CN112745896A

CN112745896A - Method and device for continuously producing aromatic hydrocarbon by hydrocatalytically cracking FCC circulating oil

Info

Publication number: CN112745896A
Application number: CN201911053569.3A
Authority: CN
Inventors: 唐津莲; 龚剑洪; 毛安国; 刘宪龙; 李泽坤; 袁起民
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2019-10-31
Filing date: 2019-10-31
Publication date: 2021-05-04
Anticipated expiration: 2039-10-31
Also published as: CN112745896B

Abstract

A process and apparatus for continuously preparing arylhydrocarbon by hydrocatalytically cracking FCC circulating oil are disclosed. In an alternate fixed bed reactor device, the aromatic hydrocarbon-rich catalytic cracking cycle oil contacts an aromatic hydrocarbon dealkylation catalyst in a hydrogen atmosphere for catalytic cracking dealkylation, and aromatic hydrocarbon extraction is carried out after the dealkylation base oil is desulfurized and nitrogen to produce aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene and the like; the coking deactivation catalyst is regenerated and recycled in an oxygen-containing atmosphere after being subjected to nitrogen stripping, dehydrogenation and depressurization. The method for continuously producing the aromatic hydrocarbons such as BTX, naphthalene and the like by regenerating and catalyzing the cracking reaction of the FCC circulating oil has the advantages of high aromatic hydrocarbon yield, low coke yield and high utilization rate of the FCC circulating oil.

Description

Method and device for continuously producing aromatic hydrocarbon by hydrocatalytically cracking FCC circulating oil

Technical Field

The invention belongs to a method and a device for continuously producing aromatic hydrocarbon by FCC circulating oil reaction regeneration, and particularly relates to a high-efficiency continuous production method and a device for producing aromatic hydrocarbon such as benzene, toluene, xylene, naphthalene and the like by hydrocatalytically cracking FCC circulating oil by adopting an alternating fixed bed reactor.

Background

As environmental regulations become more stringent, the use of catalytic cracking cycle oil (FCC cycle oil, abbreviated LCO) is limited. On one hand, the quality of the fuel oil is rapidly upgraded, the catalytic cracking cycle oil has high content of sulfur-containing compounds and nitrogen-containing compounds, high content of aromatic hydrocarbons, particularly polycyclic aromatic hydrocarbons, and low cetane number, and even if the catalytic cracking cycle oil is subjected to hydro-upgrading, the catalytic cracking cycle oil is difficult to be used as a blending component of the diesel oil for vehicles; on the other hand, the economic slow-down causes the diesel oil to have excessive structure, the diesel oil sales is greatly reduced, and the reduction of the diesel-gasoline ratio becomes a necessary trend, so that a new path must be found for the catalytic cracking cycle oil.

For the efficient conversion and utilization of the aromatic-rich catalytic diesel oil (LCO), two technologies exist at present: one technology for producing high-octane gasoline or aromatic hydrocarbon material by selective hydrogenation and catalytic cracking of LCO (liquid crystal oxygen) is LTAG technology, and the other technology for producing gasoline by hydrocracking of LCO and BTX (BTX) is RLG or FD2G technology. The LTAG technology taking patents such as CN201310516479.X, CN201310517666.X, CN201310517080.3 and the like as cores and the LTAG technology taking patents such as CN201080071134.2 and the like utilize a combination of a hydrogenation unit and a catalytic cracking unit to hydrogenate and then carry out catalytic cracking on LCO fraction. The LTAG technology realizes the maximized production of high-octane gasoline or light aromatic hydrocarbon by designing a hydrogenation LCO conversion area and simultaneously optimizing and matching the technological parameters of hydrogenation and catalytic cracking and the like. RLG or FD2G technology effectively converts poor quality catalytic diesel into high octane gasoline fraction through hydrocracking catalyst and process optimization. The above technology can effectively reduce the catalytic diesel oil and improve the benefit of the catalytic diesel oil. However, due to the aggravation of crude oil deterioration and the increasing strictness of environmental regulations, both raw materials and products of the catalytic cracking unit need to be hydrogenated, so that the hydrogen source of a refinery is seriously insufficient, and the efficient utilization of catalytic cracking cycle oil through hydrogenation re-catalytic cracking or hydrocracking is hindered. In addition, with the increase and continuous energy expansion of oil refineries and the popularization of electric automobiles, the energy production of the oil refining industry mainly based on gasoline and diesel oil production is excessive, and statistics shows that the energy production of the oil refining industry is excessive by 1 hundred million tons in 2016 in China, so that the oil conversion is a necessary trend.

The shortage of domestic petroleum resources and the increasing demand for high-quality gasoline, diesel oil, low-carbon olefin and aromatic hydrocarbon are caused, the content of C9-C11 monocyclic aromatic hydrocarbon in the catalytic cracking cycle oil LCO is higher than 20%, the content of bicyclic aromatic hydrocarbon such as naphthalene, alkyl naphthalene and the like is higher than 30%, and the potential content of BTXN is high, so that the catalyst is one of important chemical raw materials. LCO is directly extracted from aromatic hydrocarbon, and the monocyclic aromatic hydrocarbon has large molecules and is difficult to utilize; the content of the bicyclic aromatic hydrocarbon is high, but the content of the naphthalene is low and is only 1% -3%, and the separation effect is poor. If the aromatics in LCO are to be utilized, catalytic diesel aromatics dealkylation processing is necessary.

The method for producing BTXN by catalytic dealkylation of diesel oil arene includes hydrodealkylation, such as 700-800 deg.C, 2.0-3.0MPa and H for catalytic diesel oil by Daqing petrochemical research institute₂The dealkylated base oil which is reacted for 5 to 10 seconds and has the oil volume ratio of 3000:1 is extracted by dimethyl sulfoxide, the liquid yield of LCO aromatic hydrocarbon feeding reaches 70 percent, the BTX yield is 13 percent, the naphthalene yield is 33 percent, and the methylnaphthalene yield is 14.5 percent. BTXN produced by LCO thermal crackingWidely popularized and applied, the problems are as follows: LCO hydrogen thermal cracking dealkylation reaction temperature is high, coke production is high, liquid yield is low, and utilization rate is low.

In addition, patents CN201510664856.3, CN106588537, CN201410202025.X, CN105085154, CN105085134 and CN105085135 disclose a method for producing benzene and xylene from catalytic cracking light diesel oil or poor quality heavy aromatics by a hydrofining-hydrocracking combined process, wherein 0.05 wt% of Pt-0.15 wtPd-70% of ZSM-5/Al is adopted₂O₃The catalyst has the hydrofining operation pressure of 3.5-10.0MPa, the inlet temperature of 330-; the hydrocracking operating pressure is 2.5-3.0MPa, the inlet temperature is 360-460 ℃, and the hydrogen-oil volume ratio is 400-1000.

The problems with these techniques are: the LCO direct catalytic cracking or hydrocracking method for producing BTX or naphthalene has low concentration, low recovery rate, small scale and large energy consumption, especially the catalyst is easy to coke, which causes the fixed bed reactor to have short production period, and the catalyst needs to be shut down for regeneration or replacement in half a year; the LCO hydrofining-hydrocracking or hydrocracking also has the problem of high hydrogen partial pressure, the hydrogen partial pressure generally reaches more than 2.5MPa, and the high hydrogen partial pressure also leads to high device investment.

