Method for demethylating C9 < + > aromatic hydrocarbon

Abstract

The invention discloses a method for demethylating C9 < + > aromatic hydrocarbon. The method comprises the following step: in the presence of hydrogen, carrying out contact reaction on a C9 < + > aromatic hydrocarbon raw material and an aromatic hydrocarbon dealkylation catalyst to obtain an aromatic hydrocarbon dealkylation material flow. According to the method, the dealkylation reaction can be fully utilized to realize demethylation of the C2 + side chain of the C9 + aromatic hydrocarbon, so that the number of methyl groups in the aromatic hydrocarbon material flow is increased, and the methyl / benzene ring ratio of a transalkylation unit is increased.

Description

Technical Field

[0001] The present invention relates to the field of catalysis, and in particular to a C9 + Method for the demethylation of aromatic hydrocarbons. Background Art

[0002] In the petrochemical production process, the main sources of aromatics include catalytic reforming, steam cracking, catalytic cracking, light hydrocarbon aromatization, etc. In addition to producing common light aromatics such as benzene (B), toluene (T) and xylene (X), the above processes also produce some carbon nine / carbon ten aromatics (C9 / C 10 Aromatics). This part of C9 / C 10 Aromatic hydrocarbons are monocyclic aromatic hydrocarbons containing side chain substituents. According to the number of carbon atoms in the substituents, the side chain substituents can be divided into methyl and C2 + Substituents, such as trimethylbenzene, methylethylbenzene, propylbenzene, tetramethylbenzene, etc. C9 / C 10 In addition to polymethyl substituents, aromatic hydrocarbons also contain a large amount of C2 + Side chain substituents, for example, in C9 aromatics produced by catalytic reforming, the content of trimethylbenzene is 53-54%, the content of methyl and ethylbenzene is 27-28%, and the content of propylbenzene is 8-10%.

[0003] At this stage, this part of C9 / C 10 The main purpose of aromatics is to increase the production of light aromatics such as BTX. Commonly used technologies include but are not limited to: (1) Toluene disproportionation and transalkylation technology: This technology uses toluene and C9 / C 10 Aromatic hydrocarbons are used as raw materials to increase the production of benzene and xylene through methyl transfer reaction and aromatic side chain hydrogenation dealkylation reaction. In this technology, methyl groups mainly undergo transfer reactions between aromatic hydrocarbons, while C2 + The side chain substituents are removed by hydrogenation dealkylation reaction (Aromatics Technology [M]. Beijing: China Petrochemical Press, 2014: 156-191.), and the common catalyst is metal-modified molecular sieve; (2) Aromatics catalytic hydrogenation dealkylation technology: This technology uses toluene and above alkyl aromatics as raw materials, and removes all side chain substituents including methyl through side chain catalytic hydrogenation dealkylation reaction, and C2 + The removal rate of side chain substituents is higher than that of methyl groups. Common catalysts include Cr2O3 / Al2O3, MoO3 / Al2O3, etc. (Research Progress of Catalysts for Catalytic Hydrodealkylation of Alkyl Aromatics, Industrial Catalysis, 2004, 12(11): 1-6.)

[0004] It can be seen that in the above catalytic conversion process of alkyl aromatics, C2 + The side chain substituents are all removed by hydrogenation to generate the corresponding C2 + Alkane. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a C9 + A method for demethylating aromatics. Compared with the traditional toluene disproportionation and transalkylation technology, this method can make full use of the dealkylation reaction to achieve C9 + Aromatic C2 + The side chain is demethylated to increase the number of methyl groups in the aromatics stream and improve the methyl / benzene ring ratio of the alkyl transfer unit. This can be used for subsequent alkyl transfer to significantly increase the xylene yield and selectivity of the unit.

[0006] The present invention provides a C9 + The method for demethylating aromatic hydrocarbons comprises the following steps:

[0007] Under hydrogenation conditions, C9 + The aromatic hydrocarbon feedstock is contacted with an aromatic hydrocarbon dealkylation catalyst to react, thereby obtaining an aromatic hydrocarbon dealkylation stream;

[0008] The aromatic hydrocarbon dealkylation catalyst comprises an oxide carrier and a bimetallic component.

