A method for regenerating a phosphorus-poisoned Cu-LTA catalyst
By heating the phosphorus-poisoned Cu-LTA catalyst at 700-900℃, the problem of catalyst deactivation was solved, achieving rapid and low-cost regeneration and restoring the low-temperature activity of the catalyst.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF URBAN ENVIRONMENT CHINESE ACAD OF SCI
- Filing Date
- 2023-06-20
- Publication Date
- 2026-05-01
AI Technical Summary
Phosphorus poisoning leads to the deactivation of Cu-LTA catalysts, affecting their activity and lifespan in NOx purification, and existing technologies are difficult to regenerate effectively.
The phosphorus-poisoned Cu-LTA catalyst is regenerated by heating it at 700-900℃ in an aqueous or anhydrous atmosphere through a one-step heating process.
It achieves rapid catalyst regeneration, low-temperature activity recovery, simple operation and low cost, and low-temperature activity is basically fully regenerated, shortening the regeneration time.
Smart Images
Figure CN118788406B_ABST
Abstract
Description
A method for regenerating phosphorus-poisoned Cu-LTA catalyst Technical Field
[0001] This invention belongs to the field of catalyst technology and relates to a method for regenerating catalysts, specifically a method for regenerating phosphorus-poisoned Cu-LTA catalysts. Background Technology
[0002] Nitrogen oxides (NO) x Nitrogen oxides (NOx) are one of the major air pollutants, causing significant environmental problems such as photochemical smog, acid rain, and the greenhouse effect. They also pose a serious threat to human health, leading to respiratory diseases. Therefore, controlling NOx emissions is crucial. NOx primarily originates from stationary sources, such as coal-fired power plants, and mobile sources, such as diesel vehicles. Currently, NH3-SCR catalysts, using NH3 as a reducing agent, are widely used for the catalytic reduction of NO. x .
[0003] Cu-LTA is a copper-based small-porous molecular sieve catalyst with excellent hydrothermal stability and NH3-SCR activity, and can be applied to NO. x Purification. However, in actual use, catalyst performance is damaged by various chemical substances, among which phosphorus has the most significant impact. Phosphorus mainly comes from lubricants, and oil additives (such as zinc dialkyl dithiophosphate, ZDDP) are unavoidable regardless of fuel composition. In catalysts, phosphorus is usually present as phosphorus oxide (P2O5) and metaphosphate (PO3). - ) and phosphate (PO4) 3- The presence of phosphorus in the form of ) can cause pore blockage and physical deactivation by covering the active sites; in addition, the interaction between phosphorus and skeletal aluminum or non-skeletal aluminum, and the strong interaction between active copper and phosphorus not only leads to the loss of copper catalytic active centers, but also restricts the dynamic movement of copper, reduces redox performance, and causes chemical deactivation.
[0004] To improve the efficiency and lifespan of Cu-LTA catalysts, a method for regenerating phosphorus-poisoned Cu-LTA catalysts is needed. Summary of the Invention
[0005] The purpose of this invention is to provide a method for regenerating phosphorus-poisoned Cu-LTA catalysts, which can regenerate Cu-LTA catalysts after they have been deactivated by phosphorus poisoning during use, enabling Cu-LTA to be reused and improving its efficiency and lifespan.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] This invention provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0008] Phosphorus-poisoned Cu-LTA catalyst is heated at 700-900℃ in the presence of water and / or anhydrous atmosphere to obtain regenerated Cu-LTA catalyst.
[0009] The regeneration method provided by this invention only requires a heating process to regenerate phosphorus-poisoned Cu-LTA catalyst. After phosphorus poisoning, the Cu active sites of Cu-LTA catalyst are deactivated, the low-temperature activity is reduced, and Cu-P species are generated. After high-temperature regeneration, the Cu-P species decompose, and the Cu sites regain activity. The operation method is simple, low-cost, and has good regeneration effect.
[0010] Preferably, the water atmosphere includes any one or a combination of at least two of water-containing nitrogen, water-containing air, or water-containing oxygen. Typical but non-limiting combinations include a combination of water-containing nitrogen and water-containing air, a combination of water-containing air and water-containing oxygen, or a combination of water-containing nitrogen, water-containing air, and water-containing oxygen.
