Method for predicting adsorption quantity of volatile organic compounds across adsorption temperatures

Abstract

The invention provides a cross-adsorption-temperature volatile organic compound adsorption quantity prediction method, and belongs to the technical field of waste gas treatment. According to the method, two or more porous materials with concentrated pore diameters are selected as model adsorption materials, the pore structures of the model adsorption materials and the adsorption isotherm of the model adsorption materials to VOCs are tested, and on the basis that the pressure of the adsorption isotherm is normalized relative to the saturated vapor pressure at the corresponding adsorption temperature, the adsorption isotherm of the model adsorption materials is obtained; and a ternary matching relation equation among the filling type adsorption critical aperture, the relative pressure and the adsorption temperature is obtained. According to the method, on the basis of contribution of filling type adsorption and covering type adsorption to the adsorption capacity, the aperture, the relative pressure and the adsorption temperature serve as variables, coefficients of filling type adsorption and covering type adsorption are introduced, equation coefficients are solved in combination with test data of a model adsorption material, and a VOCs adsorption capacity prediction equation crossing the adsorption temperature is constructed. The equation can be used for predicting the VOCs adsorption quantity and isotherm of an adsorbent with similar surface properties at different adsorption temperatures.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and in particular to a method for predicting the adsorption amount of volatile organic compounds across adsorption temperatures. Background Art

[0002] Volatile organic compounds, also known as Volatile Organic Compounds, or VOCs for short, 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 has become one of the most widely used methods due to its advantages such as flexible operation, high purification efficiency, wide application range, promotion of recycling, and reduction of carbon emissions. At present, the refinement, scientificization and efficient recovery of VOCs control are key research points. The fine control of VOCs, the increase in adsorption capacity, and the optimization of adsorption materials and processes all require the structure-activity relationship between the physical properties of the adsorbate and the structural properties of the adsorbent. The development of adsorption materials and technologies relies heavily on the guidance of adsorption mechanisms.

[0003] The prediction of adsorption capacity is based on the precise matching relationship between the pore structure parameters of the material and the VOCs adsorption capacity and the realization of equations. It has important reference significance for the optimization of adsorption materials and technologies. For example, in industrial waste gas treatment, accurate prediction of adsorption capacity helps to rationally select adsorption materials, reduce treatment costs, and improve purification efficiency. In terms of adsorption theoretical models and equations, equations and models such as Langmuir, Dubinin-Radushkevich, and Dubinin-Astakhov can be used to fit and interpret the obtained adsorption isotherms. However, since these methods do not use the pore structure parameters of the adsorbent as variables, it is impossible to predict the VOCs adsorption capacity of unknown adsorbents. Although the neural network method introduces pore structure parameters as variables, it is a statistical result, and its accuracy is greatly affected by the quality of the data, and it often lacks a regular theoretical explanation. Therefore, it is urgent to accurately quantify the matching relationship between the structural properties of the adsorbent and the VOCs adsorption capacity from a new perspective.

[0004] Filling adsorption is a common phenomenon in gas adsorption by porous solid adsorbents. According to the Kelvin equation, due to the limitations of the pore walls in a confined space, the equilibrium vapor pressure on the concave liquid surface is less than the equilibrium vapor pressure on the flat liquid surface. Therefore, at pressures far below the saturated vapor pressure, condensate tends to form in nanopores. Under certain conditions, filling adsorption can occur in pores below a specific pore size, where the density of the adsorbate is close to 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 of VOCs.

[0005] Currently, patent publication number CN116593376A provides a method for predicting the adsorption amount of volatile organic compounds based on filling adsorption. The adsorption amount prediction equation is derived based on the contribution of filling adsorption and covering adsorption to the VOCs adsorption amount, respectively. This can predict the VOCs adsorption amount / isotherm at a specific adsorption temperature. However, because the adsorption temperature is not introduced as a variable in the prediction equation, the adsorption amount prediction equation obtained at a specific temperature can only be used to predict the adsorption amount at that target temperature. If the adsorption amount / isotherm at other temperatures is to be predicted, the adsorption amount prediction equation at the corresponding temperature needs to be re-derived, which increases the workload and, to a certain extent, limits the convenience and scalability of the adsorption amount / isotherm prediction method.

[0006] If there were a method for predicting VOC adsorption across adsorption temperatures—that is, a single adsorption prediction equation could be used to predict adsorption amounts and isotherms at different adsorption temperatures—it would significantly improve the convenience and scalability of VOC adsorption prediction equations. Adsorption prediction relies on a precise relationship between material pore structure parameters and VOC adsorption, enabling equationization. This approach can provide an important reference for the development and optimization of adsorption materials and technologies. Currently, there is a lack of a robust theoretical basis for predicting VOC adsorption across adsorption temperatures. Summary of the Invention

[0007] In light of this, the present invention aims to provide a method for predicting the adsorption amount of volatile organic compounds across adsorption temperatures. This method, using a single equation and based on the pore structure parameters of the adsorbent material, can predict the adsorption amount and adsorption isotherms of VOCs at different adsorption temperatures, i.e., across adsorption temperatures.

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

[0009] The present invention provides a method for predicting the adsorption amount of volatile organic compounds across adsorption temperatures, comprising the following steps:

[0010] (1) providing two or more porous materials with concentrated pore size distribution as model adsorption materials, and testing the pore structure parameters of the model adsorption materials, wherein the pore structure parameters include pore size distribution, cumulative pore volume change with pore size distribution, total pore volume V, cumulative specific surface area change with pore size distribution, and total specific surface area S;

[0011] (2) Testing the adsorption isotherms of a model adsorbent for specific VOCs at multiple adsorption temperatures, and obtaining the static adsorption isotherm after partial pressure normalization by dividing each pressure point on the static adsorption isotherm by the saturated vapor pressure P0 at the corresponding temperature;

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

[0013] The critical relative pressure P of the model adsorption material C / P0 is linearly fitted with the adsorption temperature T to obtain the critical relative pressure P under a specific pore size. C The linear relationship equation between / P0 and adsorption temperature:

[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, °C;

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

[0018] d P When the relative pressure approaches 0 in the linear relationship, P C / The value of P0;

[0019] According to the different P values corresponding to different adsorption temperatures T of the adsorption material in this model C / P0 value, solve the coefficient k in equation 1 corresponding to the adsorption material of this modelP and d P ;

[0020] (3) Referring to the method of step (2), the coefficient k in equation 1 corresponding to other model adsorption materials is obtained. P and d P ;

[0021] (4) Multiple critical apertures D C Under the critical relative pressure P C k of the linear relationship equation between / P0 and adsorption temperature T P and d P , relative to their respective critical apertures D C Do linear fitting and get the coefficient k P and d P With the critical aperture D C The linear relationship equation of change k P =k P1 ×D C +k P0 and d P =d P1 ×D C +d P0 , thus obtaining the filling adsorption critical relative pressure P C / P0 varies with adsorption temperature T and pore size D C The linear relationship equation of change:

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

[0023] 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;

[0024] T is the adsorption temperature, °C;

[0025] D C The relative pressure is P C / P0, the critical pore size for filling adsorption to occur, nm;

[0026] k P1 and k P0 k P With the critical aperture D C the slope and intercept of a changing linear relationship equation;

[0027] d P1 and d P0 d P With the critical aperture D C the slope and intercept of a changing linear relationship equation;

[0028] Using Equation 2, we can get different relative pressures P C / P0, the critical pore size D for filling adsorption to occur C The matching relationship equation between the adsorption temperature T is:

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

[0030] 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;

[0031] (5) With the critical pore size D C As the dividing point, according to the change of cumulative pore volume with pore size distribution and cumulative specific surface area with pore size distribution tested by pore structure parameters, the critical pore size D of the model adsorption material is obtained. C The pore volume V of the following pores C and critical pore size D C The specific surface area S of the pores above C ;

[0032] (6) Based on the pore volume V of the pores where filling adsorption occurs C and the specific surface area S of the pores where covering adsorption occurs C The contribution of different model adsorption materials to the VOCs adsorption amount is analyzed, and the pore size, relative pressure and adsorption temperature of the adsorption materials are introduced as parameters into the adsorption amount prediction equation to obtain the VOCs adsorption amount prediction equation across adsorption temperatures that can be extended to the adsorption isotherm prediction 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 capacity of VOCs per unit mass of adsorption material, g / g;

[0035] V C is the pore volume 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 size of the pores where filling adsorption occurs, nm; where D AV =4V C / (SS C ), S is the total specific surface area, m 2 / g;

[0038] D AS is the average pore size of the pores where covering adsorption occurs, nm; where D AS =4(VV 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 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, that is, the adsorption amount of VOCs per unit pore volume, g / cm 3 , where a=f(D AV ,P / P0,T) indicates that the coefficient a is the aperture D AV , function of relative pressure P / P0 and adsorption temperature T;

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

[0043] (7) By testing the pore structure of multiple model adsorption materials and the adsorption isotherms under different adsorption conditions, the critical pore size D under the corresponding conditions is obtained. C , adsorption capacity Q, critical pore volume V C, critical specific surface area S C , average pore diameter D AV and D AS , the pore structure parameters of the model adsorption material and the adsorption isotherms of specific VOCs under different adsorption conditions are substituted into Equation 4 to obtain the specific values of a and b, and the prediction equation for the adsorption amount of volatile organic compounds across the adsorption temperature is obtained.

