A calorimetric device and method for studying and detecting catalyst storage stability

Abstract

The present invention discloses a calorimetric device and method for studying and detecting catalyst storage stability, belonging to the technical field of solid catalyst storage stability evaluation. The calorimetric device of the present invention includes an upper liquid storage cup, a lower liquid storage cup, a calorimetric cup, a first measuring pipe, a second measuring pipe, a first auxiliary pipe, a second auxiliary pipe, a third auxiliary pipe, and a flowmeter. The present invention also provides a method for studying and detecting catalyst storage stability using the calorimetric device. The calorimetric device for studying catalyst storage stability of the present invention has a simple structure and is easy to operate. It can not only study factors affecting catalyst storage stability, but also infer the storage time of the catalyst under certain conditions through quantitative calorimetric data.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid catalyst storage stability evaluation, and specifically relates to a calorimetric device and method for studying and detecting catalyst storage stability. The device and method can simulate and detect the heat release behavior of the catalyst during storage under different atmospheres, contents and temperature conditions. Background Art

[0002] Precious metal catalysts are a widely used class of catalytic materials, found in a variety of fields, including petrochemicals, automotive exhaust purification, and aerospace. However, due to their limited reserves and high cost, if the prepared catalysts are not used immediately, storage conditions, including the atmosphere and temperature, can irreversibly affect their properties. This is particularly true for catalysts used in aerospace and aviation, as they play a crucial role in assisting vehicles in achieving their intended orbits and often require prolonged storage. Therefore, studying their storage stability is crucial.

[0003] Precious metal catalysts are typically prepared by loading precious metal particles onto metal oxides to form a composite material. To improve the dispersion of the precious metal, specific preparation methods are typically used to minimize the size of the metal particles (less than a few nanometers). This results in a coordinatively unsaturated surface, making it susceptible to the slow absorption of small molecules such as oxygen, CO₂, and water vapor that may be present in the environment. This process results in the generation of heat, which can lead to changes in the active metal structure of the catalyst (such as changes in particle size, morphology, and exposed crystal faces) and alter the valence state of the metal particles. Currently, there is a lack of effective analytical methods to determine the influence of storage atmosphere and temperature on the storage stability of catalysts. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a calorimetric device and method capable of studying and detecting the storage stability of a catalyst.

[0005] The present invention is based on taking into account that during storage, within a certain time, under different storage conditions, the catalyst may interact with the small molecules in the storage environment to produce different heat, and the size of the heat generated may be directly related to the storage stability of the catalyst. If the catalyst is placed in a highly sensitive heat flow calorimeter, within a certain time (several days to several months), by certain intensive tests (changing temperature, atmosphere, etc.), the cumulative heat release of the catalyst is detected, on the one hand, the key factors (atmosphere, temperature, etc.) affecting the stability of the catalyst can be determined, on the other hand, if the cumulative heat release is compared with a certain standard index calorific value, it is possible to determine how long the catalyst can be stably stored under certain conditions, for catalyst storage provides a quantitative judgment basis. Therefore, the present invention, by establishing a calorimetric device and method for studying and detecting the storage stability of the catalyst, can simulate different storage atmospheres and temperatures, and realize thermodynamic judgment on the storage stability of the catalyst.

[0006] The specific technical solutions of the present invention are as follows:

