Catalytic cracking light naphtha processing method

Abstract

The invention discloses a catalytic cracking light naphtha processing method. The method comprises the following steps: catalytic cracking light naphtha sequentially passes through a hydrofining reaction zone, a first hydro-conversion reaction zone and a second hydro-conversion reaction zone to obtain a converted light naphtha product; wherein the volume ratio of the first hydro-conversion catalyst filled in the first hydro-conversion reaction zone to the second hydro-conversion catalyst filled in the second hydro-conversion reaction zone is (10: 1)-(1: 2). The olefin in the product obtained by treating the catalytic cracking light naphtha through the method is completely saturated, and the content of normal hydrocarbon is increased.

Description

Technical Field

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

[0002] The products obtained from catalytic cracking include dry gas, liquefied petroleum gas (LPG), light naphtha, gasoline, diesel, light cycle oil, and catalytic slurry, etc. Light naphtha is mainly composed of C5 and C6 alkanes and olefins, with olefins accounting for over 30%. From a structural perspective, isomeric hydrocarbons constitute a relatively high proportion, exceeding 70 wt%.

[0003] Increasing ethylene production is an important direction for the development of the petrochemical industry. One way to expand ethylene feedstock sources and increase production is to use catalytic cracking light naphtha as a feedstock for steam cracking to produce ethylene. However, using catalytic cracking light naphtha as ethylene feedstock presents two problems: First, the high olefin content (greater than 30 wt%) in catalytic cracking light naphtha makes it prone to coking, which shortens the decoking cycle in the steam cracking ethylene unit and affects its economic efficiency. Second, the high isomeric hydrocarbon content (over 50 wt%) in catalytic cracking light naphtha results in a lower yield of trienes in the ethylene unit, reducing its economic efficiency. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for processing catalytic cracking light naphtha. The product obtained by this method has fully saturated olefins and increased n-hydrocarbon content, which can significantly improve the yield of ethylene and trienes when used as feedstock for ethylene production via steam cracking.

[0005] The first aspect of the present invention provides a method for processing catalytic cracking light naphtha, comprising: passing catalytic cracking light naphtha sequentially through a hydrorefining reaction zone, a first hydroconversion reaction zone, and a second hydroconversion reaction zone to obtain a converted light naphtha product; wherein the volume ratio of the first hydroconversion catalyst packed in the first hydroconversion reaction zone to the second hydroconversion catalyst packed in the second hydroconversion reaction zone is 10:1 to 1:2.

[0006] Furthermore, the volume ratio of the first hydroconversion catalyst and the second hydroconversion catalyst is, 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.

[0007] Further, the initial boiling point of the catalytic cracking light naphtha is 15–30°C, and the final boiling point is 60–90°C. The catalytic cracking light naphtha contains 30 wt%–60 wt% olefins and 30 wt%–66 wt% alkanes, based on a total weight of 100 wt% of the catalytic cracking light naphtha. The catalytic cracking light naphtha contains 50 wt%–90 wt% C5-C6 isomers, preferably 60 wt%–80 wt%, based on a total weight of 100 wt% of the catalytic cracking light naphtha; wherein, the C5-C6 isomer content refers to the sum of the proportions of C5-C6 isomers in the alkanes and the proportions of C5-C6 isomers in the olefins of the light naphtha.

[0008] Furthermore, the hydrorefining reaction zone is filled with a hydrorefining catalyst, which can be a conventional hydrorefining agent in the art, generally comprising a hydrorefining active metal component and a support. The hydrorefining active metal is a Group VIB metal or a Group VIII metal; the Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel. The support is an alumina support. Generally, based on the weight of the catalyst, the content of the Group VIB metal (calculated as oxide) is 20%–30%, and the content of the Group VIII metal (calculated as oxide) is 2%–10%. The hydrorefining catalyst can be an FF series catalyst developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., such as FF-66.

