A method for the hydrogenation conversion of C5C6 hydrocarbons

Abstract

The application discloses a C5-C6 hydrocarbon hydroconversion method. The method comprises the following steps: C5-C6 hydrocarbons are subjected to normal and iso separation, C5-C6 normal alkanes obtained are directly used as ethylene raw materials, C5-C6 iso alkanes obtained are mixed with hydrogen and subjected to hydroconversion reaction through a hydroconversion reaction zone, reaction effluent enters a separation system, hydrogen-rich gas and hydroconversion products are separated, the hydroconversion products are separated to obtain C2-C4 hydrocarbons which are directly used as ethylene raw materials, and C5-C6 hydrocarbons continue to be recycled and converted; wherein, the hydroconversion reaction zone is sequentially filled with a hydroconversion catalyst containing ZSM-5 molecular sieve and a hydroconversion catalyst containing mordenite along the flow direction. The method can maximize the quality of ethylene raw materials, improve the ethylene yield of an ethylene device and the total yield of trienes.

Description

Technical Field

[0001] This invention belongs to the field of hydrocarbon hydroconversion, specifically relating to a hydroconversion method for producing high-quality ethylene feedstock from C5C6 hydrocarbons. Background Technology

[0002] Feedstock for ethylene production via steam cracking is a major factor influencing ethylene costs, accounting for 70% to 75% of the total cost. Currently, the main feedstocks for ethylene production via steam cracking include ethane, propane, butane, LPG, condensate oil, naphtha, diesel oil, and hydrocracking tail oil.

[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 the hydrogenation conversion of C5C6 hydrocarbons. This method uses C5C6 hydrocarbons as raw materials and can effectively convert isoalkanes in C5C6 hydrocarbons into n-alkanes, thereby improving the quality of ethylene feedstock.

[0007] This invention provides a method for the hydrogenation conversion of C5C6 hydrocarbons, the method comprising:

[0008] (1) C5C6 hydrocarbons are treated to remove isopentane to obtain isopentane and effluent I;

[0009] (2) The effluent I obtained in step (1) is treated to remove n-pentane to obtain n-pentane and effluent II, wherein the n-pentane is directly used as ethylene feedstock;

[0010] (3) The effluent II obtained in step (2) is subjected to isohexane removal treatment to obtain isohexane and n-hexane, wherein n-hexane is directly used as ethylene feedstock;

[0011] (4) The isopentane obtained in step (1) and the isohexane obtained in step (3) are mixed with hydrogen and carried out in the hydrogenation conversion reaction zone; the hydrogenation conversion reaction zone is sequentially filled with a hydrogenation conversion catalyst containing ZSM-5 molecular sieve and a hydrogenation conversion catalyst containing mordenite along the flow direction.

[0012] (5) The reaction effluent obtained in step (4) enters the separation system to separate hydrogen-rich gas and hydrogenation conversion products. The C2-C4 hydrocarbons separated from the hydrogenation conversion products are used directly as ethylene feedstock, while the C5-C6 hydrocarbons are recycled to step (1).

[0013] According to the present invention, step (1) isopentane removal is carried out in an isopentane removal tower. The feed temperature of the isopentane removal tower is 67-71°C, the top temperature of the tower is 59-62°C, and the bottom temperature of the tower is 98-103°C. The top pressure of the tower is 0.15-0.17 MPa, and the bottom pressure of the tower is 0.18-0.20 MPa.

[0014] According to the present invention, step (2) of removing n-pentane is carried out in a n-iso-n-ane removal tower. The feed temperature of the n-pentane removal tower is 98-103°C, the top temperature is 66-75°C, and the bottom temperature is 102-105°C. The top pressure is 0.13-0.15 MPa, and the bottom pressure is 0.16-0.18 MPa.

[0015] According to the present invention, step (3) isohexane removal is carried out in an isohexane removal tower. The feed temperature of the isohexane removal tower is 102-105℃, the top temperature of the tower is 77-79℃, and the bottom temperature of the tower is 101-104℃. The top pressure of the tower is 0.07-0.08MPa, and the bottom pressure of the tower is 0.10-0.12MPa.

[0016] According to the present invention, a fixed-bed reactor is used for the hydrogenation conversion reaction.

