CN115595175B

CN115595175B - Method and device for efficiently producing light hydrocarbon and application thereof

Info

Publication number: CN115595175B
Application number: CN202110717004.1A
Authority: CN
Inventors: 郑均林; 姜向东; 宋奇; 李成; 周彦妮
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Priority date: 2021-06-28
Filing date: 2021-06-28
Publication date: 2024-05-03
Anticipated expiration: 2041-06-28
Also published as: CN115595175A

Abstract

The invention relates to a full conversion method and a full conversion device for producing chemical industry materials from catalytic diesel. The technical scheme of the invention comprises the steps of carrying out hydrofining and selective conversion reaction on catalytic diesel oil flow, wherein the selective conversion catalyst comprises beta zeolite, MWW type zeolite with the thickness of a slice ranging from 2nm to 12nm, VIB metal sulfide and a binder. Separating the product to sequentially separate C ₂-C₅ light hydrocarbon, C ₆-C₈ alkane, benzene, toluene, C ₈A、C₉A、C₁₀ A aromatic hydrocarbon and tower bottom heavy tail oil; and (3) feeding the heavy tail oil at the bottom of the tower into a post-selection saturation reactor, carrying out high-selectivity hydrogenation saturation under the low-temperature and low-pressure conditions to obtain a benzene ring product, and then feeding the benzene ring product back into the selection conversion reactor. The full fraction conversion of the chemical materials produced from the catalytic diesel is realized, and the method has the technical effects of higher yield of C ₆A-C₁₀ A light aromatic hydrocarbon and the chemical materials such as C ₂-C₅ light hydrocarbon and C ₆-C₈ alkane.

Description

Method and device for efficiently producing light hydrocarbon and application thereof

Technical Field

The invention belongs to the field of petroleum hydrocracking, and particularly relates to a method and a device for efficiently producing light hydrocarbon and application thereof.

Background

With the acceleration of the third energy revolution, electrification becomes more and more the mainstream of energy power, and the demand of gasoline and diesel is continuously reduced. The conversion of crude oil into chemical raw materials in higher proportion is an important prospect and transformation direction of future refineries. A great deal of poor-quality aromatic-rich oil products, such as catalytic diesel oil and ethylene tar, appear in refining enterprises.

Catalytic diesel is one of the main products of the catalytic cracking process, with annual production of about 5000 ten thousand tons throughout the country. Although they have boiling points in diesel oil fractions, the economy of processing them into diesel oil is poor due to the large amount of polycyclic aromatic hydrocarbons and the like, and some enterprises can only use them as fuel oil. Along with the growth and stagnation of diesel oil demands, development of efficient conversion technology is needed, catalytic diesel oil is converted into light aromatic hydrocarbon and olefin raw materials through hydrocracking reaction, and cost reduction and synergy of the oil refining-aromatic hydrocarbon-olefin industry are realized through refining integration.

The currently commonly used catalytic diesel upgrading means are hydrofining, hydro-upgrading and light oil type hydrocracking. The catalytic diesel hydrofining is to perform olefin hydrogenation saturation, desulfurization, denitrification and aromatic hydrocarbon partial saturation reaction under the conditions of medium and low pressure, so that the color and stability of the catalytic diesel can be improved. However, the catalytic diesel oil obtained by the catalytic device for processing the inferior raw material can not meet the cetane number requirement of the product through hydrofining. Hydro-upgrading processes, such as Unicracking process from UOP corporation (US 5026472), the target product of which is high cetane number diesel. The process has good arene hydrogenating saturation performance and ring opening selectivity, high arene converting depth, high cetane number and high diesel oil yield. The light oil type hydrocracking is to refine the light diesel component and then to carry out severe saturation hydrogenation to obtain a reformed material of naphtha fraction or a gasoline fraction, and the process also has the problem of low yield of the conversion of raw materials into aromatic hydrocarbons. If the naphtha fraction is used for reforming an aromatic hydrocarbon feedstock, the naphthenes and paraffins produced after supersaturation are also converted into aromatics in a reformer, which is not an economical route. The light oil type hydrocracking method as described in Chinese patent CN101684415A does not directly produce aromatic hydrocarbon, the aromatic potential of heavy naphtha is only 57% at most, and the traditional hydrocracking catalyst using USY zeolite as an acidic component is a key cause for low aromatic hydrocarbon yield and purity.

In the existing catalytic diesel hydrocracking technology, the content of aromatic hydrocarbon in heavy tail oil is reduced compared with that in catalytic diesel raw material, the cetane number is increased, and the heavy tail oil is discharged outside as diesel components or partially recycled to a hydrofining reactor, so that the heavy tail oil cannot be effectively and completely utilized. In addition, the hydrofining reaction on the metal sulfide hydrofining catalyst needs to be carried out under the severe operation condition of high temperature and high pressure, the reaction is limited by thermodynamic equilibrium, the selectivity of the partial saturation reaction of the polycyclic aromatic hydrocarbon is poor, and the retention rate of the aromatic hydrocarbon after the LCO is hydrofined is close to 90 percent. The sulfur and nitrogen content in the heavy tail oil of the chemical materials such as light aromatic hydrocarbon and light hydrocarbon produced by catalyzing diesel oil is low, and the problems of over saturation and aromatic hydrocarbon loss can be caused by directly recycling the heavy tail oil to the hydrofining reactor for treatment.

Disclosure of Invention

Aiming at the problems of the prior art, the invention provides a method and a device for efficiently producing light hydrocarbon, which are characterized in that catalytic diesel oil flow is subjected to hydrogenation refining and then is subjected to selective conversion reaction under the action of a novel selective conversion catalyst, and products are separated to sequentially separate light aromatic hydrocarbons such as C ₂-C₅ light hydrocarbon, C ₆-C₈ alkane, benzene-toluene, xylene and the like, C ₉ A aromatic hydrocarbon, C ₁₀ A aromatic hydrocarbon and tower bottom heavy tail oil; the heavy tail oil at the bottom of the tower enters a post-selection saturation reactor, is subjected to high-selectivity hydrogenation saturation under the condition of low temperature and low pressure to obtain a product with one benzene ring, and is then sent to a selective conversion reaction, so that full-fraction conversion of the chemical materials produced from catalytic diesel is realized, the yield of light hydrocarbon is higher, and the chemical materials such as light aromatic hydrocarbon, C ₂-C₅ light hydrocarbon, C ₆-C₈ alkane and the like are produced.

It is an object of the present invention to provide a process for efficiently producing light hydrocarbons comprising: the catalytic diesel is subjected to hydrofining, selective conversion and hydrogenation saturation to obtain light aromatic hydrocarbon, wherein a selective conversion catalyst used for selective conversion comprises beta zeolite, layered MWW type zeolite, VIB metal sulfide and a first binder.

Specifically, the method comprises the following steps:

step 1), catalytic diesel is hydrofined to obtain a first material flow;

step 2) selectively converting the first stream to obtain a second stream;

Step 3) separating the second stream to obtain a third stream containing heavy aromatics above C10;

step 4) carrying out hydrogenation saturation on the third material flow to obtain a fourth material flow;

step 5) repeating the operation steps of step 2) to step 4) with the fourth stream.

Preferably, the method comprises the steps of,

In the above-described process for efficiently producing light hydrocarbons, step 1):

The catalytic diesel oil can be taken as raw oil from a catalytic cracking device in the field, and the initial distillation point of the catalytic diesel oil is 160-210 ℃ under normal pressure. The composition of the catalytic diesel is not particularly limited, and the catalytic diesel may be derived from crude oils of different production sites and may have different compositions. But as an example, the catalytic diesel mainly contains components such as alkane, naphthene hydrocarbon, olefin, sulfur-containing hydrocarbon, nitrogen-containing hydrocarbon, C ₁₁ ⁺ alkylbenzene, polycyclic aromatic hydrocarbon and the like, specifically, in terms of mass percent, the catalytic diesel contains 10-40% of alkylbenzene with more than C ₁₁ and C ₁₁, 15-50% of polycyclic aromatic hydrocarbon, 200-15000 ppm of sulfur, 100-1500 ppm of nitrogen and the balance of high-boiling alkane, naphthene hydrocarbon and olefin;

The hydrofining reaction in step 1) is a catalytic diesel hydrofining technology known in the art, and the hydrofining reaction conditions can be the catalytic diesel hydrofining reaction conditions known in the art, preferably, the hydrofining reaction conditions include: the hydrogen-oil volume ratio is 500-3000 Nm ³/m³, preferably 800-2000 Nm ³/m³, more preferably 1000-1500 Nm ³/m³; the reaction temperature is 280-420 ℃, preferably 300-410 ℃, more preferably 310-390 ℃; the partial pressure of hydrogen is 5-15 MPa, preferably 6-12 MPa, more preferably 7-10 MPa; the space velocity is 0.5 to 2.0 hours ^-1, preferably 0.6 to 1.5 hours ^-1, more preferably 0.8 to 1.2 hours ^-1;

The hydrofining catalyst is added in the step 1), and any hydrofining catalyst existing in the field can be adopted as long as the purpose of catalyzing the diesel hydrofining in the step 1) can be achieved, preferably, the hydrofining catalyst comprises a catalyst carrier and a hydrogenation metal sulfide, wherein the catalyst carrier is selected from gamma-alumina; the hydrogenation metal sulfide is selected from sulfide of VIII group metal and/or VIB group metal, preferably selected from sulfide combination of nickel and/or cobalt, molybdenum and/or tungsten; the catalyst carrier is used in an amount of 60 to 99.9 parts by weight, preferably 65 to 99.9 parts by weight, more preferably 70 to 99.9 parts by weight, most preferably 75 to 99.9 parts by weight, based on 100 parts by weight of the hydrofining catalyst; the amount of the hydrogenated metal sulfide is 0.1 to 40 parts, preferably 0.1 to 35 parts, more preferably 0.1 to 30 parts, and most preferably 0.1 to 25 parts. The hydrofinishing catalyst may be prepared by any method known in the art, for example, the support may be prepared by extrusion, ball or column molding and the like methods known in the art.

