Hydrocracking light naphtha processing method

Abstract

The invention discloses a hydrocracking light naphtha conversion method. The conversion method comprises the following steps: hydrocracking light naphtha mixed with olefin-rich components passes through a hydro-conversion reaction zone to obtain a converted light naphtha product; the hydro-conversion reaction zone is sequentially filled with a catalyst A and a catalyst B in the material flowing direction; wherein the pyridine adsorption capacity (380 DEG C) of the catalyst A is 0.30-0.40 mmol / g, and the micropore volume of the catalyst B accounts for 10%-30% of the total pore volume. By adopting the method disclosed by the invention, the quality of the light naphtha can be effectively improved, and the olefin yield of a device for preparing ethylene by steam cracking is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to a method for processing hydrocracking light naphtha (mainly referring to saturated hydrocarbons rich in C5 and C6 hydrocarbons). Background Technology

[0002] Hydrocracking refers to a hydrogenation process that reduces the molecular size of feedstock by more than 15% through a hydrogenation reaction. It is a catalytic conversion process in which feedstock undergoes hydrogenation, desulfurization, denitrification, molecular structure rearrangement, and cracking reactions under high temperature, high pressure, hydrogen immersion, and the presence of a catalyst. Products obtained from hydrocracking include liquefied petroleum gas (LPG), light naphtha, heavy naphtha, jet fuel, diesel fuel, and lubricating oil base oils, among others. Hydrocracking light naphtha is typically used as feedstock for steam cracking to ethylene production units; however, due to its high isohydrocarbon content, it exhibits poor cracking performance and low ethylene and triene yields.

[0003] CN115505419A discloses a method for the ortho-configuration of light naphtha. This method involves mixing light naphtha feedstock with hydrogen, heating the mixture, and then introducing it from the top of a reactor for ortho-configuration and gas-liquid separation. The separated gaseous product can be sent to a compressor for pressurization and recycling, while the separated liquid product is sent to a stabilization tower for further removal of light components to obtain ortho-configured light naphtha. However, the method does not specify the design of a catalyst for the light naphtha upgrading process. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for processing light naphtha via hydrocracking. This method can effectively improve the quality of light naphtha, thereby significantly increasing the olefin yield of steam cracking ethylene production units.

[0005] The first aspect of this invention provides a method for converting hydrocracking light naphtha, comprising: passing hydrocracking light naphtha mixed with olefin-rich components through a hydroconversion reaction zone to obtain a converted light naphtha product; wherein the hydroconversion reaction zone is sequentially filled with catalyst A and catalyst B along the material flow direction; wherein the pyridine adsorption capacity (380℃) of catalyst A is 0.30-0.40 mmol / g, and the micropore volume of catalyst B accounts for 10%-30% of the total pore volume, preferably 15-25%.

[0006] Furthermore, the initial boiling point of the hydrocracked light naphtha is 15–30°C, and the final boiling point is 60–90°C. The content of C5-C6 isoalkanes in the hydrocracked light naphtha is 70 wt%–95 wt%, preferably 75 wt%–85 wt%, the content of C5-C6 n-alkanes is 10 wt%–20 wt%, and the content of other components is 5 wt%–20 wt%, based on 100 wt% of the weight of the hydrocracked light naphtha.

[0007] Further, the olefin-rich component is selected from pure olefin substances or olefin-rich light naphtha. The pure olefin substance is selected from at least one of butene, pentene, and hexene, and the present invention does not impose any particular limitation on the proportion of each of butene, pentene, and hexene. The olefin-rich light naphtha is one or more of catalytic cracking light naphtha and delayed coking light naphtha, and the present invention does not impose any particular limitation on the mixing ratio of the added catalytic cracking light naphtha and delayed coking light naphtha. Preferably, the mass content of C4-C6 olefins in the catalytic cracking light naphtha is 40wt% to 60wt%, and the mass content of C4-C6 olefins in the delayed coking light naphtha is 30wt% to 50wt%.

[0008] Furthermore, the olefin content in the hydrocracked light naphtha mixed with olefin-rich components is 0.03 to 1.5 wt%, preferably 0.08 to 1.0 wt%, for example, but not limited to, 0.08 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, and any range between any two values.

[0009] Furthermore, the reaction conditions in the hydrogenation conversion reaction zone are as follows: reaction temperature of 300–450°C, reaction pressure of 2.0–8.0 MPa, and total liquid hourly space velocity of 0.1–5.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 100:1 to 2000:1.

