CN112745921B

CN112745921B - Hydroconversion process for long side chain alkyl containing aromatic hydrocarbon feed

Info

Publication number: CN112745921B
Application number: CN201911047738.2A
Authority: CN
Inventors: 杨平; 秦康; 毛以朝; 胡志海; 任亮
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2019-10-30
Filing date: 2019-10-30
Publication date: 2023-02-21
Anticipated expiration: 2039-10-30
Also published as: CN112745921A

Abstract

The invention provides a method for hydroconversion of a long-side-chain-alkyl-containing aromatic hydrocarbon material, which comprises the following steps: introducing a material containing long side chain alkyl aromatic hydrocarbon into a hydrofining reaction zone in the presence of hydrogen to obtain a hydrofining effluent; and introducing the hydrofined effluent into a hydrocracking reaction zone to obtain a hydrocracking effluent, wherein a hydrocracking catalyst I containing a carrier I is filled in an upstream zone of the hydrocracking reaction zone, a hydrocracking catalyst II containing a carrier II is filled in a downstream zone of the hydrocracking reaction zone, the B acid amount of the carrier I is lower than that of the carrier II, and the B acid density of the carrier I is lower than that of the carrier II. The hydro-conversion method of the invention adjusts the cracking depth of the long alkyl side chain in the alkyl aromatic hydrocarbon conversion process by filling different hydrocracking catalysts in a combined manner, retains the molecular structure of the long alkyl side chain to the maximum extent, improves the product value, reduces the hydrogen consumption and increases the process economy.

Description

Hydroconversion process for long side chain alkyl-containing aromatic hydrocarbon feed

Technical Field

The invention relates to the field of hydrocracking, in particular to a hydroconversion method of a long-side-chain-alkyl-containing aromatic hydrocarbon material.

Background

Crude oil resources are getting heavier, mainly represented by the gradual increase of the content of aromatic hydrocarbons in crude oil, particularly the gradual increase of the content of polycyclic aromatic hydrocarbons in heavy fractions. Meanwhile, with the enhancement of environmental awareness, the requirement on aromatic hydrocarbon in the fuel oil standard is increasingly strict, and the upper limit of the content of polycyclic aromatic hydrocarbon in the vehicle diesel oil is reduced from 11% to 7% in the national hexafuel oil standard implemented by 2019. Therefore, the high-efficiency conversion of polycyclic aromatic hydrocarbons is receiving wide attention, and various polycyclic aromatic hydrocarbon conversion technologies are generated. Hydrocracking, one of the main means for upgrading heavy oils, also has significant advantages in aromatics conversion. A great deal of research finds that partial hydrogenation of aromatic hydrocarbons and selective ring opening are one of the ways for efficient conversion of aromatic hydrocarbons, but over-cracking of ring opening products results in high yield of low value-added products such as low-carbon alkanes and high chemical hydrogen consumption, and the economy needs to be improved.

CN 104646052A discloses a preparation method of a ring-opening catalyst for selective hydrogenation of aromatic hydrocarbons with more than two rings, wherein a catalyst carrier consists of alumina, amorphous silica-alumina, a modified small-crystal Beta type molecular sieve and a SAPO/ZSM-5 composite molecular sieve. The catalyst matches a hydrogenation active center, an isomerization active center and a cracking active center of the catalyst through different types of molecular sieve compounding technologies and active metal positioning loading and regulating technologies, so that the catalyst shows excellent aromatic ring opening selectivity in the hydrogenation process of poor distillate oil rich in aromatic hydrocarbons with more than two rings. However, the preparation process of the catalyst is complicated.

CN 104117386A discloses a catalyst for a polycyclic aromatic hydrocarbon hydrogenation ring-opening reaction, which takes a modified H-Beta molecular sieve with high silica-alumina ratio and an inorganic oxide as carriers, and takes noble metals Pt, pd or Ir as active components. The catalyst has the characteristics of inhibiting deep cracking and promoting the selective ring opening of aromatic hydrocarbon and the isomerization of products. However, noble metal catalysts are expensive and prone to sulfur poisoning.

CN 104043473A discloses a preparation method of a hydrocracking catalyst, which comprises the steps of mixing a Y-type zeolite molecular sieve with a Mo-containing compound and a Ni-containing compound, treating the mixture in an atmosphere containing water vapor to obtain a MoNiY-type zeolite molecular sieve containing Mo and Ni, and preparing the catalyst by taking the MoNiY-type zeolite molecular sieve as an acidic component. When the catalyst is used for diesel oil hydrogenation modification, secondary cracking of an aromatic ring-opening product in the diesel oil can be inhibited, so that the yield of the selective ring-opening product is improved, and the quality of the diesel oil is improved while the high yield of the diesel oil is kept.

