Method for regenerating platinum-tin dehydrogenation catalyst by using chlorinating agent steam

Abstract

The invention belongs to the technical field of petrochemical industry, and discloses a method for regenerating a platinum-tin dehydrogenation catalyst by using chlorinating agent steam, which comprises the following steps: adding a chlorinating agent into a bubbler, and adjusting a water bath to a preset temperature; preset gas is connected to the front end of the reactor through the bubbler; placing the inactivated platinum-tin dehydrogenation catalyst in a reactor, heating the reactor to a roasting temperature, and roasting in an oxygen-containing atmosphere; adjusting the temperature of the reactor to oxychlorination temperature, setting the preset flow of the preset gas, introducing oxygen-containing gas to stabilize the chlorinating agent of the influent section at the preset concentration, and treating for a period of time under the condition; the protective gas purges and displaces gas in the reactor and the pipeline; and adjusting the reactor to a reduction temperature, introducing a reducing gas, and carrying out a reduction reaction to obtain the regenerated platinum-tin dehydrogenation catalyst. Under the condition of not depending on ultra-low flow precise injection equipment, controllable adjustment and long-term stable maintenance of the ppm-grade chlorine content in the reaction atmosphere are realized.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically, it relates to a method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor. Background Technology

[0002] Propane dehydrogenation (PDH) is an industrial reaction process that selectively converts propane into propylene. Propylene, as a basic organic chemical feedstock, is widely used in the preparation of various chemical products such as polypropylene, epoxy resins, acrylic acid, and its esters. In recent years, with the continuous growth in downstream industries' demand for propylene, the importance of propane dehydrogenation technology in the olefin production field has become increasingly prominent. Compared with traditional petroleum-based olefin production routes, propane dehydrogenation technology has the advantages of a wider range of feedstock sources and relatively lower costs, especially with the development of shale gas, which has resulted in abundant propane resources and a significant price advantage. At the same time, this process reduces dependence on petroleum resources to a certain extent, which is conducive to building a more diversified and sustainable olefin production system. Therefore, propane dehydrogenation to propylene has gradually developed into one of the important technological approaches for obtaining propylene in modern chemical production.

[0003] In existing propane dehydrogenation processes, Pt-based catalysts are widely studied and applied due to their high dehydrogenation activity and propylene selectivity. However, propane dehydrogenation reactions are typically carried out at high temperatures, exceeding 600 °C, under which conditions carbon deposits easily form on the catalyst surface. The continuous accumulation of carbon deposits obscures the active sites of the catalyst, leading to a decrease in catalyst activity or even catalyst failure. Simultaneously, under high-temperature conditions, Pt metal particles inevitably sinter and deactivate. Therefore, periodic regeneration of the catalyst is necessary. For industrial-scale reactors, this is typically achieved by introducing a liquid chlorinating agent into the system to maintain a ppm-level chlorine environment in the reaction atmosphere, thereby redispersing the sintered metal particles and regenerating them.

[0004] However, in small or laboratory-scale reactors, due to the low flow rate of the reactant gas, the injection flow rate of the chlorinating agent needs to be precisely controlled at approximately 1 × 10⁻⁶ to maintain the same ppm-level chlorine content. −3 The flow rate is on the order of μL / min. Existing conventional feeding equipment, such as syringe pumps, cannot achieve stable, continuous, and high-precision supply within this micro-volume range, and is prone to large fluctuations, thus limiting the application of related regeneration methods in small-scale devices. Summary of the Invention

[0005] This invention focuses on the technical problem of insufficient precision and large fluctuations in chlorinating agent addition during the periodic regeneration of catalysts in small and laboratory-scale reactors. It provides a method for regenerating platinum-tin dehydrogenation catalysts using chlorinating agent vapor, which achieves controllable adjustment and long-term stable maintenance of ppm-level chlorine content in the reaction atmosphere without relying on ultra-low flow precision injection equipment.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0007] This invention provides a method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor, comprising:

