Method and system for increasing the yield of toluene and xylene from reformate

Abstract

The present application relates to the technical field of petroleum chemical industry, disclose a kind of method for improving the yield of toluene and xylene of reforming product oil, the system for improving the yield of toluene and xylene of reforming product oil.A kind of method for improving the yield of toluene and xylene of reforming product oil, the method comprises: under the alkylation reaction condition, in the presence of alkylation catalyst, C6-C7 fraction in reforming product oil is contacted with benzene and optionally hydrogen gas to carry out alkylation reaction;Wherein, alkylation catalyst includes MFI type zeolite, binder and optionally metal component, optionally metal functional adjuvant component.The method for improving the yield of toluene and xylene of reforming product oil has the advantages that toluene and xylene yield is high, and the effective separation of aromatic hydrocarbon and non-aromatic hydrocarbon under the condition of no extraction can be realized.

Description

Technical Field

[0001] This invention relates to the technical field of petrochemicals, specifically to a method and system for improving the yield of toluene and xylene in reforming products. Background Technology

[0002] Catalytic reforming is the main process for producing aromatics. Globally, 38% of benzene and 87% of xylene come from catalytic reforming units. Typical processes include Axens' Aromizing continuous reforming process, UOP's CCR Platforming process, and Sinopec's ultra-low pressure continuous reforming and countercurrent moving bed continuous reforming processes. After years of development, continuous reforming technology has become very mature. In recent years, with the liberalization of national policies, in addition to Sinopec and PetroChina, a large number of private enterprises such as Zhejiang Petrochemical and Hengli Petrochemical have formed large-scale integrated refining and chemical projects with multiple product chains and clusters. This has further impacted the already nearly saturated aromatics market. The supply shortage in the pure benzene market has been broken, inevitably leading to a large surplus of benzene, while the domestic demand for toluene and xylene remains substantial. The comprehensive utilization of benzene will undoubtedly become a priority for current producers.

[0003] In addition to aromatics, the products from the reforming unit also include some non-aromatics. Because alkanes and aromatics have similar boiling points in the C6-C7 fraction, aromatics cannot be separated by simple fractionation and must be separated by aromatic extraction. Aromatic extraction consumes a large amount of extraction solvent, which severely corrodes the equipment, and the extracted raffinate (C6-C7 non-aromatics) has a narrow range of applications and low added value. Summary of the Invention

[0004] The purpose of this invention is to overcome the supply and demand imbalance of benzene, toluene, and xylene in existing technologies, and to provide a method and system for improving the yield of toluene and xylene in reforming products. This method for achieving high yields of toluene and xylene in reforming products has the advantage of high toluene and xylene yields and can achieve effective separation of aromatics and non-aromatics without extraction conditions.

[0005] This invention directly integrates benzene and alkane alkylation technology with reforming technology, converting all C6-C7 long-chain alkanes from the top of the deheptane tower into C1-C3 gases and alkylbenzenes. This allows for the separation of aromatics and non-aromatics without extraction, and also helps to solve the current supply and demand imbalance of benzene, toluene, and xylene.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for improving the yield of toluene and xylene in reforming products, the method comprising:

[0007] Under alkylation reaction conditions, in the presence of an alkylation catalyst, the C6-C7 components in the reformate are contacted with benzene and optionally hydrogen to carry out an alkylation reaction; wherein the alkylation catalyst includes MFI type zeolite, binder, and optionally metal components and optionally metal functional additive components.

[0008] Preferably, the silicon-aluminum molar ratio of the MFI type zeolite is 25-200, more preferably 25-100.

[0009] Preferably, the MFI type zeolite is selected from ZSM-5.

[0010] Preferably, the alkylation catalyst further includes a second zeolite, which is selected from at least one of β-zeolite and MCM22 zeolite.

[0011] A second aspect of the present invention provides a system for improving the yield of toluene and xylene in reforming products, the system comprising: a reforming reactor, a cutting unit, and an alkylation reactor connected in series;

[0012] The system also includes a benzene supply unit and optionally a hydrogen supply unit connected to the alkylation reactor, the benzene supply unit being used to supply benzene to the alkylation reactor and the hydrogen supply unit being used to supply hydrogen to the alkylation reactor.

