A method for producing a chemical feedstock

Abstract

The application discloses a method for producing chemical raw materials. The method comprises the following steps: mixing hydrocracking light naphtha and hydrogen, and sequentially passing through a first hydroconversion reaction zone and a second hydroconversion reaction zone; the reaction effluent enters a separation system to obtain hydrogen-rich gas and a hydroconversion product. The first hydroconversion reaction zone is filled with a hydroconversion catalyst containing ZSM-5 molecular sieve, and at least two hydroconversion catalyst beds are filled, and the active metal content of the hydroconversion catalyst decreases in the flow direction. The second hydroconversion reaction zone is filled with a hydroconversion catalyst containing ZSM-35 molecular sieve. The method can effectively convert isomeric alkanes in the hydrocracking light naphtha into normal alkanes, and improve the quality of ethylene raw materials.

Description

Technical Field

[0001] This invention belongs to the field of hydrocarbon oil hydroconversion, specifically relating to a method for producing chemical feedstocks using hydrocracking light naphtha as raw material. Background Technology

[0002] Hydrocracking technology is characterized by strong adaptability to feedstocks, high flexibility in production operations and product solutions, and high product quality. It can directly convert various heavy and low-quality feedstocks into high-quality jet fuel, diesel, lubricating oil base materials, and chemical naphtha and tail oil steam cracking feedstocks for ethylene production, which are in high demand in the market. It has become one of the most important hydrocarbon oil deep processing technologies in modern oil refining and petrochemical industries.

[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.

[0005] The above methods can all convert small molecule isoalkanes into n-alkanes, but the energy required for the conversion of hydrocarbons with different molecular structures is different, and it is difficult to effectively guarantee the yield of the target product by using a single conversion process. Summary of the Invention

[0006] To address the problems existing in the prior art, the purpose of this invention is to provide a method for producing chemical raw materials. This method uses hydrocracking light naphtha as raw material and can effectively convert isoparaffins in hydrocracking light naphtha into n-paraffins, thereby improving the quality of ethylene feedstock.

[0007] This invention provides a method for producing chemical raw materials, the method comprising:

[0008] (1) Hydrocracked light naphtha and hydrogen are mixed and passed sequentially through the first hydroconversion reaction zone and the second hydroconversion reaction zone for hydroconversion reaction. The first hydroconversion reaction zone is filled with a hydroconversion catalyst containing ZSM-5 molecular sieve, and at least two hydroconversion catalyst beds are filled. The active metal content of the hydroconversion catalyst decreases sequentially along the flow direction. The second hydroconversion reaction zone is filled with a hydroconversion catalyst containing ZSM-35 molecular sieve.

[0009] (2) The reaction effluent from step (1) enters the separation system and is separated to obtain hydrogen-rich gas and hydrogenation conversion products.

[0010] According to the present invention, the hydrogenation conversion products of step (2) include ethane, propane and n-butane, wherein the mass ratio of n-butane to isobutane is 40-60:60-40.

[0011] According to the present invention, a fixed-bed reactor is used for the hydrogenation conversion reaction.

[0012] According to the present invention, the hydroconversion reaction zones are sequentially divided into a first hydroconversion reaction zone and a second hydroconversion reaction zone along the material flow direction. That is, the material first reacts with the hydroconversion catalyst containing ZSM-5 molecular sieve, and then reacts with the hydroconversion catalyst containing ZSM-35 molecular sieve. The hydroconversion catalysts containing ZSM-5 and ZSM-35 molecular sieves can be graded and packed in one or more reactors along the material flow direction.

[0013] According to the present invention, the hydrocracked light naphtha refers to the fraction obtained by separating hydrocarbon oil after undergoing a hydrocracking reaction process. The initial boiling point of the hydrocracked light naphtha is 10°C to 30°C, preferably 15°C to 25°C; the final boiling point is 50°C to 100°C, preferably 55°C to 70°C.

