Conversion method of light naphtha

Abstract

The invention discloses a conversion method of light naphtha. The method comprises the following steps: (a) mixing light naphtha and hydrogen, carrying out a first reaction in a first reaction zone to obtain a first reverse effluent, and controlling the olefin mass content in the first reverse effluent to be 0.05-1.50 wt%; and (b) carrying out a second reaction on the first reverse effluent obtained in the step (a) through a second reaction zone to obtain a converted light naphtha product. When the method is used for treating light naphtha, the conversion rate is obviously improved, the content of normal hydrocarbon in the obtained product is obviously increased, and the yield of triene when the light naphtha is used as a raw material for preparing ethylene through steam cracking can be greatly improved.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to a method for converting light naphtha (rich in C5 and C6 alkanes). Background Technology

[0002] During petroleum processing, atmospheric and vacuum distillation, catalytic cracking, hydrocracking and other units all produce light naphtha rich in C5 and C6 hydrocarbons.

[0003] The light naphtha produced by atmospheric and vacuum distillation units and hydrocracking units mainly consists of C5 and C6 alkanes. There are currently two main ways to utilize light naphtha: one is to use it directly as a gasoline blending component, but due to the influence of saturated vapor pressure, the amount added when used as a gasoline blending component is relatively low; the other is to use it as a feedstock for steam cracking to produce ethylene, but due to its high degree of isomerization, with isomer hydrocarbon content reaching more than 70%, the yield of trienes is low when used as a feedstock for ethylene, and its hydrocarbon composition needs to be further improved.

[0004] CN201510379026.6 discloses a method for optimizing the utilization of light naphtha. This method first passes the light naphtha through an adsorption separation unit to obtain an adsorbed oil rich in isoalkanes and a desorbed oil rich in n-alkanes. The desorbed oil can be directly used as feedstock for ethylene cracking. The adsorbed oil is then passed through a distillation unit to obtain gasoline blending material rich in isocyanate C6 and high-purity isopentane. This process uses adsorption separation, which has high energy consumption. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for converting light naphtha. Using this method to process light naphtha significantly improves the conversion rate and increases the content of n-hydrocarbons in the obtained product, thereby greatly improving the yield of trienes (ethylene, propylene, and butadiene) when used as a feedstock for ethylene production via steam cracking.

[0006] This invention provides a method for converting naphtha, comprising:

[0007] (a) Light naphtha and hydrogen are mixed and passed through the first reaction zone to carry out the first reaction to obtain the first reaction effluent. The olefin content in the first reaction effluent is controlled to be 0.05wt% to 1.50wt%, preferably 0.08wt% to 1.00wt%.

[0008] (b) The first effluent obtained in step (a) undergoes a second reaction in the second reaction zone to obtain the converted light naphtha product.

[0009] Furthermore, the olefin content in the effluent of the first reaction product is, for example, but not limited to, 0.10 wt%, 0.15 wt%, 0.20 wt%, 0.25 wt%, 0.30 wt%, 0.35 wt%, 0.40 wt%, 0.45 wt%, 0.50 wt%, 0.60 wt%, 0.70 wt%, 0.80 wt%, 0.90 wt%, 0.95 wt%, 1.00 wt%, 1.50 wt%, and any range between any two values.

[0010] Further, the light naphtha can be one or more of straight-run light naphtha, hydrocracked light naphtha, and hydrodepressed light naphtha. The initial boiling point of the light naphtha is 15–30°C, and the final boiling point is 60–90°C. Further, the mass content of C5-C6 isoalkanes in the light naphtha is 30 wt%–90 wt%, preferably 50–80 wt%, with the remainder being normal C5-C6 normal hydrocarbons and a small amount of C4 hydrocarbons. - and C6 + Hydrocarbons.

[0011] Furthermore, the reaction conditions for the first reaction are as follows: reaction temperature of 350–450℃, reaction pressure of 2.0–8.0 MPa, hydrogen-to-oil volume ratio of 100:1–2000:1, and liquid hourly space velocity of 6.0–20.0 h⁻¹. -1 .

[0012] Furthermore, the reaction conditions in the second reaction zone are as follows: reaction temperature of 350–450℃, reaction pressure of 2.0–8.0 MPa, hydrogen-to-oil volume ratio of 100:1–2000:1, and liquid hourly space velocity of 0.5–5.0 h⁻¹. -1 .

