A catalyst for diesel catalytic cracking to produce low-carbon olefins, a preparation method and application thereof

Abstract

The present application provides a kind of catalyst for diesel catalytic cracking to prepare low carbon olefin, its preparation method and application, comprising the following steps: A) ZSM-11 molecular sieve is mixed with water ball mill, then kaolin, aluminum sol, metal precursor and phosphorus precursor are added, to obtain mixed slurry A;B) mixed slurry is mixed with soft template, to obtain mixed slurry B;The soft template includes one or several of sucrose, glucose and fructose;C) after ball milling, mixed slurry B is sprayed and granulated, to obtain microspheric granule;D) the microspheric granule is calcined, to obtain the catalyst for diesel catalytic cracking to prepare low carbon olefin.The present application introduces soft template agent in the forming process, so as to introduce macropore in matrix, so that the activity and heavy metal resistance of catalyst can be improved, and the catalyst prepared by this method has the advantages of high activity, high selectivity and good diffusion for diesel cracking reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of petroleum catalytic cracking, and in particular relates to a catalyst for catalytic cracking of diesel to produce light olefins, a preparation method and application thereof. Background Art

[0002] Ethylene and propylene, important basic raw materials in the petrochemical industry, are traditionally produced primarily through tubular furnace steam cracking. Cracked feedstocks include naphtha, diesel, ethane, and liquefied petroleum gas (LPG). However, with the rapid increase in demand for olefin derivatives, the propylene produced through co-production via thermal cracking is no longer sufficient to meet the growing demand in both domestic and international markets. Furthermore, steam pyrolysis itself has numerous shortcomings. Therefore, optimizing the allocation of cracking feedstock resources and adopting new processes and technologies to replace traditional steam pyrolysis to produce light olefins has become an inevitable trend in this field. Technologies to increase the production of light olefins, particularly propylene, such as methanol-to-olefins (MTO / MTP), heavy oil catalytic cracking (DCC, CPP, HCC), propane dehydrogenation, and light hydrocarbon catalytic cracking, have emerged and developed in recent years, partially alleviating market demand for propylene.

[0003] my country currently faces a dilemma: overcapacity in refining and insufficient chemical supply. Demand for petrochemical raw materials exceeds supply, forcing refineries to reduce capacity, adjust their structures, and transition to the chemical industry. Catalytic cracking of light naphtha hydrocarbons to olefins has matured and is now in use. Some companies have adopted KBR's ACO / K-COT process to convert naphtha into high-value-added chemicals such as ethylene and propylene. For diesel, hydrotreating combined with catalytic cracking (LTAG and FCA), hydrotreating combined with hydrocracking (FD2G and RLG), and diesel adsorption separation technology packages can address diesel disposal issues to a certain extent, but they cannot fundamentally address the need for diesel reduction for most refineries. Therefore, reducing diesel production and realizing high-value-added utilization of excess diesel capacity have become pressing issues for refineries. Summary of the Invention

[0004] The purpose of the present invention is to provide a catalyst for catalytic cracking of diesel to produce light olefins, its preparation method and application. The catalyst of the present invention has high reaction activity and good selectivity for diesel cracking, and has the advantage of high yield of liquefied gas and propylene.

[0005] The present invention provides a method for preparing a catalyst for catalytic cracking of diesel to produce light olefins, comprising the following steps:

[0006] A) After mixing ZSM-11 molecular sieve and water by ball milling, kaolin, aluminum sol, metal precursor and phosphorus precursor are added to obtain mixed slurry A;

[0007] B) mixing the mixed slurry with the soft template to obtain mixed slurry B;

[0008] The soft template includes one or more of sucrose, glucose and fructose;

[0009] C) ball-milling the mixed slurry B and spray-granulating the mixed slurry B to obtain microsphere particles;

[0010] D) calcining the microsphere particles to obtain a catalyst for catalytic cracking of diesel to produce light olefins.

[0011] Preferably, the ZSM-11 molecular sieve has straight pores with a pore diameter of 0.5 to 0.6 nm.

[0012] Preferably, the metal in the metal precursor includes one or more of lanthanum, cerium, zinc, iron, magnesium, manganese, zirconium, copper and silver.

[0013] Preferably, the phosphorus precursor includes one or more of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate and trimethyl phosphate.