Therefore, in order to efficiently utilize the poor LCO resources and meet the increasing demand for chemical raw materials such as low-carbon olefins and aromatics, it is necessary to develop a catalytic conversion method for efficiently dealkylating the poor catalytic cracking cycle oil to produce aromatics BTXN.

Disclosure of Invention

The application provides a method and a device for continuously producing aromatic hydrocarbon by hydrocatalytically cracking FCC circulating oil, the method adopts an alternate fixed bed reactor device to hydrocatalytically crack FCC circulating oil to produce aromatic hydrocarbon such as benzene, toluene, xylene and naphthalene, and the hydrocarbonylation and oxygen-containing regeneration are alternately carried out, so that the efficient continuous production can be realized, the aromatic hydrocarbon yield is high, the coke yield is low, and the utilization rate of the FCC circulating oil is high.

In the method, the FCC cycle oil undergoes dealkylation in an alternate fixed bed reactor unit, wherein the alternate fixed bed reactor unit comprises a first fixed bed reactor and a second fixed bed reactor which are connected in parallel, and the first fixed bed reactor and the second fixed bed reactor are both filled with an aromatic dealkylation catalyst; the method comprises the following steps:

(1) atomizing the FCC cycle oil with an atomizing medium and feeding the atomized FCC cycle oil into a first fixed bed reactor of the alternating fixed bed reactor unit;

(2) in the first fixed bed reactor, in a hydrogen atmosphere, contacting atomized FCC circulating oil with the aromatic hydrocarbon dealkylation catalyst to carry out dealkylation reaction to obtain reaction oil gas;

(3) obtaining the aromatic hydrocarbons from the reaction oil gas;

(4) when the aromatic hydrocarbon dealkylation catalyst in the first fixed bed reactor is coked and deactivated or the activity is reduced, the FCC circulating oil is switched and fed into a second fixed bed reactor, and the dealkylation reaction is carried out in the second fixed bed reactor to obtain reaction oil gas; in the course of carrying out the dealkylation reaction in the second fixed bed reactor, the aromatic dealkylation catalyst in the first fixed bed reactor is regenerated.

In one embodiment, the dealkylation reaction and the regeneration of the aromatics dealkylation catalyst are carried out alternately in a first fixed bed reactor and a second fixed bed reactor.

In one embodiment, the dealkylation conditions are: the reaction temperature is 500-700 ℃, the reaction pressure is 0.2-6.0 MPa, and the feeding volume space velocity is 5/h-1000/h.

In one embodiment, the reaction temperature is 520-680 ℃, the reaction pressure is 1.0-5.0 MPa, and the feeding volume space velocity is 10/h-500/h.

In one embodiment, regenerating the aromatics dealkylation catalyst comprises stripping the catalyst with a gas prior to regenerating the catalyst by contacting the catalyst with an oxygen-containing regeneration gas at a temperature of 500-.

In one embodiment, the atomizing medium comprises a hydrogen-containing gas and/or a non-hydrogen-containing gas, and the atomizing medium contains no or trace amounts of oxygen, wherein the volume fraction of oxygen in the atomizing medium is no greater than 1%.

In one embodiment, the hydrogen-containing gas is selected from one or more of hydrogen, dry gas; the gas containing no hydrogen is selected from one or more of nitrogen and water vapor.

In one embodiment, the FCC cycle oil is a distillate from a catalytic cracking unit having a boiling range of 80 to 360 ℃ and a total aromatics content of 40 to 98 wt.%, based on the total weight of the FCC cycle oil.

In one embodiment, the FCC cycle oil is preheated prior to being fed to the alternating fixed bed reactor arrangement at a temperature of 180-.

In one embodiment, obtaining the aromatics from the reaction oil gas comprises:

introducing the reaction oil gas into a separation device, and separating to obtain cracked gas, dealkylated aromatic oil and oil slurry;

and introducing the dealkylated aromatic oil into an aromatic extraction device to obtain the aromatic hydrocarbon and aromatic hydrocarbon raffinate oil.

In one embodiment, the process further comprises feeding the oil slurry and/or the aromatic raffinate oil to the alternating fixed bed reactor unit.

In one embodiment, the aromatics dealkylation catalyst comprises an active metal component selected from the group consisting of group IA, group IIA, group VIA, VIIA, IB, IIB and one or more of the 4 th and 5 th periodic elements of the transition metals in amounts of from 5 to 50 wt.% on an oxide basis, based on the total weight of the catalyst, a zeolite, a binder and optionally a clay; said zeolite comprising a large pore zeolite and optionally a medium pore zeolite, in an amount of 1 to 50 wt% based on the total weight of said catalyst; the adhesive is selected from silicon dioxide and/or aluminum oxide and accounts for 5-95 wt% of the total weight of the catalyst; the clay comprises 0-70 wt% of the total weight of the catalyst.

In one embodiment, the active metal component includes one or more of Cr, Ni, Mo, Cu, and one or more of an alkali metal K and an alkaline earth metal Mg.

In another aspect, the present application provides an apparatus for continuously producing aromatic hydrocarbons by hydrocatalytically cracking FCC cycle oil, comprising:

the system comprises an alternating fixed bed reactor device, a fixed bed reactor device and a fixed bed reactor device, wherein the alternating fixed bed reactor device comprises a first fixed bed reactor and a second fixed bed reactor which are connected in parallel, and aromatic hydrocarbon dealkylation catalysts are filled in the first fixed bed reactor and the second fixed bed reactor; the first fixed bed reactor and the second fixed bed reactor are provided with a material inlet and a reaction oil gas outlet, and are also provided with a regeneration gas inlet and a regeneration gas outlet;

the separation device comprises a material inlet, a cracked gas outlet, a dealkylated aromatic oil outlet and an oil slurry outlet; the material inlet of the separation device is connected with the reaction oil gas outlets of the first fixed bed reactor and the second fixed bed reactor;

the aromatic hydrocarbon extraction device comprises a material inlet, an aromatic hydrocarbon outlet and an aromatic hydrocarbon raffinate oil outlet, wherein the material inlet of the aromatic hydrocarbon extraction device is communicated with the dealkylated aromatic hydrocarbon oil outlet of the separation device.

In one embodiment, the aromatics raffinate outlet of the aromatics extraction unit is further communicated with the feed inlets of the first and second fixed bed reactors.

In one embodiment, the slurry oil outlet of the separation device is also in communication with the feed inlets of the first and second fixed bed reactors.

Through years of research, the inventor of the invention finds that: (1) the content of C9-C11 monocyclic aromatics in the catalytic cracking cycle oil LCO is higher than 20%, the content of bicyclic aromatics such as naphthalene and alkyl naphthalene is higher than 30%, and BTXN in the LCO can be utilized through a hydrocatalytic cracking dealkylation reaction to supplement aromatic chemical raw materials; (2) the reaction conditions with high reaction temperature and hydrogen and the molecular sieve catalyst with cracking function are favorable for the dealkylation of the aromatic hydrocarbon, the higher the reaction temperature and the higher the activity of the cracking catalyst are, the more favorable the dealkylation of the aromatic hydrocarbon is, however, the higher the reaction temperature and the cracking catalyst with high activity are easy to cause the coking and inactivation of the catalyst; (3) the catalyst containing the metal component and the hydrogen atmosphere can inhibit the coking of the catalyst, the reaction pressure is 0.2-7.0MPa, and the higher the hydrogen partial pressure is, the lower the coke formation is; (4) the regeneration of the coking catalyst needs to be carried out in a high-temperature oxygen-rich system under the pressure of 0.1-0.25 MPa, and the conventional fixed bed hydrogenation device or the fluidized catalytic cracking device is difficult to coordinate the requirements of the hydrocracking and oxygen-rich regeneration of the aromatic hydrocarbon on different reaction atmospheres and reaction pressures.

