Disclosure of Invention
According to one aspect of the application, a method for converting a raw material containing naphtha into low-carbon olefins and aromatic hydrocarbons is provided, and the method solves the technical problems of reducing the influence of thermal cracking reaction in the naphtha catalytic cracking technology and reducing the yield of methane in the product.
In order to achieve the purpose, the technical scheme adopted by the application is as follows: a method for converting raw materials containing naphtha into low-carbon olefin and aromatic hydrocarbon comprises the steps that the raw materials containing naphtha enter a reaction section of a turbulent fluidized bed reactor through a feed inlet of the turbulent fluidized bed reactor to react with a catalyst, a generated product enters a product gas outlet pipeline, the catalyst descends to enter a stripping section of the turbulent fluidized bed reactor, and enters a regenerator through a to-be-regenerated inclined tube and a lifting tube after being stripped, and enters the reaction section of the turbulent fluidized bed reactor through the stripping section of the regenerator, the regeneration inclined tube and the lifting tube after being regenerated; and the product gas enters a separation system through a product gas outlet pipeline to obtain low-carbon olefin and aromatic hydrocarbon products.
Optionally, the catalyst is a microsphere catalyst containing naphtha catalytic cracking activity, and is suitable for a circulating fluidized bed reactor.
Optionally, the distillation range of the naphtha is between 20 and 200 ℃;
alternatively, the turbulent fluidized bed reactor conditions: the reaction temperature is 580-720 ℃, the reaction pressure is 0.01-0.3 MPa in terms of gauge pressure, the gas phase linear speed is 0.5-3 m/s, and the mass space velocity is 0.5-2 h-1。
Optionally, the catalyst comprises an active molecular sieve component, and the molecular sieve comprises a silicon-aluminum molecular sieve and a silicon-phosphorus-aluminum molecular sieve, and is synthesized by a known synthesis method, such as a hydrothermal synthesis method; the synthesized molecular sieve is loaded with active metal by a known loading method, such as an impregnation method.
Optionally, the microsphere catalyst is formed by mixing a molecular sieve and a binder to prepare slurry, and spray drying and forming; the content of the molecular sieve in the microspherical catalyst is 10-50%, and the diameter and the grain size of the microspherical catalyst are 30-300 microns.
Alternatively, the microspherical catalyst preferably has a diameter in the range of 50 to 150 microns.
The method for converting the raw material containing naphtha into the low-carbon olefin and the aromatic hydrocarbon is characterized by comprising the following steps of:
a) introducing a raw material containing naphtha into a turbulent fluidized bed reactor, and contacting the raw material with a catalyst at a reaction section of the turbulent fluidized bed reactor to obtain a product gas and a catalyst to be regenerated; the product gas is output from the top of the turbulent fluidized bed reactor and is separated to obtain low-carbon olefin and aromatic hydrocarbon;
b) the catalyst to be regenerated flows downwards to pass through a stripping section of the turbulent fluidized bed reactor and enters a regenerator to obtain a regenerated catalyst;
c) the regenerated catalyst is returned to the turbulent fluidized bed reactor.
Optionally, the lower olefins include ethylene, propylene, butylene.
Optionally, the aromatic hydrocarbon comprises benzene, toluene, xylene.
Optionally, the mass yield of methane in the product gas is as low as 5%.
Optionally, methanol is not included in the naphtha-containing feedstock.
Alternatively, the reaction conditions of the turbulent fluidized bed reactor are: the reaction temperature is 580-720 ℃, the reaction pressure is 0.01-0.3 MPa in terms of gauge pressure, the gas phase linear velocity is 0.5-3 m/s, and the mass space velocity of naphtha is 0.5-2 h-1。
Optionally, the upper limit of the reaction temperature is selected from 590 ℃, 600 ℃, 610 ℃, 620 ℃, 630 ℃, 640 ℃, 650 ℃, 660 ℃, 670 ℃, 680 ℃, 690 ℃, 700 ℃, 710 ℃ or 720 ℃; the lower limit is selected from 580 deg.C, 590 deg.C, 600 deg.C, 610 deg.C, 620 deg.C, 630 deg.C, 640 deg.C, 650 deg.C, 660 deg.C, 670 deg.C, 680 deg.C, 690 deg.C, 700 deg.C or 710 deg.C.
Alternatively, the upper limit of the reaction pressure in gauge pressure is selected from 0.02MPa, 0.05MPa, 0.08MPa, 0.1MPa, 0.15MPa, 0.2MPa, 0.25MPa, or 0.3 MPa; the lower limit is selected from 0.01MPa, 0.02MPa, 0.05MPa, 0.08MPa, 0.1MPa, 0.15MPa, 0.2MPa or 0.25 MPa.
Optionally, the upper limit of the gas phase linear velocity is selected from 1m/s, 1.5m/s, 2m/s, 2.5m/s, or 3 m/s; the lower limit is selected from 0.5m/s, 1m/s, 1.5m/s, 2m/s or 2.5 m/s.