[0014] According to the present invention, the content of C5-C6 isoalkanes in the hydrocracked light naphtha is 60wt% to 90wt%, preferably 70wt% to 80wt%; C7 + The hydrocarbon content is 0–10 wt%, preferably 0.5 wt%–5 wt%; the C5–C6 n-alkanes content is 10 wt%–30 wt%, preferably 15 wt%–25 wt%; C4 - The hydrocarbon content is 0-10 wt%, preferably 2 wt%-5 wt%; the cyclic hydrocarbon content is 0-10 wt%, preferably 2 wt%-5 wt%; and the total weight of the hydrocracked light naphtha is 100 wt%.

[0015] According to the present invention, preferably, the first hydroconversion reaction zone is packed with 2 to 3 hydroconversion catalyst beds. Further, 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.

[0016] According to the present invention, in the hydroconversion catalyst containing ZSM-5 molecular sieve, the SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 10-50, and the specific surface area is 300-500 m². 2 / g, with a pore volume of 0.2–0.4 mL / g.

[0017] Furthermore, in the ZSM-5 molecular sieve-containing hydroconversion catalyst, the content of ZSM-5 molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%, based on the weight of the catalyst.

[0018] According to the present invention, the hydroconversion catalyst containing ZSM-5 molecular sieve further includes a binder, preferably alumina. Further, in the hydroconversion catalyst containing ZSM-5 molecular sieve, the binder content (based on the weight of the catalyst) is 5 wt% to 65 wt%, preferably 10 wt% to 35 wt% (calculated as oxide), at a concentration of 10 wt% to 35 wt%.

[0019] According to the present invention, in the ZSM-5 molecular sieve-containing hydroconversion catalyst, the active metal component is selected from one or more of 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, in the ZSM-5 molecular sieve-containing hydroconversion catalyst, 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%.

[0020] According to the present invention, the specific surface area of ​​the hydroconversion catalyst containing ZSM-5 molecular sieve is 200-400 m². 2 / g, with a pore volume of 0.15~0.40mL / g.

[0021] According to the present invention, in the first hydroconversion reaction zone, along the stream flow direction, in the hydroconversion catalysts containing ZSM-5 molecular sieves packed in two adjacent catalyst beds, the active metal content in the downstream catalyst, calculated as oxides, is 1 to 25 percentage points lower than the active metal content in the upstream catalyst, calculated as oxides, preferably 5 to 15 percentage points lower. Further, in the first hydroconversion reaction zone, along the stream flow direction, in the hydroconversion catalysts containing ZSM-5 molecular sieves packed in two adjacent catalyst beds, the mass content of Group VIB metals in the downstream catalyst, calculated as oxides, is 1 to 23 percentage points lower than the mass content of Group VIB metals in the upstream catalyst, calculated as oxides (preferably 3 to 15 percentage points lower), and the mass content of Group VIII non-precious metals in the downstream catalyst, calculated as oxides, is 0 to 4 percentage points lower than the mass content of Group VIII non-precious metals in the upstream catalyst, calculated as oxides.

[0022] According to the present invention, the preparation method of the ZSM-5 molecular sieve-containing hydroconversion 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 support preparation process is as follows: ZSM-5 molecular sieve 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.

[0023] According to the present invention, in the preparation method of the ZSM-5 molecular sieve-containing hydroconversion catalyst, the method for 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.

[0024] According to the present invention, in the hydroconversion catalyst containing ZSM-35 molecular sieve, the SiO2 / Al2O3 molar ratio of the ZSM-35 molecular sieve is 10-50, and the specific surface area is 350-650 m². 2 / g, with a pore volume of 0.15~0.35mL / g.

[0025] Furthermore, in the hydroconversion catalyst containing ZSM-35 molecular sieve, the content of ZSM-35 molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%, based on the weight of the catalyst.

[0026] According to the present invention, the hydroconversion catalyst containing ZSM-35 molecular sieve further includes a binder, which is preferably alumina. Further, in the hydroconversion catalyst containing ZSM-35 molecular sieve, the binder content (based on the weight of the catalyst) is 5 wt% to 65 wt%, preferably 10 wt% to 35 wt% (calculated as oxides).

