A process for the conversion of sulfur-containing petroleum naphtha

Abstract

The application discloses a method for converting sulfur-containing naphtha. The method comprises the following steps: mixing the sulfur-containing naphtha with hydrogen, and then passing the mixture through a hydroconversion reaction zone; and separating a reaction product to obtain hydrogen-rich gas and a hydroconversion product, wherein the sulfur content in the hydroconversion product is 50-200 mg / kg, and the hydroconversion reaction zone is filled with at least two hydroconversion catalyst beds, and the active metal content in the catalysts decreases in sequence along the flow direction. The hydroconversion product containing a certain amount of hydrogen sulfide is used as ethylene raw material, so that the problem of sulfur injection in an ethylene production device can be solved.

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 from sulfur-containing naphtha. Background Technology

[0002] With the orderly advancement of oil conversion, hydrocracking units, serving as a crucial link between refining and chemical industries, have seen increasingly widespread application, leading to a year-on-year increase in the production of hydrocracking light naphtha. Hydrocracking light naphtha has a high content of isoalkanes and is typically used as a gasoline blending component. However, due to the influence of saturated vapor pressure, its blending volume is limited. Therefore, excess hydrocracking light naphtha is usually used as feedstock for steam cracking to produce ethylene. Steam cracking to produce ethylene is a thermal cracking reaction process, and its reaction follows the principle of free radical reactions. Isoalkanes are detrimental to the formation of the target product, ethylene. This results in low yields of both ethylene and trienes when hydrocracking light naphtha is used as ethylene feedstock, affecting the overall economic efficiency of the ethylene 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.

[0005] The methods described above can all convert small-molecule isoalkanes into n-alkanes, but the energy required for conversion varies depending on the molecular structure of the hydrocarbon. Using a single conversion process is insufficient to effectively guarantee the yield of the target product. Furthermore, ethylene feedstock obtained through hydrogenation processes undergoes a process where organic sulfur is removed and converted into hydrogen sulfide during the hydrogenation reaction, and this hydrogen sulfide is then removed during product separation. Therefore, the sulfur content in ethylene feedstock is typically low, and sulfur injection is necessary before it enters the ethylene cracking furnace to prevent coking of the furnace tubes. 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 converting sulfur-containing naphtha. This method uses sulfur-containing naphtha as raw material and can effectively convert isoparaffins in sulfur-containing naphtha into C2-C6 alkanes, thereby increasing the content of C2-C6 n-paraffins in the product and improving the quality of ethylene feedstock.

[0007] This invention provides a method for converting sulfur-containing naphtha. The method includes: mixing sulfur-containing naphtha with hydrogen and passing it through a hydroconversion reaction zone; separating the reaction products to obtain hydrogen-rich gas and hydroconversion products; the sulfur content in the hydroconversion products is 50-200 mg / kg, preferably 100-200 mg / kg; the hydroconversion reaction zone is filled with at least two hydroconversion catalyst beds, and the active metal content in the catalyst decreases sequentially along the flow direction.

[0008] According to the present invention, preferably, the hydroconversion reaction zone is packed with 2 to 3 catalyst beds.

[0009] According to the present invention, along the flow direction, in two adjacent catalyst beds, the mass content of active metal in the downstream catalyst, calculated as oxide, is 1 to 25 percentage points lower than the mass content of active metal in the upstream catalyst, preferably 5 to 15 percentage points lower.

[0010] According to the present invention, the hydrogenation conversion product includes C2-C6 alkanes, wherein the mass ratio of the yield of n-alkane to the fresh feedstock (sulfur-containing naphtha) is 0.5-0.7:1, preferably 0.5-0.6:1.

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

[0012] According to the present invention, the initial boiling point of the sulfur-containing naphtha is 10-30°C, preferably 15-25°C, and the final boiling point is 50-100°C, preferably 55-70°C.

[0013] According to the present invention, the sulfur in the sulfur-containing naphtha is introduced externally, including organic sulfur and / or inorganic sulfur, wherein the organic sulfur includes one or more of disulfides, thiols and thioethers, and the inorganic sulfur includes hydrogen sulfide.

