Process for the selective hydrogenation of pyrolysis gasoline

Abstract

A method for selective hydrogenation of pyrolysis gasoline, comprising contacting pyrolysis gasoline with a hydrogenation catalyst in the presence of hydrogen, the hydrogenation catalyst comprising a composite oxide, the composite oxide comprising alumina and titania, the specific surface area of the composite oxide being represented by X m 2 / g, the average pore diameter of the composite oxide being represented by Y nm, wherein the ratio of X to Y is 5 to 30; in the composite oxide, the titania in an anatase crystal phase accounts for 95wt% to 100wt% of the total titania. The method can selectively hydrogenate dienes in the C6-C8 fraction and the C9-C10 fraction of pyrolysis gasoline, and has the advantages of good low-temperature activity, good adaptability to raw materials, and high stability.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for selective hydrogenation of pyrolysis gasoline. BACKGROUND

[0002] Pyrolysis gasoline is the first by-product of ethylene industry. Its composition has hundreds of compounds according to different raw materials and cracking depth, and its yield accounts for about 50% to 80% of the ethylene production capacity. How to make good use of this part of by-products will have a significant impact on improving the economic efficiency of enterprises.

[0003] Pyrolysis gasoline contains a large amount of diene and sulfur and nitrogen compounds, which leads to unstable oil properties and affects its further use. In industry, hydrogenation technology is usually used to improve the stability of unsaturated hydrocarbons and remove impurities in the oil. The cutting method is used to separate C6-C8, C9 and C10 different fraction sections or full fraction for two-stage hydrofining. After the first-stage hydrofining, highly unsaturated hydrocarbons such as chain conjugated diene, styrene, alkyne and cyclic conjugated diene are removed. Then, after the second-stage hydrodesulfurization, monoene and organic compounds such as sulfur, nitrogen and oxygen are removed. The fraction oil after two-stage hydrofining can be used to produce benzene, toluene, xylene, gasoline blending oil and aromatic solvent oil products.

[0004] The core technology of pyrolysis gasoline hydrogenation lies in the development and application of hydrogenation catalysts. In industry, Ni / Al2O3 or Pd / Al2O3 is generally used as a selective hydrogenation catalyst for the first-stage hydrogenation, and there is also a Pd-Cr / Al2O3 bimetallic catalyst. In industry, Al2O3 loaded with Co, Mo, Ni and other metals is generally used as a hydrogenation catalyst for the second-stage hydrogenation to remove monoene and sulfides.

[0005] Chinese patent CN1218822A reports a Ni / Al2O3 selective hydrogenation catalyst suitable for pyrolysis gasoline fraction, which is prepared by loading nickel on an alumina carrier containing lithium or alkaline earth metal. The hydrogenation stability of this catalyst is not very good. CN1253987A reports a Ni / Al2O3 diene selective hydrogenation catalyst, the active component nickel content is 5%-30% (by weight), the Fe0 content is 0.1%-5% (by weight), the Mo content is 0.1%-5% (by weight), and the carrier is active alumina. When the nickel content of the catalyst is <6% (by weight), Ni almost forms a spinel structure of NiAl2O4 with Al2O3, and the hydrogenation activity and sulfur resistance of the catalyst are very poor. When the Ni content is very high, the Ni content of such a catalyst reaches 30% (by weight), which increases the cost of the catalyst, and the excess nickel crystal phase will also aggregate during use, affecting the hydrogenation activity of the catalyst. Chinese patent CN1429890A discloses a catalyst for selective hydrogenation of pyrolysis gasoline, the active component of which is palladium, and the impurity resistance of the catalyst needs to be improved. SUMMARY

[0006] The present application is directed to a method for selectively hydrogenating pyrolysis gasoline, which uses a hydrogenation catalyst having a specific structure, in which TiO2 is uniformly dispersed on the surface of the carrier, and which has a low-temperature activity and a high hydrogenation activity at a high space velocity, and which is inexpensive and readily available and suitable for industrial production.