[0007] A calorimetric device for studying and detecting the storage stability of a catalyst, the calorimetric device comprising a cylindrical upper liquid storage cup 1, a cylindrical lower liquid storage cup 2, a cylindrical calorimetric cup 3, a first measuring pipe 4, a second measuring pipe 5, a first auxiliary pipe 6, a second auxiliary pipe 7, a third auxiliary pipe 8 and a flow meter 9, wherein the cylindrical upper liquid storage cup 1, the cylindrical lower liquid storage cup 2 and the cylindrical calorimetric cup 3 are coaxially arranged in sequence from top to bottom; one end of the first measuring pipe 4 is connected to the flow meter 9, and the other end passes through the top of the cylindrical upper liquid storage cup 1, the cylindrical lower liquid storage cup 2 and the cylindrical calorimetric cup 3, and the outlet is located in the lower half (near the bottom) of the cylindrical calorimetric cup 3; one end of the second measuring pipe 5 is connected to the flow meter 9, and the other end passes through the cylindrical upper liquid storage cup 1, the cylindrical lower liquid storage cup 2 and the cylindrical calorimetric cup 3. Cup 1, the outlet is located in the upper half of the cylindrical upper liquid storage cup 1 (near the top); one end of the first auxiliary pipe 6 passes through the bottom of the cylindrical lower liquid storage cup 2, the outlet is located in the upper half of the cylindrical lower liquid storage cup 2, and the other end passes through the top of the cylindrical calorimetric cup 3, the outlet is located in the lower half of the cylindrical calorimetric cup 3 (near the bottom); the second auxiliary pipe 7 passes through the top of the cylindrical upper liquid storage cup 1, the cylindrical lower liquid storage cup 2, and the cylindrical calorimetric cup 3, one end is located at the top of the cylindrical calorimetric cup 3, and the other end is connected to the chromatograph or mass spectrometer; the third auxiliary pipe 8 connects the cylindrical upper liquid storage cup 1 and the cylindrical lower liquid storage cup 2, and the outlets at both ends are respectively located in the upper half of the cylindrical upper liquid storage cup 1 and the upper half of the cylindrical lower liquid storage cup 2.

[0008] Furthermore, the cylindrical upper liquid storage cup 1, the cylindrical lower liquid storage cup 2, the cylindrical calorimetric cup 3, the first measuring pipe 4, the second measuring pipe 5, the first auxiliary pipe 6, the second auxiliary pipe 7 and the third auxiliary pipe 8 of the calorimetric device are all made of stainless steel.

[0009] Furthermore, O-rings are used to seal the liquid storage cup, the calorimetric cup and the pipeline, which facilitates assembly and disassembly.

[0010] Another aspect of the present invention provides a method for studying and detecting the storage stability of a catalyst, the main process of which is to use the above-mentioned calorimetric device to study and detect the storage stability of the catalyst.

[0011] Furthermore, the effect of different humidity on the storage stability of the catalyst was studied, which mainly included the following steps: the catalyst was placed at the bottom of a cylindrical calorimetric cup 3, water was injected into the cylindrical upper liquid storage cup 1 and the cylindrical lower liquid storage cup 2, and the liquid level of the water was controlled within half the volume of the liquid storage cup, and then high-purity inert gas was introduced into the calorimetric cup 3 through the first measuring pipe 4 and the second measuring pipe 5 respectively, and the gas flow rate in the first measuring pipe 4 and the second measuring pipe 5 was controlled by a flowmeter 9 to obtain gases with different humidity, and the heat released during the storage process of the catalyst under gases with different humidity was measured to study the effect of different humidity on the storage stability of the catalyst.

[0012] Furthermore, the inert gas in the first measuring pipe 4 and the second measuring pipe 5 is Ar or N2, and the gas flow rate is set below 200 mL / h.

[0013] Furthermore, the influence of different contents of single gas on the storage stability of the catalyst is studied, which mainly includes the following steps: the catalyst is placed at the bottom of the cylindrical calorimetric cup 3, the cylindrical upper liquid storage cup 1 and the cylindrical lower liquid storage cup 2 are empty, and the single gas to be studied and the inert gas are respectively introduced through the first measuring pipe 4 and the second measuring pipe 5, and the gas flow rate in the first measuring pipe 4 and the second measuring pipe 5 is controlled by the flow meter 9 to achieve the introduction of different contents of the gas to be studied, and then the heat generated by the catalyst when different contents of single gas pass through is measured by the calorimeter to study the influence of different contents of single gas on the storage stability of the catalyst.

[0014] Furthermore, the single gas in the first measuring pipe 4 is O2 or CO2, the inert gas in the second measuring pipe 5 is Ar or N2, and the gas flow rates are both set below 200 mL / h.

