Regeneration method of metal modified mordenite catalyst for methanol amination reaction

Abstract

The invention discloses a regeneration method of a metal modified mordenite catalyst used in a methanol amination reaction, and belongs to the technical field of catalyst regeneration. The catalyst regeneration method comprises the following steps: firstly, removing non-framework aluminum in a catalyst by using an organic acid solution, and then washing by using an organic solvent to remove residual organic acid and part of carbon deposit after acid treatment; oxidizing carbon deposit on the surface of the catalyst by adopting a hydrogen peroxide solution and inert mixed gas containing ozone; and finally, reducing active metal components in the catalyst by adopting hydrogen. According to the regeneration method, carbon deposit on the surface of the catalyst can be well and effectively removed under the low-temperature condition, generation of non-framework aluminum on the surface of mordenite in the regeneration process is reduced, the service life of the catalyst is effectively prolonged, and the regenerated catalyst can keep good reaction performance in the methanol amination reaction.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst regeneration, and in particular relates to a regeneration method of a metal-modified mordenite catalyst used in a methanol amination reaction. Background Art

[0002] Methylamine is an important fine chemical product, often used as an intermediate for water treatment agents, pesticides, drugs, surfactants and solvents. The route of preparing methylamine by methanol amination has become the main way to produce methylamine in an industrial scale due to its advantages such as easy availability of raw materials, low price, and environmentally friendly process. Limited by thermodynamic equilibrium, the proportion of methanol amination reaction catalyzed by equilibrium catalysts such as zirconium oxide and tungsten oxide to produce monomethylamine (MMA), dimethylamine (DMA) and trimethylamine (TMA) can no longer meet market demand. Therefore, zeolites such as mordenite (MOR) and ZSM-5 with shape-selective catalytic function have become research hotspots in recent years.

[0003] The reaction mechanism of alcohol amination generally includes three consecutive steps: 1) alcohol dehydrogenation to form aldehydes / ketones; 2) aldehydes / ketones and ammonia CN coupling to form imines; 3) imine hydrogenation to form amines. In the alcohol amination process, the dehydrogenation step is considered to be the rate-determining step. The use of alkaline earth metals and transition metals to modify the mordenite catalyst can improve the reaction performance of methanol amination from the aspects of modifying the pore structure, regulating the acid properties, and increasing the dehydrogenation active sites. However, with the continuous extension of the reaction time, the selectivity of trimethylamine and the conversion rate of methanol gradually decrease. The main reasons for the deactivation of this catalyst are the following three aspects: 1) Coke formation: organic matter adsorbed on the surface of the catalyst will coke and form carbon, resulting in the pore structure of the catalyst being blocked and the reactive active sites being covered; 2) Sintering of metal elements: high temperature and high pressure reaction conditions cause the metal particles to agglomerate and reduce the active sites; 3) Zeolite framework dealumination: water vapor generated in the reaction system, although it can gasify part of the coke, will cause the zeolite framework to dealumination and form amorphous aluminum species.

[0004] The commonly used method for removing coke from the catalyst surface in industry is to remove coke by high-temperature oxidation with controlled oxygen concentration. Although it can avoid local overheating caused by coke oxidation during the regeneration process, this regeneration method is carried out under high temperature conditions, which will still aggravate zeolite dealumination and metal sintering. Therefore, the most ideal regeneration method for metal-modified mordenite catalysts used in methanol amination is to combine low-temperature controlled combustion of coke, removal of non-framework aluminum and reduction of transition metal elements. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a method for regenerating a metal-modified mordenite catalyst used in a methanol amination reaction.

[0006] The present invention is achieved by adopting the following technical solutions: The regeneration method of the metal-modified mordenite catalyst used in the methanol amination reaction of the present invention comprises the following steps: firstly removing non-framework aluminum from the metal-modified mordenite with decreased activity by using an organic acid solution, then washing, filtering and drying the catalyst by using an organic solvent, and then loading the dried catalyst into a fixed bed, introducing a hydrogen peroxide solution and an inert mixed gas containing ozone for low-temperature oxidation and hydrogen reduction treatment, and finally obtaining a regenerated catalyst.

