CN110642665A - C9+Process for producing dimethylbenzene from heavy aromatic hydrocarbon - Google Patents

C9+Process for producing dimethylbenzene from heavy aromatic hydrocarbon Download PDF

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CN110642665A
CN110642665A CN201810674897.4A CN201810674897A CN110642665A CN 110642665 A CN110642665 A CN 110642665A CN 201810674897 A CN201810674897 A CN 201810674897A CN 110642665 A CN110642665 A CN 110642665A
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aromatic hydrocarbon
toluene
heavy
xylene
benzene
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CN110642665B (en
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李华英
李经球
杨德琴
孔德金
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Sinopec Shanghai Research Institute of Petrochemical Technology
China Petrochemical Corp
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Sinopec Shanghai Research Institute of Petrochemical Technology
China Petrochemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C4/00—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms
    • C07C4/08—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule
    • C07C4/12—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule from hydrocarbons containing a six-membered aromatic ring, e.g. propyltoluene to vinyltoluene
    • C07C4/14—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule from hydrocarbons containing a six-membered aromatic ring, e.g. propyltoluene to vinyltoluene splitting taking place at an aromatic-aliphatic bond
    • C07C4/18—Catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/24—Chromium, molybdenum or tungsten
    • B01J23/28—Molybdenum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/24—Chromium, molybdenum or tungsten
    • B01J23/30—Tungsten
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/74—Iron group metals
    • B01J23/755—Nickel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

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Abstract

C9 +A process for producing xylenes from heavy aromatics comprising: c9 +Separating low-boiling-point heavy aromatic hydrocarbon and high-boiling-point heavy aromatic hydrocarbon from the heavy aromatic hydrocarbon in a heavy aromatic hydrocarbon separation tower; in the presence of hydrogen, low-boiling point heavy aromatic hydrocarbon is in contact reaction with a hydrodealkylation and transalkylation catalyst in a hydrodealkylation and transalkylation reaction unit to obtain a material flow containing benzene, toluene, xylene aromatic hydrocarbon, non-aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and hydrogen; containing benzene, toluene, xylene aromatic hydrocarbon, non-aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and hydrogenThe flow is sequentially separated into hydrogen, non-aromatic hydrocarbon, benzene, toluene, xylene aromatic hydrocarbon products and unreacted heavy aromatic hydrocarbon in a gas-liquid separator, a stripping tower, a benzene separating tower, a toluene separating tower and a xylene separating tower.

Description

C9+Process for producing dimethylbenzene from heavy aromatic hydrocarbon
Technical Field
The invention relates to C9 +A process method for producing dimethylbenzene from heavy aromatics.
Background
Benzene, toluene, xylene and C can be obtained in the naphtha reforming and cracking process9 +Heavy aromatics, the demand for benzene and xylene has increased rapidly in recent years due to advances in the plastics, synthetic fibers and synthetic rubber industries, and are also much more commercially available than other aromatics, and xylene is generally available at a higher price>Benzene and its derivatives>Toluene>C9 +Heavy aromatics. The method for increasing the yield of the aromatic hydrocarbon with high value by adopting the low-value aromatic hydrocarbon is an effective means for fully utilizing aromatic hydrocarbon resources. Up to now, there are many countries that use toluene and C9 +There has been a great deal of research and effort directed to the production of xylenes from heavy aromatics with some success.
By-product of catalytic reforming unit in oil refinery and large amount of C9 +Heavy aromatics, a part of which is sold at low price or blended as fuel oil for a long time, cause resource waste and environmental pollution. In order to meet the quality upgrading requirement of the gasoline at home in the future, C in the gasoline component9 +The content of heavy aromatic hydrocarbon is further reduced, and how to solve the problem of C extruded due to oil upgrading9 +Heavy aromatics are an imminent problem. The heavy components are converted into BTX by a heavy aromatics conversion technology, so that an economical and feasible process route is provided, and the problems of excessive aromatics and insufficient BTX production raw materials caused by gasoline upgrading can be solved.
The heavy arene lightening technology mainly comprises a hydrodealkylation reaction to finally generate benzene, toluene and xylene. However, the heavy aromatics are mainly prepared into light aromatics by pyrolysis or catalytic dealkylation, so that the utilization rate of side chain methyl capable of effectively increasing the yield of xylene is low, the aromatic hydrocarbon loss is large, the selectivity of target products of xylene is low, the technical and economic indexes are poor, and the commercialization is limited.
USP5,001,296 discloses a process for the catalytic hydrodealkylation of aromatic hydrocarbons. The methodUnder the condition of noble metal catalyst, C can be reacted under the reaction conditions of 315 plus 482 ℃, 200PSIG, 2.5 liquid hourly space velocity and 2000 standard ruler 3/petroleum barrel hydrogen circulation rate9 +Conversion of a feedstock with a heavy aromatics content of 96.8 mol% to BTX, the reactivity of which is C9 +Calculated as 21.0-82.0 mol%, the selectivity of benzene product is 16.0-45.8 mol%, the selectivity of toluene product is 5.8-15.4 mol%, and the selectivity of xylene product is only 7.8-24.1 mol%, i.e. the method mainly obtains benzene product.
