CN115895709B

CN115895709B - Method for preparing propylene and low-olefin gasoline

Info

Publication number: CN115895709B
Application number: CN202111165855.6A
Authority: CN
Inventors: 李福超; 魏晓丽; 袁起民
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2024-05-17
Anticipated expiration: 2041-09-30
Also published as: CN115895709A

Abstract

The present disclosure relates to a process for producing propylene and low olefin gasoline, the process comprising: the hydrocarbon oil raw material is contacted with a catalytic cracking catalyst in a first reactor to carry out catalytic cracking reaction, so as to obtain a spent catalyst and a reaction product; the reaction product is subjected to first separation to obtain C4 fraction, light gasoline and heavy gasoline; introducing the C4 fraction and the light gasoline into a second reactor to contact with a superposition catalyst for catalytic superposition reaction, and separating the obtained superposition product to obtain light superposition oil and superposition oil; returning at least a portion of the overlapping synthetic oil to the first reactor; and mixing the light laminated oil with the heavy gasoline after optional hydrotreatment to obtain the product gasoline. By adopting the method disclosed by the disclosure, the olefin content of the catalytic cracking gasoline can be reduced, the octane number and the gasoline yield of the gasoline can be improved, and meanwhile, the grading and efficient utilization of the laminated oil can be realized.

Description

Method for preparing propylene and low-olefin gasoline

Technical Field

The present disclosure relates to the petrochemical field, and in particular, to a method for producing propylene and low olefin content gasoline.

Background

In recent years, environmental pollution caused by automobile exhaust emission is increasingly serious, so that the requirements on the automobile gasoline are also more stringent. The current automotive gasoline standard GB17930-2016 provides that the upper limit values of the volume fractions of the olefins in the VIA stage and the VIB stage of the automotive gasoline are 18% and 15%, respectively. Currently, the mass fraction of the catalytic cracking gasoline in the gasoline pool in China is about 60% -70%. Catalytically cracked gasolines have a high olefin content, typically above 30% by volume. Olefins are the main contributors to the octane number of catalytically cracked gasoline, especially small molecular olefins such as C5 and C6. How to increase the octane number of gasoline while reducing the olefin content is a challenge for catalytic cracking processes.

CN1069054a discloses a catalytic cracking process for processing light hydrocarbons and heavy hydrocarbons respectively using two risers. In the first riser reactor, the light hydrocarbon reacts with the thermal catalyst under the conditions of 600-700 ℃, 10-40 weight percent of catalyst oil, 2-20 seconds of residence time and 0.1-0.4 weight percent of catalyst carbon content, so as to achieve the purposes of increasing the yield of olefin and increasing the octane number of gasoline; the catalyst then enters a conventional riser to participate in the catalytic cracking reaction of the heavy hydrocarbons. This process has limited ability to increase octane number and is detrimental to reducing the olefin content of gasoline.

CN102952577a discloses a catalytic conversion method for improving propylene yield, high-quality catalytic cracking raw oil and thermal regenerated catalyst are contacted and reacted in a first reaction zone of a reactor, the produced oil gas and catalyst containing carbon are subjected to selective hydrogen transfer reaction and isomerization reaction in a second reaction zone, and the separated C4 fraction and/or light gasoline fraction are injected into the reactor for further reaction. The method can increase propylene yield by 1.3 percent, and improve product distribution.

CN103571536a discloses a device and method for producing clean gasoline and increasing propylene yield by catalytic cracking and hydrogenation, the crude gasoline is divided into light and heavy fractions by adding a gasoline fractionating tower on the top of the catalytic cracking fractionating tower, and the heavy gasoline enters a hydrogenation unit for refining; one part of the light gasoline enters an absorption stabilization system to obtain stabilized gasoline, and the other part of the light gasoline directly returns to the lower part of the catalytic cracking riser reactor to crack and increase propylene under a harsher reaction condition; and finally, blending the stable light gasoline and the modified heavy gasoline to obtain a clean gasoline product. The method has the advantages of high efficiency modification of gasoline and yield increase of propylene.

