CN111718752B

CN111718752B - Catalytic cracking method and system for producing more propylene

Info

Publication number: CN111718752B
Application number: CN201910223375.7A
Authority: CN
Inventors: 左严芬; 许友好; 白旭辉; 张博函; 王新
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: 2019-03-22
Filing date: 2019-03-22
Publication date: 2021-11-16
Anticipated expiration: 2039-03-22
Also published as: CN111718752A

Abstract

The invention relates to a catalytic cracking method and a catalytic cracking system for producing more propylene, wherein the method comprises the following steps: injecting raw oil into the bottom of a catalytic cracking reactor to contact with a catalytic cracking catalyst and carrying out catalytic cracking reaction, and allowing the obtained reaction product and the spent catalyst to enter a settler through an outlet region to separate oil gas from the spent catalyst; oil gas enters a subsequent separation system to separate out C-containing oil gas₅Fraction of olefins and C₇The olefin is distilled and segmented, and the refined olefin are subjected to polymerization reaction in an olefin polymerization device to generate C-rich product₁₂A product of the polymerization of olefins; separating the resulting polymerization product to give C₁₂Olefins are injected into the catalytic cracking reactor and/or introduced into other catalytic cracking units. The invention effectively improves the yield of propylene.

Description

Catalytic cracking method and system for producing more propylene

Technical Field

The invention relates to a catalytic cracking method and a catalytic cracking system for producing more propylene.

Background

Propylene is one of the most important petrochemical raw materials, wherein the catalytic cracking capacity is the top grade and is 34%, the steam cracking capacity is 27%, the coal-to-olefin capacity of the new technology is 23%, and the propane dehydrogenation capacity is 16%. By taking the operation and design experience of the conventional catalytic cracking reaction-regeneration system as a reference, researchers at home and abroad develop a series of process technologies for producing propylene by catalytic cracking.

KBR, together with Mobil Technology, developed the Maxofin Technology for propylene production from heavy oil. The technology adopts a double-riser reactor, conventional FCC raw materials are cracked in a first riser, naphtha generated by reaction enters a second riser to be cracked to increase the yield of propylene, and the two risers share a settler and a regenerator.

The company UOP develops the RxPro technology for producing propylene by using light olefins with more than four carbon atoms as raw materials, the technology also adopts a double-riser reactor structure, the first riser reactor is used for cracking heavy raw materials, and the second riser reactor is used for recycling C generated by the first riser reactor₅The components and naphtha, two reaction products enter into separate fractionating systems respectively.

The petroleum university in china (east china) developed the TMP technology based on the two-stage riser catalytic cracking technology. The technology takes heavy oil as a raw material, utilizes the process characteristics of sectional reaction, catalyst relay and large catalyst-oil ratio of a two-section riser catalytic cracking process, performs optimized combination of feeding modes aiming at reaction materials with different properties, and controls the reaction conditions suitable for different materials so as to achieve the purpose of improving the yield of propylene.

In the existing double-riser technology, different distillation sections are separated by a fractionating tower, cooled into liquid by heat exchange and then returned to a reactor, the different distillation sections are firstly cooled into liquid by heat exchange of the fractionating tower, and then are further converted in a second reaction system directly or after being preheated properly (still liquid) after separation, and through the processes of cooling and heating, the investment of equipment and energy consumption is increased, so that the economical efficiency of the process technology is greatly reduced. Meanwhile, gasoline produced by catalytic cracking contains a considerable amount of olefin, the olefin content in the motor gasoline is more strictly limited along with the improvement of the environmental protection requirement, and the olefin content is not more than 20% according to the national six-gasoline standard, so that great challenges are brought to the traditional crude oil processing technology.

To obtain higher propylene yields, a portion of the gasoline fraction produced by the catalytic cracking unit, or equivalently from a refinery such as C₆、C₇And C₈The oligomer feed is recycled to an additional reactor, typically a secondary riser.

CN103814002A discloses a process for oligomerizing using one or more hydrocarbons. The method may comprise including one or more C₃-C₅The hydrocarbon feed is oligomerized to produce an effluent, and at least a portion of the effluent for oligomerization is recycled to produce propylene in excess. Which forms one or more C's in the oligomerization reaction zone₈ ⁺Hydrocarbons, e.g. C₈、C₉、C₁₂、C₁₆And C₂₀An olefin.

Disclosure of Invention

The invention aims to provide a catalytic cracking method and a catalytic cracking system for producing more propylene, which effectively improve the yield of propylene. The inventor unexpectedly discovers C in the experimental process₁₂The selectivity of olefin cracking to propylene is highest. The invention has the importance that the separated gasoline olefin products are selectively superposed, the cracking obtains higher propylene yield, and the effective utilization of petroleum resources is realized.

In order to achieve the above object, the present invention provides a catalytic cracking process for producing propylene in high yield, the process comprising:

injecting raw oil into the bottom of a catalytic cracking reactor to contact with a catalytic cracking catalyst and carrying out catalytic cracking reaction to obtain a reaction product and a spent catalyst;

introducing the obtained spent catalyst into a regenerator for coke burning regeneration to obtain a regenerated catalyst serving as the catalytic cracking catalyst to return to the catalytic cracking reactor;

separating at least C from the reaction product₅Fraction of olefins and C₇Fractionating the olefin to obtain a fraction containing C₅Fraction of olefins and C₇Introducing the fraction of olefin into a polymerization reactor, contacting with polymerization catalyst, and carrying out polymerization reaction to obtain the catalyst containing C₁₂A product of the polymerization of olefins; and/or the foreign material contains C₅Fraction of olefins and C₇The fraction containing C is produced by polymerization reaction₁₂A product of the polymerization of olefins;

superposing the obtainedProduct separation to obtain C₁₂Olefin, and C₁₂The olefin is introduced into the catalytic cracking reactor to perform catalytic cracking reaction and/or introduced into other catalytic cracking devices to perform catalytic cracking reaction.

Optionally, the conditions of the polymerization reaction include: the temperature is 50-550 ℃, the pressure is 0.2-8.0 MPa, and the weight hourly space velocity is 0.1-10 hours^-1，C₅Olefins with C₇The weight ratio of the olefin is 1: (0.7-3);

the polymerization catalyst is selected from one or more of phosphoric acid catalyst, acidic resin, silicon-aluminum solid acid catalyst and molecular sieve solid acid catalyst.

Optionally, the phosphoric acid catalyst is one or more of a catalyst formed by loading phosphoric acid on diatomite, a catalyst formed by loading phosphoric acid on activated carbon, a catalyst formed by quartz sand soaked by phosphoric acid, a catalyst formed by loading phosphoric acid on silica gel, and a catalyst formed by loading copper pyrophosphate on silica gel;

the silicon-aluminum solid acid catalyst is formed by loading metal ions on alumina and/or an amorphous silicon-aluminum carrier, and the loaded metal ions are selected from VIII group metals and/or IVA group metals;

based on the weight of the molecular sieve solid acid catalyst, the molecular sieve solid acid catalyst comprises 10-100 wt% of zeolite and 0-90 wt% of matrix, wherein the zeolite is selected from one or more of Y-type zeolite, ZSM-5 zeolite and beta zeolite.

