Device for manometric gas-sorption analysis and for determining the solid density, and method using the device

Abstract

The invention relates to a device (1-1, 1-2) for manometric gas-sorption analysis and for determining the solid density of a material. The device (1-1, 1-2) comprises a temperature-controlled region (2), a dosing system, at least one calibrated dosing volume (3, 3a, 3b), a pressure-measuring system (4, 4a, 4b), which is connected to the calibrated dosing volume (3, 3a, 3b) and has at least one pressure sensor, and a connection (15) for connecting a gas-sorption measuring cell (20a), as well as the gas-sorption measuring cell (20a), which is releasably connected to the connection (15) and is intended for receiving a first sample (21a). The dosing system is formed with a dosing element (9a), an inert-gas connection (10), a measuring-gas connection (11) and a vacuum-pump connection (12). The at least one calibrated dosing volume (3, 3a) is connected to the connection (15) for connecting the gas-sorption measuring cell (20a). The device (1-1, 1-2) also comprises a density-measuring cell (20b) for receiving a second sample (21b). The density-measuring cell (20b) is connected to the at least one calibrated dosing volume (3, 3b). The at least one calibrated dosing volume (3, 3a, 3b) and the density-measuring cell (20b) are arranged within the temperature-controlled region (2). The invention also relates to a combined method of manometric gas-sorption analysis for characterizing a material and determining the solid density of the material using the device (1-1, 1-2).

Description

[0001] Device for manometric gas sorption testing and for determining solid density and method using the device

[0002] The invention relates to a device for manometric gas sorption testing and for determining the solid density of a material. The device comprises a temperature-controlled area, a dosing system, at least one calibrated dosing volume, and a pressure measurement system connected to the calibrated dosing volume. It also comprises a connection connected to the calibrated dosing volume for connecting a gas sorption measuring cell, and the gas sorption measuring cell is detachably connected to the connection. The invention also relates to a combined method of manometric gas sorption testing for characterizing a material and determining the solid density of the material using the device.

[0003] Solid surfaces are traditionally characterized using gas sorption. The associated investigations are usually based on a manometric measurement method, also known as a static-volumetric measurement method, and are carried out in gas sorption measuring instruments at pressures of less than 10' 8 bar up to the saturation vapor pressure of a probe molecule used. The largest possible measuring range is achieved with a measuring temperature at which the saturation vapor pressure corresponds to the maximum possible pressure of the gas sorption measuring device. The maximum possible pressure of the gas sorption measuring device is usually atmospheric pressure. This results in the boiling temperature of the probe molecule used as the measuring temperature. In the gas sorption measuring devices, which are designed as vacuum apparatuses, sorption isotherms are recorded, starting at a minimum pressure up to the saturation vapor pressure of the probe molecule, referred to as the measuring gas.

[0004] Due to its relative inertness and its easy and inexpensive availability compared to other gases, nitrogen has become the standard probe molecule for gas sorption measurements used to characterize solid surfaces. However, there are also findings that question the unconditional suitability of nitrogen for such investigations and ultimately led to a general recommendation for the use of the noble gas argon.

[0005] The advantage of argon over nitrogen lies in the property of the monatomic noble gas without a quadrupole moment, which reduces unwanted interactions between the solid surface and the adsorbed probe molecule, also called adsorbate for short.

[0006] The inert measurement gases, such as nitrogen or argon, act as probe molecules and interact reversibly with the surface of the sample material under investigation at cryogenic temperatures. In addition to nitrogen and argon, krypton, carbon dioxide, gaseous hydrocarbons, or vapors, such as water or alcohols, are used as measurement gases.

[0007] In sorption analysis using vapors, a temperature-controlled vessel containing liquid is usually used as the vapor source. This vessel is located within a temperature-controlled area of ​​the manometric gas sorption measuring device. Within the temperature-controlled area, a calibrated dosing volume and valves connected to the dosing volume are also arranged, for example, for filling with helium or sample gas and for creating a vacuum within the dosing volume. Furthermore, components for throttling the gas mass flow and additional valves can be provided, which are connected to the vessel containing liquid serving as the vapor source or to a gas sorption measuring cell containing a sample to be analyzed. The calibrated dosing volume is equipped with a pressure measuring system. The cooled gas sorption measuring cell is located outside the temperature-controlled area.

[0008] Such a gas sorption measuring device and a method for

[0009] Sorption tests are available from US 3 850 040 A.

[0010] To determine the adsorbed amount of a gas, in addition to the size of the calibrated dosing volume, the size of the free gas volume within the gas sorption measuring cell is also known, which depends on the geometry of the gas sorption measuring cell, the volume of the sample arranged within the gas sorption measuring cell and the attachment of the gas sorption measuring cell to the gas sorption measuring device.

[0011] During the test, the calibrated dosing volume and the free gas volume of the gas sorption cell are first evacuated and then filled, primarily with helium. After opening a valve located between the volumes, an equilibrium pressure is established. The known calibrated dosing volume and the measured gas pressures, at constant temperature, yield the free gas volume of the gas sorption cell containing the sample, which is required for calculating adsorbed amounts of substance. Helium occurs in atomic form, exhibits a minimal atomic diameter and high thermal conductivity, and hardly adsorbs on most materials near room temperature.

