A toluene disproportionation catalyst, its preparation method and use

Abstract

The application discloses a toluene disproportionation catalyst and a preparation method and application thereof. The toluene disproportionation catalyst comprises composite modified alumina and modified molecular sieve. The composite modified alumina comprises alkali metal and / or alkaline earth metal, transition metal A and alumina. The modified molecular sieve comprises molecular sieve and modified metal. The toluene disproportionation catalyst is used for toluene disproportionation reaction and has the advantages of high benzene selectivity.

Description

Technical Field

[0001] This invention relates to the field of aromatic hydrocarbon catalytic conversion, and more specifically to a toluene disproportionation catalyst, its preparation method, and its application. Background Technology

[0002] With the continuous increase in the operating rates of styrene, phenol, and caprolactam plants, as well as the construction of new production capacity, the market demand for benzene is growing daily, and its market price is rising steadily. Furthermore, increasingly stringent environmental regulations in various regions are making benzene transportation more difficult and costly, leading to increased localized benzene shortages. These market conditions have made efficient benzene production technologies increasingly popular among enterprises.

[0003] Toluene disproportionation technology is currently the most mature and widely used technology for producing xylene and benzene. Its principle is based on the methyl transfer reaction between aromatic hydrocarbons, transferring a methyl group from one toluene molecule to another, thereby producing benzene and xylene. Theoretically, 2 moles of toluene molecules can produce 1 mole of benzene and 1 mole of xylene, with a theoretical selectivity of only 42.4 wt.% for benzene, and xylene being the predominant product. The core research focus of traditional toluene disproportionation catalysts is on suppressing the demethylation reaction and maximizing xylene selectivity, aiming to maximize xylene production and thus meet the xylene production requirements of aromatic hydrocarbon complexes.

[0004] The product structure of traditional toluene disproportionation technology, which mainly produces xylene, is not adapted to market demand. New catalysts need to be developed to improve the benzene selectivity of toluene disproportionation technology and enhance the economic efficiency of the plant. Summary of the Invention

[0005] The technical problem this invention aims to solve is the low benzene selectivity in existing toluene disproportionation technologies. This invention provides a toluene disproportionation catalyst, its preparation method, and its application. The toluene disproportionation catalyst provided by this invention exhibits advantages such as high benzene selectivity in the toluene disproportionation reaction.

[0006] The first aspect of the present invention provides a toluene disproportionation catalyst, the catalyst comprising composite modified alumina and modified molecular sieve;

[0007] The composite modified alumina comprises alkali metals and / or alkaline earth metals, transition metal A, and alumina.

[0008] The modified molecular sieve comprises a molecular sieve and a modified metal.

[0009] Furthermore, the mass fraction of the composite modified alumina in the toluene disproportionation catalyst is 30-60%, and the mass fraction of the modified molecular sieve is 40-70%.

[0010] Furthermore, the transition metal A in the composite modified alumina is selected from at least one of Co, Cr, and Mn; the mass content of transition metal A in the composite modified alumina is 1-30%, preferably 5-15%. When two or more transition metals A are present, a significant synergistic effect is observed, preferably Co and Cr.

[0011] Furthermore, the alkali metal in the composite modified alumina is preferably K and / or Cs, and the alkaline earth metal is preferably Mg and / or Ca; the alkali metal and / or alkaline earth metal accounts for 0.5% to 3% of the mass content of the composite modified alumina. The simultaneous presence of alkali metal and alkaline earth metal demonstrates a significant synergistic effect.

[0012] Furthermore, the molecular sieve in the modified molecular sieve is a zeolite molecular sieve with a 10-12 member ring channel structure, preferably at least one of ZSM-5, mordenite, and β-zeolite.

[0013] Furthermore, the modified metal in the modified molecular sieve is at least one of Pt, Re, and Mo. The modified metal accounts for 0.01-5% of the mass content of the modified molecular sieve, preferably 0.01-1%. When two or more modified metals are present, a significant synergistic effect is observed, preferably Mo and Re.

