System and method for testing oxygen storage capacity of catalyst

Abstract

The invention relates to the technical field of catalyst oxygen storage capacity testing, in particular to a catalyst oxygen storage capacity testing system and method.The catalyst oxygen storage capacity testing system comprises a gas supply module, a reaction module and a control and data acquisition module, 18O marking gas, 16O reference oxygen, reducing gas and inert carrier gas are provided, and flow, temperature and pressure are accurately controlled. The method comprises a 18O / 16O isotope homogeneous phase exchange experiment, a dynamics calculation experiment and an oxygen storage capacity calculation experiment, partial pressure changes of 16O2, 16O18O and 18O2 are monitored in real time through mass spectrometry, the oxygen exchange rate, the surface diffusion coefficient (DCS) and the bulk phase diffusion coefficient (DCB) are calculated, and the oxygen storage capacity (CO-OSC and H2-OSC) is calculated based on CO oxidation or H2 reduction reaction. The oxygen dynamic behavior is synchronously analyzed, the blank of a traditional method is filled, and the method has the advantages of high precision and multiple parameters, is suitable for the fields of automobile exhaust purification, industrial waste gas treatment and the like, and promotes conversion of catalyst research and development from experience screening to rational design.

Description

Technical Field

[0001] This invention relates to the field of catalyst oxygen storage capacity testing technology, and specifically to a catalyst oxygen storage capacity testing system and method. Background Technology

[0002] With increasingly stringent global environmental regulations, catalysts are playing an increasingly crucial role in pollutant control. In fields such as automotive exhaust purification, industrial waste gas treatment, and chemical chain energy conversion, the oxygen storage capacity (OSC) of a catalyst is one of the core indicators determining its performance. Oxygen storage capacity refers to a catalyst's ability to store and release oxygen during a redox cycle, directly affecting its oxidation efficiency for carbon monoxide (CO) and hydrocarbons (HC), as well as its oxidation efficiency for nitrogen oxides (NOx). x The reduction efficiency of oxygen storage capacity is measured. However, traditional methods for testing oxygen storage capacity have significant limitations, making it difficult to meet the needs of high-precision, multi-parameter analysis, which restricts the research and optimization of high-performance catalysts.

[0003] The industrial demand for testing catalyst oxygen storage capacity has shifted from "static total amount determination" to "dynamic behavior analysis." Early studies primarily relied on oxygen pulse titration to evaluate oxygen storage capacity. This involved alternately introducing CO and O2 pulses into the catalyst and calculating the total oxygen storage based on CO2 generation. While simple, this method only reflects the total oxygen storage capacity of the catalyst under specific conditions and cannot distinguish the contributions of surface-adsorbed oxygen and lattice oxygen (bulk oxygen), nor can it obtain dynamic parameters such as oxygen migration rate and diffusion path. Another commonly used method is temperature-programmed reduction (H2-TPR), which assesses the total amount of reducible oxygen by monitoring the hydrogen consumption of the catalyst during reduction. However, this method only reflects the thermodynamic accessibility of oxygen and cannot provide information on the diffusion rate of oxygen within the catalyst. In actual operating conditions, the oxygen behavior of a catalyst is the result of multiple synergistic effects, including the activation of oxygen at metal active sites, surface diffusion, bulk migration, and reaction with reactants. It depends not only on the total oxygen storage but also on the surface diffusion coefficient (D). CS ) and bulk diffusion coefficient (D CB These steps are closely related. Traditional methods cannot quantify the kinetic characteristics of these steps, resulting in a lack of precise guidance for catalyst formulation optimization.

[0004] To overcome the limitations of traditional methods, 18 The O isotope labeling method emerged as a result. This method utilizes... 18 O and 16 The quality difference of O, through tracking 18 This study visualizes and quantifies the exchange behavior of oxygen between the catalyst and the gas phase. The core principle is: introducing oxygen at a specific temperature... 18 O2 gas, 18O interacts with the catalyst through steps such as dissociation adsorption, surface diffusion, and bulk migration. 16 O2 exchange occurs, and the gas or solid phase is monitored using techniques such as mass spectrometry (MS). 18 Changes in O abundance are used to calculate parameters such as oxygen exchange rate and diffusion coefficient. However, currently... 18 The oxygen isotope method still suffers from complex experimental systems and insufficient universality. This invention proposes a method for testing the oxygen storage capacity of catalysts, aiming to optimize... 18 Experimental design and data processing model for O isotope labeling method, establishing a unified experimental procedure (including catalyst pretreatment, ...). 18 (O2 exchange conditions, detection parameters, etc.) to improve the reproducibility of results; develop a multi-scale data analysis model, combining the diffusion behavior of surface and bulk oxygen, to accurately calculate D CS and D CB This invention enables the simultaneous determination of oxygen exchange rate and diffusion coefficient, and, combined with CO and H2 oxidation experiments, calculates the oxygen storage capacity of the catalyst and determines its resistance to carbon deposition. This invention fills a gap in traditional methods for analyzing dynamic oxygen behavior, providing quantitative evidence for shifting catalyst development from "empirical screening" to "rational design" and promoting catalyst structural optimization. Summary of the Invention

[0005] The purpose of this invention is to provide a catalyst oxygen storage capacity testing system and method, employing... 18 O isotope labeling technology, through automated control and mass spectrometry monitoring, can simultaneously measure oxygen exchange rate, diffusion coefficient and oxygen storage capacity, achieving high-precision dynamic analysis and assisting in the rational design of catalysts.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A catalyst oxygen storage capacity testing system, comprising: Gas supply module, configured to provide including 18 O isotope-labeled gases, including 16 The system uses oxygen as a reference, a variety of reducing gases, and an inert carrier gas, with precise proportioning and control of the gas flow rates. The reaction module is fluidly connected to the gas supply module through a corrosion-resistant pipeline to form an airtight reaction space. The reaction space is equipped with a fixed catalyst bed and has controllable heating, temperature monitoring and pressure stabilization functions. The control and data acquisition module is connected to the gas supply module and the reaction module via signal transmission, and automatically executes functions including... 18 O / 16 O isotopes undergo homogeneous exchange. 18 O / 16A serialized experimental procedure for oxygen isotope kinetic analysis and oxygen storage capacity measurement; the isotope exchange process was monitored and recorded online in real time using a mass spectrometer. 16 O2, 16 O 18 O、 18 The partial pressure kinetics curve of O2, and the dynamic partial pressure data of CO oxidation products or H2 consumption during the oxygen storage capacity measurement process; The system, through the execution of the serialized experimental procedure and the acquisition of the dynamic partial pressure data, can simultaneously analyze the oxygen exchange kinetics, oxygen surface migration and bulk diffusion behavior, and total oxygen storage capacity of the catalyst.

[0007] Furthermore, the gas supply module includes: The gas supply unit consists of five independent pressurized gas cylinders, each containing 2% premixed gas. 18 O2 / He gas, 2% 16 O2 / He gas, 5% H2 / He gas, 5% CO / He gas, and He with a purity > 99.99%; The gas control unit includes multiple parallel mass flow controllers with a range of 0-200 mL / min and an accuracy of ±1% FS, as well as one-way valves installed in each gas path, for achieving accurate gas metering and flow direction control.