Based on the discovery, the invention provides a method for producing aromatic hydrocarbon by hydrocatalytically cracking FCC circulating oil in an alternate fixed bed reactor device, in the alternate fixed bed reactor, the aromatic hydrocarbon-rich catalytic cracking circulating oil contacts an aromatic hydrocarbon dealkylation catalyst in a hydrogen atmosphere to carry out hydrocatalytically cracking dealkylation, and aromatic hydrocarbon extraction is carried out after the dealkylation base oil is desulfurized and nitrogen to produce aromatic hydrocarbon such as benzene, toluene, xylene, naphthalene and the like; the coked deactivated catalyst is regenerated in an oxygen-containing atmosphere after being stripped by nitrogen, and the catalyst is recycled. The method can realize the high-efficiency continuous production of aromatic hydrocarbons such as BTX and naphthalene produced by FCC cycle oil hydrocatalytic cracking, and has the advantages of high aromatic hydrocarbon yield, low coke yield and high utilization rate of FCC cycle oil.

According to the invention, an alternate fixed bed reactor system is adopted, the hydrogenation reaction and the oxygen-containing regeneration are alternately carried out, the reaction atmosphere and the reaction pressure are changed, the continuous operation of the aromatics hydrogenation catalytic cracking dealkylation reaction and the coking catalyst oxygen-containing regeneration reactivation reaction under the condition of hydrogen pressure (0.2-6.0 MPa) can be realized, and thus the higher yield of the aromatics product of the catalytic cracking cycle oil is realized.

Compared with the prior art, the invention has the following technical effects:

(1) the FCC circulating oil can be directly subjected to hydrocatalytic cracking dealkylation to produce BTX and naphthalene oil without refining (such as hydrogenation), can be carried out under lower pressure (and further lower hydrogen partial pressure), has short flow and low hydrogen consumption, and realizes long-period continuous production;

(2) by an alternate fixed bed reactor device, the hydrogenation reaction and the oxygen regeneration are alternately carried out, so that the switching of different reaction atmospheres and reaction pressures is realized, namely, the hydrogenation catalytic cracking dealkylation reaction of FCC circulating oil is completed under the hydrogen pressure (0.2-6.0 MPa) in the alternate fixed bed reactor, and the catalyst recovers the activity in the oxygen regeneration atmosphere;

(3) the FCC circulating oil is subjected to hydrocatalytic cracking, the temperature of the dealkylation and hydrocrack reaction of the relatively heavy aromatics is low, the pressure of the dealkylation and catalytic cracking reaction of the relatively heavy aromatics is low, the yield of alkane and coke in the non-hydrocatalytic cracking gas of the FCC circulating oil is low, and the yield of the dealkylated aromatic oil is high and the yield of aromatic hydrocarbon is high;

(4) the alternate fixed bed reactor device needs a plurality of reactors to alternately carry out reaction and regeneration, has simple operation and can be transformed by utilizing the prior fixed bed hydrogenation reactor device.

Drawings

FIG. 1 is a schematic view of an apparatus and material flow direction according to an embodiment of the present invention,

wherein the reference numerals are as follows:

description of the reference numerals

1 fraction oil rich in aromatic hydrocarbon	2 atomizing medium	3 fixed bed reactor I
			4 fixed bed reactor II	5 oxygen-containing regeneration gas	6 flue gas
7 reaction oil gas pipeline	8. Oil-gas separation device	9 cracking gas
			10 dealkylated aromatic oils	11 heavy cycle oil or slurry	12 aromatic hydrocarbon extraction device
13 mixed aromatic hydrocarbons	14 aromatic raffinate oil

Detailed Description

The technical solution of the present invention is further explained below according to specific embodiments. The scope of protection of the invention is not limited to the following examples, which are set forth for illustrative purposes only and are not intended to limit the invention in any way.

The application provides a method for continuously producing aromatic hydrocarbon by hydrocatalytically cracking FCC circulating oil, wherein the FCC circulating oil is subjected to dealkylation reaction in an alternate fixed bed reactor device, wherein the alternate fixed bed reactor device comprises a first fixed bed reactor and a second fixed bed reactor which are connected in parallel, and aromatic hydrocarbon dealkylation catalysts are filled in the first fixed bed reactor and the second fixed bed reactor; the method comprises the following steps:

(2) in the first fixed bed reactor, under the hydrogen atmosphere, the atomized FCC circulating oil contacts the aromatic hydrocarbon dealkylation catalyst to carry out dealkylation reaction, so as to obtain reaction oil gas;

(3) obtaining the aromatic hydrocarbons from the reaction oil gas;

(4) when the aromatic hydrocarbon dealkylation catalyst in the first fixed bed reactor is coked and deactivated or the activity is reduced, the FCC circulating oil is switched and fed into a second fixed bed reactor, and the hydrocatalytic cracking dealkylation reaction is carried out in the second fixed bed reactor to obtain reaction oil gas; in the course of carrying out the dealkylation reaction in the second fixed bed reactor, the aromatic dealkylation catalyst in the first fixed bed reactor is regenerated.

In the present application, "hydrocatalytic cracking" refers to the catalytic cracking of FCC cycle oil in the presence of hydrogen, i.e., in a hydrocarbonic atmosphere, in the presence of a catalyst. The 'hydrogen atmosphere' refers to the existence of hydrogen in the system, wherein the hydrogen accounts for 30-90% of the volume of the system.

In the present application, the alternating fixed bed reactor arrangement comprises at least two fixed bed reactors (including at least a first fixed bed reactor and a second fixed bed reactor) connected in parallel, both the first and second fixed bed reactors being packed with an aromatics dealkylation catalyst. And carrying out the hydrodealkylation catalytic cracking reaction and regenerating the aromatic hydrocarbon dealkylation catalyst in the first fixed bed reactor and the second fixed bed reactor alternately. Of course, a third fixed bed reactor, even a fourth fixed bed reactor, etc. may be included in addition to the first fixed bed reactor and the second fixed bed reactor, so that the hydrodealkylation reaction and the regeneration of the aromatic dealkylation catalyst are alternately performed in all of these fixed bed reactors. However, since the regeneration process of the catalyst is relatively fast, it is preferable that the alternate fixed-bed reactor means includes two fixed-bed reactors connected in parallel, a first fixed-bed reactor and a second fixed-bed reactor, and the hydrodealkylation reaction and the regeneration of the aromatic dealkylation catalyst are alternately performed in the first fixed-bed reactor and the second fixed-bed reactor.

In one embodiment, two fixed bed reactors of an alternating fixed bed reactor arrangement of the present invention are coupled in parallel and arranged in a parallel or vertical orientation. The two fixed bed reactors may be of the same size or of different sizes, and may be of conventional constant diameter or variable diameter. In one embodiment, the fixed bed reactor is a radial, axial, or tubular fixed bed reactor.