[0008] (1) Add chlorinating agent to the bubbler, which is placed in a circulating cooler, and adjust the circulating constant temperature water bath to the preset temperature;

[0009] (2) The inlet of the bubbler is connected to a preset gas G1, and the outlet of the bubbler is connected to the inlet of the reactor;

[0010] (3) The deactivated platinum-tin dehydrogenation catalyst is placed in the reactor, the reactor is heated to the calcination temperature, and calcined in an oxygen-containing atmosphere;

[0011] (4) Adjust the reactor to the oxychlorination temperature, set the flow rate of the preset gas G1 to the preset flow rate, and introduce oxygen-containing gas G2 into the reactor so that the chlorinating agent in the inflow section of the reactor is stabilized at the preset concentration, and maintain this condition for a period of time.

[0012] (5) The reactor and pipeline are purged with protective gas to replace the gas.

[0013] (6) Adjust the reactor to the reduction temperature and introduce reducing gas G3 into the reactor. After the reduction reaction occurs, the regenerated platinum-tin dehydrogenation catalyst is obtained.

[0014] Furthermore, the preset temperature in step (1) and the preset flow rate in step (4) are calculated based on the preset concentration of the chlorinating agent in the inflow section of the reactor, using the saturated vapor pressure of the chlorinating agent.

[0015] Specifically:

[0016] First, based on the physical properties of the selected chlorinating agent, the saturated vapor pressure P of the chlorinating agent at the preset temperature is determined using the Antoine equation. s Among them, P s It is the saturated vapor pressure;

[0017] Secondly, based on Dalton's law of partial pressures and the ideal gas law, the pressure P at the preset temperature is calculated. sysBelow, the mole fraction (P) of the saturated chlorinating agent carried in the carrier gas (passing through at a preset flow rate) s / P sys );

[0018] Finally, by combining the ratio of the relative molecular masses of the chlorinating agent to the carrier gas, the preset flow rate (the mass flow rate of the gas entering the bubbling gas) is converted into the actual supply of chlorinating agent, so as to meet the material balance requirements of the preset chlorine concentration under the total feed flow rate of the reactor.

[0019] In practice, a preset temperature is usually fixed to obtain a stable saturated vapor pressure P. s This allows for the calculation of the required preset flow rate; or, by fixing the preset flow rate, the calculation of the required preset temperature, thereby achieving precise control over the concentration of chlorinating agent entering the reactor.

[0020] Furthermore, the chlorinating agent in step (1) is dichloroethane.

[0021] Furthermore, the preset gas G1 in step (2) is nitrogen or air.

[0022] Furthermore, the mass fraction of the platinum-tin dehydrogenation catalyst in step (3) is 0.1-2.0%.

[0023] Furthermore, the calcination temperature in steps (1) and (3) is 450-530℃, and the calcination time in the oxygen-containing atmosphere in step (3) is 10-240 min.

[0024] Furthermore, the oxychlorination temperature in step (4) is 480-530℃, and the treatment time under the conditions of step (4) is 10-240 min.

[0025] Furthermore, in step (4), the oxygen concentration in the mixture of preset gas G1 and oxygen-containing gas G2 is 2% to 21%.

[0026] Furthermore, the reduction temperature in step (6) is 550-620℃, and the reduction reaction time is 30-240 min.

[0027] Furthermore, the reducing gas G3 in step (6) is a hydrogen-containing gas.

[0028] Preferably, the reducing gas G3 is a mixture of hydrogen and nitrogen.

