A method for processing an aromatic raffinate oil

Abstract

The application discloses a processing method of aromatic raffinate oil. The method comprises the following steps: (1) contacting and reacting aromatic raffinate oil, hydrogen and a hydroconversion catalyst in a hydroconversion reaction zone, wherein the hydroconversion catalyst is a molecular sieve catalyst, and the molecular sieve is selected from any one of mordenite or ZSM-5 molecular sieve; (2) separating the hydroconversion reaction effluent obtained in the step (1) to obtain a hydrogen-rich gas and a liquid phase stream; and (3) separating the liquid phase stream obtained in the step (2) to obtain a liquid phase product and a gas phase product. The method can effectively convert isomeric alkanes in the aromatic raffinate oil into n-alkanes, and improve the ethylene raw material quality.

Description

Technical Field

[0001] This invention belongs to the field of hydrocarbon oil hydroconversion, specifically relating to a hydroconversion method for producing high-quality ethylene feedstock using aromatic raffinate as raw material. Background Technology

[0002] Aromatic raffinate is rich in saturated hydrocarbons and is typically used as a feedstock for ethylene production. Raffinate obtained from cracked gasoline after aromatic extraction has a high cycloalkanes content, while raffinate obtained from reforming oil after aromatic extraction has a high isoalkanes content. Neither cycloalkanes nor isoalkanes are ideal components for ethylene plants. Converting the cycloalkanes and isoalkanes in the raffinate to n-alkanes can significantly improve the yields of ethylene and terpenes in ethylene plants, thereby greatly enhancing the overall economic efficiency of the plant.

[0003] CN115612524A discloses a method for increasing the concentration of n-chain alkanes in a light naphtha feed stream. The method includes separating the naphtha feed stream into a stream rich in n-chain alkanes and a stream rich in non-n-chain alkanes. An isomerization feed stream is obtained from the non-n-chain alkanes stream and isomerized on an isomerization catalyst to convert the non-n-chain alkanes into n-chain alkanes and generate an isomerized effluent. Optionally, the isomerized effluent can be separated into a propane stream and a C4 stream in a single column. + Hydrocarbon feedstock. C4 + The hydrocarbon feed stream can be recycled to the step of separating the naphtha feed stream.

[0004] CN116023214A discloses a method and system for producing n-alkanes. The method involves contacting isobutane feedstock with an isobutane conversion catalyst in an isobutane conversion unit to carry out an isobutane conversion reaction. The isobutane conversion catalyst has high catalytic activity, is chlorine-free, safe and non-toxic, and reduces corrosion and wear on equipment. The resulting reaction product containing n-alkanes is introduced into a membrane separation unit for membrane separation treatment. The membrane separation element, including a molecular sieve membrane, enables efficient separation of n-alkanes and isoalkanes. The separation efficiency is high and the method is simple and easy to implement. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a processing method for aromatic raffinate oil. This method uses aromatic raffinate oil as raw material and can effectively convert isoparaffins in the aromatic raffinate oil into n-paraffins, thereby improving the quality of ethylene feedstock.

[0006] This invention provides a method for processing aromatic raffinate oil, the method comprising:

[0007] (1) Aromatic raffinate oil, hydrogen and hydroconversion catalyst are reacted in the hydroconversion reaction zone, wherein the hydroconversion catalyst is a molecular sieve catalyst, wherein the molecular sieve is selected from either mordenite or ZSM-5 molecular sieve.

[0008] (2) The effluent from the hydrogenation conversion reaction obtained in step (1) is separated to obtain hydrogen-rich gas and liquid stream;

[0009] (3) The liquid phase stream obtained in step (2) is separated to obtain liquid phase product and gas phase product.

[0010] According to the present invention, in step (2), the hydrogen-rich gas obtained by separation can be used as recycled hydrogen.

[0011] According to the present invention, in step (3), the separated gaseous products include ethane, propane, n-butane and isobutane, and the liquid products include C5 and C52. + Components.