[0012] In addition to the precise determination of the free gas volume within the gas sorption cell using a gas sorption measuring device and thus the manometric gas sorption test, the sample volume and, if the sample mass is known, the sample density often also need to be determined. Gas pycnometers based on the Boyle-Mariotte law are known for determining the volume of solids or powdered or porous samples of independent geometric shapes. The solids to be measured displace the volume of a test gas within a density cell. The resulting difference in the volume of the test gas compared to the volume of the empty density cell or a reference chamber is measured.As with the gas sorption measuring device, helium is used as the test gas, since helium is known to hardly interact with solids, in particular it is only adsorbed to a negligible extent, and due to its minimal atomic diameter and weight it easily penetrates porous material.

[0013] Conventional gas pycnometers for determining sample volume and density measurement are disclosed, for example, in US 5 074 146 A and WO 2021 105 794 A1.

[0014] If the empty volume of the density measuring cell is known, the required sample volume is determined from the corresponding known volumes and the measured gas pressures using the gas equation for ideal or real gas and, with knowledge of the mass of the sample, the sample density.

[0015] To ensure high accuracy and reproducibility of measurements with a gas pycnometer, an optimal ratio of the dosing volume to the density cell volume is required, a temporally constant and spatially uniform temperature within the volumes and the test gas, and a closure of the density cell that limits the internal volume of the density cell to the same level after each closure. Furthermore, it is important to prevent sample entry into the dosing volume. For volume and density determination of solids using gas pycnometry, adsorption effects must be excluded to avoid measurement errors. In manometric gas sorption studies, such adsorption effects are quantified using a gas sorption measuring device.

[0016] Gas sorption measuring instruments are traditionally used, in particular, to examine porous materials with low sample mass. The calibrated dosing volume of the gas sorption measuring instrument and the volume of the gas sorption measuring cell, for example, each have values ​​of approximately 20 cm 3 while the volume of the samples to be examined is often less than 0.5 cm 3 These measurement conditions, optimized for gas sorption studies using porous materials, are unsuitable for density determination.

[0017] While for density determination using gas pycnometry, the two volumes are also of a similar size for optimized measurement accuracy, for example at 20 cm each 3 the mass of the sample must be maximized to minimize the measurement error of the density measurement. For this purpose, gas pycnometers often use density measuring cells with a volume in the range of 1 cm 3 up to 100 cm 3which are each optimized for the empty volume of the density measuring cell and filled to 60% to 80% with sample.

[0018] Manometric sorption analyzers for gas sorption tests are known from the state of the art. These analyzers can determine the volume and density of the sample. The density is determined at a sorption measuring station in a non-temperature-controlled glass gas sorption measuring cell, so the aforementioned factors for achieving high measurement accuracy and reproducibility cannot be met.

[0019] For a manometric gas sorption test and the determination of density using gas pycnometry, two separate analyzers, each with a gas supply, are traditionally used. Both devices share similar components and measurement methods. Using two separate analyzers requires a large footprint and requires a lot of space for the user, in addition to separate manufacturing.

[0020] It is known from the prior art to combine manometric gas sorption testing using a gas sorption measuring device with density determination using a gas pycnometer, as well as the associated analytical methods. In this case, a glass gas sorption measuring cell connected to the measuring station of the gas sorption measuring device is used for density measurement, and thus does not achieve the accuracy of a dedicated gas pycnometer. In particular, the density measurement results in unfavorable volume ratios between the dosing volume or the volume of the measuring cell and the sample volume, as well as unfavorable temperature conditions, since the dosing volume and the volume of the measuring cell are not or not completely uniformly temperature-controlled.In addition, glass measuring cells do not have design-related, precisely known internal volumes, since batch-dependent and individual deviations occur, for example due to deviations in wall thickness, so that for the different tests the identical measuring cell must be used firstly with a sample and secondly without a sample.

[0021] While gas pycnometers are designed with precision closures that allow for highly reproducible internal volumes after the density cell is closed, glass gas sorption measuring cells are inserted into a connection element of the gas sorption measuring device, and an O-ring is compressed over a sleeve on the outside of the gas sorption measuring cell by screwing a nut. The insertion depth of the glass gas sorption measuring cell and the deformation of the O-ring due to the contact pressure of the manually operated nut influence the internal volume of the gas sorption measuring cell, thus reducing the reproducibility and accuracy of the tests.The object of the present invention is to combine a gas sorption measuring device and a gas pycnometer in such a way that a method for gas sorption testing for material characterization and a method for determining the solid density of the material can be combined. The device should be simple in design and operation, require minimal space, and allow for various usage options. The method for gas sorption testing and for determining the solid density of the material should be possible without any loss of accuracy and reproducibility.

[0022] This object is achieved by a device according to the invention for manometric gas sorption testing and for determining the solid density of a material. The device comprises a temperature-controlled area maintained at a constant and homogeneous temperature, a dosing system, at least one calibrated dosing volume, a pressure measurement system connected to the calibrated dosing volume and comprising at least one pressure sensor, a connection for connecting a gas sorption measuring cell, and the gas sorption measuring cell detachably connected to the connection for receiving a first sample of the material to be tested. The detachable connection refers to the possibility of exchanging and changing the gas sorption measuring cell, which can be adapted to a specific sample of the material, particularly with regard to its internal volume.