[0008] Furthermore, the reaction module includes: A fixed-bed reactor is constructed from a U-shaped quartz tube filled with 20-40 mesh granular catalyst to be tested, and the catalyst bed is axially fixed by quartz wool. The tubular heating device, which is installed outside the fixed bed reactor, can perform programmed temperature control within a temperature range of 20℃ to 900℃, with a temperature control accuracy of ±1℃. The temperature sensing unit, which is a K-type thermocouple inserted into the geometric center of the catalyst bed, is used to directly measure and feedback the real-time temperature of the reaction zone. The pressure control unit consists of an absolute pressure sensor and an electric back pressure valve located at the reactor outlet. It is used to dynamically stabilize the absolute pressure of the system between 1 atm and 5 atm, with a control accuracy of ±0.05 atm.

[0009] Furthermore, the control and data acquisition module includes: The mass spectrometer detector is configured to monitor in real time with a time resolution of 1 second. 16 O2 (m / z=32) 16 O 18 O (m / z=34) 18 Changes in the partial pressure of O2 (m / z=36); The central controller stores preset experimental timing logic, which is used to send control commands to the mass flow controller, the tubular heating device and the electric back pressure valve to realize fully automatic process operation. The data acquisition and storage unit synchronously records all signals from the mass spectrometer, the temperature sensing unit, the pressure control unit, and the mass flow controller at a sampling frequency of 1 Hz, and generates a timestamp-aligned data file.

[0010] Furthermore, the corrosion-resistant pipelines connecting the various modules are made of quartz or austenitic stainless steel, and the outer surface of all pipelines exposed to the gas path is covered with a heat insulation layer to minimize the impact of ambient temperature fluctuations on gas transmission and reaction.

[0011] On the other hand, the present invention proposes a method for testing the oxygen storage capacity of a catalyst based on the above system, the method comprising the following steps: S1: 18 O / 16 Homogeneous exchange experiment of O isotopes: S1.1: The catalyst is pretreated by a redox cycle to establish a standardized initial surface state; S1.2: Under preset isothermal reaction conditions, a 2% catalyst pulse is introduced. 18 O2 / He and 2% 16 A mixture of O2 and He gases; S1.3: Online monitoring 16 O2, 16 O 18 O、 18 The partial pressure of O2 evolves over time until it reaches isotope exchange equilibrium. S2: 18 O / 16 O isotope dynamics calculation experiment: S2.1: The catalyst is subjected to deep reduction-surface oxidation pretreatment to enrich surface active oxygen and clear bulk mobile oxygen. S2.2: Under the stated isothermal reaction conditions, 2% is introduced into the catalyst. 18 O2 / He gas; S2.3: Online monitoring 16 O2, 16 O 18 O、 18 The evolution of O2 partial pressure over time was used to capture the initial dynamics of oxygen migration from the surface to the bulk phase; S3: Experiment on calculating oxygen storage capacity: S3.1: After the isotope exchange is completed, under the isothermal reaction conditions, the reaction atmosphere is switched to 5% CO / He or 5% H2 / He; S3.2: Online monitoring of products (C) in the CO oxidation pathway 16 O, C 16 O2, C 16 O 18 O) partial pressure, or H2 consumption partial pressure under the H2 reduction pathway, until the reaction is complete; The method further includes calculating the oxygen exchange rate based on the data from step S1, calculating the surface and bulk oxygen diffusion coefficients based on the data from step S2, and calculating the oxygen storage capacity using CO and H2 as probes based on the data from step S3.

[0012] Furthermore, the redox cycle pretreatment in step S1 specifically includes: heating to 400°C at a rate of 10°C / min under a He atmosphere at a rate of 50 mL / min and stabilizing; then switching to a 5% [unclear - possibly a specific temperature range] rate of 50 mL / min. 16 Oxidation was carried out in an O2 / He atmosphere for 30 minutes; then reduction was carried out in a 5% H2 / He atmosphere at a flow rate of 50 mL / min for 60 minutes; finally, the atmosphere was switched back to He to purge for 30 minutes, and the temperature was programmed to decrease to the target reaction temperature at a rate of 10 °C / min.

[0013] Furthermore, the deep reduction-surface oxidation pretreatment in step S2 specifically includes: programmed heating to 300°C in a He atmosphere at a rate of 50 mL / min; switching to a 5% H2 / He atmosphere at a rate of 50 mL / min and maintaining for 60 minutes for deep reduction; purging with a He atmosphere for 30 minutes, followed by programmed heating to 400°C at a rate of 10°C / min; switching to a 5% H2 / He atmosphere at a rate of 50 mL / min. 16 Surface oxidation was carried out in an O2 / He atmosphere for 60 minutes; finally, the surface was purged in a He atmosphere for 60 minutes to ensure that only surface-adsorbed oxygen species were present.

[0014] Furthermore, in step S1 18 O / 16 The formula for calculating the initial reaction rate in a homogeneous O isotope exchange experiment is: in, Initial reaction rate (at.m) M -2 s -1 ); The total number of O atoms in the gas phase; Metal area of ​​the catalyst (m) 2 ); :16 O 18 The partial pressure of O (at.); Total pressure ( ).

[0015] In the gas phase at each time t 18 The formula for calculating the oxygen atom fraction is as follows: in, : in the gas phase at time t 18 O atom fraction; Oxygen partial pressure at time t (at., x=32, 34, 36).

[0016] The formula for calculating the switching rate is as follows: in, : Switching rate (atoms (S) -1 g -1 )); Avogadro's constant (taken as 6.02 × 10⁻⁶) 23 ); Total pressure (at.); Specific surface area of ​​oxides (m²) 2 ); Ideal gas constant (taken as 8.314 J / (mol·K)); , : The volumes of the heated and unheated zones of the reactor are respectively (m³). 3 ); , : These represent the temperatures (K) of the heated and unheated zones of the reactor, respectively.

[0017] Further, step S2.1 specifically includes: programmatically heating the catalyst under a He atmosphere, reducing it by introducing 5% H2 / He, then purging it with He and heating it again, and introducing 5% H2 / He at that temperature. 16 O2 / He oxidation, followed by He purging and then 2% oxygen. 18 O2 / He, real-time recording of oxygen partial pressure changes.

[0018] Furthermore, the surface diffusion coefficient ( The calculation formula is: in, The number of atoms that diffuse at the start of the exchange reaction; :isotope 18 The concentration of O; :isotope18 The radius of O; :isotope 18 O metal particles (n particles / m) 2 The perimeter of ().

[0019] in, Surface diffusion coefficient; The initial slope of the curve represents... With function The changes.

[0020] Furthermore, the bulk diffusion coefficient ( The calculation formula is: in, : Bulk diffusion coefficient; : The final slope of the curve; Catalyst density (kg / m³) 3 ); Catalyst surface area (m²) 2 ); Total oxygen atoms in the gas phase; , , : These represent the gas phase at time t. 18 The atomic fraction of O, and the amount of O in the solid phase at time t. 18 The atomic fraction of O and its content in the gas phase at equilibrium 18 The atomic fraction of O.

[0021] Furthermore, after step S3 is completed, 5% CO / He or 5% H2 / He is introduced, and C is monitored. 16 O, C 16 O2, C 16 O 18 The partial pressure change of O generation or H2 consumption reaches equilibrium; the formula for calculating oxygen storage capacity is: in, , : These represent the oxygen storage capacity of the catalyst (mmol / g) calculated by different methods. : Flow rate of the reaction gas during the reaction process (mL / min); The volume of 1 mol of an ideal gas is 22.4 L; Mass of catalyst (g); : The concentration of the reducing gas H2 used.

