A method and model for calculating the kinetics of cyanamide production by a lime-nitrogen process, and applications thereof

Abstract

The application discloses a kind of dynamics calculation method, dynamics calculation model and application of lime nitrogen method process preparation cyanamide, the dynamics calculation method includes the following steps: step 1, construct reaction system molecular initial model;Step 2, structure optimization and vibration analysis are carried out to molecular initial model;Step 3, transition state search is carried out to reaction path;Step 4, the free energy of solute molecule in aqueous solution environment is calculated;Step 5, reaction kinetics and thermodynamic parameter calculation.The dynamics calculation model of lime nitrogen method process preparation cyanamide of the application reveals the microcosmic reaction mechanism of lime nitrogen method process, obtains Arrhenius kinetics equation, and reaction activation energy, pre-exponential factor and other key kinetic parameters, chemical reaction information such as intermediate, transition state that cyanamide generates experiences, forms theoretical support for the reaction process optimization improvement of lime nitrogen method, provides process parameter design basis for the optimization of equipment and plant scale system optimization.

Description

Technical Field

[0001] This invention relates to the field of process optimization technology for the preparation of cyanamide using the calcium cyanamide process, and in particular to a kinetic calculation method, kinetic calculation model, and application of the preparation of cyanamide using the calcium cyanamide process. Background Technology

[0002] Monocyanamide (H2N-C≡N) is the simplest cyanamide compound, used in chemical and pharmaceutical intermediates, agrochemicals, aerospace electronics, and other fields, and has wide application value in high-end fine chemicals and new chemical materials. Dicyandiamide [(NH2)2C=NC≡N], a dimerization product of monocyanamide, is also a high-value-added commercial chemical product, which can be directly prepared from monocyanamide through quantitative dimerization in alkaline aqueous solution. The preparation of cyanamide using calcium cyanamide as a raw material is currently the most important and mature process in China, adopted by most cyanamide companies. However, this process suffers from numerous byproducts, the discharge of large amounts of incompletely reacted cyanamide waste, and resource waste.

[0003] Existing cyanamide production processes, such as Figure 11 As shown, improving existing processes to prepare high-concentration cyanamide solutions and high-purity crystals is the focus of current research and development. However, traditional techniques for studying the calcium cyanamide process through experiments are limited by instrument levels and experimental conditions, and have significant limitations in deeply exploring the reaction mechanisms and kinetics at the microscopic level. Most of these techniques rely on the research experience of technical personnel, resulting in long experimental cycles and high consumption of human and material resources. Summary of the Invention

[0004] The purpose of this invention is to provide a kinetic calculation method for the preparation of cyanamide using the calcium cyanamide process, addressing the issue that existing cyanamide production technology improvements rely on the research experience of technical personnel, have long experimental cycles, and consume a large amount of human and material resources.

[0005] Another objective of this invention is to provide a dynamic calculation model based on the aforementioned dynamic calculation method.

[0006] Another object of the present invention is to provide an application of the aforementioned dynamic calculation model.

[0007] The technical solution adopted to achieve the purpose of this invention is:

[0008] A method for constructing a kinetic calculation model for the preparation of cyanamide using the calcium cyanamide process includes the following steps:

[0009] Step 1: Construct an initial molecular model of the reaction system. Use the GaussView visualization program, which is compatible with Gaussian software, to construct an initial molecular model of the reactants in the calcium cyanamide reaction system, and obtain the original .gjf input file of Gaussian software.

[0010] Step 2: Perform structural optimization and vibrational analysis on the initial molecular model. Use Gaussian software to optimize the structure and find the potential energy surface minimum structure. The vibrational frequency is calculated by calculating the Hessian matrix of the molecule. The calculated molecular configuration has no imaginary frequency and the structure's force and displacement converge normally to obtain a reasonable configuration.

[0011] Step 3: Perform a transition state search on the reaction path. Use the opt=TS method in Gaussian software to search for the reaction transition state. Based on a reasonable initial guess of the transition state configuration, optimize the first-order saddle point of the potential energy surface. The optimized transition state configuration is determined by vibrational analysis to have only one imaginary frequency, and the direction of the imaginary frequency vibration corresponds to the direction of the reaction coordinates. On this basis, verify whether the transition state correctly connects the reactants and products in the intrinsic reaction coordinate theory to ensure the rationality of the obtained transition state.

