Rare earth element modified molecular sieve as well as preparation method and application thereof
By using rare earth element modified molecular sieve as catalysts, the problems of high catalyst cost and process pollution in the prior art are solved, and an efficient, low-cost and environmentally friendly process for isobutenamine preparation of tert-butylamine are realized.
Patent Information
- Application Number
- CN202510138968.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-08
- Publication Date
- 2025-05-13
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
In the existing methods for preparing tert-butylamine by isobutenamine, the catalyst cost is high, and the process has problems of pollution and equipment corrosion.
Rare earth element modified molecular sieve was used as a catalyst, and the H-type MCM-22 molecular sieve was mixed with aqueous solution of rare earth elements, adjusted the pH value, and impregnated, dried and calcined, and a rare earth element modified molecular sieve with high catalytic activity and low cost were prepared.
It achieves high conversion of isobutene and high selectivity of tert-butylamine, has a long service life and low cost, avoiding pollution and equipment corrosion problems.
Smart Images
Figure BDA0005264164210000081 
Figure HDA0005264164220000011 
Figure HDA0005264164220000012
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of preparing tert-butylamine by amination of isobutylene, and in particular to a rare earth element modified molecular sieve and a preparation method and application thereof. Background Art
[0002] Tert-butylamine is an important class of compounds used as intermediates in a variety of applications, including pharmaceuticals, agrochemicals, rubber chemicals and water treatment chemicals. In particular, it is highly valued by the industry as the main raw material for N-tert-butyl-2-benzothiazole sulfonamide (TBBS), a new global environmentally friendly leading rubber accelerator.
[0003] In the past few decades, people have developed various methods for synthesizing tert-butylamine, including hydrolysis of tert-butyl urea, hydrocyanic acid method, amination of halogenated hydrocarbons, etc. These methods mostly use strong acid / base, equipment is easily corroded, and pollution is serious. At present, the mainstream process in the market is produced by isobutylene and liquid ammonia synthesis. Compared with other methods, the direct amination of isobutylene has good reaction selectivity, high atomic utilization, green and clean process, and no three wastes are generated.
[0004] In the related art, solid-supported catalysts are used for the direct amination of isobutylene to produce tert-butylamine. Most of these catalysts use precious metals such as rhodium and ruthenium as active components. The yield and selectivity of tert-butylamine are high, but the cost of the catalyst is high and it is not suitable for large-scale industrial production. Summary of the invention
[0005] In view of this, the object of the present invention is to provide a rare earth element modified molecular sieve and a preparation method and application thereof. The rare earth element modified molecular sieve provided by the present invention is used as a catalyst for isobutylene amination to produce tert-butylamine, has high catalytic activity, high isobutylene conversion rate and tert-butylamine selectivity, long service life and low cost.
[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0007] The present invention provides a rare earth element modified molecular sieve, comprising an H-type MCM-22 molecular sieve and a rare earth element doped in the H-type MCM-22 molecular sieve; the rare earth element is one or more of Ce, La and Gd;
[0008] Calculated by mass percentage, the content of rare earth elements in the rare earth element modified molecular sieve is 2-10%.
[0009] The present invention provides a method for preparing the rare earth element modified molecular sieve described in the above scheme, comprising the following steps:
[0010] After mixing the H-type MCM-22 molecular sieve with the aqueous solution of the rare earth element, the pH value of the obtained mixed system is adjusted to 2-6 for impregnation, and the impregnated molecular sieve is dried and calcined in sequence to obtain the rare earth element modified molecular sieve.
[0011] Preferably, the calcination temperature is 500-600° C. and the calcination time is 3-6 hours.
[0012] Preferably, the aqueous solution of rare earth elements is obtained by dissolving nitrates of rare earth elements in water; the mass concentration of nitrates of rare earth elements in the aqueous solution of rare earth elements is 10-50%.
[0013] Preferably, the immersion temperature is 15 to 30° C. and the immersion time is 1 to 30 hours.
