A moving bed spherical catalyst for propylene production from refinery dry gas, its preparation method and application

Abstract

This invention discloses a moving bed spherical catalyst for propylene production from refinery dry gas, its preparation method, and its application. The catalyst comprises: (1) a transition metal oxide-silica solid solution; (2) an alkaline metal oxide-alumina solid solution; and (3) kaolin; wherein the mass ratio of the transition metal oxide-silica solid solution: the alkaline metal oxide-alumina solid solution: the kaolin is 15–30: 60–80: 5–10. The catalyst of this invention is applied in the chemical utilization of refinery dry gas, exhibiting high conversion rate, good selectivity, and excellent regeneration performance.

Description

Technical Field

[0001] This invention relates to the field of chemical utilization of refinery dry gas, specifically to a moving bed microsphere catalyst for propylene production from refinery dry gas, its preparation method, and its application. Background Technology

[0002] Refinery dry gas mainly refers to the tail gas from catalytic cracking, catalytic pyrolysis, and delayed coking units, containing hydrogen, nitrogen, methane, ethylene, ethane, etc. Currently, this dry gas is mainly used as low-grade fuel, which is particularly wasteful from a resource utilization perspective. On the other hand, with the popularization of new energy vehicles and the commissioning of several large-scale integrated refining and chemical projects in recent years, refining capacity has become excessive. Newly built refining units tend to choose deep catalytic cracking processes (such as DCC-plus, RTC, etc.) that produce more olefins and have a higher ethylene content in the dry gas. Furthermore, fuel-type refineries that have already been put into operation have also proposed a new goal of transforming into chemical-type refineries. Against the backdrop of the above-mentioned "oil conversion," the recovery and high-value conversion of ethylene in dry gas has become a key focus for enterprises, whether for existing or planned refining and chemical units.

[0003] Currently, there are two main ways to utilize ethylene from dry gas. One is to concentrate the ethylene through methods such as cryogenic separation, membrane separation, pressure swing adsorption separation, and oil absorption separation before feeding it into the ethylene plant. The other is to use the ethylene in the dry gas directly as a raw material for chemical conversion, such as dry gas synthesis to produce isooctene or dry gas to produce ethylbenzene. Of these two technologies, ethylene separation and concentration technology is more suitable for large refineries due to investment and other reasons, and is not very suitable for the oil conversion and upgrading needs of small and medium-sized refineries. On the other hand, existing technologies for direct chemical utilization of dry gas have not been successfully promoted in small and medium-sized refineries due to constraints such as downstream product distribution and supporting utilities. Against this backdrop, developing new dry gas chemical utilization technologies with lower investment, simpler operation, and more flexible and diverse downstream product lines is particularly attractive.

[0004] Olefin disproportionation is the process by which the C=C bonds of olefins are broken down, rearranged, and new molecules are formed under the action of a catalyst. In the field of basic organic chemical raw materials, a typical reaction is as follows: C4 molecules, mainly n-butene, react with excess polymer-grade ethylene to produce propylene through double bond substitution and rearrangement. CN200580045983.X proposes a method for producing propylene from a C4 feed containing 2-butene. This method includes contacting the feed with ethylene under metathesis reaction conditions in a metathesis reaction zone containing a metathesis catalyst of group VIB or VIIB metal oxides to provide an effluent containing propylene. CN202011126304.4 discloses a catalyst particle for olefin disproportionation reaction and its preparation method. The catalyst particle is prepared by layering and integrating a disproportionation catalyst and an isomerization catalyst, exhibiting good catalytic activity and stability when used in olefin disproportionation reaction. While the above methods involve the butene and ethylene disproportionation reaction to propylene and the catalyst, they all use pure ethylene or even polymer-grade ethylene as the ethylene feedstock, without addressing the use of refinery dry gas feedstock. This is mainly because refinery dry gas has a complex composition and many impurities, posing a significant challenge to catalyst stability. CN201510685645.8 pre-treats refinery gas through pressure swing adsorption, dry gas enrichment, and dry gas refining steps, then simultaneously feeds it into a fixed-bed reactor with a C4 feedstock containing butene. Ethylene and butene in the refinery gas are converted to propylene on the surface of the olefin double bond translocation catalyst. After separation, the mixture yields ethane-rich C2 hydrocarbons, which can be directly used as feedstock for ethylene plant cracking furnaces. Although this method proposes using olefin disproportionation to convert ethylene in refinery gas to propylene, its main objective is to obtain ethane-rich feedstock. Therefore, to improve the single-pass conversion rate of ethylene, this method employs a feedstock scheme with a large excess of butene (butene to ethylene molar ratio of (8:1) to (2:1)), which is detrimental to improving the selectivity of propylene in the product. Furthermore, this method does not address the stability of the catalyst in dry gas applications. Summary of the Invention

