Method for predicting adsorption capacity of volatile organic compounds across adsorption temperature

Abstract

The application provides a volatile organic compound adsorption capacity prediction method across adsorption temperature, and belongs to the technical field of waste gas treatment. The method selects two or more than two porous materials with concentrated pore diameter as model adsorption materials, tests the pore structure and the adsorption isotherm of VOCs, and obtains a ternary matching relationship equation among the critical pore diameter of the packed adsorption, the relative pressure and the adsorption temperature on the basis of normalizing the pressure of the adsorption isotherm relative to the saturated vapor pressure under the corresponding adsorption temperature. The application respectively contributes to the contribution of the packed adsorption and the contribution of the covered adsorption to the adsorption capacity, introduces the coefficients of the packed adsorption and the covered adsorption as variables, combines the test data of the model adsorption materials to solve the equation coefficients, and constructs a VOCs adsorption capacity prediction equation across adsorption temperature. The equation can be used for the adsorbents with similar surface properties to predict the VOCs adsorption capacity and the isotherm under different adsorption temperatures.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste gas treatment, and particularly relates to a volatile organic compound adsorption capacity prediction method across adsorption temperature. BACKGROUND

[0002] Volatile organic compounds, in English, are referred to as VOCs, which are a general term for a class of volatile organic compounds. VOCs are widely used in various industrial processes, but their emissions can cause serious harm to the ecological environment and human health. Among various VOCs pollution control technologies, adsorption method has become one of the most widely used methods due to its flexible operation, high purification efficiency, wide application range, promotion of recycling, reduction of carbon emissions and other advantages. At present, the fine, scientific and efficient recovery of VOCs control is the key point of the research. The fine control of VOCs, the improvement of adsorption capacity, and the optimization of adsorption material and process all need to be based on the structure-activity relationship between the physical properties of adsorbate and the structural properties of adsorbent. The development of adsorption material and technology depends largely on the guidance of adsorption mechanism.

[0003] Adsorption capacity prediction is based on the accurate matching relationship between material pore structure parameters and VOCs adsorption capacity and the realization of equation, which has important reference significance for the optimization of adsorption material and technology. For example, in industrial waste gas treatment, accurate prediction of adsorption capacity can help to reasonably select adsorption material, reduce treatment cost and improve purification efficiency. In terms of adsorption theoretical model and equation, Langmuir, Dubinin-Radushkevich, Dubinin-Astakhov and other equations and models can be used to fit and explain the obtained adsorption isotherms. However, since these methods do not take the pore structure parameters of adsorbent as variables, they cannot predict the VOCs adsorption capacity of unknown adsorbent. Although the neural network method introduces pore structure parameters as variables, it is a statistical result, and its accuracy is greatly affected by data quality, and often lacks regularity of theoretical explanation. Therefore, it is urgent to accurately quantify the matching relationship between the structural properties of adsorbent and the VOCs adsorption capacity from a new angle.

[0004] Filling adsorption is a common phenomenon in the adsorption of gases by porous solids. According to the Kelvin equation, the equilibrium vapor pressure on the concave liquid surface is less than that on the flat liquid surface due to the restriction of the pore wall in the confined space. Therefore, the condensed liquid tends to form in the nanopores at a pressure much lower than the saturated vapor pressure. Under certain conditions, filling adsorption can occur in pores below a certain pore size, where the density of the adsorbate approaches that of the liquid. Therefore, there is a critical pore size, which is the dividing size between filling and covering adsorption. The study of this critical pore size provides a starting point for quantitatively analyzing the contribution of pores of different pore sizes to the adsorption capacity of VOCs.

[0005] At present, the patent with publication number CN116593376A provides a prediction method for the adsorption capacity of volatile organic compounds based on filling adsorption. The adsorption capacity prediction equation is obtained according to the contribution of filling adsorption and covering adsorption to the adsorption capacity of VOCs, which can realize the prediction of VOCs adsorption capacity / isotherm at a specific adsorption temperature. However, since the adsorption temperature is not introduced as a variable into the prediction equation, the adsorption capacity prediction equation obtained at a specific temperature can only be used to predict the adsorption capacity at that target temperature. If the adsorption capacity / isotherm at other temperatures is to be predicted, the adsorption capacity prediction equation at the corresponding temperature needs to be re-derived, which increases the workload and to some extent limits the convenience and generalizability of the adsorption capacity / isotherm prediction method.

[0006] If there is a prediction method for the adsorption capacity of volatile organic compounds across adsorption temperatures, i.e., the same adsorption capacity prediction equation can be used to predict the adsorption capacity / isotherm at different adsorption temperatures, it will significantly improve the convenience and generalizability of the VOCs adsorption capacity prediction equation. Adsorption capacity prediction is based on the accurate matching relationship between material pore structure parameters and VOCs adsorption capacity and the realization of equation, which can provide important reference for the development and optimization of adsorption materials and technology. At present, there is still a lack of a prediction method for the adsorption capacity of volatile organic compounds across adsorption temperatures with a solid theoretical basis. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a prediction method for the adsorption capacity of volatile organic compounds across adsorption temperatures. The prediction method provided by the present application can realize the prediction of the adsorption capacity and adsorption isotherm of VOCs at different adsorption temperatures according to the pore structure parameters of the adsorption material through the same equation, i.e., prediction across adsorption temperatures.

[0008] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0009] The present application provides a prediction method for the adsorption capacity of volatile organic compounds across adsorption temperatures, comprising the following steps:

[0010] (1) Provide two or more porous materials with concentrated pore size distribution as model adsorption materials, and test the pore structure parameters of the model adsorption materials. The pore structure parameters include pore size distribution, cumulative pore volume variation with pore size distribution, total pore volume V, cumulative specific surface area variation with pore size distribution, and total specific surface area S.

[0011] (2) Test the adsorption isotherms of a model adsorbent material for a specific VOCs at multiple adsorption temperatures. By dividing each pressure point on the static adsorption isotherm by the saturated vapor pressure P0 at the corresponding temperature, the static adsorption isotherm after partial pressure normalization is obtained.

[0012] Based on the static adsorption isotherm after partial pressure normalization, the relative pressure range corresponding to the filling adsorption of the model adsorbent material is obtained, and the median value of the relative pressure range is taken as the critical relative pressure P. C / P0; the critical relative pressure P C / P0 corresponds to the median value of the pore size distribution of the adsorbent material in this model, and this median value of the pore size distribution is taken as the critical relative pressure P. C The critical pore size D at / P0 that allows for packed adsorption is D C ;

[0013] The critical relative pressure P of the adsorbent material in this model C Linear fitting of / P0 with adsorption temperature T yields the critical relative pressure P at a specific pore size. C The linear relationship between P0 and adsorption temperature is expressed as follows:

[0014] P C / P0=k P ×T+d P Equation 1;

[0015] Among them, P C / P0 is the critical pressure P C The critical relative pressure relative to the saturated vapor pressure P0 at the corresponding adsorption temperature;

[0016] T is the adsorption temperature, in °C;

[0017] k P The slope of the linear relationship between relative pressure and adsorption temperature;

[0018] d P In a linear relationship, P approaches 0. C The value of / P0;

[0019] Based on the different adsorption temperatures T corresponding to different P values ​​of the adsorbent material in this model C The P0 value is used to solve for the coefficient k in Equation 1 corresponding to the adsorbent material in this model.P and d P ;

[0020] (3) Refer to the method of step (2), obtain the coefficients k P and d P ;

[0021] (4) Linearly fit the k C and d C of the linear relationship equation between the critical relative pressure P P / P0 and the adsorption temperature T under the condition of multiple critical pore diameters D P , respectively, and make linear fitting with respect to the respective critical pore diameters D C , to obtain the linear relationship equations of the coefficients k P and d P with the critical pore diameters D C , respectively, k P =k P1 ×D C +k P0 and d P =d P1 ×D C +d P0 , so as to obtain the linear relationship equation of the filled adsorption critical relative pressure P C / P0 with the adsorption temperature T and the pore size D C :

[0022] P C / P0=(k P1 ×D C +k P0 )×T+(d P1 ×D C +d P0 ), equation 2;

[0023] wherein P C / P0 is the critical relative pressure of the critical pressure P C relative to the saturated vapor pressure P0 at the corresponding adsorption temperature;

[0024] T is the adsorption temperature, ℃;

[0025] D C is the critical pore size, nm, at which the filled adsorption can occur when the relative pressure is P C / P0;

[0026] k P1 and k P0 are the slope and the intercept of the linear relationship equation of k P with the critical pore diameter D C , respectively;

[0027] d P1 and d P0 respectively are d P The slope and intercept of the linear relationship equation change with the critical pore size D C ;

[0028] The critical pore size D C at which the filling-type adsorption can occur at different relative pressure P C / P0 and adsorption temperature T can be obtained by using equation 2:

[0029] D C =(P C / P0-k P0 ×T-d P0 ) / (k P1 ×T+d P1 ), equation 3;

[0030] wherein D C , P C / P0, T, k P1 , k P0 , d P1 and d P0 have the same meaning as in equation 2;

[0031] (5) Taking the critical pore size D C as the demarcation point, the variation of the cumulative pore volume with pore size distribution and the variation of the cumulative specific surface area with pore size distribution tested according to the pore structure parameters are obtained, respectively, to obtain the pore volume V C of the pores below the critical pore size D C and the specific surface area S C of the pores above the critical pore size D C ;

[0032] (6) Based on the contribution of the pore volume V C of the pores in which the filling-type adsorption occurs and the specific surface area S C of the pores in which the covering-type adsorption occurs to the VOCs adsorption amount, the pore size, the relative pressure and the adsorption temperature of different model adsorbents are introduced into the adsorption amount prediction equation as parameters to obtain the VOCs adsorption amount prediction equation that can be extended to the prediction of the adsorption isotherm at different adsorption temperatures T:

[0033] Q=a×V C +b×S C =f(D AV ,P / P0,T)×V C +g(D AS ,P / P0,T)×S C , equation 4;

[0034] wherein Q is the adsorption amount of VOCs per unit mass of adsorbent, g / g;

[0035] V C is the pore volume of pores below the critical pore size, i.e. the critical pore volume, cm 3 / g;

[0036] S C is the specific surface area of pores above the critical pore size, i.e. the critical specific surface area, m 2 / g;

[0037] D AV is the average pore diameter of pores where filling adsorption occurs, nm; wherein D AV = 4V C / (S-S C ), S is the total specific surface area, m 2 / g;

[0038] D AS is the average pore diameter of pores where covering adsorption occurs, nm; wherein D AS = 4(V-V C ) / S C , V is the total pore volume, cm 3 / g;

[0039] T is the adsorption temperature, °C;

[0040] P / P0 is any relative pressure point on the adsorption isotherm normalized with respect to the saturated vapor pressure at the corresponding temperature; P0 is the saturated vapor pressure of VOCs at the corresponding adsorption temperature T, mbar;

[0041] a is the coefficient of filling adsorption, i.e. the adsorption amount of VOCs per unit pore volume, g / cm 3 , wherein a = f(D AV , P / P0, T) indicates that the coefficient a is a function of the pore diameter D AV , the relative pressure P / P0 and the adsorption temperature T;

[0042] b is the coefficient of covering adsorption, i.e. the adsorption amount of VOCs per unit specific surface area, g / m 2 , wherein b = g(D AS , P / P0, T) indicates that the coefficient b is a function of the pore diameter D AS , the relative pressure P / P0 and the adsorption temperature T;

[0043] (7) by testing the pore structure of a plurality of model adsorbents and the adsorption isotherms under different adsorption conditions, the critical pore size D C , the adsorption amount Q and the critical pore volume V C under the corresponding conditions are obtained., critical specific surface area S C , average pore size D AV and D AS , the pore structure parameters of the model adsorbent and the adsorption isotherms of specific VOCs under different adsorption conditions are taken as known data, and substituted into equation 4 to obtain the specific values of a and b, and the VOCs adsorption amount prediction equation across adsorption temperature is obtained.

