A method for adsorbing NO in automobile exhaust using MgAl composite metal oxide x
By constructing molecular unit cell models of MgAl composite metal oxide and NOx, and using DFT calculations to determine the optimal molecular orientation, the problems of long synthesis cycle and resource waste of MgAl composite metal oxide low-temperature NOx catalysts in existing technologies are solved, and efficient prediction of NOx adsorption performance and material design are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KUNMING UNIV OF SCI & TECH
- Filing Date
- 2026-01-19
- Publication Date
- 2026-06-12
AI Technical Summary
In existing technologies, the synthesis process of MgAl composite metal oxide low-temperature NOx catalysts is time-consuming and resource-intensive. The preferential adsorption order of NO, NO2, and N2O under different molecular orientations is unclear, resulting in a high failure rate.
Using Materials Studio and the VASP software package combined with the DFT method, molecular unit cell models of MgAl composite metal oxide and NOx were built, their structures were optimized, and adsorption energies were calculated to determine the optimal molecular orientation (the N-terminus or O-terminus close to any metal atom on the MgAl composite metal oxide), providing atomic-level basis for material preparation.
This method enables the rapid determination of the optimal molecular orientation of MgAl composite metal oxides, shortens the research and development cycle, and improves the accuracy of NOx adsorption performance prediction and synthesis efficiency of the materials.
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Figure CN122201494A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of air pollution control technology, specifically to a method for adsorbing NOx in automobile exhaust using MgAl composite metal oxides. Background Technology
[0002] NOx in vehicle exhaust is a core precursor to photochemical smog, acid rain, and PM2.5, resulting in substantial annual environmental remediation and health expenditures. Modern gasoline vehicles emit approximately 5%–10% of the total conventional pollutants in their exhaust. For China VI diesel trucks, NOx emissions account for approximately 1 / 4–1 / 3 of the conventional pollutants in their exhaust, making it the single largest pollutant by mass. Installing aftertreatment devices is one of the effective ways to control NOx emissions. Among these, adsorption-catalysis integrated materials are widely used in diesel vehicle exhaust systems due to their simple operation, low cost, and ability to operate across a full temperature range. MgAl composite metal oxides (MgAl-MMO) are obtained through the topological transformation of layered bimetallic hydroxides and possess lamellar Mg... 2+ / Al 3+ Advantages such as adjustable ratio, abundant surface oxygen vacancies, and well-developed mesoporous structure make it suitable for use in low-temperature NO2 combustion in engines. x The NO capture field shows great potential. Numerous studies have demonstrated that suitable MgAl composite metal oxide catalysts possess both NO capture and NO capture capabilities. x And activated and oxidized to NO 2- / NO 3- Its dual function enables efficient adsorption-regeneration cycle. In existing technologies, MgAl composite metal oxides for low-temperature NO... x The catalyst process involves first synthesizing LDH precursors with different Mg / Al ratios and interlayer anions. After calcination to obtain MgAl composite metal oxides, the samples are characterized for phase and microstructure using XRD, BET, and SEM. Adsorption capacity is then tested using fixed-bed breakthrough experiments, and regeneration performance is verified through temperature-programmed desorption (TPD). However, the preferential adsorption order of NO, NO2, and N2O under different molecular orientations (N-terminus or O-terminus close to any metal atom in the MgAl composite metal oxide) has not been systematically clarified. If the synthesized material exhibits high adsorption capacity for the target NO... x If the species adsorption energy is too low or the orientation is mismatched, the experiment will fail. Therefore, this trial-and-error method based on extensive "synthesis-characterization-evaluation" has a long experimental cycle, a blind target, and is prone to resource waste, which is not conducive to advancing the low-temperature NO adsorption of MgAl composite metal oxides. x Research and application of adsorption materials. Summary of the Invention
[0003] The purpose of this application is to provide a method for adsorbing NOx in automobile exhaust using MgAl composite metal oxides, and the specific technical solution is as follows:
[0004] A method for adsorbing NOx from automobile exhaust using MgAl composite metal oxides includes: S1, In practical applications, Materials are used. MaterialsStudio was used to build molecular unit cell models of MgAl composite metal oxide and NOx respectively; S2, in practical applications, the DFT in the VASP package was used to optimize the structure of the molecular unit cell models of MgAl composite metal oxide and NOx built in S1 to obtain the stable configuration and energy of MgAl composite metal oxide and NOx; S3, based on the stable configuration and energy of MgAl composite metal oxide and NOx obtained in S2, in practical applications, the MaterialsStudio program was used to build the adsorption configuration of NOx on MgAl composite metal oxide and the adsorption configuration with the N / O end facing any metal atom on MgAl composite metal oxide respectively; S4, in practical applications, the DFT in the VASP package was used to calculate the energy of the adsorption configuration of NOx on MgAl composite metal oxide built in S3 respectively to obtain the adsorption energy data of MgAl composite metal oxide for NOx; S5, based on the adsorption energy data of MgAl composite metal oxide for each NOx obtained in S4, the adsorption energy of MgAl composite metal oxide for each NOx was analyzed and evaluated.