[0044] Preferably, the model adsorption material is one or more of ordered mesoporous silicon, 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 invention provides a method for predicting the adsorption amount of volatile organic compounds across adsorption temperatures. The present invention uses two or more model adsorption materials with concentrated pore size distributions and adopts a control variable method. On the basis of normalizing the pressure of the adsorption isotherm relative to the saturated vapor pressure at the corresponding adsorption temperature, a regular equation for the critical pore size at which specific VOCs can undergo filling-type adsorption under different adsorption conditions (temperature, relative pressure) is obtained. C The pores in the pores are filled with adsorption with high pore volume utilization. The filled adsorption follows the filling adsorption mechanism of the adsorption space. The adsorption amount of VOCs in this part of the pores is directly related to the pore volume. C The pores that occur are single-layer or multi-layer adsorption surface covering adsorption mechanisms, and the adsorption amount of VOCs by this part of the pores is directly related to the specific surface area. On this basis, adsorption amount prediction equations are proposed according to the pore volume where filling adsorption occurs and the specific surface area of the pores where covering adsorption occurs. Since the adsorption mechanisms of the two parts are different, their contributions to the adsorption amount of VOCs and the calculation methods are also different. The present invention introduces the coefficients of filling adsorption and covering adsorption by taking the pore size D, relative pressure P / P0 and adsorption temperature T as variables, and uses 2 or more model material pore structure parameters and their adsorption isotherms for VOCs as known data to solve the equation coefficients, thereby obtaining a VOCs adsorption amount prediction equation across adsorption temperatures. This equation can be used for adsorbents with the same or similar surface properties to predict the adsorption amount and isotherms of VOCs at different adsorption temperatures.

[0047] The method for predicting the adsorption amount of volatile organic compounds across adsorption temperatures provided by the present invention 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 isotherm obtained by the prediction method of the present invention has a high degree of consistency with the measured adsorption isotherm, and is also applicable to other adsorption materials that do not have a concentrated pore size distribution. The prediction of the adsorption amount and adsorption isotherm of specific VOCs at different adsorption temperatures has good accuracy and scalability. The prediction method provided by the present invention is simple to calculate, has a clear physical meaning, high accuracy, and a wide range of applications. It provides a reference basis for the selection of adsorption materials suitable for different VOCs, and provides theoretical support for the design of efficient VOCs adsorption materials, the study of adsorption and desorption processes, and the optimization of VOCs adsorption processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the method for predicting the adsorption amount of volatile organic compounds across adsorption temperatures;

[0049] Figure 2 is the pore size distribution of the model adsorbent material in Example 1;

[0050] Figure 3 The cumulative pore volume of the model adsorption material in Example 1 varies with pore diameter;

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

[0052] Figure 5 is the static adsorption isotherm of benzene of the model adsorbent material in Example 1 at multiple adsorption temperatures;

[0053] Figure 6 is the normalized static adsorption isotherm of benzene obtained relative to the saturated vapor pressure P0 at each adsorption temperature in Example 1;

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

[0055] Figure 8 The coefficient k of equation 1 during the adsorption of benzene at different temperatures in Example 1 is P and d P With the critical aperture size D C Linear relationship equation of change;

[0056] Figure 9 The pore volume of pores within a specific pore size range obtained by accumulating pore volumes in Example 1;

[0057] Figure 10 The specific surface area of pores within a specific pore size range is obtained by accumulating the specific surface areas in Example 1;

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

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

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

[0061] Figure 14 The influence of adsorption temperature T on the blanket adsorption coefficient (b) in MCM-41-3.0 in Example 1 is shown;

[0062] Figure 15 The influence of adsorption temperature T on the blanket adsorption coefficient (b) in MCM-41-4.0 in Example 1 is shown;

[0063] Figure 16 The influence of adsorption temperature T on the blanket adsorption coefficient (b) in MCM-41-4.5 in Example 1 is shown;

[0064] Figure 17 is the slope k in Example 1 b The trend of change with pore size at 5°C and 45°C;

[0065] Figure 18 is the slope k in Example 1 b The law of how the coefficients of the equation change with temperature and pore size;

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

[0067] Figure 20 Comparison of the predicted and measured adsorption isotherms of the MCM-41 adsorption material at five different adsorption temperatures obtained in Example 1 by multiplying the relative pressure P / P0 in the isotherm by the saturated vapor pressure P0 at the corresponding temperature;

[0068] Figure 21 is the pore size distribution of the porous silicon oxide material without concentrated pore size distribution in Example 2;

[0069] Figure 22Comparison of the predicted and measured trends of the adsorption amount Q as a function of the relative pressure P / P0 at an adsorption temperature of 25°C for the porous silicon oxide material without concentrated pore size distribution in Example 2;

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

[0071] Figure 24 is the static adsorption isotherm of acetone of the model adsorption material in Example 3 at 5°C, 15°C, 25°C, 35°C, and 45°C;

[0072] Figure 25 is the static adsorption isotherm of acetone normalized to the saturated vapor pressure at each temperature in Example 3;

[0073] Figure 26 is the critical relative pressure (P C The linear relationship equation between / P0) and adsorption temperature (T);

[0074] Figure 27 The coefficient k in equation 1 is the adsorption process of acetone at different adsorption temperatures in Example 3. P and d P With the critical aperture D C Linear relationship equation of change;

[0075] Figure 28 The trend curve of the filling adsorption coefficient (a) of the model adsorbent materials with different pore sizes as a function of pressure in Example 3 is shown;

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

[0077] Figure 30 The influence of the pore size and adsorption temperature T on the covering adsorption coefficient (b) in the model adsorption materials with different pore sizes in Example 3;

[0078] Figure 31 is the slope k in Example 3 b The law of how the coefficients of the equation change with temperature and pore size;

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

[0080] Figure 33 The pore size distribution of the two porous silicon oxide materials without concentrated pore size distribution in Example 4;

[0081] Figure 34 Comparison of the trends of the predicted and measured adsorption amounts Q as a function of relative pressure P / P0 for acetone adsorption at 35°C for the two porous silica materials without concentrated pore size distribution in Example 4;

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

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

[0084] (1) providing two or more porous materials with concentrated pore size distribution as model adsorption materials, and testing the pore structure parameters of the model adsorption materials, wherein the pore structure parameters include pore size distribution, cumulative pore volume change with pore size distribution, total pore volume V, cumulative specific surface area change with pore size distribution, and total specific surface area S;

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

[0086] The relative pressure range corresponding to the filling adsorption of the model adsorption material is obtained according to the static adsorption isotherm after the partial pressure normalization, 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 median value of the pore size distribution of the model adsorbent, and the median value of the pore size distribution is taken as the critical relative pressure P C / The critical pore size D for filling adsorption at P0 C ;

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

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

[0089] Among them, P C / P0 is the critical pressure P CThe critical relative pressure relative to the saturated vapor pressure P0 at the corresponding adsorption temperature;

[0090] T is the adsorption temperature, °C;

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

[0092] d P When the relative pressure approaches 0 in the linear relationship, P C / The value of P0;

[0093] According to the different P values corresponding to different adsorption temperatures T of the adsorption material in this model C / P0 value, solve the coefficient k in equation 1 corresponding to the adsorption material of this model P and d P ;