[0012] Furthermore, the gaseous products obtained in step (2) are directly fed into a steam cracking ethylene production unit to obtain the main target products ethylene, propylene, and butadiene. The yield of these trienes is the mass percentage of the ethylene, propylene, and butadiene production relative to the gaseous product feed. The operating conditions for the steam cracking ethylene production are: reaction temperature 860–890°C, reaction pressure 0.1–0.3 MPa, and water-to-oil mass ratio 0.2–0.6.

[0013] According to the present invention, the aromatic raffinate oil refers to the raffinate oil obtained by aromatic extraction from reforming oil. The initial boiling point of the aromatic raffinate oil is 40℃~60℃, preferably 50℃~60℃; the final boiling point is 100℃~140℃, preferably 110℃~120℃.

[0014] According to the present invention, the aromatic raffinate contains 15 wt% to 45 wt% of C7-C8 isoalkanes, 20 wt% to 45 wt% of C6 isoalkanes, preferably 25 wt% to 40 wt%; <5% of C5 isoalkanes, 10 wt% to 40 wt% of C5-C8 n-alkanes, preferably 20 wt% to 30 wt%; and 3 wt% to 15 wt% of C6-C8 cyclic hydrocarbons, preferably 5 wt% to 12 wt%; based on a total weight of 100 wt% of the aromatic raffinate.

[0015] According to the present invention, the SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 10-50, and the specific surface area is 300-500 m². 2 The pore volume is 0.2–0.4 mL / g. The SiO2 / Al2O3 molar ratio of the mordenite is 10–50, and the specific surface area is 300–600 m² / g. 2 / g, with a pore volume of 0.15~0.35mL / g.

[0016] Furthermore, in the hydroconversion catalyst, the total content of molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%, based on the weight of the catalyst.

[0017] According to the present invention, the hydroconversion catalyst includes a binder, preferably alumina. Further, in the hydroconversion catalyst, the binder content (based on the weight of the catalyst) is 5 wt% to 65 wt%, preferably 10 wt% to 35 wt% as an oxide.

[0018] According to the present invention, the hydroconversion catalyst comprises an active metal component, which is selected from one or more Group VIB metals and Group VIII non-noble metals of the periodic table. The Group VIB metals are preferably selected from one or more of molybdenum and tungsten, and the Group VIII non-noble metals are preferably selected from one or more of cobalt and nickel. Further, based on the weight of the catalyst, the content of the Group VIB metals (calculated as oxides) is 5 wt% to 30 wt%, preferably 10 wt% to 20 wt%; and the content of the Group VIII non-noble metals (calculated as oxides) is 0.5 wt% to 15 wt%, preferably 3 wt% to 10 wt%.

[0019] According to the present invention, the specific surface area of ​​the hydroconversion catalyst is 200-400 m². 2 / g, with a pore volume of 0.15~0.40mL / g.

[0020] According to the present invention, the preparation method of the hydrogenation conversion catalyst can be carried out according to conventional methods in the art. The preparation method includes the preparation of a support and the loading of an active metal component, wherein the preparation process of the support is as follows: molecular sieves and a binder are mechanically mixed, shaped, and then dried and calcined to form a catalyst support. The drying and calcination of the support can be carried out under conventional conditions. The drying conditions are: drying at 100℃~150℃ for 1~12 hours. The calcination conditions are: calcination at 450℃~550℃ for 2.5~6.0 hours.

[0021] According to the present invention, in the preparation method of the hydroconversion catalyst, the method of loading the active metal component is a conventional method, such as kneading, impregnation, etc., with impregnation being preferred. The impregnation method can be a saturated impregnation method, an excess impregnation method, or a complex impregnation method, that is, impregnating the catalyst support with a solution containing the desired active metal component, followed by drying and calcination to obtain the hydroconversion catalyst. The drying conditions are: drying at 100℃~150℃ for 1~12 hours. The calcination conditions are: calcination at 450℃~550℃ for 2.5~6.0 hours.

