A selective hydrodesulfurization catalyst for catalytic cracking gasoline and a preparation method and application thereof

Abstract

The application provides a selective hydrodesulfurization catalyst for catalytic cracking gasoline and a preparation method and application thereof, wherein the catalyst comprises a SiO2 / γ-Al2O3 composite carrier and main active metal sulfide and auxiliary active metal sulfide loaded on the composite carrier; in the SiO2 / γ-Al2O3 composite carrier, SiO2 covers the inner surface and the outer surface of γ-Al2O3, the content of SiO2 is 1.0-10.0 wt% based on the total weight of the composite carrier; the content of the main active metal in oxide form is 2.0-20.0 wt% based on the total weight of the catalyst, and the content of the auxiliary active metal in oxide form is 1.0-10.0 wt%; in the catalyst, the concentration of the main active metal-auxiliary active metal-sulfur active site is 0.18-0.50 mmol / g. The catalyst has high desulfurization activity and low olefin saturation activity for high-sulfur FCC gasoline.

Description

TECHNICAL FIELD

[0001] The present application relates to a selective hydrodesulfurization catalyst for catalytic cracking gasoline and a preparation method and application thereof, and belongs to the technical field of selective hydrodesulfurization. BACKGROUND

[0002] FCC gasoline is a mixture of C4-C 12 hydrocarbons and trace amounts of sulfides, oxides and metal arsenides, according to the differences in the properties of crude oil and processing routes of various refining enterprises, FCC gasoline is a mixture of 18-55v% olefins, 12-20v% aromatic hydrocarbons and alkanes, the octane value characteristics of each component are aromatic hydrocarbons>olefins≈isomeric alkanes>alkanes. Generally, high sulfur, high olefin content and low octane value FCC gasoline accounts for a high proportion, while low sulfur content, low olefin content, high octane value alkylate oil, isomerate oil and reformate oil accounts for a low proportion, which makes the cleaning of FCC gasoline need to carry the triple task of desulfurization, olefin reduction and octane value maintenance at the same time.

[0003] Gasoline hydrodesulfurization catalysts can use a variety of supports, such as Okamoto et al. (Applied Catalysis A: General, 2002, 226: 115-127) studied the support effect of CoMoS catalysts on hydrodesulfurization activity (HDS) and olefin hydrogenation saturation activity (HYD). The results show that the HDS activity is positively correlated with the amount of CoSx species located at the edge of MoS2 (CoMoS concentration); CoMoS supported on different supports (such as Al2O3, SiO2, TiO2 and ZrO2) has the same HYD activity, but CoMoS supported on SiO2 has higher HDS activity, so CoMoS supported on SiO2 has higher HDS activity and selectivity. The defects of this technology or the deficiencies of the present application are: although CoMoS catalyst supported on SiO2 has the highest HDS activity, the preparation procedure of SiO2 support is complex and not convenient for industrial production.

[0004] CN102335612A discloses a selective hydrodesulfurization catalyst, which takes cobalt and molybdenum as active components, and takes SiO2 and Al2O3 as carriers. The carrier is prepared by molding, drying and calcining pseudo-boehmite and silica precursor (or pseudo-boehmite containing silica or pseudo-boehmite, silica precursor and alkali earth metal soluble salt). The catalyst is used for FCC gasoline with sulfur content of 430 mg / kg and olefin content of 45.25 v%. The average olefin saturation rate of the hydrogenated gasoline product is 10%, the selectivity factor is mostly greater than 18%, and the octane loss is not greater than 0.8. The defects of this technology or the deficiencies of the present application are as follows: the traditional preparation process of the SiO2 / Al2O3 composite carrier is adopted by using pseudo-boehmite and silica precursor as raw materials, and the prepared carrier has a certain degree of random distribution and mutual embedding between SiO2 and Al2O3. The surface Al 3+ species are mostly present, and the surface Al 3+ species have strong interaction with cobalt and molybdenum active metal precursors. Moreover, the impregnation solution of cobalt and molybdenum active metal precursors does not contain a complexing agent, which inevitably causes strong interaction between the Al 3+ species and the cobalt and molybdenum active metal precursors, which is not conducive to the sulfidation of cobalt and molybdenum to form a high-activity cobalt-molybdenum-sulfur active phase. Therefore, the average sulfur content of the hydrogenated gasoline product of the catalyst prepared by the technology is as high as 60.2 mg / kg, which is far from the clean gasoline quality standard requirement of not greater than 10 mg / kg.

[0005] CN114425455A discloses a method for preparing a SiO2-coated alumina catalytic carrier material. The preparation method of the catalytic carrier material is to first configure a coating liquid containing a silicon compound (one or more of silica sol, water glass and white carbon black), an organic carbon precursor (one or more of sugar substances, flour, polyvinyl alcohol, polyethylene glycol and cellulose ether) and water; then introducing the coating liquid into the carrier matrix, and further drying and calcining to obtain a carrier with high wear resistance. The defects of this technology or the deficiencies of the present application are as follows: the coating liquid (containing a silicon compound, an organic carbon precursor and water) is a suspension liquid, which is difficult to enter the inner surface of the alumina pores, and most of it is coated on the outer surface of the carrier matrix (the catalytic material prepared by the carrier has the characteristics of a ink bottle mouth with more active metals in the center and less on the edge), which is not conducive to the reaction and diffusion of reactants and products in the catalyst.