[0007] A method for regenerating a metal-modified mordenite catalyst used in a methanol amination reaction comprises the following steps: 1) soaking the metal-modified mordenite catalyst with reduced activity in an organic acid solution in sequence, and then filtering and drying; 2) Wash the dried catalyst with an organic solvent, filter and dry it. 3) The dried and cooled catalyst is loaded into a fixed bed reactor, and the reactor temperature is first raised to 70-90°C under an inert atmosphere. When the temperature is stable, a hydrogen peroxide solution is introduced for treatment for 10-16 hours; 4) Introduce inert gas to purge the pipeline and raise the temperature of the reactor to 105-115°C. After the temperature stabilizes for 2 hours, continuously introduce an inert mixed gas containing ozone for 6-24 hours; 5) Introduce inert gas to purge the pipeline and raise the temperature of the reactor to 400-550°C. After the temperature is stable for 0.5-1 hour, continuously introduce hydrogen for 6-20 hours to obtain a regenerated catalyst. Based on the above technical solution, further, the mass of alkaline earth metal elements accounts for 20% to 60% of the mass of mordenite; the mass of transition metal elements accounts for 1% to 5% of the mass of mordenite; the silicon-aluminum ratio of the mordenite is 5 to 60; the alkaline earth metal elements are selected from one or more of barium and calcium, and the transition metal elements are selected from one or more of nickel, cobalt, copper and zinc.

[0008] Based on the above technical solution, further, the organic acid solution is selected from one or more of 4-chloro-3-nitrobenzoic acid, p-nitrotoluene sulfonic acid, 4-bromophthalic acid, and 2,2'-dithiodibenzoic acid, and the pH range of the organic acid solution is 4 to 6.

[0009] Based on the above technical solution, further, the organic solvent is selected from one or more of ethanol, ether and chloroform.

[0010] Based on the above technical solution, further, the concentration of the hydrogen peroxide solution is 5% to 20%.

[0011] Based on the above technical solution, further, the concentration of the oxidizing gas in the inert atmosphere containing ozone is 3% to 50%, preferably 20% to 30%. The inert atmosphere is one of argon, nitrogen, and helium, or a combination of two or more thereof.

[0012] Based on the above technical solution, further, the hydrogen peroxide treatment temperature is 70-90°C.

[0013] Based on the above technical solution, further, the hydrogen peroxide treatment time is 10 to 16 hours.

[0014] Based on the above technical solution, further, the treatment temperature of the ozone-containing inert gas is 105-115°C.

[0015] Based on the above technical solution, further, the treatment time of the ozone-containing inert gas is 6 to 24 hours.

[0016] Based on the above technical solution, further, the hydrogen treatment temperature is 400-550°C.

[0017] Based on the above technical solution, further, the hydrogen treatment time is 6 to 20 hours.

[0018] Based on the above technical solution, further, the heating rate is 1 to 40°C / min.

[0019] Based on the above technical solution, further, the regeneration pressure is normal pressure.

[0020] On the other hand, the present invention provides a method for preparing methylamine by catalytic methanol amination, comprising the following steps: loading a catalyst in a fixed bed reactor, first introducing hydrogen for pretreatment for 0.5-1.0 h, then introducing a mixed liquid of methanol and liquid ammonia into a preheater for vaporization, and then introducing the mixed liquid into a fixed bed reactor for reaction to obtain a mixed product of different methylamines.

[0021] Based on the above technical solution, further, the vaporization temperature is 200-300°C.

[0022] Based on the above technical solution, further, the reaction temperature is 350-450°C.

[0023] Based on the above technical solution, further, the reaction pressure is 1 to 3 MPa.

[0024] Based on the above technical solution, further, the molar ratio of liquid ammonia to methanol is 1.2 to 2:1.