[0023] The dosing system comprises at least a first dosing element, an inert gas connection for filling the device with an inert gas, a measuring gas connection for filling the device with a measuring gas, and a vacuum pump connection for connecting the device to a vacuum pump. The at least one calibrated dosing volume is connected to the connection for connecting the gas sorption measuring cell. According to the concept of the invention, the device is designed with a density measuring cell for receiving a second sample of the material to be analyzed. The density measuring cell is connected to the at least one calibrated dosing volume. Both the at least one calibrated dosing volume and the density measuring cell are arranged within the temperature-controlled area.

[0024] According to a first alternative embodiment of the invention, the device comprises a first calibrated dosing volume for the gas sorption test and a second calibrated dosing volume, separate from the first calibrated dosing volume, for determining the solid density of the material. The first calibrated dosing volume is connected to the gas sorption measuring cell via the connection, and the second calibrated dosing volume is connected to the density measuring cell. The calibrated dosing volumes each have their own pressure measurement system and are located within the temperature-controlled area.

[0025] According to a second alternative embodiment of the invention, a common calibrated dosing volume is provided for the gas sorption test and for determining the solid density of the material. The calibrated dosing volume is connected to the density measuring cell and, via the connection, to the gas sorption measuring cell.

[0026] The calibrated dosing volume for the gas sorption test as well as the calibrated dosing volume and the density measuring cell for determining the solid density or the calibrated dosing volume for the gas sorption test and determining the solid density as well as the density measuring cell are always at the same temperature due to their arrangement within the temperature-controlled area.

[0027] According to a further development of the invention, the dosing system is connected to the common calibrated dosing volume or to the first calibrated dosing volume and the second calibrated dosing volume, and is arranged within the temperature-controlled area. This makes all supply options for manometric gas sorption testing, such as introducing the inert gas and various measurement gases, generating a vacuum, and applying various dosing algorithms, available for solid density determinations using the temperature-controlled density measuring cell.

[0028] The gas sorption measuring cell is advantageously located outside the temperature-controlled area and can be heated to a specific measuring temperature, in particular to a temperature in the range from 77 K to room temperature, specifically to a temperature of 77 K, 87 K, 195 K, or 273 K. The gas sorption measuring cell can be cooled, in particular, with liquid nitrogen.

[0029] A volume enclosed by the temperature-controlled area of ​​the device and the components arranged within the temperature-controlled area can be designed to be temperature-controlled to a constant temperature, in particular within a temperature range of 15 °C to 50 °C. The temperature required for this is preferably regulated.

[0030] According to a preferred embodiment of the invention, the density measuring cell can be reproducibly closed with a closure element. The closure element is arranged outside the temperature-controlled area and is accessible from outside the device.

[0031] The density measuring cell is advantageously designed to accommodate a container with evaporable liquid as a vapor source for vapor sorption tests.

[0032] According to a further development of the invention, a shut-off valve is arranged in a connecting line between the at least one calibrated dosing volume and the density measuring cell. A bypass flow path with a shut-off valve and a second dosing element can be provided around the shut-off valve arranged in the connecting line between the at least one calibrated dosing volume and the density measuring cell.

[0033] The dosing element of the dosing system and / or the dosing element of the bypass flow path to the density measuring cell are preferably designed as a preset needle valve or a controllable proportional valve or a perforated orifice plate, each for dosing a gas mass flow flowing through.

[0034] A further advantage of the invention is that at least one shut-off valve is formed in a connecting line between the at least one calibrated dosing volume and the dosing system. The dosing system can have a shut-off valve in a connecting line to the inert gas connection and / or in a connecting line to the sample gas connection and / or in a connecting line to the vacuum pump connection. Furthermore, a shut-off valve can be formed in a connecting line between the at least one calibrated dosing volume and the connection for connecting the gas sorption measuring cell.

[0035] The object is also achieved by a combined method according to the invention of manometric gas sorption testing for characterizing a material and determining the solid density of the material using the device according to the invention.

[0036] In this case, the common calibrated dosing volume or the separate calibrated dosing volumes and the density measuring cell connected to the calibrated dosing volume are tempered to a uniform value. In addition, the uniform dosing system with the dosing element, the inert gas connection, the measuring gas connection and the vacuum pump connection is used for filling with an inert gas and a measuring gas as well as for evacuating the gas sorption measuring cell, the density measuring cell and the calibrated dosing volume or the calibrated dosing volumes. An advantage of the device according to the invention lies in the combination of the manometric gas sorption investigation and the determination of the solid density of a material with the common dosing system for supplying inert gas and measuring gas as well as for generating vacuum, but with separate calibrated dosing volumes and volumes of the

[0037] Gas sorption measuring cell and the density measuring cell.

[0038] By combining manometric gas sorption testing and determining the solid density of a material in a single device, the measurement results are determined with the same accuracy as with individual temperature-controlled devices. In particular, the density of the material is determined with the same accuracy as with a conventional, separate gas pycnometer. Thus, in addition to manometric gas sorption testing, the device also enables density measurements in a fully temperature-controlled environment optimized for density measurements, analogous to and with the same measurement accuracy as a separate, temperature-controlled gas pycnometer. In this process, all integrated and temperature-controlled components of the device are utilized.