[0005] To address the issues of poor catalyst stability and selectivity when olefin disproportionation catalysts are applied to refinery dry gas chemical utilization scenarios, this invention provides a moving bed microsphere catalyst for propylene production from refinery dry gas, its preparation method, and its application. The catalyst of this invention exhibits extremely high strength and excellent flowability, and can be used in the moving bed catalytic reaction of propylene production from refinery dry gas, achieving stable propylene production.

[0006] The first aspect of the present invention provides a moving bed microsphere catalyst for the disproportionation of refinery dry gas to propylene, comprising: (1) a transition metal oxide-silica solid solution; (2) an alkaline metal oxide-alumina solid solution; and (3) kaolin; wherein the mass ratio of the transition metal oxide-silica solid solution to the alkaline metal oxide-alumina solid solution to the kaolin is 15-30:60-80:5-10.

[0007] In the above technical solution, the mass ratio of transition metal oxide to silicon oxide is 0.05 to 0.18, and the mass ratio of alkali metal oxide to aluminum oxide is 0.05 to 0.25.

[0008] In the above technical solution, the alkaline metal oxide-alumina solid solution is an alkali metal oxide-alumina solid solution, an alkaline earth metal oxide-alumina solid solution, or an alkali metal oxide and alkaline earth metal oxide-alumina solid solution.

[0009] In the above technical solution, the catalyst contains, based on the catalyst weight, a total content of transition metal oxides and silicon oxide of 15% to 30%, a total content of alkali metal oxides and aluminum oxide of 60% to 80%, and a kaolin content of 5% to 10%.

[0010] In the above technical solution, the transition metal element is selected from at least one of Group VIB elements or Group VIIB elements, preferably at least one of Group VIB elements Mo and W, and more preferably W; the alkali metal is selected from at least one of alkali metals and alkaline earth metals, the alkali metal element is selected from Na or K, preferably K, and the alkaline earth metal element is selected from Mg or Ca, preferably Mg.

[0011] In the above technical solution, the average size of the small spherical catalyst is 2-5 mm, and the crushing strength of the catalyst particles is ≥80 N / particle.

[0012] The present invention provides a method for preparing the above-mentioned moving bed spherical catalyst for propylene production from refinery dry gas, comprising:

[0013] (1) Preparation of transition metal oxide-silicon oxide solid solution;

[0014] (2) Preparation of alkaline metal oxide-alumina solid solution;

[0015] (3) The solid solution described in step (1) and the solid solution described in step (2) are mixed with kaolin, and the mixture is subjected to rolling, curing, drying and calcination to obtain the catalyst.

[0016] In the above technical solution, in step (1), the solid solution is prepared by equal-volume impregnation or mechanical mixing. Specifically, a precursor is obtained by impregnating a transition metal salt solution with a silica carrier in equal volume or by mechanically mixing and grinding a silica carrier with a transition metal salt. The precursor is then dried and calcined to obtain a transition metal oxide-silica solid solution, which is then powdered and sieved for later use.

[0017] In the above technical solution, in step (1), when using the equal-volume impregnation method, the transition metal salt is dissolved in deionized water, and the mass ratio of salt to water is 1:1 to 1:100, preferably 1:3 to 1:30. The mass ratio of the transition metal salt (calculated as oxide) to silicon oxide is 0.05 to 0.18. The transition metal salt is selected from at least one of the nitrates or ammonium salts of transition metals, preferably ammonium metatungstate.

