Preparation method of gasoline selective hydrogenation catalyst

Abstract

The invention discloses a preparation method of a gasoline selective hydrogenation catalyst, which comprises the following steps: (1) impregnating a carrier with an impregnation liquid containing active metals Mo and Co, and drying to obtain a first-stage hydrodesulfurization catalyst; (2) impregnating the first-stage hydrodesulfurization catalyst obtained in the step (1) with an impregnation liquid containing alkali metal and / or alkaline earth metal, and drying to obtain a second-stage hydrodesulfurization catalyst; and (3) roasting the second-stage hydrodesulfurization catalyst obtained in the step (2) under a CO and / or CO2 atmosphere condition with a certain concentration to obtain a finished product catalyst. The catalyst prepared by the method disclosed by the invention well inhibits an olefin saturation active center, is smaller in octane number loss when being applied to a gasoline selective hydrogenation process, and has higher desulfurization activity and selectivity.

Description

Technical Field

[0001] This invention belongs to the field of petroleum hydrorefining, specifically relating to a method for preparing a gasoline selective hydrogenation catalyst. Background Technology

[0002] FCC gasoline and straight-run gasoline have different characteristics in terms of sulfur and olefin content. The sulfur content of gasoline is mainly related to the sulfur content of crude oil. Even if the sulfur content of straight-run gasoline is high, the olefin content is very low. FCC gasoline has high sulfur and olefin content. When treated with conventional HDS methods, straight-run gasoline does not have a significant loss of octane number. Although the traditional HDS method can effectively remove sulfur compounds from FCC gasoline, as the sulfur content of FCC gasoline decreases, olefins are easily hydrogenated to form alkanes with low octane numbers.

[0003] UOP combines Sulfur-X (extractive desulfurization) and ISAL to extract sulfides from middle fraction (MCN) and transfer them to HCN, then uses the ISAL catalyst for HDS treatment of HCN; ExxonMobil applies Exomer (fiber membrane desulfurization) technology to ScanFining technology to remove thiols from HCN hydrogenation products; IFP applies Prime-G... + Combined with BP's OATS (Olefins Alkylation of Thiophenic Sulfur), the OATS is first used to alkylate thiophene sulfur and olefins in the FCC gasoline light fraction (LCN) and transfer it to the heavy fraction (HCN), and then Prime-G is used... + The catalyst selectively performs HDS on HCN. The key to achieving the dual goals of deep desulfurization of FCC gasoline with minimal octane number loss, using different processes and catalysts both domestically and internationally, lies in solving the problem of HCN selective hydrogenation catalysts.

[0004] CN111111701A discloses a hydrodesulfurization catalyst and its preparation method. The preparation method of the hydrodesulfurization catalyst includes the following steps: (1) loading active metals Co and Mo onto a support, drying and calcining to obtain a semi-finished catalyst; (2) saturating the semi-finished catalyst with liquid olefins, and then heat-treating it; (3) subjecting the heat-treated catalyst to sulfidation treatment to obtain the catalyst. Although this catalyst, obtained through a special coking process, has longer active phase crystals and more stack layers after sulfidation, and this structure of the sulfidated catalyst has better hydrodesulfurization selectivity, the coking process inevitably damages the desulfurization activity to some extent and cannot effectively suppress the saturated active centers of olefins. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a gasoline selective hydrogenation catalyst. The catalyst prepared by this method effectively suppresses olefin saturated active centers, resulting in less octane number loss in gasoline selective hydrogenation processes and exhibiting higher desulfurization activity and selectivity.

[0006] The method for preparing the gasoline selective hydrogenation catalyst of the present invention includes the following steps:

[0007] (1) The support is impregnated with an impregnation solution containing active metals Mo and Co, and after drying, a hydrodesulfurization catalyst is obtained.

[0008] (2) Impregnate the first-stage hydrodesulfurization catalyst obtained in step (1) with an impregnation solution containing alkali metals and / or alkaline earth metals, and after drying, obtain the second-stage hydrodesulfurization catalyst.

[0009] (3) The two-stage hydrodesulfurization catalyst obtained in step (2) is calcined under a certain concentration of CO and / or CO2 atmosphere to obtain the finished catalyst.