[0014] A second aspect of this invention provides a method for preparing the above-mentioned toluene disproportionation catalyst, comprising the following steps:

[0015] (a) Take alumina, modify it with alkali metals and / or alkaline earth metals, and then dry and calcine it to obtain modified alumina;

[0016] (b) Take the above modified alumina, modify it with transition metal A, and then dry and calcine it to obtain composite modified alumina;

[0017] (c) Take a molecular sieve, modify it with a modified metal, and then dry and calcinate it to obtain a modified molecular sieve;

[0018] (d) Take the composite modified alumina from step (b) and the modified molecular sieve from step (c), add an extrusion aid and a gelling agent, mix and shape them, and then dry and calcine to obtain the catalyst.

[0019] Further, the alkali metal in step (a) is preferably K or / and Cs, the alkaline earth metal is preferably Mg or / and Ca, and the alkali metal and / or alkaline earth metal accounts for 0.5-3% of the mass content of the modified alumina.

[0020] Further, the transition metal A mentioned in step (b) is at least one of Co, Cr, and Mn, and the modified transition metal accounts for 1 to 30% of the mass content of the composite modified alumina, preferably 5 to 15%.

[0021] Further, in step (c), the molecular sieve is a zeolite molecular sieve with a 10-12 member ring channel structure, preferably at least one of ZSM-5, mordenite, and β-zeolite.

[0022] Further, the modified metal B in step (c) is at least one of Pt, Re, and Mo, and the modified metal accounts for 0.01-5% of the mass content of the modified molecular sieve, preferably 0.01-1%.

[0023] Further, the drying conditions described in steps (a), (b), (c), and (d) are each independently selected from: a drying temperature of 90–150°C and a drying time of 1–10 hours; the roasting conditions described in steps (a) and (b) are each independently selected from: a roasting temperature of 300–400°C and a roasting time of 1–10 hours; and the roasting conditions described in steps (c) and (d) are each independently selected from: a roasting temperature of 550–650°C and a roasting time of 1–10 hours.

[0024] Furthermore, the modification methods described in steps (a), (b), and (c) are each independently selected from any one of impregnation, ion exchange, and solid-phase kneading, with impregnation being preferred, wherein the impregnation method is an equal-volume impregnation.

[0025] Furthermore, in the molding process of step (d), the mass ratio of composite modified alumina to modified molecular sieve is 30:70 to 70:30.

[0026] Furthermore, in the molding process of step (d), the extrusion aid is at least one of guar gum powder, cyclodextrin, and methylcellulose, and the gelling agent is at least one of nitric acid, sulfuric acid, and hydrochloric acid.

[0027] Furthermore, in step (d), the extrusion aid and gelling agent can be added in appropriate amounts according to the amount of composite modified alumina.

[0028] The third aspect of the present invention provides the application of the toluene disproportionation catalyst described in the first aspect in the toluene disproportionation reaction.

[0029] Furthermore, the reaction conditions are as follows: reaction temperature of 350–650 °C, and toluene weight hourly space velocity of 1–10 h⁻¹. -1 The hydrogen / toluene molar ratio is 1–10, and the reaction pressure is 1–10 MPa; preferably, the reaction temperature is 400–550 °C, and the toluene weight hourly space velocity is 2–5 h⁻¹. -1 The molar ratio of hydrogen to toluene is 1–3, and the reaction pressure is 2–5 MPa.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) The toluene disproportionation catalyst provided by the present invention has the characteristics of high benzene selectivity by combining composite modified alumina and modified molecular sieve.

[0032] (2) The method for preparing the toluene disproportionation catalyst provided by the present invention involves composite modified alumina and metal modified molecular sieve, which are then mixed, shaped, and calcined to obtain a treated toluene disproportionation catalyst for use in the toluene disproportionation reaction. This method can effectively overcome the limitation of the theoretical selectivity of benzene in the pure toluene disproportionation reaction (≤42.4wt.%), greatly increase the production of benzene, and meet the current demand of enterprises for benzene. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0034] The raw materials used in the specific embodiments of the present invention are commercially available and have an analytical grade (AR) purity.