[0014] Preferably, the mass ratio of ZSM-11 molecular sieve, aluminum sol, kaolin, phosphorus precursor and metal precursor is (10-50): (10-50): (30-70): (5-20): (0.5-5).

[0015] Preferably, the mass of the soft template is 0.1-15% of the mass of the dry basis catalyst, and the dry basis catalyst includes ZSM-11 molecular sieve, kaolin, aluminum sol, metal oxides and phosphorus oxides.

[0016] Preferably, the calcination temperature is 450° C. to 550° C., and the calcination time is 3 to 6 hours.

[0017] The present invention provides a catalyst for catalytic cracking of diesel to produce light olefins, which is prepared by the preparation method described above.

[0018] Preferably, the catalyst for catalytic cracking of diesel to produce light olefins has a microporous structure, a mesoporous structure and a macroporous structure, an average pore diameter of the catalyst is 6-10 nm, and a pore volume is 0.3-0.4 cc / g.

[0019] The present invention provides use of the catalyst for producing light olefins by catalytic cracking of diesel as described above in producing light olefins and liquefied gas by catalytic cracking of diesel.

[0020] The invention provides a preparation method of a catalyst for producing light olefins by catalytic cracking of diesel, comprising the following steps: A) ball-milling ZSM-11 molecular sieve and water, and then adding kaolin, aluminum sol, a metal precursor, and a phosphorus precursor to obtain a mixed slurry A; B) mixing the mixed slurry with a soft template to obtain a mixed slurry B, wherein the soft template comprises one or more of sucrose, glucose, and fructose; C) ball-milling the mixed slurry B and then spray-granulating the mixed slurry to obtain microsphere particles; and D) calcining the microsphere particles to obtain a catalyst for producing light olefins by catalytic cracking of diesel.

[0021] ZSM-5 molecular sieve is the most widely used active component in heavy oil catalytic cracking processes for propylene production. Its pore structure selectively cracks some gasoline components, resulting in high yields of light olefins. However, it also presents several challenges. The complex Zig-Zag pores of ZSM-5 have high diffusion resistance, hindering rapid product diffusion and increasing the likelihood of secondary reactions. Some researchers have treated ZSM-5 molecular sieves with pore expansion, a process that damages the structure and reduces its stability. ZSM-11 molecular sieve is structurally similar to ZSM-5, but also unique in that its pores are straight, reducing the diffusion resistance of reactant molecules within the sieve, thereby effectively reducing hydrogen transfer reactions for light olefins and improving olefin selectivity. However, due to its small pore size, cycloalkanes in diesel fuel cannot fully react. The present invention introduces a soft template during the molding process, creating large pores in the matrix, which improves catalyst activity and heavy metal resistance. Catalysts prepared using this method have the advantages of high activity, high selectivity, and good diffusivity for diesel cracking reactions. DETAILED DESCRIPTION

[0022] The present invention provides a method for preparing a catalyst for catalytic cracking of diesel to produce light olefins, comprising the following steps:

[0023] A) After mixing ZSM-11 molecular sieve and water by ball milling, kaolin, aluminum sol, metal precursor and phosphorus precursor are added to obtain mixed slurry A;

[0024] B) mixing the mixed slurry with the soft template to obtain mixed slurry B;

[0025] The soft template includes one or more of sucrose, glucose and fructose;

[0026] C) ball-milling the mixed slurry B and spray-granulating the mixed slurry B to obtain microsphere particles;

[0027] D) calcining the microsphere particles to obtain a catalyst for catalytic cracking of diesel to produce light olefins.

[0028] In the present invention, the ZSM-11 molecular sieve is preferably first mixed with water, and then ball-milled in a ball mill to obtain a molecular sieve slurry.

[0029] In the present invention, the ZSM-11 molecular sieve has straight channels, and the pore diameter is preferably 0.5-0.6 nm. Specifically, in an embodiment of the present invention, the ZSM-11 molecular sieve is formed by the intersection of two-dimensional straight channels of elliptical ten-membered rings with a pore diameter of 0.51 nm×0.55 nm.

[0030] In the present invention, kaolin and aluminum sol are stirred and mixed with water, and then added into molecular sieve slurry, mixed and slurried, and then metal precursor and phosphorus precursor are added in sequence and stirred to obtain mixed slurry A.