Preferably, the method comprises the steps of,

In the above-mentioned method step 2) for efficiently producing light hydrocarbons:

the reaction conditions for the selection of the conversion include: the volume ratio and the pressure condition of the hydrogen and the oil are the same as those of the hydrofining reaction; the reaction temperature is 280-450 ℃, preferably 300-430 ℃, more preferably 310-400 ℃; space velocity is 0.5-4.0 h ^-1, preferably 0.6-3.0 h ^-1, more preferably 0.8-2.0 h ^-1;

the selective conversion catalyst is added in step 2), preferably the selective conversion catalyst comprises zeolite beta, layered MWW-type zeolite, group VIB metal sulfide, a first binder, and optionally a metal function modulating component.

Wherein, the pore space index of the beta zeolite is 15-18; the silicon-aluminum ratio of the beta zeolite is 10-200, preferably 15-100;

The lamellar MWW zeolite has a lamellar thickness ranging from 2 to 12nm, preferably from 2 to 10nm; the silicon-aluminum ratio is 8-150, preferably 10-100;

the group VIB metal sulfide is preferably at least one selected from molybdenum (Mo), tungsten (W) sulfides;

the first binder can be selected from catalyst binders commonly used in the prior art, preferably one of alumina and silica;

the metal function regulating component is at least one selected from VIII group metal sulfide and IIB group metal sulfide, preferably at least one selected from nickel sulfide, cobalt sulfide and zinc sulfide;

The beta zeolite accounts for 50 to 99 percent, preferably 60 to 95 percent of the total weight of the beta zeolite and the layered MWW zeolite in terms of mass percent; the group VIB metal sulfide is 1 to 30 parts by weight, preferably 2 to 25 parts by weight, more preferably 3 to 15 parts by weight, based on 100 parts by weight of the total amount of the beta zeolite and the layered MWW zeolite; the first binder is 5-2000 parts, preferably 10-1000 parts, more preferably 10-900 parts; the metal function regulating component is 0 to 50 parts, preferably 0.5 to 30 parts, more preferably 1 to 20 parts.

The selective conversion catalyst may be prepared by any method known in the art, for example, the support may be prepared by methods known in the art such as extrusion, ball or column molding. In one embodiment, the catalyst may be prepared by a process in which the support is shaped and then impregnated with the metal. In one embodiment, the method for preparing the selective conversion catalyst may preferably comprise the following specific steps:

step a), mixing beta zeolite and layered MWW zeolite with a first adhesive, kneading, extruding strips, drying at 60-150 ℃, and roasting at 500-600 ℃ for 3-6 hours to obtain a catalyst carrier;

Step b) preparing a composite metal compound aqueous solution; wherein the composite metal compound comprises a VIB group metal compound and optionally a VIII group metal and a IIB group metal soluble metal compound, and preferably at least one of ammonium tungstate, ammonium molybdate, nickel nitrate, nickel sulfate, nickel halide, nickel oxalate, nickel acetate, cobalt nitrate, cobalt chloride, cobalt oxalate, zinc nitrate, zinc chloride, zinc oxalate and zinc acetate; the concentration of the composite metal compound aqueous solution is 3-50%, preferably 5-40%;

Step c), immersing the catalyst carrier obtained in the step a) in the composite metal compound aqueous solution obtained in the step b), drying at 60-150 ℃, and roasting at 450-520 ℃ for 1-4 hours to obtain a catalyst precursor;

step d) sulfiding the catalyst precursor from step c) to obtain the selective conversion catalyst, wherein the sulfiding may be performed by a sulfiding process commonly used in the art, and in one embodiment, the sulfiding may be performed by adding a carbon disulfide solution, wherein the solvent is at least one selected from toluene, ethylbenzene, o-xylene, p-xylene, and m-xylene. The heating rate of the heating is 1-20 ℃/h, preferably 5-10 ℃/h; the end temperature of heating is 300-370 ℃, preferably 320-360 ℃; the end temperature is maintained for 1 to 24 hours, preferably 4 to 18 hours.

In the selective conversion catalyst adopted by the invention, the combination of beta zeolite and layered MWW type zeolite is adopted as an acidic functional component, so that the catalyst has good nitrogen resistance. The beta zeolite plays a dominant cracking role, and the pore canal shape-selective effect of the beta zeolite enables tetrahydronaphthalene hydrocarbon to be selectively converted into light aromatic hydrocarbon, enables non-aromatic hydrocarbon to be deeply cracked, and the aromatic hydrocarbon purity of the obtained heavy naphtha can meet the requirements of an aromatic hydrocarbon combination device; the flaky MWW structure zeolite can realize the conversion of heavy polycyclic aromatic hydrocarbon macromolecules; the VIB metal sulfides such as Mo, W and the like are suitable for the high-sulfur environment of the single-stage process; the metal function regulating component can improve the hydrogenation capacity of the VIB group metal sulfide. The selective conversion catalyst has the characteristics of high per pass conversion rate, high light aromatic hydrocarbon yield and high chemical industry yield for the aromatic-rich inferior oil product.

Preferably, the method comprises the steps of,

In the above-mentioned method step 3) for efficiently producing light hydrocarbons:

The separation comprises gas-liquid separation, rectification and extraction; separating in the step 3) to obtain C ₂～C₅ alkane, C ₆～C₈ alkane, benzene, toluene, C ₈ arene, fraction containing C ₉ arene and C ₁₀ arene and third stream containing heavy arene with more than 10 carbon atoms; the aromatic hydrocarbon content in the third material is more than 80%, preferably more than 90%.

Preferably, the method comprises the steps of,

The above method for efficiently producing light hydrocarbons comprises the following step 4):

The hydro-saturation reaction is a liquid hydrogenation reaction, and preferably, the hydro-saturation reaction conditions include: the hydrogen-oil volume ratio is 200-3000 Nm ³/m³, preferably 300-1500 Nm ³/m³, more preferably 300-1000 Nm ³/m³; the reaction temperature is 100 to 300 ℃, preferably 120 to 280 ℃, more preferably 150 to 250 ℃; the partial pressure of hydrogen is 1.0-4.0 MPa, preferably 1.2-3.0 MPa; the airspeed is 0.1 to 5.0h ^-1, preferably 0.5 to 4.0h ^-1, more preferably 0.6 to 2.0h ^-1;

The step 4) is added with a post-selective saturation catalyst, wherein the post-selective saturation catalyst can be a hydrogenation saturation catalyst existing in the field, so long as the purpose of the hydrogenation saturation of the step 4) can be achieved, such as an aromatic hydrogenation saturation catalyst described in China patent CN 103041832A; preferably, the post-selective saturation catalyst comprises: amorphous silicon aluminum, VIII family metal and a second binder, wherein the content of silicon oxide in the amorphous silicon aluminum is 3-20wt%; the VIII metal is at least one of platinum, palladium, cobalt, nickel and iridium; the second binder is selected from aluminum oxide; in the post-selection saturated catalyst, 10-90 parts of amorphous silicon aluminum, 0.1-5 parts of VIII metal and 5-80 parts of second binder are calculated according to 100 parts by weight of the total weight of the post-selection saturated catalyst. The post-selective saturation catalyst may be prepared by any method known in the art, for example, the support may be prepared by methods known in the art such as extrusion, ball or column molding. In one embodiment, the catalyst may be prepared by a process in which the support is shaped and then impregnated with the metal.

Another object of the present invention is to provide an apparatus for producing light hydrocarbons by the above-mentioned method for producing light hydrocarbons with high efficiency, comprising:

First reaction zone: receiving catalytic diesel, carrying out hydrofining reaction in a hydrofining reactor and discharging a first material flow; wherein the inlet temperature of the hydrofining reactor is 250-450 ℃;

A second reaction zone; receiving the first stream, performing a selective conversion reaction in a hydrocracking reactor, and discharging a second stream; wherein the inlet temperature of the hydrocracking reactor is 280-450 ℃;

a first separation zone: receiving a second stream, performing gas-liquid separation, rectification and extraction processes, and discharging a third stream from the bottom;

Post-selection saturation reaction zone: receiving the third stream, conducting a hydrofinishing reaction in a hydrofinishing vessel and discharging a fourth stream; wherein the inlet temperature of the hydrogenation saturation reactor is 100-300 ℃, and the partial pressure of the reaction hydrogen is 1.0-4.0 MPa.

