Filtering device for gas produced by temperature programmed reduction instrument

Abstract

The utility model discloses a filtering device for gas produced by a temperature programmed reduction instrument. The filtering device is a U-shaped quartz filtering pipe; a molecular sieve is arranged in the U-shaped quartz filter tube; the U-shaped quartz filter tube comprises a gas inlet end and a gas outlet end; the gas inlet end is connected with a gas outlet end of a sample tube in the temperature programmed reduction instrument; and the gas outlet end is connected with the gas inlet end of a detector in the temperature programming reduction instrument. An original cold trap ring on a programmed heating reduction instrument is replaced by a U-shaped quartz filter tube, molecular sieve pellets and a proper amount of allochroic silica gel pellets are arranged in two sections in the U-shaped quartz filter tube, and impurity gases such as H2O, HCl, H2S, CH4 and CO2 generated in the programmed heating hydrogen reduction process can be effectively adsorbed. The molecular sieve and allochroic silicagel can be activated and regenerated in an in-situ heating mode, operation is convenient, and cost is saved.

Description

Technical Field

[0001] The present application relates to a filtering device for gas produced by a programmed temperature reduction instrument, and belongs to the technical field of experimental equipment. Background Art

[0002] Existing technology: The existing technology is cold trap freezing technology, that is, liquid nitrogen is used to assist isopropanol in cooling to become a refrigerant. A cold trap ring (or a symmetrical U-shaped quartz cold trap tube) surrounded by metal pipelines is immersed in a refrigerant to form a cold trap. When the catalyst is subjected to a programmed temperature increase hydrogen reduction reaction, the H2O produced will be frozen along with the carrier gas flowing through the cold trap ring to avoid interference with the TCD detector signal. This method has many disadvantages.

[0003] 1. High operation requirements.

[0004] Pouring liquid nitrogen into isopropanol and stirring it requires skill. Pour slowly and stir quickly to prevent the isopropanol on the top from freezing rapidly and being unable to be stirred, while the isopropanol on the bottom is still flowing, forming a large temperature difference. The final state of the isopropanol solid-liquid mixture affects the freezing effect. Generally, the more liquid nitrogen poured in, the lower the temperature of the mixture, the better the freezing effect, and the longer the freezing time. If too much liquid nitrogen is poured in, the mixture will be too hard, which will make it difficult to insert the cold trap ring / tube.

[0005] 2. Impact on data reliability

[0006] Existing technology mainly filters H2O, while gases such as HCl, H2S, CH4, and CO2 have high boiling points and cannot be frozen by cold traps, which affects the TCD detection signal and reduces data reliability. In addition, long-term corrosion by corrosive gases such as HCl and H2S will reduce the life of the TCD detector.

[0007] 3. Poor effectiveness

[0008] The freezing effect of the prior art on H2O is affected by the temperature of the isopropanol solid-liquid mixture. The higher the temperature of the mixture, the worse the freezing effect on H2O. And as the placement time increases, the temperature of isopropanol gradually increases. From practical experience, it can be seen that the ice-slush-like isopropanol solid-liquid mixture has a better freezing effect on water vapor within 1 hour, and the effective freezing time of non-ice-slush-like mixtures will be shortened. In addition, if some faults are encountered during the test, the baseline of the instrument TCD detector is unstable, or the instrument flow error is reported, etc., manual processing is required. In this process, the freezing effect of isopropanol will decrease due to excessive placement time.

[0009] 4. Time-consuming and laborious

[0010] The prior art requires that during each test, an isopropyl alcohol solid-liquid mixture be prepared according to the program nodes, and the tester needs to return to the test site on time. Usually, it takes 20-40 minutes to prepare the ice slush-like isopropyl alcohol solid-liquid mixture.

[0011] 5. Harmful to the human body

[0012] In the prior art, when stirring the isopropyl alcohol solid-liquid mixture, it is necessary to wear goggles and gloves to prevent the liquid nitrogen from freezing the eyes and hands, and to wear a filter mask to prevent the isopropyl alcohol (a mildly toxic substance) from being inhaled into the nose and mouth.