[0018] In the above technical solution, in step (1), the drying conditions are: temperature of 60-150℃, preferably 80-120℃, and time of 8-48h, preferably 10-18h. The calcination conditions are: temperature of 400-650℃, preferably 450-560℃, and time of 0.5-6h, preferably 1-6h.

[0019] In the above technical solution, in step (1), the particle size of the solid solution after pulverization and sieving is 400-800 mesh.

[0020] In the above technical solution, in step (2), the solid solution is prepared by equal-volume impregnation or mechanical mixing. Specifically, an alumina carrier is impregnated with an alkaline metal salt solution in equal volume, or the alumina carrier and the alkaline metal salt are mechanically mixed and ground to obtain a precursor, which is then dried and calcined to obtain an alkaline metal oxide-alumina solid solution, which is then powdered and sieved for later use.

[0021] In the above technical solution, in step (2), when using the equal-volume impregnation method, the alkaline metal salt is dissolved in deionized water, and the mass ratio of salt to water is 1:1 to 1:100, preferably 1:3 to 1:30. The mass ratio of the alkaline metal (calculated as oxide) to silicon oxide is 0.05 to 0.25. The alkaline metal salt is selected from at least one of nitrates and acetates.

[0022] In the above technical solution, in step (2), the drying conditions are: temperature of 60-150℃, preferably 80-120℃, and time of 8-48h, preferably 10-18h. The calcination conditions are: temperature of 400-650℃, preferably 450-560℃, and time of 0.5-6h, preferably 1-6h.

[0023] In the above technical solution, in step (2), the particle size of the solid solution after pulverization and sieving is 400-800 mesh.

[0024] In the above technical solution, in step (3), the rolling ball is made from a mixture of solid solution obtained in steps (1) and (2) and kaolin, and is rolled in a rolling ball machine to obtain small balls. The mass ratio of solid solution in step (1): solid solution in step (2): kaolin is 15-30: 60-80: 5-10.

[0025] In the above technical solution, in step (3), the conditioning conditions are: temperature 25-40℃, time 8-48h. The drying conditions are: temperature 60-150℃, preferably 80-120℃, time 8-48h, preferably 10-18h. The calcination conditions are: temperature 400-650℃, preferably 450-560℃, time 0.5-6h, preferably 1-6h.

[0026] A third aspect of the present invention provides a method for producing propylene by disproportionation of dry gas and C4 gas, comprising mixing a dry gas feedstock containing ethylene with a C4 feedstock containing butene, and then reacting the mixture with the aforementioned moving bed microsphere catalyst to obtain propylene.

[0027] In the above technical solution, the hydrogen content in the dry gas feedstock containing ethylene is controlled below 1 vol%, the isobutylene content in the C4 feedstock containing butene is controlled below 5 wt%, and the butadiene content is controlled below 1 wt%.

[0028] In the above technical solution, the ethylene content in the dry gas feedstock containing ethylene is above 20 vol%, and the total content of 1-butene and 2-butene in the C4 feedstock containing butene is above 30 wt%.

[0029] In the above technical solution, the reaction temperature is 250–350°C; the reaction pressure is 1.0–3.0 MPa; and the total weight hourly space velocity (WHSV) of the dry gas feedstock and C4 feedstock is 1.0–4.0 h⁻¹. -1 The molar ratio of ethylene to butene at the reactor inlet is 0.5 to 1.5.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The catalyst of this invention is a moving bed olefin disproportionation microsphere catalyst containing dual active sites, namely, disproportionation and isomerization active sites. The disproportionation active site catalyzes the reaction of ethylene and 2-butene to produce propylene, while the isomerization active site converts 1-butene to 2-butene. The combined action of these two active sites enables the catalyst to fully convert ethylene and butene in the feedstock. To prevent the loss and overlapping of these two types of active sites during continuous regeneration of the moving bed catalyst, this invention employs a stepwise preparation method to place the disproportionation and isomerization dual active sites onto different supports. Subsequently, the two types of powders containing different active sites are thoroughly mixed with kaolin and rolled to form high-strength spherical olefin disproportionation catalyst particles. The coexistence of the two types of active sites at the micron scale within the same catalyst particle gives the catalyst high activity, selectivity, and excellent regeneration performance.

