CN109370645B

CN109370645B - Catalytic cracking gasoline modification method

Info

Publication number: CN109370645B
Application number: CN201811346338.7A
Authority: CN
Inventors: 陈开龙; 庄琴珠
Original assignee: Xi'an Zhicaiquan Technology Transfer Center Co ltd
Current assignee: Xi'an Silk Road Zhixing Technology Service Co ltd
Priority date: 2018-11-13
Filing date: 2018-11-13
Publication date: 2021-05-04
Anticipated expiration: 2038-11-13
Also published as: CN109370645A

Abstract

The invention relates to a method for modifying catalytically cracked gasoline, the catalytically cracked gasoline firstly enters a pre-hydrogenation reactor, dialkene is removed under the action of a pre-hydrogenation catalyst, the effluent of the pre-hydrogenation reactor is cut into light and heavy fraction gasoline, and the light fraction gasoline is subjected to adsorption desulfurization under the action of an adsorption desulfurization catalyst; and (3) carrying out hydrodesulfurization reaction on the heavy gasoline fraction under the action of a hydrodesulfurization catalyst, and mixing the hydrodesulfurization reactant with the light gasoline fraction adsorption desulfurization reactant after the hydrodesulfurization reactant passes through an octane number recovery unit to obtain an ultra-low sulfur gasoline product.

Description

Catalytic cracking gasoline modification method

Technical Field

The invention relates to a catalytic cracking gasoline modification method.

Background

More than 70 percent of components in the domestic motor gasoline are catalytic cracking gasoline which has the characteristic of high sulfur and olefin content, so the key of upgrading the quality of the gasoline is to reduce the sulfur and olefin content in the catalytic gasoline; however, the olefin is a main contributor of the gasoline octane number, and the octane number of the gasoline is greatly lost by adopting the conventional hydrodesulfurization olefin-reducing technology. How to realize the multiple targets of desulfurization, olefin reduction and octane number maintenance of the catalytic gasoline becomes a great technical problem which needs to be solved urgently for upgrading the gasoline quality in China. The gasoline adsorption desulfurization technology becomes an important means for upgrading the quality of oil products, and the technology has the characteristics of high sulfur selectivity, small octane value loss and low investment and operation cost. Most of the existing adsorbents are desulfurization adsorbents prepared by using a silicon/aluminum material as a carrier and zinc oxide/active metal (such as nickel) as an active component, and the adsorption activity is reduced due to the formation of carbon deposit, zinc sulfide, zinc silicate and zinc aluminate in the reaction process, so that the regeneration reduction is needed to recover the activity of the adsorbent. The octane number loss is large due to the occurrence of olefin saturation.

The existing gasoline adsorption desulfurization method mainly comprises the following steps: (1) and (3) desulfurization treatment: mixing and contacting sulfur-containing hydrocarbon and hydrogen donor with an adsorbent to obtain desulfurized sulfur-containing hydrocarbon and a sulfur-carrying spent catalyst; (2) regeneration treatment: mixing and contacting the sulfur-carrying spent regenerant with oxygen-containing regeneration gas to obtain a regenerant; (3) reduction treatment: mixing and contacting the regenerant with a reducing gas to obtain a reducing regenerant which is recycled as an adsorbent; and refluxing the reduction regenerant obtained in the step (3) as an adsorbent to the step (1) to form an adsorbent circulating flow path. With continuous cyclic reduction and regeneration of the adsorbent, the adsorbent often has the problems of fragmentation (strength reduction) and activity reduction, and further the desulfurization efficiency is reduced.