[0006] Therefore, it has become a technical problem to be solved in the field to provide a new selective hydrodesulfurization catalyst for catalytic cracking gasoline and a preparation method and application thereof. SUMMARY

[0007] In order to solve the above-mentioned defects and deficiencies, one object of the present application is to provide a catalytic cracking gasoline selective hydrodesulfurization catalyst.

[0008] Another object of the present application is to provide a preparation method of the above-mentioned catalytic cracking gasoline selective hydrodesulfurization catalyst.

[0009] Still another object of the present application is to provide an application of the above-mentioned catalytic cracking gasoline selective hydrodesulfurization catalyst in selective hydrodesulfurization of FCC gasoline.

[0010] In order to achieve the above-mentioned objects, in one aspect, the present application provides a catalytic cracking gasoline selective hydrodesulfurization catalyst, wherein the catalytic cracking gasoline selective hydrodesulfurization catalyst comprises a SiO2 / γ-Al2O3 composite carrier and a main active metal sulfide and an auxiliary active metal sulfide supported on the composite carrier.

[0011] In the SiO2 / γ-Al2O3 composite carrier, the SiO2 covers the inner surface (the inner surface of γ-Al2O3 refers to the surface of the pore structure contained in γ-Al2O3) and the outer surface of γ-Al2O3, and the content of SiO2 is 1.0-10.0 wt%, preferably 2.0-9.0 wt%, based on 100% of the total weight of the composite carrier.

[0012] The content of the main active metal in terms of oxide is 2.0-20.0 wt%, preferably 7.0-15.0 wt%, and the content of the auxiliary active metal in terms of oxide is 1.0-10.0 wt%, preferably 2.0-9.0 wt%, based on 100% of the total weight of the catalyst.

[0013] In the catalytic cracking gasoline selective hydrodesulfurization catalyst, the concentration of the main active metal-auxiliary active metal-sulfur active site is 0.18-0.50 mmol / g, preferably 0.20-0.50 mmol / g. In the catalytic cracking gasoline selective hydrodesulfurization catalyst provided by the present application, since the SiO2 covers the inner surface and the outer surface of γ-Al2O3, the main active metal oxide and the auxiliary active metal oxide are actually supported on the surface of SiO2.

[0014] As a specific embodiment of the above-mentioned catalyst of the present application, the content of SiO2 is 0.5-9.5 wt%, preferably 1.5-8.5 wt%, based on 100% of the total weight of the catalyst.

[0015] As a specific embodiment of the above-mentioned catalyst of the present application, wherein the SiO2 / γ-Al2O3 composite carrier has a water absorption rate of 90-120%, preferably 100-110%; a mechanical strength of 10-20 N / mm, preferably 12-18 N / mm; a BET specific surface area of 290-360 m 2 / g, preferably 300-350 m 2 / g; a pore volume of 1.0-1.4 mL / g, preferably 1.1-1.3 mL / g.

[0016] As a specific embodiment of the above-mentioned catalyst of the present application, wherein the SiO2 / γ-Al2O3 composite carrier has a total acid amount of 0.005-0.05 mmol / g.

[0017] As a specific embodiment of the above-mentioned catalyst of the present application, wherein the main active metal comprises Mo, etc., and the auxiliary active metal comprises Co, etc.

[0018] On the other hand, the present application also provides a preparation method of the above-mentioned catalytic cracking gasoline selective hydrodesulfurization catalyst, wherein the preparation method comprises:

[0019] Step (1): fully kneading, molding, drying and calcining an aqueous solution of alumina raw powder, extrusion aid and peptizing agent to obtain a γ-Al2O3 carrier;

[0020] Step (2): preparing an aqueous solution of sodium silicate and impregnating the aqueous solution onto the γ-Al2O3 carrier, and then performing aging, acidic water ultrasonic washing, decanting, drying and calcining to obtain a SiO2 / γ-Al2O3 composite carrier;

[0021] Step (3): preparing a co-impregnation solution containing a complexing agent, an auxiliary active metal salt and a main active metal salt;

[0022] Step (4): impregnating the co-impregnation solution into the SiO2 / γ-Al2O3 composite carrier in an equal volume, and then performing aging, drying and temperature-sulfurization to obtain the catalytic cracking gasoline selective hydrodesulfurization catalyst.