[0014] Preferably, the reagent used to adjust the pH value of the obtained mixed system to 2-6 includes dilute hydrochloric acid.
[0015] Preferably, the preparation of the H-type MCM-22 molecular sieve comprises: immersing the MCM-22 molecular sieve in an NH4NO3 solution for ion exchange to obtain the H-type MCM-22 molecular sieve.
[0016] Preferably, the concentration of the NH4NO3 solution is 0.5-0.7 mol / L; the mass ratio of the volume of the NH4NO3 solution to the MCM-22 molecular sieve is 5-10 mL: 1 g.
[0017] The present invention provides the use of the rare earth element modified molecular sieve described in the above scheme or the rare earth element modified molecular sieve prepared by the preparation method described in the above scheme as a catalyst in the preparation of tert-butylamine by amination of isobutylene.
[0018] Preferably, the reaction pressure for preparing tert-butylamine by amination of isobutylene is 8-30 MPa, the reaction temperature is 200-300°C, the amination reagent is liquid ammonia, the molar ratio of liquid ammonia to isobutylene is 2-6:1, and the isobutylene space velocity is 200-500 h -1 .
[0019] The invention provides a rare earth element modified molecular sieve, comprising an H-type MCM-22 molecular sieve and a rare earth element doped in the H-type MCM-22 molecular sieve; the rare earth element is one or more of Ce, La and Gd; and the content of the rare earth element in the rare earth element modified molecular sieve is 2-10% by mass percentage.
[0020] The MCM-22 molecular sieve has a pore structure of a ten-membered ring and a twelve-membered ring, and has excellent catalytic performance in the process of isobutylene amination reaction; the present invention uses an H-type MCM-22 molecular sieve as a carrier, and compared with the MCM-22 molecular sieve, the H-type MCM-22 molecular sieve is easier to combine with rare earth elements, thereby improving the stability of the catalyst; by doping with specific rare earth elements, the metal center with an empty orbital can provide an L acid site in the process of isobutylene catalytic amination, thereby improving the catalytic activity, so that the conversion rate of isobutylene and the selectivity of tert-butylamine are high. The present invention does not use precious metals, and the catalyst cost is low.
[0021] The results of the examples show that the rare earth element modified molecular sieve used as a catalyst for the amination of isobutylene to prepare tert-butylamine has a high catalytic activity, the single-pass conversion rate of isobutylene can reach more than 20%, and the selectivity of tert-butylamine can reach more than 99%.
[0022] The present invention provides a method for preparing the rare earth element modified molecular sieve described in the above scheme. The preparation method of the present invention is simple and can be easily realized in large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 is a chromatogram of the catalytic reaction product of Example 1;
[0024] Figure 2 1 is the XRD diagram of the MCM-22 molecular sieve, HMCM-22 molecular sieve and La-HMCM-22 molecular sieve in Example 1. DETAILED DESCRIPTION
[0025] The present invention provides a rare earth element modified molecular sieve, comprising an H-type MCM-22 molecular sieve and a rare earth element doped in the H-type MCM-22 molecular sieve; the rare earth element is one or more of Ce, La and Gd;
[0026] Calculated by mass percentage, the content of rare earth elements in the rare earth element modified molecular sieve is 2-10%.
[0027] In a specific embodiment, the content of rare earth elements in the rare earth element modified molecular sieve may be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.
[0028] The MCM-22 molecular sieve has a pore structure of a ten-membered ring and a twelve-membered ring, and has excellent catalytic performance in the process of isobutylene amination reaction; the present invention uses an H-type MCM-22 molecular sieve as a carrier, and compared with the MCM-22 molecular sieve, the H-type MCM-22 molecular sieve is easier to combine with rare earth elements, thereby improving the stability of the catalyst; by doping with specific rare earth elements, the metal center with an empty orbital can provide an L acid site in the process of isobutylene catalytic amination, thereby improving the catalytic activity, so that the conversion rate of isobutylene and the selectivity of tert-butylamine are high. The present invention does not use precious metals, and the catalyst cost is low.