[0013] Furthermore, the volume ratio of catalyst A packed in the first reaction zone to catalyst B packed in the second reaction zone is 1:5 to 1:20. For example, but not limited to, 1:6, 1:7, 1:8, 1:9, 1:10, 1:12, 1:14, 1:16, 1:18, and any range between any two values.

[0014] Further, the first reaction zone is filled with catalyst A, which comprises a metal component, ZSM-5 molecular sieve, and macroporous alumina. Further, based on the weight of catalyst A, the content of ZSM-5 molecular sieve is 40 wt% to 80 wt%, the content of macroporous alumina is 15 wt% to 50 wt%, and the content of the metal component (calculated as oxides) is 0.5 wt% to 10.0 wt%. Preferably, based on the weight of catalyst A, the content of ZSM-5 molecular sieve is 50 wt% to 70 wt%, the content of macroporous alumina is 20 wt% to 30 wt%, and the content of the metal component (calculated as oxides) is 1.0 wt% to 5.0 wt%. Further, the metal in the metal component is a Group VIII metal, preferably cobalt and / or nickel.

[0015] 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.

[0016] Furthermore, the preparation method of catalyst A includes the following steps:

[0017] ZSM-5 molecular sieve, a group VIII metal source, and macroporous alumina were mixed, shaped, and calcined to obtain catalyst A.

[0018] Furthermore, the mass ratio of ZSM-5 molecular sieve, Group VIII metal source (based on oxides), and macroporous alumina is 1–2:0.5–1:0.05–0.1.

[0019] Furthermore, the Group VIII metal is preferably cobalt and / or nickel. Further, the Group VIII metal source is selected from one or more Group VIII metal nitrates and Group VIII metal basic carbonates.

[0020] Furthermore, the molding process 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 citric acid and nitric acid; the binder can be aluminum sol or silica sol prepared from porous alumina, preferably aluminum sol. The amount of molding aid added meets the requirement that the amount of molding aid added accounts for 2% to 10% of the mass of catalyst A.

[0021] Further, after molding, the catalyst is dried and then calcined to obtain catalyst A. 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, the second reaction zone is packed with catalyst B, which comprises ZSM-5 molecular sieve and macroporous alumina supported on Group VIB and Group VIII metals, wherein the infrared acidity I in catalyst B is... A Total Group VIII metals in the catalyst phase I mt molar ratio I A / I mt The value is 5.0 to 0.5, preferably 1.5 to 3.0.

[0023] Furthermore, the amount of Brønsted acid (B acid) in catalyst B is I. A The molar ratio of the total amount of Group VIB and Group VIII metals in the catalyst bulk phase I A / I mt In this context, the unit for the amount of Brønsted acid is mol / g, and the total amount of Group VIB and Group VIII metals in the catalyst bulk phase refers to the total molar amount of Group VIB and Group VIII metals per gram of catalyst, expressed in atomic terms.

[0024] Furthermore, Group VIB and Group VIII metals exist in the catalyst in the form of oxides.

[0025] Further, based on the weight of the catalyst, the content of ZSM-5 molecular sieve is 30wt% to 80wt%, the content of macroporous alumina is 15wt% 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 ZSM-5 molecular sieve is 50wt% to 75wt%, the content of macroporous alumina is 20wt% to 30wt%, and the total content of Group VIB and Group VIII metals as oxides is 1.0wt% to 5.0wt%. Further, in the macroporous alumina loaded with Group VIB and Group VIII metals, the mass ratio of Group VIB metals as oxides to Group VIII metals as oxides is 2.0 to 6.0.

[0026] Furthermore, in the macroporous alumina loaded with Group VIB and Group VIII metals, the Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel.

[0027] Furthermore, the total amount of Group VIB and Group VIII metals on the surface of catalyst B is I msThe total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt The molar ratio is 0.60–0.90. The total amount of Group VIB and Group VIII metals on the catalyst surface refers to the total molar amount of Group VIB and Group VIII metals per gram of catalyst surface, expressed in atomic terms.

[0028] Furthermore, in catalyst B, 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.

[0029] Furthermore, in catalyst A and catalyst B, the macroporous alumina can be the same or different, and the ZSM-5 molecular sieve can be the same or different.

[0030] This invention provides a method for preparing catalyst B, comprising the following steps:

[0031] (I) Macroporous alumina is impregnated with an impregnation solution containing Group VIB and Group VIII metals and then calcined to obtain macroporous alumina loaded with Group VIB and Group VIII metals.

