阅读说明：本技术 一种生产清洁汽油的催化裂化方法 (Catalytic cracking method for producing clean gasoline ) 是由 朱金泉 高永灿 谢朝钢 崔琰 杨轶男 于 2018-05-30 设计创作，主要内容包括：本发明涉及一种生产清洁汽油的催化裂化方法,该方法包括：(1)、将重质烃类原料与第一催化裂化催化剂进行第一催化裂化反应；(2)、将甲醇和第一轻质烃类与第二催化裂化催化剂进行第二催化裂化反应；(3)、将步骤(2)所得第二反应油气和半待生催化剂与第二轻质烃类一起进行第三催化裂化反应；(4)、将步骤(1)所得第一反应油气和步骤(3)所得第三反应油气进行分离；(5)、将至少部分所述第一分离产物作为所述第一轻质烃类返回进行所述第二催化裂化反应,和/或将至少部分所述第二分离产物作为所述第二轻质烃类返回进行所述第三催化裂化反应。本发明方法所产汽油辛烷值高,收率高,烯烃、芳烃和苯的含量低。(The invention relates to a catalytic cracking method for producing clean gasoline, which comprises the following steps: (1) carrying out a first catalytic cracking reaction on the heavy hydrocarbon raw material and a first catalytic cracking catalyst; (2) carrying out a second catalytic cracking reaction on the methanol, the first light hydrocarbon and a second catalytic cracking catalyst; (3) carrying out a third catalytic cracking reaction on the second reaction oil gas obtained in the step (2), the semi-spent catalyst and second light hydrocarbon together; (4) separating the first reaction oil gas obtained in the step (1) and the third reaction oil gas obtained in the step (3); (5) at least part of the first separated product is returned as the first light hydrocarbon to carry out the second catalytic cracking reaction, and/or at least part of the second separated product is returned as the second light hydrocarbon to carry out the third catalytic cracking reaction. The gasoline produced by the method has high octane number, high yield and low contents of olefin, aromatic hydrocarbon and benzene.)

1. a catalytic cracking process for producing clean gasoline, the process comprising:

(1) Contacting the heavy hydrocarbon raw material with a first catalytic cracking catalyst in a first catalytic cracking reactor and carrying out a first catalytic cracking reaction to obtain first reaction oil gas and a first catalyst to be generated;

(2) Injecting methanol and first light hydrocarbon into a second catalytic cracking reactor to contact with a second catalytic cracking catalyst and carrying out a second catalytic cracking reaction to obtain second reaction oil gas and a semi-spent catalyst; wherein the distillation range of the first light hydrocarbon is between 8 and 88 ℃;

(3) Introducing the obtained second reaction oil gas and the semi-spent catalyst into a third catalytic cracking reactor to carry out a third catalytic cracking reaction together with second light hydrocarbons injected into the third catalytic cracking reactor to obtain a third reaction oil gas and a second spent catalyst; wherein the distillation range of the second light hydrocarbon is between 41 and 221 ℃;

(4) separating the obtained first reaction oil gas and the third reaction oil gas to at least obtain gasoline, a first separation product with a distillation range meeting the requirement of first light hydrocarbons and/or a second separation product with a distillation range meeting the requirement of second light hydrocarbons;

(5) Returning at least part of the first separated product as the first light hydrocarbon to perform the second catalytic cracking reaction, and/or returning at least part of the second separated product as the second light hydrocarbon to perform the third catalytic cracking reaction;

(6) And regenerating the first spent catalyst and the second spent catalyst, wherein the regenerated catalyst is used as the first catalytic cracking catalyst and the second catalytic cracking catalyst.

2. The process of claim 1, wherein the first light hydrocarbon has a boiling range between 9-60 ℃ and the second light hydrocarbon has a boiling range between 60-195 ℃.

3. The process of claim 1, wherein the olefin content of the first light hydrocarbon is from 30 to 100 wt%.

4. The process of claim 1, wherein the olefin content of the first light hydrocarbon is from 45 to 90 wt%.

5. The method of claim 1, wherein the first and second light hydrocarbons each independently comprise C4 hydrocarbons and/or a gasoline fraction.

6. The process according to claim 1, wherein the heavy hydrocarbon feedstock is at least one selected from the group consisting of petroleum hydrocarbon oils, synthetic oils, coal liquefaction oils, oil sand oils and shale oils.