[0032] 2. The catalyst of this invention is applied to the chemical utilization of dry gas from refineries. Pretreated dry gas, after being mixed with C4, is efficiently converted into propylene in a moving bed reactor loaded with this catalyst. Further separation can yield high-purity propylene. The catalyst exhibits high conversion rate, good selectivity, and excellent regeneration performance. Specifically, the propylene selectivity is over 90%, and the single-pass conversion rate of ethylene in the dry gas is over 50%. The moving bed catalyst effectively solves the problem of olefin disproportionation catalysts being sensitive to impurities in the dry gas from refining plants and prone to poisoning and deactivation, providing a new and viable approach for the chemical utilization of dry gas. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0034] All raw materials used in the embodiments of this invention are conventional commercially available raw materials.

[0035] Example 1

[0036] WO3 / SiO2 solid solution (WO3:SiO2 (mass ratio) = 0.054). Weigh 100 kg of 99.5% pure silica powder and 6 kg of ammonium metatungstate (WO3 ≥ 90%). Dissolve the above tungsten salt in 20 kg of deionized water and impregnate the silica powder with an equal volume for 6 hours. Then place the impregnated silica in an oven and dry at 120℃ for 12 hours, followed by calcination at 450℃ for 4 hours to obtain the WO3 / SiO2 solid solution. After grinding, pass the solution through a 400-800 mesh sieve for later use.

[0037] Example 2

[0038] WO3 / SiO2 solid solution (WO3∶SiO2 (mass ratio)=0.144). Weigh 100kg of 99.5% pure silica powder and 16kg of ammonium metatungstate (WO3≥90%). Mix the above tungsten salt and silica powder, mechanically grind them evenly, and then calcine them at 550℃ for 4h to obtain the WO3 / SiO2 solid solution. After pulverizing, pass it through a 400-800 mesh sieve for later use.

[0039] Example 3

[0040] MgO / Al₂O₃ solid solution (MgO:Al₂O₃ (mass ratio) = 0.093). Weigh 100 kg of γ-Al₂O₃ and 50 kg of magnesium acetate tetrahydrate. Dissolve the magnesium salt in 150 kg of deionized water and impregnate an equal volume of alumina powder for 6 hours. Then, place the impregnated alumina in an oven and dry it at 80°C for 12 hours. After calcining at 520°C for 4 hours, the MgO / Al₂O₃ solid solution is obtained. After grinding, it is passed through a 400-800 mesh sieve for later use.

[0041] Example 4

[0042] K2O / Al2O3 solid solution (K2O∶Al2O3 (mass ratio)=0.204). Weigh 100kg γ-Al2O3 and 30kg potassium carbonate, then mix the potassium carbonate and alumina powder, mechanically grind them evenly, and calcine them at 550℃ for 4h to obtain the K2O / Al2O3 solid solution. After pulverizing, pass it through a 400~800 mesh sieve for later use.

[0043] Example 5

[0044] 20 kg of the solid solution from Example 1, 70 kg of the solid solution from Example 3, and 10 kg of kaolin were weighed and mixed in a kneader as dry powder for 2 hours. The resulting mixed powder was then spheroidized in a spheroidizing machine, with the sphere size controlled at 2–3 mm. To ensure the powder particles could adhere to each other, water was sprayed appropriately during the spheroidizing process, depending on the sphere formation. After curing the spheroids at room temperature for 24 hours, they were dried in a 120°C oven for 12 hours and then calcined at 550°C for 4 hours to obtain the finished spheroid catalyst A.

[0045] Example 6

[0046] 30 kg of the solid solution from Example 1, 60 kg of the solid solution from Example 4, and 10 kg of kaolin were weighed and mixed in a kneader as dry powder for 2 hours. The resulting powder mixture was then balled in a ballering machine, with the ball size controlled at 3–4 mm. To ensure the powder particles could adhere to each other, water was sprayed appropriately during the balling process, depending on the ball formation. After the balls were cured at room temperature for 24 hours, they were dried in a 120°C oven for 18 hours and then calcined at 550°C for 4 hours to obtain the finished small ball catalyst B.