Optionally, C in the superimposed product is based on the weight of the superimposed product₁₂The content of olefin is more than 40 wt%, more preferably more than 70 wt%, and most preferably more than 80 wt%;

said C is₅Fraction of olefins and C₇Fraction C of olefins₅Olefins and C₇The total content of olefins is from 40 to 100% by weight;

to contain C₅Fraction of olefins and C₇Based on the total weight of the fraction containing olefins, said fraction containing C₅Fraction of olefins and C₇Sulfur content in the olefin fractionation sectionNot more than 20 micrograms/gram, the content of alkaline nitride is not more than 0.6 micrograms/gram, the content of water is 600 micrograms/gram and 1800 micrograms/gram, and the content of diene is not more than 200 micrograms/gram.

Optionally, the method further includes: will separate out C₁₂The polymerization product of the olefin is returned to the polymerization reactor for the polymerization reaction.

Optionally, C introduced into the catalytic cracking reactor for catalytic cracking reaction and/or into other catalytic cracking devices₁₂The olefin accounts for 1-35 wt% of the raw oil.

Optionally, the raw oil is petroleum hydrocarbon and/or other mineral oil, wherein the petroleum hydrocarbon is one or more of vacuum gas oil, atmospheric gas oil, coker gas oil, deasphalted oil, vacuum residue, atmospheric residue and heavy aromatic raffinate oil; the other mineral oil is one or more selected from coal liquefied oil, oil sand oil and shale oil.

Optionally, the catalytic cracking catalyst comprises 1-50 wt% of zeolite selected from medium pore zeolite selected from ZSM series zeolite and/or ZRP zeolite, 5-99 wt% of inorganic oxide and 0-70 wt% of clay based on the weight of the catalytic cracking catalyst, and the large pore zeolite is selected from one or more of rare earth Y, rare earth hydrogen Y, ultrastable Y and high silicon Y.

Optionally, the catalytic cracking reactor and the other catalytic cracking unit are independently selected from one or two of a riser, a fluidized bed with equal linear speed, a fluidized bed with equal diameter, an ascending conveyor line and a descending conveyor line in series combination, wherein the riser is an equal-diameter riser reactor or a variable-diameter fluidized bed reactor.

Optionally, the variable diameter fluidized bed reactor includes two reaction zones, and the conditions of the first reaction zone include: the reaction temperature is 510-650 ℃, the reaction time is 0.05-1.0 second, and the weight ratio of the catalyst to the raw oil is (3-15): 1, the weight ratio of the water vapor to the raw oil is (0.03-0.3): 1;

the conditions of the second reaction zone include: the reaction temperature is 420-550 ℃, and the reaction time is 1.5-20 seconds.

Optionally, the variable diameter fluidized bed reactor includes two reaction zones, and the conditions of the first reaction zone include: the reaction temperature is 520-600 ℃, the reaction time is 0.1-1 second, and the weight ratio of the catalyst to the raw oil is (4-12): 1, the weight ratio of the water vapor to the raw oil is (0.05-0.2): 1;

the conditions of the second reaction zone include: the reaction temperature is 460-530 ℃, and the reaction time is 2-10 seconds.

The invention also provides a catalytic cracking system for producing more propylene, which comprises a catalytic cracking reactor, a regenerator, an oil agent separation device, a product fractionation device, an olefin separation device, a superposition reactor, a rectifying tower and other optional catalytic cracking devices;

the catalytic cracking reactor is provided with a raw oil inlet, a catalyst inlet, an oil outlet and a catalyst outlet₁₂An olefin inlet, an oil agent separation device is provided with an oil agent inlet, a catalyst outlet and a reaction product outlet, and a product fractionation device is at least provided with a reaction product inlet and a reaction product outlet₅Cut section outlet and C₇The device comprises a distillation section outlet, an olefin separation device, other catalytic cracking devices, a regenerator, a polymerization reactor and a rectifying tower, wherein the olefin separation device is provided with a distillation section inlet and an olefin outlet, the other catalytic cracking devices are provided with a raw oil inlet, a catalyst inlet and an oil outlet, the regenerator is provided with a catalyst inlet and a catalyst outlet, the polymerization reactor comprises a raw material inlet and a polymerization product outlet, and the rectifying tower is provided with an oil gas inlet, a C oil gas inlet and a C oil gas outlet₁₂An olefin outlet and a separated product outlet;

the oil outlet of the catalytic cracking reactor is communicated with the oil inlet of the oil separating device, the reaction product outlet of the oil separating device is communicated with the reaction product inlet of the product fractionating device, and the C of the product fractionating device₅Cut section outlet and C₇The outlet of the fraction section is communicated with the inlet of the fraction section of the olefin separation device, the olefin outlet of the olefin separation device is communicated with the raw material inlet of the polymerization reactor, the outlet of the polymerization product of the polymerization reactor is communicated with the oil gas inlet of the rectifying tower, and the C of the rectifying tower₁₂Olefin outlet and C of the catalytic cracking reactor₁₂Olefin hydrocarbon intoThe port and/or the raw oil inlet of the other catalytic cracking device are communicated, the catalyst inlet of the catalytic cracking reactor is communicated with the catalyst outlet of the regenerator, and the catalyst inlet of the regenerator is communicated with the catalyst outlet of the oil separating device.

Compared with the prior art, the beneficial effects of the invention are mainly embodied in the following aspects:

(1) the product obtained by the catalytic cracking reaction of the raw oil has higher olefin content, and C₅And C₇Olefin separation followed by metathesis conversion to C which is readily cracked to form propylene₁₂The olefin can effectively improve the yield of the propylene and reduce the content of other olefins in the product, meets the market demand, improves the economic benefit, has less equipment investment, relatively mild process conditions and low product cost, and has great attraction to refineries and chemical plants without hydrogenation olefin reduction devices and lacking rich hydrogen sources.

(2) The olefin selective polymerization process and the catalytic cracking process are combined, so that the reaction conditions can be flexibly controlled, the target reaction can be effectively promoted, and the target product can be increased.

(3) The raw oil is converted into propylene to the maximum extent, and the olefin content of the gasoline is reduced, so that the efficient utilization of petroleum resources is realized.

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

Drawings

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

fig. 1 comprises a schematic flow diagram of a first embodiment of the method of the present invention, and also comprises a schematic structural diagram of a first embodiment of the system of the present invention.

Fig. 2 comprises a schematic flow diagram of a second embodiment of the method of the present invention, and also comprises a schematic structural diagram of a second embodiment of the system of the present invention.

FIG. 3 comprises a schematic flow diagram of a third embodiment of the method of the present invention, and also comprises a schematic structural diagram of a third embodiment of the system of the present invention.

Fig. 4 includes a schematic flow chart of a fourth embodiment of the method of the present invention, and also includes a schematic structural diagram of the fourth embodiment of the system of the present invention.