[0013] Preferably, the system does not include an aromatics extraction unit.

[0014] This invention can maximize the conversion of reformed materials into toluene and xylene, greatly increasing their added value. It also exhibits high selectivity for toluene and xylene and can produce at least one high-quality olefin cracking feedstock, such as ethane and propane, as byproducts. This method features a simple process flow and high product output, successfully solving the problem of benzene surplus and demonstrating significant economic benefits. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the system provided by the present invention.

[0016] Explanation of reference numerals in the attached figures

[0017] 1-Depentanizer, 2-Deheptaneizer, 3-alkylation reactor

[0018] 4-Gas-liquid separator; 5-Benzene fractionation tower; 6-Toluene fractionation tower

[0019] 7-Xylene fractionation tower; 8-Benzene supply unit; 9-Hydrogen supply unit

[0020] A- Reformed oil B- Benzene C- Toluene D- Xylene

[0021] E-heavy aromatics F-C1-C3 gases Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] The first aspect of this invention provides a method for improving the yield of toluene and xylene in reformed oil, the method comprising:

[0024] Under alkylation reaction conditions, in the presence of an alkylation catalyst, the C6-C7 fraction of the reformate is contacted with benzene and optionally hydrogen to carry out an alkylation reaction; wherein the alkylation catalyst includes MFI type zeolite, binder, and optionally metal components and optionally metal functional additive components.

[0025] In this invention, it can be understood that, in the presence of an alkyl catalyst, the C6-C7 fraction of the reformed oil is subjected to an alkylation reaction with benzene. During this process, hydrogen may or may not be introduced. Specifically, the C6-C7 fraction of the reformed oil can be alkylated by contacting benzene and hydrogen, or the C6-C7 fraction of the reformed oil can be directly alkylated with benzene. In a preferred embodiment, the C6-C7 fraction of the reformed oil is alkylated by contacting benzene and hydrogen. By employing the above method, this invention selects a specific alkylation catalyst to alkylate the C6-C7 fraction of reformed oil with benzene and hydrogen. Using an appropriate amount of hydrogen allows for better hydrogenation of unsaturated hydrocarbons present in the alkylation reaction, thus avoiding the adverse effects of unsaturated hydrocarbons (including unsaturated hydrocarbons in reformed oil, unsaturated hydrocarbons generated from alkane cracking, and unsaturated hydrocarbons generated from hydrogen transfer and other side reactions that may occur during the alkylation reaction) potentially polymerizing or condensing to form carbon deposits. This further improves the benzene conversion rate and the selectivity of alkylbenzenes (mainly toluene and xylene). This method features high single-pass benzene conversion and high yields of toluene and xylene.

[0026] The method provided by the present invention does not include aromatic extraction of the reformate or the C6-C7 fraction of the reformate, but instead directly contacts the C6-C7 fraction of the reformate with benzene and optionally hydrogen to carry out an alkylation reaction.

[0027] According to the method of the present invention, in order to further promote the alkylation reaction, preferably, the silica-alumina molar ratio of the MFI type zeolite is 25-200, more preferably 25-100. Using this preferred embodiment, the alkylation reaction can be promoted, thereby increasing the yields of toluene and xylene.

[0028] According to the method of the present invention, there is no specific limitation on the type of MFI zeolite, for example, it can be hydrogen-type.

[0029] According to the method of the present invention, there is no specific limitation on the type of MFI type zeolite; all MFI type zeolites conventionally defined in the art are applicable to the present invention. Preferably, the MFI type zeolite is selected from ZSM-5.

[0030] According to the method of the present invention, preferably, the alkylation catalyst further includes a second zeolite selected from β molecular sieves and / or MCM22 molecular sieves.

[0031] According to the method of the present invention, in the alkylation catalyst, MFI type zeolite accounts for ≥60% by weight of the total zeolite, more preferably ≥80% by weight of the total zeolite. This preferred embodiment is more conducive to improving reaction activity and stability.

[0032] According to the method of the present invention, there is no particular limitation on the type of adhesive, and adhesives conventionally defined in the art are applicable to the present invention. Preferably, the adhesive is alumina and / or silicon oxide.