[0044] Preferably, the model adsorbent is one or more of ordered mesoporous silica, ordered mesoporous carbon and molecular sieve with concentrated pore size distribution.

[0045] Preferably, the VOCs are one of hydrocarbon organic matter, oxygen-containing organic matter, halogen-containing organic matter, nitrogen-containing organic matter and sulfur-containing organic matter.

[0046] The present application provides a VOCs adsorption amount prediction method across adsorption temperature. The present application uses two or more model adsorbents with concentrated pore size distribution, and obtains the regularity equation of the critical pore size of specific VOCs capable of filling adsorption under different adsorption conditions (temperature, relative pressure) by normalizing the pressure of the adsorption isotherm with respect to the saturation vapor pressure under the corresponding adsorption temperature, using the method of controlling variables. Since the pores smaller than the critical pore size D C filling adsorption occurs with high pore volume utilization, filling adsorption follows the filling adsorption mechanism of adsorption space, and the adsorption amount of this part of the pores to VOCs is directly related to the pore volume size. The pores larger than the critical pore size D C occur monolayer or multilayer adsorption surface coverage adsorption mechanism, and the adsorption amount of this part of the pores to VOCs is directly related to the specific surface area. On this basis, the adsorption amount prediction equation is proposed according to the pore volume of the pores that have filling adsorption and the specific surface area of the pores that have coverage adsorption, respectively. Since the mechanisms of the two parts of adsorption are different, their contribution to the VOCs adsorption amount and calculation methods are also different. The present application takes pore size D, relative pressure P / P0 and adsorption temperature T as variables, introduces the coefficients of filling adsorption and coverage adsorption, and uses the pore structure parameters of two or more model materials and their adsorption isotherms of VOCs as known data to solve the equation coefficients, so as to obtain the VOCs adsorption amount prediction equation across adsorption temperature. This equation can be used for adsorbents with the same or similar surface properties to predict the VOCs adsorption amount and isotherm under different adsorption temperatures.

[0047] The prediction method for volatile organic compound adsorption capacity across adsorption temperature provided by the application has a solid theoretical basis, and each variable in the equation has a clear physical meaning. The results of the examples show that the adsorption isotherms obtained by the prediction method of the application have high consistency with the measured adsorption isotherms, and the prediction method is also applicable to other adsorption materials without concentrated pore size distribution, and has good accuracy and scalability in predicting the adsorption capacity of specific VOCs and the adsorption isotherm of the VOCs at different adsorption temperatures. The prediction method provided by the application is simple to calculate, has clear physical meaning, high accuracy, and wide application range, and provides a reference basis for the selection of adsorption materials suitable for different VOCs, and provides theoretical support for the design of efficient VOC adsorption materials, the research of adsorption and desorption process, and the optimization of VOC adsorption process. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 A schematic diagram of the prediction method for volatile organic compound adsorption capacity across adsorption temperature;

[0049] Figure 2 A pore size distribution of a model adsorption material in Example 1;

[0050] Figure 3 A change of cumulative pore volume with pore size of the model adsorption material in Example 1;

[0051] Figure 4 A change of cumulative specific surface area with pore size of the model adsorption material in Example 1;

[0052] Figure 5 Static adsorption isotherms of benzene of the model adsorption material in Example 1 at multiple adsorption temperatures;

[0053] Figure 6 Normalized static adsorption isotherms of benzene relative to the saturated vapor pressure P0 at each adsorption temperature in Example 1;

[0054] Figure 7 A linear relationship equation between the critical relative pressure (P C / P0) and the adsorption temperature (T) of benzene in the filling type adsorption in the pores of different sizes in Example 1;

[0055] Figure 8 A linear relationship equation of the coefficients k P and d P of equation 1 varying with the critical pore size D C in the adsorption process of benzene at different temperatures in Example 1;

[0056] Figure 9 A pore volume of pores in a specific pore size range obtained by cumulative pore volume in Example 1;

[0057] Figure 10 For the cumulative specific surface area in Example 1 to obtain the specific surface area of the pores in a specific pore size range;

[0058] Figure 11 For the trend curve of the filling adsorption coefficient (a) of the model adsorbent with different pore sizes in Example 1 as a function of pressure;

[0059] Figure 12 For the effect of adsorption temperature T on the filling adsorption coefficient a in Example 1;

[0060] Figure 13 For the trend curve of the covering adsorption coefficient (b) of the model adsorbent with different pore sizes in Example 1 as a function of pressure;

[0061] Figure 14 For the effect of adsorption temperature T on the covering adsorption coefficient (b) in MCM-41-3.0 in Example 1;

[0062] Figure 15 For the effect of adsorption temperature T on the covering adsorption coefficient (b) in MCM-41-4.0 in Example 1;

[0063] Figure 16 For the effect of adsorption temperature T on the covering adsorption coefficient (b) in MCM-41-4.5 in Example 1;

[0064] Figure 17 For the trend of the slope k b as a function of pore size at 5°C and 45°C;

[0065] Figure 18 For the trend of the coefficient of the equation of the slope k b as a function of temperature and pore size in Example 1;

[0066] Figure 19 For the comparison of the predicted and measured normalized adsorption isotherms of benzene by the cross-temperature adsorption amount prediction equation 4.1 for the MCM-41 adsorbent at different adsorption temperatures in Example 1;

[0067] Figure 20 For the comparison of the predicted and measured adsorption isotherms of the MCM-41 adsorbent at 5 different adsorption temperatures by multiplying the relative pressure P / P0 in the isotherm by the saturation vapor pressure P0 at the corresponding temperature in Example 1;

[0068] Figure 21 For the pore size distribution of the porous silica material without a concentrated pore size distribution in Example 2;

[0069] Figure 22Comparison of predicted and measured adsorption isotherms at 25°C for the porous silica material in Example 2 without a concentrated pore size distribution;

[0070] Figure 23 Comparison of predicted and measured adsorption isotherms at 25°C for the porous silica material in Example 2 without a concentrated pore size distribution;

[0071] Figure 24 Static adsorption isotherms for acetone at 5°C, 15°C, 25°C, 35°C, 45°C for the model adsorbent in Example 3;

[0072] Figure 25 Static adsorption isotherms for acetone normalized to the saturated vapor pressure at each temperature for the model adsorbent in Example 3;

[0073] Figure 26 Linear relationship equations between the critical relative pressure (P C / P0) and the adsorption temperature (T) for the different size pores in Example 3;

[0074] Figure 27 Linear relationship equations for the coefficients k P and d P in Equation 1 as a function of the critical pore diameter D C for the adsorption of acetone at different adsorption temperatures in Example 3;

[0075] Figure 28 Trend curves for the filling adsorption coefficient (a) as a function of pressure for the model adsorbents of different pore sizes in Example 3;

[0076] Figure 29 Effect of the adsorption temperature T on the filling adsorption coefficient a in Example 3;

[0077] Figure 30 Effect of the pore size and the adsorption temperature T on the coverage adsorption coefficient (b) in the model adsorbents of different pore sizes in Example 3;

[0078] Figure 31 Equation for the slope k b as a function of temperature and pore size in Example 3;

[0079] Figure 32 Comparison of predicted and measured adsorption isotherms for MCM-41-4.0 adsorbing acetone at different adsorption temperatures in Example 3;

[0080] Figure 33 Pore size distributions for the two porous silica materials without a concentrated pore size distribution in Example 4;

[0081] Figure 34 Comparison of predicted and measured adsorption isotherms for the two porous silica materials without a concentrated pore size distribution in Example 4 for acetone adsorption at a temperature of 35°C;

[0082] Figure 35 Comparison of predicted and measured adsorption isotherms for the porous silica material without a concentrated pore size distribution in Example 4 for acetone adsorption at a temperature of 35°C, before normalization. DETAILED DESCRIPTION

[0083] The present application provides a method for predicting the adsorption amount of volatile organic compounds (VOCs) across adsorption temperatures, comprising the following steps:

[0084] (1) providing two or more porous materials with a concentrated pore size distribution as model adsorbents, testing the pore structure parameters of the model adsorbents, including pore size distribution, cumulative pore volume as a function of pore size distribution, total pore volume V, cumulative specific surface area as a function of pore size distribution, total specific surface area S;

[0085] (2) testing the adsorption isotherms of a model adsorbent for a specific VOC at multiple adsorption temperatures, obtaining the static adsorption isotherms after pressure normalization by dividing each pressure point on the static adsorption isotherm by the saturation vapor pressure P0 at the corresponding temperature;

[0086] According to the static adsorption isotherms after pressure normalization, the relative pressure range corresponding to the filling adsorption of the model adsorbent is obtained, and the middle value of the relative pressure range is taken as the critical relative pressure P C / P0; the critical relative pressure P C / P0 corresponds to the middle value of the pore size distribution of the model adsorbent, and the middle value of the pore size distribution is taken as the critical pore size D C C ;

[0087] The critical relative pressure P C / P0 of the model adsorbent is linearly fitted with the adsorption temperature T, to obtain the linear relationship equation between the critical relative pressure P C / P0 and the adsorption temperature at a specific pore size:

[0088] P C / P0=k P ×T+d P , equation 1;

[0089] where P C / P0 is the critical pressure P C ​critical relative pressure relative to the saturated vapor pressure P0 at the corresponding adsorption temperature;

[0090] T is the adsorption temperature, ℃;

[0091] k P is the slope of the linear relationship between the relative pressure and the adsorption temperature;

[0092] d P is the value of P C / P0 when the relative pressure approaches 0 in the linear relationship;

[0093] According to the model, the different P C / P0 values corresponding to different adsorption temperatures T of the adsorbent material are solved to obtain the coefficients k P and d P in equation 1 corresponding to the adsorbent material;

[0094] (3) Refer to the method of step (2), obtain the coefficients k P and d P in equation 1 corresponding to other model adsorbent materials;