Description of the reference numerals

I first reaction zone II second reaction zone

1 line 2 riser reactor 3 lines

4 line 5 line 6 line

7 outlet section 8 settler 9 gas collection chamber

10 stripping section 11 pipeline 12 inclined tube

13 regenerator 14 line 15 line

16 line 17 large oil and gas line 18 product fractionation unit

19 line 20 line 21 line

22 line 23 line 24 line

25 line 26 line 29 rectification column

31 line 34 line

35 line 36 line 40 olefin separation unit

41 line 42 line 44 superposition reactor

46 line 51 preconditioner 52 compressor

53 heat exchanger 54 other catalytic cracking unit

2A riser reactor and 2B fluidized bed reactor

201 pipeline 203 pipeline 204 pipeline

207 line

208 settler 209 plenum 210 stripping section

211 line 212 inclined tube 213 regenerator

214 pipeline 215 pipeline 216 pipeline

217 big oil-gas pipeline

3A first reaction zone 3B second reaction zone

301 line 302 riser reactor 303 line

304 line 305 line 306 line

307 line 308 settler 309 plenum

310 stripping section 311 line 312 chute

313 regenerator 314 pipeline 315 pipeline

316 line 317 large oil and gas line

4A first riser tube 4B second riser tube

401 line 403 line

405 line 406 stripping section 407 outlet section

408 settler 409 plenum 410 large oil gas pipeline

411 inclined pipe 412 regenerator 413 pipeline

Line 414 line 415 line 416 line

417 inclined tube 421 line 423 line

425 line 426 stripping section 427 outlet section

428 settler 429 plenum 430 large oil gas line

Detailed Description

The following describes in detail specific embodiments of the present invention. Typical embodiments of the catalytic cracking reaction combination reactor include a riser reactor and a fluidized bed reactor connected in series, a variable diameter fluidized bed reactor or two riser reactors connected in parallel, it being understood that the specific embodiments described herein are only for illustrating and explaining the present invention and are not intended to limit the present invention.

The invention provides a catalytic cracking method for producing more propylene, which comprises the following steps:

separating the resulting polymerization product to give C₁₂Olefin, and C₁₂The olefins are introduced into the catalytic cracking reactor (preferably the bottom or middle part) for catalytic cracking reaction and/or into other catalytic cracking units for catalytic cracking reaction.

The present inventors have unexpectedly found that the reaction product contains C₅Fraction of olefins and C₇The fraction of olefin is separated out for polymerization reaction, and C in the polymerization product is₁₂The olefin is returned to the catalytic cracking reactor for reaction and/or introduced into other catalytic cracking devices, so that the yield of the propylene can be obviously improved.

The polymerization reaction is well known to the person skilled in the art and is used for the polymerization of C according to the invention₅Olefins and C₇Reaction of olefins to C₁₂An olefin. The conditions of the polymerization reaction may include: the temperature is 50-550 ℃, preferably 400-550 ℃, the pressure is 0.2-8.0 MPa, preferably 0.5-4 MPa, and the weight hourly space velocity is 0.1-10 h^-1Preferably 1 to 6 hours^-1，C₅Olefins with C₇The weight ratio of the olefin is 1: (0.7-3); the polymerization catalyst can be selected from one or more of a phosphoric acid catalyst, an acidic resin, a silicon-aluminum solid acid catalyst and a molecular sieve solid acid catalyst, and the phosphoric acid catalyst can be one or more of a catalyst formed by supporting phosphoric acid on diatomite, a catalyst formed by supporting phosphoric acid on activated carbon, a catalyst formed by soaking quartz sand in phosphoric acid, a catalyst formed by supporting phosphoric acid on silica gel and a catalyst formed by supporting copper pyrophosphate on silica gel; the silicon-aluminum solid acid catalyst can be a catalyst formed by loading metal ions on alumina and/or an amorphous silicon-aluminum carrier, wherein the loaded metal ions are selected from VIII group metals and/or IVA group metals; the molecular sieve solid acid catalyst may include 10-100 wt% zeolite, which may be one or more of Y-zeolite, ZSM-5 zeolite and beta zeolite, and 0-90 wt% matrix, based on the weight of the molecular sieve solid acid catalyst. The superimposed product may be passed through a filtration unit to remove entrained catalyst powder before being introduced further into the second reaction zone for the reaction and/or into other catalytic cracking units. C introduced into the catalytic cracking reactor for catalytic cracking reaction and/or into other catalytic cracking devices₁₂The olefin may be present in an amount of 1 to 35 wt.% based on the feed oil.

The present invention controls reaction conditions and selects catalysts to maximize production of C₁₂For the purpose of olefins, e.g. C, in the product of the polymerization, based on the weight of the product of the polymerization₁₂The content of the olefin may be 40% by weight or more, preferably 70% by weight or more, and most preferably 80% by weight or more. In addition, by optimizing the C content₅Fraction of olefins and C₇Fraction C of olefins₅Olefins and C₇The olefin content, as well as the impurities, can further promote the polymerization, for example, the C-containing₅Fraction of olefins and C₇Fraction C of olefins₅Olefins and C₇The total content of olefins is from 40 to 100% by weight; to contain C₅Fraction of olefins and C₇Based on the total weight of the fraction containing olefins, said fraction containing C₅Fraction of olefins and C₇In the olefin distillation section, the sulfur content is not more than 20 micrograms/gram, the alkaline nitride content is not more than 0.6 micrograms/gram, the water content is 600-1800 micrograms/gram, and the diene content is not more than 200 micrograms/gram.

To further increase C₅Olefins and C₇Utilization of olefins, the method may further comprise: will separate out C₁₂The olefin polymerization product is returned to the polymerization reactor for polymerization reaction, and C can be separated₁₂Further separating C from the olefin polymerization product₅Olefins and C₇Olefin, C₅Olefins and C₇The olefin is returned to the polymerization reaction.

In the present invention, the feedstock oil is well known to those skilled in the art, and for example, the feedstock oil may include petroleum hydrocarbons and/or other mineral oils, wherein the petroleum hydrocarbons are selected from one or more of a mixture of vacuum gas oil, atmospheric gas oil, coker gas oil, deasphalted oil, vacuum residue, atmospheric residue, and heavy aromatic raffinate oil; the other mineral oil is one or more selected from coal liquefied oil, oil sand oil and shale oil.