[0005] In S1, the MgAl composite metal oxide, MgAl-LDH, releases interlayer water, removes surface hydroxyl groups, and eliminates anions as the calcination temperature increases. Finally, at around 800℃, the layered structure collapses to form the MgAl composite metal oxide, whose surface is used for adsorption calculations. NOx in S1 includes NO, NO2, and N2O.
[0006] When optimizing the MgAl composite metal oxide and NOx molecular cell models built in S1 using the DFT function in the VASP package in S2, the following steps are taken: importing the MgAl composite metal oxide cell and the molecular configurations of NO, NO2 and N2O into the DFT function in the VASP package for calculation to obtain the energy of the stable MgAl composite metal oxide cell model and the NO, NO2 and N2O models.
[0007] In S3, when constructing the adsorption configuration of NO by MgAl composite metal oxide, the TOP sites of any metal atoms on the surface of the MgAl composite metal oxide catalyst were selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst were constructed respectively. When constructing the adsorption configuration of NO2 by MgAl composite metal oxide, the TOP sites of any metal atoms on the surface of the MgAl composite metal oxide catalyst were selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst were constructed respectively. When constructing the adsorption configuration of N2O by MgAl composite metal oxide, the TOP sites of any metal atoms on the surface of the MgAl composite metal oxide catalyst were selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst were constructed respectively.
[0008] In S3, when constructing the adsorption configuration of NO by MgAl composite metal oxide, bridge sites of any metal atom on the surface of the MgAl composite metal oxide catalyst were selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst were constructed respectively. When constructing the adsorption configuration of NO2 by MgAl composite metal oxide, bridge sites of any metal atom on the surface of the MgAl composite metal oxide catalyst were selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst were constructed respectively. When constructing the adsorption configuration of N2O by MgAl composite metal oxide, bridge sites of any metal atom on the surface of the MgAl composite metal oxide catalyst were selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst were constructed respectively.
[0009] In step S4, when calculating the adsorption energy of NO on the MgAl composite metal oxide, the two adsorption configurations of NO adsorbed on the MgAl composite metal oxide are imported into the VASP program package for DFT structure optimization to obtain stable adsorption configurations and energy data, and the adsorption energies of the two adsorption configurations are calculated. Similarly, when calculating the adsorption energy of NO2 on the MgAl composite metal oxide, the two adsorption configurations of NO2 adsorbed on the MgAl composite metal oxide are imported into the VASP program package for DFT structure optimization to obtain stable adsorption configurations and energy data, and the adsorption energies of the two adsorption configurations are calculated. Likewise, when calculating the adsorption energy of N2O on the MgAl composite metal oxide, the two adsorption configurations of N2O adsorbed on the MgAl composite metal oxide are imported into the VASP program package for DFT structure optimization to obtain stable adsorption configurations and energy data, and the adsorption energies of the two adsorption configurations are calculated.
[0010] The advantages of this application lie in its ability to rapidly determine the optimal molecular orientation (any metal atom near the N-terminus or O-terminus on the MgAl composite metal oxide), providing atomic-level basis for selecting the Mg / Al ratio, interlayer anions, and calcination temperature, thus enabling the rational design of integrated adsorption-catalysis materials. NOx adsorption performance can be predicted before material preparation, shortening the research and development cycle. Attached Figure Description
[0011] Figure 1 This is a flowchart of the method of the present invention.
[0012] Figure 2 This is a schematic diagram of the structure of MgAl composite metal oxide.
[0013] Figure 3 This is a schematic diagram of the molecular models of NO, NO2, and N2O.
[0014] Figure 4 The adsorption configuration of NO at the N / O end of the Al17 atom TOP site is shown for the adsorption of NO by the MgAl composite metal oxide.
