LONG-LIFETIME SAPO-34 CATALYST PREPARED FROM MTO WASTE CATALYST AS RAW MATERIAL AND METHOD FOR PREPARATION THEREOF

Abstract

The present invention provides a long-lifetime SAPO-34 catalyst prepared from waste MTO catalyst as a raw material and a preparation method thereof. The method comprises the following steps: mixing the waste MTO catalyst fine powder with water; adding a phosphoric acid and an organic amine and stirring to obtain an initial gel mixture for SAPO-34 molecular sieve; crystallizing the initial gel mixture and then at least drying it to obtain a raw SAPO-34 molecular sieve powder; calcining the raw molecular sieve powder to obtain a SAPO-34 molecular sieve powder; then mixing it with a binder and a matrix carrier in water with stirring, and then aging it; and molding and then calcining it to obtain the long-lifetime SAPO-34 catalyst. The preparation method of the present invention uses MTO waste catalyst as a raw material to synthesize SAPO-34 molecular sieve in situ within a short time, and to prepare MTO catalysts having a long life and high selectivity for light olefins.

Claims

1. A method for preparing a long-lifetime SAPO-34 catalyst from waste MTO catalyst as a raw material, comprising the steps of: (1) mixing the waste MTO catalyst fine powder with water and stirring them for a period of time to obtain a first mixture; (2) adding phosphoric acid and an organic amine to the first mixture obtained in step (1) and stirring them for a period of time to obtain an initial gel mixture for SAPO-34 molecular sieve; (3) crystallizing the initial gel mixture for SAPO-34 molecular sieve obtained in step (2) and then at least drying it to obtain rawSAPO-34 molecular sieve powder; (4) calcining the raw SAPO-34 molecular sieve powder obtained in step (3) to obtain SAPO-34 molecular sieve powder; (5) mixing the SAPO-34 molecular sieve powder obtained in step (4) with a binder and a matrix carrier in water with stirring, and then aging the resultant by standing it for a period of time to obtain a second mixture; and (6) molding the second mixture obtained in step (5) and then calcining the resultant to obtain the long-lifetime SAPO-34 catalyst.

2. The method according to claim 1, wherein the fresh catalyst corresponding to the waste MTO catalyst fine powder used in step (1) is a SAPO-34 molecular sieve; and the waste MTO catalyst fine powder used in step (1) is a permanently deactivated waste MTO catalyst, having no characteristic diffraction peaks of SAPO-34 molecular sieve in its X-ray diffraction spectrum.

3. The method according to claim 1, wherein in step (1), the first mixture is obtained by mixing the waste MTO catalyst fine powder with a certain amount of water and stirring them for 2 to 6 hours.

4. The method according to claim 1, wherein in step (1) the waste MTO catalyst fine powder is mixed with water in a mass ratio of 1:(5-50).

5. The method according to claim 1, wherein in step (2), the initial gel mixture for SAPO-34 molecular sieve is obtained by adding phosphoric acid and an organic amine to the first mixture obtained in step (1) and stirring them for 2 to 4 hours.

6. The method according to claim 1, wherein in step (2), the organic amine comprises one or more of diethylamine, triethylamine, tetraethylammonium hydroxide, and morpholine.

7. The method according to claim 1, wherein in step (2), the phosphoric acid is in a form of an aqueous phosphoric acid solution; preferably, in step (2), the phosphoric acid is in a form of a 85% (w/w) aqueous phosphoric acid solution.

8. The method according to claim 1, wherein the mass ratio of the waste MTO catalyst fine powder in step (1), the phosphoric acid and the organic amine in step (2) is 1:(0.2-1.5):(0.3-2.2).

9. The method according to claim 1, wherein the initial gel mixture for SAPO-34 molecular sieve obtained in step (2) has a pH of 5 to 10.

10. The method according to claim 1, wherein in step (3), the crystallization is carried out at a temperature of 160 to 220 C. for a time period of 5 to 48 hours.