CN1117404 discloses a catalyst for producing BTX by light-weight of heavy aromatics and a light-weight method thereof, wherein the catalyst is prepared at the temperature of 350-450 ℃, the MPA temperature is 0.5-3.5 and the weight hourly space velocity is 1-5h-1Hydrogen hydrocarbon (volume ratio) 500-9 +The conversion of heavy aromatics was 11.4-64.3 wt%, but the maximum BTX yield was only 62.7%.
U.S. Pat. No. 5,942,651 discloses a method of converting C to C9 +A process for converting heavy aromatics to light aromatics products by converting C to9 +Heavy aromatic hydrocarbon and benzene or toluene are passed through two catalyst beds in the same reactor or two catalyst beds in two serially connected reactors under the condition of transalkylation, and the method is aimed at making raw material pass through first catalyst at slower speed to produce intermediate product, then making said intermediate product pass through second catalyst at faster speed to obtain high-purity benzene product.
Disclosure of Invention
The invention aims to solve the technical problem that the prior art only needs heavy aromatics to be light, so that side chain methyl groups are wasted, or fresh benzene or toluene is needed to participate in raw materials, so that the raw material composition requirement is strict, and provides a novel C9 +Process for the production of xylenes with heavy aromatics with C only9 +Heavy aromatics are used as aromatic hydrocarbon raw materials to produce BTX, and the target product types are flexibly adjustable among benzene, toluene and xylene.
In order to solve the technical problems, the technical scheme of the invention is as follows:
C9 +the process for producing xylene from heavy aromatics comprises the following steps:
a)C9 +separating low-boiling-point heavy aromatic hydrocarbon 4 and high-boiling-point heavy aromatic hydrocarbon 3 from the heavy aromatic hydrocarbon 1 in a heavy aromatic hydrocarbon separation tower 2;
b) in the presence of hydrogen, low-boiling heavy aromatic hydrocarbon 4 is in contact reaction with a hydrodealkylation and transalkylation catalyst in a hydrodealkylation and transalkylation reaction unit 6 to obtain a material flow 7 containing benzene, toluene, xylene aromatic hydrocarbon, non-aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and hydrogen;
c) separating hydrogen 9 or 10 from a material flow 7 containing benzene, toluene, xylene aromatic hydrocarbon, non-aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and hydrogen in a gas-liquid separator 8 to obtain a material flow 11 containing benzene, toluene, xylene aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and non-aromatic hydrocarbon;
d) separating non-aromatic hydrocarbon 13 from the material flow 11 containing benzene, toluene, xylene aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and non-aromatic hydrocarbon in a stripping tower 12 to obtain a material flow 14 containing benzene, toluene, xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon;
e) benzene 16 and a material flow 17 containing the toluene, the xylene aromatic hydrocarbon and the unreacted heavy aromatic hydrocarbon are separated from the material flow 14 containing the benzene, the toluene, the xylene aromatic hydrocarbon and the unreacted heavy aromatic hydrocarbon in a benzene separation tower 15;
f) separating toluene 19 from a material flow 17 containing toluene, xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon in a toluene separation tower 18 to obtain a material flow 20 containing xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon;
g) the material flow 20 containing the xylene aromatic hydrocarbon and the unreacted heavy aromatic hydrocarbon is separated out the unreacted heavy aromatic hydrocarbon 23 in a xylene separation tower 21 to obtain a xylene product 22.
By the method of the invention, only C can be adopted9 +The heavy aromatics are used as the aromatic hydrocarbon raw material of the device system to produce the dimethylbenzene, and the device system has the advantages of low raw material cost and flexible and adjustable target product types among benzene, methylbenzene and dimethylbenzene.
In the above process, 2 pairs of C in the heavy aromatics separation tower9 +The degree of cleavage of the heavy aromatic hydrocarbon 1 is not particularly limited, and for example, the boiling point is 350 ℃ or higherThe lower fraction is the low-boiling heavy aromatic hydrocarbon 4, but a fraction having a boiling point of 300 ℃ or lower is preferably the low-boiling heavy aromatic hydrocarbon 4, a fraction having a boiling point of 250 ℃ or lower is more preferably the low-boiling heavy aromatic hydrocarbon 4, and a fraction having a boiling point of 215 ℃ or lower is more preferably the low-boiling heavy aromatic hydrocarbon 4. C, the degree of the above-mentioned cut fraction is in the order of boiling point 350 ℃ or lower, boiling point 300 ℃ or lower, boiling point 250 ℃ or lower, boiling point 215 ℃ or lower9 +There is a significant trend towards increased conversion of heavy aromatics.
In the process, unreacted heavy aromatic hydrocarbon obtained at the heavy aromatic hydrocarbon extraction outlet at the bottom of the xylene separation tower 21 is preferably returned to C9 +And a heavy aromatics separation column 2.
In the above process, as an alternative, the benzene extracted from the benzene extraction outlet at the top of the benzene separation tower 15 is input into the reaction unit 6; in this case, the process is favorable for producing more toluene and xylene.
In the above process, as a second alternative, the toluene extracted from the toluene extraction outlet at the top of the toluene separation column 18 is input into the reaction unit 6; in this case, the process is advantageous for the production of benzene and xylene in an increased amount.
In the above process, as a third alternative, the benzene extracted from the benzene extraction outlet at the top of the benzene separation tower 15 is input into the reaction unit 6, and the toluene extracted from the toluene extraction outlet at the top of the toluene separation tower 18 is input into the reaction unit 6; in this case, the process is advantageous for the production of xylene in an increased amount.