[0007] The present application provides a method for selectively hydrogenating pyrolysis gasoline, which comprises contacting pyrolysis gasoline with a hydrogenation catalyst in the presence of hydrogen, the hydrogenation catalyst comprising a composite oxide, the composite oxide comprising alumina and titania, the specific surface area of the composite oxide being represented by X m 2 / g, and the average pore diameter of the composite oxide being represented by Y nm, wherein the ratio of X to Y is 5 to 30. Preferably, in the composite oxide, the anatase crystalline phase of titania accounts for 96 wt% to 100 wt% of the total titania. Preferably, in the composite oxide, the anatase crystalline phase of titania accounts for 97 wt% to 100 wt% of the total titania. Preferably, in the composite oxide, the anatase crystalline phase of titania accounts for 98 wt% to 100 wt% of the total titania. Preferably, in the composite oxide, the anatase crystalline phase of titania accounts for 99 wt% to 100 wt% of the total titania.

[0008] In the present application, the proportion of the anatase crystalline phase of titania to the total titania can be measured by X-ray diffraction analysis.

[0009] In the present application, the specific surface area of the composite oxide can be measured by the BET method.

[0010] According to some embodiments of the composite oxide of the present application, the diffraction peak area representing the crystal structure of the anatase-type titania accounts for 95 wt% to 100 wt% of the diffraction peak area of all the crystal structures of titania, as measured by X-ray diffraction analysis.

[0011] According to some embodiments of the composite oxide of the present application, the diffraction peak area representing the crystal structure of the anatase-type titania accounts for 96 wt% to 100 wt% of the diffraction peak area of all the crystal structures of titania, as measured by X-ray diffraction analysis.

[0012] According to some embodiments of the composite oxide of the present application, the diffraction peak area representing the crystal structure of the anatase-type titania accounts for 97 wt% to 100 wt% of the diffraction peak area of all the crystal structures of titania, as measured by X-ray diffraction analysis.

[0013] According to some embodiments of the composite oxide according to the present application, the diffraction peak area representing the crystal structure of the anatase type titanium dioxide accounts for 98wt% to 100wt% of the total diffraction peak area of the crystal structure of titanium dioxide, as measured by X-ray diffraction analysis.

[0014] According to some embodiments of the present application, the pore volume of the composite oxide is Z mL / g, and the ratio of X to Z is 220 to 400, preferably 250 to 350. In some embodiments, the ratio of X to Z is 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, or within a range consisting of any two of them.

[0015] According to some embodiments of the present application, X is 90 to 150. In some embodiments, X is 90, 100, 110, 120, 130, 140, 150, or within a range consisting of any two of them.

[0016] According to some embodiments of the present application, Y is 9 to 20, preferably 12 to 16. In some embodiments, Y is 12, 13, 14, 15, 16, or within a range consisting of any two of them.

[0017] According to some embodiments of the present application, Z is 0.3 to 0.5, preferably 0.3 to 0.4. In some embodiments, Z is 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, or within a range consisting of any two of them.

[0018] According to some embodiments of the present application, the composite oxide contains 5wt% to 21wt% of titanium dioxide. In some embodiments, the composite oxide contains 5wt%, 6wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 21wt%, or within a range consisting of any two of them.

[0019] According to some embodiments of the present application, the composite oxide has a coral-like 3D hierarchical structure. The coral-like 3D hierarchical structure can have a higher specific surface area, thereby having more active sites and stronger light trapping ability.

[0020] According to some embodiments of the present application, the preparation method of the composite oxide comprises the following steps:

[0021] Step I. Dissolving a soluble aluminum salt in water to form an aluminum salt solution, dissolving a titanium salt in an acid solution to form a titanium salt solution, and mixing an ammonium salt and a lye solution to form a mixed lye solution;

[0022] Step II. (a) adding the titanium salt solution and the mixed base solution to the aluminum salt solution, and keeping the mixture at a first pH value for a first time period; (b) stopping adding the titanium salt solution, and continuing adding the mixed base solution, and keeping the mixture at a second pH value for a second time period; (c) stopping adding the mixed base solution, and adding the titanium salt solution, and keeping the mixture at a third pH value for a third time period;

[0023] Step III. After step II.(c), increasing the temperature of the mixture, and keeping the temperature for a fourth time period, to obtain a precipitate;

[0024] Step IV. drying and calcining the precipitate to obtain a composite oxide containing alumina and titania, preferably, washing and filtering are further performed before drying.

