Catalytic gasoline hydrogenation method

Abstract

The invention discloses a catalytic gasoline hydrogenation method. The method comprises the following steps: (1) carrying out in-situ vulcanization treatment on a selective hydrodesulfurization catalyst; (2) after vulcanization is finished, introducing a certain amount of CO2 into the reactor; (3) keeping the atmosphere condition in the step (2), and introducing a catalytic gasoline raw material to react for a period of time; and (4) switching to a hydrogen atmosphere, adjusting the reaction condition to a catalytic gasoline selective hydrodesulfurization condition, and reacting to obtain a gasoline product. The method is used in a gasoline selective hydrodesulfurization process, and the hydrogenation selectivity of catalytic gasoline can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of clean oil refining, and in particular relates to a catalytic gasoline hydrogenation method. Background Art

[0002] The high sulfur content in finished motor gasoline will directly increase the SO in automobile exhaust. X The amount of emissions poisons the catalyst in the automobile exhaust converter and causes the CO and NO emissions from the automobile exhaust. X The increase of VOC and the reduction of sulfur content in finished gasoline can effectively reduce the emission of harmful substances in automobile exhaust. The traditional hydrodesulfurization (HDS) method can effectively remove organic sulfides, but the olefins with low isomerization degree in FCC gasoline are easily hydrogenated to form low-octane alkanes. During desulfurization, the octane number will inevitably drop sharply and the hydrogen consumption will also increase greatly.

[0003] CN101724442B discloses a method for reducing the octane number loss of gasoline deep hydrodesulfurization, the method first pre-sulfurizes the catalyst, and then performs hydrodesulfurization of inferior gasoline raw materials under gasoline hydrodesulfurization conditions, which is characterized in that the catalyst adopts low-temperature sulfurization operation to improve the catalyst selective hydrodesulfurization performance. CN103773439B discloses a start-up method of gasoline selective hydrodesulfurization process, the method reduces the reaction pressure while changing into feedstock oil after pre-sulfurizing the catalyst, keeps the hydrodesulfurization reaction running for a period of time under a relatively low pressure, and then increases the reaction pressure to normal production under normal conditions. The stabilization time of the selective hydrodesulfurization catalyst in the initial stage of the start-up can be shortened, and the selectivity of the catalyst hydrodesulfurization can be improved. Although the above methods can improve the gasoline selective hydrogenation performance of the catalyst, the selectivity still has a large room for improvement. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a catalytic gasoline hydrogenation method. The method of the present invention is used in the gasoline selective hydrogenation desulfurization process and can greatly improve the hydrogenation selectivity of catalytic gasoline.

[0005] The catalytic gasoline hydrogenation method of the present invention comprises the following contents: (1) subjecting a selective hydrodesulfurization catalyst to in-vehicle sulfurization treatment; (2) after the sulfurization is completed, introducing a certain amount of CO2 into the reactor; (3) maintaining the atmosphere conditions of step (2), introducing a catalytic gasoline raw material to react for a period of time; (4) switching to a hydrogen atmosphere, adjusting the reaction conditions to the catalytic gasoline selective hydrodesulfurization conditions for reaction, and obtaining a gasoline product.

[0006] In the method of the present invention, before the sulfidation treatment in step (1), the hydrodesulfurization reactor has completed conventional operations before sulfidation treatment, such as nitrogen gas-tightness, catalyst drying, hydrogen replacement, hydrogen gas-tightness and establishment of hydrogen circulation.

[0007] In the method of the present invention, the sulfurization treatment conditions in step (1) are as follows: the amount of the introduced sulfurizing agent is 90% to 150% of the theoretical sulfur requirement of the catalyst; the sulfurization process adopts programmed temperature rise, the temperature is raised to 200 to 230° C. and kept constant for 4 to 16 hours, and then kept constant at 260 to 290° C. for 4 to 16 hours; the sulfurizing agent is generally one or more of carbon disulfide, dimethyl disulfide, methyl sulfide, and n-butyl sulfide.

[0008] In the method of the present invention, the selective hydrogenation catalyst comprises a hydrogenation active component and a catalyst carrier, wherein the hydrogenation active component is a catalyst of at least one VIB group metal molybdenum and at least one VIII group metal cobalt, the weight content of molybdenum and cobalt metals as oxides is 4% to 40%, and the catalyst carrier is generally alumina, amorphous silicon aluminum, silicon oxide, titanium oxide, etc., and may contain other additives, such as P, Si, B, Ti, Zr, Ca, etc. Commercially available catalysts may be used, such as Axens RT-225, ExxonMobil HR-806 catalyst, Sinopec (Dalian) Petrochemical Co., Ltd. FGH-21, FGH-31 catalyst, etc. The pore volume of the catalyst is generally 0.45~1.30mL / g, and the specific surface area is 180~400m 2 / g.