[0029] The present invention provides a method for preparing the rare earth element modified molecular sieve described in the above scheme, comprising the following steps:
[0030] After mixing the H-type MCM-22 molecular sieve with the aqueous solution of the rare earth element, the pH value of the obtained mixed system is adjusted to 2-6 for impregnation, and the impregnated molecular sieve is dried and calcined in sequence to obtain the rare earth element modified molecular sieve.
[0031] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known in the art.
[0032] In the present invention, the preparation of the H-type MCM-22 molecular sieve preferably comprises: immersing the MCM-22 molecular sieve in an NH4NO3 solution for ion exchange to obtain the H-type MCM-22 molecular sieve.
[0033] In the present invention, the concentration of the NH4NO3 solution is preferably 0.5-0.7 mol / L, more preferably 0.6 mol / L; the mass ratio of the volume of the NH4NO3 solution to the MCM-22 molecular sieve is preferably 5-10 mL:1 g, and in specific embodiments it can be 5 mL:1 g, 7 mL:1 g, 8 mL:1 g or 10 mL:1 g.
[0034] In the present invention, the number of ion exchanges is preferably 3 times, and the time of each ion exchange is preferably 2 to 4 hours, more preferably 3 hours. After completing the ion exchange, the present invention preferably washes and dries the obtained molecular sieve to obtain an H-type MCM-22 molecular sieve. The present invention performs ion exchange on the MCM-22 molecular sieve, and the exchanged H-type MCM-22 molecular sieve can more stably bind rare earth ions, thereby increasing the service life of the catalyst.
[0035] After obtaining the H-type MCM-22 molecular sieve, the present invention mixes the H-type MCM-22 molecular sieve with an aqueous solution of a rare earth element, and adjusts the pH value of the obtained mixed system to 2-6 for impregnation.
[0036] In the present invention, the aqueous solution of rare earth elements is preferably obtained by dissolving nitrates of rare earth elements in water; the nitrates of rare earth elements preferably include one or more of cerium nitrate, lanthanum nitrate and gadolinium nitrate. In the present invention, the mass concentration of the nitrates of rare earth elements in the aqueous solution of rare earth elements is preferably 10-50%, and in specific embodiments can be 10%, 20%, 30%, 40% or 50%.
[0037] The present invention does not impose any particular limitation on the specific amount of the rare earth element aqueous solution, as long as the H-type MCM-22 molecular sieve can be completely immersed and the content of the rare earth element in the rare earth element aqueous solution is greater than the content of the rare earth element in the rare earth element modified molecular sieve.
[0038] The invention controls the content of rare earth elements in the rare earth element modified molecular sieve by adjusting the dosage of the rare earth element aqueous solution and the subsequent impregnation time.
[0039] In the present invention, the reagent used to adjust the pH value of the obtained mixed system to 2-6 preferably includes dilute hydrochloric acid; the present invention has no special requirements on the concentration of the dilute hydrochloric acid, and any concentration known in the art can be used. In the embodiment of the present invention, a 4 mol / L dilute hydrochloric acid solution is used.
[0040] In a specific embodiment, the pH value of the obtained mixed system can be adjusted to 2, 3, 4, 5 or 6.
[0041] The invention performs acidity adjustment to make the rare earth element modified molecular sieve acidic, thereby improving the catalytic effect of preparing tert-butylamine by amination of isobutylene.
[0042] In the present invention, the impregnation temperature is preferably 15-30°C, and in a specific embodiment, the impregnation temperature can be 15°C, 20°C, 25°C or 30°C; the impregnation time is preferably 1-30h, and in a specific embodiment, it can be 1h, 5h, 10h, 15h, 20h, 25h or 30h. In the impregnation process of the present invention, the rare earth elements are attached to the H-type MCM-22 molecular sieve.
[0043] After the impregnation is completed, the present invention separates the molecular sieve, and sequentially dries and calcines the impregnated molecular sieve to obtain the rare earth element modified molecular sieve.