[0010] In the method of the present invention, the impregnation solution of the active metals Mo and Co in step (1) is an aqueous solution of Mo and Co, an acid solution, or an ammonia solution. The precursor salt of Mo is generally one or more of molybdenum oxide, ammonium heptamolybdate, and ammonium tetramolybdate. The precursor salt of Co is generally one or more of basic cobalt carbonate, cobalt nitrate, and cobalt acetate.

[0011] In the method of the present invention, the drying conditions in step (1) are: drying temperature 50-150℃, drying time 3-24 hours.

[0012] In the method of the present invention, the immersion solution of alkali metal and / or alkaline earth metal in step (2) is a soluble aqueous solution of alkali metal and / or alkaline earth metal well known in the art. The alkali metal is preferably sodium and / or potassium, and the alkaline earth metal is preferably calcium and / or magnesium. The soluble alkali metal and / or alkaline earth metal salt is generally one or more of potassium nitrate, potassium chloride, potassium dihydrogen phosphate, sodium chloride, sodium carbonate, sodium bicarbonate, magnesium nitrate, calcium nitrate, magnesium chlorate, calcium chlorate, magnesium perchlorate, calcium perchlorate, magnesium acetate, calcium acetate, magnesium chloride, or calcium chloride.

[0013] In the method of the present invention, the drying conditions in step (2) are: drying temperature 50-150℃, drying time 3-24 hours.

[0014] In the method of the present invention, the concentration of CO and / or CO2 in step (3) is ≥3000μg / g, preferably ≥6000μg / g.

[0015] In the method of the present invention, the calcination conditions in step (3) are: calcination temperature of 300-650℃, calcination time of 3-4 hours, and programmed heating with a heating rate of 2-5℃ / minute.

[0016] In the method of this invention, the finished catalyst needs to undergo sulfidation treatment before use. This sulfidation process can be performed internally or externally. The amount of sulfiding agent introduced is 90%–150% of the theoretical sulfur requirement of the catalyst. The sulfidation process uses programmed temperature rise, maintaining a temperature of 200–350°C for 1–16 hours. The sulfiding agent is generally one or more of carbon disulfide, dimethyl disulfide, methyl sulfide, and n-butyl sulfide.

[0017] The present invention also provides a gasoline selective hydrogenation catalyst, which comprises a hydrogenation active component and alumina. Based on the total weight of the catalyst, MoO3 is 2.0% to 30.0%, preferably 2.0% to 25.0%, CoO is 0.1% to 7.0%, preferably 0.1% to 6.0%, alkali metal and / or alkaline earth metal content is 1.5% to 10.0%, preferably 2.3% to 8.0%, and alumina content is the balance.

[0018] The hydrogenation catalyst of this invention has a pore volume of 0.3–1.3 mL / g and a specific surface area of ​​150–400 m². 2 / g, strength 100~250N / cm, bulk density 0.65~0.90g / mL.

[0019] The selective hydrogenation catalyst for gasoline of the present invention may further include additives such as Ti, Zr, V, Cu, Zn, and Si, with the additive content being 0.5% to 7% by weight of the total catalyst, and the sum of the contents of all catalyst components being 100%.

[0020] The hydrogenation catalyst of the present invention is suitable for use in selective hydrodesulfurization of gasoline.