Preferably, the method comprises the steps of,

The reactors of the first reaction zone, the second reaction zone and the rear selective saturation reaction zone are fixed bed reaction systems, wherein the fixed bed reaction systems of the first reaction zone and the second reaction zone are configured with a shared circulating hydrogen system, and the fixed bed reaction system of the rear selective saturation reaction zone is a liquid phase hydrogenation reaction system without a circulating hydrogen system; the rectifying tower of the first reaction zone comprises a depentanizer, a deheptanizer, a dimethylbenzene tower and a heavy aromatic tower which are connected in sequence;

the first separation zone comprises a gas-liquid separator, a rectifying tower and an extraction device which are connected in sequence;

The post-selective saturation reaction zone is provided with a circulating pipeline for circulating the fourth material flow to the second reaction zone.

In the first reaction zone in the device for producing light hydrocarbon, the catalytic diesel oil serving as raw oil is hydrofined in the first reaction zone under the condition of hydrogen, wherein catalytic diesel oil material flow and hydrogen are contacted with a hydrofining catalyst to perform desulfurization and denitrification, and selective saturation reaction of polycyclic aromatic hydrocarbon with one aromatic ring reserved is generated. The hydrofining may be carried out in any manner and by any method conventionally known in the art, as long as the catalytic diesel is desulfurized and denitrified and the polycyclic aromatic hydrocarbon therein is hydrosaturated to remain one aromatic ring, without particular limitation. The first material flow obtained after the catalytic diesel is hydrofined mainly comprises refined catalytic diesel with most of sulfur and nitrogen impurities removed, and gas phase containing hydrogen sulfide and ammonia.

In the second reaction zone of the above apparatus for producing light hydrocarbons, the first stream is selectively converted under hydrogen conditions in the second reaction zone by a reaction including hydrocracking. The selective conversion includes a hydrocracking reaction that selectively converts a first stream obtained after hydrofinishing to a second stream, the second stream obtained comprising primarily dry gas (including methane and ethane), C ₃-C₅ light hydrocarbons, benzene-toluene fraction, xylene fraction, C ₉-C₁₀ fraction, and heavy tail oil. One of the purposes of the selective conversion is to carry out hydrocracking on the premise of retaining one aromatic ring of polycyclic aromatic hydrocarbon in heavy aromatic hydrocarbon in the first material flow, so that the saturation depth and the ring opening position are effectively controlled, and simultaneously, the macromolecular non-aromatic hydrocarbon in the first material flow can be isomerized and cracked; maximizing the production of light aromatic hydrocarbon under the condition of economic hydrogen consumption. The selective conversion reaction described above can be carried out according to any method known in the art for conventional hydrogenation reactions, provided that the selective conversion of the first stream to the second stream is achieved.

The first separation zone in the device for producing light hydrocarbon comprises a gas-liquid separator, a rectifying tower and an extraction unit which are optionally connected in sequence, and is used for sequentially separating and obtaining fractions including third streams of light aromatic hydrocarbons such as C ₂-C₅ light hydrocarbon, C ₆-C₈ alkane, benzene-toluene, xylene and the like, C ₉ A aromatic hydrocarbons, C ₁₀ A aromatic hydrocarbons and heavy tail oil at the bottom of the tower; the rectifying tower preferably comprises a depentanizer, a deheptanizer, a dimethylbenzene tower and a heavy aromatic tower which are connected in sequence. Wherein said first separation of the second stream preferably comprises gas-liquid separation, rectification and extraction; the rectification preferably comprises depentanglements, deheptanides, xylenes and heavy aromatics; wherein the stream enriched in benzene-toluene fraction is preferably separated by extraction from the deheptanization. Specifically, the second stream is subjected to gas-liquid separation to separate dry gas and liquid-phase material flows, wherein the dry gas is discharged outside, and the liquid-phase material flows are sent to a depentanizer for depentanizing; separating out light hydrocarbon fraction of C ₃-C₅ from the external discharged from the depentanizer, and feeding the bottom stream of the depentanizer into a heptane removal tower; separating a benzene-toluene fraction-enriched stream from a heptane-removing tower bottom stream, wherein the benzene-toluene fraction-enriched stream is preferably subjected to an extraction device to separate pure benzene-toluene mixed aromatic hydrocarbon, and extracting and separating C ₆-C₈ alkane to be sent out; the bottom stream of the deheptanizer is sent to a xylene tower, a mixed xylene product and a bottom stream of the deheptanizer are separated from the top of the xylene tower, and the bottom stream of the deheptanizer is sent to a heavy aromatic hydrocarbon tower for heavy aromatic hydrocarbon removal; the de-heavy aromatics separate the outgoing C ₉-C₁₀ and the third stream separated at the bottom. The third stream is a heavy tail oil containing heavy aromatics above C ₁₀. The heavy tail oil is fed to a selective saturation reactor. The above deheptanizer separates out a stream rich in benzene-toluene fraction, preferably after extraction, pure benzene-toluene mixed aromatic hydrocarbon is separated out, and the extracted and separated C ₆-C₈ alkane is mainly naphthene and can be used as a high-quality reforming raw material. The gas-liquid separation, extraction and rectification can be carried out by adopting extraction and rectification methods commonly used in the field, and the gas-liquid separator, the rectification column and the extraction device can also adopt the conventional equipment in the field. The aromatic hydrocarbon content in the third stream obtained after the separation of the second stream obtained through the selective conversion is preferably higher than the non-aromatic hydrocarbon content; the third stream of the present invention more preferably has an aromatic content of up to 80wt% or more, most preferably up to 90wt% or more.

In the post-selective saturation reaction zone in the device for producing light hydrocarbon, the third stream containing heavy aromatic hydrocarbon with more than C ₁₀ obtained in the step 3) is contacted with a post-selective saturation catalyst in the post-selective saturation reaction zone under the conditions of hydrogen, low temperature and low pressure to carry out high-selectivity hydrogenation saturation reaction, so that a product with one benzene ring is obtained, and a fourth stream containing the product, namely a fraction with a distillation point of more than 210 ℃, is formed. The hydrogenation saturation may be carried out according to any known method conventional in the art as long as the effect of the post-selective saturation reaction described above can be achieved. The hydrogenation saturation of the post-selective saturation reaction zone is preferably liquid hydrogenation reaction, so that the flow is simplified, the equipment is reduced, and the energy consumption is saved.

It is a further object of the present invention to provide a process for the efficient production of light hydrocarbons as described above or a plant according to the above for the production of light alkanes and light aromatics from catalytic diesel.

The light aromatic hydrocarbon refers to aromatic hydrocarbon with carbon number less than or equal to 10, and comprises C ₆ aromatic hydrocarbon such as benzene; c ₇ aromatics such as toluene; c ₈ aromatics such as ethylbenzene, xylenes; c ₉ aromatics, such as methyl ethylbenzene, propylbenzene, trimethylbenzene; c ₁₀ aromatic hydrocarbons such as tetramethylbenzene, dimethylethylbenzene, diethylbenzene, and the like. Correspondingly, the heavy aromatic hydrocarbon with more than ₁₀ carbon atoms refers to aromatic hydrocarbon with more than 10 carbon atoms.

The invention provides a method for efficiently producing light hydrocarbon, which comprises the steps of hydrofining a catalytic diesel stream of a catalytic cracking device through a first reaction zone, removing impurity sulfur and nitrogen in the catalytic diesel stream, enabling polycyclic aromatic hydrocarbon and polycyclic aromatic hydrocarbon in the catalytic diesel stream to undergo selective hydrogenation saturation reaction, hydrogenating to obtain products with only one aromatic ring, such as tetrahydronaphthalene, indene, polyalkylbenzene and the like, then sending the products to a second reaction zone, carrying out selective conversion hydrocracking reaction to generate a stream containing light aromatic hydrocarbons such as benzene, toluene, xylene, C ₉ aromatic hydrocarbon, C ₁₀ aromatic hydrocarbon and the like, and sequentially separating light aromatic hydrocarbons such as C ₂-C₅ light hydrocarbon, C ₆-C₈ alkane, benzene-toluene, xylene and the like, C ₉ A aromatic hydrocarbon, C ₁₀ A aromatic hydrocarbon and heavy tail oil at the bottom of a tower after the light components of the product stream are removed; the heavy tail oil material at the bottom of the tower enters a post-selection saturation reactor, high-selectivity hydrogenation saturation occurs under the low-temperature and low-pressure condition, a product with one aromatic ring reserved is obtained, and the product is sent to a second reaction zone for hydrogenation cracking reaction of selective conversion, so that the full conversion process of the chemical materials for producing the catalytic diesel is realized, the yields of light aromatic hydrocarbon and light hydrocarbon are improved, the aromatic hydrocarbon loss is reduced, the hydrogen consumption is reduced, the problems in the prior art are well solved, and the method is used for increasing the yield of the light aromatic hydrocarbon and olefin raw materials and obtaining good technical effects.

According to the technical scheme, through hydrofining in the first reaction zone, the saturation rate of polycyclic aromatic hydrocarbon in the catalytic diesel oil material flow is more than 50%, the sulfur content is reduced to below 100ppm, the organic nitrogen content is reduced to below 15ppm, and the final distillation point is reduced by more than 10 ℃; after passing through the hydrofining device of the first reaction zone and the selective conversion device of the second reaction zone in turn, the catalytic diesel oil material flow is converted into monocyclic aromatic hydrocarbon and light hydrocarbon with ten carbon and below, and the conversion rate is more than 70%. The hydrogenation selectivity saturation of the material flow after passing through the post-selective saturation reactor is high, and the arene retention rate is more than 98 percent.

