Background
With the prominence of global pollution and the increasing awareness of environmental protection, china is greatly pushing the upgrade of finished oil quality in recent years, and the use of clean oil products is fully ensured under the guidance of policies and systems. Although new energy automobiles become an important research and development direction and popularization center of gravity in the automobile field, gasoline automobiles still play the most important role in traffic for a while, so that the requirement for clean gasoline is not reduced. The national VI gasoline standard, which was implemented since 2019, requires that the content of olefins and aromatics be continuously reduced while the sulfur content is controlled to be no more than 10 mug/g. And 70% of the commercial gasoline in China is processed by catalytic cracking gasoline.
In China, the sulfur content of the catalytic cracking gasoline is generally high and can reach 500-900ppm, and some of the catalytic cracking gasoline is even higher than 1300 ppm, and meanwhile, the content of olefin is high and is generally between 35-40% (v). Therefore, the catalytic cracking gasoline must pass through a certain hydrodesulfurization and olefin saturation path to become applicable finished oil. However, in the catalytic cracking gasoline hydrofining process, there is a prominent contradiction point, namely, the process of removing impurity elements (sulfur, nitrogen and oxygen) by hydrogenation and the olefin hydrogenation saturation reaction are contradicted, and under severe conditions, such as increasing the hydrogenation reaction temperature, the impurity elements are beneficial to removing, so that a cleaner product is obtained, but at the same time, the olefin hydrogenation saturation reaction is also affected by the temperature, and the reaction depth is increased, so that the octane number loss of the product is serious, thereby seriously affecting the added value of the product.
To minimize octane number loss during the hydrofining process of the catalytic gasoline. Researchers often control high-selectivity desulfurization by means of developing a high-selectivity hydrodesulfurization catalyst, improving a process flow, optimizing process conditions and the like, and simultaneously, maintain a certain olefin hydrogenation saturation rate. Specific foreign successful applications include Prime-G+ technology from French Petroleum Institute (IFP), SCANfining technology from Exxon Mobil, and catalytic distillation technology from CD Tech. The domestic hydrodesulfurization refining technology mainly comprises RSDS technology of China petrochemical institute of technology (RIPP), DSO technology of China petrochemical institute of technology (DSO), OCT-M technology of China petrochemical company (Fushun) petrochemical institute of technology (FRIPP), FRS technology and OTA technology; however, in the existing technology, in order to achieve a deeper desulfurization rate, the process conditions are relatively harsh, and the control of the olefin saturation rate still has problems, so that the problems of complex processing process flow and relatively high investment cost also exist.
Disclosure of Invention
Aiming at the problems existing in the conventional hydrodesulfurization process, the invention provides a catalytic cracking gasoline hydrogenation-active metal desulfurization combined process, which combines an active metal desulfurization technology with a hydrodesulfurization technology, wherein olefin partial saturation and deep desulfurization reaction are carried out in two steps, the combined process can optimize the operational range of hydrodesulfurization process conditions, avoid olefin transition saturation and effectively reduce the octane number loss of gasoline.
A combined process of hydrogenation and active metal desulfurization of catalytic cracking gasoline, the combined process comprises a hydrofining unit and an active metal desulfurization unit, the active metal desulfurization unit comprises a reaction unit and a solid-liquid separation unit, and the active metal desulfurization unit can be arranged before or after the hydrofining unit, preferably after the catalytic hydrofining unit.
When the active metal desulfurization unit is arranged in front of the hydrofining unit, the catalytic cracking gasoline reacts with active metal firstly, and solid-liquid separation is carried out after the reaction; the liquid phase enters a hydrofining unit for reaction.
When the active metal desulfurization unit is arranged behind the hydrofining unit, the catalytic cracking gasoline is subjected to hydrofining reaction firstly, and the liquid phase product obtained after the hydrofining reaction is directly reacted with the active metal or separated.
In the combined process, the catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content of the catalytic cracking gasoline is 200-850 ppm, preferably 320-650 ppm, and the olefin volume content is 30-45%, preferably 35-40%. The combined process can treat the catalytic cracking gasoline with high sulfur content and high olefin content, and alleviate the operation condition of a catalytic cracking device.