[0027] According to the present invention, in the hydroconversion catalyst containing ZSM-35 molecular sieve, the active metal component is selected from one or more of 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, in the hydroconversion catalyst containing ZSM-35 molecular sieve, 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%; 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%.

[0028] According to the present invention, the specific surface area of ​​the hydroconversion catalyst containing ZSM-35 molecular sieve is 200-400 m². 2 / g, with a pore volume of 0.20~0.40mL / g.

[0029] According to the present invention, the preparation method of the ZSM-35 molecular sieve-containing hydroconversion 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 support preparation process is as follows: ZSM-35 molecular sieve 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.

[0030] According to the present invention, in the preparation method of the hydroconversion catalyst containing ZSM-35 molecular sieve, the method for 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.

[0031] According to the present invention, the conditions for the first hydrogenation conversion reaction are as follows: reaction pressure is 0.5 MPa to 10.0 MPa, preferably 2.0 MPa to 5.0 MPa; reaction temperature is 250°C to 500°C, preferably 350°C to 450°C; and liquid hourly space velocity is 0.1 h⁻¹. -1 ~15.0h -1 0.5h is preferred -1 ~5.0h -1 The hydrogen-to-oil volume ratio is 10:1 to 2500:1, preferably 100:1 to 2000:1, and more preferably 100:1 to 1000:1. The second hydrogenation conversion reaction conditions are as follows: reaction pressure is 0.5 MPa to 10.0 MPa, preferably 2.0 MPa to 5.0 MPa; reaction temperature is 250℃ to 500℃, preferably 350℃ to 450℃; and liquid hourly space velocity is 0.1 h⁻¹. -1 ~15.0h -1 0.5h is preferred -1 ~5.0h -1 The hydrogen-to-oil volume ratio is 10:1 to 2500:1, preferably 100:1 to 2000:1, and even more preferably 100:1 to 1000:1. Furthermore, the conditions for the first hydrogenation reaction can be the same as or different from the conditions for the second hydrogenation reaction.

[0032] According to the present invention, in step (2), the reaction effluent from step (1) is fed into a separation system, and the separated hydrogen-rich gas can be used as recycled hydrogen.

[0033] According to the present invention, the hydrogenation conversion product obtained in step (2) is directly fed into a steam cracking ethylene production unit to obtain the main target products ethylene, propylene, and butadiene, wherein the yield of the trienes is the mass percentage of the ethylene, propylene, and butadiene production relative to the feed amount. 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.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] (1) Hydrocracked light naphtha mainly contains C5 and C6 isoalkanes. The inventors have found that as the molecular weight decreases, the difficulty of hydrogenation conversion of hydrocarbon molecules gradually increases. The inventors have also found that ZSM-5 and ZSM-35 molecular sieves with higher strong acid content are more prone to cracking reactions. For hydrocracked light naphtha containing C5 and C6 isoalkanes, ZSM-5 molecular sieves are first used for conversion. During the reaction, a certain amount of isobutane is generated. For these smaller isoalkanes, ZSM-35 molecular sieves with even smaller pore structures are then used for conversion, thereby increasing the reaction rate of the byproduct isobutane and improving the yield of n-alkanes. Further research by the inventors revealed that by first loading the first hydrogenation conversion reaction zone with hydrogenation conversion catalysts containing ZSM-5 molecular sieves of varying metal content, with the metal content gradually decreasing along the flow direction, the cracking reaction effect of isoparaffins can be significantly improved, increasing the yield of small molecule n-paraffins. Then, by loading the second hydrogenation conversion reaction zone with a hydrogenation conversion catalyst containing ZSM-35 molecular sieves, isobutane can be further converted, further increasing the yield of small molecule alkanes in the product.

[0036] (2) The hydrogenation conversion process of the present invention is simple, with low equipment investment and operating costs. The content of n-alkane in the hydrogenation conversion product can reach more than 90%, which can be directly used as a raw material for steam cracking to produce olefins, thereby improving the ethylene yield and total yield of trienes in the ethylene plant. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the process flow according to an embodiment of the present invention;

[0038] Explanation of key figure labels:

[0039] 1- Hydrocracked light naphtha, 2- Hydrogen, 3- First hydroconversion reaction zone, 4- Effluent from the first hydroconversion reaction zone, 5- Second hydroconversion reaction zone, 6- Effluent from the second hydroconversion reaction zone, 7- Separation system, 8- Hydrogen-rich gas, 9- Hydroconversion product. Detailed Implementation

[0040] 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.