[0044] In the present invention, the drying temperature is preferably 60-80°C, and the drying time is preferably 10-18h; in a specific embodiment, the drying temperature can be 60°C, 65°C, 70°C, 75°C or 80°C, and the drying time can be 10h, 12h, 14h, 16h or 18h.
[0045] In the present invention, the calcination temperature is preferably 500-600°C, and the time is preferably 3-6h; in a specific embodiment, the calcination temperature can be 500°C, 550°C or 600°C, and the calcination time can be 3h, 4h, 5h or 6h. In the present invention, the calcination is preferably carried out in an air atmosphere. The present invention removes impurities on the surface of the H-type MCM-22 molecular sieve by calcination, increases the specific surface area of the H-type MCM-22 molecular sieve, and realizes a firm combination of the H-type MCM-22 molecular sieve and the rare earth element.
[0046] The present invention provides the use of the rare earth element modified molecular sieve described in the above scheme or the rare earth element modified molecular sieve prepared by the preparation method described in the above scheme as a catalyst in the preparation of tert-butylamine by amination of isobutylene.
[0047] Before use, the present invention preferably activates the catalyst. The activation temperature is preferably 200-600°C; the activation time is preferably 2-4 hours; the activation is preferably performed under nitrogen protection. In a specific embodiment, the activation temperature can be 200°C, 300°C, 400°C, 500°C or 600°C, and the activation time can be 2 hours, 3 hours or 4 hours. The present invention removes moisture and other impurities adsorbed by the catalyst through activation.
[0048] In the present invention, the reaction pressure for preparing tert-butylamine by amination of isobutylene is preferably 8-30 MPa, the reaction temperature is preferably 200-300°C, the amination reagent is liquid ammonia, the molar ratio of liquid ammonia to isobutylene is preferably 2-6:1, and the isobutylene space velocity is preferably 200-500 h -1 In a specific embodiment, the reaction pressure for preparing tert-butylamine by amination of isobutylene may be 8MPa, 10MPa, 15MPa, 20MPa, 25MPa or 30MPa, the reaction temperature may be 200°C, 220°C, 240°C, 260°C, 280°C or 300°C, the molar ratio of liquid ammonia to isobutylene may be 2:1, 3:1, 4:1, 5:1 or 6:1, and the isobutylene space velocity may be 200h -1 、300h -1 , 400h -1 or 500h -1 .
[0049] In the present invention, the preparation of tert-butylamine by amination of isobutylene is preferably carried out in a shell-and-tube reactor; specifically, the catalyst is filled in a heat exchange tube, and the reaction medium in the heat exchange tube undergoes a chemical reaction and releases a large amount of heat under the combined action of the catalyst, temperature and pressure, and the shell side takes away the reaction heat.
[0050] The rare earth element modified molecular sieve and its preparation method and application provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0051] Example 1
[0052] (1) The MCM-22 molecular sieve was immersed in a 0.6 mol / L NH4NO3 solution for ion exchange, and the exchange was repeated 3 times, each time for 2 h. After washing and drying, the H-type MCM-22 molecular sieve was obtained, which was recorded as HMCM-22.
[0053] (2) The H-type MCM-22 molecular sieve is immersed in a 10% by mass lanthanum nitrate solution, and a 4 mol / L dilute hydrochloric acid solution is added dropwise to adjust the pH to 5, and the mixture is immersed for 24 hours.
[0054] (3) The impregnated molecular sieve was dried at 80° C. for 10 h, and then calcined at 500° C. for 4 h to obtain a modified molecular sieve, which was denoted as La-HMCM-22. The mass of the rare earth element accounted for 5% of the mass of the modified molecular sieve.
[0055] Tert-Butylamine Production:
[0056] (1) The modified molecular sieve of Example 1 was loaded into a tubular reactor as a catalyst, and atmospheric pressure nitrogen was introduced for purging. At the same time, the temperature was raised to 400° C. to activate the catalyst for 3 h.
