CN115895709A

CN115895709A - Method for preparing propylene and gasoline with low olefin content

Info

Publication number: CN115895709A
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: 2023-04-04
Anticipated expiration: 2041-09-30
Also published as: CN115895709B

Abstract

The present disclosure relates to 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; carrying out first separation on the reaction product to obtain a C4 fraction, light gasoline and heavy gasoline; introducing the C4 fraction and the light gasoline into a second reactor to contact with a polymerization catalyst for catalytic polymerization reaction, and performing second separation on the obtained polymerization product to obtain light polymerization oil and overlapped polymerization oil; returning at least a portion of the refolded oil to the first reactor; and mixing the light superimposed oil with the heavy gasoline after optional hydrotreatment to obtain the product gasoline. By adopting the method disclosed by the invention, the olefin content of the catalytic cracking gasoline can be reduced, the octane number of the gasoline and the yield of the gasoline can be improved, and meanwhile, the graded efficient utilization of the superimposed oil can be realized.

Description

Method for preparing propylene and gasoline with low olefin content

Technical Field

The disclosure relates to the field of petrochemical industry, and in particular relates to a method for preparing propylene and low-olefin-content gasoline.

Background

In recent years, the problem of environmental pollution caused by automobile exhaust emission is becoming more serious, and thus the requirement for motor gasoline is becoming more strict. The volume fraction upper limit values of the olefin in VIA stage and VIB stage of the vehicle gasoline are respectively 18 percent and 15 percent according to the current vehicle gasoline standard GB 17930-2016. At present, the mass fraction of the catalytic cracking gasoline in the gasoline pool of China is about 60 to 70 percent. The catalytically cracked gasoline has a high olefin content, typically above 30% by volume. Olefins are the main contributors of 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 of the catalytic cracking process.

CN1069054A discloses a catalytic cracking method for processing light hydrocarbons and heavy hydrocarbons respectively by using two lift pipes. In the first riser reactor, light hydrocarbon reacts with a thermal catalyst under the conditions of 600-700 ℃, catalyst-oil weight ratio of 10-40, residence time of 2-20 seconds and catalyst carbon content of 0.1-0.4 wt% so as to achieve the purposes of increasing the yield of olefin and improving the octane number of gasoline; then the catalyst enters a conventional riser to participate in the catalytic cracking reaction of heavy hydrocarbons. The process has limited ability to increase octane and is not conducive to reducing the olefin content of gasoline.

CN102952577A discloses a catalytic conversion method for improving propylene yield, high-quality catalytic cracking raw oil and a thermal regeneration catalyst are in contact reaction in a first reaction zone of a reactor, generated oil gas and a carbon-containing catalyst are subjected to selective hydrogen transfer reaction and isomerization reaction in a second reaction zone, and separated C4 fraction and/or light gasoline fraction is injected into the reactor for further reaction. The method can improve the yield of the propylene by 1.3 percentage points and improve the product distribution at the same time.

CN103571536A discloses a device and a method for producing clean gasoline and increasing propylene yield by catalytic cracking and hydrogenation, wherein a gasoline fractionating tower is added at the top of a catalytic cracking fractionating tower to divide crude gasoline into light and heavy fractions, and the heavy gasoline enters a hydrogenation unit for refining; one part of the light gasoline enters an absorption stabilizing system to obtain stable gasoline, and the other part of the light gasoline directly returns to the lower part of the catalytic cracking riser reactor to be cracked under harsh reaction conditions to increase the yield of propylene; finally, blending the stable light gasoline and the modified heavy gasoline to obtain a clean gasoline product. The method can efficiently modify gasoline and increase propylene yield.

In the prior art, light gasoline is recycled mainly to reduce the olefin content of the gasoline and increase the propylene yield, but the method causes great loss of the gasoline octane number.

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

Disclosure of Invention

The purpose of this disclosure is to solve the problem that there is a large loss in gasoline octane number when light gasoline is remixed in the prior art.

