Light naphtha conversion catalyst as well as preparation method and application thereof

Abstract

The invention discloses a light naphtha conversion catalyst as well as a preparation method and application thereof. The catalyst comprises a ZSM-5 molecular sieve and macroporous alumina loaded with group VIB metal and group VIII metal, and the molar ratio IA / Imt of the amount IA of the B acid in the light naphtha conversion catalyst to the total amount Imt of the group VIB metal and the group VIII metal of the catalyst body phase is 0.5-5.0. The content of n-alkanes in a product obtained by treating light naphtha with the catalyst is obviously increased, so that the yield of triene when the catalyst 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 catalyst for the conversion of light naphtha (mainly referring to hydrocarbons rich in C5 and C6 hydrocarbons), its preparation method, and its application. Background Technology

[0002] In petroleum processing, units such as atmospheric and vacuum distillation, catalytic cracking, and hydrocracking all produce light naphtha rich in C5 and C6 hydrocarbons. The light naphtha from atmospheric and vacuum distillation units and hydrocracking units is composed mainly of alkanes, while the light naphtha from catalytic cracking units contains some olefins. From a carbon chain structure perspective, light naphtha is dominated by isomeric hydrocarbons, especially the light naphtha from catalytic cracking and hydrocracking units, where the isomeric hydrocarbon content reaches over 70%.

[0003] 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, the yield of trienes is low when used as an ethylene feedstock, and its hydrocarbon composition needs to be further improved.

[0004] CN201510944765.5 discloses a method for producing high-octane gasoline by isomerization of light naphtha. While maintaining the product performance of traditional process methods (the highest research octane number RON can reach 92), it simplifies and shortens the production process, saves investment, reduces energy consumption, makes operation and maintenance easier, and reduces production costs.

[0005] 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

[0006] To address the shortcomings of existing technologies, this invention provides a light naphtha conversion catalyst, its preparation method, and its application. The product obtained by treating light naphtha with this catalyst has a significantly increased content of n-alkanes, which can greatly improve the yield of trienes when used as a feedstock for ethylene production via steam cracking.

[0007] The first aspect of this invention provides a light naphtha conversion catalyst, the catalyst comprising ZSM-5 molecular sieve and macroporous alumina supported on Group VIB and Group VIII metals, wherein the amount of Brønsted acid in the light naphtha conversion catalyst is I. AThe total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt molar ratio I A / I mt The value is 0.5 to 5.0, preferably 1.5 to 3.0.

[0008] Furthermore, the amount of Brønsted acid (B acid) in the light naphtha conversion catalyst 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 bulk phase, expressed in atomic terms.

[0009] Furthermore, Group VIB and Group VIII metals exist in the catalyst in the form of oxides.

[0010] 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.

[0011] 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.

[0012] Furthermore, the total amount of Group VIB and Group VIII metals on the catalyst surface I ms The total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt The molar ratio is 0.60–0.90. 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.

[0013] Furthermore, the pore volume of the macroporous alumina is 0.8–1.5 cm³. 3 / g, specific surface area of ​​200-400m²2 / 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.

[0014] A second aspect of this invention provides a method for preparing a light naphtha conversion catalyst, comprising the following steps:

[0015] (1) Macroporous alumina was 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.

[0016] (2) The macroporous alumina loaded with Group VIB and Group VIII metals obtained in step (1) is mixed with ZSM-5 molecular sieve, shaped, and calcined to obtain a light naphtha conversion catalyst.

[0017] Furthermore, the impregnation in step (1) is performed using a pressure impregnation method.

[0018] 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.

[0019] 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.

[0020] 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.

[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.

[0022] Further, in step (1), 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] Furthermore, in the impregnation solution containing Group VIB metals and Group VIII metals, the mass content of Group VIB metals, calculated as oxides, is 3.0 to 30.0 g / 100 mL, and the mass content of Group VIII metals, calculated as oxides, is 1.0 to 10.0 g / 100 mL.

[0024] Further, in step (1), the pH value of the impregnation solution containing Group VIB metals 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.

[0025] Furthermore, in step (2), 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.

[0026] 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.

[0027] Further, in step (2), 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.

