A method for secondary utilization of MTO spent catalyst

Abstract

The present invention discloses a method for extracting an Al-P composite from an MTO spent catalyst. The method includes: first pre-treating the MTO spent catalyst after service, then performing a heat and pressure treatment, centrifuging to obtain a supernatant, adjusting the pH of the solution to 6-8 to obtain a precipitate, washing, drying, and calcining to obtain the Al-P composite; wherein, the purity of the obtained Al-P composite is 95-98%. The present invention also provides a method for extracting alumina from an MTO spent catalyst, including: first pre-treating the MTO spent catalyst after service, then performing a heat and pressure treatment, centrifuging to obtain a supernatant, adding a calcium-containing compound, filtering to obtain a solution, adjusting the pH of the solution to 6-8 for precipitation, washing, drying, and calcining to obtain alumina; wherein, the purity of the obtained alumina is 94-97%. This method not only realizes the green treatment of industrial waste catalysts, but also can obtain the Al-P composite and alumina, reducing production costs and achieving green preparation.

Description

Technical Field

[0001] The invention relates to a method for secondary utilization of MTO waste catalyst. Background Art

[0002] SAPO-34 molecular sieve exhibits very good catalytic performance in the methanol to olefins (MTO) reaction: the methanol conversion rate reaches 100%; the selectivity of ethylene and propylene can exceed 70%; 5 + The content of the components is relatively small and almost no aromatics are produced.

[0003] MTO industrial plants generate a large amount of waste catalysts every year. As waste residues, the transportation, discharge and treatment costs are high. Therefore, the environmental protection treatment of waste catalysts has always been a problem that troubles enterprises. The development of waste catalyst regeneration and reuse technology will bring great economic and environmental benefits.

[0004] Landfilling of waste catalysts is a way to treat waste catalysts, but the one-time investment is high and requires a qualified deep burial site. Road transportation will also cause secondary pollution. The content of heavy metals in MTO waste catalysts is relatively low, so the cost of extracting heavy metals from MTO waste catalysts is high. Therefore, an environmentally friendly and reasonable treatment method is urgently needed for MTO waste catalysts.

[0005] The treatment of FCC waste catalysts is currently the focus of much research. Some researchers have used inorganic and organic coupling methods to revive FCC waste catalysts (CN101219396A). However, this chemical method will cause loss of active components on the catalyst while removing contaminated metals. Moreover, the stability of the revived catalyst is insufficient. There is also a method for synthesizing NaY type molecular sieves using FCC waste catalysts (CN101891221A): first, the FCC waste catalysts are activated by alkali melting, and then the Y type molecular sieves are hydrothermally synthesized using a structure directing agent under the condition of adding a silicon source. This method introduces Na + ions, and the waste catalyst needs to be activated by high-temperature alkali melting, which is relatively complicated. There is also a method of "in-situ crystallization" to reuse the waste catalyst (CN102247880B): first pickling, then high-temperature alkali roasting, and then making microspheres and crystallization.

[0006] Compared with the FCC catalyst after service, the MTO catalyst after service is easier to recycle, but there are few reports on the reuse of the MTO catalyst after service. For example, Mou Baoji et al. calcined the spent methanol to olefins catalyst for a second time, and used the aluminum ammonium sulfate decomposition method and acid hydrolysis aging to obtain alumina and silicon phosphorus nitrogen mixed fertilizer (CN201811433062.6). This method requires high-temperature calcination and high equipment requirements. For the methanol to olefins catalyst after service, a simpler method is needed to recycle its components. SUMMARY OF THE INVENTION

[0007] The problem to be solved by the present invention is the secondary utilization of the MTO catalyst after service. The present invention provides a method for the secondary utilization of MTO waste catalyst, which not only realizes the green treatment of industrial waste catalyst, but also can obtain Al-P composite and alumina. Moreover, the obtained Al-P composite can be applied to the synthesis of SAPO molecular sieve, reducing the production cost of SAPO molecular sieve and realizing green preparation.

