Alkyl transfer catalyst, its preparation method, and alkyl transfer method

Abstract

The present invention relates to the technical field of aromatics alkyl transfer, and discloses an alkyl transfer catalyst, a preparation method thereof, and an alkyl transfer method. An alkyl transfer catalyst, the catalyst comprises a modified molecular sieve, a binder and a metal active component, wherein, the density ratio of the B acid to the L acid of the modified molecular sieve is 0.5 - 5, the external specific surface area is 40 - 200 m 2 / g, the microporous specific surface area is 100 - 400 m 2 / g, the total acid amount is 0.1 - 1.5 μmol / g NH3, and the intensity of the non-framework six-coordinate aluminum characteristic peak at 0 ppm in the Al nuclear magnetic spectrum is close to 0. The alkyl transfer catalyst in the present invention has high activity and can improve the xylene yield.

Description

Technical Field

[0001] The present invention relates to the technical field of alkyl transfer of aromatic hydrocarbons, and particularly relates to an alkyl transfer catalyst, a preparation method thereof, and an alkyl transfer method. Background Art

[0002] Benzene, toluene, xylene and C9 heavy aromatics can be obtained in the processes of naphtha reforming and cracking. + In recent years, due to the development of the plastics, synthetic fiber and synthetic rubber industries, the demand for benzene and xylene has increased rapidly, and their market prices are much higher than those of other aromatic hydrocarbons. In terms of price, usually xylene > benzene > toluene > C9 heavy aromatics. + Using low-value toluene and C9 heavy aromatics, + especially C9 heavy aromatics + to increase the production of more valuable xylene is an effective means to make full use of aromatic hydrocarbon resources and is currently widely used. The reaction system is relatively complex, and the main reactions are alkyl transfer reaction and dealkylation reaction of C9 heavy aromatics. The ratio of methyl groups to benzene rings in the reaction system directly determines the yield of the target product xylene. +

[0003] Therefore, at present, while improving the treatment capacity of C9 heavy aromatics, + how to reduce the loss of methyl groups to increase the yield of xylene has become an urgent problem to be solved in the technical progress of alkyl transfer of toluene and C9 heavy aromatics to produce benzene and xylene. +

[0004] Patent application CN108499597A discloses a toluene disproportionation and alkyl transfer catalyst and a preparation method thereof. The catalyst selectively deposits metal nanoparticles on the outer surface of the molecular sieve, effectively controls the position of the metal nanoparticles, inhibits the synergistic hydrogenation effect of the metal and acid sites, and alleviates the loss of aromatic rings caused by excessive hydrogenation of the metal.

[0005] Patent application CN1337890A discloses a molecular sieve catalyst containing noble metals. The catalyst uses 10 - 80% (by weight) of mordenite or beta zeolite and 0 - 70% (by weight) of ZSM-5, 5 - 90% (by weight) of γ-Al2O3 as carriers, and loads 0.001 - 0.5 parts by weight of platinum and 0.01 - 10.0 parts by weight of tin or 0.01 - 7.0 parts by weight of lead. This catalyst can process high C9 heavy aromatic hydrocarbon raw materials, and improve the yield of mixed xylene and the stability of the catalyst. This process inhibits the hydrogenation activity of the metal by adding metal promoters. +

[0006] ​​​Patent application CN107866265A discloses a method for selectively passivating an alkyl transfer catalyst. Using at least one of bicyclic or polycyclic aromatic hydrocarbons as a competitive adsorbent in the raw material to selectively passivate the hydrogenation metal catalyst can solve the problems of high initial activity and high aromatic ring loss of the catalyst. However, this competitive adsorbent will further polycondense on the catalyst and accelerate the carbon deposition of the catalyst.

[0007] The above patent literature suppresses the hydrogenation activity of metals by adding metal promoters during the catalyst preparation process or by introducing trace poisons. The application effects in suppressing the aromatic ring hydrogenation activity of metals are not very ideal or the implementation is relatively troublesome.

[0008] In summary, based on the existing methods, even when using metals to modify molecular sieves, their catalytic performance still cannot be effectively improved. Therefore, studying a new catalyst modification method is of great value and significance for improving the performance of toluene and C9 + heavy aromatics alkyl transfer catalysts. Summary of the Invention

[0009] The object of the present invention is to overcome the problem of poor catalytic performance of the catalyst during the alkyl transfer process in the prior art, and to provide an alkyl transfer catalyst, its preparation method, and an alkyl transfer method. This alkyl transfer catalyst has high activity and can improve the xylene yield.

[0010] The inventors of the present invention found during the research process that maximizing the utilization of methyl in the reaction system fundamentally stems from the optimization of the acid strength of the catalyst. Under the same reaction conditions and acid strength, the order of the dealkylation rate of the reaction raw materials from high to low is butyl > propyl > ethyl > methyl. If the acidity is too strong, it is easy to cause side reactions of demethylation, while if the acidity is too weak, it is not conducive to the dealkylation reaction of heavy aromatics, resulting in low conversion rate of heavy aromatics.

[0011] To achieve the above object, in the first aspect of the present invention, an alkyl transfer catalyst is provided. The catalyst includes a modified molecular sieve, a binder, and a metal active component, wherein the density ratio of B acid to L acid of the modified molecular sieve is 0.5 - 5, the external specific surface area is 40 - 200 m 2 / g, the microporous specific surface area is 100 - 400 m 2 / g, the total acid amount is 0.1 - 1.5 μmol / g NH3, and the intensity of the non-framework six-coordinate aluminum characteristic peak at 0 ppm in the Al nuclear magnetic spectrum is close to 0.

[0012] According to the present invention, preferably, the density ratio of B acid to L acid of the modified molecular sieve is 1 - 4.

[0013] In a preferred case, the external specific surface area of the modified molecular sieve is 60 - 150 m 2 / g, with a micropore specific surface area of 150 - 350 m 2 / g.

[0014] In a preferred case, the total acid amount of the modified molecular sieve is 0.5 - 1.5 μmol / g NH3.

[0015] The second aspect of the present invention provides a method for preparing an alkyl transfer catalyst, the method comprising the following steps:

[0016] (1) Subjecting the molecular sieve raw powder to steam treatment and acid treatment in sequence to obtain a modified molecular sieve;

[0017] (2) Modifying the modified molecular sieve with a metal active component or without modifying with a metal active component, then mixing with a binder, and then optionally forming;

[0018] This method also optionally includes: (3) impregnating the solid product obtained in step (2) in a solution containing a precursor of a metal active component.

[0019] The third aspect of the present invention provides an alkyl transfer method, the method comprising: under alkyl transfer conditions, contacting C9 + heavy aromatics and toluene with an alkyl transfer catalyst; the alkyl transfer catalyst is the alkyl transfer catalyst described in the first aspect or the alkyl transfer catalyst prepared by the preparation method described in the second aspect.