According to the present invention, the catalytic cracking catalyst is well known to those skilled in the art, and comprises, for example, from 1 to 50% by weight of a zeolite, for example selected from medium-pore zeolites and/or large-pore zeolites, as active components, from 5 to 99% by weight of an inorganic oxide and from 0 to 70% by weight of a clay, based on the weight of the catalytic cracking catalyst, the medium-pore zeolites possibly representing from 0 to 100% by weight, preferably from 0 to 50% by weight and more preferably from 0 to 20% by weight, of the total weight of the zeolites; the large pore zeolite can be 0-100 wt%, preferably 20-80 wt%, based on the total weight of the zeolite, and the medium pore zeolite can be selected from ZSM-series zeolite and/or ZRP zeolite, or the medium pore zeolite can be modified with nonmetal element such as phosphorus and/or transition metal element such as iron, cobalt, nickel, etc., and the ZSM-series zeolite can be selected from ZSM-5, ZSM-11, ZSM-12, ZSM-2, etc3. A mixture of one or more of ZSM-35, ZSM-38, ZSM-48 and other zeolites of similar structure. The large-pore zeolite can be selected from one or more of Rare Earth Y (REY), Rare Earth Hydrogen Y (REHY), ultrastable Y obtained by different methods and high-silicon Y. The inorganic oxide may be selected from silicon dioxide (SiO) as a binder₂) And/or aluminum oxide (Al)₂O₃). The clay, as a matrix (i.e., carrier), may be selected from kaolin and/or halloysite. The catalytic cracking catalyst may also be a spent equilibrium catalyst used in conventional catalytic cracking units.

According to the present invention, the first reaction zone and the second reaction zone may be adapted to the same type of catalyst or to different types of catalysts, which may be catalysts having different particle sizes and/or catalysts having different apparent bulk densities. Different types of zeolites can also be selected as active components on catalysts with different particle sizes and/or catalysts with different apparent bulk densities. The catalyst with different particles and/or the catalyst with high and low apparent bulk density can enter different reaction zones respectively, for example, the catalyst with large particles of ultrastable Y-type zeolite enters a first reaction zone to increase cracking reaction, the catalyst with small particles of rare earth Y-type zeolite enters a second reaction zone to increase hydrogen transfer reaction, the catalyst with different particle sizes is stripped in the same stripper and regenerated in the same regenerator, then the catalyst with large particles and the catalyst with small particles are separated, and the catalyst with small particles is cooled and enters the second reaction zone. The catalysts with different particle sizes are divided between 30 and 40 microns, and the catalysts with different apparent bulk densities are 0.6 to 0.7 g/cm³The division between them.

The catalytic cracking reactor used and the other catalytic cracking unit may each be independently selected from one or more combinations of equal diameter risers, equal linear velocity risers, variable diameter risers and fluidized beds, such as a composite reactor consisting of equal diameter risers and fluidized beds, for example. Preferably a variable diameter riser reactor or a combined reactor consisting of an equal diameter riser and a fluidized bed. The fluidized bed reactor can be one or two of a series combination of an equal linear speed fluidized bed, an equal diameter fluidized bed, an ascending conveyor line and a descending conveyor line. The riser can be a conventional equal-diameter riser or can be a riser with variable diameters in various forms. Wherein the gas velocity of the fluidized bed can be 0.1-2 m/s, and the gas velocity of the riser can be 2-30 m/s (excluding catalyst). The preferred embodiment of the present invention is operated in a variable diameter riser reactor, see CN1237477A for a more detailed description of the reactor.

According to the present invention, the reaction conditions of catalytic cracking can be adjusted according to the reactor, and those skilled in the art can adopt conventional reaction conditions, for example, a variable diameter fluidized bed reactor comprises two reaction zones, the reaction of the first reaction zone of catalytic cracking is mainly macromolecule cracking reaction, and the reaction of the second reaction zone is mainly cracking, hydrogen transfer and isomerization reaction, for example, the conditions of the first reaction zone include: the reaction temperature is 510-650 ℃, the reaction time is 0.05-1.0 second, and the weight ratio of the catalyst to the raw oil is (3-15): 1, the weight ratio of the water vapor to the raw oil is (0.03-0.3): 1, the pressure is 130-450 kPa; the conditions of the second reaction zone include: the reaction temperature is 420-550 ℃, and the reaction time is 1.5-20 seconds. The conditions of the first reaction zone preferably include: the reaction temperature is 520-600 ℃, the reaction time is 0.1-1 second, preferably 0.1-0.5 second, and the weight ratio of the catalyst to the raw oil is (4-12): 1, the weight ratio of the water vapor to the raw oil is (0.05-0.2): 1; the conditions of the second reaction zone preferably include: the reaction temperature is 460-530 ℃, and the reaction time is 2-10 seconds.

According to the invention, C may be₁₂The olefin is introduced into the same other catalytic cracking unit, or different other catalytic cracking units, and the structures and reaction conditions of the other catalytic cracking units and the catalytic cracking reactor can be the same or different, and the technical personnel in the field can set the catalytic cracking reactor according to the requirement of high propylene yield.

According to the invention, the reaction product can be separated into dry gas, propane and propane in addition to the above-mentioned fractionAlkenes, gasoline, diesel, and the like. Containing C₅Fraction of olefins and C₇The separation of olefins in the distillation section is well known to the person skilled in the art, preferably by extractive distillation in acetonitrile as solvent, it being possible for C to be separated off first by fractional distillation₅Fraction and C₇Fractionating the fraction and then further fractionating C₅Fraction and C₇Separation of alkanes in the fractionation section to obtain C-containing fractions₅Fraction of olefins and C₇The fraction of olefins. Since diolefins tend to poison the catalyst, too high a level of sulfur, especially mercaptans and hydrogen sulfide, reduces the activity of the catalyst and promotes the formation of gums in the gasoline, C₅Fraction of olefins and C₇The fraction section of the olefin can be treated by pretreatment units such as selective hydrogenation for removing diene, ethanolamine for desulfurization, alkali washing and water washing, alkali and nitrogen compound removal and the like, and then the superposition reaction is carried out, wherein the treatment modes are well known by the technical personnel in the field, and the details are not repeated.

the oil outlet of the catalytic cracking reactor is communicated with the oil inlet of the oil separating device,a reaction product outlet of the oil agent separation device is communicated with a reaction product inlet of the product fractionation device, and C of the product fractionation device₅Cut section outlet and C₇The outlet of the fraction section is communicated with the inlet of the fraction section of the olefin separation device, the olefin outlet of the olefin separation device is communicated with the raw material inlet of the polymerization reactor, the outlet of the polymerization product of the polymerization reactor is communicated with the oil gas inlet of the rectifying tower, and the C of the rectifying tower₁₂Olefin outlet and C of the catalytic cracking reactor₁₂And the olefin inlet and/or the raw oil inlet of the other catalytic cracking device are communicated, the catalyst inlet of the catalytic cracking reactor is communicated with the catalyst outlet of the regenerator, and the catalyst inlet of the regenerator is communicated with the catalyst outlet of the oil separation device. The reactors and apparatus of the system of the present invention are well known to those skilled in the art and will not be described in detail herein.

The present inventors have unexpectedly found that the reaction product contains C₅Fraction of olefins and C₇The fraction of olefin is separated out for polymerization reaction, and C in the polymerization product is₁₂The olefin is returned to the second reaction zone of the catalytic cracking reactor for reaction, so that the yield of the propylene can be obviously improved.

The method provided by the present invention is further illustrated with reference to the accompanying drawings, but the invention is not limited thereby.