[0022] Furthermore, a pressure reducing valve (accuracy ±0.01 bar) is installed at the outlet of the gas cylinder of the gas source unit; the mass flow controller has a range of 0-200 mL / min and an accuracy of ±1% FS.

[0023] Furthermore, the U-shaped quartz tube of the fixed bed reactor has an inner diameter of 1 mm, an outer diameter of 2 mm, and a height of 25 mm; the connecting pipes of each module are made of quartz or stainless steel, and the outer wall is wrapped with a heat insulation layer.

[0024] Furthermore, the data acquisition system has a storage frequency of 1 Hz and acquires mass spectrometry signals, temperature, pressure, and flow data in real time; the central controller uses a Siemens S7-1200 PLC.

[0025] Furthermore, by comparing the numerical differences between CO-OSC and H2-OSC, the catalyst's resistance to carbon deposition was determined. When the H2-OSC value is significantly higher than the CO-OSC value (ratio exceeding 1.5 or difference > 0.01 mmol·g), -1 This indicates that the catalyst is sensitive to CO disproportionation or its surface is easily deactivated; When there is no statistically significant difference between H2-OSC and CO-OSC values ​​(i.e., the H2-OSC / CO-OSC ratio is between 1.0 and 1.2, or the difference between the two is <0.005 mmol·g), -1 This indicates strong resistance to carbon buildup or weak surface alkalinity.

[0026] The beneficial effects of this invention are: This invention is achieved through 18 O / 16 Homogeneous exchange experiments and kinetic calculations of O isotopes were conducted, and mass spectrometry was used to monitor the gas phase in real time. 16 O2, 16 O 18 O、 18 The change in the partial pressure of O2, combined with the initial reaction rate formula Directly related 16 O 18 The O generation rate is correlated with the catalyst metal surface area, quantifying the dissociation-adsorption kinetics of surface oxygen; simultaneously, the bulk diffusion coefficient formula is used... Based on gas phase 18The linear relationship between the oxygen atom fraction and time was analyzed to determine the oxygen migration rate within the crystal lattice. For example, the initial reaction rate of LCMO-0.2 in the examples was significantly higher than that of CuO, indicating a stronger surface oxygen activation capability; while the difference in bulk diffusion coefficients revealed the unobstructedness of the lattice oxygen migration pathways. This discriminatory ability allows researchers to specifically optimize catalyst structures—such as enhancing surface oxygen activation by regulating metal dispersion or introducing lattice defects to promote bulk oxygen diffusion—thereby improving the overall performance of the catalyst under dynamic operating conditions.

[0027] This invention enables the continuous execution of isotope exchange, kinetic calculations, and oxygen storage capacity testing within the same experimental system. Stable conditions are ensured by a mass flow controller in the gas supply module and temperature and pressure sensors in the reaction module. The control and data acquisition module synchronously acquires mass spectrometry signals, temperature, pressure, and flow data at a frequency of 1 Hz, thereby deriving multiple parameters such as oxygen exchange rate, surface diffusion coefficient, bulk diffusion coefficient, and oxygen storage capacity in a single measurement. For example, in the embodiments, the oxygen exchange rate of the LCMO, along with its surface and bulk diffusion coefficients, reveals its oxygen migration mechanism: the surface diffusion rate is relatively fast, but bulk diffusion is limited, forming a bottleneck. This synchronous measurement avoids the systematic errors introduced by multiple experiments in traditional methods, and the inherent correlation between parameters (such as the surface diffusion coefficient) is also addressed. (Coupled with oxygen exchange rate) provides a more comprehensive perspective on catalyst dynamics, enhancing the guiding value of data in optimizing catalyst formulations.

[0028] This invention uses oxygen storage capacity calculation experiments to derive CO-OSC and H2-OSC values ​​based on CO oxidation and H2 oxidation reactions, respectively, and uses their comparison to determine the tendency to resist carbon deposition: if H2-OSC is significantly greater than CO-OSC, it indicates that the catalyst is prone to surface carbon deposition or deactivation in CO-rich environments due to disproportionation reaction (2CO→C+CO2); if the two are similar, it reflects strong resistance to carbon deposition or weak surface alkalinity. For example, in the examples, the difference between CO-OSC and H2-OSC for LCMO and LCMO-0.2 is extremely small (<0.003mmol / g), indicating that their surfaces are not prone to the formation of stable carbonates or carbon deposits, making them suitable for CO-rich conditions such as automotive exhaust treatment; while CuO, although showing similar performance, has a low absolute value of oxygen storage capacity, suggesting its application limitations. This judgment criterion is consistent with real-world environmental simulations (such as C in Example 2). 18 Combining O experiments with other methods provides a reliable tool for evaluating the durability of catalysts under complex operating conditions.

[0029] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the system flow for a method of testing the oxygen storage capacity of a catalyst according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a method for testing the oxygen storage capacity of a catalyst according to an embodiment of the present invention. Detailed Implementation

[0032] 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.

[0033] Example 1 This embodiment describes a catalyst oxygen storage capacity testing system, which includes a gas supply module, a reaction module, and a control and data acquisition module. The modules are connected via corrosion-resistant pipes (made of quartz or stainless steel), and the outer walls of the pipes are wrapped with an insulation layer to maintain stable gas temperature.

[0034] In this embodiment, the gas supply module consists of a gas source unit and a gas control unit. A central controller sends commands to the gas control unit to provide different gas atmospheres to the pipeline. The gas source unit includes five high-pressure gas cylinders, each storing an isotope gas. 18 O2 (2%) 18 O2 / He), primordial oxygen 16 O2 (2%) 16 The gas cylinders contain O2 / He, reducing gas H2 (5% H2 / He), reducing gas CO (5% CO / He), and carrier gas He (purity > 99.99%). A pressure reducing valve (accuracy ±0.01 bar) is installed at the cylinder outlet. The gas control unit includes a mass flow controller and a check valve; the mass flow controller (MFC, model: Sevenstar CS200A) controls... 18 O2, 16 Flow rates of O2, H2, CO and He (range: 0-200 mL / min, accuracy ±1% FS).

[0035] In this embodiment, the reaction module includes a fixed-bed reactor, a heating device, a temperature monitoring unit, and a pressure control unit. The heating device heats the fixed-bed reactor, while the temperature monitoring unit and pressure control unit provide feedback to the central controller, enabling performance testing under different reaction conditions. The fixed reaction bed is filled with a certain mass of catalyst particles (20-40 mesh) in a U-shaped quartz tube (1 mm inner diameter, 2 mm outer diameter, 25 mm height). Quartz wool is used to fix the catalyst at the inlet and outlet. The heating device is wrapped with a ceramic heating jacket (SG-GL1100L), with a temperature control range of 20-900℃ and an accuracy of ±1℃. The temperature monitoring unit is a K-type thermocouple (inserted into the center of the catalyst bed) connected to a temperature controller (Eurotherm 3216) to record the temperature in real time. The pressure control unit consists of a pressure sensor (Druck PX309) and a back pressure valve installed at the reactor outlet to maintain the reaction system pressure stable at 1-5 atm (accuracy ±0.05 atm).

[0036] In this embodiment, the control and data acquisition module consists of a mass spectrometer detector, a data acquisition system, and a central controller. Gaseous substances in the fixed reaction bed are passed through a gas detector for analysis, and the data, combined with data from the central controller, is fed back to the data acquisition system. The mass spectrometer detector is a TILON LCD / SRD mass spectrometer, which monitors the gas phase in real time. 16 O2 (m / z=32) 16 O 18 O (m / z=34) 18 The partial pressure change of O2 (m / z=36) was measured with a time resolution of 1 s. The data acquisition system utilizes integrated computer software to acquire mass spectrometry signals, temperature, pressure, and flow data in real time, storing them at a frequency of 1 Hz. The central control system employs a PLC control system (Siemens S7-1200) to control the mass flow meter, heating mantle, and valve switches in a coordinated manner, thereby automating the experiment.