[0029] The beneficial effects of this invention are:

[0030] This invention achieves controllable and long-term stable control of the ppm-level chlorine content in the reaction atmosphere by stably and continuously introducing the chlorinating agent in vapor form into the reactor, without relying on ultra-low flow precision injection equipment. This effectively solves the problems of insufficient chlorinating agent dosing precision and large fluctuations in small-scale and laboratory-scale reactors. The method of this invention can perform mild and uniform regeneration of Pt-based catalysts under high-temperature and oxygen-containing conditions, significantly improving catalyst stability and lifespan. Furthermore, this invention features a simple overall process, high operational safety, wide applicability, good repeatability, and engineering scale-up potential, making it suitable for widespread application in propane dehydrogenation reaction systems of different scales. Attached Figure Description

[0031] Figure 1 The graph shows a comparison of the propane dehydrogenation performance of the platinum-containing catalysts in Examples 1, 17, 26, and 27 of this invention after regeneration. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0033] Example 1

[0034] This embodiment provides a method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor.

[0035] The catalyst to be treated is a platinum-tin dehydrogenation catalyst that has been deactivated by carbon deposition, wherein the mass fraction of platinum (Pt) is 0.3%.

[0036] The regeneration method specifically includes the following steps:

[0037] Step 1: Add the chlorinating agent dichloroethane to the bubbler and place the bubbler in the circulating cooler. Start the constant temperature circulating water bath and adjust the water bath temperature to the preset temperature of 4°C to keep the dichloroethane at a constant saturated vapor pressure.

[0038] Step 2: Connect the gas outlet of the bubbler to the front end of the reactor through a heat tracing pipeline, and connect the inlet of the bubbler to the preset gas G1, which is high-purity nitrogen.

[0039] Step 3: Place the deactivated platinum-tin dehydrogenation catalyst in a reactor under an air atmosphere, heat the reactor to a calcination temperature of 480°C, and maintain this temperature for calcination for 30 minutes.

[0040] Step 4: Continue adjusting the reactor temperature to 500℃ for oxychlorination. Based on the saturated vapor pressure of dichloroethane at 4℃ in Step 1, calculate and set the preset flow rate of nitrogen (preset gas G1) through the bubbler to ensure a chlorine content of 700 ppm in the reactor. Simultaneously, introduce oxygen-containing gas G2 into the reactor and adjust the flow rate of G2 to achieve an oxygen concentration of 10% in the mixed gas (G1 + G2). Under these conditions, stabilize the chlorine concentration in the inflow section of the reactor and maintain these conditions for 30 minutes to achieve redispersibility of platinum active sites.

[0041] Step 5: After the treatment in Step 4 is completed, cut off the supply of chlorinating agent and oxygen-containing gas, and use nitrogen as a protective gas to purge the system until the oxygen-containing gas in the reactor and pipeline is completely replaced.

[0042] Step 6: Adjust the reactor temperature to the reduction temperature of 600℃, and introduce reducing gas G3 (a mixture of hydrogen and nitrogen) to carry out the reduction reaction for 60 min, thereby obtaining the regenerated platinum-tin dehydrogenation catalyst.

[0043] After the above treatment, the catalyst was tested for propane dehydrogenation activity. The catalyst loading was 100 mg, the reaction temperature was 600 °C, the molar ratio of propane to hydrogen was 2:1, and the total flow rate was 50 mL / min.

[0044] Example 2

[0045] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0046] In step three, the roasting time is 10 minutes.

[0047] Example 3

[0048] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0049] In step three, the roasting time is 240 min.

[0050] Example 4

[0051] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0052] In step three, the roasting temperature is 500℃.

[0053] Example 5

[0054] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0055] In step three, the roasting temperature is 530℃.

[0056] Example 6

[0057] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0058] In step four, the oxychlorination temperature is 480℃.

[0059] Example 7

[0060] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0061] In step four, the oxychlorination temperature is 530℃.

[0062] Example 8

[0063] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0064] In step four, the oxychlorination treatment time is 10 min.

[0065] Example 9

[0066] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0067] In step four, the oxychlorination treatment time is 240 min.

[0068] Example 10

[0069] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0070] In step six, the reduction temperature is 550℃.

[0071] Example 11

[0072] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0073] In step six, the reduction temperature is 620℃.

[0074] Example 12

[0075] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0076] In step six, the reduction reaction time is 30 min.

[0077] Example 13

[0078] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0079] In step six, the reduction reaction time is 240 min.