[0023] As a specific embodiment of the above-mentioned preparation method of the present application, in step (1), the alumina raw powder comprises pseudo-boehmite powder, etc., the extrusion aid comprises one or a combination of several of sesbania powder, polyacrylamide, graphite and lubricating oil, preferably one of sesbania powder, polyacrylamide and graphite, and the peptizing agent comprises one or a combination of several of nitric acid, hydrochloric acid, acetic acid and citric acid, preferably one of nitric acid, hydrochloric acid and acetic acid.

[0024] As a specific embodiment of the above-mentioned preparation method of the present application, the weight content of the extrusion aid and the peptizing agent is 4-10 wt% and 2-5 wt%, respectively, based on the total weight of the dry base of the γ-Al2O3 carrier, and is preferably 5-9 wt% and 3-4 wt%, respectively.

[0025] As a specific embodiment of the above-mentioned preparation method of the present application, the calcination in step (1) is performed at 550-600°C for 4-6h.

[0026] As a specific embodiment of the above-mentioned preparation method of the present application, the water absorption, the strength, the BET specific surface area and the pore volume of the γ-Al2O3 carrier are 90-150%, 8-20 N / mm, 290-360 m 2 / g and 0.8-1.6 mL / g, respectively, and are preferably 100-140%, 10-15 N / mm, 300-350 m 2 / g and 0.9-1.5 mL / g, respectively.

[0027] As a specific embodiment of the above-mentioned preparation method of the present application, the ratio of the number of moles of silicon dioxide (SiO2) to the number of moles of sodium oxide (Na2O) [modulus (n)] in the sodium silicate in step (2) is 1.5-3.0, and is preferably 1.7-2.8.

[0028] As a specific embodiment of the above-mentioned preparation method of the present application, the acid used in the acidic water in step (2) is one of nitric acid, hydrochloric acid, acetic acid, sulfuric acid and the like, and is preferably one of nitric acid, hydrochloric acid, acetic acid and the like.

[0029] As a specific embodiment of the above-mentioned preparation method of the present application, the calcination in step (2) is performed at 550-600°C for 4-6h.

[0030] As a specific embodiment of the above-mentioned preparation method of the present application, the molar ratio of the complexing agent to the active metal salt in the co-impregnation solution in step (3) is 1.2-2.2:1, and is preferably 1.5-1.7:1.

[0031] As a specific embodiment of the above-mentioned preparation method of the present application, the pH value of the co-impregnation solution in step (3) is greater than 8.1, and is preferably greater than 8.2.

[0032] As a specific embodiment of the above-mentioned preparation method of the present application, the complexing agent in step (3) includes one of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid, ethylenediamine, cyclohexanediaminetetraacetic acid, citric acid, ethylene glycol and the like, and is preferably one of ethylenediaminetetraacetic acid, nitrilotriacetic acid, cyclohexanediaminetetraacetic acid.

[0033] As a specific embodiment of the above-mentioned preparation method of the present application, in step (3), the promoter metal salt comprises one or a combination of several of nitrate, acetate and carbonate of the promoter metal, and the main active metal salt comprises one or a combination of several of ammonium salt and thioammonium salt of the main active metal.

[0034] When the promoter metal is Co, its salt is one or a combination of several of cobalt nitrate, cobalt acetate and cobalt carbonate, preferably cobalt nitrate or cobalt acetate; when the main active metal is Mo, its salt is one or a combination of several of ammonium heptamolybdate, ammonium tetramolybdate and ammonium tetrathiomolybdate, preferably ammonium heptamolybdate or ammonium tetrathiomolybdate.

[0035] As a specific embodiment of the above-mentioned preparation method of the present application, in step (4), the maximum sulfuration temperature is 280-360℃, preferably 300-360℃; the cumulative time of temperature rising and sulfuration is 20-100h, preferably 25-50h; the sulfuration pressure is 1.0-3.0MPa, preferably 1.5-2.5MPa; the volume space velocity of sulfuration oil is 1.0-3.0h -1 , preferably 1.0-2.0h -1 ; the hydrogen / oil volume ratio is 200:1-500:1, preferably 250:1-350:1.

[0036] As a specific embodiment of the above-mentioned preparation method of the present application, in step (4), the sulfuration reagent used in the sulfuration comprises one or a combination of several of dimethyl disulfide, carbon disulfide, methyl mercaptan, ethyl mercaptan and sulfide (such as methyl sulfide), preferably dimethyl disulfide or carbon disulfide.

[0037] In another aspect, the present application further provides the use of the above-mentioned selective hydrodesulfurization catalyst for catalytically cracked gasoline in selective hydrodesulfurization of FCC gasoline.

[0038] Compared with the prior art, the present application can achieve the following beneficial technical effects:

[0039] (1) The present application first prepares a γ-Al2O3 carrier, then prepares an aqueous solution of sodium silicate and impregnates the aqueous solution into the γ-Al2O3 carrier, at this time, the sodium silicate is loaded on the inner and outer surfaces of the γ-Al2O3 through impregnation, and finally, the impregnated product is sequentially subjected to aging, ultrasonic water washing with acidic water, decantation, drying, and calcination, during the calcination process, the sodium silicate is converted into SiO2 and covers the inner and outer surfaces of the γ-Al2O3, thereby obtaining a SiO2 / γ-Al2O3 composite carrier, that is, the inner and outer surfaces of most of the pores of the composite carrier are covered by SiO2, and the SiO2 / γ-Al2O3 composite carrier in which the SiO2 covers the inner and outer surfaces of the γ-Al2O3 creates a prerequisite for the selective loading of the salts of the main active metal, the auxiliary active metal and other metals on the surface of the SiO2 in the composite carrier.