[0037] Example 2 18 O / 16 O isotope experiment ( 18 O2): like Figure 1 As shown, the system for testing the oxygen storage capacity of a catalyst provided in this embodiment includes a gas supply module (S1-S2), a reaction module (S3-S6), and a control and data acquisition module (S7-S9). Each module is connected via corrosion-resistant pipes (made of quartz or stainless steel), and the outer wall of the pipes is wrapped with an insulation layer to maintain a stable gas temperature.

[0038] like Figure 2As shown in this embodiment, a method for testing the oxygen storage capacity of a catalyst is provided. The testing method includes... 18 O / 16 Homogeneous exchange of O isotopes (S10-S19) 18 O / 16 O isotope kinetic calculation experiments (S10, S21-S28) and oxygen storage capacity calculation experiments (S29-S30).

[0039] In this embodiment, the 18 O / 16 Homogeneous exchange experiments of O isotopes (S10-S19): ① 150 mg (20-40 mesh) of catalyst is loaded into the fixed-bed reactor (S3); ②The temperature was programmed to rise to 400℃ (S12) under a He atmosphere (50 mL / min); ③ At this temperature, 5% 16 O2 / He (50 mL / min) 16 O2 oxidation experiment (S13) 30 min; ④Then an H2 reduction experiment was carried out for 1 h under a 5% H2 / He atmosphere (50 mL / min) (S15); ⑤ After purging with He atmosphere (50 mL / min) for 30 min, the pretreatment is complete; ⑥ Cool to 150℃ in a He atmosphere (50 mL / min) (S17-S18); ⑦ Introduce 2% [agent] at a total flow rate of 10 mL / min into the fixed-bed reactor (S3). 18 O2 / He and 2% 16 O2 / He; ⑧ Real-time recording at a specific temperature using a mass spectrometer detector (S7) 16 O2 (P-32) 16 O 18 O (P-34) 18 The changes in the concentration of each substance in O2 (P-36) per second over time are recorded until the oxygen partial pressure reaches equilibrium. 18 O / 16 Homogeneous exchange experiment of O isotopes.

[0040] In this embodiment, the 18 O / 16 O isotope dynamics calculation experiments (S10, S21-S28): ① 150 mg (20-40 mesh) of catalyst is loaded into the fixed-bed reactor (S3); ②The temperature was programmed to rise to 300℃ (S21) under a He atmosphere (50 mL / min); ③ At this temperature, 5% H2 / He (50 mL / min) was introduced for 1 h of H2 reduction experiment (S22); ④ After purging with He atmosphere (50 mL / min), the temperature is raised to 400℃ (S24-S25). ⑤ At this temperature, 5% 16 O2 / He (50 mL / min) oxidizes the catalyst surface (S26) for 1 h; ⑥ At this temperature, He (50 mL / min) is introduced to purge for 1 h to remove adsorbed species and complete the pretreatment; ⑦ After pretreatment, introduce 2% of the pretreatment solution into the fixed-bed reactor (S3). 18 O2 / He (10 mL / min); ⑧ Real-time recording at a specific temperature using a mass spectrometer detector (S7) 16 O2 (P-32) 16 O 18 O (P-34) 18 The changes in the concentrations of various substances in O2 (P-36) per second over time were completed. 18 O / 16 O isotope dynamics calculation experiment.

[0041] In this embodiment, the oxygen storage capacity calculation experiment (S29-S30): ① After the isotope experiment, CO (5% CO / He) or H2 (5% H2 / He) gas (50 mL / min) is introduced into the fixed bed reactor (S3) to carry out the CO oxidation experiment (S29) or H2 oxidation experiment (S30) at the reaction temperature. ② Record continuous monitoring of C using a mass spectrometer detector (S7) 16 O (P-28), C 16 O2 (P-44), C 16 O 18 The partial pressure change of O (P-46) generation or H2 (P-2) consumption until the reaction reaches equilibrium; ③ Use the data acquisition system to export relevant data for further analysis and complete the oxygen storage capacity calculation experiment.

[0042] As provided in this embodiment, a method for testing the oxygen storage capacity of a catalyst is described. 18 O / 16 The data from the homogeneous exchange experiment of O isotopes for three catalysts, LCMO, LCMO-0.2 and CuO, are shown in Table 1.

[0043] In this embodiment, the total number of O atoms in the gas phase is calculated according to the ideal gas law (total pressure 1 atm, volume 6.5 × 10⁻⁶).-7 m 3 ).

[0044] In this embodiment, the 18 O / 16 The formula for calculating the initial reaction rate in the homogeneous exchange experiment of O isotopes is as follows: in, Initial reaction rate (at.m) M -2 s -1 ); The total number of O atoms in the gas phase; Metal area of ​​the catalyst (m) 2 ); : 16 O 18 The partial pressure of O (at.); Total pressure ( ).

[0045] Table 1 18 O / 16 Data table of three catalysts, LCMO, LCMO-0.2 and CuO, in the homogeneous exchange experiment of O isotopes. Parameter definition LCMO LCMO-0.2 CuO Total number of O atoms in the gas phase (atoms) <![CDATA[1.41×10 19 ]]> <![CDATA[1.41×10 19 ]]> <![CDATA[1.41×10 19 ]]> <![CDATA[Sample metal area (m 2 ).]]> 10 15 4 Total pressure (atm) 1 1 1 <![CDATA[P 34 partial pressure change rate (atm / min) 0.3 0.5 0.1 <![CDATA[Initial reaction rate (at.•m M -2 •s -1 )]]> <![CDATA[3.53×10 -3 ]]> <![CDATA[3.97×10 -3 ]]> <![CDATA[4.70×10 -4 ]]> <![CDATA[t time 16 O2 partial pressure (atm)]]> 0.04 0.03 0.06 <![CDATA[At time t 16 O 18 Partial pressure of O (atm)]]> 0.03 0.05 0.02 <![CDATA[At time t 16 Partial pressure of O2 (atm)]]> 0.03 0.02 0.02 <![CDATA[Gas phase at time t 18 O atom fraction]]> 0.26 0.25 0.20 Avogadro's constant (atoms / mol) <![CDATA[6.02×10 23 ]]> <![CDATA[6.02×10 23 ]]> <![CDATA[6.02×10 23 ]]> <![CDATA[Specific surface area (m 2 / g)]]> 20 25 10 Ideal gas constant (J / (mol•K)) 8.314 8.314 8.314 <![CDATA[Volume of the reactor heating zone (m 3 )]]> <![CDATA[1.5×10 -7 ]]> <![CDATA[1.5×10 -7 ]]> <![CDATA[1.5×10 -7 ]]> <![CDATA[Non-heating zone volume (m 3 )]]> <![CDATA[5×10 -7 ]]> <![CDATA[5×10 -7 ]]> <![CDATA[5×10 -7 ]]> Heating zone temperature (K) 673 673 673 Temperature of the non-heated zone (K) 298 298 298 <![CDATA[F g Rate of change over time (min) -1 )]]> -0.015 -0.02 -0.008 <![CDATA[Exchange rate (atoms•S -1 •g -1 )]]> <![CDATA[1.21×10 18 ]]> <![CDATA[1.69×10 18 ]]> <![CDATA[3.85×10 17 ]]> In this embodiment, substituting the data from Table 1 into the formula above, the initial reaction rates of the three catalysts, LCMO, LCMO-0.2, and CuO, are 3.53 × 10⁻⁶. -3 3.97×10 -3 and 4.70×10 -4 (at.m) M -2 s -1 ).