[0009] Furthermore, the C9 + Aromatic hydrocarbons contain C2 + The carbon number of the side chain substituent (carbon 2 or more side chain substituent) is a monocyclic aromatic hydrocarbon with more than nine carbon atoms, preferably containing C2 + The side chain of the single ring C9 / C 10 Aromatics (i.e. C9 aromatics and / or C 10 Aromatic hydrocarbons). The present invention is for C9 + The source of the aromatic hydrocarbon feedstock is not particularly limited, for example, but not limited to, at least one of the products from catalytic reforming, pyrolysis gasoline hydrogenation, hydrocracking, etc. + Among aromatic raw materials, C9 + The mass content of aromatic hydrocarbons is above 95.0%.

[0010] Furthermore, in the bimetallic catalyst for aromatic dealkylation, the first metal is at least one of Rh, Ir and Re, preferably Rh or / and Ir, more preferably Rh. The second metal is Zn or / and Sn.

[0011] Furthermore, the carrier in the aromatic dealkylation catalyst is at least one of γ-alumina, SiO2, and MgO, preferably γ-alumina.

[0012] Furthermore, the mass content of the first metal in the aromatic dealkylation catalyst is 0.01% to 10%, preferably 0.01% to 1%, more preferably 0.1% to 0.6%; the mass content of the second metal is 0.5% to 20%, preferably 1% to 5%. The catalyst has high terminal methyl removal activity and low aromatic ring loss rate. The aromatic dealkylation catalyst can be obtained by conventional preparation methods in the art, preferably by using an equal volume impregnation method to impregnate the bimetallic into the carrier.

[0013] Furthermore, in the method, a dealkylation reaction is carried out under the following reaction conditions: a temperature of 300 to 550° C., a reaction pressure of 2 to 5 MPa, and C9 + Aromatic mass space velocity is 1~10h -1 , hydrogen and C9 + The molar ratio of aromatic hydrocarbons is 2-6.

[0014] Compared with the prior art, the advantages of the present invention are:

[0015] Compared with traditional C9 / C 10 Aromatic hydrocarbon utilization technology (such as toluene disproportionation and alkyl transfer technology, heavy aromatic hydrocarbon lightening technology, etc.), the present invention adopts a specific aromatic hydrocarbon dealkylation catalyst, utilizes C9 + C2 in aromatics + The side chain increases the number of methyl groups in the aromatic materials, improves the methyl / benzene ratio, and cooperates with the liquid phase transalkylation reaction to significantly increase the xylene yield and selectivity. 10 C2 in aromatics + The side chain is effectively converted, so that the C9 / C 10 Aromatic hydrocarbons are basically polymethyl aromatic hydrocarbons, and the alkyl transfer unit can achieve liquid phase conversion. The process is much simpler than traditional toluene disproportionation and alkyl transfer technology, and can significantly improve the yield and selectivity of xylene. DETAILED DESCRIPTION

[0016] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0017] The raw materials used in the examples and comparative examples of the present invention are commercially available and have an analytical purity (AR).

[0018] The dealkylation reaction described in the present invention is mainly a terminal methylation reaction. For example, taking ethyl methylbenzene as an example, the specific reaction process is as follows: the terminal methyl of the ethyl group substituted by the side chain undergoes a terminal methylation reaction by hydrogenation to generate xylene and methane, while the traditional route is that the ethyl group substituted by the side chain is removed as a whole by hydrogenation to generate toluene and ethane. The schematic process is as follows:

[0019] .

[0020] In the present invention, the reaction of toluene and C9 / C 10 The overall conversion of aromatics and the selectivity to xylenes are defined as follows:

[0021]

[0022]

[0023] Example 1

[0024] 1. Preparation of aromatic dealkylation catalyst

[0025] 100 g of γ-Al2O3 carrier was taken, and 0.3% Rh, 0.1% Re and 5% Zn were introduced by equal volume impregnation method to prepare aromatic dealkylation catalyst D1.