[0031] In the present invention, the metal precursor is preferably a metal salt, which forms a metal oxide after calcination, more preferably a metal nitrate, wherein the metal is preferably one or more of lanthanum, cerium, zinc, iron, magnesium, manganese, zirconium, copper and silver. Specifically, the metal precursor can be one or more of lanthanum nitrate, zirconium nitrate and copper nitrate.

[0032] In the present invention, the phosphorus precursor forms phosphorus oxide after calcination, preferably one or more of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate and trimethyl phosphate.

[0033] After obtaining the mixed slurry A, the present invention adds cork boards therein and stirs them evenly to obtain the mixed slurry B.

[0034] In the present invention, the soft template includes one or more of sucrose, glucose and fructose.

[0035] In the present invention, the mass ratio of the ZSM-11 molecular sieve, aluminum sol, kaolin, phosphorus precursor and metal precursor is preferably (10-50): (10-50): (30-70): (5-20): (0.5-5), more preferably (20-40): (20-40): (40-65): (10-20): (1-4), and further preferably (30-35): (25-30): (50-65): (15-18): (2-3).

[0036] After obtaining the mixed slurry A, the present invention adds the soft template into the mixed slurry A and stirs it evenly to obtain the mixed slurry B.

[0037] The present invention controls the size of the introduced pores by controlling the size and amount of the introduced soft template. In the present invention, the soft template comprises one or more of sucrose, glucose, and fructose; the mass of the soft template is preferably 0.1-15% of the dry mass of the catalyst, more preferably 0.5-10%, such as 0.1%, 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, preferably within a range with any of the above values ​​as the upper or lower limit. In the present invention, the dry mass of the catalyst is the ZSM-11 molecular sieve, kaolin, aluminum sol, metal oxide, and phosphorus oxide described above.

[0038] After obtaining the mixed slurry B, the present invention uses a ball mill to ball mill the mixed slurry B, and the milled slurry is spray granulated using a high-temperature spray centrifugal device to obtain microsphere particles.

[0039] In the present invention, the temperature of the spray granulation is preferably 300-400° C., and the particle size of the microsphere particles is preferably 20-150 μm.

[0040] After obtaining the microsphere particles, the present invention bakes the microsphere particles in an oxygen-containing atmosphere, such as air, to obtain a catalyst for catalytic cracking of diesel to produce light olefins.

[0041] In the present invention, the calcination temperature is preferably 450° C. to 550° C., more preferably 500° C. to 540° C., and the calcination time is 3 to 6 hours, more preferably 4 to 5 hours.

[0042] The present invention also provides a catalyst for catalytic cracking of diesel to produce light olefins, which is prepared by the preparation method described above.

[0043] The catalyst of the present invention has a pore structure characterized by micropores, mesopores and macropores, with an average pore diameter of 6-10 nm and a pore volume of 0.3-0.4 cc / g. In the present invention, the micropore size is 0.5-2 nm; the mesopore size is 2-40 nm; and the macropore size is 60.

[0044] The present invention also provides the use of the above-mentioned catalyst for catalytic cracking of diesel to produce light olefins in the catalytic cracking of diesel to produce light olefins and liquefied gas. The catalyst of the present invention has the advantages of high activity, good selectivity, and ease of industrial application. In particular, it has a significant effect on improving the yield of light olefin products and liquefied gas products from the catalytic cracking of diesel.

[0045] To further illustrate the present invention, a catalyst for catalytic cracking of diesel to produce light olefins, its preparation method and application provided by the present invention are described in detail below in conjunction with examples, but it should not be understood as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] 30 g of ZSM-11 molecular sieve was added to 100 g of deoxygenated ionized water, and the mixture was milled and mixed uniformly in a ball mill to obtain slurry A.

[0048] 65 g of kaolin and 30 g of aluminum sol were added to 100 g of deoxygenated ionized water, and the mixture was stirred evenly. Slurry A was then added and mixed and beaten to obtain slurry B.

[0049] 2 g of lanthanum nitrate was added to slurry B and stirred to obtain slurry C.

[0050] 15 g of ammonium dihydrogen phosphate was added to slurry C and stirred to obtain slurry D.

[0051] 15 g of glucose was added to slurry D and stirred to obtain slurry E.