[0080] Example 14

[0081] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0082] In step six, the reducing gas G3 is pure hydrogen.

[0083] Example 15

[0084] The only difference between this embodiment and Example 1 is the catalyst parameters. The specific process parameters are adjusted as follows:

[0085] The mass fraction of platinum (Pt) in the catalyst to be treated is 0.1%.

[0086] Example 16

[0087] The only difference between this embodiment and Example 1 is the catalyst parameters. The specific process parameters are adjusted as follows:

[0088] The mass fraction of platinum (Pt) in the catalyst to be treated is 2.0%.

[0089] Example 17

[0090] In this embodiment, a fresh catalyst with a Pt content of 0.3% was used. Without undergoing the above regeneration treatment, it was directly subjected to the reduction treatment in step six, and then the propane dehydrogenation activity was tested under the same conditions as in Example 1.

[0091] Example 18

[0092] In this embodiment, a fresh catalyst with a Pt content of 0.1% was used. Without undergoing the above regeneration treatment, it was directly subjected to the reduction treatment in step six, and then the propane dehydrogenation activity was tested under the same conditions as in Example 1.

[0093] Example 19

[0094] In this embodiment, a fresh catalyst with a Pt content of 2% was used. Without undergoing the above regeneration treatment, it was directly subjected to the reduction treatment in step six, and then the propane dehydrogenation activity was tested under the same conditions as in Example 1.

[0095] Example 20

[0096] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0097] In step four, the chlorine content in the reactor is 0 ppm.

[0098] Example 21

[0099] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0100] In step four, the chlorine content in the reactor is 300 ppm.

[0101] Example 22

[0102] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0103] In step four, the chlorine content in the reactor is 1000 ppm.

[0104] Example 23

[0105] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0106] In step two, the preset gas G1 is air.

[0107] Example 24

[0108] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0109] In step four, the oxygen concentration in the gas mixture (G1 + G2) is 2%.

[0110] Example 25

[0111] The only difference between this embodiment and Embodiment 1 is the regeneration process parameters. The specific process parameters are adjusted as follows:

[0112] In step four, the oxygen concentration in the gas mixture (G1 + G2) is 20%.

[0113] Example 26

[0114] The only difference between this embodiment and Example 1 is the catalyst used.

[0115] The catalyst to be treated is a Pt-based dehydrogenation catalyst that has been treated in steps one to six of Example 1 and has undergone propane dehydrogenation activity testing.

[0116] Example 27

[0117] The only difference between this embodiment and Example 1 is the catalyst used.

[0118] The catalyst to be treated was a Pt-based dehydrogenation catalyst that had been treated in steps one to six of Example 26 and tested for propane dehydrogenation activity.

[0119] A comparative analysis was conducted on the experimental results of Examples 1-27 above, using the same test conditions and methods as in Example 1, to examine the influence of different parameters on the catalyst reaction performance.

[0120] (1) The effect of calcination time on catalyst regeneration performance in step three of Examples 1, 2, 3 and 17. See Table 1 for specific test results.

[0121] Table 1. Effect of carbonization time on the regeneration performance of platinum-containing catalysts

[0122]

[0123] Table 1 shows that the carbonization time significantly affects the performance of platinum-containing catalysts in the propane dehydrogenation reaction. For fresh catalysts, the propane conversion is 32% and the propylene selectivity is 87.6%. For catalysts requiring regeneration after deactivation, when the calcination time is 10 min, the propane conversion drops to 19.2%, although the propylene selectivity remains around 86.1%, the catalyst activity is low. With increasing calcination time, the propane conversion gradually increases, reaching its optimal state at 30 min, with a propane conversion of 35.2% and a propylene selectivity of 91.4%. However, further extending the calcination time to 240 min slightly decreases the propane conversion and propylene selectivity to 35.1% and 90.5%, respectively. Therefore, the calcination time is crucial for restoring catalyst performance, and a carbonization time of 30 min is considered the optimal choice, effectively improving propane conversion and optimizing propylene selectivity.