[0008] In the first aspect of the present invention, a method for extracting Al-P composite from MTO waste catalyst is provided, including: pre-treating the MTO waste catalyst after service, then performing heat and pressure treatment, centrifuging to obtain the supernatant, adjusting the pH of the solution to 6-8 to obtain a precipitate, washing, drying and calcining to obtain the Al-P composite;

[0009] wherein, the purity of the obtained Al-P composite is 95-98%; the extraction rate of extracting Al-P composite from MTO waste catalyst (m(Al-P composite): m(waste catalyst)) is 70-79%.

[0010] Further, in the Al-P composite, the weight ratio of Al is 70-80%; the weight ratio of P element is 18-25%; the weight ratio of Si is 0.5-3%.

[0011] Further, the MTO waste catalyst comes from the catalyst after service in the industrial methanol-to-olefins unit, and this catalyst contains SAPO-34 molecular sieve.

[0012] Further, the MTO waste catalyst contains Si, Al and P elements; the mass percentage of Al and P in the MTO waste catalyst is 70-80%.

[0013] Further, the pre-treatment is to add the MTO waste catalyst after service into an acid solution, and the acid solution is selected from at least one of strong acid solutions, preferably at least one of hydrochloric acid, phosphoric acid and sulfuric acid; the concentration of H + in the acid solution is 5-12 mol / L.

[0014] Further, the molar amount of the acid, calculated by H + , and the total molar amount of Al and P in the MTO waste catalyst, calculated by the sum of Al and P elements, n(H + ): n(Al+P) ranges from 2 to 10, preferably from 3 to 7.

[0015] Further, the mass ratio of the MTO waste catalyst to the acid solution ranges from 0.05 to 0.3, preferably from 0.1 to 0.2.

[0016] Further, in the heat and pressure treatment, the treatment temperature is 100 - 200 °C, the treatment time is 2 - 40 hours, and the pressure is the pressure generated by the autoclave itself.

[0017] Further, the pH is adjusted to 6 - 8, which can be achieved by adding acid or base.

[0018] Further, the drying conditions are 70 - 120 °C for 6 - 24 hours; the calcination conditions are 500 - 650 °C for 6 - 12 hours.

[0019] The second aspect of the present invention provides a method for extracting alumina from MTO waste catalyst, including:

[0020] including: first pre - treating the used MTO waste catalyst, then performing heat and pressure treatment, centrifuging to obtain the supernatant, adding a calcium - containing compound, filtering to obtain a solution, adjusting the pH of the solution to 6 - 8 for precipitation, washing, drying, and calcining to obtain alumina;

[0021] Among them, the purity of the obtained alumina is 94 - 97%.

[0022] Further, the pre - treatment is adding the used MTO waste catalyst into an alkali solution, and the alkali solution is selected from at least one of strong alkali solutions, preferably at least one of sodium hydroxide and potassium hydroxide solutions; the concentration of OH - in the alkali solution is 5 - 12 mol / L.

[0023] Further, the molar amount of the alkali, calculated by OH - , and the total molar amount of Al and P in the MTO waste catalyst, calculated by the sum of Al and P elements, the range of n(OH - ) : n(Al + P) is 4 - 10, preferably 5 - 9.

[0024] Further, the mass ratio of the MTO waste catalyst to the alkali solution ranges from 0.05 to 0.8, preferably from 0.05 to 0.3.

[0025] Further, in the heat and pressure treatment, the treatment temperature is 100 - 200 °C, the treatment time is 2 - 24 hours, and the pressure is the pressure generated by the autoclave itself.

[0026] Further, the calcium - containing compound is selected from calcium chloride or calcium oxide.

[0027] Further, the molar ratio of n(Ca) : n(P) is (2 - 6) : 1, preferably (2 - 4) : 1, where n(P) is the molar amount of P in the MTO waste catalyst.

