CN112538384B - Hydrotreating-catalytic cracking combined process method for increasing yield of isobutane and light aromatic hydrocarbons - Google Patents

Abstract

The invention relates to a hydrotreating-catalytic cracking combined process method for producing isobutane and light aromatic hydrocarbons in a high yield, which comprises the following steps: mixing a wax oil raw material and catalytic cracking distillate oil, then sending the mixture into four reaction zones of a hydrotreating reactor to carry out hydrodemetallization, hydrodesulfurization reaction, deep hydrogenation saturation reaction of aromatic hydrocarbon and hydrodesulfurization denitrification reaction in sequence, and then separating to obtain a gas product, hydrogenated naphtha, hydrogenated diesel oil and hydrogenated tail oil; introducing the obtained hydrogenated diesel oil into a first cracking reaction zone of a catalytic cracking reactor to contact with a catalytic cracking catalyst and carry out a first catalytic cracking reaction to obtain a reaction oil agent; and introducing the obtained hydrogenated tail oil into a second cracking reaction zone to contact with the reaction oil from the first cracking reaction zone and carry out a second catalytic cracking reaction to obtain a reaction product and a spent catalyst. The method of the invention can enable the catalytic cracking unit to produce more isobutane and light aromatics.

Description

Hydrotreating-catalytic cracking combined process method for increasing yield of isobutane and light aromatic hydrocarbons

Technical Field

The invention relates to a hydrotreating-catalytic cracking combined process method for producing isobutane and light aromatic hydrocarbons in a high yield.

Background

In China, catalytic cracking is widely applied due to good operation flexibility, high gasoline yield and low one-time investment. The single catalytic cracking process has certain requirements on catalytic raw materials, and the raw materials with high sulfur content not only make SOx emission in catalytic cracking flue gas not meet the environmental protection requirements, but also make the sulfur content of gasoline products not meet the product specification requirements. High nitrogen content in the catalytic cracking feedstock increases the catalyst consumption of the cracking catalyst and increases operating costs. The catalytic cracking raw material hydrogenation pretreatment technology can greatly reduce the sulfur and nitrogen content and increase the hydrogen content, thereby reducing the sulfur and nitrogen content of a cracking product and improving the product distribution.

The existing catalytic cracking raw material hydrogenation pretreatment technology mainly adopts single catalytic raw material hydrogenation pretreatment or raw material hydrogenation pretreatment-catalytic cracking combined process technology, and mainly aims to improve the conversion rate of a catalytic cracking unit and further improve the yield of light oil.

For a catalytic cracking device, a wax oil raw material subjected to hydrotreating is used as a catalytic cracking (including various catalytic cracking processes) feed, and catalytic cracking gasoline with low sulfur content can be produced, but the produced catalytic cracking diesel oil (LCO) has high sulfur content and high aromatic hydrocarbon content, generally reaches more than 50 percent, even reaches more than 80 percent, has low cetane number and poor stability, cannot be directly delivered from a factory, and needs to be further processed. Usually, a new catalytic cracking diesel hydro-upgrading device is required to be built or the catalytic cracking diesel is taken as low-value fuel oil to leave a factory. On the other hand, in order to increase the catalytic cracking conversion rate and the light oil yield, the catalytic cracking unit generally circulates Heavy Cycle Oil (HCO) in the catalytic cracking unit, but the cracking effect is not ideal due to high content of HCO aromatics, and a large part of HCO is converted into coke, so that the load of a regenerator is increased, and the treatment capacity and the economic benefit of the catalytic cracking unit are reduced.

US20150274611a1 discloses a process for producing gasoline and diesel oil by hydrogenating and saturating LCO and HCO in a hydrotreating reaction zone, and then returning to catalytic cracking for continuous reaction. In the combined process, LCO and HCO are recycled to the second reactor of the hydrotreating reaction zone, avoiding the demetallization and desulfurization reaction zones. In the method, LCO is circularly converted, the yield of the product propylene is improved by 1.0 percent, the yield of the product gasoline is increased by 2.7 percent, and the yield of aromatic hydrocarbon is increased by 1.6 percent; by adopting HCO cyclic conversion, the propylene product is increased by 0.3 percent, the gasoline is increased by 0.8 percent, and the liquefied gas is increased by 0.4 percent.

CN103937545A discloses a method for preparing high-octane gasoline and propylene from inferior raw oil. In the method, the catalytic wax oil obtained by separating the cracking reaction product is filtered after solvent deasphalting or enters a hydrotreatment device after adsorption deasphalting to obtain the hydrogenated catalytic wax oil. The hydrogenated catalytic wax oil is circulated to the first reaction zone of the catalytic conversion reactor to further obtain high-octane gasoline and propylene. The method not only greatly reduces the yield of dry gas and coke, but also realizes the long-period production of the catalytic wax oil hydrogenation device and the efficient utilization of petroleum resources while converting the poor-quality raw materials into high-octane gasoline and propylene.

CN102443438A discloses a pretreatment method and a combined process of catalytic cracking raw materials. In the method, a residual oil raw material and catalytic slurry oil enter a solvent deasphalting device, deasphalted oil and deep-drawn VGO are mixed and enter a demetalization reaction zone, a reaction product and one or two of light wax oil and coking wax oil are mixed and enter a hydrotreating reaction zone, and a liquid-phase reaction product is used as a catalytic cracking raw material. The catalytic oil slurry returns to the solvent deasphalting device for circular processing. The method improves the flexibility and the desulfurization efficiency of the device and reduces the cost by treating different catalytic cracking raw materials in a segmented manner.

CN103160317B discloses a method for producing propylene and high octane gasoline. In the method, catalytic cracking heavy oil enters a hydrogenation unit, and under the action of a hydrogenation catalyst, 10-80% of polycyclic aromatic hydrocarbon contained in the hydrogenated catalytic cracking heavy oil is hydrogenated and saturated into naphthenic hydrocarbon. The hydrogenated oil enters catalytic cracking to produce propylene and high-octane gasoline. The method can greatly improve the cracking performance of catalytic cracking heavy oil, thereby improving the conversion rate of a catalytic cracking unit and the yield of light oil and realizing the high-efficiency utilization of petroleum resources.

Disclosure of Invention

The invention aims to provide a hydrotreating-catalytic cracking combined process method for producing isobutane and light aromatic hydrocarbons in a high yield.

