Adsorbent for desulfurization of gasoline and method for desulfurization of gasoline

Abstract

The present invention provides an adsorbent and a method for desulfurization of gasoline. The adsorbent is obtained by loading active metal component on a composite carrier comprising zeolite and active carbon subjected to alkali treatment respectively, the active metal is selected from one or more elements of IA, IIA, VIII, IB, IIB and VIB groups in the periodic table. This method uses the adsorbent to conduct gasoline adsorption desulfurization, which especially cuts the gasoline into a light and a heavy gasoline fraction firstly, then the light fraction is subjected to adsorption desulfurization using the adsorbent, and the heavy fraction is subjected to selective hydrodesulfurization, a cutting temperature of the light and the heavy gasoline fraction is 70-110 C. The adsorbent has a large sulfur adsorption, a long service life, and simply to be regenerated; the method can realize deep desulfurization of gasoline, and has a less octane number loss.

Claims

1. An adsorbent for desulfurization of gasoline, wherein the absorbent is obtained by loading an active metal component on a composite carrier, the composite carrier comprises a zeolite and an active carbon, wherein the zeolite and the active carbon are treated with alkali respectively before they are mixed to prepare the composite carrier, wherein the zeolite and the active carbon being treated with alkali respectively comprises treating the zeolite and the active carbon, respectively, as follows: blending at a mass ratio of the zeolite or the active carbon to alkali to water: (0.1-2):(0.05-2):(4-15), and stirring the mixture for 0.1-24 h at a temperature of 0-120 C., and then drying, the active metal is selected from one or more of elements of IA, VIII, IB, IIB and VIB groups in the periodic table.

2. The adsorbent for desulfurization of gasoline according to claim 1, wherein a mass ratio of the zeolite to the active carbon in the composite carrier is (20-80): (80-20).

3. The adsorbent for desulfurization of gasoline according to claim 1, wherein the zeolite is an X type, a Y type or a ZSM-5 type zeolite.

4. The adsorbent for desulfurization of gasoline according to claim 1, wherein the active metal is selected from at least two of Ni, Fe, Ag, Co, Mo, Zn and K.

5. The adsorbent for desulfurization of gasoline according to claim 1, wherein the active metal has a loading of 2-30% on the composite carrier.

6. A method for preparing the adsorbent for desulfurization of gasoline according to claim 1, comprising steps of: blending the zeolite and the active carbon subjected to alkali treatment, respectively, in proportion to prepare the composite carrier; impregnating the composite carrier with a soluble salt solution of the active metal, drying the composite carrier impregnated with soluble salt solution and, then, calcinating to obtain the adsorbent for desulfurization of gasoline.

7. The method according to claim 6, wherein the alkali treatment comprises treating the zeolite and the active carbon, respectively, as follows: blending at a mass ratio of the zeolite or the active carbon to alkali to water: (0.1-2):(0.05-2):(4-15), and stirring the mixture for 0.1-24 h at a temperature of 0-120 C., and then drying, the above alkali treatment is conducted at least one time.

8. The method according to claim 6, wherein calcinating the composite carrier impregnated with the soluble salt solution after being dried is conducted for 4-6 h at a temperature of between 450-640 C.

9. The method according to claim 6, wherein calcinating the composite carrier comprises cooling the composite carrier impregnated with the soluble salt solution after being dried down to a room temperature, elevating the temperature to 400 C. at a speed of 6 C./min firstly, and then elevating the temperature to 450-640 C. at a speed of 3 C./min.

10. A method for desulfurization of gasoline, comprising: conducting adsorption desulfurization to gasoline using the adsorbent according to claim 1.

11. The method for desulfurization of gasoline according to claim 10, comprising firstly cutting the gasoline into a light gasoline fraction and a heavy gasoline fraction, and then conducting adsorption desulfurization to the light gasoline fraction using the adsorbent to obtain a desulfurized light gasoline fraction, and conducting selective hydrodesulfurization to the heavy gasoline fraction to obtain a desulfurized heavy gasoline fraction; wherein, a cutting temperature of the light gasoline fraction and the heavy gasoline fraction is 70-110 C.

12. The method for desulfurization of gasoline according to claim 10, wherein the adsorption desulfurization is conducted using a fixed-bed at atmospheric pressure, and a temperature of the adsorption desulfurization is controlled between 20-100 C., a flow rate of the gasoline is 0.3-1 mL/min.

13. The method for desulfurization of gasoline according to claim 11, further comprising: washing the adsorbent which is subjected to the adsorption desulfurization with steam to collect a sulfur-rich component; mixing the sulfur-rich component with the heavy gasoline fraction to conduct the selective hydrodesulfurization.