[0015] Furthermore, the influence of mixed atmospheres with different proportions on the storage stability of the catalyst was studied, which mainly included the following steps: the catalyst was placed at the bottom of the cylindrical calorimetric cup 3, the cylindrical upper liquid storage cup 1 and the cylindrical lower liquid storage cup 2 were empty, different gases to be studied were introduced through the first measuring pipe 4 and the second measuring pipe 5 respectively, the gas flow rate in the first measuring pipe 4 and the second measuring pipe 5 was controlled by the flowmeter 9 to realize the introduction of mixed gases with different contents, and then the heat generated by the catalyst when mixed gases with different proportions passed through was measured by the calorimeter to study the influence of mixed atmospheres with different proportions on the storage stability of the catalyst.

[0016] Furthermore, the gas in the first measuring pipe 4 is O2, the gas in the second measuring pipe 5 is CO2, and the gas flow rates are both set below 200 mL / h.

[0017] The present invention has the following beneficial effects compared to the prior art:

[0018] 1. The calorimetric device of the present invention can be used in conjunction with heat flow calorimeters produced by different companies to achieve calorimetric research on the storage stability of solid catalysts.

[0019] 2. The calorimetric device of the present invention can be used to study factors affecting the storage stability of solid catalysts based on heat release behavior, and to estimate the storage life of the catalyst based on the heat release.

[0020] 3. The calorimetric device of the present invention has simple operating steps and can simulate storage environments with different gas compositions to study the effects on catalyst storage stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments are briefly introduced below.

[0022] Figure 1 Schematic diagram of a calorimetric device for studying and detecting catalyst storage stability provided by the present invention, wherein: 1: cylindrical upper liquid storage cup, 2: cylindrical lower liquid storage cup, 3: cylindrical calorimetric cup, 4: first measuring pipe, 5: second measuring pipe, 6: first auxiliary pipe, 7: second auxiliary pipe, 8: third auxiliary pipe, 9: flow meter, 10: water, 11: catalyst;

[0023] Figure 2 2. The graph comparing the heat release of the sample (b) loaded with 200 mg of Ir / Al2O3 catalyst and the sample (a) without loading under different oxygen content conditions in Example 3;

[0024] Figure 3 The figure is a comparison of the heat released after oxygen is introduced during the storage of the catalyst at different temperatures in Example 4. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the embodiments, but the embodiments of the present invention are not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments obtained without creative work all fall within the scope of protection of the present invention.

[0026] Example 1

[0027] A calorimetric device for studying and testing the storage stability of catalysts, such as Figure 1As shown, the calorimetric device includes a cylindrical upper liquid storage cup 1, a cylindrical lower liquid storage cup 2, a cylindrical calorimetric cup 3, a first measuring pipe 4, a second measuring pipe 5, a first auxiliary pipe 6, a second auxiliary pipe 7, a third auxiliary pipe 8 and a flow meter 9. The cylindrical upper liquid storage cup 1, the cylindrical lower liquid storage cup 2 and the cylindrical calorimetric cup 3 are coaxially arranged from top to bottom; one end of the first measuring pipe 4 is connected to the flow meter 9, and the other end passes through the top of the cylindrical upper liquid storage cup 1, the cylindrical lower liquid storage cup 2 and the cylindrical calorimetric cup 3, and the outlet is located in the lower half (near the bottom) of the cylindrical calorimetric cup 3; one end of the second measuring pipe 5 is connected to the flow meter 9, and the other end passes through the top of the cylindrical upper liquid storage cup 1, and the outlet is located in the upper half (near the top) of the cylindrical upper liquid storage cup 1; one end of the first auxiliary pipe 6 passes through the cylindrical The bottom of the cylindrical lower liquid storage cup 2 has an outlet located in the upper half of the cylindrical lower liquid storage cup 2, and the other end passes through the top of the cylindrical calorimetric cup 3, with an outlet located in the lower half (near the bottom) of the cylindrical calorimetric cup 3. A second auxiliary pipe 7 passes through the tops of the cylindrical upper liquid storage cup 1, the cylindrical lower liquid storage cup 2, and the cylindrical calorimetric cup 3, with one end located at the top of the cylindrical calorimetric cup 3 and the other end connected to a chromatograph or mass spectrometer. A third auxiliary pipe 8 connects the cylindrical upper liquid storage cup 1 and the cylindrical lower liquid storage cup 2, with outlets at both ends located in the upper half of the cylindrical upper liquid storage cup 1 and the upper half of the cylindrical lower liquid storage cup 2, respectively. The first measuring pipe 4 and the second measuring pipe 5 of the calorimetric device are connected to a flow meter 9, through which gases of different compositions are introduced. The second auxiliary pipe 7 is connected to a chromatograph or mass spectrometer for detecting exhaust gas. The liquid storage cup, calorimetric cup, and pipes of the calorimetric device are all made of stainless steel, and O-rings are used to seal the pipes, liquid storage cups, and calorimetric cups for easy loading and unloading.