The prior art mainly reduces the olefin content of the gasoline by recycling the light gasoline and increases the propylene at the same time, but the method causes great loss of the octane number of the gasoline.

In addition, light gasoline etherification is also an important way to increase the octane number of gasoline. However, the vehicular E10 ethanol gasoline standard GB18351-2017 implemented in 9 of 2017 clearly specifies that "ethanol volume fraction is 10% ± 2%", and oxygenates such as MTBE, etherified light gasoline, etc. will not be added artificially in the gasoline pool.

Disclosure of Invention

The purpose of the present disclosure is to solve the problem of a large loss of gasoline octane number when light gasoline is recycled in the prior art.

To achieve the above object, the present disclosure provides a process for producing propylene and low olefin content gasoline, the process comprising: the hydrocarbon oil raw material is contacted with a catalytic cracking catalyst in a first reactor to carry out catalytic cracking reaction, so as to obtain a spent catalyst and a reaction product; the reaction product is subjected to first separation to obtain C4 fraction, light gasoline and heavy gasoline; introducing the C4 fraction and the light gasoline into a second reactor to contact with a superposition catalyst for catalytic superposition reaction, and separating the obtained superposition product to obtain light superposition oil and superposition oil; returning at least a portion of the overlapping synthetic oil to the first reactor; and mixing the light laminated oil with the heavy gasoline after optional hydrotreatment to obtain the product gasoline.

Optionally, the conditions of the catalytic cracking reaction include: the reaction temperature is 450-580 ℃, the oil-gas residence time is 0.5-5 seconds, the reaction pressure is 0.1-1MPa, and the catalyst-oil weight ratio is 4-50; the first reactor is selected from one or a combination of more than two of a riser reactor, a fluidized bed reactor, an up-flow conveyor line and a down-flow conveyor line, and the combination comprises series connection and/or parallel connection.

Optionally, the first reactor is a riser reactor; preferably, the riser reactor is an equal diameter riser reactor or a variable diameter riser reactor; according to the flow direction of the catalyst, the catalytic cracking catalyst is contacted with the heavy laminated oil first and then with the hydrocarbon oil raw material.

Optionally, the catalytic cracking catalyst comprises natural minerals, oxides, and zeolites; the content of the natural mineral substances is 15-65 wt%, the content of the oxide is 10-30 wt% and the content of the zeolite is 25-75 wt% based on the total weight of the catalytic cracking catalyst; wherein the natural ore is selected from one or more of kaolin, montmorillonite, diatomite, attapulgite, sepiolite, halloysite, hydrotalcite, bentonite and rectorite; the oxide is an inorganic oxide, preferably one or more of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide and amorphous silicon aluminum; the zeolite is one or more selected from Y zeolite, ZSM-5 zeolite and Beta zeolite.

Optionally, the method further comprises: injecting a pre-lifting medium at the bottom of the first reactor; the pre-lifting medium is selected from one or more of steam, dry gas and nitrogen, and the weight ratio of the pre-lifting medium to the hydrocarbon oil raw material is 0.01-2, preferably 0.05-1;

Optionally, the process further comprises preheating the hydrocarbon oil feedstock to 180-400 ℃ prior to entering the first reactor.

Alternatively, the cutting temperature of the light gasoline and the heavy gasoline is 50-80 ℃, preferably 60-70 ℃.

Optionally, the reaction conditions of the catalytic folding reaction include: the reaction temperature is 50-200 ℃, preferably 60-160 ℃; the reaction pressure is 0.1-5MPa, preferably 0.5-3MPa; the liquid volume space velocity is 0.5-10h ^-1, preferably 0.8-5h ^-1; the second reactor is selected from one of a fixed bed reactor, a stirred tank reactor and a tower reactor.

Optionally, the superposition catalyst is selected from one or more of solid phosphoric acid, ion exchange resin and zeolite molecular sieve, preferably ion exchange resin.