[0040] (2) Based on the above improved SiO2 / γ-Al2O3 composite carrier, in the preparation of the selective hydrodesulfurization catalyst for catalytically cracked gasoline, a complexing agent (the complexing agent preferentially complexes with the main and auxiliary active metal cation species, mainly the auxiliary active metal cation species and the Al 3+ not covered by SiO2 on the surface of the SiO2 / γ-Al2O3 composite carrier) is added to the co-impregnation solution, and by adjusting the molar ratio of the complexing agent to the auxiliary metal and the pH value of the co-impregnation solution, the selective loading of the salts of the main active metal and the auxiliary metal (such as the metal salts of Co and Mo) on the surface of the SiO2 in the composite carrier is achieved, and in the subsequent sulfidation process, more main active metal-auxiliary active metal-sulfur (such as CoMoS) active sites with high activity and high selectivity can be formed, so that the selective hydrodesulfurization catalyst for catalytically cracked gasoline has high desulfurization activity and low olefin saturation activity for high-sulfur FCC gasoline. DETAILED DESCRIPTION

[0041] It should be noted that the terms "comprising" and any variation thereof in the specification and claims of the present application are intended to cover non-exclusive inclusion, for example, a process, method, system, product or apparatus that includes a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatuses.

[0042] The ranges disclosed herein are meant to include any and all sub-ranges of the named ranges, including the range endpoints. For instance, a range from 60-120 should be interpreted to include not only 60-120 and 80- 110, but also 60- 80, 80- 100, 100- 120, etc.

[0043] In the present application, unless otherwise stated, the numerical range "a-b" means a shorthand notation for representing any real combination of numbers between a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in the present application, and "0-5" is just a shorthand notation for these numerical combinations.

[0044] In the present application, unless otherwise stated, all embodiments and preferred embodiments mentioned in the present application can be combined with each other to form new technical solutions.

[0045] In the present application, unless otherwise stated, all technical features and preferred features mentioned in the present application can be combined with each other to form new technical solutions.

[0046] In the present application, unless otherwise stated, all steps mentioned herein can be performed in sequence or randomly, but preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method further comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0047] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be given below in combination with the accompanying tables and examples. The examples described below are part of the examples of the present application, but not all the examples, which are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the examples in the present application, all the other examples obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. If no specific conditions are indicated in the examples, the conventional conditions or the conditions recommended by the manufacturer are adopted. If no manufacturer of the reagents or instruments is indicated, it is a conventional product that can be purchased in the market.

[0048] Carrier examples and comparative examples

[0049] Example 1

[0050] In this example, SiO2 / γ-Al2O3 composite carrier (ZAT-1) was prepared. First, 300 g of pseudoboehmite powder and 15.0 g of sesbania powder were mixed uniformly, and then 9.0 g of concentrated nitric acid (65 wt%) and 540 g of deionized water were added. After kneading thoroughly, 1.5-3.0 mm clover-shaped strips were extruded in an extruder, and then dried at 120℃ for about 4 h and calcined at 520℃ for about 4 h. After cooling and sieving, 3-10 mm long γ-Al2O3 carrier (ZAT-D1, total dry weight of the prepared γ-Al2O3 was 225 g) was obtained. Then, an aqueous solution of sodium silicate (n = 2.1) was prepared and impregnated on 100 g of ZAT-D1. After aging overnight, it was treated with 2.5 wt% hydrochloric acid solution at 30℃ for 20 min under ultrasonic, and then decanted. The above process was repeated three times. Then, it was treated with deionized water at 30℃ for 20 min under ultrasonic, and then decanted. After drying at 120℃ for 4 h and calcining at 550℃ for 6 h, ZAT-1 was obtained.

[0051] Example 2

[0052] In this example, SiO2 / γ-Al2O3 composite carrier (ZAT-2) was prepared. The difference between this example and Example 1 is that an aqueous solution of sodium silicate (n = 2.2) was impregnated on 100 g of ZAT-D1. After aging overnight, it was treated with 3.0 wt% nitric acid solution under ultrasonic. After the second decantation, it was first dried at 110℃ for 6 h, and then calcined at 580℃ for 5 h.