11. The method according to claim 1, wherein in step (3), the drying is carried out at a temperature of 100 to 120 C. for a time period of 4 to 12 hours.

12. The method according to claim 1, wherein in step (4), the calcining is carried out at a temperature of 500 to 600 C. for a time period of 4 to 10 hours.

13. The method according to claim 1, wherein in step (5), the aging by standing is carried out for a time period of 4 to 12 hours.

14. The method according to claim 1, wherein in step (5), the binder comprises one or more of pseudo-boehmite, alumina sol, and silica sol.

15. The method according to claim 1, wherein in step (5), the matrix carrier comprises one or more of diatomaceous earth, kaolin, and montmorillonite.

16. The method according to claim 1, wherein in step (5), the SAPO-34 molecular sieve powder, the binder, and the matrix carrier are mixed in a mass ratio of 1:(0.1-1.25):(0.2-10).

17. The method according to claim 1, wherein in step (5), the SAPO-34 molecular sieve powder is mixed with water in a mass ratio of 1:(1-10).

18. The method according to claim 1, wherein in step (6), the molding is carried out in a spray dryer with an inlet temperature of 250 to 350 C. and an outlet temperature of 80 to 200 C.

19. The method according to claim 1, wherein in step (6), the calcining is carried out at a temperature of 500 to 700 C. for a time period of 4 to 8 hours.

20. A long-lifetime SAPO-34 catalyst prepared from waste MTO catalyst as a raw material by the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG. 1 shows a process flow diagram for preparing the long-lifetime SAPO-34 catalyst from a waste MTO catalyst as a raw material of Examples 1-5.

[0045] FIG. 2 shows X-ray diffraction spectra of the waste MTO catalyst, a fresh catalyst and catalyst samples of Examples 1-5.

[0046] FIG. 3a shows a transmission electron microscopy image of the long-lifetime SAPO-34 catalyst (S1) provided in Example 1.

[0047] FIG. 3b shows a transmission electron microscopy image of the long-lifetime SAPO-34 catalyst (S2) provided in Example 2.

[0048] FIG. 3c shows a transmission electron microscopy image of the long-lifetime SAPO-34 catalyst (S3) provided in Example 3.

[0049] FIG. 3d shows a transmission electron microscopy image of the long-lifetime SAPO-34 catalyst (S4) provided in Example 4.

DETAILED DESCRIPTION OF THE INVENTION

[0050] The following detailed description of the technical solutions of the present invention is provided to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, but it is not to be understood as limiting the scope of the practicable scope of the present invention.

Example 1

[0051] The example provides a long-lifetime SAPO-34 catalyst prepared from a waste MTO catalyst as a raw material, as in the process shown in FIG. 1, which is prepared by a method comprising the following steps:

[0052] 8 g of waste MTO catalyst fine powders were mixed with 80 g of deionized water and stirred for 4 hours at room temperature for aging at a stirring speed of 400 to 700 r/min. Then 2.8 g of a 85% (w/w) aqueous phosphoric acid solution and 5.37 g of tetraethylammonium hydroxide were added sequentially and stirred for aging at room temperature for 2 hours at a stirring speed of 400 to 700 r/min to obtain an initial gel mixture. The initial gel mixture was loaded into an autoclave with a PTFE liner, and then the autoclave was placed in an oven at 160 C. for crystallization at a constant temperature for 8 hours. After crystallization, the autoclave was naturally cooled to room temperature, and then separated, washed, dried and calcined to obtain SAPO-34 molecular sieve powder. The separation was done by centrifugation to separate out the solid product; and the washing was done with deionized water to wash the separated solid product until the pH of the washed liquid was below 8. The drying was carried out at a temperature of 100 C. for a time period of 12 hours. The calcining was carried out at a temperature of 500 C. for a time period of 10 hours.