Optionally, the cutting temperature of the light laminating oil and the laminating oil is 110-150 ℃, preferably 120-130 ℃; the total content of trimethylpentene and trimethylhexene in the light folding oil is more than 80% by volume, preferably more than 85% by volume; the content of C12 and higher olefins in the above-mentioned overlapping oil is 70% by volume or more, preferably 75% by volume or more.

Optionally, the hydrotreating conditions include: the reaction temperature is 50-180 ℃, the reaction pressure is 1-3MPa, and the volume airspeed is 0.2-10h ^-1; the hydrogenation catalyst is selected from one or more of supported cobalt molybdenum catalysts and/or supported nickel-based catalysts, preferably supported nickel-based catalysts.

Optionally, the method further comprises: and after introducing the spent catalyst into a regenerator for regeneration, returning the obtained regenerated catalyst to the first reactor.

Optionally, the hydrocarbon oil raw material is one or more selected from vacuum gas oil, vacuum residue oil, normal pressure gas oil, normal pressure residue oil, coker gas oil, deasphalted oil, hydrofined oil, hydrocracking tail oil, crude oil, coal liquefied oil, shale oil and oil sand oil.

Through the technical scheme, the C4 fraction obtained by the catalytic cracking reaction and the light gasoline fraction are subjected to superposition treatment by adopting the method disclosed by the disclosure, so that the olefin content of the catalytic cracking gasoline can be reduced, the octane number and the gasoline yield of the gasoline are improved, and a gasoline product with a high octane number is obtained. In addition, the laminated oil is fractionated into a light fraction and a heavy fraction, so that the graded and efficient utilization of the laminated oil can be realized.

Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate the disclosure and together with the description serve to explain, but do not limit the disclosure. In the drawings:

FIG. 1 is a schematic flow diagram of one embodiment of the present disclosure for producing propylene and low olefin gasoline.

Description of the reference numerals

1. A riser reactor; 2. a regenerator; 3. a separation device; 4. a superposition reactor; 5. a fractionating tower; 6. a hydrotreater; 7. pre-lifting medium in a riser reactor; 8. heavy laminating oil; 9. a hydrocarbon oil feedstock; 10. a cyclone separator; 11. a stripping section; 12. a catalyst to be regenerated; 13. regenerating the catalyst; 14. reacting oil gas; 15. a C4 fraction; 16. light gasoline; 17. folding the product; 18. light laminating oil; 19. light laminated oil after hydrotreatment; 20. heavy gasoline.

Detailed Description

Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.

The present disclosure provides a process for producing propylene and low olefin gasoline comprising: the hydrocarbon oil raw material is contacted with a catalytic cracking catalyst in a first reactor to carry out catalytic cracking reaction, so as to obtain a spent catalyst and a reaction product; the reaction product is subjected to first separation to obtain C4 fraction, light gasoline and heavy gasoline; introducing the C4 fraction and the light gasoline into a second reactor to contact with a superposition catalyst for catalytic superposition reaction, and separating the obtained superposition product to obtain light superposition oil and superposition oil; returning at least a portion of the overlapping synthetic oil to the first reactor; and mixing the light laminated oil with the heavy gasoline after optional hydrotreatment to obtain the product gasoline.

Through the technical scheme, the method disclosed by the disclosure is adopted to carry out superposition treatment on the C4 fraction and the light gasoline, so that the olefin content of the catalytic cracking gasoline can be reduced, and the octane number and the gasoline yield of the gasoline are improved. The catalytically cracked light gasoline is rich in C5 and C6 olefins, and is a key component for increasing propylene and increasing the octane number of gasoline. Compared to small molecular olefins, polymethyl substituted isoparaffins, such as 2, 4-trimethyl-1-pentene and 2, 4-trimethyl-2-pentene, generally have higher octane numbers. The inventor of the invention finds in the research process that adding small molecular olefins, such as C5 olefins, in the process of overlapping C4 olefins is beneficial to improving the selectivity of trimethylpentene and trimethylhexene in the overlapped product, thereby improving the octane number of gasoline; the light composite oil mainly contains trimethylpentene and trimethylhexene, can be used as a blending component of high-octane gasoline, and the heavy composite oil mainly contains C12 and higher olefins, thus being suitable for cracking and increasing the yield of gasoline and propylene. The method disclosed by the invention is used for fractionating the laminated oil into the light fraction and the heavy fraction, so that the graded high-efficiency utilization of the laminated oil can be realized.