[0021] The inventors first impregnated Mo and Co, dried them without calcination, and then dried them with alkali metals and / or alkaline earth metals. The dried sample, containing active metals Mo and Co and alkali metals and / or alkaline earth metals, was then calcined under a certain concentration of CO and / or CO2 atmosphere. During calcination, as the calcination temperature gradually increases, the active metals Mo and Co can gradually transform into oxidized states and form desulfurization and hydrogenation active sites. Because CO and / or CO2 are more readily adsorbed onto the active sites of the hydrodesulfurization reaction, they can better protect these sites during the gradual transformation of Mo and Co into oxidized states. Simultaneously, the alkali metals and / or alkaline earth metals also gradually transform into oxidized states. Alkali metals and / or alkaline earth metals are catalyst poisons and can inhibit catalyst activity. This inhibitory effect is observed in the CO atmosphere. With the protective effect of CO and / or CO2 molecules on the active sites of the hydrodesulfurization reaction, the active sites of the olefin hydrogenation saturation reaction are more easily affected during the gradual transformation of the active center, thus inhibiting the olefin saturation activity to a greater extent. The entire process is completed during the gradual formation of the active phase. CO and / or CO2 molecules provide better protection for the active sites of the hydrodesulfurization reaction, while alkali metals and / or alkaline earth metals provide better inhibition of the active sites of the olefin hydrogenation saturation reaction. The finished catalyst undergoes sulfidation treatment before use, which enhances the hydrodesulfurization activity and selectivity of the catalyst, achieving the goal of selective hydrodesulfurization of gasoline. This invention uses only one calcination process for the two-stage impregnation to obtain the finished catalyst, simplifying the process and reducing energy consumption. Detailed Implementation

[0022] In this invention, the specific surface area and pore volume were determined using a cryogenic liquid nitrogen adsorption method. In this invention, % represents mass percentage. The catalyst composition was determined using a titration method.

[0023] The specific preparation process of the catalyst of this invention is as follows:

[0024] The support is impregnated with an impregnation solution containing active metals Mo and Co, and dried at 50–150 °C for 3–24 hours to obtain a first-stage hydrodesulfurization catalyst. The first-stage hydrodesulfurization catalyst is impregnated with an impregnation solution containing alkali metals and / or alkaline earth metals, and dried at 50–150 °C for 3–24 hours to obtain a second-stage hydrodesulfurization catalyst. Under an atmosphere of ≥3000 μg / g CO and / or CO2, the second-stage hydrodesulfurization catalyst is calcined at 300–650 °C for 3–4 hours at a programmed heating rate of 2–5 °C / min to obtain the finished catalyst.

[0025] In the above preparation method, the concentration of the impregnation solution is determined by the water absorption rate and the required catalyst composition (content).

[0026] The catalysts used in this invention are described in detail below using examples.

[0027] Example 1

[0028] 200g of alumina support was impregnated with a molybdenum and cobalt ammonia solution containing 11.2g of cobalt carbonate and 22.5g of ammonium molybdate in 190mL of solution, and dried at 110℃ for 5 hours to obtain a first-stage hydrodesulfurization catalyst A. The first-stage hydrodesulfurization catalyst A was impregnated with an aqueous solution containing 16.6g of potassium dihydrogen phosphate in 120mL of solution, and dried at 110℃ for 5 hours to obtain a second-stage hydrodesulfurization catalyst A. Under a CO2 atmosphere of 5900μg / g, the second-stage hydrodesulfurization catalyst A was calcined at 550℃ for 3 hours at a programmed heating rate of 3℃ / min to obtain the finished catalyst A.

[0029] Example 2

[0030] 200g of alumina support was impregnated with 190mL of a molybdenum and cobalt ammonia solution containing 5.2g of cobalt carbonate and 11.4g of ammonium molybdate, and dried at 110℃ for 5 hours to obtain a first-stage hydrodesulfurization catalyst B. The first-stage hydrodesulfurization catalyst B was impregnated with 130mL of an aqueous solution containing 16.6g of potassium dihydrogen phosphate, and dried at 110℃ for 5 hours to obtain a second-stage hydrodesulfurization catalyst B. Under a CO atmosphere of 4700μg / g, the second-stage hydrodesulfurization catalyst B was calcined at 500℃ for 3 hours at a programmed heating rate of 3℃ / min to obtain the finished catalyst B.

[0031] Example 3

[0032] 200g of alumina support was impregnated with 190mL of a molybdenum and cobalt ammonia solution containing 14.3g of cobalt carbonate and 36.3g of ammonium molybdate, and dried at 110℃ for 5 hours to obtain a first-stage hydrodesulfurization catalyst C. The first-stage hydrodesulfurization catalyst C was impregnated with 110mL of an aqueous solution containing 17.6g of potassium dihydrogen phosphate, and dried at 110℃ for 5 hours to obtain a second-stage hydrodesulfurization catalyst C. The second-stage hydrodesulfurization catalyst C was calcined at 500℃ for 3 hours under an atmosphere of 3000μg / g CO and 3800μg / g CO2 at a programmed heating rate of 3℃ / min to obtain the finished catalyst C.