[0017] According to the present invention, the hydroconversion reaction zone is sequentially filled with a hydroconversion catalyst containing ZSM-5 molecular sieve and a hydroconversion catalyst containing mordenite 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 mordenite. The hydroconversion catalyst containing ZSM-5 molecular sieve and the hydroconversion catalyst containing mordenite can be graded and packed in one or more catalyst beds along the material flow direction.

[0018] According to the present invention, the initial boiling point of the C5C6 hydrocarbon 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.

[0019] According to the present invention, the content of C5-C6 isoalkanes in the C5-C6 hydrocarbons is 40wt% to 60wt%, preferably 45wt% to 55wt%; C7 + The hydrocarbon content is 0–10 wt%, preferably 0.5 wt%–5 wt%; the C5–C6 n-alkanes content is 40 wt%–60 wt%, preferably 45 wt%–55 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 C5C6 hydrocarbons is 100 wt%.

[0020] According to the present invention, the packing volume ratio of the hydroconversion catalyst containing ZSM-5 molecular sieve to the hydroconversion catalyst containing mordenite is 1:3 to 3:1, preferably 1:2 to 2:1. Further, the active metal content (in oxides) of the hydroconversion catalyst containing ZSM-5 molecular sieve is 1 to 20 percentage points higher than that of the hydroconversion catalyst containing mordenite (in oxides), preferably 5 to 10 percentage points higher.

[0021] 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. In hydroconversion catalysts containing mordenite, the SiO2 / Al2O3 molar ratio of 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.

[0022] 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.

[0023] 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%.

[0024] 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 Group VIB metals (calculated as oxides) is 5 wt% to 30 wt%, preferably 10 wt% to 20 wt%; the content of Group VIII non-noble metals (calculated as oxides) is 0.5 wt% to 15 wt%, preferably 3 wt% to 10 wt%.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] Furthermore, in the hydroconversion catalyst containing mordenite, the content of mordenite molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%, based on the weight of the catalyst.

[0029] According to the present invention, the hydroconversion catalyst containing mordenite further includes a binder, preferably alumina. Further, in the hydroconversion catalyst containing mordenite, the binder content (calculated as oxide) is 5 wt% to 65 wt%, preferably 10 wt% to 35 wt%, based on the weight of the catalyst.

[0030] According to the present invention, in the mordenite-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 mordenite-containing hydroconversion catalyst, based on the weight of the catalyst, 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-noble metals (calculated as oxides) is 0.5 wt% to 15 wt%, preferably 3 wt% to 10 wt%.

[0031] According to the present invention, the specific surface area of ​​the hydroconversion catalyst containing mordenite is 200-400 m². 2 / g, with a pore volume of 0.15~0.40mL / g.

[0032] According to the present invention, the preparation method of the mordenite-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: mordenite and a binder are mechanically mixed, shaped, dried, and calcined to form a catalyst support. The drying and calcination of the support can be performed 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.

[0033] According to the present invention, in the preparation method of the hydroconversion catalyst containing mordenite, 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.

[0034] According to the present invention, the active metal content (in oxides) of the hydroconversion catalyst containing ZSM-5 molecular sieve is 1 to 20 percentage points higher than that of the hydroconversion catalyst containing mordenite (in oxides), preferably 5 to 10 percentage points higher. Preferably, the content of Group VIB metals (in oxides) in the hydroconversion catalyst containing ZSM-5 molecular sieve is 1 to 18 percentage points higher (preferably 2 to 10 percentage points) higher than that in the hydroconversion catalyst containing mordenite, and the content of Group VIII non-precious metals (in oxides) in the hydroconversion catalyst containing ZSM-5 molecular sieve is 0 to 4 percentage points higher than that in the hydroconversion catalyst containing mordenite.

[0035] According to the present invention, the hydroconversion 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°C to 500°C, preferably 350°C to 450°C; and liquid hourly space velocity is 0.1 h⁻¹. -1 ~15.0h -1 Preferred 0.5h- 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.

[0036] According to the present invention, the reaction effluent from step (1) in step (2) is fed into a separation system, and the separated hydrogen-rich gas can be used as recycled hydrogen.