7. the process of claim 1, wherein the heavy hydrocarbon feedstock is at least one selected from the group consisting of atmospheric gas oil, vacuum gas oil, coker gas oil, deasphalted oil, hydrogenated tail oil, atmospheric residue, vacuum residue, and crude oil.

8. The process of claim 1, wherein the weight ratio of the first light hydrocarbons to heavy hydrocarbon feedstock is (0.01-0.4): 1, the methanol accounts for 5-50 wt% of the total weight of the methanol and the first light hydrocarbon;

The weight ratio of the second light hydrocarbon to the heavy hydrocarbon raw material is (0.01-0.4): 1.

9. The process of claim 1, wherein the weight ratio of the first light hydrocarbons to heavy hydrocarbon feedstock is (0.05-0.2): 1; the methanol accounts for 25-50 wt% of the total weight of the methanol and the first light hydrocarbon;

The weight ratio of the second light hydrocarbon to the heavy hydrocarbon raw material is (0.05-0.2): 1.

10. The process of claim 1, wherein methanol and the first light hydrocarbon are mixed and injected together into the second catalytic cracking reactor.

11. The process of claim 1, wherein the first, second and third catalytic cracking reactors are each independently selected from at least one of a riser reactor, a downer reactor, a fluidized bed reactor, a riser and downer composite reactor, a riser and fluidized bed composite reactor, a downer and fluidized bed composite reactor, and a fluidized bed reactor selected from at least one of a fixed fluidized bed reactor, a bulk fluidized bed reactor, a bubble bed reactor, a turbulent bed reactor, a fast bed reactor, a transport bed reactor, and a dense phase fluidized bed.

12. The process of claim 1, wherein the first catalytic cracking reactor is a riser reactor and the conditions of the first catalytic cracking reaction comprise: the reaction temperature is 480-700 ℃, the reaction time is 0.5-10 seconds, and the weight ratio of the catalyst to the oil is (5-40): 1, the weight ratio of water to oil is (0.05-1): 1;

The second catalytic cracking reactor is a riser reactor, and the conditions of the second catalytic cracking reaction comprise: the reaction temperature is 480-650 ℃, the reaction time is 0.5-10 seconds, and the weight ratio of the catalyst to the oil is (5-40): 1, the weight ratio of water to oil is (0.05-1): 1;

The third catalytic cracking reactor is a fluidized bed reactor, and the conditions of the third catalytic cracking reaction comprise that the reaction temperature is 300-600 ℃, the weight hourly space velocity is 0.5-30 h ^-1, the weight ratio of water to oil is (0.05-1) to 1, and the absolute reaction pressure is 0.1-1.5 MPa.

13. The process of claim 12, wherein the conditions of the first catalytic cracking reaction comprise: the reaction temperature is 510-550 ℃, the reaction time is 1-5 seconds, and the weight ratio of the catalyst to the oil is (7-20): 1, the weight ratio of water to oil is (0.1-0.6): 1;

The conditions of the second catalytic cracking reaction include: the reaction temperature is 440-550 ℃, the reaction time is 1-5 seconds, and the weight ratio of the catalyst to the oil is (7-20): 1, the weight ratio of water to oil is (0.08-0.6): 1;

The conditions of the third catalytic cracking reaction comprise that the reaction temperature is 380-520 ℃, the weight hourly space velocity is 1.5-16 h ^-1, the weight ratio of water to oil is (0.08-0.6): 1, and the absolute reaction pressure is 0.1-0.51 MPa.

14. The process according to claim 1, wherein the first catalytic cracking catalyst comprises 10 to 50 wt% of a zeolite, at least one selected from the group consisting of rare earth-containing or non-containing Y zeolite, HY zeolite, USY zeolite, ZSM-5 series zeolite, high-silica zeolite having a pentasil structure and Beta zeolite, 5 to 90 wt% of an inorganic oxide and 0 to 70 wt% of clay, on a dry basis and based on the weight of the first catalytic cracking catalyst;

the second catalytic cracking catalyst comprises 10 to 50 wt% of zeolite, which is at least one selected from the group consisting of rare earth-containing or non-containing Y zeolite, HY zeolite, USY zeolite, ZSM-5 series zeolite, high-silica zeolite having a pentasil structure, and Beta zeolite, 5 to 90 wt% of an inorganic oxide, and 0 to 70 wt% of clay, on a dry basis and based on the weight of the second catalytic cracking catalyst.