[0015] Figure 5 The adsorption configuration of NO2 at the N / O end of the Al17 atom TOP site is shown for the adsorption of NO2 by the MgAl composite metal oxide.
[0016] Figure 6 The adsorption configuration of N2O at the N / O end of the Al17 atom TOP site is shown for the adsorption of N2O by the MgAl composite metal oxide.
[0017] Figure 7 The adsorption configuration of NO at the N / O end of the Al17 atom Bridge site is shown for the adsorption of NO by the MgAl composite metal oxide.
[0018] Figure 8The adsorption configuration of NO2 at the N / O end of the Bridge site on Al17 atom for MgAl composite metal oxide is shown.
[0019] Figure 9 The adsorption configuration of N2O at the N / O end of the Bridge site on Al17 atoms for N2O adsorption in MgAl composite metal oxides. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.
[0021] like Figure 1 As shown, a method for adsorbing NOx in automobile exhaust using MgAl composite metal oxides includes:
[0022] like Figure 2 and Figure 3 As shown in Figure S1, Material Studio was used to build molecular unit cell models of MgAl composite metal oxide and NOx, respectively. Specifically, the MgAl composite metal oxide, MgAl-LDH, releases interlayer water, removes surface hydroxyl groups, and eliminates anions as the calcination temperature increases, eventually collapsing at around 800℃ to form MgAl composite metal oxide (MgAl-MMO), whose surface is used for adsorption calculations. NOx includes NO, NO2, and N2O.
[0023] S2. Optimize the MgAl composite metal oxide and NOx molecular unit cell models built in S1 using the DFT function in the VASP package to obtain stable configurations and energies for the MgAl composite metal oxide and NOx. Specifically, optimizing the MgAl composite metal oxide and NOx molecular unit cell models built in S1 using the DFT function in the VASP package includes: importing the MgAl composite metal oxide unit cell and the molecular configurations of NO, NO2, and N2O into the DFT function in the VASP package for calculation to obtain stable MgAl composite metal oxide unit cell models and the energies of NO, NO2, and N2O models.
[0024] S3. Based on the stable configurations and energies of the MgAl composite metal oxide and NOx obtained in S2, the adsorption configurations of NOx on the MgAl composite metal oxide and the adsorption configurations with the N / O ends facing any metal atom on the MgAl composite metal oxide were constructed using Materials Studio. Specifically, such as... Figure 4 ,Figure 5 and Figure 6 As shown, when constructing the adsorption configuration for NO adsorption by MgAl composite metal oxides, the TOP sites of any metal atoms on the surface of the MgAl composite metal oxide catalyst are selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst are constructed respectively. Similarly, when constructing the adsorption configuration for NO2 adsorption by MgAl composite metal oxides, the TOP sites of any metal atoms on the surface of the MgAl composite metal oxide catalyst are selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst are constructed respectively. Another method is as follows: Figure 7 , Figure 8 and Figure 9 As shown, when constructing the adsorption configuration of NO by MgAl composite metal oxide, bridge sites of any metal atom on the surface of the MgAl composite metal oxide catalyst were selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst were constructed respectively. When constructing the adsorption configuration of NO2 by MgAl composite metal oxide, bridge sites of any metal atom on the surface of the MgAl composite metal oxide catalyst were selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst were constructed respectively. When constructing the adsorption configuration of N2O by MgAl composite metal oxide, bridge sites of any metal atom on the surface of the MgAl composite metal oxide catalyst were selected for adsorption, and adsorption configurations with the N-terminus and O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst were constructed respectively.
[0025] S4. Using the DFT function in the VASP package, calculate the energies of the NOx adsorption configurations on the MgAl composite metal oxide constructed in S3, obtaining the adsorption energy data of NOx on the MgAl composite metal oxide. Specifically, when calculating the energy of the NO adsorption configurations on the MgAl composite metal oxide, import the two NO adsorption configurations of the MgAl composite metal oxide into the VASP package for DFT structure optimization to obtain stable adsorption configurations and energy data, and calculate the adsorption energies of the two adsorption configurations; when calculating the energy of the NO2 adsorption configurations on the MgAl composite metal oxide, import the two NO2 adsorption configurations of the MgAl composite metal oxide into the VASP package for DFT structure optimization to obtain stable adsorption configurations and energy data, and calculate the adsorption energies of the two adsorption configurations; when calculating the energy of the N2O adsorption configurations on the MgAl composite metal oxide, import the two N2O adsorption configurations of the MgAl composite metal oxide into the VASP package for DFT structure optimization to obtain stable adsorption configurations and energy data, and calculate the adsorption energies of the two adsorption configurations.
