Method for modifying molecular sieve and a catalytic cracking catalyst containing the molecular sieve

Abstract

The invention relates to a molecular sieve modification method and a catalytic cracking catalyst containing a molecular sieve. The method comprises: mixing a solution containing an ion of a Group MB metal in the periodic table, an organic complexing agent, and/or a dispersant and a precipitation agent, and stirring the same to form a suspension containing a precipitant of a Group IIIB element; and mixing the resulting precipitant and a molecular sieve slurry, stirring the same to obtain a mixed slurry containing the precipitant of the Group MB element and a molecular sieve, and performing spray drying and optional calcination, to obtain a modified molecular sieve. The catalyst comprises, as calculated based on the catalyst mass being 100%, 10-55% of a modified molecular sieve (on a dry basis), 10-80% of clay (on a dry basis), 0-40% of an inorganic oxide (on an oxide basis), and 5-40% of a binding agent (on an oxide basis). The catalyst has good activity stability and heavy metal contamination resistance.

Claims

1. A method for modifying a molecular sieve, wherein the method comprises: mixing and stirring a solution containing metal ions of Group IIIB of the periodic table with an organic complexing agent and/or a dispersant and a precipitating agent to form a suspension containing a precipitate of Group IIIB element; mixing the suspension containing the precipitate of Group IIIB element with a molecular sieve slurry to obtain a mixed slurry containing the precipitate of Group IIIB element and the molecular sieve; spray-drying and optionally calcining the mixed slurry, to obtain the molecular sieve modified with the Group IIIB element; wherein the weight ratio of the Group IIIB element in terms of oxide to the molecular sieve on dry basis is 0.3 to 10:100, the molar ratio of the organic complexing agent to the metal ions of Group IIIB is 0.3 to 10:1, and the molar ratio of the dispersant to the metal ions is 0.2 to 16:1.

2. The method for modifying according to claim 1, wherein the method comprises: mixing a solution containing the metal ions of Group IIIB of the periodic table with an organic complexing agent and/or a dispersant and a precipitating agent, and stirring this mixture for at least 10 minutes to form a suspension containing a precipitate of Group IIIB element; and mixing the suspension of the precipitate of Group IIIB element with a molecular sieve slurry and stirring this mixture at a temperature of 5 to 100° C. for at least 10 minutes to obtain a mixed slurry containing the precipitate of Group IIIB element and the molecular sieve; spray-drying and optionally calcining the mixed slurry, to obtain the molecular sieve modified with the Group IIIB element; wherein the weight ratio of the Group IIIB element in terms of oxide to the molecular sieve on dry basis is 0.3 to 10:100, the molar ratio of the organic complexing agent to the metal ions of Group IIIB is 0.3 to 10:1, and the molar ratio of the dispersant to the metal ions of Group IIIB is 0.2 to 16:1.

3. The method for modifying according to claim 2, wherein the mixed slurry containing the precipitate of Group IIIB element and the molecular sieve is obtained by stirring at a temperature of 5-60° C. for 10-40 minutes.

4. The method for modifying according to claim 2, wherein the weight ratio of the Group IIIB element in terms of oxide to the molecular sieve on dry basis is 0.3 to 8:100.

5. The method for modifying according to claim 2, wherein the molar ratio of the organic complexing agent to the metal ions of Group IIIB is 0.5 to 6:1; and the molar ratio of the dispersant to the metal ions of Group IIIB is 1 to 11:1.

6. The method for modifying according to claim 5, wherein the molar ratio of the organic complexing agent to the metal ions of Group IIIB is 1.0 to 4:1; and the molar ratio of the dispersant to the metal ions of Group IIIB is 2 to 7:1.

7. The method for modifying according to claim 2, wherein the precipitating agent is a substance capable of chemically reacting with the Group IIIB metal ion in the system and making the product thereof slightly soluble or insoluble in the system, in a chemical precipitation reaction.

8. The method for modifying according to claim 7, wherein the precipitating agent is one or more of oxalic acid, ammonium oxalate, ammonium carbonate, ammonium bicarbonate, carbon dioxide, aqueous ammonia, phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate and urea.