[0012] Step 4: Calculate the solute molecule's free energy in aqueous solution. The free energy in aqueous solution is the sum of the free energy in the gas phase, the dissolution free energy, and the difference in free energy between the standard states. Using the obtained free energy values ​​in aqueous solution, plot the reaction coordinates on the x-axis and the free energy in aqueous solution (relative free energy values) on the y-axis to obtain the reaction potential energy barrier diagram. The reaction rate control steps are derived from the reaction potential energy surface of the lime cyanide process.

[0013] Step 5: Calculation of reaction kinetics and thermodynamic parameters. Based on the free energy barrier difference of the rate-controlling step in the reaction potential energy surface barrier diagram, the reaction rate constant within the operating temperature range of the lime cyanide process is obtained by calculating the mean potential (PMF) or transition state theory (TST) combined with tunneling correction. The Arrhenius kinetic equation, reaction activation energy, and pre-exponential factor are obtained by fitting the equation, and the thermodynamic equilibrium constant of the reaction is obtained by using Gaussian software.

[0014] In the above technical solution, the aqueous solution environment of the calcium cyanamide process in the kinetic calculation model adopts an implicit solvent model.

[0015] In the above technical solution, when calculating the free energy in the gas phase in step 4, the Shermo program is used, the ZPE correction factor at the geometric optimization level is adopted, and the Grimme quasi-RRHO model is used.

[0016] In the above technical solution, the dissolution free energy in step 4 is calculated by the following method: using a specialized solvent model parameterized calculation level M05-2X / 6-31G* to calculate under the SMD implicit solvent model, the dissolution free energy is the single-point energy calculated under the SMD model (M05-2X / 6-31G* / / SMD), minus the single-point energy calculated under the gas phase (M05-2X / 6-31G*).

[0017] In the above technical solution, when the free energy barrier difference in the reaction rate control step in step 5 is negative, the calculation steps for the average force potential are as follows: the location where the reaction intermediate breaks bonds is flexibly scanned using Gaussian software, and then vibration analysis is performed on each frame configuration of the flexible scan. After calculating the free energy of each frame configuration, the free energy value is fitted to the scanned bond length, and the free energy of the maximum point of the curve is taken as the average force potential to calculate the reaction rate constant.

[0018] In the above technical solution, when the free energy barrier difference in the reaction rate control step in step 5 is positive, the tunneling correction calculation adopts the Wigner correction method, which requires the imaginary frequency value of the transition state and the reaction temperature. The original reaction rate constant obtained by the transition state theory is corrected by the obtained tunneling coefficient.

[0019] In the above technical solution, the temperature range for the monocyanate reaction in the calcium cyanamide process is 10-50℃, and the temperature range for the dicyandiamide reaction is 50-90℃.

[0020] In the above technical solution, the dynamic calculation model uses DFT-D3 dispersion correction to improve the quality of the calculation functional's description of dispersive interactions.

[0021] In another aspect, the present invention provides a kinetic calculation model for the preparation of cyanamide by the calcium cyanamide process, which is obtained by the aforementioned construction method.

[0022] In another aspect, the present invention provides an application of the kinetic calculation model for the preparation of cyanamide by the calcium cyanamide process described above in the design, optimization and process intensification of reactor equipment.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. The kinetic calculation model for cyanamide preparation by the calcium cyanamide process of this invention is based on the microscopic reaction mechanism of the calcium cyanamide process. It obtains the rate-controlling steps of each reaction, the Arrhenius kinetic equation, and key kinetic parameters such as reaction activation energy and pre-exponential factor. In turn, it obtains the reaction network of the cyanamide formation process, and obtains the microscopic reaction process that cannot be obtained by experimental means, as well as the chemical reaction information such as intermediates and transition states involved in cyanamide formation. This provides theoretical support for the optimization and improvement of the calcium cyanamide reaction process and provides a basis for process parameter design for equipment selection and plant-scale system optimization.

[0025] 2. The kinetic calculation model for the preparation of cyanamide using the calcium cyanamide process of the present invention can obtain the intrinsic kinetic information of cyanamide formation, which makes up for the shortcomings of experimental methods in obtaining apparent kinetic parameters at the kinetic level.