[0009] Furthermore, the refined naphtha obtained after hydrorefining contains 0.05 wt% to 1.5 wt% of olefins, preferably 0.08 wt% to 1.0 wt%, for example, but not limited to, 0.09 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.55 wt%, 0.6 wt%, 0.65 wt%, 0.7 wt%, 0.75 wt%, 0.8 wt%, 0.85 wt%, 0.9 wt%, 0.95 wt%, 1.0 wt%, and any range between any two values.

[0010] Furthermore, the hydrorefining conditions are: reaction temperature 150–250°C, reaction pressure 2–8 MPa, and liquid hourly space velocity (LHSV) 0.1–5.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 100:1 to 2000:1.

[0011] Furthermore, the hydrogenation conversion conditions are: reaction temperature 300–450°C, reaction pressure 2–8 MPa, and liquid hourly space velocity (LHSV) 0.1–5.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 100:1 to 2000:1.

[0012] Further, the first hydroconversion catalyst 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.

[0013] Further, in the first hydroconversion catalyst, 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%.

[0014] Furthermore, in the first hydroconversion catalyst, the mass ratio of Group VIB metal (calculated as oxide) to Group VIII metal (calculated as oxide) is 2.0 to 6.0.

[0015] Furthermore, in the first hydroconversion catalyst, 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.

[0016] Furthermore, the pyridine adsorption capacity (380℃) of the first hydroconversion catalyst is 0.30–0.40 mmol / g.

[0017] Furthermore, the preparation method of the first hydroconversion catalyst is as follows:

[0018] (1) ZSM-5 molecular sieve was mixed with macroporous alumina, shaped, and calcined to obtain a catalyst support;

[0019] (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 the first hydrogenation conversion catalyst.

[0020] Furthermore, in step (1), the mass ratio of ZSM-5 molecular sieve to macroporous alumina is 5.0 to 1.0.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] Furthermore, in step (2), the impregnation is preferably saturated impregnation.

[0027] Furthermore, the second hydroconversion catalyst comprises modified ZSM-5 molecular sieve, Group VIB metal and Group VIII metal, and macroporous alumina.

[0028] Further, based on the weight of the catalyst, the modified ZSM-5 molecular sieve content is 35wt%–80wt%, the macroporous alumina content 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 the second hydroconversion catalyst, the modified ZSM-5 molecular sieve content is 45wt%–75wt%, the macroporous alumina content 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.

[0029] 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%. The microporous pore volume of the second hydroconversion catalyst accounts for 10% to 30% of the total pore volume, preferably 15% to 25%.

[0030] Furthermore, the pore volume of the macroporous alumina is 0.8–1.5 cm³. 3 / g, specific surface area of ​​200-400m² 2 / g.

[0031] Furthermore, the preparation method of the second hydrogenation conversion catalyst includes the following steps:

[0032] (I) Pore expansion treatment of ZSM-5 molecular sieve;

[0033] (II) Remove non-framework aluminum from step (I) to obtain modified ZSM-5 molecular sieve;

[0034] (III) The modified ZSM-5 molecular sieve obtained in step (II) is mixed with macroporous alumina, shaped, and calcined to obtain a catalyst support;

[0035] (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 the second hydrogenation conversion catalyst.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Furthermore, in step (III), the mass ratio of macroporous alumina to modified ZSM-5 molecular sieve is 0.2 to 1.5.

[0042] 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.

[0043] 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.

[0044] Further, in step (III), after molding, the catalyst is dried and calcined to obtain the second hydroconversion catalyst. 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.

[0045] Further, in step (IV), after impregnation, the catalyst is dried and calcined to obtain the second hydroconversion catalyst. 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.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. This invention achieves the saturation and conversion of catalytic cracking light naphtha through a combination of hydrorefining and hydroconversion processes, yielding a hydrocarbon stream product that is free of olefins and has an increased content of n-alkanes. By controlling the olefin content in the refined naphtha stream, trace amounts of olefins act as initiators, rapidly reacting with the acidic centers of the catalyst to generate carbocations. These carbocations continue to propagate after completing the reaction, allowing the reaction to proceed continuously, thereby improving the conversion capacity of the light naphtha conversion stage.