14. The method for desulfurization of gasoline according to claim 11, further comprising: washing the desulfurization adsorbent which is subjected to the adsorption desulfurization with steam, drying the washed adsorbent with nitrogen at a temperature of 200-400 C., and cooling the dried adsorbent with nitrogen to realize regeneration of the adsorbent.

15. The method for desulfurization of gasoline according to claim 11, wherein the heavy gasoline fraction and hydrogen are subjected to the selective hydrodesulfurization in the presence of a selective hydrodesulfurization catalyst to obtain the desulfurized heavy gasoline fraction, wherein, a temperature of the selective hydrodesulfurization is 200-300 C., a pressure is 1.5-2.5 MPa, a liquid hourly space velocity is 1-5 h-1, a volume ratio of hydrogen to oil is 400-600.

16. The method for desulfurization of gasoline according to claim 15, wherein the hydrodesulfurization catalyst is obtained by loading a carrier with an active metal component, wherein the carrier is a zeolite or a metal oxide, and the active metal comprises Co and Mo.

17. The method for desulfurization of gasoline according to claim 16, wherein Co and Mo have an overall loading of 5-20% on the carrier.

18. The method for desulfurization of gasoline according to claim 11, wherein the light gasoline fraction is subjected to the adsorption desulfurization after being subjected to demercaptan treatment.

19. The method for desulfurization of gasoline according to claim 11, wherein the gasoline is cut into the light gasoline fraction and the heavy gasoline fraction after being subjected to demercaptan treatment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a curve of adsorption and desorption isotherms of a ZSM-5 type zeolite before and after alkali treatment according to Embodiment 1;

(2) FIG. 2 is a curve of pore diameter distribution of a ZSM-5 type zeolite before and after alkali treatment according to Embodiment 1;

(3) FIG. 3 is a process flow chart of a method for desulfurization of gasoline according to Embodiment 7;

(4) FIG. 4 is a process flow chart of a method for desulfurization of gasoline according to Embodiment 8; and

(5) FIG. 5 is a process flow chart of a method for desulfurization of gasoline according to Embodiment 9.

DETAILED DESCRIPTION

(6) In order to make objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in embodiments of the present invention are hereinafter described clearly and completely with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of embodiments of the present invention, rather than all embodiments of the present invention. All other embodiments obtained by those skilled in the art based on embodiments of the present invention without any creative efforts shall fall within the protection scope of the present invention.

Embodiment 1

(7) 1. Prepare a Zeolite and Active Carbon Subjected to Alkali Treatment

(8) After elevating temperatures of two 500 mL of NaOH solutions at a concentration of 0.3 mol/L to about 70 C. by a water bath, adding 25 g of ZSM-5 type zeolite and 25 g of active carbon therein respectively, immediately lowering the temperature of the mixture to room temperature by an ice bath after stirring for about 200 minutes, filtering the mixture, and washing the filter cake with deionized water several times till a pH value of the filtrate is about 7, placing the filter cake obtained into an oven at a temperature of 110 C. to be dried for 4 h, and thus preparing a ZSM-5 type zeolite subjected to alkali treatment and active carbon subjected to alkali treatment respectively, where, curves of adsorption and desorption isotherms and pore diameter distribution of the ZSM-5 type zeolite before and after alkali treatment can be seen from FIG. 1 and FIG. 2 respectively.

(9) In addition, an ASAP2000 type automatically physical adsorption instrument is used to measure specific surface areas and pore diameter distributions of the ZSM-5 type zeolite and the active carbon, and results are as shown in Table 1.

(10) TABLE-US-00001 TABLE 1 Total specific Medium pore Average surface Total pore volume pore area S.sub.BET/ volume V/ V.sub.meso/ diameter Carrier (m.sup.2 .Math. g.sup.1) (cm.sup.3 .Math. g.sup.1) (cm.sup.3 .Math. g.sup.1) d/(nm) ZSM-5 zeolite 380 0.212 0.041 2.241 before alkali treatment ZSM-5 zeolite 427 0.430 0.300 4.031 after alkali treatment Active carbon 1190 0.701 0.326 2.321 before alkali treatment Active carbon 1254 0.742 0.358 2.427 after alkali treatment

(11) It can be seen from FIG. 1 that: the ZSM-5 zeolite before alkali treatment exhibits an I-type isotherm which is characterized by micropore properties, the desorption isotherm thereof is almost overlapped with the adsorption isotherm; whereas the ZSM-5 zeolite after alkali treatment exhibits an IV-type isotherm with obvious characteristics, which presents a continuous adsorption state till a saturation pressure within the entire measured pressure range, and which conducts desorption slowly with decrease in the pressure during the desorption firstly, when the pressure reaches a certain value, the desorption amount surges suddenly to form a relatively steep curve, and then it overlapped with the adsorption isotherm as pressure further decreases, thus it indicates that a great number of mesopores (medium pores) are generated in the ZSM-5 zeolite after alkali treatment.