The aromatics in the hydrocracking raw material usually have side chains and even long side chains, and the ring opening reaction of the aromatics also can generate longer side chains, and the long alkyl side chains can generate side chain breaking reaction and generate paraffin which is easy to generate deep cracking reaction under the action of the conventional hydrocracking catalyst, because the breaking of the alkyl side chains and the cracking reaction of the paraffin are easier to generate compared with the ring opening reaction, but the hydrogen consumption of the process is increased, and a large amount of low-molecular low-carbon alkane such as propane, butane and the like can be produced. Therefore, inhibiting the excessive cracking of the alkyl side chain of the long-side chain alkyl aromatic hydrocarbon or the ring-opening product of the aromatic hydrocarbon is one of the main means for regulating and controlling the product structure in the hydrogenation conversion process of the aromatic hydrocarbon, reducing the chemical hydrogen consumption and improving the economic benefit

It is noted that the information disclosed in the foregoing background section is only for enhancement of background understanding of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a method capable of effectively inhibiting the long side chain overcracking of alkyl in the process of hydro-conversion of alkyl aromatic hydrocarbon.

In order to achieve the purpose, the invention adopts the following technical scheme:

a process for the hydroconversion of a long side chain alkyl aromatic-containing feedstock comprising the steps of:

introducing a material containing long side chain alkyl aromatic hydrocarbon into a hydrofining reaction zone in the presence of hydrogen to obtain a hydrofining effluent; and

introducing the hydrofining effluent into a hydrocracking reaction zone to obtain a hydrocracking effluent,

the hydrocracking reaction zone comprises an upstream area and a downstream area along the material flow direction, wherein the upstream area is filled with a hydrocracking catalyst I containing a carrier I, the downstream area is filled with a hydrocracking catalyst II containing a carrier II, the B acid content of the carrier I is lower than that of the carrier II, and the B acid density of the carrier I is lower than that of the carrier II.

In some embodiments, the long side chain alkyl-containing aromatic hydrocarbon material is an alkyl aromatic hydrocarbon having at least one side chain with a carbon number greater than or equal to 4, preferably at least one side chain with a carbon number greater than 5 and less than 25.

In some embodiments, the amount of carrier i photoacid per unit weight is 30% or less, preferably 20% or less, of the amount of carrier ii photoacid per unit weight.

In some embodiments, the density of the B acid of carrier I is less than 40%, preferably less than 30%, of the density of the B acid of carrier II, based on the density of the B acid of carrier II.

In some embodiments, the hydrocracking catalyst I comprises 60-85wt% of the carrier I, 1.5-6wt% of the VIII group metal component and 10-35wt% of the VIB group metal component on oxide basis, and the hydrocracking catalyst II comprises 60-85wt% of the carrier II, 1.5-6wt% of the VIII group metal component and 10-35wt% of the VIB group metal component.

In some embodiments, the support I comprises modified alumina and/or amorphous silica-alumina and a matrix I, and the support II comprises a silica-alumina molecular sieve and a matrix II.

In some embodiments, the modified alumina and/or amorphous silica-alumina content of the support I is 50 to 99.5wt%, and the matrix I content is 0.5 to 50wt%.

In some embodiments, the modified alumina is one or more of F, P, B, mg, and the like. In some embodiments, the content of the silicon-aluminum molecular sieve in the carrier II is 10-50 wt%, and the content of the matrix II is 50-90 wt%.

In some embodiments, the substrate i and the substrate ii are each independently selected from one or more of alumina, silica, and silica-alumina.

In some embodiments, the packing volume ratio of the hydrocracking catalyst i to the hydrocracking catalyst ii is 1.

In some embodiments, the reaction conditions of the hydrocracking reaction zone are: the reaction pressure is 2-15 MPa, the reaction temperature is 300-415 ℃, the volume ratio of hydrogen to oil is 100-1500, and the volume space velocity is 0.5-10.0 h ^-1 。

In some embodiments, the hydrocracking reaction zoneThe reaction conditions of (A) are as follows: the reaction pressure is 3-12 MPa, the reaction temperature is 320-380 ℃, the volume ratio of hydrogen to oil is 300-800, and the volume airspeed is 1.0-6.0 h ^-1 。

The invention improves the matching property of the catalyst property and the reaction process by filling the hydrocracking catalysts with different properties in a combined manner, can inhibit the over-cracking of alkyl side chains during the conversion of alkyl aromatic hydrocarbon, improves the content of long-chain paraffin in products, reduces the yield of low-carbon paraffin and chemical hydrogen consumption, increases the yield of high-value products, improves the economical efficiency of the process, and realizes the high-efficiency conversion of long-chain alkyl polycyclic aromatic hydrocarbon.