In order to achieve the above object, the present invention provides a combined hydrotreating-catalytic cracking process for producing isobutane and light aromatics in high yield, which comprises:

mixing a wax oil raw material and catalytic cracking distillate oil, feeding the mixture into a hydrotreating reactor, sequentially carrying out contact reaction with a hydrodemetallization catalyst in a first hydrogenation reaction zone, carrying out contact reaction with a hydrodesulfurization catalyst in a second hydrogenation reaction zone, carrying out contact reaction with an aromatic deep hydrogenation saturated catalyst in a third hydrogenation reaction zone, and carrying out contact reaction with a hydrodesulfurization denitrification catalyst in a fourth hydrogenation reaction zone, and then separating to obtain a gas product, hydrogenated naphtha, hydrogenated diesel oil and hydrogenated tail oil; wherein the hydrogen content of the hydrogenated diesel oil is not less than 11.5 wt%, and the hydrogen content of the hydrogenated tail oil is not less than 11.5 wt%; the catalytic cracking distillate oil is selected from one or more of light cycle oil, heavy cycle oil and catalytic wax oil;

introducing the obtained hydrogenated diesel oil into a first cracking reaction zone of a catalytic cracking reactor to contact with a catalytic cracking catalyst and carry out a first catalytic cracking reaction to obtain a reaction oil agent, wherein the catalytic cracking reactor further comprises a second cracking reaction zone positioned at the downstream of the first cracking reaction zone according to the flow direction of a reaction material;

introducing the obtained hydrogenated tail oil into the second cracking reaction zone to contact with the reaction oil from the first cracking reaction zone and carry out a second catalytic cracking reaction to obtain a reaction product and a spent catalyst;

optionally separating said catalytically cracked distillate selected from one or more of light cycle oil, heavy cycle oil and catalytic wax oil from the resulting reaction product and returning said catalytically cracked distillate to said hydrotreating reactor.

Optionally, the deep hydrogenation saturation catalyst for aromatic hydrocarbon contains a silica carrier, a group VIII metal salt and a group VIB metal oxide;

based on the total weight of the aromatic hydrocarbon deep hydrogenation saturation catalyst and calculated by oxides, the content of the VIII group metal salt is 1.5-7 wt%, and the content of the VIB group metal oxide is 7-35 wt%;

the metal element in the VIII group metal salt is selected from one or more of Cr, Mo and W, and the metal element in the VIB group metal oxide is selected from one or more of Fe, Co and Ni.

Optionally, the third hydrogenation reaction zone is also filled with a hydrocracking catalyst, and the hydrocracking catalyst comprises a carrier and a hydrogenation active metal component loaded on the carrier;

the carrier comprises 5-80 wt% of alumina, 5-80 wt% of silica-alumina and 0.05-75 wt% of molecular sieve based on the dry weight of the carrier, wherein the pore volume of pore channels with pore diameter less than 60 angstroms in the alumina accounts for more than 25% of the total pore volume, and the silica-alumina contains 5-60 wt% of silica and 40-95 wt% of alumina;

based on the dry weight of the hydrocracking catalyst and calculated by oxides, the hydrogenation active metal component comprises 1-10 wt% of VIII group metal elements and 5-40 wt% of VIB group metal elements, wherein the VIII group metal elements are cobalt and/or nickel, and the VIB group metal elements are molybdenum and/or tungsten.

Optionally, if the content of aromatic hydrocarbons with more than three rings in the catalytic cracking distillate is higher than 30 wt%, the third hydrogenation reaction zone is filled with the aromatic deep hydrogenation saturation catalyst and the hydrocracking catalyst, and the filling volume ratio of the aromatic deep hydrogenation saturation catalyst to the hydrocracking catalyst is (1-5): 1;

if the content of aromatic hydrocarbon with more than three rings in the catalytic cracking distillate oil is not higher than 30 weight percent, the third hydrogenation reaction zone is filled with the aromatic hydrocarbon deep hydrogenation saturated catalyst, and the hydrocracking catalyst is not filled.

Optionally, the first hydrogenation reaction zone is further filled with a hydrogenation protective agent, and the filling volume of the hydrogenation protective agent is 0.1-35 vol% and the filling volume of the hydrodemetallization catalyst is 65-99.9 vol% based on the total volume of the catalyst filled in the first hydrogenation reaction zone;

the hydrogenation protective agent comprises 0.5-5 wt% of nickel oxide, 2-10 wt% of molybdenum oxide and the balance of alumina carrier on a dry basis and on the basis of the dry weight of the hydrogenation protective agent.

Optionally, the conditions of the hydroprocessing reactor include: the hydrogen partial pressure is 5-20 MPa, the reaction temperature is 320-450 ℃, and the volume space velocity is 0.1-2 hours^-1The volume ratio of hydrogen to oil is 300-2000 standard cubic meters/cubic meter.

Optionally, the wax oil feedstock is selected from one or more of straight run vacuum wax oil, coker wax oil, and deasphalted oil.

Optionally, the hydrodemetallization catalyst comprises 0.5-5.0 wt% nickel oxide, 2.0-15.0 wt% molybdenum oxide and the balance alumina support, based on the dry weight of the hydrodemetallization catalyst;

on the basis of the dry weight of the hydrodesulfurization catalyst, the hydrodesulfurization catalyst comprises 1.0-10.0 wt% of cobalt oxide, 5-30 wt% of molybdenum oxide and the balance of alumina carrier;

based on the dry weight of the hydrodesulfurization and denitrification catalyst, the hydrodesulfurization and denitrification catalyst comprises 1-10 wt% of nickel oxide, 10-50 wt% of molybdenum oxide and tungsten oxide, 1-10 wt% of fluorine, 0.5-8 wt% of phosphorus oxide and the balance of silica-alumina.

Optionally, the distillation range of the hydrogenated diesel oil is 150-360 ℃, and the initial distillation point of the hydrogenated tail oil is 330-380 ℃.

Optionally, the hydrogenated diesel oil has a total aromatic content of not more than 60 wt%, preferably 35 to 60 wt%, a cyclic hydrocarbon content of not less than 15 wt%, preferably 16 to 55 wt%, and a hydrogen content of 11.5 to 14.0 wt%, preferably 12.0 to 13.5 wt%;

in the hydrogenated tail oil, the total aromatic hydrocarbon content is not higher than 60 wt%, preferably 35-50 wt%, the cyclic hydrocarbon content is not lower than 20 wt%, preferably 20-45 wt%, and the hydrogen content is not lower than 11.5 wt%, preferably 12-13.5 wt%.

Optionally, the catalytic cracking catalyst comprises a zeolite selected from one or more of REY, REHY and ZSM-5, and further comprises an inorganic oxide and/or clay;

the catalytic cracking reactor is selected from one or the combination of a riser reactor and a fluidized bed reactor, and the riser reactor is an equal-diameter riser reactor or a variable-diameter riser reactor.

Optionally, the catalytic cracking reactor is a riser reactor;

the conditions of the first catalytic cracking reaction include: the reaction temperature is 480-700 ℃, the reaction time is 0.05-5 seconds, and the weight ratio of the catalyst to the oil is (3-60): 1;

the conditions of the second catalytic cracking reaction include: the reaction temperature is 420-530 ℃, the reaction time is 2-30 seconds, and the weight ratio of the catalyst to the oil is (3-18): 1.

optionally, the conditions of the first catalytic cracking reaction include: the reaction temperature is 520-680 ℃, the reaction time is 0.2-3 seconds, and the weight ratio of the catalyst to the oil is (4-50): 1;

the conditions of the second catalytic cracking reaction include: the reaction temperature is 460-510 ℃, the reaction time is 3-15 seconds, and the weight ratio of the catalyst to the oil is (4-15): 1.

the invention has the following advantages:

(1) by adopting the hydrotreating process and the catalyst loading scheme thereof provided by the invention, the poor-quality wax oil, the catalytic cracking light cycle oil, the heavy cycle oil, the wax oil and the like are used as raw materials, and the catalytic cracking unit can produce gasoline fraction with high BTX aromatic hydrocarbon content and can produce more isobutane.