[0025] The regeneration method of the metal-modified mordenite catalyst of the present invention can well remove carbon deposits on the catalyst surface and reduce the generation of non-framework aluminum at low temperature, and can realize the regeneration process at a low temperature of 105-115, effectively extending the service life of the catalyst. The regenerated catalyst has good stability in the methanol amination reaction, and the reaction activity is basically restored to the level of the fresh catalyst, which is of great significance to the continuous industrial production of methylamine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a test chart of the stability performance of the regenerated catalyst in Example 6 of the present invention in the reaction of preparing trimethylamine by methanol amination. DETAILED DESCRIPTION

[0027] The content of the present invention is further described below in conjunction with specific embodiments and comparative examples, but the implementation manner of the present invention is not limited thereto, and other similar embodiments all belong to the protection scope of the present invention.

[0028] Example 1 The Ba and Ni metal element modified mordenite catalyst is prepared by impregnation method and extrusion molding with silica sol as a binder. The fresh Ba and Ni metal element modified mordenite is loaded into a fixed bed reactor for methanol amination to prepare methylamine. When the conversion rate of methanol is reduced to 80%, the feeding and heating are stopped, and N2 is continuously introduced for purging. When the temperature drops to room temperature and the fixed bed pressure drops to normal pressure, the trimethylamine catalyst with reduced activity is taken out for use.

[0029] Example 2 The trimethylamine catalyst with reduced activity in Example 1 was immersed in a 4-chloro-3-nitrobenzoic acid solution at 80°C and pH=5. After soaking for 5 hours, the catalyst was filtered out and dried at 110°C for 10 hours. The acid-treated catalyst was then washed with ethanol, filtered and dried at 110°C for 4 hours. The dried and cooled catalyst was then loaded into a fixed bed reactor. The reactor temperature was raised to 90°C at a heating rate of 5°C / min under a N2 atmosphere. After the regeneration temperature was stabilized for 0.5 hours, 0.50 mL / min of 10% hydrogen peroxide solution was introduced for treatment for 10 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 110°C at a heating rate of 5°C / min. After the regeneration temperature was stabilized for 2 hours, 0.6 mL / min of 20% O3-N2 mixed gas was introduced for regeneration for 20 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 450°C at a heating rate of 5°C / min. The regeneration temperature was stabilized for 0.5 hours. h later, H2 with a volume flow rate of 0.4 mL / min was introduced for 10 h. The regeneration pressure was atmospheric pressure. After the catalyst was regenerated, methanol amination reaction was carried out. The molar ratio of the reaction raw materials was liquid ammonia: methanol = 2:1, the reaction pressure was 2 MPa, the vaporization temperature was 280 °C, the reaction temperature was 400 °C, and the liquid hourly volume space velocity was 1.3 h -1 After 2 h of reaction, samples were taken every 1 h for gas chromatography analysis. The average value of the analysis data of 6 parallel samples was taken. The results are shown in Table 1.

[0030] Example 3 The trimethylamine catalyst with reduced activity in Example 1 was immersed in a para-nitrotoluene o-sulfonic acid solution at 80°C and pH=5. After soaking for 5 hours, the catalyst was filtered out and dried at 110°C for 10 hours. The acid-treated catalyst was then washed with ether, filtered and dried at 110°C for 4 hours. The dried and cooled catalyst was then loaded into a fixed bed reactor. The reactor temperature was raised to 90°C at a heating rate of 5°C / min under a N2 atmosphere. After the regeneration temperature was stabilized for 0.5 hours, 0.50 mL / min of 10% hydrogen peroxide solution was introduced for treatment for 10 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 110°C at a heating rate of 5°C / min. After the regeneration temperature was stabilized for 2 hours, 0.6 mL / min of 20% O3-N2 mixed gas was introduced for regeneration for 20 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 450°C at a heating rate of 5°C / min. After the regeneration temperature was stabilized for 0.5 hours, a volume flow rate of 0.4 mL / min H2 treatment for 10 h. The regeneration pressure was atmospheric pressure. After the catalyst was regenerated, methanol amination reaction was carried out. The molar ratio of the reaction materials was liquid ammonia: methanol = 2:1, the reaction pressure was 2 MPa, the vaporization temperature was 280 °C, the reaction temperature was 400 °C, and the liquid hourly volume space velocity was 1.3 h -1After 2 h of reaction, samples were taken every 1 h for gas chromatography analysis. The average value of the analysis data of 6 parallel samples was taken. The results are shown in Table 1.