[0124] (2) The effect of calcination temperature on catalyst regeneration performance in step three of Examples 1, 4, 5 and 17. See Table 2 for specific test results.

[0125] Table 2 Effect of calcination temperature on the regeneration performance of platinum-containing catalysts

[0126]

[0127] Table 2 shows that calcination temperature significantly affects the regeneration performance of platinum-containing catalysts in propane dehydrogenation. For fresh catalysts, the propane conversion is 32%, and the propylene selectivity is 87.6%. At a calcination temperature of 480℃, the propane conversion increases to 35.0%, and the propylene selectivity also improves to 90.8%. With the calcination temperature increasing to 500℃, the propane conversion further increases to 35.2%, and the propylene selectivity reaches 91.4%, exhibiting optimal regeneration performance. However, when the calcination temperature continues to rise to 520℃, the propane conversion decreases significantly to 25.1%, and the propylene selectivity also slightly decreases to 90.1%, indicating that excessively high calcination temperatures may lead to catalyst activity loss. Therefore, calcination temperature has a significant impact on catalyst regeneration, and a calcination temperature of 500℃ provides the best catalyst performance.

[0128] (3) The effect of oxychlorination temperature on catalyst regeneration performance in step four of Examples 1, 6, 7 and 17. See Table 3 for specific test results.

[0129] Table 3 Effect of oxychlorination temperature on the regeneration performance of platinum-containing catalysts

[0130]

[0131] According to the data in Table 3, the oxychlorination temperature has a certain impact on the regeneration performance of the platinum-containing catalyst in the propane dehydrogenation reaction. For the fresh catalyst, the propane conversion is 32%, and the propylene selectivity is 87.6%. When the oxychlorination temperature is 480℃, the propane conversion slightly increases to 33.7%, and the propylene selectivity is 88.5%. At 500℃, the propane conversion further increases to 35.2%, and the propylene selectivity reaches its highest value of 91.4%, showing optimal catalyst performance. However, when the oxychlorination temperature increases to 530℃, the propane conversion slightly decreases to 33.7%, and the propylene selectivity also decreases to 90.5%. This result indicates that the oxychlorination temperature plays an important role in the recovery of catalyst performance, and 500℃ is an ideal temperature that allows the catalyst to achieve optimal propane conversion and propylene selectivity.

[0132] (4) The effect of oxychlorination time on catalyst regeneration performance in Examples 1, 8, 9 and 17. See Table 4 for specific test results.

[0133] Table 4. Effect of oxychlorination time on the regeneration performance of platinum-containing catalysts

[0134]

[0135] According to the data in Table 4, the oxychlorination time significantly affects the propane conversion and propylene selectivity of the platinum-containing catalyst. In the fresh catalyst, the propane conversion is 32% and the propylene selectivity is 87.6%. When the oxychlorination time is 10 minutes, the propane conversion drops to 23.4%, and although the propylene selectivity improves to 90.1%, the catalyst activity is significantly reduced. With the oxychlorination time increased to 30 minutes, the propane conversion recovers to 35.2%, and the propylene selectivity reaches 91.4%, achieving optimal performance. However, when the oxychlorination time is extended to 240 minutes, the propane conversion decreases to 31.1%, and the propylene selectivity also slightly decreases to 89.1%. These results indicate that a moderate oxychlorination time (e.g., 30 minutes) can effectively restore the catalyst activity and optimize propylene selectivity, while excessively long oxychlorination times may lead to partial loss of catalyst activity, affecting its overall performance.

[0136] (5) The effect of reduction temperature on catalyst regeneration performance in Examples 1, 10, 11 and 17. See Table 5 for specific test results.