(2) The invention adopts one hydrogenation unit to realize two purposes: firstly, hydrodesulfurization, hydrodenitrogenation and hydrodearomatization of the inferior wax oil raw material provide raw materials for producing low-sulfur gasoline by a catalytic cracking unit; secondly, catalytic cracking light cycle, hydrogenation impurity removal of heavy cycle oil and wax oil, deep hydrogenation saturation reaction and selective ring opening of aromatic hydrocarbons with more than two rings provide high-quality feed for producing high-octane gasoline by a catalytic cracking unit.

(3) By the method provided by the invention, the catalytic cracking light cycle oil, the heavy cycle oil, the catalytic wax oil and the like are treated by the hydrogenation unit and then returned to the catalytic cracking unit for further cracking, so that the utilization efficiency of unconverted inferior catalytic cracking light cycle oil, heavy cycle oil and catalytic wax oil is improved, the gasoline yield is further improved, and the BTX aromatic hydrocarbon content in the gasoline fraction is improved.

(4) The method provided by the invention can produce the liquefied gas with high isobutane content while producing the gasoline fraction rich in light aromatic hydrocarbons, and the yield of the liquefied gas is greatly improved.

(5) The product quality is excellent, and the gasoline fraction produced by catalytic cracking has low sulfur content and olefin content; the product yield is high, and the distillate oil produced by the catalytic cracking unit enters the catalytic cracking unit after being hydrogenated, so that the coke yield is reduced, and the yields of gasoline and liquefied gas are correspondingly improved.

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 flow diagram of one embodiment of the combined hydrotreating-catalytic cracking process of the present invention.

Description of the reference numerals

1 hydrogenation reactor 2 hot high pressure separator 3 cold high pressure separator

4 hot low pressure separator 5 cold low pressure separator 6 recycle hydrogen desulfurization tank

7 recycle hydrogen compressor 8 fractionating tower 9 catalytic cracking unit

10 filtering device 11 pipeline 12 pipeline

13 line 14 line 15 line

16 line 17 line 18 line

19 line 20 line 21 line

22 line 23 line 24 line

25 line 26 line 27 line

28 line 29 line 30 line

31 line 32 line 33 line

34 line 35 line

37 line 38 line 39 line

I first hydrogenation reaction zone II second hydrogenation reaction zone III third hydrogenation reaction zone

IV fourth hydrogenation reaction zone

Detailed Description

The following describes in detail specific embodiments of the present invention. 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 hydrotreating-catalytic cracking combined process method for producing isobutane and light aromatic hydrocarbons in a high yield, which comprises the following steps of:

mixing a wax oil raw material and catalytic cracking distillate oil, feeding the mixture into a hydrotreating reactor, sequentially carrying out contact reaction with a hydrodemetallization catalyst in a first hydrogenation reaction zone, carrying out contact reaction with a hydrodesulfurization catalyst in a second hydrogenation reaction zone, carrying out contact reaction with an aromatic deep hydrogenation saturated catalyst in a third hydrogenation reaction zone, and carrying out contact reaction with a hydrodesulfurization denitrification catalyst in a fourth hydrogenation reaction zone, and then separating to obtain a gas product, hydrogenated naphtha, hydrogenated diesel oil and hydrogenated tail oil; wherein the hydrogen content of the hydrogenated diesel oil is not less than 11.5 wt%, and the hydrogen content of the hydrogenated tail oil is not less than 11.5 wt%; the catalytic cracking distillate oil is selected from one or more of light cycle oil, heavy cycle oil and catalytic wax oil;

introducing the obtained hydrogenated diesel oil into a first cracking reaction zone of a catalytic cracking reactor to contact with a catalytic cracking catalyst and carry out a first catalytic cracking reaction to obtain a reaction oil agent, wherein the catalytic cracking reactor further comprises a second cracking reaction zone positioned at the downstream of the first cracking reaction zone according to the flow direction of a reaction material;

introducing the obtained hydrogenated tail oil into the second cracking reaction zone to contact with the reaction oil from the first cracking reaction zone and carry out a second catalytic cracking reaction to obtain a reaction product and a spent catalyst;

optionally separating said catalytically cracked distillate selected from one or more of light cycle oil, heavy cycle oil and catalytic wax oil from the resulting reaction product and returning said catalytically cracked distillate to said hydrotreating reactor.

According to the present invention, the aromatics deep hydrogenation saturation catalyst can be a hydrogenation catalyst containing a metal mixed phase, for example, the aromatics deep hydrogenation saturation catalyst can contain a silica support, at least one metal component selected from group VIII and at least one metal component selected from group VIB. In one embodiment, the group VIB metal component may be present as a metal oxide and the group VIII metal component may be present as a metal salt, i.e., the aromatics deep hydrosaturation catalyst comprises a silica support, a salt of a group VIII metal, and an oxide of a group VIB metal. Wherein the amount of each component may vary over a wide range, in one embodiment the amount of group VIII metal salt may be from 1 to 10 wt.% and the amount of group VIB metal component may be from 5 to 40 wt.%, based on catalyst and calculated as oxide. Preferably, the group VIII metal component is present in an amount of from 1.5 to 7 wt.% and the group VIB metal component is present in an amount of from 7 to 35 wt.%, based on catalyst and calculated as oxide. The metal element in the VIB group metal oxide can be one or more selected from Cr, Mo and W, and is preferably Mo and/or W; the metal element in the VIII group metal salt can be one or more selected from Fe, Co and Ni, and Co and/or Ni are preferred. The salts of the VIII group metals can be one or more of inorganic salts or organic salts of the VIII group metal elements, and the inorganic salts are one or more of carbonates, basic carbonates and nitrates; the organic salt is a salt or a soluble complex generated by combining an organic substance and VIII group metal, the organic substance can be organic alkali, organic carboxylic acid, amine, ketone, ether and alkyl, and organic carboxylate is preferred. For example, preferably the salt of the group VIII metal may be at least one of cobalt nitrate, nickel nitrate, basic nickel carbonate, basic cobalt carbonate, and the oxide of the group VIB metal may be at least one of molybdenum trioxide, tungsten trioxide, ammonium paramolybdate, ammonium metatungstate.

In a further embodiment, the deep hydrogenation saturation catalyst for aromatic hydrocarbons may further comprise one or more auxiliary agents selected from P, F, B, wherein the content of the auxiliary agent is not more than 10 wt% calculated on element and based on the catalyst. The silica support may have a specific surface and pore volume of a conventional silica support, and preferably the specific surface of the silica support is 100-450m²(ii)/g, more preferably 150- & lt 300 & gt²The pore volume of the silica carrier is preferably 0.4 to 1.6mL/g, more preferably 0.5 to 1.0 mL/g.