[0013] 6. High cost

[0014] Isopropyl alcohol and liquid nitrogen are used in large quantities, increasing testing costs. Utility Model Content

[0015] The catalyst can release a variety of gases during the programmed temperature hydrogen reduction process. First, hydrogen can reduce metal oxides, chlorides, and sulfides to generate a large amount of H2O and a small amount of corrosive gases HCl and H2S. Secondly, under the catalysis of precious metals, hydrogen reacts with carbon species adsorbed on the catalyst surface to produce CH4 gas. In addition, the thermal decomposition of carbonates and the thermal desorption of CO2 adsorbed in the pores of the carrier will also produce CO2 gas. By effectively removing these gases, the hydrogen consumption of the catalyst can be accurately quantified and the data reliability can be improved. In addition, the removal of corrosive gases can ensure the good sensitivity of the TCD detector and extend its service life. In order to solve the above-mentioned technical problems, the technical solution of the present application is proposed.

[0016] In one aspect of the present application, a filtering device for gas produced by a temperature-programmed reduction instrument is provided. The device is a simple U-shaped quartz filter tube, which replaces the original cold trap / tube ring accessories on the temperature-programmed reduction instrument. The bottom of the U-shaped tube is thickened and built-in molecular sieve balls, such as Figure 1 As shown. The gas after programmed temperature reduction flows through the U-shaped tube, and the gases such as H2O, HCl, H2S, CO2, and CH4 in the gas can be effectively adsorbed.

[0017] Optionally, the filtering device is a U-shaped quartz filter tube;

[0018] The U-shaped quartz filter tube has a built-in molecular sieve;

[0019] The U-shaped quartz filter tube includes an air inlet end and an air outlet end;

[0020] The air inlet end is connected to the air outlet end of the sample tube in the programmed temperature reduction instrument;

[0021] The gas outlet is connected to the gas inlet of a detector in the programmed temperature reduction instrument.

[0022] Optionally, the molecular sieve is built into the bottom of the U-shaped tube of the U-shaped quartz filter tube. However, the gas mainly flows through the upper part of the molecular sieve, resulting in uneven adsorption; the molecular sieve has no morphological changes such as color and volume before and after moisture absorption and saturation, and it cannot be activated in time according to the degree of adsorption, thereby failing to ensure the accuracy of the experiment.

[0023] In order to further improve the accuracy of the experiment, a color-changing silica gel ball is also placed in the U-shaped quartz filter tube.

[0024] Optionally, the U-shaped quartz filter tube is a two-stage U-shaped quartz filter tube.

[0025] Optionally, a cylindrical protrusion I is provided on the tube body of the filter tube at the air inlet end;

[0026] The cylindrical protrusion I is coaxial with the filter tube at the air inlet end;

[0027] The inner cavity formed by the cylindrical protrusion I contains the color-changing silica gel ball.

[0028] Optionally, a cylindrical protrusion II is provided on the tube body of the filter tube at the gas outlet end;

[0029] The cylindrical protrusion II is coaxial with the filter tube at the gas outlet end;

[0030] The inner cavity formed by the cylindrical protrusion II contains the molecular sieve.

[0031] Optionally, a perforated partition is further provided in the inner cavity formed by the cylindrical protrusion I, and the color-changing silica gel ball is located on the perforated partition.