[0022] According to the present invention, preferably, the hydroconversion reaction zone is packed with at least two hydroconversion catalyst beds, more preferably two to three hydroconversion catalyst beds. Further, along the flow direction, the active metal content of the hydroconversion catalyst packed in adjacent catalyst beds decreases sequentially. Preferably, in the hydroconversion catalysts packed in adjacent catalyst beds, the active metal content in the downstream catalyst, calculated as oxides, is 1 to 20 percentage points lower than the active metal content in the upstream catalyst, more preferably 5 to 10 percentage points lower. Preferably, in the hydroconversion catalysts packed in adjacent catalyst beds, the mass content of Group VIB metals in the downstream catalyst, calculated as oxides, is 1 to 15 percentage points lower than the mass content of Group VIB metals in the upstream catalyst, and the mass content of Group VIII non-precious metals in the downstream catalyst, calculated as oxides, is 0 to 2 percentage points lower than the mass content of Group VIII non-precious metals in the upstream catalyst, calculated as oxides. Furthermore, along the flow direction, the ratio of the upstream catalyst loading volume to the downstream catalyst loading volume in two adjacent catalyst beds is 1:3 to 3:1, preferably 1:2 to 2:1.

[0023] According to the present invention, a fixed-bed reactor is used for the hydrogenation conversion reaction.

[0024] Compared with the prior art, the present invention has the following beneficial technical effects:

[0025] (1) For hydrocracking reactions, the smaller the molecules, the more difficult it is for cracking reactions to occur, especially for small molecule hydrocarbons such as C6-C8. It is necessary to ensure that the reactants have a certain residence time in the catalyst channels. At the same time, when the goal is to produce n-alkanes, the molecular sieve of the catalyst needs to have a straight channel structure, which is also more conducive to the formation of n-alkanes. Therefore, when processing feedstocks rich in C6-C8 isoalkanes, it is necessary to select catalysts with special channel structures. The inventors have found that molecular sieves with shape selectivity have very good reaction performance for reactions with small molecular diameters (including n-alkanes and short-chain branched isoalkanes), and can effectively convert C6-C8 isoalkanes. Hydrogenation of hydrocarbon feedstocks containing C6-C8 isoalkanes can significantly improve the yield of trienes in steam cracking to ethylene plants and improve the economic efficiency of ethylene plants. Preferably, by loading a hydrogenation conversion catalyst bed with different active metal contents, and with the active metal contents gradually decreasing along the flow direction, the present invention can further significantly improve the yield of n-alkanes in the product by matching the dehydrogenation performance of the catalyst.

[0026] (2) The processing capacity of the ethylene plant is based on the ethylene yield. That is, the higher the ethylene yield, the less raw material the ethylene plant consumes. The raw material cost accounts for more than 60% of the processing cost of the ethylene plant. Therefore, the method of the present invention can significantly reduce the processing cost of the ethylene plant by increasing the ethylene yield. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the process flow according to an embodiment of the present invention;

[0028] Explanation of key figure labels:

[0029] Figure 1 This is a schematic diagram of a process flow of the present invention.

[0030] exist Figure 1 In the middle, 1-aromatic raffinate, 2-hydrogen, 3-hydrogenation reaction zone, 4-hydrogenation reaction zone effluent, 5-high pressure separator, 6-hydrogen-rich gaseous stream, 7-liquid stream, 8-fractionation tower, 9-gaseous product, 10-liquid product. Detailed Implementation

[0031] The following examples further illustrate the function and effect of the present invention, but the following examples do not constitute a limitation on the method of the present invention.

[0032] Unless otherwise specified, all percentages in this invention refer to mass fractions.

[0033] The method of the present invention, such as Figure 1 As shown, aromatic raffinate 1 is mixed with hydrogen 2 and enters the hydroconversion reaction zone 3. The effluent 4 from the hydroconversion reaction zone enters the high-pressure separator 5. The separated gaseous stream 6 is recycled, and the liquid stream 7 enters the fractionation tower to separate gaseous product 9 and liquid product 10. Gaseous product 9 is used as ethylene feedstock.

[0034] In this invention, the yield of n-alkane = n-alkane yield in gaseous products / fresh feed amount × 100%, by mass.

[0035] In this invention, the hydroconversion catalyst is prepared by conventional active metal saturation impregnation method, and the physicochemical properties of the obtained catalyst are shown in Table 1.