[0053] Then 10.5 g of the SAPO-34 molecular sieve powder were mixed with 6.5 g of alumina sol, 4.5 g of diatomaceous earth and 40 g of deionized water, stirred for 4 hours at room temperature at a stirring speed of 400 to 700 r/min to be well mixed, and then left standing to age for 4 hours to obtain a mixture. The mixture was then molded by spraying with a spray dryer with an inlet temperature of 350 C. and an outlet temperature of 180 C. The obtained product was calcined in a muffle furnace at 550 C. for 6 hours to obtain a long-lifetime SAPO-34 catalyst (Si).

[0054] The XRD spectrum of the long-lifetime SAPO-34 catalyst (Si) is shown in FIG. 2. For comparison, the XRD spectra of the used waste MTO catalyst fine powders, an industrial fresh catalyst (which was the fresh one corresponding to the waste MTO catalyst fine powders used in this example) are also shown in FIG. 2. It can be demonstrated that the obtained samples are SAPO-34 molecular sieves with CHA topology, exhibiting strong characteristic diffraction peaks affiliated to the SAPO-34 framework at 9.6, 12.8, 16.2, 21.5 and 30.9. And its corresponding diffraction peak intensity was significantly higher than that of the industrial fresh catalyst, which can be used as a catalyst for the reaction of methanol to olefin.

[0055] Among them, the waste MTO catalyst fine powder was permanently deactivated waste MTO catalysts. As shown in FIG. 2, the characteristic diffraction peaks of SAPO-34 molecular sieve were not present in their X-ray diffraction spectra. Namely, the characteristic diffraction peaks of the SAPO-34 framework were not present at 9.6, 12.8, 16.2, 21.5 and 30.9. The permanent deactivation of the waste MTO catalyst fine powder in this example was achieved by exposing an incompletely deactivated waste MTO catalyst fine powder in air at room temperature for a long time period (3 months). This incompletely deactivated waste MTO catalyst fine powder was an industrially discarded waste MTO catalyst of SAPO-34 molecular sieve. The Si/Al/P molar ratio of the waste MTO catalyst fine powder used in this example was 1:(3.5-4.5):(1-2.5).

[0056] The transmission electron microscopy (TEM) image of the long-lifetime SAPO-34 catalyst (S1) is shown in FIG. 3a. The molecular sieve is cubic in shape with an average crystal size of 200 to 500 nm, and having a mesoporous and macropore structure with a mesopore size of 20 to 50 nm and a macropore size of 80 to 100 nm.

Example 2

[0057] The example provides a long-lifetime SAPO-34 catalyst prepared from a waste MTO catalyst as a raw material, as in the process shown in FIG. 1, which is prepared by a method comprising the following steps:

[0058] g of waste MTO catalyst fine powders (the same as Example 1, which was a permanently deactivated waste MTO catalyst fine powder) were mixed with 120 g of deionized water and stirred for 2 hours at room temperature for aging at a stirring speed of 400 to 700 r/min. Then 6.5 g of a 85% (w/w) aqueous phosphoric acid solution and 13.65 g of diethylamine were added sequentially and stirred for aging at room temperature for 4 hours at a stirring speed of 400 to 700 r/min to obtain an initial gel mixture. The initial gel mixture was loaded into an autoclave with a PTFE liner, and then the autoclave was placed in an oven at 180 C. for crystallization at a constant temperature for 5 hours. After crystallization, the autoclave was naturally cooled to room temperature, and then separated, washed, dried and calcined to obtain SAPO-34 molecular sieve powder. The separation was done by centrifugation to separate out the solid product; and the washing was done with deionized water to wash the separated solid product until the pH of the washed liquid was below 8. The drying was carried out at a temperature of 110 C. for a time period of 6 hours. The calcining was carried out at a temperature of 550 C. for a time period of 5 hours.