(12) It can be seen from FIG. 2 that, the ZSM-5 zeolite before alkali treatment is mainly micropores, there is a wide distribution before 2 nm and a small peak at a position of 3.5 nm, and substantially no pores after 4 nm, an obtained average pore diameter calculated using a t-plot method is about 2.3 nm; there is still a distribution of a part of micropores before 2 nm for the ZSM-5 zeolite after alkali treatment, and a strong peak at a position of about 3.8 nm, the peak height is almost about 11 times the height of the ZSM-5 zeolite before alkali treatment, and there is also a relative wide distribution of pores after 4 nm.

(13) Meanwhile, results of Table 1 shows that: a medium pore volume and an average pore diameter of the ZSM-5 type zeolite subjected to alkali treatment are increased significantly, which indicates that a large number of micropores are converted into medium pores, thereby forming a composite pore structure of a mesopore and a micropore; the total specific surface area, the total pore volume, the medium pore volume and the average pore diameter of the active carbon subjected to alkali treatment are all increased.

(14) 2. Prepare a Composite Carrier

(15) Placing the ZSM-5 type zeolite subjected to alkali treatment and the active carbon subjected to alkali treatment in a mortar to be ground into powders after mixing them at a mass ratio of 40:60, then placing the mixture in an oven at a temperature of 120 C. to be dried for 6 h, thereby preparing a composite carrier.

(16) 3. Prepare a Desulfurization Adsorbent

(17) The composite carrier obtained above is firstly subjected to incipient wetness impregnation with a K.sub.2SO.sub.4 solution, after washing, drying and calcinating, then the composite carrier impregnated with K.sub.2SO.sub.4 solution is subjected to incipient wetness impregnation with NiSO.sub.4, and after washing, drying and calcinating, a desulfurization adsorbent is prepared;

(18) The washing, the drying and the calcinating described above are specifically: after washing the impregnated material with deionized water, drying it for 20 hours at a temperature of 120 C., after cooling the dried material down to room temperature, elevating the temperature to 400 C. at a speed of 6 C./min firstly, and then elevating the temperature to 550 C. at a speed of 3 C./min, conducting calcinations for 4 hours at the temperature of 550 C.

(19) In the desulfurization adsorbent prepared above, K has a loading of about 5% on the composite carrier, Ni has a loading of about 10% on the composite carrier; moreover, K and Ni which are loaded on the composite carrier have a mass ratio of 0.5:1.

Embodiment 2

(20) 1. Prepare a Zeolite and an Active Carbon Subjected to Alkali Treatment

(21) After elevating temperatures of two 500 mL of NaOH solutions at a concentration of 0.2 mol/L to about 80 C. by a water bath, adding 25 g of Y type zeolite and 25 g of active carbon therein respectively, immediately lowering a temperature of the mixture to room temperature by an ice bath after stirring for about 120 minutes, filtering the mixture, and washing the filter cake with deionized water several times till pH value of the filtrate is about 7, placing the filter cake obtained into an oven at a temperature of 120 C. to be dried for 3 h, and thus preparing a Y type zeolite subjected to alkali treatment and active carbon subjected to alkali treatment respectively; specific surface areas and pore diameter distributions of the Y type zeolite and the active carbon as shown in Table 2.

(22) TABLE-US-00002 TABLE 2 Specific Surface Areas and Pore Diameters of Y Type Zeolite and Active Carbon Total specific Medium pore Average surface Total pore volume pore area S.sub.BET/ volume V/ V.sub.meso/ diameter Carrier (m.sup.2 .Math. g.sup.1) (cm.sup.3 .Math. g.sup.1) (cm.sup.3 .Math. g.sup.1) d/(nm) Y type zeolite 706 0.390 0.053 2.001 before alkali treatment Y type zeolite 713 0.462 0.118 2.139 after alkali treatment Active carbon 1190 0.701 0.326 2.321 before alkali treatment Active carbon 1233 0.729 0.355 2.346 after alkali treatment

(23) 2. Prepare a Composite Carrier

(24) Placing the Y type zeolite subjected to alkali treatment and the active carbon subjected to alkali treatment in a mortar to be ground into powders after mixing them at a mass ratio of 20:80, then placing the mixture in an oven at a temperature of 110 C. to be dried for 6 h, thereby preparing a composite carrier.