[0036] In this invention, the ZSM-5 molecular sieve used in the catalyst has the following properties: a SiO2 / Al2O3 molar ratio of 30 and a specific surface area of ​​400 m². 2 / g, pore volume 0.25cm 3 / g; The properties of the mordenite zeolite used in the catalyst are as follows: SiO2 / Al2O3 molar ratio is 20, and specific surface area is 450m². 2 / g, pore volume 0.25cm3 / g.

[0037] The main properties of the aromatic raffinate used in each example of this invention are shown in Table 2.

[0038] In this invention, the n-alkanes in Table 3 include ethane, propane, and n-butane.

[0039] Example 1

[0040] The conversion method for aromatic raffinate oil adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0041] (1) Aromatic raffinate is mixed with hydrogen and passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-1.

[0042] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, and the hydrogen-rich gas and liquid stream are separated, wherein the hydrogen-rich gas is used as recycled hydrogen.

[0043] (3) The liquid phase stream from step (2) is separated to obtain a gaseous product which is used as a raw material for ethylene.

[0044] The process conditions and hydrogenation effect in this example are shown in Table 3.

[0045] Example 2

[0046] The conversion method for aromatic raffinate oil adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0047] (1) Aromatic raffinate is mixed with hydrogen and passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-3.

[0048] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, and the hydrogen-rich gas and liquid stream are separated, wherein the hydrogen-rich gas is used as recycled hydrogen.

[0049] (3) The liquid phase stream from step (2) is separated to obtain a gaseous product which is used as a raw material for ethylene.

[0050] The process conditions and hydrogenation effect in this example are shown in Table 3.

[0051] Example 3

[0052] The conversion method for aromatic raffinate oil adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0053] (1) Aromatic raffinate is mixed with hydrogen and then passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-2 / Cat-1;

[0054] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, and the hydrogen-rich gas and liquid stream are separated, wherein the hydrogen-rich gas is used as recycled hydrogen.

[0055] (3) The liquid phase stream from step (2) is separated to obtain a gaseous product which is used as a raw material for ethylene.

[0056] The process conditions and hydrogenation effect in this example are shown in Table 3.

[0057] Example 4

[0058] The conversion method for aromatic raffinate oil adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0059] (1) Aromatic raffinate is mixed with hydrogen and then passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-3 / Cat-4.

[0060] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, and the hydrogen-rich gas and liquid stream are separated, wherein the hydrogen-rich gas is used as recycled hydrogen.

[0061] (3) The liquid phase stream from step (2) is separated to obtain a gaseous product which is used as a raw material for ethylene.

[0062] The process conditions and hydrogenation effect in this example are shown in Table 3.

[0063] Comparative Example 1

[0064] The difference from Example 1 is that the hydrogenation conversion reaction zone is filled with catalyst Cat-1 / Cat-2.

[0065] The process conditions and hydrogenation effect in this example are shown in Table 4.

[0066] Comparative Example 2

[0067] The difference from Example 2 is that the hydrogenation conversion reaction zone is filled with catalyst Cat-4 / Cat-3.

[0068] The process conditions and hydrogenation effect in this example are shown in Table 4.

[0069] Table 1. Composition and physicochemical properties of hydroconversion catalysts

[0070]

[0071] Table 2 Composition and properties of aromatic raffinate

[0072] Hydrocarbon composition <![CDATA[n-Paraffin in C5, %]]> 3.89 <![CDATA[C5 Isoparaffin, %]]> 2.02 <![CDATA[n - hexane in C6, %]]> 13.03 <![CDATA[C6 Isoparaffin, %]]> 33.10 <![CDATA[n - C7 - C8 paraffin, %]]> 7.43 <![CDATA[C7 - C8 Isoparaffin, %]]> 32.41 <![CDATA[C6-C8 cycloalkane, %]]> 7.99 Total aromatics, % 0.13 Initial boiling point, ℃ 55 Final boiling point, ℃ 114

[0073] Table 3. Process conditions and conversion results for each embodiment and comparative example.

[0074]

[0075]

[0076] Table 4. Process conditions and conversion results for each comparative example.