In the above process, C9 +Heavy aromatics are not particularly limited, such as, but not limited to, products from catalytic reforming, pyrolysis gasoline hydrogenation, hydrocracking, and the like. By way of comparison only, C employed in the embodiments of the present invention9 +Heavy aromatics come from catalytic reforming.
C from catalytic reforming9 +The heavy aromatic hydrocarbons have complicated composition, and contain more than ten carbon and carbon components such as butylbenzene, monomethyl propylbenzene, diethyl benzene, ethylbenzene, etc. in addition to 50-90 wt% of carbon nine and indane,Dimethyl ethylbenzene, tetramethylbenzene, methyl indane, naphthalene, methyl naphthalene, dimethyl naphthalene, biphenyl, polycyclic aromatic hydrocarbons, and the like.
In at least one embodiment of the present invention, the low-boiling heavy aromatic hydrocarbon 4 is a heavy aromatic hydrocarbon having a boiling point of 300 ℃ or less, and has a specific composition (specific point): 2.53% by weight of propylbenzene, 15.38% by weight of methylethylbenzene, 41.58% by weight of trimethylbenzene, 1.40% by weight of indane, 1.10% by weight of butylbenzene, 6.35% by weight of monomethylpropylbenzene, 0.67% by weight of diethylbenzene, 12.39% by weight of dimethylethylbenzene, 7.35% by weight of tetramethylbenzene, 1.88% by weight of methylindane, 2.67% by weight of C11 monocyclic aromatic hydrocarbon, 1.98% by weight of naphthalene, 1.88% by weight of methylnaphthalene, 2.85% by weight of polymethylnaphthalene and biphenyl polycyclic aromatic hydrocarbon.
In at least one embodiment of the present invention, the low-boiling heavy aromatic hydrocarbon 4 is a heavy aromatic hydrocarbon having a boiling point of 250 ℃ or less, and specifically comprises: 2.61% by weight of propylbenzene, 15.83% by weight of methylethylbenzene, 42.80% by weight of trimethylbenzene, 1.44% by weight of indane, 1.14% by weight of butylbenzene, 6.53% by weight of monomethylpropylbenzene, 0.69% by weight of diethylbenzene, 12.75% by weight of dimethylethylbenzene, 7.56% by weight of tetramethylbenzene, 1.94% by weight of methylindane, 2.75% by weight of C11 monocyclic aromatic hydrocarbon, 2.04% by weight of naphthalene, 1.19% by weight of beta-methylnaphthalene, 0.75% by weight of alpha-methylnaphthalene.
In at least one embodiment of the present invention, the low boiling point heavy aromatic hydrocarbon 4 is a heavy aromatic hydrocarbon having a boiling point of 215 ℃ or less, and is specifically composed of: 2.78 wt% of propylbenzene, 16.85 wt% of methylethylbenzene, 45.56 wt% of trimethylbenzene, 1.53 wt% of indane, 1.21 wt% of butylbenzene, 6.96 wt% of monomethylpropylbenzene, 0.74 wt% of diethylbenzene, 13.57 wt% of dimethylethylbenzene, 7.09 wt% of tetramethylbenzene, 1.71 wt% of methylindane, 2.01 wt% of C11 monocyclic aromatic hydrocarbon.
In the above process, the hydrodealkylation and transalkylation catalysts used in the reaction unit 6 are not particularly limited, and those commonly used in the art can be used without any inventive effort and all can achieve comparable technical results. Such catalysts in the art typically comprise a molecular sieve in the hydrogen form and a hydrogenation metal supported thereon.
In the above process, the hydrogen-form molecular sieve may comprise at least one selected from the group consisting of ZSM-5, MOR, Beta, Y molecular sieves, or mixtures thereof. For SiO in molecular sieves2/Al2O3The molecular ratio is not particularly limited, and those skilled in the art can select appropriately and all can achieve comparable technical effects without making a creative effort. By way of non-limiting example, such as SiO2/Al2O3The molecular ratio may be 5 to 100, more preferably 5 to 80, and still more preferably 5 to 50.
In the above process, the hydrogenation metal component may comprise at least one selected from Mo, Ni, Co and W.
In the above process, the reaction temperature is preferably 200-500 ℃.
In the above process, the reaction pressure is preferably 2.0 to 6.0MPa in gauge pressure.
In the above process, the molar ratio of hydrogen to hydrocarbon in the feed to the reaction unit is from 2 to 10.