Compared with the prior art, the technical scheme of the invention adopts a hydrofining-selective conversion single-section double-catalyst (hydrofining catalyst and selective conversion catalyst) series scheme of tail oil saturation and comprises hydrofining, selective conversion and heavy tail oil post-saturation processes, and mainly solves the technical problems that the single-section double-catalyst series scheme has low light aromatic hydrocarbon yield in the conversion process because part of tail oil (usually 20-50wt% of the discharge capacity) is discharged outside in order to prevent the accumulation of the overweight aromatic hydrocarbon, and the full fraction catalytic diesel oil cannot be completely converted. The heavy tail oil of the catalytic diesel oil processing material is sent into a selective saturation reactor, and selective saturation reaction occurs under the conditions of moderate pressure and temperature, so that the problem of accumulation of overweight aromatic hydrocarbon caused by direct circulation back to the hydrofining reactor can be prevented. The selectivity of the hydrogenation saturation is greatly improved to more than 98 percent or even higher, and the problem of excessive hydrogenation saturation is solved; and also helps to reduce the cracking hydrogen consumption reaction that occurs when non-aromatics formed by over hydrogenation enter the selective conversion reactor. The method improves the technical and economic index of the whole process for preparing the chemical engineering by catalyzing the diesel, and realizes the full fraction conversion of the diesel. Compared with the hydrofining-selective conversion single-stage process, the light aromatic hydrocarbon yield of the invention can be improved by at least 2 percent, preferably by more than 5 percent, and the light hydrocarbon C ₂-C₅ and the alkane C ₆-C₈ are produced simultaneously.

Drawings

FIG. 1 is a schematic process flow diagram of a single-stage two-agent process for producing chemical industry materials from catalytic diesel in accordance with comparative example 1.

Reference numerals illustrate:

1. Is raw oil-catalytic diesel oil

2. Is a first reaction zone-hydrofining reactor

3. For the first reaction zone outlet stream-first stream

4. Selective conversion reactor for the second reaction zone

5. To select conversion reaction product-second stream

6. For the first separation zone, for example, rectifying columns including gas-liquid separators, depentanizer, deheptanizer, xylene column, heavy aromatics column and the like, and benzene-toluene fraction extraction apparatus

7. For dry gas and C ₃-C₅ light hydrocarbon streams separated in the first separation zone

8. Separating a C ₆-C₈ alkane stream from the first separation zone

9. For benzene and toluene streams separated in the first separation zone

10. C ₈ aromatic hydrocarbon material separated from the first separation zone

11. An aromatic hydrocarbon stream containing C ₉ aromatic hydrocarbons and C ₁₀ aromatic hydrocarbons separated for the first separation zone

12. Heavy tail oil discharged from the first separation zone

13. The heavy tail oil recycled to the first reaction zone for the first separation zone

FIG. 2 is a schematic process flow diagram of the full conversion process of the present invention from catalytic diesel production process.

Reference numerals illustrate:

1. Is raw oil-catalytic diesel oil

2. Is a first reaction zone-hydrofining reactor

3. For the first reaction zone outlet stream-first stream

4. Selective conversion reactor for the second reaction zone

5. To select conversion reaction product-second stream

8. Separating a C ₆-C₈ alkane stream from the first separation zone

9. For benzene and toluene streams separated in the first separation zone

12. Heavy tail-third stream separated for the first separation zone

13. Post-selective saturation zone-post-selective saturation reactor

14. For post-selection of saturated reactor outlet stream-fourth stream

Detailed Description

The present invention is described in detail below with reference to specific embodiments, and it should be noted that the following embodiments are only for further description of the present invention and should not be construed as limiting the scope of the present invention, and some insubstantial modifications and adjustments of the present invention by those skilled in the art from the present disclosure are still within the scope of the present invention.

All publications, patent applications, patents, and other references mentioned in this specification are herein incorporated by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art. In case of inconsistency or conflict, the definition of the present specification shall control.

When the specification derives materials, substances, methods, steps, devices, or elements and the like in the word "known to those skilled in the art", "prior art", or the like, such derived objects encompass those conventionally used in the art as the application suggests, but also include those which are not currently commonly used but which would become known in the art to be suitable for similar purposes.

The endpoints of the ranges and any values disclosed in this document are not limited to the precise range or value, and the range or value should be understood to include values approaching the range or value. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. In the following, the individual technical solutions can in principle be combined with one another to give new technical solutions, which should also be regarded as specifically disclosed herein.

The following describes specific embodiments of the present invention in detail, but the present invention is not limited to the specific details of the embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.

In addition, the specific features described in the following embodiments may be combined in any suitable manner without contradiction. The various possible combinations of the invention are not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention can be made, so long as the concept of the present invention is not deviated, and the technical solution formed thereby is a part of the original disclosure of the present specification, and also falls within the protection scope of the present invention.

Unless explicitly indicated otherwise, the pressures mentioned in this specification are gauge pressures.

Where not explicitly indicated, the space velocity referred to in this specification is the liquid hourly space velocity LHSV.

Unless explicitly indicated, all percentages, parts, ratios, etc. mentioned in this specification are by weight unless otherwise clear to the routine knowledge of a person skilled in the art.

The invention provides a device for efficiently producing light hydrocarbon

Fig. 2 is a schematic process flow diagram of an exemplary embodiment of a method of catalyzing a diesel fuel production process of the present invention, omitting many conventional equipment such as pumps, compressors, heat exchangers, extraction units, hydrogen lines, etc., but such equipment is well known to those of ordinary skill in the art. As shown in fig. 2, the flow of one exemplary embodiment of the method of the present invention is described in detail as follows:

The catalytic diesel 1 as raw oil enters a hydrofining device of a first reaction zone 2 to obtain hydrofined catalytic diesel containing hydrogen sulfide and ammonia, namely an outlet material flow 3 (a first material flow) of the first reaction zone; the first stream enters a selective conversion device of a second reaction zone 4 to obtain a second reaction zone outlet stream 5 (second stream) rich in light aromatic hydrocarbons such as benzene, toluene, xylene and the like, C ₉ A and C ₁₀ A fractions and heavy tail oil, the second stream enters a first separation zone 6, and dry gas and C ₃-C₅ light hydrocarbon stream 7, C ₆-C₈ alkane stream 8, benzene stream 9, toluene stream 10, aromatic hydrocarbon stream 11 comprising C ₉A/C₁₀ A and heavy tail oil third stream 12 containing heavy aromatic hydrocarbons above C ₁₀ are obtained through separation. The third stream 12 enters a post-selective saturation reactor 13 of the post-selective saturation reaction zone and the post-selective saturation reactor outlet stream 14 (fourth stream) is recycled to the selective conversion means of the second reaction zone 4 without separation.

Specifically, the first separation zone 6 comprises a rectifying column such as a gas-liquid separator, a depentanizer, a deheptanizer, a xylene column, a heavy aromatic column and the like and a benzene-toluene fraction extraction device which are connected in sequence.

The device and test method used in the examples are as follows:

The analysis of the composition of the catalysts involved in the present invention all employ analytical methods known in the art. For example, the composition of the catalyst may be analyzed by ICP (inductively coupled plasma) and XRF (X-ray fluorescence) methods for the selective conversion catalyst. The composition ratio of the group VIB metal oxides and the metal sulfides was determined by XPS (X-ray photoelectron spectroscopy) method. ICP testing was performed using a Varian 700-ES series XPS instrument. XRF testing was performed using a Rigaku ZSX 100e type XRF instrument. XPS test conditions included: PERKIN ELMER PHI5000C ESCA type X-ray photoelectron spectrometer, using Mg K excitation light source, operating voltage l0kV, current 40mA, vacuum degree 4.0X10-8 Pa.

In the invention, the group composition of catalytic diesel and hydrofinished catalytic diesel is analyzed (multidimensional chromatographic analysis) by using a full two-dimensional gas chromatograph/high throughput time-of-flight mass spectrometer (GC×GC-TOFMS) of the American LECO company, and is also used for analyzing the group composition of heavy tail oil and selecting saturated heavy tail oil.

In the present invention, the composition of the reactant stream (e.g., the selected conversion product, etc.) is determined by gas chromatography. The chromatography model was Agilent 7890A, equipped with FID detector, and the FFAP capillary column was separated using temperature programming, with an initial temperature of 90 ℃ for 15 minutes, and then at a rate of 15 ℃/min to 220 ℃ for 45 minutes.

In the method of the invention, the calculation formula is as follows:

1. the aromatics retention in the hydrofinishing and selective saturation (post saturation) process is calculated as follows:

2. The calculation formula of the total conversion (the single pass conversion of the fraction above 200 ℃) is as follows:

3. the light aromatic hydrocarbon yield is calculated as follows:

the catalyst raw materials of the examples and comparative examples of the present invention are commercially available.