[0094] (3) Referring to the method of step (2), the coefficient k in equation 1 corresponding to other model adsorption materials is obtained. P and d P ;

[0095] (4) Multiple critical apertures D C Under the critical relative pressure P C k of the linear relationship equation between / P0 and adsorption temperature T P and d P , relative to their respective critical apertures D C Do linear fitting and get the coefficient k P and d P With the critical aperture D C The linear relationship equation of change k P =k P1 ×D C +k P0 and d P =d P1 ×D C +d P0 , thus obtaining the filling adsorption critical relative pressure P C / P0 varies with adsorption temperature T and pore size D C The linear relationship equation of change:

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

[0097] Among them, 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, °C;

[0099] D C The relative pressure is P C / P0, the critical pore size for filling adsorption to occur, nm;

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

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

[0102] Using Equation 2, we can get different relative pressures P C / P0, the critical pore size D for filling adsorption to occur C The matching relationship equation between the adsorption temperature T is:

[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) With the critical pore size D C As the dividing point, according to the change of cumulative pore volume with pore size distribution and cumulative specific surface area with pore size distribution tested by pore structure parameters, the critical pore size D of the model adsorption material is obtained. C The pore volume V of the following pores C and critical pore size D C The specific surface area S of the pores above C ;

[0106] (6) Based on the pore volume V of the pores where filling adsorption occurs Cand the specific surface area S of the pores where covering adsorption occurs C The contribution of different model adsorption materials to the VOCs adsorption amount is analyzed, and the pore size, relative pressure and adsorption temperature of the adsorption materials are introduced as parameters into the adsorption amount prediction equation to obtain the VOCs adsorption amount prediction equation across adsorption temperatures that can be extended to the adsorption isotherm prediction at different adsorption temperatures T:

[0107] 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;

[0108] In equation 4,

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

[0110] V C is the pore volume below the critical pore size, i.e., the critical pore volume, cm 3 / g;

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

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

[0113] D AS is the average pore size of the pores where covering adsorption occurs, nm; where D AS =4(VV C ) / S C , V is the total pore volume, cm 3 / g;

[0114] T is the adsorption temperature, °C;

[0115] P / P0 is any relative pressure point on the adsorption isotherm normalized 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 , where a=f(D AV,P / P0,T) indicates that the coefficient a is the aperture D AV , function of relative pressure P / P0 and adsorption temperature T;

[0117] b is the coefficient of covering adsorption, that is, the adsorption amount of VOCs per unit specific surface area, g / m 2 , where b = g(D AS ,P / P0,T) indicates that the coefficient b is the aperture D AS , function of relative pressure P / P0 and adsorption temperature T;

[0118] (7) By testing the pore structure of multiple model adsorption materials and the adsorption isotherms under different adsorption conditions, the critical pore size D under the corresponding conditions is obtained. C , adsorption capacity Q, critical pore volume V C , critical specific surface area S C , average pore diameter D AV and D AS , the pore structure parameters of the model adsorption material and the adsorption isotherms of specific VOCs under different adsorption conditions are substituted into Equation 4 to obtain the specific values of a and b, and the prediction equation for the adsorption amount of volatile organic compounds across the adsorption temperature is obtained.

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

[0120] The present invention preferably uses a commercial specific surface area and pore structure analyzer to test the pore structure parameters of the adsorption material, and obtains the pore structure parameters of the adsorption material through the DFT cylindrical pore calculation model.

[0121] The present invention tests the adsorption isotherms of a model adsorption material for 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, a static adsorption isotherm after partial pressure normalization is obtained. According to the static adsorption isotherm after partial pressure normalization, the relative pressure range corresponding to the filling adsorption of the model adsorption material is obtained, 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 model adsorption material C / P0 is linearly fitted with the adsorption temperature T to obtain the critical relative pressure P under a specific pore size. C The linear relationship equation between / P0 and adsorption temperature. For the model adsorbent material with concentrated pore size distribution, its adsorption isotherm shows the typical VI type adsorption isotherm characteristics. When filling adsorption occurs, the adsorption amount will increase rapidly within a specific pressure range. This change can intuitively reflect the critical pressure value P corresponding to the filling adsorption of the model adsorbent material with a specific pore size from the adsorption isotherm. C .

[0122] 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, as the adsorption temperature increases, the relative pressure required for filling adsorption increases, and the critical relative pressure P C There is a correlation between / P0 and the corresponding adsorption temperature T. Under the condition of the same adsorption temperature, the larger the pore size of the model adsorbent material, the greater the relative pressure required for the corresponding filling adsorption. 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, the critical relative pressure (P C The linear relationship equation between adsorption temperature (T) and adsorption temperature (P0) is:

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

[0124] According to the different P values corresponding to different adsorption temperatures T of the adsorption material in this model C / P0 value, solve the coefficient k in equation 1 corresponding to the adsorption material of this model P and d P ; Further, the coefficient k in equation 1 corresponding to other model adsorption materials is obtained P and d P .

[0125] The present invention uses multiple critical apertures D C Under the critical relative pressure P C k of the linear relationship equation between / P0 and adsorption temperature T P and d P , relative to their respective critical apertures D C Do linear fitting and get the coefficient k P and d PWith the critical aperture D C The linear relationship equation of change k P =k P1 ×D C +k P0 and d P =d P1 ×D C +d P0 , thus obtaining the filling adsorption critical relative pressure P C / P0 varies with adsorption temperature T and pore size D C The linear relationship equation of change:

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

[0127] This equation can be used to solve the critical relative pressure P at which filling adsorption can occur at different adsorption temperatures T. C / P0 and critical aperture size D C The matching relationship between them.

[0128] Furthermore, the present invention uses equation 2 to obtain different critical relative pressures P C / P0, the critical pore size D for filling adsorption to occur C The matching relationship equation between the adsorption temperature T is:

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

[0130] The present invention uses equation 3 to solve the critical and critical pore sizes D for filling adsorption at different adsorption temperatures T and relative pressures P / P0. C ; With the critical pore size D C As the dividing point, according to the results of the pore structure test, the pore volume V of the model adsorption material below any critical pore size can be obtained. C and the specific surface area S of pores above the critical pore size C Equation 3 can be used to solve the critical relative pressure P at which filling adsorption can occur at the corresponding adsorption temperature T. C / P0 and critical aperture size D CThe matching relationship between them is used to obtain the critical pore size D corresponding to different relative pressures. C Combining the pore structure parameters, different critical pore sizes D can be obtained. C The corresponding critical pore volume V C and critical specific surface area S C . Smaller than the critical pore size D C The pores in the pores are filled with adsorption with high pore volume utilization. Filling adsorption follows the filling mechanism of adsorption space. The adsorption amount of VOCs in this part of the pores is directly related to the pore volume. C The pores in the upper and lower layers of the membrane are covered by a single or multilayer adsorption mechanism. The amount of VOCs adsorbed by these pores is directly related to the specific surface area. The adsorption mechanisms of the two parts are different, so their contributions to VOC adsorption and the calculation methods are also different.

[0131] The present invention is based on the pore volume V of the pores where filling adsorption occurs. C and the specific surface area S of the pores where covering adsorption occurs C The contribution of different model adsorption materials to the VOCs adsorption amount is analyzed, and the pore size, relative pressure and adsorption temperature of the adsorption materials are introduced as parameters into the adsorption amount prediction equation to obtain the VOCs adsorption amount prediction equation across adsorption temperatures that can be extended to the adsorption isotherm prediction at different adsorption temperatures T:

[0132] 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.

[0133] By testing the pore structure of multiple model adsorption materials and the adsorption isotherms under different adsorption conditions, the critical pore size D under the corresponding conditions was obtained. C , adsorption capacity Q, critical pore volume V C , critical specific surface area S C , average pore diameter D AV and D AS , the pore structure parameters of the model adsorption material and the adsorption isotherms of specific VOCs under different adsorption conditions are substituted into Equation 4 to obtain the specific values of a and b, and the prediction equation for the adsorption amount of volatile organic compounds across the adsorption temperature is obtained.

[0134] Based on the obtained prediction equation of the adsorption amount of volatile organic compounds across adsorption temperatures, the present invention can calculate the critical pore size D under the corresponding adsorption conditions (adsorption temperature T, relative pressure P / P0) through the pore structure parameters of the model adsorption material. C The corresponding critical pore volume VC , critical specific surface area S C Substitute the known numbers into the equation to solve the trend of adsorption amount changing with relative pressure at different adsorption temperatures. 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; the same equation can be used to predict the VOCs adsorption amount and isotherm at different temperatures.