According to the present invention, in order to promote the occurrence of the selective ring-opening reaction, the third hydrogenation reaction zone may be further filled with a hydrocracking catalyst, which may include a carrier and a hydrogenation active metal component supported on the carrier; the support may comprise from 5 to 80 wt% alumina, from 5 to 80 wt% silica-alumina and from 0.05 to 75 wt% molecular sieve, based on the dry weight of the support, and the pore volume of the channels having pore diameters of less than 60 angstroms in the alumina may be in a proportion of greater than 25% of the total pore volume. The silica-alumina is characterized by a gamma-alumina X-ray diffraction spectrum, and can contain 5-60 wt% of silica and 40-95 wt% of alumina; the hydrocracking catalyst has moderate ring-opening cracking activity, good hydrogenation performance and certain nitrogen resistance.

According to the present invention, the catalyst in the third hydrogenation reaction zone can be loaded according to the content of the aromatic hydrocarbon with more than three rings in the catalytic cracking distillate, for example, if the content of the aromatic hydrocarbon with more than three rings in the catalytic cracking distillate is higher than 30 wt%, preferably higher than 25 wt%, the third hydrogenation reaction zone can be loaded with the deep hydrogenation saturation catalyst of the aromatic hydrocarbon and the hydrocracking catalyst, and the loading volume ratio of the deep hydrogenation saturation catalyst of the aromatic hydrocarbon and the hydrocracking catalyst can be (1-5): 1, preferably (2-4): 1; if the content of aromatic hydrocarbon above three rings in the catalytic cracking distillate oil is not higher than 30 wt%, the third hydrogenation reaction zone can be filled with an aromatic hydrocarbon deep hydrogenation saturated catalyst, and is not filled with a hydrocracking catalyst.

According to the present invention, the first hydrogenation reaction zone may further be filled with a hydrogenation protective agent, and the loading volume of the hydrogenation protective agent may be 0.1-35 vol%, preferably 5-30 vol%, and the loading volume of the hydrodemetallization catalyst may be 65-99.9 vol%, preferably 70-95 vol%, based on the total volume of the catalyst filled in the first hydrogenation reaction zone. Preferably, the hydrogenation protective agent is filled with the hydrodemetallization catalyst based on the total filling volume of the catalyst in the first reaction zone. The hydrogenation protective agent can comprise 0.5-5 wt% of nickel oxide, 2-10 wt% of molybdenum oxide and the balance of alumina carrier based on dry basis and weight of hydrogenation protective agent on a dry basis. The hydrogenation protective agent can be filled with at least one, preferably the combination of two hydrogenation protective agents with different activities and different pore structures, so as to slow down the pressure drop rise of a catalyst bed layer and improve the operation period.

The conditions of the hydrogenation reaction according to the present invention are well known to the skilled person, for example the conditions of the hydroprocessing reactor may comprise: the hydrogen partial pressure is 5-20 MPa, the reaction temperature is 300-450 ℃, and the volume space velocity is 0.1-3 hours^-1The hydrogen-oil volume ratio is 300-: the hydrogen partial pressure is 6-16 MPa, the reaction temperature is 330-^-1The volume ratio of hydrogen to oil is 500-2000 standard cubic meters/cubic meter.

According to the present invention, a wax oil feedstock is well known to those skilled in the art and may be selected from one or more of straight run vacuum wax oil, coker wax oil, and deasphalted oil.

Hydrodemetallization, hydrodesulfurization, and hydrodenitrogenation catalysts are well known to those skilled in the art in accordance with the present invention, and may include, for example, 0.5-5.0 wt% nickel oxide, 2.0-15.0 wt% molybdenum oxide, and the balance alumina support, based on the dry weight of the hydrodemetallization catalyst; the hydrodesulfurization catalyst may comprise 1.0-10.0 wt% cobalt oxide, 5-30 wt% molybdenum oxide and the balance alumina support, based on the dry weight of the hydrodesulfurization catalyst; the hydrodesulfurization and denitrogenation catalyst may include nickel oxide in an amount of 1 to 10 wt%, molybdenum oxide and tungsten oxide in an amount of 10 to 50 wt%, fluorine in an amount of 1 to 10 wt%, phosphorus oxide in an amount of 0.5 to 8 wt%, and silica-alumina in the balance, based on the dry weight of the hydrodesulfurization and denitrogenation catalyst.

According to the invention, the hydrogenation product is subjected to a fractionation unit to obtain a diesel oil fraction rich in cyclic hydrocarbons and a desulfurized and denitrified hydrogenated wax oil. The hydrogenated diesel oil fraction is sent into a first cracking reaction zone, and the hydrogenated tail oil fraction is sent into a second cracking reaction zone. The hydrogenated diesel oil and the hydrogenated tail oil are respectively cracked in the catalytic cracking unit, so that the yield of the product gasoline and the BTX aromatic hydrocarbon content in the gasoline can be greatly improved, and meanwhile, the liquefied gas rich in isobutane can be produced. In addition, the invention can respectively feed the hydrogenation diesel oil and the hydrogenation tail oil which are composed of specially selected hydrogen content and hydrocarbons into the catalytic cracking reactor for reaction by controlling the hydrogenation condition, so as to produce more isobutane and light aromatic hydrocarbons, wherein the distillation range of the hydrogenation diesel oil can be 150-380 ℃ and the initial distillation point of the hydrogenation tail oil can be 330-380 ℃. The hydrogenated diesel oil may have a total aromatics content of not more than 60% by weight, preferably not more than 50% by weight, for example, from 35 to 60% by weight, a cyclic hydrocarbon content of not less than 15% by weight, preferably not less than 20% by weight, for example, from 15 to 55% by weight, and a hydrogen content of from 11.5 to 14.0% by weight, preferably from 12.0 to 13.5% by weight; the hydrogenated tail oil may have a total aromatic content of not more than 60% by weight, preferably not more than 50% by weight, for example, from 35 to 50% by weight, a cyclic hydrocarbon content of not less than 20% by weight, preferably not less than 20% by weight to 45% by weight, for example, from 30 to 40% by weight, and a hydrogen content of not less than 11.5% by weight, preferably from 12 to 13.5% by weight.

The catalytic cracking process in the present invention may include various types of fluidized catalytic cracking processes, and catalytic cracking processes developed for specific purposes, such as MIP process for producing various isomeric olefins developed by petrochemical in china, DCC process, and the like. Catalytic cracking catalysts and catalytic cracking reactors are well known to those skilled in the art, for example, the catalytic cracking catalyst may comprise a zeolite selected from one or more of REY, REHY, and ZSM-5, and further comprise an inorganic oxide and/or clay; the catalytic cracking reactor can be selected from one or a combination of a riser reactor and a fluidized bed reactor, and the riser reactor can be a constant-diameter riser reactor or a variable-diameter riser reactor.