[0046] In this embodiment, 18 O / 16 In a homogeneous exchange experiment of O isotopes, the gas phase at each time t is defined as... 18 The formula for calculating the oxygen atom fraction is as follows: in, : in the gas phase at time t 18 O atom fraction; Oxygen partial pressure at time t (at., x=32, 34, 36).

[0047] In this embodiment, substituting the data from Table 1 into the above formula yields the gas phase values ​​of the three catalysts at time t: LCMO, LCMO-0.2, and CuO. 18 The oxygen atom fractions were 0.26, 0.25, and 0.20, respectively.

[0048] In this embodiment, 18 O / 16 The formula for calculating the exchange rate in a homogeneous exchange experiment of O isotopes is as follows: in, : Switching rate (atoms (S) -1 g -1 )); Avogadro's constant (taken as 6.02 × 10⁻⁶) 23 ); Total pressure (at.); Specific surface area of ​​oxides (m²) 2 ); Ideal gas constant (taken as 8.314 J / (mol·K)); , : The volumes of the heated and unheated zones of the reactor are respectively (m³). 3 ); , : These represent the temperatures (K) of the heated and unheated zones of the reactor, respectively.

[0049] In this embodiment, substituting the data from Table 1 into the above formula yields exchange rates of 1.21 × 10⁻⁶ for the three catalysts LCMO, LCMO-0.2, and CuO. 18 1.69×10 18 and 3.85×10 17 (atoms(S) -1 g -1 )).

[0050] This embodiment provides a method for testing the oxygen storage capacity of a catalyst. 18 O / 16 Table 2 shows the data from the O isotope kinetic calculation experiments for three catalysts: LCMO, LCMO-0.2, and CuO.

[0051] Table 2 18 O / 16 Data table of three catalysts, LCMO, LCMO-0.2 and CuO, from O isotope kinetic calculation experiments and oxygen storage capacity experiments. Parameter definition LCMO LCMO-0.2 CuO initial slope <![CDATA[3×10 17 ]]> <![CDATA[5×10 17 ]]> <![CDATA[1×10 17 ]]> <![CDATA[ 18 O concentration (atoms / m³) 3 )]]> <![CDATA[1.08×10 24 ]]> <![CDATA[1.08×10 24 ]]> <![CDATA[1.08×10 24 ]]> <![CDATA[Specific perimeter (m -1 )]]> <![CDATA[4×10 5 ]]> <![CDATA[5×10 5 ]]> <![CDATA[2×10 5 ]]> The number of atoms that diffuse at the start of an exchange reaction. <![CDATA[2.52×10 23 ]]> <![CDATA[4.11×10 23 ]]> <![CDATA[8.0×10 22 ]]> <![CDATA[Surface diffusion coefficient (m 2 •s -1 )]]> <![CDATA[2.67×10 -13 ]]> <![CDATA[4.56×10 -13 ]]> <![CDATA[1.07×10 -13 ]]> Final slope <![CDATA[1.5×10 16 ]]> <![CDATA[2×10 16 ]]> <![CDATA[0.8×10 16 ]]> <![CDATA[Sample density (kg / m 3 )]]> 6500 6500 6310 <![CDATA[Volume diffusion coefficient (m 2 •s -1 )]]> <![CDATA[3.92×10 -19 ]]> <![CDATA[5.67×10 -19 ]]> <![CDATA[1.28×10 -19 ]]> <![CDATA[CO2 integrated volume (L, standard condition)]]> 0.2 0.3 0.1 Sample mass (g) 0.15 0.15 0.15 CO-OSC oxygen storage capacity (mmol / g) 0.059 0.089 0.029 <![CDATA[Oxygen storage capacity of H2-OSC (mmol / g)]]> 0.06 0.092 0.031 In this embodiment, when surface migration is the rate-determining step of oxygen migration, the exchange rate depends on both the surface diffusion coefficient (D) and the surface diffusion coefficient (D). CS It also depends on the specific perimeter (Z) of the particles. N The formula for calculating the number of atoms diffusing at the start of an exchange reaction is as follows: in, The number of atoms that diffuse at the start of the exchange reaction; :isotope 18 The concentration of O; :isotope 18 The radius of O; :isotope 18 O metal particles (n particles / m) 2 The perimeter of ().

[0052] In this embodiment, substituting the data from Table 2 into the formula above, the number of atoms diffused at the start of the exchange reaction of the three catalysts LCMO, LCMO-0.2, and CuO is 2.52 × 10⁻⁶. 23 4.11×10 23 and 8.0×10 22 .

[0053] In this embodiment, when 18 When the O concentration equals the oxygen surface concentration on the metal surface particles, this method is only applicable at the beginning of the exchange reaction. Under this condition... 18 O / 16 The formula for calculating the surface diffusion coefficient in the O isotope dynamics calculation experiment is as follows: in, Surface diffusion coefficient; The initial slope of the curve represents... With function The changes.

[0054] In this embodiment, substituting the data from Table 2 into the formula above, the surface diffusion coefficients of the three catalysts, LCMO, LCMO-0.2, and CuO, are 2.67 × 10⁻⁶. -13 4.56×10 -13 and 1.07×10 -13 (m) 2 ·s -1 ).

[0055] In this embodiment, the final slope of the curve is measured. (When the surface reaches exchange equilibrium) it can be calculated 18 O / 16 The diffusion coefficient of the experimental sample calculated using O isotope dynamics is as follows: in, : Bulk diffusion coefficient; : The final slope of the curve; Catalyst density (kg / m³) 3 ); Catalyst surface area (m²) 2 ); Total oxygen atoms in the gas phase; , , : These represent the gas phase at time t. 18 The atomic fraction of O, and the amount of O in the solid phase at time t. 18 The atomic fraction of O and its content in the gas phase at equilibrium 18 The atomic fraction of O.

[0056] In this embodiment, substituting the data from Table 2 into the formula above, the diffusion coefficients of the three catalysts, LCMO, LCMO-0.2, and CuO, are 3.92 × 10⁻⁶. -19 5.67×10 -19 and 1.28×10 -19 (m) 2 ·s -1 ).

[0057] In this embodiment, the oxygen storage capacity calculation experiment (S29-S30) involves introducing CO (5% CO / He) or H2 (5% H2 / He) gas (50 mL / min) into the fixed-bed reactor (S3) after the isotope experiment, and conducting the CO oxidation experiment (S29) or H2 oxidation experiment (S30) at the reaction temperature. The CO is continuously monitored using a mass spectrometer detector (S7). 16 O (P-28), C 16 O2 (P-44), C 16 O 18 The partial pressure changes of O (P-46) generation or H2 (P-2) consumption are recorded until the reaction reaches equilibrium. The relevant data are then exported using a data acquisition system for further analysis.

[0058] in, , : These represent the oxygen storage capacity of the catalyst (mmol / g) calculated by different methods. : Flow rate of the reaction gas during the reaction process (mL / min); The volume of 1 mol of an ideal gas is 22.4 L; Mass of catalyst (g); : The concentration of the reducing gas H2 used.