Comparative example 1

The catalytic diesel oil is processed by adopting a hydrofining-selective conversion single-stage scheme, a hydrofining reactor and a selective conversion reactor share a circulating hydrogen system, and products such as C ₂-C₅ light hydrocarbon, C ₆-C₈ alkane, benzene-toluene, dimethylbenzene, C ₉ A aromatic hydrocarbon, C ₁₀ A aromatic hydrocarbon and heavy tail oil are obtained by separating a catalytic diesel oil raw material serving as raw material oil after hydrofining and selective conversion through a gas-liquid separation, a rectification system and extraction. In order to prevent accumulation of overweight aromatic hydrocarbon, 50% of heavy tail oil is discharged, and 50% is recycled to the hydrofining reactor. The flow is shown in figure 1.

The analysis data of the catalytic diesel oil raw material are shown in table 1, and the aromatic hydrocarbon content of the catalytic diesel oil raw material 1 is 78.8wt%. Table 2 shows the hydrofinishing catalysts, selective conversion (hydrocracking) catalysts and their reaction conditions used.

TABLE 1 catalytic Diesel feedstock

Project	Catalytic diesel feedstock 1	Catalytic diesel feedstock 2
			Density (4 ℃ C.)	0.947	0.971
Sulfur (wtppm)	1305	2130
			Nitrogen (wtppm)	368	865
Total aromatic content (wt%)	78.8	90.7
			Non-aromatic hydrocarbons (wt%)	21.2	9.3
Monocyclic aromatic hydrocarbons (wt%)	28.5	22.4
			Polycyclic aromatic hydrocarbon (wt%)	50.3	68.3
T95(℃)	325	365

TABLE 2 reaction conditions for comparative example 1

Preparation of hydrofining catalyst A1 precursor used: adding 2 kg of sesbania powder, 9L of nitric acid and 60L of water into 100 kg of pseudo-boehmite, kneading into clusters, extruding strips, preserving at room temperature for 24h, drying at 100 ℃ for 12h, and roasting at 550 ℃ for 3h in air atmosphere to obtain the hydrofining catalyst carrier. 7.90 kg of nickel nitrate hexahydrate, 8.71 kg of ammonium molybdate, 9.18 kg of ammonium metatungstate and 10 liters of aqueous ammonia were dissolved in water to obtain 50ml of a clear solution. And adding a metal solution into the hydrofining catalyst carrier in an equal volume dipping mode, soaking for 3 hours, drying at 110 ℃ for 12 hours, and roasting at 500 ℃ for 4 hours in an air atmosphere to obtain a hydrofining catalyst A1 precursor.

Preparation of the selective conversion catalyst B1 precursor used: the layered MWW-type zeolite is selected from SRZ-21 zeolite of China petrochemical catalyst division, and is prepared specifically as follows (example 1 according to CN101121524A specification): 6.1 kg of sodium aluminate (Al ₂O₃ 42.0.0 wt%) is dissolved in 288 kg, 1.0 kg of sodium hydroxide is added to dissolve the sodium aluminate, 34 kg of piperidine is added under stirring, 60 kg of solid silicon oxide and 5.5 kg of trimethylchlorosilane are added, and the material ratios (molar ratios) of reactants are respectively as follows: siO ₂/Al₂O₃＝40、NaOH/SiO₂ =0.025, trimethylchlorosilane/SiO ₂ =0.05, piperidine/SiO ₂＝0.50、H₂O/SiO₂ =16.

After the reaction mixture is stirred uniformly, the mixture is put into a crystallization kettle and crystallized for 50 hours at 135 ℃ under the stirring condition. And filtering, washing and drying after taking out to obtain SRZ-21 zeolite. The molar ratio of SiO ₂/Al₂O₃ was found to be 42.1 by chemical analysis.

The dried sample was measured and its ²⁹ Si MAS NMR solid nuclear magnetic spectrum showed a nuclear magnetic resonance peak at 15.1 ppm. The X-ray diffraction data are shown in Table 3.

TABLE 3X-ray diffraction data for layered MWW zeolites

The above SRZ-21 zeolite had a silica to alumina ratio of 42.1. The SRZ-21 zeolite has a distinct layered structure of MWW-type zeolite, wherein the single layer MWW structure has a platelet thickness of 2.6-2.7nm, and there are also a small number of double or triple layer MWW structures, with a platelet thickness of about 5-9nm.

The hydrogen type beta zeolite raw material is taken from China petrochemical catalyst division, the silicon-aluminum ratio (SAR) of the hydrogen type beta zeolite raw material is 50.5, and the pore space index is 16.5. Taking 52g of the hydrogen type beta zeolite, 10gSRZ-21 zeolite and 38g of pseudo-boehmite (Al ₂O₃ dry basis content 70 wt%) and kneading, extruding, drying at 120 ℃ and roasting for 2 hours in an air atmosphere at 530 ℃ to obtain the required catalyst carrier. 4.8g of nickel nitrate and 4.7g of ammonium heptamolybdate were dissolved in an appropriate amount of water to prepare 50ml of a bimetal aqueous solution. The catalyst carrier was impregnated by an isovolumetric impregnation method, 50g of the catalyst carrier was added to 35ml of the impregnation solution, and after standing for 2 hours, it was dried at 90℃and then calcined in an air atmosphere at 500℃for 2 hours to obtain a catalyst precursor B1.

The single-stage double-catalyst serial device is adopted, a hydrofining catalyst A1 precursor is filled into a pre-reactor, a selective conversion catalyst B1 precursor is filled into a post-reactor which is connected in series, and two catalysts are vulcanized by adopting carbon disulfide as a vulcanizing agent, so that a hydrofining catalyst A1 and a selective conversion catalyst B1 are respectively obtained, and the final compositions are shown in Table 2.

After the vulcanization is completed, the catalytic diesel oil raw material 1 is adopted, the reaction pressure is 8.5Mpa, and the hydrogen-oil ratio is 2000. The space velocity (LHSV) of the hydrofining catalyst A1 is 1.2h ^-1, and the inlet reaction temperature is 315 ℃; the space velocity (LHSV) of the conversion catalyst B1 was selected to be 1.0h ^-1, with an inlet reaction temperature of 375 ℃. And a sampling port is led out from an outlet pipeline of the hydrofining reactor and is used for sampling and analyzing the hydrofining oil, and the nitrogen content is 12.4ppm. The aromatic hydrocarbon retention rate of the raw materials after hydrofining reaction is 89.17wt% as obtained through the group composition analysis of refined oil.

The outlet of the selective conversion reactor is provided with a high-pressure separator, and after the device is stably operated for 48 hours, the gas and liquid products are respectively metered and analyzed in composition. After the gas-liquid separation, rectification system and extraction system, the reaction products are classified into five groups of CH ₄、C₂-C₅ light hydrocarbon, C ₆-C₈ alkane, C ₆-C₁₀ arene and tail oil with the temperature higher than 200 ℃, and the data are shown in Table 4. The total conversion was calculated to be 94.75wt% with 32.57wt% yields of light aromatics such as benzene-toluene, xylenes, C ₉ A aromatics, and C ₁₀ A aromatics. The resulting heavy tail oil has an off-set of > 200℃of 5.25wt% of fresh feed and sulfur nitrogen contents of 39.8ppm and 1.7ppm, respectively. The composition of the discharged tail oil obtained by multidimensional chromatography analysis is as follows: 10.77wt% of non-aromatic hydrocarbon, 36.86wt% of monocyclic aromatic hydrocarbon and 52.37wt% of polycyclic aromatic hydrocarbon.

TABLE 4 composition of the products obtained in comparative example 1

Product(s)	Yield, wt%
		CH₄	0.15
C ₂-C₅ light hydrocarbon	43.08
		C ₆-C₈ alkane	18.95
C ₆-C₁₀ aromatic hydrocarbons	32.57
		Tail oil at > 200 DEG C	5.25

Example 1

The flow of the present example for the full conversion of catalytic diesel into light hydrocarbon chemicals is shown in figure 2. The method comprises the steps of hydrofining catalytic diesel oil, separating impurities, selectively converting (hydrocracking), and sending heavy tail oil with the temperature of more than 200 ℃ obtained after selective conversion into a post-selective saturation reaction zone for selective hydrogenation saturation treatment, wherein the method comprises the following specific steps:

Wherein the raw materials, hydrofining catalyst, selective conversion catalyst and reaction conditions are the same as comparative example 1.

The composition of the post-selective saturation catalyst C1 for treating the heavy tail oil with the temperature of more than 200 ℃ is as follows: 0.05wt% Pt-0.15wt% Pd-4.5wt% SiO ₂-95.3wt％Al₂O₃. The post-selective saturation catalyst C1 was prepared as follows: mixing a commercial amorphous silicon aluminum material with the SiO ₂ content of 20 weight percent with pseudo-boehmite, adding a nitric acid peptizing agent, sesbania powder extrusion assisting agent and a proper amount of water, kneading, extruding to form strips, drying in air at 100 ℃ for 24 hours, and roasting at 550 ℃ for 4 hours to obtain the catalyst carrier. Dissolving a proper amount of chloroplatinic acid and palladium chloride in water to obtain a metal impregnation liquid, impregnating a catalyst carrier by an equal volume method, drying the catalyst carrier in air at 80 ℃ for 48 hours, and roasting the catalyst carrier for 2 hours under the air condition at 480 ℃ to obtain the post-selective saturation catalyst C1. The post-selective saturation catalyst C1 was reduced under hydrogen conditions at a reduction end point temperature of 450 ℃ and maintained for two hours.