[0011] Preferably, the anhydrous atmosphere includes any one or a combination of at least two of nitrogen, oxygen, or air. Typical but non-limiting combinations include a combination of nitrogen and air, a combination of air and oxygen, or a combination of nitrogen, air, and oxygen.
[0012] Preferably, the volume fraction of water in the aqueous atmosphere is 1-30%, for example, it can be 1%, 5%, 10%, 15%, 20%, 25% or 30%, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0013] Preferably, the phosphorus-poisoned Cu-LTA catalyst is obtained by treating Cu-LTA catalyst with phosphorus poisoning.
[0014] Preferably, the preparation method of the Cu-LTA catalyst includes the following steps: H-LTA is synthesized by hydrothermal method using silicon source, aluminum source, tetramethylammonium hydroxide pentahydrate, organic structure directing agent and seed crystal, and then ammonium exchange and copper exchange are performed twice in sequence. After each exchange, the catalyst is filtered, washed and dried, and finally calcined to obtain Cu-LTA catalyst.
[0015] Preferably, the reaction temperature of the hydrothermal method is 150-200℃, for example, it can be 150℃, 160℃, 170℃, 180℃, 190℃ or 200℃, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0016] Preferably, the ammonium source used for the ammonium exchange includes ammonium chloride.
[0017] Preferably, the copper source used for copper exchange includes copper nitrate.
[0018] Preferably, the roasting temperature is 500-600℃, for example, 500℃, 520℃, 550℃, 580℃ or 600℃, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0019] Preferably, the roasting time is 5-10 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but not limited to the listed values. Other unlisted values within the range are also applicable.
[0020] Preferably, the phosphorus poisoning treatment includes the following steps: mixing Cu-LTA catalyst with a phosphorus source, and then drying and calcining the mixture to obtain a phosphorus-poisoned Cu-LTA catalyst.
[0021] Preferably, the phosphorus source comprises diammonium hydrogen phosphate.
[0022] Preferably, the second calcination temperature is 500-600℃, for example, it can be 500℃, 520℃, 550℃, 580℃ or 600℃, but is not limited to the listed values, and other unlisted values within the range are also applicable.
[0023] Preferably, the second roasting time is 1-8 hours, for example, it can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0024] Compared with the prior art, the present invention has the following beneficial effects:
[0025] The regeneration method for phosphorus-poisoned Cu-LTA catalyst provided by this invention can regenerate the catalyst in just one heating step. The operation method is simple, low-cost, and easy to implement. The regeneration process only takes 1 hour, which greatly shortens the processing time compared with the prior art. Moreover, the regeneration effect is good, and the low-temperature activity can basically achieve complete regeneration. Attached Figure Description
[0026] Figure 1 shows the NO content of the regenerated Cu-LTA catalyst prepared in Examples 1-3 of this invention, as well as the Cu-LTA catalyst and the phosphorus-poisoned Cu-LTA catalyst. x The curve showing the relationship between conversion rate and temperature.
[0027] Figure 2 shows the XRD diffraction patterns of the regenerated Cu-LTA catalyst, Cu-LTA catalyst, and phosphorus-poisoned Cu-LTA catalyst prepared in Examples 1-3 of this invention.
[0028] Figure 3 shows the NO content of the regenerated Cu-LTA catalyst and Cu-LTA catalyst prepared in Examples 2 and 4-8 of this invention, as well as the NO content of the phosphorus-poisoned Cu-LTA catalyst.x The curve showing the relationship between conversion rate and temperature.
[0029] Figure 4 shows the XRD diffraction patterns of the regenerated Cu-LTA catalyst, Cu-LTA catalyst, and phosphorus-poisoned Cu-LTA catalyst prepared in Examples 2 and 4-8 of this invention. Detailed Implementation
[0030] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0031] To clearly illustrate the technical solution of this invention, the regenerated Cu-LTA catalyst prepared in the embodiments of this invention was sequentially compressed, ground, and sieved. 40-60 mesh particles were then used to test the NH3-SCR reaction activity in a fixed-bed reactor, yielding NO... x The curve showing the relationship between conversion rate and temperature.
