A device and method for quantitatively measuring the acidity of a material surface

Abstract

A device and method for quantitative determination of surface acidity of a material, comprising a hollow measuring tube, a spring suspended at the top is arranged in the measuring tube, and an aperture and a sample basket are connected in sequence below the spring; in the horizontal direction of the aperture, a movable bracket is arranged outside the measuring tube, one end of the movable bracket is a light source, and the other end is a detector or an infrared camera, the movable bracket is movably fixedly installed on a guide rail driven by a stepper motor, and can be controlled by the stepper motor to move up and down on the guide rail, so that the light source, the aperture and the detector or the infrared camera are located on the same horizontal straight line, and the detector or the infrared camera and the stepper motor are externally connected to a program control system; a heating device is arranged around the sample basket; the invention measures the amount and distribution of acid on the surface of the material by converting the light intensity transmitted by the aperture detected by the detector or the consistency of the infrared camera imaging through the deformation of the spring caused by the change of the sample weight into the angle and direction of rotation of the stepper motor. The device of the invention has a wide range of applications and high accuracy of results. During the determination process, the device automatically completes the determination, reducing manual operations, and is easy and convenient to implement.

Description

Technical Field

[0001] The invention relates to the technical field of material characterization, and in particular to a device and a method for quantitatively determining the surface acidity of a material. Background Art

[0002] The acidic sites of materials such as solid acid catalysts are generally regarded as active sites on the surface of oxide catalysts. In reactions such as catalytic cracking, isomerization, and polymerization, hydrocarbon molecules and surface acidic sites interact to form positive carbon ions, which are intermediate products of the reaction. The positive carbon ions can theoretically successfully explain the reaction of hydrocarbons on the acidic surface and provide strong evidence for the existence of acidic sites. In order to characterize the properties of materials, it is necessary to measure the acid strength and acid amount of surface acidic sites.

[0003] Pyridine was the first probe molecule proposed for determining the surface acidity of catalysts. During the experiment, pyridine was saturatedly adsorbed on the purified catalyst, and then high vacuum desorption was performed under different temperature conditions. The weight change of the catalyst was measured in real time using a spring balance to obtain the acid strength distribution and acid amount of the catalyst.

[0004] The existing method for determining infrared acid is the gravimetric method, that is, using a spring balance to determine the acidity of the catalyst. However, this device is large in size, complicated to operate, and most importantly, uses an expensive altimeter, and requires manual observation and conversion, resulting in large errors in the determination. In order to facilitate the determination of the acidity of catalytic materials and improve the accuracy and repeatability of the acidity determination results, it is urgent to establish a catalytic material acidity determination device and method that can conveniently, quickly and accurately determine the material surface acidity information and improve the accuracy and repeatability of the determination. Summary of the invention

[0005] In order to solve the problems of large size, complicated operation and large error in measurement results of material surface acidity measurement devices in the prior art, the present invention provides a device and a measurement method for quantitative measurement of material surface acidity. By using the device, the acidity information of the catalytic material can be obtained, which is convenient for improving the accuracy of the measurement results and work efficiency. After the analysis starts, the control program automatically runs until the test process is completed and the results are calculated, thereby reducing the workload of analysts and improving the measurement accuracy.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] The technical purpose of the first aspect of the present invention is to provide a device for quantitatively determining the surface acidity of a material, comprising a hollow measuring tube, a spring suspended from the top is arranged inside the measuring tube, and an aperture and a sample basket are connected in sequence below the spring; in the horizontal direction of the aperture, a movable bracket is arranged outside the measuring tube, one end of the movable bracket is a light source, and the other end is a detector or an infrared camera, the movable bracket is movably fixedly mounted on a guide rail driven by a stepper motor, and can be controlled by the stepper motor to move up and down on the guide rail so that the light source, the aperture and the detector or the infrared camera are located on the same horizontal straight line, and the detector or the infrared camera and the stepper motor are all externally connected to a program control system; a heating device is arranged around the sample basket, the heating device is arranged outside the measuring tube, and a temperature detection device is arranged next to the sample basket, the heating device and the temperature detection device are both connected to the temperature control system outside the measuring tube, and the temperature control system is connected to the program control system; the measuring tube is also connected to an adsorption probe molecule tube and a vacuum system.

[0008] Furthermore, the light source is a red laser light source, and the same laser light source is used when the detector and the infrared camera are used.

[0009] Furthermore, the centers of the light source, the aperture and the detector or the infrared camera are on a horizontal line.