CN103657709A discloses a reactive adsorption desulfurization-aromatization reaction process and a catalyst thereof. The catalyst not only has the function of reaction adsorption desulfurization when the catalytic cracking gasoline raw material is hydrotreated, but also can be coupled with the reaction adsorption desulfurization reaction and the aromatization reaction, so that the octane number of the product is not obviously reduced while deep desulfurization can be achieved when the developed process and the catalyst thereof modify the catalytic cracking gasoline raw material. The FCC gasoline with the sulfur content of 300-800ppm is used as the raw material, the S content of the product gasoline is less than 10ppm, the olefin content is reduced by 10 percent, the RON loss is less than 1, and the gasoline yield is more than 95 percent. CN101905161A relates to a catalytic gasoline adsorption desulfurization catalyst and preparation and application thereof; the weight percentage composition is as follows: 10-85% of active zinc oxide, 5-80% of white carbon black, 5-30% of alumina and 4-45% of nickel oxide; (1) carrying out pyrolysis on titanium tetrachloride at 1400 ℃ under hydrogen atmosphere to obtain fumed silica; (2) mixing active zinc oxide, fumed silica, alumina and nickel salt uniformly to form slurry; (3) spraying the mixture into balls or injecting oil into balls; (4) drying the particles in the step (3), wherein the drying temperature is 110-150 ℃; (5) roasting the microspheres obtained in the step (4) at the roasting temperature of 300-550 ℃; the prepared adsorption desulfurization catalyst has the advantages of good strength, high wear resistance, good desulfurization activity, small octane number loss and low operation cost, and is very suitable for a moving bed adsorption desulfurization process.

CN201511027275.5 discloses a method for hydro-upgrading poor catalytic gasoline, which comprises (1) mixing catalytic gasoline and hydrogen to enter a pre-hydrogenation reactor; (2) cutting the product obtained in the step (1) into light, medium and heavy gasoline components in a fractionating tower; (3) the light gasoline component coming out of the top of the fractionating tower is used as a modified gasoline blending component, and the middle gasoline component coming out of the lateral line and hydrogen are mixed, enter the first hydrodesulfurization reactor, react and then return to the fractionating tower; (4) mixing the heavy gasoline component and hydrogen from the bottom of the fractionating tower and allowing the mixture to enter a hydro-upgrading reactor for reaction; (5) the product of the step (4) enters a second hydrodesulfurization reactor for reaction; (6) and (5) cooling the product, then, introducing the product into a product separator for gas-liquid separation, recycling the hydrogen at the top, introducing the liquid phase at the bottom into a stabilizer for removing sulfur-containing gas, and mixing the liquid phase with light gasoline to obtain the modified gasoline product. The method of the invention greatly reduces the contents of olefin and sulfur, and simultaneously reduces the octane number loss in the catalytic gasoline hydro-upgrading. CN108018069A discloses a sulfur-containing hydrocarbon adsorption desulfurization method and device, the method comprises: and (3) desulfurization treatment: mixing and contacting sulfur-containing hydrocarbon and hydrogen donor with an adsorbent to obtain desulfurized sulfur-containing hydrocarbon and a sulfur-carrying spent catalyst; regeneration treatment: subjecting said sulfur-loaded spentThe agent is mixed and contacted with oxygen-containing regeneration gas to obtain a regeneration agent; reduction treatment: mixing and contacting the regenerant with a reducing gas to obtain a reducing regenerant which is recycled as an adsorbent; the adsorbent contains active metal monomers, and the reaction conditions of the reduction treatment comprise: taking a gas mixture containing non-hydrogen reducing gas as reducing gas, wherein the reducing temperature is 250-420 ℃, the reducing pressure is 0-3 MPa, and the volume space velocity of the reducing gas is 50-1000 h^-1The reduction time is 0.5-3 h. The method suppresses the formation of zinc silicate in the reduction reaction and desulfurization reaction, thereby improving the activity and strength of the regenerant. CN201310292325.7 discloses a method for adsorption desulfurization of catalytically cracked gasoline, which comprises the steps of using the catalytic gasoline subjected to selective hydrodesulfurization as a raw material (the sulfur content is less than 150 mu g/g), and performing cutting fractionation by a fractionating tower to obtain light gasoline and heavy gasoline. The light gasoline enters a fixed bed reactor to be subjected to non-hydrogenation physical adsorption desulfurization, the olefin content is not reduced by the physical adsorption desulfurization, and the octane number of the product is not lost; the heavy gasoline enters a fixed bed reactor to be subjected to hydro-adsorption desulfurization, and the reaction product is blended with the light gasoline physical adsorption desulfurization product to obtain a clean gasoline product which can meet the Euro V sulfur index requirement. The prior catalyst has the problems that the sulfur capacity is possibly low, zinc silicate and zinc aluminate are easily formed during regeneration and reduction, the adsorption activity is reduced, the octane number loss is large due to the occurrence of olefin saturation reaction, and the like. Therefore, it is necessary to develop a catalyst and a desulfurization process thereof, which have high breakthrough sulfur capacity, small octane number loss, good regeneration and reduction stability, and high adsorption desulfurization activity.