In the combined process, the volume content of olefin in the hydrofined material is higher than 20%, preferably 20-30%, and more preferably 23-28%.
In the combined process, the reaction temperature of the hydrofining unit is 200-280 ℃, the reaction pressure is 1-3MPa, and the volume space velocity is 1-4h -1 The volume ratio of the hydrogen to the oil is 100-300, and moderate saturation of olefin is realized by adjusting the process conditions.
In the combined process, the hydrofining catalyst adopted by the hydrofining unit adopts Al 2 O 3 As a carrier by MoO 3 CoO is an active component, and the weight of the catalyst is taken as the reference, and MoO in the catalyst 3 The mass fraction is 8-13%, and the mass fraction of CoO is 2-6%.
In the above combined process, the active metal comprises one or a mixture of several of Li, na and K, and the preferred active metal is Na.
In the combined process, the active metal desulfurization reaction can be performed in a CSTR reactor; before entering a CSTR reactor, the active metal can be heated to be in a liquid state and premixed with the catalytic cracking gasoline or with the hydrofined liquid phase product, and the full contact between the active metal and the liquid phase product can be promoted by means of ultrasonic dispersion, high-speed stirring, mixing shearing and the like in the premixing process. The volumetric space velocity of the active metal desulfurization unit corresponds to the ratio of the volumetric flow rate of the gasoline feed to the CSTR reactor volume.
In the combined process, when the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with active metal, the reaction temperature is 150-320 ℃, the reaction pressure is 2-6MPa, and the volume space velocity is 0.5-6 h -1 The volume ratio of hydrogen oil is 100-300, and the molar ratio of the active metal to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 1-6, preferably 2-4.
In the above combined process, when the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with the active metal, the introduced hydrogen contains hydrogen sulfide (based on the total volume of the hydrogen and the hydrogen sulfide) with a volume content of 5-20%, preferably 8-15%. The research result shows that the small amount of hydrogen sulfide contained in the hydrogen can promote the dispersion of alkali metal and shorten the residence time of the reaction.
In the combined process, the metal sulfide and unreacted active metal in the liquid phase material after the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with the active metal are converted into the active metal hydrosulfide through hydrogen sulfide or gas containing hydrogen sulfide. The catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with active metals, so that less alkali metal is needed, and alkali metal or alkali metal sulfide in the reacted materials is difficult to remove. In the method, hydrogen sulfide is introduced into the liquid phase material after the alkali metal reaction, so that metal sulfide and unreacted active metal are converted into active metal hydrosulfide, and then liquid-liquid separation is carried out, thereby improving the product separation efficiency. Research results show that the liquid active metal hydrosulfide is generated, is easier to gather and can be layered with diesel oil, and is easier to separate compared with the conventional process of generating solid sodium sulfide by desulfurizing metallic sodium, so that post-treatment processes such as water washing and the like are reduced.
The combined process of hydrogenation and active metal desulfurization of catalytically cracked gasoline can effectively reduce the operation conditions such as the temperature, the pressure and the like of hydrofining reaction, avoid the high-severity reaction conditions maintained by pursuing high desulfurization rate, and can deeply desulfurize materials under mild reaction conditions by the active metal desulfurization reaction, and simultaneously maintain certain olefin content and octane number. The method can process the full fraction catalytic cracking gasoline, omits a part of fractionating tower and device units such as mercaptan removal, simplifies the process flow and reduces the investment cost.
Detailed Description
The following examples and comparative examples are provided to further illustrate the production of high octane gasoline by a combination of catalytic cracking gasoline hydrogenation and active metal desulfurization processes, but are not intended to limit the process of the present invention.
The hydrofining catalyst adopted in the embodiment of the invention adopts Al 2 O 3 Takes Co-Mo as an active component and takes the weight of the catalyst as the reference, moO in the catalyst 3 The mass fraction is 10%, and the mass fraction of CoO is 4%. The active metal is Na. The active metal desulfurization reaction is carried out in a Continuous Stirred Tank (CSTR) reactor; before entering the CSTR reactor, the activity is increasedThe metal is heated to liquid state and premixed with the catalytic cracking gasoline or the hydrofined liquid phase product, and the premixing process is carried out under stirring.