[0010] Furthermore, catalyst A and catalyst B can be packed in one or two reactors. The volume ratio of catalyst A to catalyst B is 10:1 to 1:2, for example, but not limited to, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, and any range between any two values.

[0011] Further, catalyst A comprises ZSM-5 molecular sieve, macroporous alumina, and an active metal component, wherein the active metal component is selected from Group VIB and Group VIII metals. Further, the Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel.

[0012] Further, in catalyst A, based on the weight of the catalyst, the content of ZSM-5 molecular sieve is 50wt% to 80wt%, the content of macroporous alumina is 15wt% to 50wt%, and the total content of Group VIB and Group VIII metals as oxides is 0.5wt% to 8.0wt%; preferably, based on the weight of the catalyst, the content of ZSM-5 molecular sieve is 50wt% to 75wt%, the content of macroporous alumina is 20wt% to 40wt%, and the total content of Group VIB and Group VIII metals as oxides is 1.0wt% to 8.0wt%.

[0013] Furthermore, in catalyst A, the mass ratio of Group VIB metal (calculated as oxide) to Group VIII metal (calculated as oxide) is 2.0 to 6.0.

[0014] Furthermore, in catalyst A, the macroporous alumina has a pore volume of 0.8–1.5 cm³. 3 / g, specific surface area of ​​200-400m² 2 / g. The pore volume of the ZSM-5 molecular sieve is 0.18–0.26 cm³. 3 / g, specific surface area of ​​300-450m² 2 / g, the silicon-aluminum molar ratio SiO2:Al2O3 is 20-100.

[0015] Furthermore, the catalyst A is prepared as follows:

[0016] (1) ZSM-5 molecular sieve was mixed with macroporous alumina, shaped, and calcined to obtain a catalyst support;

[0017] (2) The support obtained in step (1) is impregnated with an impregnation solution containing Group VIB metals and Group VIII metals, and then calcined to obtain catalyst A.

[0018] Furthermore, in step (1), the mass ratio of ZSM-5 molecular sieve to macroporous alumina is 5.0 to 1.0.

[0019] Furthermore, in step (1), the pore volume of the macroporous alumina is 0.8–1.5 cm³. 3 / g, specific surface area of ​​200-400m² 2 / g. The pore volume of the ZSM-5 molecular sieve is 0.18–0.26 cm³. 3 / g, specific surface area of ​​300-450m² 2 / g, the silicon-aluminum molar ratio SiO2:Al2O3 is 20-100.

[0020] Further, in step (1), the molding can be carried out using conventional methods in the art, such as extrusion molding. During the molding process, conventional molding aids can be added, such as at least one of extrusion aids, pectinic acids, and binders; the extrusion aid can be guar gum powder, the pectinic acid can be at least one of citric acid and nitric acid, preferably at least one of citric acid and nitric acid; the binder can be aluminum sol or silica sol prepared from porous alumina, preferably aluminum sol. Further, the amount of molding aid added accounts for 1.0% to 5.0% of the total mass of the obtained catalyst.

[0021] Further, in step (1), after molding, the catalyst support is dried and calcined to obtain the catalyst support. The drying temperature is 100℃~150℃, and the drying time is 2~4h; the calcination temperature is 400℃~600℃, and the calcination time is 3~5h.

[0022] Further, in step (2), the impregnation solution containing Group VIB metal and Group VIII metal is provided with one or more of tungsten salt or molybdenum salt as the source of Group VIB metal and one or more of nickel salt or cobalt salt as the source of Group VIII metal.

[0023] Further, in step (2), the impregnation solution containing Group VIB metals and Group VIII metals contains Group VIB metals as oxides at a mass content of 3.0 to 30.0 g / 100 mL and Group VIII metals as oxides at a mass content of 1.0 to 10.0 g / 100 mL.

[0024] Furthermore, in step (2), the impregnation is preferably saturated impregnation.

[0025] Furthermore, the catalyst B comprises modified ZSM-5 molecular sieve, Group VIB metal and Group VIII metal, and macroporous alumina.

[0026] Further, based on the weight of the catalyst, the content of modified ZSM-5 molecular sieve is 35wt%–80wt%, the content of macroporous alumina is 20wt%–65wt%, and the total content of Group VIB and Group VIII metals (based on oxides) is 0.5wt%–8.0wt%. Preferably, based on the weight of catalyst B, the content of modified ZSM-5 molecular sieve is 40wt%–75wt%, the content of macroporous alumina is 30wt%–50wt%, and the total content of Group VIB and Group VIII metals (based on oxides) is 1.0wt%–7.0wt%. Further, the Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel. Further, in the macroporous alumina loaded with Group VIB and Group VIII metals, the mass ratio of Group VIB metals (based on oxides) to Group VIII metals (based on oxides) is 2.0–6.0.