[0137] Table 5. Effect of reduction temperature on the regeneration performance of platinum-containing catalysts

[0138]

[0139] According to the data in Table 5, the reduction temperature has a relatively small effect on the regeneration performance of the platinum-containing catalyst in the propane dehydrogenation reaction, but there is still a certain trend. For the fresh catalyst, the propane conversion is 32% and the propylene selectivity is 87.6%. When the reduction temperature is 550℃, the propane conversion increases to 34.9% and the propylene selectivity improves to 91.8%. Further increasing the reduction temperature to 600℃, the propane conversion increases slightly to 35.2%, while the propylene selectivity decreases slightly to 91.4%. When the reduction temperature reaches 620℃, the propane conversion increases slightly to 35.3%, but the propylene selectivity decreases slightly again to 90.9%. These results indicate that increasing the reduction temperature helps restore the catalyst activity, but excessively high reduction temperatures may lead to a slight decrease in propylene selectivity. Therefore, a reduction temperature of around 600℃ provides a good balance of catalyst performance.

[0140] (6) The effect of reduction time on catalyst regeneration performance in Examples 1, 12, 13 and 17. See Table 6 for specific test results.

[0141] Table 6. Effect of reduction time on the regeneration performance of platinum-containing catalysts

[0142]

[0143] According to the data in Table 6, the reduction time has a relatively small impact on the regeneration performance of the platinum-containing catalyst in the propane dehydrogenation reaction, but still shows a certain trend. For the fresh catalyst, the propane conversion is 32%, and the propylene selectivity is 87.6%. When the reduction time is 30 min, the propane conversion increases to 35.1%, and the propylene selectivity is 91.2%. As the reduction time is extended to 60 min, the propane conversion further increases to 35.2%, and the propylene selectivity also slightly improves to 91.4%, showing the best propylene selectivity. As the reduction time increases to 240 min, the propane conversion slightly increases to 35.5%, but the propylene selectivity slightly decreases to 91.1%. These results indicate that the reduction time has a certain impact on the catalyst performance, and a reduction time of 60 min provides the best propylene selectivity. A reduction time of 240 min improves the propane conversion, but has a small impact on the propylene selectivity, which may lead to a slight decrease in selectivity.

[0144] (7) The effect of the difference in platinum content on the catalyst regeneration performance in Examples 1, 15, 16, 17, 18 and 19 is shown in Table 7 for specific test results.

[0145] Table 7. Effect of Platinum Content Difference on Regeneration Performance of Platinum-Containing Catalysts

[0146]

[0147] According to the data in Table 7, for catalysts with the same Pt ​​content, the performance of the catalysts was generally improved after regeneration. Taking the catalyst containing 0.1% platinum as an example, the propane conversion rate increased from 15.1% of the fresh catalyst to 16.2% of the deactivated catalyst, and the propylene selectivity also increased from 88.6% to 92.3%. Similarly, for the catalyst containing 0.3% platinum, the propane conversion rate increased from 32% to 35.2% and the propylene selectivity increased from 87.6% to 91.4% after deactivation. For the catalyst containing 2% platinum, the propane conversion rate increased from 49.3% to 51.5% and the propylene selectivity increased from 89.6% to 91.0% after regeneration. These data show that catalysts with different Pt contents all showed improved propane conversion rate and propylene selectivity after regeneration, indicating that the regeneration method can effectively restore the activity of the catalyst.

[0148] (8) The effect of the difference in chlorine content on the catalyst regeneration performance in Examples 1, 17, 20, 21 and 22. See Table 8 for specific test results.

[0149] Table 8. Effect of Chlorine Content Difference on Regeneration Performance of Platinum-Containing Catalysts

[0150]

[0151] According to the data in Table 8, the difference in chlorine content significantly affected the propane conversion and propylene selectivity of the platinum-containing catalyst. For the fresh catalyst, the propane conversion was 32% and the propylene selectivity was 87.6%. When the chlorine content was 0 ppm, the propane conversion decreased significantly to 17.2%, but the propylene selectivity increased significantly to 93.3%. With increasing chlorine content, the propane conversion gradually recovered, reaching 35.2% at a chlorine content of 700 ppm, and the propylene selectivity was 91.4%. At a chlorine content of 1000 ppm, the propane conversion decreased slightly to 34.25%, and the propylene selectivity also decreased slightly to 89.9%. These results indicate that chlorine content has a certain optimizing effect on the regeneration performance of the catalyst; an appropriate amount of chlorine (e.g., 700 ppm) can improve the propane conversion and maintain a high propylene selectivity. However, excessively high chlorine content (e.g., 1000 ppm) may negatively affect the propylene selectivity, even though the propane conversion remains high. Therefore, proper control of the chlorine content is crucial for improving the overall performance of the catalyst.