[0032] As a specific implementation method, the filtration device replaces the original cold trap / tube ring accessories on the programmed temperature reduction instrument with a two-stage U-shaped quartz filter tube. The two sides of the U-shaped tube are thickened, and molecular sieve balls and appropriate amount of color-changing silica gel balls are placed respectively. The bottom of the balls is separated by a perforated partition. For details, see Figure 2 . The gas after programmed temperature reduction flows through the U-shaped tube, enters from one end of the color-changing silica gel, and flows out from one end of the molecular sieve. Gases such as H2O, HCl, H2S, CH4, CO2 in the gas can be effectively adsorbed. In this scheme, the color-changing silica gel is used as a humidity indicator. If there is a slight color change, the molecular sieve and the color-changing silica gel can be activated and regenerated. 50-80ml / min argon gas is introduced into the U-shaped tube, and heated for 4-6h by a dual heating belt temperature controller. The heating temperature of the molecular sieve is 200-350℃, and the heating temperature of the color-changing silica gel is 110-150℃.

[0033] The beneficial effects of this application include:

[0034] 1) Save time and effort

[0035] This technology does not need to set up waiting instructions for cold traps or other instructions involving manual filtering operations in the test procedure, and does not need testers to wait at the test site.

[0036] 2) Efficient and fast

[0037] This technology can filter H2O, HCl, H2S, CH4, CO2 and other 5A or 13x molecular sieve adsorbable gases. The adsorption of H2 and Ar in the carrier gas can quickly reach equilibrium before the sample is heated and reduced, and will not cause fluctuations in the TCD and mass spectrometry baselines. In the absence of leakage in the instrument, the molecular sieve can be used continuously for three to six months after in-situ heating and activation. It can effectively fully adsorb H2O, HCl, H2S, CO2 and other gases generated during the programmed temperature reduction of hydrogen, and partially adsorb CH4 gas, thereby improving data reliability and protecting the TCD detector from corrosion.

[0038] 3) Safety and environmental protection

[0039] The existing technology is to load the molecular sieve and the color-changing silica gel balls at one time, and the reducing gas flows in from the color-changing silica gel end of the U-shaped tube and flows out from the molecular sieve end. The color-changing silica gel balls can act as sensitive indicators, and when they change from blue to light pink, the molecular sieve can be activated in situ. After high-temperature desorption, the adsorbed gas is purged to the tail gas end of the instrument by the high-flow (50-80ml / min) carrier gas along the pipeline, which is safe and non-toxic.

[0040] 4) Replace the original cold trap ring on the temperature-programmed reduction instrument with a U-shaped quartz filter tube, which is divided into two sections and filled with molecular sieve balls and appropriate amount of color-changing silica gel balls, which can effectively adsorb impurity gases such as H2O, HCl, H2S, CH4, CO2, etc. generated during the temperature-programmed hydrogen reduction process. Molecular sieves and color-changing silica gel can be activated and regenerated by in-situ heating, which is easy to operate and saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a simple U-shaped quartz filter tube for this application;

[0042] Figure 2 A two-stage U-shaped quartz filter tube structure diagram and a double heating belt temperature controller diagram for this application;

[0043] Figure 3 This is a mass spectrometry signal diagram obtained in Example 1 of the present application;

[0044] Figure 4 This is a TCD signal diagram obtained in Example 1 of the present application;

[0045] Figure 5 This is a mass spectrometry signal diagram obtained in Comparative Example 1 of the present application;

[0046] Figure 6This is a TCD signal diagram obtained in Comparative Example 1 of the present application;

[0047] Figure 7 This is a mass spectrometry signal diagram obtained in Example 2 of the present application;

[0048] Figure 8 This is a TCD signal diagram obtained in Example 2 of the present application;

[0049] Fig. 9 This is a mass spectrometry signal diagram obtained in Comparative Example 2 of the present application;

[0050] Fig.10 This is a TCD signal diagram obtained in Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0051] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0052] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0053] The double heating belt used in this technology has a heat resistance temperature of 450°C. The specific activation and regeneration method of the molecular sieve and the color-changing silica gel is: 50-80ml / min argon is introduced into the U-shaped tube, and the double heating belt temperature controller is used to heat for 4-6 hours. The molecular sieve is heated at 200-350°C, and the color-changing silica gel is heated at 110-150°C.