(25) 3. Prepare a Desulfurization Adsorbent

(26) The composite carrier obtained above is firstly subjected to incipient wetness impregnation with a ZnSO.sub.4 solution, after washing, drying and calcinating, then the composite carrier impregnated with the ZnSO.sub.4 solution is subjected to incipient wetness impregnation with Fe.sub.2(SO.sub.4).sub.3, thereby preparing a desulfurization adsorbent after washing, drying and calcinating;

(27) The washing, the drying and the calcinating described above are specifically: after washing the impregnated material with deionized water, drying it for 24 hours at a temperature of 110 C., after cooling the dried material down to a room temperature, elevating the temperature to 400 C. at a speed of 6 C./min firstly, and then elevating the temperature to 450 C. at a speed of 3 C./min, conducting calcinations for 6 hours at the temperature of 450 C.

(28) In the desulfurization adsorbent prepared above, Zn has a loading of about 10% on the composite carrier, Fe has a loading of about 10% on the composite carrier; moreover, Zn and Fe which are loaded on the composite carrier have a mass ratio of 1:1.

Embodiment 3

(29) 1. Prepare a Zeolite and an Active Carbon Subjected to Alkali Treatment

(30) After elevating temperatures of two 500 mL of NaOH solutions at a concentration of 0.3 mol/L to about 80 C. by a water bath, adding 25 g of X type zeolite and 25 g of active carbon therein respectively, immediately lowering a temperature of the mixture to room temperature by an ice bath after stirring for about 180 minutes, filtering the mixture, and washing the filter cake with deionized water several times till a pH value of the filtrate is about 7, placing the filter cake obtained into an oven at a temperature of 100 C. to be dried for 6 h, and thus preparing an X type zeolite subjected to alkali treatment and active carbon subjected to alkali treatment respectively.

(31) 2. Prepare a Composite Carrier

(32) Placing the X type zeolite subjected to alkali treatment and the active carbon subjected to alkali treatment in a mortar to be ground into powders after mixing them at a mass ratio of 30:70, then placing the mixture in an oven at a temperature of 120 C. to be dried for 6 h, thereby preparing a composite carrier.

(33) 3. Prepare a Desulfurization Adsorbent

(34) The composite carrier prepared above is firstly subjected to incipient wetness impregnation with a K.sub.2SO.sub.4 solution, and after washing, drying and calcinating, then the composite carrier impregnated with the K.sub.2SO.sub.4 solution is subjected to incipient wetness impregnation with NiSO.sub.4, thereby preparing a desulfurization adsorbent after washing, drying and calcinating;

(35) The washing, the drying and the calcinating described above are specifically: after washing the impregnated material with deionized water, drying it for 18 hours at a temperature of 120 C., after cooling the dried material down to a room temperature, elevating the temperature to 400 C. at a speed of 6 C./min firstly, and then elevating the temperature to 640 C. at a speed of 3 C./min, conducting calcinations for 5 hours at the temperature of 640 C.

(36) In the desulfurization adsorbent prepared above, K has a loading of about 5% on the composite carrier, Ni has a loading of about 15% on the composite carrier; moreover, K and Ni which are loaded on the composite carrier have a mass ratio of 0.3:1.

Embodiment 4

(37) 1. Prepare a Zeolite and an Active Carbon Subjected to Alkali Treatment

(38) After elevating temperatures of two 500 mL of NaOH solutions at a concentration of 0.2 mol/L to about 70 C. by a water bath, adding 25 g of ZSM-5 type zeolite and 25 g of active carbon therein respectively, immediately lowering a temperature of the mixture to room temperature by an ice bath after stirring for about 90 minutes, filtering the mixture, and washing the filter cake with deionized water several times till a pH value of the filtrate is about 7, placing the filter cake obtained into an oven at a temperature of 120 C. to be dried for 3 h;

(39) Repeating the above steps one time respectively for the ZSM-5 type zeolite and the active carbon obtained (that is, conducting alkali treatment twice), and thus preparing a ZSM-5 type zeolite subjected to alkali treatment and an active carbon subjected to alkali treatment; specific surface areas and pore diameter distributions of the ZSM-5 type zeolite and the active carbon as shown in Table 3.

(40) TABLE-US-00003 TABLE 3 Specific Surface Areas and Pore Diameters of ZSM-5 Type Zeolite and Active Carbon Total specific Total Medium pore Average surface pore volume pore area S.sub.BET/ volume V/ V.sub.meso/ diameter Carrier (m.sup.2 .Math. g.sup.1) (cm.sup.3 .Math. g.sup.1) (cm.sup.3 .Math. g.sup.1) d/(nm) ZSM-5 type 380 0.212 0.041 2.241 zeolite before alkali treatment ZSM-5 type 432 0.433 0.302 4.030 zeolite after alkali treatment Active carbon 1190 0.701 0.326 2.321 before alkali treatment Active carbon 1259 0.749 0.363 2.430 after alkali treatment

(41) 2. Prepare a Composite Carrier

(42) Placing the ZSM-5 type zeolite subjected to alkali treatment and the active carbon subjected to alkali treatment in a mortar to be ground into powders after mixing them at a mass ratio of 20:80, then placing the mixture in an oven at a temperature of 100 C. to be dried for 8 h, thereby preparing a composite carrier.