Technical Field

The invention relates to a catalytic cracking method for producing clean gasoline.

background

The national common people's republic of China is officially implemented in the automotive gasoline standard GB17930-2016, the technical requirements on the automotive gasoline are stricter, and the requirements are that the olefin content is not more than 15 percent (volume fraction), the aromatic hydrocarbon content is not more than 35 percent (volume fraction), and the benzene content is not more than 0.8 percent (volume fraction). As crude oil becomes heavier and the supply of light petroleum hydrocarbons is limited, the technical route for preparing high-standard gasoline by strengthening deep catalytic cracking reaction of heavy hydrocarbons by using the traditional heavy oil catalytic cracking technology as a platform and using cheap heavy oil as a raw material has high economical efficiency, but the high-octane gasoline obtained by the method hardly meets the requirements of the current or future automotive gasoline standard on the content of olefin or aromatic hydrocarbon, and if the content of olefin, benzene and aromatic hydrocarbon is reduced by modifying the gasoline by the traditional catalytic conversion method, the octane number of the gasoline is greatly reduced.

Chinese patent CN 101210190A discloses a method for preparing low-carbon olefin and gasoline by co-feeding heavy petroleum hydrocarbon and methanol, which is carried out on a fluidized catalytic cracking device on a composite molecular sieve catalyst by taking the heavy petroleum hydrocarbon and the methanol as raw materials, wherein the operation temperature of the process is 480-600 ℃, the system pressure is 0.01-0.51 MPa, the weight hourly space velocity is 1.01-20.1 h ^-1, the catalyst-to-oil ratio is 1.0-20.1, the methanol accounts for 1.5-50 w% of the raw material oil, the water injection accounts for 5-50% of the raw material oil, the composite molecular sieve catalyst contains a shape-selective molecular sieve and a large-size molecular sieve with the weight ratio of 1: 0.1-1.0, when the heavy petroleum hydrocarbon and the methanol are fed into the same reactor, the low-carbon olefin yield is increased, the olefin content in the gasoline is reduced, the aromatic hydrocarbon content in the gasoline is increased, the aromatic hydrocarbon content reaches 70 wt%, but the method does not accord with the requirements of GB17930-2013 and the stricter limit on the aromatic hydrocarbon content in the gasoline in the future.

Chinese patent CN101892067A discloses a method for improving propylene yield and selectivity by promoting catalytic cracking of heavy oil, which is mainly characterized in that during the reaction process, one or more of small amount of small molecular alcohols such as methanol, ethanol, propanol, butanol, etc. is fed together with heavy oil, thereby obviously promoting the conversion rate of heavy oil and improving the yield of liquefied gas and propylene. Compared with other heavy oil catalytic cracking or catalytic cracking yield-increasing or propylene-increasing technologies, the method introduces a small amount of alcohol to improve the yield and selectivity of heavy oil catalytic cracking propylene, and has the advantages of convenient implementation, obvious effect, remarkable economic benefit and the like. The method mainly produces more low-carbon olefins, has low gasoline yield and does not disclose the properties of gasoline products.

Another kind of technology is that gasoline is directly prepared from methanol, i.e. MTG process, the catalyst used is mainly a ZSM-5 containing molecular sieve catalyst, where the content of aromatics in gasoline is > 30% and the content of olefins is > 12%, USP3894104 discloses a technology for preparing gasoline from methanol, and the content of aromatics in C ₅ ⁺ gasoline is up to over 50%.

In summary, from the technology disclosed at present, both the direct catalytic cracking of heavy hydrocarbon feedstock to produce gasoline (FCC technology) and the catalytic conversion of methanol to produce gasoline (MTG technology) are faced with the technical problem of high olefin content or high aromatic hydrocarbon content in gasoline. The prior published literature of methanol and heavy oil coupled feeding has not published relevant reports for preparing clean gasoline. In the prior art, the difficulty of directly producing high-octane clean gasoline is increasing when the automobile gasoline standard GB17930-2016 is faced and the future stricter automobile gasoline standard is met.

Disclosure of Invention

The invention aims to provide a catalytic cracking method for producing clean gasoline, and the gasoline produced by the method has high octane number, high yield and low contents of olefin, aromatic hydrocarbon and benzene.