[0028] Further, the pH is adjusted to 6 - 8, which can be achieved by adding acid.

[0029] Further, the drying conditions are 70 to 120 °C for 6 to 24 hours; the calcination conditions are 500 to 650 °C for 6 to 12 hours.

[0030] Further, for the method provided by the present invention, the extraction rate (yield) m(extracted Al):m(Al in the waste catalyst) of extracting alumina from the MTO waste catalyst is 40 to 50%.

[0031] The third aspect of the present invention provides an Al-P composite extracted from an MTO waste catalyst obtained by the method of the first aspect.

[0032] The fourth aspect of the present invention provides an alumina extracted from an MTO waste catalyst obtained by the method of the second aspect.

[0033] The fifth aspect of the present invention provides an application of the Al-P composite extracted from the MTO waste catalyst described in the third aspect, which can be used for the synthesis of SAPO molecular sieves.

[0034] The application of the Al-P composite extracted from the MTO waste catalyst provided by the present invention for the synthesis of SAPO molecular sieves includes: the phosphorus source is provided by phosphoric acid and the Al-P composite, and based on H 3 PO 4 calculation, the mass ratio of phosphoric acid to the Al-P composite is (1.1 to 100):1. The aluminum source can be completely provided by the Al-P composite or can be provided by the Al-P composite and pseudo-boehmite. Based on Al 2 O 3 calculation, the mass ratio of the Al-P composite to the aluminum source A is (0.1 to 100):1. In the mixture of the aluminum source, phosphorus source, structure-directing agent, silicon source and water, based on Al 2 O 3 calculation, based on H 3 PO 4 calculation, based on SiO 2 calculation for the silicon source, then the molar ratio of Al 2 O 3 :H 3 PO 4 :structure-directing agent:SiO 2 :H 2 O is (0.7 to 1.3):(1.4 to 3.0):(2 to 5):(0.2 to 0.9):(40 to 90). The crystallization conditions are as follows: the crystallization temperature is 180 to 220 °C, and the crystallization time is 20 to 80 hours.

[0035] The sixth aspect of the present invention provides an alumina extracted from the MTO waste catalyst described in the fourth aspect, which can be used for other smelting or the synthesis of aluminosilicate molecular sieves.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1. The waste catalyst utilized and extracted in the present invention is the waste catalyst from the MTO reaction, which contains a relatively large amount of P element.

[0038] 2. The method for extracting the Al-P composite from the MTO waste catalyst provided by the present invention is simple and easy to operate, with low cost, low requirements for equipment, and the extracted Al-P composite can be applied to the synthesis of SAPO molecular sieve, reducing the production cost of SAPO molecular sieve and realizing green preparation, and having good industrial application prospects.

[0039] 3. The method for extracting alumina from the MTO waste catalyst provided by the present invention is simple and easy to operate, with low cost, low requirements for equipment, and the extracted alumina can be used for other smelting or the synthesis of aluminosilicate molecular sieve, and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is the XRD pattern of the SAPO-34 molecular sieve obtained in Example 1 of the present invention;

[0041] Figure 2 is the SEM image of the SAPO-34 molecular sieve obtained in Example 1 of the present invention; on the left is the overall appearance of the molecular sieve, and on the right is the enlarged view. DETAILED DESCRIPTION OF THE INVENTION

[0042] In the context of this specification, including in the following examples and comparative examples, the XRD data was measured using a Bruker AXS D8 Advance X-ray diffractometer, and the test conditions were Cu Kα radiation (40 kV, 40 mA, ), the test step size was 0.02, the step time was 12.6 s, and the test 2θ range was 5 - 50°.

[0043] In the context of this specification, including in the following examples and comparative examples, the XRF data results were obtained using an XRF-1800 produced by SHIMADZU Corporation.

[0044] In the present invention, the measurements related to the MTO waste catalyst and the Al-P composite are all based on non-oxygen elements.