[0054] The molecular sieve beads mentioned in this technology are of model 5A or 13x (preferably 13x), purchased from Green New Source Environmental Protection Company, and are specifically for laboratory use. Their technical indicators are detailed in Tables 1 and 2.

[0055] Table 1 Technical specifications of 5A molecular sieve beads used in this technology

[0056]

[0057] Table 2 Technical specifications of 13x molecular sieve beads used in this technology

[0058]

[0059] In the embodiment according to Figure 2A two-stage U-shaped quartz filter tube is made in medium size. The left side of the air outlet thick tube section is filled with molecular sieve balls, and the right side of the air inlet thick tube end is filled with color-changing silica gel balls (particle size 2.0-3.0mm). Remove the cold trap ring / tube on the programmed temperature reduction instrument and install the U-shaped tube. After the molecular sieve and color-changing silica gel are activated in situ, the experiment can be carried out. No further activation is required before the color-changing silica gel changes color slightly. During the programmed temperature reduction test, the carrier gas hydrogen and argon standard gas flows out of the sample tube, flows in through one end of the U-shaped tube color-changing silica gel, and then flows out from the molecular sieve end. The H2O produced during the heating process, as well as the HCl and CO that may be produced 2、 Gases such as H2S are completely adsorbed by the molecular sieve, and CH4 is partially adsorbed. Finally, only H2 and Ar are flowing through the TCD detector and mass spectrometer. At this time, the TCD detector collects the signal curve with temperature change, and the peak area of ​​the peak that appears can be interpreted as being related only to the hydrogen consumption.

[0060] Example 1

[0061] Take 40mg of Ru / Al2O3 catalyst, put it into a sample tube, install it on the programmed temperature reduction instrument, heat it to 300℃ at 10℃ / min in Ar atmosphere, then drop it to -80℃, switch the gas to hydrogen argon standard gas, and flow it through a two-stage U-shaped filter tube. When the TCD detector baseline is stable, heat the sample to 400℃ at 10℃ / min, and collect the TCD and mass spectrometry signal curves with temperature. From the mass spectrometry signal diagram ( Figure 3 ) shows that the curves of HCl, H2O, and CO2 are stable, indicating that these gases are basically fully adsorbed; the CH4 curve begins to tilt slightly at 250°C, indicating that CH4 is partially adsorbed. TCD signal diagram ( Figure 4 ), the curve is smooth, and the hydrogen consumption per gram of catalyst is estimated to be 349 umol based on the peak area of ​​the hydrogen consumption peak.

[0062] Comparative Example 1

[0063] Take 40mg of Ru / Al2O3 catalyst, load it into a sample tube, install it on a programmed temperature reduction instrument, heat it to 300℃ at 10℃ / min in an Ar atmosphere, drop it to -80℃, switch the gas to hydrogen-argon standard gas, and let the gas go through the cold trap ring / tube. At this time, according to the program preset, the software will pop up "Wait for cold trap" to wait for the cold trap instruction. Pour about 700ml of isopropanol into the Dewar flask, and pour liquid nitrogen in small amounts and multiple times, stirring quickly while pouring to prevent the temperature difference between the upper and lower parts of the isopropanol from being too large due to rapid freezing, and the freezing effect will be poor if the amount of liquid nitrogen is too low. After stirring until it is ice-slushy (this process takes 20-40 minutes), move the Dewar flask to the cold trap ring / tube to completely immerse it. After freezing for 10 minutes, wait for the TCD detector baseline to stabilize (this process takes about 30 minutes to 1 hour), heat the sample to 400℃ at 10℃ / min, and collect the curves of TCD and mass spectrometry signals changing with temperature. From Figure 5 It can be seen that compared with Example 1, after 100°C, there is an obvious H2O peak, the freezing effect of the cold trap on H2O is not ideal, and the HCl, CH4, and CO2 curves also have obvious peaks. Figure 6 The baseline of the TCD signal curve is not smooth after 150° C., and starts to slightly rise at 300° C. The hydrogen consumption per gram of catalyst is calculated to be 374 umol, which is 7.16% higher than the value measured in Example 1, which is presumably caused by the failure of the above-mentioned gases to be effectively filtered.