Detailed Description

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

In the present invention, anything or matters not mentioned is directly applicable to those known in the art without any change except those explicitly described. Moreover, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solutions or concepts formed thereby are considered part of the original disclosure or original description of the present invention, and should not be considered as new matters not disclosed or contemplated herein, unless such combination is considered clearly unreasonable by those skilled in the art.

All features disclosed in this invention may be combined in any combination and such combinations are understood to be disclosed or described herein unless a person skilled in the art would consider such combinations to be clearly unreasonable. The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and these ranges or values should be understood to encompass values close to these ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

Taking dodecylnaphthalene as an example, the inventor of the present invention found in research that when a traditional hydrocracking process is adopted, dodecylnaphthalene is easy to undergo dealkylation, and an alkyl side chain is continuously over-cracked to generate a large amount of micromolecular products, namely C3 and C4 alkanes, and the added value of the products is low and the chemical hydrogen consumption is high.

Therefore, the invention provides a method for hydro-conversion of a material containing long side chain alkyl aromatic hydrocarbon, so as to effectively inhibit the excessive cracking of alkyl aromatic hydrocarbon side chains in the hydro-conversion process.

The hydroconversion process of the present invention comprises: introducing a material containing long side chain alkyl aromatic hydrocarbon into a hydrofining reaction zone in the presence of hydrogen to obtain a hydrofining effluent; and introducing the hydrofining effluent into a hydrocracking reaction zone to obtain a hydrocracking effluent.

In the hydroconversion method, a hydrocracking reaction zone comprises an upstream zone and a downstream zone along the material flow direction, wherein a hydrocracking catalyst I containing a carrier I is filled in the upstream zone, a hydrocracking catalyst II containing a carrier II is filled in the downstream zone, and a hydrofining effluent firstly flows through the upstream zone and contacts with the hydrocracking catalyst I, and then flows through the downstream zone and contacts with the hydrocracking catalyst II.

The long side chain alkyl-containing aromatic hydrocarbon material treated by the invention is at least one alkyl aromatic hydrocarbon with a side chain of which the carbon number is more than or equal to 4, preferably at least one alkyl aromatic hydrocarbon with a side chain of which the carbon number is more than 5 and less than 25, such as nonyl benzene, dodecyl naphthalene, dodecyl pyrene and the like.

The amount of B acid in the carrier I is lower than that in the carrier II, wherein the amount of B acid is Bronsted acid and is measured by pyridine absorption infrared spectroscopy (Py-IR). The amount of the B acid per unit weight of the carrier I is 30% or less, preferably 20% or less, based on the amount of the B acid per unit weight of the carrier II.

The density of B acid of the carrier I is also lower than that of B acid of the carrier II, wherein the density of B acid refers to the amount of B acid per unit specific surface area of the catalyst carrier, specifically the total amount of B acid of the carrier/specific surface area of the carrier, and the specific surface area is formed byN ₂ Obtained by the characterization of a static adsorption and desorption method (BET for short). The B acid density of the carrier I is 40% or less, preferably 30% or less, based on the B acid density of the carrier II.

In the hydroconversion method, the filling ratio of the hydrocracking catalyst I to the hydrocracking catalyst II is 1

In the hydroconversion method, a carrier I comprises modified alumina and/or amorphous silica-alumina and a matrix I, wherein the content of the modified alumina and/or amorphous silica-alumina is 50-99.5 wt%, and the content of the matrix I is 0.5-50 wt%; the carrier II comprises a silicon-aluminum molecular sieve and a matrix II, wherein the content of the silicon-aluminum molecular sieve is 10-50 wt%, and the content of the matrix II is 50-90 wt%.

The modified alumina used in the present invention may contain one or more of F, P, B, mg and the like, and the alumina is modified with the above elements.

In the hydroconversion process of the present invention, the substrate I and the substrate II may be the same or different, and any substrate may be selected as the substrate for preparing the hydrogenation catalyst carrier. In a preferred embodiment, the substrates I and II are each independently selected from one or more of alumina, silica and silica-alumina, which are commercially available or obtained by any of the existing methods.