[0014] According to the present invention, the sulfur content in the sulfur-containing naphtha is 50-20000 mg / kg, preferably 200-10000 mg / kg, for example, it can be 200 mg / kg, 500 mg / kg, 800 mg / kg, 1000 mg / kg, 1500 mg / kg, 2000 mg / kg, 2500 mg / kg, 3000 mg / kg, 3500 mg / kg, 4000 mg / kg, 5000 mg / kg, 6000 mg / kg, 7000 mg / kg, 8000 mg / kg, 9000 mg / kg, 10000 mg / kg, and any range between any two values.

[0015] According to the present invention, the sulfur-containing naphtha contains 60 wt% to 90 wt% C5-C6 isoalkanes, preferably 70 wt% to 80 wt%; 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 sulfur-containing naphtha is 100 wt%.

[0016] According to the present invention, preferably, the hydroconversion reaction zone is packed with 2 to 3 hydroconversion catalyst beds. Further, along the flow direction, in two adjacent catalyst beds, the volume ratio of upstream catalyst to downstream catalyst is 1:3 to 3:1, preferably 1:2 to 2:1.

[0017] According to the present invention, the hydroconversion catalyst comprises a molecular sieve, an active metal component, and a binder. The molecular sieve is a shape-selective catalytic sieve, preferably mordenite. Further, the mordenite has a SiO2 / Al2O3 molar ratio of 10–50 and a specific surface area of ​​300–600 m². 2 / g, with a pore volume of 0.15–0.35 mL / g. Further, in the hydroconversion catalyst, based on the weight of the catalyst, the content of the molecular sieve is 30 wt%–80 wt%, preferably 40 wt%–70 wt%.

[0018] According to the present invention, the binder is preferably alumina. Further, in the hydroconversion catalyst, 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.

[0019] According to the present invention, 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, based on the weight of the catalyst, the content of the Group VIB metals as oxides is 5.0 wt% to 30.0 wt%, preferably 10 wt% to 20 wt%; the content of the Group VIII non-noble metals as oxides is 0.5 wt% to 15 wt%, preferably 3 wt% to 10 wt%.

[0020] According to the present invention, preferably, along the flow direction, 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 (preferably 3 to 15 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.

[0021] According to the present invention, the specific surface area of ​​the hydroconversion catalyst is 200-400 m². 2 / g, with a pore volume of 0.15~0.35mL / g.

[0022] According to the present invention, the preparation method of the 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 preparation process of the support is as follows: a shape-selective cracking 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 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.

[0024] 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 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.

[0025] According to the present invention, the hydroconversion products can be directly used as feedstock for a steam cracking ethylene production unit to obtain the main target products ethylene, propylene, and butadiene. The triene yield is the sum of the yields of ethylene, propylene, and butadiene as a percentage by mass of the hydroconversion product feed. The operating conditions for the steam cracking ethylene production include: a reaction temperature of 860–890°C, a reaction pressure of 0.1–0.3 MPa, and a water-to-oil mass ratio of 0.2–0.6.

[0026] According to the present invention, the separated hydrogen gas is used as recycled hydrogen.

[0027] In the hydroconversion process, the first step is the dehydrogenation reaction. Through research, the inventors have discovered that the smaller the molecular weight of isoalkanes, the more difficult it is for them to undergo the dehydrogenation reaction. Therefore, the hydrogenation performance of the hydroconversion catalyst directly affects the conversion effect of isoalkanes. That is, the stronger the hydrogenation performance of the catalyst, the easier it is for the dehydrogenation reaction to occur, generating carbocations, thereby realizing the conversion of isoalkanes into n-alkanes.

[0028] Compared with the prior art, the present invention has the following beneficial technical effects:

[0029] (1) The reactivity of hydroconversion catalysts is mainly affected by hydrotreating performance, while the reaction process of isoalkanes is mainly affected by acid centers, i.e., molecular sieves. The inventors have discovered that mordenite with a high content of medium-strong acids tends to undergo normalization reactions during hydroconversion, enabling highly selective conversion of isoalkanes in hydrocracking light naphtha into C2-C6 normal alkanes. However, existing technologies generally use hydroconversion catalysts with the same metal content, resulting in low normal alkane yields. Further research by the inventors revealed that the method of this invention, by loading hydroconversion catalyst beds with different active metal contents, and with the active metal content gradually decreasing along the stream direction, can significantly improve normal alkane yield by matching the dehydrogenation performance of the catalysts.