[0095] (4) Linearly fit the k C and d C of the linear relationship equation between the critical relative pressure P P / P0 and the adsorption temperature T at multiple critical pore diameters D P , respectively, with respect to the respective critical pore diameters D C , to obtain the linear relationship equations of the coefficients k P and d P with the critical pore diameter D C , k P =k P1 ×D C +k P0 and d P =d P1 ×D C +d P0 , thereby obtaining the linear relationship equation of the filled adsorption critical relative pressure P C / P0 with the adsorption temperature T and the pore size D C :

[0096] P C / P0=(k P1 ×D C +k P0 )×T+(d P1 ×D C +d P0 ), equation 2;

[0097] wherein P C / P0 is the critical pressure PC The critical relative pressure relative to the saturated vapor pressure P0 at the corresponding adsorption temperature;

[0098] T is the adsorption temperature, in °C;

[0099] D C The relative pressure is P C At / P0, the critical pore size at which packed adsorption can occur, in nm;

[0100] k P1 and k P0 k P With the critical aperture D C The slope and intercept of the linear relationship equation;

[0101] d P1 and d P0 d respectively P With the critical aperture D C The slope and intercept of the linear relationship equation;

[0102] Equation 2 is used to obtain different relative pressures P C At / P0, the critical pore size D that enables packed adsorption is C The matching equation between adsorption temperature T and the adsorption temperature is as follows:

[0103] D C =(P C / P0-k P0 ×Td P0 ) / (k P1 ×T+d P1 Equation 3;

[0104] Among them, D C P C / P0, T, k P1 k P0 d P1 and d P0 The meaning represented is the same as in Equation 2;

[0105] (5) The critical channel size D C Using the pore structure parameters as the dividing point, the cumulative pore volume and the cumulative specific surface area as the pore size distribution are measured to obtain the critical pore size D of the model adsorbent material. C The following hole volume V C and critical channel size D C The specific surface area S of the above holes C ;

[0106] (6) Based on the pore volume V of the pores where filling adsorption has occurred CS is the specific surface area of the pores in which the coverage adsorption occurs C The contribution of the VOCs adsorption amount, and the pore size of the adsorbent material, relative pressure and adsorption temperature of different models are introduced into the adsorption amount prediction equation as parameters, and the VOCs adsorption amount prediction equation which can be extended to the prediction of adsorption isotherm at different adsorption temperatures T is obtained:

[0107] Q = a x V C + b x S C = f(D AV , P / P0, T) x V C + g(D AS , P / P0, T) x S C Equation 4

[0108] In equation 4,

[0109] Q is the adsorption amount of VOCs per unit mass of adsorbent, g / g;

[0110] V C is the pore volume of the pores below the critical pore size, that is, the critical pore volume, cm 3 / g;

[0111] S C is the specific surface area of the pores above the critical pore size, that is, the critical specific surface area, m 2 / g;

[0112] D AV is the average pore size of the pores in which the filling adsorption occurs, nm; wherein D AV = 4V C / (S-S C ), S is the total specific surface area, m 2 / g;

[0113] D AS is the average pore size of the pores in which the coverage adsorption occurs, nm; wherein D AS = 4(V-V C ) / S C , V is the total pore volume, cm 3 / g;

[0114] T is the adsorption temperature, ℃;

[0115] P / P0 is any relative pressure point on the adsorption isotherm normalized with respect to the saturated vapor pressure at the corresponding temperature; P0 is the saturated vapor pressure of VOCs at the corresponding adsorption temperature T, mbar;

[0116] a is the coefficient of filling adsorption, that is, the adsorption amount of VOCs per unit pore volume, g / cm 3 , wherein a = f(D AVP / P0, T) represents that the coefficient a is a function of pore diameter D AV , relative pressure P / P0 and adsorption temperature T.

[0117] b is the coefficient of the coverage type adsorption, i.e. the adsorption amount of VOCs per unit specific surface area, g / m 2 , wherein b = g(D AS P / P0, T) represents that the coefficient b is a function of pore diameter D AS , relative pressure P / P0 and adsorption temperature T.

[0118] (7) By testing the pore structure of a plurality of model adsorption materials and the adsorption isotherm under different adsorption conditions, the critical pore diameter size D C , adsorption amount Q, critical pore volume V C , critical specific surface area S C , average pore diameter D AV and D AS , the specific values of a and b are obtained by substituting the pore structure parameters of the model adsorption material and the adsorption isotherm of a specific VOC under different adsorption conditions into equation 4, and the prediction equation of the adsorption amount of volatile organic compounds across the adsorption temperature is obtained.

[0119] The present application provides two or more porous materials with concentrated pore diameter distribution as model adsorption materials, and tests the pore structure parameters of the model adsorption materials, which include pore diameter distribution, change of cumulative pore volume with pore diameter distribution, total pore volume V, change of cumulative specific surface area with pore diameter distribution, and total specific surface area S. In the present application, the porous material is preferably one or more of ordered mesoporous silica, ordered mesoporous carbon and molecular sieve. In the present application, when the pore diameter distribution is concentrated within the range of 2.0 nm, and the specific surface area of the part of the pores accounts for more than 90% of the total specific surface area of the material, it is set as an adsorption material with concentrated pore diameter distribution. In the present application, the concentrated pore diameter of the adsorption material is preferably within the range of micropore and small mesopore, and the pore size is preferably equal to or several times the molecular size of VOCs.

[0120] In the present application, the pore structure parameters of the adsorption material are preferably tested by using a commercial specific surface area and pore structure analyzer, and the pore structure parameters of the adsorption material are obtained by using the calculation model of DFT cylindrical pores.

[0121] In the present application, the adsorption isotherm of a specific VOC under a plurality of adsorption temperatures is tested for one model adsorption material, and the static adsorption isotherm after pressure normalization is obtained by dividing each pressure point on the static adsorption isotherm by the saturated vapor pressure P0 at the corresponding temperature, and the relative pressure range corresponding to the filling type adsorption of the model adsorption material is obtained according to the static adsorption isotherm after pressure normalization, and the middle value of the relative pressure range is taken as the critical relative pressure PC / P0, the critical relative pressure P of the adsorbent material in this model. C Linear fitting of / P0 with adsorption temperature T yields the critical relative pressure P at a specific pore size. C The linear relationship between / P0 and adsorption temperature is shown in the equation. For model adsorbents with concentrated pore size distribution, their adsorption isotherms exhibit typical Type VI adsorption isotherm characteristics. During packed adsorption, the adsorption capacity increases rapidly within a specific pressure range. This change can be directly reflected in the adsorption isotherm, indicating the critical pressure P corresponding to packed adsorption of model adsorbents with specific pore sizes. C .

[0122] According to the Kelvin equation, the adsorption of gas molecules on porous materials results in filled adsorption within pores of a specific size. It can be observed that, for the same pore size, as the adsorption temperature increases, the relative pressure required for filled adsorption to occur also increases, with the critical relative pressure P... C There is a correlation between / P0 and the corresponding adsorption temperature T. Under the same adsorption temperature, the larger the pore size of the model adsorbent material, the greater the relative pressure required for filled adsorption. A correlation exists between the relative pressure and the corresponding critical pore size. By matching the critical relative pressure at different temperatures for the same pore size with the adsorption temperature, linear fitting can be used to obtain the critical relative pressure (P0) for a specific pore size. C The linear relationship between / P0) and adsorption temperature (T) is expressed as follows:

[0123] P C / P0=k P ×T+d P Equation 1.

[0124] Based on the different adsorption temperatures T corresponding to different P values ​​of the adsorbent material in this model C The P0 value is used to solve for the coefficient k in Equation 1 corresponding to the adsorbent material in this model. P and d P Furthermore, the coefficients k in Equation 1 corresponding to other model adsorbent materials are obtained. P and d P .

[0125] This invention uses multiple critical apertures D C Below, the critical relative pressure P C The linear relationship between P0 and adsorption temperature T is represented by the equation k. P and d P Relative to their respective critical aperture D C Perform linear fitting to obtain the coefficients k. P and d PWith critical pore size D C The linear equation k P = k P1 × D C + k P0 and d P = d P1 × D C + d P0 , so as to obtain the linear equation of the critical relative pressure P C / P0 of the filling type adsorption varying with the adsorption temperature T and the pore size D C :

[0126] P C / P0 = (k P1 × D C + k P0 ) × T + (d P1 × D C + d P0 ), equation 2.

[0127] By using the equation, the matching relationship between the critical relative pressure P C / P0 of the filling type adsorption and the critical pore size D C under different adsorption temperatures T can be solved.

[0128] Further, by using equation 2, the matching relationship equation between the critical pore size D C under different critical relative pressure P C / P0 and the adsorption temperature T can be obtained:

[0129] D C = (P C / P0 - k P0 × T - d P0 ) / (k P1 × T + d P1 ), equation 3.

[0130] By using equation 3, the critical pore size D C under different adsorption temperatures T and relative pressure P / P0 corresponding to the filling type adsorption can be solved; with the critical pore size D C as a demarcation point, the pore volume V C of the pores below the critical pore size and the specific surface area S C of the pores above the critical pore size of the model adsorption material can be obtained according to the results of the pore structure test. By using equation 3, the critical relative pressure P C / P0 of the filling type adsorption and the critical pore size D C under the corresponding adsorption temperature T can be solved.The matching relationship between the critical pore size D C corresponding to different relative pressures is obtained C The critical pore volume V C and the critical specific surface area S C corresponding to different critical pore sizes D C are obtained in combination with the pore structure parameters. C The pores smaller than the critical pore size D C occur high pore volume utilization filling adsorption, and the filling adsorption follows a filling mechanism of adsorption space, and the adsorption amount of VOCs of the pores is directly related to the pore volume size. The pores larger than the critical pore size D C occur monolayer or multilayer adsorption covering mechanism, and the adsorption amount of VOCs of the pores is directly related to the specific surface area. The adsorption mechanisms of the two parts are different, and therefore the contribution amount of VOCs adsorption and the calculation method are also different.

[0131] The present application is based on the contribution of the pore volume V C of the pores occurring filling adsorption and the specific surface area S C of the pores occurring covering adsorption to the VOCs adsorption amount, and introduces the pore size, relative pressure and adsorption temperature of different model adsorption materials as parameters into the adsorption amount prediction equation, to obtain a VOCs adsorption amount prediction equation across adsorption temperatures which can be extended to the prediction of adsorption isotherms under different adsorption temperatures T:

[0132] Q = a x V C +b x S C =f(D AV ,P / P0,T) x V C +g(D AS ,P / P0,T) x S C Equation 4.