[0077] serial number Comparative Example 1 Comparative Example 2 Hydrogenation conversion reaction zone catalyst Cat-1 / Cat-2 Cat-4 / C at-3 Volume ratio of each catalyst 1：1 1：1 Reaction temperature / °C 380 380 Reaction pressure / MPa 5.0 5.0 Hydrogen-to-oil volume ratio 500 400 <![CDATA[Liquid hourly space velocity / h -1 > 1.0 1.0 n-Alkane yield, % 65 64 Steam cracking to olefins Reaction temperature / °C 890 890 Reaction pressure / MPa 0.25 0.25 Water-oil mass ratio 0.3 0.3 Ethylene yield, wt% 37.8 37.4 Propylene yield, wt% 14.5 14.6 Butadiene yield, wt% 3.1 3.1

[0078] The specific 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 combining the 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 processing aromatic raffinate oil, the method comprising: (1) Aromatic raffinate oil, hydrogen and hydroconversion catalyst are reacted in the hydroconversion reaction zone, wherein the hydroconversion catalyst is a molecular sieve catalyst, wherein the molecular sieve is selected from either mordenite or ZSM-5 molecular sieve. (2) The effluent from the hydrogenation conversion reaction obtained in step (1) is separated to obtain hydrogen-rich gas and liquid stream; (3) The liquid phase stream obtained in step (2) is separated to obtain liquid phase product and gas phase product.

2. The processing method according to claim 1, characterized in that: In step (3), the separated gaseous products include ethane, propane, n-butane, and isobutane, and the liquid products include C5 and C52. + Components.

3. The processing method according to claim 1, characterized in that: The initial boiling point of the aromatic raffinate oil is 40℃~60℃, preferably 50℃~60℃; the final boiling point is 100℃~140℃, preferably 110℃~120℃.

4. The processing method according to claim 1, characterized in that: The aromatic raffinate contains 15 wt% to 45 wt% of C7-C8 isoalkanes and 20 wt% to 45 wt% of C6 isoalkanes, preferably 25 wt% to 40 wt%, based on a total weight of 100 wt% of the aromatic raffinate.

5. The processing method according to claim 1, characterized in that: The ZSM-5 molecular sieve has a SiO2 / Al2O3 molar ratio of 10–50 and a specific surface area of ​​300–500 m². 2 / g, with a pore volume of 0.2–0.4 mL / g; and / or, the SiO2 / Al2O3 molar ratio of the mordenite is 10–50, and the specific surface area is 300–600 m² / g. 2 / g, with a pore volume of 0.15~0.35mL / g.

6. The processing method according to claim 1, characterized in that: The hydroconversion catalyst includes a binder, preferably alumina; Preferably, in the hydroconversion catalyst, the binder content, calculated as oxide, is 5 wt% to 65 wt% based on the weight of the catalyst, and more preferably 10 wt% to 35 wt%.

7. The processing method according to claim 1, characterized in that: The hydroconversion catalyst includes an active metal component, which is selected from one or more metals of Group VIB and Group VIII of the periodic table. The Group VIB metal is preferably selected from one or more of molybdenum and tungsten, and the Group VIII non-precious metal is preferably selected from one or more of cobalt and nickel. Preferably, in the hydroconversion catalyst, based on the weight of the catalyst, the content of Group VIB metals as oxides is 5 wt% to 30 wt%, preferably 10 wt% to 20 wt%; and the content of Group VIII non-precious metals as oxides is 0.5 wt% to 15 wt%, preferably 3 wt% to 10 wt%.

8. The processing method according to claim 1, characterized in that: In the hydrogenation conversion catalyst, the total content of molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%, based on the weight of the catalyst.

9. The processing method according to claim 1, characterized in that: The hydroconversion reaction zone is filled with at least two hydroconversion catalyst beds.

10. The processing method according to claim 9, characterized in that: Along the flow direction, the active metal content of the hydroconversion catalyst packed in two adjacent catalyst beds decreases sequentially. Preferably, along the flow direction, in the hydroconversion catalysts packed in two adjacent catalyst beds, the active metal content in the downstream catalyst, calculated as oxides, is 1 to 20 percentage points lower than the active metal content in the upstream catalyst, calculated as oxides, and more preferably 5 to 10 percentage points lower.

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