Regeneration method of carbon deposition molecular sieve catalyst
By regenerating carbonized molecular sieve catalysts using a low-temperature, low-pressure plasma ashing method, the problem of catalyst deactivation due to carbon buildup was solved, catalytic activity was restored, catalytic performance was improved, and structural damage caused by traditional high-temperature calcination was avoided.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XUZHOU COLLEGE OF INDAL TECH
- Filing Date
- 2026-04-10
- Publication Date
- 2026-05-12
AI Technical Summary
During the catalytic pyrolysis of lignite, the catalyst is prone to carbon deposition and deactivation. Traditional high-temperature calcination regeneration methods lead to catalyst particle sintering and agglomeration and changes in molecular sieve structure, which reduce catalytic activity.
The carbonized molecular sieve catalyst was regenerated using a low-temperature, low-pressure plasma ashing method. The carbonized molecular sieve catalyst powder was treated with a low-pressure plasma generator at a temperature below 200°C using an oxygen atmosphere. The completion of regeneration was determined based on the change in catalyst mass.
It significantly improves the catalytic activity of the catalyst, avoids the damage to the catalyst structure caused by traditional high-temperature calcination, restores the yield of light aromatics and gaseous products of the catalyst, and its performance is close to or better than that of fresh catalyst.
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Figure CN122006801A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst regeneration, and more specifically to a method for regenerating carbonized molecular sieve catalysts. Background Technology
[0002] my country has abundant lignite reserves, but it is characterized by high moisture, high ash content, high oxygen content, and low calorific value. Direct combustion or gasification is not only inefficient but also causes severe pollution. Pyrolysis is an effective way to cleanly and efficiently utilize lignite, yielding semi-coke, gas, and tar. However, traditional coal pyrolysis processes produce complex tar products with low selectivity for light aromatics, and heavy tar easily causes equipment blockage. Therefore, using suitable catalysts to catalytically reform the pyrolysis volatiles during pyrolysis can promote reactions such as cracking, deoxygenation, and aromatization, thereby significantly improving the selectivity and yield of light aromatics. This can provide an alternative for producing liquid fuels and fine chemicals from non-petroleum resources.
[0003] Currently, the key to catalytic pyrolysis of lignite is solving the problem of catalyst deactivation due to carbon deposition. The main causes of carbon deposition are: (1) Acidic centers on the catalyst surface can trigger side reactions (polymerization, cyclization, and aromatization), generating large molecules such as polycyclic aromatic hydrocarbons. These molecules are difficult to diffuse out of the catalyst micropores to form carbon deposits, covering the active centers and blocking the pores; (2) A large number of oxygen-containing functional groups and unsaturated hydrocarbons generated by the pyrolysis of lignite with high oxygen content and high volatile content undergo condensation reactions during the catalytic process, forming heavy tar and carbon deposit precursors, which eventually form carbon deposits. The traditional method for regenerating carbon deposit catalysts is high-temperature calcination, but multiple high-temperature calcination processes can cause the molecular sieve catalyst particles to sinter and agglomerate. In addition, the combustion of carbon deposits during calcination will generate local high temperatures, leading to changes in the molecular sieve structure, thereby reducing catalytic activity.
[0004] Based on this, many scholars have conducted extensive research on solving the carbon deposition problem. For example, patent CN121103413A discloses a method to improve the selectivity of light aromatics in the biomass pyrolysis products catalyzed by zeolite molecular sieve catalysts. This method introduces mesopores into the molecular sieve through alkali treatment or hard template method, thereby improving mass transfer and reducing carbon deposition. Patent CN120984319A discloses a modified ZSM-5 molecular sieve catalyst and its preparation method and application. This method reduces carbon deposition by supporting metal modification to promote the hydrogen transfer reaction of pyrolysis free radical fragments at the metal site. However, although the above methods can improve the catalyst's resistance to carbon deposition, the phenomenon of rapid catalyst deactivation still exists. Therefore, catalyst regeneration is essential to improve the economics of the entire process. Summary of the Invention
[0005] The purpose of this invention is to provide a method for regenerating carbon-deposited molecular sieve catalysts. This method can solve the problem of carbon deposition and deactivation of molecular sieve catalysts for the catalytic pyrolysis of lignite to produce aromatics, and significantly improve the catalytic activity of the regenerated catalyst.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for regenerating a carbonized molecular sieve catalyst, comprising the following steps: S1. Collect the carbonized molecular sieve catalyst after the reaction of lignite catalytic pyrolysis to produce aromatics, grind the carbonized molecular sieve catalyst to obtain carbonized molecular sieve catalyst powder. S2. The carbonized molecular sieve catalyst powder obtained in step S1 is placed in a low-pressure plasma generator for ashing and regeneration treatment, with a maximum treatment temperature of 200°C. o C, the atmosphere is O2; S3. The regeneration process is considered complete based on the change in the mass of the catalyst. When the difference between the two weighings of the carbonized catalyst is less than 1% of the mass of the carbonized molecular sieve catalyst collected in step S1, the low-pressure plasma ashing regeneration process is considered complete.