[0031] Example 4 The trimethylamine catalyst with reduced activity in Example 1 was immersed in a 4-bromophthalic acid solution at 80°C and pH=5. After soaking for 5 hours, the catalyst was filtered out and dried at 110°C for 10 hours. The acid-treated catalyst was then washed with chloroform, filtered and dried at 110°C for 4 hours. The dried and cooled catalyst was then loaded into a fixed bed reactor. The reactor temperature was raised to 90°C at a heating rate of 5°C / min under a N2 atmosphere. After the regeneration temperature was stabilized for 0.5 hours, 0.50 mL / min of 10% hydrogen peroxide solution was introduced for treatment for 10 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 110°C at a heating rate of 5°C / min. After the regeneration temperature was stabilized for 2 hours, 0.6 mL / min of 20% O3-N2 mixed gas was introduced for regeneration for 20 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 450°C at a heating rate of 5°C / min. The regeneration temperature was stabilized for 0.5 hours. h later, H2 with a volume flow rate of 0.4 mL / min was introduced for 10 h. The regeneration pressure was atmospheric pressure. After the catalyst was regenerated, methanol amination reaction was carried out. The molar ratio of the reaction raw materials was liquid ammonia: methanol = 2:1, the reaction pressure was 2 MPa, the vaporization temperature was 280 °C, the reaction temperature was 400 °C, and the liquid hourly volume space velocity was 1.3 h -1 After 2 h of reaction, samples were taken every 1 h for gas chromatography analysis. The average value of the analysis data of 6 parallel samples was taken. The results are shown in Table 1.

[0032] Example 5 The trimethylamine catalyst with reduced activity in Example 1 was immersed in a 2,2'-dithiodibenzoic acid solution at 80°C and pH=6. After soaking for 5 hours, the catalyst was filtered out and dried at 110°C for 10 hours. The acid-treated catalyst was then washed with ethanol, filtered and dried at 110°C for 4 hours. The dried and cooled catalyst was then loaded into a fixed bed reactor. The reactor temperature was raised to 90°C at a heating rate of 5°C / min under N2 atmosphere. After the regeneration temperature was stabilized for 0.5 hours, 0.50 mL / min of 10% hydrogen peroxide solution was introduced for treatment for 10 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 110°C at a heating rate of 5°C / min. After the regeneration temperature was stabilized for 2 hours, 0.6 mL / min of 20% O3-N2 mixed gas was introduced for regeneration for 20 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 450°C at a heating rate of 5°C / min. The regeneration temperature was stabilized for 0.5 hours. h later, H2 with a volume flow rate of 0.4 mL / min was introduced for 10 h. The regeneration pressure was atmospheric pressure. After the catalyst was regenerated, methanol amination reaction was carried out. The molar ratio of the reaction raw materials was liquid ammonia: methanol = 2:1, the reaction pressure was 2 MPa, the vaporization temperature was 280 °C, the reaction temperature was 400 °C, and the liquid hourly volume space velocity was 1.3 h -1 After 2 h of reaction, samples were taken every 1 h for gas chromatography analysis. The average value of the analysis data of 6 parallel samples was taken. The results are shown in Table 1.