[0064] Example 2

[0065] Take 40mg Ir / Al2O3 catalyst, put it into the sample tube, install it on the programmed temperature reduction instrument, heat it to 300℃ at 10℃ / min in Ar atmosphere, then drop it to -80℃, switch the gas to hydrogen argon standard gas, and flow it through the U-shaped filter tube. When the TCD detector baseline is stable, heat the sample to 500℃ at 10℃ / min, and collect the TCD and mass spectrometry signal curves with temperature. From the mass spectrometry signal diagram ( Figure 7 ) shows that the curves of H2O, HCl, CO2, and CH4 are smooth and without fluctuation, proving that these gases are effectively adsorbed. TCD signal diagram ( Figure 8 ), the baseline is smooth, and the hydrogen consumption per gram of catalyst can be estimated to be 836 umol through the peak area of ​​the hydrogen consumption peak.

[0066] Comparative Example 2

[0067] Take 40mg of Ir / Al2O3 catalyst, put it into a sample tube, install it on a programmed temperature reduction instrument, heat it to 300℃ in Ar atmosphere at 10℃ / min, drop it to -80℃, switch the gas to hydrogen-argon standard gas, and let the gas go through the cold trap ring / tube. At this time, according to the program preset, the software will pop up "Wait for cold trap" to wait for the cold trap instruction. Move the Dewar flask containing the isopropanol solid-liquid mixture to the cold trap ring / tube so that it is completely immersed. After freezing for 10 minutes, wait for the TCD detector baseline to stabilize, heat the sample to 500℃ at 10℃ / min, and collect the TCD and mass spectrometry signal curves as they change with temperature. From Fig. 9 It can be seen that there is an obvious H2O peak after 400 degrees Celsius. The freezing effect of the cold trap on H2O is not ideal. The HCl, CH4, and CO2 curves also have obvious peaks. Figure 6 The TCD signal curve is not smooth after 70° C. The hydrogen consumption per gram of catalyst is calculated to be 892 umol, which is 6.70% higher than the value measured in Example 2. It is presumed that this is because the above-mentioned gases are not effectively filtered.

[0068] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A filtering device for gas produced by a programmed temperature reduction instrument, It is characterized in that The filtering device is a U-shaped quartz filtering tube; The U-shaped quartz filter tube has a built-in molecular sieve; The U-shaped quartz filter tube is also provided with a color-changing silica gel ball; The U-shaped quartz filter tube includes an air inlet end and an air outlet end; The air inlet end is connected to the air outlet end of the sample tube in the programmed temperature reduction instrument; The gas outlet is connected to the gas inlet of a detector in the programmed temperature reduction instrument.

2. The filtering device according to claim 1, It is characterized in that The molecular sieve is built in the bottom of the U-shaped tube of the U-shaped quartz filter tube.

3. The filtering device according to claim 2, It is characterized in that The U-shaped quartz filter tube is a two-stage U-shaped quartz filter tube.

4. The filtering device according to claim 1, It is characterized in that A cylindrical protrusion I is provided on the body of the filter tube at the air inlet end; The cylindrical protrusion I is coaxial with the filter tube at the air inlet end; The inner cavity formed by the cylindrical protrusion I contains the color-changing silica gel ball.

5. The filtering device according to claim 1, It is characterized in that A cylindrical protrusion II is provided on the body of the filter tube at the gas outlet end; The cylindrical protrusion II is coaxial with the filter tube at the gas outlet end; The inner cavity formed by the cylindrical protrusion II contains the molecular sieve.

6. The filtering device according to claim 4, It is characterized in that A perforated partition is also provided in the inner cavity formed by the cylindrical protrusion I, and the color-changing silica gel ball is located on the perforated partition.

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