[0007] Preferably, in step S1, the carbon-depositing molecular sieve catalyst is a carbon-depositing silicon-aluminum molecular sieve.
[0008] Preferably, in step S1, the carbon-depositing molecular sieve catalyst is a carbon-depositing ZSM-5 molecular sieve catalyst, a carbon-depositing HY molecular sieve catalyst, or a carbon-depositing MCM-11 molecular sieve catalyst.
[0009] Preferably, in step S1, the carbonized molecular sieve catalyst is ground to a particle size of less than 75 μm.
[0010] Preferably, in step S2, the low-pressure plasma generator has a frequency of 40 kHz and an O2 flow rate of 13 mL / min.
[0011] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a low-temperature ashing method from materials science to treat carbon-deactivated molecular sieve catalysts. The performance of catalysts regenerated using conventional calcination and low-pressure plasma ashing were compared. The results demonstrate that the performance of catalysts regenerated by low-pressure plasma ashing is superior to that regenerated by conventional calcination. This invention effectively solves the problem of catalyst particle sintering and agglomeration caused by multiple calcinations in the traditional high-temperature calcination regeneration process. Simultaneously, it avoids the problem of localized high temperatures on the molecular sieve surface due to the intense exothermic combustion of carbon deposits, which leads to molecular sieve framework collapse and structural changes, thus significantly improving the catalytic activity of the regenerated catalyst. Attached Figure Description
[0012] Figure 1Schematic diagram of the distribution of light aromatics (a) and gaseous products (b) produced by the pyrolysis of fresh and carbon-deposited ZSM-5 catalytic lignite; Figure 2 Schematic diagram of the distribution of light aromatics (a) and gaseous products (b) produced by pyrolysis of fresh and carbon-regenerated HY catalytic lignite; Figure 3 A schematic diagram showing the distribution of light aromatics (a) and gaseous products (b) produced by the pyrolysis of fresh and carbon-regenerated MCM-41 catalytic lignite. Detailed Implementation
[0013] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0014] The apparatus and method for obtaining the carbon-depositing molecular sieve catalyst are described in the following examples: The lignite catalytic pyrolysis to aromatics experiment described in this invention is conducted in a fixed-bed reactor. The apparatus mainly consists of five parts: a gas supply unit, a feed unit, a pyrolysis reaction unit, a temperature control unit, and a product collection unit. The gas supply unit purges the entire apparatus with argon (Ar) to maintain an inert atmosphere in the reaction system. Lignite feedstock is fed into the pyrolysis zone of the reactor at a rate of 0.1 g / min via a feed bottle. The pyrolysis volatiles are purged to the catalyst bed by Ar carrier gas for catalytic reforming. The pyrolysis reactor uses a 360 mm long, 22 mm inner diameter quartz tube, and the pyrolysis zone and catalytic reforming zone are separated by quartz wool. The reactor is equipped with a programmed temperature control system to precisely regulate the reaction temperature. The product collection unit is divided into tar collection and gas collection sections: tar is collected in cold traps cooled by ethylene glycol circulation. Four cold traps are filled with 40 mL, 30 mL, 30 mL, and 20 mL methanol solutions and appropriate amounts of glass beads, respectively, to ensure complete tar collection. The gas generated in the reaction is collected by a gas sampling bag at the end of the cold traps.
[0015] The material will undergo pre-calcination treatment (calcination pre-treatment temperature is 550°C). o 3.0 g of ZSM-5 molecular sieve catalyst (in an O2 atmosphere) was granulated and loaded into the catalytic reforming zone of the reactor. The lignite feed rate was set to 0.1 g / min, the reaction pressure to 0.1 MPa, and the reaction temperature to 600 ℃. The catalytic pyrolysis of lignite to produce aromatics was carried out under an Ar atmosphere, with the reactants' residence time in the catalyst bed controlled to 1 s. After 30 min of reaction, the products were qualitatively and quantitatively analyzed, and the yields of light aromatics and gaseous products were calculated to complete the fresh catalyst performance evaluation experiment. After the experiment, the lignite feed and heating system were stopped sequentially. After the reactor cooled to room temperature, the Ar gas source was turned off, the reactor was disassembled, and the carbonized ZSM-5 molecular sieve catalyst was removed. Carbonized HY molecular sieve catalyst and carbonized MCM-11 molecular sieve catalyst were prepared using the same method.