In one embodiment, the method of the present disclosure may be applicable to treatment of various hydrocarbon oil raw materials, and has good treatment effect, for example, the hydrocarbon oil raw materials may be selected from one or more of vacuum gas oil, vacuum residue, atmospheric gas oil, atmospheric residue, coker gas oil, deasphalted oil, hydrofined oil, hydrocracked tail oil, crude oil, coal liquefied oil, shale oil and oil sand oil, wherein the treatment effect on vacuum gas oil, atmospheric residue and hydrocracked tail oil is better.

In one embodiment, the conditions of the catalytic cracking reaction include: the reaction temperature is 450-580 ℃, preferably 490-540 ℃; the residence time of the oil gas is 0.5 to 5 seconds, preferably 1 to 5 seconds; the reaction pressure is 0.1-1MPa, preferably 0.1-0.3MPa; the weight ratio of the agent to the oil is 4-50, preferably 5-20.

In this embodiment, the cracking effect of the hydrocarbon oil feedstock is better under the above-described catalytic cracking reaction conditions. In order to further enhance the effect of the cracking reaction, the conditions of the catalytic cracking reaction are optimized.

In one embodiment, the first reactor is selected from one or a combination of two or more of a riser reactor, a fluidized bed reactor, an ascending transfer line and a descending transfer line, the combination comprising series and/or parallel.

According to a preferred embodiment of the invention, the first reactor is a riser reactor; preferably, the riser reactor is an equal diameter riser reactor or a variable diameter riser reactor.

According to one embodiment of the invention, the first reactor comprises a plurality of reaction sites, and part and/or all of the heavy laminating oil can be introduced into the first reactor at one feed site, or the heavy laminating oil can be introduced into the reactor at least two different feed sites in the same or different proportions.

Further in accordance with a preferred embodiment of the present invention, the feed location of the overlapping oil is located in the lower portion of the first reactor.

In the embodiment where the first reactor is a riser reactor, it is further preferred that the catalytic cracking catalyst is contacted with the heavy oil in a first step and then with the hydrocarbon oil feedstock in a second step according to a flow direction of the catalyst, so as to increase a degree of matching between an activity of the catalytic cracking catalyst and properties of the heavy oil and the hydrocarbon oil feedstock, thereby further improving product distribution and avoiding side reactions.

In this embodiment, when the reactor is a riser reactor, the reaction temperature refers to the outlet temperature of the riser reactor or a certain reaction zone of the riser reactor; the reaction pressure refers to gauge pressure.

In one embodiment, the catalytic cracking catalyst comprises natural minerals, oxides, and zeolites; the content of the natural mineral substances is 15-65 wt%, the content of the oxide is 10-30 wt% and the content of the zeolite is 25-75 wt% based on the total weight of the catalytic cracking catalyst; wherein the natural ore is selected from one or more of kaolin, montmorillonite, diatomite, attapulgite, sepiolite, halloysite, hydrotalcite, bentonite and rectorite; the oxide is an inorganic oxide, preferably one or more of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide and amorphous silicon aluminum; the zeolite is one or more selected from Y zeolite, ZSM-5 zeolite and Beta zeolite.

In the above embodiment, the use of the above-described preferred catalytic cracking catalyst can further enhance the activity of the catalytic cracking catalyst and improve the product distribution.