Disclosure of Invention

The invention provides a catalytic cracking gasoline modification method, wherein catalytic cracking gasoline is subjected to pre-hydrogenation treatment to remove dialkenes, then is cut into light and heavy fraction gasoline, the light fraction gasoline is subjected to adsorption desulfurization, the heavy fraction gasoline is subjected to hydrodesulfurization, and is blended with a light fraction gasoline adsorption desulfurization product after octane number recovery reaction to obtain the ultra-low sulfur gasoline.

A process for modifying the catalytically cracked gasoline includes such steps as loading the catalytically cracked gasoline in pre-hydrogenation reactor, removing diolefins under the action of pre-hydrogenation catalyst, cutting the effluent from pre-hydrogenation reactor to obtain light-heavy fraction gasoline, adsorptive desulfurizing the light fraction gasoline under the action of adsorptive desulfurizing catalyst, hydrodesulfurizing the heavy fraction gasoline, and regulating the product with the desulfurized light fraction gasoline to obtain the ultralow-sulfur gasoline. Meets the gasoline standards of the national six and the national five.

The pre-hydrogenation reaction conditions are as follows: the pressure is 1.0-5.0 MPa, the reaction temperature is 120-280 ℃, and the volume space velocity is 2.0-7.0 h^-1The volume ratio of the hydrogen to the oil is 10-240; the pre-hydrogenation catalyst carrier is macroporous alumina and silicon oxide, the loaded metal active component is selected from one or more of VIB and VIIIB, and the content of the metal active component oxide is 10-30% by weight of the catalyst of 100%; the metal active component is selected from one or more of molybdenum and/or tungsten in the VIB and cobalt, nickel, palladium and iron in the VIIIB.

An adsorptive desulfurization catalyst comprising, in weight percent: 25.0-50.0 wt% of zinc oxide, 0.5-25.0 wt% of nickel oxide, 2.0-55.0 wt% of ZSM-5 molecular sieve, 20.0-50.0 wt% of macroporous alumina and 1.0-25.0 wt% of cerium-zirconium solid solution; the reaction process conditions are as follows: the reaction temperature is 180 ℃ and 320 ℃, the reaction pressure is 0.5-2.5MPa, and the volume space velocity is 3-8h^-1Hydrogen-oil volume ratio is 1-50; and (3) carrying out hydrodesulfurization reaction on the heavy gasoline fraction, and blending the hydrodesulfurization reactant with the light fraction adsorption desulfurization reactant after the hydrodesulfurization reactant passes through an octane number recovery unit to obtain an ultra-low sulfur gasoline product. The adsorption desulfurization catalyst has high sulfur capacity, small octane value loss, good regeneration and reduction stability and high adsorption desulfurization activity.

The gasoline adsorption desulfurization method provided by the invention has the advantages that the fixed bed reactor can be a fixed bed adiabatic reactor or a fixed bed isothermal reactor, and is preferably the fixed bed adiabatic reactor; further preferably, the reaction process conditions are as follows: the reaction temperature is 180 ℃ and 300 ℃, the reaction pressure is 0.5-2.0MPa, and the volume space velocity is 5-8h^-1The volume ratio of hydrogen to oil is 1-40.

A preparation method of the adsorption desulfurization catalyst comprises the following steps: (1) dissolving nickel salt and zinc salt in nitric acid, and adding a pore-expanding agent to obtain acid liquor containing the nickel salt and the zinc salt; (2) preparing an acid solution containing a pore-expanding agent, adding a ZSM-5 molecular sieve, macroporous alumina and a cerium-zirconium solid solution into the acid solution containing the pore-expanding agent, and uniformly stirring to obtain a mixture slurry containing the ZSM-5 molecular sieve, the macroporous alumina and the cerium-zirconium solid solution, wherein the mass percentage of the pore-expanding agent in the acid solution containing nickel and zinc is more than 2 times that of the pore-expanding agent in the mixture slurry containing the ZSM-5 molecular sieve, the macroporous alumina and the cerium-zirconium solid solution calculated by oxides; adding an acid solution containing nickel salt and zinc salt into the slurry obtained in the step (2), and then adding an alkaline solution to perform a precipitation reaction; after the reaction is finished, the catalyst is obtained by filtering, washing, drying, forming and roasting.