[0059] In this embodiment, C is generated based on data analysis. 16 O2, C 16 O 18 The integral of O or H2 16 O, H2 18 The oxygen storage capacity (CO-OSC) or H2-OSC) of the catalyst is calculated by integrating the O content. Substituting the data from Table 2 into the formula above, the oxygen storage capacities of the three catalysts, LCMO, LCMO-0.2, and CuO, are obtained: CO-OSC were 0.059, 0.089, and 0.029 (mmol / g), respectively. The H2-OSC values ​​were 0.060, 0.092, and 0.031 (mmol / g), respectively.

[0060] In this embodiment, the CO-OSC is more directly related to applications in CO-rich environments (such as the oxygen-deficient / oil-rich stage in automobile exhaust treatment, and certain industrial process exhaust gases). The H2-OSC is more directly related to applications in hydrogen-rich environments (such as fuel cell exhaust treatment, and certain catalytic reforming processes).

[0061] In this embodiment, by comparing the oxygen storage capacity of the two cases using CO-OSC and H2-OSC, we can conclude that: If H2-OSC >> CO-OSC: This may indicate that the material is sensitive to CO disproportionation and carbon deposition occurs, or that the surface is easily deactivated under CO atmosphere; If H2-OSC≈CO-OSC: it indicates that the material has strong resistance to carbon deposition, or weak surface alkalinity (it is not easy to form stable carbonates).

[0062] In this embodiment, CO-OSC and H2-OSC are compared: LCMO: H2-OSC (0.060) ≈ CO-OSC (0.059) → Strong resistance to carbon buildup LCMO-0.2: H2-OSC (0.092) ≈ CO-OSC (0.089) → Strong resistance to carbon buildup CuO:H2-OSC (0.031) ≈CO-OSC (0.029) → Strong resistance to carbon buildup Activity trend: LMCO-0.2 > LCMO > CuO (based on a comprehensive judgment of parameters such as initial reaction rate, exchange rate, diffusion coefficient, and oxygen storage capacity).

[0063] Example 3 CO 18 O labeling experiment (C 18 O): In this embodiment, 2% C is added to the gas supply module (S1-S2). 18O / He (replacing the original text) 18 O2 / He), retain 2% 16 O2 / He, 5%H2 / He, and He (carrier gas) provide 18 O-labeled CO gas source is used for studying oxygen migration in CO disproportionation or oxidation reactions.

[0064] In this embodiment, the CO experiment needs to be controlled at a temperature ≤400℃ to prevent interference from the Boudouard reaction (2CO→C+CO2).

[0065] In this embodiment, after the catalyst is reduced by H2, 2% C is introduced. 18 O / He (50 mL / min, 400℃, 30 min), making 18 O enters the catalyst lattice via CO adsorption / dissociation. Switch to 50 mL / min 2% 16 O2 / He makes the surface 18 O and gas phase 16 O2 undergoes exchange to produce C. 16 O 18 O (m / z=46) and release C 16 O (m / z=28). Monitoring C in the gas phase. 16 O (m / z=28), C 18 O (m / z=30) 16 O2 (m / z=32), C 16 O2 (m / z=44), C 16 O 18 Changes in partial pressure of O (m / z=46).

[0066] In this embodiment, C 18 The O-OSC calculation method is as follows: in, : Indicates the oxygen storage capacity of the catalyst (mmol / g); : Flow rate of the reaction gas during the reaction process (mL / min); The volume of 1 mol of an ideal gas is 22.4 L; Mass of catalyst (g); The gas produced contains C 16 O2 concentration; The gas produced contains C 16 O 18 The concentration of O.

[0067] In this embodiment, C is generated based on data analysis. 16 O2, C 16 O 18The oxygen storage capacity C of the catalyst is calculated by integrating O. 18 O-OSC. Substituting the data from Table 2 into the formula above, we obtain the oxygen storage capacity of the three catalysts: LCMO, LCMO-0.2, and CuO. C 18 O-OSC were 0.061, 0.088, and 0.030 (mmol / g), respectively.

[0068] In this embodiment, the C 18 O-OSC and 18 O / 16 The results obtained from CO-OSC calculations after passing CO through the O isotope exchange experiment are similar. 18 The O labeling has been extended from O2 to CO, and this method can cover carbon-containing fuel exhaust gases (directly using C). 18 O simulates oxygen-deficient (vehicle exhaust (CO-rich)) environments, quantifies the catalyst's oxygen release / storage capacity under CO atmosphere, and more realistically reflects the actual operating performance of TWC catalysts, providing a precise analytical tool for the oxygen migration behavior of catalysts in real environments.

[0069] Example 4 H2O 18 O labeling experiment (H2) 18 O): In this embodiment, a steam generation module is added to the gas supply module (S1-S2) to generate H2. 18 O liquid is injected into a temperature-controlled evaporator to generate H2. 18 O(g) is carried into the reactor by the He carrier gas.

[0070] In this embodiment, the H2O experiment must ensure that the steam is completely vaporized to avoid condensation and blockage of the pipeline.

[0071] In this embodiment, the evaporation temperature in the steam generation module is 100°C, the steam flow rate is 2.5 mL / min, and the carrier gas flow rate is 47.5 mL / min.

[0072] In this embodiment, after the catalyst is reduced by H2, 5% H2 is introduced. 18 O / He (400℃, 30min), making 18 O enters the catalyst through adsorption via the dissociation of water molecules. Switch to 2%. 16 O2 / He, surface 18 O and gas phase 16 O2 exchange produces a mixture of water molecules (H2). 16 O 18 O). Monitoring H2 16 O (m / z=18), H2 18 O (m / z=20) 16O2 (m / z=32), H2 16 O 18 Changes in partial pressure of O (m / z=36).

[0073] In this embodiment, at time t, in the gas phase 18 The calculation methods for the O atom fraction and exchange rate are as follows: in, : in the gas phase at time t 18 O atom fraction; Oxygen partial pressure at time t, based on m / z = 20 (H2) 18 O) and m / z=18 (H2) 16 O) Calculation 18 O atomic fraction (P) 36 H2 16 O 18 O partial pressure (m / z=36), contributes 1. 18 O atoms).

[0074] In this embodiment, substituting the data from Table 1 into the above formula yields the gas phase values ​​of the three catalysts at time t: LCMO, LCMO-0.2, and CuO. 18 The oxygen atom fractions were 0.25, 0.25, and 0.18, respectively.

[0075] in, : Switching rate (atoms (S) -1 g -1 )); Avogadro's constant (taken as 6.02 × 10⁻⁶) 23 ); Total pressure (at.); Specific surface area of ​​oxides (m²) 2 ); Ideal gas constant (taken as 8.314 J / (mol·K)); , : The volumes of the heated and unheated zones of the reactor are respectively (m³). 3 ); , : These represent the temperatures (K) of the heated and unheated zones of the reactor, respectively.

[0076] In this embodiment, substituting the data from Table 1 into the above formula yields exchange rates of 1.18 × 10⁻⁶ for the three catalysts LCMO, LCMO-0.2, and CuO. 18 1.69×10 18 and 3.69×10 17 (atoms(S)-1 g -1 )).