In one embodiment, the process of the present disclosure further comprises the step of regenerating the spent catalyst resulting from the reaction, the catalyst regeneration process may be carried out according to methods conventional in the art, such as: introducing a spent catalyst into a regenerator, introducing oxygen-containing gas (such as air) from the bottom of the regenerator, enabling the spent catalyst to contact with oxygen for burning regeneration, performing gas-solid separation on generated flue gas through a cyclone separator of the regenerator, and enabling the flue gas to enter a subsequent energy recovery system, wherein the regenerated catalyst returns to the first reactor for continuous use. The regeneration conditions of the spent catalyst may be: the regeneration temperature is 600-750deg.C, preferably 640-720deg.C; the apparent linear velocity of the gas is 0.2 to 3 m/s, preferably 0.4 to 2.5 m/s; the average residence time of the spent catalyst is from 0.5 to 3 minutes, preferably from 0.6 to 2.6 minutes.

In one embodiment, the method further comprises: injecting a pre-lifting medium at the bottom of the first reactor; the pre-lifting medium is selected from one or more of steam, dry gas and nitrogen, and the weight ratio of the pre-lifting medium to the hydrocarbon oil raw material is 0.01-2, preferably 0.05-1.

In one embodiment, the process further comprises preheating the hydrocarbon oil feedstock to 180-400 ℃ prior to entering the first reactor.

In this embodiment, the hydrocarbon oil raw material is preheated and then fed into the first reactor, and when fed into the first reactor, the temperature can be quickly raised to the reaction temperature, and the hydrocarbon oil raw material can be sufficiently reacted in the first reactor, so that the generation of unreacted hydrocarbon oil raw material or reaction by-products can be reduced.

In one embodiment, the first separation is performed in a fractionation column; the cutting temperature of the light gasoline and the heavy gasoline is 50-80 ℃, preferably 60-70 ℃. Wherein, when the final distillation point of the light gasoline is lower than 70 ℃, the volume content of C5 olefin in the light gasoline is more than 80 percent. The preferred cutting temperature helps to further increase the selectivity of trimethylpentene in the resulting light gasoline fraction and the folded product of the catalytic folding reaction of the C4 fraction, to increase the octane number of the gasoline, and to produce a high carbon number folded product which is prone to cracking to propylene.

In one embodiment, the reaction conditions of the catalytic folding reaction include: the reaction temperature is 50-200 ℃, preferably 60-160 ℃; the reaction pressure is 0.1-5MPa, preferably 0.5-3MPa; the liquid volume space velocity is 0.5-10h ^-1, preferably 0.8-5h ^-1; the second reactor is selected from one of a fixed bed reactor, a stirred tank reactor and a tower reactor, preferably a fixed bed reactor.

Alternatively, the second reactor may be operated batchwise or continuously, preferably continuously.

In one embodiment, the folding catalyst is selected from one or more of solid phosphoric acid, ion exchange resin and zeolite molecular sieve, preferably ion exchange resin. In the above embodiment, the ion exchange resin is obtained by introducing sulfonic acid groups after crosslinking styrene with divinylbenzene. The resin can be synthesized according to the prior method, and can also be purchased from the market, such as Amberlyst15, amberlyst35 strong acid cation exchange resin and one or more of Nafion perfluorinated sulfonic acid novel resin catalysts.

In one embodiment, the second separation is carried out in a fractionation column, the cutting temperature of the light bottoms oil and the overlapping bottoms oil being in the range 110 to 150 ℃, preferably 120 to 130 ℃.

In one embodiment, the total content of trimethylpentene and trimethylhexene in the light-ends oil is 80% by volume or more, preferably 85% by volume or more; the content of C12 and higher olefins in the above-mentioned overlapping oil is 70% by volume or more, preferably 75% by volume or more.

According to the present disclosure, the light blending oil may or may not be hydrotreated prior to mixing with the heavy gasoline. The light blending oil may not be hydrotreated on the premise of meeting the olefin content requirements of the blended gasoline. In this embodiment, the product oil made using the present disclosure has an olefin content of 20% by volume or less. In order to reduce the olefin content of gasoline, the light blending oil is preferably hydrotreated under mild conditions to convert the isoparaffins to isoparaffins.