[0025] According to some embodiments of the present application, in step II, the first pH value is less than 5, preferably 3 to 4. According to some embodiments of the method of the present application, in step II, the second pH value is greater than 8.5, preferably 9 to 10. According to some embodiments of the method of the present application, in step II, the third pH value is greater than 7 and less than 9, preferably 7.5 to 8.5.

[0026] According to some embodiments of the present application, in step II, the first time period, the second time period and the third time period are each 5 minutes to 20 minutes, preferably 10 minutes to 15 minutes.

[0027] According to some embodiments of the present application, in step II, the fourth time period is 20 minutes to 60 minutes.

[0028] According to some embodiments of the present application, in step III, the operating temperature is 25°C to 60°C, preferably 50°C to 60°C.

[0029] According to some embodiments of the present application, in step III, the temperature is increased to 80°C to 150°C, preferably 80°C to 100°C. In some embodiments, in step III, the temperature is increased to 80°C, 85°C, 90°C, 92°C or 95°C.

[0030] According to some embodiments of the present application, in step IV, the drying temperature is 110°C to 130°C.

[0031] According to some embodiments of the method of the present application, in step IV, the calcining temperature is 800°C to 1000°C. In some embodiments, in step IV, the calcining temperature is 800°C, 850°C, 900°C, 950°C or a range consisting of any two of them.

[0032] According to some embodiments of the present application, the concentration of the aluminum salt is 0.5 to 2.5 mol / L. The aluminum salt can be selected from one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, and other organic aluminum salts.

[0033] According to some embodiments of the present application, the concentration of the titanium salt is 0.2 to 1.2 moL / L. According to some embodiments of the preparation method of the present application, the concentration of the ammonium salt is 0.1 to 0.3 moL / L. The ammonium salt can be selected from one or more of ammonium bicarbonate, ammonium carbonate, and other organic ammonium salts.

[0034] According to some embodiments of the present application, the concentration of the alkali solution is 0.2 to 0.4 moL / L. The alkali solution can be selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, and other organic alkalis.

[0035] According to some embodiments of the present application, the acid solution can be selected from one or more of sulfuric acid, nitric acid, hydrochloric acid, and other organic acids.

[0036] According to some embodiments of the present application, in step IV, the washing process of the precipitate includes washing with deionized water until the acid radical ion is not detected, the drying temperature is 100°C to 120°C, the drying time is 4°C to 12h, and the calcination temperature is 800°C to 1000°C. In some embodiments, in step IV, the calcination temperature is 800°C, 850°C, 900°C, 950°C, or a range defined by any two of them.

[0037] The composite oxide prepared by the method contains 5% to 21% of titanium dioxide, which is uniformly mixed with aluminum oxide. The inventors have surprisingly found that the surface micro-morphology of the composite oxide is a 3D layered structure of coral clusters. The 3D layered structure of coral shape can make the composite oxide have a higher specific surface area, thereby having more active sites and stronger electron capture capacity, which helps to promote the catalytic effect of TiO2 as an electronic additive, thereby improving the comprehensive performance of the catalyst such as activity and selectivity.

[0038] Furthermore, it is generally believed that TiO2 calcination begins at 500℃ to produce rutile, and above 700℃, the majority of the TiO2 crystal phases transform from anatase to rutile. However, the composite oxide prepared by the method provided in this invention, after high-temperature calcination above 800℃, shows through X-ray diffraction analysis that anatase-type titanium dioxide accounts for 95%–100% of all TiO2 crystal phases, breaking with common knowledge. The inventors have discovered that TiO2 existing in the anatase form in the composite oxide possesses an electron-inducing effect, effectively inducing a decrease in the electron cloud density of the active metal Ni in the prepared catalyst (compared to the rutile phase generated by high-temperature calcination), thereby enhancing the adsorption capacity for alkynes in the reactants and improving the selective hydrogenation activity and selectivity of the catalyst.

[0039] According to some embodiments of the present invention, the hydrogenation catalyst further includes nickel and / or nickel oxide, preferably, the nickel content can be 8-25 wt%, more preferably 12-20 wt%.