[0010] Furthermore, when a detector is installed at one end of the movable bracket, the movable bracket moves on the guide rail and is controlled by the program control system so that the light intensity detected by the detector after each movement is consistent with that before. The program control system records the angular rotation and direction information of the stepper motor during each movement, which corresponds to the change in spring length and is associated with the change in sample weight in the sample basket.

[0011] Furthermore, when an infrared camera is installed at one end of the movable bracket, the movable bracket moves on the guide rail and is controlled by the program control system so that the infrared image collected after each movement is consistent. The program control system records the angular rotation and direction information of the stepper motor during each movement, which corresponds to the change in spring length and is associated with the change in sample weight in the sample basket.

[0012] Furthermore, the measuring tube between the heating device and the sample basket is made of quartz glass, and the sample basket is made of quartz glass.

[0013] Furthermore, the heating device is a heating furnace; and the temperature detection device is a thermocouple.

[0014] Furthermore, the adsorption probe molecular tube is a pyridine tube.

[0015] Furthermore, the vacuum system is a combination of a molecular turbo pump and a mechanical pump, which can meet the vacuum degree of the system to reach 10 -4 Pa.

[0016] The technical purpose of the second aspect of the present invention is to provide a method for quantitatively determining the surface acidity of a material using the above-mentioned device, which is as follows:

[0017] First, the stepper motor is rotated through the program control system to drive the moving bracket to move, so that the light emitted by the light source is irradiated onto the detector through the slit in the center of the aperture or formed on the infrared camera. The program control system records the light intensity or image, and records the initial stepper motor angle and spring length. When the sample to be tested is placed in the sample basket, the vacuum degree is adjusted through the vacuum system, the temperature is adjusted through the heating device, and the adsorption probe molecule tube is opened to allow the sample to adsorb the molecular probe, the spring is deformed due to the change in sample weight, the aperture position changes, and the light transmittance detected by the detector or the image on the infrared camera changes accordingly, and the change information is output to the program control system. In order to keep the light intensity or image consistent with the previous one, the program control system sends a rotation command to the stepper motor, converts the angle and direction of the stepper motor rotation into a change in the spring length, and then associates it with the sample weight and the change in weight, thereby obtaining the acidity information of the sample to be tested.

[0018] Further, as one of the more specific implementations, the specific steps of determination are as follows:

[0019] (1) The program control system rotates the stepper motor to drive the movable bracket to move, so that the light emitted by the light source passes through the slit in the center of the aperture and is irradiated onto the detector or imaged on the infrared camera. The program control system records the light intensity or image, and records the initial stepper motor angle and spring length;

[0020] (2) A sample of a certain weight is placed in the sample basket. The spring becomes longer, the aperture position changes, and the light intensity detected by the detector or the image on the infrared camera changes. The change information is output to the program control system. In order to keep the light intensity or image consistent with the previous one, the program control system sends a rotation command to the stepper motor, converts the angle and direction of the stepper motor into a change in the spring length, and then associates it with the change in sample weight.

[0021] (3) The vacuum degree is adjusted by the vacuum system, and the temperature is adjusted by the heating device. The sample is subjected to high-temperature and high-vacuum purification treatment. After purification, the temperature is lowered to room temperature. The program control system automatically records the rotation angle and direction of the stepper motor. The adsorption probe molecule tube is opened to allow the sample to adsorb the molecular probe. After adsorption equilibrium, the probe molecule adsorption tube is closed, and the programmed temperature rise and vacuum treatment are started to obtain the correlation information between the rotation angle and direction of the stepper motor and the change in sample weight under different temperatures and pressures, thereby obtaining quantitative acidity information of the sample under different measurement conditions.

[0022] (4) After all temperature points are measured, the conversion relationship between spring length and sample weight is obtained based on the angle and direction data of the stepper motor rotation, and the acid content and acid strength distribution of the sample at different temperatures can be obtained.

[0023] In the above determination method, the technicians in this field should understand that in step (3), after the adsorption equilibrium is reached, the mass of the sample after the adsorption of the probe molecule also changes continuously due to the continuous change in temperature during the process of programmed heating and vacuum treatment. The program control system controls the rotation of the stepper motor, uses the light source and the detector or the infrared camera to track the change in the aperture height, and converts the change in the spring length through the rotation angle and direction of the stepper motor. Therefore, the program control system needs to continuously change the angle output to the stepper motor to track the sample height; the programmed heating should be maintained for a period of time at multiple preset temperature points so that the sample reaches the adsorption-desorption equilibrium state at the corresponding temperature, and then the motor rotation angle and direction at the corresponding temperature points are recorded respectively.