[0033] In this invention, the alkylation catalyst may or may not contain a metal component.

[0034] According to the method of the present invention, the range of metal components can be broadly selected, as long as it is conducive to promoting the alkylation reaction. Preferably, the metal component is selected from at least one of Pt, Mo, Ni, Ga and Zn, and more preferably Pt and / or Mo.

[0035] In this invention, the alkylation catalyst may contain a metal functional auxiliary component or may not contain a metal functional auxiliary component.

[0036] According to the method of the present invention, the range of types of metal functional adjuvant components is relatively wide. Preferably, the metal functional adjuvant component is selected from at least one of La, Y, and Ag. This preferred embodiment can promote the alkylation reaction, thereby increasing the yield of the target products toluene and xylene.

[0037] According to the method of the present invention, preferably, based on the total amount of the alkylation catalyst, the content of the MFI type zeolite is 60-90% by weight, the content of the binder is 10-40% by weight, the content of the metal component is 0-0.5% by weight, and the content of the metal functional auxiliary component is 0-0.1% by weight.

[0038] More preferably, based on the total amount of the alkylation catalyst, the content of the MFI type zeolite is 80-90% by weight, the content of the binder is 10-20% by weight, the content of the metal component is 0-0.2% by weight, and the content of the metal functional auxiliary component is 0-0.05% by weight.

[0039] In this invention, the preparation method of the alkylation catalyst is not particularly limited, as long as the alkylation catalyst with the above composition can be obtained. In a preferred embodiment, the alkylation catalyst is prepared by the following method: MFI-type zeolite is mixed with a binder, shaped, and then calcined, and then optionally impregnated with a metal component or optionally with a metal functional additive component. In this invention, the impregnation method is not particularly limited, as long as the metal or metal functional additive component is impregnated onto the calcined product. In this invention, there are no limitations on the shaping method; for example, existing standard shaping methods can be used, specifically mixing molecular sieve powder, binder, and guar gum powder with dilute nitric acid, adding the material to an extruder with a pre-installed mold, and extruding the powder as a strip-shaped extrudate.

[0040] According to the method of the present invention, the calcination conditions can be selected from a wide range and can be conventional calcination conditions in the art. Preferably, the calcination conditions include: a calcination temperature of 550-600℃ and a calcination time of 2-4 hours.

[0041] According to the method of the present invention, preferably, the alkylation reaction conditions include: a temperature of 450-550°C, a hydrogen partial pressure of 1-6 MPa, and a weight hourly space velocity of 1-10 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500-4000.

[0042] In a preferred embodiment, the alkylation reaction conditions include: a temperature of 480-520°C, a hydrogen partial pressure of 2-4 MPa, and a weight hourly space velocity of 4-8 h⁻¹. -1 The hydrogen-to-oil volume ratio is 1000-2000. The advantage of this preferred embodiment is that the methane yield in the product is low, and the carbon atom utilization rate is high.

[0043] According to the method of the present invention, preferably, the reformed oil contains n-alkanes, isoalkanes, aromatics, and small amounts of cycloalkanes and olefins.

[0044] According to the method of the present invention, preferably, the method further includes: first cutting the reformed oil to obtain C6-C7 fractions, and then carrying out the alkylation reaction.

[0045] To further improve the alkylation reaction, preferably, the benzene content in the stream for the alkylation reaction is not less than 80% by weight, more preferably 80-90% by weight. The advantage of this preferred embodiment is that it can suppress excessive cracking of alkanes, reduce the yield of methane, and make full use of carbon atoms in alkanes.

[0046] In a preferred embodiment, the method further includes: optionally cooling the aromatic product obtained from the alkylation reaction, followed by gas-liquid separation to obtain a gaseous material and a liquid material. In this invention, the gaseous material contains C1-C3 components, and the liquid material contains benzene, toluene, xylene, and heavy aromatic components. Preferably, the cooling is preferably performed to below 25°C.

[0047] In a preferred case, such as Figure 1 As shown, the method further includes: fractionating the liquid phase material to obtain benzene, toluene and xylene, and then recycling the benzene for alkylation reaction. In this preferred embodiment, benzene can be recycled and the reformed material is maximized to be converted into toluene and xylene.