[0026] S5. Based on the adsorption energy data of MgAl composite metal oxides for each NOx obtained in S4, analyze and evaluate the adsorption energy of MgAl composite metal oxides for each NOx.
[0027] To make this application easier to understand, further explanation is provided below with reference to specific embodiments.
[0028] Table 1 shows the stable structure energies of MgAl composite metal oxides and NO, NO2, and N2O molecules in Examples 1 and 2. Table 2 shows the stable structure energies and adsorption energies of the N / O ends of NO, NO2, and N2O molecules adsorbed by MgAl composite metal oxides at the TOP sites. By comparing and analyzing the data in Table 2, it can be concluded that when MgAl composite metal oxides adsorb NO, the adsorption energy near the Al17 atom at the N end is -0.849 eV, and the adsorption energy near the Al17 atom at the O end is -0.555 eV, indicating that the adsorption capacity of MgAl composite metal oxides near the Al17 atom at the N end is stronger when adsorbing NO. When MgAl composite metal oxides adsorb NO2, the adsorption energy near the Al17 atom at the N end is -4.658 eV, and the adsorption energy near the Al17 atom at the O end is -0.696 eV, indicating that the adsorption capacity of MgAl composite metal oxides near the Al17 atom at the N end is stronger when adsorbing NO2. When MgAl composite metal oxides adsorb N₂O, the adsorption energy near the Al₁₇ atom at the N-terminus is -0.479 eV, while that at the O-terminus is -0.897 eV. This indicates that the O-terminus exhibits stronger adsorption capacity for N₂O compared to the N-terminus. When adsorbing the three NOx compounds at the TOP sites of the Al₁₇ atoms in MgAl composite metal oxides, the adsorption capacity near the Al₁₇ atom at the N-terminus is the strongest for NO₂, representing the optimal adsorption configuration at the TOP sites of the Al₁₇ atoms.
[0029] Table 1
[0030]
[0031] Table 2
[0032]
[0033] Table 3
[0034]
[0035] Table 3 shows the stable structure energy and adsorption energy of the N-terminus / O-terminus of NO, NO2, and N2O molecules adsorbed by MgAl composite metal oxides at the Bridge site. Comparative analysis of the data in Table 3 shows that when MgAl composite metal oxides adsorb NO, the adsorption energy near the Al17 atom at the N-terminus is -0.658 eV, and the adsorption energy near the Al17 atom at the O-terminus is -0.334 eV. This indicates that the adsorption capacity of MgAl composite metal oxides near the N-terminus is stronger when adsorbing NO. When MgAl composite metal oxides adsorb NO2, the adsorption energy near the Al17 atom at the N-terminus is -1.062 eV, and the adsorption energy near the Al17 atom at the O-terminus is -1.518 eV. This indicates that the adsorption capacity of MgAl composite metal oxides near the O-terminus is stronger when adsorbing NO2. When MgAl composite metal oxides adsorb N₂O, the adsorption energy near the Al₁₇ atom at the N-terminus is -1.426 eV, while the adsorption energy near the Al₁₇ atom at the O-terminus is -0.394 eV. This indicates that the adsorption capacity of MgAl composite metal oxides for N₂O is stronger when the N-terminus is closer to the Al₁₇ atom. When adsorbing the three NOx molecules at the Bridge site of the Al₁₇ atom in MgAl composite metal oxides, the adsorption configuration with the O-terminus of the NO₂ molecule closer to the Al₁₇ atom exhibits the strongest adsorption capacity and is the optimal adsorption configuration at the Bridge site of the Al₁₇ atom.
[0036] Furthermore, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for adsorbing NOx from automobile exhaust using MgAl composite metal oxides, characterized in that, include: S1. Construct molecular unit cell models of MgAl composite metal oxide and NOx respectively; S2. Optimize the molecular unit cell models of MgAl composite metal oxide and NOx constructed in S1 to obtain the stable configuration and energy of MgAl composite metal oxide and NOx. S3. Based on the stable configuration and energy of the MgAl composite metal oxide and NOx obtained in S2, construct the adsorption configuration of NOx on the MgAl composite metal oxide and the adsorption configuration of the N / O end facing any metal atom on the MgAl composite metal oxide, respectively. S4. Calculate the adsorption energy of the NOx adsorption configuration on the MgAl composite metal oxide constructed in S3, and obtain the adsorption energy data of NOx on the MgAl composite metal oxide. S5. Based on the adsorption energy data of MgAl composite metal oxide for each NOx obtained in S4, analyze and evaluate the adsorption energy of MgAl composite metal oxide for each NOx.