[0135] In the present invention, the schematic diagram of the method for predicting the adsorption amount of volatile organic compounds across the adsorption temperature is as follows: Figure 1 shown. Figure 1 In the pores with different pore sizes, under specific adsorption conditions (specific VOCs type, temperature, pressure), the pore size is smaller than the critical pore size (D C ) pores undergo filling adsorption, while pores larger than the critical pore size (D C The pores with the size smaller than the critical pore size (D C The pore volume of all pores (V C =V1+V2+...V n ) and larger than the critical pore size (D C The specific surface area of all pores (S C =S1+S2+...+S n By taking pore size D, relative pressure P / P0 and adsorption temperature T as variables and introducing the coefficients of filling adsorption and covering adsorption, a prediction equation for VOCs adsorption across adsorption temperatures is obtained. This equation can be used to predict the VOCs adsorption amount and isotherms of adsorbents with the same or similar surface properties at different adsorption temperatures.

[0136] Based on the obtained prediction equation of the adsorption amount of volatile organic compounds across adsorption temperatures, the critical pore size D under the corresponding adsorption conditions (adsorption temperature T, relative pressure P / P0) can be calculated through the pore structure parameters of the model adsorption material. C The corresponding critical pore volume V C , critical specific surface area S C Substitute the known numbers into the equation to solve the trend of adsorption amount changing with relative pressure at different adsorption temperatures. 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; the same equation can be used to predict the VOCs adsorption amount and isotherm at different temperatures.

[0137] The method for predicting the amount of volatile organic compound adsorption across adsorption temperatures provided by the present invention is described in detail below with reference to the following examples. However, these examples should not be construed as limiting the scope of protection of the present invention.

[0138] Example 1

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

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

[0141] By dividing each pressure point on the adsorption isotherm by the saturated vapor pressure at the corresponding temperature, the static adsorption isotherm after partial pressure normalization is obtained, such as Figure 6 As shown. According to the Kelvin equation, the adsorption of gas molecules on porous materials will form filling adsorption in pores below a specific size. According to the normalized adsorption isotherm, the relative pressure range corresponding to the filling adsorption of each model adsorption material is obtained, and the middle value of the relative pressure range is taken as the critical relative pressure point (P C / P0), the critical relative pressure point corresponds to the middle value of the pore size distribution of the model adsorbent material, and the pore size is used as the relative pressure point P C The critical pore size (D C According to the normalized adsorption isotherms of three model adsorbent materials (pore sizes of 3.0 nm, 4.0 nm and 4.5 nm) at multiple temperatures (5, 15, 25, 35 and 45 °C), the midpoint of the rapid rise phase corresponding to the occurrence of filling adsorption (critical relative pressure P C / P0), as shown in Table 1.

[0142] Table 1 Relative pressure (P) at the middle point of the rapid rise phase 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, as the adsorption temperature increases, the relative pressure required for filling adsorption increases, and the critical relative pressure P C There is a correlation between / P0 and the corresponding adsorption temperature T. Under the condition of the same adsorption temperature, the larger the pore size of the model adsorbent material, the greater the relative pressure required for the corresponding filling adsorption. 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, the critical relative pressure (P C The linear relationship equation between adsorption temperature (T) and adsorption temperature (P0) is:

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

[0146] in,

[0147] 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;

[0148] T is the adsorption temperature, °C;

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

[0150] d P When the relative pressure approaches 0 in the linear relationship, P C / The value of P0;

[0151] Based on the adsorption isotherms at different adsorption temperatures in the same pore size, the midpoint of the rapid rise phase (critical relative pressure P) corresponding to the occurrence of filling adsorption at different adsorption temperatures was calculated. C / P0) corresponds to temperature T, and a linear fit is performed. It is found that the critical relative pressure of the adsorption isotherm at different temperatures in pores of the same size shows a good linear relationship with the adsorption temperature. CThe linear relationship equation between / P0) and adsorption temperature (T) is shown in the linear fitting results. Figure 7 As shown, the linear relationship equations are:

[0152] When 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] The critical relative pressure (P C By comparing the linear relationship equation between P / P0) and adsorption temperature (T), it can be found that the linear relationship equation P C / P0=k P ×T+d P The coefficient k P and d P There are certain differences among different pore sizes, as shown in Table 2.

[0156] Table 2 Critical relative pressure (P) for filling adsorption of benzene 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 <![CDATA[Coefficient k P > <![CDATA[Coefficient d P > 3.0nm 0.00116 0.072 4.0nm 0.00152 0.163 4.5nm 0.00158 0.213

[0158] According to the pore sizes of different 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 diameter D C Change, get the aperture D C Critical relative pressure (P C / P0); the critical relative pressure of filled adsorption (P C / P0) varies with adsorption temperature T and pore size D C The changing matching relationship 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, °C;

[0162] D C The relative pressure is P C / P0, the critical pore size for filling adsorption to occur, nm;

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

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

[0165] This equation can be used to solve the critical relative pressure P at which filling adsorption can occur at different adsorption temperatures T. C / P0 and critical aperture size D C The matching relationship between the three different pore sizes is obtained by dividing the critical relative pressure (P C The coefficient k in the linear relationship equation between / P0) and adsorption temperature (T) P and d P , linear fitting is performed with respect to the respective pore sizes (3.0nm, 4.0nm, 4.5nm), and the coefficient k is obtained 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, as Figure 8 As shown, the critical relative pressure of filling adsorption (P C / P0) varies with adsorption temperature T and pore size D C The changing matching relationship equation:

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

[0167] 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;

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

[0169] D C The relative pressure is P C / P0, the critical pore size for filling adsorption to occur, nm.

[0170] This equation can be used to solve the critical relative pressure P at which filling adsorption can occur at different adsorption temperatures T. C / P0 and critical aperture size D C The matching relationship between the two; and the different relative pressures P C / P0, the critical pore size D for filling adsorption to occur C The matching relationship between the adsorption temperature T.

[0171] Using Equation 2, we can get different relative pressures P C / P0, the critical pore size D for filling adsorption to occur C The matching relationship between the adsorption temperature T:

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

[0173] Among them, D C 、P C / P0, T, k P1 、k P0 d P1 and d P0 The meanings are the same as in Equation 2.

[0174] Equation 3 can be used to solve the critical pore size D for filling adsorption under different adsorption conditions (adsorption temperature T, relative pressure P / P0): C .

[0175] Using the obtained equation (Equation 2.1) combined with the method of Equation 3, the specific critical relative pressure P can be obtained C / P0, the critical pore size D for filling adsorption to occur C The matching relationship between the 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 used for different adsorption temperatures T and different critical relative pressures P C / P0 corresponds to the critical pore size D for filling adsorption C Calculation of the critical pore size D C As the dividing point, according to the results of the pore structure test, the critical pore size D of the model adsorption material is obtained. C The pore volume V of the following pores C , and the critical pore size D C The specific surface area S of the pores above C According to equation 3.1, combined with the pore structure parameters of the model adsorption material, any critical pore size D can be calculated. C The pore volume V of the pores below the critical pore size is C and the specific surface area S of pores above the critical pore size C Among them, the pore volume below a certain size can be obtained by cumulative 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, as Figure 10 shown.

[0178] According to the Kelvin equation, the adsorption of gas molecules on porous materials results in filling-type adsorption in pores below a certain size. Since filling-type adsorption follows a filling mechanism, the amount of adsorption is related to the density and volume of the pores where filling-type adsorption occurs. Pores where filling-type adsorption does not occur, however, exhibit a covering mechanism of monolayer or multilayer adsorption, and the amount of adsorption in these pores is related to the corresponding specific surface area.