[0039] This allows, in addition to manometric gas sorption tests, density measurements and special gas pycnometer tests to be carried out with all measuring gases available on the device and using the software options available in the device.

[0040] The device is compact and has a minimal footprint and installation space compared to individual devices.

[0041] Further details, features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Figure 1 shows a gas sorption measuring device for manometric

[0042] State-of-the-art gas sorption test with a dosing system and a pressure measuring system as well as a calibrated dosing volume and a gas sorption measuring device connected to the

[0043] Gas sorption measuring cell in schematic representation,

[0044] Figure 2: a gas pycnometer for determining the solid density from the state of the art with a pressure measuring system as well as a calibrated dosing volume and a density measuring cell connected to the gas pycnometer in a schematic representation and

[0045] Figures 3a and 3b: each show a first device for manometric gas sorption testing and for determining the solid density in a schematic representation and

[0046] Figure 4: a second device for manometric

[0047] Gas sorption investigation and determination of solid density with a common calibrated dosing volume in schematic representation.

[0048] Figure 1 shows a prior art gas sorption measuring device 1a' for manometric gas sorption testing. It has a temperature-controlled area 2a' in which a calibrated dosing volume 3a', also referred to as a manifold volume, a pressure measuring system 4a' with at least one pressure sensor, preferably several pressure sensors for different measuring ranges, and a dosing system are arranged. A gas sorption measuring cell 20a' is connected to the gas sorption measuring device 1a'. The gas sorption measuring device 1a' is used in particular for gas sorption tests with vapors.

[0049] The dosing system, which is connected to the calibrated dosing volume 3a' via shut-off valves 5a', 6a', 7a', 8a', also has dosing elements 9a' configured, for example, as a preset needle valve, a controllable proportional valve, or a perforated orifice plate. The dosing system is coupled to an inert gas connection 10a, a sample gas connection 11, and a vacuum pump connection 12 via a connecting line each with a first shut-off valve 5a', a second shut-off valve 6a', and a third shut-off valve 7a'. By opening one of the shut-off valves 5a', 6a', 7a' accordingly, the dosing system is connected, as required, to the inert gas connection 10a for introducing inert gas, in particular helium, the measuring gas connection 11 for introducing measuring gas into the gas sorption measuring device 1a' or the vacuum pump connection 12 for evacuating the gas sorption measuring device 1a'.

[0050] The dosing elements 9a' serve to fill the calibrated dosing volume 3a' with inert gas or sample gas as slowly and precisely as possible, or to evacuate it. Via a connecting line with a fourth shut-off valve 8a', the calibrated dosing volume 3a' is connected to a container 13 for receiving and storing liquid, which serves as a vapor source.

[0051] The calibrated dosing volume 3a' is connected to a connection 15 via a fifth shut-off valve 14a'. Connection 15 also has an enclosed connection volume, which results, among other things, from the internal volumes of connecting lines. The calibrated dosing volume can be, for example, 30 cm 3 while the connection volume is 10 cm 3 amounts.

[0052] The gas sorption measuring cell 20a', containing a sample 21a' to be analyzed, is connected to the gas sorption measuring device 1a' via connection 15. The cooled gas sorption measuring cell 20a' is located outside the temperature-controlled area 2a' of the gas sorption measuring device 1a'. Liquid nitrogen can be used to cool the gas sorption measuring cell 20a'. For the analysis, the sample gas is introduced sequentially and in a metered manner into the calibrated dosing volume 3a' through the sample gas connection 11, the second shut-off valve 6a', and the corresponding dosing element 9a' until a predetermined and precisely determined pressure is reached within the calibrated dosing volume 3a'. Subsequently, the fifth shut-off valve 14a' arranged in the connecting line between the calibrated dosing volume 3a' and the gas sorption measuring cell 20a' is opened.The internal volume of the gas sorption measuring cell 20a' is determined minus the volume of the sample 21a' arranged within the gas sorption measuring cell 20a' by means of a separate measurement with the gas sorption measuring device 1a' and is thus known.

[0053] By connecting the calibrated dosing volume 3a' to the internal volume of the gas sorption measuring cell 20a', the pressure within the calibrated dosing volume 3a' and within the gas sorption measuring cell 20a' is immediately equalized. Furthermore, the pressure inside the volumes decreases due to the adsorption of the probe molecules of the measurement gas on the solid surface of the sample 21a'. From the pressure reduction resulting from the adsorption of the probe molecules on the solid surface of the sample 21a', the amount of the measurement gas adsorbed by the sample 21a' is calculated using equations of state similar to the equation for ideal gases, with the aid of the measured temperatures and the material parameters.

[0054] Prior to such an investigation, the sample 21 a' to be investigated, located in the gas sorption measuring cell 20 a', is activated. The sample 21 a' is heated under vacuum to desorb volatile substances, such as water or solvent residues, from the solid surface of the sample 21 a' and to remove them from the gas sorption measuring cell 20 a' by means of the vacuum pump connected to the vacuum pump connection 12. The maximum temperatures during heating depend on the chemical composition of the sample 21 a' and can, for example, be less than 100 °C for sensitive materials and up to 600 °C for ceramic materials. The sample 21 a' to be investigated can be connected for activation either directly to the gas sorption measuring device 1 a' via connection 15, also referred to as "in situ," or to a separate activation station.