[0053] Example 3

[0054] Example 3

[0055] Example 4

[0056] Example 3

[0057] Comparative Example 1

[0058] Comparative Example 1

[0059] The SiO2 / γ-Al2O3 composite carriers (ZAT-1 to ZAT-4, ZAT-D1 and ZAT-D2) were measured for SiO2 content, water absorption, strength, BET specific surface area, pore volume and total acid amount by X-ray fluorescence method, saturated immersion method, the method specified in Q / SH-361926, the method specified in GB / T-5816, the method specified in Q / SH-361913 and ammonia temperature programmed desorption method, respectively. The composition and physicochemical properties of the carriers are shown in Table 1 below.

[0060] Table 1 Composition and physicochemical properties of carriers

[0061]

[0062] As can be seen from Table 1, the water absorption, strength, BET specific surface area and pore volume of ZAT-1 to ZAT-4 change little compared with ZAT-D1 and ZAT-D2, but the total acid amount on the surface of ZAT-1 to ZAT-4 decreases obviously, which indicates that the Al content on the surface of ZAT-1 to ZAT-4 carriers provided by the embodiments of the present application is lower than that of ZAT-D1 and ZAT-D2. 3+The obvious decrease can prove that the inner and outer surfaces of the most of the pores of the SiO2 / γ-Al2O3 composite carrier provided or used by the embodiment of the present application are covered by SiO2. It can also be seen from Table 1 that, compared with ZAT-D1 prepared by using pseudo-boehmite powder, ZAT-D2 prepared by using pseudo-boehmite powder containing silicon contains SiO2, and thus it can expose less surface Al 3+ The species, i.e. the amount of acid of the ZAT-D2 is less.

[0063] Catalyst Examples and Comparative Examples

[0064] Example 5

[0065] The catalyst CAT-1 is prepared in this example, and the preparation method comprises the following specific steps:

[0066] A co-impregnation solution containing EDTA, cobalt nitrate and ammonium heptamolybdate is prepared, wherein the molar ratio of EDTA and cobalt nitrate is 1.5:1, and the pH of the co-impregnation solution is adjusted to 9.8 by adding concentrated ammonia water;

[0067] The co-impregnation solution is impregnated into ZAT-1 in an equal volume, and after the conventional aging and drying procedures, a semi-finished product is obtained. The semi-finished product is loaded into a 200 mL fixed bed reactor for sulfidation. The sulfidation oil is straight-run naphtha, and the sulfidation agent is carbon disulfide. The concentration of carbon disulfide is 1.5 wt.% based on the total weight of the sulfidation oil, the sulfidation pressure is 2.0 MPa, the hydrogen / oil volume ratio is 300:1, and the sulfidation oil volume space velocity is 1.5 h -1 ; The temperature rising process is: first, under a nitrogen atmosphere, the temperature is raised from room temperature to 180℃ at a temperature rising rate of 30℃ / h, and then the nitrogen is switched to hydrogen, the sulfidation oil is started to be injected, and the temperature is raised from 180℃ to 230℃ at a temperature rising rate of 20℃ / h, and then the temperature is kept constant for 4h, and finally the temperature is raised from 230℃ to 350℃ at a temperature rising rate of 20℃ / h, and then the temperature is kept constant for 4h, to obtain CAT-1.

[0068] Example 6

[0069] The catalyst CAT-2 is prepared in this example, and the preparation method comprises the following specific steps:

[0070] A co-impregnation solution containing cyclohexanediaminetetraacetic acid, cobalt nitrate and ammonium heptamolybdate is prepared, wherein the molar ratio of cyclohexanediaminetetraacetic acid and cobalt nitrate is 2.0:1, and the pH of the co-impregnation solution is adjusted to 8.8 by adding concentrated ammonia water;

[0071] The co-impregnation solution was impregnated into ZAT-2 in an equal volume, and after the conventional aging and drying procedures, a semi-finished product was obtained. The semi-finished product was loaded into a 200 mL fixed bed reactor for vulcanization. The vulcanizing oil was straight-run naphtha, the vulcanizing agent was dimethyl disulfide, the concentration of dimethyl disulfide was 1.5 wt.% based on the total weight of the vulcanizing oil, the vulcanization pressure was 1.5 MPa, the hydrogen to oil volume ratio was 250:1, and the volume space velocity of the vulcanizing oil was 1.2 h -1 The temperature rising process was as follows: first, the temperature was raised from room temperature to 180°C at a rate of 30°C / h under a nitrogen atmosphere, and then kept constant for 2 h; then the nitrogen was switched to hydrogen, the vulcanizing oil was injected, and the temperature was raised from 180°C to 230°C at a rate of 20°C / h, and kept constant for 4 h; finally, the temperature was raised from 230°C to 360°C at a rate of 20°C / h, and kept constant for 2 h, to obtain CAT-2.