9. The method for modifying according to claim 2, wherein the organic complexing agent is selected from one or more of formic acid, acetic acid, adipic acid, citric acid, tartaric acid, benzoic acid, ethylenediamine tetraacetic acid, salicylic acid and salts of the above acids, and acetylacetone, diethanolamine, and triethanolamine.

10. The method for modifying according to claim 2, wherein the dispersant is a surfactant having both lipophilic and hydrophilic properties in the molecule, which can uniformly disperse those solid particles that are insoluble in liquid while preventing the sedimentation and agglomeration of the solid particles, and form a material needed for stabilizing the suspension, and the dispersant does not form precipitates with the metal ions of Group IIIB.

11. The method for modifying according to claim 10, wherein the dispersant is selected from one or more of monohydric or dihydric alcohols having 2 to 8 carbon atoms, polyethylene glycol, cellulose derivatives, polyacrylamide and derivatives thereof, and guar gum.

12. The method for modifying according to claim 11, wherein the cellulose derivative is selected from one or more of carboxymethylcellulose sodium, methyl hydroxyethyl cellulose, and hydroxy propyl methyl cellulose; and the monohydric or dihydric alcohol having 2 to 8 carbon atoms is selected from one or more of ethanol, ethylene glycol, isopropanol, butanol, and methylpentanol.

13. The method for modifying according to claim 2, wherein the Group IIIB element is selected from one or more of scandium, yttrium, and lanthanide rare earth elements.

14. The method for modifying according to claim 2, wherein the mixing process of the solution containing the metal ions of Group IIIB of the periodic table with the organic complexing agent and/or the dispersant, the precipitating agent is implemented through one of the following manners: Method 1: Uniformly mixing the solution containing the metal ions of Group IIIB of the periodic table with the organic complexing agent and/or the dispersant, followed by adding the precipitating agent and stirring for at least 10 minutes to form the precipitate containing Group IIIB element; Method 2: Uniformly mixing the precipitating agent with the organic complexing agent and/or the dispersant, followed by adding the compound solution containing the metal ions of Group IIIB of the periodic table and stirring for at least 10 minutes to form the precipitate containing Group IIIB element; Method 3: Mixing the precipitating agent with the compound solution containing the metal ions of Group IIIB of the periodic table, followed by adding the organic complexing agent and/or the dispersant and stirring for at least 10 minutes to form the precipitate containing Group IIIB element; or Method 4: Adding and mixing the solution containing the metal ions of Group IIIB of the periodic table and the organic complexing agent and/or the dispersant, the precipitating agent simultaneously, and stirring for at least 10 minutes to form the precipitate containing Group IIIB element.

15. A catalytic cracking catalyst containing a modified molecular sieve, wherein the catalyst contains a catalytically effective amount of the modified molecular sieve prepared by the method according to claim 2.

16. The catalytic cracking catalyst containing the modified molecular sieve according to claim 15, wherein the catalyst contains 10 to 55% on dry basis of the modified molecular sieve, 10 to 80% on dry basis of clay, 0 to 40% of an inorganic oxide in terms of oxide and 5 to 40% of a binder in terms of oxide, based on 100% of mass of the catalyst.

17. The catalytic cracking catalyst containing the modified molecular sieve according to claim 16, wherein the catalyst contains 15 to 45% on dry basis of the modified molecular sieve, 20 to 65% on dry basis of clay, 5 to 25% of the inorganic oxide in terms of oxide and 5 to 30% of the binder in terms of oxide, based on 100% of mass of the catalyst.

18. The method for modifying according to claim 2, wherein the molecular sieve slurry is a sodium-reduced molecular sieve slurry.

19. A method for preparing a catalytic cracking catalyst containing a modified molecular sieve, the method comprises: (1) mixing a solution containing the metal ions of Group IIIB of the periodic table with an organic complexing agent and/or a dispersant and a precipitating agent, and stirring this mixture for at least 10 minutes to form a suspension containing a precipitate of Group IIIB element and mixing the suspension of the precipitate of Group IIIB element with a molecular sieve slurry and stirring this mixture at a temperature of 5 to 100° C. for at least 10 minutes to obtain a mixed slurry containing the precipitate of Group IIIB element and the molecular sieve; and (2) mixing and slurrying the mixed slurry containing the precipitate of Group IIIB element and the molecular sieve obtained in (1), clay, an inorganic oxide and a binder, and spray-drying to prepare the catalyst.