[0026] 2. Catalyst evaluation

[0027] C9 + Aromatic feedstocks come from catalytic reforming of C2 + C9 / C of the side chain 10 Aromatics, among which C9 aromatics and C 10 The mass content of aromatics is 100%. Aromatic dealkylation reaction conditions: reaction temperature 500℃, reaction pressure 3MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0028] The C9 / C 10 The total conversion rate of aromatics was 50.6%, the raw material methylbenzene ratio was 2.5, and the aromatics dealkylation stream methylbenzene ratio was 3.4.

[0029] Example 2

[0030] 1. Preparation of aromatic dealkylation catalyst

[0031] 100 g of γ-Al2O3 carrier was taken, and 0.5% Ir, 0.1% Re and 3% Sn were introduced by equal volume impregnation method to prepare aromatic dealkylation catalyst D2.

[0032] 2. Catalyst evaluation

[0033] C9 + The source and content of aromatic hydrocarbon raw materials are the same as those in Example 1, wherein the ratio of raw material methylbenzene is different, as follows. Aromatic hydrocarbon dealkylation reaction conditions: reaction temperature 350°C, reaction pressure 5MPa, C9 / C 10 Aromatic feed mass space velocity 1h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 6 / 1, and an aromatics dealkylation stream is obtained.

[0034] The C9 / C 10 The total conversion rate of aromatics was 49.4%, the raw material methylbenzene conversion rate was 2.8 on a month-on-month basis, and the aromatics dealkylation stream methylbenzene conversion rate was 3.9 on a month-on-month basis.

[0035] Example 3

[0036] 1. Preparation of aromatic dealkylation catalyst

[0037] 100 g of γ-Al2O3 carrier was taken, and 0.1% Rh, 0.1% Ir and 2% Sn were introduced by equal volume impregnation method to prepare aromatic dealkylation catalyst D3.

[0038] 2. Catalyst evaluation

[0039] C9 + The source and content of aromatic raw materials are the same as those in Example 1, wherein the ratio of raw material methylbenzene is different, as follows. Aromatic dealkylation reaction conditions: reaction temperature 500°C, reaction pressure 5MPa, C9 / C 10 Aromatic feed mass space velocity 8h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 6 / 1, and an aromatics dealkylation stream is obtained.

[0040] The C9 / C 10 The total conversion rate of aromatics was 48.2%, the raw material methylbenzene conversion rate was 2.6 on a month-on-month basis, and the aromatics dealkylation stream methylbenzene conversion rate was 3.4 on a month-on-month basis.

[0041] Example 4

[0042] 1. Preparation of aromatic dealkylation catalyst

[0043] 100 g of γ-Al2O3 carrier was taken, and 0.3% Rh and 5% Zn were introduced by equal volume impregnation method to prepare aromatic dealkylation catalyst D4.

[0044] 2. Catalyst evaluation

[0045] C9 +The aromatic raw materials were the same as those in Example 1. The aromatic dealkylation reaction conditions were: reaction temperature 500°C, reaction pressure 3 MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0046] The C9 / C 10 The total conversion rate of aromatics was 49.5%, the raw material methylbenzene ratio was 2.5, and the aromatic dealkylation stream methylbenzene ratio was 3.5.

[0047] Example 5

[0048] 1. Preparation of aromatic dealkylation catalyst

[0049] 100 g of γ-Al2O3 carrier was taken, and 0.5% Ir and 3% Sn were introduced by equal volume impregnation method to prepare aromatic dealkylation catalyst D5.

[0050] 2. Catalyst evaluation

[0051] C9 + The source and content of aromatic hydrocarbon raw materials are the same as those in Example 1, wherein the ratio of raw material methylbenzene is different, as follows. Aromatic hydrocarbon dealkylation reaction conditions: reaction temperature 350°C, reaction pressure 5MPa, C9 / C 10 Aromatic feed mass space velocity 1h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 6 / 1, and an aromatics dealkylation stream is obtained.