[0024] The present invention has the following advantages:

[0025] (1) The device of the present invention can quantitatively measure the acid content and acid strength distribution of various catalyst materials, has a wide range of applications, and has high accuracy and repeatability of the results. During the measurement process, the device automatically completes the measurement, reducing manual operations, and is easy and convenient to implement;

[0026] (2) This device does not require an expensive height gauge to measure the change in spring length and has the advantages of small size and easy operation;

[0027] (3) The acidity determination device can be completely encapsulated in an instrument housing, becoming a conventional analytical instrument that can be directly placed on a test bench, providing assistance for the development of new catalytic materials. The device has good application prospects and commercial value.

[0028] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 . Schematic diagram of the device for quantitatively determining the surface acidity of the material in Example 1;

[0030] Figure 2 . Schematic diagram of the device for quantitative determination of surface acidity of materials in Example 2;

[0031] Among them, 1. measuring tube, 2. spring, 3. detector, 4. aperture, 5. movable bracket, 6. light source, 7. heating furnace, 8. sample basket, 9. sample to be tested, 10. thermocouple, 11. pyridine tube, 12. stepper motor, 13. guide rail, 14. vacuum system, 15. program control system, 16. temperature control system, 17. infrared camera. DETAILED DESCRIPTION

[0032] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0033] Example 1

[0034] This embodiment discloses a device for quantitatively determining the acidity of a material surface. Figure 1 As shown:

[0035] The invention comprises a hollow measuring tube 1, a spring 2 suspended from the top is arranged in the measuring tube 1, an aperture 4 and a sample basket 8 are connected in sequence below the spring 2, and the sample basket 8 is made of quartz glass; in the horizontal direction of the aperture 4, a movable bracket 5 is arranged outside the measuring tube 1, and the two ends of the movable bracket 5 are respectively connected to the light source 6 and the detector 3, and the movable bracket 5 is movably fixed on the guide rail 13 driven by the stepping motor 12, and can be controlled by the stepping motor 12 to move up and down on the guide rail 13, so that the light source 6, the aperture 4 and the detector 3 are moved upward and downward, so that the light source 6, the aperture 4 and the detector 3 are moved upward and downward, and ... The detector 3 is located on the same horizontal line, and the detector 3 and the stepper motor 12 are connected to the program control system 15; a heating furnace 7 is arranged around the sample basket 8, and the heating furnace 7 is arranged outside the measuring tube 1. A thermocouple 10 is arranged next to the sample basket 8. The measuring tube 1 between the heating furnace 7 and the sample basket 8 is made of quartz glass. The heating furnace 7 and the thermocouple 10 are connected to the temperature control system 16 outside the measuring tube 1, and the temperature control system 16 is connected to the program control system 15; the measuring tube 1 is also connected to a pyridine tube 11 and a vacuum system 14. The vacuum system 14 is a combination of a molecular turbo pump and a mechanical pump, which can meet the system vacuum degree of 10 -4 Pa.

[0036] Example 2

[0037] This embodiment discloses a device for quantitatively determining the acidity of a material surface. Figure 2 As shown:

[0038] The invention comprises a hollow measuring tube 1, a spring 2 suspended from the top is arranged in the measuring tube 1, an aperture 4 and a sample basket 8 are connected in sequence below the spring 2, and the sample basket 8 is made of quartz glass; in the horizontal direction of the aperture 4, a movable bracket 5 is arranged outside the measuring tube 1, and the two ends of the movable bracket 5 are respectively connected to a light source 6 and an infrared camera 17, and the movable bracket 5 is movably fixedly installed on a guide rail 13 driven by a stepping motor 12, and can be controlled by the stepping motor 12 to move up and down on the guide rail 13, so that the light source 6, the aperture 4 and the infrared camera 17 are moved upward and downward, and ... The machine 17 is located on the same horizontal line, the infrared camera 17 and the stepper motor 12 are connected to the program control system 15; a heating furnace 7 is arranged around the sample basket 8, the heating furnace 7 is arranged outside the measuring tube 1, a thermocouple 10 is arranged next to the sample basket 8, the measuring tube 1 between the heating furnace 7 and the sample basket 8 is made of quartz glass, the heating furnace 7 and the thermocouple 10 are connected to the temperature control system 16 outside the measuring tube 1, and the temperature control system 16 is connected to the program control system 15; the measuring tube 1 is also connected to a pyridine tube 11 and a vacuum system 14. The vacuum system 14 is a combination of a molecular turbo pump and a mechanical pump, which can meet the system vacuum degree of 10 -4 Pa.