[0028] Example 2

[0029] The following will provide a detailed introduction to this device in conjunction with a schematic diagram of a calorimetric device for studying and detecting catalyst storage stability.

[0030] When studying the effect of different humidity levels on catalyst storage stability, water was injected into the cylindrical upper liquid storage cup 1 and the cylindrical lower liquid storage cup 2, with the water level controlled to be within half the volume of the liquid storage cup. 200 mg of catalyst sample was weighed and placed in the cylindrical calorimetric cup 3. The calorimetric device was then placed in the calorimeter. After the heat flow signal stabilized, high-purity inert gas (N2 or Ar gas) was introduced into the cylindrical calorimetric cup 3 through the first measuring pipe 4 and the second measuring pipe 5, respectively. By controlling the flow rates of the two gases at different levels, mixed gases with different humidity levels could be obtained. The calorimeter detected the heat release during the storage of the catalyst under different humidity levels.

[0031] When studying the effect of different contents of a single gas on the storage stability of the catalyst, the cylindrical upper liquid storage cup 1 and the cylindrical lower liquid storage cup 2 are emptied, 200 mg of catalyst is weighed and placed in the calorimetric cup, and then the calorimetric device is placed in the calorimeter. After the heat flow signal stabilizes, inert gases (N2 and Ar gas) are introduced through the first measuring pipe 4, and the gas to be studied (such as O2 or CO2, etc.) is introduced through the second measuring pipe 5. Different flow rates are controlled by the flow meter 9 to achieve the introduction of different contents of the gas to be studied. The calorimeter measures the heat generated by the catalyst when different contents of the single gas pass through.

[0032] When studying the effect of mixed atmospheres of different proportions on the storage stability of the catalyst, when the effect of water vapor is not measured, the cylindrical upper liquid storage cup 1 and the cylindrical lower liquid storage cup 2 are left empty, 200 mg of catalyst is weighed and placed in the calorimetric cup, the calorimetric device is placed in the calorimeter, and different gases to be studied (such as O2 or CO2, etc.) are introduced through the first measuring pipe 4 and the second measuring pipe 5 respectively. The different flow rates of the two are controlled by the flow meter 9 to achieve the introduction of mixed gases of different proportions. When studying and measuring the effect of a mixed atmosphere containing water vapor on the storage stability of a catalyst, water is injected into the cylindrical upper liquid storage cup 1 and the cylindrical lower liquid storage cup 2, with the water level controlled to within half the volume of the liquid storage cup. A 200mg catalyst sample is weighed and placed in the calorimetric cup. The calorimetric device is then placed in the calorimeter. After the heat flow signal stabilizes, the gas to be studied (such as O2 or CO2) is introduced through the first measuring conduit 4, and a high-purity inert gas (N2 or Ar) is introduced into the calorimetric cup through the second measuring conduit 5. By controlling the flow rates of the two gases, a mixed gas containing water vapor can be achieved. The heat generated by the catalyst when different proportions of mixed gases pass through it is then measured using the calorimeter.

[0033] From this embodiment, it can be seen that the calorimetric device of the present invention has the advantages of simple structure, convenient operation, easy use and maintenance, etc.