[0133] Through the pore structure of a plurality of model adsorption materials and the adsorption isotherm test under different adsorption conditions, the critical pore size D C , the adsorption amount Q, the critical pore volume V C , the critical specific surface area S C , the average pore size D AV and D AS corresponding to the conditions are obtained, the pore structure parameters of the model adsorption materials and the adsorption isotherms of specific VOCs under different adsorption conditions are taken as known numbers, and substituted into equation 4 to obtain the specific values of a and b, and the volatile organic compound adsorption amount prediction equation across adsorption temperatures is obtained.

[0134] Based on the obtained volatile organic compound adsorption amount prediction equation across adsorption temperatures, the critical pore size D C corresponding to the critical pore volume VC Critical specific surface area S C Substituting known values ​​into the equation, the trend of adsorption amount changing with relative pressure at different adsorption temperatures is solved. By multiplying the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 at the corresponding temperature, the predicted adsorption isotherm before normalization at the corresponding adsorption temperature can be obtained; thus, the adsorption amount and isotherm of VOCs at different temperatures can be predicted using the same equation.

[0135] In this invention, a schematic diagram of the method for predicting the adsorption amount of volatile organic compounds across adsorption temperatures is shown below. Figure 1 As shown. Figure 1 In this context, pores of different sizes, under specific adsorption conditions (specific VOCs type, temperature, and pressure), have pore sizes smaller than the critical pore size (D). C The pores of the sample underwent filling adsorption, while those larger than the critical pore size (D) were subjected to adsorption. C The pores undergo capping adsorption. Commercially available instruments can be used to measure pore structure data, yielding results smaller than the critical pore size (D). C The orifice volume (V) of all channels C =V1+V2+...V n ) and larger than the critical aperture size (D) C The specific surface area (S) of all channels C =S1+S2+...+S n By introducing coefficients for packed and covered adsorption as variables, including pore size D, relative pressure P / P0, and adsorption temperature T, a prediction equation for VOCs adsorption capacity across adsorption temperature is obtained. This equation can be used to predict the VOCs adsorption capacity and isotherm of adsorbents with the same or similar surface properties at different adsorption temperatures.

[0136] Based on the obtained equation for predicting the adsorption capacity of volatile organic compounds across the adsorption temperature, the critical pore size D under the corresponding adsorption conditions (adsorption temperature T, relative pressure P / P0) can be determined by using the pore structure parameters of the model adsorbent material. C The corresponding critical pore volume V C Critical specific surface area S C Substituting known values ​​into the equation, the trend of adsorption amount changing with relative pressure at different adsorption temperatures is solved. By multiplying the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 at the corresponding temperature, the predicted adsorption isotherm before normalization at the corresponding adsorption temperature can be obtained; thus, the adsorption amount and isotherm of VOCs at different temperatures can be predicted using the same equation.

[0137] The cross-adsorption temperature volatile organic compound adsorption amount prediction method provided by the present application will be described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0138] Example 1

[0139] A series of ordered mesoporous silica MCM-41 materials with concentrated pore size distribution were used as model adsorbents, which were named MCM-41-3.0, MCM-41-4.0, and MCM-41-4.5, respectively. The pore size distribution of the materials was obtained by the DFT cylindrical pore calculation model with the help of a commercial pore structure and specific surface area tester. The results showed that the series of model adsorbents had concentrated pore size distribution, and the most probable pore sizes were 3.0 nm, 4.0 nm, and 4.5 nm, respectively. The pore size distribution of the model adsorbents is shown in Figure 2 The cumulative pore volume as a function of pore size is shown in Figure 3 , and the cumulative specific surface area as a function of pore size is shown in Figure 4 .

[0140] The static adsorption isotherms of benzene on the three model adsorbents with the most probable pore sizes of 3.0 nm, 4.0 nm, and 4.5 nm at 5℃, 15℃, 25℃, 35℃, and 45℃ were tested by an intelligent gravimetric analyzer (IGA), as shown in Figure 5 .

[0141] By dividing each pressure point on the adsorption isotherm by the saturation vapor pressure at the corresponding temperature, the static adsorption isotherms after pressure normalization were obtained, as shown in Figure 6 . According to the Kelvin equation, the adsorption of gas molecules on porous materials will form filled adsorption in pores below a certain size. According to the normalized adsorption isotherms, the relative pressure intervals corresponding to the occurrence of filled adsorption of each model adsorbent were obtained, and the middle value of the relative pressure interval was taken as the critical relative pressure point (P C / P0). This critical relative pressure point was corresponded to the middle value of the pore size distribution of the model adsorbent, and the pore size at this point was taken as the critical pore size (D C ) at which filled adsorption could occur at the relative pressure point P C . According to the normalized adsorption isotherms of the three model adsorbents (pore sizes of 3.0 nm, 4.0 nm, and 4.5 nm) at multiple temperatures (5, 15, 25, 35, and 45℃), the middle points of the stages of rapid rise corresponding to the occurrence of filled adsorption (critical relative pressure P C / P0) were determined, as shown in Table 1.

[0142] Table 1 The relative pressure (P / P0) of the middle point of the corresponding fast rising stage when filling adsorption occurs on the normalized benzene adsorption isotherm C / P0)

[0143]

[0144] According to the Kelvin equation, the adsorption of gas molecules on porous materials will form filling adsorption in pores below a certain size. It can be found that in the same pore size, the higher the corresponding relative pressure required for filling adsorption to occur, the higher the critical relative pressure P C / P0) and the corresponding adsorption temperature T. Under the same adsorption temperature, the larger the pore size of the model adsorption material, the larger the corresponding relative pressure required for filling adsorption to occur, and there is a correlation between the relative pressure and the corresponding critical pore size. By matching the critical relative pressure at different temperatures in the same pore size with the adsorption temperature, a linear relationship equation between the critical relative pressure (P C / P0) and the adsorption temperature (T) at a certain pore size can be obtained by linear fitting:

[0145] P C / P0=k P ×T+d P , equation 1;

[0146] wherein,

[0147] P C / P0 is the critical pressure P C relative to the critical relative pressure of the saturated vapor pressure P0 at the corresponding adsorption temperature;

[0148] T is the adsorption temperature, ℃;

[0149] k P is the slope of the linear relationship between the relative pressure and the adsorption temperature;

[0150] d P is the value of P C / P0 when the relative pressure approaches 0 in the linear relationship;

[0151] Based on the adsorption isotherms at different adsorption temperatures in the same pore size, by corresponding the critical relative pressure (P C / P0) of the middle point of the corresponding fast rising stage when filling adsorption occurs at different adsorption temperatures with the temperature T, and performing linear fitting, it is found that there is a good linear relationship between the critical relative pressure of the adsorption isotherm at different temperatures in the same size pore and the adsorption temperature. The critical relative pressure (P C / P0) and the adsorption temperature (T) in different size pores.The linear relationship equation between / P0) and adsorption temperature (T) is shown in the linear fitting result as follows: Figure 7 As shown, the linear relationship equations are as follows:

[0152] At 3.0nm, P C / P0=0.00116×T+0.072;

[0153] At 4.0nm, P C / P0=0.00152×T+0.163;

[0154] At 4.5nm, P C / P0=0.00158×T+0.213.

[0155] Critical relative pressure (P) across three orifice sizes C By comparing the linear relationship equation between / P0) and adsorption temperature (T), it can be found that the linear relationship equation P C / P0=k P ×T+d P coefficient k P and d P The results show certain differences in different aperture sizes, as shown in Table 2.

[0156] Table 2. Critical relative pressure (P0) for benzene to undergo packed adsorption in pores of different sizes. C The coefficient k of the linear relationship equation (Equation 1) between / P0) and adsorption temperature (T) P and d P

[0157] Aperture coefficient k P ]] coefficient d P ]] 3.0 nm 0.00116 0.072 4.0 nm 0.00152 0.163 4.5 nm 0.00158 0.213

[0158] Based on multiple orifice sizes, the critical relative pressure (P) C The coefficient k of the linear relationship equation between / P0) and adsorption temperature (T) P and d P With the material pore size D C Changes yield the aperture D C For critical relative pressure (P) C The influence law of / P0) can be obtained through linear fitting; the critical relative pressure (P) of the packed adsorption can be obtained. C / P0) varies with adsorption temperature T and pore size D C The changing matching equation:

[0159] P C / P0=f(D C )×T+g(D C )=(k P1 ×D C +k P0)×T+(d P1 ×D C +d P0 Equation 2;

[0160] Among them, P C / P0 is the critical pressure P C The critical relative pressure relative to the saturated vapor pressure P0 at the corresponding adsorption temperature;

[0161] T is the adsorption temperature, in °C;

[0162] D C The relative pressure is P C At / P0, the critical pore size at which packed adsorption can occur, in nm;

[0163] k P1 and k P0 k P With the critical aperture D C The slope and intercept of the linear relationship equation;

[0164] d P1 and d P0 d respectively P With the critical aperture D C The slope and intercept of the linear relationship equation.

[0165] This equation can be used to solve for the critical relative pressure P at different adsorption temperatures T that allow for packed adsorption. C / P0 and critical aperture size D C The matching relationship between them. By comparing the critical relative pressure (P) in three different orifice sizes. C The coefficient k in the linear relationship equation between / P0) and adsorption temperature (T) P and d P Linear fitting was performed with respect to their respective pore sizes (3.0 nm, 4.0 nm, and 4.5 nm) to obtain the coefficient k. P and d P With aperture D C The linear relationship equation of change k P =0.00029×D C +0.0003 and d P =0.094×D C -0.209, such as Figure 8 As shown, the critical relative pressure (P) of the packed adsorption is thus obtained. C / P0) varies with adsorption temperature T and pore size D C The changing matching equation:

[0166] P C / P0=(0.00029×DC +0.0003) x T + (0.094 x D C -0.209), Equation 2.1.

[0167] wherein P C / P0 is the critical pressure P C relative to the saturation vapor pressure P0 at the corresponding adsorption temperature;

[0168] T is the adsorption temperature, °C;

[0169] D C is the critical pore size, nm, at which the filling-type adsorption can occur at the relative pressure P C / P0.

[0170] Using this equation, the matching relationship between the critical relative pressure P C / P0 and the critical pore size D C at different adsorption temperatures T, and the matching relationship between the critical pore size D C and the adsorption temperature T at different relative pressures P C / P0 can be solved.

[0171] Using Equation 2, the matching relationship between the critical pore size D C and the adsorption temperature T at different relative pressures P C / P0 can be solved.

[0172] D C = (P C / P0 - k P0 x T - d P0 ) / (k P1 x T + d P1 ), Equation 3.

[0173] wherein D C , P C / P0, T, k P1 , k P0 , d P1 and d P0 have the same meanings as in Equation 2.

[0174] Using Equation 3, the critical pore size D C at which the filling-type adsorption can occur at different adsorption conditions (adsorption temperature T, relative pressure P / P0) can be solved.