20. The method according to claim 19, wherein the mixed slurry containing the precipitates of Group IIIB element and the molecular sieve is a mixed slurry containing the precipitate of Group IIIB element and a sodium-reduced molecular sieve.

Description

DETAILED DESCRIPTION

(1) The present invention is further illustrated as below by the Examples, but the present invention is not limited to these examples.

(2) (A) The analytical test method used in Examples

(3) 1. sodium oxide, yttrium oxide, and rare earth content: using X ray fluorescence analysis.

(4) 2. crystallinity, and unit cell constant of the molecular sieve: using X-ray diffraction analysis.

(5) 3. particle size: using laser particle size analyzer method.

(6) 4. catalyst activity determination: performed on CSA-B-type catalyst evaluation device produced by Huayang company. The catalyst was preliminarily aged at 800° C. under 100% of steam for 6 h or 17 h, and the activity of the catalyst was measured using Dagang light diesel oil as a raw material at a reaction temperature of 460° C., a reaction time of 70 s, a catalyst loading of 5.0 g and a ratio of oil to solvent of 3.2:1.

(7) (B) Specifications of raw material used in the Examples

(8) 1. NaY molecular sieve, REUSY molecular sieve (RE.sub.2O.sub.3 content: 4.02%, Na.sub.2O content: 1.24%), NH.sub.4Y molecular sieve (Na.sub.2O content: 1.68%, subjected to hydrothermal calcination once), ZSM-5 molecular sieve (Na.sub.2O content: 0.10%), kaolin (ignition loss: 18.6%) or kaolin (ignition loss: 14.6%), diatomaceous earth (ignition loss: 15.4%), aluminum sol (containing 21.2 wt % of alumina) or aluminum sol (containing 19.4 wt % of alumina), pseudo-boehmite (ignition loss: 31.8%), boehmite (ignition loss: 17.0%), silica (white carbon black, ignition loss: 9.91%), ammonia (concentration: 18%), rare earth nitrate (RE.sub.2O.sub.3 230.5 g/L): all of which are industrial products, from Lanzhou Petrochemical Company catalyst plant.

(9) 2. Ammonium sulfate, citric acid, ammonium citrate, ethylene glycol, ethanol, methyl hydroxyethyl cellulose, ammonium oxalate, ethylenediamine tetraacetic acid, urea, diammonium hydrogen phosphate, lanthanum nitrate, cerium nitrate, yttrium nitrate: all of which are chemical reagents.

(10) 3. Hydrochloric acid: concentration of 36%, chemical reagent.

(11) 4. Synthesized yttrium-containing Y-type molecular sieve slurry Y-1: the molecular sieve slurry was prepared by the following process: (1) adding 1000 g of NaY molecular sieve (on dry basis) to 7 L of deionized water, adding thereto 350 g of ammonium sulfate while stirring, adjusting the pH value of the slurry to 3.4 with hydrochloric acid, and stirring the mixture at a temperature of 85° C. for 1 hour, followed by filtering and washing to obtain a filter cake; mixing the filter cake (798 g on dry basis) with 102 g of yttrium nitrate and 2.2 L of deionized water, stirring for 0.5 h, spray-drying, and hydrothermally calcining in a calciner in an atmosphere of 100% steam at a calcination temperature of 600° C. for a calcination time of 2 hours; (2) mixing the molecular sieve obtained in the step (1), ammonium sulfate and water in a weight ratio of molecular sieve (on dry basis):ammonium salt:water=1:0.3:5 to form a slurry; stirring at 75° C. and pH=3.5 for 1 hour to obtain the synthesized yttrium-containing Y-type molecular sieve slurry Y-1.

Example 1

(12) 2 g of citric acid, 2.48 mL of rare earth nitrate and 75 mL of deionized water were mixed to form a homogeneous solution, then 2 g of ammonium oxalate was added and stirred for 15 minutes to form a rare earth-containing precipitate slurry CD-1.