[0179] Based on the pore volume V of the pores where filling adsorption occurs C and the specific surface area S of the pores where covering adsorption occurs C The contribution of different model adsorption materials to VOCs adsorption isotherms is studied. The pore size, relative pressure and adsorption temperature of different model adsorption materials are introduced as parameters into the adsorption amount prediction equation to obtain a VOCs adsorption amount prediction equation that can be extended to the adsorption isotherm prediction at different adsorption temperatures. C , specific surface area S C The prediction equation for the adsorption amount of volatile organic compounds across the adsorption temperature is satisfied, namely, Equation 4:

[0180] 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;

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

[0182] V C is the pore volume 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 size of the pores where filling adsorption occurs, nm; where D A =4V C / (SS C ), S is the total specific surface area, m 2 / g;

[0185] D AS is the average pore size of the pores where covering adsorption occurs, nm; where D AS =4(VV 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 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 filling adsorption, that is, the adsorption amount of VOCs per unit pore volume, g / cm 3 , where a=f(D AV ,P / P0,T) indicates that the coefficient a is the average pore diameter D AV , function of relative pressure P / P0 and adsorption temperature T;

[0190] b is the coefficient of covering adsorption, that is, the adsorption amount of VOCs per unit specific surface area, g / m 2 , where b = g(DAS ,P / P0,T) represents the coefficient b is the average pore diameter D AS , function of relative pressure P / P0 and adsorption temperature T.

[0191] The static adsorption of benzene on the series of model adsorption materials is a typical type IV adsorption isotherm, which can be roughly divided into three stages: in the initial stage of adsorption, as the pressure increases, the adsorption amount rapidly reaches a plateau and then slowly increases, which is attributed to the process of benzene molecules gradually forming a single layer or multilayer adsorption 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 in the concentrated pores; in the third stage of adsorption, the isotherm reaches the second plateau, and the adsorption amount increases slowly, which is mainly due to the rearrangement of the benzene molecules adsorbed in the pores in a filling manner, resulting in a slight increase in the adsorption amount.

[0192] Calculation method of filling adsorption coefficient (a):

[0193] By dividing the adsorption amount at each relative pressure point on the adsorption isotherm of the model adsorption material by the total pore volume, the trend of the filling adsorption coefficient (a = Q / V) changing with relative pressure can be obtained, as shown in the following example: Figure 11 In the volume filling adsorption coefficient (a), the part not affected by relative pressure and pore size is set to a0, and the part affected by pore size is set to a1=f(D AV ), the part affected by relative pressure is set to a2 = f(P / P0), the part affected by adsorption temperature is set to a3 = f(T), and a = a0 + a1 + a2 + a3. Therefore, the filling 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, the high-pressure region of the adsorption isotherm, the filling adsorption is basically completed. At the same time, with the increase of relative pressure, the coefficient (a) of filling adsorption also shows a slightly increasing trend. This is mainly attributed to the fact that the VOCs molecules in the filling adsorption can undergo molecular rearrangement with the increase of relative pressure, resulting in a slight increase in the coefficient (a) of filling adsorption, while the coefficient (a) of volume filling adsorption of different pore sizes increases at the same rate, that is, the slope (0.11). Therefore, the change in coefficient a caused by relative pressure is a2 = 0.11 × P / P0, as shown in Figure 11 shown.

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

[0196] In the high-pressure region of the third stage adsorption isotherm, the volume filling adsorption coefficient (a) corresponding to different adsorption temperatures in the same pore size also has certain differences, such as Figure 12 As shown in Figure 2, with the increase of adsorption temperature, the density of benzene adsorbed per unit pore volume will decrease, resulting in a regular change in coefficient a. The change in coefficient a caused by the adsorption temperature difference is a3 = -0.0013 × T, as shown in Figure 2. Figure 12 shown.

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

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

[0199] Among them, D AV is the average pore size of the pores where filling adsorption occurs, nm; where D AV =4V C / (SS C ), S is the total specific surface area, m 2 / g;

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

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

[0202] Calculation method of surface coverage adsorption coefficient (b):

[0203] By dividing the adsorption amount at each relative pressure point on the adsorption isotherm of the model adsorption material by the total surface area, the trend of the covering adsorption coefficient (b = Q / S) changing with relative pressure can be obtained, as shown in the following example: Figure 13 As shown in the figure, in the adsorption isotherm in the low-pressure region, the adsorption capacity increases slowly, indicating the gradual formation of monolayer or multilayer surface coverage adsorption. In this state, 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 for the coefficient (b) of different pore sizes can be obtained by linearly fitting the adsorption isotherm of the low-pressure region (b = k b ×P / P0+d b ), where d b is the intercept, k b are the slopes, which are affected by pore size and adsorption temperature.

[0205] For the MCM-41-3.0 model adsorption material, when the adsorption temperature is 5°C, the linear fitting result of the surface coverage adsorption coefficient (b) is b = 0.00319 × P / P0 + 0.0000496; when the adsorption temperature is 45°C, the linear fitting result of the surface coverage adsorption coefficient (b) is b = 0.00214 × P / P0 + 0.0000327. Figure 14 shown.

[0206] For the MCM-41-4.0 model adsorption material, when the adsorption temperature is 5°C, 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 45°C, the linear fitting result of the coefficient (b) of surface coverage adsorption is b = 0.00147 × P / P0 + 0.0000439. Figure 15 shown.

[0207] For the MCM-41-4.5 model adsorption material, when the adsorption temperature is 5°C, the linear fitting result of the surface coverage adsorption coefficient (b) is b = 0.00160 × P / P0 + 0.000102; when the adsorption temperature is 45°C, the linear fitting result of the surface coverage adsorption coefficient (b) is b = 0.00115 × P / P0 + 0.000097. Figure 16 shown.

[0208] Combining the three model adsorption materials MCM-41-3.0, MCM-41-4.0 and MCM-41-4.5, in the first stage of the adsorption isotherm, the equation of the coefficient (b) for different adsorption temperatures and different pore sizes (b = k b ×P / P0+d b ), we can find the intercept d in these equations b and slope k b , are affected by pore size and adsorption temperature. The intercept d of the surface coverage adsorption coefficient (b) equation for three model adsorbent materials with the most probable pore sizes of 3.0nm, 4.0nm, and 4.5nm at 5℃ and 45℃ is b and slope k b The values are shown in Table 3.

[0209] Table 3. Surface coverage adsorption coefficient (b) and intercept d of the equation for three model adsorbent materials with most probable pore sizes of 3.0 nm, 4.0 nm, and 4.5 nm at 5°C and 45°C. b and slope k b The value of

[0210] Aperture <![CDATA[k at 5°C b > <![CDATA[d at 5 °C b > <![CDATA[k at 45°C b > <![CDATA[d at 45°C 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 slope k of the coefficient (b) of the covering adsorption equation is b The value of shows a decreasing trend as the pore size of the material increases. Assuming that the pore size and the slope k b It is a linear relationship, and the slope is set as equation k b =k k ×D AS +d k , where D AS (D AS =4(VV C ) / S C ) is the average pore size of the pores that undergo surface coverage adsorption.

[0212] According to the slope k at 5℃, b The variation trend in the three model adsorption materials with pore sizes of 3.0 nm, 4.0 nm, and 4.5 nm can be obtained from the equation k b =0.00632-0.00103×D AS , where D AS (D AS =4(VV C ) / S C ) is the average pore size of the pores for surface coverage adsorption, such as Figure 17 shown.

[0213] According to the slope k at 45℃, b The variation trend in the three model adsorption materials with pore sizes of 3.0 nm, 4.0 nm, and 4.5 nm can be obtained from the equation k b =0.00412-0.00066×D AS , where D AS (D AS =4(VV C ) / S C ) is the average pore size of the pores for surface coverage adsorption, such as Figure 17 shown.

[0214] from Figure 17 It can be seen that the slope k of the covering adsorption coefficient b corresponding to the adsorption temperature T b There are important effects, such as k at 5℃ b=0.00632-0.00103×D AS , k at 45℃ b =0.00412-0.00066×D AS This is mainly because as the adsorption temperature increases, the adsorption force of the pore wall of the adsorption material on VOCs molecules weakens, resulting in a decrease in the amount of benzene adsorbed per unit surface area, and therefore the coefficient b also shows a regular change.