The conditions of the catalytic cracking reaction according to the present invention are well known to those skilled in the art, for example, the catalytic cracking reactor is a riser reactor; the conditions of the first catalytic cracking reaction may include: the reaction temperature is 480-700 ℃, the reaction time is 0.05-5 seconds, and the weight ratio of the catalyst to the oil is (3-60): 1; the conditions of the second catalytic cracking reaction may include: the reaction temperature is 420-530 ℃, the reaction time is 2-30 seconds, and the weight ratio of the catalyst to the oil is (3-18): 1. the conditions of the first catalytic cracking reaction preferably include: the reaction temperature is 520-680 ℃, the reaction time is 0.2-3 seconds, and the weight ratio of the catalyst to the oil is (4-50): 1; the conditions of the second catalytic cracking reaction preferably include: the reaction temperature is 460-510 ℃, the reaction time is 3-15 seconds, and the weight ratio of the catalyst to the oil is (4-15): 1.

the method for separating the hydrogenation product according to the present invention is within the skill of the art, and can be performed in, for example, a hot high-pressure separator, a hot low-pressure separator, a cold high-pressure separator, a cold low-pressure separator, and a fractionating tower, and the description of the present invention is omitted.

The method provided by the invention is further explained in the following with reference to the attached drawings.

FIG. 1 is a schematic flow diagram of a combined hydrotreating-catalytic cracking process for increasing isobutane and light aromatics production according to the present invention. Many necessary devices such as heating furnaces, pumps, heat exchangers, etc. are omitted from the drawings.

As shown in fig. 1, the wax oil raw material from the pipeline 11 is mixed with the catalytic cracking light cycle oil, heavy cycle oil and/or wax oil from the pipeline 37, and then mixed with the hydrogen-rich gas from the pipeline 26 via the pipeline 12, and then fed into the hydrogenation reactor 1 via the pipeline 13, and then sequentially passes through the first hydrogenation reaction zone I to perform hydrodemetallization reaction, the second hydrogenation reaction zone II to perform hydrodesulfurization reaction, the third hydrogenation reaction zone III to perform deep hydrogenation saturation and/or ring opening cracking reaction of aromatic hydrocarbon, and the fourth hydrogenation reaction zone IV to perform desulfurization, denitrification, deep refining, and the like. The resulting oil produced by the reaction is separated in a hot high pressure separator 2 via line 14. The gas phase substance obtained from the hot high-pressure separator 2 flows through a pipeline 19 and enters the cold high-pressure separator 3 for further separation, and the gas phase substance obtained from the cold high-pressure separator 3 flows through a pipeline 24 and enters the recycle hydrogen desulfurization tank 6, then flows through the recycle hydrogen compressor 7 and returns to the inlet of the hydrogenation reactor through a pipeline 26. The sour water separated in cold high pressure separator 3 is withdrawn via line 38 and the resulting liquid phase stream is passed via line 20 to cold low pressure separator 5 for further separation. The liquid phase obtained from the hot low-pressure separator 2 flows through a pipeline 15 to enter the hot low-pressure separator 4 for separation. The gas phase obtained from the hot low-pressure separator 4 flows through a pipeline 21 to enter the cold low-pressure separator 5 for separation, and the liquid phase obtained flows through a pipeline 16 and a pipeline 17 to enter the fractionating tower 8 for component separation. The sour water from the cold low pressure separator 5 is withdrawn via line 39 and the resulting gas is withdrawn via line 27 and the liquid phase stream from the cold low pressure separator is passed via line 22 to the fractionation column 8 for component separation. The hydrogenated naphtha separated from the fractionating tower 8 is pumped out through a pipeline 28, the obtained hydrogenated diesel oil enters a first cracking reaction zone of the catalytic cracking unit 9 through a pipeline 23 for cracking reaction, and the obtained hydrogenated tail oil enters a second cracking reaction zone of the catalytic cracking unit 9 through a pipeline 18 for cracking reaction. The reaction product is separated into dry gas by a fractionating device in the catalytic cracking unit and is pumped out by a pipeline 29, liquefied gas is pumped out by a pipeline 30, catalytic gasoline is pumped out by a pipeline 31, catalytic cracking light cycle oil is mixed by a pipeline 32, catalytic cracking heavy cycle oil is mixed by a pipeline 33 and/or wax oil by a pipeline 34, solid particles are removed by a filtering device 10, and the mixture is mixed with a wax oil raw material 11 by a pipeline 37 and then enters a hydrotreating unit. Coke is withdrawn via line 35.

The following examples further illustrate the process of the present invention but are not intended to limit the invention thereto.

In the embodiment, the commodity brand of a hydrogenation protective agent A is RG-30A, the commodity brand of a hydrogenation protective agent B is RG-30B, the commodity brands of a hydrogenation demetallization catalyst C and a hydrogenation demetallization catalyst D are RDM-35 and RAM-100, the commodity brand of a hydrogenation desulfurization catalyst E is RVS-420, an aromatic deep hydrogenation saturated catalyst F is prepared according to the method, a hydrocracking catalyst G is RHC-140, and a hydrogenation desulfurization denitrification catalyst H is RN-410.

The aromatic hydrocarbon deep hydrogenation saturation catalyst is prepared by the following method:

(1) preparation of silica carrier:

3000 g of Silica Gel 955 commercial Silica Gel (product of Davison Chemical company, USA, containing SiO299.8 wt%) and 75 g of sesbania powder are mixed uniformly, then mixed with 84 ml of nitric acid (concentration 65-68%, analytical purity, Shantou Kanghua) and 4200 ml of water, the mixture is kneaded uniformly on a double screw extruder, and then extruded into butterfly-shaped strips with phi of 1.3 mm, the wet strips are dried at 120 ℃ for 4 hours, and then baked at 600 ℃ for 3 hours, and the silicon oxide carrier S is obtained. Using BET N₂The specific surface area of the carrier is 180m by adsorption analysis²The pore volume is 0.78 mL/g.

(2) Preparing an aromatic hydrocarbon deep hydrogenation saturated catalyst:

the preparation method comprises the steps of taking 200 g of a silicon oxide carrier S, soaking the silicon oxide carrier S in 200 ml of a dilute ammonia solution (with the concentration of 10%) containing 21.9 g of ammonium paramolybdate for 2 hours, drying the silicon oxide carrier S at 120 ℃ for 4 hours, roasting the silicon oxide carrier S at 460 ℃ for 4 hours to obtain a molybdenum-containing carrier loaded with molybdenum oxide, soaking the molybdenum-containing carrier in 156 ml of an aqueous solution containing 13.3 g of cobalt nitrate and 4.4 g of nickel nitrate for 2 hours, and drying the molybdenum-containing carrier at 120 ℃ for 4 hours to obtain the aromatic hydrocarbon deep hydrogenation saturated catalyst. The chemical composition of the catalyst was determined by X-ray fluorescence based on the weight of the catalyst. The aromatic hydrocarbon deep hydrogenation saturated catalyst prepared by the method contains 8.0% of molybdenum oxide, 0.6% of nickel oxide and 1.5% of cobalt oxide.

The above catalysts are all produced by China Long-distance division of petrochemical catalysts.

The wax oil feedstock I used in the examples was obtained from a refinery hydrotreater and the properties are given in Table 1.