[0048] The present invention does not impose specific limitations on the fractionation conditions, as long as the required materials can be fractionated. Preferably, the fractionation process includes: first, a first fraction with a distillation range of 65-85°C is fractionated to obtain benzene, which is then returned to continue the alkylation reaction; then a second fraction with a distillation range of 85-105°C is fractionated to obtain toluene; and then a third fraction with a distillation range of 105-145°C is fractionated to obtain xylene.

[0049] A second aspect of the present invention provides a system for improving the yield of toluene and xylene in reformed oils, such as... Figure 1 As shown, the system includes: a reforming reactor (not shown in the figure) connected in series, a cutting unit, and an alkylation reactor 3;

[0050] The system also includes a benzene supply unit 8 and an optional hydrogen supply unit 9 connected to the alkylation reactor 3, wherein the benzene supply unit 8 supplies benzene to the alkylation reactor 3 and the hydrogen supply unit 9 supplies hydrogen to the alkylation reactor 3.

[0051] The system provided by the present invention preferably does not include an aromatics extraction unit. This preferred embodiment has the advantages of low energy consumption and simple process, and is beneficial to solving the current supply and demand imbalance of benzene, toluene, and xylene.

[0052] According to the system provided by the present invention, the system further includes a cutting unit disposed between the reformate A and the alkylation reactor 3 for fractionating the reformate.

[0053] In this invention, preferably, the cutting unit includes a depentanizer 1 and a deheptanizer 2, the inlet of the deheptanizer 2 is connected to the bottom outlet of the depentanizer 1, and the inlet of the alkylation reactor 3 is connected to the top of the deheptanizer 2, for cutting the reformed oil into C6-C7 fractions and then feeding them into the alkylation reactor 3.

[0054] According to the system provided by the present invention, preferably, the system further includes a gas-liquid separator 4 connected to the alkylation reactor 3, the gas-liquid separator 4 being used to separate the aromatic hydrocarbon-containing product obtained from the alkylation reaction into gaseous and liquid phase materials. In the present invention, the specific device of the gas-liquid separator 4 is not specifically limited; those skilled in the art can select it according to specific needs, for example, it can be a high-pressure separator.

[0055] According to the system provided by the present invention, preferably, the system further includes a fractionation unit connected to the gas-liquid separator 4, the fractionation unit being used to fractionate the liquid phase material to obtain benzene, toluene and xylene.

[0056] In a preferred embodiment, the fractionation unit is connected to the alkylation reactor 3, so that the benzene obtained from the fractionation unit is recycled back to the alkylation reactor 3. This preferred embodiment enables the recycling of benzene.

[0057] In a preferred embodiment, the fractionation unit includes a benzene fractionation tower 5, a toluene fractionation tower 6, and a xylene fractionation tower 7. The inlet of the benzene fractionation tower 5 is connected to the liquid phase material outlet of the gas-liquid separator 4, and is used to perform a first fractionation on the liquid phase material separated by the gas-liquid separator 4 to obtain benzene. The top material outlet of the benzene fractionation tower 5 is connected to the alkylation reactor 3, and is used to recycle the benzene obtained from the fractionation of the benzene fractionation tower 5 for the alkylation reaction. The inlet of the toluene fractionation tower 6 is connected to the bottom outlet of the benzene fractionation tower 5, and is used to perform a second fractionation on the liquid phase material obtained from the bottom outlet of the benzene fractionation tower 5 to obtain toluene. The inlet of the xylene fractionation tower 7 is connected to the bottom outlet of the toluene fractionation tower 6, and is used to perform a third fractionation on the liquid phase material obtained from the bottom outlet of the toluene fractionation tower 6 to obtain xylene.

[0058] The system provided by the present invention can realize the method of the first aspect mentioned above, converting non-aromatic fractions in the C6-C7 fraction of reformed oil into alkylbenzenes (mainly toluene and xylene), and the benzene conversion rate and the selectivity of alkylbenzenes (mainly toluene and xylene) are high.

[0059] The present invention will be described in detail below through embodiments.