[0048] 2. The hydroconversion reaction zone of this invention employs a catalyst gradation system consisting of a first hydroconversion catalyst and a second hydroconversion catalyst. The modified ZSM-5 molecular sieve used in the first hydroconversion catalyst has a higher 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 isomeric hydrocarbon content in the stream entering the lower bed of the reactor decreases. The modified ZSM-5 molecular sieve used in the second hydroconversion catalyst has 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

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] In this invention, unless otherwise specified, all percentages (%) in the embodiments and comparative examples refer to mass fractions.

[0054] 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.

[0055] In this invention, the ZSM-5 molecular sieve pore volume in the hydroconversion catalysts involved in the examples and comparative examples is 0.18 cm³. 3 / g, specific surface area is 191cm³ 2 / g, the silicon-aluminum molar ratio SiO2:Al2O3 is 55.

[0056] 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:

[0057] 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%;

[0058] 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%;

[0059] 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.

[0060] In this invention, in each example, the nickel source used is nickel nitrate, and the tungsten source is ammonium metatungstate.

[0061] The hydrorefining catalyst involved in the embodiments and comparative examples of this invention is FF-66, a commercial catalyst developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd.

[0062] Example 1

[0063] 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.

[0064] 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.

[0065] Example 2

[0066] 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.

[0067] 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.

[0068] Example 3

[0069] 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.

[0070] 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.

[0071] Comparative Example 1

[0072] 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.

[0073] 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.

[0074] Comparative Example 2

[0075] 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.

[0076] 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.

[0077] Table 1. Catalyst properties of examples and comparative examples

[0078]

[0079] Example 4

[0080] 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.

[0081] 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.

[0082] 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.

[0083] Example 5

[0084] 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.

[0085] 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.

[0086] 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.

[0087] Example 6

[0088] 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.

[0089] 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.

[0090] 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.

[0091] Comparative Example 3

[0092] 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 0.07 cm³. 3 / g, total pore volume is 0.17cm³ 3 / g, mesoporous pore volume accounts for 41% of the total pore volume.

[0093] 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.

[0094] 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.

[0095] Comparative Example 4

[0096] 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.

[0097] 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.

[0098] 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.

[0099] Table 2. Catalyst properties of examples and comparative examples

[0100]

[0101] Example 7

[0102] 1.0 mL of catalyst FF-66 was placed in the first reactor of the fixed-bed reactor. 8.0 mL of catalyst CAT-A-1 was placed in the upper part of the second reactor of the fixed-bed reactor. 2.0 mL of catalyst CAT-B-1 was placed in the lower part of the second reactor of the fixed-bed reactor. Catalytic cracking light naphtha was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts FF-66, CAT-A-1, and CAT-B-1. The reaction conditions in the first reactor were as follows: reaction temperature 180℃, reaction pressure 4.0 MPa, and hydrogen-to-oil volume ratio 400:1. The reaction conditions in the second reactor 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] Example 8

[0104] 2.0 mL of catalyst FF-66 was placed in the first reactor of the fixed-bed reactor. 9.0 mL of catalyst CAT-A-2 was placed in the upper part of the second reactor, and 1.0 mL of catalyst CAT-B-2 was placed in the lower part. Catalytic cracking light naphtha was introduced into the reactors at a flow rate of 10 mL / h to react with the catalysts FF-66, CAT-A-2, and CAT-B-2 sequentially. The reaction conditions in the first reactor were: reaction temperature 180℃, reaction pressure 4.0 MPa, and hydrogen-to-oil volume ratio 400:1. The reaction conditions in the second reactor were: 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.

[0105] Example 9

[0106] 0.7 mL of catalyst FF-66 was placed in the first reactor of the fixed-bed reactor. 4.0 mL of catalyst CAT-A-3 was placed in the upper part of the second reactor, and 6.0 mL of catalyst CAT-B-3 was placed in the lower part. Catalytic cracking light naphtha was introduced into the reactors at a flow rate of 10 mL / h to react with the catalysts FF-66, CAT-A-3, and CAT-B-3. The reaction conditions in the first reactor were: reaction temperature 180℃, reaction pressure 4.0 MPa, and hydrogen-to-oil volume ratio 400:1. The reaction conditions in the second reactor were: 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.