[0077] In this embodiment, the and and 18 O / 16 O isotope experiments and The calculated results are similar. By... 18 The O labeling has been extended from O2 to H2O, and this method can cover water-containing fuel cells (via H2O). 18 O exchange experiments were conducted to elucidate oxygen migration pathways involving water molecules (e.g., SOFC cathode materials) and to assess the impact of water vapor on oxygen diffusion kinetics. Chemical looping hydrogen production (using H2) was also employed. 18 O-labeling, tracking the lattice oxygen exchange rate of oxygen supports (such as Fe2O3) in water splitting reactions, and optimizing the cycling stability of oxygen supports, etc., provide a precise analytical tool for the oxygen migration behavior of catalysts in real environments.

[0078] Example 5 The catalyst oxygen storage capacity testing method described in this embodiment includes a synergistic diagnostic process of pretreatment, isotope exchange, kinetic analysis, oxygen storage capacity testing, and anti-carbon deposition analysis. Each step has a continuous causal relationship in terms of physicochemical mechanism, forming an inseparable dynamic analysis system.

[0079] S1: Pretreatment stage, a standardized initial surface state is established through oxidation-reduction cycle to ensure comparability between different samples; S2: Isotope exchange stage, utilizing... 18 O / 16 The real-time interchange behavior of O dual isotope gases captures the transient process of oxygen atoms migrating between the surface and the lattice. S3: Dynamic analysis stage, based on gas phase 16 O2, 16 O 18 O、 18 The time-dependent change in the partial pressure of O2, and the inversion of the surface diffusion coefficient (D). CS ) and bulk diffusion coefficient (D CB This quantitatively describes the relationship between oxygen migration rate and channel coupling. S4: Oxygen storage capacity measurement stage, 5% CO / He or 5% H2 / He gas is introduced, the dynamic partial pressure change of CO2 or H2 consumption is recorded, and the CO-OSC and H2-OSC values ​​are calculated. S5: Anti-carbon deposition analysis stage, evaluating the catalyst's anti-carbon deposition performance based on the H2-OSC to CO-OSC ratio.

[0080] In this embodiment, the H2-OSC / CO-OSC ratio is between 1.0 and 1.2, or the difference between the two is less than 0.005 mmol·g. -1 When the ratio is greater than 1.5 or the difference is greater than 0.01 mmol·g, it indicates that oxygen migration on the catalyst surface is smooth and that the catalyst has strong resistance to carbon deposition; when the ratio exceeds 1.5 or the difference is greater than 0.01 mmol·g, it indicates that oxygen migration on the catalyst surface is smooth and that the catalyst has strong resistance to carbon deposition. -1 When the time is right, it indicates that oxygen migration on the catalyst surface is restricted or deactivated under a CO atmosphere.

[0081] In this embodiment, the oxidation-reduction pretreatment includes: at 5% 16 Oxidation was carried out in O2 / He at 400 °C for 30 min; reduction was carried out in 5% H2 / He at 400 °C for 60 min; and cooling to the target temperature was carried out under He purging.

[0082] In this embodiment, in the isotope kinetics experiment, the surface diffusion coefficient D CS Based on gas phase 16 O 18 Calculation of the initial change rate of partial pressure O, and the bulk diffusion coefficient D. CB Calculated based on the final slope of the curve.

[0083] In this embodiment, by continuously completing steps S1–S4 in the same reaction system, the oxygen exchange rate, surface diffusion, bulk diffusion, and oxygen storage capacity can be measured simultaneously, avoiding systematic errors caused by operating multiple instruments.

[0084] In this embodiment, the method can be further extended to C 18 O or H2 18 O2 was used as a labeling gas in experiments to study oxygen migration behavior in carbon- or water-containing environments.

[0085] The above methods are executed sequentially and data is shared within the same experimental system, ensuring a holistic characterization of oxygen storage-release behavior and avoiding systematic errors introduced by traditional multi-instrument, multi-batch testing.

[0086] Compared to traditional oxygen pulse titration and H2-TPR methods, which can only determine the "total oxygen", the system of this invention can analyze the co-migration mechanism of surface and bulk oxygen.

[0087] For example, under the same temperature (400 °C) and oxygen partial pressure conditions, the conventional method yielded an oxygen storage capacity of only 0.06 mmol / g for the LCMO catalyst, while this method further separated D... CS ≈ 2.7 × 10 -13 m 2 ·s -1 D CB ≈ 3.9×10 -19 m 2·s -1 The surface-bulk diffusion combination parameters reveal a "bottleneck effect" where surface oxygen activation is rapid but bulk diffusion is limited; Comparison of D of CuO sample CS ≈1.1×10 -13 m 2 ·s -1 D CB ≈1.3×10 -19 m 2 ·s -1 It is evident that the testing system of this invention can distinguish the synergistic and restrictive relationships of surface-bulk oxygen migration in catalysts with different structures, a mechanism that cannot be directly observed using traditional methods.

[0088] In summary, this invention proposes a catalyst oxygen storage capacity testing system and method, including a gas supply module, a reaction module, and a control and data acquisition module, providing... 18 O-labeled gas, 16 The method uses standard oxygen, reducing gas, and inert carrier gas, with precise control of flow rate, temperature, and pressure. The method includes... 18 O / 16 O isotope homogeneous exchange experiments, kinetic calculation experiments, and oxygen storage capacity calculation experiments were conducted using real-time mass spectrometry monitoring. 16 O2, 16 O 18 O、 18 This invention calculates the oxygen exchange rate, surface diffusion coefficient (DCS), and bulk diffusion coefficient (DCB) based on changes in O2 partial pressure, and then calculates the oxygen storage capacity (CO-OSC and H2-OSC) based on CO oxidation or H2 reduction reactions. This invention simultaneously analyzes the dynamic behavior of oxygen, filling a gap in traditional methods. It offers advantages such as high precision and multiple parameters, and is applicable to fields such as automotive exhaust purification and industrial waste gas treatment, promoting a shift in catalyst development from empirical screening to rational design.

[0089] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A catalyst oxygen storage capacity testing system, characterized in that, include: Gas supply module, configured to provide including 18 O isotope-labeled gases, including 16 The system uses oxygen as a reference, a variety of reducing gases, and an inert carrier gas, with precise proportioning and control of the gas flow rates. The reaction module is fluidly connected to the gas supply module through a corrosion-resistant pipeline to form an airtight reaction space. The reaction space is equipped with a fixed catalyst bed and has controllable heating, temperature monitoring and pressure stabilization functions. The control and data acquisition module is connected to the gas supply module and the reaction module via signal transmission, and automatically executes functions including... 18 O / 16 O isotopes undergo homogeneous exchange. 18 O / 16 A serialized experimental procedure for oxygen isotope kinetic analysis and oxygen storage capacity measurement; the isotope exchange process was monitored and recorded online in real time using a mass spectrometer. 16 O2, 16 O 18 O、 18 The partial pressure kinetics curve of O2, and the dynamic partial pressure data of CO oxidation products or H2 consumption during the oxygen storage capacity measurement process; The system, through the execution of the serialized experimental procedure and the acquisition of the dynamic partial pressure data, can simultaneously analyze the oxygen exchange kinetics, oxygen surface migration and bulk diffusion behavior, and total oxygen storage capacity of the catalyst.

2. The catalyst oxygen storage capacity testing system as described in claim 1, characterized in that, The gas supply module includes: The gas supply unit consists of five independent pressurized gas cylinders, each containing 2% premixed gas. 18 O2 / He gas, 2% 16 O2 / He gas, 5% H2 / He gas, 5% CO / He gas, and He with a purity > 99.99%; The gas control unit includes multiple parallel mass flow controllers with a range of 0-200 mL / min and an accuracy of ±1% FS, as well as one-way valves installed in each gas path, for achieving accurate gas metering and flow direction control.