(43) 3. Prepare a Desulfurization Adsorbent

(44) The composite carrier obtained above is subjected to incipient wetness impregnation with a ZnSO.sub.4 solution, after washing, drying and calcinating, then the composite carrier impregnated with the ZnSO.sub.4 solution is subjected to incipient wetness impregnation with Fe.sub.2(SO.sub.4).sub.3, and after washing, drying and calcinating, desulfurization absorbent is prepared;

(45) The washing, drying and calcinating described above are specifically: after washing the impregnated material with deionized water, drying it for 20 hours at a temperature of 120 C., after cooling the dried material down to a room temperature, elevating the temperature to 400 C. at a speed of 6 C./min firstly, and then elevating the temperature to 600 C. at a speed of 3 C./min, conducting calcinations for 6 hours at the temperature of 600 C.

(46) In the desulfurization adsorbent prepared above, Zn has a loading of about 5% on the composite carrier, Fe has a loading of about 10% on the composite carrier; moreover, Zn and Fe which are loaded on the composite carrier have a mass ratio of 0.5:1.

Comparative Embodiment 1

(47) After preparing a ZSM-5 type zeolite subjected to alkali treatment according to the method described in Embodiment 1, the ZSM-5 type zeolite subjected to alkali treatment is subjected to incipient wetness impregnation with a K.sub.2SO.sub.4 solution and a NiSO.sub.4 solution according to the method described in Embodiment 1 sequentially, and washing, drying and calcinating, thereby preparing a desulfurization adsorbent.

Comparative Embodiment 2

(48) After preparing an active carbon subjected to alkali treatment according to the method described in Embodiment 1, the active carbon subjected to alkali treatment is subjected to incipient wetness impregnation with a K.sub.2SO.sub.4 solution and a NiSO.sub.4 solution according to the method described in Embodiment 1 sequentially, and washing, drying and calcinating, thereby preparing a desulfurization adsorbent.

Comparative Embodiment 3

(49) Placing a ZSM-5 type zeolite (without alkali treatment) and an active carbon (without alkali treatment) in Embodiment 1 into a mortar to ground after directly mixing them at a mass ratio of 40:60, then placing it in an oven at a temperature of 120 C. to be dried for 6 h, thereby preparing a composite carrier.

(50) The composite carrier is subjected to incipient wetness impregnation with a K.sub.2SO.sub.4 solution and a NiSO.sub.4 solution according to the method described in Embodiment 1 sequentially, and washing, drying and calcinating, thereby preparing a desulfurization adsorbent.

Embodiment 5

(51) Filling the desulfurization adsorbent prepared in Embodiments 1-4 and Comparative Embodiments 1-3 into a fixed-bed reactor respectively, using a fluid catalytic cracking gasoline as a feedstock (see Table 4 for its composition), carrying out an adsorption desulfurization experiment for consecutive 10 hours at a flow rate of 0.5 mL/min at a temperature of 30 C. and atmospheric pressure, see Table 5 for a result of the adsorption desulfurization experiment, where a sulfur capacity is a total desulfurized sulfur content (by gram) when 1 g of desulfurization adsorbent reduces the total sulfur content in the gasoline below 10 ppmw, for instance, when the sulfur capacity is 0.514, it indicates that the total desulfurized sulfur content desulfurized is 0.514 g on 1 g of desulfurization adsorbent to reduce the total sulfur content in the gasoline feedstock below 10 ppmw.

(52) TABLE-US-00004 TABLE 4 Composition of Gasoline Feedstock Items Value Density (20 C.), g/cm.sup.3 0.7012 Total sulfur content, ppmw 282 Thiophene and derivatives thereof, ppmw 260 Composition, m % Paraffin 35.0 Olefin 48.2 Naphthene 6.3 Aromatics 10.5 Octane number RON 90.2 MON 80.9