The carrier can be made into various easy-to-handle molded objects according to different requirements, such as microspheres, spheres, tablets or strips. The shaping can be carried out in a conventional manner, for example, by extruding the molecular sieve or modified alumina or amorphous silica-alumina, with or without refractory inorganic oxide, into strips and calcining. When the carrier is extruded and formed, a proper amount of extrusion aid and/or adhesive can be added into the carrier, and then the carrier is extruded and formed. The kind and amount of the extrusion aid and the peptizing agent are well known to those skilled in the art, for example, the common extrusion aid can be one or more selected from sesbania powder, methyl cellulose, starch, polyvinyl alcohol and polyvinyl alcohol.

In the hydro-conversion method, the hydrocracking catalyst I and the hydrocracking catalyst II are both supported catalysts which both comprise a carrier and an active metal component loaded on the carrier. The active metal component may comprise at least one metal component selected from group VIII and at least one metal component selected from group VIB. The metal component of group VIII may be iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, etc., and the metal component of group VIB may be chromium, molybdenum, tungsten, etc. The active metal component is usually supported on the support in the form of a metal oxide. The weight, the metal system and the content of the carrier on the hydrocracking catalyst I and the hydrocracking catalyst II can be different or the same.

Based on oxides, the hydrocracking catalyst I comprises 60-85wt% of carrier I, 1.5-6wt% of VIII group metal component and 10-35wt% of VIB group metal component, and the hydrocracking catalyst II comprises 60-85wt% of carrier II, 1.5-6wt% of VIII group metal component and 10-35wt% of VIB group metal component.

The present invention is not particularly limited to the supporting method on the premise that it is sufficient to support the active metal component on the carrier, and a preferable method is an impregnation method comprising preparing an impregnation solution of the metal component-containing compound, and thereafter impregnating the carrier with the solution. The impregnation method is a conventional method, and for example, it may be an excess liquid impregnation method, a pore saturation method impregnation method. Wherein the specified amount of catalyst can be prepared by adjusting and controlling the concentration, amount or support amount of the impregnation solution containing the metal component, as will be readily understood and realized by those skilled in the art.

The compound containing the metal component selected from VIB group can be one or more of soluble compounds, such as one or more of molybdenum oxide, molybdate and paramolybdate, preferably molybdenum oxide, ammonium molybdate and paramolybdate; one or more of tungstate, metatungstate and ethyl metatungstate, preferably ammonium metatungstate and ethyl ammonium metatungstate.

The compound containing the group VIII metal component can be selected from one or more soluble compounds thereof, such as one or more soluble complexes of cobalt nitrate, cobalt acetate, basic cobalt carbonate, cobalt chloride and cobalt, preferably cobalt nitrate and basic cobalt carbonate; one or more of nickel nitrate, nickel acetate, basic nickel carbonate, nickel chloride and soluble complex of nickel, preferably nickel nitrate and basic nickel carbonate.

The catalyst provided by the invention can also contain one or more organic compounds selected from oxygen-containing or nitrogen-containing organic compounds, and the preferable oxygen-containing organic compound is one or more selected from organic alcohol and organic acid; the preferable nitrogen-containing organic compound is one or more selected from organic amines. Examples of the oxygen-containing organic compound include one or more of ethylene glycol, glycerol, polyethylene glycol (molecular weight 200 to 1500), diethylene glycol, butanediol, acetic acid, maleic acid, oxalic acid, nitrilotriacetic acid, 1, 2-cyclohexanediaminetetraacetic acid, citric acid, tartaric acid, and malic acid, and examples of the nitrogen-containing organic compound include ethylenediamine, EDTA, and ammonium salts thereof. The organic compound and metal components selected from VIII group and VIB group are prepared into impregnation liquid together to optimize a metal precursor and improve the interaction between metal and a carrier on a catalyst, and the molar ratio of the organic compound to the sum of the VIII group metal components and the VIB group metal components calculated by oxides is 0.03-2, preferably 0.08-1.5.

In the hydroconversion method of the invention, the catalyst used in the hydrorefining reaction zone can be various commercial catalysts, and can also be prepared according to the prior art in the field, and the reaction conditions in the hydrorefining reaction zone can adopt the process parameters of the prior hydrorefining reaction and can be properly adjusted according to the reaction raw materials.