First embodiment

As shown in figure 1, a pre-lifting medium enters from the bottom of a riser reactor 2 through a pipeline 1, a regenerated catalytic cracking catalyst from a pipeline 16 moves upwards in an accelerated manner along the riser reactor 2 under the lifting action of the pre-lifting medium, preheated raw oil is injected into the bottom of a first reaction zone I of the riser reactor 2 through a pipeline 3 together with atomized steam from a pipeline 4 and is mixed with existing material flow of the riser reactor 2, and the raw oil is subjected to a cracking reaction on a hot catalyst and moves upwards in an accelerated manner. The light raw oil is injected into the bottom of the second reaction zone II of the riser reactor 2 through a pipeline 5 and atomized steam from a pipeline 6, and is mixed with the existing reaction oil material flow of the riser reactor, so that the light raw oil is lightThe raw oil is cracked on the lower catalyst containing carbon and moves upward in an accelerated manner, the generated reaction product and the inactivated spent catalyst enter a cyclone separator in a settler 8 through an outlet section 7 to realize the separation of the spent catalyst and the reaction product, the reaction product enters an air collection chamber 9, and the fine catalyst powder returns to the settler through a dipleg. Spent catalyst in the settler flows to the stripping section 10 where it is contacted with steam from line 11. Oil gas stripped from the spent catalyst enters a gas collection chamber 9 after passing through a cyclone separator. The stripped spent catalyst enters a regenerator 13 through an inclined pipe 12, the main air enters the regenerator through a pipeline 14 to burn off coke on the spent catalyst, the inactivated spent catalyst is regenerated, and the flue gas enters a smoke machine through a pipeline 15. The regenerated catalyst enters the riser via line 16. Oil gas in the gas collection chamber 9 enters a subsequent product fractionation device 18 through a large oil-gas pipeline 17, propylene obtained by separation is led out through a pipeline 20, propane obtained by separation is led out through a pipeline 21, catalytic cracking dry gas is led out through a pipeline 19, a gasoline fraction section is led out through a pipeline 24, a diesel fraction section is led out through a pipeline 25, and oil slurry is led out through a pipeline 26. C₅、C₇The distillation sections are respectively led out through a pipeline 22 and a pipeline 23, enter an olefin separation device 40, the separated alkane is returned through a pipeline 41 to be mixed with the gasoline fraction section, the olefin material flow is sent to a preprocessor 51 through a pipeline 42, is subjected to desulfurization, alkali washing and water washing, is pressurized through a compressor 52, is subjected to heat exchange through a heat exchanger 53, enters a superposition reactor 44, is contacted with a superposition catalyst and is subjected to superposition reaction, a superposition product obtained by the superposition reaction is sent to a rectifying tower 29 through a pipeline 46 to be separated to obtain C₁₂After the olefin, C₁₂The olefin is fed into the second reaction zone II via the line 34, the line 28 and the line 31 and/or is introduced into a further catalytic cracking unit 54 via the line 34, the line 28 and the line 36, and is continuously cracked to form propylene, C is separated₁₂The olefin post-polymerization product is sent via line 35 or returned to polymerization reactor 44.

Second embodiment

The preferred technical scheme of the embodiment comprises the following steps:

as shown in FIG. 2, the hot regenerated catalyst from line 216 is lifted via the pre-lift medium from line 201Ascending along the riser reactor 2A, the raw oil from the pipeline 203 is atomized by the atomized steam from the pipeline 204 and then introduced into the riser reactor 2A to contact with the existing materials of the riser reactor 2A, and the raw oil reacts in the first catalytic cracking reactor under the conditions that the reaction temperature is 500-650 ℃, the reaction time is 0.5-4 seconds, the reaction pressure is 0.15-0.30 MPa (absolute), and the weight ratio of the catalytic cracking catalyst to the raw material is 1-100; introducing the reaction oil obtained in the first catalytic cracking reactor into a fluidized bed reactor 2B for a second catalytic cracking reaction at 480-620 ℃ and a weight hourly space velocity of 0.2-30h^-1The reaction pressure is 0.15-0.30 MPa (absolute) to obtain spent catalyst and reaction product, the spent catalyst and reaction product are subjected to oil separation in a settler 208, the reaction product enters a gas collection chamber 209 and is led out from a large oil-gas pipeline 217, the spent catalyst enters a stripping section 210 to be in countercurrent contact with stripping steam from a pipeline 211 for stripping, the stripped spent catalyst is led into a regenerator 213 from an inclined pipe 212 to be burnt and regenerated with air from a pipeline 214, the regenerated flue gas leaves the regenerator 213 from a pipeline 215 to obtain regenerated catalyst, the regenerated catalyst is used as the catalytic cracking catalyst and is returned to the first catalytic cracking reactor from a pipeline 216, and the obtained reaction product is at least separated to obtain C₅Olefins and C₇Olefin, separation of product C after polymerization₁₂Olefin, C₁₂Olefins are introduced from line 207 into the second catalytic cracking reactor for continued cracking to yield propylene.

Third embodiment

The preferred technical scheme of the embodiment comprises the following steps:

as shown in fig. 3, the thermally regenerated catalyst from the line 316 is lifted up along the first reaction zone 3A of the riser reactor 302 by the pre-lifting medium from the line 301, the feedstock oil from the line 303 is atomized by the atomized steam from the line 304 and introduced into the first reaction zone 3A to contact with the existing material of the first reaction zone 3A, and the catalytic cracking reaction occurs in the first reaction zone 3A and the second reaction zone 3B in sequence, wherein the conditions of the first reaction zone include: the reaction temperature is 520-600 ℃, the reaction time is 0.1-1 second, and the weight ratio of the catalyst to the raw oil is (4-12): 1,the weight ratio of the water vapor to the raw oil is (0.05-0.2): 1; the conditions of the second reaction zone include: the reaction temperature is 460-530 ℃, and the reaction time is 2-10 seconds. Reaction products and spent catalyst to be coked are separated in a settler 308 along an outlet section 307 of the riser reactor, the reaction products enter a gas collection chamber 309 and are led out from a large oil-gas pipeline 317, the spent catalyst enters a stripping section 310 to be in countercurrent contact with stripping steam from a pipeline 311 for stripping, the stripped spent catalyst is led into a regenerator 313 from an inclined pipe 312 to be burnt and regenerated with air from a pipeline 314, regenerated flue gas leaves the regenerator 313 from a pipeline 315 to obtain regenerated catalyst serving as the catalytic cracking catalyst, the regenerated catalyst returns to the first catalytic cracking reactor from a pipeline 316, and the obtained reaction products are at least separated to obtain C₅Olefins and C₇Olefin, separation of product C after polymerization₁₂Olefin, C₁₂Olefins from line 305 are atomized via atomized steam from line 306 and introduced into the second reaction zone and/or other catalytic cracking unit for continued cracking to yield propylene.