[0027] Furthermore, the mesoporous pore volume of the modified ZSM-5 molecular sieve accounts for 50% to 80% of the total pore volume, preferably 60% to 70%.

[0028] Furthermore, the preparation method of the catalyst B includes the following steps:

[0029] (I) Pore expansion treatment of ZSM-5 molecular sieve;

[0030] (II) Remove non-framework aluminum from step (I) to obtain modified ZSM-5 molecular sieve;

[0031] (III) The modified ZSM-5 molecular sieve obtained in step (II) is mixed with macroporous alumina, shaped, and calcined to obtain a catalyst support;

[0032] (IV) The catalyst support obtained in step (III) is impregnated with an impregnation solution containing Group VIB metals and Group VIII metals, and then calcined to obtain catalyst B.

[0033] Further, in step (I), the ZSM-5 molecular sieve can be a commercially available product or a microporous hydrogen-form ZSM-5 molecular sieve prepared according to existing technology. The properties of the ZSM-5 molecular sieve are as follows: SiO2 / Al2O3 molar ratio 20–100, specific surface area 300–450 m² / g. 2 / g, pore volume 0.15~0.20cm³ 3 / g.

[0034] Further, in step (I), the pore-expanding treatment can be one or more of acid treatment, alkali treatment, and hydrothermal treatment, preferably hydrothermal treatment. The temperature of the hydrothermal treatment is 400-600℃, preferably 500-600℃, the time is 0.5-5h, preferably 1-2h, and the pressure is 0.05-0.5MPa, preferably 0.1-0.3MPa.

[0035] Further, in step (II), the method for removing non-skeletal aluminum can be a buffer solution method. The buffer solution used is one or more of oxalic acid-ammonium oxalate solution and acetate-ammonium acetate solution. The pH value of the buffer solution is 4.5–6.5, preferably 5.0–6.0. ​​The molar concentration of the organic acid in the buffer solution is 0.1–1.0 mol / L. The volume ratio of the buffer solution to the mass ratio of the molecular sieve obtained in step (I) is 3:1–10:1.

[0036] Further, in step (II), the specific process for removing non-skeletal aluminum is as follows: the molecular sieve obtained in step (I) is mixed with a buffer solution and stirred, the treatment temperature is 40-80℃, the treatment time is 0.5-3h, and then solid-liquid separation is performed (e.g., vacuum filtration); and the above operation is repeated 2-4 times.

[0037] Furthermore, in step (III), the pore volume of the macroporous alumina is 0.8–1.5 cm³. 3 / g, specific surface area of ​​200-400m² 2 / g.

[0038] Furthermore, in step (III), the mass ratio of macroporous alumina to modified ZSM-5 molecular sieve is 0.2 to 1.5.

[0039] Further, in step (III), the molding can be carried out using conventional methods in the art, such as extrusion molding. Conventional molding aids can be added during the molding process, such as at least one of extrusion aids and pectinic acids; the extrusion aid can be guar gum powder, and the pectinic acid can be at least one of citric acid and nitric acid, preferably citric acid and nitric acid. The amount of molding aid added accounts for 1.0% to 5.0% of the mass of the hydroconversion catalyst.

[0040] Further, in step (IV), in the impregnation solution containing Group VIB and Group VIII metals, the Group VIB metal source is one or more of tungsten salts or molybdenum salts, and the Group VIII metal source is one or more of nickel salts or cobalt salts. Further, in the impregnation solution containing Group VIB and Group VIII metals, the mass content of the Group VIB metal (calculated as oxide) is 3.0–30.0 g / 100 mL, and the mass content of the Group VIII metal (calculated as oxide) is 1.0–10.0 g / 100 mL.

[0041] Further, in step (III), after molding, the catalyst is dried and calcined to obtain catalyst B. The drying temperature is 100℃~150℃, and the drying time is 2~4h; the calcination temperature is 400℃~600℃, and the calcination time is 3~5h.

[0042] Further, in step (IV), after impregnation, the catalyst is dried and calcined to obtain catalyst B. The drying temperature is 100℃~150℃, and the drying time is 2~4h; the calcination temperature is 400℃~600℃, and the calcination time is 3~5h.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. The processing method of the present invention introduces a small amount of olefin-rich stream, in which the olefin can rapidly react with the acidic center of the catalyst to generate carbocations. After the generated carbocations complete the reaction, they continue to propagate, so that the reaction continues and acts as an initiator.