[0020] In the present invention, reducing the acid amount by steam treatment of the molecular sieve inhibits the excessive cracking reaction of aromatics. Subsequently, the molecular sieve treated with steam is subjected to acid treatment, and the acid-treated molecular sieve unblocks the molecular sieve pores blocked by non-framework aluminum brought about during the steam treatment process, improving the reaction activity. The alkyl transfer catalyst prepared by combining the modified molecular sieve of the present invention with a binder and a metal active component is used in the alkyl transfer reaction of toluene and C9 + heavy aromatics, reducing the methyl removal rate and increasing the xylene yield, and can be used in industrial production. Description of the Drawings

[0021] Figure 1 are the NH3-TPD curves of the molecular sieve before and after modification in Example 1 of this application. Detailed Embodiments

[0022] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0023] In the first aspect of the present invention, an alkyl transfer catalyst is provided. The catalyst comprises a modified molecular sieve, a binder and a metal active component, wherein the density ratio of Bronsted acid to Lewis acid of the modified molecular sieve is 0.5 - 5, the external specific surface area is 40 - 200 m 2 / g, the microporous specific surface area is 100 - 400 m 2 / g, the total acid amount is 0.1 - 1.5 μmol / g NH3, and the intensity of the non-framework six-coordinate aluminum characteristic peak at 0 ppm in the Al nuclear magnetic resonance spectrum is close to 0.

[0024] According to the present invention, preferably, the density ratio of Bronsted acid to Lewis acid of the modified molecular sieve is 1 - 4.

[0025] In a preferred case, the external specific surface area of the modified molecular sieve is 60 - 150 m 2 / g, and the microporous specific surface area is 150 - 350 m 2 / g.

[0026] In a preferred case, the total acid amount of the modified molecular sieve is 0.5 - 1.5 μmol / g NH3.

[0027] In the present invention, the acidity and acid amount of the molecular sieve are measured by using a Nicolet TM type infrared spectrometer (Py-IR) of the American Nicolet Corporation. During the test process, the sample is pressed into a tablet, evacuated to 10 -4 Pa, heated to 400 °C for heat treatment for 2 h. After the temperature drops to 200 °C, pyridine is statically adsorbed for 1 min, balanced for 5 min, then evacuated at low vacuum for 10 min, evacuated at high vacuum for 30 min, and then heated to 300 °C in 10 min and balanced for 5 min for IR scanning. The amounts of Bronsted acid and Lewis acid are calculated according to the absorption peak areas of the sample at 1540 cm -1 and 1450 cm -1 respectively.

[0028] In the present invention, the external specific surface area and the microporous specific surface area of the modified molecular sieve are measured by BET characterization. Specifically, a 3Flex-Physisorption type full-automatic specific surface area and pore size distribution analyzer of the American Micromeritics Corporation is used for N2 adsorption-desorption characterization of the molecular sieve. The adsorbate is high-purity N2, and the adsorption temperature is -196 °C. Before the test, the molecular sieve is pretreated by evacuation at 350 °C for 3 h to remove the adsorbed impurities. The specific surface area is calculated by the BET method, and the pore structure is analyzed by the BJH method of the adsorption branch. Ammonia temperature-programmed desorption (NH3-TPD) is carried out on an AutoChem2920 full-automatic temperature-programmed chemisorption instrument of Micrometrics Corporation, with a thermal conductivity detector.

[0029] In the present invention, the Al nuclear magnetic resonance spectrum was measured using a Bruker AMX-400 nuclear magnetic resonance spectrometer.

[0030] In the present invention, in the statement that "the intensity of the non-framework six-coordinate aluminum characteristic peak is close to 0", the intensity being "close to 0" means that there is no characteristic peak at a displacement of 0 ppm.

[0031] By adopting the above technical solution, the alkyl transfer catalyst provided by the present invention contains a specific modified molecular sieve, and this alkyl transfer catalyst can improve the yield of xylene and can be applied to industrial production.

[0032] In the present invention, there is no particular limitation on the type of the modified molecular sieve, and the modified molecular sieves defined conventionally in the art are all applicable to the present invention. Preferably, the modified molecular sieve is ZSM-5 and / or mordenite, and more preferably ZSM-5 and mordenite. The inventors of the present invention have found that the combination of ZSM-5 and mordenite can further improve the conversion rate of heavy aromatics and the selectivity of xylene aromatics.

[0033] According to the present invention, preferably, based on the total amount of the modified molecular sieve, the content of ZSM-5 is 10-50% by weight, and the content of mordenite is 50-90% by weight.

[0034] In a preferred embodiment, based on the total amount of the modified molecular sieve, the content of ZSM-5 is 20-40% by weight, and the content of mordenite is 60-80% by weight.

[0035] According to the present invention, preferably, based on the total amount of the modified molecular sieve and the binder, the content of the modified molecular sieve is 50-80% by weight, and the content of the binder is 20-50% by weight; relative to 100 parts by weight of the modified molecular sieve and the binder, the content of the metal active component is 0.01-3 parts by weight.

[0036] In a preferred embodiment, based on the total amount of the modified molecular sieve and the binder, the content of the modified molecular sieve is 50-75% by weight, and the content of the binder is 25-50% by weight; relative to 100 parts by weight of the modified molecular sieve and the binder, the content of the metal active component is 0.01-2 parts by weight.

[0037] In the present invention, the contents of the modified molecular sieve, the binder, and the metal active component in the catalyst are obtained by calculation.

[0038] In the present invention, there is no particular limitation on the type of the binder, and the binders defined conventionally in the art are all applicable to the present invention. Preferably, the binder is at least one of alumina, silica sol, clay, and diatomaceous earth, and more preferably alumina and / or silica sol.

[0039] According to a preferred embodiment of the present invention, the binder is alumina.

[0040] In the present invention, the alumina may be selected from at least one of γ-alumina, δ-alumina, ρ-alumina, κ-alumina, and χ-alumina, and the present invention has no particular limitation thereto.

[0041] In the present invention, there is no particular limitation on the type of the metal active group, and the metal active components defined in the art are all applicable to the present invention. Preferably, the metal active component is selected from at least one of the metals of Group VIB, Group VIIB, and Group VIII.

[0042] In a preferred case, the metal of Group VIB is selected from at least one of chromium, molybdenum, and tungsten.

[0043] In a preferred case, the metal of Group VIIB is selected from at least one of manganese, technetium, and rhenium.

[0044] In a preferred case, the metal of Group VIII is selected from at least one of iron, cobalt, nickel, ruthenium, rhodium, palladium, and platinum.