[0040] According to some embodiments of the present invention, the pyrolysis gasoline comprises C6 to C8 fractions, the reactor inlet temperature is 35 to 60°C, and the space velocity is 2 to 4 h⁻¹. -1 The hydrogen-to-oil ratio is 80:1 to 200:1, and the pressure is 2.5 to 3.5 MPa.

[0041] According to some embodiments of the present invention, the pyrolysis gasoline comprises C9 to C10 fractions, the reactor inlet temperature is 50 to 90°C, and the space velocity is 1 to 2 h⁻¹. -1 The hydrogen-to-oil ratio is 200:1 to 600:1, and the pressure is 2.5 to 3.5 MPa.

[0042] This invention uses an alumina-titanium dioxide composite oxide with a coral cluster 3D microstructure as a support. This support can provide a higher specific surface area under the same pore size distribution and pore volume conditions, thereby having more active sites and stronger electron capture ability, ultimately improving the co-catalytic effect of TiO2 as an electron aid. Attached Figure Description

[0043] Figure 1 The 3D microstructure of the coral reef prepared by the alumina-titanium dioxide composite oxide in Example 1 is shown.

[0044] Figure 2 The XRD pattern of the alumina-titanium dioxide composite oxide prepared in Example 1 is shown. Detailed Implementation

[0045] To facilitate understanding of the present invention, the present invention will be described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not limited to the scope of application of the present invention.

[0046] The raw materials or components used in the present application can be prepared by commercial or conventional methods unless otherwise specified.

[0047] The specific surface area and pore structure of the composite oxides were determined by using ASAP 2020 adsorption instrument (N2 adsorption method) of Micromeritics Instrument Corporation of USA. The composite oxide sample was degassed at 623 K for 4 h before testing, and nitrogen was adsorbed at liquid nitrogen temperature. The sample data were processed using AMS software, and the specific surface area of the sample was obtained using the Brunauer-Emmet-Teller (BET) method. The average pore diameter was obtained from the nitrogen adsorption isotherm using the Barrett-Joyner-Halenda (BJH) method, and the pore volume was obtained from the P / Po single-point desorption curve.

[0048] The morphology of the composite oxides was observed by using QUANTA 200 scanning electron microscope of FEI Corporation.

[0049] The crystal phase structure of the composite oxides was characterized by using EMPYREAN X-ray diffractometer of PANalytical of the Netherlands. Cu Kα was used as the radiation source X-ray tube voltage was 40 kV, X-ray tube current was 40 mA, slit width was 10 mm, scanning range was 5-90°, and scanning speed was 0.013° / s.

[0050] Example 1

[0051] 328.02 g of Al2(SO4)3 was dissolved in deionized water to prepare 1000 mL of aluminum sulfate solution. 21.14 g of TiO(OH)2 was dissolved in the sulfuric acid solution, and deionized water was added to prepare 500 mL of dilute metatitanic acid sulfuric acid solution. 18 g of NH4HCO3 was dissolved in 600 mL of deionized water to prepare an ammonium bicarbonate solution, and 250 mL of ammonia water with a concentration of 24-28 wt% was added, and the mixture was stirred and mixed uniformly, and deionized water was added to prepare 1000 mL of mixed alkali solution.

[0052] At normal pressure and a temperature of 55°C, the above-mentioned dilute metatitanic acid sulfuric acid solution and the mixed alkali solution were added to the aluminum sulfate solution in parallel flow, and strong stirring was maintained, and the pH value of the mixed solution was maintained in the range of 3 to 4 for 15 min, the addition of the dilute metatitanic acid sulfuric acid solution was stopped, and the mixed alkali solution was continuously added to make the pH value = 9 to 10, and the pH value was maintained in this range for 15 min, the addition of the mixed alkali solution was stopped, the above-mentioned dilute metatitanic acid sulfuric acid solution was added, the pH value was adjusted to 7.5 to 8.5, and the temperature was raised to 92°C, and the temperature was maintained for 20 min, and the filter cake was filtered, and the filter cake was repeatedly washed with 20 times the volume of deionized water for 5 times, and the washed filter cake was dried at 110°C for 6 h, and was calcined at 850°C for 5 h. 114.3 g of composite oxide with a TiO2 content of 15.0% was obtained. The composite oxide was characterized by X-ray diffraction, and the results are shown in Table 1. Figure 1The SEM of the composite oxide can be seen that the surface micro-morphology of the composite oxide is a 3D layered structure of coral cluster. Figure 2 The XRD spectrum of the alumina-titania composite oxide prepared in Example 1 is shown. For the titania, only the characteristic diffraction peak of anatase appears at 2θ = 25.4° and no diffraction peak of other crystal phase appears at other positions, indicating that the TiO2 component in the composite oxide is in the form of anatase crystal phase, that is, the anatase crystal phase of titania accounts for 100wt% of the total titania.