[0045] 2. This invention employs a gradation system of catalyst A and catalyst B. Catalyst A uses ZSM-5 molecular sieve with a higher total acid content and higher catalyst activity, making it suitable for the efficient conversion of high-isomeric hydrocarbon content streams in the upper part of the reactor. As the reaction proceeds, the content of isomeric hydrocarbons in the stream entering the lower bed of the reactor decreases. Catalyst B uses modified ZSM-5 molecular sieve with a higher mesopore content, promoting the contact and reaction between isomeric hydrocarbons and acid centers in the feedstock, and improving the conversion selectivity of isomeric hydrocarbons. Detailed Implementation

[0046] The following examples and comparative examples further illustrate the role and effect of the technical solution of the present invention, but the following examples do not constitute a limitation on the scope of protection of the present invention.

[0047] In this invention, the specific surface area, pore volume, and pore distribution were measured using the following method: an ASAP 2420 cryogenic liquid nitrogen physical adsorption instrument manufactured by Microlithics, Inc. was used, with a pretreatment temperature of 300°C and a pretreatment time of 4 hours.

[0048] In this invention, the amount of carbon deposited on the catalyst is measured by an infrared sulfur and carbon analyzer. A high-frequency infrared carbon and sulfur analyzer of EMIA-820V from HORIBA Corporation of Japan is used. The high-frequency induction heating furnace has an output power of 2300W and a frequency of 20MHz. The sample heating temperature is 1800℃. The carbon content of the catalyst is calculated based on the peak area of ​​the vibrational spectrum of CO2 generated by the combustion of carbon deposits.

[0049] In this invention, the pyridine adsorption amount in the catalyst is measured by a pyridine infrared spectroscopy device. The powdered catalyst is compressed into tablets, vacuumed, and degassed at 450°C for 2 hours. After the temperature drops to room temperature, the kinetic diameter is... Pyridine molecules were used as probe molecules for adsorption, and then the temperature was raised to 380℃ to measure the infrared spectrum of chemical desorption, and the amount of pyridine adsorbed was calculated. The unit is mmol / g.

[0050] In this invention, unless otherwise specified, all percentages (%) in the embodiments and comparative examples refer to mass fractions.

[0051] In this invention, the macroporous alumina involved in the embodiments and comparative examples is a commercially available product with a pore volume of 1.1 cm³. 3 / g, specific surface area is 350cm² 2 / g.

[0052] In this invention, the unmodified ZSM-5 molecular sieve involved in the embodiments and comparative examples has a pore volume of 0.18 cm³. 3 / g, specific surface area is 191cm³ 2 / g, the silicon-aluminum molar ratio SiO2:Al2O3 is 55.

[0053] In this invention, the conversion rate of light naphtha isohydrocarbons, the selectivity of isohydrocarbon conversion, and the proportion of n-alkanes in the products are calculated as follows:

[0054] Isomer hydrocarbon conversion rate = (mass of isomer C5 and C6 hydrocarbons in feedstock - mass of isomer C5 and C6 hydrocarbons in product) / (mass of isomer C5 and C6 hydrocarbons in feedstock) × 100%;

[0055] Isomer hydrocarbon conversion selectivity = (mass of isomer C5 and C6 hydrocarbons in feedstock - mass of isomer C5 and C6 hydrocarbons in product) / (mass of C5 and C6 hydrocarbons in feedstock - mass of C5 and C6 hydrocarbons in product) × 100%;

[0056] The proportion of n-alkane = mass of n-alkane in the product / total mass of the product × 100%, where n-alkane includes ethane, propane, n-butane, n-pentane and n-hexane.

[0057] In this invention, in each example, the nickel source used is nickel nitrate, and the tungsten source is ammonium metatungstate.

[0058] Example 1

[0059] Take 100g of commercially available ZSM-5 molecular sieve and 45g of macroporous alumina, add 70g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain CAT-A-1S.

[0060] Take 100g of CAT-A-1S and immerse it in 200mL of an aqueous solution containing 1.0g / 100mL of nickel and 5.0g / 100mL of tungsten (based on oxides) for 2h. After filtration, dry at 120℃ for 3h and calcine at 500℃ for 4h, CAT-A-1 is obtained. Its properties are shown in Table 1.