In one embodiment, the hydrotreating is performed in a fixed bed reactor; the hydrotreating conditions include: the reaction temperature is 50-180 ℃, preferably 60-120 ℃, the reaction pressure is 1-3MPa, preferably 1.2-2.5MPa, the volume space velocity is 0.2-10h ^-1, preferably 0.5-8h ^-1; the hydrogenation catalyst is selected from one or more of a supported cobalt-molybdenum catalyst and a supported nickel-based catalyst, preferably a supported nickel-based catalyst, and has better olefin hydrogenation saturation activity, good thermal stability and high mechanical strength.

The following examples further illustrate the invention but are not intended to limit it.

The weight ratio of the atmospheric residuum to the hydrocracked tail oil in the heavy oil feedstock used in examples and comparative examples was 3, and the properties are shown in Table 1.

The catalytic cracking catalyst used was a cracking catalyst with the trade designation CDOS, manufactured by Qilu division, china petrochemical catalyst, and the properties are shown in Table 2.

The RON octane number of the gasoline is determined according to the method of GB/T5487.

TABLE 1 Properties of heavy oil feedstock

TABLE 2 Properties of catalytic cracking catalysts

Example 1

The polymerization catalyst is Amberlyst35 resin (commercially available), and the light polymerization oil hydrotreating catalyst adopts a hydrotreating catalyst with the trade name of RS-40 produced by Chang Ling division of China petrochemical catalyst Co.

According to the illustration of fig. 1, a pre-lifting medium 7 (weight ratio of hydrocarbon oil raw material is 0.06) enters from the bottom of a lifting tube reactor 1 through a pipeline, a high-temperature regenerated catalyst 13 from a regenerator moves upwards under the action of the pre-lifting medium, atomized overlapped oil 8 is introduced into the lifting tube reactor 1, contacts and reacts with the high-temperature regenerated catalyst 13, preheated hydrocarbon oil raw material (heavy oil raw material) 9 and an atomized medium (water vapor) are injected into the lifting tube reactor 1 together, and catalytic cracking reaction occurs on a hot catalytic cracking catalyst, wherein the operation conditions are as follows: the reaction temperature is 520 ℃, the reaction pressure is 0.14MPa, the catalyst-to-oil weight ratio is 6, the reaction time is 3s, the generated reaction product and the spent catalyst with carbon enter a cyclone separator 10 to realize the separation of the spent catalyst 12 and the reaction oil gas 14, the spent catalyst is stripped by a stripping section 11, and the stripped spent catalyst 12 enters a regenerator 2 through a conveying inclined tube to be burnt and regenerated and then returns to a riser reactor 1. The reaction oil gas 14 enters a subsequent separation device 3, after separation operations such as distillation, absorption and the like, C4 fraction 15 and light gasoline 16 with the final distillation point not higher than 70 ℃ are introduced into a superposition reactor 4, and catalytic superposition reaction is carried out under the action of Amberlyst35 resin catalyst, wherein the operation conditions are as follows: the reaction temperature is 80 ℃, the reaction pressure is 1.0MPa, the liquid volume space velocity is 2h ^-1, and a fixed bed reactor is adopted. The superposition product 17 is introduced into a fractionating tower 5, light superposition oil 18 with the final distillation point not higher than 120 ℃ is distilled out from the top of the fractionating tower and then enters a hydrotreater 6, and the isoolefin is converted into isoparaffin under the action of hydrogen and an RS-40 hydrogenation catalyst, wherein the operation conditions of the hydrotreatment are as follows: the reaction temperature is 70 ℃, the reaction pressure is 1.6MPa, the volume space velocity is 2h ^-1, and a fixed bed reactor is adopted. The hydrotreated light folded oil 19 is mixed with the heavy gasoline 20 from the separation device 3 to obtain high-octane gasoline. The heavy bottoms 8 are returned to the riser reactor 1. The operating conditions and product distribution are listed in Table 3.