[0060] Example 1

[0061] Adopting such Figure 1 The system shown depentanizer oil (composition as shown in Table 1) is fractionated in depentanizer 1, and the bottom stream is fractionated in deheptanizer 2. The top product of deheptanizer 2 (composition as shown in Table 2) and benzene mixture F1 (composition as shown in Table 3) then enter alkylation reactor 3. The alkylation reaction conditions are: hydrogen-to-oil volume ratio of 1000:1, temperature of 500℃, hydrogen partial pressure of 3 MPa, and mass hourly space velocity of 7 h⁻¹. -1 ;

[0062] Preparation of alkylation catalyst: Hydrogen-form ZSM-5 (SAR = 37.25) was mixed with alumina and calcined at 550°C for 2 hours, and then impregnated with 0.2 wt% platinum solution to obtain alkylation catalyst. The proportion of hydrogen-form ZSM-5 molecular sieve in the catalyst was 81.35 wt%. The catalyst composition is shown in Table 4.

[0063] A gas-liquid separator 4 is installed at the outlet of the alkylation reactor 3. The alkylation reaction product, after cooling, is fed into the gas-liquid separator 4 to separate gaseous and liquid phases. The liquid phase enters the benzene fractionation tower 5 for first fractionation (distillation range 65-85℃), from which benzene is separated and returned to the alkylation reactor 3. The bottom material of the benzene fractionation tower 5 then enters the toluene fractionation tower 6 (distillation conditions 85-105℃), from which toluene is separated. The bottom material of the toluene fractionation tower 6 then enters the xylene fractionation tower 7 (distillation range 105-145℃), from which xylene is separated.

[0064] After the device has been running stably for 48 hours, the gaseous materials (C1-C3 components, C...) were tested separately. 4+ The reaction products (light hydrocarbons) and liquid products (benzene, toluene, xylene, and heavy aromatic components) were quantified and analyzed. The reaction products were classified as CH4, C2-C3 light hydrocarbons, C... 4+ Light hydrocarbons, benzene, toluene, ethylbenzene, xylene, and heavy aromatics are listed in Table 5.

[0065] Example 2

[0066] The method is the same as in Example 1, except that the top material of the deheptane tower 2 (composition as shown in Table 2) and the benzene mixture F2 (composition as shown in Table 3) enter the alkylation reactor 3. Otherwise, they are the same as in Example 1.

[0067] Example 3

[0068] The method is the same as in Example 1, except that the top material of the deheptane tower 2 (composition as shown in Table 2) and the benzene mixture F3 (composition as shown in Table 3) enter the alkylation reactor 3, and the rest is the same as in Example 1.

[0069] Example 4

[0070] The method is the same as in Example 1, except that the top material of the deheptane tower 2 (composition as shown in Table 2) and the benzene mixture F4 (composition as shown in Table 3) enter the alkylation reactor 3, and the rest is the same as in Example 1.

[0071] Example 5

[0072] The method is the same as in Example 1, except that after impregnation with the platinum metal solution, the metal functional additive lanthanum is further impregnated; otherwise, it is the same as in Example 1.

[0073] Example 6

[0074] The method is the same as in Example 1, except that the proportion of hydrogen-form ZSM-5 molecular sieve in the catalyst is 85.35 wt%, and the rest is the same as in Example 1.

[0075] Example 7

[0076] The method is the same as in Example 1, except that the proportion of hydrogen-form ZSM-5 molecular sieve in the catalyst is 90.35 wt%, and the rest is the same as in Example 1.

[0077] Example 8

[0078] The method is the same as in Example 1, except that 5% Beta of the second zeolite component is added to the catalyst.

[0079] Example 9

[0080] The method is the same as in Example 1, except that no metal impregnation is added.

[0081] Example 10

[0082] The method was the same as in Example 1, except that the alkylation reaction temperature was 550°C.

[0083] Example 11

[0084] The method is the same as in Example 1, except that the hydrogen form ZSM-5 (SAR=293) is selected.

[0085] Example 12

[0086] The method is the same as in Example 1, except that the catalyst impregnation solution is a 2wt% platinum metal solution.

[0087] Example 13

[0088] The method was the same as in Example 1, except that the alkylation reaction temperature was 400°C.