In order to solve the technical problem, the following complete equipment system can be adopted:
C9 +the complete equipment system for producing the dimethylbenzene from the heavy aromatics comprises C9 +A heavy aromatics separation tower (2), a hydrodealkylation and transalkylation reaction unit (6), a gas-liquid separator (8), a stripping tower (12), a benzene separation tower (15), a toluene separation tower (18) and a xylene separation tower (21); c9 +The heavy aromatic hydrocarbon separation tower (2) is provided with a low boiling point heavy aromatic hydrocarbon top extraction outlet and a high boiling point heavy aromatic hydrocarbon bottom discharge outlet, and the component C is9 +A low-boiling point heavy aromatic hydrocarbon top extraction outlet of the heavy aromatic hydrocarbon separation tower (2) is input into the reaction unit (6); the reaction unit (6) is provided with a hydrogen inlet, and the discharge end of the reaction unit (6) is input into a gas-liquid separator (8); the gas-liquid separator (8) is provided with a gas-phase outlet and a liquid-phase outlet, and the liquid-phase outlet of the gas-liquid separator (8) is input into the inlet of the stripping tower (12); stripping column (12) is provided with a gas phaseAn outlet and a liquid phase outlet, wherein the liquid phase outlet of the stripping tower (12) is input into the inlet of the benzene separation tower (15); the benzene separation tower (15) is provided with a tower top benzene extraction outlet, and the tower bottom of the benzene separation tower (15) is input into a toluene separation tower (18); a toluene extraction outlet is arranged at the top of the toluene separation tower (18), and the bottom of the toluene separation tower (18) is input into a xylene separation tower (21); the top of the xylene separation tower (21) is provided with a xylene extraction outlet, and the bottom of the xylene separation tower (21) is provided with a heavy aromatic extraction outlet.
In the above-mentioned complete plant system, the heavy aromatics extraction outlet at the bottom of the xylene separation column (21) is preferably returned to C9 +And a heavy aromatics separation tower (2).
In the above plant system, the gas phase outlet of the gas-liquid separator (8) is preferably provided with a passage for feeding to the reaction unit (6) and a discharge port for discharging the plant system.
In the above-mentioned plant system, in order to make the plant system produce toluene and xylene in a large amount, the benzene take-off port at the top of the benzene separation column (15) preferably has a passage for feeding to the reaction unit (6).
In the above-mentioned plant system, in order to make the plant system produce benzene and xylene in a large amount, the toluene take-off port at the top of the toluene separation column (18) preferably has a passage for feeding to the reaction unit (6).
In the above-mentioned plant system, in order to make the plant system use xylene as the only target product, it is preferable that the benzene take-out port at the top of the benzene separation column (15) has a passage for feeding to the reaction unit (6), and the toluene take-out port at the top of the toluene separation column (18) has a passage for feeding to the reaction unit (6).
In the above plant system, the reaction unit may comprise at least one hydrodealkylation and transalkylation reactor.
In the above plant system, the reaction unit may comprise 2 or more than 2 hydrodealkylation and transalkylation reactors connected in series or in parallel.
In the above-mentioned plant system, the reaction unit may comprise 3 or more than 3 hydrodealkylation and transalkylation reactors, which are connected in series-parallel.
The data processing calculation formula is as follows:
Figure BDA0001709264610000051
Figure BDA0001709264610000052
Figure BDA0001709264610000062
in the above formula, C8A represents xylene, C9 +A represents C9 +Heavy aromatics.
By the present invention, C can be used9 +The heavy aromatics are used as the only aromatic raw material of the device system, benzene, toluene and xylene products are produced through the hydrogenation dealkylation and transalkylation reaction of the heavy aromatics, and the advantage that the target product types can be flexibly adjusted among benzene, toluene and xylene is realized through the process routes that the benzene is circulated back to the reaction unit and the toluene is circulated back to the reaction unit or the benzene and the toluene are simultaneously circulated back to the reaction unit, and the like, so that better technical effects are obtained.
The process flow of the process of the present invention will be described in detail below with reference to the description of the apparatus system of FIGS. 1 to 4, which can be used in the present invention.
Drawings
FIGS. 1 to 4 show the present invention C9 +A schematic diagram of a complete device system for producing dimethylbenzene from heavy aromatics.
In the figure: 1 is C9 +Heavy aromatics; 2 is a heavy aromatics separation tower; 3 is high boiling point heavy aromatic hydrocarbon; 4 is low boiling heavy aromatics; 5 is new hydrogen; 6 is a hydrodealkylation and transalkylation reaction unit; 7 is a material flow containing benzene, toluene, xylene aromatic hydrocarbon, non-aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and hydrogen; 8 is a gas-liquid separator; 9 is discharge hydrogen; 10 is circulating hydrogen;11 a stream containing benzene, toluene, xylene aromatics, unreacted heavy aromatics and non-aromatic hydrocarbons; 12 is a stripping tower; 13 a non-aromatic hydrocarbon; 14 is a material flow containing benzene, toluene, xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon; 15 is a benzene separation tower; 16 is benzene separated from the benzene separation tower 15; 17 is a material flow containing toluene, xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon; 18 is a toluene separation tower; 19 is toluene separated from the toluene separation tower 18; 20 is a material flow containing xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon; 21 is a xylene separation column; 22 is a xylene product; 23 are unconverted heavy aromatics.