[0037] According to the present invention, a steam cracking unit for producing ethylene from C2-C4 hydrocarbons obtained by hydroconversion products and n-pentane and n-hexane obtained by isomerization yields the main target products ethylene, propylene, and butadiene, wherein the yields of the trienes are the mass percentages of ethylene, propylene, and butadiene produced relative to the feed amount. The operating conditions for the steam cracking to produce ethylene are: reaction temperature 860-890°C, reaction pressure 0.1-0.3 MPa, and water-to-oil mass ratio 0.2-0.6.

[0038] Compared with the prior art, the present invention has the following beneficial technical effects:

[0039] (1) Through research, the inventors discovered that as the molecular weight increases, the difficulty of ortho-alkanization reactions gradually increases, and C6 components are more prone to cracking reactions. The reactivity of hydroconversion catalysts is mainly affected by hydrogenation performance, while the reaction process of isoalkanes is mainly affected by acid centers, i.e., molecular sieves. Through research, the inventors discovered that mordenite with a high content of medium-strong acids tends to undergo ortho-alkanization reactions during hydroconversion, while ZSM-5 molecular sieves with a high content of strong acids tend to undergo cracking reactions. By using these two molecular sieves with different reaction characteristics in a graded manner, efficient conversion of different molecular hydrocarbons can be achieved. Through further research, the inventors discovered that using ZSM-5 molecular sieve catalysts with high active metal content can improve the cracking performance of hydroconversion catalysts, preferentially hydrocracking C6 isoalkanes, and then using mordenite catalysts with lower active metal content to induce ortho-alkanization reactions of C5 isoalkanes. This fully utilizes the catalytic effects of the two molecular sieve catalysts, and can effectively reduce the hydrogen consumption of the reaction while increasing the proportion of ortho-alkanes in the hydrogenation products.

[0040] (2) The hydroconversion method of this invention first separates C5C6 hydrocarbons into n-pentane and n-hexane, which are then used directly as ethylene feedstock. The isopentane and isohexane are then hydrogenated to n-alkanes. The hydroconversion reaction zone is sequentially loaded with a hydroconversion catalyst containing ZSM-5 molecular sieve and a hydroconversion catalyst containing mordenite along the feedstock direction. The active metal content of the ZSM-5 molecular sieve-containing hydroconversion catalyst is higher than that of the mordenite-containing hydroconversion catalyst. This invention employs a full-cycle process, combined with catalyst gradation, to maximize the quality of the ethylene feedstock and improve the ethylene yield and total terene yield of the ethylene plant. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the process flow according to an embodiment of the present invention;

[0042] Explanation of key figure labels:

[0043] 1-C5C6 hydrocarbons, 2-Isopentane removal tower, 3-Isopentane, 4-Isopentane removal tower bottom effluent, 5-N-pentane removal tower, 6-N-pentane, 7-N-pentane removal tower bottom effluent, 8-Isohexane removal tower, 9-Isohexane, 10-N-hexane, 11-Hydrogen, 12-Hydroconversion reaction zone, 13-Hydroconversion reaction effluent, 14-Separator, 15-Hydrogen-rich gas, 16-Hydroconversion product, 17-Fracturing tower, 18-C2~C4 hydrocarbons, 19-Hydroconversion C5C6 hydrocarbons. Detailed Implementation

[0044] 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.

[0045] Unless otherwise specified, all percentages in this invention refer to mass fractions.

[0046] The method of the present invention, such as Figure 1 As shown, the process includes: C5C6 hydrocarbon 1 enters the isopentane removal tower 2 to obtain isopentane 3 as the top effluent; bottom effluent 4 enters the n-pentane removal tower 5 to obtain n-pentane 6 as the top effluent; bottom effluent 7 enters the isohexane removal tower 8 to obtain isohexane 9 as the top effluent and n-hexane 10 as the bottom effluent; isopentane 3 and isohexane 9 are mixed with hydrogen 11 and enter the hydroconversion reaction zone 12 for hydroconversion reaction; hydroconversion reaction effluent 13 enters the separation system 14; the separated hydrogen-rich gas 15 is recycled; the hydroconversion product 16 enters the fractionation tower 17; the separated C2-C4 hydrocarbon 18 is directly used as ethylene feedstock; and the hydroconverted C5C6 hydrocarbon 19 is recycled to the isopentane removal tower 2.

[0047] In this invention, the yield (%) of n-alkanes = (yield of C2-C4 n-alkanes in the hydrogenation conversion products + n-pentane yield from the n-pentane removal tower + n-hexane yield from the isohexane removal tower) / fresh feed amount × 100%, by mass.