In the hydroconversion method of the invention, the reaction conditions of the hydrocracking reaction zone are as follows: the reaction pressure is 2-15 MPa, the reaction temperature is 300-415 ℃, the volume ratio of hydrogen to oil is 100-1500, and the volume airspeed is 0.5-10.0 h ^-1 More preferred reaction conditions are: the reaction pressure is 3-12 MPa, the reaction temperature is 320-380 ℃, the volume ratio of hydrogen to oil is 300-800, and the volume airspeed is 1.0-6.0 h ^-1 。

Once the hydrocracked effluent is obtained, it may be separated and fractionated to obtain further products, which may be carried out using methods and apparatus conventional in the art.

The researches show that long-side chain alkyl aromatic hydrocarbon generally undergoes cracking or dealkylation of alkyl side chains to generate naked-ring cyclic hydrocarbon or side chain-broken cyclic hydrocarbon and long-chain alkane, then the long-chain alkane undergoes overcracking to generate small-molecular low-carbon alkane, and meanwhile the cyclic hydrocarbon undergoes ring opening and cracking reactions. And the excessive cracking reaction of paraffin is more likely to occur than the ring-opening reaction of cyclic hydrocarbon. However, in the case of a heterogeneous catalytic reaction process, the adsorption of hydrocarbon molecules is preferred before the reaction, while for a hydrocracking catalyst, the adsorption constants of hydrocarbon molecules with different structures are significantly different, for example, the adsorption of polycyclic aromatic hydrocarbons is significantly stronger than that of paraffin hydrocarbons.

The hydro-conversion method of the invention carries out reasonable catalyst grading based on the structure-activity relationship of hydrocarbon reaction chemistry and different types of hydrocracking catalysts in the hydrocracking process, strengthens the matching degree of the catalyst property and the reaction process based on the alkyl aromatic hydrocarbon hydrogenation reaction process, obtains a composite catalyst bed layer by combining and filling the hydrocracking catalysts with different properties, and leads reactants to contact proper catalysts in turn.

Specifically, at the initial stage of reaction, the material contacts with a hydrocracking catalyst I with less B acid and low B acid density, dealkylation and cracking reactions of long side chains of alkyl aromatics mainly occur, and simultaneously, the activity of secondary cracking reactions of lower side chains is kept, so that cyclic hydrocarbon and long-chain paraffin are generated; then the material contacts with a hydrocracking catalyst II with high B acid content and high B acid density, the ring opening reaction of naked ring or short chain cyclic hydrocarbon is mainly carried out by utilizing the characteristic that the adsorption of the cyclic hydrocarbon, especially aromatic hydrocarbon, on an acid center is obviously stronger than that of paraffin hydrocarbon, and the paraffin hydrocarbon is basically not cracked, namely long chain alkyl aromatic hydrocarbon mainly generates monocyclic aromatic hydrocarbon and paraffin hydrocarbon, and the original structure of hydrocarbon molecules is retained to the maximum extent. The cyclic aromatic hydrocarbon is converted into high-value monocyclic aromatic hydrocarbon such as BTX, and paraffin is an ideal low-carbon olefin raw material, so that the aim of 'aromatic hydrocarbon in case of aromatic hydrocarbon and alkene in case of olefinic hydrocarbon' is fulfilled; and reduces the hydrogen consumption of the process and improves the economy.

The present invention will be described in detail with reference to examples, but the scope of the present invention is not limited thereto.

Examples

Reagents, instruments and tests

Unless otherwise specified, the reagents used in the present invention are all analytical reagents, and the reagents used are all commercially available, for example, from Bailingwei and the national drug group.

In the following examples, preparations and comparative examples, the method of measuring the amount of acid B is as follows:

an FTS3000 Fourier Infrared spectrometer manufactured by BIO-RAD company, USA is adopted.

And (3) testing conditions are as follows: pressing the sample into tablet, sealing in an in-situ cell of an infrared spectrometer, and vacuumizing to 10 deg.C at 350 deg.C ^-3 Pa, keeping for 1h to enable gas molecules on the surface of the sample to be desorbed completely, and cooling to room temperature. Introducing pyridine vapor with pressure of 2.67Pa into the in-situ tank, balancing for 30min, heating to 200 deg.C, and vacuumizing to 10 deg.C ^-3 Pa, maintaining for 30min, cooling to room temperature at 1400-1700cm ^-1 Scanning in wave number range, and recording infrared spectrogram of pyridine adsorption at 200 ℃. Then the sample in the infrared absorption cell is moved to a heat treatment area, the temperature is raised to 350 ℃, and the vacuum is pumped to 10 DEG ^-3 Pa, keeping for 30min, cooling to room temperature, and recording an infrared spectrogram of pyridine adsorption at 350 ℃. The instrument automatically integrates to obtain the acid B amount.