[0030] (2) In the process of producing ethylene by steam cracking, the sulfur content of the feedstock needs to be controlled to a certain extent. If the sulfur content is too low, sulfur needs to be injected before the cracking furnace, otherwise it will accelerate the coking of the ethylene cracking furnace, affecting the operating cycle and cracking effect; while if the sulfur content in the feedstock is too high, it will increase the operating cost of subsequent desulfurization. The inventors have found through research that when producing ethylene feedstock through hydrogenation reaction, by processing sulfur-containing feedstock and controlling the appropriate sulfur content in the hydrogenation products, the sulfur content in the feedstock of the ethylene unit can be effectively controlled, reducing or even eliminating the amount of sulfur injected into the ethylene cracking furnace, and reducing the operating cost of the ethylene unit.

[0031] (3) During the hydrogenation reaction of sulfur-containing hydrocarbon feedstocks, organic sulfides are converted into hydrogen sulfide. This hydrogen sulfide is a worthless product for the hydrogenation unit and may even require removal through separation methods such as stripping. The removed hydrogen sulfide also requires subsequent harmless treatment. This invention uses hydrogenation products containing a certain amount of hydrogen sulfide as ethylene feedstock, which not only solves the problem of sulfur injection into ethylene production units but also achieves high-value utilization of the useless components. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the process flow according to an embodiment of the present invention;

[0033] Explanation of key figure labels:

[0034] 1-Sulfur-containing naphtha, 2-Hydrogen gas, 3-Hydroconversion reaction zone, 4-Hydroconversion reaction zone effluent, 5-Separation system, 6-Hydrogen-rich gas, 7-Hydroconversion products. Detailed Implementation

[0035] 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.

[0036] Unless otherwise specified, all percentages in this invention refer to mass fractions.

[0037] The method of the present invention, such as Figure 1 As shown, the process includes: sulfur-containing naphtha 1 and hydrogen 2 are mixed and enter the hydroconversion reaction zone 3 for hydroconversion reaction; the hydroconversion reaction effluent 4 enters the separation system 5; the separated hydrogen-rich gas 6 is recycled; and the hydroconversion product 7 is used directly as ethylene feedstock.

[0038] 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 were prepared using a conventional active metal saturation impregnation method, and the physicochemical properties of the obtained catalysts are shown in Table 1.

[0039] In this invention, the mordenite zeolite used in each example catalyst has a SiO2 / Al2O3 molar ratio of 20 and a specific surface area of ​​450 m². 2 / g, pore volume is 0.25mL / g; the Beta molecular sieve used in each catalyst example has a SiO2 / Al2O3 molar ratio of 30 and a specific surface area of ​​350m². 2 / g, pore volume is 0.30mL / g.

[0040] In this invention, the sulfur-containing naphtha used in each example is hydrocracked light naphtha with added sulfur-containing compounds, and its main properties are shown in Table 3. The sulfur-containing compound is hydrogen sulfide.

[0041] In this invention, the n-alkanes in Tables 3-4 include ethane, propane, n-butane, n-pentane, and n-hexane.

[0042] In this invention, the yield of n-alkanes = n-alkanes yield in hydrogenation conversion products / fresh feed amount × 100%, by mass.

[0043] In this invention, the sulfur content of the naphtha in each example is less than 5 ppm.

[0044] Example 1

[0045] The conversion method of sulfur-containing naphtha adopts, for example Figure 1 The process is shown below. The method specifically includes:

[0046] (1) Sulfur-containing naphtha is mixed with hydrogen and passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is sequentially filled with catalysts Cat-A2 and Cat-A3 along the flow direction;

[0047] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, the separated hydrogen-rich gas is used as recycled hydrogen, and the hydrogenation conversion product directly enters the steam cracking ethylene production unit.

[0048] The process conditions and hydrogenation effect in this example are shown in Table 4.

[0049] Example 2

[0050] The conversion method of sulfur-containing naphtha adopts, for example Figure 1 The process is shown below. The method specifically includes:

[0051] (1) Sulfur-containing naphtha is mixed with hydrogen and passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is sequentially filled with catalysts Cat-A1, Cat-A2 and Cat-A3 along the flow direction;

[0052] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, the separated hydrogen-rich gas is used as recycled hydrogen, and the hydrogenation conversion product directly enters the steam cracking ethylene production unit.

[0053] The process conditions and hydrogenation effect in this example are shown in Table 4.