In the preparation method of the catalyst, the addition amount of the pore-expanding agent in the step (1) accounts for 1-35% of the total mass of the nickel-zinc oxide.

The catalyst is further improved by preparing nickel salt and zinc salt to be dissolved in deionized water, impregnating the surface of the catalyst, drying and roasting to obtain the catalyst, and controlling the catalyst to comprise 25.0-50.0 wt% of zinc oxide and 0.5-25.0 wt% of nickel oxide. The mass percentage content of nickel oxide and zinc oxide on the surface of the catalyst is 0.1-2.0 times higher than that of the nickel oxide and the zinc oxide in the catalyst. Is favorable for improving the adsorption desulfurization activity and selectivity of the catalyst, and has high adsorption desulfurization rate. The desulfurization activity and selectivity of the catalyst after 8-10 times of regeneration are higher than those of the catalyst without surface modification by nickel oxide and zinc oxide.

The mass percentage content of nickel oxide and zinc oxide on the surface of the catalyst is 0.1-2.0 times higher than that of the nickel oxide and the zinc oxide in the catalyst.

Further preferably, the adsorption desulfurization catalyst comprises the following components in percentage by weight: 25.0-45.0 wt% of zinc oxide, 0.5-20.0 wt% of nickel oxide, 10.0-55.0 wt% of ZSM-5 molecular sieve, 20.0-40.0 wt% of macroporous alumina and 1.0-20.0 wt% of cerium-zirconium solid solution.

The alkaline solution comprises: one or more of sodium bicarbonate, ammonium bicarbonate, sodium carbonate, sodium hydroxide and ammonia water. The catalyst calcination temperature is 450-650 ℃.

Preparation of cerium-zirconium solid solution: weighing cerium nitrate and zirconium nitrate according to a stoichiometric ratio, placing the weighed cerium nitrate and zirconium nitrate into a beaker to prepare a mixed solution, adding a pore-expanding agent, dropwise adding ammonia water or a sodium carbonate solution into the mixed solution under the condition of continuously stirring, carrying out coprecipitation reaction, carrying out suction filtration, drying, roasting at 800-950 ℃ for 4-8 hours, and then crushing and grinding into powder. The addition amount of the pore-expanding agent accounts for 1-30% of the mass of the cerium-zirconium solid solution.

The pore-expanding agent is methyl cellulose, active carbon, polyvinyl alcohol, urea or sodium polyacrylate; polyacrylic acid; one or more of ammonium polyacrylate, preferably sodium polyacrylate.

The pore-expanding agent is added into the catalyst step by step, the catalyst has a mesoporous and macroporous structure, and the mass percentage of the pore-expanding agent in the acid solution containing nickel and zinc is more than 2 times of that of the pore-expanding agent in the mixture slurry containing the ZSM-5 molecular sieve, the macroporous alumina and the cerium-zirconium solid solution, so that the penetration sulfur capacity of the adsorption desulfurization catalyst is improved, the olefin saturation rate of the catalyst is low, and the octane number loss is low.

The adsorption desulfurization catalyst comprises: 25.0-50.0 wt% of zinc oxide, 0.5-25.0 wt% of nickel oxide, 2.0-55.0 wt% of ZSM-5 molecular sieve, 20.0-50.0 wt% of macroporous alumina and 1.0-25.0 wt% of cerium-zirconium solid solution, especially the introduction of cerium-zirconium solid solution (adding pore expanding agent in the mixing process of cerium-zirconium solid solution, ZSM-5 molecular sieve and macroporous alumina), effectively inhibits the generation of zinc aluminate/zinc silicate in the high-temperature reduction and regeneration process, and improves the reduction and regeneration stability of the adsorption desulfurization catalyst.

