Method for calculating adsorption energy of a zeolite h-cha adsorbing gas molecules
By constructing a high-precision optimized composite model of zeolite H-CHA and gas molecules, and using VASP software to calculate the adsorption energy of zeolite H-CHA, the complexity of studying the adsorption energy of zeolite H-CHA and gas molecules was solved, the calculation process was simplified and resource consumption was reduced, and a theoretical basis was provided.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI UNIV
- Filing Date
- 2023-05-26
- Publication Date
- 2026-07-31
AI Technical Summary
Existing technologies have limited and complex research on the adsorption energy of zeolite H-CHA with gas molecules, making it difficult to apply widely. In particular, the calculation of the adsorption energy of simple gas molecules is difficult, which hinders the development of this field.
A composite model combining a high-precision optimized zeolite H-CHA model and a gas molecule model was adopted. The adsorption energy of gas molecules adsorbed by zeolite H-CHA was calculated using VASP software. The formula Eads = Egas//H-CHA - Egas - EH-CHA was used to construct the model and perform low-precision optimization using VESTA software.
This method simplifies the calculation of the adsorption capacity of zeolite H-CHA with different gas molecules at the same level of precision, reduces computational resource consumption, is simple to operate and easy to implement, and has theoretical reference value.
Smart Images
Figure CN116631520B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of zeolite adsorption of gases, and in particular to a method for calculating the adsorption energy of gas molecules adsorbed by zeolite H-CHA. Background Technology
[0002] H-CHA zeolite is a highly selective and stable zeolite with a 12-ring structure and straight 10-ring channels, making it a promising candidate for applications as an adsorbent, catalyst, and separation material. However, many unresolved issues and challenges remain. While research on zeolites and various gases is extensive, particularly on their adsorption performance, studies on the adsorption energy of protonated zeolites, especially H-CHA, is scarce. This is due to a limited number of researchers and the complexity of calculating the adsorption energy, hindering its widespread application. Consequently, a breakthrough at the source is difficult to achieve. Therefore, resolving the adsorption energy problem of H-CHA for adsorbing simple gas molecules (i.e., those with no more than 6-8 atoms) is crucial for the development and in-depth research of this field. Summary of the Invention
[0003] The purpose of this invention is to overcome the shortcomings of the prior art by providing a method for calculating the adsorption energy of gas molecules adsorbed by zeolite H-CHA.
[0004] The objective of this invention can be achieved through the following technical solutions:
[0005] The technical solution of this invention is to provide a method for calculating the adsorption energy of gas molecules adsorbed by zeolite H-CHA, wherein the adsorption energy E of gas molecules adsorbed by zeolite H-CHA is... ads =E gas / / H-CHA -E gas -E H-CHA , of which E gas / / H-CHA E represents the energy value obtained after high-precision optimization of the composite model of the zeolite H-CHA model and the gas molecule model. gas E represents the energy value obtained after high-precision optimization of the gas molecule model. H-CHA The energy value is obtained after high-precision optimization of the zeolite H-CHA model.
[0006] Furthermore, the high-precision optimized energy convergence criterion is as follows:
[0007] Furthermore, the zeolite H-CHA model is constructed as follows: [The model is based on] a chemical composition of Si... n O (2n+x) After removing O atoms not bonded to Si atoms from the zeolite CHA model, the chemical composition was obtained as Si. n O2n The structure is obtained by replacing any Si atom with an Al atom and adding a H atom to any adjacent O atom. After low-precision optimization, the chemical composition is HAlSi. (n-1) O 2n The H-CHA zeolite structural model is given, where n is ≥36 and x is any positive integer.
[0008] Furthermore, the energy convergence criterion for low-precision optimization is...
[0009] Furthermore, the gas molecule model is constructed by optimizing the gas structure with low precision to obtain the gas molecule model.
[0010] Furthermore, the energy convergence criterion for low-precision optimization is...
[0011] Furthermore, the gas structure is a gas with no more than 6 to 8 atoms.
[0012] Furthermore, the composite model of the zeolite H-CHA model and the gas molecule model is constructed by adsorbing the zeolite H-CHA model and the gas molecule model onto each other and then optimizing them with low precision to obtain the composite model of the zeolite H-CHA model and the gas molecule model.
[0013] Furthermore, the energy convergence criterion for low-precision optimization is...
[0014] Furthermore, the mutual adsorption between the zeolite H-CHA model and the gas molecule model is that the gas molecule model enters the inner ring of the zeolite H-CHA model and adsorbs onto the acidic sites on the zeolite H-CHA model to form a stable configuration.