The supersaturated amount of hydrogen is dissolved in heavy tail oil with the temperature of more than 200 ℃ through a hydrogen mixer, and the heavy tail oil is sent into a selective saturation reactor under the reaction conditions that: the hydrogen-oil volume ratio was 450Nm ³/m³, the reactor inlet temperature was 185 ℃, the hydrogen partial pressure was 1.6MPa, and the feed volume space velocity was 1.0 hour ^-1. After the balance of the whole reaction system was established, the analysis results of the selected saturated raw materials and the products are shown in Table 5, and the sulfur nitrogen contents were 13.7ppm and 0.8ppm, respectively. Calculated according to the aromatic hydrocarbon composition data, the retention rate of the polycyclic aromatic hydrocarbon in the saturation process is selected to be 98.08 weight percent.

TABLE 5 selection of saturated starting materials and products

	Heavy tail oil at > 200 DEG C	Selecting heavy tail oil with saturation higher than 200 DEG C
			Density (4 ℃ C.)	0.965	0.949
Sulfur (wtppm)	38.2	13.7
			Nitrogen (wtppm)	1.7	0.8
Non-aromatic hydrocarbons (wt%)	10.05	11.78
			Monocyclic aromatic hydrocarbons (wt%)	36.98	61.33
Polycyclic aromatic hydrocarbon (wt%)	52.97	26.89

And (3) returning all the heavy tail oil which is saturated and is more than 200 ℃ to the selective conversion reactor, and respectively metering and analyzing the composition of the gas and liquid products after establishing stable stream balance. After the gas-liquid separation, rectification system and extraction system, the reaction products are classified into five groups of CH ₄、C₂-C₅ light hydrocarbon, C ₆-C₈ alkane, C ₆-C₁₀ arene and tail oil with the temperature higher than 200 ℃, and the data are shown in Table 6. The total conversion rate is 100wt% because the device has no discharged heavy tail oil. The light aromatic hydrocarbon yield of benzene-toluene, dimethylbenzene, C ₉ A aromatic hydrocarbon, C ₁₀ A aromatic hydrocarbon and the like is 37.68wt percent, which is improved by 5.11 percent compared with the light aromatic hydrocarbon yield in the comparative example, and the aim of fully converting catalytic diesel oil into light hydrocarbon industrial materials is fulfilled.

TABLE 6 products obtained in example 1

Product(s)	Yield, wt%
		CH₄	0.17
C ₂-C₅ light hydrocarbon	42.01
		C ₆-C₈ alkane	20.14
C ₆-C₁₀ aromatic hydrocarbons	37.68
		Tail oil at > 200 DEG C	0

Example 2

The flow of the present example for the full conversion of catalytic diesel into light hydrocarbon chemicals is also shown in figure 2. The method comprises the following steps: wherein the hydrofinishing catalyst is the same as comparative example 1 and the post-selective saturation catalyst is the same as example 1.

The selective conversion catalyst B2 used was prepared:

the hydrogen type beta zeolite raw material is taken from China petrochemical catalyst division, the silicon-aluminum ratio (SAR) is 25, and the pore space index is 15.1. The layered MWW-type zeolite is selected from the SRZ-21 zeolite prepared in example 1.

And fully mixing 45g of hydrogen type beta zeolite, 5gSRZ-21 zeolite and 58g of pseudo-boehmite (Al ₂O₃ dry basis content 70 wt%) and then kneading, extruding, drying at 120 ℃ and roasting for 2 hours in an air atmosphere at 530 ℃ to obtain the required catalyst carrier. 4.14g of cobalt acetate tetrahydrate, 1.66g of ammonium metatungstate and 3.27g of ammonium heptamolybdate were dissolved in an appropriate amount of water to prepare 50ml of a trimetallic aqueous solution. The catalyst carrier was impregnated by an isovolumetric impregnation method, 50g of the catalyst carrier was added to 38ml of the impregnation solution, and after standing for 2 hours, it was dried at 110℃and calcined in an air atmosphere at 520℃for 2 hours to obtain a catalyst B2 precursor.

The obtained catalyst B2 precursor was sulfided in the same manner as in example 1 to obtain catalyst B2. The composition of the adhesive comprises the following components in parts by weight: 2.3wt% CoS-4.5wt% MoS ₂-2.2wt％WS₂/45 wt% beta zeolite-5 wt% SRZ-21-41wt% Al ₂O₃.

A single-section double-catalyst serial device is adopted, the hydrofining catalyst A1 after vulcanization is filled into a pre-reactor, and the selective conversion catalyst B2 is filled into a post-reactor which is connected in series. The analysis data of the catalytic diesel oil raw material are shown in table 1, and the aromatic hydrocarbon content of the catalytic diesel oil raw material 2 is 90.74wt%. The reaction pressure is 7.0Mpa, and the hydrogen-oil ratio is 2800. Hydrofining catalyst A1 space velocity (LHSV) 1.0h ^-1, reaction temperature 309 ℃; the space velocity (LHSV) of the conversion catalyst B2 was selected to be 1.2h ^-1, and the reaction temperature was 365 ℃.

The supersaturated amount of hydrogen is dissolved in heavy tail oil with the temperature of more than 200 ℃ through a hydrogen mixer, and the heavy tail oil is sent into a selective saturation reactor under the reaction conditions that: the hydrogen-oil volume ratio was 500Nm ³/m³, the reactor inlet temperature was 190 ℃, the hydrogen partial pressure was 2.0MPa, and the feed volume space velocity was 1.0 hour ^-1. After the balance of the whole reaction system was established, the analysis results of the saturated raw materials and the products were shown in Table 7, and the sulfur nitrogen contents of the products were 65ppm and 4.7ppm, respectively. Calculated according to the aromatic hydrocarbon composition data, the retention rate of the polycyclic aromatic hydrocarbon in the saturation process is 98.36wt%.

TABLE 7 selection of saturated starting materials and products

	Heavy tail oil at > 200 DEG C	Selecting heavy tail oil with saturation higher than 200 DEG C
			Density (4 ℃ C.)	0.982	0.952
Sulfur (wtppm)	129	65
			Nitrogen (wtppm)	5.9	4.7
Non-aromatic hydrocarbons (wt%)	2.3	3.9
			Monocyclic aromatic hydrocarbons (wt%)	42.9	71.4
Polycyclic aromatic hydrocarbon (wt%)	54.8	24.7

And (3) returning all the heavy tail oil which is saturated and is more than 200 ℃ to the selective conversion reactor, and respectively metering and analyzing the composition of the gas and liquid products after establishing stable stream balance. After the gas-liquid separation, rectification system and extraction system, the reaction products are classified into five groups of CH ₄、C₂-C₅ light hydrocarbon, C ₆-C₈ alkane, C ₆-C₁₀ arene and tail oil with the temperature higher than 200 ℃, and the data are shown in Table 8. The total conversion rate is 100wt% because the device has no discharged heavy tail oil. The light aromatic hydrocarbon yield of benzene-toluene, dimethylbenzene, C ₉ A aromatic hydrocarbon, C ₁₀ A aromatic hydrocarbon and the like is 45.65wt% obtained through calculation, and the aim of fully converting catalytic diesel oil into light hydrocarbon industrial materials is fulfilled.

TABLE 8 products obtained in EXAMPLE 2

Product(s)	Yield, wt%
		CH₄	0.13
C ₂-C₅ light hydrocarbon	41.84
		C ₆-C₈ alkane	12.38
C ₆-C₁₀ aromatic hydrocarbons	45.65
		Tail oil at > 200 DEG C	0

Comparative example 2

The flow of this comparative example for the full conversion of catalytic diesel into light hydrocarbon chemicals is also shown in figure 2. The method comprises the following steps: wherein the hydrofinishing catalyst is the same as comparative example 1 and the post-selective saturation catalyst is the same as example 1.

The selective conversion catalyst B3 used was prepared:

the hydrogen type USY zeolite raw material is taken from China petrochemical catalyst division, the silicon-aluminum ratio (SAR) of the raw material is 11, and the pore space index is 18.6. The layered MWW-type zeolite is selected from the SRZ-21 zeolite prepared in example 1.

The 45g USY zeolite, 5gSRZ-21 zeolite and 58g pseudo-boehmite (Al ₂O₃ dry basis content 70 wt%) are fully mixed, kneaded, extruded, dried at 120 ℃ and baked in 530 ℃ air atmosphere for 2 hours to obtain the required catalyst carrier. 4.14g of cobalt acetate tetrahydrate, 1.66g of ammonium metatungstate and 3.27g of ammonium heptamolybdate were dissolved in an appropriate amount of water to prepare 50ml of a trimetallic aqueous solution. The catalyst carrier was impregnated by an isovolumetric impregnation method, 50g of the catalyst carrier was added to 38ml of the impregnation solution, and after standing for 2 hours, it was dried at 110℃and calcined in an air atmosphere at 520℃for 2 hours to obtain a catalyst B3 precursor.

The obtained catalyst B3 precursor was sulfided in the same manner as in example 1 to obtain catalyst B3. The composition of the adhesive comprises the following components in parts by weight: 2.3wt% CoS-4.5wt% MoS ₂-2.2wt％WS₂/45 wt% USY zeolite-5 wt% SRZ-21-41wt% Al ₂ O3.