[0032] The test conditions for the NH3-SCR reactivity assay were as follows: the NO and NH3 concentrations in the test gas were 500 ppm each, the O2 volume fraction was 5%, the H2O volume fraction was 10%, and N2 was used as the equilibrium gas. The total gas flow rate was 500 mL / min. -1 The reaction space velocity is 100,000 h⁻¹ -1 The reaction temperature was 150-600℃. During the reaction, the contents of NO, NH3, and byproducts N2O and NO2 were determined using an infrared gas analyzer (Antaris IGS).
[0033] Example 1
[0034] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0035] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 700°C for 1 hour in an air atmosphere with a water volume fraction of 10% to obtain the regenerated Cu-LTA catalyst.
[0036] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is as follows:
[0037] (1) H-LTA was synthesized by hydrothermal method using tetraethyl orthosilicate, aluminum hydroxide, tetramethylammonium hydroxide pentahydrate, organic structure directing agent and seed crystals at a hydrothermal temperature of 175℃.
[0038] (2) Using ammonium chloride as ammonium source and copper nitrate as copper source, the LTA obtained in step (1) was subjected to two ammonium exchange and two copper exchange in sequence. After each exchange, it was filtered, washed and dried, and then placed in a muffle furnace and calcined at 550°C for 8 hours to obtain Cu-LTA catalyst. The copper content in the obtained Cu-LTA catalyst was 2.1 wt%.
[0039] (3) Using diammonium hydrogen phosphate as a precursor, Cu-LTA was impregnated and dried, and then placed in a muffle furnace and calcined at 550°C for 4 hours to obtain phosphorus-poisoned Cu-LTA catalyst. The phosphorus loading of each gram of phosphorus-poisoned Cu-LTA catalyst was 0.2 mmol.
[0040] The regenerated Cu-LTA catalyst prepared in this embodiment is designated as P-Cu-LTA(700)-HA.
[0041] The NO content of the Cu-LTA catalyst, phosphorus-poisoned Cu-LTA catalyst (denoted as P-Cu-LTA), and regenerated Cu-LTA catalyst prepared in this embodiment is shown in the figure. x The conversion rate is shown in Figure 1, and the XRD diffraction pattern is shown in Figure 2.
[0042] Example 2
[0043] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0044] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 800°C for 1 hour in an air atmosphere with a water volume fraction of 10% to obtain the regenerated Cu-LTA catalyst.
[0045] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is the same as in Example 1.
[0046] The regenerated Cu-LTA catalyst prepared in this embodiment is designated as P-Cu-LTA(800)-HA, and its NO content is... x The conversion rate is shown in Figure 1, and the XRD diffraction pattern is shown in Figure 2.
[0047] Example 3
[0048] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0049] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 900°C for 1 hour in an air atmosphere with a water volume fraction of 10% to obtain the regenerated Cu-LTA catalyst.
[0050] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is the same as in Example 1.
[0051] The regenerated Cu-LTA catalyst prepared in this embodiment is designated as P-Cu-LTA(900)-HA, and its NO content is... x The conversion rate is shown in Figure 1, and the XRD diffraction pattern is shown in Figure 2.
[0052] Example 4
[0053] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0054] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 800°C for 1 hour in air atmosphere to obtain the regenerated Cu-LTA catalyst.
[0055] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is the same as in Example 1.
[0056] The regenerated Cu-LTA catalyst prepared in this embodiment is designated as P-Cu-LTA(800)-A, and its NO content is... x The conversion rate is shown in Figure 3, and the XRD diffraction pattern is shown in Figure 4.
[0057] Example 5
[0058] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0059] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 800°C for 1 hour under an oxygen atmosphere to obtain the regenerated Cu-LTA catalyst.
[0060] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is the same as in Example 1.
[0061] The regenerated Cu-LTA catalyst prepared in this embodiment is designated as P-Cu-LTA(800)-O, and its NO content is... x The conversion rate is shown in Figure 3, and the XRD diffraction pattern is shown in Figure 4.
[0062] Example 6
[0063] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0064] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 800°C for 1 hour in an oxygen atmosphere with a water volume fraction of 10% to obtain the regenerated Cu-LTA catalyst.
[0065] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is the same as in Example 1.
[0066] The regenerated Cu-LTA catalyst prepared in this embodiment is designated as P-Cu-LTA(800)-HO, and its NO content is... x The conversion rate is shown in Figure 3, and the XRD diffraction pattern is shown in Figure 4.