In order to achieve the above object, the present invention provides a catalytic cracking process for producing clean gasoline, comprising:

(1) Contacting the heavy hydrocarbon raw material with a first catalytic cracking catalyst in a first catalytic cracking reactor and carrying out a first catalytic cracking reaction to obtain first reaction oil gas and a first catalyst to be generated;

(2) Injecting methanol and first light hydrocarbon into a second catalytic cracking reactor to contact with a second catalytic cracking catalyst and carrying out a second catalytic cracking reaction to obtain second reaction oil gas and a semi-spent catalyst; wherein the distillation range of the first light hydrocarbon is between 8 and 88 ℃;

(3) Introducing the obtained second reaction oil gas and the semi-spent catalyst into a third catalytic cracking reactor to carry out a third catalytic cracking reaction together with second light hydrocarbons injected into the third catalytic cracking reactor to obtain a third reaction oil gas and a second spent catalyst; wherein the distillation range of the second light hydrocarbon is between 41 and 221 ℃;

(4) Separating the obtained first reaction oil gas and the third reaction oil gas to at least obtain gasoline, a first separation product with a distillation range meeting the requirement of first light hydrocarbons and/or a second separation product with a distillation range meeting the requirement of second light hydrocarbons;

(5) returning at least part of the first separated product as the first light hydrocarbon to perform the second catalytic cracking reaction, and/or returning at least part of the second separated product as the second light hydrocarbon to perform the third catalytic cracking reaction;

(6) And regenerating the first spent catalyst and the second spent catalyst, wherein the regenerated catalyst is used as the first catalytic cracking catalyst and the second catalytic cracking catalyst.

optionally, the distillation range of the first light hydrocarbon is between 9 and 60 ℃, and the distillation range of the second light hydrocarbon is between 60 and 195 ℃.

Optionally, the olefin content of the first light hydrocarbon is from 30 to 100 wt%.

optionally, the olefin content of the first light hydrocarbon is 45 to 90 wt%.

optionally, the first and second light hydrocarbons each independently comprise C4 hydrocarbons and/or a gasoline fraction.

optionally, the heavy hydrocarbon feedstock is at least one selected from the group consisting of petroleum hydrocarbon oil, synthetic oil, coal liquefaction oil, oil sand oil, and shale oil.

Optionally, the heavy hydrocarbon feedstock is at least one selected from the group consisting of atmospheric gas oil, vacuum gas oil, coker gas oil, deasphalted oil, hydrogenated tail oil, atmospheric residue, vacuum residue, and crude oil.

optionally, the weight ratio of the first light hydrocarbons to the heavy hydrocarbon feedstock is (0.01-0.4): 1, the methanol accounts for 5-50 wt% of the total weight of the methanol and the first light hydrocarbon;

The weight ratio of the second light hydrocarbon to the heavy hydrocarbon raw material is (0.01-0.4): 1.

Optionally, the weight ratio of the first light hydrocarbons to the heavy hydrocarbon feedstock is (0.05-0.2): 1; the methanol accounts for 25-50 wt% of the total weight of the methanol and the first light hydrocarbon;

The weight ratio of the second light hydrocarbon to the heavy hydrocarbon raw material is (0.05-0.2): 1.

Optionally, the methanol and the first light hydrocarbon are mixed and then injected into the second catalytic cracking reactor together.

optionally, the first catalytic cracking reactor, the second catalytic cracking reactor, and the third catalytic cracking reactor are each independently selected from at least one of a riser reactor, a downer reactor, a fluidized bed reactor, a composite reactor of a riser and a downer, a composite reactor of a riser and a fluidized bed, and a composite reactor of a downer and a fluidized bed, and the fluidized bed reactor is selected from at least one of a fixed fluidized bed reactor, a bulk fluidized bed reactor, a bubbling bed reactor, a turbulent bed reactor, a fast bed reactor, a transport bed reactor, and a dense-phase fluidized bed.

Optionally, the first catalytic cracking reactor is a riser reactor, and the conditions of the first catalytic cracking reaction include: the reaction temperature is 480-700 ℃, the reaction time is 0.5-10 seconds, and the weight ratio of the catalyst to the oil is (5-40): 1, the weight ratio of water to oil is (0.05-1): 1;

The second catalytic cracking reactor is a riser reactor, and the conditions of the second catalytic cracking reaction comprise: the reaction temperature is 480-650 ℃, the reaction time is 0.5-10 seconds, and the weight ratio of the catalyst to the oil is (5-40): 1, the weight ratio of water to oil is (0.05-1): 1;

The third catalytic cracking reactor is a fluidized bed reactor, and the conditions of the third catalytic cracking reaction comprise that the reaction temperature is 300-600 ℃, the weight hourly space velocity is 0.5-30 h ^-1, the weight ratio of water to oil is (0.05-1) to 1, and the absolute reaction pressure is 0.1-1.5 MPa.