[0059] Then 25 g of the SAPO-34 molecular sieve powder were mixed with 8.7 g of pseudo-boehmite, 6.3 g of kaolin and 40 g of deionized water, stirred for 2 hours at room temperature at a stirring speed of 400 to 700 r/min to be well mixed, and then left standing to age for 8 hours to obtain a mixture. The mixture was then molded by spraying with a spray dryer with an inlet temperature of 300 C. and an outlet temperature of 150 C. The obtained product was calcined in a muffle furnace at 550 C. for 8 hours to obtain a long-lifetime SAPO-34 catalyst (S2).

[0060] The XRD spectrum of the long-lifetime SAPO-34 catalyst (S2) is shown in FIG. 2. It can be demonstrated that the obtained samples are SAPO-34 molecular sieves with CHA topology, exhibiting strong characteristic diffraction peaks affiliated to the SAPO-34 framework at 9.6, 12.8, 16.2, 21.5 and 30.9. And its corresponding diffraction peak intensity was significantly higher than that of the industrial fresh catalyst, which can be used as a catalyst for the reaction of methanol to olefins.

[0061] The transmission electron microscopy (TEM) image of the long-lifetime SAPO-34 catalyst (S2) is shown in FIG. 3b. The molecular sieve is cubic in shape with an average crystal size of 200 to 500 nm, and having a mesoporous and macropore structure with a mesopore size of 10 to 30 nm and a macropore size of 50 to 70 nm.

Example 3

[0062] The example provides a long-lifetime SAPO-34 catalyst prepared from a waste MTO catalyst as a raw material, as in the process shown in FIG. 1, which is prepared by a method comprising the following steps:

[0063] g of waste MTO catalyst fine powders (the same as Example 1, which was a permanently deactivated waste MTO catalyst fine powder) were mixed with 100 g of deionized water and stirred for 6 hours at room temperature for aging at a stirring speed of 400 to 700 r/min. Then 8 g of a 85% (w/w) aqueous phosphoric acid solution and 6.92 g of triethylamine were added sequentially and stirred for aging at room temperature for 3 hours at a stirring speed of 400 to 700 r/min to obtain an initial gel mixture. The initial gel mixture was loaded into an autoclave with a PTFE liner, and then the autoclave was placed in an oven at 220 C. for crystallization at a constant temperature for 12 hours. After crystallization, the autoclave was naturally cooled to room temperature, and then separated, washed, dried and calcined to obtain SAPO-34 molecular sieve powder. The separation was done by centrifugation to separate out the solid product; and the washing was done with deionized water to wash the separated solid product until the pH of the washed liquid was below 8. The drying was carried out at a temperature of 110 C. for a time period of 12 hours. The calcining was carried out at a temperature of 600 C. for a time period of 4 hours.

[0064] Then 19.5 g of the SAPO-34 molecular sieve powder were mixed with 8.7 g of pseudo-boehmite, 6.3 g of montmorillonite and 30 g of deionized water, stirred for 3 hours at room temperature at a stirring speed of 400 to 700 r/min to be well mixed, and then left standing to age for 6 hours to obtain a mixture. The mixture was then molded by spraying with a spray dryer with an inlet temperature of 300 C. and an outlet temperature of 150 C. The obtained product was calcined in a muffle furnace at 600 C. for 4 hours to obtain a long-lifetime SAPO-34 catalyst (S3).

[0065] The XRD spectrum of the long-lifetime SAPO-34 catalyst (S3) is shown in FIG. 2. It can be demonstrated that the obtained samples are SAPO-34 molecular sieves with CHA topology, exhibiting strong characteristic diffraction peaks affiliated to the SAPO-34 framework at 9.6, 12.8, 16.2, 21.5 and 30.9. And its corresponding diffraction peak intensity was significantly higher than that of the industrial fresh catalyst, which can be used as a catalyst for the reaction of methanol to olefin.