[0152] (9) The effect of the difference in the type of chlorine-containing organic gas G1 introduced in Examples 1, 17 and 23 on the catalyst regeneration performance is shown in Table 9 for specific test results.

[0153] Table 9. Effects of the type of chlorine gas G1 on the regeneration performance of platinum-containing catalysts.

[0154]

[0155] According to the data in Table 9, different types of G1 gas have a relatively small impact on the regeneration performance of platinum-containing catalysts. In fresh catalyst containing 0.3% platinum, the propane conversion rate is 32%, and the propylene selectivity is 87.6%. When chlorinated organic compounds are introduced into the deactivated catalyst under nitrogen as the carrier gas, the propane conversion rate is 35.2%, and the propylene selectivity is 91.4%; while when air is used as the carrier gas, the propane conversion rate is 34.9%, and the propylene selectivity is 91.9%. The propane conversion rate and propylene selectivity under the two gas conditions are very close, and the difference is within the experimental error range. This indicates that under the same chlorine source concentration, the type of G1 gas has no significant impact on the catalyst regeneration effect. The catalyst performance is mainly controlled by the chlorine source, rather than the type of carrier gas itself.

[0156] (10) In Examples 1, 17, 24 and 25, the effect of the difference in oxygen concentration in the mixed gas on the catalyst regeneration performance after oxygen-containing gas G2 is introduced into the reactor is shown in Table 10.

[0157] Table 10. Effect of oxygen concentration difference in mixed gas on regeneration performance of platinum-containing catalyst.

[0158]

[0159] Table 10 shows that the oxygen concentration in the mixed gas has a certain impact on the regeneration performance of platinum-containing catalysts, but there is a clear optimal range. Compared with the fresh catalyst containing 0.3% platinum, the propane conversion rate of the deactivated catalyst after regeneration under low oxygen concentration (2%) is only 28.1%, lower than that of the fresh catalyst, indicating that the regeneration effect is limited when oxygen is insufficient. As the oxygen concentration increases to 10%, the propane conversion rate significantly increases to 35.2%, while the propylene selectivity remains at 91.4%, indicating that a moderate oxygen concentration is beneficial to the synergistic recovery of catalyst activity and selectivity. However, when the oxygen concentration is further increased to 21%, the propane conversion rate decreases to 30.4%, although the propylene selectivity slightly increases to 92.1%, indicating that excessively high oxygen concentrations may cause metal sintering or over-oxidation, thus hindering activity recovery. Overall, the oxygen concentration has a "first increase, then decrease" trend in its effect on catalyst regeneration performance, with an oxygen concentration of approximately 10% being more conducive to achieving better regeneration results.

[0160] (11) The catalysts in Examples 1, 17, 26, and 27 after multiple regeneration cycles; specific test results are shown in Table 11 and Figure 1 .

[0161] Table 11 Regeneration performance of platinum-containing catalysts after multiple cycles of regeneration

[0162]

[0163] Figure 1 This is a comparison chart of the propane dehydrogenation performance of the platinum-containing catalysts in Examples 1, 17, 26, and 27 of this invention after regeneration. (Based on Table 11 and...) Figure 1 The data show that the catalyst containing 0.3% platinum maintained good performance after multiple regeneration cycles, with almost no significant decrease in propane conversion and propylene selectivity. The fresh catalyst had a propane conversion of 32.0% and a propylene selectivity of 87.6%. After one regeneration, the propane conversion increased to 35.2% and the propylene selectivity to 91.4%. After the second regeneration, the propane conversion slightly decreased to 34.1%, but the propylene selectivity remained at 92.3%. After the third regeneration, the propane conversion rebounded to 35.1% and the propylene selectivity to 90.5%. These data indicate that after multiple regeneration cycles, the propane conversion and propylene selectivity of the catalyst remained essentially stable, demonstrating that the method described in this invention can significantly improve the catalyst regeneration effect.