In one embodiment, the FCC cycle oil in the present invention is aromatic-rich catalytic cracking cycle oil, which refers to distillate oil with a distillation range of 80-360 ℃ from a catalytic cracking unit, and the total aromatic content is 40-98 wt%, and includes distillate oil directly from the catalytic cracking unit and/or hydrogenated catalytic cracking distillate oil, and aromatic-rich distillate oil from other units, such as reformed heavy aromatic hydrocarbon rich in C9-C11. The distillation range of the catalytic cracking cycle oil can be selected according to the requirement of producing a target aromatic hydrocarbon product, the distillate oil with the distillation range of 150-300 ℃ is preferentially selected for producing monocyclic aromatic hydrocarbon, and the distillate oil with the distillation range of 220-360 ℃ is preferentially selected for producing bicyclic aromatic hydrocarbons such as naphthalene. The hydrogenated catalytic cracking distillate oil can be mixed with the distillate oil directly coming from a catalytic cracking device and/or the distillate oil rich in aromatic hydrocarbon coming from other devices for feeding, or can be fed at the upstream or downstream of the distillate oil directly coming from the catalytic cracking device, preferably at the upstream of the distillate oil directly coming from the catalytic cracking device, and the reaction time is 0.1-10 seconds before the distillate oil directly coming from the catalytic cracking device is fed.

In one embodiment, the atomizing medium comprises a hydrogen-containing gas and/or a non-hydrogen-containing gas, and the atomizing medium contains no or trace amounts of oxygen, wherein the volume fraction of oxygen in the atomizing medium is no greater than 1%. In one embodiment, the hydrogen-containing gas is selected from one or more of hydrogen, dry gas; the gas containing no hydrogen is selected from one or more of nitrogen and water vapor. When a gas containing no hydrogen is used as the atomizing medium, it is necessary to introduce H into the reaction apparatus₂To provide a hydrogen atmosphere. In one embodiment, H₂The volume ratio of/FCC circulating oil is 100-1000.

The aromatic dealkylation catalyst is a bifunctional catalyst consisting of metal and a molecular sieve, and is characterized in that: the metal component of the aromatic hydrocarbon dealkylation catalyst is a metal element of IA group, IIA group, VIA group, VIIA group, IB group and IIB group or transition metal, mainly a metal element of fourth period and fifth period, preferably any one or any two, three or more of secondary group metals of Cr, Ni, Mo, Cu and the like, alkali metal K, alkaline earth metal Mg and the like, and the metal component exists in the form of oxide; the catalyst molecular sieve comprises a large pore zeolite and optionally a medium pore zeolite. Preferably, the catalyst is a composite of a large pore zeolite and optionally an inorganic oxide such as a medium pore zeolite, alumina, silica, and optionally a metal oxide supported on a refractory inorganic oxide support such as a clay, natural porous support material, and the like. The active metal component accounts for 5-50 wt% of the total catalyst, preferably 15-30 wt% in terms of oxide. If the composite metal oxide is used as the active component of the adsorbent, the molar ratio of the transition metal elements in the fourth and fifth periods to the metal elements in the IA group, the IIA group, the VIA group, the VIIA group, the IB group and the IIB group can be selected from 0: 1-0: 100, preferably 1: 1-1: 10. In one embodiment, the catalyst molecular sieve comprises 1 to 50 wt%, preferably 20 to 40 wt% of the total catalyst. The average particle size of the catalyst is 2-8 mm.

In one embodiment, the aromatics dealkylation catalyst comprises an active metal component selected from one or more of group IA, group IIA, group VIA, VIIA, IB, IIB and

transition metals group

4 and 5 period elements (preferably, the active metal component comprises one or more of Cr, Ni, Mo, Cu, and one or more of alkali metal K and alkaline earth metal Mg) in an amount of from 5 to 50 wt%, preferably from 15 to 30 wt%, calculated as oxides, based on the total weight of the catalyst, a zeolite, a binder and optionally a clay.

In one embodiment, the zeolite comprises a large pore zeolite and optionally a medium pore zeolite, and comprises from 1 to 50 weight percent of the total weight of the catalyst. The large pore zeolite accounts for 80-100 wt%, preferably 90-100 wt% of the total weight of the zeolite; the medium pore zeolite constitutes 0 to 20 wt%, preferably 0 to 10 wt%, of the total weight of the zeolite. The large-pore zeolite can be selected from Y series zeolite, including Rare Earth Y (REY), Rare Earth Hydrogen Y (REHY), ultrastable Y obtained by different methods and high-silicon Y. The medium pore zeolite is selected from ZSM series zeolite and/or ZRP zeolite, and can also be modified by nonmetal elements such as phosphorus; the ZSM series zeolite may be selected from one or a mixture of two or more of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and other zeolites of similar structure, and more detailed description of ZSM-5 may be found in U.S. Pat. No. 3,702,886.

In one embodiment, the binder is selected from silica and/or alumina, and is present in an amount of from 5 to 9 weight percent based on the total weight of the catalyst5% by weight. The inorganic oxide may be used as a binder and may be selected from silicon dioxide (SiO)₂) And/or aluminum oxide (Al)₂O₃). In one embodiment, the binder may comprise silica in an amount of 50 to 90 wt.% and alumina in an amount of 10 to 50 wt.%, on a dry weight basis.

In one embodiment, the clay comprises from 0 to 70 weight percent of the total weight of the catalyst. The clay as matrix (i.e. carrier) can be selected from one or more of silica, kaolin and/or halloysite, montmorillonite, diatomite, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite.

Preferably, the large pore and medium pore zeolites, the inorganic oxide binder, the clay, and the like are modified with a transition metal element such as iron, cobalt, and nickel.

The catalyst can be made into spherical, strip or clover-shaped particles or net, honeycomb, fiber and the like; in order to facilitate the reduction of attrition and breakage, the catalyst is preferably in the form of pellets, each of which may have an average particle size of 2 to 8mm, preferably 3 to 6 mm.

In one embodiment, the conditions for the hydrocatalytic cleavage dealkylation are: the reaction temperature is 500-700 ℃, the reaction pressure is 0.2-6.0 MPa, and the feeding volume space velocity is 5/h-1000/h. Preferably, in another embodiment, the reaction temperature is 520-680 ℃, the reaction pressure is 1.0-5.0 MPa, and the feeding volume space velocity is 10/h-500/h. In one embodiment, the reaction temperature is 550-650 ℃, or 550-600 ℃. In another embodiment, the reaction pressure is 1.0 to 3.0MPa, or 1.0 to 2.0 MPa.

In one embodiment, obtaining the aromatics from the reaction oil gas comprises: introducing the reaction oil gas into a separation device, and separating to obtain cracked gas, dealkylated aromatic oil and oil slurry; and introducing the dealkylated aromatic oil into an aromatic extraction device to obtain aromatic hydrocarbon and aromatic hydrocarbon raffinate oil. In the present application, "separation system", "oil and gas separation system" and "separation device" have the same meaning; the term "aromatics extraction unit" is also synonymous with the term "aromatics extraction system".

In the present invention, the reaction oil gas is fed into a separation device to perform product separation, for example, the product is separated into the dealkanized aromatic oil, slurry oil and cracked gas such as propylene, etc., which are well known to those skilled in the art, and fractionation, rectification, etc. may be used. The distillation range of the dealkanized aromatic oil and the like can be adjusted as required.

In the present invention, a method of extracting aromatics from the dealkanized aromatic oil in an aromatics extraction apparatus is also well known to those of ordinary skill in the art. In one embodiment, the dealkylated aromatic oil is subjected to aromatic extraction by one aromatic extraction unit and/or a plurality of identical/different aromatic extraction units, the aromatic extraction solvent comprises a conventional solvent and a plasma solvent, and the aromatic mixture obtained by aromatic extraction is further subjected to aromatic separation to obtain BTX (benzene-toluene-xylene) monocyclic aromatic hydrocarbon and bicyclic aromatic hydrocarbons such as naphthalene and dimethylnaphthalene. In one embodiment, the dealkylated aromatic oil is further treated to remove impurities such as nitrides and sulfides before the dealkylated aromatic oil is subjected to aromatic extraction, and this may be by adsorption and/or selective hydrogenation, preferably adsorption. In one embodiment, the impurity-removed dealkylated aromatic oil has an impurity level of nitrides, sulfides, etc. of no greater than 30 micrograms/gram, preferably no greater than 10 micrograms/gram.