[0032] (II) The macroporous alumina loaded with Group VIB and Group VIII metals obtained in step (I) is mixed with ZSM-5 molecular sieve, shaped, and calcined to obtain catalyst B.

[0033] Furthermore, the impregnation in step (1) is performed using a pressure impregnation method.

[0034] Furthermore, the pressure impregnation includes: mixing macroporous alumina with an impregnation solution containing Group VIB and Group VIII metals, and impregnating in a closed atmosphere under nitrogen.

[0035] Furthermore, the impregnation conditions include: a pressure of 0.5–3.0 MPa, a temperature of 60–80 °C, and an impregnation time of 1–4 h.

[0036] Further, the impregnation is preferably carried out under stirring at a stirring rate of 100–300 rpm. Further, after impregnation, stirring and heating are stopped, and the mixture is allowed to stand for 2–4 hours until cooled to room temperature. The resulting material is first subjected to conventional filtration and drying, and then calcined to obtain macroporous alumina loaded with Group VIB and Group VIII metals. The drying temperature is 100°C–150°C, and the drying time is 2–4 hours; the calcination temperature is 400°C–600°C, and the calcination time is 3–5 hours.

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

[0038] Further, in step (I), 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 oxides) is 3.0–30.0 g / 100 mL, and the mass content of the Group VIII metal (calculated as oxides) is 1.0–10.0 g / 100 mL.

[0039] Further, in step (I), the pH value of the impregnation solution containing Group VIB and Group VIII metals is 8.0 to 10.0. Further, there are no particular limitations on the pH adjuster used; conventional pH adjusters in the art can be used.

[0040] Furthermore, in step (II), the mass ratio of macroporous alumina loaded with Group VIB and Group VIII metals to ZSM-5 molecular sieve is 0.2 to 1.0.

[0041] Furthermore, 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.

[0042] Furthermore, in step (II), 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, 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.

[0043] Further, in step (II), after molding, the catalyst is dried and calcined to obtain the 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.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The isomeric C5 and C6 alkanes in the light naphtha of this invention, compared to long-chain alkanes, have a more difficult dehydrogenation process during conversion, which is the controlling step of the overall reaction. Increasing the number of metal active sites can improve the dehydrogenation activity of the catalyst. Since both dehydrogenation and hydrogenation reactions occur at metal active sites, increasing the metal content increases the hydrogenation activity, leading to rapid termination of the light naphtha conversion reaction and a decrease in conversion rate.

[0046] In the conversion method of light naphtha of this invention, the raw material light naphtha first passes through a first reaction zone of catalyst A, which is packed with a Group VIII monometallic center and has higher dehydrogenation activity, producing a certain amount of olefins. These olefins can rapidly react with the acidic centers of the catalyst to generate carbocations. The generated carbocations continue to propagate after completing the reaction, allowing the reaction to continue and acting as an initiator. Then, it passes through a second reaction zone packed with catalyst B, which has Group VIII and Group VIB bimetallic centers with better hydrogenation activity. The amount of Brønsted acid in catalyst B is I. A The total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt molar ratio I A / I mt It has a higher efficiency than traditional hydrocracking catalysts, which can improve the conversion activity of light naphtha.

[0047] In catalyst B of this invention, the hydrogenation metals (Group VIII and Group VIB bimetals) are supported within the pores of macroporous alumina. Within the molecular sieve pores, the hydrogenation activity is low, which is beneficial for improving the conversion reaction activity. Simultaneously, due to the confinement of the molecular sieve pores, the reaction intermediate olefins are less prone to carbon deposition. After diffusing out of the molecular sieve pores, the n-olefins or small molecule olefins obtained from the conversion of light hydrocarbons rapidly contact the hydrogenation centers on the alumina, undergoing a saturation reaction, thus preventing carbon deposition and improving catalyst stability.

[0048] Using the conversion method of naphtha of the present invention, the conversion rate can reach more than 52%, preferably 54% to 60%, and the proportion of n-hydrocarbons in the obtained product can reach more than 50%, preferably 52% to 55%. 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 total amount of Group VIB and Group VIII metals on the catalyst surface is I ms The elemental composition and state of the catalyst surface (3 nm–10 nm) were determined by X-ray photoelectron spectroscopy (XPS) using a Thermofisher Multilab 2000 electron spectrometer. The excitation source was Mg Kα, and the cathode voltage and current were 13 kV and 20 mA, respectively. The electron binding energy was calibrated using Cls (284.6 eV). The data obtained directly from XPS are mass percentages. ms The values ​​are converted to mol / g.