Example 2

The process and apparatus for producing propylene and low olefin gasoline are the same as in example 1, except that the light blending oil is not hydrotreated and is directly blended with the heavy gasoline. The operating conditions and product distribution are listed in Table 3.

Example 3

The process and apparatus for producing propylene and low olefin gasoline are the same as in example 1, except that the polymerization conditions are: the reaction temperature is 80 ℃, the reaction pressure is 1.2MPa, and the liquid volume space velocity is 1.5h ^-1. The operating conditions and product distribution are listed in Table 3.

Example 4

The process and apparatus for producing propylene and low olefin gasoline are the same as in example 1, except that solid phosphoric acid (commercially available) is used as the polymerization catalyst. The operating conditions and product distribution are listed in Table 3.

Comparative example 1

The process and apparatus for producing propylene and low olefin content gasoline are the same as in example 1 except that the C4 cut and light gasoline in this comparative example are not introduced into the polymerization reactor but are withdrawn as products after being mixed with heavy gasoline. The operating conditions and product distribution are listed in Table 3.

Comparative example 2

The method and apparatus for producing propylene and low olefin gasoline are the same as in example 1, except that the light gasoline in this comparative example is not fed into the polymerization reactor, and only the C4 fraction is fed into the polymerization reactor to carry out the polymerization reaction, and the hydrotreated light polymerization oil is mixed with the light gasoline and heavy gasoline from the separation apparatus to obtain gasoline products. The operating conditions and product distribution are listed in Table 3.

TABLE 3 operating conditions and product distribution

As can be seen from Table 3, comparing the data in examples 1-4 with the data in comparative examples 1-2, the method provided by the invention has the advantages that the gasoline yield is increased by 2.1-4.5%, the propylene yield is increased by 0.4-1.9%, the olefin content of the gasoline is reduced by 7.3-17.8%, and the research octane number of the gasoline is increased by 2.1-3.7 units. The method provided by the invention can obviously improve the content of trimethylpentene and trimethylhexene in the light-superposition oil, is beneficial to improving the propylene yield, and can obtain a high-octane gasoline component with low olefin content, and the gasoline yield is increased. It is evident from a comparison of the data in example 1 and example 2 that the hydrotreating can be carried out to further reduce the olefin content in the product oil. As can be seen from the comparison of the data in the example 1 and the example 4, the composition of the laminated gasoline can be further optimized by adopting the ion exchange resin as the catalyst for the lamination reaction, and the effect of preparing the propylene and the gasoline with low olefin content is better.

The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the embodiments described above, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.

In addition, the specific features described in the foregoing embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present disclosure does not further describe various possible combinations.

Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.

Claims

1. A process for producing propylene and low olefin gasoline comprising:

The hydrocarbon oil raw material is contacted with a catalytic cracking catalyst in a first reactor to carry out catalytic cracking reaction, so as to obtain a spent catalyst and a reaction product; the reaction product is subjected to first separation to obtain C4 fraction, light gasoline and heavy gasoline;

introducing the C4 fraction and the light gasoline into a second reactor to contact with a superposition catalyst for catalytic superposition reaction, and separating the obtained superposition product to obtain light superposition oil and superposition oil;

Returning at least a portion of the overlapping synthetic oil to the first reactor; mixing the light laminated oil with the heavy gasoline after hydrotreatment or without hydrotreatment to obtain product gasoline;

The superposition catalyst is selected from one or more of solid phosphoric acid, ion exchange resin and zeolite molecular sieve;

The total content of trimethylpentene and trimethylhexene in the light folding oil is more than 80 volume percent; the content of C12 and higher olefins in the overlapping oil is more than 70% by volume.

2. The method of claim 1, wherein the conditions of the catalytic cracking reaction comprise: the reaction temperature is 450-580 ℃, the oil-gas residence time is 0.5-5 seconds, the reaction pressure is 0.1-1 MPa, and the catalyst-oil weight ratio is 4-50;

The first reactor is selected from one or a combination of more than two of a riser reactor, a fluidized bed reactor, an up-flow conveyor line and a down-flow conveyor line, and the combination comprises series connection and/or parallel connection.