[0055] To determine the amount of a gas adsorbed by sample 21 a', the free gas volume V2a within the gas sorption measuring cell 20 a' must be known in addition to the calibrated dosing volume 3 a' with the volume V1 a. The free gas volume V2a within the gas sorption measuring cell 20 a' depends on the geometry of the gas sorption measuring cell 20 a', the volume of the sample 21 a', and the attachment of the gas sorption measuring cell 20 a' to the gas sorption measuring device 1 a'. The empty volume of the gas sorption measuring cell 20 a' can be known, at least approximately.

[0056] With the gas sorption measuring cell 20a' connected to the gas sorption measuring device 1a', the calibrated dosing volume 3a' and the free gas volume V2a within the gas sorption measuring cell 20a' are first evacuated. The third shut-off valve 7a' and the fifth shut-off valve 14a' are open. The vacuum pump is in operation when the third shut-off valve 7a' of the vacuum pump connection 12 is open. The first shut-off valve 5a' of the inert gas connection 10a and the second shut-off valve 6a' of the sample gas connection 11 are closed.

[0057] The calibrated dosing volume 3a' is then filled with inert gas, particularly helium, via the dosing system up to a gas pressure p1. The first shut-off valve 5a' of the inert gas connection 10a is open, while the second shut-off valve 6a' of the sample gas connection 11 and the third shut-off valve 7a' of the vacuum pump connection 12 are closed.

[0058] Subsequently, the fifth shut-off valve 14a' of connection 15, located between the calibrated dosing volume 3a' and the gas sorption measuring cell 20a', is opened, so that a lower, common equilibrium pressure p2 is established in the calibrated dosing volume 3a' and the free gas volume V2a within the gas sorption measuring cell 20a'. From the known volume V1a of the calibrated dosing volume 3a', the gas pressure p1, and the equilibrium pressure p2, the free gas volume V2a within the gas sorption measuring cell 20a' with the sample 21a' is determined at constant temperature, which serves to calculate the adsorbed amounts of substance.

[0059] Figure 2 shows a schematic representation of a prior art density measuring device 1b' for determining solid density, also referred to as a gas pycnometer. It includes a pressure measuring system 4b' with a pressure sensor, a calibrated dosing volume 3b', and a density measuring cell 20b' connected to the density measuring device 1b' and containing a sample 21b'. The gas pycnometer is used to determine the volume of the sample 21b' and, if the mass of the sample 21b' is known, also to determine the density of the sample 21b'.

[0060] The calibrated dosing volume 3b' with the volume V1 b and the density measuring cell 20b' with the inner volume V2b and the sample 21 b' arranged inside the density measuring cell 20b' with the volume VP2 are arranged within a temperature-controlled area 2b' of the density measuring device 1 b'.

[0061] The calibrated dosing volume 3b' is connected, on the one hand, to a gas supply, in particular a helium gas supply, via a connecting line to an inert gas connection 10b with a shut-off valve 5b' arranged in the connecting line. On the other hand, the calibrated dosing volume 3b' and the internal volume V2b of the density measuring cell 20b' are connected to one another via a connecting line to ensure pressure equalization between the calibrated dosing volume 3b' and the internal volume V2b of the density measuring cell 20b' if necessary. A shut-off valve 14b' and a dosing element 9b', which is preferably designed as a needle valve, controllable proportional valve, or perforated orifice, are arranged within the connecting line between the calibrated dosing volume 3b' and the density measuring cell 20b'. The dosing element 9b' serves to enable slow pressure equalization.

[0062] The density measuring cell 20b' has a closure element 16, which is opened for introducing the sample 21b' into the density measuring cell 20b' and removing the sample 21b' from the density measuring cell 20b'. The closure element 16 is designed to be reproducibly closable such that after each closing process, the internal volume V2b of the density measuring cell 20b' remains the same—apart from the volume VP2 of the sample 21b' arranged in the density measuring cell 20b'.

[0063] Via a further shut-off valve 17' connected to the density measuring cell 20b', the internal volume V2b of the density measuring cell 20b' and, when the shut-off valve 14b' is open, the calibrated dosing volume 3b' can be released to atmospheric pressure.

[0064] With known internal volume V2b as empty volume of the density measuring cell 20b' and the volume V1 b of the calibrated dosing volume 3b' as well as the corresponding measured gas pressures, the volume VP2 of the sample 21 b' is obtained by applying a gas equation for ideal or real gas and, with knowledge of the mass of the sample 21 b', the sample density.

[0065] The sequence for filling the density measuring device 1b' with inert gas is not predetermined, so that, for example, the calibrated dosing volume 3b' is filled to a pressure p1 with the shut-off valve 14b' closed, before the shut-off valve 14b' is opened to the internal volume V2b of the density measuring cell 20b', in order to subsequently determine the resulting equilibrium pressure p2. Likewise, the internal volume V2b of the density measuring cell 20b' could first be filled to the pressure p1 with the shut-off valve 14b' closed, before the shut-off valve 14b' is opened to the calibrated dosing volume 3b', in order to subsequently determine the resulting equilibrium pressure p2. However, in this case, the inert gas connection would be connected to the shut-off valve 14b', while the shut-off valve 5b' represents an outlet to the environment.