[0026] 3. The dynamic calculation model based on density functional theory provided by this invention can be completed on a properly configured server, avoiding the safety risks of contact with chemicals in experimental research, reducing the cost of purchasing a large number of experimental equipment and consumables, and has the advantages of high safety, small space occupation, and good reliability.

[0027] 4. The kinetic calculation model of this invention can provide theoretical guidance for the improvement and optimization of the calcium cyanamide process, and provide data reference for the design, optimization and process intensification of reactor equipment. Attached Figure Description

[0028] Figure 1 The main chemical molecular structures involved in the preparation of cyanamide by the calcium cyanamide method.

[0029] Figure 2 To optimize the geometric parameters (bond length in angstroms, bond angle in degrees) of the reactants, reaction complex (RC), transition state (TS), product complex (PC), and product in the obtained cyanamide reaction system.

[0030] Figure 3 denoted as , where is the relative energy (kJ / mol) at each stationary point in the cyanamide reaction system.

[0031] Figure 4 To optimize the geometric parameters (bond length in angstroms, bond angle in degrees) of the reactants, reaction complex (RC), transition state (TS), intermediate (IM), product complex (PC), and product in the dicyandiamide reaction system.

[0032] Figure 5 ν represents the relative energy (kJ / mol) at each station point in the dicyandiamide reaction.

[0033] Figure 6 A flowchart illustrating the reaction kinetics calculations for the preparation of cyanamide via the calcium cyanamide method.

[0034] Figure 7 The flexible scan curve (bond length unit: Å) of the reaction complex R1 RC in the H2-N4 direction is shown for the R1 reaction.

[0035] Figure 8 The curves showing the fitting of the free energy and H2-N4 bond length for the flexible scanning configuration are shown.

[0036] Figure 9 The Arrhenius kinetic equation for the monocyanamide reaction is fitted.

[0037] Figure 10 The Arrhenius kinetic equation for the dicyandiamide reaction is fitted.

[0038] Figure 11 A flowchart of the existing process for cyanamide production. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0040] The reaction equation for cyanamide in this invention is as follows:

[0041] CN2 2- +H2O→HCN2 - +OH- R1

[0042] HCN2 - +H₂O→H₂CN₂+OH⁻ R₂

[0043] The reaction equation for dicyandiamide is as follows:

[0044] H₂CN₂ + OH⁻ → HCN₂ - +H2O R3

[0045] HCN2 - +H2CN2→H3C2N4 - R4

[0046] H3C2N4 - +H2CN2→HCN2 - +(H2CN2)2 R5

[0047] The main chemical molecular structures involved in this invention are as follows: Figure 1 As shown.

[0048] Example 1

[0049] This embodiment uses the cyanamide reaction system as the research object, with the reaction equation as R1-R2. The kinetic calculation model is constructed through the following steps:

[0050] Step 1: Based on theoretical literature on cyanamide, the most stable conformation of the cyanamide molecule (cyanamide form, H2NCN) is used as the model molecule of cyanamide, and the conformations of other molecules are established in GaussView.

[0051] Step 2: Structural optimization and vibration analysis were performed using Gaussian software. The convergence criterion was set to the software's default settings, and the calculation level was B2PLYP-D3 / def2-TZVP. Frequency calculations were used to confirm the presence of imaginary frequencies. Based on the optimized configuration, high-precision electron energy calculations were performed at the B2PLYP-D3 / ma-QZVPP level.

[0052] Step 3: Based on the optimized complex configuration, a transition state search is performed using Gaussian software with opt=TS, and frequency calculations are performed to ensure that the transition state has exactly one imaginary frequency and a reasonable vibrational direction. Subsequently, an IRC task is performed to verify whether the transition state correctly connects the reactants and products. Figure 2 To optimize the obtained molecular configuration and its geometric parameters;