[0045] In the present invention, the composition of the obtained alumina is based on non-oxygen elements, and the purity of the alumina is the proportion of aluminum element in non-oxygen elements.

[0046] The present invention will be further described below in conjunction with the examples, but the examples do not limit the protection scope of the present invention.

[0047]

Example 1

[0048] 15 g of waste MTO catalyst (this waste MTO catalyst is a post-service catalyst containing SAPO-34 molecular sieve that has undergone a conventional methanol-to-olefins reaction, and its composition and elemental ratios are shown in Table 1) was added to 80 mL of hydrochloric acid solution with a concentration of 6 mol / L. Among them, n(H + ) : n(Al + P) = 7.1, and the solid-liquid ratio (the mass ratio of the MTO waste catalyst to the acid solution) = 0.17. Then, it was transferred to an autoclave and treated at 115 °C for 15 hours. After cooling to room temperature, it was centrifuged, and the supernatant was taken. The pH was adjusted to 7 with hydrochloric acid solution, then centrifuged again, and the precipitate was taken. After washing with deionized water, it was dried at 100 °C for 12 hours and calcined at 550 °C for 6 hours to obtain the Al-P composite. The results are shown in Table 1.

[0049]

Example 2

[0050] 15 g of waste MTO catalyst (the same as in Example 1) was added to 80 mL of hydrochloric acid solution with a concentration of 6 mol / L. Among them, n(H + ) : n(Al + P) = 7.1, and the solid-liquid ratio (the mass ratio of the MTO waste catalyst to the acid solution) = 0.17. Then, it was transferred to an autoclave and treated at 150 °C for 2 hours. After cooling to room temperature, it was centrifuged, and the supernatant was taken. The pH was adjusted to 7 with hydrochloric acid solution, then centrifuged again, and the precipitate was taken. After washing with deionized water, it was dried at 100 °C for 12 hours and calcined at 550 °C for 6 hours to obtain the Al-P composite. The results are shown in Table 1. The results are shown in Table 1.

[0051]

Example 3

[0052] 15 g of waste MTO catalyst (the same as in Example 1) was added to 80 mL of hydrochloric acid solution with a concentration of 6 mol / L. Among them, n(H + ) : n(Al + P) = 7.1, and the solid-liquid ratio (the mass ratio of the MTO waste catalyst to the acid solution) = 0.17. Then, it was transferred to an autoclave and treated at 130 °C for 8 hours. After cooling to room temperature, it was centrifuged, and the supernatant was taken. The pH was adjusted to 7 with hydrochloric acid solution, then centrifuged again, and the precipitate was taken. After washing with deionized water, it was dried at 100 °C for 12 hours and calcined at 550 °C for 6 hours to obtain the Al-P composite. The results are shown in Table 1. The results are shown in Table 1.

[0053]

Comparative Example 1

[0054] 15 g of waste MTO catalyst (the same as in Example 1) was added to 80 mL of hydrochloric acid solution with a concentration of 3.0 mol / L. Among them, n(H +):n(Al + P) = 3.6, solid-liquid ratio (mass ratio of the MTO waste catalyst to the acid solution) = 0.18. Then, transfer it to an autoclave and treat it at 115 °C for 15 hours. After cooling to room temperature, centrifuge, take the supernatant, adjust the pH to 7 with hydrochloric acid solution, centrifuge again, take the precipitate, wash it with deionized water, dry it at 100 °C for 12 hours, and calcine it at 550 °C for 6 hours to obtain the Al-P composite. The results are shown in Table 1. The results are shown in Table 1.

[0055]

Comparative Example 2

[0056] 15 g of waste MTO catalyst (same as in Example 1) was added to 80 mL of hydrochloric acid solution with a concentration of 6 mol / L, where n(H + ):n(Al + P) = 7.1, solid-liquid ratio (mass ratio of the MTO waste catalyst to the acid solution) = 0.17. Then, transfer it to an autoclave and treat it at 150 °C for 2 hours. After cooling to room temperature, centrifuge, take the supernatant, adjust the pH to 5 with hydrochloric acid solution, a small amount of precipitate was produced, but the precipitate gradually disappeared during centrifugation and no product was obtained.