[0048] In this invention, the hydroconversion catalysts in each example are designated as Cat-A followed by a number, such as Cat-A1, Cat-A2, Cat-A3, and Cat-A4. The hydroconversion catalysts in each example 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 Table 1.

[0049] 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 the mordenite used in Cat-B are as follows: SiO2 / Al2O3 molar ratio is 20, and specific surface area is 450m². 2 / g, pore volume 0.25cm 3 / g.

[0050] The main properties of the C5C6 hydrocarbons used in the various examples of this invention are shown in Table 3.

[0051] In this invention, the n-alkanes in Tables 4-5 include ethane, propane, n-butane, n-pentane, and n-hexane.

[0052] In this invention, the feed temperature of the isopentane removal tower is 69°C, the top temperature is 60°C, the bottom temperature is 100°C, the top pressure is 0.16 MPa, and the bottom pressure is 0.19 MPa; the feed temperature of the n-pentane removal tower is 100°C, the top temperature is 70°C, the bottom temperature is 103°C, the top pressure is 0.14 MPa, and the bottom pressure is 0.17 MPa; the feed temperature of the isohexane removal tower is 103°C, the top temperature is 78°C, the bottom temperature is 103°C, the top pressure is 0.07 MPa, and the bottom pressure is 0.11 MPa.

[0053] Example 1

[0054] The conversion methods for C5 and C6 hydrocarbons employ methods such as... Figure 1 The process is shown below. The method specifically includes:

[0055] (1) Isopentane and isohexane obtained by C5C6 hydrocarbons through normal isomerization are mixed with hydrogen and carried out in the hydrogenation conversion reaction zone; the hydrogenation conversion reaction zone is sequentially filled with hydrogenation conversion Cat-A1 and Cat-B1; n-pentane and n-hexane obtained by C5C6 hydrocarbons through normal isomerization are directly used as ethylene feedstock.

[0056] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained from the separation is used as recycled hydrogen. The C2-C4 hydrocarbons obtained from the separation of the hydrogenation conversion products are used directly as ethylene feedstock. The C5-C6 hydrocarbons are recycled to the inlet of the deisopentane tower.

[0057] The process conditions and hydrogenation effect after cyclic operation in this example are shown in Table 4.

[0058] Example 2

[0059] The conversion methods for C5 and C6 hydrocarbons employ methods such as... Figure 1 The process is shown below. The method specifically includes:

[0060] (1) Isopentane and isohexane obtained by normal isomerization of C5C6 hydrocarbons are mixed with hydrogen and carried out in the hydrogenation conversion reaction zone; the hydrogenation conversion reaction zone is sequentially filled with hydrogenation conversion Cat-A2 and Cat-B2.

[0061] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained from the separation is used as recycled hydrogen. The C2-C4 hydrocarbons obtained from the separation of the hydrogenation conversion products are used directly as ethylene feedstock. The C5-C6 hydrocarbons are recycled to the inlet of the deisopentane tower.

[0062] The process conditions and hydrogenation effect after cyclic operation in this example are shown in Table 4.

[0063] Example 3

[0064] The conversion methods for C5 and C6 hydrocarbons employ methods such as... Figure 1 The process is shown below. The method specifically includes:

[0065] (1) Isopentane and isohexane obtained by C5C6 hydrocarbons through normal isomerization are mixed with hydrogen and carried out in the hydrogenation conversion reaction zone; the hydrogenation conversion reaction zone is sequentially filled with hydrogenation conversion Cat-A3 and Cat-B3; n-pentane and n-hexane obtained by C5C6 hydrocarbons through normal isomerization are directly used as ethylene feedstock.

[0066] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained from the separation is used as recycled hydrogen. The C2-C4 hydrocarbons obtained from the separation of the hydrogenation conversion products are used directly as ethylene feedstock. The C5-C6 hydrocarbons are recycled to the inlet of the deisopentane tower.

[0067] The process conditions and hydrogenation effect after cyclic operation in this example are shown in Table 4.