[0041] Unless otherwise specified, all percentages in this invention refer to mass fractions.

[0042] The method of the present invention, such as Figure 1As shown, the process includes: hydrocracking light naphtha 1 and hydrogen 2 are mixed and fed into the first hydroconversion reaction zone 3 for hydroconversion reaction; the hydroconversion reaction effluent 4 is fed into the second hydroconversion reaction zone 5 for hydroconversion reaction; the hydroconversion reaction effluent 6 is fed into the separation system 7; the separated hydrogen-rich gas 8 is recycled; and the hydroconversion product 9 is directly used as feedstock for the steam cracking ethylene production unit.

[0043] In this invention, the yield of n-alkane = n-alkane yield in hydrogenation conversion products / fresh feed amount × 100%, by mass.

[0044] In this invention, the hydroconversion catalysts containing ZSM-5 molecular sieves are designated as Cat-A followed by a number, such as Cat-A1, Cat-A2, Cat-A3, and Cat-A4. The hydroconversion catalysts containing ZSM-35 molecular sieves are designated as Cat-B followed by a number, such as Cat-B1, Cat-B2, Cat-B3, and Cat-B4. The hydroconversion catalysts were prepared using a conventional active metal saturation impregnation method, and the physicochemical properties of the obtained catalysts are shown in Tables 1-3.

[0045] In this invention, the properties of the ZSM-5 molecular sieve used in Cat-A are as follows: SiO2 / Al2O3 molar ratio is 30, and specific surface area is 400 m². 2 / g, pore volume 0.25cm 3 / g; The properties of ZSM-35 used in Cat-B are as follows: SiO2 / Al2O3 molar ratio is 15, specific surface area is 500m² / g; 2 / g, pore volume 0.22cm 3 / g; The SiO2 / Al2O3 molar ratio of the Beta molecular sieve used in Cat-C is 30, and the specific surface area is 350m². 2 / g, pore volume is 0.3mL / g.

[0046] The main properties of the hydrocracked light naphtha used in each example of this invention are shown in Table 4.

[0047] In this invention, the n-alkanes in Tables 5-6 include ethane, propane, and n-butane.

[0048] Example 1

[0049] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0050] (1) Hydrocracked light naphtha is mixed with hydrogen and passed sequentially through the first hydroconversion reaction zone and the second hydroconversion reaction zone for hydroconversion reaction; the first hydroconversion reaction zone is loaded with catalysts Cat-A2 and Cat-A3 sequentially along the flow direction; the second hydroconversion reaction zone is loaded with Cat-B1;

[0051] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained by separation is used as recycled hydrogen, and the hydrogenation conversion product is used directly as ethylene feedstock. The hydrogenation conversion product includes ethane, propane and n-butane, and the mass ratio of n-butane to isobutane is 1:1.

[0052] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0053] Example 2

[0054] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0055] (1) Hydrocracked light naphtha is mixed with hydrogen and passed sequentially through the first hydroconversion reaction zone and the second hydroconversion reaction zone for hydroconversion reaction; the first hydroconversion reaction zone is loaded with catalysts Cat-A1, Cat-A2 and Cat-A3 sequentially along the flow direction and the second hydroconversion reaction zone is loaded with Cat-B2;

[0056] (2) The effluent from the hydrogenation reaction in step (1) enters the separation system. The hydrogen-rich gas obtained by separation is used as recycled hydrogen, and the hydrogenation conversion product is used directly as ethylene feedstock. The hydrogenation conversion product includes ethane, propane and n-butane, and the mass ratio of n-butane to isobutane is 52:48.