[0067] Example 7
[0068] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0069] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 800°C for 1 hour under a nitrogen atmosphere to obtain the regenerated Cu-LTA catalyst.
[0070] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is the same as in Example 1.
[0071] The regenerated Cu-LTA catalyst prepared in this embodiment is designated as P-Cu-LTA(800)-N, and its NO content is... x The conversion rate is shown in Figure 3, and the XRD diffraction pattern is shown in Figure 4.
[0072] Example 8
[0073] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0074] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 800°C for 1 hour under a nitrogen atmosphere containing 10% water by volume to obtain the regenerated Cu-LTA catalyst.
[0075] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is the same as in Example 1.
[0076] The regenerated Cu-LTA catalyst prepared in this embodiment is designated as P-Cu-LTA(800)-HN, and its NO content is... x The conversion rate is shown in Figure 3, and the XRD diffraction pattern is shown in Figure 4.
[0077] Example 9
[0078] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0079] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 800°C for 1 hour under a nitrogen atmosphere containing 1% water by volume to obtain the regenerated Cu-LTA catalyst.
[0080] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is as follows:
[0081] (1) H-LTA was synthesized by hydrothermal method using tetraethyl orthosilicate, aluminum hydroxide, tetramethylammonium hydroxide pentahydrate, organic structure directing agent and seed crystals at a hydrothermal temperature of 150℃.
[0082] (2) Using ammonium chloride as ammonium source and copper nitrate as copper source, the LTA obtained in step (1) was subjected to two ammonium exchange and two copper exchange in sequence. After each exchange, it was filtered, washed and dried, and then placed in a muffle furnace and calcined at 500°C for 10 h to obtain Cu-LTA catalyst. The copper content in the obtained Cu-LTA catalyst was 2.1 wt%.
[0083] (3) Using diammonium hydrogen phosphate as a precursor, Cu-LTA was impregnated and dried, and then placed in a muffle furnace and calcined at 500°C for 8 hours to obtain phosphorus-poisoned Cu-LTA catalyst. The phosphorus loading per gram of phosphorus-poisoned Cu-LTA catalyst was 0.2 mmol.
[0084] Example 10
[0085] This embodiment provides a method for regenerating a phosphorus-poisoned Cu-LTA catalyst, the regeneration method comprising the following steps:
[0086] The phosphorus-poisoned Cu-LTA catalyst was placed in a tube furnace and heated at 800°C for 1 hour under a nitrogen atmosphere containing 30% water by volume to obtain the regenerated Cu-LTA catalyst.
[0087] In this embodiment, the preparation method of the phosphorus-poisoned Cu-LTA catalyst is as follows:
[0088] (1) H-LTA was synthesized by hydrothermal method using tetraethyl orthosilicate, aluminum hydroxide, tetramethylammonium hydroxide pentahydrate, organic structure directing agent and seed crystals at a hydrothermal temperature of 200℃.
[0089] (2) Using ammonium chloride as ammonium source and copper nitrate as copper source, the LTA obtained in step (1) was subjected to two ammonium exchange and two copper exchange in sequence. After each exchange, it was filtered, washed and dried, and then placed in a muffle furnace and calcined at 600°C for 5 hours to obtain Cu-LTA catalyst. The copper content in the obtained Cu-LTA catalyst was 2.1 wt%.
[0090] (3) Using diammonium hydrogen phosphate as a precursor, Cu-LTA was impregnated and dried, and then placed in a muffle furnace and calcined at 600°C for 1 h to obtain phosphorus-poisoned Cu-LTA catalyst. The phosphorus loading of each gram of phosphorus-poisoned Cu-LTA catalyst was 0.2 mmol.
[0091] As shown in Figure 1, under the same reaction conditions, the regenerated Cu-LTA catalysts prepared in Examples 1-3 of this invention exhibit significantly higher NH3-SCR activity at low temperatures (below 450°C) than the unregenerated P-Cu-LTA catalyst. The regenerated Cu-LTA catalyst P-Cu-LTA(900)-HA prepared in Example 3 of this invention shows the best low-temperature activity, essentially the same as the activity of the unpoisoned Cu-LTA catalyst, indicating complete regeneration at low temperatures. In the prior art, the regeneration treatment of phosphorus-poisoned Cu-SSZ requires more than 12 hours, while the regeneration method provided by this invention achieves excellent regeneration results in just 1 hour.