3. The method of claim 2, wherein the first reactor is a riser reactor;

according to the flow direction of the catalyst, the catalytic cracking catalyst is contacted with the heavy laminated oil first and then with the hydrocarbon oil raw material.

4. A method according to claim 3, wherein the riser reactor is an equal diameter riser reactor or a variable diameter riser reactor.

5. The process according to claim 1 or 2, characterized in that the catalytic cracking catalyst comprises natural minerals, oxides and zeolites; the content of the natural mineral substances is 15-65 wt%, the content of the oxide is 10-30 wt% and the content of the zeolite is 25-75 wt% based on the total weight of the catalytic cracking catalyst;

Wherein the natural mineral is selected from one or more of kaolin, montmorillonite, diatomite, attapulgite, sepiolite, halloysite, hydrotalcite, bentonite and rectorite;

the oxide is an inorganic oxide;

the zeolite is one or more selected from Y zeolite, ZSM-5 zeolite and Beta zeolite.

6. The method of claim 5, wherein the oxide is one or more of silica, alumina, zirconia, titania, and amorphous silica-alumina.

7. The method according to claim 1, characterized in that the method further comprises: injecting a pre-lifting medium at the bottom of the first reactor; the pre-lifting medium is selected from one or more of steam, dry gas and nitrogen, and the weight ratio of the pre-lifting medium to the hydrocarbon oil raw material is 0.01-2.

8. The method of claim 7, wherein the weight ratio of the pre-lift medium to the hydrocarbon oil feedstock is from 0.05 to 1.

9. The process of claim 7 further comprising preheating the hydrocarbon oil feedstock to 180-400 ℃ prior to entering the first reactor.

10. The method of claim 1, wherein the light gasoline and the heavy gasoline have a cut temperature of 50-80 ℃.

11. The method of claim 10, wherein the light gasoline and the heavy gasoline have a cut temperature of 60-70 ℃.

12. The method according to claim 1, wherein the reaction conditions of the catalytic folding reaction comprise: the reaction temperature is 50-200 ℃, the reaction pressure is 0.1-5 MPa, and the liquid volume space velocity is 0.5-10h ^-1;

The second reactor is selected from one of a fixed bed reactor, a stirred tank reactor and a tower reactor.

13. The method according to claim 1, wherein the reaction conditions of the catalytic folding reaction comprise: the reaction temperature is 60-160 ℃, the reaction pressure is 0.5-3 MPa, and the liquid volume space velocity is 0.8-5h ^-1.

14. The method of claim 1, wherein the lamination catalyst is an ion exchange resin.

15. The method of claim 1, wherein the cutting temperature of the light laminating oil and the overlapping laminating oil is 110-150 ℃;

The total content of trimethylpentene and trimethylhexene in the light folding oil is more than 85 volume percent;

the content of C12 and higher olefins in the overlapping oil is more than 75% by volume.

16. The method of claim 15, wherein the cutting temperature of the light laminating oil and the overlapping oil is 120-130 ℃.

17. The method of claim 1, wherein the hydrotreating conditions comprise: the reaction temperature is 50-180 ℃, the reaction pressure is 1-3 MPa, and the volume space velocity is 0.2-10h ^-1;

The hydrogenation catalyst is selected from a supported cobalt molybdenum catalyst and/or a supported nickel-based catalyst.

18. The method of claim 17, wherein the hydrogenation catalyst is a supported nickel-based catalyst.

19. The method according to claim 1, characterized in that the method further comprises: and after introducing the spent catalyst into a regenerator for regeneration, returning the obtained regenerated catalyst to the first reactor.

20. The method of claim 1, wherein the hydrocarbon oil feedstock is selected from one or more of vacuum gas oil, vacuum residuum, atmospheric gas oil, atmospheric residuum, coker gas oil, deasphalted oil, hydrofined oil, hydrocracked tail oil, crude oil, coal liquefied oil, shale oil, and oil sand oil.