Fourth embodiment

The preferred technical scheme of the embodiment comprises the following steps:

raw oil is introduced into the bottom of a first riser 4A from a pipeline 403, a thermally regenerated catalyst from a pipeline 415 is contacted with the raw oil after being lifted by pre-lifting steam from a pipeline 401, the reaction temperature is 450-550 ℃, the reaction time is 0.5-5 seconds, the reaction pressure is 0.15-0.40 MPa (absolute), and the weight ratio of the catalytic cracking catalyst to the raw material is 5-20, the obtained spent catalyst and reaction products enter a settler 408 along an outlet section 407 for oil separation, the obtained reaction products enter a plenum chamber 409 and are led out from a large oil pipeline 410, the spent catalyst is introduced into a stripping section 406 for countercurrent stripping with stripping steam from the pipeline 405, then is introduced into a regenerator 412 from an inclined pipe 411 to be contacted with air from a pipeline 413 for coke burning regeneration, regenerated flue gas leaves the regenerator 412 from the pipeline 414, and the obtained regenerated catalyst is returned into the first riser 4A from the pipeline 415 as the catalytic cracking catalyst. Separating at least C from the reaction product₅Olefins and C₇Olefins, after being superimposedIsolation of product C₁₂Olefin, C₁₂Olefin is introduced into the second riser 4B from line 423 and hot regenerated catalyst from line 416 is promoted with C via pre-lift steam from line 421₆Olefin is contacted, the propylene yield is increased by continuously cracking under the conditions that the reaction temperature is 350-660 ℃, the reaction time is 1.0-8 seconds, the reaction pressure is 0.15-0.40 MPa (absolute), the weight ratio of the catalytic cracking catalyst to the raw materials is 3-45, the obtained reaction product enters a settler 428 along an outlet section 427 for oil separation, the obtained reaction product enters a plenum chamber 429 and is led out from a large oil-gas pipeline 430, the spent catalyst is led into a stripping section 426 for countercurrent stripping with stripping steam from a pipeline 425, then the spent catalyst is led into a regenerator 412 from an inclined pipe 417 to be contacted with air from a pipeline 413 for scorching regeneration, and the regenerated flue gas leaves the regenerator 412 from a pipeline 414.

The invention will be further illustrated by the following examples, but is not to be construed as being limited thereto.

The properties of the raw material A, B, C, D used in the examples are shown in Table 1.

The preparation of the catalytic cracking catalyst A used in the examples is briefly as follows:

1) 20 g of NH₄Cl was dissolved in 1000 g of water, and 100 g (dry basis) of crystallized ZRP-1 zeolite (produced by catalyst works of Qilu petrochemical Co., Ltd., SiO) was added to the solution₂/Al₂O₃30, rare earth content RE₂O₃2.0 wt%), exchanged at 90 ℃ for 0.5 hour, filtered to obtain a filter cake; 4.0 g of H are added₃PO₄(85% strength) with 4.5 g Fe (NO)₃)₃Dissolving in 90 g of water, mixing with a filter cake, soaking and drying; then roasting at 550 ℃ for 2 hours to obtain the MFI structure mesoporous zeolite containing phosphorus and iron, and the element analysis chemical composition of the MFI structure mesoporous zeolite containing phosphorus and iron is as follows:

0.1Na₂O·5.1Al₂O₃·2.4P₂O₅·1.5Fe₂O₃·3.8RE₂O₃·88.1SiO₂。

2) 75.4 kg of halloysite (product of Suzhou china clay company, Ltd.) was mixed with 250 kg of decationized water71.6 wt.%) pulping, adding 54.8 kg of pseudoboehmite (industrial product from Toho aluminum plant, solid content 63 wt.%), adjusting pH to 2-4 with hydrochloric acid, stirring, standing at 60-70 deg.C for 1 hr, ageing, keeping pH at 2-4, cooling to below 60 deg.C, adding 41.5 kg of alumina sol (catalyst plant product from Qilu petrochemical company, Al)₂O₃Content 21.7 wt%), and stirred for 40 minutes to obtain a mixed slurry.

3) Adding the MFI structure mesoporous zeolite (dry basis is 2 kg) containing phosphorus and iron and prepared in the step 1) and DASY zeolite (industrial product of catalyst plant of Qilu petrochemical company, unit cell constant is 2.445-2.448 nm, dry basis is 22.5 kg) into the mixed slurry obtained in the step 2), stirring uniformly, spray drying and forming, washing with ammonium dihydrogen phosphate solution (phosphorus content is 1 wt%), washing to remove free Na⁺Drying to obtain a catalytic cracking catalyst sample, wherein the dry basis of the catalyst comprises 2 wt% of phosphorus and iron-containing MFI structure mesoporous zeolite, 18 wt% of DASY zeolite, 32 wt% of pseudo-boehmite, 7 wt% of alumina sol and the balance of kaolin.

The preparation of the hydrotreating catalyst used in the examples is briefly as follows: ammonium metatungstate ((NH) was weighed₄)₂W₄O₁₃·18H₂O, chemically pure) and nickel nitrate (Ni (NO)₃)₂·18H₂O, chemically pure), 200 ml of solution was made with water. The solution was added to 50 g of alumina support, immersed at room temperature for 3 hours, the immersion liquid was treated with ultrasonic waves for 30 minutes during the immersion, cooled, filtered, and dried in a microwave oven for about 15 minutes. The catalyst comprises the following components: 30.0% by weight of WO₃L wt% NiO and balance alumina. Denoted as F.

The properties of the cat A, B, C, D and the procatalyst E used in the examples are set forth in Table 2, the procatalyst E being a molecular sieve solid acid catalyst and having the commercial designation RGW-1.

Example 1

This example was tested according to the procedure of FIG. 1, feedstock A being the feedstock for catalytic cracking, on a medium-sized unit of a variable diameter fluidized bed reactorThe oil A enters the bottom of a first reaction area I, contacts with a catalyst A and sequentially undergoes catalytic cracking reaction in the first reaction area I and a second reaction area II, a reaction product and a spent catalyst to be carbonized are separated in a settler, and the reaction product is cut according to the distillation range in a product fractionation device, so that dry gas, liquefied gas, propylene, C are obtained₅Fraction section, C₇Distillate fractions, gasoline, diesel and slurry oil. C₅Fraction section, C₇The fraction enters an olefin separation device to separate C₅Fraction of olefins and C₇The fraction of olefins enters a polymerization reactor, wherein C₅Olefins and C₇Olefin accounts for 90 wt%, sulfur content is 18 microgram/g, basic nitride content is 0.3 microgram/g, water content is 1200 microgram/g, diene content is 100 microgram/g, C₅Olefins with C₇The weight ratio of the olefin is 1: 0.7 at 400 ℃ and a weight hourly space velocity of 2.1 h^-1Reacting with a superposed catalyst under the reaction pressure of 3 MPa to obtain a superposed product, and separating C₁₂Olefins, C in the product of said polymerization₁₂Olefin content 70 wt.%, C separated₁₂The olefin is circulated to the second reaction zone of the medium-sized device of the reducing fluidized bed reactor to be continuously cracked, C₁₂The olefin accounted for 14.56 wt% of the weight of the feed oil. The operating conditions and the product distribution are listed in Table 3.