Optionally, the conditions of the first catalytic cracking reaction include: the reaction temperature is 510-550 ℃, the reaction time is 1-5 seconds, and the weight ratio of the catalyst to the oil is (7-20): 1, the weight ratio of water to oil is (0.1-0.6): 1;

The conditions of the second catalytic cracking reaction include: the reaction temperature is 440-550 ℃, the reaction time is 1-5 seconds, and the weight ratio of the catalyst to the oil is (7-20): 1, the weight ratio of water to oil is (0.08-0.6): 1;

the conditions of the third catalytic cracking reaction comprise that the reaction temperature is 380-520 ℃, the weight hourly space velocity is 1.5-16 h ^-1, the weight ratio of water to oil is (0.08-0.6): 1, and the absolute reaction pressure is 0.1-0.51 MPa.

Optionally, the first catalytic cracking catalyst comprises, on a dry basis and based on the weight of the first catalytic cracking catalyst, 10 to 50 wt% of a zeolite, 5 to 90 wt% of an inorganic oxide and 0 to 70 wt% of a clay, the zeolite being at least one selected from the group consisting of rare earth-containing or non-containing Y zeolite, HY zeolite, USY zeolite, ZSM-5 series zeolite, high-silica zeolite having a pentasil structure and Beta zeolite;

The second catalytic cracking catalyst comprises 10 to 50 wt% of zeolite, which is at least one selected from the group consisting of rare earth-containing or non-containing Y zeolite, HY zeolite, USY zeolite, ZSM-5 series zeolite, high-silica zeolite having a pentasil structure, and Beta zeolite, 5 to 90 wt% of an inorganic oxide, and 0 to 70 wt% of clay, on a dry basis and based on the weight of the second catalytic cracking catalyst.

by adopting the method, the yield of the product gasoline is increased, the olefin content and the benzene content in the product gasoline are reduced, the contents of multi-branched isoparaffin and polymethylbenzene are increased, the quality of the gasoline is improved, the research octane number is over 95, and the technical indexes that the olefin content is not more than 15 percent (volume fraction), the aromatic hydrocarbon content is not more than 35 percent (volume fraction) and the benzene content is not more than 0.8 percent (volume fraction) are met.

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 is a schematic diagram of an embodiment of a system used in the method of the present invention.

Description of the reference numerals

1 first catalytic cracking reactor 2 second catalytic cracking reactor 3 third catalytic cracking reactor

6 settler 7 stripper 9 regenerator

10 separator 11 line 12 line

17 line 20 line 21 line

22 line 23 line 24 line

25 line 26 line 27 line

28 line 29 line 41 line

42 line 43 line 44 line

47 line 51 line 52 line

90 line 91 line 100 external heat exchanger

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

the invention provides a catalytic cracking method for producing clean gasoline, which comprises the following steps: (1) contacting the heavy hydrocarbon raw material with a first catalytic cracking catalyst in a first catalytic cracking reactor and carrying out a first catalytic cracking reaction to obtain first reaction oil gas and a first catalyst to be generated; (2) injecting methanol and first light hydrocarbon into a second catalytic cracking reactor to contact with a second catalytic cracking catalyst and carrying out a second catalytic cracking reaction to obtain second reaction oil gas and a semi-spent catalyst; wherein the distillation range of the first light hydrocarbon is between 8 and 88 ℃; (3) introducing the obtained second reaction oil gas and the semi-spent catalyst into a third catalytic cracking reactor to carry out a third catalytic cracking reaction together with second light hydrocarbons injected into the third catalytic cracking reactor to obtain a third reaction oil gas and a second spent catalyst; wherein the distillation range of the second light hydrocarbon is between 41 and 221 ℃; (4) separating the obtained first reaction oil gas and the third reaction oil gas to at least obtain gasoline, a first separation product with a distillation range meeting the requirement of first light hydrocarbons and/or a second separation product with a distillation range meeting the requirement of second light hydrocarbons; (5) returning at least part of the first separated product as the first light hydrocarbon to perform the second catalytic cracking reaction, and/or returning at least part of the second separated product as the second light hydrocarbon to perform the third catalytic cracking reaction; (6) and regenerating the first spent catalyst and the second spent catalyst, wherein the regenerated catalyst is used as the first catalytic cracking catalyst and the second catalytic cracking catalyst.