[0057]

Comparative Example 3

[0058] 15 g of waste MTO catalyst (same as in Example 1) was added to 80 mL of sodium hydroxide solution with a concentration of 7 mol / L, where n(OH - ):n(Al + P) = 7.1, solid-liquid ratio (mass ratio of the MTO waste catalyst to the alkali solution) = 0.15. Then, transfer it to an autoclave and treat it at 115 °C for 15 hours. After cooling to room temperature, centrifuge, take the supernatant, adjust the pH to 7 with hydrochloric acid solution, centrifuge again, take the precipitate, wash it with deionized water, dry it at 100 °C for 12 hours, and calcine it at 550 °C for 6 hours to obtain the Al-P composite. The results are shown in Table 1.

[0059]

Comparative Example 4

[0060] 15 g of waste MTO catalyst (same as in Example 1) was added to 80 mL of sodium hydroxide solution with a concentration of 8 mol / L, where n(OH - ):n(Al + P) = 8.1, solid-liquid ratio (mass ratio of the MTO waste catalyst to the alkali solution) = 0.16. Then, transfer it to an autoclave and treat it at 120 °C for 12 hours. After cooling to room temperature, centrifuge, take the supernatant, adjust the pH to 7 with hydrochloric acid solution, centrifuge again, take the precipitate, wash it with deionized water, dry it at 100 °C for 12 hours, and calcine it at 550 °C for 6 hours to obtain the Al-P composite. The results are shown in Table 1.

[0061]

Example 4

[0062] 15 g of waste MTO catalyst (same as Example 1) was added to 80 mL of sodium hydroxide solution with a concentration of 7 mol / L. Among them, n(OH - ) : n(Al + P) = 7.1, and the solid-liquid ratio (mass ratio of the MTO waste catalyst to the alkali solution) = 0.15. Then, it was transferred to an autoclave and treated at 150 °C for 2 hours. After cooling to room temperature, it was centrifuged, and the supernatant was taken. 8 g of calcium chloride was added, and n(Ca) : n(P) = 2.5. It was stirred at room temperature for 10 hours. After centrifugation, the supernatant was taken, and the pH was adjusted to about 7 with hydrochloric acid. The precipitate was taken, dried at 100 °C for 12 hours, and calcined at 550 °C for 6 hours.

[0063]

Example 5

[0064] 15 g of waste MTO catalyst (same as Example 1) was added to 80 mL of sodium hydroxide solution with a concentration of 7 mol / L. Among them, n(OH - ) : n(Al + P) = 7.1, and the solid-liquid ratio (mass ratio of the MTO waste catalyst to the alkali solution) = 0.11. Then, it was transferred to an autoclave and treated at 150 °C for 2 hours. After cooling to room temperature, it was centrifuged, and the supernatant was taken. 8 g of calcium chloride was added, and n(Ca) : n(P) = 2.5. It was stirred at room temperature for 10 hours. After centrifugation, the supernatant was taken, and the pH was adjusted to about 7 with hydrochloric acid. The precipitate was taken, dried at 100 °C for 12 hours, and calcined at 550 °C for 6 hours.

[0065]

Example 6

[0066] 15 g of waste MTO catalyst (same as Example 1) was added to 80 mL of sodium hydroxide solution with a concentration of 7 mol / L. Among them, n(OH - ) : n(Al + P) = 7.1, and the solid-liquid ratio (mass ratio of the MTO waste catalyst to the alkali solution) = 0.08. Then, it was transferred to an autoclave and treated at 150 °C for 2 hours. After cooling to room temperature, it was centrifuged, and the supernatant was taken. 8 g of calcium chloride was added, and n(Ca) : n(P) = 2.5. It was stirred at room temperature for 10 hours. After centrifugation, the supernatant was taken, and the pH was adjusted to about 7 with hydrochloric acid. The precipitate was taken, dried at 100 °C for 12 hours, and calcined at 550 °C for 6 hours.