[0053] Step 4: Calculation of the free energy of solute molecules in aqueous solution: The free energy in the gas phase is calculated using the Shermo program. The high-precision electron energy values ​​obtained from Gaussian software are written into the Shermo input file settings.ini. In settings.ini, ilowfreq is set to 2, and the Grimme quasi-RRHO model is selected. The ZPE correction factor (0.98168) at the B2PLYP-D3 / def2-TZVP level is written into the sclZPE field in settings.ini to obtain the free energy in the gas phase. The dissolution free energy is the difference between the single-point energy under the SMD model and the single-point energy in the gas phase [E(M05-2X / 6-31G* / / SMD)-E(M05-2X / 6-31G*)], and the calculation level is M05-2X / 6-31G*, which performs excellently in calculating dissolution free energy. The standard state transition free energy difference is 1.89 kcal / mol, corresponding to the free energy change at 298.15 K from 1 atm to 1 mol / L concentration. The free energy in the aqueous solution environment is the sum of the free energy in the gas phase, the dissolution free energy, and the standard state transition free energy difference (1.89 kcal / mol). Based on the calculated free energy values ​​in the aqueous solution, an energy barrier diagram for the cyanamide reaction is obtained with the reaction coordinates as the x-axis and the relative free energy values ​​as the y-axis (e.g., ...). Figure 3As shown in the figure, the rate-determining step of the monocyanamide series reaction is the formation of the reaction complex R1 RC, with a free energy barrier of 13.86 kJ / mol. The negative barrier indicates that the formation of monocyanamide is a barrier-free process, which can be completed rapidly in a short time.

[0054] Step 5, calculate based on the reaction kinetics flowchart ( Figure 6 The reaction rate constant is calculated using the method corresponding to reactions with negative potential barriers. The reverse reaction of R1, where the rate-determining step of the cyanamide reaction occurs, is treated as a barrier-free reaction, and a flexible scan is performed on the bond-breaking process of the transition state of R1 (e.g., ...). Figure 7 As shown), each frame configuration is extracted for vibration analysis. The configuration with only one imaginary frequency, and whose imaginary frequency is strictly aligned with the scanning bond length direction, is used to calculate the free energy in an aquatic environment. The obtained free energy values ​​are then fitted to the bond lengths to form curves (e.g., ...). Figure 8 As shown in the figure, the free energy corresponding to the maximum point of the curve can be used to calculate the reverse reaction rate constant of the cyanamide system using transition state theory, and the forward reaction rate constant can be derived by using the fine equilibrium principle. The calculated reaction rate constants and equilibrium constants are summarized in Table 1.

[0055] Table 1. Forward reaction of cyanamide at different temperatures (k + ) and reverse (k - Reverse reaction rate constant and equilibrium constant (K)

[0056] T / ℃ <![CDATA[k + / (cm 3 ·mol -1 ·s -1 )]]> <![CDATA[k - / (cm 3 ·mol -1 ·s -1 )]]> K 10 <![CDATA[7.81×10 22 ]]> <![CDATA[3.81×10 14 ]]> <![CDATA[2.05×10 8 ]]> 20 <![CDATA[3.06×10 22 ]]> <![CDATA[2.76×10 14 ]]> <![CDATA[1.11×10 8 ]]> 30 <![CDATA[1.28×10 22 ]]> <![CDATA[2.04×10 14 ]]> <![CDATA[6.26×10 7 ]]> 40 <![CDATA[5.64×10 21 ]]> <![CDATA[1.54×10 14 ]]> <![CDATA[3.67×10 7 ]]> 50 <![CDATA[2.62×10 21 ]]> <![CDATA[1.18×10 14 ]]> <![CDATA[2.22×10 7 ]]>

[0057] The forward reaction rate constant at 10-50℃ was fitted with temperature, with 1000 / T as the abscissa and lnk... + Using the ordinate as the vertical axis, the Arrhenius equation is obtained by fitting (e.g.) Figure 9 As shown), the Arrhenius equation is expressed as k + = (9.760 × 10 7 )exp(7.760 / T), the pre-exponential factor value is 9.760×10 7 The activation energy is -64.521 kJ / mol. The negative activation energy value is consistent with the negative potential barrier characteristic, and it can be regarded as a barrier-free reaction process.

[0058] Example 2

[0059] This embodiment uses the dicyandiamide reaction system as the research object. The reaction equations are shown in R3-R5. The kinetic calculation model is constructed through the following steps:

[0060] Step 1: Based on theoretical literature on dicyandiamide, the most stable conformation of the dicyandiamide molecule [cyanoimine form, (NH2)2C=NC≡N] is used as the model molecule of dicyandiamide, and the conformations of other molecules are established in GaussView;

[0061] Step 2: Structural optimization and vibration analysis were performed using Gaussian software. The convergence criterion was set to the software's default settings, and the calculation level was B2PLYP-D3 / def2-TZVP. Frequency calculations were used to confirm the presence of imaginary frequencies. Based on the optimized configuration, high-precision electron energy calculations were performed at the B2PLYP-D3 / ma-QZVPP level.