A single-section double-catalyst serial device is adopted, the hydrofining catalyst A1 after vulcanization is filled into a pre-reactor, and the selective conversion catalyst B3 is filled into a post-reactor which is connected in series. The analysis data of the catalytic diesel oil raw material are shown in table 1, and the aromatic hydrocarbon content of the catalytic diesel oil raw material 2 is 90.74wt%. The reaction pressure is 7.0Mpa, and the hydrogen-oil ratio is 2800. Hydrofining catalyst A1 space velocity (LHSV) 1.0h ^-1, reaction temperature 309 ℃; the space velocity (LHSV) of the conversion catalyst B3 was selected to be 1.2h ^-1, and the reaction temperature was 380 ℃.

The supersaturated amount of hydrogen is dissolved in heavy tail oil with the temperature of more than 200 ℃ through a hydrogen mixer, and the heavy tail oil is sent into a selective saturation reactor under the reaction conditions that: the hydrogen-oil volume ratio was 500Nm ³/m³, the reactor inlet temperature was 190 ℃, the hydrogen partial pressure was 2.0MPa, and the feed volume space velocity was 1.0 hour ^-1. After the balance of the whole reaction system was established, the analysis results of the saturated raw materials and the products were shown in Table 9, and the sulfur nitrogen contents of the products were 127ppm and 6.5ppm, respectively. Calculated according to the aromatic hydrocarbon composition data, the retention rate of the polycyclic aromatic hydrocarbon in the saturation process is 96.64wt%.

TABLE 9 selection of saturated starting materials and products

	Heavy tail oil at > 200 DEG C	Selecting heavy tail oil with saturation higher than 200 DEG C
			Density (4 ℃ C.)	0.944	0.938
Sulfur (wtppm)	177	127
			Nitrogen (wtppm)	7.9	6.5
Non-aromatic hydrocarbons (wt%)	34.5	36.7
			Monocyclic aromatic hydrocarbons (wt%)	23.7	38.0
Polycyclic aromatic hydrocarbon (wt%)	41.8	25.3

On the B3 catalyst based on USY and SRZ-21, the single pass conversion rate through hydrofining and hydrocracking reactions is only 71% as calculated by test results, and the non-aromatic hydrocarbon content in heavy tail oil at the temperature of more than 200 ℃ is 36.7%. To avoid the accumulation of non-aromatics, 50% of the heavy tail oil, which was selectively saturated at > 200 ℃, is returned to the selective conversion reactor. After establishing a stable stream balance, the gaseous and liquid products were metered and analyzed for composition, respectively. After the gas-liquid separation, rectification system and extraction system, the reaction products are classified into five groups of CH ₄、C₂-C₅ light hydrocarbon, C ₆-C₁₀ alkane, C ₆-C₁₀ arene and tail oil with the temperature higher than 200 ℃, and the data are shown in Table 10. The calculated light aromatic hydrocarbon yield of benzene-toluene, dimethylbenzene, C ₉ A aromatic hydrocarbon, C ₁₀ A aromatic hydrocarbon and the like is 27.32wt%.

TABLE 10 products obtained in comparative example 2

Product(s)	Yield, wt%
		CH₄	0.29
C ₂-C₅ light hydrocarbon	25.91
		C ₆-C₁₀ alkane	29.45
C ₆-C₁₀ aromatic hydrocarbons	27.32
		Tail oil at > 200 DEG C	17.03

In comparative example 2, USY zeolite commonly used in the traditional process is adopted to replace beta zeolite in the conversion catalyst B2 in example 2, and because USY zeolite pore canal is different from beta zeolite, the pore canal effect of the catalyst is different, the single pass conversion rate of hydrofining and hydrocracking reactions is only 71%, the non-aromatic hydrocarbon content in heavy tail oil at the temperature of more than 200 ℃ is relatively high and reaches 36.7%, and the yield of light aromatic hydrocarbons such as benzene-toluene, dimethylbenzene, C ₉ A aromatic hydrocarbon, C ₁₀ A aromatic hydrocarbon and the like is 27.32wt%. In the embodiment 2 of the invention, the selective conversion catalyst B2 of beta zeolite is adopted, the non-aromatic hydrocarbon content in heavy tail oil at the temperature of more than 200 ℃ is only 3.9%, the yield of light aromatic hydrocarbons such as benzene-toluene, dimethylbenzene, C ₉ A aromatic hydrocarbon and C ₁₀ A aromatic hydrocarbon is 45.65wt%, the yield of the light hydrocarbon is higher, the total conversion rate is 100wt%, and the full fraction conversion of the catalytic diesel is realized.

Claims

1. A method of producing light hydrocarbons comprising: the catalytic diesel is subjected to hydrofining, selective conversion and hydrogenation saturation to obtain light aromatic hydrocarbon, wherein the light aromatic hydrocarbon comprises C ₆-C₁₀ aromatic hydrocarbon; the selective conversion catalyst comprises beta zeolite, layered MWW zeolite, VIB metal sulfide, a first binder and a metal function regulating component, wherein the layered MWW zeolite is SRZ-21 zeolite, the VIB metal sulfide is selected from at least one of sulfide of Mo and W, the first binder is selected from one of alumina and silicon oxide, and the metal function regulating component is selected from at least one of nickel sulfide, cobalt sulfide and zinc sulfide; the thickness range of the lamellar MWW type zeolite is 2-12 nm, and the silicon-aluminum ratio is 8-150; the beta zeolite accounts for 50-99% of the total weight of the beta zeolite and the layered MWW zeolite in percentage by mass; the total amount of the beta zeolite and the layered MWW zeolite is calculated as 100 parts by weight, and the VI B metal sulfide is 1-30 parts; 5-2000 parts of first binder; 0.5-30 parts of metal function regulating components;

the method specifically comprises the following steps:

step 1), catalytic diesel is hydrofined to obtain a first material flow;

step 2) selectively converting the first stream to obtain a second stream;

Step 3) separating the second stream to obtain C ₂~C₅ alkane, C ₆~C₈ alkane, benzene, toluene, C ₈ arene, fraction containing C ₉ arene and C ₁₀ arene and third stream containing more than 10 carbon atoms;

step 5) repeating the operation steps from step 2) to step 4) on the fourth material flow;

In the catalytic diesel, the content of alkylbenzene with more than C ₁₁ and C ₁₁ is 10-40wt%, the content of polycyclic aromatic hydrocarbon is 15-50wt%, the content of sulfur is 200-15000 wtppm, the content of nitrogen is 100-1500 wtppm, and the other components are high-boiling alkane, naphthene and olefin.

2. The method according to claim 1, wherein in step 1):

the reaction conditions of the hydrofining in the step 1) comprise:

the volume ratio of the hydrogen to the oil is 500-3000 Nm ³/m³; and/or the number of the groups of groups,

The reaction temperature is 280-420 ℃; and/or the number of the groups of groups,

The partial pressure of hydrogen is 5-15 MPa; and/or the number of the groups of groups,

The liquid hourly space velocity is 0.5-2.0 hours ^-1; and/or the number of the groups of groups,

The hydrofining catalyst is added in the step 1).

3. The method according to claim 2, wherein in step 1):

the reaction conditions of the hydrofining in the step 1) comprise:

The volume ratio of hydrogen to oil is 800-2000 Nm ³/m³; and/or the number of the groups of groups,

The reaction temperature is 300-410 ℃; and/or the number of the groups of groups,

The partial pressure of hydrogen is 6-12 MPa; and/or the number of the groups of groups,

The liquid hourly space velocity is 0.6-1.5 hours ^-1; and/or the number of the groups of groups,

The hydrofining catalyst comprises a catalyst carrier and hydrogenation metal sulfide.

4. A method according to claim 3, wherein in step 1):

the reaction conditions of the hydrofining in the step 1) comprise:

The volume ratio of the hydrogen to the oil is 1000-1500 Nm ³/m³; and/or the number of the groups of groups,

The reaction temperature is 310-390 ℃; and/or the number of the groups of groups,

The partial pressure of hydrogen is 7-10 MPa; and/or the number of the groups of groups,

The liquid hourly space velocity is 0.8-1.2 hours ^-1.

5. The method of claim 3, wherein the step of,

The catalyst carrier of the hydrofining catalyst is selected from gamma-alumina; and/or the number of the groups of groups,

The hydrogenation metal sulfide of the hydrofining catalyst is selected from sulfide of VIII group metal and/or VIB group metal; and/or the number of the groups of groups,

The catalyst carrier is used in an amount of 60-99.9 parts by weight based on 100 parts by weight of the hydrofining catalyst; the dosage of the hydrogenated metal sulfide is 0.1-40 parts.

6. The method of claim 5, wherein the step of determining the position of the probe is performed,

The hydrofining catalyst has its hydrogenation metal sulfide selected from the sulfide combination of nickel and/or cobalt, molybdenum and/or tungsten; and/or the number of the groups of groups,

The catalyst carrier is used in an amount of 65-99.9 parts by weight based on 100 parts by weight of the hydrofining catalyst; the dosage of the hydrogenated metal sulfide is 0.1-35 parts.

7. The method of claim 6, wherein the step of providing the first layer comprises,

The catalyst carrier is used in an amount of 70-99.9 parts by weight based on 100 parts by weight of the hydrofining catalyst; the dosage of the hydrogenated metal sulfide is 0.1-30 parts.