[0051] In this invention, the total amount of Group VIB and Group VIII metals in the bulk phase of the catalyst is I mt The results were obtained by X-ray fluorescence spectroscopy (XRF) analysis using a ZSX100e X-ray fluorescence spectrometer. The spectral line was Kα, the crystal was LiF1, the target material was Rh, the detector was SC scintillation, the timing was 20 s, and the optical atmosphere was vacuum. The data obtained directly from XRF are mass percentages. Im t is the value after conversion to mol / g. The total amount of Group VIB and Group VIII metals in the bulk catalyst refers to the total amount of Group VIB and Group VIII metals in the entire catalyst.

[0052] 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.

[0053] In this invention, the amount of Brønsted acid in the catalyst is I. A Measurements were taken using a pyridine infrared spectroscopy device. The powdered catalyst was compressed into tablets, evacuated, and degassed at 450°C for 2 hours. After the temperature dropped to room temperature, the kinetic diameter was measured... Pyridine molecules are used as probe molecules to measure the infrared spectrum of chemical desorption and calculate the amount of Brønsted acid (B acid) adsorbed. Because the diameter of pyridine molecules is smaller than that of molecular sieve channels, this method can obtain the amount of B acid in mol / g.

[0054] In this invention, unless otherwise specified, all percentages (%) in the embodiments and comparative examples refer to mass fractions.

[0055] The ZSM-5 molecular sieve involved in the embodiments and comparative examples of this invention is a commercially available product with a pore volume of 0.18 cm³. 3 / g, specific surface area is 191cm³ 2 / g, the silicon-to-aluminum molar ratio of SiO2:Al2O3 is 55. The macroporous alumina is a commercially available product with a pore volume of 1.1 cm³. 3 / g, specific surface area is 350cm² 2 / g.

[0056] In this invention, the conversion rate of light naphtha and the proportion of n-alkanes in the product are calculated as follows:

[0057] Conversion rate = (mass of isomeric C5 and C6 hydrocarbons in feedstock - mass of isomeric C5 and C6 hydrocarbons in product) / (mass of isomeric C5 and C6 hydrocarbons in feedstock) × 100%;

[0058] 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.

[0059] In this invention, the light naphtha conversion evaluation test is carried out in a fixed-bed device, wherein the first reactor is filled with catalyst A and serves as the first reaction zone for the first reaction; the second reactor is filled with catalyst B and serves as the second reaction zone for the second reaction.

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

[0061] In this invention, the initial boiling point of the light naphtha raw material in Table 2 is 16.4℃, and the final boiling point is 67.8℃.

[0062] Example 1

[0063] 100g of macroporous alumina was impregnated for 2h in 200mL of an aqueous solution with a nickel content of 2.0g / 100mL (nickel as oxide, nickel source: nickel nitrate), a tungsten content of 10.0g / 100mL (tungsten as oxide, ammonium metatungstate as tungsten source), and a pH of 9.0. The impregnation pressure was 1.0MPa, and the impregnation temperature was 60℃. After impregnation, the alumina was cooled to room temperature, filtered, dried at 120℃ for 3h, and calcined at 450℃ for 3h to obtain A-NW-1. 100g of ZSM-5 molecular sieve and 30g of A-NW-1 were mixed, and 85g of pectinic acid (concentration: 1wt%) and 1g of extrusion aid guar gum powder were added. The mixture was then rolled, extruded, dried at 120℃ for 3h, and calcined at 500℃ for 4h to obtain CAT-B1, the properties of which are shown in Table 1.

[0064] Comparative Example 1

[0065] 100g of ZSM-5 molecular sieve and 45g of macroporous alumina were mixed, and 85g of pectinic acid (1wt%) and 1g of extrusion aid guar gum powder were added. The mixture was then crushed, extruded into strips, dried at 120℃ for 3 hours, and calcined at 500℃ for 4 hours to obtain A-NW-D1. 100g of A-NW-D1 was impregnated in 200mL of an aqueous solution containing 1.5g / 100mL of nickel and 8.0g / 100mL of tungsten (based on oxides) for 2 hours. After filtration, drying at 120℃ for 3 hours, and calcining at 500℃ for 4 hours, DCAT-B1 was obtained. Its properties are shown in Table 1.