[0107] Comparative Example 5

[0108] 0.4 mL of catalyst FF-66 was placed in the first reactor of the fixed-bed reactor. 4.0 mL of catalyst CAT-A-3 was placed in the upper part of the second reactor, and 6.0 mL of catalyst CAT-B-3 was placed in the lower part. Catalytic cracking light naphtha was introduced into the reactors at a flow rate of 10 mL / h to react with the catalysts FF-66, CAT-A-3, and CAT-B-3. The reaction conditions in the first reactor were: reaction temperature 180℃, reaction pressure 4.0 MPa, and hydrogen-to-oil volume ratio 400:1. The reaction conditions in the second reactor were: 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 6

[0110] 6.0 mL of catalyst FF-66 was placed in the first reactor of the fixed-bed reactor, 4.0 mL of catalyst CAT-A-3 was placed in the upper part of the second reactor, and 6.0 mL of catalyst CAT-B-3 was placed in the lower part of the second reactor. Catalytic cracking light naphtha was introduced into the reactors at a flow rate of 10 mL / h to react with the catalysts FF-66, CAT-A-3, and CAT-B-3. The reaction conditions in the first reactor were as follows: reaction temperature 180℃, reaction pressure 4.0 MPa, and hydrogen-to-oil volume ratio 400:1. The reaction conditions in the second reactor 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 7

[0112] 0.7 mL of catalyst FF-66 was placed in the first reactor of the fixed-bed reactor. 4.0 mL of catalyst CAT-A-3 was placed in the upper part of the second reactor, and 9.0 mL of catalyst CAT-B-3 was placed in the lower part. Catalytic cracking light naphtha was introduced into the reactors at a flow rate of 10 mL / h to react with the catalysts FF-66, CAT-A-3, and CAT-B-3. The reaction conditions in the first reactor were: reaction temperature 180℃, reaction pressure 4.0 MPa, and hydrogen-to-oil volume ratio 400:1. The reaction conditions in the second reactor were: 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 8

[0114] 0.7 mL of catalyst FF-66 was placed in the first reactor of the fixed-bed reactor. 10.0 mL of catalyst CAT-A-3 was placed in the upper part of the second reactor of the fixed-bed reactor. 0.1 mL of catalyst CAT-B-3 was placed in the lower part of the second reactor of the fixed-bed reactor. Catalytic cracking light naphtha was introduced into the reactor at a flow rate of 10 mL / h to react with the catalysts FF-66, CAT-A-3, and CAT-B-3. The reaction conditions in the first reactor were as follows: reaction temperature 180℃, reaction pressure 4.0 MPa, and hydrogen-to-oil volume ratio 400:1. The reaction conditions in the second reactor 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.

[0115] Comparative Example 9

[0116] 0.7 mL of catalyst FF-66 was placed in the first reactor of the fixed-bed reactor. 4.0 mL of catalyst DCAT-A-1 was placed in the upper part of the second reactor, and 6.0 mL of catalyst DCAT-B-1 was placed in the lower part. Catalytic cracking light naphtha was introduced into the reactors at a flow rate of 10 mL / h to react with the catalysts FF-66, DCAT-A-1, and DCAT-B-1. The reaction conditions in the first reactor were: reaction temperature 180℃, reaction pressure 4.0 MPa, and hydrogen-to-oil volume ratio 400:1. The reaction conditions in the second reactor were: 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.