[0053] Example 2

[0054] Take 256.04 g of Al2(SO4)3 and dissolve it in deionized water to prepare 1000 mL of aluminum sulfate solution. Take 32.15 g of Ti(SO4)2 and dissolve it in dilute sulfuric acid to prepare 500 mL of dilute sulfuric acid solution of titanium sulfate. Take 18 g of NH4HCO3 and dissolve it in 600 mL of deionized water to prepare an ammonium bicarbonate solution, then add 250 mL of ammonia water with a concentration of 24-28wt%, stir and mix uniformly, and add deionized water to make 1000 mL of mixed alkali solution.

[0055] At normal pressure, at a temperature of 60°C, the above-mentioned dilute sulfuric acid solution of titanium sulfate and the mixed alkali solution are added to the aluminum sulfate solution in parallel flow, strong stirring is maintained, the pH value of the mixed solution is maintained in the range of 3 to 4 for 15 min, the addition of the dilute sulfuric acid solution of titanium sulfate is stopped, the addition of the mixed alkali solution is continued, so that the pH is 9 to 10, and the pH is maintained in this range for 15 min, the addition of the mixed alkali solution is stopped, the above-mentioned dilute sulfuric acid solution of titanium sulfate is added, and the pH is adjusted to 7.5 to 8.5. The temperature is raised to 85°C and maintained for 40 min, filtered, the filter cake is washed repeatedly 5 times with 20 times the volume of deionized water, the washed filter cake is dried at 110°C for 6 h, and calcined at 950°C for 5 h. 86.8 g of alumina-titania composite oxide with a TiO2 content of 12.3% is obtained.

[0056] Example 3

[0057] The preparation process of the titania-alumina composite oxide in Example 1 is repeated, except that 379.79 g of Al(NO 3)3 is dissolved in deionized water to prepare 1000 mL of aluminum nitrate solution. Take 25.99 g of Ti(OCH3CH2)4 and dissolve it in anhydrous ethanol to prepare 500 mL of titanium tetraethoxide ethanol solution. Finally, 9.1% of alumina-titania composite oxide is obtained.

[0058] Example 4

[0059] The preparation procedure of titanium dioxide-alumina composite oxide in Example 1 was repeated, except that 396.92 g of Al(N03)3was dissolved in deionized water to prepare 1000 mL of aluminum nitrate solution. 6.13 g of TiO(OH)2was dissolved in sulfuric acid solution and deionized water was added to prepare 500 mL of dilute metatitanic acid sulfuric acid solution. Finally, 5.0% of alumina-titanium dioxide composite oxide was obtained.

[0060] Example 5

[0061] The preparation procedure of titanium dioxide-alumina composite oxide in Example 1 was repeated, except that 374.13 g of AlCl3-6H20 was dissolved in deionized water to prepare 1000 mL of aluminum chloride solution. 59.99 g of Ti(OCH3CH2)4was dissolved in anhydrous ethanol to prepare 500 mL of titanium tetraethoxide ethanol solution. Finally, 21.0 wt% of alumina-titanium dioxide composite oxide was obtained.

[0062] The scanning electron microscope and XRD test results show that the composite oxides prepared in Examples 2-5 are similar to Example 1, and the surface microstructure is a coral cluster 3D layered structure, and the Ti02component in the composite oxide is in the form of anatase phase.

[0063] Comparative Example 1

[0064] 268.46 g of Al2(S04)3was dissolved in deionized water to prepare 1000 mL of aluminum sulfate solution. 24.5 g of TiO(OH)2was dissolved in sulfuric acid solution and deionized water was added to prepare 1000 mL of dilute metatitanic acid sulfuric acid solution. 18 g of NH4HCO3was dissolved in 600 mL of deionized water to prepare an ammonium bicarbonate solution, and 250 mL of ammonia water with a concentration of 24-28 wt% was added, stirred and mixed uniformly, and deionized water was added to prepare 1000 mL of mixed alkali solution.