[0054] Example 3

[0055] The conversion method of sulfur-containing naphtha adopts, for example Figure 1 The process is shown below. The method specifically includes:

[0056] (1) Sulfur-containing naphtha is mixed with hydrogen and then subjected to a hydroconversion reaction in the hydroconversion reaction zone; the hydroconversion reaction zone is sequentially filled with catalysts Cat-A2, Cat-A3 and Cat-A4 along the flow direction;

[0057] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, the separated hydrogen-rich gas is used as recycled hydrogen, and the hydrogenation conversion product directly enters the steam cracking ethylene production unit.

[0058] The process conditions and hydrogenation effect in this example are shown in Table 4.

[0059] Example 4

[0060] The conversion method of sulfur-containing naphtha adopts, for example Figure 1 The process is shown below. The method specifically includes:

[0061] (1) Sulfur-containing naphtha is mixed with hydrogen and passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is sequentially filled with catalysts Cat-A1, Cat-A4 and Cat-A5 along the flow direction;

[0062] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, the separated hydrogen-rich gas is used as recycled hydrogen, and the hydrogenation conversion product directly enters the steam cracking ethylene production unit.

[0063] The process conditions and hydrogenation effect in this example are shown in Table 4.

[0064] Example 5

[0065] The conversion method of sulfur-containing naphtha adopts, for example Figure 1 The process is shown below. The method specifically includes:

[0066] (1) Sulfur-containing naphtha is mixed with hydrogen and passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is sequentially filled with catalysts Cat-A4, Cat-A6 and Cat-A3 along the flow direction;

[0067] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, the separated hydrogen-rich gas is used as recycled hydrogen, and the hydrogenation conversion product directly enters the steam cracking ethylene production unit.

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

[0069] Example 6

[0070] The conversion method of sulfur-containing naphtha adopts, for example Figure 1 The process is shown below. The method specifically includes:

[0071] (1) Sulfur-containing naphtha is mixed with hydrogen and passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is sequentially filled with catalysts Cat-A4, Cat-A7 and Cat-A3 along the flow direction;

[0072] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, the separated hydrogen-rich gas is used as recycled hydrogen, and the hydrogenation conversion product directly enters the steam cracking ethylene production unit.

[0073] The process conditions and hydrogenation effect in this example are shown in Table 4.

[0074] Example 7

[0075] The conversion method of sulfur-containing naphtha adopts, for example Figure 1 The process shown uses a raw material with a sulfur content of 1000 mg / kg. The method specifically includes:

[0076] (1) Sulfur-containing naphtha is mixed with hydrogen and passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is sequentially filled with catalysts Cat-A3 and Cat-A1 along the flow direction;

[0077] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, the separated hydrogen-rich gas is used as recycled hydrogen, and the hydrogenation conversion product directly enters the steam cracking ethylene production unit.

[0078] The process conditions and hydrogenation effect in this example are shown in Table 4.

[0079] Example 8

[0080] The conversion method of sulfur-containing naphtha adopts, for example Figure 1 The process shown uses a raw material with a sulfur content of 5000 mg / kg. The method specifically includes:

[0081] (1) Sulfur-containing naphtha is mixed with hydrogen and passed through a hydroconversion reaction zone for hydroconversion reaction; the hydroconversion reaction zone is sequentially filled with catalysts Cat-A6 and Cat-A3 along the flow direction;

[0082] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system, the separated hydrogen-rich gas is used as recycled hydrogen, and the hydrogenation conversion product directly enters the steam cracking ethylene production unit.

[0083] The process conditions and hydrogenation effect in this example are shown in Table 4.

[0084] Comparative Example 1

[0085] The difference from Example 1 is that the hydroconversion reaction zone is filled with a hydroconversion catalyst, Cat-A5.

[0086] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0087] Comparative Example 2

[0088] The difference from Example 1 is that the hydroconversion reaction zone is sequentially filled with hydroconversion catalysts Cat-B1 and Cat-A4.

[0089] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0090] Comparative Example 3

[0091] The difference from Example 1 is that the hydrogenation conversion reaction zone is sequentially filled with catalysts Cat-A4 and Cat-A2.

[0092] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0093] Comparative Example 4

[0094] The difference from Example 1 is that the hydrogenation conversion reaction zone is filled with catalyst Cat-B1.

[0095] The process conditions and hydrogenation effect in this example are shown in Table 5.