(53) TABLE-US-00005 TABLE 5 Result of Adsorption Desulfurization Experiment of Desulfurization Adsorbent Total sulfur content of gasoline Time of Desulfurization Sulfur after adsorption desulfurization duration adsorbent capacity (ppmw) (hour) Desulfurization 0.514 <1 .sup.0-4.5 adsorbent in <10 4.5-6.3 Embodiment 1 <50 6.3-8.3 Desulfurization 0.547 <1 .sup.0-4.8 adsorbent in <10 4.8-6.7 Embodiment 2 <50 6.7-8.6 Desulfurization 0.563 <1 .sup.0-5.0 adsorbent in <10 5.0-6.9 Embodiment3 <50 6.9-8.8 Desulfurization 0.490 <1 .sup.0-4.3 adsorbent in <10 4.3-6.0 Embodiment 4 <50 6.0-8.0 Desulfurization 0.286 <1 .sup.0-2.1 adsorbent in <10 2.1-3.5 Comparative <50 3.5-4.2 Embodiment1 Desulfurization 0.236 <1 .sup.0-1.5 adsorbent in <10 1.5-2.9 Comparative <50 2.9-3.9 Embodiment 2 Desulfurization 0.155 <1 .sup.0-0.8 adsorbent in <10 0.8-1.9 Comparative <50 1.9-2.7 Embodiment 3

(54) It can be seen from a result as shown in Table 5 that:

(55) 1. The adsorbent for desulfurization prepared in the present invention has highly deep desulfurization, sulfur in a gasoline feedstock may be reduced to below 1 ppmw after conducting adsorption desulfurization for 4-5 hours, and its service life lasts for about 8 h; moreover, the adsorbent for desulfurization has a large sulfur capacity and a good selectivity especially for thiophene and derivatives thereof.

(56) 2. When a zeolite subjected to alkali treatment is used as a carrier alone, service life of the adsorbent for desulfurization is shortened significantly; and when active carbon subjected to alkali treatment is used as a carrier alone, desulfurization adsorbent has a low selectivity for sulfur; when a zeolite and active carbon without alkali treatment are used as a composite carrier, sulfur capacity is relatively small and service life is short.

Embodiment 6

(57) Taking the desulfurization adsorbent in Embodiments 1-4 for desulfurization to breakthrough sulfur capacity (that is, the adsorbent loses efficacy) according to the method described in Embodiment 5 as a to-be-regenerated desulfurization adsorbent, firstly sweeping the to-be-regenerated desulfurization adsorbent with steam for washing, then sweeping the same with nitrogen for drying, and finally sweeping the same with nitrogen at a room temperature for cooling, see Table 6 for parameters of the regenerating process.

(58) The regenerated desulfurization adsorbent is repeatedly subjected to adsorption desulfurization and regeneration according to the method described in Embodiment 5, a desulfurization adsorbent subjected to adsorption desulfurization for three times and regeneration for three times is used to conduct adsorption desulfurization according the method described in Embodiment 5, and see Table 7 for a result of the adsorption desulfurization experiment.

(59) TABLE-US-00006 TABLE 6 Parameters of Regenerating Process of Desulfurization Adsorbent Steam-sweeping for washing Nitrogen-sweeping for drying Nitrogen-sweeping for cooling Steam Sweeping Nitrogen Sweeping Nitrogen Sweeping temperature time temperature time temperature time Adsorbents ( C.) (h) ( C.) (min) ( C.) (min) Desulfurization 150 3 300 30 30 30 adsorbent in Embodiment 1 Desulfurization 180 1 400 10 35 10 adsorbent in Embodiment 2 Desulfurization 130 3 200 60 20 60 adsorbent in Embodiment 3 Desulfurization 160 2 300 45 25 45 adsorbent in Embodiment 4

(60) TABLE-US-00007 TABLE 7 Result of Adsorption Desulfurization Experiment of Desulfurization Adsorbent Regenerated for Three Times Total sulfur content of gasoline Time of Sulfur after adsorption desulfurization duration Adsorbents capacity (ppmw) (hour) Desulfurization 0.473 <1 .sup.0-4.2 adsorbent in <10 4.2-5.8 Embodiment 1 <50 5.8-7.0 Desulfurization 0.481 <1 .sup.0-4.4 adsorbent in <10 4.4-5.8 Embodiment 2 <50 5.8-7.2 Desulfurization 0.514 <1 .sup.0-4.5 adsorbent in <10 4.5-6.3 Embodiment 3 <50 6.3-8.3 Desulfurization 0.457 <1 .sup.0-4.0 adsorbent in <10 4.0-5.6 Embodiment 4 <50 5.6-6.8

(61) It can be seen from a result of Table 7 that:

(62) After the desulfurization adsorbent according to the present invention is subjected to regeneration several times by using the regenerating method described above, the desulfurization adsorbent still can maintain a high sulfur capacity and a good desulfurization effect.

Embodiment 7

(63) 1. Prepare a Selective Hydrodesulfurization Catalyst

(64) A ZSM-5 type zeolite (carrier) is firstly subjected to incipient wetness impregnation with a CoSO.sub.4 solution, after washing, drying and calcinating, then the ZSM-5 type zeolite impregnated with the CoSO.sub.4 solution is subjected to incipient wetness impregnation with an aqueous solution of (NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O, and after washing, drying and calcinating, a selective hydrodesulfurization catalyst is prepared, wherein, reference may be made to Embodiment 1 for a specific operation of the washing, the drying and the calcinating.