[0045] More preferably, the metal active component is selected from at least one of Ni, Mo, Re, and Pt.

[0046] The second aspect of the present invention provides a method for preparing an alkyl transfer catalyst, the method comprising the following steps:

[0047] (1) Subjecting the molecular sieve raw powder to steam treatment and acid treatment in sequence to obtain a modified molecular sieve;

[0048] (2) Modifying the modified molecular sieve with a metal active component or without modifying with a metal active component, then mixing with a binder, and then optionally forming;

[0049] The method may also optionally include: (3) impregnating the solid product obtained in step (2) in a solution containing a metal active component precursor.

[0050] According to the method of the present invention, there is no particular limitation on the timing of introducing the metal active component, and it may be introduced in step (2) or in step (3). Preferably, the metal active component is introduced in step (3), and the advantage of adopting this embodiment is that the metal dispersion is uniform.

[0051] "Optionally forming" in step (2) of the present invention means that forming may be carried out or not carried out, and forming is preferably carried out.

[0052] According to the method of the present invention, preferably, in step (1), the density ratio of Bronsted acid to Lewis acid of the molecular sieve raw powder is 5-10, the external specific surface area is 20-100 m 2 / g, and the microporous specific surface area is 100-400 m 2 / g, and the total acid amount is 1.0-2.0 μmol / g NH3.

[0053] In the present invention, the test methods for the density ratio of Bronsted acid to Lewis acid, external specific surface area, microporous specific surface area and total acid amount of the molecular sieve have been described in the first aspect of the present invention and will not be elaborated here.

[0054] According to the method of the present invention, there is no specific limitation on the type of the molecular sieve, and the types defined in the art are all applicable to the present invention. Preferably, the molecular sieve is an ammonium-type molecular sieve and / or a hydrogen-type molecular sieve, and more preferably an ammonium-type molecular sieve.

[0055] According to the method of the present invention, there is no particular limitation on the specific type of the molecular sieve, and those skilled in the art can select according to specific needs. Preferably, the molecular sieve is ZSM-5 and / or mordenite, and more preferably ZSM-5 and mordenite.

[0056] In a preferred embodiment, based on the total amount of the molecular sieve, the content of ZSM-5 is 10-50% by weight, and the content of mordenite is 50-90% by weight.

[0057] In a particularly preferred embodiment, based on the total amount of the molecular sieve, the content of ZSM-5 is 20-40% by weight, and the content of mordenite is 60-80% by weight.

[0058] According to the method provided by the present invention, preferably, the steam treatment and acid treatment reduce the density ratio of Bronsted acid to Lewis acid of the modified molecular sieve to 1-4; compared with the molecular sieve raw powder in step (1), the external specific surface area of the obtained modified molecular sieve is increased by 10-40%, the microporous loss rate is less than 5%, and the loss rate of the total acid amount in the NH3-TPD test is 10-30%; the intensity of the non-framework six-coordinated aluminum characteristic peak at 0 ppm in the Al nuclear magnetic spectrum is close to 0.

[0059] According to the method of the present invention, the molecular sieve is first subjected to steam treatment. Preferably, the steam treatment can be carried out in a rotary furnace.

[0060] According to the method of the present invention, there is no specific limitation on the amount of steam used. Preferably, in step (1), during the steam treatment process, the amount of water used is 0.05-5 mL per gram of the molecular sieve, preferably 1-3 mL. The advantage of adopting this preferred embodiment is that continuous production can be achieved.

[0061] According to the method of the present invention, the range of conditions for steam treatment is relatively wide. Preferably, the temperature is 300 - 600 °C and the time is 1 - 10 h. Further preferably, the temperature is 400 - 500 °C and the time is 3 - 5 h. Under this preferred embodiment, the acid amount of the molecular sieve can be reduced after steam treatment, and the excessive cracking reaction of aromatics can be inhibited.

[0062] According to the method of the present invention, in order to improve the reaction activity of the molecular sieve, the molecular sieve after steam treatment is subjected to acid treatment. Preferably, in step (1), the acid used for the acid treatment is an organic acid.

[0063] In a preferred embodiment, the organic acid is selected from at least one of formic acid, acetic acid, propionic acid, butyric acid, caprylic acid, adipic acid, oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, benzoic acid, phenylacetic acid, phthalic acid, terephthalic acid, valeric acid, hexanoic acid, and capric acid.

[0064] In a preferred embodiment, the organic acid is selected from at least one of oxalic acid, citric acid, and acetic acid.

[0065] In a particularly preferred embodiment, the organic acid is selected from at least two of citric acid, oxalic acid, and acetic acid.

[0066] Adopting this particularly preferred embodiment, using at least two specific organic acids in combination is more beneficial to dredging the pore blockage caused by steam treatment during the acid treatment process, further improving the reaction activity of the molecular sieve, and further improving the selectivity of xylene in the alkyl transfer reaction of toluene and C9 + heavy aromatics.

[0067] According to the method of the present invention, preferably, the range of conditions for acid treatment is relatively wide. Preferably, in step (1), the conditions for the acid treatment include: the acid concentration is 0.05 - 1.0 mol / L, the liquid-solid mass ratio is 1 - 10:1, the temperature is 60 - 100 °C, and the time is 2 - 10 h.

[0068] In a preferred case, the acid concentration is 0.1 - 0.5 mol / L, the liquid-solid mass ratio is 3 - 6:1, the temperature is 85 - 95 °C, and the time is 4 - 6 h. The advantage of adopting this preferred embodiment is that the dredging effect on the molecular sieve pores is better.

[0069] According to the method of the present invention, preferably, before step (2), the modified molecular sieve obtained in step (1) is dried and / or pulverized. Further preferably, the modified molecular sieve obtained in step (1) is first dried and then pulverized.

[0070] According to the method of the present invention, the drying conditions have a wide range of selection. Preferably, the drying conditions include: a temperature of 100-150°C and a time of 10-24h.

[0071] According to the method of the present invention, preferably, the powdering makes the modified molecular sieve smaller than 200 meshes. The advantage of adopting this preferred embodiment is that the molecular sieve can be better mixed with the binder.

[0072] According to the method of the present invention, the binder in step (2) has been described in the first aspect of the present invention and will not be described again here.

[0073] According to the present invention, the metal active components in step (2) and step (3) may be the same or different, and may be independently selected from the types of metal active components described in the first aspect of the present invention, and the present invention will not be described in detail here.

[0074] According to the method of the present invention, preferably, in step (2), the modified molecular sieve is mixed with a binder and then molded.

[0075] According to the method of the present invention, during the molding process, an extrusion aid can be added to improve the molding rate, and the type of the extrusion aid is not specifically limited in the present invention. For example, the extrusion aid is selected from at least one of sesbania powder, starch and cellulose, preferably sesbania powder.