Through experimental research, the inventor of the invention finds that under proper reaction conditions, the yield of the product gasoline is increased, the property of the gasoline is changed, the olefin content in the gasoline is reduced, and the content of non-aromatic high-octane component is increased in light hydrocarbons obtained by catalytic cracking of heavy hydrocarbon raw materials after a certain amount of methanol is added. Compared with the technical scheme of independent recycling of light hydrocarbons or co-feeding of methanol and heavy hydrocarbon raw materials in the prior art, the technical scheme of the invention has better reaction effect and better quality of gasoline products. The main reasons for this are: (1) the method provided by the invention is characterized in that an intermediate product obtained by cracking reaction of a heavy hydrocarbon raw material is divided into a first light hydrocarbon and a second light hydrocarbon according to the property, and the first light hydrocarbon and the second light hydrocarbon circulate in different reaction stages according to the composition characteristics and the reaction mechanism and react with methanol in a certain proportion. (2) In the invention, methanol molecules are introduced to react with a first light hydrocarbon and a second light hydrocarbon together, wherein C4-C5 olefin rich in the first light hydrocarbon and methyl micromolecule groups released by methanol undergo transalkylation reaction and hydrogen transfer reaction, so that the number of carbon atoms of hydrocarbon molecules in the light hydrocarbons is increased, the number of branched chains is increased, and the light hydrocarbons are converted into multi-branched isomeric hydrocarbons with high octane number of above C5. Since the first light hydrocarbon is a shorter molecule of C4-C5, 2 or more molecules of methanol are required to react with it to convert it to a multi-branched isoparaffin. (3) And benzene and single-branched-chain hydrocarbons rich in the second light hydrocarbons react with methyl small molecular groups in the methanol, so that the carbon number of the light hydrocarbons is increased, the number of branched chains is increased, and the light hydrocarbons are converted into isomeric hydrocarbons with high octane number of above C7, polymethylbenzene and the like. Since the second light hydrocarbon is C6 and above, 1 methanol molecule is needed to react with it to convert into isoparaffin and polymethylbenzene above C7. (4) According to the difference of reaction mechanisms, the first light hydrocarbon needs to be subjected to catalytic reaction preferentially with a large amount of methanol to be converted effectively, the required reaction time is longer, the catalytic cracking time of the second light hydrocarbon is shorter, and less methanol is required to participate in the reaction. (5) Therefore, by adopting the method of the invention, the yield of the product gasoline is increased, the olefin content and the benzene content in the product gasoline are reduced, the content of multi-branched isoparaffin and polymethyl benzene is increased, and the quality of the gasoline is improved. For example, a molecule of 2-methyl-2-butene in light gasoline reacts with a molecule of methanol to produce 2, 3-dimethyl-2-butene, which further reacts by hydrogen transfer to produce 2, 3-dimethylbutane. The octane number of 2, 3-dimethylbutane is as high as 103.6. Specifically, according to the method provided by the invention, the yield of the gasoline is increased, the research octane number is more than 95, and the technical indexes that the olefin content is not more than 15% (volume fraction), the aromatic hydrocarbon content is not more than 35% (volume fraction) and the benzene content is not more than 0.8% (volume fraction) are met.

In the present invention, the first light hydrocarbon may have a boiling range of 8 to 88 ℃, preferably 9 to 60 ℃, the olefin content of 30 to 100% by weight, preferably 45 to 90% by weight, and the second light hydrocarbon may have a boiling range of 41 to 221 ℃, preferably 60 to 195 ℃. The first light hydrocarbon and the second light hydrocarbon can respectively and independently comprise C4 hydrocarbon and/or gasoline fraction, and the C4 hydrocarbon fraction and the gasoline fraction can be produced by the method and can also be produced by other devices.

According to the present invention, the heavy hydrocarbon feedstock may be at least one selected from the group consisting of petroleum hydrocarbon oils, synthetic oils, coal liquefaction oils, oil sand oils, and shale oils. Preferably, the heavy hydrocarbon feedstock is selected from at least one of atmospheric gas oil, vacuum gas oil, coker gas oil, deasphalted oil, hydrogenated tail oil, atmospheric residue, vacuum residue, and crude oil. The synthetic oil can be distillate oil obtained by Fischer-Tropsch (F-T) synthesis of coal and/or natural gas.

according to the invention, the feed weight ratio of the first light hydrocarbon to the heavy hydrocarbon feedstock may be (0.01-0.4): 1, preferably (0.05-0.2): 1; the methanol accounts for 5 to 50 wt%, preferably 25 to 50 wt% of the total weight of the methanol and the first light hydrocarbon; the weight ratio of the second light hydrocarbon to the heavy hydrocarbon feedstock may be (0.01-0.4): 1, preferably (0.05-0.2): 1.

according to the present invention, methanol and the first light hydrocarbon may be mixed and then injected into the second catalytic cracking reactor, or methanol may be injected into the second catalytic cracking reactor upstream or downstream of the injection position of the first light hydrocarbon, preferably, methanol and the first light hydrocarbon are mixed and then injected into the second catalytic cracking reactor, according to the flow direction of the reaction material.