In one embodiment, the slurry oil and/or the aromatic raffinate oil may also be fed to the alternating fixed bed reactor unit to further process these streams to increase the yield of high value aromatics.

In one embodiment, when the aromatics dealkylation catalyst in the first fixed bed reactor is coked out or has reduced activity, the FCC cycle oil is switched to be fed to a second fixed bed reactor, and the dealkylation reaction is carried out in the second fixed bed reactor to obtain reaction oil gas; in the course of carrying out the dealkylation reaction in the second fixed bed reactor, the aromatic dealkylation catalyst in the first fixed bed reactor is regenerated. And when the catalyst of the second fixed bed reactor is coked and deactivated or the activity is reduced, switching and feeding the FCC circulating oil into the first fixed bed reactor, performing the dealkylation reaction in the first fixed bed reactor, and simultaneously regenerating the aromatic hydrocarbon dealkylation catalyst in the second fixed bed reactor. Thereby, the hydrodealkylation reaction and the regeneration of the aromatic hydrocarbon dealkylation catalyst are alternately carried out in the first fixed bed reactor and the second fixed bed reactor.

In one embodiment, regenerating the aromatics dealkylation catalyst comprises stripping the catalyst with a gas prior to regenerating the catalyst by contacting the catalyst with an oxygen-containing regeneration gas at a temperature of 500-. The gas used for stripping the catalyst is not particularly limited and may be nitrogen or the like. In the regeneration process, the regeneration gas can be one or more of air, oxygen and oxygen-containing gas, and the regeneration temperature can be 500-700 ℃, preferably 540-640 ℃.

The application also relates to a device for continuously producing aromatic hydrocarbon by hydrocatalytically cracking FCC circulating oil, which comprises:

In one embodiment, the aromatics raffinate outlet of the aromatics extraction unit is further communicated with the feed inlets of the first and second fixed bed reactors. In another embodiment, the slurry oil outlet of the separation device is also in communication with the feed inlets of the first and second fixed bed reactors.

FIG. 1 is a schematic illustration of the apparatus and material flow in one embodiment of the present invention, in which an alternating fixed bed reactor apparatus consisting of two fixed bed reactors is used. The device includes:

the system comprises an alternating fixed bed reactor device, a fixed bed reactor device and a fixed bed reactor device, wherein the alternating fixed bed reactor device comprises a first fixed bed reactor 3 and a second fixed bed reactor 4 which are connected in parallel, and aromatic hydrocarbon dealkylation catalysts are filled in the first fixed bed reactor and the second fixed bed reactor; the first fixed bed reactor and the second fixed bed reactor are provided with a material inlet and a reaction oil gas outlet, and are also provided with a regeneration gas inlet and a regeneration gas outlet;

a separation device 8, which comprises a material inlet, a cracked gas outlet, a dealkylated aromatic oil outlet and an oil slurry outlet; the material inlet of the separation device is connected with the reaction oil gas outlets of the first fixed bed reactor and the second fixed bed reactor through a pipeline 7;

and the aromatic hydrocarbon extraction device 12 comprises a material inlet, an aromatic hydrocarbon outlet and an aromatic hydrocarbon raffinate oil outlet, wherein the material inlet of the aromatic hydrocarbon extraction device is communicated with the dealkylated aromatic hydrocarbon oil outlet of the separation device, and the aromatic hydrocarbon raffinate oil outlet of the aromatic hydrocarbon extraction device is also communicated with the material inlets of the first fixed bed reactor and the second fixed bed reactor.

In the apparatus shown in FIG. 1, the feed inlets of the first and second fixed bed reactors are disposed at the lower part of the reactor and are communicated with the feed lines of the respective feeds (FCC cycle oil, atomizing medium, etc.). The reaction oil gas outlet is arranged at the top of the reactor and is connected with the material inlet of the separation device 8 through a reaction oil gas pipeline 7. The first and second fixed bed reactors are also provided with a regeneration gas inlet and outlet for introducing stripping gas and regeneration gas and discharging treated gas out of the reactors.

FCC cycle oil (such as distillate oil rich in aromatic hydrocarbon) is subjected to hydrocatalytic dealkylation in one of the fixed bed reactors, when the fixed bed reactor is deactivated due to catalyst coking and the yield of target product aromatic hydrocarbon is greatly reduced, the feeding is stopped, and the FCC cycle oil feeding is switched to the other of the alternate fixed bed reactors, dealkylation reaction is carried out in the reactor, and the catalyst in the first reactor is regenerated on line. Thus, reaction and regeneration are alternately carried out in alternating fixed bed reactors. The process flow is as follows:

FCC cycle oil (e.g. aromatic-rich distillate) 1 is subjected to hydrodealkylation in a fixed bed reactor I3: FCC circulating oil (such as aromatic hydrocarbon-rich distillate oil) 1 is injected into the bottom of the fixed bed reactor I3, ascends along with the atomizing medium 2, contacts with the catalyst and carries out the dealkylation reaction of the hydrocatalytic cracking reaction; the reacted oil gas enters an oil-gas separation device 8 through a pipeline 7 to obtain a cracking gas 9, dealkylated aromatic oil 10 and heavy cycle oil or oil slurry 11; the dealkylated aromatic oil is further subjected to aromatic extraction in an aromatic extraction system 12 to obtain mixed aromatic hydrocarbon 13 containing benzene, toluene, xylene, naphthalene, methylnaphthalene and the like and aromatic raffinate oil 14; the aromatic raffinate oil 14 is preferably recycled, part of the gas alkane in the cracking gas 9 can be selected to be recycled to the reactor as a hydrogen-containing fluidizing medium or a pre-lifting medium according to needs, and the oil slurry 11 is selectively recycled or not recycled according to needs. After reacting for a period of time, if the yield of the target product aromatic hydrocarbon is lower than a preset value (for example, lower than 70% of the initial reaction period), switching to feed the fixed bed reactor II4 for the cracking dealkylation reaction; the catalyst in the fixed bed reactor I3 is contacted with oxygen-containing regeneration gas 5 for regeneration, the regeneration temperature is 500 ℃ and 640 ℃, and the regenerated catalyst is recycled. Similarly, when the yield of the target product aromatic hydrocarbon in the case of using the fixed bed reactor II4 is lower than a predetermined value (for example, 70% of the initial stage of the reaction), the feed is switched to the fixed bed reactor I3 for the cracking dealkylation reaction; meanwhile, the catalyst in the fixed bed reactor II4 is contacted with oxygen-containing regeneration gas 5 for regeneration, the regeneration temperature is 500-640 ℃, the regenerated catalyst is recycled, and the flue gas 6 is discharged. Thereby, regeneration and reaction are alternately carried out in the two reactors of an alternating fixed bed reactor arrangement.

In this embodiment, FCC cycle oil (e.g., aromatics-rich distillate) 1 refers primarily to distillate directly from a catalytic cracking unit and/or aromatics-rich distillate from other units such as reformed heavy aromatics rich in C9-C11 aromatics; the hydrogenated catalytically cracked distillate may be fed as a blend with the distillate directly from the catalytic cracker and/or with FCC cycle oil (e.g. aromatics rich distillate) 1 from other units, depending on the production requirements.