[0039] Example 3

[0040] This embodiment discloses a method for quantitatively determining the surface acidity of a material using the device of embodiment 1:

[0041] (1) The program control system 15 rotates the stepper motor 12 to drive the movable bracket 5 to move, so that the light emitted by the light source 6 passes through the slit in the center of the aperture 4 and irradiates the detector 3. The program control system 15 records the light intensity, the initial stepper motor 12 angle and the length of the spring 2;

[0042] (2) A sample 9 of a certain weight is placed in the sample basket 8, the spring 2 becomes longer, the position of the aperture 4 changes, the light intensity detected by the detector 3 changes, and the change information is output to the program control system 15. In order to keep the light intensity received by the detector 3 consistent with the previous one, the program control system 15 sends a rotation instruction to the stepper motor 12, converts the rotation angle and direction of the stepper motor 12 into a change in the length of the spring 2, and then associates it with the change in the sample weight;

[0043] (3) The vacuum degree is adjusted by the vacuum system 14, and the temperature is adjusted by the thermocouple 10. The sample is subjected to high temperature and high vacuum purification treatment. After purification, the temperature is lowered to room temperature. The program control system 15 automatically records the rotation angle and direction of the stepper motor 12. The pyridine tube 11 is opened to allow the sample to adsorb the molecular probe. After adsorption equilibrium, the pyridine tube 11 is closed, and the program heating and vacuum treatment is started to obtain the correlation information between the rotation angle and direction of the stepper motor 12 and the change in sample weight under a certain temperature and pressure, thereby obtaining the quantitative acidity information of the sample under this measurement condition. Then, the temperature and pressure are changed, and the measurement data under different measurement conditions can be obtained by the same method.

[0044] (4) After all temperature points are measured, the conversion relationship between the length of the spring 2 and the weight of the sample is obtained according to the angle and direction data of the stepper motor 12, and the acid content and acid strength distribution of the sample at different temperatures can be obtained.

[0045] Example 4

[0046] This embodiment discloses a method for quantitatively determining the surface acidity of a material using the device of embodiment 2:

[0047] (1) The program control system 15 rotates the stepper motor 12 to drive the movable bracket 5 to move, so that the light emitted by the light source 6 passes through the slit in the center of the aperture 4 to illuminate the infrared camera 17 to form an image, and the program control system 15 records the image, the initial stepper motor 12 angle and the length of the spring 2;

[0048] (2) A sample 9 of a certain weight is placed in the sample basket 8, the spring 2 becomes longer, the position of the aperture 4 changes, the image on the infrared camera 17 changes, and the change information is output to the program control system 15. In order to keep the image consistent with the previous one, the program control system 15 sends a rotation instruction to the stepper motor 12, and converts the rotation angle and direction of the stepper motor 12 into a change in the length of the spring 2, and then associates it with the change in the sample weight;

[0049] (3) The vacuum degree is adjusted by the vacuum system 14, and the temperature is adjusted by the thermocouple 10. The sample is subjected to high temperature and high vacuum purification treatment. After purification, the temperature is lowered to room temperature. The program control system 15 automatically records the rotation angle and direction of the stepper motor 12. The pyridine tube 11 is opened to allow the sample to adsorb the molecular probe. After adsorption equilibrium, the pyridine tube 11 is closed, and the program heating and vacuum treatment is started to obtain the correlation information between the rotation angle and direction of the stepper motor 12 and the change in sample weight under a certain temperature and pressure, thereby obtaining the quantitative acidity information of the sample under this measurement condition. Then, the temperature and pressure are changed, and the measurement data under different measurement conditions can be obtained by the same method.

[0050] (4) After all temperature points are measured, the conversion relationship between the length of the spring 2 and the weight of the sample is obtained according to the angle and direction data of the stepper motor 12, and the acid content and acid strength distribution of the sample at different temperatures can be obtained.