[0076] According to the method of the present invention, during the molding process, a sol agent may be added to improve the molding rate, and the type of the sol agent is not specifically limited in the present invention. For example, the sol agent is selected from at least one of hydrochloric acid, nitric acid, citric acid and oxalic acid, preferably nitric acid.

[0077] The present invention has no particular limitation on the amount of the extrusion aid and the sol agent, as long as the molding can be carried out smoothly. Preferably, based on the total amount of the material to be molded, the amount of the extrusion aid is 1-5% by weight; preferably, the amount of the sol agent is 1-5% by weight.

[0078] In the present invention, the molding may be extrusion molding. There is no particular limitation on the shape of the molded product, for example, it may be columnar, clover-shaped, butterfly-shaped, honeycomb-shaped, etc.

[0079] According to the method of the present invention, in step (2), preferably, the molded product is further subjected to a calcination treatment. The calcination conditions in the present invention can be selected over a wide range. Preferably, the calcination temperature is 450-600°C and the calcination time is 1-10 hours.

[0080] The preparation method provided by the present invention preferably further comprises pelletizing the calcined product, preferably, the particle size is 1-2 mm and the particle length is 1-20 mm.

[0081] According to the method of the present invention, in step (3), the selection range of the metal active component precursor is relatively wide and can be selected from water-soluble compounds of respective metal active components, preferably nitrates of respective metal active components, etc.

[0082] According to the method of the present invention, in step (3), the metal active component precursor is dissolved in a solvent (such as water) to prepare a solution containing the metal active component precursor.

[0083] According to the method of the present invention, there is no specific limitation on the impregnation method in the present invention, as long as the metal active component can be loaded on the solid product.

[0084] According to the method of the present invention, in step (3), it is preferably further included to perform a drying treatment on the impregnated product. The selection range of the drying conditions in the present invention is relatively wide. Preferably, the drying temperature is 90 - 120 °C and the time is 1 - 10 h.

[0085] According to the method of the present invention, after the drying in step (3) is completed, it is preferably further included to perform a calcination treatment on the dried product. The selection range of the calcination conditions in the present invention is relatively wide. Preferably, the calcination temperature is 450 - 600 °C and the time is 1 - 10 h.

[0086] According to the method of the present invention, preferably, the dosages of the modified molecular sieve, binder, metal active component, and metal active component precursor are such that in the catalyst prepared, based on the total amount of the modified molecular sieve and binder, the content of the modified molecular sieve is 50 - 80 wt%, and the content of the binder is 20 - 50 wt%; relative to 100 parts by weight of the modified molecular sieve and binder, the content of the metal active component is 0.01 - 3 parts by weight.

[0087] In a preferred embodiment, based on the total amount of the modified molecular sieve and binder, the content of the modified molecular sieve is 50 - 75 wt%, and the content of the binder is 25 - 50 wt%; relative to 100 parts by weight of the modified molecular sieve and binder, the content of the metal active component is 0.01 - 2 parts by weight.

[0088] The third aspect of the present invention provides an alkyl transfer method, which includes: under alkyl transfer conditions, contacting C9 + heavy aromatics and toluene with an alkyl transfer catalyst; the alkyl transfer catalyst is the alkyl transfer catalyst described in the first aspect or the alkyl transfer catalyst prepared by the preparation method described in the second aspect.

[0089] According to the alkyl transfer method provided by the present invention, preferably, the method further includes reducing and activating the alkyl transfer catalyst before the contact. The present invention has a relatively wide selection range for the conditions of the reduction and activation. Preferably, it is carried out in a hydrogen-containing atmosphere (hydrogen content not less than 90% by volume), the temperature is 300-450 °C, the pressure is 1-3 MPa, and the time is 2-12 h.

[0090] According to the present invention, preferably, the alkyl transfer conditions include: the reaction temperature is 300-500 °C, the mass space velocity of the raw material is 2-6 h -1 , the reaction pressure is 2-4 MPa, and the hydrogen-hydrocarbon molar ratio is 2-4.

[0091] In a specific embodiment, in order to further improve the catalytic performance of the alkyl transfer catalyst and improve the selectivity of xylene, the reaction temperature can be any value between 300-500 °C, such as 300 °C, 400 °C, 500 °C, and can also be selected from any value and any interval of any two values.

[0092] In a specific embodiment, the mass space velocity of the raw material is 2-6 h -1 , such as 2 h -1 , 3 h -1 , 4 h -1 , 5 h -1 , 6 h -1 , and can also be any value and any interval of any two values.

[0093] In a specific embodiment, the reaction pressure is preferably 2-4 MPa, for example, it can be 2 MPa, 3 MPa, 4 MPa, and can also be any value and any interval of any two values.

[0094] In a specific embodiment, the hydrogen-hydrocarbon molar ratio is 2-4, for example, it can be 2, 3, 4, and can also be any value and any interval of any two values.

[0095] According to the present invention, preferably, the mass ratio of toluene and C9 + heavy aromatics is 90:10-10:90.

[0096] According to the present invention, there is no particular limitation on the source of the C9 + heavy aromatics. Preferably, the C9 + heavy aromatics come from catalytic cracking reaction and / or catalytic reforming reaction.

[0097] In a preferred case, the C9 + heavy aromatics contain at least one monocyclic aromatic hydrocarbon mixture with 9 or more carbon atoms such as trimethylbenzene, methyl ethylbenzene, propylbenzene, indane, tetramethylbenzene, diethylbenzene, dimethylethylbenzene, etc.

[0098] According to the present invention, the reactor for carrying out the alkyl transfer method can be realized by using conventional devices in the art, such as riser, reaction tower, fixed bed, fluidized bed or moving bed.

[0099] The present invention will be described in detail below by way of examples. The raw materials used in the following examples are all commercially available products without special instructions, and the purity is analytical pure (AR).