[0096] Table 1. Composition and physicochemical properties of hydroconversion catalysts

[0097]

[0098]

[0099] Table 2 Composition and physicochemical properties of hydroconversion catalysts

[0100] Catalyst number Cat-B1 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

[0101] Table 3. Main Properties of Sulfur-Containing Naphtha

[0102] Raw material composition <![CDATA[C4 isoparaffin content, wt%]]> 1 <![CDATA[Content of n-C4 paraffin, wt%]]> 2 <![CDATA[Content of C5-C6 normal paraffins, wt%]]> 16 <![CDATA[C5-C6 isoparaffin content, wt%]]> 78 <![CDATA[C7 + Hydrocarbon and cyclic hydrocarbon content, wt% 3 Initial boiling point, ℃ 24 Final boiling point, ℃ 64

[0103] Table 4. Process conditions and conversion results of each embodiment

[0104]

[0105]

[0106] Table 4 continues with the process conditions and conversion results of each embodiment.

[0107]

[0108] Table 5. Process conditions and conversion results for each comparative example.

[0109]

[0110] Application examples

[0111] The products obtained from hydrogenation conversion in Examples 1, 2, 7, 8, and Comparative Example 2 of this invention were fed into a steam cracking unit to produce ethylene, yielding the main target products ethylene, propylene, and butadiene. The operating conditions for the steam cracking to produce ethylene 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.

[0112] Table 6

[0113]

[0114]

[0115] 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 converting sulfur-containing naphtha, the method comprising: Sulfur-containing naphtha is mixed with hydrogen and then passed through a hydroconversion reaction zone. The reaction products are separated to obtain hydrogen-rich gas and hydroconversion products. The sulfur content in the hydroconversion products is 50-200 mg / kg, preferably 100-200 mg / kg. The hydroconversion reaction zone is filled with at least two hydroconversion catalyst beds, and the active metal content in the catalyst decreases sequentially along the flow direction.

2. The conversion method according to claim 1, characterized in that, The hydroconversion reaction zone is packed with 2 to 3 catalyst beds; along the flow direction, the volume ratio of the upstream catalyst to the downstream catalyst in two adjacent catalyst beds is 1:3 to 3:1, preferably 1:2 to 2:

1.

3. The conversion method according to claim 1, characterized in that, The hydroconversion catalyst comprises a molecular sieve, an active metal component, and a binder, wherein the molecular sieve is preferably mordenite, the active metal component is selected from one or more Group VIB metals and Group VIII non-precious metals, the Group VIB metal is selected from one or more molybdenum and tungsten, the Group VIII non-precious metal is selected from one or more cobalt and nickel, and the binder is preferably alumina.

4. The conversion method according to claim 3, characterized in that, In the hydroconversion catalyst, based on the weight of the catalyst, the content of the molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%; the content of the Group VIB metal as oxide is 5.0wt% to 30.0wt%, preferably 10wt% to 20wt%; the content of the Group VIII non-noble metal as oxide is 0.5wt% to 15wt%, preferably 3wt% to 10wt%; and the content of the binder as oxide is 5wt% to 65wt%, preferably 10wt% to 35wt%.

5. The conversion method according to claim 1 or 3, characterized in that, Along the flow direction, in two adjacent catalyst beds, the mass content of active metals in the downstream catalyst, calculated as oxides, is 1 to 25 percentage points lower than that in the upstream catalyst, preferably 5 to 15 percentage points lower.

6. The conversion method according to claim 1 or 3, characterized in that, Along the flow direction, 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 that 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 that in the upstream catalyst.

7. The conversion method according to claim 1, characterized in that, The hydrogenation conversion products include C2-C6 alkanes, wherein the mass ratio of n-alkanes to fresh feedstock is 0.5-0.7:1, preferably 0.5-0.6:

1.

8. The conversion method according to claim 1, characterized in that, The initial boiling point of the sulfur-containing naphtha is 10-30℃, preferably 15-25℃, and the final boiling point is 50-100℃, preferably 55-70℃.

9. The conversion method according to claim 1, characterized in that, The sulfur content in the sulfur-containing naphtha is 50-20000 mg / kg, preferably 200-10000 mg / kg; And / or, the sulfur-containing naphtha contains 60 wt% to 90 wt% C5-C6 isoalkanes, preferably 70 wt% to 80 wt%; 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 sulfur-containing naphtha is 100 wt%.

10. The conversion 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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