[0175] Using the obtained equation (Equation 2.1) and the method of Equation 3, the matching relationship between the critical relative pressure P C and the adsorption temperature T at different critical pore sizes DAt / P0, the critical pore size D that enables packed adsorption is C Matching relationship with adsorption temperature T:

[0176] D C =(P C / P0-0.0003×T+0.209) / (0.00029×T+0.0936), Equation 3.1;

[0177] This equation can be applied to different critical relative pressures P under different adsorption temperatures T. C / P0 corresponds to the critical pore size D that enables packed adsorption. C The calculation is based on the critical channel size D. C Using the pore structure test results as the dividing point, the critical pore size D of the model adsorbent material was obtained. C The following hole volume V C and the critical channel size D C The specific surface area S of the above holes C Based on Equation 3.1 and the pore structure parameters of the model adsorbent material, the critical pore size D can be calculated for any given condition. C The orifice volume V of the orifice below the critical orifice size at that time C The specific surface area S of holes above the critical channel size C Among them, the pore volume below a certain size can be obtained by accumulating the pore volume, such as... Figure 9 As shown, the specific surface area above a certain size can be obtained by accumulating the specific surface area, such as... Figure 10 As shown.

[0178] According to the Kelvin equation, the adsorption of gas molecules on porous materials results in packed adsorption within pores of a specific size. Since packed adsorption follows a packed mechanism, the amount of adsorption in this region is related to the density and the pore volume where packed adsorption occurred. In contrast, pores where packed adsorption does not occur exhibit a monolayer or multilayer covering mechanism, and the amount of adsorption in this region is related to the corresponding specific surface area.

[0179] Based on the pore volume V of the pores where filling adsorption occurred C The specific surface area S of the pores where covering adsorption occurred C The contribution of different models to VOCs adsorption capacity was investigated, and the pore size, relative pressure, and adsorption temperature of the adsorption materials were introduced as parameters into the adsorption capacity prediction equation. This yielded a VOCs adsorption capacity prediction equation that can be extended to the adsorption isotherm prediction at different adsorption temperatures, spanning across adsorption temperatures. The adsorption capacity Q and pore volume V are mentioned. C Specific surface area S C The equation for predicting the adsorption capacity of volatile organic compounds across the adsorption temperature is Equation 4:

[0180] Q = a x V C +b x S C = f(D AV , P / P0, T) x V C + g(D AS , P / P0, T) x S C Equation 4;

[0181] In Equation 4, Q is the adsorption amount of VOCs per unit mass of the adsorbent, g / g;

[0182] V C is the pore volume of pores below the critical pore size, i.e., the critical pore volume, cm 3 / g;

[0183] S C is the specific surface area of pores above the critical pore size, i.e., the critical specific surface area, m 2 / g.

[0184] D AV is the average pore diameter of pores in which the filling-type adsorption occurs, nm; wherein D A = 4V C / (S-S C ), S is the total specific surface area, m 2 / g;

[0185] D AS is the average pore diameter of pores in which the covering-type adsorption occurs, nm; wherein D AS = 4(V-V C ) / S C , V is the total pore volume, cm 3 / g;

[0186] T is the adsorption temperature, °C;

[0187] P / P0 is any relative pressure point on the adsorption isotherm normalized with respect to the saturated vapor pressure at the corresponding temperature;

[0188] P0 is the saturated vapor pressure of VOCs at the corresponding adsorption temperature T, mbar;

[0189] a is the coefficient of the filling-type adsorption, i.e., the adsorption amount of VOCs per unit pore volume, g / cm 3 , wherein a = f(D AV , P / P0, T) indicates that the coefficient a is a function of the average pore diameter D AV , the relative pressure P / P0, and the adsorption temperature T;

[0190] b is the coefficient of the covering-type adsorption, i.e., the adsorption amount of VOCs per unit specific surface area, g / m 2 , wherein b = g(DAS (P / P0,T) indicates that coefficient b is the average aperture D. AS It is a function of relative pressure P / P0 and adsorption temperature T.

[0191] The static adsorption of benzene on a series of model adsorbents exhibits a typical Type IV adsorption isotherm, which can be roughly divided into three stages: In the initial stage of adsorption, the adsorption amount rapidly reaches a plateau with increasing pressure and then increases slowly. This is attributed to the gradual formation of monolayers or multilayers of benzene molecules on the mesoporous surface. In the middle stage of adsorption, the adsorption amount of benzene rises rapidly on the isotherm, which is caused by capillary condensation occurring in the concentrated pores. In the third stage of adsorption, the isotherm reaches a second plateau, and the increase in adsorption amount is slow. This is mainly due to the rearrangement of benzene molecules adsorbed in a packed manner in the pores, resulting in a slight increase in adsorption amount.

[0192] Method for calculating the coefficient (a) of packed adsorption:

[0193] By dividing the adsorption amount at each relative pressure point on the adsorption isotherm of the model adsorbent material by the total pore volume, the trend of the packed adsorption coefficient (a = Q / V) as a function of relative pressure can be obtained, such as... Figure 11 As shown. In the volumetric adsorption coefficient (a), the portion unaffected by relative pressure and pore size is set as a0, and the portion affected by pore size is set as a1 = f(D). AV The portion affected by relative pressure is set as a2 = f(P / P0), and the portion affected by adsorption temperature is set as a3 = f(T), and a = a0 + a1 + a2 + a3. Therefore, the packed adsorption coefficient a = a0 + f(D) AV )+f(P / P0)+f(T).

[0194] It can be observed that in the third stage of the adsorption isotherm, in the high-pressure region of the adsorption isotherm, the packed adsorption is basically completed. Simultaneously, with the increase of relative pressure, the coefficient (a) of the packed adsorption also shows a slight increasing trend. This is mainly attributed to the fact that VOCs molecules in the packed adsorption can undergo molecular rearrangement with the increase of relative pressure, leading to a slight increase in the coefficient (a). The increase in the coefficient (a) of the packed adsorption for different pore sizes is the same, i.e., the slope (0.11). Therefore, the change in coefficient a caused by relative pressure is a2 = 0.11 × P / P0, as shown below. Figure 11 As shown.

[0195] In the high-pressure region of the adsorption isotherm in the third stage, under the same relative pressure, the volumetric adsorption coefficient (a) corresponding to different pore sizes also shows certain differences, such as... Figure 11 As shown, the change in coefficient 'a' caused by the difference in aperture size is a1 = 0.06 × D. AVThe numerical value of the part not affected by the relative pressure and the pore size is a0=0.6, as shown in Figure 11 .

[0196] In the high-pressure region of the third-stage adsorption isotherm, the volume filling adsorption coefficient (a) also has certain differences corresponding to different adsorption temperatures in the same pore size, as shown in Figure 12 . With the increase of the adsorption temperature, the density of the adsorbed benzene in the unit pore volume will decrease, resulting in the regular change of the coefficient a, and the change of the coefficient a caused by the difference of the adsorption temperature is a3=-0.0013×T, as shown in Figure 12 .

[0197] According to the high-pressure region of the filling adsorption formed in the adsorption isotherm, and the influence of the difference of the pore size and the adsorption temperature between different model adsorption materials on the adsorption isotherm, the calculation equation of the coefficient (a) of the filling adsorption is obtained:

[0198] a=0.6+0.06×D AV +0.11×P / P0-0.0013×T

[0199] wherein D AV is the average pore size of the pore in which the filling adsorption occurs, nm; wherein D AV =4V C / (S-S C ), S is the total specific surface area, m 2 / g;

[0200] S C is the specific surface area of the pore above the critical pore size, m 2 / g;

[0201] P / P0 is any relative pressure point on the adsorption isotherm normalized with respect to the saturated vapor pressure at the corresponding temperature.

[0202] The calculation method of the coefficient (b) of the surface coverage adsorption:

[0203] The adsorption capacity at each relative pressure point on the adsorption isotherm of the model adsorption material is divided by the total surface area, and the trend of the coverage adsorption coefficient (b=Q / S) with the relative pressure is obtained, as shown in Figure 13 . In the low-pressure region of the adsorption isotherm, the adsorption capacity slowly increases, which is the gradual formation process of the monolayer or multilayer surface coverage adsorption. In this state, the volume filling adsorption has not yet begun, so the trend of this state can be used to obtain the relationship between the coefficient b and the relative pressure P / P0.

[0204] In the low pressure region of the first stage adsorption isotherm, the equation of the coefficient (b) of different pore size (b=k b ×P / P0+d b ) can be obtained by linear fitting the adsorption isotherm in the low pressure region, where d b is the intercept and k b is the slope, which are affected by the pore size and adsorption temperature.

[0205] For the MCM-41-3.0 model adsorbent, the linear fitting result of the coefficient (b) of surface coverage adsorption is b=0.00319×P / P0+0.0000496 when the adsorption temperature is 5℃, and the linear fitting result of the coefficient (b) of surface coverage adsorption is b=0.00214×P / P0+0.0000327 when the adsorption temperature is 45℃, as shown in the following table. Figure 14

[0206] For the MCM-41-4.0 model adsorbent, the linear fitting result of the coefficient (b) of surface coverage adsorption is b=0.00236×P / P0+0.0000352 when the adsorption temperature is 5℃, and the linear fitting result of the coefficient (b) of surface coverage adsorption is b=0.00147×P / P0+0.0000439 when the adsorption temperature is 45℃, as shown in the following table. Figure 15

[0207] For the MCM-41-4.5 model adsorbent, the linear fitting result of the coefficient (b) of surface coverage adsorption is b=0.00160×P / P0+0.000102 when the adsorption temperature is 5℃, and the linear fitting result of the coefficient (b) of surface coverage adsorption is b=0.00115×P / P0+0.000097 when the adsorption temperature is 45℃, as shown in the following table. Figure 16

[0208] Combining the MCM-41-3.0, MCM-41-4.0 and MCM-41-4.5 three model adsorbents, in the first stage of the adsorption isotherm, the equation of the coefficient (b) of different adsorption temperature and different pore size (b=k b ×P / P0+d b ) can be obtained by linear fitting the adsorption isotherm in the low pressure region, it can be found that the intercept d b and the slope k b in these equations are affected by the pore size and adsorption temperature. The values of the intercept d b and the slope k b of the coefficient (b) equation of surface coverage adsorption of the three model adsorbents with the most probable pore size of 3.0nm, 4.0nm and 4.5nm at 5℃ and 45℃ are shown in the following table.

[0209] ​​​Table 3 intercept d of the equation of the coefficient (b) of surface coverage adsorption of three model adsorbents with the most probable pore diameters of 3.0 nm, 4.0 nm and 4.5 nm at 5°C and 45°C b and the value of the slope k b

[0210] Aperture at 5°C k b ]]> at 5°C d b ]]> 45 °C k b ]]> 45 °C d b ]]> 3.0 0.00319 0.0000496 0.00214 0.0000327 4.0 0.00236 0.0000352 0.00147 0.0000439 4.5 0.00160 0.0001020 0.00115 0.0000970

[0211] It can be found that the value of the slope k b of the equation of the coefficient (b) of surface coverage adsorption decreases with the increase of the pore size of the material. Assuming that the pore size and the slope k b are linearly related, the slope is set as the equation k b = k k × D AS + d k , wherein D AS (D AS = 4(V-V C ) / S C ) is the average pore diameter of the pores for surface coverage adsorption.