The process flow of fig. 1 is:
C9 +heavy aromatic hydrocarbon 1 firstly passes through a heavy aromatic hydrocarbon separation tower 2 to remove high-boiling point heavy aromatic hydrocarbon 3 to obtain low-boiling point heavy aromatic hydrocarbon 4, the low-boiling point heavy aromatic hydrocarbon 4 is mixed with new hydrogen 5 and circulating hydrogen 10 and then enters a hydrodealkylation and transalkylation reaction unit 6 to be contacted with a catalyst to carry out hydrodealkylation and transalkylation reactions, so that a material flow 7 containing benzene, toluene, xylene aromatic hydrocarbon, non-aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and hydrogen is obtained; the material flow 7 enters a gas-liquid separator 8 for separation, a small amount of hydrogen separated from the top is discharged out of the device system in a form of discharged hydrogen 9, and the rest is returned to the reaction unit 6 in a form of circulating hydrogen 10, a material flow 11 containing benzene, toluene, xylene aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and non-aromatic hydrocarbon separated from the bottom of the gas-liquid separator 8 enters a stripping tower 12, and a material flow 14 containing benzene, toluene, xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon is obtained at the top of the stripping tower 12; the material flow 14 enters a benzene separation tower 15, and a benzene material flow 16 obtained at the top of the benzene separation tower 15 and a material flow 17 containing methylbenzene, xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon are obtained; the material flow 17 enters a toluene separation tower 18, a toluene material flow 19 is obtained at the top of the toluene separation tower 18, a material flow 20 containing xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon is obtained at the bottom of the toluene separation tower 18, the material flow 20 enters a xylene separation tower 21, a xylene product 22 is obtained at the top of the xylene separation tower 21, and unconverted heavy aromatic hydrocarbon 23 is obtained at the bottom of the xylene separation tower 21; the unconverted heavy aromatics 23 are returned to the heavy aromatics separation column 2.
The process flow shown in FIG. 1 is completely the same except that the benzene stream 16 obtained from the top of the benzene separation column 15 in FIG. 2 is returned to the reaction unit, the toluene stream 19 obtained from the top of the toluene separation column 18 in FIG. 3 is returned to the reaction unit, and the benzene stream 16 obtained from the top of the benzene separation column 15 and the toluene stream 19 obtained from the top of the toluene separation column 18 in FIG. 4 are both returned to the reaction unit.
Detailed Description
The process flow of FIG. 1 is adopted in examples 1 to 5, the process flow of FIG. 2 is adopted in examples 1b to 5b, the process flow of FIG. 3 is adopted in examples 1c to 5c, and the process flow of FIG. 4 is adopted in examples 1d to 5 d.
[ example 1]
Preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium ZSM-5 zeolite 66.7 g and Na with molecular ratio of 802gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support are taken up in 35 ml of aqueous ammonium molybdate solution (corresponding to MoO content)31.6 g) impregnated carrier, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours to obtain MoO3Catalyst in an amount of 3.1 w%.
Catalyst evaluation
The process flow shown in fig. 1 is adopted, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are as follows:
a reactor: inner diameter
Figure BDA0001709264610000071
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000072
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is a fraction with a boiling point of below 300 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (which is not returned to the reactor), toluene (which is not returned to the reactor) and xylene products.
[ example 2]
Preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium ZSM-5 zeolite 66.7 g and Na with molecular ratio of 802gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support are taken up in 35 ml of aqueous ammonium molybdate solution (corresponding to MoO content)31.6 g) impregnated carrier, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours to obtain MoO3Catalyst in an amount of 3.1 w%.
Catalyst evaluation
The process flow shown in fig. 1 is adopted, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are as follows:
a reactor: inner diameter
Figure BDA0001709264610000081
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000082
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 250 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (which is not returned to the reactor), toluene (which is not returned to the reactor) and xylene products.
[ example 3]
Preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium Beta zeolite 66.7 g and Na with molecular ratio of 252gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the carrier was impregnated with 35 ml of an aqueous nickel nitrate solution (equivalent to 1.3 g of NiO), dried at 120 ℃ for 4 hours, and calcined at 550 ℃ for 3 hours to obtain a catalyst having a NiO content of 2.5 w%.
Catalyst evaluation
The process flow shown in fig. 1 is adopted, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are as follows:
a reactor: inner diameter
Figure BDA0001709264610000091
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and downThe glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (which is not returned to the reactor), toluene (which is not returned to the reactor) and xylene products.
[ example 4]
Preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium MOR zeolite 66.7 g and Na with molecular ratio of 282gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the carrier was taken and used with 35 ml of an aqueous ammonium tungstate solution (equivalent to a solution containingWO31.3 g) impregnated support, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours, to obtain WO3Catalyst in an amount of 2.5 w%.
Catalyst evaluation
The process flow shown in fig. 1 is adopted, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are as follows:
a reactor: inner diameter
Figure BDA0001709264610000101
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000102
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (which is not returned to the reactor), toluene (which is not returned to the reactor) and xylene products.
[ example 5]
Preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium Beta zeolite 66.7 g and Na with molecular ratio of 252gamma-Al with O less than 0.05 wt%2O3·H2Mixing O57.1 g, adding 7 g of 65-68 wt% nitric acid water solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extrudingMolding, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in air atmosphere, and pelletizing to obtain a cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the carrier was impregnated with 35 ml of an aqueous nickel nitrate solution (equivalent to 1.3 g of NiO), dried at 120 ℃ for 4 hours, and calcined at 550 ℃ for 3 hours to obtain a catalyst having a NiO content of 2.5 w%.
Catalyst evaluation
The process flow shown in fig. 1 is adopted, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are as follows:
a reactor: inner diameter
Figure BDA0001709264610000111
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000112
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 3.0h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.4MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 6.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (which is not returned to the reactor), toluene (which is not returned to the reactor) and xylene products.
The reaction results of examples 1 to 5 are shown in Table 1. As can be seen from the data in table 1, the selectivity for BTX in the optimized scheme reached 78.4, wt%, indicating that higher yields of BTX in the product can be obtained using the process of the invention.