[0065] The three solutions of the above-mentioned deionized aqueous solution of aluminum sulfate, the dilute sulfuric acid solution of metatitanic acid and the mixed alkali solution are co-precipitated under the conditions of normal pressure and temperature of 70-75°C. The flow rate of the solution of the mixed alkali solution is controlled so that the pH value of the precipitate is kept in the range of 5.0-6.0 for 8 minutes, then the flow rate of the solution of the mixed alkali solution is increased so that the pH value of the mixed solution is kept in the range of 8.5-9.5 for 8 minutes, then the flow rate of the solution of the mixed alkali solution is decreased so that the pH value of the mixed solution is kept in the range of 5.0-6.0 for 8 minutes, then the flow rate of the solution of the mixed alkali solution is increased so that the pH value of the precipitate is kept in the range of 8.5-9.5, and the above-mentioned process is repeated until the solutions Al and Bl are completely added. The reaction liquid is kept at 70°C for 30 minutes, then filtered, the filter cake is washed with 15 times the volume of deionized water for 30 minutes, then filtered again, the washing process is repeated four times, and finally the filter cake is dried at 100-120°C for 8-12 hours and calcined at 950°C for 5 hours to obtain the titanium dioxide-aluminum oxide composite. The structure and performance results are shown in Table 1.

[0066] Comparative Example 2

[0067] Analyzed 401.88 g of AlCl3-6H2O was dissolved in 1000 ml of deionized water to prepare solution Al; chemically pure 43.25 g of Ti(OCH2CH3)4 was dissolved in 500 ml of benzene (benzene content was 99.8 (wt) %) to prepare solution Bl; analyzed NH4HCO3 18 g was dissolved in 600 ml of deionized water, 250 ml of ammonia water with a concentration of 24-28 wt% was added, stirred and mixed uniformly, and then deionized water was added to prepare 1000 ml of solution Cl.

[0068] The three solutions of Al, Bl and Cl were co-precipitated under the conditions of normal pressure and temperature of 70-75°C. The flow rate of the solution Cl was controlled so that the pH value of the precipitate was kept in the range of 5.0-6.0 for 8 minutes, then the flow rate of the solution Cl was increased so that the pH value of the mixed solution was kept in the range of 8.5-9.5 for 8 minutes, then the flow rate of the solution Cl was decreased so that the pH value of the mixed solution was kept in the range of 5.0-6.0 for 8 minutes, then the flow rate of the solution Cl was increased so that the pH value of the precipitate was kept in the range of 8.5-9.5, and the above-mentioned process was repeated until the solutions Al and Bl were completely added. The reaction liquid was kept at 70°C for 30 minutes, then filtered, the filter cake was washed with 15 times the volume of deionized water for 30 minutes, then filtered again, the washing process was repeated four times, and finally the filter cake was dried at 100-120°C for 8-12 hours and calcined at 550°C for 5 hours to obtain 42.7 g of titanium dioxide-aluminum oxide composite. The structure and performance results are shown in Table 1.

[0069] Comparative Example 3

[0070] The preparation process of the titanium dioxide-alumina composite oxide in Comparative Example 2 was repeated, except that the calcination temperature after drying was changed to 950°C.

[0071] The scanning electron microscope and XRD test results showed that the composite oxides prepared in Comparative Examples 1-3 did not have the coral cluster 3D layered structure, and the TiO2crystal phase was mainly titanium dioxide with a rutile crystal phase.

[0072] Table 1 Analysis data of titanium dioxide-alumina composite

[0073]

[0074]

[0075] Preparation of the catalyst:

[0076] Example 6

[0077] Take 100 mL of 24.72 g Ni / 100 mL of nickel nitrate aqueous solution to impregnate 156 g of the composite oxide prepared in the above Example 1, the impregnation time is 1 h, 110°C drying for 6 h, and calcination at 600°C for 4 h after filtration to dryness to prepare a Ni / Al2O3-TiO2catalyst A with a Ni content of 13.68%.