[0057] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0058] Example 3

[0059] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0060] (1) Hydrocracked light naphtha is mixed with hydrogen and passed sequentially through the first hydroconversion reaction zone and the second hydroconversion reaction zone for hydroconversion reaction; the first hydroconversion reaction zone is loaded with catalysts Cat-A2, Cat-A3 and Cat-A4 sequentially along the flow direction and the second hydroconversion reaction zone is loaded with Cat-B3;

[0061] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained by separation is used as recycled hydrogen, and the hydrogenation conversion product is used directly as ethylene feedstock. The hydrogenation conversion product includes ethane, propane and n-butane, wherein the mass ratio of n-butane to isobutane is 1:1.

[0062] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0063] Example 4

[0064] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0065] (1) Hydrocracked light naphtha is mixed with hydrogen and passed sequentially through the first hydroconversion reaction zone and the second hydroconversion reaction zone for hydroconversion reaction; the first hydroconversion reaction zone is loaded with catalysts Cat-A1, Cat-A4 and Cat-A5 sequentially along the flow direction and the second hydroconversion reaction zone is loaded with Cat-B3;

[0066] (2) The effluent from the hydrogenation reaction in step (1) enters the separation system. The hydrogen-rich gas obtained by separation is used as recycled hydrogen, and the hydrogenation conversion product is used directly as ethylene feedstock. The hydrogenation conversion product includes ethane, propane and n-butane, and the mass ratio of n-butane to isobutane is 51:49.

[0067] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0068] Example 5

[0069] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0070] (1) Hydrocracked light naphtha is mixed with hydrogen and passed sequentially through the first hydroconversion reaction zone and the second hydroconversion reaction zone for hydroconversion reaction; the first hydroconversion reaction zone is loaded with catalysts Cat-A1, Cat-A6 and Cat-A3 sequentially along the flow direction and the second hydroconversion reaction zone is loaded with Cat-B1;

[0071] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained by separation is used as recycled hydrogen, and the hydrogenation conversion product is used directly as ethylene feedstock. The hydrogenation conversion product includes ethane, propane and n-butane, and the mass ratio of n-butane to isobutane is 49:51.

[0072] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0073] Example 6

[0074] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:

[0075] (1) Hydrocracked light naphtha is mixed with hydrogen and passed sequentially through the first hydroconversion reaction zone and the second hydroconversion reaction zone for hydroconversion reaction; the first hydroconversion reaction zone is loaded with catalysts Cat-A1, Cat-A7 and Cat-A3 sequentially along the flow direction and the second hydroconversion reaction zone is loaded with Cat-B5;

[0076] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained by separation is used as recycled hydrogen, and the hydrogenation conversion product is used directly as ethylene feedstock. The hydrogenation conversion product includes ethane, propane and n-butane, wherein the mass ratio of n-butane to isobutane is 1:1.

[0077] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0078] Comparative Example 1

[0079] The difference from Example 1 is that the first hydroconversion reaction zone is only filled with one type of hydroconversion catalyst, Cat-A1. The hydroconversion products are used directly as ethylene feedstock, and the hydroconversion products include ethane, propane, and n-butane, wherein the mass ratio of n-butane to isobutane is 1:1.

[0080] The process conditions and hydrogenation effect in this example are shown in Table 6.

[0081] Comparative Example 2

[0082] The difference from Example 1 is that the first hydroconversion reaction zone is only filled with one type of hydroconversion catalyst, Cat-C1. The hydroconversion products are used directly as ethylene feedstock, and the hydroconversion products include ethane, propane, and n-butane, wherein the mass ratio of n-butane to isobutane is 48:52.

[0083] The process conditions and hydrogenation effect in this example are shown in Table 6.

[0084] Comparative Example 3

[0085] The difference from Example 1 is that the first hydroconversion reaction zone is sequentially loaded with hydroconversion catalysts Cat-A1 and Cat-A5 along the feed direction. The hydroconversion products are used directly as ethylene feedstock, and the hydroconversion products include ethane, propane, and n-butane, wherein the mass ratio of n-butane to isobutane is 53:47.

[0086] The process conditions and hydrogenation effect in this example are shown in Table 6.