[0212] According to the change trend of the slope k b of the equation of the coefficient (b) of surface coverage adsorption in the three model adsorbents with the pore diameters of 3.0 nm, 4.0 nm and 4.5 nm at 5°C, the equation k b = 0.00632-0.00103×D AS can be obtained, wherein D AS (D AS = 4(V-V C ) / S C ) is the average pore diameter of the pores for surface coverage adsorption, as shown in Figure 17 .

[0213] According to the change trend of the slope k b of the equation of the coefficient (b) of surface coverage adsorption in the three model adsorbents with the pore diameters of 3.0 nm, 4.0 nm and 4.5 nm at 45°C, the equation k b = 0.00412-0.00066×D AS can be obtained, wherein D AS (D AS = 4(V-V C ) / S C ) is the average pore diameter of the pores for surface coverage adsorption, as shown in Figure 17 .

[0214] It can be seen from Figure 17 that the slope k b of the coefficient (b) of surface coverage adsorption corresponding to the adsorption temperature T has an important influence, such as k b ​=0.00632-0.00103×D AS At 45℃, k b =0.00412 - 0.00066 × D AS This is mainly because as the adsorption temperature increases, the adsorption force of the pore walls of the adsorption material on VOCs molecules weakens, resulting in a decrease in the amount of benzene adsorbed per unit surface area. Therefore, the coefficient b also shows a regular change.

[0215] The slope k at different temperatures b The coefficients of the equation were linearly fitted with the adsorption temperature T (5℃ and 45℃) to obtain the slope k. b The equation showing the regularity of coefficients changing with temperature and aperture is k. b =(0.00659-5.5×10 -5 ×T)-(0.00108-9.25×10 -6 ×T)×D AS ,like Figure 18 As shown.

[0216] The coefficient of surface-covered adsorption (b) and the intercept d of the equation b The values ​​for different pore sizes and adsorption temperatures are shown in Table 3. The value for d at 5℃ is... b The average value is used to obtain d. b It is approximately 0.00006. Meanwhile, for the same pore size, the intercept d of the coverage adsorption coefficient (b) at different adsorption temperatures is... b There are also some differences, such as Figure 14 As shown, for a 3.0 nm aperture, the intercept d of coefficient b at 5 °C b The intercept d of coefficient b at 45℃ is 0.0000496. b The value is 0.0000327, therefore the intercept d of the adsorption temperature T with respect to the coefficient b can be obtained. P The incremental result is △ d b = -4.23 × 10 -7 ×T. Therefore, the intercept d of the covering adsorption coefficient b. b =0.00006 - 4.23 × 10 -7 ×T.

[0217] Therefore, by using aperture D AS The relative pressure P / P0 and adsorption temperature T are introduced as variables, with coefficient b. The equation for the surface-covered adsorption coefficient b during the adsorption of benzene at different temperatures is as follows:

[0218] b=((0.00659-5.5×10 -5 ×T)-(0.00108-9.25×10 -6×T)×D AS )×P / P0+(0.00006-4.23×10 -7 Equation 6.1 (×T);

[0219] In Equation 6.1, b is the coefficient of saturated adsorption, i.e., the amount of VOCs adsorbed per unit specific surface area, in g / m². 2 , where b = g(D AS (P / P0,T) indicates that coefficient b is the average aperture D. AS A function of relative pressure P / P0 and adsorption temperature T;

[0220] D AS The average pore size, in nm, represents the pore size of the channels where occlusive adsorption occurred.

[0221] D AS =4(VV) C ) / S C V is the total pore volume, in cm. 3 / g;

[0222] P / P0 is any relative pressure point on the adsorption isotherm normalized relative to the saturated vapor pressure at the corresponding temperature.

[0223] T is the adsorption temperature, in °C.

[0224] In summary, this invention utilizes the aperture D and relative partial pressure P... C / P0 and adsorption temperature T are introduced as parameters into the VOCs adsorption capacity prediction equation Q=a×V C +b×S C In the process, the adsorption coefficients a for packed structures and b for covered structures were obtained as a function of pore size D and relative partial pressure P. C The regularity equations for the changes in / P0 and adsorption temperature T are derived. From this, the prediction equation for the adsorption amount / isotherm across the adsorption temperature is derived, and the resulting equations for predicting the adsorption amount / isotherm of benzene at different temperatures are:

[0225] Q = (0.6 + 0.06 × D) AV +0.11×P / P0-0.0013×T)×V C +(((0.00659-5.5×10 -5 ×T)-(0.00108-9.25×10 -6 ×T)×D AS )×P / P0+(0.00006-4.23×10 -7 ×T))×S C Equation 4.1;

[0226] In Equation 4.1, Q represents the amount of VOCs adsorbed per unit mass of adsorbent material, in g / g;

[0227] V C The critical pore volume is the pore volume below the critical pore size, expressed in cm. 3 / g;

[0228] S C The specific surface area of ​​pores exceeding the critical pore size, i.e., the critical specific surface area, in m. 2 / g.

[0229] D AV The average pore size of the channels where packed adsorption occurred is in nm; where D A =4V C / (SS C S is the total specific surface area, m 2 / g;

[0230] D AS The average pore size of the channels where covering adsorption occurred is in nm; where D AS =4(VV) C ) / S C V is the total pore volume, in cm. 3 / g;

[0231] T is the adsorption temperature, in °C;

[0232] P / P0 is any relative pressure point on the adsorption isotherm normalized relative to the saturated vapor pressure at the corresponding temperature.

[0233] P0 is the saturated vapor pressure of VOCs at the corresponding adsorption temperature T, in mbar.

[0234] Using the same equation (Equation 4.1), the adsorption capacity of VOCs and isotherms at different temperatures can be predicted based on the pore structure parameters of the model adsorbent material. According to D... C The matching relationship between T and P / P0 (Equation 3.1) (D) C =(P C / P0-0.0003×T+0.209) / (0.00029×T+0.0936), yielding the critical pore size D for packed adsorption at different adsorption temperatures T and relative pressures P / P0. C By combining the pore structure parameters of the model adsorbent material, the critical pore size D can be obtained for any given condition. C Critical pore volume V at time C and critical specific surface area S C The adsorption isotherm values, including the adsorption temperature T, relative pressure P / P0, and their corresponding pore structure parameters (D), are used to determine the adsorption temperature T, relative pressure P / P0, and their corresponding pore structure parameters (D). AV D AS V C SC ) The predicted adsorption isotherms at different temperatures were calculated by substituting the adsorption amount prediction equation, that is, the adsorption amount / isotherm prediction across temperature was realized.

[0235] The pore structure parameters of MCM-41-4.0 and the adsorption temperature T (5℃, 15℃, 25℃, 35℃, 45℃) were substituted into the same adsorption amount prediction equation across temperature (equation 4.1) to calculate the trend of the adsorption amount of p-xylene of MCM-41-4.0 model adsorbent at multiple adsorption temperatures with the change of relative pressure, that is, the predicted normalized adsorption isotherm. The predicted and measured normalized adsorption isotherms at different adsorption temperatures are shown in Figure 19 It can be seen that the predicted normalized adsorption isotherm can well coincide with the measured normalized adsorption isotherm obtained by experimental test.

[0236] Based on the obtained adsorption amount prediction equation of volatile organic compounds across adsorption temperature, the critical pore diameter D C , the critical specific surface area S C , and the critical pore volume V C corresponding to the adsorption conditions (adsorption temperature T, relative pressure P / P0) can be obtained by the pore structure parameters of the model adsorbent. Substituting the above known numbers into the equation, the trend of the adsorption amount at different adsorption temperatures with the change of relative pressure P / P0 was solved, and the predicted adsorption isotherm before normalization at the corresponding adsorption temperature was obtained by multiplying the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 (49.58 mbar, 79.03 mbar, 127.61 mbar, 198.63 mbar, 299.2 mbar) at the corresponding temperature (5℃, 15℃, 25℃, 35℃, 45℃), that is, the predicted adsorption isotherm before normalization at the corresponding adsorption temperature was obtained. The VOCs adsorption amount and isotherm at different temperatures were predicted by the same equation, as shown in Figure 20 .

[0237] The VOCs adsorption amount prediction equation across adsorption temperature was obtained by exploring the critical pore channel size of the filling type adsorption and its change rule with the adsorption temperature. Based on the pore volume of the pores where the filling type adsorption occurred and the specific surface area of the pores where the covering type adsorption occurred, and taking the pressure and the adsorption temperature related parameters (saturated vapor) as variables, the VOCs adsorption amount prediction equation across adsorption temperature was obtained. According to the equation, the VOCs adsorption amount and isotherm at different temperatures can be predicted by the same equation according to the pore structure parameters of the adsorbent, which has important reference value for the development of VOCs adsorbent and technology.

[0238] Example 2

[0239] To further verify that the obtained adsorption amount prediction equation can be applied to predict the adsorption amount and adsorption isotherm of other conventional adsorbents for specific VOCs, in this embodiment, a porous silica material without a concentrated pore size distribution (e.g., as shown in FIG. 1) is used as the adsorbent, and the benzene adsorption amount prediction equation across the adsorption temperature obtained in Example 1 is used to verify the applicability of the equation to other adsorbents without a concentrated pore size distribution. Figure 21

[0240] The pore structure parameters of the adsorbent are tested using a commercial specific surface area and pore structure analyzer, and the pore structure parameters of the adsorbent are obtained by a DFT cylindrical pore calculation model. The critical pore size D C and the critical relative pressure P C / P0and the adsorption temperature T are matched in a ternary matching relationship equation (Equation 3.1), and the obtained pore structure parameters of the adsorbent are combined to obtain the critical pore size D C , the critical pore volume V C , the critical specific surface area S C , and the like corresponding to the adsorption conditions (adsorption temperature T, relative pressure P / P0) according to the relationship between the cumulative pore volume and the cumulative specific surface area with respect to the pore size.

[0241] The critical pore size D C and the critical relative pressure P C / P0and the adsorption temperature T in Example 1 are matched in a ternary matching relationship equation as follows:

[0242] D C =(P C / P0-0.0003×T+0.209) / (0.00029×T+0.0936), Equation 3.1.