[0067]

Comparative Example 5

[0068] 15 g of waste MTO catalyst (same as Example 1) was added to 80 mL of sodium hydroxide solution with a concentration of 7 mol / L. Among them, n(OH -):n(Al + P) = 7.1, solid-liquid ratio (mass ratio of the MTO waste catalyst to the alkali solution) = 0.15. Then, it was transferred to an autoclave and treated at 150 °C for 2 hours. After cooling to room temperature, it was centrifuged, and the supernatant was taken. 5 g of calcium chloride was added, and n(Ca):n(P) = 1.6. It was stirred at room temperature for 10 hours. Then it was centrifuged again, and the supernatant was taken. The pH was adjusted to about 7 with hydrochloric acid, and the precipitate was taken and dried at 100 °C for 12 hours and calcined at 550 °C for 6 hours.

[0069]

Example 7

[0070] Using the extracted Al-P complex as part of the aluminum source and part of the phosphorus source, phosphoric acid (85 wt% H 3 PO 4 ) and silica sol (40 wt%) were used as the silicon source and part of the phosphorus source respectively. The mass ratio of phosphoric acid to the Al-P complex was 1.3:1; pseudo-boehmite was used as part of the aluminum source, and the mass ratio of the Al-P complex to pseudo-boehmite was 12:1. Triethylamine TEA was used as the structure-directing agent. The silicon source, Al-P complex, phosphoric acid, and triethylamine TEA were added to water for mixing. The molar ratio of the raw materials was Al 2 O 3 :H 3 PO 4 :TEA:SiO 2 :H 2 O = 1.0:2.0:3.5:0.35:55. The mixture was crystallized at 200 °C with a rotation speed of 30 rpm for 60 hours. After the crystallization was completed, the crystallization product was cooled, centrifuged, washed, and dried at 100 °C for 6 hours to obtain the SAPO-34 molecular sieve.

[0071] The XRD pattern of the sample is as Figure 1 shown. It can be seen from Figure 1 that the synthesized molecular sieve has the characteristic diffraction peaks of the SAPO-34 molecular sieve. The diffraction peaks at 2θ of 9.5°, 15.9°, 20.5°, 26°, and 31° belong to the SAPO-34 molecular sieve.

[0072] As Figure 2 shown, the molecular sieve has a cubic-like morphology and a smooth particle surface. The longest side length of the SAPO-34 molecular sieve particles is 3 - 10 μm.

[0073] Table 1 Weight composition distribution and yield of the obtained Al-P complex

[0074]

[0075] Note: In the present invention, the yield of each product is calculated by mass. The yield is m(Al-P complex):m(waste catalyst).

[0076] Weight Composition Distribution and Yield of Alumina Obtained in Table 2

[0077]

[0078] Note: In the present invention, the yield of each product is calculated by mass. The yield is m(extracted Al): m(Al in the waste catalyst).

Claims

1. A method for extracting an Al-P composite from an MTO spent catalyst, comprising: pre-treating the MTO spent catalyst after service, then performing a heat and pressure treatment, centrifuging to obtain a supernatant, adjusting the pH of the solution to 6-8 to obtain a precipitate, washing, drying, and calcining to obtain the Al-P composite; wherein, the purity of the obtained Al-P composite is 95-98%; the extraction rate of the Al-P composite from the MTO spent catalyst is 70-79%; The pretreatment is to add the MTO waste catalyst after service into an acid solution, and the concentration of H + in the acid solution is 5 to 12 mol / L.

2. The method according to claim 1, characterized in that, in the Al-P composite, the weight percentage of Al is 70-80%; the weight percentage of P element is 18-25%; the weight percentage of Si is 0.5-3%.