[ example 1b ]
Except that all the benzene generated by the reaction is returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those in the example 1, and the specific steps are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium ZSM-5 zeolite 66.7 g and Na with molecular ratio of 802gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support are taken up in 35 ml of aqueous ammonium molybdate solution (corresponding to MoO content)31.6 g) impregnated carrier, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours to obtain MoO3Catalyst in an amount of 3.1 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 2, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000121
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000122
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is a fraction with a boiling point of below 300 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (not returned to the reactor) and xylene products.
[ example 2b ]
Except that all the benzene generated by the reaction is returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those of the example 2, and the specific steps are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium ZSM-5 zeolite 66.7 g and Na with molecular ratio of 802gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support are taken up in 35 ml of aqueous ammonium molybdate solution (corresponding to MoO content)31.6 g) impregnated carrier, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours to obtain MoO3Catalyst in an amount of 3.1 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 2, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000123
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000124
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 250 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (not returned to the reactor) and xylene products.
[ example 3b ]
Except that all the benzene generated by the reaction is returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those in the example 3, and the specific steps are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium Beta zeolite 66.7 g and Na with molecular ratio of 252gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the carrier was impregnated with 35 ml of an aqueous nickel nitrate solution (equivalent to 1.3 g of NiO), dried at 120 ℃ for 4 hours, and calcined at 550 ℃ for 3 hours to obtain a catalyst having a NiO content of 2.5 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 2, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000131
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000132
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (not returned to the reactor) and xylene products.
[ example 4b ]
Except that all the benzene generated by the reaction is returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those of the example 4, and the specific steps are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium MOR zeolite 66.7 g and Na with molecular ratio of 282gamma-Al with O less than 0.05 wt%2O3·H2Mixing O57.1 g, adding 7 g of 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding, drying at 120 deg.C for 4 hr, calcining at 550 deg.C in air atmosphere for 3 hr, cuttingThe pellets gave a cylindrical support of 2mm length and 1.5mm diameter.
Catalyst preparation
50 g of the support were taken and 35 ml of an aqueous ammonium tungstate solution (equivalent to WO-containing solution) was added31.3 g) impregnated support, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours, to obtain WO3Catalyst in an amount of 2.5 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 2, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000141
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000142
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (not returned to the reactor) and xylene products.
[ example 5b ]
Except that all the benzene generated by the reaction is returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those in the example 5, and the specific steps are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium Beta zeolite 66.7 g and Na with molecular ratio of 252gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the carrier was impregnated with 35 ml of an aqueous nickel nitrate solution (equivalent to 1.3 g of NiO), dried at 120 ℃ for 4 hours, and calcined at 550 ℃ for 3 hours to obtain a catalyst having a NiO content of 2.5 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 2, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000151
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000152
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 3.0h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.4MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 6.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (not returned to the reactor) and xylene products.
The results of the reactions of examples 1b-5b are shown in Table 1 b. As can be seen from the comparison of the data in Table 1b with the data in Table 1, the selectivity of toluene and xylene is improved by the recycle of benzene, wherein the selectivity of toluene is 57.8 wt%, and the selectivity of xylene is 53.0 wt%, indicating that the method of the invention can obtain higher yield of toluene and xylene in the products.
[ example 1c ]
Except that the toluene generated by the reaction is all returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those in the example 1, and specifically, the process conditions are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium ZSM-5 zeolite 66.7 g and Na with molecular ratio of 802gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support are taken up in 35 ml of aqueous ammonium molybdate solution (corresponding to MoO content)31.6 g) impregnated carrier, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours to obtain MoO3Catalyst in an amount of 3.1 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 3, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000161
The length is 1000 mm;
filling a catalyst: stainless steel materialThe catalyst bed is filled up and down
Figure BDA0001709264610000162
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is a fraction with a boiling point of below 300 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatics mixture produced by the reactions is separated to obtain toluene (returned to the reactor), benzene (not returned to the reactor) and xylene products.
[ example 2c ]
Except that the toluene generated by the reaction is all returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those of the example 2, and the specific steps are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium ZSM-5 zeolite 66.7 g and Na with molecular ratio of 802gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support are taken up in 35 ml of aqueous ammonium molybdate solution (corresponding to MoO content)31.6 g) impregnated carrier, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours to obtain MoO3Catalyst in an amount of 3.1 w%.
Catalyst evaluation
The process flow shown in fig. 1 is adopted, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are as follows:
a reactor: inner diameter
Figure BDA0001709264610000171
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000172
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 250 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatics mixture produced by the reactions is separated to obtain toluene (returned to the reactor), benzene (not returned to the reactor) and xylene products.
[ example 3c ]
Except that the toluene generated by the reaction is all returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those in the example 3, and specifically, the process conditions are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium Beta zeolite 66.7 g and Na with molecular ratio of 252gamma-Al with O less than 0.05 wt%2O3·H2O57.1 g is evenly mixed, and then 7 g of 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water are added for kneadingMixing uniformly, extruding into strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in air atmosphere, and granulating to obtain a cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the carrier was impregnated with 35 ml of an aqueous nickel nitrate solution (equivalent to 1.3 g of NiO), dried at 120 ℃ for 4 hours, and calcined at 550 ℃ for 3 hours to obtain a catalyst having a NiO content of 2.5 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 3, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000181
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000182
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatics mixture produced by the reactions is separated to obtain toluene (returned to the reactor), benzene (not returned to the reactor) and xylene products.