3. The catalyst oxygen storage capacity testing system as described in claim 1, characterized in that, The reaction module includes: A fixed-bed reactor is constructed from a U-shaped quartz tube filled with 20-40 mesh granular catalyst to be tested, and the catalyst bed is axially fixed by quartz wool. The tubular heating device, which is installed outside the fixed bed reactor, can perform programmed temperature control within a temperature range of 20℃ to 900℃, with a temperature control accuracy of ±1℃. The temperature sensing unit, which is a K-type thermocouple inserted into the geometric center of the catalyst bed, is used to directly measure and feedback the real-time temperature of the reaction zone. The pressure control unit consists of an absolute pressure sensor and an electric back pressure valve located at the reactor outlet. It is used to dynamically stabilize the absolute pressure of the system between 1 atm and 5 atm, with a control accuracy of ±0.05 atm.

4. The catalyst oxygen storage capacity testing system as described in claim 1, characterized in that, The control and data acquisition module includes: The mass spectrometer detector is configured to monitor in real time with a time resolution of 1 second. 16 O2, 16 O 18 O、 18 Changes in the partial pressure of O2; The central controller stores preset experimental timing logic, which is used to send control commands to the mass flow controller, the tubular heating device and the electric back pressure valve to realize fully automatic process operation. The data acquisition and storage unit synchronously records all signals from the mass spectrometer, the temperature sensing unit, the pressure control unit, and the mass flow controller at a sampling frequency of 1 Hz, and generates a timestamp-aligned data file.

5. The catalyst oxygen storage capacity testing system as described in claim 1, characterized in that, The corrosion-resistant pipes connecting the various modules are made of quartz or austenitic stainless steel, and all pipes exposed to the gas path are covered with a heat insulation layer to minimize the impact of ambient temperature fluctuations on gas transmission and reaction.

6. A method for testing the oxygen storage capacity of a catalyst based on the system described in any one of claims 1-5, characterized in that, Includes the following steps: S1: 18 O / 16 Homogeneous exchange experiment of O isotopes: S1.1: The catalyst is pretreated by a redox cycle to establish a standardized initial surface state; S1.2: Under preset isothermal reaction conditions, a 2% catalyst pulse is introduced. 18 O2 / He and 2% 16 A mixture of O2 and He gases; S1.3: Online monitoring 16 O2, 16 O 18 O、 18 The partial pressure of O2 evolves over time until it reaches isotope exchange equilibrium. S2: 18 O / 16 O isotope dynamics calculation experiment: S2.1: The catalyst is subjected to deep reduction-surface oxidation pretreatment to enrich surface active oxygen and clear bulk mobile oxygen. S2.2: Under the stated isothermal reaction conditions, 2% is introduced into the catalyst. 18 O2 / He gas; S2.3: Online monitoring 16 O2, 16 O 18 O、 18 The evolution of O2 partial pressure over time was used to capture the initial dynamics of oxygen migration from the surface to the bulk phase; S3: Experiment on calculating oxygen storage capacity: S3.1: After the isotope exchange is completed, under the isothermal reaction conditions, the reaction atmosphere is switched to 5% CO / He or 5% H2 / He; S3.2: Online monitoring of products along the CO oxidation pathway, including C 16 O, C 16 O2, C 16 O 18 The partial pressure of O, or the partial pressure of H2 consumption in the H2 reduction pathway, until the reaction is complete; The oxygen exchange rate is calculated based on the data from step S1, the surface and bulk oxygen diffusion coefficients are calculated based on the data from step S2, and the oxygen storage capacity using CO and H2 as probes is calculated based on the data from step S3.

7. The method for testing the oxygen storage capacity of a catalyst as described in claim 6, characterized in that, The oxidation-reduction cycle pretreatment in step S1 specifically includes: heating to 400℃ at a rate of 10℃ / min under a He atmosphere at a rate of 50 mL / min and stabilizing; then switching to a 5% oxidation-reduction cycle at a rate of 50 mL / min. 16 Oxidation was carried out in an O2 / He atmosphere for 30 minutes; then reduction was carried out in a 5% H2 / He atmosphere at a flow rate of 50 mL / min for 60 minutes; finally, the atmosphere was switched back to He to purge for 30 minutes, and the temperature was programmed to decrease to the target reaction temperature at a rate of 10 °C / min. In step S1 18 O / 16 The formula for calculating the initial reaction rate in a homogeneous O isotope exchange experiment is: in, Initial reaction rate; The total number of O atoms in the gas phase; : The metal surface area of ​​the catalyst; : 16 O 18 The partial pressure of O; Total pressure ; In the gas phase at each time t 18 The formula for calculating the oxygen atom fraction is as follows: in, : in the gas phase at time t 18 O atom fraction; Oxygen partial pressure at time t; The formula for calculating the switching rate is as follows: in, : Switching rate; Avogadro's constant; Total pressure; Specific surface area of ​​oxides; Ideal gas constant; , : These represent the volumes of the heated and unheated zones of the reactor, respectively; , : These represent the temperatures of the heated and unheated zones of the reactor, respectively.

8. The method for testing the oxygen storage capacity of a catalyst as described in claim 6, characterized in that, The deep reduction-surface oxidation pretreatment in step S2 specifically includes: programmed heating to 300°C in a He atmosphere at 50 mL / min; switching to a 5% H2 / He atmosphere at 50 mL / min and maintaining for 60 minutes for deep reduction; purging with a He atmosphere for 30 minutes, followed by programmed heating to 400°C at a rate of 10°C / min; switching to a 5% H2 / He atmosphere at 50 mL / min. 16 Surface oxidation was carried out in an O2 / He atmosphere for 60 minutes; finally, the surface was purged in a He atmosphere for 60 minutes to ensure that only surface-adsorbed oxygen species were present. Step S2.1 specifically includes: heating the catalyst under a He atmosphere, reducing it by introducing 5% H2 / He, purging it with He, and then heating it again, introducing 5% H2 / He at that temperature. 16 O2 / He oxidation, followed by He purging and then 2% oxygen. 18 O2 / He, real-time recording of oxygen partial pressure changes; The surface diffusion coefficient The calculation formula is: in, The number of atoms that diffuse at the start of the exchange reaction; :isotope 18 The concentration of O; :isotope 18 The radius of O; :isotope 18 The perimeter of the metal particle of O; in, Surface diffusion coefficient; The initial slope of the curve represents... With function Changes; The bulk diffusion coefficient The calculation formula is: in, : Bulk diffusion coefficient; : The final slope of the curve; Catalyst density; Catalyst surface area; Total oxygen atoms in the gas phase; , , : These represent the gas phase at time t. 18 The atomic fraction of O, and the amount of O in the solid phase at time t. 18 The atomic fraction of O and its content in the gas phase at equilibrium 18 The atomic fraction of O.

9. The method for testing the oxygen storage capacity of a catalyst as described in claim 6, characterized in that, After step S3 is completed, 5% CO / He or 5% H2 / He is introduced, and C is monitored. 16 O, C 16 O2, C 16 O 18 The partial pressure change of O generation or H2 consumption reaches equilibrium; the formula for calculating oxygen storage capacity is: in, , : These represent the oxygen storage capacity of the catalyst calculated using different methods; The flow rate of the reactant gas during the reaction process; The volume of 1 mol of an ideal gas is 22.4 L; : The quality of the catalyst; : The concentration of the reducing gas H2 used.

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