Example 1
The active metal desulfurization unit is arranged before the hydrofining unit, the catalytic cracking gasoline reacts with active metal firstly, and liquid-liquid separation is carried out after the reaction; the liquid phase enters a hydrofining unit for reaction. The catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 220 ppm, and the volume content of olefin is 33%; when the catalytic cracking gasoline reacts with the active metal Na, the reaction temperature is 180 ℃, the reaction pressure is 2MPa, and the volume space velocity is 6 h -1 The volume ratio of hydrogen oil is 100, and the molar ratio of the active metal consumption to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 2; introducing hydrogen sulfide gas into the liquid phase material obtained after the reaction to convert metal sulfide and unreacted active metal in the material into active metal hydrosulfide, then performing liquid-liquid separation, and feeding the material after the active metal hydrosulfide is removed into a hydrofining unit, wherein the average reaction temperature of the hydrofining unit is 200 ℃, the reaction pressure is 1MPa, and the volume space velocity is 2.5h -1 The hydrogen oil volume ratio was 200. In the finally obtained gasoline product, the volume content of olefin is 24%, the sulfur content is 4ppm, the octane number of the gasoline is 90.6, and no Na residue exists in the gasoline.
Example 2
The active metal desulfurization unit is arranged before the hydrofining unit, the catalytic cracking gasoline reacts with active metal firstly, and solid-liquid separation is carried out after the reaction; the liquid phase enters a hydrofining unit for reaction. The catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 530 ppm, and the volume content of olefin is 38%; when the catalytic cracking gasoline reacts with the active metal Na, the reaction temperature is 240 ℃, the reaction pressure is 4MPa, and the volume space velocity is 3h -1 The volume ratio of hydrogen oil is 200, and the molar ratio of the active metal consumption to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 4; introducing into the liquid phase material obtained after the reactionHydrogen sulfide gas is added to convert metal sulfide and unreacted active metal in the material into active metal hydrosulfide, then liquid-liquid separation is carried out, the material after the active metal hydrosulfide is removed enters a hydrofining unit, the average reaction temperature of the hydrofining unit is 240 ℃, the reaction pressure is 2MPa, and the volume space velocity is 1.8h -1 The hydrogen oil volume ratio was 200. In the finally obtained gasoline product, the volume content of olefin is 27%, the sulfur content is 7 ppm, the octane number of the gasoline is 91.0, and no Na residue exists in the gasoline.
Example 3
The active metal desulfurization unit is arranged before the hydrofining unit, the catalytic cracking gasoline reacts with active metal firstly, and solid-liquid separation is carried out after the reaction; the liquid phase enters a hydrofining unit for reaction. The catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 784 ppm, and the volume content of olefin is 42%; when the catalytic cracking gasoline reacts with the active metal Na, the reaction temperature is 280 ℃, the reaction pressure is 6MPa, and the volume space velocity is 0.75 h -1 The volume ratio of hydrogen oil is 300, and the molar ratio of the active metal consumption to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 6; introducing hydrogen sulfide gas into the liquid phase material obtained after the reaction to convert metal sulfide and unreacted active metal in the material into active metal hydrosulfide, then performing liquid-liquid separation, and feeding the material after the active metal hydrosulfide is removed into a hydrofining unit, wherein the average reaction temperature of the hydrofining unit is 280 ℃, the reaction pressure is 3MPa, and the volume space velocity is 1 h -1 The hydrogen oil volume ratio was 300. In the finally obtained gasoline product, the volume content of olefin is 29%, the sulfur content is 9 ppm, the octane number of the gasoline is 92.2, and no Na residue exists in the gasoline.
Example 4
The catalytic cracking gasoline is subjected to hydrofining reaction firstly, and a liquid phase product obtained after separating materials subjected to hydrofining reaction reacts with active metal; the catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 245 ppm, and the volume content of olefin is 33%; the hydrogenation essenceThe average reaction temperature of the unit is 210 ℃, the reaction pressure is 1MPa, and the volume space velocity is 3h -1 The volume ratio of hydrogen to oil is 100; when the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with active metal Na, the reaction temperature is 200 ℃, the reaction pressure is 2MPa, and the volume space velocity is 4h -1 The volume ratio of hydrogen oil is 100, and the molar ratio of the active metal consumption to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 2; introducing hydrogen sulfide gas into the liquid phase material obtained after the reaction to convert metal sulfide and unreacted active metal in the material into active metal hydrosulfide, and then carrying out liquid-liquid separation; in the finally obtained gasoline product, the volume content of olefin is 24%, the sulfur content is 5ppm, the octane number of the gasoline is 90.5, and no Na residue exists in the gasoline.