The method is suitable for removing sulfur in the catalytically cracked gasoline, and after the adsorption desulfurization catalyst is regenerated for 8-10 times, the sulfur capacity is reduced by 2-7%, and the catalyst has good stability.

The catalytic cracking gasoline modification method comprises the step of carrying out hydrodesulfurization reaction on heavy gasoline fraction, wherein a hydrodesulfurization catalyst contains 5-18 wt% of molybdenum oxide and 2-15 wt% of tungsten oxide, a carrier is macroporous alumina, and the desulfurization reaction conditions are as follows: the pressure is 1.0-3.0 MPa, the reaction temperature is 220-350 ℃, and the volume space velocity is 2.0-5.0 h^-1The volume ratio of hydrogen to oil is 200-500; the octane number recovery unit catalyst packageThe gasoline comprises nickel oxide, molybdenum oxide, aluminum oxide and ZSM-5, wherein the content of nickel oxide in the catalyst is 3-28 wt%, the content of molybdenum oxide in the catalyst is 1-15.0 wt%, the content of aluminum oxide in the catalyst is 20-55 wt%, the content of ZSM-5 in the catalyst is 25-65 wt%, and an octane number recovery unit reactant is blended with a light fraction adsorption desulfurization reactant to obtain an ultra-low sulfur gasoline product.

The present invention will be further illustrated by way of examples to illustrate the measurement method of the present invention, but the present invention is not limited to these examples.

Detailed Description

All starting materials for the present invention are commercially available.

Example 1

Preparation of adsorption desulfurization catalyst

Preparation of cerium-zirconium solid solution: weighing 38.8g of cerium nitrate and 33.9g of zirconium nitrate according to a stoichiometric ratio, placing the cerium nitrate and the zirconium nitrate into a beaker to prepare a mixed solution, adding 4g of sodium polyacrylate, dropwise adding ammonia water or a sodium carbonate solution into the mixed solution under the condition of continuous stirring for coprecipitation reaction, then carrying out suction filtration, drying, roasting at 840 ℃ for 6 hours, crushing and grinding into powder.

Preparation of the catalyst: (1) dissolving 67.4g of nickel nitrate and 136g of zinc nitrate in nitric acid, and adding 16g of sodium polyacrylate to obtain acid liquor containing nickel and zinc; (2) preparing an acid solution containing 5.5g of sodium polyacrylate, adding 23g of ZSM-5 molecular sieve, 17g of macroporous alumina and 5.7g of cerium-zirconium solid solution into the acid solution containing sodium polyacrylate, and uniformly stirring to obtain a mixture slurry containing the ZSM-5 molecular sieve, the macroporous alumina and the cerium-zirconium solid solution; and then adding acid liquor containing nickel salt and zinc salt into the mixture slurry, adding sodium carbonate and ammonia water solution, carrying out precipitation reaction, raising the temperature of the obtained reaction product to 90 ℃, aging for 5 hours, filtering, washing, drying, molding and roasting to obtain the catalyst. The composition of the catalyst is shown in table 1.

Example 2

The preparation of cerium zirconium solid solution was the same as in example 1, the catalyst was prepared in the same manner as in example 1, the pore-expanding agent in the acid solution containing nickel and zinc was contained in an amount of 3.2 times by mass as the metal oxide as compared with the pore-expanding agent in the slurry of the mixture containing ZSM-5 molecular sieve, macroporous alumina and cerium zirconium solid solution, and the composition of the catalyst is shown in table 1.

Example 3

The preparation of the cerium zirconium solid solution is the same as that of example 1, the preparation steps of the catalyst are the same as that of example 1, and the mass percentage of the pore-expanding agent in the acid solution containing nickel and zinc is 3.8 times higher than that of the pore-expanding agent in the mixture slurry containing the ZSM-5 molecular sieve, the macroporous alumina and the cerium zirconium solid solution calculated by oxides. After obtaining the catalyst, preparing nickel salt and zinc salt to be dissolved in deionized water, impregnating the surface of the catalyst, and then drying and roasting to obtain the catalyst with modified nickel and zinc surfaces. The mass percentage content of nickel oxide and zinc oxide on the surface of the catalyst is 0.9 times higher than that of the nickel oxide and the zinc oxide in the catalyst. The composition of the catalyst is shown in table 1.