[0061] Example 2

[0062] Take 100g of commercially available ZSM-5 molecular sieve and 80g of macroporous alumina, add 85g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain CAT-A-2S.

[0063] Take 100g of CAT-A-2S and immerse it in 200mL of an aqueous solution containing 2.0g / 100mL of nickel and 10.0g / 100mL of tungsten (based on oxides) for 2h. After filtration, dry at 120℃ for 3h and calcine at 500℃ for 4h, CAT-A-2 is obtained. Its properties are shown in Table 1.

[0064] Example 3

[0065] Take 100g of commercially available ZSM-5 molecular sieve and 60g of macroporous alumina, add 80g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain CAT-A-3S.

[0066] Take 100g of CAT-A-3S and immerse it in 200mL of an aqueous solution containing 1.0g / 100mL of nickel and 5.0g / 100mL of tungsten (based on oxides) for 2h. After filtration, dry at 120℃ for 3h and calcine at 500℃ for 4h, CAT-A-3 is obtained. Its properties are shown in Table 1.

[0067] Comparative Example 1

[0068] Take 30g of commercially available ZSM-5 molecular sieve and 100g of macroporous alumina, add 80g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain DCAT-A-1S.

[0069] 100g of DCAT-A-1S was impregnated in 200mL of an aqueous solution containing 1.0g / 100mL nickel and 5.0g / 100mL tungsten (based on oxides) for 2 hours. After filtration, drying at 120℃ for 3 hours, and calcination at 500℃ for 4 hours, DCAT-A-1 was obtained. Its properties are shown in Table 1.

[0070] Comparative Example 2

[0071] Take 100g of commercially available ZSM-5 molecular sieve and 10g of macroporous alumina, add 40g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain DCAT-A-2S.

[0072] 100g of DCAT-A-2S was impregnated in 200mL of an aqueous solution containing 2.0g / 100mL nickel and 10.0g / 100mL tungsten (based on oxides) for 2 hours. After filtration, drying at 120℃ for 3 hours, and calcination at 500℃ for 4 hours, DCAT-A-2 was obtained. Its properties are shown in Table 1.

[0073] Table 1. Catalyst properties of examples and comparative examples

[0074]

[0075] Example 4

[0076] Preparation of modified ZSM-5 molecular sieve (denoted as Z-1): Commercially available ZSM-5 molecular sieve was placed in a hydrothermal treatment furnace and treated at 450℃ and 0.1MPa steam pressure for 2 hours to obtain modified ZSM-5 molecular sieve Z-1, with a mesopore volume of 0.09 cm³. 3 / g, total pore volume is 0.17cm³ 3 / g, mesoporous pore volume accounts for 52% of the total pore volume.

[0077] Take 100g of Z-1 molecular sieve and 100g of macroporous alumina, add 110g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain CAT-B-1S.

[0078] Take 100g of CAT-B-1S and immerse it in 200mL of an aqueous solution containing 1.0g / 100mL of nickel and 5.0g / 100mL of tungsten (based on oxides) for 2 hours. After filtration, dry at 120℃ for 3 hours and calcine at 500℃ for 4 hours, CAT-B-1 is obtained. Its properties are shown in Table 2.

[0079] Example 5

[0080] Preparation of modified ZSM-5 molecular sieve (denoted as Z-2): Commercially available ZSM-5 molecular sieve was placed in a hydrothermal treatment furnace and treated at 500℃ and 0.1MPa steam pressure for 2 hours to obtain modified ZSM-5 molecular sieve Z-2, with a mesopore volume of 0.11 cm³. 3 / g, total pore volume is 0.17cm³ 3 / g, mesoporous pore volume accounts for 65% of the total pore volume.

[0081] Take 100g of Z-2 molecular sieve and 60g of macroporous alumina, add 80g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain CAT-B-2S.

[0082] Take 100g of CAT-B-2S and immerse it in 200mL of an aqueous solution containing 1.5g / 100mL of nickel and 7.5g / 100mL of tungsten (based on oxides) for 2 hours. After filtration, dry at 120℃ for 3 hours and calcine at 500℃ for 4 hours to obtain CAT-B-2. Its properties are shown in Table 2.

[0083] Example 6

[0084] Preparation of modified ZSM-5 molecular sieve (denoted as Z-3): Commercially available ZSM-5 molecular sieve (silicon-to-aluminum ratio: 55) was placed in a hydrothermal treatment furnace and treated at 600℃ and 0.1MPa steam pressure for 2 hours to obtain modified ZSM-5 molecular sieve Z-3, with a mesopore volume of 0.14 cm³. 3 / g, total pore volume is 0.18cm³ 3 / g, mesoporous pore volume accounts for 78% of the total pore volume.