Example 1

By adopting the process flow shown in fig. 1, a wax oil raw material I and catalytic cracking Light Cycle Oil (LCO) are mixed and then enter a hydrotreating reactor, and are sequentially subjected to contact reaction with a hydrogenation protective agent A, a hydrogenation protective agent B and a hydrogenation demetalization catalyst D (the filling volume ratio is 10: 10: 80) in a first hydrogenation reaction zone, contact reaction with a hydrodesulfurization catalyst E in a second hydrogenation reaction zone, contact reaction with an aromatic deep hydrogenation saturated catalyst F in a third hydrogenation reaction zone, and contact reaction with a hydrodesulfurization and denitrification catalyst H in a fourth hydrogenation reaction zone. The liquid product enters a fractionation system for further separation to obtain hydrogenated naphtha, hydrogenated diesel oil and hydrogenated tail oil.

The obtained hydrogenated diesel oil enters a first cracking reaction zone of a catalytic cracking reactor. The total aromatic hydrocarbon content of the obtained hydrogenated diesel oil is 49 wt%, the cyclic hydrocarbon content is 18 wt%, and the H content is 12.1 wt%.

The obtained hydrogenated tail oil enters a second cracking reaction zone of the catalytic cracking reactor. The total aromatic content of the obtained hydrogenated tail oil is 48.5 wt%, the content of cyclic hydrocarbon is 34.3 wt%, and the content of H is 12.3 wt%.

Table 2 shows the properties of the catalytically cracked light cycle oil, table 3 shows the process parameters of each reaction zone, table 4 shows the product distribution of the hydrotreating unit, table 5 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the examples, table 6 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the comparative examples, and table 7 shows the distribution of the catalytically cracked products and the yields of isoparaffins and aromatics.

Example 2

By adopting the process flow shown in fig. 1, a wax oil raw material I and catalytic cracking Heavy Cycle Oil (HCO) are mixed and then enter a hydrotreating reactor, and are sequentially contacted with a hydrogenation protective agent A, a hydrogenation protective agent B and a hydrogenation demetalization catalyst C (the filling volume ratio is 15: 10: 75) in a first hydrogenation reaction zone for reaction, contacted with a hydrodesulfurization catalyst E in a second hydrogenation reaction zone for reaction, contacted with an aromatic deep hydrogenation saturated catalyst F in a third hydrogenation reaction zone for reaction, and contacted with a hydrodesulfurization and denitrification catalyst H in a fourth hydrogenation reaction zone for reaction. The liquid product enters a fractionation system for further separation to obtain hydrogenated naphtha, hydrogenated diesel oil and hydrogenated tail oil.

The obtained hydrogenated diesel oil enters a first cracking reaction zone of a catalytic cracking reactor. The total aromatic hydrocarbon content of the obtained hydrogenated diesel oil is 51.0 weight percent, the cyclic hydrocarbon content is 25.5 weight percent, and the H content is 12.6 weight percent.

The obtained hydrogenated tail oil enters a second cracking reaction zone of the catalytic cracking reactor. The total aromatic content of the obtained hydrogenated tail oil is 40.0 wt%, the content of cyclic hydrocarbon is 33.0 wt%, and the content of H is 12.8 wt%.

Table 2 shows the properties of the catalytically cracked light cycle oil, table 3 shows the process parameters of each reaction zone, table 4 shows the product distribution of the hydrotreating unit, table 5 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the examples, table 6 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the comparative examples, and table 7 shows the distribution of the catalytically cracked products and the yields of isoparaffins and aromatics.

Example 3

By adopting the process flow shown in fig. 1, a wax oil raw material I and catalytic wax oil (FGO) are mixed and then enter a hydrotreating reactor, and are sequentially subjected to contact reaction with a hydrogenation protective agent a, a hydrogenation protective agent B, a hydrogenation demetallization catalyst C and a hydrogenation demetallization catalyst D (the loading volume ratio is 5: 25: 30: 40) in a first hydrogenation reaction zone, contact reaction with a hydrodesulfurization catalyst E and a hydrotreating catalyst H (the loading volume ratio is 50: 50) in a second reaction zone, contact reaction with an aromatic deep hydrogenation saturated catalyst F and a hydrocracking catalyst G (the loading volume ratio is 70: 30) in a third hydrogenation reaction zone, and contact reaction with a hydrodesulfurization and denitrification catalyst H in a fourth hydrogenation reaction zone. The liquid product enters a fractionation system for further separation to obtain hydrogenated naphtha, hydrogenated diesel oil and hydrogenated tail oil.

The obtained hydrogenated diesel oil enters a first cracking reaction zone of a catalytic cracking reactor. The total aromatic content of the obtained hydrogenated diesel oil is 59.4 wt%, the content of cyclic hydrocarbon is 19.3 wt%, and the content of H is 11.6 wt%.

The obtained hydrogenated tail oil enters a second cracking reaction zone of the catalytic cracking reactor. The total aromatic content of the obtained hydrogenated tail oil is 49.6 wt%, the content of cyclic hydrocarbon is 28.4 wt%, and the content of H is 12.1 wt%.

Table 2 shows the properties of the catalytically cracked light cycle oil, table 3 shows the process parameters of each reaction zone, table 4 shows the product distribution of the hydrotreating unit, table 5 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the examples, table 6 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the comparative examples, and table 7 shows the distribution of the catalytically cracked products and the yields of isoparaffins and aromatics.

Comparative example 1

The process is basically the same as example 1, except that a catalyst H is adopted in the third reaction zone, and the hydrogen content of the hydrogenated diesel oil and the hydrogenated wax oil is lower than that of example 1.

By adopting the process flow shown in fig. 1, a wax oil raw material I and catalytic cracking Light Cycle Oil (LCO) are mixed and then enter a hydrotreating reactor, and are sequentially subjected to contact reaction with a hydrogenation protective agent A, a hydrogenation protective agent B and a hydrogenation demetalization catalyst D (the filling volume ratio is 10: 10: 80) in a first hydrogenation reaction zone, contact reaction with a hydrodesulfurization catalyst E in a second hydrogenation reaction zone, contact reaction with a conventional hydrogenation catalyst H in a third hydrogenation reaction zone, and contact reaction with a hydrodesulfurization denitrification catalyst H in a fourth hydrogenation reaction zone. The liquid product enters a fractionation system for further separation to obtain hydrogenated naphtha, hydrogenated diesel oil and hydrogenated tail oil.

The obtained hydrogenated diesel oil enters a first cracking reaction zone of a catalytic cracking reactor. The total aromatic hydrocarbon content of the obtained hydrogenated diesel oil is 65 wt%, the cyclic hydrocarbon content is 15 wt%, and the H content is 11.4 wt%.

The obtained hydrogenated tail oil enters a second cracking reaction zone of the catalytic cracking reactor. The total aromatic content of the obtained hydrogenated tail oil is 52.0 wt%, the content of cyclic hydrocarbon is 25.5 wt%, and the content of H is 11.9 wt%.

Table 2 shows the properties of the catalytically cracked light cycle oil, table 3 shows the process parameters of each reaction zone, table 4 shows the product distribution of the hydrotreating unit, table 5 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the examples, table 6 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the comparative examples, and table 7 shows the distribution of the catalytically cracked products and the yields of isoparaffins and aromatics.

Comparative example 2

The same as example 1 except that the hydrogen content of the hydrogenated diesel oil and the hydrogen content of the hydrogenated wax oil were controlled to be less than 11.5 wt%.