Example 4

The preparation of the cerium zirconium solid solution is the same as that of example 3, the preparation steps of the catalyst are the same as that of example 3, and the mass percentage content of nickel oxide and zinc oxide on the surface of the catalyst is 1.5 times higher than that of the nickel oxide and zinc oxide in the catalyst. The composition of the catalyst is shown in table 1.

Table 1 example/comparative catalyst composition/wt%

Examples/comparative examples	Zinc oxide	Nickel oxide	ZSM-5	Macroporous aluminium oxide	Cerium zirconium solid solution
						Example 1	37	17.3	23	17	5.7
Example 2	46	16	20	13	5.0
						Example 3	29	20	33	13.5	4.5
Example 4	31	23	19	23.5	3.5

Comparative example 1

Preparation of the catalyst: (1) dissolving 67.4g of nickel nitrate and 136g of zinc nitrate in nitric acid, and adding 16g of sodium polyacrylate to obtain acid liquor containing nickel and zinc; (2) preparing an acid solution containing 5.5g of sodium polyacrylate, adding 23g of ZSM-5 molecular sieve and 17g of macroporous alumina into the acid solution containing sodium polyacrylate, and uniformly stirring to obtain a mixture slurry containing the ZSM-5 molecular sieve and the macroporous alumina; and adding an acid solution containing nickel salt and zinc salt into the mixture slurry, adding sodium carbonate and an ammonia water solution, carrying out precipitation reaction, raising the temperature of the obtained reaction product to 90 ℃, aging for 5 hours, filtering, washing, drying, molding and roasting to obtain the comparative catalyst 1.

Comparative example 2

Preparation of the catalyst: (1) dissolving 67.4g of nickel nitrate and 136g of zinc nitrate in nitric acid, and adding 21.5g of sodium polyacrylate to obtain acid liquor containing nickel and zinc; (2) adding 23g of ZSM-5 molecular sieve, 17g of macroporous alumina and 5.7g of cerium-zirconium solid solution into acid liquor containing nickel and zinc, uniformly stirring, adding sodium carbonate and ammonia water solution, carrying out precipitation reaction, raising the temperature of an obtained reaction product to 90 ℃, aging for 5 hours, filtering, washing, drying, forming and roasting to obtain the comparative catalyst 2.

The raw material is full-fraction FCC gasoline, and the olefin content in the gasoline raw material is 35.9 v%, the sulfur content is 183ppm and the octane number is 92.1.

The catalytically cracked gasoline enters a pre-hydrogenation reactor, and diene is removed under the action of a pre-hydrogenation catalyst, wherein the pre-hydrogenation reaction conditions are as follows: the pressure is 1.6MPa, the reaction temperature is 130 ℃, and the volume space velocity is 4.0h^-16 of hydrogen-oil volume ratio; the pre-hydrogenation catalyst carrier is macroporous alumina and silica (70% macroporous alumina-30% silica), the loaded metal active components of molybdenum, cobalt and nickel comprise 8.5 wt% of nickel oxide, 3.8 wt% of cobalt oxide and 11.4 wt% of molybdenum oxide, diene is removed by 100%, the effluent of the pre-hydrogenation reactor is cut into light fraction gasoline, the cutting temperature is 70 ℃, the light fraction gasoline is subjected to adsorption desulfurization under the action of an adsorption desulfurization catalyst, the heavy fraction gasoline is subjected to hydrodesulfurization, and is blended with the light fraction gasoline adsorption desulfurization product after octane number recovery reaction, so that the ultra-low sulfur gasoline is obtained. Satisfy the six and the national countriesFive gasoline standards.