In order to achieve the above objects, the present disclosure provides a method for preparing propylene and gasoline having a low olefin content, the method 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; carrying out first separation on the reaction product to obtain a C4 fraction, light gasoline and heavy gasoline; introducing the C4 fraction and the light gasoline into a second reactor to contact with a polymerization catalyst for catalytic polymerization reaction, and performing second separation on the obtained polymerization product to obtain light polymerization oil and overlapped polymerization oil; returning at least a portion of the refolding oil to the first reactor; and mixing the light superimposed 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 weight ratio of the solvent to the oil is 4-50; the first reactor is selected from one or more of a riser reactor, a fluidized bed reactor, an ascending conveyor line and a descending 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 reducing riser reactor; according to the flowing direction of the catalyst, the catalytic cracking catalyst is firstly contacted with the heavy superposed oil and then contacted with the hydrocarbon oil raw material.

Optionally, the catalytic cracking catalyst comprises natural minerals, oxides, and zeolites; based on the total weight of the catalytic cracking catalyst, the content of the natural mineral is 15-65 wt%, the content of the oxide is 10-30 wt%, and the content of the zeolite is 25-75 wt%; 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 silica-alumina; the zeolite is selected from one or more of 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 water vapor, 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.

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

Optionally, the reaction conditions of the catalytic polymerization 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 to 5 hours ^-1 (ii) a The second reactor is selected from one of a fixed bed reactor, a stirred tank reactor and a tower reactor.

Optionally, the polymerization 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 heavy laminating oil is 110-150 ℃, preferably 120-130 ℃; the total content of trimethylpentene and trimethylhexene in the light laminating oil is more than 80 volume percent, and preferably more than 85 volume percent; the content of C12 and higher olefins in the heavy overlapping oil is 70 vol% or more, preferably 75 vol% or more.

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

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

Optionally, the hydrocarbon oil feedstock is selected from one or more of vacuum gas oil, vacuum residue, atmospheric gas oil, atmospheric residue, coker gas oil, deasphalted oil, hydrofinished oil, hydrocracked tail oil, crude oil, coal liquefied oil, shale oil and oil sand oil.

By adopting the technical scheme, the method disclosed by the invention is adopted to carry out superposition treatment on the C4 fraction obtained by catalytic cracking reaction and the light gasoline fraction, so that 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 a high-octane number gasoline product can be obtained. In addition, the laminated oil is fractionated into light fraction and heavy fraction, so that the laminated oil can be efficiently utilized in a grading manner.

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

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting 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 content gasoline.

Description of the reference numerals

1. A riser reactor; 2. a regenerator; 3. a separation device; 4. a polymerization reactor; 5. a fractionating column; 6. a hydrotreater; 7. pre-lift media for a riser reactor; 8. overlapping the oil; 9. a hydrocarbon oil feedstock; 10. a cyclone separator; 11. a stripping section; 12. a spent catalyst; 13. regenerating the catalyst; 14. reacting the oil gas; 15. a C4 fraction; 16. light gasoline; 17. superposing the products; 18. light laminating oil; 19. the light superposed oil after hydrotreating; 20. heavy gasoline.

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

The present disclosure provides a process for producing propylene and low olefin content gasoline, the process comprising: contacting a hydrocarbon oil raw material with a catalytic cracking catalyst in a first reactor to carry out catalytic cracking reaction to obtain a spent catalyst and a reaction product; carrying out first separation on the reaction product to obtain a C4 fraction, light gasoline and heavy gasoline; introducing the C4 fraction and the light gasoline into a second reactor to contact with a polymerization catalyst for catalytic polymerization reaction, and performing second separation on the obtained polymerization product to obtain light polymerization oil and overlapped polymerization oil; returning at least a portion of the refolded oil to the first reactor; and mixing the light superimposed oil with the heavy gasoline after optional hydrotreatment to obtain the product gasoline.

By adopting the technical scheme, the method disclosed by the invention 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 can be improved. The catalytic cracking light gasoline is rich in C5 and C6 olefins and is a key component for increasing the yield of propylene and improving the octane number of the gasoline. The polymethylsubstituted isomerates, such as 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, generally have higher octane numbers than the small molecule olefins. The inventor of the invention finds in the research process that the addition of small molecular olefins, such as C5 olefins, in the C4 olefin polymerization process is helpful for improving the selectivity of trimethylpentene and trimethylhexene in the polymerization product, thereby improving the octane number of gasoline; the superimposed oil is fractionated into light and heavy fractions, the light superimposed oil mainly contains trimethylpentene and trimethylhexene and can be used as a blending component of high-octane gasoline, and the heavy superimposed oil mainly contains C12 and higher-carbon-number olefins and is suitable for cracking yield-increasing gasoline and propylene. The method disclosed by the invention can be used for fractionating the laminated oil into the light fraction and the heavy fraction, so that the classified efficient utilization of the laminated oil can be realized.