Alternatively, the upper limit of the mass space velocity of the naphtha is selected from 1h-1、1.5h-1Or 2h-1(ii) a The lower limit is selected from 0.5h-1、1h-1Or 1.5h-1。
Optionally, step a) comprises: and the product gas is output from the top of the turbulent fluidized bed reactor through the expanding section of the turbulent fluidized bed reactor, and low-carbon olefin and aromatic hydrocarbon are obtained through separation.
Optionally, step b) comprises: the catalyst to be regenerated descends through a steam stripping section of the turbulent fluidized bed reactor and enters a regenerator through a to-be-regenerated inclined pipe and a riser to obtain the regenerated catalyst.
Optionally, step c) comprises: the regenerated catalyst enters the turbulent fluidized bed reactor from the expanding section of the turbulent fluidized bed reactor through a regeneration inclined pipe and a riser.
Optionally, the catalyst is a microsphere catalyst containing naphtha catalytic cracking activity; the diameter of the microspherical catalyst is 30-300 mu m.
Optionally, the diameter of the microspherical catalyst is 50-150 μm. Optionally, the catalyst is a microspherical catalyst comprising a molecular sieve.
Optionally, the content of the molecular sieve in the microspherical catalyst is 10-50 wt%.
Optionally, the upper limit of the content of the molecular sieve in the microspherical catalyst is selected from 20%, 30%, 40% or 50%; the upper limit is selected from 10%, 20%, 30% or 40%.
Optionally, the catalyst is a microspherical catalyst containing a ZSM-5 molecular sieve.
Optionally, the forming of the microspheroidal catalyst comprises: and (3) spray drying and forming the slurry containing the molecular sieve and the binder.
Optionally, the distillation range of the naphtha is between 20 and 200 ℃.
As an embodiment, the method comprises the following steps:
raw materials containing naphtha enter a reaction section of the turbulent fluidized bed reactor through a feed inlet of the turbulent fluidized bed reactor to react with a catalyst, and the obtained product gas enters a product gas outlet pipeline and enters a separation system to obtain low-carbon olefin and aromatic hydrocarbon;
the catalyst to be regenerated descends into a steam stripping section of the turbulent fluidized bed reactor, and enters a regenerator through a to-be-regenerated inclined pipe and a riser after steam stripping to obtain a regenerated catalyst; the regenerated catalyst returns to the reaction section of the turbulent fluidized bed reactor through a regenerator stripping section, a regeneration inclined tube and a riser.
Optionally, the yield of the low-carbon olefin in the product gas is 30-37 wt%, the yield of the aromatic hydrocarbon is 26-35 wt%, and the yield of the methane is as low as 3 wt%.
The beneficial effects that this application can produce include:
1) according to the naphtha conversion process provided by the application, in the turbulent bed reactor, the volume content of the catalyst is higher than that of the riser reactor, so that the effect of the catalyst is improved, and the influence of thermal cracking reaction is reduced;
2) according to the naphtha conversion process provided by the application, the yield of low-carbon olefins in the product can reach 37 percent (mass), the yield of aromatic hydrocarbon can reach 35 percent (mass), and the yield of methane can be as low as 3 percent.
3) The present application provides a process for converting a naphtha containing feedstock, the products being lower olefins and aromatics. Feeding raw materials including naphtha into a turbulent fluidized bed reactor, and feeding reaction products into a separation system at an outlet at the top of the turbulent fluidized bed reactor to obtain low-carbon olefin and aromatic hydrocarbon; the catalyst enters the turbulent fluidized bed reactor from the regenerator through the riser, and returns to the regenerator for regeneration after the catalytic cracking is finished. The method reduces the influence of thermal cracking reaction in the catalytic cracking process of naphtha, reduces the yield of methane in the product, and improves the utilization rate of carbon element.
Detailed Description
The present application will be described in detail with reference to examples, but the present application is not limited to these examples.
The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.
In the examples, the catalyst was "microspheres containing catalytic cracking activity of naphtha", said catalyst being prepared according to the method of patent CN 200710118286.3.
The analysis method in the examples of the present application is as follows:
product analysis was performed using agilent gas chromatography.
The conversion, selectivity, in the examples of the present application were calculated as follows:
in the examples of the present application, the olefin yield, the aromatic hydrocarbon yield, and the methane yield were calculated on the basis of mass:
olefin yield ═ product mass flow rate (olefin mass content in product)/(product mass flow rate + coke formation); aromatics yield ═ product mass flow rate)/(product mass flow rate + coke rate in the product; methane yield (mass methane content in product × (product mass flow rate)/(product mass flow rate + coke formation).