[ example 4c ]
Except that the toluene generated by the reaction is all returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those of the example 4, and the specific steps are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium MOR zeolite 66.7 g and Na with molecular ratio of 282gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support were taken and 35 ml of an aqueous ammonium tungstate solution (equivalent to WO-containing solution) was added31.3 g) impregnated support, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours, to obtain WO3Catalyst in an amount of 2.5 w%.
Catalyst evaluation
The process flow shown in fig. 1 is adopted, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are as follows:
a reactor: inner diameter
Figure BDA0001709264610000191
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000192
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatics mixture produced by the reactions is separated to obtain toluene (returned to the reactor), benzene (not returned to the reactor) and xylene products.
[ example 5c ]
Except that the toluene generated by the reaction is all returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those in the example 5, and the specific steps are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium Beta zeolite 66.7 g and Na with molecular ratio of 252gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the carrier was impregnated with 35 ml of an aqueous nickel nitrate solution (equivalent to 1.3 g of NiO), dried at 120 ℃ for 4 hours, and calcined at 550 ℃ for 3 hours to obtain a catalyst having a NiO content of 2.5 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 3, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000201
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000202
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 3.0h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.4MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 6.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatics mixture produced by the reactions is separated to obtain toluene (returned to the reactor), benzene (not returned to the reactor) and xylene products.
The results of the reactions of examples 1c-5c are shown in Table 1 c. As can be seen from the comparison of the data in Table 1c with the data in Table 1, the selectivity of two high-value aromatics, benzene and xylene, is improved by the circulation of toluene, indicating that the method of the invention can obtain higher yield of benzene and xylene in the products.
[ example 1d ]
Except that all the benzene and toluene generated by the reaction are returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those in the example 1, and specifically, the process conditions are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium ZSM-5 zeolite 66.7 g and Na with molecular ratio of 802gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support are taken up in 35 ml of aqueous ammonium molybdate solution (corresponding to MoO content)31.6 g) impregnated carrier, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours to obtain MoO3Catalyst in an amount of 3.1 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 4, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000203
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and downThe glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is a fraction with a boiling point of below 300 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (returned to the reactor) and xylene products.
[ example 2d ]
Except that all the benzene and toluene generated by the reaction are returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those of the example 2, and specifically, the process conditions are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium ZSM-5 zeolite 66.7 g and Na with molecular ratio of 802gamma-Al with O less than 0.05 wt%2O3·H2O57.1 g, then 7 g of 65-68 wt% nitric acid aqueous solution and 2 gThe sesbania powder and 60-70 g of water are evenly kneaded, extruded and formed, dried for 4 hours at 120 ℃, roasted for 3 hours at 550 ℃ in air atmosphere, and cut into granules to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support are taken up in 35 ml of aqueous ammonium molybdate solution (corresponding to MoO content)31.6 g) impregnated carrier, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours to obtain MoO3Catalyst in an amount of 3.1 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 4, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000212
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000213
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 250 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (returned to the reactor) and xylene products.
[ example 3d ]
Except that all the benzene and toluene generated by the reaction are returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those in the example 3, and specifically, the process conditions are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium Beta zeolite 66.7 g and Na with molecular ratio of 252gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the carrier was impregnated with 35 ml of an aqueous nickel nitrate solution (equivalent to 1.3 g of NiO), dried at 120 ℃ for 4 hours, and calcined at 550 ℃ for 3 hours to obtain a catalyst having a NiO content of 2.5 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 4, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000221
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000222
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (returned to the reactor) and xylene products.
[ example 4d ]
Except that all the benzene and toluene generated by the reaction are returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those of the example 4, and the specific steps are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium MOR zeolite 66.7 g and Na with molecular ratio of 282gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the support were taken and 35 ml of an aqueous ammonium tungstate solution (equivalent to WO-containing solution) was added31.3 g) impregnated support, dried at 120 ℃ for 4 hours, calcined at 550 ℃ for 3 hours, to obtain WO3Catalyst in an amount of 2.5 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 4, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameterThe length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000232
The glass beads act as gas flow distribution and lower layer support, and 20 g catalyst is filled in the reactorAn oxidizing agent;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 2.5h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.0MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 4.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (returned to the reactor) and xylene products.
[ example 5d ]
Except that all the benzene and toluene generated by the reaction are returned to the reactor, the process conditions of the carrier preparation, the catalyst preparation and the catalyst evaluation are the same as those of the example 5, and specifically, the process conditions are as follows:
preparation of the support
Mixing Na2O less than 0.05 wt%, SiO2/Al2O3Ammonium Beta zeolite 66.7 g and Na with molecular ratio of 252gamma-Al with O less than 0.05 wt%2O3·H2And uniformly mixing 57.1 g of O, adding 7 g of a 65-68 wt% nitric acid aqueous solution, 2 g of sesbania powder and 60-70 g of water, kneading uniformly, extruding to form strips, drying at 120 ℃ for 4 hours, roasting at 550 ℃ for 3 hours in an air atmosphere, and granulating to obtain the cylindrical carrier with the length of 2mm and the diameter of 1.5 mm.