[0066] Comparative Example 2

[0067] 100g of macroporous alumina was impregnated for 2h in 200mL of an aqueous solution containing 8.0g / 100mL nickel, 40.0g / 100mL tungsten (based on oxides), and pH 9.0, at a pressure of 1.0MPa and a temperature of 60℃. After impregnation, the alumina was cooled to room temperature, filtered, dried at 120℃ for 3h, and calcined at 450℃ for 3h to obtain A-NW-D2. 100g of ZSM-5 molecular sieve and 30g of A-NW-D2 were mixed, and 85g of pectinic acid (1wt%) and 1g of extrusion aid guar gum powder were added. The mixture was then rolled, extruded, dried at 120℃ for 3h, and calcined at 500℃ for 4h to obtain DCAT-B2, the properties of which are shown in Table 1.

[0068] Comparative Example 3

[0069] 100g of macroporous alumina was impregnated in 200mL of an aqueous solution (pH 5.4) 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 450℃ for 3 hours, macroporous alumina loaded with nickel oxide and tungsten oxide was obtained, denoted as A-NW-D3. 100g of ZSM-5 molecular sieve and 30g of A-NW-D3 were mixed, and 85g of pectinic acid (concentration 1wt%) and 1g of extrusion aid guar gum powder were added. The mixture was then rolled, extruded, dried at 120℃ for 3 hours, and calcined at 500℃ for 4 hours to obtain a catalyst, denoted as DCAT-B3, the properties of which are shown in Table 1.

[0070] Comparative Example 4

[0071] Take 100g of small-pore alumina (pore volume 0.48cm³). 3 / g, specific surface area is 251cm³ 2A small-pore alumina loaded with nickel oxide and tungsten oxide, denoted as A-NW-D4, was obtained by impregnating 200 mL of an aqueous solution containing 2.0 g / 100 mL of nickel and 10.0 g / 100 mL of tungsten (calculated as oxides) with a pH of 9.0 for 2 h at an impregnation pressure of 1.0 MPa and an impregnation temperature of 60 °C after impregnation. After impregnation, the alumina was cooled to room temperature, filtered, dried at 120 °C for 3 h, and calcined at 450 °C for 3 h. 100 g of ZSM-5 molecular sieve and 30 g of A-NW-D4 were mixed, and 85 g of pectinic acid (1 wt%) and 1 g of extrusion aid guar gum powder were added. The mixture was then crushed, extruded, dried at 120 °C for 3 h, and calcined at 500 °C for 4 h to obtain a catalyst, denoted as DCAT-B4, the properties of which are shown in Table 1.

[0072] Example 2

[0073] 100g of macroporous alumina was impregnated for 2h in 200mL of an aqueous solution containing 1.0g / 100mL nickel, 5.0g / 100mL tungsten (based on oxides), and pH 9.0, at an impregnation pressure of 0.5MPa and an impregnation temperature of 70℃. After impregnation, the alumina was cooled to room temperature, filtered, dried at 120℃ for 3h, and calcined at 450℃ for 3h to obtain A-NW-2. 100g of ZSM-5 molecular sieve and 30g of A-NW-2 were mixed, and 85g of pectinic acid (1wt%) and 1g of extrusion aid guar gum powder were added. The mixture was then rolled, extruded, dried at 120℃ for 3h, and calcined at 500℃ for 4h to obtain CAT-B2, the properties of which are shown in Table 1.

[0074] Example 3

[0075] 100g of macroporous alumina was impregnated for 2h in 200mL of an aqueous solution containing 2.0g / 100mL nickel, 10.0g / 100mL tungsten (based on oxides), and pH 10.0, under a pressure of 2.0MPa and a temperature of 80℃. After impregnation, the alumina was cooled to room temperature, filtered, dried at 120℃ for 3h, and calcined at 450℃ for 3h to obtain A-NW-3. 80g of ZSM-5 molecular sieve and 50g of A-NW-3 were mixed, and 90g of pectinic acid (1wt%) and 1g of extrusion aid guar gum powder were added. The mixture was then rolled, extruded, dried at 120℃ for 3h, and calcined at 500℃ for 4h to obtain CAT-B3, the properties of which are shown in Table 1.