In the following examples, preparations and comparative examples, the specific surface area of the carrier was measured by a nitrogen adsorption and desorption method.

The specific measurement method is as follows: the measurement was carried out by using AS-3, AS-6 static nitrogen adsorption apparatus manufactured by Quantachrome instruments.

And (3) testing conditions: the sample was placed in a sample handling system and evacuated to 1.33X 10 at 300 deg.C ^-2 Pa, keeping the temperature and the pressure for 4h, and purifying the sample. Under the condition of liquid nitrogen temperature of-196 ℃, testing the adsorption quantity and desorption quantity of the purified sample on the nitrogen under the condition of different specific pressures P/P0 to obtain N ₂ Adsorption-desorption isotherm curves. Then, the total specific surface area, the micropore specific surface area and the mesopore specific surface area are calculated by utilizing a two-parameter BET formula.

In the following examples, preparation examples and comparative examples, the kind and content of each metal element in the catalyst were measured by X-ray fluorescence spectroscopy (XRF) according to the protocol defined in RIPP 132-92 (edited by "analytical methods in petrochemical industry (RIPP methods of experiments"), yankee et al, science publishers, 1 st edition, 1990, p. 371-379). When the catalyst was tested, a sample of the catalyst was stored under an argon atmosphere.

Preparation example 1 preparation of modified alumina

100.0 g of pseudoboehmite (Changling catalyst division) was immersed in an aqueous solution containing 5.5g of ammonium fluoride for 3 hours, dried at 150 ℃ for 3 hours, and calcined at 550 ℃ in an air atmosphere for 3 hours to obtain a modified alumina containing F.

Preparation example 2 preparation of catalyst C-I-1

50.0 g of pseudo-boehmite (a product of Changling catalyst division, dry basis 0.71) and 191.9 g of modified alumina (prepared in preparation example 1) were mixed, extruded into clover-shaped strips with a circumscribed circle diameter of 1.6 mm, wet strips were dried at 150 ℃ for 3h, and calcined at 550 ℃ for 3h to obtain the carrier Z-I-1. The amount of B acid and the density of B acid in the carrier Z-I-1 are shown in Table 1.

100.0 g of the vector Z-I-1 was taken and 95 ml of MoO was added ₃ 280.7 g/l, niO 42.1 g/l, P ₂ O ₅ 28.1 g/l and 45.5 g/l of citric acid, and drying at 150 ℃ for 3 hours to obtain the catalyst C-I-1.

Preparation example 3 preparation of catalyst C-I-2

50.0 g of pseudo-boehmite (a product of Changling catalyst division, dry basis 0.71) and 182.1 g of amorphous silicon-aluminum (a product of Changling catalyst division, dry basis 0.78) are mixed, extruded into clover-shaped strips with the diameter of an external circle of 1.6 mm, and the wet strips are dried at 150 ℃ for 3h and roasted at 550 ℃ for 3h to obtain the carrier Z-I-2. The amount of B acid and the density of B acid of the carrier Z-I-2 are shown in Table 1.

100.0 g of the vector Z-I-2 was taken and 100 ml of MoO was added ₃ 266.7 g/l, niO 40.0 g/l, P ₂ O ₅ 26.7 g/L and 43.2 g/L of citric acid, and the nickel and molybdenum complex solution is soaked for 4 hours and dried for 3 hours at 150 ℃ to obtain the catalyst C-I-2.

Preparation example 4 preparation of catalyst C-II-1

200.0 g of pseudo-boehmite (product of Changling catalyst division, dry basis 0.71) and 47.3 g of USY molecular sieve (product of Changling catalyst division, dry basis 0.75) are mixed, extruded into clover-shaped strips with the diameter of the circumscribed circle of 1.6 mm, and the wet strips are dried at 150 ℃ for 3h and roasted at 550 ℃ for 3h to obtain the carrier Z-II-1. The amount of B acid and the density of B acid in the carrier Z-II-1 are shown in Table 1.

100.0 g of the vector Z-II-1 was taken and 80 ml of MoO-containing solution was added ₃ 333.3 g/L, niO 49.9 g/L, P ₂ O ₅ 33.4 g/L and 54.0 g/L of the nickel and molybdenum complex solution of citric acid are dipped for 4 hours and dried for 3 hours at 150 ℃ to obtain the catalyst C-II-1.