[0052] The C9 / C 10 The total conversion rate of aromatics was 46.2%, the raw material methylbenzene conversion rate was 2.6 on a month-on-month basis, and the aromatics dealkylation stream methylbenzene conversion rate was 3.7 on a month-on-month basis.

[0053] Example 6

[0054] 1. Preparation of aromatic dealkylation catalyst

[0055] 100 g of γ-Al2O3 carrier was taken, and 0.1% Re and 5% Zn were introduced by equal volume impregnation method to prepare aromatic dealkylation catalyst D6.

[0056] 2. Catalyst evaluation

[0057] C9 + The aromatic raw materials were the same as those in Example 1. The aromatic dealkylation reaction conditions were: reaction temperature 500°C, reaction pressure 3 MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0058] The C9 / C 10 The total conversion rate of aromatics was 50.6%, the raw material methylbenzene ratio was 2.5, and the aromatic dealkylation stream methylbenzene ratio was 3.1.

[0059] Example 7

[0060] 1. Preparation of aromatic dealkylation catalyst

[0061] 100 g of SiO2 carrier was taken, and 0.1% Re and 5% Zn were introduced by equal volume impregnation method to prepare aromatic dealkylation catalyst D7.

[0062] 2. Catalyst evaluation

[0063] C9 + The aromatic raw materials were the same as those in Example 1. The aromatic dealkylation reaction conditions were: reaction temperature 500°C, reaction pressure 3 MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0064] The C9 / C 10 The total conversion rate of aromatics was 48.9%, the raw material methylbenzene ratio was 2.5, and the aromatic dealkylation stream methylbenzene ratio was 3.2.

[0065] Example 8

[0066] 1. Preparation of aromatic dealkylation catalyst

[0067] 100 g of MgO carrier was taken, and 0.1% Re and 5% Zn were introduced by an equal volume impregnation method to prepare an aromatic dealkylation catalyst D8.

[0068] 2. Catalyst evaluation

[0069] C9 + The aromatic raw materials were the same as those in Example 1. The aromatic dealkylation reaction conditions were: reaction temperature 500°C, reaction pressure 3 MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0070] The C9 / C 10 The total conversion rate of aromatics was 52.4%, the raw material methylbenzene ratio was 2.5, and the aromatic dealkylation stream methylbenzene ratio was 3.5.

[0071] Comparative Example 1

[0072] 1. Preparation of aromatic dealkylation catalyst

[0073] 100 g of γ-Al2O3 carrier (same as Example 1) was taken, and 0.3% of Rh was introduced by an equal volume impregnation method to prepare an aromatic dealkylation catalyst DD1.

[0074] 2. Catalyst evaluation

[0075] C9 + The aromatic raw materials were the same as those in Example 1. The aromatic dealkylation reaction conditions were: reaction temperature 500°C, reaction pressure 3 MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0076] The C9 / C 10 The total conversion rate of aromatics was 50.5%, the raw material methylbenzene ratio was 2.5, and the aromatic dealkylation stream methylbenzene ratio was 2.2.

[0077] Comparative Example 2

[0078] 1. Preparation of aromatic dealkylation catalyst

[0079] 100 g of γ-Al2O3 carrier (same as Example 1) was taken, and 5% of Zn was introduced by an equal volume impregnation method to prepare an aromatic dealkylation catalyst DD2.

[0080] 2. Catalyst evaluation

[0081] C9 + The aromatic raw materials were the same as those in Example 1. The aromatic dealkylation reaction conditions were: reaction temperature 500°C, reaction pressure 3 MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0082] The C9 / C 10 The total conversion rate of aromatics was 44.7%, the raw material methylbenzene ratio was 2.5, and the aromatic dealkylation stream methylbenzene ratio was 2.1.

[0083] Comparative Example 3

[0084] 1. Preparation of aromatic dealkylation catalyst

[0085] 100 g of γ-Al2O3 carrier (same as Example 1) was taken, and 0.03% of Pt and 1.0% of Mo were introduced by an equal volume impregnation method to prepare an aromatic dealkylation catalyst DD3.