[0057] (2) Liquid ammonia and isobutylene are preheated and mixed evenly in a molar ratio of 4:1 before entering the reactor. The reaction temperature is 260°C, the reaction pressure is 10 MPa, and the isobutylene space velocity is 200 h -1 .
[0058] Figure 1 is the chromatogram of the catalytic reaction product of Example 1, from Figure 1 It can be seen that the peak of isobutylene appears at 5.52 min and the peak of tert-butylamine appears at 6.19 min.
[0059] Figure 2 The XRD patterns of MCM-22 molecular sieve, HMCM-22 molecular sieve and La-HMCM-22 molecular sieve in Example 1 are shown in FIG. Figure 2 It can be seen that the spectra of HMCM-22 and La-HMCM-22 are basically consistent with the MCM-22 standard card, indicating that their crystal structures are not destroyed.
[0060] Example 2
[0061] (1) The MCM-22 molecular sieve was immersed in a 0.6 mol / L NH4NO3 solution for ion exchange, and the exchange was repeated 3 times, each time for 2 hours. After washing and drying, the H-type MCM-22 molecular sieve was obtained.
[0062] (2) The H-type MCM-22 molecular sieve is immersed in a lanthanum nitrate solution with a mass fraction of 30%, and a dilute hydrochloric acid solution with a concentration of 4 mol / L is added dropwise to adjust the pH to 5, and the mixture is immersed for 24 hours.
[0063] (3) The impregnated molecular sieve was dried at 80° C. for 10 h, and then calcined at 500° C. for 4 h to obtain a modified molecular sieve. The test showed that the mass of the rare earth element accounted for 10% of the mass of the modified molecular sieve.
[0064] Tert-Butylamine Production:
[0065] (1) The modified molecular sieve was loaded into a tubular reactor as a catalyst, and atmospheric pressure nitrogen was introduced for purging. At the same time, the temperature was raised to 400°C for catalyst activation for 3 hours.
[0066] (2) Liquid ammonia and isobutylene are preheated and mixed evenly in a molar ratio of 4:1 before entering the reactor. The reaction temperature is 260°C, the reaction pressure is 10 MPa, and the isobutylene space velocity is 200 h -1 .
[0067] Example 3
[0068] (1) The MCM-22 molecular sieve was immersed in a 0.6 mol / L NH4NO3 solution for ion exchange, and the exchange was repeated 3 times, each exchange for 2 h. After washing and drying, the H-type MCM-22 molecular sieve was obtained.
[0069] (2) The H-type MCM-22 molecular sieve is immersed in a 10% by mass lanthanum nitrate solution, and a 4 mol / L dilute hydrochloric acid solution is added dropwise to adjust the pH to 5, and the mixture is immersed for 24 hours.
[0070] (3) The impregnated molecular sieve catalyst is dried at 80° C. for 10 h, and then calcined at 500° C. for 4 h to obtain a modified molecular sieve, wherein the mass of the rare earth element accounts for 5% of the mass of the modified molecular sieve.
[0071] Tert-Butylamine Production:
[0072] (1) The modified molecular sieve was loaded into a tubular reactor as a catalyst, and atmospheric pressure nitrogen was introduced for purging. At the same time, the temperature was raised to 400° C. to activate the catalyst for 3 h.
[0073] (2) Liquid ammonia and isobutylene are preheated and mixed evenly in a molar ratio of 4:1 before entering the reactor. The reaction temperature is 240°C, the reaction pressure is 10 MPa, and the isobutylene space velocity is 200 h-1 .
[0074] Example 4
[0075] (1) The MCM-22 molecular sieve was immersed in a 0.6 mol / L NH4NO3 solution for ion exchange, and the exchange was repeated 3 times, each exchange for 2 h. After washing and drying, the H-type MCM-22 molecular sieve was obtained.
[0076] (2) The H-type MCM-22 molecular sieve is immersed in a 10% by mass lanthanum nitrate solution, and a 4 mol / L dilute hydrochloric acid solution is added dropwise to adjust the pH to 5, and the mixture is immersed for 24 hours.