The following examples further illustrate the process but are not intended to limit it. The properties of the feedstock catalytically cracked cycle oil used in the examples are shown in table 1.

The catalysts used in the examples are the same and the preparation is briefly as follows:

1) 20kgNH₄Cl is dissolved in 1000kg water, 100kg (dry basis) of crystallized DASY zeolite (manufactured by catalyst works of Qilu petrochemical company, 2.445-2.448nm, RE content₂O₃2.0 wt%), exchanged at 90 deg.C for 0.5h, filtered to obtain filter cake; 94.0kgCr (NO) was added₃)₃·9H₂Dissolving O in 540kg of water, mixing with the filter cake, soaking and drying; then roasting at 550 deg.C for 2 hr to obtain chromium-containing macroporous zeolite with elemental analysis chemical composition of 0.1Na₂O·5.1Al₂O₃·19.0Cr₂O₃·3.8RE₂O₃·88.1SiO₂。

2) Pulping 75.4Kg of halloysite (industrial product of Suzhou china clay company, with a solid content of 71.6 m%) with 250Kg of decationized water, adding 54.8Kg of pseudo-boehmite (industrial product of Shandong aluminum plant, with a solid content of 63 m%), adjusting the pH to 2-4 with hydrochloric acid, stirring uniformly, standing and aging at 60-70 deg.C for 1 hour, maintaining the pH at 2-4, cooling to below 60 deg.C, adding 41.5Kg of alumina sol (product of catalyst plant of Qilu petrochemical company, Al)₂O₃Content 21.7 m%), and stirred for 40 minutes to obtain a mixed slurry.

3) The chromium-containing large-pore zeolite prepared in the step 1) (33.8 kg on a dry basis) and MFI structure medium-pore ZRP-1 zeolite (industrial product of catalyst plant of Qilu petrochemical company, SiO)₂/Al₂O₃30 dry basis of 3.0kg) was added to the mixed slurry obtained in step 2), stirred uniformly, and 4.0g of a commercial alumina binder was added, mixed and placed in a bonder, an appropriate amount of water was added, stirred sufficiently and uniformly, placed in the air for 4 hours, ball-rolled by a ball roller, dried in a drying oven at 120 ℃ for 3 hours, washed with a solution of ammonium dihydrogen phosphate (phosphorus content: 1 m%), and free Na was washed off⁺Washing to remove free Na⁺And drying again to obtain the catalyst CAT-1 (the average particle size is 4-6 mm). The catalyst consists of chromium oxide 7.4 wt%, MFI structure mesoporous zeolite 2.2 wt%, DASY zeolite 20.6 wt%, pseudoboehmite 24.8 wt%, alumina sol 6.5 wt% and kaolin for the rest. The properties are shown in Table 2.

Example 1

This example was tested according to the apparatus and flow scheme of figure 1 using FCC cycle oil a in table 1 as feed on an alternating fixed bed reactor unit using CAT-1 catalyst with catalyst MAT 66. This alternate fixed bed reactor device includes two fixed bed reactors I and II, and two fixed bed reactors have the same structure, are tubular reactor, and the reactor size is diameter 30 millimeters, and length 1600 millimeters, and the loading of catalyst is 30 milliliters in fixed bed reactor I and II.

Preheating FCC circulating oil A at 160 ℃, then feeding the FCC circulating oil A into the bottom of a fixed bed reactor I, and reacting under the pressure of 0.2MPa and H₂The volume ratio of the circulating oil/FCC is 500, the circulating oil flows from bottom to top along with the hydrogen-containing fluidized medium, contacts with the catalyst, and performs the catalytic hydrodealkylation reaction at the reaction temperature (based on the middle part of the reactor) of 540 ℃ and the feeding volume space velocity of 30/hour; the reaction oil gas is separated by a separation device to obtain a gas product and dealkylated aromatic oil, the dealkylated aromatic oil is desulfurized and subjected to aromatic extraction after nitrogen to obtain high-value aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene and the like,and (5) recycling 100% of the aromatic raffinate oil. After reacting for a period of time, switching the feed to the fixed bed reactor II for a cracking dealkylation reaction, wherein the yield of the target product aromatic hydrocarbon is lower than 70% of the initial reaction period due to coking of the spent catalyst; the coking catalyst in the fixed bed reactor I is contacted with air for regeneration at the regeneration temperature of 540 ℃ and 640 ℃, and the regenerated catalyst is recycled. The operating conditions and the product distribution are listed in Table 3.

As can be seen from table 3, in example 1, the recycle FCC oil rich in monocyclic aromatic hydrocarbon is hydrodecatalytically cracked and dealkylated in the alternating fixed bed reactor unit, the yield of the dealkylated base oil is 81.67 wt%, the yield of BTX is 27.60 wt%, the yield of naphthalene is 12.66 wt%, the yield of methylnaphthalene is 3.23 wt%, and the yield of trienes (lower olefins ethylene + propylene + butylene) is 7.37 wt%; the yield of the slurry oil is 0.23 wt%, and the yield of the coke is 4.86 wt%; the total yield of high value aromatics (BTXN) such as benzene, toluene, xylene and naphthalene was 43.49 wt%.

Comparative example 1

Catalytic cracking was carried out by the same method and apparatus as in example 1, except that in comparative example 1: non-hydrocatalytic cracking, wherein fluidizing medium is water vapor and nitrogen without hydrogen; the catalyst and the process conditions are the same as those in the example 1, under the reaction pressure of 0.2MPa, the FCC circulating oil A flows from bottom to top along with the non-hydrogen-containing fluidized medium and contacts with the catalyst, the non-hydrocatalytic cracking dealkylation reaction is carried out under the conditions that the reaction temperature is 540 ℃ and the feeding volume space velocity is 30/hour, and the weight ratio of the steam to the total raw material is 5 percent; and (3) separating the reaction oil gas by a separation device to obtain a gas product and dealkylated aromatic oil, desulfurizing the dealkylated aromatic oil, extracting aromatic hydrocarbon after nitrogen to obtain high-value aromatic hydrocarbon such as benzene, toluene, xylene and naphthalene, and refining 100% of the raffinate oil of the aromatic hydrocarbon. After reacting for a period of time, switching the feed to the fixed bed reactor II for a cracking dealkylation reaction, wherein the yield of the target product aromatic hydrocarbon is lower than 70% of the initial reaction period due to coking of the spent catalyst; the coking catalyst in the fixed bed reactor I is contacted with air for regeneration at the regeneration temperature of 540 ℃ and 640 ℃, and the regenerated catalyst is recycled. The operating conditions and the product distribution are listed in Table 3.

As can be seen from table 3, compared with comparative example 1 (non-hydrocatalytic cracking), the yield of BTX, naphthalene and low carbon olefins in example 1 (hydrocatalytic cracking) is high, the recycle ratio of the aromatic raffinate oil is low, the yield of slurry oil and coke is low, the yields of BTX, naphthalene and low carbon olefins are respectively increased by 11.55, 10.37 and 1.29 percentage points, and the yields of slurry oil and coke are respectively decreased by 0.26 and 0.88 percentage points.