[0076] Example 4

[0077] 100g of macroporous alumina was impregnated for 2h in 200mL of an aqueous solution containing 1.0g / 100mL nickel, 5.0g / 100mL tungsten (based on oxides), and pH 8.0, at an impregnation pressure of 2.0MPa and a temperature of 80℃. After impregnation, the alumina was cooled to room temperature, filtered, dried at 120℃ for 3h, and calcined at 450℃ for 3h to obtain A-NW-4. 50g of ZSM-5 molecular sieve and 50g of A-NW-4 were mixed, and 75g of pectinic acid (1wt%) and 1g of extrusion aid guar gum powder were added. The mixture was then rolled, extruded, dried at 120℃ for 3h, and calcined at 500℃ for 4h to obtain CAT-B4, the properties of which are shown in Table 1.

[0078] Example 5

[0079] Take 100g of ZSM-5 molecular sieve, 20g of nickel nitrate hexahydrate, and 30g of macroporous alumina, add 85g of pectinic acid 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. Its properties are shown in Table 1.

[0080] Table 1. Composition and properties of catalysts obtained in the examples and comparative examples.

[0081]

[0082] Note: The alumina content of DCAT-B4 is calculated based on microporous alumina, while the content of the other catalysts is calculated based on macroporous alumina.

[0083] Example 6

[0084] 1.0 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10.0 mL of catalyst CAT-B1 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact catalyst CAT-B1 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 10.0 h⁻¹. -1 The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0085] Comparative Example 5

[0086] 1.0 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10.0 mL of catalyst DCAT-B1 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact catalyst DCAT-B1 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 10.0 h⁻¹. -1 The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0087] Comparative Example 6

[0088] The first reactor of the fixed-bed reactor was not loaded with catalyst. 10.0 mL of catalyst CAT-B1 was placed in the second reactor of the fixed-bed reactor. The reaction was carried out at a pressure of 4.0 MPa, a hydrogen-to-oil volume ratio of 400:1, and a liquid hourly space velocity of 1.0 h⁻¹. -1 The light naphtha conversion reaction was carried out at a reaction temperature of 400℃. The feedstock light naphtha was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha. Its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0089] Comparative Example 7

[0090] 0.33 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10.0 mL of catalyst DCAT-B2 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact catalyst DCAT-B2 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 30.0 h⁻¹. -1 The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0091] Comparative Example 8

[0092] 1.0 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10.0 mL of catalyst DCAT-B3 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact catalyst DCAT-B3 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 10.0 h⁻¹. -1 The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0093] Comparative Example 9

[0094] 1.0 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10.0 mL of catalyst DCAT-B4 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact with catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact with catalyst DCAT-B4 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 10.0 h⁻¹. -1 The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0095] Comparative Example 10

[0096] 3.3 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10.0 mL of catalyst CAT-B1 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact catalyst CAT-B1 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 3.0 h⁻¹. -1 The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0097] Example 7

[0098] 0.5 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10.0 mL of catalyst CAT-B2 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact catalyst CAT-B2 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 20.0 h⁻¹. -1 The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0099] Example 8

[0100] 1.0 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10 mL of catalyst CAT-B3 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact with catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact with catalyst CAT-B3 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 10.0 h⁻¹. -1The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0101] Example 9

[0102] 1.0 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10 mL of catalyst CAT-B4 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact with catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact with catalyst CAT-B4 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 10.0 h⁻¹. -1 The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0103] Example 10

[0104] 1.5 mL of catalyst CAT-A was placed in the first reactor of the fixed-bed reactor, and 10.0 mL of catalyst CAT-B1 was placed in the second reactor. The feedstock, light naphtha and hydrogen, was mixed and introduced into the first reactor to contact catalyst CAT-A for the first reaction. The resulting effluent was then introduced into the second reactor to contact catalyst CAT-B1 for the second reaction. The reaction conditions for the first reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity (LHSV) 6.7 h⁻¹. -1 The reaction temperature was 400℃. The reaction conditions for the second reaction were as follows: reaction pressure 4.0 MPa, hydrogen-to-oil volume ratio 400:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The reaction temperature was 400℃. The feedstock, light naphtha, was a 1:1 mixture of straight-run light naphtha and hydrocracked naphtha, and its properties are shown in Table 2. After running for 160 hours, the olefin content, conversion rate of each component, yield of each component, and catalyst carbon deposition in the first reaction effluent are shown in Table 3.