8. The method of claim 1, wherein the step of determining the position of the substrate comprises,

The reaction conditions for selecting the conversion in step 2) include:

the volume ratio and the pressure condition of the hydrogen and the oil are the same as those of the hydrofining reaction; and/or the number of the groups of groups,

The reaction temperature is 280-450 ℃; and/or the number of the groups of groups,

The liquid hourly space velocity is 0.5-4.0 h ^-1; and/or the number of the groups of groups,

The selective conversion catalyst is added in the step 2).

9. The method of claim 8, wherein the step of determining the position of the first electrode is performed,

The reaction conditions for selecting the conversion in step 2) include:

the reaction temperature is 300-430 ℃; and/or the number of the groups of groups,

The liquid hourly space velocity is 0.6-3.0 h ^-1.

10. The method of claim 9, wherein the step of determining the position of the substrate comprises,

The reaction conditions for selecting the conversion in step 2) include:

The reaction temperature is 310-400 ℃; and/or the number of the groups of groups,

The liquid hourly space velocity is 0.8-2.0 h ^-1.

11. The method according to claim 1, wherein in the selective conversion catalyst,

The silicon-aluminum ratio of the beta zeolite is 10-200; and/or the number of the groups of groups,

The thickness range of the lamellar MWW type zeolite is 2-10 nm; the silicon-aluminum ratio is 10-100; and/or the number of the groups of groups,

The beta zeolite accounts for 60-95% of the total weight of the beta zeolite and the layered MWW zeolite in percentage by mass.

12. The method according to claim 11, wherein in the selective conversion catalyst,

The silicon-aluminum ratio of the beta zeolite is 15-100; and/or the number of the groups of groups,

2-25 Parts of VIB group metal sulfide based on 100 parts by weight of the total amount of the beta zeolite and the layered MWW zeolite; 10-1000 parts of a first binder; the metal function regulating component is 0.5-30 parts.

13. The method according to claim 12, wherein in the selective conversion catalyst,

3-15 Parts of VIB group metal sulfide based on 100 parts by weight of the total amount of the beta zeolite and the layered MWW zeolite; 10-900 parts of first binder; the metal function regulating component is 1-20 parts.

14. The method according to claim 1, wherein the method for preparing the selective conversion catalyst comprises:

step a), mixing beta zeolite and layered MWW zeolite with a first adhesive, kneading, extruding strips, drying and roasting to obtain a catalyst carrier;

Step b) preparing an aqueous solution of a composite metal compound, wherein the composite metal compound comprises a VIB group metal compound and a VIII group metal and IIB group metal soluble metal compound;

Step c), immersing the catalyst carrier obtained in the step a) in the composite metal compound aqueous solution obtained in the step b), and then drying and roasting to obtain a catalyst precursor;

Step d) sulfiding the catalyst precursor from step c) to obtain the selective conversion catalyst.

15. The method according to claim 14, wherein the selective conversion catalyst is prepared by:

the drying temperature of the step a) is 60-150 ℃; and/or the number of the groups of groups,

The roasting temperature of the step a) is 500-600 ℃, and roasting is carried out for 3-6 hours; and/or the number of the groups of groups,

The composite metal compound in the step b) is at least one selected from ammonium tungstate, ammonium molybdate, nickel nitrate, nickel sulfate, nickel halide, nickel oxalate, nickel acetate, cobalt nitrate, cobalt chloride, cobalt oxalate, zinc nitrate, zinc chloride, zinc oxalate and zinc acetate; and/or the number of the groups of groups,

The concentration of the composite metal compound aqueous solution in the step b) is 3-50wt%; and/or the number of the groups of groups,

The drying temperature of the step c) is 60-150 ℃; and/or the number of the groups of groups,

The roasting temperature in the step c) is 450-520 ℃ and the roasting time is 1-4 h.

16. The method according to claim 15, wherein the selective conversion catalyst is prepared by:

the concentration of the composite metal compound aqueous solution in the step b) is 5-40 wt%.

17. The method according to claim 2, wherein in the step 3):

the separation comprises gas-liquid separation, rectification and extraction; and/or the number of the groups of groups,

The aromatic hydrocarbon content in the third stream is greater than 80wt%.

18. The method according to claim 17, wherein in step 3):

The aromatic hydrocarbon content in the third stream is greater than 90wt%.

19. The method according to claim 2, wherein in step 4):

The hydrogenation saturation reaction is a liquid hydrogenation reaction; and/or the number of the groups of groups,

The reaction temperature is 100-300 ℃; and/or the number of the groups of groups,

The partial pressure of hydrogen is 1.0-4.0 MPa; and/or the number of the groups of groups,

The liquid hourly space velocity is 0.1-5.0 h ^-1; and/or the number of the groups of groups,

The saturation catalyst is selected after the addition in the step 4).

20. The method according to claim 19, wherein in step 4):

The hydrogenation saturation reaction conditions include: the volume ratio of the hydrogen to the oil is 200-3000 Nm ³/m³; and/or the number of the groups of groups,

The reaction temperature is 120-280 ℃; and/or the number of the groups of groups,

The partial pressure of hydrogen is 1.2-3.0 MPa; and/or the number of the groups of groups,

The post-selective saturation catalyst comprises: amorphous silica alumina, a group VIII metal, and a second binder.

21. The method according to claim 20, wherein in step 4):

the hydrogenation saturation reaction conditions include: the volume ratio of hydrogen to oil is 300-1500 Nm ³/m³; and/or the number of the groups of groups,

The reaction temperature is 150-250 ℃; and/or the number of the groups of groups,

The liquid hourly space velocity is 0.6-2.0 h ^-1.

22. The method according to claim 21, wherein in step 4):

The hydrogenation saturation reaction conditions include: the volume ratio of hydrogen to oil is 300-1000 Nm ³/m³.

23. The method of claim 20, wherein the step of determining the position of the probe is performed,

The content of silicon oxide in the amorphous silicon aluminum of the post-selection saturated catalyst is 3-20wt%; and/or the number of the groups of groups,

The VIII group metal of the post-selective saturation catalyst is at least one of platinum, palladium, cobalt, nickel and iridium; and/or the number of the groups of groups,

The second binder of the post-selective saturation catalyst is selected from alumina; and/or the number of the groups of groups,

In the post-selection saturated catalyst, 10-90 parts of amorphous silicon aluminum, 0.1-5 parts of VIII metal and 5-80 parts of second binder are calculated by taking the total weight of the post-selection saturated catalyst as 100 parts by weight.

24. An apparatus for producing light hydrocarbons using the method of any one of claims 1 to 23, comprising:

first reaction zone: receiving catalytic diesel, carrying out hydrofining reaction in a hydrofining reactor and discharging a first material flow;

a second reaction zone; receiving the first stream, performing a selective conversion reaction in a hydrocracking reactor, and discharging a second stream;

post-selection saturation reaction zone: receiving the third stream, conducting a hydrofinishing reaction in a hydrofinishing vessel and discharging a fourth stream;

The selective conversion catalyst adopted in the selective conversion reaction in the second reaction zone comprises beta zeolite, layered MWW zeolite, VIB group metal sulfide, a first binder and a metal function regulating component, wherein the layered MWW zeolite is SRZ-21 zeolite, the VIB group metal sulfide is selected from at least one of sulfide of Mo and W, the first binder is selected from one of aluminum oxide and silicon oxide, and the metal function regulating component is selected from at least one of nickel sulfide, cobalt sulfide and zinc sulfide; the thickness range of the lamellar MWW type zeolite is 2-12 nm, and the silicon-aluminum ratio is 8-150; the beta zeolite accounts for 50-99% of the total weight of the beta zeolite and the layered MWW zeolite in percentage by mass; the total amount of the beta zeolite and the layered MWW zeolite is calculated as 100 parts by weight, and the VI B metal sulfide is 1-30 parts; 5-2000 parts of first binder; and 0.5-30 parts of metal function regulating component.

25. The apparatus of claim 24, wherein the device comprises a plurality of sensors,

The inlet temperature of the hydrofining reactor is 250-450 ℃; and/or the number of the groups of groups,

The inlet temperature of the hydrocracking reactor is 280-450 ℃; and/or the number of the groups of groups,

The inlet temperature of the hydrogenation saturation reactor is 100-300 ℃, and the partial pressure of the reaction hydrogen is 1.0-4.0 MPa; and/or the number of the groups of groups,

The reactors of the first reaction zone, the second reaction zone and the later selective saturation reaction zone are fixed bed reaction systems; and/or the number of the groups of groups,

The first separation zone comprises a gas-liquid separator, a rectifying tower and an extraction device which are connected in sequence; and/or the number of the groups of groups,

26. The apparatus of claim 25, wherein the device comprises a plurality of sensors,

The fixed bed reaction systems of the first reaction zone and the second reaction zone are configured with a shared circulating hydrogen system; and/or the number of the groups of groups,

The fixed bed reaction system of the post-selective saturation reaction zone is a liquid phase hydrogenation reaction system without a circulating hydrogen system; and/or the number of the groups of groups,

The rectifying tower of the first reaction zone comprises a depentanizer, a deheptanizer, a dimethylbenzene tower and a heavy aromatic tower which are connected in sequence.

27. Use of the method for producing light hydrocarbons according to any one of claims 1 to 23 or the apparatus according to any one of claims 24 to 26 for producing light alkanes and light aromatics from catalytic diesel.