Example 2

The example was tested according to the apparatus and flow scheme of figure 1 using FCC cycle oil B in table 1 as feed on a fixed bed reactor unit using CAT-1 catalyst with catalyst MAT 66. This fixed bed reactor device includes two fixed bed reactors I and II, and two fixed bed reactors have the same structure, are tubular reactor, and the reactor size is diameter 30 millimeters, and length 1600 millimeters, and the loading of catalyst is 15 milliliters in fixed bed reactor I and II.

Preheating FCC circulating oil B at 260 ℃, then feeding the FCC circulating oil B into the bottom of a fixed bed reactor I, contacting with a catalyst, and reacting under the reaction pressure of 6.0MPa and H₂The volume ratio of the circulating oil is 1000, and the hydrodealkylation reaction is carried out under the conditions that the reaction temperature is 680 ℃ and the feeding volume space velocity is 70/hour along with the flowing of the hydrogen-containing fluidized medium from bottom to top; and (3) separating the reaction oil gas by a separation device to obtain a gas product, dealkylated aromatic oil and slurry oil, desulfurizing the dealkylated aromatic oil, extracting aromatic hydrocarbon after nitrogen to obtain high-value aromatic hydrocarbon such as benzene, toluene, xylene and naphthalene, and refining the raffinate oil of the aromatic hydrocarbon by 100%. After reacting for a period of time, switching the feed to the fixed bed reactor II for a cracking dealkylation reaction, wherein the yield of the target product aromatic hydrocarbon is lower than 70% of the initial reaction period due to coking of the spent catalyst; the coking catalyst in the fixed bed reactor I is contacted with air for regeneration at the regeneration temperature of 540 ℃ and 640 ℃, and the regenerated catalyst is recycled. The operating conditions and the product distribution are listed in Table 4.

As can be seen from table 4, in example 2, the FCC cycle oil rich in bicyclic aromatic hydrocarbons is hydrodecatalytically cracked and dealkylated in the alternating fixed bed reactor, the yield of dealkylated base oil is 70.03 wt%, the yield of BTX is 7.28 wt%, the yield of naphthalene is 40.90 wt%, the yield of methylnaphthalene is 10.99 wt%, and the yield of trienes (low-carbon olefins ethylene + propylene + butylene) is 11.18 wt%; the yield of the slurry oil is 2.01 wt%, and the yield of the coke is 7.82 wt%; the overall yield of high value aromatics (BTXN) such as benzene, toluene, xylene and naphthalene was 59.18 wt%.

Comparative example 2

Catalytic cracking was performed by the same method as in example 2, except that in comparative example 2, only the fixed bed reactor I of the alternate fixed bed reactor set was used, the reactor I was free of catalyst, and external heating, i.e., electric heating, was used to maintain the reaction temperature.

In comparative example 2, the hydrocracking was carried out using hydrogen-containing hydrogen and dry catalytic cracking gas as the fluidizing medium under the same process conditions as in example 2 at a reaction pressure of 5.0MPa and H₂The volume ratio of circulating oil is 1000, FCC circulating oil B enters the bottom of a fixed bed reactor I after being preheated at 260 ℃, then flows from bottom to top along with a hydrogen-containing fluidized medium, and is subjected to a hydrocracking dealkylation reaction under the conditions that the reaction temperature is 680 ℃ and the empty tube feeding volume airspeed of a constant temperature region is 70/hour; and (3) separating the reaction oil gas by a separation device to obtain a gas product, dealkylated aromatic oil and slurry oil, desulfurizing the dealkylated aromatic oil, extracting aromatic hydrocarbon after nitrogen to obtain high-value aromatic hydrocarbon such as benzene, toluene, xylene and naphthalene, and refining the raffinate oil of the aromatic hydrocarbon by 100%. The operating conditions and the product distribution are listed in Table 4.

As can be seen from table 4, compared with the comparative example 2 (hydrocracked), the BTX, naphthalene and low carbon olefins yield of example 2 (hydrocracked) is high, the aromatics raffinate oil recycle ratio is low, the slurry oil and coke yield is low, the BTX, naphthalene and low carbon olefins yield is respectively increased by 3.84, 8.23 and 3.99 percentage points, and the slurry oil and coke yield is respectively decreased by 0.71 and 3.81 percentage points.

Example 3

This example was tested according to the apparatus and procedure of figure 1 (apparatus as in example 1) using 30 wt% FCC cycle oil a and 70 wt% hydrogenated FCC cycle oil C of table 1 as feed on an alternating fixed bed reactor using CAT-1 catalyst with catalyst MAT 66.

Preheating FCC circulating oil A at 200 ℃, then feeding the preheated FCC circulating oil A into the bottom of an alternate fixed bed reactor, and hydrogenating FCC circulating oil C on the FCC circulating oil AThe free feed firstly contacts with a high-temperature regenerant, the FCC cycle oil A and the hydrogenated FCC cycle oil C contact with a catalyst to react, and H is carried out under the reaction pressure of 1.8MPa₂The volume ratio of the circulating oil is 800, the hydrogen-containing fluidized medium flows from bottom to top, and the hydrodealkylation reaction is carried out under the conditions of the reaction temperature of 560 ℃ and the feeding volume space velocity of 140/hour; and (3) separating the reaction oil gas by a separation device to obtain a gas product and dealkylated aromatic oil, desulfurizing the dealkylated aromatic oil, extracting aromatic hydrocarbon after nitrogen to obtain high-value aromatic hydrocarbon such as benzene, toluene, xylene and naphthalene, and refining 100% of the raffinate oil of the aromatic hydrocarbon. After reacting for a period of time, switching the feed to the fixed bed reactor II for a cracking dealkylation reaction, wherein the yield of the target product aromatic hydrocarbon is lower than 70% of the initial reaction period due to coking of the spent catalyst; the coking catalyst in the fixed bed reactor I is contacted with air for regeneration at the regeneration temperature of 540 ℃ and 640 ℃, and the regenerated catalyst is recycled. The operating conditions and the product distribution are listed in Table 5.

As can be seen from table 5, in example 3, the yield of the dealkylated base oil is 77.95 wt%, the yield of BTX is 28.69 wt%, the yield of naphthalene is 7.05 wt%, the yield of methylnaphthalene is 3.13 wt%, and the yield of trienes (low-carbon olefins ethylene + propylene + butylene) is 8.55 wt% when the monocyclic aromatic hydrocarbon-rich FCC cycle oil and the hydrogenated FCC cycle oil are subjected to hydrodecatalytic cracking dealkylation in the alternating fixed bed reactor; the yield of the slurry oil is 0.62 percent by weight, and the yield of the coke is 4.86 percent by weight; the overall yield of high value aromatics (BTXN) such as benzene, toluene, xylene and naphthalene was 38.87 wt%.

Comparative example 3

Catalytic cracking was carried out by the same apparatus and flow scheme as in example 3, except that in comparative example 3: non-hydrocatalytic cracking, wherein fluidizing medium is water vapor and nitrogen without hydrogen; the catalyst and the process conditions are the same as those in the example 3, the hydrogenated FCC cycle oil C is fed at the upstream of the FCC cycle oil A under the reaction pressure of 1.8MPa, the hydrogenated FCC cycle oil C contacts with the catalyst to react, the non-hydrocatalytic cracking dealkylation reaction is carried out under the reaction pressure of 1.8MPa along with the downward flow of a fluidizing medium under the conditions of the reaction temperature of 560 ℃ and the feeding volume space velocity of 140/hour, and the weight ratio of water vapor to the total raw material is 10 percent; and (3) separating the reaction oil gas by a separation device to obtain a gas product and dealkylated aromatic oil, desulfurizing the dealkylated aromatic oil, extracting aromatic hydrocarbon after nitrogen to obtain high-value aromatic hydrocarbon such as benzene, toluene, xylene and naphthalene, and refining 100% of the raffinate oil of the aromatic hydrocarbon. After reacting for a period of time, switching the feed to the fixed bed reactor II for a cracking dealkylation reaction, wherein the yield of the target product aromatic hydrocarbon is lower than 70% of the initial reaction period due to coking of the spent catalyst; the coking catalyst in the fixed bed reactor I is contacted with air for regeneration at the regeneration temperature of 540 ℃ and 640 ℃, and the regenerated catalyst is recycled. The operating conditions and the product distribution are listed in Table 5.