[0100] In the present invention, the performance calculation formula of the alkyl transfer catalyst is as follows:

[0101]

[0102]

[0103]

[0104] Example 1

[0105] Hydrogen-type mordenite was continuously fed into a rotary furnace at a rate of 500 grams per hour, and at the same time, steam was introduced for hydrothermal treatment. The amount of steam used was 1000 mL / h, the hydrothermal treatment temperature was 500 °C, and the treatment time was 6 h to obtain steam-treated molecular sieve powder; the steam-treated molecular sieve powder was subjected to ion exchange treatment with 0.2 mol / L acetic acid, the mass ratio of the exchange liquid to the solid was 5 / 1, the temperature was 95 °C, and the time was 4 h. The obtained molecular sieve after exchange was dried at a temperature of 120 °C for 12 h and mechanically pulverized to less than 200 mesh to obtain a composite modified molecular sieve. The NH3-TPD curves of the molecular sieve before and after modification are as Figure 1 shown. Before the steam treatment, the ratio of the B acid density to the L acid density of mordenite was 10, the external specific surface area was 95 m 2 / g, the microporous specific surface area was 340 m 2 / g, and the total acid amount measured by NH3-TPD was 2.0 μmol / g NH3. After the steam treatment, the ratio of the B acid density to the L acid density of mordenite was 4, the external specific surface area increased by 38%, the microporous loss rate was 2.9%, the loss rate of the total acid amount measured by NH3-TPD was 28%, and the intensity of the non-framework hexa-coordinated aluminum characteristic peak at 0 ppm in the Al nuclear magnetic spectrum was close to 0. The physicochemical parameters of the molecular sieve before and after modification are shown in Table 1.

[0106] 67 grams of the composite modified molecular sieve was uniformly mixed with 33 g of γ-Al2O3·H2O, then 4 g of dilute nitric acid and 1 g of sesbania powder were added and kneaded evenly, extruded into pellets, and calcined at 550 °C for 5 h to make a carrier, which was cut into particles and placed in an impregnation container. A certain amount of ammonium molybdate was dissolved in water and impregnated on the surface of the carrier, dried at 120 °C for 4 hours, and calcined at 550 °C for 3 hours to obtain catalyst A. The catalyst composition is shown in Table 2.

[0107] In a fixed-bed reactor, 20 g of catalyst A was loaded, hydrogen was introduced, the pressure was 3 MPa, the temperature was raised to 400 °C, and after purging for 6 hours for reduction and activation, toluene and C9 were introduced. + Heavy aromatics were reacted, and the weight composition of the raw materials was toluene / C9 + Heavy aromatics = 50 / 50, the reaction temperature was 400 °C, the pressure was 2.5 MPa, the feed WHSV = 4 h -1 , and the hydrogen-hydrocarbon molar ratio was 3. The reaction performance is shown in Table 3.

[0108] Example 2

[0109] Ammonium-type ZSM-5 molecular sieve was continuously fed into a rotary furnace at a rate of 500 g per hour, and at the same time, steam was introduced for hydrothermal treatment. The amount of steam used was 500 mL / h, the hydrothermal treatment temperature was 400 °C, and the treatment time was 6 h to obtain steam-treated molecular sieve powder; the steam-treated molecular sieve powder was exchanged with 0.1 mol / L oxalic acid, the mass ratio of the exchange liquid to the solid was 6 / 1, the temperature was 85 °C, and the time was 6 h. After exchange, the obtained molecular sieve was dried at a temperature of 90 °C for 10 h and mechanically pulverized to less than 200 mesh to obtain a composite modified molecular sieve. Before steam treatment, the ratio of the B acid density to the L acid density of the molecular sieve was 5, the external specific surface area was 35 m 2 / g, and the microporous specific surface area was 190 m 2 / g, and the total acid amount measured by NH3-TPD was 1.1 μmol / g NH3. After steam treatment, the ratio of the B acid density to the L acid density of ZSM-5 molecular sieve was 1, the external specific surface area increased by 15%, the microporous loss rate was 2.1%, the loss rate of the total acid amount measured by NH3-TPD was 10%, and the intensity of the non-framework hexa-coordinated aluminum characteristic peak at 0 ppm in the Al nuclear magnetic spectrum was close to 0. The physical and chemical parameters of the molecular sieve before and after modification are shown in Table 1.

[0110] 80 g of the composite modified molecular sieve was uniformly mixed with 20 g of silica sol, then 1 g of dilute nitric acid and 2 g of sesbania powder were added and kneaded evenly, extruded into pellets, and calcined at 450 °C for 10 h to make a carrier. After cutting into pellets, it was placed in an impregnation container. A certain amount of nickel nitrate was dissolved in water and impregnated on the surface of the carrier, dried at 100 °C for 10 hours, and calcined at 500 °C for 4 hours to obtain catalyst B. The catalyst composition is shown in Table 2.

[0111] In a fixed-bed reactor, 20 g of catalyst B was loaded, hydrogen was introduced, the pressure was 2 MPa, the temperature was raised to 450 °C, and after purging for 12 hours for reduction and activation, toluene and C9 were introduced. + Heavy aromatics were reacted, and the weight composition of the raw materials was toluene / C9 + Heavy aromatics = 10 / 90, the reaction temperature was 350 °C, the pressure was 2 MPa, the feed WHSV = 2 h -1 , and the hydrogen-hydrocarbon molar ratio was 2. The reaction performance is shown in Table 3.

[0112] Example 3

[0113] The ammonium-type molecular sieve was continuously fed into a rotary furnace at a rate of 500 g per hour, and at the same time, steam was introduced for hydrothermal treatment. The steam usage was 1500 mL / h, the hydrothermal treatment temperature was 480 °C, and the treatment time was 4 h to obtain steam-treated molecular sieve powder; the steam-treated molecular sieve powder was subjected to an ion exchange treatment with 0.5 mol / L citric acid, the mass ratio of the exchange liquid to the solid was 3 / 1, the temperature was 90 °C, and the time was 5 h. The molecular sieve obtained after the exchange was dried at a temperature of 120 °C for 24 h and mechanically pulverized to less than 200 mesh to obtain a composite modified molecular sieve. The molecular sieve before steam treatment was composed of 25 wt% ZSM-5 and 75 wt% mordenite, the ratio of the B acid density to the L acid density was 7.5, the external specific surface area was 75 m 2 / g, and the microporous specific surface area was 305 m 2 / g. The total acid amount measured by NH3-TPD was 1.5 μmol / g NH3. After steam treatment, the ratio of the B acid density to the L acid density of the molecular sieve was 2, the external specific surface area increased by 26%, the microporous loss rate was 2.6%, and the loss rate of the total acid amount measured by NH3-TPD was 12%. The intensity of the non-framework six-coordinated aluminum characteristic peak at 0 ppm in the Al nuclear magnetic spectrum was close to 0. The physical and chemical parameters before and after the modification of the molecular sieve are shown in Table 1.

[0114] 50 g of the composite modified molecular sieve and 50 g of δ-Al2O3·H2O were uniformly mixed, then 5 g of dilute nitric acid and 3 g of sesbania powder were added and kneaded evenly, extruded into pellets, and calcined at 550 °C for 10 h to make a carrier. After cutting into pellets, they were placed in an impregnation container. A certain amount of ammonium perrhenate was dissolved in water and impregnated on the surface of the carrier, dried at 100 °C for 10 hours, and calcined at 500 °C for 5 hours to obtain catalyst C. The catalyst composition is shown in Table 2.