[0077] (3) The impregnated molecular sieve catalyst was dried at 80° C. for 10 h, and then calcined at 500° C. for 4 h to obtain a modified molecular sieve. The test showed that the mass of the rare earth element accounted for 5% of the mass of the modified molecular sieve.
[0078] Tert-Butylamine Production:
[0079] (1) The modified molecular sieve was loaded into a tubular reactor as a catalyst, and atmospheric pressure nitrogen was introduced for purging. At the same time, the temperature was raised to 400° C. to activate the catalyst for 3 h.
[0080] (2) Liquid ammonia and isobutylene are preheated and mixed evenly in a molar ratio of 4:1 before entering the reactor. The reaction temperature is 220°C, the reaction pressure is 10 MPa, and the isobutylene space velocity is 300 h -1 .
[0081] Example 5
[0082] (1) The MCM-22 molecular sieve was immersed in a 0.6 mol / L NH4NO3 solution for ion exchange, and the exchange was repeated 3 times, each exchange for 2 h. After washing and drying, the H-type MCM-22 molecular sieve was obtained.
[0083] (2) The H-type MCM-22 molecular sieve is immersed in a cerium nitrate solution with a mass fraction of 10%, and a dilute hydrochloric acid solution with a concentration of 4 mol / L is dropped into it, the pH is adjusted to 5, and the mixture is immersed for 24 hours.
[0084] (3) The impregnated molecular sieve catalyst was dried at 80° C. for 10 h, and then calcined at 500° C. for 4 h to obtain a modified catalyst. The test showed that the mass of the rare earth element accounted for 10% of the mass of the modified molecular sieve.
[0085] Tert-Butylamine Production:
[0086] (1) The modified molecular sieve was loaded into a tubular reactor as a catalyst, and atmospheric pressure nitrogen was introduced for purging. At the same time, the temperature was raised to 400° C. to activate the catalyst for 3 h.
[0087] (2) Liquid ammonia and isobutylene are preheated and mixed evenly in a molar ratio of 4:1 before entering the reactor. The reaction temperature is 220°C, the reaction pressure is 10 MPa, and the isobutylene space velocity is 300 h -1 .
[0088] Example 6
[0089] (1) The MCM-22 molecular sieve was immersed in a 0.6 mol / L NH4NO3 solution for ion exchange, and the exchange was repeated 3 times, each time for 2 hours. After washing and drying, the H-type MCM-22 molecular sieve was obtained.
[0090] (2) The H-type MCM-22 molecular sieve is immersed in a 10% by mass gadolinium nitrate solution, and a 4 mol / L dilute hydrochloric acid solution is added dropwise to adjust the pH to 5, and the mixture is immersed for 24 hours.
[0091] (3) The impregnated molecular sieve catalyst was dried at 80° C. for 10 h, and then calcined at 500° C. for 4 h to obtain a modified molecular sieve. The test showed that the mass of the rare earth element accounted for 5% of the mass of the modified molecular sieve.
[0092] Tert-Butylamine Production:
[0093] (1) The modified molecular sieve was loaded into a tubular reactor as a catalyst, and atmospheric pressure nitrogen was introduced for purging. At the same time, the temperature was raised to 400°C for catalyst activation for 3 hours.
[0094] (2) Liquid ammonia and isobutylene are preheated and mixed evenly in a molar ratio of 4:1 before entering the reactor. The reaction temperature is 220°C, the reaction pressure is 10 MPa, and the isobutylene space velocity is 300 h -1 .
[0095] Comparative Example 1
[0096] (1) The MCM-22 molecular sieve was immersed in a 10% by mass lanthanum nitrate solution for ion exchange, and a 4 mol / L dilute hydrochloric acid solution was added dropwise to adjust the pH to 5, and the mixture was immersed for 24 hours.
[0097] (2) The impregnated molecular sieve catalyst is dried at 80° C. for 10 h, and then calcined at 500° C. for 4 h to obtain a modified molecular sieve, wherein the mass of the rare earth element accounts for 10% of the mass of the modified molecular sieve.