[0028] Further, in step (2), 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.

[0029] Further, the catalyst obtained in step (2) comprises ZSM-5 molecular sieve and macroporous alumina supported on Group VIB and Group VIII metals, wherein the amount of Brønsted acid in the catalyst is I. A Metal content I in the bulk catalyst phase mt molar ratio I A / I mt The value is 0.5 to 5.0, preferably 1.5 to 3.0.

[0030] Furthermore, Group VIB and Group VIII metals exist in the catalyst in the form of oxides.

[0031] Further, based on the weight of the catalyst, the content of ZSM-5 molecular sieve is 35wt% 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 70wt%, 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.

[0032] 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.

[0033] Furthermore, the total amount of Group VIB and Group VIII metals on the surface of the light naphtha conversion catalyst is I ms The total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt The ratio is 0.60 to 0.90.

[0034] A third aspect of the present invention provides a method for converting light naphtha, comprising:

[0035] (l) Saturated naphtha and olefin-rich streams are mixed to obtain a reaction stream;

[0036] (2) The reaction stream from step (1) is mixed with hydrogen and reacted with any of the catalysts provided in the first aspect to obtain the reaction product.

[0037] Furthermore, the reaction products include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, etc.

[0038] Further, in step (1), the saturated light naphtha can be one or more of straight-run light naphtha, hydrocracked light naphtha, or hydrodepressed light naphtha. Further, 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 wt%–80 wt%, with the remainder being normal C5-C6 normal hydrocarbons and a small amount of C4 hydrocarbons. - and C6 + Hydrocarbons.

[0039] Further, in step (1), the olefin-rich stream is selected from pure olefins or olefin-rich light naphtha. The pure olefin is selected from at least one of butene, pentene, and hexene. This invention does not impose any particular limitation on the proportion of butene, pentene, and hexene in the olefin-rich stream. The olefin-rich light naphtha is one or more of catalytic cracking light naphtha and delayed coking light naphtha. This 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%.

[0040] Further, in step (1), the olefin content in the reaction stream is 0.05 wt% to 1.5 wt%, preferably 0.08 wt% to 1.0 wt%, for example, but not limited to, 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%, and 0.9 wt%.

[0041] Furthermore, in step (2), the conditions for the light naphtha conversion reaction are: reaction pressure of 2.0–8.0 MPaG, reaction temperature of 350–450 °C, and liquid hourly space velocity of 0.5–5.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 100:1 to 2000:1.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The light naphtha conversion catalyst of this invention comprises ZSM-5 molecular sieve and macroporous alumina supported on Group VIB and Group VIII metals, and controls the amount of Brønsted acid (B acid) in the catalyst. A The total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt molar ratio I A / I mt The value is 5–0.5. Furthermore, 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 mtThe molar ratio is 0.60–0.90. The catalyst of this invention can significantly improve the conversion activity of light naphtha and the proportion of n-alkanes in the products, while reducing the carbon deposition content. Specifically, the catalyst of this invention exhibits low hydrogenation activity within the molecular sieve channels, which is beneficial for improving the conversion reaction activity. Simultaneously, due to the restriction of the molecular sieve channels, the reaction intermediate olefins are less prone to carbon deposition. The n-olefins or small molecule olefins obtained from the conversion of light hydrocarbons diffuse out of the molecular sieve channels and rapidly contact the hydrogenation centers on the macroporous alumina, undergoing a saturation reaction, thus preventing carbon deposition and improving catalyst stability.

[0044] In the preparation method of the catalyst of this invention, Group VIB and VIII metals are first supported on macroporous alumina, then mixed with ZSM-5 molecular sieves, shaped, and calcined to obtain the catalyst. The inventors have discovered that by comprehensively coordinating each step, the amount of Brønsted acid (B acid) in the catalyst can be controlled. A The total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt molar ratio I A / I mt The concentration is 5–0.5. Furthermore, by controlling the impregnation conditions, the total amount of Group VIB and Group VIII metals on the catalyst surface is adjusted to I0.5. ms The total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt The molar ratio is controlled between 0.60 and 0.90. This catalyst, used in the conversion of light naphtha, can significantly improve the conversion rate and the proportion of n-alkanes in the product, while also reducing the carbon deposit content.