Preparation example 5 preparation of catalyst C-II-2

200.0 g of pseudoboehmite (product of Changling catalyst division, 0.71 dry basis) and 81.1 g of USY molecular sieve (product of Changling catalyst division, 0.75 dry basis) are mixed and extruded into clover-shaped strips with the circumscribed circle diameter of 1.6 mm, and the clover-shaped strips are dried at 150 ℃ for 3h and roasted at 550 ℃ for 3h to obtain the carrier Z-II-2. The amount of B acid and the density of B acid in the carrier Z-II-2 are shown in Table 1.

100.0 g of the carrier Z-II-2 was taken and 76 ml of MoO-containing solution was added ₃ 350.8 g/L, niO 52.5 g/L, P ₂ O ₅ 35.2 g/L and 56.8 g/L of citric acid, and drying at 150 ℃ for 3 hours to obtain the catalyst C-II-2.

Preparation example 6 preparation of catalyst C-II-3

200.0 g of pseudo-boehmite (a product of Changling catalyst division, dry basis 0.71) and 43.3 g of Beta molecular sieve (a product of Changling catalyst division, dry basis 0.82) are mixed, extruded into clover-shaped strips with the diameter of an external circle of 1.6 mm, and the wet strips are dried at 150 ℃ for 3h and roasted at 550 ℃ for 3h to obtain the carrier Z-II-3. The amount of B acid and the density of B acid in the carrier Z-II-3 are shown in Table 1.

100.0 g of the vector Z-II-3 was taken and 75 ml of MoO was added ₃ 355.5 g/l, niO 53.2 g/l, P ₂ O ₅ 35.6 g/L and 57.6 g/L of the nickel and molybdenum complex solution of citric acid are dipped for 4 hours and dried for 3 hours at 150 ℃ to obtain the catalyst C-II-3.

TABLE 1 Carrier composition and Properties

Example 1

Before the reaction starts, firstly, presulfurizing a catalyst, specifically: the sulfurized oil being CS ₂ The weight percentage of the cyclohexane solution is 6 percent, the vulcanization pressure is 4.0MPa, the vulcanization temperature is 330 ℃, and the vulcanization time is 3 hours. Switching to the reaction oil and raising the temperature to the reaction temperature.

Introducing methylcyclohexane (the mass fraction of the dodecylnaphthalene is 50%) containing the dodecylnaphthalene into a hydrofining reaction zone of a miniature fixed bed in the presence of hydrogen to obtain a hydrofining effluent; the specific reaction conditions are as follows: the reaction temperature is 330 ℃, the reaction pressure is 4.0MPa, and the volume ratio of hydrogen to oil is 400:1, volume space velocity of 6.0h ^-1 。

The hydrocracking reaction zone was filled with the catalyst in a manner of "upstream filling of C-I-1, downstream filling of C-II-1 and a filling ratio of C-I-1 to C-II-1 of 1", the filling manner and the compounding ratio of the catalyst being shown in Table 2.

Introducing the hydrofining effluent into a hydrocracking reaction zone, wherein the reaction conditions are as follows: the reaction temperature is 360 ℃, the reaction pressure is 4.0MPa, the volume ratio of hydrogen to oil is 400, and the volume airspeed is 6.0h ^-1 And obtaining a hydrocracking effluent, and separating and fractionating the hydrocracking effluent and detecting the hydrocracking effluent.

For better comparison, the following two performance indicators are given and defined, and the test results are also shown in table 2.

Example 2

The procedure of example 1 was substantially the same, except that the catalyst was packed in such a manner that "C-I-1 was packed upstream, C-II-1 was packed downstream, and the packing ratio of C-I-1 to C-II-1 was 3", and the reaction results were as shown in Table 2.

Example 3

The procedure of example 1 was substantially the same, except that the catalyst loading was carried out in such a manner that "C-I-1 was loaded upstream, C-II-2 was loaded downstream, and the loading ratio of C-I-1 to C-II-2 was 1" and the reaction results were as shown in Table 2.

Example 4

The procedure of example 1 was substantially the same, except that the catalyst was packed in such a manner that "C-I-1 was packed upstream, C-II-3 was packed downstream, and the packing ratio of C-I-1 to C-II-3 was 1" and the reaction results were as shown in Table 2.

Example 5

The procedure of example 1 was substantially the same, except that the catalyst loading was carried out in such a manner that "C-I-2 was loaded upstream, C-II-2 was loaded downstream, and the loading ratio of C-I-2 to C-II-2 was 1" and the reaction results were as shown in Table 2.