[0085] Take 100g of Z-3 molecular sieve and 100g of macroporous alumina, add 110g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain CAT-B-3S.

[0086] 100g of CAT-B-3S was impregnated in 200mL of an aqueous solution containing 1.0g / 100mL nickel and 5.0g / 100mL tungsten (based on oxides) for 2 hours. After filtration, drying at 120℃ for 3 hours, and calcination at 500℃ for 4 hours, CAT-B-3 was obtained. Its properties are shown in Table 2.

[0087] Comparative Example 3

[0088] Preparation of modified ZSM-5 molecular sieve (denoted as DZ-1): Commercially available ZSM-5 molecular sieve was placed in a hydrothermal treatment furnace and treated at 300℃ and 0.1MPa steam pressure for 2 hours to obtain modified ZSM-5 molecular sieve DZ-1, with a mesopore volume of 0.05 cm³. 3 / g, total pore volume is 0.17cm³ 3 / g, mesoporous pore volume accounts for 29% of the total pore volume.

[0089] Take 100g of DZ-1 molecular sieve and 60g of macroporous alumina, add 80g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain DCAT-B-1S.

[0090] 100g of DCAT-B-1S was impregnated in 200mL of an aqueous solution containing 2.0g / 100mL of nickel and 10.0g / 100mL of tungsten (based on oxides) for 2 hours. After filtration, drying at 120℃ for 3 hours, and calcination at 500℃ for 4 hours, DCAT-B-1 was obtained. Its properties are shown in Table 2.

[0091] Comparative Example 4

[0092] Preparation of modified ZSM-5 molecular sieve (denoted as DZ-2): Commercially available ZSM-5 molecular sieve was placed in a hydrothermal treatment furnace and treated at 650℃ and 0.1MPa steam pressure for 2 hours to obtain modified ZSM-5 molecular sieve DZ-2, with a mesopore volume of 0.16 cm³. 3 / g, total pore volume is 0.19cm³ 3 / g, mesoporous pore volume accounts for 84% of the total pore volume.

[0093] Take 60g of DZ-2 molecular sieve and 100g of macroporous alumina, add 85g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder, then crush, extrude into strips, dry at 120℃ for 3h, and calcine at 500℃ for 4h to obtain DCAT-B-2S.

[0094] 100g of DCAT-B-2S was impregnated in 200mL of an aqueous solution containing 1.0g / 100mL nickel and 5.0g / 100mL tungsten (based on oxides) for 2 hours. After filtration, drying at 120℃ for 3 hours, and calcination at 500℃ for 4 hours, DCAT-B-2 was obtained. Its properties are shown in Table 2.

[0095] Table 2. Catalyst properties of examples and comparative examples

[0096]

[0097] Example 7

[0098] 8.0 mL of catalyst CAT-A-1 was placed in the first reactor of the fixed-bed reactor, and 2.0 mL of catalyst CAT-B-1 was placed in the second reactor. Hydrocracking light naphtha mixed with olefin-rich components (olefin content 0.08 wt%) was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts CAT-A-1 and CAT-B-1. The reaction conditions were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and reaction temperature 400℃. The properties of the feedstock are shown in Table 3. After 160 h of operation, the isomeric hydrocarbon conversion rate, isomeric hydrocarbon conversion selectivity, product n-hydrocarbon content, and catalyst carbon deposition are shown in Table 4.

[0099] Example 8

[0100] 9.0 mL of catalyst CAT-A-2 was placed in the first reactor of the fixed-bed reactor, and 1.0 mL of catalyst CAT-B-2 was placed in the second reactor. Hydrocracking light naphtha (olefin content 0.5 wt%) mixed with olefin-rich components was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts CAT-A-2 and CAT-B-2. The reaction conditions were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and reaction temperature 400℃. The properties of the feedstock are shown in Table 3. After 160 h of operation, the isomeric hydrocarbon conversion rate, isomeric hydrocarbon conversion selectivity, product n-hydrocarbon content, and catalyst carbon deposition are shown in Table 4.