[0034] Example 3

[0035] The calorimetric device provided by the present invention was used to measure the heat release under conditions of no sample and sample loading, respectively. First, the heat release of the calorimetric device without sample was measured after the atmosphere was introduced. The specific process is: the upper liquid storage cup 1, the lower liquid storage cup 2 and the calorimetric cup 3 of the calorimetric device are emptied, and high-purity N2 and O2 are introduced through the first measuring pipe 4 and the second measuring pipe 5, respectively. The flow rate of the flow meter connecting the first measuring pipe 4 and the second measuring pipe 5 is adjusted so that the O2 content is 20% and 100%, respectively. The heat release of gases with different contents is detected by the calorimeter. In order to test whether this heat release is reversible, when the heat flow signal is stable, the O2 gas is turned off and only N2 is introduced. It can be seen that an endothermic peak appears in the N2 atmosphere, which can be attributed to the desorption of O2 on the metal wall (such as Figure 2As shown in Figure a), after 20% and 100% O₂ / N₂ mixtures are introduced into the empty tube, equilibrium is reached within 2-3 hours, generating 8.8 mJ and 28.1 mJ of heat, respectively. The corresponding desorption heat releases are 9.0 mJ and 28.3 mJ, indicating that O₂ adsorption on the calorimetric cup wall is reversible.

[0036] The experimental process of loading samples is as follows: 200 mg of Ir / Al2O3 solid catalyst is placed in the calorimetric cup 3 of the calorimetric device, and then the calorimetric device is placed in the calorimeter. After the heat flow signal stabilizes, high-purity N2 and O2 are introduced through the first measuring pipe 4 and the second measuring pipe 5 respectively. The flow rate of the flow meter connecting the first measuring pipe 4 and the second measuring pipe 5 is adjusted so that the O2 content is 10%, 15%, 20% and 50% respectively. The heat released by the catalyst in the presence of the above-mentioned oxygen content is detected by the calorimeter. Figure 2 As shown in Figure b, compared with the empty tube test, in the catalyst sample group, the adsorption time reaches 1-2 days after the oxygen-containing gas is introduced, and the heat released is 2-3 orders of magnitude of that in the empty tube test, indicating that the heat released is mainly due to the adsorption and aging of oxygen on the catalyst.

[0037] The heat generated by irreversible adsorption (i.e., the irreversible interaction between oxygen and the catalyst) was calculated based on the heat released and absorbed. The results are shown in Table 1. It can be clearly seen that there is no obvious linear relationship between the heat generated on the catalyst and the oxygen content, indicating that only a small amount of oxygen can have a significant impact on the storage of the catalyst in the storage environment.

[0038] Table 1. Absolute heat generated by different oxygen contents

[0039]

[0040] Example 4

[0041] Study the effect of temperature on storage heat storage: Temperature is usually an important factor affecting the storage stability of catalysts. This example studies the difference in heat release aging during catalytic storage at different temperatures under the same atmosphere. First, place 200 mg of Ir / Al2O3 sample in the calorimetric cup 3 of the calorimetric device, and introduce high-purity N2 and O2 through the first measuring pipe 4 and the second measuring pipe 5 respectively. Adjust the flow rate of the flowmeter connecting the first measuring pipe 4 and the second measuring pipe 5 so that the O2 content is fixed at 21% under each temperature condition. Then set the test temperature to 25, 80 and 120 ° C respectively through the calorimeter, and then detect the difference in heat release of the Ir / Al2O3 catalyst under these temperature conditions. The results are as follows. Figure 3As shown in the figure, at 25℃, the heat release of the catalyst reaches 760mJ / day. As the temperature increases, the heat release on the catalyst decreases, indicating that at a certain temperature, the aging heat release of O2 on the catalyst is suppressed. As the temperature exceeds 80℃, the aging heat release of O2 on the catalyst increases, indicating that at higher temperatures, the degree of oxidation aging of the catalyst will gradually increase during storage.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A calorimetric device for studying and detecting the storage stability of catalysts, characterized in that: The calorimetric device comprises an upper liquid storage cup, a lower liquid storage cup, a calorimetric cup, a first measuring pipe, a second measuring pipe, a first auxiliary pipe, a second auxiliary pipe, a third auxiliary pipe and a flow meter. The upper liquid storage cup, the lower liquid storage cup and the calorimetric cup are coaxially arranged from top to bottom. One end of the first measuring pipe is connected to the flow meter, and the other end passes through the top of the upper liquid storage cup, the lower liquid storage cup and the calorimetric cup, and the outlet is located in the lower half of the calorimetric cup. One end of the second measuring pipe is connected to the flow meter, and the other end passes through the top of the upper liquid storage cup, and the outlet is located in the lower half of the calorimetric cup. The outlet is located in the upper half of the upper liquid storage cup; one end of the first auxiliary pipe passes through the bottom of the lower liquid storage cup, and the outlet is located in the upper half of the lower liquid storage cup, and the other end passes through the top of the calorimetric cup, and the outlet is located in the lower half of the calorimetric cup; the second auxiliary pipe passes through the upper liquid storage cup, the lower liquid storage cup, and the top of the calorimetric cup, one end is located at the top of the calorimetric cup, and the other end is connected to the chromatograph or mass spectrometer; the third auxiliary pipe connects the upper liquid storage cup and the lower liquid storage cup, and the outlets at both ends are respectively located in the upper half of the upper liquid storage cup and the upper half of the lower liquid storage cup.