[0015] In some specific embodiments, the adsorption energy E of zeolite H-CHA adsorbs gas molecules ads =E gas / / H-CHA -E gas -E H-CHA , of which E gas / / H-CHA The energy value, E, is obtained by high-precision optimization calculation using VASP software for a composite model of the zeolite H-CHA model and the gas molecule model. gas E represents the energy value obtained from high-precision optimization calculations using the VASP software on a gas molecule model. H-CHA The energy value is obtained by high-precision optimization calculation using VASP software for the zeolite H-CHA model.
[0016] Furthermore, high-precision optimization calculations are performed by setting the energy convergence criterion using VASP software.
[0017] Furthermore, the zeolite H-CHA model is constructed as follows: [The model is based on] a chemical composition of Si... n O (2n+x) The zeolite CHA model was obtained by removing O atoms not bonded to Si atoms using VESTA software, resulting in a chemical composition of Si. n O 2n The structure is obtained by replacing any Si atom with an Al atom and adding a H atom to any adjacent O atom. After low-precision optimization, the chemical composition is HAlSi. (n-1) O 2n The H-CHA zeolite structural model is given, where n is ≥36 and x is any positive integer.
[0018] Furthermore, the low-precision optimization calculation is performed by setting the energy convergence criterion using VASP software.
[0019] Furthermore, the gas molecule model is constructed by performing low-precision optimization calculations on the gas structure using VASP software to obtain the gas molecule model.
[0020] Furthermore, the low-precision optimization calculation is performed by setting the energy convergence criterion using VASP software.
[0021] Furthermore, the gas structure is a gas with no more than 6 to 8 atoms, and it is modeled using VESTA software.
[0022] Furthermore, the composite model of the zeolite H-CHA model and the gas molecule model is constructed by adsorbing the zeolite H-CHA model and the gas molecule model onto each other, and then performing low-precision optimization calculations using VASP software to obtain the composite model of the zeolite H-CHA model and the gas molecule model.
[0023] Furthermore, the low-precision optimization calculation is performed by setting the energy convergence criterion using VASP software.
[0024] Furthermore, the mutual adsorption between the zeolite H-CHA model and the gas molecule model is that the gas molecule model enters the inner ring of the zeolite H-CHA model and adsorbs onto the acidic sites on the zeolite H-CHA model to form a stable configuration.
[0025] Compared with the prior art, the present invention has the following beneficial effects:
[0026] (1) The calculation method of the present invention can obtain the energy of zeolite H-CHA adsorbing different gas molecules under the same calculation accuracy. The adsorption capacity of zeolite H-CHA to react with different gas molecules can be easily determined by calculation.
[0027] (2) The calculation method of the present invention consumes less computing resources and is simple to operate and easy to implement, and has theoretical reference value for experiments. Attached Figure Description
[0028] Figure 1 Examples 1 include the zeolite H-CHA model (a), the ethylene gas molecule model (b), and the composite model of the ethylene gas model and the zeolite H-CHA model (c).
[0029] Figure 2 The sum of the energies of the zeolite H-CHA model and the ethylene gas molecule model in Example 1 is the difference between the energy of the composite model of the ethylene gas model and the zeolite H-CHA model. Detailed Implementation
[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0031] The VESTA and VASP software involved in this embodiment are both well-known to those skilled in the art. The related functions involved in the modeling, low-precision optimization calculation, and high-precision optimization calculation of the software are all built-in functions of the software itself and are also well-known to those skilled in the art.