[0072] Example 7

[0073] In this example, a catalyst (CAT-3) was prepared by the following method:

[0074] A co-impregnation solution containing nitrilotriacetic acid, cobalt acetate and ammonium heptamolybdate was prepared, in which the molar ratio of nitrilotriacetic acid to cobalt acetate was 2.2:1, and the pH of the co-impregnation solution was adjusted to 9.0 by adding concentrated ammonia water;

[0075] The co-impregnation solution was impregnated into ZAT-3 in an equal volume, and after the conventional aging and drying procedures, a semi-finished product was obtained. The semi-finished product was loaded into a 200 mL fixed bed reactor for vulcanization. The vulcanizing oil was straight-run naphtha, the vulcanizing agent was methyl mercaptan, the concentration of methyl mercaptan was 1.5 wt.% based on the total weight of the vulcanizing oil, the vulcanization pressure was 1.6 MPa, the hydrogen to oil volume ratio was 270:1, and the volume space velocity of the vulcanizing oil was 1.6 h -1 The temperature rising process was as follows: first, the temperature was raised from room temperature to 180°C at a rate of 30°C / h under a nitrogen atmosphere, and then kept constant for 2 h; then the nitrogen was switched to hydrogen, the vulcanizing oil was injected, and the temperature was raised from 180°C to 230°C at a rate of 20°C / h, and kept constant for 4 h; finally, the temperature was raised from 230°C to 340°C at a rate of 20°C / h, and kept constant for 5 h, to obtain CAT-3.

[0076] Example 8

[0077] In this example, a catalyst (CAT-4) was prepared by the following method:

[0078] A co-impregnation solution containing ethylenediamine, cobalt acetate and ammonium tetramolybdate was prepared, in which the molar ratio of ethylenediamine to cobalt acetate was 1.6:1, and the pH of the co-impregnation solution was adjusted to 9.8 by adding concentrated ammonia water;

[0079] The co-impregnation solution was impregnated into ZAT-4 in an equal volume, and after a conventional aging and drying procedure, a semi-finished product was obtained. The semi-finished product was loaded into a 200 mL fixed bed reactor for vulcanization. The vulcanization oil was straight-run naphtha, and the vulcanizing agent was ethyl mercaptan. The concentration of ethyl mercaptan was 1.5 wt.% based on the total weight of the vulcanization oil. The vulcanization pressure was 1.9 MPa, the hydrogen to oil volume ratio was 320:1, and the volume space velocity of the vulcanization oil was 1.8 h-1. -1 The temperature rising process was as follows: first, the temperature was raised from room temperature to 180°C at a rate of 30°C / h under a nitrogen atmosphere, and then kept constant for 2 h. Then, the nitrogen was switched to hydrogen, the vulcanization oil was injected, and the temperature was raised from 180°C to 230°C at a rate of 20°C / h, and kept constant for 4 h. Finally, the temperature was raised from 230°C to 345°C at a rate of 20°C / h, and kept constant for 4.5 h, to obtain CAT-4.

[0080] Example 9

[0081] A catalyst (CAT-5) was prepared in this example. The preparation method included the following specific steps:

[0082] A co-impregnation solution containing EDTA, cobalt nitrate, and ammonium heptamolybdate was prepared, in which the molar ratio of EDTA to cobalt nitrate was 1.9:1. The pH of the co-impregnation solution was adjusted to 9.8 by adding concentrated ammonia water.

[0083] The co-impregnation solution was impregnated into ZAT-1 in an equal volume, and after a conventional aging and drying procedure, a semi-finished product was obtained. The semi-finished product was loaded into a 200 mL fixed bed reactor for vulcanization. The vulcanization oil was straight-run naphtha, and the vulcanizing agent was methyl mercaptan. The concentration of methyl mercaptan was 1.5 wt.%. The vulcanization pressure was 2.4 MPa, the hydrogen to oil volume ratio was 340:1, and the volume space velocity of the vulcanization oil was 1.9 h-1. -1 The temperature rising process was as follows: first, the temperature was raised from room temperature to 180°C at a rate of 30°C / h under a nitrogen atmosphere, and then kept constant for 2 h. Then, the nitrogen was switched to hydrogen, the vulcanization oil was injected, and the temperature was raised from 180°C to 230°C at a rate of 20°C / h, and kept constant for 4 h. Finally, the temperature was raised from 230°C to 355°C at a rate of 20°C / h, and kept constant for 3.5 h, to obtain CAT-5.

[0084] Comparative Example 2

[0085] A catalyst (CAT-D1) was prepared in this comparative example. The preparation method was compared with that of Example 5, and the only difference was that the pH of the co-impregnation solution containing EDTA, cobalt nitrate, and ammonium heptamolybdate was 7.5.

[0086] Comparative Example 3

[0087] A catalyst (CAT-D2) was prepared in this comparative example. The preparation method was compared with that of Example 5, and the only difference was that ZAT-D2 was used as the carrier.

[0088] Comparative Example 4

[0089] The comparative example prepared catalyst (CAT-D3) which the preparation method compared with example 5, the only difference is that ZAT-D2 is used as carrier, and the co-impregnation solution does not contain complexing agent.

[0090] Comparative Example 5

[0091] The comparative example prepared catalyst (CAT-D4) which the preparation method compared with example 5, the only difference is that ZAT-D1 is used as carrier, and the co-impregnation solution does not contain complexing agent.