[0115] In a fixed-bed reactor, 20 g of catalyst C was loaded, hydrogen was introduced, the pressure was 1 MPa, the temperature was raised to 400 °C, and after purging and reducing activation for 5 hours, toluene and C9 + heavy aromatics were fed for reaction. The weight composition of the raw materials was toluene / C9 + heavy aromatics = 90 / 10, the reaction temperature was 400 °C, the pressure was 4 MPa, the feed WHSV = 4 h -1 , and the hydrogen-hydrocarbon molar ratio was 4. The reaction performance is shown in Table 3.

[0116] Example 4

[0117] The ammonium-type molecular sieve was continuously fed into a rotary furnace at a rate of 500 g per hour, and at the same time, steam was introduced for hydrothermal treatment. The amount of steam used was 750 mL / h, the hydrothermal treatment temperature was 500 °C, and the treatment time was 3 h to obtain steam-treated molecular sieve powder. The steam-treated molecular sieve powder was subjected to an ion exchange treatment with 0.2 mol / L acetic acid. The mass ratio of the exchange liquid to the solid was 4 / 1, the temperature was 90 °C, and the time was 3 h. The obtained molecular sieve after exchange was dried at a temperature of 100 °C for 16 h and mechanically ground to less than 200 mesh to obtain a composite modified molecular sieve. The molecular sieve before steam treatment was composed of 20 wt% ZSM-5 and 80 wt% mordenite, the ratio of the density of Brønsted acid to the density of Lewis acid was 6.5, the external specific surface area was 85 m 2 / g, and the microporous specific surface area was 285 m 2 / g. The total acid amount measured by NH3-TPD was 1.7 μmol / g NH3. After steam treatment, the ratio of the density of Brønsted acid to the density of Lewis acid of the molecular sieve was 3.8, the external specific surface area increased by 25%, the microporous loss rate was 2.1%, the loss rate of the total acid amount measured by NH3-TPD was 25%, and the intensity of the non-framework hexa-coordinated aluminum characteristic peak at 0 ppm in the Al nuclear magnetic spectrum was close to 0. The physical and chemical parameters before and after molecular sieve modification are shown in Table 1.

[0118] 75 g of the composite modified molecular sieve was uniformly mixed with 25 g of ρ-Al2O3·H2O, then 3 g of dilute nitric acid and 5 g of sesbania powder were added and kneaded evenly, extruded into pellets, and calcined at 600 °C for 3 h to make a support. After cutting into pellets, it was placed in an impregnation container. A certain amount of chloroplatinic acid was dissolved in water and impregnated on the surface of the support, dried at 90 °C for 5 hours, and calcined at 450 °C for 5 hours to obtain catalyst D. The catalyst composition is shown in Table 2.

[0119] In a fixed-bed reactor, 20 g of catalyst D was loaded, hydrogen was introduced, the pressure was 1 MPa, the temperature was raised to 300 °C, and after purging for 2 hours for reduction activation, toluene and C9 + heavy aromatics were fed for reaction. The weight composition of the raw materials was toluene / C9 + heavy aromatics = 30 / 70, the reaction temperature was 390 °C, the pressure was 2 MPa, the feed WHSV = 5 h -1 , and the hydrogen-hydrocarbon molar ratio was 2. The reaction performance is shown in Table 3.

[0120] Example 5

[0121] The ammonium-type molecular sieve is continuously fed into a rotary furnace at a rate of 500 grams per hour, and at the same time, steam is introduced for hydrothermal treatment. The steam consumption is 550 mL / h, the hydrothermal treatment temperature is 500 °C, and the treatment time is 4 h to obtain steam-treated molecular sieve powder. The steam-treated molecular sieve powder is subjected to an ion exchange treatment with 0.15 mol / L oxalic acid. The mass ratio of the exchange liquid to the solid is 6 / 1, the temperature is 95 °C, and the time is 6 h. The obtained molecular sieve after exchange is dried at a temperature of 120 °C for 12 h and mechanically ground to less than 200 mesh to obtain a composite modified molecular sieve. The molecular sieve before steam treatment is composed of 40 wt% ZSM-5 and 60 wt% mordenite, the ratio of the density of Brønsted acid to the density of Lewis acid is 5.5, the external specific surface area is 62 m 2 / g, and the microporous specific surface area is 350 m 2 / g. The total acid amount measured by NH3-TPD is 1.3 μmol / g NH3. After steam treatment, the ratio of the density of Brønsted acid to the density of Lewis acid of mordenite is 2.9, the external specific surface area increases by 21%, the microporous loss rate is 4.6%, and the loss rate of the total acid amount measured by NH3-TPD is 21%. The intensity of the characteristic peak of non-framework six-coordinated aluminum at 0 ppm in the 27Al NMR spectrum is close to 0. The physical and chemical parameters before and after molecular sieve modification are shown in Table 1.

[0122] 60 grams of the composite modified molecular sieve and 40 g of κ-Al2O3·H2O are uniformly mixed, then 5 g of dilute nitric acid and 4 g of sesbania powder are added and kneaded evenly, extruded into pellets, and calcined at 550 °C for 2 h to make a support. After cutting into pellets, they are placed in an impregnation container. A certain amount of chloroplatinic acid is dissolved in water and impregnated on the surface of the support, dried at 120 °C for 5 hours, and calcined at 500 °C for 5 hours to obtain catalyst E. The catalyst composition is shown in Table 2.

[0123] In a fixed-bed reactor, 20 grams of catalyst E is loaded, hydrogen is introduced, the pressure is 3 MPa, the temperature is raised to 400 °C, and after purging and reducing activation for 6 hours, toluene and C9 + heavy aromatics are fed for reaction. The weight composition of the raw materials is toluene / C9 + heavy aromatics = 40 / 60, the reaction temperature is 400 °C, the pressure is 2 MPa, the feed WHSV = 6 h -1 , and the hydrogen-hydrocarbon molar ratio is 4. The reaction performance is shown in Table 3.