[0164] In summary, this invention achieves controllable adjustment and long-term stable maintenance of ppm-level chlorine content in the regeneration atmosphere without relying on ultra-low flow precision injection equipment by stably and continuously introducing the chlorinating agent in the form of steam into the reactor. This effectively solves the problems of insufficient chlorinating agent dosing precision and large fluctuations in small and laboratory-scale reactors. This method can perform mild and uniform regeneration of Pt-based catalysts under high-temperature oxygen-containing conditions, significantly improving catalyst stability and lifespan. Furthermore, the device of this invention has a simple structure, high operational safety, wide applicability, good repeatability, and engineering scale-up potential, making it suitable for widespread application in propane dehydrogenation reaction systems of different scales.

[0165] The technical solutions disclosed and proposed in this invention can be implemented by those skilled in the art by appropriately modifying the conditions and routes, etc. Although the methods and preparation techniques of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.

Claims

1. A method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor, characterized in that, include: (1) Add chlorinating agent to the bubbler, which is placed in a circulating cooler, and adjust the circulating constant temperature water bath to the preset temperature; (2) The inlet of the bubbler is connected to a preset gas G1, and the outlet of the bubbler is connected to the inlet of the reactor; (3) The deactivated platinum-tin dehydrogenation catalyst is placed in the reactor, the reactor is heated to the calcination temperature, and calcined in an oxygen-containing atmosphere; (4) Adjust the reactor to the oxychlorination temperature, set the flow rate of the preset gas G1 to the preset flow rate, and introduce oxygen-containing gas G2 into the reactor so that the chlorinating agent in the inflow section of the reactor is stabilized at the preset concentration, and maintain this condition for a period of time. (5) The reactor and pipeline are purged with protective gas to replace the gas. (6) Adjust the reactor to the reduction temperature and introduce reducing gas G3 into the reactor. After the reduction reaction occurs, the regenerated platinum-tin dehydrogenation catalyst is obtained.

2. The method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor according to claim 1, characterized in that, The preset temperature in step (1) and the preset flow rate in step (4) are calculated based on the preset concentration of the chlorinating agent in the inflow section of the reactor and the saturated vapor pressure of the chlorinating agent.

3. The method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor according to claim 1, characterized in that, The chlorinating agent in step (1) is dichloroethane.

4. The method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor according to claim 1, characterized in that, The preset gas G1 in step (2) is nitrogen or air.

5. The method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor according to claim 1, characterized in that, The mass fraction of the platinum-tin dehydrogenation catalyst in step (3) is 0.1-2.0%.

6. The method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor according to claim 1, characterized in that, The calcination temperature in steps (1) and (3) is 450-530℃, and the calcination time in step (3) in an oxygen-containing atmosphere is 10-240 min.

7. The method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor according to claim 1, characterized in that, The oxychlorination temperature in step (4) is 480-530℃, and the treatment time under the conditions in step (4) is 10-240 min.

8. The method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor according to claim 1, characterized in that, The oxygen concentration in the mixture of preset gas G1 and oxygen-containing gas G2 in step (4) is 2% to 21%.

9. The method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor according to claim 1, characterized in that, The reduction temperature in step (6) is 550-620℃, and the reduction reaction takes 30-240 min.

10. The method for regenerating a platinum-tin dehydrogenation catalyst using chlorinating agent vapor according to claim 1, characterized in that, The reducing gas G3 in step (6) is a hydrogen-containing gas.

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