[0092] Comparative Example 6

[0093] The comparative example prepared catalyst (CAT-D5) which the preparation compared with example 5, the only difference is that no complexing agent is used.

[0094] Comparative Example 7

[0095] The comparative example prepared catalyst (CAT-D6) which the preparation compared with example 5, the only difference is that ZAT-D1 is used.

[0096] Comparative Example 8

[0097] The comparative example prepared catalyst (CAT-D7) which the preparation compared with example 5, the only difference is that the molar ratio of complexing agent and auxiliary metal salt is 1.0:1.

[0098] The atomic absorption method, X-ray fluorescence method, CO infrared spectroscopy method are used to measure the MoO3 content, CoO content, SiO2 content and CoMoS active site concentration in the above catalysts (CAT-1 to CAT-5 and CAT-D1 to CAT-D7), and the results are shown in Table 2.

[0099] Table 2 Catalyst composition and physicochemical properties

[0100]

[0101] From Table 2, it can be seen that the catalyst provided by the example of the application has higher selective hydrodesulfurization CoMoS active site concentration compared with the comparative agent. This is due to the fact that the example of the application adds a complexing agent in the co-impregnation solution when preparing the selective hydrodesulfurization catalyst for catalytic cracking gasoline, and the complexing agent and Co 2+ and Al in SiO2 / γ-Al2O3 composite carrier 3+By preferential complexation and by adjusting the molar ratio of the complexing agent to the auxiliary metal and the pH value of the co-impregnation solution, the metal salts of Co and Mo can be selectively loaded on the SiO2 surface in the composite carrier. In the subsequent sulfidation process, more highly active and selective CoMoS active sites can be formed.

[0102] Catalyst performance evaluation examples

[0103] This evaluation example used a 200 mL fixed-bed reactor with FCC gasoline containing 1000 mg / kg sulfur, 50 v% olefins, and a research octane number (RON) of 91.5 as feedstock. The reactor inlet temperature was 230°C, the reaction pressure was 1.7 MPa, and the volumetric hourly space velocity (VHSV) was 2.6 h⁻¹. -1 Under the catalyst evaluation conditions of a hydrogen-to-oil volume ratio of 250:1, CAT-1 to CAT-5 and CAT-D1 to CAT-D7 were compared and evaluated. The total sulfur content of catalytic cracking gasoline and its hydrotreated products was determined according to SH / T 0689-2000, the RON content of catalytic cracking gasoline and its hydrotreated products was determined according to GB / T 5487-1995, and the olefin content of catalytic cracking gasoline and its hydrotreated products was determined according to GB / T 11132. The evaluation results are shown in Table 3 below.

[0104] Table 3. Analysis Data of Hydrogenated Gasoline Products

[0105] Item Total sulfur / mg / kg Olefin saturation rate / % RON loss CAT-1 9.2 8.0 1.3 CAT-2 8.5 7.2 1.2 CAT-3 9.0 7.5 1.3 CAT-4 7.2 7.0 1.2 CAT-5 9.6 8.5 1.4 CAT-D1 29.8 9.0 1.6 CAT-D2 248.8 10.0 1.7 CAT-D3 510.5 15.0 2.5 CAT-D4 671.7 18.1 3.5 CAT-D5 35.0 8.8 1.5 CAT-D6 235.2 10.5 1.8 CAT-D7 250.5 10.1 1.7

[0106] As shown in Table 3, for the aforementioned FCC gasoline feedstock, compared with the comparative agent, the catalyst provided in this embodiment of the invention produces hydrogenated gasoline products with lower sulfur content (<10 mg / kg) and olefin saturation (<9.0%), and less RON loss (<1.6%). This is attributed to the high concentration of CoMoS active sites in the selective hydrodesulfurization of the catalyst obtained in this embodiment of the invention.

[0107] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical inventions, and technical inventions in this invention can be freely combined and used.

Claims

1. A catalyst for selective hydrodesulfurization of catalytic cracking gasoline, characterized in that, The selective hydrodesulfurization catalyst for catalytic cracking gasoline includes a SiO2 / γ-Al2O3 composite support and a main active metal sulfide and a co-active metal sulfide supported on the composite support. In the SiO2 / γ-Al2O3 composite support, SiO2 covers both the inner and outer surfaces of γ-Al2O3, and the SiO2 content is 1.0-10.0 wt% based on the total weight of the composite support (100%). Based on the total weight of the catalyst (100%), the content of the main active metal (calculated as oxide) is 2.0-20.0 wt%, and the content of the co-active metal (calculated as oxide) is 1.0-10.0 wt%. In the selective hydrodesulfurization catalyst for catalytic cracking gasoline, the concentration of the main active metal-co-active metal-sulfur active sites is 0.18-0.50 mmol / g; The selective hydrodesulfurization catalyst for catalytic cracking gasoline is prepared by a method comprising the following steps: Step (1): The aqueous solution of alumina powder, extrusion aid and adhesive solvent is thoroughly mixed, shaped, dried and calcined to obtain γ-Al2O3 support; Step (2): Prepare an aqueous solution of sodium silicate and impregnate it onto the γ-Al2O3 support. After aging, ultrasonic washing with acidic water, decantation, drying and calcination, a SiO2 / γ-Al2O3 composite support is obtained. Step (3): Prepare a co-impregnation solution containing a complexing agent, a co-active metal salt and a main active metal salt, wherein the molar ratio of the complexing agent and the co-active metal salt in the co-impregnation solution is 1.2-2.2:1; Step (4): The co-impregnation liquid is impregnated onto the SiO2 / γ-Al2O3 composite support in equal volume, and then aged, dried and heated for sulfidation to obtain the selective hydrodesulfurization catalyst for catalytic cracking gasoline.