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

[0216] The intercept d of the coefficient of surface coverage adsorption (b) equation b The values at different pore sizes and adsorption temperatures are shown in Table 3. b The average value of d is obtained b At the same time, in the same pore size, the intercept d of the covering adsorption coefficient (b) corresponding to different adsorption temperatures is b There are also some differences, such as Figure 14 As shown, for a pore of 3.0 nm, the intercept d of the coefficient b at 5°C is b The intercept d of coefficient b is 0.0000496 at 45°C. b is 0.0000327, so the intercept d of the adsorption temperature T on the coefficient b can be obtained P The increase brought by △ 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 setting the aperture D AS , relative pressure P / P0 and adsorption temperature T are introduced as variables to introduce coefficient b. During the adsorption process of benzene at different temperatures, the equation of surface coverage adsorption coefficient b is:

[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 ×T) Equation 6.1;

[0219] In Equation 6.1, b is the coefficient of covering adsorption, that is, the amount of VOCs adsorbed per unit surface area, g / m 2 , where b = g(D AS ,P / P0,T) represents the coefficient b is the average pore diameter D AS , function of relative pressure P / P0 and adsorption temperature T;

[0220] D AS is the average pore size of the pores where covering adsorption occurs, nm;

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

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

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

[0224] In summary, the present invention is to make the pore size D, relative partial pressure P C / P0 and adsorption temperature T are introduced as parameters into the VOCs adsorption prediction equation Q=a×V C +b×S C The filling adsorption coefficient a and the covering adsorption coefficient b are obtained as a function of the pore size D and the relative partial pressure P. C / P0 and the regularity equation of the adsorption temperature T. Thus, the adsorption amount / isotherm prediction equation across the adsorption temperature is derived, and the equation suitable for predicting the adsorption amount / isotherm of benzene at different temperatures is:

[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 is the amount of VOCs adsorbed per unit mass of adsorbent material, g / g;

[0227] V C is the pore volume below the critical pore size, i.e., the critical pore volume, cm 3 / g;

[0228] S C is the specific surface area of pores above the critical pore size, i.e. the critical specific surface area, m 2 / g.

[0229] D AV is the average pore size of the pores where filling adsorption occurs, nm; where D A =4V C / (SS C ), S is the total specific surface area, m 2 / g;

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

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

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

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

[0234] Through the same equation (Equation 4.1), the VOCs adsorption amount and isotherm at different temperatures can be predicted based on the pore structure parameters of the model adsorption material. C and 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), the critical pore size D for filling adsorption at different adsorption temperatures T and different relative pressures P / P0 was obtained. C Combining the pore structure parameters of the model adsorption material, any critical pore size D can be obtained. C The critical pore volume V C and critical specific surface area S C The adsorption temperature T, relative pressure P / P0 and the corresponding pore structure parameters (D AV 、D AS 、V C 、SC ) is substituted into the adsorption amount prediction equation to calculate the predicted adsorption isotherms at different temperatures, thus realizing the cross-temperature adsorption amount / isotherm prediction.

[0235] Using the same cross-temperature adsorption amount prediction equation (Equation 4.1), the pore structure parameters of MCM-41-4.0 and the adsorption temperature T (5℃, 15℃, 25℃, 35℃, 45℃) are substituted into the equation to calculate the trend of the adsorption amount of benzene of the MCM-41-4.0 model adsorbent material at multiple adsorption temperatures as a function of relative pressure, i.e., the predicted normalized adsorption isotherm. The predicted and measured normalized adsorption isotherms at different adsorption temperatures are shown in Figure 4.1. Figure 19 As shown in Figure 2, it can be seen that the predicted normalized adsorption isotherm can be well coincided with the measured normalized adsorption isotherm obtained from the experimental test.

[0236] Based on the obtained prediction equation of the adsorption amount of volatile organic compounds across adsorption temperatures, the critical pore size D under the corresponding adsorption conditions (adsorption temperature T, relative pressure P / P0) can be calculated through the pore structure parameters of the model adsorption material. C The corresponding critical pore volume V C , critical specific surface area S C Substitute the known numbers into the equation to solve the trend of adsorption amount changing with relative pressure at different adsorption temperatures. By multiplying the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 (49.58mbar, 79.03mbar, 127.61mbar, 198.63mbar, 299.2mbar) at the corresponding temperature (5℃, 15℃, 25℃, 35℃, 45℃), the predicted adsorption isotherm before normalization at the corresponding adsorption temperature can be obtained. The same equation can be used to predict the VOCs adsorption amount and isotherm at different temperatures, such as Figure 20 shown.

[0237] This VOCs adsorption amount prediction equation across adsorption temperatures, through the study of the critical pore size of filled adsorption and its variation with adsorption temperature, obtains a regularity equation for the critical pore size that can cause filled adsorption under different adsorption conditions (temperature, pressure). Based on the pore volume of the pores where filled adsorption occurs and the specific surface area of the pores where covered adsorption occurs, and taking pressure and adsorption temperature-related parameters (saturated vapor) as variables, the VOCs adsorption amount prediction equation across adsorption temperatures is obtained. According to this equation, the VOCs adsorption amount and isotherms at different temperatures can be predicted through the same equation based on the pore structure parameters of the adsorption material, which has important reference value for the development of VOCs adsorption materials and technologies.

[0238] Example 2

[0239] In order to further verify that the obtained adsorption amount prediction equation can be applied to the prediction of the adsorption amount and adsorption isotherm of specific VOCs by other conventional adsorption materials, this example uses porous silica materials without concentrated pore size distribution (such as Figure 21 The adsorption material is shown in FIG. 1 . The benzene adsorption amount prediction equation across the adsorption temperature obtained in Example 1 is used to verify the applicability of the equation to adsorption materials with other non-concentrated pore size distributions.

[0240] The pore structure parameters of the adsorbent material were tested using a commercial specific surface area and pore structure analyzer, and the pore structure parameters of the adsorbent material were obtained using the DFT cylindrical pore calculation model. C and critical relative pressure P C The ternary matching relationship equation between / P0 and adsorption temperature T (Equation 3.1), combined with the obtained pore structure parameters of the adsorption material, according to the relationship between the cumulative pore volume and cumulative specific surface area and the pore diameter, the critical pore diameter D under the corresponding adsorption conditions (adsorption temperature T, relative pressure P / P0) is obtained. C The corresponding critical pore volume V C , critical specific surface area S C and other parameters.

[0241] The critical pore size D of the filled adsorption in Example 1 C and critical relative pressure P C The ternary matching relationship equation between / P0 and adsorption temperature T is:

[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 under the corresponding adsorption conditions C The corresponding critical pore volume V C , critical specific surface area S C Substitute the parameters as known numbers into the benzene cross-temperature adsorption prediction equation (Equation 4.1) and solve the trend of the adsorption amount changing with relative pressure at the corresponding adsorption temperature, as shown in the following example: Figure 22 shown.

[0244] In Example 1, the prediction equation for the adsorption amount of benzene across the adsorption temperature is:

[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 ×T)×D AS )×P / P0+(0.00006-4.23×10 -7 ×T))×S C Equation 4.1;

[0246] By multiplying the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 (127.61 mbar) at the corresponding temperature (25°C), the adsorption isotherm of benzene on the porous silica adsorption material before normalization at 25°C is calculated, that is, the predicted adsorption isotherm, such as Figure 23 shown. Figure 23 Comparison of the predicted and measured adsorption isotherms for porous silica adsorbents without concentrated pore size distribution. Figure 23 It can be seen that the prediction method provided by the present invention can well coincide with the adsorption isotherm obtained from experimental tests.

[0247] It can be found that the method of the present invention is also applicable to the prediction of the adsorption amount and adsorption isotherm of specific VOCs at different adsorption temperatures by other adsorption materials that do not have a concentrated pore size distribution. The adsorption amount prediction equation obtained using the silicon-based adsorption material in Example 2 can be directly used to predict the adsorption amount of other silicon-based adsorption materials that do not have a concentrated pore size distribution. Therefore, when the composition and surface properties of the materials are relatively similar, the obtained adsorption amount prediction equation can be directly used to predict the adsorption amount and adsorption isotherm of other adsorption materials at different adsorption temperatures. This shows that the VOCs adsorption amount and adsorption isotherm prediction method of the present invention has good generalizability.

[0248] Example 3

[0249] The derivation of the adsorption prediction equation demonstrates that this VOC adsorption prediction method is not limited by VOC type and exhibits good generalizability. To further validate the generalizability of this method, this example uses acetone as the adsorbate and measures the adsorption isotherms of a series of model adsorbent materials at multiple adsorption temperatures. Incorporating pore structure parameters, an equation for predicting acetone adsorption across adsorption temperatures was derived.