[0047] Example 7

[0048] 15 kg of the solid solution from Example 2, 80 kg of the solid solution from Example 3, and 5 kg of kaolin were weighed and mixed in a kneader as dry powder for 2 hours. The resulting mixed powder was then spheroidized in a spheroidizing machine, with the sphere size controlled at 2–3 mm. To ensure the powder particles could adhere to each other, water was sprayed appropriately during the spheroidizing process, depending on the sphere formation. After curing the spheroids at room temperature for 24 hours, they were dried in a 120°C oven for 10 hours and then calcined at 550°C for 3 hours to obtain the finished spheroid catalyst C.

[0049] Example 8

[0050] 25 kg of the solid solution from Example 2, 65 kg of the solid solution from Example 4, and 10 kg of kaolin were weighed and mixed in a kneader as dry powder for 2 hours. The resulting mixed powder was then spheroidized in a spheroidizing machine, with the sphere size controlled at 4–5 mm. To ensure the powder particles could adhere to each other, water was sprayed appropriately during the spheroidizing process, depending on the sphere formation. After curing the spheroids at room temperature for 24 hours, they were dried in a 120°C oven for 24 hours and then calcined at 500°C for 6 hours to obtain the finished spheroid catalyst D.

[0051] Comparative Example 1

[0052] 5 kg of the solid solution from Example 1, 90 kg of the solid solution from Example 3, and 5 kg of kaolin were weighed and mixed in a kneader as dry powder for 2 hours. The resulting mixed powder was then balled in a ballering machine, with the ball size controlled at 2-3 mm. To ensure the powder particles could adhere to each other, water was sprayed appropriately during the balling process, depending on the ball formation. After the balls were cured at room temperature for 24 hours, they were dried in a 120°C oven for 12 hours and then calcined at 550°C for 4 hours to obtain the finished small ball catalyst E.

[0053] Comparative Example 2

[0054] 75 kg of the solid solution from Example 1, 20 kg of the solid solution from Example 3, and 5 kg of kaolin were weighed and mixed in a kneader as dry powder for 2 hours. The resulting mixed powder was then spheroidized in a spheroidizing machine, with the sphere size controlled at 2–3 mm. To ensure the powder particles could adhere to each other, water was sprayed appropriately during the spheroidizing process, depending on the sphere formation. After curing the spheroids at room temperature for 24 hours, they were dried in a 120°C oven for 12 hours and then calcined at 550°C for 4 hours to obtain the finished spheroid catalyst F.

[0055] Comparative Example 3

[0056] 20 kg of the solid solution from Example 2 and 80 kg of the solid solution from Example 3 were weighed and mixed in a kneader as dry powder for 2 hours. The resulting mixed powder was then spherically shaped in a spheroidizing machine, with the sphere size controlled at 2–3 mm. After curing at room temperature for 24 hours, the shaped spheres were dried in a 120°C oven for 10 hours and then calcined at 550°C for 3 hours to obtain the finished spherical catalyst G.

[0057] Comparative Example 4

[0058] 15 kg of the solid solution from Example 1, 60 kg of the solid solution from Example 3, and 25 kg of kaolin were weighed and mixed in a kneader as dry powder for 2 hours. The resulting mixed powder was then spheroidized in a spheroidizing machine, with the sphere size controlled at 2–3 mm. To ensure the powder particles could adhere to each other, water was sprayed appropriately during the spheroidizing process, depending on the sphere formation. After curing the spheroids at room temperature for 24 hours, they were dried in a 120°C oven for 12 hours and then calcined at 550°C for 4 hours to obtain the finished spheroid catalyst H.

[0059] Comparative Example 5

[0060] Weigh 15 kg of 99.5% pure silica powder and 60 kg of γ-Al₂O₃ powder, mix them in a kneader as dry powder for 2 hours. Dissolve 1.2 kg of ammonium metatungstate and 5.6 kg of magnesium acetate tetrahydrate in deionized water, and impregnate the silica and alumina mixture powder by volume for 6 hours. Place the impregnated powder in an oven and dry it overnight at 120°C. After drying, grind the powder, pass it through a 400-800 mesh sieve, add 10 kg of kaolin and mix evenly, then shape it into balls. To ensure the powder adheres to each other, spray water appropriately during the ball-forming process, depending on the ball formation. After the shaped balls are cured at room temperature for 24 hours, they are dried in an oven at 120°C for 12 hours, and then calcined at 550°C for 4 hours to obtain the finished small ball catalyst I.