[0035] Example 1

[0036] Dissolve 3.61g of potassium carbonate in 120g of deionized water, add 100g of alumina, soak for 5 hours, dry in air at 100℃ for 10 hours, and calcine at 300℃ in air for 10 hours to obtain K-modified alumina, wherein the mass content of modifier K is 2%.

[0037] 19.82g of cobalt nitrate was dissolved in 120g of deionized water, and 100g of the above-mentioned K-modified alumina was added. After soaking for 5 hours, it was dried in air at 120℃ for 10 hours. After drying, it was calcined in air at 350℃ for 5 hours to obtain composite modified alumina, wherein the mass content of the modifier Co was 6%.

[0038] Dissolve 0.216g of ammonium perrhenate in 150g of deionized water, add 100g of ZSM-5 molecular sieve, soak for 5h, dry in air at 120℃ for 10h, and calcine at 550℃ in air atmosphere for 3h to obtain Re modified molecular sieve, wherein the mass content of the modifier Re is 0.15%.

[0039] Take 50g of the above-mentioned composite modified alumina and 50g of Re modified molecular sieve, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 100℃ for 10 hours and calcine in air at 600℃ for 5 hours to obtain a catalyst for toluene disproportionation reaction.

[0040] The mass fraction of the composite modified alumina and the mass fraction of the modified molecular sieve in the toluene disproportionation catalyst are 50%.

[0041] The above catalyst was used in the toluene disproportionation reaction under the following conditions: temperature 450℃, toluene weight hourly space velocity (WHSV) 5 h⁻¹. -1 The hydrogen / toluene molar ratio was 3, the reaction pressure was 5 MPa, and the reaction performance is shown in Table 1.

[0042] Example 2

[0043] 18.12g of magnesium acetate was dissolved in 120g of deionized water, and 100g of alumina was added. After soaking for 5 hours, the alumina was dried in air at 150℃ for 1 hour. After drying, the alumina was calcined in air at 400℃ for 5 hours to obtain Mg-modified alumina, wherein the mass content of the modifier Mg was 3%.

[0044] 37.12g of chromium nitrate was dissolved in 120g of deionized water, and 100g of the above-mentioned Mg-modified alumina was added. After soaking for 5 hours, it was dried in air at 100℃ for 5 hours. After drying, it was calcined in air at 400℃ for 10 hours to obtain composite modified alumina, wherein the mass content of the modifier Cr was 15%.

[0045] Dissolve 1.86g of ammonium heptamolybdate in 150g of deionized water, add 100g of mordenite molecular sieve, soak for 5h, dry in air at 100℃ for 5h, and calcine at 550℃ in air atmosphere for 5h to obtain Mo modified molecular sieve, wherein the mass content of the modifier Mo is 1%.

[0046] Take 70g of the above-mentioned composite modified alumina and 30g of Mo modified molecular sieve, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 150℃ for 11 hours and calcine in air at 600℃ for 10 hours to obtain a catalyst for toluene disproportionation reaction.

[0047] The mass fraction of the composite modified alumina in the toluene disproportionation catalyst is 70%, and the mass fraction of the modified molecular sieve is 30%.

[0048] The above catalyst was used in the toluene disproportionation reaction under the following conditions: temperature 400℃, toluene weight hourly space velocity (WHSV) 2 h⁻¹. -1 The molar ratio of hydrogen to toluene was 3, the reaction pressure was 3 MPa, and the reaction performance is shown in Table 1.

[0049] Example 3

[0050] Dissolve 0.737g of cesium nitrate in 120g of deionized water, add 100g of alumina, soak for 5 hours, dry in air at 100℃ for 10 hours, and calcine at 350℃ in air for 6 hours to obtain Cs-modified alumina, wherein the mass content of the modifier Cs is 0.5%.