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

[0251] By dividing each pressure point on the adsorption isotherm by the saturated vapor pressure at the corresponding temperature, the static adsorption isotherm after partial pressure normalization is obtained, such as Figure 25 According to the normalized adsorption isotherms of three model adsorbent materials (pore sizes of 3.0 nm, 4.0 nm and 4.5 nm) at five temperatures (5, 15, 25, 35 and 45 °C), the midpoint of the rapid rise phase corresponding to the occurrence of filling adsorption (critical relative pressure P C / P0), as shown in Table 4.

[0252] Table 4 Relative pressure (P) at the midpoint of the rapid rise phase corresponding to the filling adsorption on the normalized acetone adsorption isotherm C / P0) value

[0253]

[0254] According to the method of Example 1, by matching the critical relative pressure at different temperatures in the same pore size with the adsorption temperature, the critical relative pressure (P C The linear relationship equation between the adsorption temperature (T) and the critical relative pressure (P C The linear relationship equation between / P0) and adsorption temperature (T) is shown in the linear fitting results. Figure 26 As shown, the linear relationship equations are:

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

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

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

[0258] The critical relative pressure (P C By comparing the linear relationship equation between P / P0) and adsorption temperature (T), it can be found that the linear relationship equation P C / P0=k P ×T+d P The coefficient k P and d P There are certain differences among different pore sizes, as shown in Table 5.

[0259] Table 5 Critical relative pressure (P) of acetone adsorbed by pores of different sizesC The coefficient k of the linear relationship equation (Equation 1) between / P0) and adsorption temperature (T) P and d P

[0260] Aperture <![CDATA[Coefficient k P > <![CDATA[Coefficient d P > 3.0nm 0.00102 0.126 4.0nm 0.00124 0.247 4.5nm 0.00168 0.302

[0261] According to Equation 2, the critical relative pressure (P C The coefficient k in the linear relationship equation between / P0) and adsorption temperature (T) P and d P , linear fitting is performed with respect to the respective pore sizes (3.0nm, 4.0nm, 4.5nm), and the coefficient k is obtained 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, as Figure 27 As shown, the critical relative pressure of filling adsorption (P C / P0) varies with adsorption temperature T and pore size D C The changing matching relationship 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, °C;

[0265] D C The relative pressure is P C / P0, the critical pore size for filling adsorption to occur, nm.

[0266] Using the obtained equation (Equation 2.2) combined with the method of Equation 3, we can get D C The matching relationship equation between T and P / P0 is Equation 3.2:

[0267] D C =(P C / P0-0.000253×T+0.227) / (0.00041×T+0.118), Equation 3.2;

[0268] 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;

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

[0270] D C The relative pressure is P C / P0, the critical pore size for filling adsorption to occur, nm.

[0271] According to the method of Example 1, the pore size D, the relative partial pressure P C / P0 and adsorption temperature T are introduced as parameters into the VOCs adsorption prediction equation Q=a×V C +b×S C The filling adsorption coefficient a of the acetone adsorption prediction equation is obtained (e.g. Figure 28 and Figure 29 As shown) and the covering adsorption coefficient b (as Figure 30 and 31 As shown), with the pore diameter D, relative partial pressure P C / P0 and the regularity equation of the adsorption temperature T. Among them, when calculating the adsorption coefficient b, by analyzing Figure 30 It can be seen that the slope k of adsorption temperature versus b b Therefore, to simplify the calculation, we take the slope k of b in the adsorption isotherm of each model adsorption material at 25℃. b The values are taken as average values. The equations for the filling adsorption coefficient a and the covering adsorption coefficient b are:

[0272] a=0.5+0.057×D AV +0.12×P / P0-0.00115×T;

[0273] b=(0.00185-0.000266×D AS )×P / P0+(0.000176+0.00000857×D AS )-6.5×10 -7 ×T;

[0274] Thus, the adsorption amount / isotherm prediction equation across the adsorption temperature is derived, and the equation suitable for predicting the adsorption amount / isotherm of acetone at different temperatures is obtained as follows:

[0275] Q=(0.5+0.057×D AV+0.12×P / P0-0.00115×T)×V C +((0.00185-0.000266×D AS )×P / P0+(0.000176+0.00000857×D AS )-6.5×10 -7 ×T)×S C Equation 4.2;

[0276] Among them, Q, V C 、S C 、D AV 、D AS , T, P / P0, etc. have the same meanings as in Equation 4.

[0277] Based on the obtained prediction equation for the amount of acetone adsorption across adsorption temperatures (Equation 4.2), the adsorption temperature T of the adsorption isotherm, the value of the relative pressure P / P0 and its corresponding pore structure parameter (D AV 、D AS 、V C 、S C ) is substituted into the adsorption amount prediction equation (Equation 4.2) to solve the trend of adsorption amount changing with relative pressure at different adsorption temperatures. By multiplying the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 (120.1mbar, 195.73mbar, 306.73mbar, 464.28mbar, 681.42mbar) at the corresponding temperature (5℃, 15℃, 25℃, 35℃, 45℃), the predicted adsorption isotherm at the corresponding adsorption temperature can be obtained, as shown in Figure 4. Figure 32 As shown, the VOCs adsorption amount and isotherms at different temperatures can be predicted by the same equation. Figure 32 are the predicted and measured adsorption isotherms at different adsorption temperatures, Figure 32 It can be seen that the prediction method provided by the present invention can well coincide with the adsorption isotherm obtained from experimental tests. It can be found that the method of the present invention is also applicable to the derivation and prediction of the adsorption amount and adsorption isotherm prediction equations of other VOCs (such as acetone) at different adsorption temperatures.

[0278] In general, by comparing with the benzene adsorption prediction equation in Example 1, it can be found that the VOCs adsorption prediction equation Q = a × V C +b×S CThe basic structure remains unchanged, that is, the adsorption of VOCs by porous materials includes two parts: filling adsorption and covering adsorption. By introducing adsorption temperature T, relative pressure P / P0 and pore size D as variables, the influence of the difference in adsorption temperature is effectively overcome, and the prediction across adsorption temperatures is achieved using the same equation. Due to differences in the saturated vapor pressure, molecular weight, molecular size, boiling point, polarity and other properties of different VOCs, the coefficients (a and b) corresponding to filling adsorption and covering adsorption will also be different. But in general, based on the adsorption isotherm of the model adsorption material for specific VOCs and the pore structure parameters of the model adsorption material, the method of the present invention can be used to derive the adsorption amount prediction equation for the specific VOCs across adsorption temperatures, indicating that the VOCs adsorption amount / adsorption isotherm prediction method across adsorption temperatures developed by the present invention has good generalizability.

[0279] Example 4

[0280] In order to further verify that the obtained adsorption amount prediction equation can be applied to the prediction of the adsorption amount and adsorption isotherm of specific VOCs by other conventional adsorption materials, this example uses two porous silica materials without concentrated pore size distribution (such as Figure 33 The adsorption material is shown in FIG. 3 . The acetone adsorption amount prediction equation across the adsorption temperature obtained in Example 3 is used to verify the applicability of the equation to adsorption materials with other non-concentrated pore size distributions.

[0281] The pore structure parameters of the adsorbent material were tested using a commercial specific surface area and pore structure analyzer, and the pore structure parameters of the adsorbent material were obtained using the DFT cylindrical pore calculation model. C and critical relative pressure P C The ternary matching relationship equation between / P0 and adsorption temperature T (Equation 3.2), combined with the obtained pore structure parameters of the adsorption material, according to the relationship between the cumulative pore volume and cumulative specific surface area and the pore diameter, the critical pore diameter D under the corresponding adsorption conditions (adsorption temperature T, relative pressure P / P0) is obtained. C The corresponding critical pore volume V C , critical specific surface area S C and other parameters.

[0282] The critical pore size D of the filled adsorption in Example 3 C and critical relative pressure P C The ternary matching relationship 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] The critical pore size D under the corresponding adsorption conditions C The corresponding critical pore volume V C , critical specific surface area S C Substitute the parameters as known numbers into the prediction equation of acetone adsorption across temperature (Equation 4.2) and solve the trend of adsorption amount changing with relative pressure at the corresponding adsorption temperature, as shown in the following example: Figure 34 shown.

[0285] In Example 3, the prediction equation for the adsorption amount of acetone across the adsorption temperature is:

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

[0287] By multiplying the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 (464.28 mbar) of acetone at the corresponding temperature (35 ° C), the adsorption isotherms of acetone on the two porous silica adsorption materials before normalization at 35 ° C were calculated, that is, the predicted adsorption isotherms, such as Figure 35 shown. Figure 35 Comparison of the predicted and measured adsorption isotherms for two porous silica adsorption materials without concentrated pore size distribution. Figure 35 It can be seen that the adsorption isotherm of acetone at 35° C. obtained by the prediction method provided by the present invention can be well coincided with the adsorption isotherm obtained by experimental testing.