Comparative example 1

Substantially the same as in example 1 except that no laminating operation was conducted and C₁₂Olefin recycling. The operating conditions and the product distribution are listed in Table 3.

Example 2

Feed oil B was used as a catalytic cracking feed and tested in a riser reactor and a fluidized bed reactor as shown in fig. 2. The raw oil B is contacted with a catalyst B, and the reaction is carried out in a riser reactor under the conditions that the reaction temperature is 650 ℃, the reaction time is 0.8 second, the weight ratio of the catalyst to the oil is 20, and the weight ratio of the water to the oil is 0.8; introducing the obtained reaction oil agent into a fluidized bed reactor for continuous reaction, wherein the reaction temperature is 580 ℃, and the weight hourly space velocity is 10h^-1. To obtain spent catalyst and reaction product, and regenerating the spent catalyst to obtain regenerated catalystReturning agent as said catalytic cracking catalyst to said riser reactor; the reaction product is cut according to the distillation range in a product fractionation device, thereby obtaining dry gas, liquefied gas, propylene and C₅Fraction section, C₇Distillate fractions, gasoline, diesel and slurry oil. C₅Fraction section, C₇The fraction enters an olefin separation device to separate C₅Fraction of olefins and C₇The fraction of olefins enters a polymerization reactor, wherein C₅Olefins and C₇Olefin accounts for 90 wt%, sulfur content is 18 microgram/g, basic nitride content is 0.3 microgram/g, water content is 1200 microgram/g, diene content is 100 microgram/g, C₅Olefins with C₇The weight ratio of the olefin is 1: 0.7 at 400 ℃ and a weight hourly space velocity of 2.1 h^-1Reacting with a superposed catalyst under the reaction pressure of 3 MPa to obtain a superposed product, and separating C₁₂Olefins, C in the product of said polymerization₁₂The content of olefin was 70% by weight, and C was separated in an amount of 9.36% by weight based on the feed oil₁₂The olefin is circulated to the fluidized bed reactor to continue cracking. The operating conditions and the product distribution are listed in Table 4.

Comparative example 2

Substantially the same as in example 2 except that no laminating operation was conducted and C₁₂Olefin recycling. The operating conditions and the product distribution are listed in Table 4.

Example 3

Feedstock C was tested as a feedstock for catalytic cracking in a riser plus fluidized bed reactor as shown in fig. 2. The raw oil C is contacted with a catalyst C, and the reaction is carried out in a riser reactor under the conditions that the reaction temperature is 530 ℃, the reaction time is 1.5 seconds, the weight ratio of the catalyst to the oil is 8, and the weight ratio of the water to the oil is 0.1; introducing the obtained reaction oil agent into a fluidized bed reactor for continuous reaction, wherein the reaction temperature is 500 ℃, and the weight hourly space velocity is 10h^-1. Obtaining spent catalyst and reaction products, regenerating the spent catalyst to obtain regenerated catalyst serving as the catalytic cracking catalyst and returning the regenerated catalyst to the riser reactor; the reaction product is cut according to the distillation range in a product fractionation device, thereby obtaining dry gas, liquefied gas, propylene and C₅A distillation section,C₇The system comprises a distillation section, gasoline, diesel oil and oil slurry, wherein the oil slurry is returned to the riser reactor after being subjected to hydrogenation treatment. C₅Fraction section, C₇The fraction enters an olefin separation device to separate C₅Fraction of olefins and C₇The fraction of olefins enters a polymerization reactor, wherein C₅Olefins and C₇Olefin accounts for 90 wt%, sulfur content is 18 microgram/g, basic nitride content is 0.3 microgram/g, water content is 1200 microgram/g, diene content is 100 microgram/g, C₅Olefins with C₇The weight ratio of the olefin is 1: 0.7 at 400 ℃ and a weight hourly space velocity of 2.1 h^-1Reacting with a superposed catalyst under the reaction pressure of 3 MPa to obtain a superposed product, and separating C₁₂Olefins, C in the product of said polymerization₁₂The content of olefin was 70 wt%, and C was separated in an amount of 11.08 wt% based on the feed oil₁₂The olefin is circulated to the fluidized bed reactor to continue cracking. The operating conditions and the product distribution are listed in Table 5.

Comparative example 3

Substantially the same as in example 3 except that no laminating operation was conducted and C₁₂Olefin recycling. The operating conditions and the product distribution are listed in Table 5.

Example 4

Feedstock D was tested as a feedstock for catalytic cracking in a double riser reactor as shown in FIG. 4. Raw oil D is contacted with a catalyst D, the reaction is carried out in a first lifting pipe under the conditions that the reaction temperature is 600 ℃, the reaction time is 1.5 seconds, the catalyst-oil weight ratio is 6 and the water-oil weight ratio is 0.05 to obtain a spent catalyst and a reaction product, the spent catalyst is regenerated to obtain a regenerated catalyst serving as the catalytic cracking catalyst and returns to the first lifting pipe, and the reaction product is cut according to the distillation range in a product fractionation device to obtain dry gas, liquefied gas, propylene and C₅Fraction section, C₇Distillate fractions, gasoline, diesel and slurry oil. C₅Fraction section, C₇The fraction enters an olefin separation device to separate C₅Fraction of olefins and C₇The fraction of olefins enters a polymerization reactor, wherein C₅Olefins and C₇Olefin accounts for 90 wt%, sulfur content is 18 microgram/g, basic nitride content is 0.3 microgram/g, water content is 1200 microgram/g, diene content is 100 microgram/g, C₅Olefins with C₇The weight ratio of the olefin is 1: 0.7 at 400 ℃ and a weight hourly space velocity of 2.1 h^-1Reacting with a superposed catalyst under the reaction pressure of 3 MPa to obtain a superposed product, and separating C₁₂Olefins, C in the product of said polymerization₁₂The content of olefin was 70% by weight, and C was separated in an amount of 15.34% by weight based on the feed oil₁₂The olefin is circulated to the second riser, and the cracking production of the propylene is increased continuously under the conditions that the reaction temperature is 500 ℃, the reaction time is 3 seconds, the weight ratio of the catalyst to the oil is 6, and the weight ratio of the water to the oil is 0.05. The operating conditions and the product distribution are listed in Table 6.

Comparative example 4

Basically the same as example 4, except that no folding operation was performed, the gasoline 15.34 wt% of the feed oil was separated from the first catalytic cracking reaction product and recycled to the second catalytic cracking. The operating conditions and the product distribution are listed in Table 6.

As can be seen from tables 3, 4, 5 and 6, C in gasoline is₄、C₈Olefin is separated and selectively superposed to generate C₁₂The propylene yield can be improved by 38-120% by carrying out olefin recycling.

Comparative example 5

Essentially the same as in example 1, except that C was not recycled₁₂Olefins, but separating C from the polymerization product₇Olefin, C₇Recycling the olefin to the second reaction zone for continuous cracking, C₇The olefin accounted for 14.56 wt% of the vacuum residue weight and the product distribution is listed in table 7.