(65) A total specific surface area of the selective hydrodesulfurization catalyst prepared above is about 356 m.sup.2/g, a total pore volume is about 0.315 cm.sup.3.Math.g.sup.1, Co has a loading of about 5% on the carrier, Mo has a loading of about 10% on the carrier, and Co and Mo which are loaded on the carrier have a mass ratio of 0.5:1.

(66) 2. Gasoline Desulfurization

(67) Fluid catalytic cracking gasoline which is produced from Daqing atmospheric pressure heavy oil subjected to catalytic cracking is taken as a feedstock (see Table 8 for its composition), and a process flow of desulfurization of the gasoline feedstock as shown in FIG. 3.

(68) Firstly, cutting the gasoline feedstock into a light gasoline fraction and a heavy gasoline fraction, where a cutting temperature of the light and heavy gasoline fraction is 100 C.

(69) Filling the desulfurization adsorbent prepared in Embodiment 1 into a fixed-bed reactor, and at a temperature of 30 C. and atmospheric pressure, the light gasoline fraction being subjected to adsorption desulfurization at a flow rate of 0.5 mL/min to obtain a desulfurized light gasoline fraction; in addition, after the adsorption desulfurization, sweeping the desulfurization adsorbent which has been subject to the adsorption desulfurization with steam at a temperature of 150 C. for 3 h for washing, collecting a sulfur-rich component, and incorporating the sulfur-rich component into the heavy gasoline fraction to proceed with a next step.

(70) Filling the selective hydrodesulfurization catalyst prepared above into the fixed-bed reactor, the heavy gasoline fraction incorporated with the sulfur-rich component is subjected to selective hydrodesulfurization in a condition where a reacting temperature is 260 C., a reacting pressure is 1.8 MPa, a liquid hourly space velocity is 3.0 h.sup.1, and a volume ratio of hydrogen to oil is 500, thereby obtaining a desulfurized heavy gasoline fraction. Mixing the desulfurized heavy gasoline fraction with the desulfurized light gasoline fraction to prepare a desulfurized gasoline, and see Table 8 for its composition.

(71) TABLE-US-00008 TABLE 8 Composition of Gasoline before and after Desulfurization Gasoline Desulfurized Items feedstock gasoline Density (20 C.), g/cm.sup.3 0.7012 0.7252 Sulfur content, ppmw 282 10 Group composition, m % Paraffin 35.0 47.2 Olefin 48.2 24.0 Naphthene 6.3 11.5 Aromatics 10.5 17.3 Octane number RON 90.2 89.7 MON 80.9 80.6

(72) It can be seen from Table 8 that:

(73) The method for desulfurization of gasoline as described in this Embodiment not only can reduce sulfur content in the gasoline feedstock below 10 ppm, but also can control olefin content below 24%, and loss of octane number (RON) is only 0.5.

Embodiment 8

(74) 1. Prepare a Selective Hydrodesulfurization Catalyst

(75) Preparing a selective hydrodesulfurization catalyst according to the method described in Embodiment 7, whereas the difference lies in that, controlling Co to have a loading of about 2% on the carrier, and controlling Mo to have a loading of about 8% on the carrier; moreover, Co and Mo which are loaded on the carrier have a mass ratio of 0.25:1.

(76) 2. Gasoline Desulfurization

(77) Fluid catalytic cracking gasoline from Daqing is taken as a feedstock (see Table 9 for its composition), and a process flow of desulfurization of the gasoline feedstock as shown in FIG. 4.

(78) Firstly, fractionating the gasoline feedstock into a light gasoline fraction and a heavy gasoline fraction, where a cutting temperature of the light and heavy gasoline fractions is 80 C.

(79) The light gasoline fraction is enabled to be in contact with alkali solution for demercaptan treatment in an extraction system, where the alkali used is a NaOH solution in a mass content of 20%, a volume ratio of the light gasoline fraction to the NaOH solution is 5:1, an operating temperature is 30 C., a demercaptan light gasoline fraction and extracted oil are collected, and the extracted oil is incorporated into the heavy gasoline fraction to proceed with a next step.

(80) Filling the desulfurization adsorbent prepared in Embodiment 2 into a fixed-bed reactor, at a temperature of 30 C. and atmospheric pressure, the demercaptan light gasoline fraction being subjected to adsorption desulfurization at a flow rate of 0.3 mL/min to obtain a desulfurized light gasoline fraction; after the adsorption desulfurization, sweeping the desulfurization adsorbent subjected to the adsorption desulfurization with steam at a temperature of 180 C. for 1 h for washing, collecting a sulfur-rich component, and incorporating the sulfur-rich component into the heavy gasoline fraction to proceed with a next step.