[0009] In the method of the present invention, the amount of CO2 introduced in step (2) is ≮3000 μg / g, preferably ≮6000 μg / g, based on its concentration in hydrogen; In the method of the present invention, the amount of the catalytic gasoline feedstock introduced in step (3) is 2 to 10 h / min. -1 , preferably a volume space velocity of 4 to 8 h -1 , the reaction time is 48 to 600 hours, preferably 72 to 480 hours, and the reactor inlet temperature is inlet temperature ≮280°C, preferably ≮290°C; In the method of the present invention, the hydrodesulfurization conditions in step (4) are: reaction pressure 1.0-3.0 MPa, reaction temperature 250-300°C, volume space velocity 2.0-5.0 h -1 The volume ratio of hydrogen to oil is 200:1~500:1.

[0010] In the method of the present invention, after the sulfurization in step (2) is completed, the concentration of hydrogen sulfide in the hydrogen is generally replaced by hydrogen circulation ≯ 300 mg / m 3 , preferably ≯100mg / m 3 .

[0011] In the method of the present invention, the CO2 content in the hydrogen atmosphere of step (1) and step (4) is generally ≯20 μg / g, preferably ≯10 μg / g.

[0012] The present invention ingeniously utilizes the characteristics that the catalyst hydrodesulfurization reaction and the olefin hydrogenation saturation reaction have different active sites on the catalyst, and adsorbs a large amount of acidic CO2 molecules on the active sites of the catalyst hydrodesulfurization reaction, and introduces catalytic gasoline raw materials at a relatively high reaction temperature to accelerate the carbon deposition of the catalyst. Since a large amount of CO2 molecules are adsorbed on the active sites of the catalyst hydrodesulfurization reaction, more carbon deposition covers the active sites of the olefin hydrogenation saturation reaction, thereby reducing the activity of the olefin hydrogenation saturation reaction. Since the adsorption of CO2 molecules on the catalyst is recoverable, when the CO2 content in the hydrogen is restored to ≯20μg / g, the hydrodesulfurization reaction activity of the catalyst is restored, but at this time, the olefin hydrogenation saturation reaction activity of the catalyst has been suppressed, thereby greatly improving the selectivity of the catalytic gasoline hydrodesulfurization. This method only increases the CO2 content in the hydrogen that is easily controlled by the refinery during the catalyst activity stabilization stage after the start-up of sulfurization. After a short period of initial catalyst activity stabilization, the CO2 content in the hydrogen is re-controlled to a lower level, thereby achieving the purpose of improving the catalytic gasoline hydrogenation selectivity. The method is simple and effective. DETAILED DESCRIPTION

[0013] The following examples are used to specifically illustrate the effect of the specific method for improving the catalytic gasoline hydrogenation selectivity, but they do not constitute a limitation on the method of the present invention. The catalyst used is the FGH-31 catalyst of Sinopec (Dalian) Petrochemical Co., Ltd., and its properties are shown in Table 1. The comparative results of the catalytic gasoline hydrogenation selectivity of the examples and comparative examples are shown in Table 2.

[0014] Table 1 FGH-31 catalyst properties project index Analytical methods Active Metals <![CDATA[MoO3+CoO]]> Colorimetry shape Cylindrical Visual inspection Dimensions, mm Ф(1.3~1.6)×(3~8) Caliper Lateral compressive strength, N / cm ≮80 Progressive Strength Meter Bulk density, g / mL 0.70～0.80 Graduated cylinder method Pore ​​volume, mL / g ≮0.40 Low temperature nitrogen adsorption <![CDATA[Specific surface area, m 2 / g]]> ≮210 Low temperature nitrogen adsorption Example 1

[0015] (1) After the hydrogen circulation is established, the reactor inlet temperature is raised to 230°C and the temperature is kept constant for 8 hours. Then the reactor inlet temperature is raised to 280°C and the temperature is kept constant for 8 hours. The circulating hydrogen H2S concentration is 11000 mg / m 3 During the sulfidation process, the CO2 content in the hydrogen is controlled at 5μg / g; (2) After the sulfidation is completed, the concentration of hydrogen sulfide in the replaced hydrogen is 90mg / m 3 , CO2 content 6900μg / g, catalytic gasoline raw material, volume space velocity 5 h -1 , the reactor inlet temperature was controlled at 300°C; (3) 240 hours after the introduction of the catalytic gasoline feedstock, the CO2 content in the hydrogen was restored to 5μg / g, and the reactor inlet temperature dropped to the actual reaction temperature for normal production. Example 2

[0016] Same as Example 1, except that the CO2 content in step (2) is 4700 μg / g. Example 3

[0017] The same as Example 1, except that the catalytic gasoline feedstock is introduced into step (3) for 390 hours. Example 4

[0018] Same as Example 2, except that the catalytic gasoline feedstock is introduced in step (3) at a volumetric space velocity of 6 h -1 , the reactor inlet temperature was controlled at 290°C.