[0045] This invention introduces a small amount of olefin-rich stream into the light naphtha conversion process. The introduced olefins can rapidly react with the acidic centers of the catalyst to generate carbocations. After the carbocations complete the reaction, they continue to propagate, allowing the reaction to proceed continuously, thus acting as an initiator. The metal in the catalyst no longer needs to complete the dehydrogenation initiation process; it only needs to complete the hydrogenation to avoid catalyst deactivation, thereby enabling the reaction to proceed at a lower metal content. 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 total amount of Group VIB and Group VIII metals on the catalyst surface is I msThe 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 C1s (284.6 eV). The data obtained directly from XPS are mass percentages. ms The values ​​are converted to mol / g.

[0048] 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. mt The values ​​are converted 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.

[0049] 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.

[0050] 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) adsorption. Because the diameter of pyridine molecules is smaller than that of molecular sieve channels, this method can obtain the amount of B acid, expressed in mol / g.

[0051] In this invention, unless otherwise specified, all percentages (%) in the embodiments and comparative examples refer to mass fractions.

[0052] 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.

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

[0054] 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%;

[0055] 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.

[0056] In this invention, the olefin-rich stream introduced in each example is a mixed olefin of butene, pentene, and hexene. The olefin content refers to the total content of butene, pentene, and hexene.

[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] 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) and 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 macroporous alumina loaded with nickel oxide and tungsten oxide, denoted as 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 a catalyst, denoted as CAT-1, the properties of which are shown in Table 1.

[0060] Comparative Example 1

[0061] 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 AZ-D1. 100g of AZ-D1 was impregnated in 200mL of an aqueous solution containing 1.5g / 100mL nickel and 8.0g / 100mL tungsten (based on oxides) for 2 hours. After filtration, drying at 120℃ for 3 hours, and calcining at 500℃ for 4 hours, a catalyst was obtained, denoted as CAT-D1. Its properties are shown in Table 1.

[0062] Comparative Example 2

[0063] 100g of macroporous alumina was impregnated for 2h in 200mL of an aqueous solution containing 8.0g / 100mL nickel and 40.0g / 100mL tungsten (based on oxides), with 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 macroporous alumina loaded with nickel oxide and tungsten oxide, denoted as 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 a catalyst, denoted as CAT-D2, the properties of which are shown in Table 1.

[0064] Comparative Example 3

[0065] 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 (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 CAT-D3. Its properties are shown in Table 1.

[0066] Comparative Example 4

[0067] Take 100g of small-pore alumina (pore volume 0.48cm³). 3 / g, specific surface area is 251cm³ 2 A small-pore alumina loaded with nickel oxide and tungsten oxide, denoted as A-NW-D4, was obtained by impregnation in 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) at pH 9.0 for 2 h under an impregnation pressure of 1.0 MPa and an impregnation temperature of 60 °C. 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 CAT-D4, the properties of which are shown in Table 1.

[0068] Example 2

[0069] 100g of macroporous alumina was impregnated for 2h in 200mL of an aqueous solution containing 1.0g / 100mL nickel and 5.0g / 100mL tungsten (based on oxides), with a pH of 9.0. The impregnation pressure was 0.5MPa and the impregnation temperature was 70℃. After impregnation, the alumina was cooled to room temperature, filtered, dried at 120℃ for 3h, and calcined at 450℃ for 3h to obtain macroporous alumina loaded with nickel oxide and tungsten oxide, denoted as 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 a catalyst, denoted as CAT-2, the properties of which are shown in Table 1.

[0070] Example 3

[0071] 100g of macroporous alumina was impregnated for 2h in 200mL of an aqueous solution containing 2.0g / 100mL nickel and 10.0g / 100mL tungsten (based on oxides), with a pH of 10.0. The impregnation pressure was 2.0MPa and the impregnation temperature was 80℃. After impregnation, the alumina was cooled to room temperature, filtered, dried at 120℃ for 3h, and calcined at 450℃ for 3h to obtain macroporous alumina loaded with nickel oxide and tungsten oxide, denoted as 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 a catalyst, denoted as CAT-3, whose properties are shown in Table 1.