By adopting the process flow shown in fig. 1, a wax oil raw material I and catalytic cracking Light Cycle Oil (LCO) are mixed and then enter a hydrotreating reactor, and are sequentially subjected to contact reaction with a hydrogenation protective agent A, a hydrogenation protective agent B and a hydrogenation demetalization catalyst D (the filling volume ratio is 10: 10: 80) in a first hydrogenation reaction zone, contact reaction with a hydrodesulfurization catalyst E in a second hydrogenation reaction zone, contact reaction with a conventional hydrogenation catalyst F in a third hydrogenation reaction zone, and contact reaction with a hydrodesulfurization denitrification catalyst H in a fourth hydrogenation reaction zone. The liquid product enters a fractionation system for further separation to obtain hydrogenated naphtha, hydrogenated diesel oil and hydrogenated tail oil.

The obtained hydrogenated diesel oil enters a first cracking reaction zone of a catalytic cracking reactor. The total aromatic hydrocarbon content of the obtained hydrogenated diesel oil is 68.5 weight percent, the cyclic hydrocarbon content is 12.0 weight percent, and the H content is 10.9 weight percent.

The obtained hydrogenated tail oil enters a second cracking reaction zone of the catalytic cracking reactor. The total aromatic content of the obtained hydrogenated tail oil is 55.5 wt%, the content of cyclic hydrocarbon is 25.0 wt%, and the content of H is 11.1 wt%.

Table 2 shows the properties of the catalytically cracked light cycle oil, table 3 shows the process parameters of each reaction zone, table 4 shows the product distribution of the hydrotreating unit, table 5 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the examples, table 6 shows the properties of the hydrogenated diesel oil and the hydrogenated wax oil of the comparative examples, and table 7 shows the distribution of the catalytically cracked products and the yields of isoparaffins and aromatics.

The embodiment shows that the method provided by the invention has the advantages that the isobutane content in the liquefied gas product of the catalytic cracking unit is high, and the aromatic hydrocarbon content in the gasoline product is high.

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 hydroprocessing reaction zone wax oil feedstock Properties

Name of raw materials	Wax oil feedstock I
		Density (20 ℃ C.), g/cm3	0.9322
S，μg/g	24000
		N，μg/g	1200
Total aromatic content, wt.%	50.0
		Aromatic hydrocarbon content over bicyclo ring, wt%	23.0
Content of aromatic hydrocarbons of three or more rings, wt.%	9.7
		Distillation Range ASTM D-1160, deg.C
Initial boiling point	260
		10％	375
50％	458
		90％	524
End point of distillation	540

TABLE 2 catalytic cracking light cycle oil, heavy cycle oil and wax oil Properties

	Example 1	Example 2	Example 3
				Fraction of recycle	LCO	HCO	FGO
Density (20 ℃ C.), g/cm3	0.9471	0.9714	1.027
				C, weight%	90.36	90.77	91.33
H, weight%	9.64	9.23	8.66
				S，μg/g	7550	8520	4990
N，μg/g	781	1000	1200
				Total aromatic content, wt.%	78.9	79.9	83.8
Aromatic hydrocarbon content over bicyclo ring, wt%	55.8	70.2	77.7
				Content of aromatic hydrocarbons of three or more rings, wt.%	6.4	9.5	44.6
Distillation range, deg.C	ASTM D-86	ASTM D-86	ASTM D-1160
				Initial boiling point	216	250	230
10％	240	267	365
				50％	274	294	485
90％	330	336	545
				End point of distillation	356	362	565

TABLE 3 hydroprocessing unit and catalytic cracking unit Process conditions

TABLE 4 hydroprocessing unit product distribution

	Comparative example 1	Comparative example 2	Example 1	Example 2	Example 3
						A hydrotreating unit: by weight%
Entering a formula:
						mixing feed	100	100	100	100	100
Inferior wax oil	75	75	75	85	60
						Catalytic distillates (LCO, HCO, FGO)	25	25	25	15	40
Chemical hydrogen consumption, wt.%	1.00	0.9	1.39	1.25	2.1
						The method comprises the following steps:
H2S+NH3	1.96	1.92	2.08	2.37	1.56
						C1+C2	0.35	0.31	0.37	0.32	0.25
C3+C4	0.47	0.44	0.51	0.47	0.4
						hydrogenated naphtha	0.65	0.58	0.73	0.56	0.5
Hydrogenated diesel oil (first cracking reaction zone)	28.9	27.45	31.7	22.96	37.24
						Hydrogenation tail oil (to the second cracking reaction zone)	68.67	70.24	66.00	74.57	62.15

TABLE 5 comparative example hydrogenated Diesel and hydrogenated wax oil Properties

TABLE 6 hydrogenated Diesel and hydrogenated Tail oil Properties of the examples

TABLE 7 catalytic cracking unit product distribution

A catalytic cracking unit: by weight%	Comparative example 1	Comparative example 2	Example 1	Example 2	Example 3
						Dry gas	1.75	1.35	2.3	2.12	2.75
Liquefied gas	25.5	19.82	37.4	35.2	33.7
						Propylene (PA)	9.1	5.82	13.1	11.52	11.3
Isobutene	2.52	2.63	2.49	1.31	1.15
						Isobutane	5.92	2.98	14.32	13.25	12.5
Gasoline (gasoline)	50.6	49.5	53.5	50.9	47.8
						Benzene and its derivatives	0.83	0.71	2.06	1.81	1.88
Toluene	5.77	4.89	9.97	8.5	8.77
						Xylene	7.95	6.95	13.14	12.36	12.8
BTX	14.55	12.55	25.17	22.67	23.45
						Catalytic Light Cycle Oil (LCO)	8.45	13.68	0	6.83	7.70
Catalytic Heavy Cycle Oil (HCO)	6.5	7.15	3.7	0	0
						Catalytic FGO	0	0	0	0	0
Coke	7.2	8.5	3.1	5.05	8.05
						Total up to	100.00	100.00	100.00	100.00	100.00

Claims (14)

1. A hydrotreating-catalytic cracking combined process method for producing isobutane and light aromatic hydrocarbons in a high yield comprises the following steps:

mixing a wax oil raw material and catalytic cracking distillate oil, feeding the mixture into a hydrotreating reactor, sequentially carrying out contact reaction with a hydrodemetallization catalyst in a first hydrogenation reaction zone, carrying out contact reaction with a hydrodesulfurization catalyst in a second hydrogenation reaction zone, carrying out contact reaction with an aromatic deep hydrogenation saturated catalyst in a third hydrogenation reaction zone, and carrying out contact reaction with a hydrodesulfurization denitrification catalyst in a fourth hydrogenation reaction zone, and then separating to obtain a gas product, hydrogenated naphtha, hydrogenated diesel oil and hydrogenated tail oil; wherein the hydrogen content of the hydrogenated diesel oil is not less than 11.5 wt%, and the hydrogen content of the hydrogenated tail oil is not less than 11.5 wt%; the catalytic cracking distillate oil is selected from one or more of light cycle oil, heavy cycle oil and catalytic wax oil;

introducing the obtained hydrogenated diesel oil into a first cracking reaction zone of a catalytic cracking reactor to contact with a catalytic cracking catalyst and carry out a first catalytic cracking reaction to obtain a reaction oil agent, wherein the catalytic cracking reactor further comprises a second cracking reaction zone positioned at the downstream of the first cracking reaction zone according to the flow direction of a reaction material;

introducing the obtained hydrogenated tail oil into the second cracking reaction zone to contact with the reaction oil from the first cracking reaction zone and carry out a second catalytic cracking reaction to obtain a reaction product and a spent catalyst;

optionally separating said catalytically cracked distillate selected from one or more of light cycle oil, heavy cycle oil and catalytic wax oil from the resulting reaction product and returning said catalytically cracked distillate to said hydrotreating reactor.