[0066] The transmission electron microscopy (TEM) image of the long-lifetime SAPO-34 catalyst (S3) is shown in FIG. 3c. The molecular sieve is cubic in shape with an average crystal size of 200 to 500 nm, and having a mesoporous and macropore structure with a mesopore size of 20 to 40 nm and a macropore size of 60 to 100 nm.

Example 4

[0067] The example provides a long-lifetime SAPO-34 catalyst prepared from a waste MTO catalyst as a raw material, as in the process shown in FIG. 1, which is prepared by a method comprising the following steps:

[0068] The waste MTO catalyst fine powders (the same as Example 1, which was a permanently deactivated waste MTO catalyst fine powder) were calcined at a temperature of 600 C. for 8 hours. 5 g of calcined waste MTO catalyst fine powders were mixed with 60 g of deionized water and stirred for 6 hours at room temperature for aging at a stirring speed of 400 to 700 r/min. Then 2.4 g of a 85% (w/w) aqueous phosphoric acid solution and 7.2 g of morpholine were added sequentially and stirred for aging at room temperature for 3 hours at a stirring speed of 400 to 700 r/min to obtain an initial gel mixture. The initial gel mixture was loaded into an autoclave with a PTFE liner, and then the autoclave was placed in an oven at 175 C. for crystallization at a constant temperature for 24 hours. After crystallization, the autoclave was naturally cooled to room temperature, and then separated, washed, dried and calcined to obtain SAPO-34 molecular sieve powder. The separation was done by centrifugation to separate out the solid product; and the washing was done with deionized water to wash the separated solid product until the pH of the washed liquid was below 8. The drying was carried out at a temperature of 110 C. for a time period of 12 hours. The calcining was carried out at a temperature of 550 C. for a time period of 5 hours.

[0069] Then 9.5 g of the SAPO-34 molecular sieve powder were mixed with 5.1 g of silica sol, 2.8 g of kaolin and 20 g of deionized water, stirred for 4 hours at room temperature at a stirring speed of 400 to 700 r/min to be well mixed, and then left standing to age for 4 hours to obtain a mixture. The mixture was then spray formed with a spray dryer with an inlet temperature of 280 C. and an outlet temperature of 130 C. The obtained product was calcined in a muffle furnace at 500 C. for 8 hours to obtain a long-lifetime SAPO-34 catalyst (S4).

[0070] The XRD spectrum of the long-lifetime SAPO-34 catalyst (S4) is shown in FIG. 2. It can be demonstrated that the obtained samples are SAPO-34 molecular sieves with CHA topology, exhibiting strong characteristic diffraction peaks affiliated to the SAPO-34 framework at 9.6, 12.8, 16.2, 21.5 and 30.9. And its corresponding diffraction peak intensity was significantly higher than that of the industrial fresh catalyst, which can be used as a catalyst for the reaction of methanol to olefin.

[0071] The transmission electron microscopy (TEM) image of the long-lifetime SAPO-34 catalyst (S4) is shown in FIG. 3d. The molecular sieve is cubic in shape with an average crystal size of 200 to 400 nm, and having a mesoporous and macropore structure with a mesopore size of 10 to 40 nm and a macropore size of 60 to 80 nm.

Example 5

[0072] The example provides a long-lifetime SAPO-34 catalyst prepared from a waste MTO catalyst as a raw material, as in the process shown in FIG. 1, which is prepared by a method comprising the following steps:

[0073] 12 g of waste MTO catalyst fine powders (the same as Example 1, which was a permanently deactivated waste MTO catalyst fine powder) were mixed with 100 g of deionized water and stirred for 2 hours at room temperature for aging at a stirring speed of 400 to 700 r/min. Then 5.4 g of a 85% (w/w) aqueous phosphoric acid solution and 7.5 g of tetraethylammonium hydroxide were added sequentially and stirred for aging at room temperature for 3 hours at a stirring speed of 400 to 700 r/min to obtain an initial gel mixture. The initial gel mixture was loaded into an autoclave with a PTFE liner, and then the autoclave was placed in an oven at 200 C. for crystallization at a constant temperature for 48 hours. After crystallization, the autoclave was naturally cooled to room temperature, and then separated, washed, dried and calcined to obtain SAPO-34 molecular sieve powder. The separation was done by centrifugation to separate out the solid product; and the washing was done with deionized water to wash the separated solid product until the pH of the washed liquid was below 8. The drying was carried out at a temperature of 100 C. for a time period of 10 hours. The calcining was carried out at a temperature of 500 C. for a time period of 6 hours.