[0068] Example 4

[0069] The conversion methods for C5 and C6 hydrocarbons employ methods such as... Figure 1 The process is shown below. The method specifically includes:

[0070] (1) Isopentane and isohexane obtained by the normal isomerization of C5C6 hydrocarbons are mixed with hydrogen and carried out in the hydrogenation conversion reaction zone; the hydrogenation conversion reaction zone is sequentially filled with hydrogenation conversion Cat-A1 and Cat-B3; n-pentane and n-hexane obtained by the normal isomerization of C5C6 hydrocarbons are directly used as ethylene feedstock.

[0071] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained from the separation is used as recycled hydrogen. The C2-C4 hydrocarbons obtained from the separation of the hydrogenation conversion products are used directly as ethylene feedstock. The C5-C6 hydrocarbons are recycled to the inlet of the deisopentane tower.

[0072] The process conditions and hydrogenation effect after cyclic operation in this example are shown in Table 4.

[0073] Example 5

[0074] The conversion methods for C5 and C6 hydrocarbons employ methods such as... Figure 1 The process is shown below. The method specifically includes:

[0075] (1) Isopentane and isohexane obtained by C5C6 hydrocarbons through normal isomerization are mixed with hydrogen and carried out in the hydrogenation conversion reaction zone; the hydrogenation conversion reaction zone is sequentially filled with hydrogenation conversion Cat-A4 and Cat-B1; n-pentane and n-hexane obtained by C5C6 hydrocarbons through normal isomerization are directly used as ethylene feedstock.

[0076] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained from the separation is used as recycled hydrogen. The C2-C4 hydrocarbons obtained from the separation of the hydrogenation conversion products are used directly as ethylene feedstock. The C5-C6 hydrocarbons are recycled to the inlet of the deisopentane tower.

[0077] The process conditions and hydrogenation effect after cyclic operation in this example are shown in Table 4.

[0078] Example 6

[0079] The conversion methods for C5 and C6 hydrocarbons employ methods such as... Figure 1 The process is shown below. The method specifically includes:

[0080] (1) Isopentane and isohexane obtained by the normal isomerization of C5C6 hydrocarbons are mixed with hydrogen and carried out in the hydrogenation conversion reaction zone; the hydrogenation conversion reaction zone is sequentially filled with hydrogenation conversion Cat-A1 and Cat-B5; n-pentane and n-hexane obtained by the normal isomerization of C5C6 hydrocarbons are directly used as ethylene feedstock.

[0081] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system. The hydrogen-rich gas obtained from the separation is used as recycled hydrogen. The C2-C4 hydrocarbons obtained from the separation of the hydrogenation conversion products are used directly as ethylene feedstock. The C5-C6 hydrocarbons are recycled to the inlet of the deisopentane tower.

[0082] The process conditions and hydrogenation effect after cyclic operation in this example are shown in Table 4.

[0083] Comparative Example 1

[0084] The difference from Example 1 is that the hydroconversion reaction zone is only filled with one type of hydroconversion catalyst, Cat-A1.

[0085] The process conditions and hydrogenation effect after cyclic operation in this example are shown in Table 5.

[0086] Comparative Example 2

[0087] The difference from Example 1 is that the hydroconversion reaction zone is only filled with one type of hydroconversion catalyst, Cat-B1.

[0088] The process conditions and hydrogenation effect after cyclic operation in this example are shown in Table 5.

[0089] Comparative Example 3

[0090] The difference from Example 1 is that the hydroconversion reaction zone is sequentially filled with hydroconversion catalysts Cat-A3 and Cat-B1.

[0091] The process conditions and hydrogenation effect after cyclic operation in this example are shown in Table 5.

[0092] Comparative Example 4

[0093] The difference from Example 1 is that the hydrogenation conversion reaction zone is sequentially loaded with catalysts Cat-A1 and Cat-B4. The process conditions and hydrogenation effect after cycle operation in this example are shown in Table 5.