2. The combined process of claim 1 wherein the aromatics deep hydrosaturation catalyst comprises a silica support, a salt of a group VIII metal, and an oxide of a group VIB metal;

based on the total weight of the aromatic hydrocarbon deep hydrogenation saturation catalyst and calculated by oxides, the content of the VIII group metal salt is 1.5-7 wt%, and the content of the VIB group metal oxide is 7-35 wt%;

the metal element in the VIII group metal salt is selected from one or more of Cr, Mo and W, and the metal element in the VIB group metal oxide is selected from one or more of Fe, Co and Ni.

3. The combined process of claim 1, wherein the third hydrogenation reaction zone is further loaded with a hydrocracking catalyst comprising a support and a hydrogenation-active metal component supported on the support;

the carrier comprises 5-80 wt% of alumina, 5-80 wt% of silica-alumina and 0.05-75 wt% of molecular sieve based on the dry weight of the carrier, wherein the pore volume of pore channels with pore diameter less than 60 angstroms in the alumina accounts for more than 25% of the total pore volume, and the silica-alumina contains 5-60 wt% of silica and 40-95 wt% of alumina;

based on the dry weight of the hydrocracking catalyst and calculated by oxides, the hydrogenation active metal component comprises 1-10 wt% of VIII group metal elements and 5-40 wt% of VIB group metal elements, wherein the VIII group metal elements are cobalt and/or nickel, and the VIB group metal elements are molybdenum and/or tungsten.

4. The combined process method of claim 1, wherein if the aromatic hydrocarbon content of the catalytic cracked distillate is higher than 30 wt%, the third hydrogenation reaction zone is filled with the aromatic hydrocarbon deep hydrogenation saturation catalyst and the hydrocracking catalyst, and the filling volume ratio of the aromatic hydrocarbon deep hydrogenation saturation catalyst to the hydrocracking catalyst is (1-5): 1;

if the content of aromatic hydrocarbon with more than three rings in the catalytic cracking distillate oil is not higher than 30 weight percent, the third hydrogenation reaction zone is filled with the aromatic hydrocarbon deep hydrogenation saturated catalyst, and the hydrocracking catalyst is not filled.

5. The integrated process of claim 1, wherein the first hydrogenation reaction zone is further filled with a hydrogenation protective agent, wherein the loading volume of the hydrogenation protective agent is 0.1-35 vol% and the loading volume of the hydrodemetallization catalyst is 65-99.9 vol% based on the total volume of the catalyst filled in the first hydrogenation reaction zone;

the hydrogenation protective agent comprises 0.5-5 wt% of nickel oxide, 2-10 wt% of molybdenum oxide and the balance of alumina carrier on a dry basis and on the basis of the dry weight of the hydrogenation protective agent.

6. The combined process of claim 1, wherein the conditions of the hydroprocessing reactor include: the hydrogen partial pressure is 5-20 MPa, the reaction temperature is 320-450 ℃, and the volume space velocity is 0.1-2 hours^-1The volume ratio of hydrogen to oil is 300-2000 standard cubic meters/cubic meter.

7. The combined process of claim 1, wherein the wax oil feedstock is selected from one or more of straight run vacuum wax oil, coker wax oil, and deasphalted oil.

8. The combined process of claim 1 wherein the hydrodemetallization catalyst comprises, on a dry basis weight basis of the hydrodemetallization catalyst, 0.5-5.0 wt.% nickel oxide, 2.0-15.0 wt.% molybdenum oxide, and the balance alumina support;

on the basis of the dry weight of the hydrodesulfurization catalyst, the hydrodesulfurization catalyst comprises 1.0-10.0 wt% of cobalt oxide, 5-30 wt% of molybdenum oxide and the balance of alumina carrier;

based on the dry weight of the hydrodesulfurization and denitrification catalyst, the hydrodesulfurization and denitrification catalyst comprises 1-10 wt% of nickel oxide, 10-50 wt% of molybdenum oxide and tungsten oxide, 1-10 wt% of fluorine, 0.5-8 wt% of phosphorus oxide and the balance of silica-alumina.

9. The combined process as claimed in claim 1, wherein the distillation range of the hydrogenated diesel oil is 150-360 ℃ and the initial distillation point of the hydrogenated tail oil is 330-380 ℃.

10. The integrated process of claim 1 wherein said hydrogenated diesel fuel has a total aromatics content of no more than 60 wt.%, a cyclic hydrocarbons content of no less than 15 wt.%, and a hydrogen content of from 11.5 to 14.0 wt.%;

in the hydrogenated tail oil, the total aromatic hydrocarbon content is not higher than 60 wt%, the cyclic hydrocarbon content is not lower than 20 wt%, and the hydrogen content is not lower than 11.5 wt%.

11. The integrated process of claim 10 wherein said hydrogenated diesel fuel has a total aromatics content of 35 to 60 wt.%, a cyclic hydrocarbons content of 16 to 55 wt.%, and a hydrogen content of 12.0 to 13.5 wt.%;

in the hydrogenation tail oil, the total aromatic hydrocarbon content is 35-50 wt%, the cyclic hydrocarbon content is 20-45 wt%, and the hydrogen content is 12-13.5 wt%.

12. The combined process of claim 1 wherein the catalytic cracking catalyst comprises a zeolite selected from one or more of REY, REHY, and ZSM-5, and further comprises an inorganic oxide and/or clay;

the catalytic cracking reactor is selected from one or the combination of a riser reactor and a fluidized bed reactor, and the riser reactor is an equal-diameter riser reactor or a variable-diameter riser reactor.

13. The combined process of claim 1 wherein the catalytic cracking reactor is a riser reactor;

the conditions of the first catalytic cracking reaction include: the reaction temperature is 480-700 ℃, the reaction time is 0.05-5 seconds, and the weight ratio of the catalyst to the oil is (3-60): 1;

the conditions of the second catalytic cracking reaction include: the reaction temperature is 420-530 ℃, the reaction time is 2-30 seconds, and the weight ratio of the catalyst to the oil is (3-18): 1.

14. the combined process of claim 13 wherein the conditions of the first catalytic cracking reaction comprise: the reaction temperature is 520-680 ℃, the reaction time is 0.2-3 seconds, and the weight ratio of the catalyst to the oil is (4-50): 1;

the conditions of the second catalytic cracking reaction include: the reaction temperature is 460-510 ℃, the reaction time is 3-15 seconds, and the weight ratio of the catalyst to the oil is (4-15): 1.

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