[0101] Example 9

[0102] 4.0 mL of catalyst CAT-A-3 was placed in the first reactor of the fixed-bed reactor, and 6.0 mL of catalyst CAT-B-3 was placed in the second reactor. Hydrocracking light naphtha (olefin content 0.9 wt%) mixed with olefin-rich components was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts CAT-A-3 and CAT-B-3. The reaction conditions were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and reaction temperature 400℃. The properties of the feedstock are shown in Table 3. After 160 h of operation, the isomeric hydrocarbon conversion rate, isomeric hydrocarbon conversion selectivity, product n-hydrocarbon content, and catalyst carbon deposition are shown in Table 4.

[0103] Comparative Example 5

[0104] 4.0 mL of catalyst CAT-A-3 was placed in the first reactor of the fixed-bed reactor, and 6.0 mL of catalyst CAT-B-3 was placed in the second reactor. Hydrocracking light naphtha was introduced into the reactors at a flow rate of 10 mL / h to react with the catalysts CAT-A-3 and CAT-B-3. The reaction conditions were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and reaction temperature 400℃. The properties of the feedstock are shown in Table 3. After 160 h of operation, the isomeric hydrocarbon conversion rate, isomeric hydrocarbon conversion selectivity, product n-hydrocarbon content, and catalyst carbon deposition are shown in Table 5.

[0105] Comparative Example 6

[0106] 4.0 mL of catalyst CAT-A-3 was placed in the first reactor of the fixed-bed reactor, and 9.0 mL of catalyst CAT-B-3 was placed in the second reactor. Hydrocracking light naphtha (olefin content 0.9 wt%) mixed with olefin-rich components was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts CAT-A-3 and CAT-B-3. The reaction conditions were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and reaction temperature 400℃. The properties of the feedstock are shown in Table 3. After 160 h of operation, the isomeric hydrocarbon conversion rate, isomeric hydrocarbon conversion selectivity, product n-hydrocarbon content, and catalyst carbon deposition are shown in Table 5.

[0107] Comparative Example 7

[0108] 10.0 mL of catalyst CAT-A-3 was placed in the first reactor of the fixed-bed reactor, and 0.1 mL of catalyst CAT-B-3 was placed in the second reactor. Hydrocracking light naphtha (olefin content 0.9 wt%) mixed with olefin-rich components was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts CAT-A-3 and CAT-B-3. The reaction conditions were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and reaction temperature 400℃. The properties of the feedstock are shown in Table 3. After 160 h of operation, the isomeric hydrocarbon conversion rate, isomeric hydrocarbon conversion selectivity, product n-hydrocarbon content, and catalyst carbon deposition are shown in Table 5.

[0109] Comparative Example 8

[0110] 4.0 mL of catalyst DCAT-A-1 was placed in the first reactor of the fixed-bed reactor, and 6.0 mL of catalyst DCAT-B-1 was placed in the second reactor. Hydrocracking light naphtha (olefin content 0.9 wt%) mixed with olefin-rich components was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts DCAT-A-1 and DCAT-B-1. The reaction conditions were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and reaction temperature 400℃. The properties of the feedstock are shown in Table 3. After 160 h of operation, the isomeric hydrocarbon conversion rate, isomeric hydrocarbon conversion selectivity, product n-hydrocarbon content, and catalyst carbon deposition are shown in Table 5.

[0111] Comparative Example 9

[0112] 4.0 mL of catalyst DCAT-A-2 was placed in the first reactor of the fixed-bed reactor, and 6.0 mL of catalyst DCAT-B-2 was placed in the second reactor. Hydrocracking light naphtha (olefin content 0.9 wt%) mixed with olefin-rich components was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts DCAT-A-2 and DCAT-B-2. The reaction conditions were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and reaction temperature 400℃. The properties of the feedstock are shown in Table 3. After 160 h of operation, the isomeric hydrocarbon conversion rate, isomeric hydrocarbon conversion selectivity, product n-hydrocarbon content, and catalyst carbon deposition are shown in Table 5.

[0113] Comparative Example 10

[0114] 4.0 mL of catalyst CAT-A-3 was placed in the first reactor of the fixed-bed reactor, and 6.0 mL of catalyst CAT-B-3 was placed in the second reactor. Hydrocracking light naphtha (olefin content 2.0 wt%) mixed with olefin-rich components was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts CAT-A-3 and CAT-B-3. The reaction conditions were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and reaction temperature 400℃. The properties of the feedstock are shown in Table 3. After 160 h of operation, the isomeric hydrocarbon conversion rate, isomeric hydrocarbon conversion selectivity, product n-hydrocarbon content, and catalyst carbon deposition are shown in Table 4.