[0094] Table 1. Composition and physicochemical properties of hydroconversion catalysts

[0095] Catalyst number Cat-A1 Cat-A2 Cat-A3 Cat-A4 Catalyst properties <![CDATA[Pore volume, cm 3 / g]]> 0.28 0.30 0.31 0.32 <![CDATA[Specific surface area, m 2 / g]]> 296 308 316 290 Catalyst composition ZSM-5 molecular sieve, wt% 50 50 50 45 Alumina, wt% 20 25 30 30 <![CDATA[MoO3,wt%]]> 25 20 15 20 NiO, wt% 5 5 5 5

[0096] Table 2 Composition and physicochemical properties of hydroconversion catalysts

[0097] Catalyst number Cat-B1 Cat-B2 Cat-B3 Cat-B4 Cat-B5 Catalyst properties <![CDATA[Pore volume, cm 3 / g]]> 0.25 0.26 0.26 0.28 0.30 <![CDATA[Specific surface area, m 2 / g]]> 308 310 315 346 355 Catalyst composition Siliceous zeolite, wt% 50 50 50 50 60 Alumina, wt% 30 32 35 46 15 <![CDATA[MoO3,wt%]]> 15 13 10 3 20 NiO, wt% 5 5 5 1 5

[0098] Table 3. Main Properties of C5C6 Hydrocarbons

[0099] raw material <![CDATA[C5C6 hydrocarbon]]> <![CDATA[C4 isoparaffin content, wt%]]> 1 <![CDATA[n-alkane content in C4, wt%]]> 2 <![CDATA[Content of C5-C6 normal paraffin, wt%]]> 53 <![CDATA[C5-C6 isoparaffin content, wt%]]> 43 <![CDATA[C7 + Hydrocarbon and cyclic hydrocarbon content, wt% 1 Initial boiling point, ℃ 23 Final boiling point, ℃ 65

[0100] Table 4. Process conditions and conversion results of each embodiment

[0101]

[0102] Table 5. Process conditions and conversion results for each comparative example.

[0103] serial number Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Hydrogenation conversion reaction zone Catalyst loading sequence Cat-A1 Cat-B1 Cat-A3 / Cat-B 1 Cat-A1 / Cat-B4 Volume ratio of each catalyst 1：1 1：1 Reaction temperature / °C 385 385 385 385 Reaction pressure / MPa 4.0 4.0 4.0 4.0 Hydrogen-to-oil volume ratio 500 500 500 500 <![CDATA[Liquid hourly space velocity / h -1 > 0.8 0.8 0.8 0.8 n-Alkane yield, % 80 83 84 82

[0104] Application examples

[0105] The n-alkanes obtained in Examples 1, 2, and Comparative Example 4 of this invention (i.e., C2-C4 hydrocarbons separated from hydrogenation conversion products and n-pentane and n-hexane separated from isomerization) were respectively fed into a steam cracking unit for ethylene production, yielding the main target products ethylene, propylene, and butadiene. The operating conditions for the steam cracking to ethylene production were: reaction temperature 880°C, reaction pressure 0.2 MPa, and water-to-oil mass ratio 0.4. The reaction results are shown in Table 6.

[0106] Table 6

[0107] Example 1 Example 2 Comparative Example 4 Ethylene yield, wt% 39.8 41.0 36.8 Propylene yield, wt% 17.7 17.5 18.3 Butadiene yield, wt% 3.9 3.8 4.0

[0108] 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 the hydrogenation conversion of C5C6 hydrocarbons, the method comprising: (1) C5C6 hydrocarbons are treated to remove isopentane to obtain isopentane and effluent I; (2) The effluent I obtained in step (1) is treated to remove n-pentane to obtain n-pentane and effluent II, wherein the n-pentane is directly used as ethylene feedstock; (3) The effluent II obtained in step (2) is subjected to isohexane removal treatment to obtain isohexane and n-hexane, wherein n-hexane is directly used as ethylene feedstock; (4) The isopentane obtained in step (1) and the isohexane obtained in step (3) are mixed with hydrogen and carried out in the hydrogenation conversion reaction zone; the hydrogenation conversion reaction zone is sequentially filled with a hydrogenation conversion catalyst containing ZSM-5 molecular sieve and a hydrogenation conversion catalyst containing mordenite along the flow direction. (5) The reaction effluent obtained in step (4) enters the separation system to separate hydrogen-rich gas and hydrogenation conversion products. The C2-C4 hydrocarbons separated from the hydrogenation conversion products are used directly as ethylene feedstock, while the C5-C6 hydrocarbons are recycled to step (1).