[0124] Example 6

[0125] The ammonium-type molecular sieve was continuously fed into a rotary furnace at a rate of 500 g per hour, and at the same time, steam was introduced for hydrothermal treatment. The amount of steam used was 1000 mL / h, the hydrothermal treatment temperature was 450 °C, and the treatment time was 5 h to obtain steam-treated molecular sieve powder. The steam-treated molecular sieve powder was subjected to an ion exchange treatment with a mixed solution of 0.15 mol / L oxalic acid and 0.3 mol / L acetic acid. The mass ratio of the exchange liquid to the solid was 3 / 1, the temperature was 95 °C, and the time was 5 h. The molecular sieve obtained after the exchange was dried at a temperature of 100 °C for 16 h and mechanically pulverized to less than 200 mesh to obtain a composite modified molecular sieve. Before the steam treatment, the molecular sieve was composed of 30 wt% ZSM-5 and 70 wt% mordenite, the ratio of the density of Brønsted acid to the density of Lewis acid was 6.1, the external specific surface area was 75 m 2 / g, and the microporous specific surface area was 270 m 2 / g. The total acid amount measured by NH3-TPD was 1.6 μmol / g NH3. After the steam treatment, the ratio of the density of Brønsted acid to the density of Lewis acid of the molecular sieve was 3.2, the external specific surface area increased by 32%, the microporous loss rate was 1.9%, and the loss rate of the total acid amount measured by NH3-TPD was 11%. The intensity of the characteristic peak of non-framework six-coordinated aluminum at 0 ppm in the 27Al NMR spectrum was close to 0. The physical and chemical parameters before and after the modification of the molecular sieve are shown in Table 1.

[0126] 70 g of the composite modified molecular sieve was uniformly mixed with 30 g of silica sol, then 2 g of dilute nitric acid and 2 g of sesbania powder were added and kneaded evenly, extruded into pellets, and calcined at 550 °C for 5 h to prepare a carrier. After cutting into pellets, it was placed in an impregnation container. A certain amount of ammonium molybdate was dissolved in water and impregnated on the surface of the carrier, dried at 90 °C for 10 hours, and calcined at 450 °C for 10 hours to obtain catalyst F. The composition of the catalyst is shown in Table 2.

[0127] In a fixed-bed reactor, 20 g of catalyst F was loaded, hydrogen was introduced, the pressure was 3 MPa, the temperature was raised to 450 °C, and after purging for 10 hours for reduction activation, toluene and C9 + heavy aromatics were fed for reaction. The weight composition of the raw materials was toluene / C9 + heavy aromatics = 50 / 50, the reaction temperature was 385 °C, the pressure was 3 MPa, the feed WHSV = 3 h -1 , and the hydrogen-hydrocarbon molar ratio was 3. The reaction performance is shown in Table 3.

[0128] Example 7

[0129] The ammonium-type molecular sieve was continuously fed into a rotary furnace at a rate of 500 g per hour, and at the same time, steam was introduced for hydrothermal treatment. The amount of steam used was 900 mL / h, the hydrothermal treatment temperature was 550 °C, and the treatment time was 3 h to obtain steam-treated molecular sieve powder. The steam-treated molecular sieve powder was subjected to ion exchange treatment with a mixed solution of 0.2 mol / L oxalic acid and 0.5 mol / L citric acid. The mass ratio of the exchange liquid to the solid was 3 / 1, the temperature was 95 °C, and the time was 5 h. After the exchange, the obtained molecular sieve was dried at a temperature of 100 °C for 16 h and mechanically pulverized to less than 200 mesh to obtain a composite modified molecular sieve. The molecular sieve before steam treatment was composed of 30 wt% ZSM-5 and 70 wt% mordenite, the ratio of the density of Brønsted acid to the density of Lewis acid was 6.1, the external specific surface area was 75 m 2 / g, and the microporous specific surface area was 270 m 2 / g. The total acid amount measured by NH3-TPD was 1.6 μmol / g NH3. After steam treatment, the ratio of the density of Brønsted acid to the density of Lewis acid of the molecular sieve was 4, the external specific surface area increased by 35%, the microporous loss rate was 2.2%, and the loss rate of the total acid amount measured by NH3-TPD was 18%. The intensity of the characteristic peak of non-framework six-coordinated aluminum at 0 ppm in the 27Al NMR spectrum was close to 0. The physical and chemical parameters of the molecular sieve before and after modification are shown in Table 1.

[0130] 70 g of the composite modified molecular sieve was uniformly mixed with 30 g of silica sol, then 2 g of dilute nitric acid and 2 g of sesbania powder were added and kneaded evenly, extruded into pellets, and calcined at 550 °C for 5 h to prepare a carrier. After cutting into pellets, it was placed in an impregnation container. A certain amount of ammonium molybdate was dissolved in water and impregnated on the surface of the carrier, dried at 90 °C for 10 hours, and calcined at 450 °C for 10 hours to obtain catalyst G. The composition of the catalyst is shown in Table 2.

[0131] In a fixed-bed reactor, 20 g of catalyst G was loaded, hydrogen was introduced, the pressure was 3 MPa, the temperature was raised to 450 °C, and after purging and reducing activation for 4 hours, toluene and C9 + heavy aromatics were fed for reaction. The weight composition of the raw materials was toluene / C9 + heavy aromatics = 50 / 50, the reaction temperature was 385 °C, the pressure was 3 MPa, the feed WHSV = 3 h -1 , and the hydrogen-hydrocarbon molar ratio was 3. The reaction performance is shown in Table 3.

[0132] Comparative Example 1

[0133] According to the method of Example 1, the difference was that the composite modified molecular sieve was replaced with an equal mass of the mordenite raw powder used in Example 1 to prepare catalyst DA. Catalyst DA was evaluated according to the method of Example 1. The reaction performance is shown in Table 3.

[0134] Table 1 Physical and chemical parameters of the molecular sieve before and after modification

[0135]

[0136]

[0137] Table 2 Composition of the transalkylation catalyst

[0138]

[0139]

[0140] Table 3 Performance of the transalkylation catalyst

[0141] Total conversion rate (wt / %) Xylene selectivity (wt / %) Aromatic ring loss rate (mol / %) Example 1 42 70 1.6 Example 2 43 75 1.9 Example 3 44 66 0.3 Example 4 45 72 1.0 Example 5 46 71 1.1 Example 6 46 72 0.9 Example 7 47 73 0.7 Comparative Example 1 40 65 2.1

[0142] It can be seen from the results in Table 3 that the catalyst with the molecular sieve treated by the composite treatment of the present invention has significantly better conversion rate and xylene selectivity than the catalyst with the unmodified molecular sieve, and the aromatic ring loss rate is lower.

[0143] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. An alkyl transfer catalyst, which catalyst comprises a modified molecular sieve, a binder and a metal active component, wherein, The density ratio of Bronsted acid to Lewis acid of the modified molecular sieve is 0.5 - 5, the external specific surface area is 40 - 200 m 2 / g, the microporous specific surface area is 100 - 400 m 2 / g, the total acid amount is 0.1 - 1.5 μmol / g NH3, and the intensity of the non-framework six-coordinated aluminum characteristic peak at 0 ppm in the Al nuclear magnetic spectrum is close to 0; Based on the total amount of the modified molecular sieve and the binder, the content of the modified molecular sieve is 50 - 80% by weight, and the content of the binder is 20 - 50% by weight; based on 100 parts by weight of the modified molecular sieve and the binder, the content of the metal active component is 0.01 - 3 parts by weight; The metal active component is selected from at least one of Ni, Mo, Re, and Pt; Among them, the modified molecular sieve is ZSM-5 and / or mordenite that have been treated with steam and acid.