[0051] Take 20.79g of manganese nitrate and dissolve it in 120g of deionized water. Add 100g of the above-mentioned Cs-modified alumina and soak it for 5 hours. Then dry it in air at 150℃ for 1 hour. After drying, calcine it in air at 300℃ for 10 hours to obtain composite modified alumina, wherein the mass content of the modifier Mn is 6%.

[0052] Dissolve 0.021g of chloroplatinic acid in 150g of deionized water, add 100g of β molecular sieve, soak for 5h, dry in air at 120℃ for 10h, and calcine at 600℃ in air atmosphere for 1h to obtain Pt modified molecular sieve, wherein the mass content of the modifier Pt is 0.01%.

[0053] Take 30g of the above-mentioned composite modified alumina and 70g of Pt modified molecular sieve, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 120℃ for 6 hours and calcine in air at 600℃ for 10 hours to obtain a catalyst for toluene disproportionation reaction.

[0054] The mass fraction of the composite modified alumina in the toluene disproportionation catalyst is 30%, and the mass fraction of the modified molecular sieve is 70%.

[0055] The above catalyst was used in the toluene disproportionation reaction under the following conditions: temperature 500℃, toluene weight hourly space velocity (WHSV) 5 h⁻¹. -1 The hydrogen / toluene molar ratio was 1, the reaction pressure was 2 MPa, and the reaction performance is shown in Table 1.

[0056] Example 4

[0057] Dissolve 5.47g of potassium carbonate in 120g of deionized water, add 100g of alumina, soak for 5 hours, dry in air at 100℃ for 10 hours, and calcine at 300℃ in air for 10 hours to obtain K-modified alumina, wherein the mass content of modifier K is 3%.

[0058] 13.42g of chromium nitrate was dissolved in 120g of deionized water, and 100g of the above-mentioned K-modified alumina was added. After soaking for 5 hours, it was dried in air at 120℃ for 10 hours. After drying, it was calcined in air at 350℃ for 5 hours to obtain composite modified alumina, wherein the mass content of the modifier Cr was 6%.

[0059] Dissolve 1.39g of ammonium heptamolybdate in 150g of deionized water, add 100g of ZSM-5 molecular sieve, soak for 5h, dry in air at 120℃ for 10h, and calcine at 550℃ in air atmosphere for 3h to obtain Mo modified molecular sieve, wherein the mass content of the modifier Mo is 0.75%.

[0060] Take 40g of the above-mentioned composite modified alumina and 60g of Mo modified molecular sieve, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 100℃ for 10 hours and calcine in air at 600℃ for 5 hours to obtain a catalyst for toluene disproportionation reaction.

[0061] The mass fraction of the composite modified alumina in the toluene disproportionation catalyst is 40%, and the mass fraction of the modified molecular sieve is 60%.

[0062] The above catalyst was used in the toluene disproportionation reaction under the following conditions: temperature 470℃, toluene weight hourly space velocity (WHSV) 5 h⁻¹. -1 The molar ratio of hydrogen to toluene was 1, the reaction pressure was 3 MPa, and the reaction performance is shown in Table 1.

[0063] Example 5

[0064] 9.29g of magnesium nitrate was dissolved in 120g of deionized water, and 100g of alumina was added. After soaking for 5 hours, the alumina was dried in air at 100℃ for 10 hours. After drying, the alumina was calcined in air at 350℃ for 6 hours to obtain Mg-modified alumina, wherein the mass content of the modifier Mg was 1.5%.

[0065] 26.12g of cobalt acetate was dissolved in 120g of deionized water, and 100g of the above Mg-modified alumina was added. After soaking for 5 hours, it was dried in air at 150℃ for 1 hour. After drying, it was calcined in air at 300℃ for 10 hours to obtain composite modified alumina, wherein the mass content of the modifier Co was 8%.