[0087] Comparative Example 4

[0088] The difference from Example 1 is that the first hydroconversion reaction zone is sequentially loaded with catalysts Cat-C1 and Cat-A1 along the feed direction. The hydroconversion products are used directly as ethylene feedstock, and the hydroconversion products include ethane, propane, and n-butane, wherein the mass ratio of n-butane to isobutane is 1:1.

[0089] The process conditions and hydrogenation effect in this example are shown in Table 6.

[0090] Table 1. Composition and physicochemical properties of hydroconversion catalysts

[0091]

[0092]

[0093] Table 2 Composition and physicochemical properties of hydroconversion catalysts

[0094] Catalyst number Cat-B1 Cat-B2 Cat-B3 Cat-B4 Cat-B5 Catalyst properties <![CDATA[Pore volume, cm 3 / g]]> 0.24 0.25 0.26 0.27 0.28 <![CDATA[Specific surface area, m 2 / g]]> 310 320 330 340 350 Catalyst composition ZSM-35, wt% 50 50 50 50 45 Alumina, wt% 15 15 15 25 20 <![CDATA[MoO3,wt%]]> 27 28 29 20 35 NiO, wt% 8 7 6 5 5

[0095] Table 3 Physicochemical properties of hydroconversion catalysts

[0096] Catalyst number Cat-C1 Catalyst properties <![CDATA[Pore volume, cm 3 / g]]> 0.30 <![CDATA[Specific surface area, m 2 / g]]> 350 Catalyst composition Beta, wt% 50 Alumina, wt% 20 <![CDATA[MoO3,wt%]]> 25 NiO, wt% 5

[0097] Table 4. Main Properties of Hydrocracked Light Naphtha

[0098]

[0099]

[0100] Table 5. Process conditions and conversion results of each embodiment.

[0101]

[0102] Table 6. Process conditions and conversion results for each comparative example.

[0103]

[0104]

[0105] 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 producing chemical raw materials, the method comprising: (1) Hydrocracked light naphtha and hydrogen are mixed and passed sequentially through the first hydroconversion reaction zone and the second hydroconversion reaction zone for hydroconversion reaction. The first hydroconversion reaction zone is filled with a hydroconversion catalyst containing ZSM-5 molecular sieve, and at least two hydroconversion catalyst beds are filled. The active metal content of the hydroconversion catalyst decreases sequentially along the flow direction. The second hydroconversion reaction zone is filled with a hydroconversion catalyst containing ZSM-35 molecular sieve. (2) The reaction effluent from step (1) enters the separation system and is separated to obtain hydrogen-rich gas and hydrogenation conversion products.

2. The method according to claim 1, characterized in that, The initial boiling point of hydrocracked light naphtha is 10℃~30℃, preferably 15℃~25℃; the final boiling point is 50℃~100℃, preferably 55℃~70℃.

3. The method according to claim 1, characterized in that, In hydrocracking light naphtha, the content of C5-C6 isoalkanes is 60wt%–90wt%, preferably 70wt%–80wt%; C7 + The hydrocarbon content is 0–10 wt%, preferably 0.5 wt%–5 wt%; the C5–C6 n-alkanes content is 10 wt%–30 wt%, preferably 15 wt%–25 wt%; C4 - The hydrocarbon content is 0-10 wt%, preferably 2 wt%-5 wt%; the cyclic hydrocarbon content is 0-10 wt%, preferably 2 wt%-5 wt%; and the total weight of the hydrocracked light naphtha is 100 wt%.

4. The method according to claim 1, characterized in that, In the hydroconversion catalyst containing ZSM-5 molecular sieve, the active metal is selected from one or more of Group VIB metals and Group VIII non-precious metals, the Group VIB metal is selected from one or more of molybdenum and tungsten, and the Group VIII non-precious metal is selected from one or more of cobalt and nickel. Preferably, the hydroconversion catalyst containing ZSM-5 molecular sieve includes a binder, and the binder is preferably alumina.