(81) Filling the selective hydrodesulfurization catalyst prepared above into the fixed bed reactor, the heavy gasoline fraction incorporated with extracted oil and the sulfur-rich component is subjected to hydrodesulfurization in a condition where a reacting temperature is 300 C., a reacting pressure is 1.5 MPa, a liquid hourly space velocity is 4.0 h.sup.1, and a volume ratio of hydrogen to oil is 600, thereby obtaining a desulfurized heavy gasoline fraction. Mixing the desulfurized heavy gasoline fraction with the desulfurized light gasoline fraction to prepare a desulfurized gasoline, and see Table 9 for its composition.

(82) TABLE-US-00009 TABLE 9 Composition of Gasoline before and after Desulfurization Gasoline Desulfurized Items feedstock gasoline Density (20 C.), g/cm.sup.3 0.7012 0.7208 Sulfur content, ppmw 282 10 Group composition, m % Paraffin 35.0 47.8 Olefin 48.2 23.2 Naphthene 6.3 11.4 Aromatics 10.5 17.6 Octane number RON 90.2 89.5 MON 80.9 80.2

(83) It can be seen from Table 9 that:

(84) The method for desulfurization of gasoline as described in this Embodiment not only can reduce sulfur content in the gasoline feedstock below 10 ppm, but also can control olefin content below 24%, and loss of octane number is only 0.7.

Embodiment 9

(85) Fluid catalytic cracking gasoline from Jinan is taken as a feedstock (see Table 10 for its composition), and a process flow of desulfurization of the gasoline feedstock as shown in FIG. 5.

(86) Firstly, a mercaptan conversion method (an alkali-free deodorization process) is used to conduct demercaptan treatment for the gasoline feedstock, where an operating pressure of the reactor is controlled at about 0.5 MPa, a reacting temperature is about 40 C., a feeding space velocity is 1.0 h.sup.1 and a volume ratio of an air flow to a feeding flow is about 0.5 to collect a demercaptan gasoline.

(87) The demercaptan gasoline feedstock is cut into a light gasoline fraction and a heavy gasoline fraction, and a cutting temperature of the light and the heavy gasoline fractions is 80 C.

(88) Filling the desulfurization adsorbent prepared in Embodiment 4 into a fixed-bed reactor, and in a condition of temperature of 30 C. and atmospheric pressure, the light gasoline fraction is subjected to adsorption desulfurization at a flow rate of 0.8 mL/min to obtain a desulfurized light gasoline fraction; and after the adsorption desulfurization, sweeping the desulfurization adsorbent subjected to the adsorption desulfurization with steam at a temperature of 160 C. for 2 h for washing, collecting a sulfur-rich component, incorporating the sulfur-rich component into the heavy gasoline fraction to proceed with a next step.

(89) Filling the selective hydrodesulfurization catalyst prepared in Embodiment 7 into the fixed-bed reactor, the heavy gasoline fraction incorporated with the sulfur-rich component is subjected to hydrodesulfurization in a condition where a reacting temperature is 300 C., a reacting pressure is 2.5 MPa, a liquid hourly space velocity is 2.0 h.sup.1, and a volume ratio of hydrogen to oil is 400, thereby obtaining a desulfurized heavy gasoline fraction. Mixing the desulfurized heavy gasoline fraction with the desulfurized light gasoline fraction to prepare a desulfurized gasoline, and see Table 10 for its composition.

(90) TABLE-US-00010 TABLE 10 Composition of Gasoline before and after Desulfurization Gasoline Desulfurized Items feedstock gasoline Density (20 C.), g/cm.sup.3 0.7562 0.7748 Surfur content, ppmw 421 10 Group composition, m % Paraffin 25.6 35.0 Olefin 30.9 12.6 Naphthene 8.9 14.2 Aromatics 34.6 38.2 Octane number RON 89.2 88.6 MON 80.1 79.8

(91) It can be seen from Table 10 that:

(92) The method for desulfurization of gasoline as described in this embodiment not only can reduce sulfur content in the gasoline feedstock below 10 ppm, but also can control olefin content below 24%, and loss of octane number is only 0.6.

(93) Finally, it should be noted that the foregoing embodiment are merely intended for describing technical solutions of the present invention rather than limiting the present invention. Although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they may still make modifications to the technical solutions described in the foregoing embodiments, or make equivalent replacements to some or all technical features thereof; however, these modifications or replacements do not make the essence of corresponding technical solutions depart from the scope of the technical solutions in the embodiments of the present invention.