[0032] Example 1:
[0033] A method for calculating the adsorption energy of ethylene gas molecules adsorbed by zeolite H-CHA includes the following steps:
[0034] (1) The zeolite CHA model was obtained from the International Zeolite Association (IZA) website (http: / / www.iza-structure.org / ). After converting the zeolite CHA model into a VASP file, its chemical composition is Si. 36 O 84 After removing O atoms not bonded to Si atoms using VESTA software, the resulting product has the chemical composition Si. 36 O 72 The structure was modified by replacing one Si atom with an Al atom and adding a H atom at the adjacent O(3) atom position (the O(3) position is located to the right of the Al atom), resulting in the chemical composition HAlSi. 35 O 72 The zeolite H-CHA model was then optimized using VASP software with low precision, and the energy convergence criterion was set to... A stable zeolite H-CHA model was obtained, such as Figure 1 As shown in (a);
[0035] (2) Ethylene gas molecules were modeled using VESTA software, and low-precision optimization was performed using VASP software. The energy convergence criterion was set to... A stable molecular model of ethylene gas was obtained, such as Figure 1 As shown in (b);
[0036] (3) Using VESTA software, the composite structure of ethylene gas molecules adsorbed on the zeolite H-CHA model and the ethylene gas molecule model was modeled. The ethylene gas molecule model interacted with the Al(1)O(3) acidic sites in the inner ring of the zeolite H-CHA model. Low-precision optimization was performed using VASP software, and the energy convergence criterion was set to A model was obtained showing the adsorption of stable ethylene gas molecules onto H-CHA, such as... Figure 1 As shown in (c);
[0037] (4) High-precision optimization calculations were performed on the zeolite H-CHA model, the ethylene gas molecule model, and the composite model of ethylene gas molecules adsorbed on the zeolite H-CHA model using VASP software, and the energy convergence criterion was raised to [value missing]. VASP software outputs the energy E of the zeolite H-CHA model. H-CHA The energy E of the ethylene gas molecule model is -860.88 eV. ethene The energy E is -31.98 eV, and the energy E of the recombination model of ethylene gas molecules adsorbed in the zeolite H-CHA model is also considered. ethene / / H-CHA It is -893.48 eV;
[0038] (5) The adsorption energy E of ethylene gas molecules by zeolite H-CHA ads Using formula E ads =E ethene / / H-CHA -E ethene -E H-CHA The energy of ethylene gas molecules adsorbed by zeolite H-CHA was found to be -0.615 eV, as shown in the figure. Figure 2 As shown.
[0039] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A method of calculating an adsorption energy of a zeolite H-CHA adsorbing a gas molecule, characterized by, The adsorption energy E of gas molecules adsorbed by zeolite H-CHA ads =E gas / / H-CHA -E gas -E H-CHA , of which E gas / / H-CHA E represents the energy value obtained after high-precision optimization of the composite model of the zeolite H-CHA model and the gas molecule model. gas E represents the energy value obtained after high-precision optimization of the gas molecule model. H-CHA The energy value is obtained after high-precision optimization of the zeolite H-CHA model. The zeolite H-CHA model is constructed as follows: [The model is based on] a chemical composition of Si... n O （2n+x） After removing O atoms not bonded to Si atoms from the zeolite CHA model, the chemical composition was obtained as Si. n O 2n The structure is obtained by replacing any Si atom with an Al atom and adding a H atom to any adjacent O atom. After low-precision optimization, the chemical composition is HAlSi. （n-1） O 2n The structural model of H-CHA zeolite, where n is ≥36 and x is any positive integer; The gas molecule model is constructed by optimizing the gas structure with low precision to obtain the gas molecule model. The composite model of the zeolite H-CHA model and the gas molecule model is constructed as follows: The zeolite H-CHA model and the gas molecule model are mutually adsorbed and then optimized with low precision to obtain a composite model of the zeolite H-CHA model and the gas molecule model. 2.The method of claim 1, wherein the method is characterized by, High precision optimized energy convergence criterion of 10 -7 eV / Å. 3.The method of claim 1, wherein the method is characterized by, In the construction of the zeolite H-CHA model, the energy convergence criterion for low-precision optimization was 10 -5 eV / Å. 4.The method of claim 1, wherein the method is characterized by, In the construction of the gas molecule model, the energy convergence criterion for low-precision optimization is 10. -5 eV / Å.
5. The method for calculating the adsorption energy of gas molecules adsorbed by zeolite H-CHA according to claim 1, characterized in that, In the construction of the gas molecule model, the gas structure is a gas with no more than 6 to 8 atoms.
6. The method for calculating the adsorption energy of gas molecules adsorbed by zeolite H-CHA according to claim 1, characterized in that, In the construction of the composite model of the zeolite H-CHA model and the gas molecule model, the energy convergence criterion for low-precision optimization is 10. -5 eV / Å.
7. The method for calculating the adsorption energy of gas molecules adsorbed by zeolite H-CHA according to claim 1, characterized in that, In the construction of the composite model of the zeolite H-CHA model and the gas molecule model, the mutual adsorption between the zeolite H-CHA model and the gas molecule model is that the gas molecule model enters the inner ring of the zeolite H-CHA model and adsorbs onto the acidic sites on the zeolite H-CHA model to form a stable configuration.