[0066] In Figures 3a and 3b, a first device 1-1 for manometric gas sorption testing and for determining the solid density of various materials is shown as a combination of a gas sorption measuring device and a density measuring device using a density measuring cell 20b for density measurement and as a vapor source for gas sorption testing.

[0067] A dosing system, a first calibrated dosing volume 3a with a first volume V1 a, a second calibrated dosing volume 3b with a second volume V1 b, and the density measuring cell 20b are arranged in a temperature-controlled area 2. Thus, the first device 1-1 as a complete system, with the exception of a gas sorption measuring cell 20a and only one closure element 16 of the density measuring cell 20b, can be fully temperature-controlled.

[0068] The dosing system serves to supply gas to and evacuate the first calibrated dosing volume 3a and the gas sorption measuring cell 20a connected to the first calibrated dosing volume 3a, as well as the second calibrated dosing volume 3b and the density measuring cell 20b connected to the second calibrated dosing volume 3b. The dosing system comprises a first shut-off valve 5a with an inert gas connection 10, in particular for supplying helium, a second shut-off valve 6a with a sample gas connection 11 for supplying sample gas, and a third shut-off valve 7a with a vacuum pump connection 12 for connecting a vacuum pump and for evacuation. This allows both the gas sorption measuring cell 20a and the density measuring cell 20b to be supplied with all gases available at the device 1-1 and with vacuum.To ensure the slowest and most precise filling with inert gas or sample gas, or evacuation of the calibrated dosing volumes 3a, 3b and in particular of the gas sorption measuring cell 20a, a first dosing element 9a for throttling the gas mass flow is provided in a connecting line between the shut-off valves 5a, 6a, 7a and the calibrated dosing volumes 3a, 3b. This first dosing element 9a is designed, in particular, as a needle valve, controllable proportional valve, or a perforated orifice plate. The dosing system with the inert gas connection 10, sample gas connection 11, and vacuum pump connection 12, which can be closed by means of the shut-off valves 5a, 6a, 7a, as well as the first dosing element 9a, can be separated on the media side from all other components of the device 1-1 via a first shut-off valve 18-1 of a valve arrangement.

[0069] The first calibrated dosing volume 3a is connected via a connecting line with a shut-off valve 14a and a connection 15 to the gas sorption measuring cell 20a, in which a first sample 21a to be analyzed is arranged. The gas sorption measuring cell 20a is arranged outside the temperature-controlled area 2 and can be cooled, for example, with liquid nitrogen. In order to determine the pressure within the first calibrated dosing volume 3a or the gas sorption measuring cell 20a, the first calibrated dosing volume 3a, also referred to as the manifold volume, is designed with a first pressure measuring system 4a, which has at least one pressure sensor, preferably several pressure sensors for different measuring ranges. The first calibrated dosing volume 3a and the gas sorption measuring cell 20a can be separated on the media side from all other components of the device 1-1 via a second shut-off valve 18-2 of a valve arrangement.

[0070] The second calibrated dosing volume 3b is connected via a connecting line with a shut-off valve 19 to a density measuring cell 20b, in which a second sample 21b to be examined is arranged. The density measuring cell 20b is arranged substantially within the temperature-controlled area 2. In order to determine the pressure within the second calibrated dosing volume 3b or the density measuring cell 20b, the second calibrated dosing volume 3b is designed with a second pressure measuring system 4b, which has at least one pressure sensor. Consequently, in addition to the at least one pressure sensor of the first pressure measuring system 4a, at least one additional, separate pressure sensor of the second pressure measuring system 4b is provided for determining the solid density. The second calibrated dosing volume 3b and the density measuring cell 20b can be separated on the media side from all other components of the device 1-1 via a third shut-off valve 18-3 of a valve arrangement.

[0071] The second calibrated dosing volume 3b is optimized to the requirements of the density measuring cell 20b with respect to a range of the volume of the second sample 21b to be measured. With the second calibrated dosing volume 3b, the device 1-1 has a second volume for density measurement that is separate from the first calibrated dosing volume 3a and also arranged within the temperature-controlled area 2. This second volume is accessible from the outside for introducing and removing the second sample 21b and is not connected to the connection 15 for coupling the gas sorption measuring cell 20a.

[0072] The density measuring cell 20b can be closed with the closure element 16. The closure element 16, which closes the density measuring cell 20b with excellent reproducibility via a spring-loaded bayonet lock and a seal compressed in the closing direction, is arranged outside the temperature-controlled area 2, so that the closure element 16 and thus the density measuring cell 20b are accessible from outside the device 1-1. With the seal compressed in the closing direction, the same contact pressure always achieves the same deformation of the seal, which ensures the very good reproducibility of the closing process.

[0073] The connecting line with the shut-off valve 19 arranged between the second calibrated dosing volume 3b and the density measuring cell 20b has a bypass flow path around the shut-off valve 19. The bypass flow path has a shut-off valve 14b and a second dosing element 9b, which is designed in particular as a needle valve, controllable proportional valve, or a perforated orifice plate, for throttling the gas mass flow. Throttling the gas mass flow causes a slow pressure equalization between the second calibrated dosing volume 3b and the density measuring cell 20b, thus preventing any possible turbulence of the second sample 21b.