[0089] Example 14

[0090] Following the method in Example 1, the alkylation reaction weight hourly space velocity was 12 h⁻¹. -1 The rest is the same as in Example 1.

[0091] Table 1. PIONA Analysis of Reformed Oil (wt%)

[0092]

[0093] Table 2 Composition of the overhead stream from the heptane removal column (wt%)

[0094]

[0095]

[0096] Table 3. Composition of the mixture (by weight %)

[0097]

[0098] Table 4 Composition of Alkylation Catalysts

[0099] catalyst composition Example 1 C1 <![CDATA[0.2wt%Pt / 81.35wt%ZSM-5(SAR 37.25) / 18.15wt%Al2O3]]> Example 2 C2 <![CDATA[0.2wt%Pt / 81.35wt%ZSM-5 / 18.15wt%Al2O3]]> Example 3 C3 <![CDATA[0.2wt%Pt / 81.35wt%ZSM-5 / 18.15wt%Al2O3]]> Example 4 C4 <![CDATA[0.2wt%Pt / 81.35wt%ZSM-5 / 18.15wt%Al2O3]]> Example 5 C5 <![CDATA[0.2wt%Pt / 0.05wt%La / 81.35wt%ZSM-5 / 18.15wt%Al2O3]]> Example 6 C6 <![CDATA[0.5wt%Pt / 85.35wt%ZSM-5 / 14.15wt%Al2O3]]> Example 7 C7 <![CDATA[0.5wt%Pt / 90.35wt%ZSM-5 / 9.15wt%Al2O3]]> Example 8 C8 <![CDATA[80.35wt%ZSM-5 / 5%wt Beta / -14.15wt%Al2O3]]> Example 9 C9 <![CDATA[81.35wt%ZSM-5 / 18.15wt%Al2O3]]> Example 10 C10 <![CDATA[0.2wt%Pt / 81.35wt%ZSM-5 / 18.15wt%Al2O3]]> Example 11 C11 <![CDATA[0.2wt%Pt / 81.35wt%ZSM-5(SAR 293) / 18.15wt%Al2O3]]> Example 12 C12 <![CDATA[2wt%Pt / 81.35wt%ZSM-5 / 18.15wt%Al2O3]]> Example 13 C13 <![CDATA[0.2wt%Pt / 81.35wt%ZSM-5(SAR 37.25) / 18.15wt%Al2O3]]> Example 14 C14 <![CDATA[0.2wt%Pt / 81.35wt%ZSM-5(SAR 37.25) / 18.15wt%Al2O3]]>

[0100] Table 5. Yields (%) of products in the examples and comparative examples.

[0101]

[0102]

[0103] As can be seen from the experimental results in Table 5, the specific method of this invention has a lower methane yield and a higher yield of toluene and xylene, resulting in high added value. Furthermore, all non-aromatic hydrocarbons in the C6-C7 fraction are converted into small-molecule C1-C3 light hydrocarbons, and in actual operation, no extraction operation is required to separate aromatic and non-aromatic hydrocarbons.

[0104] Comparative examples and Examples 11-12 show that selecting an alkylation catalyst with a low silica-to-alumina ratio MFI zeolite molecular sieve and impregnated with a small amount of metal is more conducive to the conversion of non-aromatic hydrocarbons in reformed oil and the generation of toluene and xylene.

[0105] Comparing Examples 1 and 5, it is evident that the preferred alkylation catalyst scheme of this invention, with the introduction of an appropriate amount of metal functional additives, reduces the acid strength and acidity of the alkylation catalyst, inhibits the secondary cracking of non-aromatic hydrocarbons, and thus reduces the methane yield. Comparing Examples 1 and 8, it is evident that the preferred alkylation catalyst scheme of this invention, with the addition of a small amount of second zeolite molecular sieve components, is beneficial in inhibiting hydrogen transfer and reducing the formation of heavy aromatic hydrocarbons in the side reaction.

[0106] By comparing the examples and Examples 13-14, it can be seen that the preferred alkylation reaction conditions of the present invention are more conducive to the conversion of non-aromatic hydrocarbons and the generation of toluene and xylene.