Catalyst preparation
50 g of the carrier was impregnated with 35 ml of an aqueous nickel nitrate solution (equivalent to 1.3 g of NiO), dried at 120 ℃ for 4 hours, and calcined at 550 ℃ for 3 hours to obtain a catalyst having a NiO content of 2.5 w%.
Catalyst evaluation
By adopting the process flow shown in fig. 4, the hydrodealkylation and transalkylation reaction unit is a single reactor, and the process parameters of the reaction unit are specifically as follows:
a reactor: inner diameter
Figure BDA0001709264610000241
The length is 1000 mm;
filling a catalyst: stainless steel material, catalyst bed layer is filled up and down
Figure BDA0001709264610000242
The glass beads play a role in gas flow distribution and lower layer support, and 20 g of catalyst is filled in the reactor;
the low-boiling heavy aromatic hydrocarbon is fraction with a boiling point of below 215 ℃ and is taken as the low-boiling heavy aromatic hydrocarbon;
the weight space velocity of the aromatic hydrocarbon in the feed of the reactor is 3.0h-1；
The reaction temperature is 380 ℃;
the reaction pressure is 3.4MPa, and the gauge pressure is higher;
the molar ratio of hydrogen to aromatics in the reactor feed was 6.0.
The low boiling point heavy aromatics and hydrogen are mixed and then pass through a catalyst bed layer from top to bottom to generate dealkylation and transalkylation reactions, and the aromatic hydrocarbon mixture produced by the reactions is separated to obtain benzene (returned to the reactor), toluene (returned to the reactor) and xylene products.
TABLE 1
Figure BDA0001709264610000251
TABLE 1b
Figure BDA0001709264610000252
TABLE 1c
Figure BDA0001709264610000253
TABLE 1d
Figure BDA0001709264610000254

Claims (10)

1.C9 +The process for producing xylene from heavy aromatics comprises the following steps:
a)C9 +separating low-boiling-point heavy aromatic hydrocarbon (4) and high-boiling-point heavy aromatic hydrocarbon (3) from the heavy aromatic hydrocarbon (1) in a heavy aromatic hydrocarbon separation tower (2);
b) in the presence of hydrogen, low-boiling heavy aromatic hydrocarbon (4) is in contact reaction with a hydrodealkylation and transalkylation catalyst in a hydrodealkylation and transalkylation reaction unit (6) to obtain a material flow (7) containing benzene, toluene, xylene aromatic hydrocarbon, non-aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and hydrogen;
c) separating hydrogen (9 or 10) from a material flow (7) containing benzene, toluene, xylene aromatic hydrocarbon, non-aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and hydrogen in a gas-liquid separator (8) to obtain a material flow (11) containing benzene, toluene, xylene aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and non-aromatic hydrocarbon;
d) separating non-aromatic hydrocarbon (13) from a stream (11) containing benzene, toluene, xylene aromatic hydrocarbon, unreacted heavy aromatic hydrocarbon and non-aromatic hydrocarbon in a stripping tower (12) to obtain a stream (14) containing benzene, toluene, xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon;
e) separating benzene (16) and a material flow (17) containing the toluene, the xylene aromatic hydrocarbon and the unreacted heavy aromatic hydrocarbon from the material flow (14) containing the benzene, the toluene, the xylene aromatic hydrocarbon and the unreacted heavy aromatic hydrocarbon in a benzene separation tower (15);
f) separating toluene (19) from the material flow (17) containing toluene, xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon in a toluene separation tower (18) to obtain a material flow (20) containing xylene aromatic hydrocarbon and unreacted heavy aromatic hydrocarbon;
g) the material flow (20) containing the xylene aromatic hydrocarbon and the unreacted heavy aromatic hydrocarbon is separated out the unreacted heavy aromatic hydrocarbon (23) in a xylene separation tower (21) to obtain a xylene product (22).
2. The process as claimed in claim 1, wherein the low-boiling heavy aromatics (4) are obtained from a fraction having a boiling point of 350 ℃ or less.
3. The process as claimed in claim 2, characterized in that the low-boiling heavy aromatics (4) are obtained as a fraction having a boiling point of 250 ℃.
4. A process according to claim 3, characterized in that the fraction below 215 ℃ is taken as the low-boiling heavy aromatic hydrocarbon (4).
5. The process as claimed in claim 1, characterized in that the unreacted heavy aromatics obtained at the bottom heavy aromatics extraction of the xylene separation column (21) are sent back to the C9 +And a heavy aromatics separation tower (2).
6. The process as claimed in claim 1, characterized in that the benzene withdrawn from the benzene withdrawal at the top of the benzene separation column (15) is fed to the reaction unit (6).
7. The process as claimed in claim 1, wherein the toluene taken off at the toluene withdrawal at the top of the toluene separation column (18) is fed to the reaction unit (6).
8. The process as claimed in claim 1, wherein C is9 +Heavy aromatics include products from catalytic reforming, pyrolysis gasoline hydrogenation, or hydrocracking processes.
9. The process according to claim 1, characterized in that said reaction unit (6) comprises at least one hydrodealkylation and transalkylation reactor.
10. The process according to claim 9, characterized in that the reaction unit (6) comprises 2 or more than 2 hydrodealkylation and transalkylation reactors, connected in series or in parallel.
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