In one embodiment, the method of the present disclosure can be applied to the treatment of various hydrocarbon oil feedstocks, and the treatment effect is good, for example, the hydrocarbon oil feedstock can be selected from one or more of vacuum gas oil, vacuum residue oil, atmospheric gas oil, atmospheric residue oil, 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 the vacuum gas oil, the atmospheric residue oil and the 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 oil gas residence time is 0.5-5 seconds, preferably 1-5 seconds; the reaction pressure is 0.1-1MPa, preferably 0.1-0.3MPa; the weight ratio of the solvent to the oil is 4-50, preferably 5-20.

In this embodiment, the hydrocarbon oil feedstock has a good cracking effect under the catalytic cracking reaction conditions described above. To further enhance the effectiveness 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 transport line and a descending transport line, the combination comprising series and/or parallel.

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

In one embodiment according to the present invention, the first reactor comprises a plurality of reaction locations, and part and/or all of the refolding oil may be introduced into the first reactor at one feed location, or the refolding oil may be introduced into the reactor at least two different feed locations in the same or different proportions.

Further, according to a preferred embodiment of the present invention, the feeding position of the overlapping oil is located at a 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 contacts the heavy overlapping oil first and then contacts the hydrocarbon oil raw material according to the flowing direction of the catalyst, so as to improve the matching degree of the activity of the catalytic cracking catalyst and the properties of the overlapped oil and the hydrocarbon oil raw material, thereby further improving the 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 is a gauge pressure.

In one embodiment, the catalytic cracking catalyst comprises natural minerals, oxides, and zeolites; based on the total weight of the catalytic cracking catalyst, the content of the natural mineral is 15-65 wt%, the content of the oxide is 10-30 wt%, and the content of the zeolite is 25-75 wt%; 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 silica-alumina; the zeolite is selected from one or more of Y zeolite, ZSM-5 zeolite and Beta zeolite.

In the above embodiment, the activity of the catalytic cracking catalyst can be further enhanced and the product distribution can be improved by using the above preferred catalytic cracking catalyst.

In one embodiment, the method of the present disclosure further comprises a step of regenerating the spent catalyst obtained from the reaction, and the catalyst regeneration method can be performed according to a method conventional in the art, such as: introducing the spent catalyst into a regenerator, introducing oxygen-containing gas (such as air) from the bottom of the regenerator, contacting the spent catalyst with the oxygen, burning and regenerating, carrying out gas-solid separation on the generated flue gas through a cyclone separator of the regenerator, and entering a subsequent energy recovery system, wherein the regenerated catalyst returns to the first reactor for continuous use. The regeneration conditions of the spent catalyst can be as follows: the regeneration temperature is 600-750 ℃, preferably 640-720 ℃; the gas apparent linear velocity is 0.2-3 m/s, preferably 0.4-2.5 m/s; the average residence time of the spent catalyst is 0.5 to 3 minutes, preferably 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 water vapor, 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 the temperature can be rapidly raised to the reaction temperature when the hydrocarbon oil raw material is fed into the first reactor, so that the hydrocarbon oil raw material can be sufficiently reacted in the first reactor, and the production 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 ℃, and 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 is favorable for further improving the selectivity of trimethylpentene in the superposed product of the catalytic superposition reaction of the obtained light gasoline fraction and the C4 fraction, improving the octane number of the gasoline and simultaneously being favorable for generating a high-carbon-number superposed product which is easy to crack into propylene.

In one embodiment, the reaction conditions for the catalytic polymerization reaction include: inverse directionThe 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 to 5h ^-1 (ii) a The second reactor is selected from one of a fixed bed reactor, a stirred tank reactor and a tower reactor, and is preferably a fixed bed reactor.

Alternatively, the second reactor may be operated batchwise or continuously, preferably in a continuous manner.