As can be seen from table 5, compared with comparative example 3 (non-hydrocatalytic cracking), example 3 (hydrocatalytic cracking) has high yields of BTX, naphthalene and low carbon olefins, low recycle ratio of aromatic raffinate oil, and low yields of slurry oil and coke, the yields of BTX, naphthalene and low carbon olefins are respectively increased by 8.32, 4.46 and 1.77 percentage points, and the yields of slurry oil and coke are respectively decreased by 0.33 and 1.35 percentage points.

TABLE 1

Raw oil name	FCC cycle oil	FCC cycle oil	Hydrogenated FCC cycle oil
				Raw oil numbering	A	B	C
Density (20 deg.C), kg/m³	876	939	912
				Sulfur content, wt.%	0.19	0.56	0.01
Nitrogen content, weight%	0.052	0.16	0.01
				Composition of hydrocarbons
Saturated hydrocarbon, weight%	19.8	17.2	23.4
				Monocyclic aromatic hydrocarbon, by weight%	60.3	16.6	64.3
Bicyclic aromatic hydrocarbon, weight%	19.6	64.8	11.2
				Tricyclic aromatic hydrocarbons, by weight%	0.3	1.4	1.1
Distillation range, deg.C
				Initial boiling point	168	210	176
10％	206	242	208
				50％	219	284	243
90％	224	339	300
				End point of distillation	245	357	342

TABLE 2

TABLE 3

	Example 1	Comparative example 1
			Raw oil	A	A
Reaction mode	Hydrocatalytic cracking	Non-hydrocatalytic cracking
			Name of catalyst	CAT-1	CAT-1
Catalyst Activity (MAT)	64	64
			Recycle ratio of aromatic raffinate oil	0.05	0.10
Reaction operating conditions
			Reaction pressure, MPa	0.2	0.2
Partial pressure of hydrogen, MPa	0.1	-
			Reactor inlet temperature,. deg.C	580	580
Middle temperature of the reactor, deg.C	540	540
			Reactor outlet temperature,. deg.C	520	520
Space velocity of feed volume, h^-1	30	30
			H₂Volume ratio of circulating oil	500	-
Water vapor/total raw material weight ratio%	-	2.0
			Product yield, weight%
Cracked gas	14.65	12.46
			Wherein the triene	8.23	6.45
Gaseous alkane	6.42	6.01
			Dealkylated base oil	81.82	82.71
Wherein BTX	28.23	16.54
			Naphthalene	13.09	2.48
Methylnaphthalene	3.27	9.93
			Oil slurry	0.11	0.28
Coke	3.42	4.55
			Total up to	100.00	100.00
BTXN yield	44.59	28.95

TABLE 4

TABLE 5

It should be noted by those skilled in the art that the described embodiments of the present invention are merely exemplary and that various other substitutions, alterations, and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited to the above-described embodiments, but is only limited by the claims.

Claims

1. A method for continuously producing aromatic hydrocarbon by hydrocatalytically cracking FCC circulating oil, wherein the FCC circulating oil is subjected to dealkylation reaction in an alternate fixed bed reactor device, wherein the alternate fixed bed reactor device comprises a first fixed bed reactor and a second fixed bed reactor which are connected in parallel, and aromatic hydrocarbon dealkylation catalysts are filled in the first fixed bed reactor and the second fixed bed reactor; the method comprises the following steps:

(3) obtaining the aromatic hydrocarbons from the reaction oil gas;

2. The process of claim 1, wherein the conducting the dealkylation reaction and the regenerating the aromatics dealkylation catalyst are performed alternately in a first fixed bed reactor and a second fixed bed reactor.

3. The process of claim 1, wherein the dealkylation conditions are: the reaction temperature is 500-700 ℃, the reaction pressure is 0.2-6.0 MPa, and the feeding volume space velocity is 5/h-1000/h.

4. The method of claim 3, wherein the reaction temperature is 520 to 680 ℃, the reaction pressure is 1.0 to 5.0MPa, the reaction time is 3 to 30 seconds, and the feed volume space velocity is 10/hr to 500/hr.

5. The process as claimed in claim 1, wherein the regenerating the aromatic dealkylation catalyst comprises stripping the catalyst with a gas and then regenerating the catalyst by contacting the catalyst with an oxygen-containing regeneration gas at a temperature of 500 ℃ and 640 ℃ and a pressure of 0.2 to 2.0 MPa.

6. The method of claim 1, wherein the atomizing medium comprises a hydrogen-containing gas and/or a hydrogen-free gas, the atomizing medium containing no or trace amounts of oxygen, wherein the volume fraction of oxygen in the atomizing medium is no greater than 1%.

7. The method of claim 6, wherein the hydrogen-containing gas is selected from one or more of hydrogen, dry gas; the gas containing no hydrogen is selected from one or more of nitrogen and water vapor.

8. The process of claim 1, wherein the FCC cycle oil is a distillate from a catalytic cracker having a boiling range of 80-360 ℃ and a total aromatics content of 40-98 wt.%, based on the total weight of the FCC cycle oil.

9. The process as claimed in claim 1, wherein the FCC cycle oil is preheated prior to feeding to the alternating fixed bed reactor unit, the temperature of the preheating being 180-400 ℃, preferably 200-360 ℃.

10. The method of claim 1, wherein obtaining the aromatics from the reaction oil gas comprises:

11. The process of claim 10, further comprising feeding the oil slurry and/or the aromatic raffinate oil to the alternating fixed bed reactor arrangement.

12. The process of claim 1 wherein the aromatics dealkylation catalyst comprises an active metal component, a zeolite, a binder and optionally a clay; wherein the active metal component is selected from one or more of elements of 4 th period and elements of 5 th period of IA group, IIA group, VIA group, VIIA group, IB group, IIB group and transition metal, and accounts for 5-50 wt% of the total weight of the catalyst calculated by oxide; said zeolite comprising a large pore zeolite and optionally a medium pore zeolite, in an amount of 1 to 50 wt% based on the total weight of said catalyst; the adhesive is selected from silicon dioxide and/or aluminum oxide and accounts for 5-95 wt% of the total weight of the catalyst; the clay comprises 0-70 wt% of the total weight of the catalyst.

13. The method of claim 12, wherein the active metal component comprises one or more of Cr, Ni, Mo, Cu, and one or more of an alkali metal K and an alkaline earth metal Mg.

14. The process of claim 12, wherein the catalyst has an average particle size of 2-8 mm.

15. Device of full production arene of FCC circulating oil of hydrocatalytic pyrolysis, include:

16. The apparatus of claim 15 wherein the aromatics raffinate outlet of the aromatics extraction unit is further in communication with the feed inlets of the first and second fixed bed reactors.

17. The apparatus according to claim 15, wherein the slurry oil outlet of the separation device is further in communication with the feed inlets of the first and second fixed bed reactors.