[0117] Comparative Example 10

[0118] 0.7 mL of catalyst FF-66 was placed in the first reactor of the fixed-bed reactor. 4.0 mL of catalyst DCAT-A-2 was placed in the upper part of the second reactor, and 6.0 mL of catalyst DCAT-B-2 was placed in the lower part. Catalytic cracking light naphtha was introduced into the reactors at a flow rate of 10 mL / h to react with the catalysts FF-66, DCAT-A-2, and DCAT-B-2 sequentially. The reaction conditions in the first reactor were: reaction temperature 180℃, reaction pressure 4.0 MPa, and hydrogen-to-oil volume ratio 400:1. The reaction conditions in the second reactor were: 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.

[0119] Table 3 Composition and Oil Properties of Light Naphtha from Catalytic Cracking Feedstock

[0120] composition Content, wt% Alkanes 36.7 Olefins 58.9 Cycloalkanes 2.5 Aromatics 1.9 <![CDATA[C5-C6 Isoparaffin Content]]> 66.7 Initial boiling point, ℃ 22.8 Final boiling point, ℃ 65.7

[0121] Table 4 Evaluation results of the catalysts in the examples

[0122] project Example 7 Example 8 Example 9 Olefin content in refined naphtha, % 0.15 0.07 0.63 Isomer hydrocarbon conversion rate, % 45.2 44.5 48.4 Selectivity for isomeric hydrocarbon conversion, % 74.3 71.5 77.2 The proportion of n-alkane in the product, % 53.3 51.2 54.0 Carbon deposits, % 0.11 0.15 0.21

[0123] Table 5 Evaluation results of the comparative example catalysts

[0124]

[0125] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for processing catalytic cracking light naphtha, comprising: Catalytic cracked light naphtha is sequentially passed through a hydrorefining reaction zone, a first hydroconversion reaction zone, and a second hydroconversion reaction zone to obtain the converted light naphtha product; wherein, the volume ratio of the first hydroconversion catalyst packed in the first hydroconversion reaction zone to the second hydroconversion catalyst packed in the second hydroconversion reaction zone is 10:1 to 1:

2.

2. The processing method according to claim 1, characterized in that, The initial boiling point of the catalytic cracked light naphtha is 15–30°C, and the final boiling point is 60–90°C. Preferably, the olefin content in the catalytic cracking light naphtha is 30wt% to 60wt%, and the alkane content is 30wt% to 66wt%, based on a total weight of 100wt% of the catalytic cracking light naphtha. Preferably, the C5-C6 isohydrocarbon content in the catalytic cracking light naphtha is 50wt% to 90wt%, more preferably 60wt% to 80wt%, based on a total weight of 100wt% of the catalytic cracking light naphtha.

3. The processing method according to claim 1, characterized in that, The hydrorefining conditions are: reaction temperature 150-250℃, reaction pressure 2-8MPa, and hydrogen-to-oil volume ratio 100:1-2000:

1.

4. The processing method according to claim 1, characterized in that, The hydrogenation conversion conditions are: reaction temperature 300-450℃, reaction pressure 2-8MPa, and hydrogen-to-oil volume ratio 100:1-2000:

1.

5. The processing method according to claim 1, characterized in that, The refined naphtha obtained after hydrorefining contains 0.05 wt% to 1.5 wt% olefins, preferably 0.08 wt% to 1.0 wt%.

6. The processing method according to claim 1, characterized in that, The first hydroconversion catalyst 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.

7. The processing method according to claim 1 or 6, characterized in that, In the first hydroconversion catalyst, 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%.

8. The processing method according to claim 1, characterized in that, The pyridine adsorption capacity (380℃) of the first hydroconversion catalyst is 0.30-0.40 mmol / g.

9. The processing method according to claim 1, characterized in that, The second hydroconversion catalyst comprises a modified ZSM-5 molecular sieve, a Group VIB metal and a 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 processing method according to claim 1 or 9, characterized in that, In the second hydroconversion catalyst, based on the weight of the catalyst, 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 the catalyst, the content of modified ZSM-5 molecular sieve is 45wt% 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%.

11. The processing method according to claim 1 or 9, characterized in that, The micropore volume of the second hydroconversion catalyst accounts for 10% to 30% of the total pore volume, preferably 15% to 25%.

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