[0074] The shut-off valve 19 arranged in the connecting line directly connecting the second calibrated dosing volume 3b and the density measuring cell 20b enables the two volumes to be connected without narrowing the flow cross-section and thus without throttling the gas mass flow. The shut-off valve 19 is opened in particular when the differential pressure within the second calibrated dosing volume 3b and the density measuring cell 20b is very low and pressure equalization through the bypass flow path with the second dosing element 9b would require too long a period of time. Furthermore, the shut-off valve 19 can be opened when the density measuring cell 20b according to Figure 3b is not used to measure the density of the second sample 21b, but rather as a vapor source for the gas sorption test, by inserting a container 21b-1 containing vaporizable liquid into the density measuring cell 20b.Thus, the density measuring cell 20b integrated into the device 1-1 can serve as a temperature-controlled liquid reservoir and vapor source for manometric vapor sorption tests. If the second dosing element 9b is designed as a proportional valve, the shut-off valve 19 can be omitted.

[0075] The dosing system, the first calibrated dosing volume 3a with the gas sorption measuring cell 20a and the second calibrated dosing volume 3b with the density measuring cell 20b are connected to each other via the valve arrangement with the shut-off valves 18-1, 18-2, 18-3.

[0076] The density measuring cell 20b integrated in the device 1-1 can be used to calibrate the dosing volumes 3a, 3b with the volumes V1a, V1b. Furthermore, by connecting the calibrated dosing volumes 3a, 3b by simultaneously opening the shut-off valves 18-2, 18-3 of the valve arrangement arranged between the calibrated dosing volumes 3a, 3b, a common, larger dosing volume can be provided. This can be particularly useful for gas sorption studies at low saturation vapor pressures, for example, with water vapor.

[0077] Figure 4 shows a second device 1-2 for manometric gas sorption testing and for determining the solid density of various materials as a combination of a gas sorption measuring device and a density measuring device using a density measuring cell 20b for density measurement and as a vapor source for gas sorption testing with a common calibrated dosing volume 3 and an associated pressure measuring system 4.

[0078] In contrast to the first device 1-1 from Figures 3a and 3b, the dosing system and only a calibrated dosing volume 3 are arranged within the temperature-controlled area 2. The dosing system with the inert gas connection 10, which can be closed by means of the shut-off valves 5a, 6a, 7a,

[0079] The sample gas connection 11 and vacuum pump connection 12, as well as the first dosing element 9a, can be separated from all other components of the device 1-2 on the media side via a shut-off valve 18. Identical components of the devices 1-1, 1-2 are identified by the same reference numerals. For the individual functions of the components, reference is made to the explanations for the device 1-1 shown in Figures 3a and 3b.

[0080] The size of the calibrated dosing volume 3 with the volume V1 and the size of the volume of the density measuring cell 20b with the internal volume V2b are matched to one another in such a way that the volume V1 of the calibrated dosing volume 3 numerically corresponds to the size of the calibrated dosing volume 3 assigned to the gas sorption measuring cell 20a with the free gas volume V2a, so that the calibrated dosing volume 3 with the pressure measuring system 4 serves both in conjunction with the gas sorption measuring cell 20a for the manometric gas sorption investigation of the first sample 21a and in conjunction with the density measuring cell 20b for determining the solid density of the second sample 21b.

[0081] LIST OF REFERENCE SYMBOLS

[0082] 1-1 , 1-2 device

[0083] 1a' Gas sorption measuring device

[0084] 1b' Density meter

[0085] 2, 2a', 2b' temperate area

[0086] 3, 3a, 3a (first) calibrated dosing volume

[0087] 3b, 3b' (second) calibrated dosing volume

[0088] 4, 4a, 4a' (first) pressure measuring system

[0089] 4b, 4b' (second) pressure measuring system

[0090] 5a, 5a', 5b' (first) shut-off valve

[0091] 6a, 6a' second shut-off valve

[0092] 7a, 7a' third shut-off valve

[0093] 8a' fourth shut-off valve

[0094] 9a, 9a' (first) dosing element

[0095] 9b, 9b' (second) dosing element

[0096] 10, 10a, 10b inert gas connection

[0097] 11 Sample gas connection

[0098] 12 Vacuum pump connection

[0099] 13 containers

[0100] 14a, 14b, 14a', 14b' (fifth) shut-off valve

[0101] 15 Connection

[0102] 16 locking element

[0103] 17' shut-off valve

[0104] 18, 18-1 , 18-2, 18-3 shut-off valve

[0105] 19 Shut-off valve

[0106] 20a, 20a' gas sorption measuring cell

[0107] 20b, 20b' density measuring cell

[0108] 21a, 21a' (first) rehearsal

[0109] 21 b, 21b' (second) rehearsal

[0110] 21 b-1 container

Claims

PATENT CLAIMS 1. Device (1-1, 1-2) for manometric gas sorption testing and for determining the solid density, comprising a temperature-controlled area (2), a dosing system, at least one calibrated dosing volume (3, 3a, 3b), a pressure measuring system (4, 4a, 4b) connected to the calibrated dosing volume (3, 3a, 3b) with at least one pressure sensor and a connection (15) for connecting a gas sorption measuring cell (20a) as well as the gas sorption measuring cell (20a) detachably connected to the connection (15) for receiving a first sample (21a), wherein - the dosing system comprises a dosing element (9a), an inert gas connection (10), a measuring gas connection (11) and a vacuum pump connection (12) and - the at least one calibrated dosing volume (3, 3a) is connected to the connection (15), characterized in that a density measuring cell (20b) is designed to receive a second sample (21b), wherein the density measuring cell (20b) is connected to the at least one calibrated dosing volume (3, 3b) and the at least one calibrated dosing volume (3, 3a, 3b) and the density measuring cell (20b) are arranged within the temperature-controlled area (2).