[0033] Example 4

[0034] 200g of alumina support was impregnated with a molybdenum and cobalt amine solution containing 190mL of cobalt carbonate and 47.3g of ammonium molybdate, and dried at 110℃ for 5 hours to obtain a first-stage hydrodesulfurization catalyst D. The first-stage hydrodesulfurization catalyst D was impregnated with an aqueous solution containing 13.7g of potassium nitrate in 110mL of water, and dried at 110℃ for 5 hours to obtain a second-stage hydrodesulfurization catalyst D. Under a CO2 atmosphere of 7500μg / g, the second-stage hydrodesulfurization catalyst D was calcined at 500℃ for 3 hours at a programmed heating rate of 3℃ / min to obtain the finished catalyst D.

[0035] Comparative Example 1

[0036] The preparation method is the same as in Example 1, except that the two-stage hydrodesulfurization catalyst E is not calcined at 550°C for 3 hours under a CO2 atmosphere, with the temperature increased at a rate of 3°C / min, to obtain the finished catalyst E.

[0037] Comparative Example 2

[0038] The preparation method is the same as in Example 2, except that 200g of alumina support is impregnated with 190mL of a molybdenum and cobalt ammonia solution containing 5.2g of cobalt carbonate and 11.4g of ammonium molybdate, dried at 110℃ for 5 hours, and then calcined at 500℃ for 3 hours at a programmed heating rate of 3℃ / min to obtain a first-stage hydrodesulfurization catalyst F.

[0039] Comparative Example 3

[0040] The preparation method is the same as in Example 3, except that instead of impregnating a section of hydrodesulfurization catalyst G with 110 mL of aqueous solution containing 17.6 g of potassium dihydrogen phosphate, the section of hydrodesulfurization catalyst G is directly calcined at 500 °C for 3 hours under an atmosphere of 3000 μg / g CO and 3800 μg / g CO2 at a programmed heating rate of 3 °C / min to obtain the finished catalyst G.

[0041] Comparative Example 4

[0042] The preparation process is the same as in Example 4, except that the CO2 content is always kept at 700 μg / g in the atmosphere, and the two-stage hydrodesulfurization catalyst H is heated to 500°C at a programmed heating rate of 3°C / min for 3 hours to obtain the finished catalyst H.

[0043] Example 5

[0044] In a 200 mL fixed-bed small-scale hydrogenation unit, catalysts A, B, C, D, E, F, G, and H (catalyst properties are shown in Table 1) were used respectively. After sulfidation, the reaction was carried out at a reaction pressure of 1.6 MPa and a liquid hourly space velocity of 3.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 300 Nm. 3 / m 3Selective hydrodesulfurization was carried out on a feedstock with a sulfur content of 664 μg / g and a RON of 93.0 at reaction temperatures of 270, 310, 260, 250℃ and 270, 310, 260, 250℃, respectively. The evaluation results of each catalyst after 600 hours of operation are shown in Table 2.

[0045] Table 1. Main properties of the catalyst

[0046] Catalyst number A B C D E F G H <![CDATA[MoO3,wt%]]> 8.1 4.2 11.9 15.8 8.1 4.2 11.9 15.8 CoO, wt% 2.5 1.4 3.2 4.0 2.5 1.4 3.2 4.0 <![CDATA[K2O,wt%]]> 2.6 2.7 2.5 2.7 2.6 2.7 - 2.7 Pore ​​volume, mL / g 0.43 0.48 0.47 0.42 0.41 0.46 0.49 0.43 <![CDATA[Specific surface area, m 2 / g]]> 245 249 224 208 235 241 243 226

[0047] Table 2 Catalyst Activity and Selectivity

[0048] catalyst A B C D E F G H Reaction temperature, °C 270 310 260 250 270 310 260 250 Sulfur, μg / g 7.3 7.1 7.2 7.0 7.1 7.2 6.9 7.2 RON 92.1 92.0 92.0 92.1 91.2 91.5 90.8 91.4 RON loss 0.9 1.0 1.0 0.9 1.8 1.5 2.2 1.6

[0049] Reaction conditions: P = 1.6 MPa; LHSV = 3.0 h⁻¹ -1 H2 / Oil = 300 Nm 3 / m 3 The results in Table 2 show that the catalyst of the present invention has better hydrodesulfurization selectivity and less octane number loss under the same desulfurization rate.