[0288] The above description shows that the method of the present invention is also applicable to the prediction of the adsorption amount and adsorption isotherm of specific VOCs at different adsorption temperatures by other adsorption materials that do not have a concentrated pore size distribution. The acetone adsorption amount prediction equation across adsorption temperatures obtained using the silicon-based adsorption material in Example 3 can be directly used to predict the adsorption amount of other silicon-based adsorption materials that do not have a concentrated pore size distribution. Therefore, when the composition and surface properties of the materials are relatively similar, the obtained adsorption amount prediction equation can be directly used to predict the adsorption amount and adsorption isotherm of other adsorption materials at different adsorption temperatures. This shows that the VOCs adsorption amount and adsorption isotherm prediction method of the present invention has good generalizability.

[0289] In summary, based on the theoretical basis that the adsorption of VOCs by porous materials includes filling adsorption and covering adsorption, the regularity equation of the critical pore size for filling adsorption under different adsorption conditions (temperature, relative pressure) is obtained. C and the specific surface area S of the pores where covering adsorption occurs C The contribution to the adsorption of VOCs is obtained, and the basic structure of the adsorption prediction equation is Q = a × V C +b×S C . By taking pore size D, relative pressure P / P0 and adsorption temperature T as variables, introducing the coefficients of filling adsorption and covering adsorption, the VOCs adsorption amount prediction equation across adsorption temperature is obtained. This equation can be used for adsorbents with the same or similar surface properties to predict the VOCs adsorption amount and isotherms of adsorbent materials at different adsorption temperatures. Based on the obtained volatile organic compound adsorption amount prediction equation across adsorption temperature, the critical pore size D under the corresponding adsorption conditions (adsorption temperature T, relative pressure P / P0) can be calculated through the pore structure parameters of the adsorbent material. C The corresponding critical pore volume V C , critical specific surface area S C Substitute the known numbers into the equation to solve the trend of the adsorption amount changing with the relative pressure at different adsorption temperatures. Multiply the relative pressure P / P0 of the predicted adsorption isotherm by the saturated vapor pressure P0 at the corresponding temperature to obtain the predicted adsorption isotherm before normalization at the corresponding adsorption temperature. The VOCs adsorption amount and isotherm at different temperatures can be predicted by the same equation. The VOCs adsorption amount and adsorption isotherm prediction method of the present invention has good scalability and is of great reference significance for the optimization of adsorption materials and technologies.

[0290] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for predicting the adsorption amount of volatile organic compounds across adsorption temperatures, characterized in that: The following steps are involved: (1) providing two or more porous materials with concentrated pore size distribution as model adsorption materials, and testing the pore structure parameters of the model adsorption materials, wherein the pore structure parameters include pore size distribution, cumulative pore volume change with pore size distribution, total pore volume V, cumulative specific surface area change with 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 isotherm after partial pressure normalization by dividing each pressure point on the static adsorption isotherm by the saturated vapor pressure P0 at the corresponding temperature; The relative pressure range corresponding to the filling adsorption of the model adsorption material is obtained according to the static adsorption isotherm after the partial pressure normalization, and the middle value of the relative pressure range is taken as the relative critical pressure P C / P0; the critical relative pressure P C / P0 corresponds to the median value of the pore size distribution of the model adsorbent, and the median value of the pore size distribution is taken as the critical relative pressure P C / The critical pore size D for filling adsorption at P0 C ; The critical relative pressure P of the model adsorption material C / P0 is linearly fitted with the adsorption temperature T to obtain the critical relative pressure P under a specific pore size. C The linear relationship equation between / P0 and adsorption temperature: P C / P0=k P ×T+d P , Equation 1; 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; T is the adsorption temperature, °C; k P is the slope of the linear relationship between relative pressure and adsorption temperature; d P When the relative pressure approaches 0 in the linear relationship, P C / The value of P0; According to the different P values corresponding to different adsorption temperatures T of the adsorption material in this model C / P0 value, solve the coefficient k in equation 1 corresponding to the adsorption material of this model P and d P ; (3) Referring to the method of step (2), the coefficient k in equation 1 corresponding to other model adsorption materials is obtained. P and d P ; (4) Multiple critical apertures D C Under the critical relative pressure P C k of the linear relationship equation between / P0 and adsorption temperature T P and d P , relative to their respective critical apertures D C Do linear fitting and get the coefficient k P and d P With the critical aperture D C The linear relationship equation of change k P =k P1 ×D C +k P0 and d P =d P1 ×D C +d P0 , thus obtaining the filling adsorption critical relative pressure P C / P0 varies with adsorption temperature T and pore size D C The linear relationship equation of change: P C / P0=(k P1 ×D C +k P0 )×T+(d P1 ×D C +d P0 ), Equation 2; 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; T is the adsorption temperature, °C; D C The relative pressure is P C / P0, the critical pore size for filling adsorption to occur, nm; k P1 and k P0 k P With the critical aperture D C the slope and intercept of a changing linear relationship equation; d P1 and d P0 d P With the critical aperture D C the slope and intercept of a changing linear relationship equation; Using Equation 2, we can get different relative pressures P C / P0, the critical pore size D for filling adsorption to occur C The matching relationship equation between the adsorption temperature T is: D C =(P C / P0-k P0 ×Td P0 ) / (k P1 ×T+d P1 ), Equation 3; 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; (5) With the critical pore size D C As the dividing point, according to the change of cumulative pore volume with pore size distribution and cumulative specific surface area with pore size distribution tested by pore structure parameters, the critical pore size D of the model adsorption material is obtained. C The pore volume V of the following pores C and critical pore size D C The specific surface area S of the pores above C ; (6) Based on the pore volume V of the pores where filling adsorption occurs C and the specific surface area S of the pores where covering adsorption occurs C The contribution of different model adsorption materials to the VOCs adsorption amount is analyzed, and the pore size, relative pressure and adsorption temperature of the adsorption materials are introduced as parameters into the adsorption amount prediction equation to obtain the VOCs adsorption amount prediction equation across adsorption temperatures that can be extended to the adsorption isotherm prediction at different adsorption temperatures T: 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; Wherein, Q is the adsorption capacity of VOCs per unit mass of adsorption material, g / g; V C is the pore volume below the critical pore size, i.e., the critical pore volume, cm 3 / g; S C is the specific surface area of pores above the critical pore size, i.e. the critical specific surface area, m 2 / g; D AV is the average pore size of the pores where filling adsorption occurs, nm; where D AV =4V C / (SS C ), S is the total specific surface area, m 2 / g; D AS is the average pore size of the pores where covering adsorption occurs, nm; where D AS =4(VV C ) / S C , V is the total pore volume, cm 3 / g; T is the adsorption temperature, °C; P / P0 is any relative pressure point on the adsorption isotherm normalized 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 filling adsorption, that is, the adsorption amount of VOCs per unit pore volume, g / cm 3 , where a=f(D AV ,P / P0,T) indicates that the coefficient a is the aperture D AV , function of relative pressure P / P0 and adsorption temperature T; b is the coefficient of covering adsorption, that is, the adsorption amount of VOCs per unit specific surface area, g / m 2 , where b = g(D AS ,P / P0,T) indicates that the coefficient b is the aperture D AS , function of relative pressure P / P0 and adsorption temperature T; (7) By testing the pore structure of multiple model adsorption materials and the adsorption isotherms under different adsorption conditions, the critical pore size D under the corresponding conditions is obtained. C , adsorption capacity Q, critical pore volume V C , critical specific surface area S C , average pore diameter D AV and D AS , the pore structure parameters of the model adsorption material and the adsorption isotherms of specific VOCs under different adsorption conditions are substituted into Equation 4 to obtain the specific values of a and b, and the prediction equation for the adsorption amount of volatile organic compounds across the adsorption temperature is obtained.

2. The method according to claim 1, characterized in that The model adsorption material is one or more of ordered mesoporous silicon, ordered mesoporous carbon and molecular sieve with concentrated pore size distribution.

3. The method according to claim 1, characterized in that 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.

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