3. The method according to claim 1, characterized in that, the MTO spent catalyst contains Si, Al, and P elements; the mass percentage of Al and P in the MTO spent catalyst is 70-80%.

4. The method according to claim 1, characterized in that, The acid solution is selected from at least one of strong acid solutions; the molar amount of the acid, calculated as H + is such that the total molar amount of Al and P in the MTO spent catalyst, calculated as the sum of the Al and P elements, n(H + ) : n(Al + P) ranges from 2 to 10.

5. The method according to claim 1, characterized in that, The acid solution is selected from at least one of hydrochloric acid, phosphoric acid, and sulfuric acid; the molar amount of the acid, calculated as H + is such that, calculated as the total molar amount of Al and P in the MTO spent catalyst in terms of the sum of the Al and P elements, the range of n(H + ) : n(Al + P) is 3 to 7.

6. The method according to claim 1 or 4, characterized in that, the mass ratio range of the MTO spent catalyst to the acid solution is 0.05-0.

3.

7. The method according to claim 1 or 4, characterized in that, the mass ratio range of the MTO spent catalyst to the acid solution is 0.1-0.

2.

8. The method according to claim 1, characterized in that, in the heat and pressure treatment, the treatment temperature is 100-200 °C, the treatment time is 2-40 hours, and the pressure is the pressure generated by the autoclave itself.

9. A method for extracting alumina from an MTO spent catalyst, comprising: pre-treating the MTO spent catalyst after service, then performing a heat and pressure treatment, centrifuging to obtain a supernatant, adding a calcium-containing compound, filtering to obtain a solution, adjusting the pH of the solution to 6-8 to obtain a precipitate, washing, drying, and calcining to obtain alumina; wherein, the purity of the obtained alumina is 94-97%; The pretreatment is to add the MTO waste catalyst after service into an alkali solution; the molar amount of the alkali, calculated by OH - is such that the total molar amount of Al and P in the MTO waste catalyst, calculated by the sum of Al and P elements, n(OH - ) : n(Al + P) ranges from 4 to 10; the calcium-containing compound is selected from calcium chloride; the calcium-containing compound is calculated as Ca, and the molar ratio of n(Ca):n(P) is (2-6):1; the MTO spent catalyst contains Si, Al, and P elements, and the mass percentage of Al and P in the MTO spent catalyst is 70-80%.

10. The method according to claim 9, characterized in that, The alkali solution is selected from at least one of strong alkali solutions; the concentration of OH - in the alkali solution is 5 to 12 mol / L.

11. The method according to claim 9, characterized in that, the alkali solution is selected from at least one of sodium hydroxide and potassium hydroxide solution.

12. The method according to claim 9, characterized in that, The molar amount of the base, calculated as OH - is such that the total molar amount of Al and P in the MTO spent catalyst, calculated as the sum of the Al and P elements, n(OH - ) : n(Al + P) ranges from 5 to 9; the mass ratio of the MTO spent catalyst to the alkali solution ranges from 0.05 to 0.

8.

13. The method according to claim 9, characterized in that, the mass ratio range of the MTO spent catalyst to the alkali solution is 0.05-0.

3.

14. The method according to claim 9, characterized in that, in the heat and pressure treatment, the treatment temperature is 100-200 °C, the treatment time is 2-24 hours, and the pressure is the pressure generated by the autoclave itself.

15. The method according to claim 9, characterized in that, In the method, the molar ratio of n(Ca):n(P) is (2-4):

1.

16. According to the method described in claim 9, characterized in that the calcination conditions are 500-650 °C for 6-12 hours.

17. An Al-P composite obtained by the method according to any one of claims 1-8.

18. An alumina obtained by the method according to any one of claims 9-16.

19. An application of the Al-P composite according to claim 17 in the synthesis of SAPO molecular sieve.

Images