[0092] As shown in Figure 3, under the same reaction conditions, the NH3-SCR activities of Examples 2 and 4-8 of this invention at low temperatures (below 450°C) are significantly higher than those of the unregenerated P-Cu-LTA catalyst. The regenerated Cu-LTA catalyst prepared in Example 8 of this invention exhibits the best low-temperature activity, which is very close to that of the unpoisoned Cu-LTA catalyst. The preferred reaction conditions of this invention can achieve the best regeneration effect for phosphorus-poisoned Cu-LTA catalysts. If the regeneration temperature is too low, the Cu-P species in the catalyst are not easily decomposed, making complete regeneration difficult. The examples of this invention have already achieved complete regeneration of the catalyst's low-temperature activity. If the reaction temperature is further increased, it is difficult to further improve the catalyst's regeneration activity; instead, it may damage the catalyst structure and affect its performance.
[0093] As shown in Figures 2 and 4, the XRD diffraction patterns of the regenerated Cu-LTA catalyst prepared in the embodiments of the present invention show no significant changes from the structures of Cu-LTA and P-Cu-LTA. The regeneration method provided by the present invention does not damage the structure of the catalyst.
[0094] In summary, the regeneration method for phosphorus-poisoned Cu-LTA catalyst provided by this invention only requires one heating step to achieve catalyst regeneration. The operation method is simple, low-cost, and easy to implement. Compared with the prior art, the processing time is greatly shortened, and the regeneration effect is good. The low-temperature activity can basically achieve complete regeneration.
[0095] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A method for regenerating a phosphorus-poisoned Cu-LTA catalyst, characterized in that, The regeneration method includes the following steps: heating the phosphorus-poisoned Cu-LTA catalyst at 700-900℃ in an aqueous and / or anhydrous atmosphere to obtain a regenerated Cu-LTA catalyst; the preparation method of the Cu-LTA catalyst includes the following steps: synthesizing H-LTA by hydrothermal method using a silicon source, an aluminum source, tetramethylammonium hydroxide pentahydrate, an organic structure directing agent and seed crystals, then performing two ammonium exchange and two copper exchange in sequence, and after each exchange, filtering, washing and drying are performed, and finally calcination is performed to obtain the Cu-LTA catalyst.
2. The regeneration method according to claim 1, characterized in that, The aqueous atmosphere includes any one or a combination of at least two of the following: aqueous nitrogen, aqueous air, or aqueous oxygen.
3. The regeneration method according to claim 1, characterized in that, The anhydrous atmosphere includes any one or a combination of at least two of nitrogen, oxygen, or air.
4. The regeneration method according to claim 1, characterized in that, The volume fraction of water in the aqueous atmosphere is 1-30%.
5. The regeneration method according to claim 1, characterized in that, The phosphorus-poisoned Cu-LTA catalyst is obtained by treating Cu-LTA catalyst with phosphorus poisoning.
6. The regeneration method according to claim 1, characterized in that, The reaction temperature of the hydrothermal method is 150-200℃.
7. The regeneration method according to claim 1, characterized in that, The ammonium source used for the ammonium exchange includes ammonium chloride.
8. The regeneration method according to claim 1, characterized in that, The copper source used in the copper exchange includes copper nitrate.
9. The regeneration method according to claim 1, characterized in that, The roasting temperature is 500-600℃.
10. The regeneration method according to claim 1, characterized in that, The roasting time is 5-10 hours.
11. The regeneration method according to claim 5, characterized in that, The phosphorus poisoning treatment includes the following steps: mixing Cu-LTA catalyst with a phosphorus source, and then drying and calcining the mixture to obtain a phosphorus-poisoned Cu-LTA catalyst.
12. The regeneration method according to claim 11, characterized in that, The phosphorus source includes diammonium hydrogen phosphate.
13. The regeneration method according to claim 11, characterized in that, The second roasting temperature is 500-600℃.
14. The regeneration method according to claim 11, characterized in that, The second roasting time is 1-8 hours.