[0061] Comparative Example 6

[0062] 15 kg of the solid solution from Example 2 and 1.5 kg of kaolin were weighed and mixed in a kneader as dry powder for 2 hours. The resulting powder was then balled in a ball-rolling machine, with the ball size controlled at 2-3 mm. Next, 80 kg of the solid solution from Example 3 and 3.5 kg of kaolin were weighed and mixed in a kneader as dry powder for 2 hours. The resulting powder was then balled in a ball-rolling machine, with the ball size controlled at 2-3 mm. To ensure the powders could adhere to each other, water was sprayed appropriately during the ball-rolling process, depending on the ball formation. After the two types of balls were cured at room temperature for 24 hours, they were dried in a 120°C oven for 10 hours and calcined at 550°C for 3 hours. Afterward, the two types of balls were mechanically mixed evenly to obtain the finished small-ball catalyst J.

[0063] Example 9

[0064] Catalyst strength determination. The crushing strength of the small-sphere catalysts prepared in Examples 5-8 (catalyst AD) and Comparative Examples 1-6 (catalyst EJ) was measured using a Dalian Penghui DL4 intelligent particle strength tester, and the average value was taken. The results are shown in Table 2. The results show that the crushing strength of the small-sphere catalyst G without kaolin is relatively low and cannot fully meet the requirements of a moving bed catalyst.

[0065] Table 1. Composition of the microsphere catalysts obtained in each example.

[0066]

[0067]

[0068] Table 2 shows the crushing strength of the obtained microsphere catalysts in each example.

[0069]

[0070] Example 10

[0071] Catalyst performance evaluation. The catalysts prepared in Examples 5-8 (catalyst AD) and Comparative Examples 1-6 (catalyst EJ) were pressed, crushed, and sieved. 20-40 mesh catalyst samples were loaded into a moving bed reactor with a diameter of 8 mm. The catalysts were activated sequentially at 550°C with air and high-purity nitrogen to fully expose the active sites. Then, ethylene (20 vol%, balance methane) and C4 (1-butene, 99.5 wt%) were introduced into the reaction tube and reacted in the catalytic bed. The reaction temperature was 290°C, the reaction system pressure was 2.0 MPa, and the feedstock space velocity was 1.0 h⁻¹. -1 The disproportionation reaction was carried out under conditions where the ethylene:butene (molar ratio) was 0.5. The reaction results are shown in Table 3.

[0072] Table 3. Catalytic performance of the obtained microsphere catalysts in each example.

[0073]

[0074]

[0075] Example 11

[0076] Catalyst regeneration. The deactivated catalyst was selected for online regeneration. It was sequentially coked and activated at 550°C with air and high-purity nitrogen, respectively, to re-expose active sites. The regenerated catalyst was then evaluated for performance. This process was repeated multiple times to examine the catalyst regeneration performance; the results are shown in Tables 4 and 5. It can be seen that Example 7 (catalyst C) exhibited good regeneration performance after multiple regenerations. In Comparative Example 6 (catalyst J), the moving bed caused gradual stratification of the disproportionate and isomerized catalytic components after regeneration, resulting in a gradual decrease in catalytic activity with each regeneration.

[0077] Table 4 Regeneration performance of spherical catalyst C

[0078]

[0079] Table 5 Regeneration performance of spherical catalyst J

[0080]

[0081] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A moving bed microsphere catalyst for the disproportionation of refinery dry gas to propylene, comprising: (1) Transition metal oxide-silicon oxide solid solution; (2) Alkaline metal oxide-alumina solid solution; (3) Kaolin; wherein the mass ratio of transition metal oxide-silica solid solution: alkaline metal oxide-alumina solid solution: kaolin is 15~30:60~80:5~10; the mass ratio of alkaline metal oxide to alumina is 0.05~0.25, and the mass ratio of transition metal oxide to silica is 0.05~0.18; The method for preparing the catalyst includes: (1) Preparation of transition metal oxide-silicon oxide solid solution; (2) Preparation of alkaline metal oxide-alumina solid solution; (3) The solid solution described in step (1) and the solid solution described in step (2) are mixed with kaolin, and the mixture is rolled, cured, dried and calcined to obtain the catalyst.