[0098] Tert-Butylamine Production:
[0099] (1) The modified molecular sieve was loaded into a tubular reactor as a catalyst, and atmospheric pressure nitrogen was introduced for purging. At the same time, the temperature was raised to 400°C for catalyst activation for 3 hours.
[0100] (2) Liquid ammonia and isobutylene are preheated and mixed evenly in a molar ratio of 4:1 before entering the reactor. The reaction temperature is 260°C, the reaction pressure is 10 MPa, and the isobutylene space velocity is 300 h -1 .
[0101] The types and contents of the modifying elements in each embodiment and comparative example, as well as the reaction temperature and reaction results (the reaction results after 6 hours of reaction) of preparing tert-butylamine by amination of isobutylene are shown in Table 1.
[0102] Table 1 Composition and catalytic conditions and results of modified molecular sieves of Examples and Comparative Examples
[0103]
[0104] From the results in Table 1, it can be seen that the rare earth element modified molecular sieve prepared by the present invention is used as a catalyst for preparing tert-butylamine by amination of isobutylene, and has a high catalytic activity, the single-pass conversion rate of isobutylene can reach more than 20%, and the selectivity of tert-butylamine can reach more than 99%. However, since the MCM-22 molecular sieve in Comparative Example 1 is not ion-exchanged, the catalytic performance of the modified molecular sieve obtained is lower than that of the embodiment, which is manifested in the reduction of isobutylene conversion rate and tert-butylamine selectivity.
[0105] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A rare earth element modified molecular sieve, characterized in that: It comprises an H-type MCM-22 molecular sieve and a rare earth element doped in the H-type MCM-22 molecular sieve; the rare earth element is one or more of Ce, La and Gd; Calculated by mass percentage, the content of rare earth elements in the rare earth element modified molecular sieve is 2-10%.
2. The method for preparing the rare earth element modified molecular sieve according to claim 1, characterized in that: The following steps are involved: After mixing the H-type MCM-22 molecular sieve with the aqueous solution of the rare earth element, the pH value of the obtained mixed system is adjusted to 2-6 for impregnation, and the impregnated molecular sieve is dried and calcined in sequence to obtain the rare earth element modified molecular sieve.
3. The preparation method according to claim 2, characterized in that: The calcination temperature is 500-600° C. and the calcination time is 3-6 hours.
4. The preparation method according to claim 2, characterized in that: The rare earth element aqueous solution is obtained by dissolving the nitrate of the rare earth element in water; the mass concentration of the nitrate of the rare earth element in the rare earth element aqueous solution is 10-50%.
5. The preparation method according to claim 2 or 4, characterized in that: The immersion temperature is 15-30° C. and the immersion time is 1-30 hours.
6. The preparation method according to claim 2, characterized in that: The reagent used to adjust the pH value of the obtained mixed system to 2-6 includes dilute hydrochloric acid.
7. The preparation method according to claim 2, characterized in that: The preparation of the H-type MCM-22 molecular sieve comprises: immersing the MCM-22 molecular sieve in an NH4NO3 solution for ion exchange to obtain the H-type MCM-22 molecular sieve.
8. The preparation method according to claim 7, characterized in that: The concentration of the NH4NO3 solution is 0.5-0.7 mol / L; the mass ratio of the volume of the NH4NO3 solution to the MCM-22 molecular sieve is 5-10 mL: 1 g.
9. Use of the rare earth element modified molecular sieve according to claim 1 or the rare earth element modified molecular sieve prepared by the preparation method according to any one of claims 2 to 8 as a catalyst in the preparation of tert-butylamine by amination of isobutylene.
10. The use according to claim 9, characterized in that: The reaction pressure for preparing tert-butylamine by isobutylene amination is 8-30 MPa, the reaction temperature is 200-300° C., the amination reagent is liquid ammonia, the molar ratio of liquid ammonia to isobutylene is 2-6:1, and the isobutylene space velocity is 200-500 h -1 .