[0052] The slurry E is ball-milled using a ball mill, and the ball-milled slurry is formed using a high-temperature spray centrifugal device to obtain microsphere particles.

[0053] The microsphere catalyst was calcined in air at 540°C for 4 h, and the calcined catalyst was evaluated using a riser.

[0054] Example 2

[0055] 35 g of ZSM-11 molecular sieve was added to 100 g of deoxygenated ionized water, and the mixture was milled and mixed uniformly in a ball mill to obtain slurry A.

[0056] 65 g of kaolin and 30 g of aluminum sol were added to 100 g of deoxygenated ionized water, and the mixture was stirred evenly. Slurry A was then added and mixed and beaten to obtain slurry B.

[0057] 2 g of zirconium nitrate was added to slurry B and stirred to obtain slurry C.

[0058] 16 g of ammonium dihydrogen phosphate was added to slurry C, and the mixture was stirred evenly to obtain slurry D.

[0059] 20 g of glucose was added to slurry D and stirred to obtain slurry E.

[0060] The slurry E is ball-milled using a ball mill, and the ball-milled slurry is formed using a high-temperature spray centrifugal device to obtain microsphere particles.

[0061] The microsphere catalyst was calcined in air at 540°C for 4 h, and the calcined catalyst was evaluated using a riser.

[0062] Example 3

[0063] 35 g of ZSM-11 molecular sieve was added to 100 g of deoxygenated ionized water, and the mixture was milled and mixed uniformly in a ball mill to obtain slurry A.

[0064] 65 g of kaolin and 30 g of aluminum sol were added to 100 g of deoxygenated ionized water, and the mixture was stirred evenly. Slurry A was then added and mixed and beaten to obtain slurry B.

[0065] 2 g of copper nitrate was added to slurry B and stirred to obtain slurry C.

[0066] 18 g of ammonium dihydrogen phosphate was added to slurry C and stirred to obtain slurry D.

[0067] 20 g of fructose was added to slurry D and stirred to obtain slurry E.

[0068] The slurry E is ball-milled using a ball mill, and the ball-milled slurry is formed using a high-temperature spray centrifugal device to obtain microsphere particles.

[0069] The microsphere catalyst was calcined in air at 540°C for 4 h, and the calcined catalyst was evaluated using a riser.

[0070] Example 4

[0071] C molecular sieve was added to 100 g of deoxygenated ionized water, and the mixture was milled and mixed uniformly in a ball mill to obtain slurry A.

[0072] 65 g of kaolin and 30 g of aluminum sol were added to 100 g of deoxygenated ionized water, and the mixture was stirred evenly. Slurry A was then added and mixed and beaten to obtain slurry B.

[0073] 2 g of copper nitrate was added to slurry B and stirred to obtain slurry C.

[0074] 18 g of ammonium dihydrogen phosphate was added to slurry C and stirred to obtain slurry D.

[0075] The slurry D is ball-milled using a ball mill, and the ball-milled slurry is formed using a high-temperature spray centrifugal device to obtain microsphere particles.

[0076] The microsphere catalyst was calcined in air at 540°C for 4 h, and the calcined catalyst was evaluated using a riser.

[0077] Example 5

[0078] 35 g of ZSM-11 molecular sieve was added to 100 g of deoxygenated ionized water, and the mixture was milled and mixed uniformly in a ball mill to obtain slurry A.

[0079] 65 g of kaolin and 30 g of aluminum sol were added to 100 g of deoxygenated ionized water, and the mixture was stirred evenly. Slurry A was then added and mixed and beaten to obtain slurry B.

[0080] 2 g of zirconium nitrate was added to slurry B and stirred to obtain slurry C.

[0081] 16 g of ammonium dihydrogen phosphate was added to slurry C, and the mixture was stirred evenly to obtain slurry D.

[0082] 20 g of sucrose was added to slurry D and stirred to obtain slurry E.

[0083] The slurry E is ball-milled using a ball mill, and the ball-milled slurry is formed using a high-temperature spray centrifugal device to obtain microsphere particles.

[0084] The microsphere catalyst was calcined in air at 540°C for 4 h, and the calcined catalyst was evaluated using a riser.

[0085] Comparative Example 1

[0086] 30 g of Y-type molecular sieve was added to 100 g of deoxygenated ionized water, and the mixture was milled and mixed uniformly in a ball mill to obtain slurry A.