[0078] Example 7

[0079] Take 100 mL of 20.0 g Ni / 100 mL of nickel nitrate aqueous solution to impregnate 180 g of the composite oxide prepared in the above Example 1, the impregnation time is 0.5 h, 110°C drying for 5 h after filtration to dryness, and calcination at 550°C for 5 h. Then use 100 mL of 12.24 g Ni / 100 mL of nickel nitrate aqueous solution to impregnate 100 g of the above calcined catalyst precursor, the impregnation time is 0.5 h, 110°C drying for 4 h after filtration to dryness, and calcination at 550°C for 6 h to prepare a Ni / Al2O3-TiO2catalyst B with a Ni content of 19.82%.

[0080] Comparative Example 4

[0081] Take 100 mL of 24.72 g Ni / 100 mL of nickel nitrate aqueous solution to impregnate 156 g of the composite oxide prepared in the above Example 1, the impregnation time is 1 h, 110°C drying for 6 h after filtration to dryness, and calcination at 600°C for 4 h to prepare a Ni / Al2O3-TiO2catalyst C with a Ni content of 13.68%.

[0082] Comparative Example 5

[0083] Take 100 mL 24.72 g Ni / 100 mL of aqueous nickel nitrate solution to impregnate 156 g of the above prepared composite oxide in the above Example 1, the impregnation time is 1 h, after filtration and drying at 110°C for 6 h, calcination at 600°C for 4 h, to prepare a Ni content of 13.68% Ni / Al2O3-TiO2 catalyst A.

[0084] Comparative Example 6

[0085] Take 100 mL 24.72 g Ni / 100 mL of aqueous nickel nitrate solution to impregnate 156 g of the above prepared composite oxide in the above Example 1, the impregnation time is 1 h, after filtration and drying at 110°C for 6 h, calcination at 600°C for 4 h, to prepare a Ni content of 13.68% Ni / Al2O3-TiO2 catalyst A.

[0086] Example 8

[0087] Use the cracking C9~C10 fraction of a chemical plant as raw material, the diene value is 21.36 g I2 / 100 g oil, and the bromine value is 101 g Br2 / 100 g oil.

[0088] Use the fixed bed hydrogenation reactor of Takagawa Company, fill 50 mL of catalyst A, B, C, D, E respectively, under the conditions of pressure 0.5 MPa, hydrogen amount 20 L / h, temperature 420°C, reduce for 15 h. Then cool the catalyst bed. Under the conditions of inlet temperature 40°C, hydrogen amount 5 L / h, fresh raw material space velocity 3.5 h -1 , and recycle ratio 3:1, evaluate, the evaluation results are shown in Table 2.

[0089] Table 2 Evaluation results of hydrogenation catalyst cracking C6~C8 fraction

[0090]

[0091] As can be seen from Table 2, the catalyst is applied to select hydrogenation saturation of diene in cracking C6~C8 fraction, which has the advantages of low temperature activity, good raw material adaptability and high stability.

[0092] Example 9

[0093] Use the cracking C9~C10 fraction of a chemical plant as raw material, the diene value is 21.36 g I2 / 100 g oil, and the bromine value is 101 g Br2 / 100 g oil.

[0094] The fixed bed hydrogenation reactor of Takagawa Company was used, and 50 mL of catalyst A, B, C, D and E were filled respectively, under the conditions of 0.5 MPa pressure, 20 L / h hydrogen amount and 440℃ temperature, reduction was carried out for 20 h. Then the catalyst bed was cooled. Under the conditions of 70℃ inlet temperature, 10 L / h hydrogen amount, fresh raw material space velocity of 1.5 h -1 , and circulation ratio of 1:1, the evaluation was carried out, and the evaluation results are shown in Table 3.

[0095] Table 3 Evaluation results of hydrogenation catalyst cracking C9-C10 fraction

[0096]

[0097] As can be seen from Table 3, the catalyst is applied to the selective hydrogenation saturation of dienes in C6-C8 fraction and C9-C10 fraction of cracked gasoline, and has the advantages of good low-temperature activity, good raw material adaptability and high stability.