Comparative example 6

Substantially the same as in example 1, except that the temperature was 400 ℃ and the weight hourly space velocity was 2 hours^-1Reacting with a superposed catalyst under the reaction pressure of 2.5 MPa to obtain a superposed product, and separating C₁₀Olefin, C₁₀Recycling the olefin to the second reaction zone for continuous cracking, C₁₀The olefin accounted for 14.56 wt% of the vacuum residue weight and the product distribution is listed in table 7.

Comparative example 7

Substantially the same as in example 1, except that the temperature was 450 ℃ and the weight hourly space velocity was 2.5 hours^-1Reacting with a superposed catalyst under the reaction pressure of 3 MPa to obtain a superposed product, and separating C₁₄Olefin, C₁₄Recycling the olefin to the second reaction zone for continuous cracking, C₁₄The olefin accounted for 14.56 wt% of the vacuum residue weight and the product distribution is listed in table 7.

As can be seen from Table 7, C₁₂The olefin is recycled, so that the propylene yield is higher.

The preferred embodiments of the present invention have been described in detail, however, the present invention 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 invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the content of the present invention as long as it does not depart from the gist of the present invention.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

TABLE 5

TABLE 6

TABLE 7

Item	Comparative example 5	Comparative example 6	Comparative example 7
				Dry gas	7.99	7.31	7.80
Liquefied gas	36.71	36.20	37.55
				Propylene (PA)	14.88	15.34	15.79
Gasoline (gasoline)	18.22	18.72	17.96
				Diesel oil	22.09	22.59	20.81
Oil slurry	5.66	5.43	5.91
				Coke	9.33	9.75	9.97
Total up to	100.00	100.00	100.00

Claims

1. A catalytic cracking process for increasing propylene production, the process comprising:

separating the resulting polymerization product to give C₁₂Olefin, and C₁₂The olefin is introduced into the catalytic cracking reactor to perform catalytic cracking reaction and/or introduced into other catalytic cracking devices to perform catalytic cracking reaction.

2. The method of claim 1, wherein the conditions of the polymerization reaction include: the temperature is 50-550 ℃, the pressure is 0.2-8.0 MPa, and the weight hourly space velocity is 0.1-10 hours^-1，C₅Olefins with C₇The weight ratio of the olefin is 1: (0.7-3);

3. The method of claim 2, wherein the phosphoric acid catalyst is one or more of a catalyst in which phosphoric acid is supported on diatomaceous earth, a catalyst in which phosphoric acid is supported on activated carbon, a catalyst in which phosphoric acid is soaked with silica sand, a catalyst in which phosphoric acid is supported on silica gel, and a catalyst in which copper pyrophosphate is supported on silica gel;

4. The process of claim 1 wherein C in the laminated product is based on the weight of the laminated product₁₂The content of olefin is more than 40 wt%;

to contain C₅Fraction of olefins and C₇Based on the total weight of the fraction containing olefins, said fraction containing C₅Fraction of olefins and C₇In the olefin distillation section, the sulfur content is not more than 20 micrograms/gram, the basic nitride content is not more than 0.6 micrograms/gram, the water content is 600-1800 micrograms/gram, and the diene content is not more than 200 micrograms/gram.

5. A process according to claim 4, wherein C in the superimposed product is based on the weight of the superimposed product₁₂The content of olefin is 70 wt% or more.

6. A process according to claim 5, wherein C in the superimposed product is based on the weight of the superimposed product₁₂The content of olefin is 80 wt% or more.

7. The method of claim 1, further comprising: will separate out C₁₂The polymerization product of the olefin is returned to the polymerization reactor for the polymerization reaction.

8. The process according to claim 1, wherein C is introduced into the catalytic cracking reactor for catalytic cracking reactions and/or into other catalytic cracking units₁₂The olefin accounts for 1-35 wt% of the raw oil.

9. The method of claim 1, wherein the raw oil is a petroleum hydrocarbon and/or other mineral oil, wherein the petroleum hydrocarbon is selected from one or more of a mixture of vacuum gas oil, atmospheric gas oil, coker gas oil, deasphalted oil, vacuum residue, atmospheric residue, and heavy aromatic raffinate oil; the other mineral oil is one or more selected from coal liquefied oil, oil sand oil and shale oil.

10. The process of claim 1 wherein the catalytic cracking catalyst comprises from 1 to 50 wt% of a zeolite selected from the group consisting of medium pore zeolites selected from the group consisting of ZSM series zeolites and/or ZRP zeolites, from 5 to 99 wt% of an inorganic oxide, and from 0 to 70 wt% of a clay, based on the weight of the catalytic cracking catalyst, and the large pore zeolites selected from one or more of rare earth Y, rare earth hydrogen Y, ultrastable Y, and high silica Y.

11. The process of claim 1, wherein the catalytic cracking reactor and the other catalytic cracking unit are independently selected from one or two of a riser, a constant linear velocity fluidized bed, a constant diameter fluidized bed, an ascending transport line and a descending transport line in series combination, wherein the riser is a constant diameter riser reactor or a variable diameter fluidized bed reactor.

12. The method of claim 11, wherein the variable diameter fluidized bed reactor comprises two reaction zones, and the conditions of the first reaction zone comprise: the reaction temperature is 510-650 ℃, the reaction time is 0.05-1.0 second, and the weight ratio of the catalyst to the raw oil is (3-15): 1, the weight ratio of the water vapor to the raw oil is (0.03-0.3): 1;

13. The method of claim 11, wherein the variable diameter fluidized bed reactor comprises two reaction zones, and the conditions of the first reaction zone comprise: the reaction temperature is 520-600 ℃, the reaction time is 0.1-1 second, and the weight ratio of the catalyst to the raw oil is (4-12): 1, the weight ratio of the water vapor to the raw oil is (0.05-0.2): 1;

14. A catalytic cracking system for increasing the yield of propylene comprises a catalytic cracking reactor, a regenerator, an oil separation device, a product fractionation device, an olefin separation device, a superposition reactor, a rectifying tower and optional other catalytic cracking devices;

the oil outlet of the catalytic cracking reactor is communicated with the oil inlet of the oil separating device, the reaction product outlet of the oil separating device is communicated with the reaction product inlet of the product fractionating device, and the C of the product fractionating device₅Cut section outlet and C₇The outlet of the fraction section is communicated with the inlet of the fraction section of the olefin separation device, the olefin outlet of the olefin separation device is communicated with the raw material inlet of the polymerization reactor, the outlet of the polymerization product of the polymerization reactor is communicated with the oil gas inlet of the rectifying tower, and the C of the rectifying tower₁₂Olefin outlet and C of the catalytic cracking reactor₁₂The olefin inlet and/or the raw oil inlet of the other catalytic cracking device are communicated, and the catalyst inlet of the catalytic cracking reactor is communicated with the catalyst inlet of the other catalytic cracking deviceAnd the catalyst inlet of the regenerator is communicated with the catalyst outlet of the oil agent separation device.