According to the present invention, the catalytic cracking reactor is well known to those skilled in the art, for example, the first catalytic cracking reactor, the second catalytic cracking reactor and the third catalytic cracking reactor may each be independently selected from at least one of a riser reactor, a downer reactor and a fluidized bed reactor, preferably at least one of a riser reactor, a downer reactor, a fluidized bed reactor, a riser and downer composite reactor, a riser and fluidized bed composite reactor, a downer and fluidized bed composite reactor, and the third catalytic cracking reactor is preferably a fluidized bed reactor or a composite reactor comprising at least one fluidized bed reactor, which may be selected from a fixed fluidized bed reactor, a bulk fluidized bed reactor, a bubbling bed reactor, a turbulent fluidized bed reactor, a fast bed reactor, a fluidized bed reactor, At least one of a transport bed reactor and a dense phase fluidized bed. The fluidized bed reactor can be a fluidized bed structure with equal diameter or a fluidized bed structure with variable diameter, and the riser reactor and the downer reactor can be a riser reactor and a downer reactor with equal diameter or various riser reactors and downer reactors with variable diameter.

^{-1 -1}In a preferred embodiment, the first catalytic cracking reactor is a riser reactor, the first catalytic cracking reaction conditions comprise that the reaction temperature (at the outlet of the reactor) is 480-700 ℃, preferably 500-600 ℃, the reaction time is 0.5-10 seconds, preferably 1-5 seconds, the catalyst-oil weight ratio is (5-40): 1, preferably (7-20): 1, the water-oil weight ratio (the weight ratio of atomized steam to heavy hydrocarbon raw material) is (0.05-1): 1, preferably (0.1-0.6): 1, the second catalytic cracking reactor is a riser reactor, the second catalytic cracking reaction conditions comprise that the reaction temperature (at the outlet of the reactor) is 480-650 ℃, preferably 500-600 ℃, the reaction time is 0.5-10 seconds, preferably 1-5 seconds, the catalyst-oil weight ratio (the weight ratio of second catalytic cracking catalyst to first light hydrocarbon) is (5-40): 1, preferably (7-20): 1-10 seconds, preferably 1-5 seconds, the catalyst-oil weight ratio of atomized steam to first hydrocarbon raw material) is 0.05-1, preferably 0.05-10 seconds, preferably 0.05-1, preferably 0.5-1, the second catalytic cracking reactor is a riser reactor, the second catalytic cracking reactor (the reactor outlet of 480: (the reactor-10) is preferably 0.05-10) is a riser reactor, the catalyst-10-5 seconds, the catalyst-10-5-10-5-10-5-10-0, the catalyst-10-5-10-5-0, the second-10-5-10-5-10-.

According to the present invention, the catalytic cracking catalyst is well known to those skilled in the art, and for example, the first catalytic cracking catalyst comprises, on a dry basis and based on the weight of the first catalytic cracking catalyst, 10 to 50% by weight of a zeolite, which is at least one selected from the group consisting of rare earth-containing or non-containing Y zeolite, HY zeolite, USY zeolite, ZSM-5 series zeolite, high-silica zeolite having a pentasil structure and Beta zeolite, 5 to 90% by weight of an inorganic oxide and 0 to 70% by weight of clay; the second catalytic cracking catalyst comprises 10 to 50 wt% of zeolite, which is at least one selected from the group consisting of rare earth-containing or non-containing Y zeolite, HY zeolite, USY zeolite, ZSM-5 series zeolite, high-silica zeolite having a pentasil structure, and Beta zeolite, 5 to 90 wt% of an inorganic oxide, and 0 to 70 wt% of clay, on a dry basis and based on the weight of the second catalytic cracking catalyst. The first catalytic cracking catalyst and the second catalytic cracking catalyst may be the same or different, preferably the same.