[0066] Dissolve 0.361g of ammonium perrhenate in 150g of deionized water, add 100g of mordenite molecular sieve, soak for 5h, dry in air at 120℃ for 10h, and calcine at 600℃ in air atmosphere for 1h to obtain Re modified molecular sieve, wherein the mass content of the modifier Re is 0.25%.

[0067] Take 60g of the above-mentioned composite modified alumina and 40g of Re modified molecular sieve, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 120℃ for 6 hours and calcine in air at 600℃ for 10 hours to obtain a catalyst for toluene disproportionation reaction.

[0068] The toluene disproportionation catalyst contains 60% by mass of composite modified alumina and 40% by mass of modified molecular sieve.

[0069] The above catalyst was used in the toluene disproportionation reaction under the following conditions: temperature 420℃, toluene weight hourly space velocity (WHSV) 4 h⁻¹. -1 The molar ratio of hydrogen to toluene was 2, the reaction pressure was 4 MPa, and the reaction performance is shown in Table 1.

[0070] Example 6

[0071] Dissolve 1.76g of calcium nitrate and 1.81g of potassium nitrate in 120g of deionized water, add 100g of alumina, soak for 5 hours, dry in air at 120℃ for 5 hours, and calcine at 350℃ in air for 6 hours to obtain Ca and K modified alumina, wherein the mass content of modifier Ca is 1% and the mass content of modifier K is 1%.

[0072] 13.42g of chromium nitrate and 6.53g of cobalt acetate were dissolved in 120g of deionized water. 100g of the above-mentioned Ca and K modified alumina was added, and the mixture was impregnated for 5 hours. After that, it was dried in air at 120℃ for 10 hours. After drying, it was calcined in air at 350℃ for 5 hours to obtain composite modified alumina, wherein the mass content of the modifier Cr was 6% and the mass content of the modifier Co was 2%.

[0073] Dissolve 1.39 g of ammonium heptamolybdate and 0.108 g of ammonium perrhenate in 150 g of deionized water, add 100 g of ZSM-5 molecular sieve, impregnate for 5 h, dry in air at 120 °C for 10 h, and calcine at 550 °C in air for 3 h to obtain Mo and Re modified molecular sieve, wherein the mass content of modifier Mo is 0.75% and the mass content of modifier Re is 0.075%.

[0074] Take 40g of the above-mentioned composite modified alumina and 60g of Mo and Re modified molecular sieves, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 100℃ for 10 hours and calcine in air at 600℃ for 5 hours to obtain a catalyst for toluene disproportionation reaction.

[0075] The mass fraction of the composite modified alumina in the toluene disproportionation catalyst is 40%, and the mass fraction of the modified molecular sieve is 60%.

[0076] The above catalyst was used in the toluene disproportionation reaction under the following conditions: temperature 470℃, toluene weight hourly space velocity (WHSV) 5 h⁻¹. -1 The molar ratio of hydrogen to toluene was 1, the reaction pressure was 3 MPa, and the reaction performance is shown in Table 1.

[0077] Comparative Example 1

[0078] Dissolve 0.216g of ammonium perrhenate in 150g of deionized water, add 100g of ZSM-5 molecular sieve, soak for 5h, dry in air at 120℃ for 10h, and calcine at 550℃ in air atmosphere for 3h to obtain Re modified molecular sieve, wherein the mass content of the modifier Re is 0.15%.

[0079] Take 50g of unmodified alumina and 50g of the above Re-modified molecular sieve, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 100℃ for 10 hours and calcine in air at 600℃ for 5 hours to obtain a catalyst for toluene disproportionation reaction.

[0080] The toluene disproportionation catalyst contains 50% alumina and 50% modified molecular sieve by mass.

[0081] The above catalyst was used in the toluene disproportionation reaction under the following conditions: temperature 450℃, toluene weight hourly space velocity (WHSV) 5 h⁻¹. -1 The hydrogen / toluene molar ratio was 3, the reaction pressure was 5 MPa, and the reaction performance is shown in Table 1.