[0087] 65 g of kaolin and 30 g of aluminum sol were added to 100 g of deoxygenated ionized water, and the mixture was stirred evenly. Slurry A was then added and mixed and beaten to obtain slurry B.

[0088] 2 g of copper nitrate was added to slurry B and stirred to obtain slurry C.

[0089] 18 g of ammonium dihydrogen phosphate was added to slurry C and stirred to obtain slurry D.

[0090] The slurry D is ball-milled using a ball mill, and the ball-milled slurry is formed using a high-temperature spray centrifugal device to obtain microsphere particles.

[0091] The microsphere catalyst was calcined in air at 540°C for 4 h, and the calcined catalyst was evaluated using a riser.

[0092] Comparative Example 2

[0093] 30 g of ZSM-5 molecular sieve was added to 100 g of deoxygenated ionized water, and the mixture was milled and mixed uniformly in a ball mill to obtain slurry A.

[0094] 65 g of kaolin and 30 g of aluminum sol were added to 100 g of deoxygenated ionized water, and the mixture was stirred evenly. Slurry A was then added and mixed and beaten to obtain slurry B.

[0095] 2 g of zirconium nitrate was added to slurry B and stirred to obtain slurry C.

[0096] 16 g of ammonium dihydrogen phosphate was added to slurry C, and the mixture was stirred evenly to obtain slurry D.

[0097] 15 g of glucose was added to slurry D and stirred to obtain slurry E.

[0098] The slurry E is ball-milled using a ball mill, and the ball-milled slurry is formed using a high-temperature spray centrifugal device to obtain microsphere particles.

[0099] The microspheres catalyst was calcined in air at 540°C for 4h, and the calcined catalyst was evaluated in a riser.

[0100] The pilot riser evaluation conditions were as follows:

[0101] Table 1. Pilot riser evaluation conditions

[0102]

[0103] Table 2. Diesel feed properties

[0104]

[0105] Table 3. Product distribution

[0106]

[0107] The current evaluation results show that the diesel cracking catalyst prepared by modifying the molecular sieve by the method of Example 2 has high liquefied gas and propylene yield, and has the advantages of high reaction activity and high propylene yield.

[0108] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for preparing a catalyst for catalytic cracking of diesel to produce light olefins, comprising the following steps: A) After mixing ZSM-11 molecular sieve and water by ball milling, kaolin, aluminum sol, metal precursor and phosphorus precursor are added to obtain mixed slurry A; B) mixing the mixed slurry with the soft template to obtain mixed slurry B; The soft template includes one or more of sucrose, glucose and fructose; C) ball-milling the mixed slurry B and spray-granulating the mixed slurry B to obtain microsphere particles; D) calcining the microsphere particles to obtain a catalyst for catalytic cracking of diesel to produce light olefins.

2. The preparation method according to claim 1, characterized in that The ZSM-11 molecular sieve has straight pores with a pore diameter of 0.5-0.6 nm.

3. The preparation method according to claim 1, characterized in that The metal in the metal precursor includes one or more of lanthanum, cerium, zinc, iron, magnesium, manganese, zirconium, copper and silver.

4. The preparation method according to claim 1, characterized in that The phosphorus precursor includes one or more of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate and trimethyl phosphate.

5. The preparation method according to claim 1, characterized in that The mass ratio of ZSM-11 molecular sieve, aluminum sol, kaolin, phosphorus precursor and metal precursor is (10~50): (10~50): (30~70): (5~20): (0.5~5).

6. The preparation method according to claim 1, characterized in that The calcination temperature is 450° C. to 550° C., and the calcination time is 3 to 6 hours.

7. A catalyst for catalytic cracking of diesel to produce light olefins, prepared by the preparation method according to any one of claims 1 to 6.

8. The catalyst for catalytic cracking of diesel to produce light olefins according to claim 7, characterized in that: The catalyst for catalytic cracking of diesel to produce light olefins has a microporous structure, a mesoporous structure and a macroporous structure, an average pore diameter of the catalyst is 6-10 nm, and a pore volume of 0.3-0.4 cc / g.

9. Use of the catalyst for preparing light olefins by catalytic cracking of diesel as claimed in claim 7 or 8 in preparing light olefins and liquefied gas by catalytic cracking of diesel.

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