[0072] Example 4

[0073] 100g of macroporous alumina was impregnated for 2h in 200mL of an aqueous solution containing 1.0g / 100mL nickel and 5.0g / 100mL tungsten (based on oxides), with a pH of 8.0. The impregnation pressure was 2.0MPa and the impregnation temperature was 80℃. After impregnation, the alumina was cooled to room temperature, filtered, dried at 120℃ for 3h, and calcined at 450℃ for 3h to obtain macroporous alumina loaded with nickel oxide and tungsten oxide, denoted as 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 a catalyst, denoted as CAT-4, whose properties are shown in Table 1.

[0074] Table 1. Composition and properties of catalysts obtained in the examples and comparative examples.

[0075]

[0076] Note: The alumina content of CAT-D4 is calculated based on microporous alumina, while the content of the other catalysts is calculated based on macroporous alumina.

[0077] Example 5

[0078] 10g of catalyst CAT-1 was placed in a fixed-bed reactor and reacted 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 olefin content in the reaction stream was 0.05%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 3.

[0079] Example 6

[0080] 10g of catalyst CAT-2 was placed in a fixed-bed reactor and reacted at a pressure of 4.0 MPa, a hydrogen-to-oil volume ratio of 800:1, 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 olefin content in the reaction stream was 0.2%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 3.

[0081] Example 7

[0082] 10g of catalyst CAT-3 was placed in a fixed-bed reactor and reacted at a reaction pressure of 4.0 MPa, a hydrogen-to-oil volume ratio of 800:1, 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 olefin content in the reaction stream was 0.2%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 3.

[0083] Example 8

[0084] 10g of catalyst CAT-4 was placed in a fixed-bed reactor. The reaction was carried out at a pressure of 4.0 MPa, a hydrogen-to-oil volume ratio of 800:1, 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 olefin content in the reaction stream was 0.2%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 3.

[0085] Example 9

[0086] 10g of catalyst CAT-2 was placed in a 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. -1The light naphtha conversion reaction was carried out at a reaction temperature of 400℃. The olefin content in the reaction stream was 0.1%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 3.

[0087] Example 10

[0088] 10g of catalyst CAT-2 was placed in a fixed-bed reactor and reacted at a pressure of 4.0 MPa, a hydrogen-to-oil volume ratio of 600:1, 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 olefin content in the reaction stream was 0.5%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 3.

[0089] Comparative Example 5

[0090] 10g of catalyst CAT-D1 was placed in a fixed-bed reactor and reacted 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 olefin content in the reaction stream was 0.05%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 4.

[0091] Comparative Example 6

[0092] 10g of catalyst CAT-D1 was placed in a fixed-bed reactor and reacted 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 reaction stream did not contain olefins. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 4.

[0093] Comparative Example 7

[0094] 10g of catalyst CAT-1 was placed in a fixed-bed reactor and reacted 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 reaction stream did not contain olefins. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 4.

[0095] Comparative Example 8

[0096] 10g of catalyst CAT-D2 was placed in a 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 olefin content in the reaction stream was 0.05%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 4.

[0097] Comparative Example 9

[0098] 10g of catalyst CAT-D2 was placed in a 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 reaction stream did not contain olefins. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 4.

[0099] Comparative Example 10

[0100] 10g of catalyst CAT-D3 was placed in a fixed-bed reactor and reacted 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 olefin content in the reaction stream was 0.05%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 4.

[0101] Comparative Example 11

[0102] 10g of catalyst CAT-D4 was placed in a 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 olefin content in the reaction stream was 0.05%. The properties of the light naphtha are shown in Table 2. After running for 160 hours, the conversion rate, yield of each component, and catalyst carbon deposition are shown in Table 4.

[0103] Table 2 Hydrocarbon Composition of Raw Material Light Naphtha

[0104] Hydrocarbon composition, wt% Isobutane 5.2 n-Butane 5.7 isopentane 53.2 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, % 18.5 Initial boiling point, ℃ 25.3 Final boiling point, ℃ 75.2

[0105] Table 3 Evaluation results of the catalysts in the examples

[0106]

[0107] Table 4 Evaluation results of comparative catalysts

[0108]

[0109] 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 light naphtha conversion catalyst, said catalyst comprising ZSM-5 molecular sieve and macroporous alumina supported on Group VIB and Group VIII metals, wherein, The amount of Brønsted acid in the naphtha conversion catalyst 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 The value is 0.5 to 5.0, preferably 1.5 to 3.