The adsorption desulfurization of the light fraction gasoline is evaluated by adopting a 100ml adiabatic bed, the catalyst or a comparative catalyst is firstly reduced by hydrogen under the pressure of 1.8MPa, the temperature of the bed layer is firstly increased to 360 ℃ and stays for 5 hours, and then the temperature of the bed layer is increased to 460 ℃ and stays for 8 hours to finish the reduction. Cutting the prehydrogenation effluent of the catalytically cracked gasoline into light gasoline fraction and heavy gasoline fraction at 70 deg.c, adsorbing and desulfurizing the light gasoline fraction, and evaluating the technological conditions with the catalyst: the inlet temperature of the reactor is 280 ℃, the pressure is 1.1MPa, and the space velocity is 4.5h^-1The hydrogen/oil volume ratio was 25, and the evaluation results are shown in Table 2. The desulfurization rate of the catalyst is more than 98 percent, the octane number loss is less than 0.4, the penetrating sulfur capacity is higher than 28 percent, and the olefin saturation rate is less than 15 percent. The comparative catalyst 1 has large octane number loss, the comparative catalyst 2 has low desulfurization rate, large octane number loss and low penetrating sulfur capacity. Hydrodesulfurization of heavy gasoline fractions, the hydrodesulfurization catalyst comprising: 16 wt% of molybdenum oxide, 11 wt% of tungsten oxide, and macroporous alumina as a carrier, wherein a hydrodesulfurization reaction product enters an octane number recovery unit, and the catalyst comprises the following components: the content of nickel oxide is 21 wt%, the content of molybdenum oxide is 4 wt%, the content of aluminum oxide is 33 wt%, the content of ZSM-5 is 42 wt%, and the octane number recovery unit effluent is blended with the light fraction adsorption desulfurization reactant to obtain the ultra-low sulfur gasoline product with the sulfur content of less than 10ppm, which meets the national six standards.

TABLE 2 catalyst and comparative catalyst reaction results

	Desulfurization rate/%)	Loss of octane number	Penetration of sulfur capacity/%)
				Example 1	98.9	0.3	29
Example 2	98.6	0.2	28
				Example 3	99.8	0.2	30
Example 4	99.9	0.2	31
				Comparative example 1	98.2	2,4	28
Comparative example 2	92.8	1.3	19

After the adsorbed sulfur capacity reaches saturation, the catalyst or the comparative catalyst is regenerated, and the process conditions are as follows: heating to 260 ℃ at a heating rate of 35 ℃/h in a nitrogen atmosphere, and staying for 7 h; and then regenerating the catalyst, wherein the used regeneration gas is a mixed gas of oxygen and nitrogen, and the volume content of the oxygen accounts for 7 percent of the total gas. The regenerated catalysts 1 and 4,comparative catalysts 1 and 2, reactor inlet temperature 280 ℃, pressure 1.1MPa, space velocity 4.5h^-1The evaluation results are shown in Table 3, with a hydrogen-oil volume ratio of 25. The desulfurization effect of the catalyst can be basically recovered to the level of a fresh agent, the generation of zinc silicate and zinc aluminate in the high-temperature reduction and regeneration process is effectively inhibited, and the reduction and regeneration stability of the catalyst is improved. Compared with catalysts 1 and 2, the activity is reduced after regeneration, the octane number loss is large, and the penetration sulfur capacity is reduced. After 10 times of regeneration, the desulfurization rate of the catalyst in the embodiment 1 is 92.9 percent, and the sulfur capacity is reduced by 6 percent; in example 4, the desulfurization rate of the catalyst was 94.8%, and the sulfur capacity was decreased by 3%.

TABLE 3 catalyst and comparative catalyst reaction results

	Desulfurization rate/%)	Loss of octane number	Penetration of sulfur capacity/%)
				Example 1	98.8	0.3	29
Example 4	99.8	0.2	30
				Comparative example 1	94.1	2.6	25
Comparative example 2	90.1	1.6	17