2. The catalyst according to claim 1, characterized in that: The catalyst, based on its weight, contains 15% to 30% total transition metal oxides and silicon dioxide, 60% to 80% total alkali metal oxides and aluminum oxide, and 5% to 10% kaolin.

3. The catalyst according to claim 1, characterized in that: The transition metal element is selected from at least one element from Group IB or Group IIB; the alkali metal is selected from at least one alkali metal and alkaline earth metal; the alkaline earth metal element is selected from Mg or Ca.

4. The catalyst according to claim 3, characterized in that: The transition metal element is selected from at least one of the group VIB elements Mo and W; the alkali metal element is selected from Na or K; and the alkaline earth metal element is Mg.

5. The catalyst according to claim 4, characterized in that: The transition metal element is W; the alkali metal element is K.

6. The catalyst according to claim 1, characterized in that: The catalyst has an average size of 2-5 mm and a particle crushing strength of ≥80 N / particle.

7. A method for preparing the catalyst according to any one of claims 1-6, comprising: (1) Preparation of transition metal oxide-silicon oxide solid solution; (2) Preparation of alkaline metal oxide-alumina solid solution; (3) The solid solution described in step (1) and the solid solution described in step (2) are mixed with kaolin, and the mixture is rolled, cured, dried and calcined to obtain the catalyst.

8. The preparation method according to claim 7, characterized in that: In step (1) or step (2), the solid solution is prepared by equal volume impregnation or mechanical mixing.

9. The preparation method according to claim 7, characterized in that: In step (1), when using the equal volume impregnation method, the transition metal salt is dissolved in deionized water, and the mass ratio of salt to water is 1:1 to 1:

100. In step (2), when using the equal volume impregnation method, the alkaline metal salt is dissolved in deionized water, and the mass ratio of salt to water is 1:1 to 1:

100.

10. The preparation method according to claim 9, characterized in that: In step (1), when using the equal volume impregnation method, the transition metal salt is dissolved in deionized water, and the mass ratio of salt to water is 1:3~1:30; In step (2), when using the equal volume impregnation method, the alkaline metal salt is dissolved in deionized water, and the mass ratio of salt to water is 1:3 to 1:

30.

11. The preparation method according to claim 7, characterized in that: The particle size of the solid solution after pulverization and sieving in step (1) or step (2) is independently selected from 400~800 mesh.

12. The preparation method according to claim 7, characterized in that: In step (3), the health preservation conditions are: temperature 25~40℃, time 8~48h; The drying conditions are: temperature 60~150℃, time 8~48h; The roasting conditions are: temperature 400~650℃, time 0.5~6h.

13. The preparation method according to claim 12, characterized in that: In step (3), the drying conditions are: temperature 80~120℃, time 10~18h; the calcination conditions are: temperature 450~560℃, time 1~6h.

14. A method for producing propylene by disproportionation of dry gas and C4, comprising mixing a dry gas feedstock containing ethylene with a C4 feedstock containing butene, and then reacting the mixture with a moving bed microsphere catalyst as described in any one of claims 1-6 to obtain propylene.

15. The method according to claim 14, characterized in that: The hydrogen content in the dry gas containing ethylene is controlled below 1 vol%, the isobutene content in the C4 feedstock containing butene is controlled below 5 wt%, and the butadiene content is controlled below 1 wt%.

16. The method according to claim 15, characterized in that: The reaction temperature is 250~350℃; the reaction pressure is 1.0~3.0MPa; and the total weight hourly space velocity (WHSV) of the raw materials is 1.0-4.0h. -1 ; The ethylene:butene molar ratio at the reactor inlet is 0.5~1.5.

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