2. Device (1 -1 ) according to claim 1, characterized in that a first calibrated dosing volume (3a) for the gas sorption investigation and a second calibrated dosing volume (3b) for determining the solid density are formed, wherein the first calibrated dosing volume (3a) is connected via the connection (15) to the gas sorption measuring cell (20a) and the second calibrated dosing volume (3b) is connected to the density measuring cell (20b), wherein the calibrated dosing volumes (3a, 3b) are each connected to a pressure measuring system (4a, 4b) connected and arranged within the tempered area (2).

3. Device (1-2) according to claim 1, characterized in that a calibrated dosing volume (3) is designed for the gas sorption investigation and the determination of the solid density, wherein the calibrated dosing volume (3) is connected to the density measuring cell (20b) and via the connection (15) to the gas sorption measuring cell (20a).

4. Device (1 -1 , 1 -2) according to claim 2 or 3, characterized in that the dosing system - is connected to the uniform calibrated dosing volume (3) or to the first calibrated dosing volume (3a) and the second calibrated dosing volume (3b) respectively, and - is arranged within the temperate area (2).

5. Device (1-1, 1-2) according to one of claims 1 to 4, characterized in that the gas sorption measuring cell (20a) is arranged outside the temperature-controlled area (2) and is designed to be temperature-controlled to a specific measuring temperature, in particular to a temperature in the range from 77 K to room temperature, specifically to a temperature of 77 K, 87 K, 195 K or 273 K.

6. Device (1-1, 1-2) according to claim 5, characterized in that the gas sorption measuring cell (20a) is designed to be cooled with liquid nitrogen.

7. Device (1 -1, 1 -2) according to one of claims 1 to 6, characterized in that a volume enclosed by the tempered area (2) and the elements arranged within the tempered area (2) Components are designed to be tempered to a constant temperature, in particular in a temperature range of 15 °C to 50 °C.

8. Device (1-1, 1-2) according to one of claims 1 to 7, characterized in that the density measuring cell (20b) is designed to be reproducibly closable with a closure element (16), wherein the closure element (16) is arranged outside the temperature-controlled area (2) and is accessible from outside the device (1-1, 1-2).

9. Device (1-1, 1-2) according to one of claims 1 to 8, characterized in that the density measuring cell (20b) is designed to accommodate a container (21b-1) with evaporable liquid as a vapor source for vapor sorption tests.

10. Device (1-1, 1-2) according to one of claims 1 to 9, characterized in that a shut-off valve (19) is formed in a connecting line between the at least one calibrated dosing volume (3, 3b) and the density measuring cell (20b).

11. Device (1-1, 1-2) according to claim 10, characterized in that a bypass flow path is formed around the shut-off valve (19) arranged in the connecting line between the at least one calibrated dosing volume (3, 3b) and the density measuring cell (20b), wherein the bypass flow path has a shut-off valve (14b) and a dosing element (9b).

12. Device (1-1, 1-2) according to one of claims 1 to 11, characterized in that the metering element (9a, 9b) is designed as a preset needle valve or a controllable proportional valve or a perforated diaphragm for metering a gas mass flow flowing through.

13. Device (1-1, 1-2) according to one of claims 1 to 12, characterized in that at least one shut-off valve (18, 18-1, 18-2, 18-3) is formed in a connecting line between the at least one calibrated dosing volume (3, 3a, 3b) and the dosing system.

14. Device (1-1, 1-2) according to one of claims 1 to 13, characterized in that the dosing system has a shut-off valve (5a, 6a, 7a) in a connecting line to the inert gas connection (10) and / or in a connecting line to the measuring gas connection (11) and / or in a connecting line to the vacuum pump connection (12).

15. Device (1-1, 1-2) according to one of claims 1 to 14, characterized in that a shut-off valve (14a) is formed in a connecting line between the at least one calibrated dosing volume (3, 3a) and the connection (15).

16. Combined method of manometric gas sorption testing for characterizing a material and determining the solid density of the material with a device (1-1, 1-2) according to one of claims 1 to 15, characterized in that a calibrated dosing volume (3) or calibrated dosing volumes (3a, 3b) and a density measuring cell (20b) connected to the calibrated dosing volume (3, 3b) are tempered to a uniform temperature value and that a uniform dosing system with a dosing element (9a), an inert gas connection (10), a measuring gas connection (11) and a vacuum pump connection (12) for filling with an inert gas and a measuring gas and for evacuating a gas sorption measuring cell (20a), the density measuring cell (20b) and the calibrated dosing volume (3) or the calibrated dosing volumes (3a, 3b) is used.

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