[0082] Comparative Example 2

[0083] Dissolve 3.61g of potassium carbonate in 120g of deionized water, add 100g of alumina, soak for 5 hours, dry in air at 100℃ for 10 hours, and calcine at 300℃ in air for 10 hours to obtain K-modified alumina, wherein the mass content of modifier K is 2%.

[0084] Dissolve 0.216g of ammonium perrhenate in 150g of deionized water, add 100g of ZSM-5 molecular sieve, soak for 5h, dry in air at 120℃ for 10h, and calcine at 550℃ in air atmosphere for 3h to obtain Re modified molecular sieve, wherein the mass content of the modifier Re is 0.15%.

[0085] Take 50g of the above-mentioned K-modified alumina and 50g of Re-modified molecular sieve, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 100℃ for 10 hours and calcine in air at 600℃ for 5 hours to obtain a catalyst for toluene disproportionation reaction.

[0086] The mass fraction of K-modified alumina and the mass fraction of modified molecular sieve in the toluene disproportionation catalyst are both 50%.

[0087] The above catalyst was used in the toluene disproportionation reaction under the following conditions: temperature 450℃, toluene weight hourly space velocity (WHSV) 5 h⁻¹.-1 The hydrogen / toluene molar ratio was 3, the reaction pressure was 5 MPa, and the reaction performance is shown in Table 1.

[0088] Comparative Example 3

[0089] 19.82g of cobalt nitrate was dissolved in 120g of deionized water, and 100g of alumina was added. After soaking for 5 hours, the alumina was dried in air at 120℃ for 10 hours. After drying, the alumina was calcined in air at 350℃ for 5 hours to obtain Co-modified alumina, wherein the mass content of the modifier Co was 6%.

[0090] Dissolve 0.216g of ammonium perrhenate in 150g of deionized water, add 100g of ZSM-5 molecular sieve, soak for 5h, dry in air at 120℃ for 10h, and calcine at 550℃ in air atmosphere for 3h to obtain Re modified molecular sieve, wherein the mass content of the modifier Re is 0.15%.

[0091] Take 50g of the above-mentioned Co-modified alumina and 50g of Re-modified molecular sieve, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 100℃ for 10 hours and calcine in air at 600℃ for 5 hours to obtain a catalyst for toluene disproportionation reaction.

[0092] The toluene disproportionation catalyst contains 50% Co-modified alumina and 50% modified molecular sieve by mass.

[0093] Comparative Example 4

[0094] Dissolve 3.61g of potassium carbonate in 120g of deionized water, add 100g of alumina, soak for 5 hours, dry in air at 100℃ for 10 hours, and calcine at 300℃ in air for 10 hours to obtain K-modified alumina, wherein the mass content of modifier K is 2%.

[0095] 19.82g of cobalt nitrate was dissolved in 120g of deionized water, and 100g of the above-mentioned K-modified alumina was added. After soaking for 5 hours, it was dried in air at 120℃ for 10 hours. After drying, it was calcined in air at 350℃ for 5 hours to obtain composite modified alumina, wherein the mass content of the modifier Co was 6%.

[0096] Take 50g of the above-mentioned composite modified alumina and 50g of unmodified ZSM-5 molecular sieve, add an appropriate amount of guar gum powder extrusion aid and nitric acid solution, mix evenly and knead into shape, then dry in air at 100℃ for 10 hours and calcine in air at 600℃ for 5 hours to obtain a catalyst for toluene disproportionation reaction.

[0097] The mass fraction of the composite modified alumina and the mass fraction of the molecular sieve in the toluene disproportionation catalyst are 50%.

[0098] The above catalyst was used in the toluene disproportionation reaction under the following conditions: temperature 450℃, toluene weight hourly space velocity (WHSV) 5 h⁻¹. -1 The hydrogen / toluene molar ratio was 3, the reaction pressure was 5 MPa, and the reaction performance is shown in Table 1.