[0098] It should be noted that the above-described embodiments are only used to explain the present application and do not constitute any limitation on the present application. The present application is described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified within the scope of the claims of the present application, and the present application can be revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and embodiments, it does not mean that the present application is limited to the specific examples disclosed therein, on the contrary, the present application can be extended to all other methods and applications with the same function.

Claims

1. A selective hydrotreating method for pyrolysis gasoline, comprising contacting pyrolysis gasoline with a hydrotreating catalyst in the presence of hydrogen, said hydrotreating catalyst comprising a composite oxide comprising alumina and titanium dioxide, the specific surface area of ​​said composite oxide being expressed as X m 2 / g, the average pore size of the composite oxide is expressed as Y nm, where, The ratio of X to Y is 5 to 30, and in the composite oxide, the anatase phase titanium dioxide accounts for 95 wt% to 100 wt% of the total titanium dioxide; the composite oxide has a coral-like 3D layered structure. The preparation method of the composite oxide includes the following steps: Step I. Dissolve soluble aluminum salts in water to form an aluminum salt solution, dissolve titanium salts in an acid solution to form a titanium salt solution, and mix ammonium salts and alkaline solutions to form a mixed alkaline solution; Step II. (a) Add the titanium salt solution and the mixed alkali solution to the aluminum salt solution, so that the mixture is maintained at the first pH value for a first time period; (b) Stop adding the titanium salt solution and continue adding the mixed alkali solution, so that the mixture is maintained at the second pH value for a second time period; (c) Stop adding the mixed alkali solution and add the titanium salt solution, so that the mixture is maintained at the third pH value for a third time period. Step III. After step II.(c), the temperature of the mixture is raised and maintained for a fourth time period to obtain a precipitate; Step IV. The precipitate is dried and calcined to obtain a composite oxide containing alumina and titanium dioxide; The first pH value is less than 5, the second pH value is greater than 8.5, and the third pH value is greater than 7 and less than 9. The first, second, and third time periods are 5 to 20 minutes each; the fourth time period is 20 to 60 minutes.

2. The method according to claim 1, characterized in that, The pore volume of the composite oxide is expressed as Z mL / g, and the ratio of X to Z is 220 to 400.

3. The method according to claim 2, characterized in that, The pore volume of the composite oxide is expressed as Z mL / g, and the ratio of X to Z is 250 to 350.

4. The method according to claim 2, characterized in that, X is 90 to 150; and / or Y is 9 to 20; and / or Z is 0.3 to 0.5; and / or the composite oxide contains 5 wt% to 21 wt% titanium dioxide.

5. The method according to claim 4, characterized in that, Y is 12 to 16; and / or Z is 0.3 to 0.

4.

6. The method according to any one of claims 1-5, characterized in that, The hydrogenation catalyst also includes nickel and / or nickel oxides.

7. The method according to claim 6, characterized in that, The nickel content in the catalyst is 8-25 wt%.

8. The method according to claim 6, characterized in that, The catalyst contains 12-20 wt% nickel.

9. The method according to claim 1, characterized in that, In step IV, washing and filtration are performed before drying.

10. The method according to claim 1, characterized in that, In step II, the first pH value is 3 to 4, the second pH value is 9 to 10, and the third pH value is 7.5 to 8.

5.

11. The method according to claim 1, characterized in that, The first, second, and third time periods are each 10 to 15 minutes long.

12. The method according to claim 1, characterized in that, In step II, the operating temperature is 25°C to 60°C; and / or in step III, the temperature is increased to 80°C to 150°C; and / or in step IV, the drying temperature is 110°C to 130°C; and / or the calcination temperature is 800°C to 1000°C.

13. The method according to any one of claims 1-5, characterized in that, The cracked gasoline comprises C6-C8 fractions, and the reactor inlet temperature is 35-60°C with a space velocity of 2-4 h⁻¹. -1 The hydrogen-to-oil ratio is 80:1 to 200:1, and the pressure is 2.5 to 3.5 MPa.

14. The method according to any one of claims 1-5, characterized in that, The pyrolyzed gasoline comprises C9-C10 fractions, the reactor inlet temperature is 50-90°C, and the space velocity is 1-2 h⁻¹. -1 The hydrogen-to-oil ratio is 200:1 to 600:1, and the pressure is 2.5 to 3.5 MPa.

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