2. The method for adsorbing NOx in automobile exhaust using MgAl composite metal oxides as described in claim 1, characterized in that, The MgAl composite metal oxide in S1 is obtained by calcining MgAl-LDH at about 800℃. During the heating process, the MgAl-LDH sequentially removes interlayer water, surface hydroxyl groups and interlayer anions. After the layered structure collapses, it forms MgAl composite metal oxide (MgAl-MMO), and its surface is used for adsorption calculation.
3. The method for adsorbing NOx in automobile exhaust using MgAl composite metal oxides as described in claim 2, characterized in that, The NOx in S1 includes nitric oxide (NO), nitrogen dioxide (NO2), and nitrous oxide (N2O).
4. The method for adsorbing NOx in automobile exhaust using MgAl composite metal oxides as described in claim 3, characterized in that, When optimizing the MgAl composite metal oxide and NOx molecular unit cell models constructed in S1 in S2, the following steps are included: optimizing the structure of the MgAl composite metal oxide unit cell and the molecular configurations of NO, NO2 and N2O to obtain stable MgAl composite metal oxide unit cell models and the energies of NO, NO2 and N2O models.
5. The method for adsorbing NOx in automobile exhaust using MgAl composite metal oxides as described in claim 4, characterized in that, In step S3, when constructing the adsorption configuration for NO adsorption by the MgAl composite metal oxide, the TOP sites of any metal atoms on the surface of the MgAl composite metal oxide catalyst are selected for adsorption, and adsorption configurations with the N-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst and the O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst are constructed respectively. When constructing the adsorption configuration for NO2 adsorption by the MgAl composite metal oxide, the TOP sites of any metal atoms on the surface of the MgAl composite metal oxide catalyst are selected for adsorption, and adsorption configurations with the N-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst and the O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst are constructed respectively. When constructing the adsorption configuration for N2O adsorption by the MgAl composite metal oxide, the TOP sites of any metal atoms on the surface of the MgAl composite metal oxide catalyst are selected for adsorption, and adsorption configurations with the N-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst and the O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst are constructed respectively.
6. The method for adsorbing NOx in automobile exhaust using MgAl composite metal oxides as described in claim 4, characterized in that, In step S3, when constructing the adsorption configuration for NO adsorption by the MgAl composite metal oxide, Bridge sites of any metal atom on the surface of the MgAl composite metal oxide catalyst are selected for adsorption, and adsorption configurations with the N-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst and the O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst are constructed respectively. When constructing the adsorption configuration for NO2 adsorption by the MgAl composite metal oxide, Bridge sites of any metal atom on the surface of the MgAl composite metal oxide catalyst are selected for adsorption, and adsorption configurations with the N-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst and the O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst are constructed respectively. When constructing the adsorption configuration for N2O adsorption by the MgAl composite metal oxide, Bridge sites of any metal atom on the surface of the MgAl composite metal oxide catalyst are selected for adsorption, and adsorption configurations with the N-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst and the O-terminus close to any metal atom on the surface of the MgAl composite metal oxide catalyst are constructed respectively.
7. The method for adsorbing NOx in automobile exhaust using MgAl composite metal oxides as described in claim 5 or 6, characterized in that, In step S4, when calculating the energy of the adsorption configuration of NO on the MgAl composite metal oxide, DFT structure optimization is performed on the two adsorption configurations of NO adsorbed on the MgAl composite metal oxide to obtain stable adsorption configurations and energy data, and the adsorption energies of the two adsorption configurations are calculated. When calculating the energy of the adsorption configuration of NO2 on the MgAl composite metal oxide, the two adsorption configurations of NO2 adsorbed on the MgAl composite metal oxide are imported into the VASP program package for DFT structure optimization to obtain stable adsorption configurations and energy data, and the adsorption energies of the two adsorption configurations are calculated. When calculating the energy of the adsorption configuration of N2O on the MgAl composite metal oxide, DFT structure optimization is performed on the two adsorption configurations of N2O adsorbed on the MgAl composite metal oxide to obtain stable adsorption configurations and energy data, and the adsorption energies of the two adsorption configurations are calculated.