[0033] Table 1. Effects of different organic acid solutions on the reaction performance of metal-modified mordenite catalyst after regeneration

[0034] Example 6 The trimethylamine catalyst with reduced activity in Example 1 was immersed in a 4-bromophthalic acid solution at 80°C and pH=5. After soaking for 5 hours, the catalyst was filtered out and dried at 110°C for 10 hours. The acid-treated catalyst was then washed with chloroform, filtered and dried at 110°C for 4 hours. The dried and cooled catalyst was then loaded into a fixed bed reactor. The reactor temperature was raised to 90°C at a heating rate of 5°C / min under a N2 atmosphere. After the regeneration temperature was stabilized for 0.5 hours, 0.50 mL / min of 10% hydrogen peroxide solution was introduced for treatment for 10 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 110°C at a heating rate of 5°C / min. After the regeneration temperature was stabilized for 2 hours, 0.6 mL / min of 20% O3-N2 mixed gas was introduced for regeneration for 20 hours; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 450°C at a heating rate of 5°C / min. The regeneration temperature was stabilized for 0.5 hours. h later, H2 with a volume flow rate of 0.4 mL / min was introduced for 10 h. The regeneration pressure was atmospheric pressure. After the catalyst was regenerated, methanol amination reaction was carried out. The molar ratio of the reaction raw materials was liquid ammonia: methanol = 2:1, the reaction pressure was 2 MPa, the vaporization temperature was 280 °C, the reaction temperature was 400 °C, and the liquid hourly volume space velocity was 1.3 h -1 After 2 h of reaction, samples were taken every 1 h for gas chromatography analysis. The stability test was performed for 300 h. The results were as follows: Figure 1 shown.

[0035] Comparative Example 1 The trimethylamine catalyst with reduced activity in Example 1 was loaded into a fixed bed reactor, and the reactor temperature was raised to 90°C at a heating rate of 5°C / min under N2 atmosphere. After the regeneration temperature was stable for 0.5 h, 0.50 mL / min of 10% hydrogen peroxide solution was introduced for 10 h; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 110°C at a heating rate of 5°C / min. After the regeneration temperature was stable for 2 h, 0.6 mL / min of 20% O3-N2 mixed gas was introduced for regeneration for 20 h; then N2 was introduced into the purge pipeline and the regeneration temperature was raised to 450°C at a heating rate of 5°C / min. After the regeneration temperature was stable for 0.5 h, H2 with a volume flow rate of 0.4 mL / min was introduced for 10 h. The regeneration pressure was normal pressure. After the catalyst regeneration was completed, methanol amination reaction was carried out. The molar ratio of the reaction materials is liquid ammonia: methanol = 2:1, the reaction pressure is 2 MPa, the vaporization temperature is 280°C, the reaction temperature is 400°C, and the liquid hourly volume space velocity is 1.3 h -1 After 2 h of reaction, samples were taken every 1 h for gas chromatography analysis. The average value of the analysis data of 6 parallel samples was taken. The results are shown in Table 2.

[0036] Comparative Example 2 The trimethylamine catalyst with reduced activity in Example 1 was soaked in a 2,2'-dithiodibenzoic acid solution at 80°C and pH=6. After soaking for 5 hours, the catalyst was filtered out and dried at 110°C for 10 hours. Then, the acid-treated catalyst was washed with ethanol, filtered and dried at 110°C for 4 hours. After that, the dried and cooled catalyst was loaded into a fixed bed reactor, and N2 was passed through the pipeline to raise the regeneration temperature to 110°C at a heating rate of 5°C / min. After the regeneration temperature was stable for 2 hours, 0.6mL / min of 20% O3-N2 mixed gas was passed through for regeneration for 20 hours; then N2 was passed through the pipeline to raise the regeneration temperature to 450°C at a heating rate of 5°C / min. After the regeneration temperature was stable for 0.5 hours, H2 with a volume flow rate of 0.4 mL / min was passed through for 10 hours. The regeneration pressure was normal pressure. After the catalyst was regenerated, methanol amination reaction was carried out. The molar ratio of the reaction materials is liquid ammonia: methanol = 2:1, the reaction pressure is 2 MPa, the vaporization temperature is 280°C, the reaction temperature is 400°C, and the liquid hourly volume space velocity is 1.3 h -1 After 2 h of reaction, samples were taken every 1 h for gas chromatography analysis. The average value of the analysis data of 6 parallel samples was taken. The results are shown in Table 2.