[0051] Example 5

[0052] This example discloses a process for determining the surface acidity of a specific catalyst material using the apparatus and method of Examples 1 and 3:

[0053] (1) The stepper motor 12 is rotated by the program control system 15 to drive the movable bracket 5 to move, so that the light emitted by the light source 6 is irradiated onto the detector 3 through the slit in the center of the aperture 4. The program control system 15 records the light intensity and the initial angle of the stepper motor 12; (2) 0.2g of the hydrocracking catalyst sample 9 to be tested is added to the sample basket 8, and the determination program control system 15 is turned on, and the vacuum system 14 and the temperature control system 16 are automatically started. The light source 6, the aperture 4, the detector 3, and the spring 2 begin to work together to measure the change of the spring 2 and the rotation angle of the stepper motor 12 when the mass of the sample 9 to be tested changes in real time. After the sample 9 to be tested completes the high-temperature and high-vacuum purification treatment (4 hours), the pyridine tube 11 is opened, and pyridine is adsorbed onto the sample 9 in the form of vapor. After the adsorption equilibrium is reached, the program heating and high-vacuum purification process are started. The desorption temperatures are 160°C, 250°C, 350°C, and 450°C, respectively. The constant temperature desorption is performed for 1 hour in each stage. The pyridine molecules are continuously desorbed and the sample mass change is measured in real time. During the whole determination process, the device automatically completes the determination and turns off the vacuum system 14 and the temperature control system 16. After the desorption process is completed, the acid content and acid strength distribution of the sample to be measured are calculated according to the mass change of the sample 9 to be measured before and after pyridine adsorption. The determination is performed 5 times respectively, and the results are shown in Table 1. The unit of acid strength is mmol / g.

[0054] Example 6

[0055] This example discloses a process for determining the surface acidity of a specific catalyst material using the apparatus and method of Examples 2 and 4:

[0056] (1) The stepper motor 12 is rotated by the program control system 15 to drive the moving bracket 5 to move, so that the light emitted by the light source 6 is irradiated to the infrared camera 17 through the slit in the center of the aperture 4 to form an image, and the program control system 15 records the image and the initial stepper motor 12 angle; (2) 0.2g of the hydrocracking catalyst sample 9 to be tested is added to the sample basket 8, and the determination program control system 15 is turned on, and the vacuum system 14 and the temperature control system 16 are automatically started. The light source 6, the aperture 4, the infrared camera 17, and the spring 2 start to work together to measure the change of the spring 2 and the rotation angle of the stepper motor 12 when the mass of the sample 9 to be tested changes in real time. After the sample 9 to be tested completes the high-temperature and high-vacuum purification treatment (4 hours), the pyridine tube 11 is opened, and pyridine is adsorbed on the sample 9 in the form of vapor. After the adsorption equilibrium is reached, the program heating and high-vacuum purification process are started. The desorption temperatures are 160°C, 250°C, 350°C, and 450°C, respectively. The constant temperature desorption is 1 hour in each stage, and the pyridine molecules are continuously desorbed and the sample mass change is measured in real time. During the whole determination process, the device automatically completes the determination and turns off the vacuum system 14 and the temperature control system 16. After the desorption process is completed, the acid content and acid strength distribution of the sample to be measured are calculated according to the mass change of the sample 9 to be measured before and after pyridine adsorption. The determination is performed 5 times respectively, and the results are shown in Table 2. The unit of acid strength is mmol / g.

[0057] Comparative Example 1

[0058] The acid strength of the same hydrocracking catalyst was measured using the traditional method for 5 times, and the errors were compared. The results are shown in Table 3, where the acid strength unit is mmol / g.

[0059] Table 1.

[0060]

[0061] Table 2.

[0062]

[0063] Table 3.

[0064]

Claims

1. A device for quantitatively determining the surface acidity of a material, characterized in that: The device comprises a hollow measuring tube, a spring suspended at the top is arranged inside the measuring tube, and an aperture and a sample basket are connected in sequence below the spring; a movable bracket is arranged outside the measuring tube in the horizontal direction of the aperture, one end of the movable bracket is a light source, and the other end is a detector or an infrared camera, the movable bracket is movably fixedly mounted on a guide rail driven by a stepper motor, and can be controlled by the stepper motor to move up and down on the guide rail so that the light source, the aperture and the detector or the infrared camera are located on the same horizontal straight line, and the detector or the infrared camera and the stepper motor are both externally connected to a program control system; a heating device is arranged around the sample basket, the heating device is arranged outside the measuring tube, a temperature detection device is arranged next to the sample basket, the heating device and the temperature detection device are both connected to the temperature control system outside the measuring tube, and the temperature control system is connected to the program control system; the measuring tube is also connected to an adsorption probe molecule tube and a vacuum system; Wherein, when a detector is installed at one end of the movable bracket, the movable bracket moves on the guide rail, and is controlled by the program control system so that the light intensity detected by the detector after each movement is consistent with that before, and the program control system records the angular rotation and direction information of the stepping motor during each movement, corresponding to the change in the length of the spring, and associated with the change in the weight of the sample in the sample basket; When an infrared camera is installed at one end of the movable bracket, the movable bracket moves on the guide rail and is controlled by the program control system to make the infrared image collected after each movement consistent. The program control system also records the angular rotation and direction information of the stepper motor during each movement, corresponding to the change in spring length, and associated with the change in sample weight in the sample basket.