[0086] 2. Catalyst evaluation

[0087] C9 + The aromatic raw materials were the same as those in Example 1. The aromatic dealkylation reaction conditions were: reaction temperature 500°C, reaction pressure 3 MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0088] The C9 / C 10 The total conversion rate of aromatics was 49.2%, the raw material methylbenzene ratio was 2.5, and the aromatic dealkylation stream methylbenzene ratio was 1.9.

[0089] Comparative Example 4

[0090] 1. Preparation of aromatic dealkylation catalyst

[0091] Take 100 g of γ-Al2O3 carrier (same as Example 1), introduce 0.3% Pt and 5% Zn by equal volume impregnation method to prepare aromatic dealkylation catalyst DD4.

[0092] 2. Catalyst evaluation

[0093] C9 + The aromatic raw materials were the same as those in Example 1. The aromatic dealkylation reaction conditions were: reaction temperature 500°C, reaction pressure 3 MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0094] The above reaction was performed for 72 hours, and the C9 / C 10 The total conversion rate of aromatics was 56.7%, the raw material methylbenzene ratio was 2.5, and the aromatic dealkylation stream methylbenzene ratio was 1.4.

[0095] Comparative Example 5

[0096] 1. Preparation of aromatic dealkylation catalyst

[0097] 100 g of ZSM-5 (SiO2 / Al2O3 molar ratio 25) carrier was taken, and 0.3% Rh, 0.1% Re and 5% Zn were introduced by equal volume impregnation method to prepare aromatic dealkylation catalyst DD5.

[0098] 2. Catalyst evaluation

[0099] C9 + The aromatic raw material is the same as in Example 1. Aromatic dealkylation reaction conditions: reaction temperature 500°C, reaction pressure 3 MPa, C9 / C 10 Aromatic feed mass space velocity 4h -1 , hydrogen and C9 / C 10 The molar ratio of aromatics is 3 / 1, and an aromatic dealkylation stream is obtained.

[0100] The C9 / C 10 The total conversion rate of aromatics was 49.4%, the raw material methylbenzene conversion rate was 2.5 on a month-on-month basis, and the aromatics dealkylation stream methylbenzene conversion rate was 1.6 on a month-on-month basis.

[0101] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A C9 + The method for demethylating aromatic hydrocarbons comprises the following steps: Under hydrogenation conditions, C9 + The aromatic hydrocarbon feedstock is contacted with an aromatic hydrocarbon dealkylation catalyst to react to obtain an aromatic hydrocarbon dealkylation stream; The aromatic hydrocarbon dealkylation catalyst comprises an oxide carrier and a bimetallic component.

2. The method according to claim 1, characterized in that: The bimetal in the aromatic dealkylation catalyst, wherein the first metal is at least one of Rh, Ir and Re; and the second metal is Zn and / or Sn.

3. The method according to claim 1, characterized in that The bimetal in the aromatic dealkylation catalyst, wherein the first metal is Rh and / or Ir.

4. The method according to claim 1, characterized in that: The bimetal in the aromatic dealkylation catalyst, wherein the first metal is Rh.

5. The method according to claim 1, characterized in that The carrier in the aromatic dealkylation catalyst is at least one of γ-alumina, SiO2 and MgO.

6. The method according to claim 1, characterized in that The mass content of the first metal in the aromatic dealkylation catalyst is 0.01% to 10%; the mass content of the second metal is 0.5% to 20%.

7. The method according to claim 1, characterized in that The mass content of the first metal in the aromatic dealkylation catalyst is 0.1% to 0.6%; the mass content of the second metal is 1% to 5%.

8. The method according to claim 1, characterized in that The C9 + Aromatic hydrocarbons contain C2 + C9 on the side chain + Aromatic hydrocarbons.

9. The method according to claim 1, characterized in that: The dealkylation reaction conditions are as follows: the temperature is 300-550°C, the reaction pressure is 2-5MPa, C9 + The mass space velocity of aromatic raw materials is 1 to 10 h -1 , hydrogen and C9 + The molar ratio of aromatic hydrocarbons is 2-6.

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