2. The catalyst according to claim 1, characterized in that, The SiO2 / γ-Al2O3 composite carrier has a water absorption rate of 90-120%, a mechanical strength of 10-20 N / mm, and a BET specific surface area of ​​290-360 m². 2 / g, pore volume is 1.0-1.4 mL / g; The total acidity of the SiO2 / γ-Al2O3 composite support is 0.005-0.05 mmol / g.

3. The catalyst according to claim 1 or 2, characterized in that, The primary active metal includes Mo, and the secondary active metal includes Co.

4. The method for preparing the selective hydrodesulfurization catalyst for catalytic cracking gasoline according to any one of claims 1-3, characterized in that, The preparation method includes: Step (1): The aqueous solution of alumina powder, extrusion aid and adhesive solvent is thoroughly mixed, shaped, dried and calcined to obtain γ-Al2O3 support; Step (2): Prepare an aqueous solution of sodium silicate and impregnate it onto the γ-Al2O3 support. After aging, ultrasonic washing with acidic water, decantation, drying and calcination, a SiO2 / γ-Al2O3 composite support is obtained. Step (3): Prepare a co-impregnation solution containing a complexing agent, a co-active metal salt and a main active metal salt, wherein the molar ratio of the complexing agent and the co-active metal salt in the co-impregnation solution is 1.2-2.2:1; Step (4): The co-impregnation liquid is impregnated onto the SiO2 / γ-Al2O3 composite support in equal volume, and then aged, dried and heated for sulfidation to obtain the selective hydrodesulfurization catalyst for catalytic cracking gasoline.

5. The preparation method according to claim 4, characterized in that, In step (1), the alumina raw powder includes boehmite powder, the extrusion aid includes one or a combination of guar gum powder, polyacrylamide, graphite and lubricating oil, and the adhesive solvent includes one or a combination of nitric acid, hydrochloric acid, acetic acid and citric acid.

6. The preparation method according to claim 4 or 5, characterized in that, Based on the total dry weight of the γ-Al2O3 support, the weight contents of the extrusion aid and the adhesive solvent are 4-10 wt% and 2-5 wt%, respectively.

7. The preparation method according to claim 4 or 5, characterized in that, The water absorption rate, strength, BET specific surface area, and pore volume of the γ-Al₂O₃ support are 90-150%, 8-20 N / mm², and 290-360 m³, respectively. 2 / g and 0.8-1.6 mL / g.

8. The preparation method according to claim 4, characterized in that, In step (2), the molar ratio of silicon dioxide to sodium oxide in the sodium silicate is 1.5-3.

0.

9. The preparation method according to claim 4, characterized in that, In step (3), the pH value of the co-impregnation solution is greater than 8.

1.

10. The preparation method according to claim 4 or 9, characterized in that, In step (3), the complexing agent includes one of ethylenediaminetetraacetic acid, aziridine triacetic acid, ethylenediamine, cyclohexanediaminetetraacetic acid, citric acid and ethylene glycol.

11. The preparation method according to claim 4 or 9, characterized in that, In step (3), the auxiliary active metal salt includes one or a combination of several of the auxiliary active metal nitrates, acetates and carbonates, and the main active metal salt includes one or a combination of several of the main active metal ammonium salts.

12. The preparation method according to claim 11, characterized in that, The ammonium salt of the main active metal is one or a combination of several of the thioammonium salts of the main active metal.

13. The preparation method according to claim 4, characterized in that, In step (4), the maximum sulfidation temperature is 280-360 ℃, the cumulative time for heating and sulfidation is 20-100 h, the sulfidation pressure is 1.0-3.0 MPa, and the volume hourly space velocity of the sulfidation oil is 1.0-3.0 h. -1 The hydrogen / oil volume ratio is 200:1-500:

1.

14. The preparation method according to claim 4 or 13, characterized in that, In step (4), the sulfiding reagent used in the sulfidation includes one or a combination of several of dimethyl disulfide, carbon disulfide, methanethiol, ethanethiol and thioether.

15. The application of the catalytic cracking gasoline selective hydrodesulfurization catalyst according to any one of claims 1-3 in FCC gasoline selective hydrodesulfurization.

Images