[0115] Table 3 Hydrocarbon composition of hydrocracking light naphtha

[0116] Hydrocarbon composition, % Isobutane 3.3 n-Butane 3.7 isopentane 57.1 n-Pentane 11.7 2,2-Dimethylbutane 0.6 Cyclopentane 1.6 2,3-Dimethylbutane 3.3 2-Methylpentane 11.0 3-Methylpentane 5.3 n-Hexane 1.1 Methylcyclopentane 1.3 n-Hydrocarbon ratio, % 16.5 Initial boiling point, ℃ 18.7 Final boiling point, ℃ 67.4

[0117] Table 4 Evaluation results of the catalysts in the examples

[0118]

[0119] Table 5 Evaluation results of the comparative example catalysts

[0120]

[0121]

[0122] 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 hydrocracking light naphtha, the conversion method comprising: Hydrocracked light naphtha mixed with olefin-rich components is passed through a hydroconversion reaction zone to obtain the converted light naphtha product. The hydrogenation conversion reaction zone is sequentially filled with catalyst A and catalyst B along the material flow direction; wherein, the pyridine adsorption capacity (380℃) of catalyst A is 0.30-0.40 mmol / g, and the micropore volume of catalyst B accounts for 10%-30% of the total pore volume, preferably 15-25%.

2. The conversion method according to claim 1, characterized in that, The initial boiling point of the hydrocracked light naphtha is 15–30°C, and the final boiling point is 60–90°C. And / or, the C5-C6 isoalkanes in the hydrocracking light naphtha are 70wt% to 95wt%, preferably 75wt% to 85wt%.

3. The conversion method according to claim 1, characterized in that, The olefin-rich component is selected from either pure olefin substances or olefin-rich light naphtha. Preferably, the pure olefin is selected from at least one of butene, pentene, and hexene; the olefin-rich light naphtha is one or more of catalytic cracking light naphtha and delayed coking light naphtha. Preferably, the mass content of C4-C6 olefins in the catalytic cracking light naphtha is 40wt% to 60wt%, and the mass content of C4-C6 olefins in the delayed coking light naphtha is 30wt% to 50wt%.

4. The conversion method according to claim 1, characterized in that, The olefin content in the hydrocracked light naphtha mixed with olefin-rich components is 0.03–1.5 wt%, preferably 0.08–1.0 wt%.

5. The conversion method according to claim 1, characterized in that, The reaction conditions in the hydroconversion reaction zone are: reaction temperature of 300-450℃, reaction pressure of 2.0-8.0MPa, and hydrogen-to-oil volume ratio of 100:1-2000:

1.

6. The conversion method according to claim 1, characterized in that, The volume ratio of catalyst A to catalyst B is 10:1 to 1:

2.

7. The conversion method according to claim 1, characterized in that, Catalyst A comprises ZSM-5 molecular sieve, macroporous alumina, and an active metal component, wherein the active metal component is selected from Group VIB metals and Group VIII metals; preferably, the Group VIB metal is molybdenum and / or tungsten, and the Group VIII metal is cobalt and / or nickel.

8. The conversion method according to claim 1 or 7, characterized in that, In catalyst A, based on the weight of the catalyst, the content of ZSM-5 molecular sieve is 50wt% to 80wt%, the content of macroporous alumina is 15wt% to 50wt%, and the total content of Group VIB and Group VIII metals as oxides is 0.5wt% to 8.0wt%; preferably, based on the weight of the catalyst, the content of ZSM-5 molecular sieve is 50wt% to 75wt%, the content of macroporous alumina is 20wt% to 40wt%, and the total content of Group VIB and Group VIII metals as oxides is 1.0wt% to 8.0wt%.

9. The conversion method according to claim 1, characterized in that, Catalyst B comprises modified ZSM-5 molecular sieve, Group VIB metal and Group VIII metal, and macroporous alumina; preferably, the Group VIB metal is molybdenum and / or tungsten, and the Group VIII metal is cobalt and / or nickel.

10. The conversion method according to claim 1 or 9, characterized in that, In catalyst B, based on the weight of catalyst B, the content of modified ZSM-5 molecular sieve is 35wt% to 80wt%, the content of macroporous alumina is 20wt% to 65wt%, and the total content of Group VIB and Group VIII metals as oxides is 0.5wt% to 8.0wt%; preferably, based on the weight of catalyst B, the content of modified ZSM-5 molecular sieve is 40wt% to 75wt%, the content of macroporous alumina is 30wt% to 50wt%, and the total content of Group VIB and Group VIII metals as oxides is 1.0wt% to 7.0wt%.

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