[0016] The fresh ZSM-5 molecular sieve catalyst, fresh HY molecular sieve catalyst, and fresh MCM-41 molecular sieve catalyst used in the following examples all refer to catalysts that have undergone calcination pretreatment (calcination pretreatment temperature is 550°C). o The catalyst is obtained after being shaped (C, atmosphere is O2). Example 1
[0017] A method for regenerating a carbonized molecular sieve catalyst includes the following steps: S1. Collect 1g of the above-mentioned carbonized ZSM-5 molecular sieve catalyst and grind it until the particle size is less than 75μm to prepare carbonized ZSM-5 molecular sieve catalyst powder. S2. The carbonized ZSM-5 molecular sieve catalyst powder is placed in a low-pressure plasma generator for ashing and regeneration treatment at a temperature below 200°C. o C, the reaction atmosphere is pure oxygen (O2), the flow rate is 13 mL / min, and the frequency of the low-pressure plasma generator is 40 kHz; S3. The change in catalyst mass is used as the basis for judging the end point of regeneration. When the difference between two consecutive weighings of the catalyst is less than 0.01 g, the low-pressure plasma ashing regeneration is completed.
[0018] Comparative Example 1 Collect 1g of the above-mentioned carbonized ZSM-5 molecular sieve catalyst and regenerate it using a conventional high-temperature calcination method, with the treatment temperature controlled at 550°C. o C, the treatment atmosphere is pure oxygen, and the treatment time is 1 h; after calcination and regeneration, the catalytic performance is evaluated under the same conditions.
[0019] The performance evaluation experiments for lignite pyrolysis to aromatics were conducted under identical reaction conditions using fresh ZSM-5 molecular sieve catalyst, the low-pressure plasma ashing regenerated catalyst obtained in Example 1, and the conventional calcination regenerated catalyst obtained in Comparative Example 1. Detailed results are attached. Figure 1 As can be seen from the figure, the total yield of light aromatics from the low-pressure plasma ashing regeneration catalyst is 4.78% higher than that from the conventional calcination regeneration catalyst. Example 2
[0020] Replace the “carbon-deposited ZSM-5 molecular sieve catalyst” in step S1 with the “carbon-deposited HY molecular sieve catalyst”, and keep the rest of the regeneration process the same as in Example 1.
[0021] Comparative Example 2 The "Carbonized ZSM-5 molecular sieve catalyst" in Comparative Example 1 was replaced with "Carbonized HY molecular sieve catalyst", and the other regeneration processes remained the same as in Comparative Example 1.
[0022] The performance evaluation experiments for lignite pyrolysis to aromatics were conducted under identical reaction conditions using fresh HY molecular sieve catalyst, the low-pressure plasma ashing regenerated catalyst obtained in Example 2, and the conventional calcination regenerated catalyst obtained in Comparative Example 2. Detailed results are attached. Figure 2 As can be seen from the figure, the total yield of light aromatics from the low-pressure plasma ashing regeneration catalyst is 10.79% higher than that from the conventional calcination regeneration catalyst. Example 3
[0023] Replace the “carbon-deposited ZSM-5 molecular sieve catalyst” in step S1 with the “carbon-deposited MCM-41 molecular sieve catalyst”, and keep the rest of the regeneration process the same as in Example 1.
[0024] Comparative Example 3 The “Carbonized ZSM-5 molecular sieve catalyst” in Comparative Example 1 was replaced with “Carbonized MCM-41 molecular sieve catalyst”, and the rest of the regeneration process remained the same as in Comparative Example 1.
[0025] The performance evaluation experiments for lignite pyrolysis to aromatics were conducted under identical reaction conditions using fresh MCM-41 molecular sieve catalyst, the low-pressure plasma ashing regenerated catalyst obtained in Example 3, and the conventional calcination regenerated catalyst obtained in Comparative Example 3. Detailed results are attached. Figure 3 As can be seen from the figure, the total yield of light aromatics from the low-pressure plasma ashing regeneration catalyst is 9.19% higher than that from the conventional calcination regeneration catalyst.