In one embodiment, the polymerization 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 crosslinking styrene with divinylbenzene and then introducing sulfonic acid groups. The resin can be synthesized according to the existing method, and can also be purchased from the market, such as one or more of Amberlyst15, amberlyst35 strong acid cation exchange resin and Nafion perfluorosulfonic acid novel resin catalyst.

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

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

According to the present disclosure, the light overlay oil may or may not be hydrotreated prior to mixing with the heavy gasoline. The light superposition oil can not be subjected to hydrotreatment on the premise of meeting the requirement of the olefin content 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 syncrude is preferably hydrotreated under mild conditions to convert isoolefins to isoalkanes.

In one embodiment, the hydrotreating is carried out 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, and the volume space velocity is 0.2-10h ^-1 Preferably 0.5 to 8h ^-1 (ii) a The hydrogenation catalyst is selected from one or more of supported cobalt-molybdenum catalysts and supported nickel-based catalysts, preferably supported nickel-based catalysts, 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 the invention thereto.

The heavy oil feedstock used in the examples and comparative examples had a weight ratio of atmospheric residue to hydrocracked tail oil of 3, and the properties are shown in table 1.

The catalytic cracking catalyst was a cracking catalyst of CDOS, a commercial product of China petrochemical catalyst, inc., qilu division, and the properties are shown in Table 2.

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

TABLE 1 Properties of heavy oil feedstocks

TABLE 2 Properties of the catalytic cracking catalysts

Example 1

The polymerization catalyst is Amberlyst35 resin (sold in the market), and the light polymerization oil hydrotreating catalyst adopts a hydrogenation catalyst with the product number of RS-40, which is produced by Changjingtian of China petrochemical catalyst company Limited.

As shown in fig. 1, a pre-lifting medium 7 (the weight ratio of the pre-lifting medium to the hydrocarbon oil feedstock is 0.06) enters from the bottom of a riser reactor 1 through a pipeline, a high-temperature regenerated catalyst 13 from a regenerator moves upward in an accelerated manner under the action of the pre-lifting medium, atomized overlapping oil 8 is introduced into the riser reactor 1 to contact and react with the high-temperature regenerated catalyst 13, a preheated hydrocarbon oil feedstock (heavy oil feedstock) 9 and an atomized medium (steam) are injected into the riser reactor 1 together, and a catalytic cracking reaction occurs on a hot catalytic cracking catalyst under the operating conditions that: the reaction temperature is 520 ℃, the reaction pressure is 0.14MPa, the catalyst-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 pipe to be coked and regenerated and then returns to the riser reactor 1. The reaction oil gas 14 enters a subsequent separation device 3, after separation operations such as distillation, absorption and the like, a C4 fraction 15 and light gasoline 16 with the final distillation point not higher than 70 ℃ are introduced into a polymerization reactor 4, and catalytic polymerization 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, and the liquid volume space velocity is 2h ^-1 A fixed bed reactor is used. Introducing the superimposed product 17 into a fractionating tower 5, distilling light superimposed oil 18 with the final distillation point not higher than 120 ℃ from the top of the fractionating tower, then entering a hydrotreater 6, and converting isoolefins into isoalkanes under the action of hydrogen and an RS-40 hydrogenation catalyst, wherein the operation conditions of hydrotreatment are as follows: the reaction temperature is 70 ℃, the reaction pressure is 1.6MPa, and the volume space velocity is 2h ^-1 A fixed bed reactor is used. The light superimposed oil 19 after hydrotreating is mixed with the heavy gasoline 20 from the separation device 3 to obtain the high-octane gasoline. Heavy overlapping oil 8 is returned to riser reactor 1. The operating conditions and the product distribution are listed in table 3.

Example 2

The process and apparatus for the preparation of propylene and low olefin content gasoline are the same as in example 1 except that the light overlay oil is not hydrotreated and is directly blended with the heavy gasoline. The operating conditions and the product distribution are listed in table 3.

Example 3

The process and apparatus for the preparation of propylene and gasoline with a low olefin content 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 the product distribution are listed in table 3.

Example 4

The process and apparatus for the preparation of propylene and low olefin content gasoline were the same as in example 1 except that solid phosphoric acid (commercially available) was used as the polymerization catalyst. The operating conditions and the product distribution are listed in table 3.