2. The device according to claim 1, characterized in that The light source is a red laser light source.

3. The device according to claim 1, characterized in that The centers of the light source, the aperture and the detector or the infrared camera are on a horizontal line.

4. The device according to claim 1, characterized in that The measuring tube between the heating device and the sample basket is made of quartz glass, and the sample basket is made of quartz glass.

5. The device according to claim 1, characterized in that The heating device is a heating furnace; the temperature detection device is a thermocouple.

6. The device according to claim 1, characterized in that The adsorption probe molecular tube is a pyridine tube.

7. A method for quantitatively determining the surface acidity of a material using the device according to any one of claims 1 to 6, as follows: First, the stepper motor is rotated through the program control system to drive the moving bracket to move, so that the light emitted by the light source is irradiated onto the detector through the slit in the center of the aperture or formed on the infrared camera. The program control system records the light intensity or image, and records the initial stepper motor angle and spring length. When the sample to be tested is placed in the sample basket, the vacuum degree is adjusted through the vacuum system, the temperature is adjusted through the heating device, and the adsorption probe molecule tube is opened to allow the sample to adsorb the molecular probe, the spring is deformed due to the change in sample weight, the aperture position changes, and the light transmittance detected by the detector or the image on the infrared camera changes accordingly, and the change information is output to the program control system. In order to keep the light intensity or image consistent with the previous one, the program control system sends a rotation command to the stepper motor, converts the angle and direction of the stepper motor rotation into a change in the spring length, and then associates it with the sample weight and the change in weight, thereby obtaining the acidity information of the sample to be tested.

8. The method according to claim 7, characterized in that The specific steps of the determination are as follows: (1) The program control system rotates the stepper motor to drive the movable bracket to move, so that the light emitted by the light source passes through the slit in the center of the aperture and is irradiated onto the detector or imaged on the infrared camera. The program control system records the light intensity or image, and records the initial stepper motor angle and spring length; (2) A sample of a certain weight is placed in the sample basket. The spring becomes longer, the aperture position changes, and the light intensity detected by the detector or the image on the infrared camera changes. The change information is output to the program control system. In order to keep the light intensity or image consistent with the previous one, the program control system sends a rotation command to the stepper motor, converts the angle and direction of the stepper motor into a change in the spring length, and then associates it with the change in sample weight. (3) The vacuum degree is adjusted by the vacuum system, and the temperature is adjusted by the heating device. The sample is subjected to high-temperature and high-vacuum purification treatment. After purification, the temperature is lowered to room temperature. The program control system automatically records the rotation angle and direction of the stepper motor. The adsorption probe molecule tube is opened to allow the sample to adsorb the molecular probe. After adsorption equilibrium, the probe molecule adsorption tube is closed, and the programmed temperature rise and vacuum treatment are started to obtain the correlation information between the rotation angle and direction of the stepper motor and the change in sample weight under different temperatures and pressures, thereby obtaining quantitative acidity information of the sample under different measurement conditions. (4) After all temperature points are measured, the conversion relationship between spring length and sample weight is obtained based on the angle and direction data of the stepper motor rotation, and the acid content and acid strength distribution of the sample at different temperatures can be obtained.

9. The method according to claim 7, characterized in that: In step (3), after adsorption equilibrium is reached, the mass of the sample after adsorption of the probe molecule also changes continuously due to the constant change in temperature. The program control system controls the rotation of the stepper motor, uses the light source and detector or infrared camera to track the change in the aperture height, and converts the change in the spring length through the rotation angle and direction of the stepper motor. Therefore, the program control system needs to continuously change the angle output to the stepper motor to track the sample height. The programmed temperature rise should be maintained for a period of time at multiple preset temperature points so that the sample can reach the adsorption-desorption equilibrium state at the corresponding temperature, and then the motor rotation angle and direction at the corresponding temperature points are recorded respectively.

Images