[0243] The critical pore size D C , the critical pore volume V C , the critical specific surface area S C , and the like corresponding to the adsorption conditions are substituted into the benzene adsorption amount prediction equation across the temperature (Equation 4.1) as known quantities, and the trend of the adsorption amount with respect to the relative pressure under the corresponding adsorption temperature is solved as shown in FIG. 4. Figure 22

[0244] The benzene adsorption amount prediction equation across the adsorption temperature in Example 1 is as follows:

[0245] Q=(0.6+0.06×D AV +0.11×P / P0-0.0013×T)×V C +(((0.00659-5.5×10 -5 ×T)-(0.00108-9.25×10​​-6 xT)xD AS )xP / P0+(0.00006-4.23x10 -7 xT))xS C Equation 4.1;

[0246] The normalized adsorption isotherm of benzene at 25℃ on the porous silica adsorbent before normalization, i.e. the predicted adsorption isotherm, was calculated by multiplying the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 at the corresponding temperature (25℃) (127.61 mbar), as shown in Figure 23 . Figure 23 The comparison of the predicted adsorption isotherm and the measured adsorption isotherm of the porous silica adsorbent without a concentrated pore size distribution. It can be seen from Figure 23 that the prediction method provided by the present application can well coincide with the adsorption isotherm obtained by experimental testing.

[0247] It can be found that the method of the present application is also applicable to the prediction of the adsorption amount and the adsorption isotherm of other adsorbents without a concentrated pore size distribution at different adsorption temperatures for specific VOCs. The adsorption amount prediction equation obtained by the silica-based adsorbent in Example 2 can be directly used for the prediction of the adsorption amount of other silica-based adsorbents without a concentrated pore size distribution. Therefore, under the condition that the composition and surface properties of the materials are similar, the obtained adsorption amount prediction equation can be directly used for the prediction of the adsorption amount and the adsorption isotherm of other adsorbents at different adsorption temperatures. It shows that the VOCs adsorption amount and adsorption isotherm prediction method of the present application has good generalizability.

[0248] Example 3

[0249] From the derivation method of the adsorption amount prediction equation, it can be judged that the VOCs adsorption amount prediction method is not limited by the type of VOCs and has good generalizability. In order to further verify the generalizability of the adsorption amount prediction method, this example takes acetone as the adsorbate, tests the adsorption isotherms of a series of model adsorbents for acetone at multiple adsorption temperatures, and derives an equation applicable to the prediction of the adsorption amount of acetone across adsorption temperatures in combination with the pore structure parameters.

[0250] The ordered mesoporous silica MCM-41 materials with the most probable pore diameters of 3.0 nm, 4.0 nm and 4.5 nm in Example 1 were used as model adsorbents, as shown in Figure 2 , Figure 3 and Figure 4 . The static adsorption isotherms of the three model adsorbents for acetone at 5℃, 15℃, 25℃, 35℃ and 45℃ were tested by an intelligent gravimetric analyzer (IGA), as shown in Figure 24 .

[0251] The static adsorption isotherms after normalization of partial pressure were obtained by dividing each pressure point on the adsorption isotherm by the saturated vapor pressure at the corresponding temperature, as shown in Figure 25 Table 3. According to the normalized adsorption isotherms of the three model adsorbents (pore sizes of 3.0 nm, 4.0 nm, and 4.5 nm) at five temperatures (5, 15, 25, 35, and 45°C), the midpoints of the corresponding rapid rise stages (critical relative pressures P C / P0) of the filling-type adsorption were determined, as shown in Table 4.

[0252] Table 4 shows the values of the relative pressures (P C / P0) of the midpoints of the corresponding rapid rise stages of the filling-type adsorption on the normalized acetone adsorption isotherms.

[0253]

[0254] According to the method of Example 1, by matching the critical relative pressures at different temperatures in the same pore size with the adsorption temperature, a linear relationship equation between the critical relative pressure (P C / P0) and the adsorption temperature (T) at a specific pore size can be obtained by linear fitting. Linear relationship equations between the critical relative pressure (P C / P0) and the adsorption temperature (T) in pores of different sizes were obtained, and the results of linear fitting are shown in Figure 26 Table 5. The linear relationship equations are as follows:

[0255] For 3.0 nm, P C / P0 = 0.00102 × T + 0.126.

[0256] For 4.0 nm, P C / P0 = 0.00124 × T + 0.247.

[0257] For 4.5 nm, P C / P0 = 0.00168 × T + 0.302.

[0258] By comparing the linear relationship equations between the critical relative pressure (P C / P0) and the adsorption temperature (T) at three pore sizes (3.0 nm, 4.0 nm, and 4.5 nm), it can be found that the coefficients k C and d P of the linear relationship equation P P / P0 = k P × T + d P present certain differences in different pore sizes, as shown in Table 5.

[0259] Table 5 shows the values of the coefficients k P and d P in the linear relationship equation P C / P0 = k P × T + d P in the adsorption of acetone in pores of different sizes.C The coefficient k of the linear relationship equation (Equation 1) between / P0) and adsorption temperature (T) P and d P

[0260] Aperture coefficient k P ]]> coefficient d P ]]> 3.0 nm 0.00102 0.126 4.0 nm 0.00124 0.247 4.5 nm 0.00168 0.302

[0261] According to Equation 2, by considering the critical relative pressure (P) in three different aperture sizes... C The coefficient k in the linear relationship equation between / P0) and adsorption temperature (T) P and d P Linear fitting was performed with respect to their respective pore sizes (3.0 nm, 4.0 nm, and 4.5 nm) to obtain the coefficient k. P and d P With aperture D C The linear relationship equation of change k P =0.00041×D C +0.000253 and d P =0.118×D C -0.227, such as Figure 27 As shown, the critical relative pressure (P) of the packed adsorption is thus obtained. C / P0) varies with adsorption temperature T and pore size D C The changing matching equation:

[0262] P C / P0=(0.00041×D C +0.000253)×T+(0.118×D C -0.227), Equation 2.2;

[0263] Among them, P C / P0 is the critical pressure P C The critical relative pressure relative to the saturated vapor pressure P0 at the corresponding adsorption temperature;

[0264] T is the adsorption temperature, in °C;

[0265] D C The relative pressure is P C At / P0, the critical pore size at which packed adsorption can occur is in nm.

[0266] By combining the obtained equation (Equation 2.2) with the method in Equation 3, we can obtain D. C The matching relationship equation between T and P / P0 is Equation 3.2:

[0267] D C =(P CP0-0.000253xT+0.227) / (0.00041xT+0.118), Equation 3.2;

[0268] wherein P C P0is the critical pressure P C relative to the saturation vapor pressure P0at the corresponding adsorption temperature;

[0269] T is the adsorption temperature, °C;

[0270] D C is the critical pore size, nm, at which the filling-type adsorption can occur at the relative pressure P C / P0.

[0271] According to the method of Example 1, by introducing the pore size D, the relative partial pressure P C / P0and the adsorption temperature T as parameters into the VOCs adsorption amount prediction equation Q=a x V C +b x S C , the filling-type adsorption coefficient a (as shown in Figure 28 and Figure 29 ) and the coverage-type adsorption coefficient b (as shown in Figure 30 and 31 ) of the acetone adsorption amount prediction equation were obtained, which changed regularly with the pore size D, the relative partial pressure P C / P0and the adsorption temperature T. In the calculation of the adsorption coefficient b, it was found through analysis Figure 30 that the adsorption temperature had a smaller influence on the slope k b of b. Therefore, for the purpose of simplifying the calculation, the numerical value of the slope k b of b in the adsorption isotherm of each model adsorption material at 25°C was taken as the average value. The equations of the filling-type adsorption coefficient a and the coverage-type adsorption coefficient b were obtained as follows:

[0272] a=0.5+0.057xD AV +0.12xP / P0-0.00115xT;

[0273] b=(0.00185-0.000266xD AS ) x P / P0+(0.000176+0.00000857xD AS )-6.5x10 -7 xT;

[0274] Thus, the adsorption amount / isotherm prediction equation across the adsorption temperature was derived, and the equation applicable to the prediction of the acetone adsorption amount / isotherm at different temperatures was obtained as follows:

[0275] Q=(0.5+0.057xD AV+0.12xP / P0-0.00115xT) x V C +((0.00185-0.000266xD AS ) x P / P0+ (0.000176+0.00000857xD AS )-6.5x10 -7 x T) x S C Equation 4.2.

[0276] Wherein, Q, V C , S C , D AV , D AS , T, P / P0 represent the same meaning as Equation 4.

[0277] Based on the obtained acetone adsorption amount prediction equation (Equation 4.2) across the adsorption temperature, the trend of the adsorption amount changing with the relative pressure at different adsorption temperatures can be solved by substituting the adsorption temperature T, the relative pressure P / P0 and the corresponding pore structure parameters (D AV , D AS , V C , S C ) of the adsorption isotherm into the adsorption amount prediction equation (Equation 4.2), and the predicted adsorption isotherm at the corresponding adsorption temperature can be obtained by multiplying the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 (120.1 mbar, 195.73 mbar, 306.73 mbar, 464.28 mbar, 681.42 mbar) at the corresponding temperature (5℃, 15℃, 25℃, 35℃, 45℃), as shown in Figure 32 , the VOCs adsorption amount at different temperatures and the isotherm can be predicted by the same equation. Figure 32 For the predicted and measured adsorption isotherms at different adsorption temperatures, it can be seen from Figure 32 that the prediction method provided by the present application can well coincide with the adsorption isotherms obtained by experimental test. It can be found that the method of the present application is also applicable to the derivation and prediction of the adsorption amount and adsorption isotherm prediction equation of other VOCs (such as acetone) at different adsorption temperatures.

[0278] Overall, by comparing with the benzene adsorption amount prediction equation in Example 1, it can be found that the VOCs adsorption amount prediction equation Q=a x V C +b x S CThe basic structure remains unchanged; the adsorption of VOCs by porous materials includes both packed adsorption and covered adsorption. By introducing adsorption temperature T, relative pressure P / P0, and pore size D as variables, the influence of differences in adsorption temperature is effectively overcome, and the same equation is used to predict the adsorption temperature across adsorption. Since different VOCs have different saturated vapor pressure, molecular weight, molecular size, boiling point, polarity, etc., the coefficients (a and b) corresponding to packed adsorption and covered adsorption will also differ. However, overall, based on the adsorption isotherm of the model adsorbent material for a specific VOC and the pore structure parameters of the model adsorbent material, the adsorption amount prediction equation across adsorption temperature for that specific VOC can be derived using the method of this invention. This indicates that the VOC adsorption amount / adsorption isotherm prediction method across adsorption temperature developed in this invention has good generalizability.

[0279] Example 4

[0280] To further verify that the obtained adsorption capacity prediction equation can be applied to predict the adsorption capacity and adsorption isotherm of other conventional adsorbent materials for specific VOCs, this embodiment uses two porous silica materials without concentrated pore size distribution (such as...) Figure 33 The figure shown is an adsorbent material. The acetone adsorption capacity prediction equation across the adsorption temperature obtained in Example 3 is used to verify the applicability of the equation to other adsorbent materials with non-concentrated pore size distribution.