Example 5
The catalytic cracking gasoline is subjected to hydrofining reaction firstly, and a liquid phase product obtained after separating materials subjected to hydrofining reaction reacts with active metal; the catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 476 ppm, and the volume content of olefin is 37%; the average reaction temperature of the hydrofining unit is 250 ℃, the reaction pressure is 2MPa, and the volume space velocity is 2 h -1 The volume ratio of hydrogen to oil is 200; when the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with active metal Na, the reaction temperature is 230 ℃, the reaction pressure is 4MPa, and the volume space velocity is 2 h -1 The volume ratio of hydrogen oil is 200, and the molar ratio of the active metal consumption to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 3; introducing hydrogen sulfide gas into the liquid phase material obtained after the reaction to convert metal sulfide and unreacted active metal in the material into active metal hydrosulfide, and then carrying out liquid-liquid separation; in the finally obtained gasoline product, the volume content of olefin is 25%, the sulfur content is 6 ppm, the octane number of the gasoline is 91.1, and no Na residue exists in the gasoline.
Example 6
The catalytic cracking gasoline is firstly subjected to hydrofining reaction, and liquid phase product is obtained after the material after the hydrofining reaction is separatedReacting with active metal; the catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 784 ppm, and the volume content of olefin is 42%; the average reaction temperature of the hydrofining unit is 270 ℃, the reaction pressure is 3MPa, and the volume space velocity is 1.5 h -1 Hydrogen oil volume ratio is 300; when the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with active metal Na, the reaction temperature is 300 ℃, the reaction pressure is 6MPa, and the volume space velocity is 0.67 and 0.67 h -1 The volume ratio of hydrogen oil is 300, and the molar ratio of the active metal consumption to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 5; introducing hydrogen sulfide gas into the liquid phase material obtained after the reaction to convert metal sulfide and unreacted active metal in the material into active metal hydrosulfide, and then carrying out liquid-liquid separation; in the finally obtained gasoline product, the volume content of olefin is 29%, the sulfur content is 4ppm, the octane number of the gasoline is 92.7, and no Na residue exists in the gasoline.
Example 7
The catalytic cracking gasoline is subjected to hydrofining reaction firstly, and a liquid phase product obtained after separating materials subjected to hydrofining reaction reacts with active metal; the catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 245 ppm, and the volume content of olefin is 33%; the average reaction temperature of the hydrofining unit is 210 ℃, the reaction pressure is 1MPa, and the volume space velocity is 3h -1 The volume ratio of hydrogen to oil is 100, and the volume content of hydrogen sulfide in the introduced hydrogen is 5%; when the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with active metal Na, the reaction temperature is 200 ℃, the reaction pressure is 2MPa, and the volume space velocity is 6 h -1 The volume ratio of hydrogen oil is 100, and the molar ratio of the active metal consumption to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 2; introducing hydrogen sulfide gas into the liquid phase material obtained after the reaction to convert metal sulfide and unreacted active metal in the material into active metal hydrosulfide, and then carrying out liquid-liquid separation; in the finally obtained gasoline product, the volume content of olefin is 24 percent, and the sulfur content is3 ppm, the octane number of the gasoline is 90.5, and no Na residue exists in the gasoline.
Example 8
The catalytic cracking gasoline is subjected to hydrofining reaction firstly, and a liquid phase product obtained after separating materials subjected to hydrofining reaction reacts with active metal; the catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 476 ppm, and the volume content of olefin is 37%; the average reaction temperature of the hydrofining unit is 250 ℃, the reaction pressure is 2MPa, and the volume space velocity is 2 h -1 The hydrogen oil volume ratio is 200, and the hydrogen sulfide volume content in the introduced hydrogen is 10%; when the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with active metal Na, the reaction temperature is 230 ℃, the reaction pressure is 4MPa, and the volume space velocity is 3h -1 The volume ratio of hydrogen oil is 200, and the molar ratio of the active metal consumption to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 3; introducing hydrogen sulfide gas into the liquid phase material obtained after the reaction to convert metal sulfide and unreacted active metal in the material into active metal hydrosulfide, and then carrying out liquid-liquid separation; in the finally obtained gasoline product, the volume content of olefin is 26%, the sulfur content is 4ppm, the octane number of the gasoline is 91.1, and no Na residue exists in the gasoline.