[0107] As can be seen from the comparison of Examples 1-4, the scheme using the preferred alkylation reaction conditions of the present invention, under feed conditions with higher benzene content, can further reduce methane generation and improve carbon atom utilization. As can be seen from the comparison of Examples 1 and 10, the scheme using the preferred alkylation reaction conditions of the present invention, by selecting an appropriate temperature, can save energy and reduce methane generation on the one hand.

[0108] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for improving the yield of toluene and xylene in reforming products, the method comprising: Under alkylation reaction conditions, in the presence of an alkylation catalyst, the C6-C7 fraction of the reformate is contacted with benzene and hydrogen to carry out an alkylation reaction; wherein the alkylation catalyst includes MFI type zeolite, binder, and metal components, optionally metal functional additive components; The method further includes: first cutting the reformed oil to obtain C6-C7 fractions, and then carrying out the alkylation reaction; In the stream for the alkylation reaction, benzene accounts for 80-90% by weight. The silicon-aluminum molar ratio of the MFI type zeolite is 25-200; The metal component is selected from at least one of Pt, Mo, Ni, Ga and Zn; The metal functional additive component is selected from at least one of La, Y and Ag; Based on the total amount of the alkylation catalyst, the zeolite content is 60-90% by weight, the binder content is 10-40% by weight, the metal component content is 0-0.5% by weight, and the metal functional additive component content is 0-0.1% by weight. The content of the metal component is not 0; The alkylation reaction conditions include: a temperature of 450-550℃, a hydrogen partial pressure of 1-6 MPa, and a weight hourly space velocity of 1-10 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500-4000.

2. The method according to claim 1, wherein, The silicon-aluminum molar ratio of the MFI type zeolite is 25-100.

3. The method according to claim 1, wherein, The MFI type zeolite is selected from ZSM-5.

4. The method according to any one of claims 1-3, wherein, The alkylation catalyst also includes a second zeolite, which is selected from β molecular sieves and / or MCM22 molecular sieves.

5. The method according to claim 4, wherein, In the alkylation catalyst, MFI type zeolite accounts for ≥60% of the total zeolite content by weight.

6. The method according to claim 5, wherein, In the alkylation catalyst, MFI type zeolite accounts for ≥80% of the total zeolite weight.

7. The method according to claim 1, wherein, The binder is aluminum oxide and / or silicon oxide.

8. The method according to any one of claims 1-3, wherein, The alkylation reaction conditions include: a temperature of 480-520℃, a hydrogen partial pressure of 2.0-4.0 MPa, and a weight hourly space velocity of 4-8 h⁻¹. -1 The hydrogen-to-oil volume ratio is 1000-2000.

9. The method according to any one of claims 1-3, wherein, The reformed oil contains n-alkanes, isoalkanes, aromatics, and small amounts of cycloalkanes and olefins.

10. The method according to any one of claims 1-3, wherein, The method also includes: cooling the aromatic product obtained from the alkylation reaction, and then performing gas-liquid separation to obtain gaseous and liquid phase materials.

11. The method according to claim 10, wherein, The method further includes: fractionating the liquid phase material to obtain benzene, toluene and xylene, and then recycling the benzene for alkylation reaction.

12. An apparatus for improving the yield of toluene and xylene from reforming as described in any one of claims 1-11, the apparatus comprising: A reforming reactor, a cutting unit, and an alkylation reactor connected in series; The apparatus also includes a benzene supply unit and a hydrogen supply unit connected to the alkylation reactor. The benzene supply unit supplies benzene to the alkylation reactor, and the hydrogen supply unit supplies hydrogen to the alkylation reactor.

13. The apparatus according to claim 12, wherein, The device does not include an aromatics extraction unit.

14. The apparatus according to claim 12 or 13, wherein, The apparatus also includes a gas-liquid separator connected to the alkylation reactor; the gas-liquid separator is used to separate the aromatic products obtained from the alkylation reaction into gaseous and liquid phase materials.

15. The apparatus according to claim 14, wherein, The device also includes a fractionation unit connected to the gas-liquid separator, which is used to fractionate the liquid phase material to obtain benzene, toluene and xylene.

16. The apparatus according to claim 12 or 13, wherein, The fractionation unit is connected to the alkylation reactor so that the benzene obtained from the fractionation unit is recycled back to the alkylation reactor.

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