FIG. 1 is a device adopted in the method of the present application, raw materials including naphtha enter a reaction section 15 of a turbulent fluidized bed reactor through a feeding hole 4 of the turbulent fluidized bed reactor to react with a catalyst, the generated product enters a product gas outlet pipeline 7, the catalyst descends to enter a stripping section 16 of the turbulent fluidized bed reactor, and after stripping, the catalyst enters a regenerator 9 through a to-be-regenerated inclined pipe 13 and a riser 20 to obtain a regenerated catalyst, and the regenerated catalyst enters the reaction section 15 of the turbulent fluidized bed reactor through a stripping section 19 of the regenerator, a regenerated inclined pipe 12 and the riser 2. The product gas enters a separation system through a product gas outlet pipeline 7 to obtain the carbon olefin and aromatic hydrocarbon products.
Example 1
In the apparatus shown in FIG. 1, the catalyst is a microspherical catalyst containing catalytic cracking activity of naphtha, the weight content of the molecular sieve in the catalyst is 10%, and the particle size range is 50-150 microns. Raw materials (distillation range is 20-200 ℃) comprising naphtha enter a reaction section of the turbulent fluidized bed reactor through a feed inlet of the turbulent fluidized bed reactor to react with a catalyst, a generated product enters a product gas outlet pipeline, the catalyst descends to a steam stripping section of the fluidized bed reactor, and after steam stripping, the catalyst enters a regenerator through a to-be-regenerated inclined tube and a lifting tube to obtain a regenerated catalyst. The regenerated catalyst enters the reaction section of the turbulent fluidized bed reactor through a regenerator stripping section, a regeneration inclined tube and a riser. And the product gas enters a separation system through a product gas outlet pipeline to obtain low-carbon olefin and aromatic hydrocarbon products. The catalyst circulation amount is controlled by a plug valve or a slide valve. The composition of the naphtha is shown in Table 1. Turbulent fluidized bed reactor reaction conditions: the reaction temperature is 690 ℃, the reaction pressure is 0.01MPa in gauge pressure, and the gas-phase linear speed is 0.5 m/s. The catalyst circulation quantity is kept stable, and the mass space velocity of the fluidized bed reactor is 0.5h-1. The product gas is analyzed by on-line chromatography, the olefin quality yield is 36%, the aromatic hydrocarbon yield is 30%, and the methane yield is 4.7%.
TABLE 1 naphtha composition
Composition (wt%)
|
Naphtha (IBP-150 ℃ C.)
|
Naphtha (IBP-180 degree)
|
N-alkanes
|
41
|
35
|
Isoalkanes
|
24
|
29
|
Cycloalkanes
|
15
|
28
|
Aromatic hydrocarbons
|
14
|
7 |
Example 2
The catalyst was microspheres containing naphtha catalytic cracking activity, with a molecular sieve content of 30% by weight and a particle size range of 50-150 microns, according to the conditions and procedures described in example 1. Turbulent fluidized bed reactor reaction conditions: the reaction temperature is 650 ℃, the reaction pressure is 0.1MPa in gauge pressure, and the gas-phase linear speed is 1 m/s. The mass space velocity of the fluidized bed reactor is 1h-1. The product gas is analyzed by on-line chromatography, the olefin quality yield is 33%, the aromatic hydrocarbon yield is 28%, and the methane yield is 4%.
Example 3
According toThe conditions and procedures described in example 1, the catalyst was microspheres containing naphtha catalytic cracking activity, the molecular sieve content of the catalyst was 50%, and the particle size range was 50-150 microns. Turbulent fluidized bed reactor reaction conditions: the reaction temperature is 580 ℃, the reaction pressure is 0.2MPa in gauge pressure, and the gas-phase linear speed is 2 m/s. The mass space velocity of the fluidized bed reactor is 1.5h-1. The product gas is analyzed by on-line chromatography, the olefin quality yield is 30%, the aromatic hydrocarbon yield is 26%, and the methane yield is 3%.
Example 4
The catalyst was microspheres containing naphtha catalytic cracking activity according to the conditions and procedures described in example 1, with a molecular sieve weight content of 50% and a particle size range of 50-150 microns. Turbulent fluidized bed reactor reaction conditions: the reaction temperature is 720 ℃, the reaction pressure is 0.3MPa in gauge pressure, and the gas-phase linear speed is 3 m/s. The mass space velocity of the fluidized bed reactor is 2h-1. The product gas is analyzed by on-line chromatography, the olefin quality yield is 37%, the aromatic hydrocarbon yield is 35%, and the methane yield is 5%.
Example 5
The catalyst was microspheres containing naphtha catalytic cracking activity, with a molecular sieve content of 30% by weight and a particle size range of 50-150 microns, according to the conditions and procedures described in example 1. Turbulent fluidized bed reactor reaction conditions: the reaction temperature was 690 ℃, the reaction pressure was 0.01MPa in terms of gauge pressure, and the gas-phase linear velocity was 2 m/s. The product gas is analyzed by on-line chromatography, the olefin quality yield is 37%, the aromatic hydrocarbon yield is 28%, and the methane yield is 4.2%.
Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.