[0074] Then 16.5 g of the SAPO-34 molecular sieve powder were mixed with 3 g of pseudo-boehmite, 6.5 g of montmorillonite and 20 g of deionized water, stirred for 4 hours at room temperature at a stirring speed of 400 to 700 r/min to be well mixed, and then left standing to age for 6 hours to obtain a mixture. The mixture was then molded by spraying with a spray dryer with an inlet temperature of 350 C. and an outlet temperature of 180 C. The obtained product was calcined in a muffle furnace at 550 C. for 8 hours to obtain a long-lifetime SAPO-34 catalyst (S5).

[0075] The XRD spectrum of this long-lifetime SAPO-34 catalyst (S5) is shown in FIG. 2. It can be demonstrated that the obtained samples are SAPO-34 molecular sieves with CHA topology, exhibiting strong characteristic diffraction peaks affiliated to the SAPO-34 framework at 9.6, 12.8, 16.2, 21.5 and 30.9. And its corresponding diffraction peak intensity was significantly higher than that of the industrial fresh catalyst, which can be used as a catalyst for the reaction of methanol to olefins.

[0076] The evaluation on the performance of the molecular sieve catalyst Five samples of the long-lifetime SAPO-34 catalyst from Examples 1-5 were evaluated for MTO performance using a fixed-bed catalytic reaction device for evaluation. First, the above five catalyst samples and 1.0 g of industrial fresh catalyst (which was the fresh catalyst corresponding to the waste MTO catalyst fine powder used in Examples 1-5) were weighed and placed into the reactor and activated by nitrogen gas at 550 C. for 2 hours, and then cooled down to 470 C. The feed methanol was carried by nitrogen at an air speed of 1.5 h.sup.1 and the reaction products were analyzed online using gas chromatography Agilent 6820 and Agilent 7820 at 15 min intervals. The reaction was terminated when the methanol conversion rate was below 100%, i.e., when methanol and dimethyl ether components appeared in the GC Agilent 6820 spectrum. After the reaction, the liquid products were collected in an ice and water bath and the gaseous products were discharged through the tail gas duct. The evaluation results are shown in Table 1.

TABLE-US-00001 TABLE 1 Life Selectivity (wt %) Samples (min) CH.sub.4 C.sub.2H.sub.6 C.sub.2H.sub.4 C.sub.3H.sub.8 C.sub.3H.sub.6 C.sub.4 C.sub.5.sup.+ C.sub.2 + C.sub.3 C.sub.2 + C.sub.3 + C.sub.4 Fresh 50 5.0 51.7 0.5 32.9 0.4 8.7 0.8 84.6 93.3 catalyst S1 510 4.8 57.2 0.6 29.9 0.5 6.8 0.2 87.1 93.1 S2 485 3.5 57.5 0.6 30.4 1.2 5.9 0.9 87.9 93.7 S3 425 4.3 59.1 0.7 28.8 1 5.2 0.9 87.9 93 S4 440 4.6 58.2 0.6 29.5 0.5 6.2 0.4 87.7 93.8 S5 470 4.6 59.1 0.5 29.4 0.5 5.4 0.5 88.5 93.9

[0077] As can be seen from Table 1, all five catalyst samples of the inventive examples had a long catalytic lifetime (higher than 425 min), which was more than 8 times that of the industrial fresh catalyst. Meanwhile the total yield of ethylene and propylene could exceed 87%.