Comparative example 1

The process and apparatus for the preparation of propylene and low olefin gasolines are identical to example 1, except that in this comparative example the C4 cut and the light gasoline are not introduced into the polymerization reactor, but are instead taken off as product after mixing with the heavy gasoline. The operating conditions and the product distribution are listed in table 3.

Comparative example 2

The method and the device for preparing the propylene and the gasoline with low olefin content are the same as the example 1, except that in the comparative example, the light gasoline does not enter the polymerization reactor, only the C4 fraction is introduced into the polymerization reactor for polymerization reaction, and the light polymerization oil after the hydrotreatment is mixed with the light gasoline and the heavy gasoline from the separation device to obtain the gasoline product. The operating conditions and the 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 comparative examples 1-2, it can be seen that using the process of the present invention, gasoline yield is increased by 2.1-4.5 percent, propylene yield is increased by 0.4-1.9 percent, gasoline olefin content is decreased by 7.3-17.8 percent, and gasoline research octane number is increased by 2.1-3.7 units, compared to the comparative examples. The method provided by the invention can obviously improve the content of trimethylpentene and trimethylhexene in the light superimposed oil, is beneficial to improving the yield of propylene, obtains a high-octane gasoline component with low olefin content and increases the yield of gasoline. As can be seen from a comparison of the data in example 1 and example 2, hydrotreating can further reduce the olefin content in the product oil. Comparing the data of the embodiment 1 and the embodiment 4, the ion exchange resin is adopted as the catalyst of the polymerization reaction, the composition of the polymerization gasoline can be further optimized, and the effect of preparing the propylene and the gasoline with low olefin content is better.

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A process for producing propylene and a gasoline having a low olefin content, the process comprising:

contacting a hydrocarbon oil raw material with a catalytic cracking catalyst in a first reactor to carry out catalytic cracking reaction to obtain a spent catalyst and a reaction product; carrying out first separation on the reaction product to obtain a C4 fraction, light gasoline and heavy gasoline;

introducing the C4 fraction and the light gasoline into a second reactor to contact with a polymerization catalyst for catalytic polymerization reaction, and performing second separation on the obtained polymerization product to obtain light polymerization oil and overlapped polymerization oil;

returning at least a portion of the refolded oil to the first reactor; and mixing the light superimposed oil with the heavy gasoline after optional hydrotreatment to obtain the product gasoline.

2. The process according to claim 1, characterized in that 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 0.1-1MPa, and the weight ratio of the solvent to the oil is 4-50;

the first reactor is selected from one or more of a riser reactor, a fluidized bed reactor, an ascending conveyor line and a descending 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; preferably, the riser reactor is an equal-diameter riser reactor or a reducing riser reactor;

according to the flowing direction of the catalyst, the catalytic cracking catalyst is firstly contacted with the heavy superposed oil and then contacted with the hydrocarbon oil raw material.

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

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 silica-alumina;

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

5. The method of claim 1, further comprising: 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;

6. The method according to claim 1, characterized in that the cutting temperature of the light gasoline and the heavy gasoline is 50-80 ℃, preferably 60-70 ℃.

7. The method of claim 1, wherein the reaction conditions of the catalytic polymerization 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 to 5 hours ^-1 ；

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

8. The method according to claim 1, wherein the polymerization catalyst is selected from one or more of solid phosphoric acid, ion exchange resin and zeolite molecular sieve, preferably ion exchange resin.

9. The method according to claim 1, characterized in that the cutting temperature of the light laminating oil and the heavy laminating oil is 110-150 ℃, preferably 120-130 ℃;

the total content of trimethylpentene and trimethylhexene in the light superimposed oil is more than 80 volume percent, and preferably more than 85 volume percent;

the content of C12 and higher olefins in the heavy overlapping oil is 70 vol% or more, preferably 75 vol% or more.

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

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

11. The method of claim 1, further comprising: introducing the spent catalyst into a regenerator for regeneration, and returning the obtained regenerated catalyst to the first reactor.

12. The process 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, hydrofinished oil, hydrocracked tail oil, crude oil, coal liquefied oil, shale oil, and oil sand oil.