[0026] From the appendix Figure 1 ~Attached Figure 3 As can be seen, the low-pressure plasma ashing regeneration method described in this invention was used to regenerate three molecular sieve catalysts (ZSM-5, HY, and MCM-41) that had become deactivated due to carbon buildup after the catalytic pyrolysis of lignite to produce aromatics. Catalytic performance was tested under the same evaluation conditions. The results showed that the regenerated catalysts had catalytic performance close to that of the fresh catalysts, and all exhibited significant improvements compared to the traditional high-temperature calcination regenerated catalysts. Traditional high-temperature calcination regenerated molecular sieve catalysts, when used in the lignite pyrolysis to produce aromatics reaction, resulted in lower yields of light aromatics and gaseous products compared to the fresh catalysts. After low-pressure plasma ashing regeneration according to this invention, the catalytic activity of all three molecular sieve catalysts was efficiently restored, with no significant difference in performance compared to the fresh catalysts. Among them, the attached… Figure 1 As can be seen, the ZSM-5 molecular sieve catalyst regenerated using the regeneration method proposed in this invention exhibits a higher yield of light aromatics than the fresh ZSM-5 molecular sieve catalyst, and the gaseous product yield is also significantly improved, indicating that the catalyst activity did not decline after regeneration. (See attached...) Figure 2As can be seen, the HY molecular sieve catalyst regenerated using the regeneration method proposed in this invention achieves a light aromatic hydrocarbon yield that is essentially the same as that of fresh HY molecular sieve, while the gas yield is slightly lower than that of fresh catalyst, but significantly higher than that of HY molecular sieve regenerated using the traditional calcination method. (See attached...) Figure 3 It can be seen that the MCM-41 molecular sieve catalyst regenerated using the regeneration method proposed in this invention has a light aromatic hydrocarbon yield comparable to that of fresh MCM-41 molecular sieve, and a gas yield slightly lower than that of fresh catalyst, but about twice the gas yield of MCM-41 molecular sieve regenerated by the traditional calcination method.
[0027] In summary, as can be seen from the above examples, the low-pressure plasma low-temperature ashing regeneration method provided by this invention can efficiently restore the catalytic performance of carbon-deactivated molecular sieve catalysts used in lignite pyrolysis to produce aromatics. It is applicable to the three commonly used industrial molecular sieves: ZSM-5, HY, and MCM-41. The yield of light aromatics from the regenerated catalyst can reach the level of the fresh catalyst. Among them, the activity of the regenerated ZSM-5 molecular sieve is even better than that of the fresh catalyst, demonstrating excellent potential for industrial application.
Claims
1. A method for regenerating a carbonized molecular sieve catalyst, characterized in that, Includes the following steps: S1. Collect the carbonized molecular sieve catalyst after the reaction of lignite catalytic pyrolysis to produce aromatics, grind the carbonized molecular sieve catalyst to obtain carbonized molecular sieve catalyst powder. S2. The carbonized molecular sieve catalyst powder obtained in step S1 is placed in a low-pressure plasma generator for ashing and regeneration treatment, with a maximum treatment temperature of 200°C. o C, the atmosphere is O2; S3. The regeneration process is considered complete based on the change in the mass of the catalyst. When the difference between the two weighings of the carbonized molecular sieve catalyst is less than 1% of the mass of the carbonized molecular sieve catalyst collected in step S1, the low-pressure plasma ashing regeneration process is considered complete.
2. The method for regenerating a carbonized molecular sieve catalyst according to claim 1, characterized in that, In step S1, the carbon-depositing molecular sieve catalyst is a carbon-depositing silicon-aluminum molecular sieve.
3. The method for regenerating a carbonized molecular sieve catalyst according to claim 1, characterized in that, In step S1, the carbon-depositing molecular sieve catalyst is a carbon-depositing ZSM-5 molecular sieve catalyst, a carbon-depositing HY molecular sieve catalyst, or a carbon-depositing MCM-11 molecular sieve catalyst.
4. In the regeneration method of the carbon-deposited molecular sieve catalyst according to claim 1, in step S1, the carbon-deposited molecular sieve catalyst is ground to a particle size of less than 75 μm.
5. In the regeneration method of the carbonized molecular sieve catalyst according to claim 1, in step S2, the frequency of the low-pressure plasma generator is 40 kHz and the O2 flow rate is 13 mL / min.