[0281] The pore structure parameters of the adsorbent material were tested using a commercially available surface area and pore structure analyzer. The pore structure parameters were obtained using a DFT cylindrical pore calculation model. The critical pore size D required for packed adsorption in Example 3 was then used. C With critical relative pressure P C The ternary matching equation (Equation 3.2) between / P0 and adsorption temperature T, combined with the obtained pore structure parameters of the adsorbent material, and based on the relationship between cumulative pore volume and cumulative specific surface area and pore size, yields the critical pore size D under the corresponding adsorption conditions (adsorption temperature T, relative pressure P / P0). C The corresponding critical pore volume V C Critical specific surface area S C Parameters such as these.

[0282] In Example 3, the critical pore size D of the packed adsorption system C With critical relative pressure P C The ternary matching equation between / P0 and adsorption temperature T is:

[0283] D C =(P C / P0-0.000253×T+0.227) / (0.00041×T+0.118), Equation 3.2;

[0284] and the critical pore diameter D C corresponding to the adsorption condition C , the critical specific surface area S C and other parameters as known quantities into the acetone cross-temperature adsorption amount prediction equation (equation 4.2), the trend of the adsorption amount with the relative pressure at the corresponding adsorption temperature is solved, as shown in Figure 34

[0285] In Example 3, the acetone cross-temperature adsorption amount prediction equation is:

[0286] Q = (0.5 + 0.057 x D AV + 0.12 x P / P0- 0.00115 x T) x V C + ((0.00185-0.000266 x D AS ) x P / P0+ (0.000176 + 0.00000857 x D AS )- 6.5 x 10 -7 x T) x S C Equation 4.2

[0287] The normalized adsorption isotherm of acetone at 35℃ on the two porous silica adsorption materials is calculated by multiplying the predicted relative pressure P / P0 of the adsorption isotherm by the saturated vapor pressure P0 (464.28 mbar) of acetone at the corresponding temperature (35℃), i.e. the predicted adsorption isotherm, as shown in Figure 35 Figure 35 The predicted adsorption isotherm of the two porous silica adsorption materials without concentrated pore size distribution is compared with the measured adsorption isotherm. As can be seen from Figure 35 , the acetone adsorption isotherm at 35℃ obtained by the prediction method provided by the present application can well coincide with the adsorption isotherm obtained by experimental testing.

[0288] The above description shows that the method of the present application is also applicable to the prediction of the adsorption amount and adsorption isotherm of other adsorption materials without concentrated pore size distribution at different adsorption temperatures for specific VOCs. The acetone adsorption amount prediction equation obtained by the silica-based adsorption material in Example 3 can be directly used for the prediction of the adsorption amount of other silica-based adsorption materials without concentrated pore size distribution. Therefore, in the case of similar composition and surface properties of the materials, the obtained adsorption amount prediction equation can be directly used for the prediction of the adsorption amount and adsorption isotherm of other adsorption materials at different adsorption temperatures. It shows that the VOCs adsorption amount and adsorption isotherm prediction method of the present application has good generalizability.

[0289] ​​In summary, based on the adsorption of VOCs by porous materials including filling adsorption and covering adsorption, the regularity equation of critical pore diameter under different adsorption conditions (temperature, relative pressure) that can occur filling adsorption is obtained. C And the specific surface area S C of the pores that occur covering adsorption contributes to the VOCs adsorption capacity, and the basic structure of the adsorption capacity prediction equation Q=a x V C +b x S C is obtained. By introducing the coefficients of filling adsorption and covering adsorption as variables of pore diameter D, relative pressure P / P0 and adsorption temperature T, the VOCs adsorption capacity prediction equation across adsorption temperature is obtained. This equation can be used to predict the VOCs adsorption capacity and isotherm of the adsorbent with the same or similar surface properties at different adsorption temperatures. Based on the obtained VOCs adsorption capacity prediction equation across adsorption temperature, the critical pore diameter D C , the critical pore volume V C and the critical specific surface area S C corresponding to the adsorption conditions (adsorption temperature T, relative pressure P / P0) can be obtained by the pore structure parameters of the adsorbent, and the equation can be solved by substituting the known numbers into the equation to obtain the trend of the adsorption capacity with the change of relative pressure at different adsorption temperatures. The predicted adsorption isotherm multiplied by the saturated vapor pressure P0 at the corresponding temperature can obtain the predicted adsorption isotherm before normalization at the corresponding adsorption temperature. The VOCs adsorption capacity and isotherm prediction method of the present application can predict the VOCs adsorption capacity and isotherm at different temperatures by the same equation, and has good generalizability and important reference significance for the optimization of adsorbent and technology.

[0290] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, several improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for predicting adsorption capacity of volatile organic compounds across adsorption temperature, characterized in that, The method comprises the following steps: (1) providing two or more porous materials with concentrated pore size distribution as model adsorbents, testing the pore structure parameters of the model adsorbents, wherein the pore structure parameters include pore size distribution, cumulative pore volume versus pore size distribution, total pore volume V, cumulative specific surface area versus pore size distribution, and total specific surface area S; (2) testing the adsorption isotherms of a model adsorbent for specific VOCs at multiple adsorption temperatures, and obtaining the static adsorption isotherms after pressure normalization by dividing each pressure point on the static adsorption isotherm by the saturated vapor pressure P0 at the corresponding temperature; According to the static adsorption isotherm after the pressure normalization, a relative pressure interval corresponding to the filling adsorption of the model adsorption material is obtained, and a middle value of the relative pressure interval is taken as a relative critical pressure P C / P0; the critical relative pressure P C / P0 corresponds to a middle value of the pore size distribution of the model adsorption material, and the middle value of the pore size distribution is taken as the critical relative pressure P C / P0; and a critical pore size D C under which the filling adsorption can occur The critical relative pressure P of the adsorbent material in this model C Linear fitting of / P0 with adsorption temperature T yields the critical relative pressure P at a specific pore size. C The linear relationship between P0 and adsorption temperature is expressed as follows: P C / P0=k P ×T+d P , Equation 1; wherein P C P0 is the critical pressure P C critical relative pressure with respect to the saturation vapor pressure P0 at the corresponding adsorption temperature; T is the adsorption temperature, ℃; k P is the slope of the linear relationship between relative pressure and adsorption temperature; d P For linear relationship, the value of P C / P0 as the relative pressure approaches 0. According to the model, different P C values of / P0, the coefficient k in equation 1 corresponding to the adsorption material is solved P and d P ; (3) Refer to the method of step (2), obtain the coefficient k in equation 1 corresponding to other model adsorbent materials P and d P ; (4) a plurality of critical pore diameters D C Next, the critical relative pressure P C The k P and d P of the linear relationship equation between P C / P0 and the adsorption temperature T were determined, respectively, and the linear relationship equation between k P and d P and the critical pore diameter D C was determined, respectively, to obtain the linear relationship equation k P =k P1 ×D C +k P0 and d P =d P1 ×D C +d P0 , and thus the linear relationship equation of the filled adsorption critical relative pressure P C / P0 with the adsorption temperature T and the pore size D C was obtained: P C / P0=(k P1 ×D C +k P0 )×T+(d P1 ×D C +d P0 ), Equation 2; wherein P C P0 is the critical pressure P C critical relative pressure with respect to the saturation vapor pressure P0 at the corresponding adsorption temperature; T is the adsorption temperature, ℃; D C For a relative pressure of P C Critical pore size, nm, at which filling adsorption can occur for a relative pressure of P k P1 and k P0 respectively are the slope and intercept of the linear relationship equation as a function of the critical aperture D P D C the slope and intercept of the linear relationship equation as a function of the critical aperture D d P1 and d P0 respectively are d P The slope and intercept of the linear relationship equation as the critical aperture D C varies; Using equation 2, the critical pore size D C at which the critical pore size D C Equation of matching relationship between the adsorption temperature T D C = (P C / P0-k P0 ×T-d P0 ) / (k P1 ×T+d P1 ), Equation 3; where D C , P C / P0, T, k P1 , k P0 , d P1 and d P0 have the same meaning as in equation 2; (5) the critical pore size D C as the demarcation point, the cumulative pore volume according to the pore structure parameter test changes with the pore size distribution, the cumulative specific surface area changes with the pore size distribution, respectively, to obtain the model adsorbent material in the critical pore size D C The pore volume V C of the following pores C The specific surface area S C of the above pores (6) the pore volume V of the pores in which filling adsorption occurs C and the specific surface area S of the pores in which overlying adsorption occurs C The contribution of VOCs adsorption capacity, and the different model adsorption material pore size, relative pressure and adsorption temperature as the parameter into the adsorption capacity prediction equation, get can be extended to different adsorption temperature T under the adsorption isotherm prediction of cross adsorption temperature of VOCs adsorption capacity prediction equation: Q = a x V C + b x S C = f(D AV , P / P0, T) x V C + g(D AS , P / P0, T) x S C Equation 4; wherein Q is the adsorption amount of VOCs per unit mass of adsorbent, g / g; V C The pore volume of pores below the critical pore size, i.e. the critical pore volume, cm3 / g 3 / g; S C The specific surface area of the pores above the critical pore size, i.e. the critical specific surface area, m 2 / g; D AV The average pore size of the channels where packed adsorption occurred is in nm; where D AV =4V C / (SS C S is the total specific surface area, m 2 / g; D AS The average pore size of the channels where covering adsorption occurred is in nm; where D AS =4(VV) C ) / S C V is the total pore volume, in cm. 3 / g; T is the adsorption temperature, ℃; P / P0 is any relative pressure point on the adsorption isotherm after normalization relative to the saturated vapor pressure at the corresponding temperature; P0 is the saturated vapor pressure of VOCs at the corresponding adsorption temperature T, mbar; a is the coefficient of packed adsorption, i.e. the amount of VOCs adsorbed per unit pore volume, g / cm 3 where a = f(D AV , P / P0, T) indicates that the coefficient a is a function of the pore diameter D AV , the relative pressure P / P0and the adsorption temperature T; b is the coefficient of the coverage of the adsorption, i.e. the amount of VOCs adsorbed per unit of specific surface, g / m2 2 where b = g(D AS , P / P0, T) indicates that the coefficient b is a function of the pore diameter D AS , the relative pressure P / P0and the adsorption temperature T; (7) Through the pore structure of multiple model adsorbents and the adsorption isotherm test under different adsorption conditions, the critical pore size D C , adsorption capacity Q, critical pore volume V C , critical specific surface area S C , average pore size D AV and D AS , the pore structure parameters of the model adsorbent and the adsorption isotherm of the specific VOC under different adsorption conditions are taken as known numbers, and substituted into equation 4 to obtain the specific values of a and b, and the volatile organic compound adsorption capacity prediction equation across the adsorption temperature is obtained.

2. The method of claim 1, wherein, The model adsorbents are one or more of ordered mesoporous silica, ordered mesoporous carbon, and molecular sieves with concentrated pore size distribution.

3. The method of claim 1, wherein, The VOCs are one of hydrocarbon organic compounds, oxygen-containing organic compounds, halogen-containing organic compounds, nitrogen-containing organic compounds, and sulfur-containing organic compounds.

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