[0099] Table 1. Performance of Toluene Disproportionation Reaction in Implementation and Comparative Examples

[0100]

[0101]

Claims

1. A toluene disproportionation catalyst, said catalyst comprising composite modified alumina and modified molecular sieve; in, The composite modified alumina comprises alkali metals and / or alkaline earth metals, transition metal A, and alumina. The modified molecular sieve comprises a molecular sieve and a modified metal; The transition metal A is selected from at least one of Co, Cr, and Mn; the modifying metal in the modified molecular sieve is at least one of Pt, Re, and Mo. The modified molecular sieve is selected from at least one of ZSM-5, mordenite, and β-zeolite; The preparation method of the toluene disproportionation catalyst includes the following steps: (a) Take alumina, modify it with alkali metals and / or alkaline earth metals, and then dry and calcine it to obtain modified alumina; (b) Take the above modified alumina, modify it with transition metal A, and then dry and calcine it to obtain composite modified alumina; (c) Take a molecular sieve, modify it with a modified metal, and then dry and calcine it to obtain a modified molecular sieve; (d) Take the composite modified alumina from step (b) and the modified molecular sieve from step (c), add an extrusion aid and a gelling agent, mix and shape them, and then dry and calcine to obtain the catalyst.

2. The catalyst according to claim 1, characterized in that, The mass fraction of composite modified alumina in the toluene disproportionation catalyst is 30-60%, and the mass fraction of modified molecular sieve is 40-70%.

3. The catalyst according to claim 1, characterized in that, The transition metal A in the composite modified alumina accounts for 1-30% of the mass content of the composite modified alumina.

4. The catalyst according to claim 1, characterized in that, The alkali metal in the composite modified alumina is K or / and Cs, and the alkaline earth metal is Mg or / and Ca; the alkali metal and / or alkaline earth metal account for 0.5-3% of the mass content of the composite modified alumina.

5. The catalyst according to claim 1, characterized in that, The modified metal accounts for 0.01-5% of the mass of the modified molecular sieve.

6. A method for preparing a toluene disproportionation catalyst according to any one of claims 1-5, comprising the following steps: (a) Take alumina, modify it with alkali metals and / or alkaline earth metals, and then dry and calcine it to obtain modified alumina; (b) Take the above modified alumina, modify it with transition metal A, and then dry and calcine it to obtain composite modified alumina; (c) Take a molecular sieve, modify it with a modified metal, and then dry and calcine it to obtain a modified molecular sieve; (d) Take the composite modified alumina from step (b) and the modified molecular sieve from step (c), add an extrusion aid and a gelling agent, mix and shape them, and then dry and calcine to obtain the catalyst.

7. The preparation method according to claim 6, characterized in that, The alkali metal in step (a) is K or / and Cs, and the alkaline earth metal is Mg or / and Ca. The alkali metal and / or alkaline earth metal account for 0.5-3% of the mass of the modified alumina.

8. The preparation method according to claim 6, characterized in that, The transition metal A mentioned in step (b) is at least one of Co, Cr, and Mn, and the mass content of transition metal A in the composite modified alumina is 1 to 30%.

9. The preparation method according to claim 6, characterized in that, The modified metal in step (c) is at least one of Pt, Re, and Mo, and the modified metal accounts for 0.01~5% of the mass content of the modified molecular sieve.

10. The preparation method according to claim 6, characterized in that, In the molding process of step (d), the extrusion aid is at least one of guar gum powder, cyclodextrin, and methylcellulose, and the gelling agent is at least one of nitric acid, sulfuric acid, and hydrochloric acid.

11. The use of the toluene disproportionation catalyst according to any one of claims 1-5 in the toluene disproportionation reaction.

12. The application according to claim 11, characterized in that, The reaction conditions are: a reaction temperature of 350~650°C. o C, Toluene weight hourly space velocity is 1~10h -1 The molar ratio of hydrogen to toluene is 1~10, and the reaction pressure is 1~10 MPa.

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