Example 2

(13) 2 g of ethanol, 2.48 mL of rare earth nitrate and 75 mL of deionized water were mixed to form a homogeneous solution, then 2 g of ammonium oxalate was added and stirred for 15 minutes to form a rare earth-containing precipitate slurry CD-2.

Comparative Example 1

(14) 2.48 mL of rare earth nitrate and 75 mL of deionized water were mixed to form a homogeneous solution, then 2 g of ammonium oxalate was added and stirred for 15 minutes to form a rare earth-containing precipitate slurry DCD-1.

(15) The particle sizes were tested for the rare earth precipitates in the rare earth-containing precipitate slurries CD-1, CD-2, DCD-1 prepared by Examples 1, 2 and Comparative Example 1, respectively. The results are shown in Table 1:

(16) TABLE-US-00001 TABLE 1 The particle sizes of the rare earth precipitates particle size, % Items D(V, 0.1), μm D(V, 0.5), μm D(V, 0.9), μm the rare earth-containing precipitate CD-1 1.17 6.78 15.13 prepared in Example 1 the rare earth-containing precipitate CD-2 1.16 9.08 20.53 prepared in Example 2 the rare earth-containing precipitate DCD-1 1.18 12.24 27.37 prepared in Comparative Example 1

(17) The results in Table 1 show that in comparison with the rare earth-containing precipitate DCD-1 prepared by Comparative Example 1, the rare earth-containing precipitates CD-1 and CD-2 prepared by Examples 1 and 2 have a smaller particle size, indicating that the organic complexing agent and dispersant of the present invention can effectively reduce the particle size of the precipitates formed in the reaction of the rare earth with the precipitating agent.

Example 3

(18) (1) 16 g of citric acid, 4 g of ethylene glycol, 54 g of yttrium nitrate and 1 L of deionized water were mixed to form a homogeneous solution, then 100 g of ammonium oxalate was added and stirred for 15 minutes to form a yttrium-containing precipitate slurry.

(19) (2) The precipitate slurry formed in step (1) was added to the prepared yttrium-containing Y-type molecular sieve slurry Y-1, and stirred at a temperature of 55° C. for 10 minutes. The resultant was filtered, washed with water, and the filter cake was calcined at 600° C. under 100% steam atmosphere for 2 hours to obtain the modified molecular sieve Z-1.

(20) 600 g (on dry basis) of the molecular sieve Z-1 were added to 1.2 L of deionized water, and to a molecular sieve slurry Z-1J was obtained after sand milling. 619 g of aluminum sol (containing 19.4 wt % of alumina), 1499 g of kaolin (ignition loss: 14.6%), 2.2 L of water were mixed and slurried, and then added to the molecular sieve slurry Z-1J, and the stirring was continued for 30 minutes. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the catalyst C-1 of the present invention.

Example 4

(21) (1) 782 g (on dry basis) of REUSY molecular sieve, 16 g (on dry basis) of ZSM-5 molecular sieve and water were mixed according to the weight ratio of the molecular sieve (on dry basis): water=1:3 to form a molecular sieve slurry.

(22) (2) 110 g of ethylenediamine tetraacetic acid, and 104 mL of rare earth nitrate were added into 0.8 L of deionized water to form a solution, the pH value of the mixed slurry was adjusted with ammonia to 7.5-8.0, 23 g of ethanol was added and the mixture was stirred at room temperature (25° C.) for 30 minutes to form a rare earth-containing precipitate slurry.

(23) (3) The precipitate slurry formed in step (2) was added to the molecular sieve slurry obtained in step (1), and stirred at room temperature (25° C.) for 15 minutes. The resultant was filtered, washed, and the filter cake was dried at 200° C. to obtain the modified molecular sieve Z-2.

(24) 600 g (on dry basis) of the molecular sieve Z-2 was added to 1.2 L of deionized water, and a molecular sieve slurry Z-2J was obtained after sand milling. 619 g of aluminum sol (containing 19.4 wt % of alumina), 1513 g of diatomaceous earth, and 2.2 L of water were mixed and slurried, and then added to the molecular sieve slurry Z-2J, and the stirring was continued for 30 minutes. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the catalyst C-2 of the present invention.