2. The catalyst according to claim 1, wherein The density ratio of Bronsted acid to Lewis acid of the modified molecular sieve is 1 - 4; The external specific surface area of the modified molecular sieve is 60-150 m 2 / g, and the microporous specific surface area is 150-350 m 2 / g; The total acid amount of the modified molecular sieve is 0.5 - 1.5 μmol / g NH₃.

3. The catalyst according to claim 1, wherein, Based on the total amount of the modified molecular sieve, the content of ZSM-5 is 10 - 50% by weight, and the content of mordenite is 50 - 90% by weight.

4. The catalyst according to claim 3, wherein, Based on the total amount of the modified molecular sieve, the content of ZSM-5 is 20 - 40% by weight, and the content of mordenite is 60 - 80% by weight.

5. The catalyst according to claim 1, wherein, The binder is at least one of alumina, silica sol, clay, and diatomite.

6. The catalyst according to claim 5, wherein, The binder is alumina and / or silica sol.

7. The preparation method of the transalkylation catalyst according to any one of claims 1 - 6, the method comprising the following steps: (1) Subjecting the molecular sieve raw powder to steam treatment and acid treatment in sequence to obtain a modified molecular sieve; (2) Modifying the modified molecular sieve with a metal active component or not, then mixing it with a binder, and then optionally forming it; The method further includes: (3) Immersing the solid product obtained in step (2) in a solution containing a metal active component precursor; Among them, the molecular sieve raw powder is ZSM-5 and / or mordenite.

8. The preparation method according to claim 7, wherein In the step (1), the density ratio of Bronsted acid to Lewis acid of the molecular sieve raw powder is 5-10, the external specific surface area is 20-100 m 2 / g, the microporous specific surface area is 100-400 m 2 / g, and the total acid amount is 1-2 μmol / g NH3.

9. The preparation method according to claim 7, wherein, The molecular sieve raw powder is ammonium-type molecular sieve and / or hydrogen-type molecular sieve.

10. The preparation method according to claim 7, wherein, Based on the total amount of the molecular sieve, the content of ZSM-5 is 10 - 50% by weight, and the content of mordenite is 50 - 90% by weight.

11. The preparation method according to claim 10, wherein, Based on the total amount of the molecular sieve, the content of ZSM-5 is 20 - 40% by weight, and the content of mordenite is 60 - 80% by weight.

12. According to the preparation method described in claim 7, wherein, In step (1), during the steam treatment process, the water consumption per gram of the molecular sieve is 0.05 - 5 mL.

13. The preparation method according to claim 12, wherein In step (1), during the steam treatment process, the water consumption per gram of the molecular sieve is 1 - 3 mL.

14. The preparation method according to claim 7, wherein, The conditions of the steam treatment include: temperature is 300 - 600 °C, time is 1 - 10 h.

15. According to the preparation method described in claim 14, wherein, Temperature is 400 - 500 °C, time is 3 - 5 h.

16. The preparation method according to claim 7, wherein, In step (1), the acid used for the acid treatment is an organic acid.

17. The preparation method according to claim 16, wherein, The organic acid is selected from at least one of formic acid, acetic acid, propionic acid, butyric acid, octanoic acid, adipic acid, oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, valeric acid, hexanoic acid, and decanoic acid.

18. The preparation method according to claim 17, wherein, The organic acid is selected from at least one of oxalic acid, citric acid, and acetic acid.

19. The preparation method according to claim 18, wherein The organic acid is selected from at least two of citric acid, oxalic acid, and acetic acid.

20. The preparation method according to claim 7, wherein The conditions of the acid treatment in step (1) include: Acid concentration is 0.05 - 1.0 mol / L, liquid-solid mass ratio is 1 - 10:1, temperature is 60 - 100 °C, time is 2 - 10 h.

21. The preparation method according to claim 20, wherein, The acid concentration is 0.1 - 0.5 mol / L, the liquid-solid mass ratio is 3 - 6:1, the temperature is 85 - 95 °C, and the time is 4 - 6 h.

22. The preparation method according to claim 7, wherein This method includes drying and / or pulverizing the modified molecular sieve obtained in step (1) before step (2).

23. The preparation method according to claim 22, wherein, The conditions for the drying include: the temperature is 100 - 150 °C, and the time is 10 - 24 h.

24. The preparation method according to claim 22, wherein, The pulverizing makes the particle size of the modified molecular sieve less than 200 mesh.

25. The preparation method according to claim 7, wherein, The binder in step (2) is at least one of alumina, silica sol, clay, and diatomaceous earth.

26. The preparation method according to claim 25, wherein, The binder in step (2) is alumina and / or silica sol.

27. The preparation method according to claim 7, wherein, The metal active components in step (2) and step (3) are each independently selected from at least one of the metals in Group VIB, Group VIIB, and Group VIII.

28. The preparation method according to claim 27, wherein, The metal active components in step (2) and step (3) are selected from at least one of Ni, Mi, Re, and Pt.

29. The preparation method according to claim 7, wherein, The dosages of the modified molecular sieve, the binder, the metal active component, and the metal active component precursor are such that in the catalyst prepared, based on the total amount of the modified molecular sieve and the binder, the content of the modified molecular sieve is 50 - 80 wt%, and the content of the binder is 20 - 50 wt%; relative to 100 parts by weight of the modified molecular sieve and the binder, the content of the metal active component is 0.01 - 3 parts by weight.

30. An alkyl transfer method, the method comprising: Under alkyl transfer conditions, C9 + heavy aromatics and toluene are contacted with an alkyl transfer catalyst; the alkyl transfer catalyst is the alkyl transfer catalyst described in any one of claims 1-6 or the alkyl transfer catalyst prepared by the preparation method described in any one of claims 7-29.

31. The alkyl transfer method according to claim 30, wherein, The transalkylation conditions include: The reaction temperature is 300 - 500 °C, and the mass hourly space velocity of the raw material is 2 - 6 h -1 , the reaction pressure is 2 - 4 MPa, and the hydrogen-hydrocarbon molar ratio is 2 - 4.

32. The alkyl transfer method according to claim 30, wherein Toluene and C9 + The mass ratio of the heavy aromatics is 90:10 - 10:

90.

33. The alkyl transfer method according to claim 32, wherein, The C9 + The heavy aromatics are from catalytic cracking reaction and / or catalytic reforming reaction.

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