2. The calorimetric device according to claim 1, characterized in that The upper liquid storage cup, the lower liquid storage cup and the calorimetric cup are all cylindrical in shape; the upper liquid storage cup, the lower liquid storage cup, the calorimetric cup, the first measuring pipe, the second measuring pipe, the first auxiliary pipe, the second auxiliary pipe and the third auxiliary pipe are all made of stainless steel.

3. The calorimetric device according to claim 1, characterized in that The liquid storage cup, calorimetric cup and pipeline are sealed with O-rings.

4. A method for studying and detecting the storage stability of a catalyst, characterized in that: The main process of the research and detection method is to use the calorimetric device described in any one of claims 1-3 to study and detect the storage stability of the catalyst.

5. The research and detection method according to claim 4, characterized in that The study of the effect of different humidity on the storage stability of the catalyst mainly includes the following steps: the catalyst is placed at the bottom of the calorimetric cup, water is injected into the upper and lower liquid storage cups, and the liquid level of the water is controlled within half the volume of the liquid storage cups. Then, high-purity inert gas is introduced into the calorimetric cup through a first measuring pipe and a second measuring pipe, respectively. The gas flow rate in the first measuring pipe and the second measuring pipe is controlled by a flow meter to obtain gases with different humidity. The heat released during the storage process of the catalyst under gases with different humidity is measured to study the effect of different humidity on the storage stability of the catalyst.

6. The research and detection method according to claim 5, characterized in that The inert gas in the first measuring pipe and the second measuring pipe is Ar or N2, and the gas flow rate is set below 200 mL / h.

7. The research and detection method according to claim 4, characterized in that The study of the effect of different single gas contents on the storage stability of the catalyst mainly includes the following steps: placing the catalyst at the bottom of the calorimetric cup, leaving the upper liquid storage cup and the lower liquid storage cup empty, introducing the single gas to be studied and the inert gas through the first measuring pipe and the second measuring pipe respectively, controlling the gas flow rate in the first measuring pipe and the second measuring pipe by a flow meter to achieve the introduction of different contents of the gas to be studied, and then measuring the heat generated by the catalyst when different contents of the single gas pass through it by a calorimeter to study the effect of different contents of the single gas on the storage stability of the catalyst.

8. The research and detection method according to claim 7, characterized in that The single gas in the first measuring pipe is O2 or CO2, and the inert gas in the second measuring pipe is Ar or N2. The gas flow rates are all set below 200 mL / h.

9. The research and detection method according to claim 4, characterized in that The study of the effects of mixed atmospheres of different proportions on the storage stability of the catalyst mainly includes the following steps: placing the catalyst at the bottom of the calorimetric cup, leaving the upper and lower liquid storage cups empty, introducing different gases to be studied through the first measuring pipe and the second measuring pipe respectively, controlling the gas flow rate in the first measuring pipe and the second measuring pipe by a flow meter to achieve the introduction of mixed gases of different contents, and then measuring the heat generated by the catalyst when mixed gases of different proportions pass through the calorimeter to study the effects of mixed atmospheres of different proportions on the storage stability of the catalyst.

10. The research and detection method according to claim 9, characterized in that The gas in the first measuring pipe is O2, and the gas in the second measuring pipe is CO2, and the gas flow rates are both set below 200 mL / h.

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