2. The method according to claim 1, characterized in that, Step (1) isopentane removal is carried out in an isopentane removal tower. The feed temperature of the isopentane removal tower is 67-71℃, the top temperature of the tower is 59-62℃, and the bottom temperature of the tower is 98-103℃. The top pressure of the tower is 0.15-0.17MPa, and the bottom pressure of the tower is 0.18-0.20MPa. And / or, step (2) n-pentane removal is carried out in an iso-n-ane removal tower, the feed temperature of the n-pentane removal tower is 98-103℃, the top temperature of the tower is 66-75℃, the bottom temperature of the tower is 102-105℃; the top pressure of the tower is 0.13-0.15MPa, and the bottom pressure of the tower is 0.16-0.18MPa; And / or, step (3) isohexane removal is carried out in an isohexane removal tower, the feed temperature of the isohexane removal tower is 102-105℃, the top temperature of the tower is 77-79℃, the bottom temperature of the tower is 101-104℃; the top pressure of the tower is 0.07-0.08MPa, and the bottom pressure of the tower is 0.10-0.12MPa.

3. The method according to claim 1, characterized in that, The initial boiling point of the C5C6 hydrocarbon is 10℃~30℃, preferably 15℃~25℃; the final boiling point is 50℃~100℃, preferably 55℃~70℃.

4. The method according to claim 1, characterized in that, The C5-C6 hydrocarbons contain 40 wt% to 60 wt% of C5-C6 isoalkanes, preferably 45 wt% to 55 wt%; C7 + The hydrocarbon content is 0–10 wt%, preferably 0.5 wt%–5 wt%; the C5–C6 n-alkanes content is 40 wt%–60 wt%, preferably 45 wt%–55 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 C5C6 hydrocarbons is 100 wt%.

5. The method according to claim 1, characterized in that, 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-precious metals, wherein the Group VIB metals are preferably selected from one or more of molybdenum and tungsten, and the Group VIII non-precious metals are preferably selected from one or more of cobalt and nickel. Preferably, in the ZSM-5 molecular sieve-containing hydroconversion catalyst, based on the weight of the catalyst, the content of ZSM-5 molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%, the content of Group VIB metals is 5wt% to 30wt%, preferably 10wt% to 20wt%, and the content of Group VIII non-precious metals is 0.5wt% to 15wt%, preferably 3wt% to 10wt%.

6. The method according to claim 1, characterized in that, In the hydroconversion catalyst containing mordenite, the active metal component is selected from one or more of Group VIB metals and Group VIII non-precious metals, wherein the Group VIB metals are preferably selected from one or more of molybdenum and tungsten, and the Group VIII non-precious metals are preferably selected from one or more of cobalt and nickel. Preferably, in the mordenite-containing hydroconversion catalyst, based on the weight of the catalyst, the mordenite content is 30wt% to 80wt%, preferably 40wt% to 70wt%; the content of Group VIB metals is 5wt% to 30wt%, preferably 10wt% to 20wt%; and the content of Group VIII non-precious metals is 0.5wt% to 15wt%, preferably 3wt% to 10wt%.

7. The method according to claim 1, characterized in that, The packing volume ratio of the hydroconversion catalyst containing ZSM-5 molecular sieve to the hydroconversion catalyst containing mordenite is 1:3 to 3:1, preferably 1:2 to 2:

1.

8. The method according to claim 1, characterized in that, Along the logistics direction, the active metal content of the hydroconversion catalyst containing ZSM-5 molecular sieve, calculated as oxides, is 1 to 20 percentage points higher than that of the hydroconversion catalyst containing mordenite, calculated as oxides, preferably 5 to 10 percentage points higher. Preferably, the content of Group VIB metals in the hydroconversion catalyst containing ZSM-5 molecular sieve, calculated as oxides, is 1 to 18 percentage points higher than that in the hydroconversion catalyst containing mordenite, calculated as oxides; and the content of Group VIII non-precious metals in the hydroconversion catalyst containing ZSM-5 molecular sieve, calculated as oxides, is 0 to 4 percentage points higher than that in the hydroconversion catalyst containing mordenite, calculated as oxides.

9. The method according to claim 1, characterized in that, The specific surface area of ​​the ZSM-5 molecular sieve-containing hydroconversion catalyst is 200–400 m². 2 / g, with a pore volume of 0.15–0.40 mL / g; and / or, the specific surface area of ​​the mordenite-containing hydroconversion catalyst is 200–400 m² / g. 2 / g, with a pore volume of 0.15~0.40mL / g.

10. The method according to claim 1, characterized in that, The 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.

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