[0105] Table 2 Hydrocarbon Composition of Raw Material Light Naphtha

[0106]

[0107] Table 3 Evaluation results of the catalysts in the examples

[0108] project Example 6 Example 7 Example 8 Example 9 Example 10 Olefin content of the first-stage effluent, % 0.12 0.07 0.12 0.12 0.54 Conversion rate, % 58 52 54 55 57 The proportion of n-alkane in the product, % 53 51 52 52 54 Carbon deposits, % 0.25 0.17 0.18 0.20 0.30

[0109] Table 4 Evaluation results of the comparative example catalysts

[0110]

[0111] 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 naphtha, comprising: (a) Light naphtha and hydrogen are mixed and passed through the first reaction zone to carry out the first reaction to obtain the first reaction effluent. The olefin content in the first reaction effluent is controlled to be 0.05wt% to 1.50wt%, preferably 0.08wt% to 1.00wt%. (b) The first effluent obtained in step (a) undergoes a second reaction in the second reaction zone to obtain the converted light naphtha product.

2. The method according to claim 1, characterized in that: The light naphtha is one or more of straight-run light naphtha, hydrocracked light naphtha, and hydrodepressed light naphtha. Preferably, the initial boiling point of the light naphtha is 15-30°C and the final boiling point is 60-90°C; further, the mass content of C5-C6 isoalkanes in the light naphtha is 30wt%-90wt%, preferably 50wt%-80wt%.

3. The method according to claim 1, characterized in that: The reaction conditions for the first reaction were: a reaction temperature of 350–450℃, a reaction pressure of 2.0–8.0 MPa, a hydrogen-to-oil volume ratio of 100:1–2000:1, and a liquid hourly space velocity of 6.0–20.0 h⁻¹. -1 ; And / or, the reaction conditions in the second reaction zone are: a reaction temperature of 350–450℃, a reaction pressure of 2.0–8.0 MPa, a hydrogen-to-oil volume ratio of 100:1–2000:1, and a liquid hourly space velocity of 0.5–5.0 h⁻¹. -1 .

4. The method according to claim 1, characterized in that: The first reaction zone is filled with catalyst A, which includes a metal component, ZSM-5 molecular sieve and macroporous alumina; preferably, the metal in the metal component is a Group VIII metal, preferably cobalt and / or nickel; And / or, the second reaction zone is filled with catalyst B, which comprises ZSM-5 molecular sieve and macroporous alumina supported on Group VIB and Group VIII metals; preferably, the Group VIB metal is molybdenum and / or tungsten, and the Group VIII metal is cobalt and / or nickel.

5. The method according to claim 4, characterized in that: The volume ratio of catalyst A packed in the first reaction zone to catalyst B packed in the second reaction zone is 1:5 to 1:

20.

6. The method according to claim 4, characterized in that: Based on the weight of catalyst A, the content of ZSM-5 molecular sieve is 40wt% to 80wt%, the content of macroporous alumina is 15wt% to 50wt%, and the content of metal components as oxides is 0.5wt% to 10.0wt%. Preferably, based on the weight of catalyst A, the content of ZSM-5 molecular sieve is 50wt% to 70wt%, the content of macroporous alumina is 20wt% to 30wt%, and the content of metal components as oxides is 1.0wt% to 5.0wt%.

7. The method according to claim 4, characterized in that: The amount of Br acid in catalyst B is I A Total Group VIII metals in the catalyst phase I mt molar ratio I A / I mt The value is 5.0 to 0.5, preferably 1.5 to 3.

0.

8. The method according to claim 4, characterized in that: Based on the weight of catalyst B, the content of ZSM-5 molecular sieve is 30wt% to 80wt%, the content of macroporous alumina is 15wt% 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 ZSM-5 molecular sieve is 50wt% to 75wt%, the content of macroporous alumina is 20wt% to 30wt%, and the total content of Group VIB and Group VIII metals as oxides is 1.0wt% to 5.0wt%.

9. The method according to claim 4 or 8, characterized in that: In catalyst B, the total amount of Group VIB and Group VIII metals on the catalyst surface is I ms The total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt The molar ratio is 0.60 to 0.

90.

10. The method according to claim 4 or 6, characterized in that: 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; and / or, 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.

11. The method according to claim 4 or 8, characterized in that: In catalyst B, the macroporous alumina has a pore volume of 0.8–1.5 cm³. 3 / g, specific surface area of ​​200-400m² 2 / g; and / or, 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.

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