[0062] Step 3: Based on the optimized complex configuration, a transition state search is performed using Gaussian software with opt=TS, and frequency calculations are performed to ensure that the transition state has exactly one imaginary frequency and a reasonable vibrational direction. Subsequently, an IRC task is performed to verify whether the transition state correctly connects the reactants and products. Figure 4 To optimize the obtained molecular configuration and its geometric parameters;

[0063] Step 4: Calculation of the free energy of solute molecules in aqueous solution: The free energy in the gas phase is calculated using the Shermo program. The high-precision electron energy values ​​obtained from Gaussian software are written into the Shermo input file settings.ini. In settings.ini, ilowfreq is set to 2, and the Grimme quasi-RRHO model is selected. The ZPE correction factor (0.98168) at the B2PLYP-D3 / def2-TZVP level is written into the sclZPE field in settings.ini to obtain the free energy in the gas phase. The dissolution free energy is the difference between the single-point energy under the SMD model and the single-point energy in the gas phase [E(M05-2X / 6-31G* / / SMD)-E(M05-2X / 6-31G*)], and the calculation level is M05-2X / 6-31G*, which performs excellently in calculating dissolution free energy. The standard state transition free energy difference is 1.89 kcal / mol, corresponding to the free energy change at 298.15 K from 1 atm to 1 mol / L concentration. The free energy in aqueous solution is the sum of the free energy in the gas phase, the dissolution free energy, and the standard state transition free energy difference (1.89 kcal / mol). Based on the calculated free energy values ​​in aqueous solution, an energy barrier diagram for the dicyandiamide reaction is obtained with the reaction coordinates as the x-axis and the relative free energy values ​​as the y-axis (e.g., ...). Figure 5 As shown, the rate-determining step of the dicyandiamide chain reaction is the bonding process between the carbon atom of cyanamide and the nitrogen atom of the cyanamide anion.

[0064] Step 5: Calculate the reaction rate constant using the free energy difference of the rate-determining step in the dicyandiamide series reaction. The reaction barrier is positive. This is based on the reaction kinetics calculation flowchart (…). Figure 6 The reaction rate constant is calculated using the method corresponding to reactions with positive potential barriers. The formula for calculating the reaction rate constant based on thermodynamic quantities is:

[0065]

[0066] Where σ is the reaction path degeneracy, κ is the tunneling coefficient, and k B Where is the Boltzmann constant, h is the Planck constant, and ΔG 0,≠ Let R be the free energy barrier of the rate-controlling step, and R be the ideal gas constant.

[0067] The formula for calculating the tunneling coefficient using the Wigner correction method is:

[0068]

[0069] In the formula, υ m Let be the imaginary frequency of the transition state of the potential energy surface.

[0070] The calculation results of the reaction rate constant, equilibrium constant and tunneling effect of dicyandiamide reaction at different temperatures, based on the operating temperature of the dicyandiamide reaction, are summarized in Table 2.

[0071] Table 2. Forward reaction of dicyandiamide at different temperatures (k + ), reverse (k) - Calculation results of reaction rate constant, equilibrium constant (K) and tunneling coefficient (κ)

[0072]

[0073]

[0074] The forward reaction rate constant at 50-90℃ was fitted with temperature, with 1000 / T as the abscissa and lnk... + Using the ordinate as the vertical axis, the Arrhenius equation is obtained by fitting (e.g.) Figure 10 As shown), the Arrhenius equation is expressed as k + = (1.570 × 10 4 )exp(-15.515 / T), the pre-exponential factor is 1.570×10 4 The activation energy is 129.001 kJ / mol.