[0019] Comparative Example 1 Same as Example 1, except that the CO2 content in step (2) is 5 μg / g.

[0020] Comparative Example 2 The same as Example 1, except that the catalytic gasoline feedstock is introduced into step (3) for 24 hours.

[0021] Comparative Example 3 Same as Example 1, except that the reactor inlet temperature in step (3) is controlled at 250°C.

[0022] Comparative Example 4 Same as Example 1, except that the catalytic gasoline feedstock is introduced in step (3) at a volume space velocity of 1 h -1 .

[0023] Table 2 Comparison results of catalytic gasoline hydrogenation selectivity project raw material Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Octane number, RON 93.0 92.4 92.3 92.5 92.4 91.7 91.8 91.9 91.9 Sulfur content, μg / g 664 7.1 7.0 7.2 7.2 6.9 7.0 7.0 6.9 Multidimensional chromatographic composition Olefins, % 36.0 34.8 34.7 34.9 34.8 33.4 33.7 33.6 33.7 Note: Reaction conditions: P=1.6MPa H2 / Oil=300Nm 3 / m 3 ; Volume space velocity = 3.0h -1 ;Average reactor temperature 270°C; Table 2 lists the results of the comparison of the catalytic gasoline hydrogenation selectivity, which show that the desulfurization activity of the catalyst is equivalent, the olefin saturation rate is significantly reduced, and the octane number loss is small when the method for improving the catalytic gasoline hydrogenation selectivity of the present invention is adopted. The method for improving the catalytic gasoline hydrogenation selectivity of the present invention significantly improves the selective hydrogenation reaction performance of the catalyst.

Claims

1. A method for catalytic gasoline hydrogenation, characterized in that The method comprises the following contents: (1) subjecting a selective hydrodesulfurization catalyst to in-vehicle sulfurization treatment; (2) after the sulfurization is completed, introducing a certain amount of CO2 into the reactor; (3) maintaining the atmosphere conditions of step (2), introducing a catalytic gasoline raw material to react for a period of time; (4) switching to a hydrogen atmosphere, adjusting the reaction conditions to the catalytic gasoline selective hydrodesulfurization conditions for reaction, and obtaining a gasoline product.

2. The method according to claim 1, characterized in that: Before the sulfidation treatment in step (1), the hydrodesulfurization reactor has completed nitrogen airtightness, catalyst drying, hydrogen replacement, hydrogen airtightness and establishment of hydrogen circulation.

3. The method according to claim 1, characterized in that: The sulfurization treatment conditions in step (1) are as follows: the amount of the introduced sulfurizing agent is 90wt%~150wt% of the theoretical sulfur requirement of the catalyst; the sulfurization process adopts programmed temperature rise, the temperature is raised to 200~230℃ and kept constant for 4~16h, and then kept constant at 260~290℃ for 4~16h; the sulfurizing agent is one or more of carbon disulfide, dimethyl disulfide, methyl sulfide, and n-butyl sulfide.

4. The method according to claim 1, characterized in that: The selective hydrogenation catalyst comprises a hydrogenation active component and a catalyst carrier, wherein the hydrogenation active component is a catalyst of at least one VIB group metal molybdenum and at least one VIII group metal cobalt, the weight content of molybdenum and cobalt metal as oxides is 4% to 40%, the catalyst carrier is one or more of aluminum oxide, amorphous silicon aluminum, silicon oxide, and titanium oxide; the catalyst may contain one or more of P, Si, B, Ti, Zr, and Ca as additives; the pore volume of the catalyst is 0.45 to 1.30 mL / g, and the specific surface area is 180 to 400 m 2 / g.

5. The method according to claim 1, characterized in that: The amount of CO2 introduced in step (2) is ≮3000 μg / g, preferably ≮6000 μg / g, based on its concentration in hydrogen.

6. The method according to claim 1, characterized in that: The amount of catalytic gasoline raw material introduced in step (3) is 2 to 10 h / s. -1 , the reaction time is 48~600 hours, and the reactor inlet temperature is ≮280℃.

7. The method according to claim 1, characterized in that: The amount of catalytic gasoline raw material introduced in step (3) is 4-8 h / s. -1 , the reaction time is 72~480 hours, and the reactor inlet temperature is ≮290℃.

8. The method according to claim 1, characterized in that: The hydrodesulfurization conditions in step (4) are: reaction pressure 1.0-3.0 MPa, reaction temperature 250-300°C, volume space velocity 2.0-5.0 h -1 , hydrogen-oil volume ratio 200:1~500:

1.

9. The method according to claim 1, characterized in that: Step (2) After the sulfidation is completed, the hydrogen sulfide concentration in the hydrogen is replaced by hydrogen circulation ≯300mg / m 3 , preferably ≯100mg / m 3 .

10. The method according to claim 1, characterized in that: In the hydrogen atmosphere of step (1) and step (4), the CO2 content is ≯20 μg / g, preferably ≯10 μg / g.