Claims

1. A method for preparing a gasoline selective hydrogenation catalyst, characterized in that... The process includes the following: (1) impregnating the carrier with an impregnation solution containing active metals Mo and Co, and then drying it to obtain a first-stage hydrodesulfurization catalyst; (2) impregnating the first-stage hydrodesulfurization catalyst obtained in step (1) with an impregnation solution containing alkali metals and / or alkaline earth metals, and then drying it to obtain a second-stage hydrodesulfurization catalyst; (3) calcining the second-stage hydrodesulfurization catalyst obtained in step (2) under a certain concentration of CO and / or CO2 atmosphere to obtain the finished catalyst.

2. The method according to claim 1, characterized in that: The impregnation solution of the active metals Mo and Co in step (1) is an aqueous solution of Mo and Co, an acid solution, or an ammonia solution; the precursor salt of Mo is one or more of molybdenum oxide, ammonium heptamolybdate, and ammonium tetramolybdate, and the precursor salt of Co is generally one or more of basic cobalt carbonate, cobalt nitrate, and cobalt acetate.

3. The method according to claim 1, characterized in that: The drying conditions described in step (1) are: drying temperature 50~150℃, drying time 3~24 hours.

4. The method according to claim 1, characterized in that: The impregnation solution of the alkali metal and / or alkaline earth metal in step (2) is a soluble aqueous solution of the alkali metal and / or alkaline earth metal, wherein the alkali metal is preferably sodium and / or potassium, and the alkaline earth metal is preferably calcium and / or magnesium; the soluble alkali metal and / or alkaline earth metal salt is one or more of potassium nitrate, potassium chloride, potassium dihydrogen phosphate, sodium chloride, sodium carbonate, sodium bicarbonate, magnesium nitrate, calcium nitrate, magnesium chlorate, calcium chlorate, magnesium perchlorate, calcium perchlorate, magnesium acetate, calcium acetate, magnesium chloride, or calcium chloride.

5. The method according to claim 1, characterized in that: The drying conditions for step (2) are: drying temperature 50~150℃, drying time 3~24 hours.

6. The method according to claim 1, characterized in that: The concentration of CO and / or CO2 in step (3) is ≥3000 μg / g, preferably ≥6000 μg / g.

7. The method according to claim 1, characterized in that: The calcination conditions described in step (3) are: calcination temperature of 300~650℃, calcination time of 3~4 hours, and programmed heating with a heating rate of 2~5℃ / minute.

8. The method according to claim 1, characterized in that: Before use, the finished catalyst needs to be sulfided. The sulfidation process can be carried out inside or outside the equipment. The amount of sulfiding agent introduced is 90% to 150% of the theoretical sulfur required by the catalyst. The sulfidation process adopts programmed temperature rise, and the temperature is kept at 200 to 350℃ for 1 to 16 hours. The sulfiding agent is one or more of carbon disulfide, dimethyl disulfide, methyl sulfide, and n-butyl sulfide.

9. A gasoline selective hydrogenation catalyst prepared by the method according to any one of claims 1 to 8, characterized in that: The catalyst comprises a hydrogenation active component and alumina. Based on the total weight of the catalyst, MoO3 is 2.0% to 30.0%, preferably 2.0% to 25.0%, CoO is 0.1% to 7.0%, preferably 0.1% to 6.0%, alkali metal and / or alkaline earth metal content is 1.5% to 10.0%, preferably 2.3% to 8.0%, and alumina content is the balance.

10. The catalyst according to claim 9, characterized in that: The catalyst has a pore volume of 0.3~1.3 mL / g and a specific surface area of ​​150~400 m². 2 / g, strength 100~250N / cm, bulk density 0.65~0.90g / mL.