Example 9
The catalytic cracking gasoline is subjected to hydrofining reaction firstly, and a liquid phase product obtained after separating materials subjected to hydrofining reaction reacts with active metal; the catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 784 ppm, and the volume content of olefin is 42%; the average reaction temperature of the hydrofining unit is 270 ℃, the reaction pressure is 3MPa, and the volume space velocity is 1.5 h -1 The hydrogen oil volume ratio is 300, and the hydrogen sulfide volume content in the introduced hydrogen is 15%; when the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with active metal Na, the reaction temperature is 300 ℃, the reaction pressure is 6MPa, and the volume space velocity is 1.5 h -1 The volume ratio of hydrogen to oil is 300, and the consumption of active metal is equal to that of the raw material of the catalytic cracking gasolineSulfur (calculated as sulfur element) content molar ratio is 5; introducing hydrogen sulfide gas into the liquid phase material obtained after the reaction to convert metal sulfide and unreacted active metal in the material into active metal hydrosulfide, and then carrying out liquid-liquid separation; in the finally obtained gasoline product, the volume content of olefin is 29%, the sulfur content is 2 ppm, the octane number of the gasoline is 92.8, and no Na residue exists in the gasoline.
Example 10
The catalytic cracking gasoline is subjected to hydrofining reaction firstly, and a liquid phase product obtained after separating materials subjected to hydrofining reaction reacts with active metal; the catalytic cracking gasoline is high-sulfur gasoline obtained from a catalytic cracking device of a refinery, wherein the sulfur content in the catalytic cracking gasoline is 245 ppm, and the volume content of olefin is 33%; the average reaction temperature of the hydrofining unit is 230 ℃, the reaction pressure is 1.5 MPa, and the volume space velocity is 2.5h -1 The hydrogen oil volume ratio is 150, and the hydrogen sulfide volume content in the introduced hydrogen is 5%; when the catalytic cracking gasoline or the catalytic cracking gasoline after hydrofining reacts with active metal Na, the reaction temperature is 200 ℃, the reaction pressure is 2MPa, and the volume space velocity is 6 h -1 The volume ratio of hydrogen oil is 200, and the molar ratio of the active metal consumption to the sulfur (calculated by sulfur element) content in the catalytic cracking gasoline raw material is 3. And (5) carrying out solid-liquid separation by using a centrifugal method. In the finally obtained gasoline product, the volume content of olefin is 24%, the sulfur content is 3 ppm, the octane number of the gasoline is 90.3, and the Na content in the gasoline is 33.2 ppm.
Comparative example 1
When the catalytic cracking gasoline only carries out hydrofining reaction, the catalytic cracking gasoline is taken from high-sulfur gasoline of a catalytic cracking device of a refinery, the sulfur content in the catalytic cracking gasoline is 476 ppm, and the volume content of olefin is 37%; the average reaction temperature of the hydrofining unit is 220 ℃, the reaction pressure is 1MPa, and the volume space velocity is 1.5 h -1 The hydrogen oil volume ratio was 200. In the final gasoline product obtained, the olefin content was 29% by volume, the sulfur content was 87 ppm and the gasoline octane number was 90.4.
Comparative example 2
The catalytic cracking gasoline only carries out hydrofining reactionWhen the catalytic cracking gasoline is obtained from high-sulfur gasoline of a catalytic cracking device of a refinery, the sulfur content in the catalytic cracking gasoline is 476 ppm, and the volume content of olefin is 37%; the average reaction temperature of the hydrofining unit is 280 ℃, the reaction pressure is 2MPa, and the volume space velocity is 1.5 h -1 The hydrogen oil volume ratio was 300. In the final gasoline product obtained, the olefin content was 11% by volume, the sulfur content was 9 ppm and the gasoline octane number was 88.5.