step: The third temperature range is 375℃-425℃; The third airspeed is 11-15 h. -1 ; The preset heating rate is ≤50℃ / min; The third duration is 0.5-4 hours; The water-carbon molar ratio in the methanol-water solution is 1.0-1.

5.

5. The activation method for the noble metal catalyst according to claim 1 or 2, characterized in that, In the pre-activation step, the methanol-water solution introduced is treated with vaporized steam to obtain methanol-water vapor at an initial temperature of 90℃-110℃.

6. The activation method for the noble metal catalyst according to claim 1 or 3, characterized in that, In the preliminary activation step, the noble metal catalyst is initially reduced and forms a metal-oxygen vacancy structure with the cerium-zirconium solid solution. The initially reduced noble metal is anchored on the oxygen vacancy to form a metastable structure.

7. The activation method for the noble metal catalyst according to claim 1 or 4, characterized in that, In the deep activation step, the noble metal catalyst is deeply reduced. Short-time high-temperature reduction helps to restore the order of oxygen vacancies in cerium oxide, and exposes more acidic sites on the alumina microsphere carrier to promote the formation of oxygen vacancies.

8. A noble metal catalyst activated by the method according to any one of claims 1-7, characterized in that, The noble metal catalyst comprises: Alumina microsphere carriers; A cerium-zirconium solid solution coating layer loaded on the surface of an alumina microsphere carrier; Pt-In2O3-Ga2O3 catalyst coating layer supported on the surface of cerium-zirconium solid solution coating layer.

9. The noble metal catalyst according to claim 8, characterized in that, The alumina microsphere support has a diameter of 4-6 mm, and the noble metal catalyst, after activation, exhibits the following properties within the tested space velocity range: Methanol conversion rate ≥ 84.4%; CO content < 4.46%; The hydrogen production rate increases linearly with increasing mass space velocity.

10. A methanol-to-hydrogen system, characterized in that, include: The reactor and the noble metal catalyst as described in any one of claims 8-9, wherein the system is configured to perform the activation method of the noble metal catalyst as described in any one of claims 1-7.

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