in one embodiment, in the settler, the reaction oil gas and the carbon deposit catalyst to be regenerated are separated, the separated reaction oil gas is introduced into a subsequent separation device, and is further separated to obtain gasoline, and also can be separated to obtain products such as dry gas, liquefied gas, gasoline, diesel oil, heavy oil and the like, and at least part of the first separation product and the second separation product are separated to be used as the first light hydrocarbon and the second light hydrocarbon and are returned to the reactor for recycling.

the method according to the invention is further illustrated with reference to fig. 1, but the invention is not limited thereto:

As shown in fig. 1, the first catalytic cracking reactor 1 is a riser reactor, the second catalytic cracking reactor 2 is a riser reactor, the third catalytic cracking reactor 3 is a fluidized bed reactor, and the outlet of the second catalytic cracking reactor 2 is coaxially connected in series with the bottom of the third catalytic cracking reactor 3. The hot regenerated catalyst from the regenerator 9 enters the bottom of the first catalytic cracking reactor 1 via regenerated catalyst transfer line 11 and is accelerated to flow upward by the pre-lift medium injected via line 51. The preheated heavy hydrocarbon raw material is mixed with the atomized steam from the pipeline 41 through the pipeline 21, and then is injected into the first catalytic cracking reactor 1 to contact with the regenerated catalyst to carry out the first catalytic cracking reaction. The mixture of the first reaction oil gas and the first catalyst to be generated in the first catalytic cracking reactor 1 is quickly separated by a quick separation device at an outlet, and the first catalyst to be generated with carbon deposit is introduced into a stripper 7. The separated reaction oil gas (the startup stage only comprises the first reaction oil gas from the first catalytic cracking reactor, and the continuous cycle operation process comprises the reaction oil gas from the first catalytic cracking reactor and the third catalytic cracking reactor) is sent to a subsequent separation device 10 through a settler 6 and a pipeline 20 at the top of the settler for continuous separation, and products such as dry gas, liquefied gas, gasoline, diesel oil, heavy oil and the like are obtained after separation (respectively led out through pipelines 25, 26, 27, 28 and 29), and simultaneously, the first separation product for recycling can be further separated to be used as a first light hydrocarbon (led out through a pipeline 23) and the second separation product as a second light hydrocarbon (led out through a pipeline 24). The first light hydrocarbon is injected into the second catalytic cracking reactor 2 via line 23 after being mixed with the atomized steam from line 43 to contact the regenerated catalyst lifted by the pre-lift gas from line 12 and injected via line 52 and undergo a second catalytic cracking reaction. Methanol injection can be done in a variety of ways: methanol can be fed via line 23 with the mist steam from line 43 in a ratio of (0.05-1): 1, namely, the methanol and the first light hydrocarbon are mixed and then injected into the second catalytic cracking reactor 2; methanol can also be fed via line 22 with the atomized vapor from line 42 in the following (0.05-1): 1, and the mixture is injected into a second catalytic cracking reactor 2, wherein the injection position can be positioned at the upstream and downstream of the injection point of the first light hydrocarbon. The mixture of the second reaction oil gas and the semi-spent catalyst in the second catalytic cracking reactor 2 is further introduced into a third catalytic cracking reactor 3 through the outlet of the second catalytic cracking reactor 2 for continuous reaction. The second light hydrocarbon is contacted with the mist steam from line 44 via line 24 in the ratio of (0.05-1): 1, then injecting the mixture into the bottom of a third catalytic cracking reactor 3 and carrying out a third catalytic cracking reaction with the oil mixture in the second catalytic cracking reactor 2. The third reaction oil gas and the second spent catalyst in the third catalytic cracking reactor 3 are separated and separated through an annular gap between the wall of the third catalytic cracking reactor 3 and the top cap, and the spent catalyst is introduced into a stripper 7. The separated spent catalyst with carbon deposit after reaction enters a stripper 7, stripping steam is injected into the stripper 7 through a pipeline 47 and contacts with the spent catalyst in a countercurrent manner, and reaction oil gas carried by the spent catalyst is stripped as clean as possible. The stripped spent catalyst is sent into a regenerator 9 through a spent agent conveying pipeline 17, air is injected into the regenerator 9 through a pipeline 90, the catalyst is contacted with the heated air in the regenerator and regenerated at the temperature of 600-800 ℃, and the temperature of the regenerator is controlled by an external heat exchanger 100. The regeneration flue gas is led out through a line 91. The regenerated catalyst is returned to the first catalytic cracking reactor and the second catalytic cracking reactor for recycling through the regenerant conveying pipelines 11 and 12.

The process provided by the present invention is further illustrated below by way of examples, but the invention is not limited thereto.