Comparative example 1

Essentially the same procedure as in example 1, except that the hydrocracking reaction zone was charged with catalyst C-I-1 only, the results are shown in Table 2.

Comparative example 2

Essentially the same procedure as in example 1, except that the hydrocracking reaction zone was packed with catalyst C-II-2 only, the results are shown in Table 2.

TABLE 2 catalyst loading and evaluation results

The results in Table 2 show that the conversion of alkylaromatic is lower for the single-charge catalyst C-I-1, although the selectivity to C3+ C4 is lower; the single-packed catalyst C-II-2 has high conversion rate of alkyl aromatic hydrocarbon, but serious over-cracking of a side chain and high selectivity of C3+ C4. In comparison, in the embodiments 1-5 of the present invention, by loading hydrocracking catalysts with different properties in combination, the overcracking of alkyl side chain is inhibited during the conversion of alkyl aromatic hydrocarbon, so that the C8-C12 paraffin content in the hydrocracking product is significantly increased, the economic value of the product is high, and the chemical hydrogen consumption is significantly reduced

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

Claims

1. A process for hydroconversion of a long side chain alkyl-containing aromatic hydrocarbon feed, characterized by the steps of:

the hydrocracking reaction zone comprises an upstream area and a downstream area along the material flow direction, wherein the upstream area is filled with a hydrocracking catalyst I containing a carrier I, the downstream area is filled with a hydrocracking catalyst II containing a carrier II, the B acid content of the carrier I is lower than that of the carrier II, and the B acid density of the carrier I is lower than that of the carrier II;

the material containing long side chain alkyl aromatic hydrocarbon is alkyl aromatic hydrocarbon with at least one side chain with the carbon number more than or equal to 4;

the amount of the B acid of the carrier I per unit weight is less than 30% of the amount of the B acid of the carrier II per unit weight, based on the amount of the B acid of the carrier II;

on the basis of the density of the B acid of the carrier II, the density of the B acid of the carrier I is less than 40% of that of the B acid of the carrier II;

on the basis of an oxide, the hydrocracking catalyst I comprises 60-85wt% of the carrier I, 1.5-6wt% of VIII group metal components and 10-35wt% of VIB group metal components, and the hydrocracking catalyst II comprises 60-85wt% of the carrier II, 1.5-6wt% of VIII group metal components and 10-35wt% of VIB group metal components;

the carrier I comprises modified alumina and/or amorphous silica-alumina and a matrix I, and the carrier II comprises a silica-alumina molecular sieve and a matrix II;

the content of modified alumina and/or amorphous silicon-aluminum in the carrier I is 50-99.5 wt%, and the content of the matrix I is 0.5-50 wt%; the content of the silicon-aluminum molecular sieve in the carrier II is 10-50 wt%, and the content of the matrix II is 50-90 wt%;

the matrix I and the matrix II are respectively and independently selected from one or more of alumina, silica and silica-alumina.

2. The hydroconversion process of claim 1 wherein the long side chain alkyl-containing aromatic hydrocarbon feed is at least one alkyl aromatic hydrocarbon having a side chain with a number of carbon atoms in the range of 4 to 30.

3. The hydroconversion process of claim 2 wherein the long side chain alkyl-containing aromatic hydrocarbon feed is at least one alkyl aromatic hydrocarbon having a side chain with a number of carbon atoms greater than 5 and less than 25.

4. The hydroconversion process of claim 1, wherein the amount of carrier i ba acid per weight is less than 20% of the amount of carrier ii ba acid per weight, based on the amount of carrier ii ba acid.

5. The hydroconversion process of claim 1, wherein the density of the B acid on carrier I is less than 30% of the density of the B acid on carrier II.

6. The hydroconversion process according to claim 1, wherein the loading volume ratio of hydrocracking catalyst i to hydrocracking catalyst ii is 1.

7. The hydroconversion process of claim 6 wherein the loading volume ratio of hydrocracking catalyst I to hydrocracking catalyst II is from 1.

8. The hydroconversion process of claim 1, wherein the reaction conditions of the hydrocracking reaction zone are:

the reaction pressure is 2-15 MPa, the reaction temperature is 300-415 ℃, the volume ratio of hydrogen to oil is 100-1500, and the volume airspeed is 0.5-10.0 h ^-1 。

9. The hydroconversion process of claim 8, wherein the reaction conditions of the hydrocracking reaction zone are:

the reaction pressure is 3-12 MPa, the reaction temperature is 320-380 ℃, the volume ratio of hydrogen to oil is 300-800, and the volume airspeed is 1.0-6.0 h ^-1 。