0.

2. The catalyst according to claim 1, characterized in that: Based on the weight of the catalyst, the ZSM-5 molecular sieve content is 30wt% to 80wt%, the macroporous alumina content 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%.

3. The catalyst according to claim 1, characterized in that: In macroporous alumina loaded with Group VIB and Group VIII metals, the Group VIB metals are preferably molybdenum and / or tungsten, and the Group VIII metals are preferably cobalt and / or nickel.

4. The catalyst according to claim 1, characterized in that: 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.

5. The catalyst according to claim 1, characterized in that: The total amount of Group VIB and Group VIII metals on the catalyst surface 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.

6. A method for preparing a light naphtha conversion catalyst, comprising the following steps: (1) Macroporous alumina was 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. (2) The macroporous alumina loaded with Group VIB and Group VIII metals obtained in step (1) is mixed with ZSM-5 molecular sieve, shaped, and calcined to obtain a light naphtha conversion catalyst.

7. The preparation method according to claim 6, characterized in that: In step (1), the impregnation is performed using a pressure impregnation method; preferably, the impregnation conditions include: a pressure of 0.5 to 3.0 MPa, a temperature of 60 to 80°C, and an impregnation time of 1 to 4 hours. And / or, in step (1), in the impregnation solution containing Group VIB metal and Group VIII metal, the Group VIB metal source is one or more of tungsten salt or molybdenum salt, and the Group VIII metal source is one or more of nickel salt or cobalt salt. Preferably, in the impregnation solution containing Group VIB metals and Group VIII metals, the mass content of Group VIB metals, calculated as oxides, is 3.0 to 30.0 g / 100 mL, and the mass content of Group VIII metals, calculated as oxides, is 1.0 to 10.0 g / 100 mL. Preferably, the pH value of the impregnation solution containing Group VIB metals and Group VIII metals is 8.0 to 10.

0.

8. The preparation method according to claim 6, characterized in that: 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.

9. The preparation method according to claim 6, characterized in that: In step (1), the roasting temperature is 400℃~600℃; the roasting time is 3~5h; and / or, in step (2), the roasting temperature is 400℃~600℃; the roasting time is 3~5h.

10. The preparation method according to claim 6, characterized in that: In step (2), 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.

11. The preparation method according to claim 6, characterized in that: In step (2), 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.

12. The preparation method according to claim 6, characterized in that: The amount of Brønsted acid I in the catalyst obtained in step (2) A The total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt molar ratio I A / I mt The value is 0.5 to 5.0, preferably 1.5 to 3.0; And / or, the total amount of Group VIB and Group VIII metals on the catalyst surface I ms The total amount of Group VIB and Group VIII metals in the bulk catalyst phase I mt The ratio is 0.60 to 0.

90.

13. A method for converting light naphtha, comprising: (1) Saturated naphtha and olefin-rich streams are mixed to obtain a reaction stream; (2) The reaction stream from step (1) is mixed with hydrogen and reacted with any of the catalysts described in claims 1-5 to obtain the reaction product.

14. The method according to claim 13, characterized in that: The saturated 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. Preferably, the mass content of C5-C6 isoalkanes in the light naphtha is 30wt% to 90wt%, and more preferably 50wt% to 80wt%.

15. The method according to claim 13, characterized in that: The olefin-rich stream 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%.

16. The method according to claim 13 or 15, characterized in that: In step (1), the olefin content in the reaction stream is 0.05 wt% to 1.5 wt%, preferably 0.08 wt% to 1.0 wt%.

17. The method according to claim 13, characterized in that: The conditions for the conversion of light naphtha are: reaction pressure of 2.0–8.0 MPaG, reaction temperature of 350–450℃, and liquid hourly space velocity of 0.5–5.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 100:1 to 2000:1.

Images