5. The method according to claim 4, characterized in that, In the hydroconversion catalyst containing ZSM-5 molecular sieve, based on the weight of the hydroconversion catalyst containing ZSM-5 molecular sieve, the content of Group VIB metals as oxides is 5 wt% to 30 wt%, preferably 10 wt% to 20 wt%; the content of Group VIII non-precious metals as oxides is 0.5 wt% to 15 wt%, preferably 3 wt% to 10 wt%; the content of ZSM-5 molecular sieve is 30 wt% to 80 wt%, preferably 40 wt% to 70 wt%; and the content of binder as oxides is 5 wt% to 65 wt%, preferably 10 wt% to 35 wt%.

6. The method according to claim 1, characterized in that, In the hydroconversion catalyst containing ZSM-35, the active metal is selected from one or more of Group VIB metals and Group VIII non-precious metals, the Group VIB metal is selected from one or more of molybdenum and tungsten, and the Group VIII non-precious metal is selected from one or more of cobalt and nickel. Preferably, the hydroconversion catalyst containing ZSM-35 molecular sieve includes a binder, and the binder is preferably alumina.

7. The method according to claim 6, characterized in that, In the hydroconversion catalyst containing ZSM-35 molecular sieve, based on the weight of the hydroconversion catalyst containing ZSM-35 molecular sieve, the content of Group VIB metals, calculated as oxides, is 5 wt% to 30 wt%, preferably 10 wt% to 20 wt%; the content of Group VIII non-precious metals, calculated as oxides, is 0.5 wt% to 15 wt%, preferably 3 wt% to 10 wt%; the content of ZSM-35 molecular sieve is 30 wt% to 80 wt%, preferably 40 wt% to 70 wt%; and the content of binder, calculated as oxides, is 5 wt% to 65 wt%, preferably 10 wt% to 35 wt%.

8. The method according to claim 1, characterized in that, The first hydroconversion reaction zone is filled with 2 to 3 hydroconversion catalyst beds; preferably, along the flow direction, in the first hydroconversion reaction zone, 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, more preferably 1:2 to 2:

1.

9. The method according to claim 1 or 8, characterized in that, In the first hydroconversion reaction zone, along the flow direction, in the hydroconversion catalyst containing ZSM-5 molecular sieve packed in two adjacent catalyst beds, the active metal content in the downstream catalyst, calculated as oxides, is 1 to 25 percentage points lower than the active gold content in the upstream catalyst, calculated as oxides, preferably 5 to 15 percentage points lower. Preferably, in the first hydroconversion reaction zone, along the flow direction, in the hydroconversion catalysts containing ZSM-5 molecular sieves packed in two adjacent catalyst beds, the mass content of Group VIB metals as oxides in the downstream catalyst is 1 to 23 percentage points lower than the mass content of Group VIB metals as oxides in the upstream catalyst, and the mass content of Group VIII non-precious metals as oxides in the downstream catalyst is 0 to 4 percentage points lower than the mass content of Group VIII non-precious metals as oxides in the upstream catalyst.

10. The method according to claim 1, characterized in that, The first hydrogenation conversion reaction conditions are as follows: reaction pressure is 0.5 MPa to 10.0 MPa, preferably 2.0 MPa to 5.0 MPa; reaction temperature is 250℃ to 500℃, preferably 350℃ to 450℃; liquid hourly space velocity is 0.1 h⁻¹. -1 ~15.0h -1 0.5h is preferred -1 ~5.0h -1 The hydrogen-to-oil volume ratio is 10:1 to 2500:1, preferably 100:1 to 2000:1, and even more preferably 100:1 to 1000:

1. And / or, the conditions for the second hydrogenation conversion reaction are as follows: reaction pressure of 0.5 MPa to 10.0 MPa, preferably 2.0 MPa to 5.0 MPa; reaction temperature of 250°C to 500°C, preferably 350°C to 450°C; and liquid hourly space velocity of 0.1 h⁻¹. -1 ~15.0h -1 0.5h is preferred -1 ~5.0h -1 The hydrogen-to-oil volume ratio is 10:1 to 2500:1, preferably 100:1 to 2000:1, and even more preferably 100:1 to 1000:1.

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