[0075] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A kinetic calculation method for the preparation of cyanamide using the calcium cyanamide process, characterized in that, Includes the following steps: Step 1: Construct an initial molecular model of the reaction system. Use the GaussView visualization program, which is compatible with Gaussian software, to construct an initial molecular model of the reactants in the calcium cyanamide reaction system and obtain the original input file for Gaussian software. Step 2: Perform structural optimization and vibrational analysis on the initial molecular model. Use Gaussian software to optimize the structure and find the potential energy surface minimum structure. The vibrational frequency is calculated by calculating the Hessian matrix of the molecule. The calculated molecular configuration has no imaginary frequency and the structure's force and displacement converge normally to obtain a reasonable configuration. Step 3: Perform a transition state search on the reaction path. Use the opt=TS method in Gaussian software to search for the reaction transition state. Based on a reasonable initial guess of the transition state configuration, optimize the first-order saddle point of the potential energy surface. The optimized transition state configuration is determined by vibrational analysis to have only one imaginary frequency, and the direction of the imaginary frequency vibration corresponds to the direction of the reaction coordinates. On this basis, verify whether the transition state correctly connects the reactants and products in the intrinsic reaction coordinate theory to ensure the rationality of the obtained transition state. Step 4: Calculate the free energy of solute molecules in aqueous solution. The free energy in aqueous solution is the sum of the free energy in the gas phase, the dissolution free energy, and the difference in free energy between the standard states. Using the obtained free energy values ​​in aqueous solution, a reaction potential energy barrier diagram is obtained with the reaction coordinates as the x-axis and the free energy in aqueous solution as the y-axis. The reaction rate control steps are derived from the reaction potential energy surface of the lime cyanide process. Step 5: Calculation of reaction kinetics and thermodynamic parameters. Based on the free energy barrier difference of the rate-controlling step in the reaction potential energy surface barrier diagram, the average force potential or transition state theory combined with tunneling correction method is used to obtain the reaction rate constant within the operating temperature range of the lime cyanide process. The Arrhenius kinetic equation, reaction activation energy, and pre-exponential factor are fitted, and the thermodynamic equilibrium constant of the reaction is obtained through Gaussian software.

2. The kinetic calculation method for preparing cyanamide using the calcium cyanamide process as described in claim 1, characterized in that, In the aforementioned kinetic calculation method, the aqueous solution environment of the calcium cyanamide process is modeled using an implicit solvent model.

3. The kinetic calculation method for preparing cyanamide using the calcium cyanamide process as described in claim 1, characterized in that, In step 4, when calculating the free energy in the gas phase, the Shermo program is used, with the ZPE correction factor at the geometric optimization level, and the Grimme quasi-RRHO model is used.

4. The kinetic calculation method for preparing cyanamide using the calcium cyanamide process as described in claim 1, characterized in that, The dissolution free energy in step 4 is calculated as follows: the solvent model parameterization calculation level M05-2X / 6-31G* is used to calculate the dissolution free energy under the SMD implicit solvent model. The dissolution free energy is the single-point energy calculated under the SMD model, minus the single-point energy calculated under the gas phase.

5. The kinetic calculation method for preparing cyanamide using the calcium cyanamide process as described in claim 1, characterized in that, When the free energy barrier difference in the reaction rate control step in step 5 is negative, the calculation steps for the average potential are as follows: the location where the reaction intermediate breaks bonds is flexibly scanned using Gaussian software, and then vibration analysis is performed on each frame configuration of the flexibly scanned configuration. After calculating the free energy of each frame configuration, the free energy value is fitted to the scanned bond length, and the free energy of the maximum point of the curve is taken as the average potential to calculate the reaction rate constant.

6. The kinetic calculation method for preparing cyanamide using the calcium cyanamide process as described in claim 1, characterized in that, When the free energy barrier difference in the reaction rate control step in step 5 is positive, the tunneling correction calculation adopts the Wigner correction method, and the original reaction rate constant obtained by the transition state theory is corrected by the obtained tunneling coefficient.

7. The kinetic calculation method for preparing cyanamide using the calcium cyanamide process as described in claim 1, characterized in that, In the calcium cyanide process, the temperature range for the monocyanate reaction is 10-50℃, and the temperature range for the dicyandiamide reaction is 50-90℃.

8. The kinetic calculation method for preparing cyanamide using the calcium cyanamide process as described in claim 1, characterized in that, The dynamic calculation method employs DFT-D3 dispersion correction to improve the quality of the calculated functional's description of dispersive interactions.

9. A kinetic calculation model for the preparation of cyanamide by the calcium cyanamide process based on the kinetic calculation method described in any one of claims 1-8.

10. The application of a kinetic calculation model for the preparation of cyanamide by the calcium cyanamide process as described in claim 9 in the design, optimization and process intensification of reactor equipment.

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