Claims

1. A catalytic cracking gasoline modification method is characterized in that catalytic cracking gasoline firstly enters a pre-hydrogenation reactor, diene is removed under the action of a pre-hydrogenation catalyst, the effluent of the pre-hydrogenation reactor is cut into light and heavy fraction gasoline, and the cutting temperature of the light and heavy fraction gasoline is 70 ℃; the light fraction gasoline is adsorbed and desulfurized under the action of an adsorption desulfurization catalyst, and the adsorption desulfurization catalyst comprises the following components in percentage by weight: 25.0-50.0 wt% of zinc oxide, 0.5-25.0 wt% of nickel oxide, 2.0-55.0 wt% of ZSM-5 molecular sieve, 20.0-50.0 wt% of macroporous alumina and 1.0-25.0 wt% of cerium-zirconium solid solution; the mass percentage content of nickel oxide and zinc oxide on the surface of the catalyst is 0.1-2.0 times higher than that of the nickel oxide and the zinc oxide in the catalyst; the preparation method of the adsorption desulfurization catalyst comprises the following steps: (1) dissolving nickel salt and zinc salt in nitric acid, and adding a pore-expanding agent to obtain acid liquor containing the nickel salt and the zinc salt; (2) preparing an acid solution containing a pore-expanding agent, adding a ZSM-5 molecular sieve, macroporous alumina and a cerium-zirconium solid solution into the acid solution containing the pore-expanding agent, and uniformly stirring to obtain a mixture slurry containing the ZSM-5 molecular sieve, the macroporous alumina and the cerium-zirconium solid solution, wherein the mass percentage of the pore-expanding agent in the acid solution containing nickel and zinc is more than 2 times that of the pore-expanding agent in the mixture slurry containing the ZSM-5 molecular sieve, the macroporous alumina and the cerium-zirconium solid solution calculated by oxides; adding an acid solution containing nickel salt and zinc salt into the slurry obtained in the step (2), and then adding an alkaline solution to perform a precipitation reaction; after the reaction is finished, filtering, washing, drying, forming and roasting to obtain a catalyst; the catalyst was then further modified: nickel salt,Dissolving zinc salt in deionized water, soaking the surface of the catalyst, drying and roasting to obtain a finished product catalyst, wherein the catalyst comprises 25.0-50.0 wt% of zinc oxide and 0.5-25.0 wt% of nickel oxide; the reaction process conditions are as follows: the reaction temperature is 180 ℃ and 320 ℃, the reaction pressure is 0.5-2.5MPa, and the volume space velocity is 3-8h^-1Hydrogen-oil volume ratio is 1-50; and (3) carrying out hydrodesulfurization reaction on the heavy gasoline fraction under the action of a hydrodesulfurization catalyst, and blending the hydrodesulfurization reactant with the light gasoline fraction adsorption desulfurization reactant after the hydrodesulfurization reactant passes through an octane number recovery unit to obtain an ultra-low sulfur gasoline product.

2. The catalytic cracked gasoline upgrading method of claim 1, wherein the pre-hydrogenation catalyst comprises a carrier and an active component, the carrier is a macroporous alumina and silica composite carrier, the loaded active component is selected from one or more of group VIB and group VIIIB, and the content of the metal active component oxide is 10-30% by weight of the catalyst of 100%; the pre-hydrogenation reaction conditions are as follows: the pressure is 1.0-5.0 MPa, the reaction temperature is 120-280 ℃, and the volume space velocity is 2.0-7.0 h^-1And the volume ratio of the hydrogen to the oil is 10-240.

3. The catalytic gasoline upgrading method of claim 2, wherein the metal active component of the pre-hydrogenation catalyst is selected from one or more of molybdenum and/or tungsten in VIB, cobalt, nickel, palladium and iron in VIIIB.

4. The catalytic gasoline upgrading method of claim 1, wherein the adsorption desulfurization reaction process conditions are as follows: the reaction temperature is 180 ℃ and 320 ℃, the reaction pressure is 0.5-2.5MPa, and the volume space velocity is 3-8h^-1The volume ratio of hydrogen to oil is 1-50.

5. The catalytic gasoline upgrading method of claim 1, wherein the hydrodesulfurization catalyst is prepared by taking macroporous alumina as a carrier and loading active components of molybdenum and tungsten, and the active components comprise 5-18 wt% of molybdenum oxide and 2-15 wt% of tungsten oxide.

6. The catalytic gasoline upgrading method of claim 1, wherein the octane number recovery unit catalyst comprises nickel oxide, molybdenum oxide, aluminum oxide, and ZSM-5, and the catalyst contains 3-28 wt% of nickel oxide, 1-15.0 wt% of molybdenum oxide, 20-55 wt% of aluminum oxide, and 25-65 wt% of ZSM-5.