[0037] Table 2. Effects of different regeneration methods on the reaction performance of metal-modified mordenite catalyst after regeneration

[0038] In summary, the present invention first uses an organic acid to remove non-framework aluminum in the catalyst, then uses an organic solvent to wash and remove residual organic acid and part of carbon deposits, and finally uses a combination of low-temperature oxidation with an inert mixed gas containing hydrogen peroxide and ozone and hydrogen reduction to perform in-situ regeneration treatment on the metal-modified mordenite. The catalyst regeneration method is simple and efficient, and the regenerated catalyst still maintains good reaction performance in the methanol amination reaction.

[0039] It should be noted that all variations directly replaced or indirectly modified by those skilled in the art from the disclosure of the present invention should be considered to be within the protection scope of the present invention.

Claims

1. A method for regenerating a metal-modified mordenite catalyst used in a methanol amination reaction, characterized in that: The following steps are involved: 1) soaking the metal-modified mordenite catalyst with reduced activity in an organic acid solution in sequence, and then filtering and drying; 2) Wash the dried catalyst with an organic solvent, filter and dry it. 3) The dried and cooled catalyst is loaded into a fixed bed reactor, and the reactor temperature is first raised to 70-90°C under an inert atmosphere. When the temperature is stable, a hydrogen peroxide solution is introduced for treatment for 10-16 hours; 4) Introduce inert gas to purge the pipeline and raise the temperature of the reactor to 105-115°C. After the temperature stabilizes for 2 hours, continuously introduce an inert mixed gas containing ozone for 6-24 hours; 5) Introduce inert gas to purge the pipeline and raise the temperature of the reactor to 400-550°C. After the temperature is stable for 0.5-1h, continuously introduce hydrogen for 6-20h to obtain a regenerated catalyst.

2. The method for regenerating the metal-modified mordenite catalyst used in methanol amination reaction according to claim 1, characterized in that: The metal-modified mordenite catalyst is alkali metal and transition metal modified mordenite, wherein the mass of the alkaline earth metal element accounts for 20% to 60% of the mass of the mordenite; the mass of the transition metal element accounts for 1% to 5% of the mass of the mordenite; the silicon-aluminum ratio of the mordenite is 5 to 60; the alkaline earth metal element is selected from one or more of barium and calcium, and the transition metal element is selected from one or more of nickel, cobalt, copper and zinc.

3. The method for regenerating the metal-modified mordenite catalyst used in methanol amination reaction according to claim 1, characterized in that: The organic acid solution is selected from one or more of 4-chloro-3-nitrobenzoic acid, p-nitrotoluene sulfonic acid, 4-bromophthalic acid, and 2,2'-dithiodibenzoic acid, and the pH range of the organic acid solution is 4-6.

4. The method for regenerating the metal-modified mordenite catalyst used in methanol amination reaction according to claim 1, characterized in that: The organic solvent is selected from one or more of ethanol, ether and chloroform.

5. The method for regenerating the metal-modified mordenite catalyst used in methanol amination reaction according to claim 1, characterized in that: The heating rate is 1 to 40°C / min, preferably 5 to 8°C / min; the concentration of the hydrogen peroxide solution is 5% to 20%.

6. The method for regenerating the metal-modified mordenite catalyst used in methanol amination reaction according to claim 1, characterized in that: The ozone concentration in the inert atmosphere containing ozone is 3-50%; the inert atmosphere is one of argon, nitrogen, and helium, or a combination of two or more thereof.

7. A method for preparing methylamine by catalytic amination of methanol, characterized in that: The following steps are involved: The mixed liquid of methanol and liquid ammonia is passed into a preheater for vaporization, and then passed into a fixed bed reactor filled with a metal-modified mordenite catalyst obtained by the regeneration method according to any one of claims 1 to 6, to react and obtain a mixed product of different methylamines.

8. The method according to claim 7, characterized in that The vaporization temperature is 200-300℃.

9. The method according to claim 7, characterized in that: The reaction temperature is 350-450°C, and the reaction pressure is 1-3MPa.

10. The method according to claim 7, characterized in that The molar ratio of liquid ammonia to methanol is 1.2 to 2:1.

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