Example 5

(25) (1) 798 g (on dry basis) of REUSY molecular sieve and water were mixed according to the weight ratio of the molecular sieve (on dry basis): water=1:3 to form a molecular sieve slurry.

(26) (2) 155 g of urea, and 85 g of lanthanum nitrate were added into 0.8 L of deionized water and stirred, the pH value of the molecular sieve slurry was adjusted with ammonia to 6.5-7.0, 14 g of ethylene glycol was added therein and the mixture was stirred at room temperature (25° C.) for 1.5 hours to form a rare earth-containing precipitate slurry.

(27) (3) The precipitate slurry formed in step (2) was added to the molecular sieve slurry obtained in step (1), and stirred at room temperature (25° C.) for 15 minutes. The mixed slurry was dried at 250° C. to obtain the modified molecular sieve Z-3.

(28) 600 g (on dry basis) of molecular sieve Z-3 were added to 1.2 L of deionized water, and the molecular sieve slurry Z-3J was obtained after sand milling. 1054 g of kaolin (ignition loss: 14.6%), 587 g of pseudo-boehmite, and 2.2 L of water were mixed and slurried. 60 mL of hydrochloric acid was added therein and stirred for 1 hour. The molecular sieve slurry Z-3J was added and stirred for 15 minutes. Then 515 g of aluminum sol (containing 19.4 wt % of alumina) was added, and the stirring was continued for 30 minutes to form a gel. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the catalyst C-3 of the present invention.

Example 6

(29) (1) 798 g (on dry basis) of NH.sub.4Y molecular sieve and water were mixed according to the weight ratio of the molecular sieve (on dry basis): water=1:5 to form a slurry.

(30) (2) 40 g of ammonium citrate, and 277 mL of rare earth nitrate were added to 0.6 L of deionized water, the pH value of the molecular sieve slurry was adjusted with ammonia to 8.0-9.0, and the stirring was continued at a temperature of 35° C. for 30 minutes to form a rare earth-containing precipitate slurry.

(31) (3) The precipitate slurry formed in step (2) was added to the molecular sieve slurry obtained in step (1), and stirred at 35° C. for another 40 minutes to obtain the modified molecular sieve Z-4 slurry. The modified molecular sieve Z-4 slurry was spray-dried to obtain the modified molecular sieve Z-4.

(32) 1030 g of kaolin (ignition loss: 14.6%), 440 g of pseudo-boehmite, 120 g of boehmite, and 2.2 L of water were mixed and slurried, 33 mL of hydrochloric acid was added therein and stirred for 1 hour, and then 600 g (on dry basis) of the modified molecular sieve Z-4 slurry was added and stirred for 15 minutes. Then 619 g of aluminum sol (containing 19.4 wt % of alumina) was added and the stirring was continued for 30 minutes to form a gel. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the catalyst C-4 of the present invention.

Example 7

(33) (1) 798 g (on dry basis) of NH.sub.4Y molecular sieve and water were mixed according to the weight ratio of the molecular sieve (on dry basis): water=1:3.5 to form a slurry.

(34) (2) 70 g of diammonium phosphate, 64 g of cerium nitrate were added to 0.4 L of deionized water, and stirred at a temperature of 15° C. for 10 minutes, and then 30 g of ethylene glycol, 15 g of ethanol were added and stirred for 20 minutes to form a rare earth-containing precipitate slurry.

(35) (3) The precipitate slurry formed in step (2) was mixed with the molecular sieve slurry obtained in step (1) and stirred at 15° C. for 25 minutes, the obtained molecular sieve after spray-dried was hydrothermally calcined in a calcination furnace under 100% steam atmosphere at a temperature of 550° C. and a calcination time of 2.5 hours to obtain the modified molecular sieve Z-5.

(36) 600 g (on dry basis) of molecular sieve Z-5 was added to 1.2 L of deionized water, after sanding treatment to obtain the molecular sieve slurry Z-5J. 738 g of kaolin (ignition loss: 14.6%), 220 g of pseudo-boehmite, and 1.5 L of water were mixed and slurried. 19 mL of hydrochloric acid was added and stirred for 1 hour. Then the molecular sieve slurry Z-5J was added and stirred for 25 minutes, then 619 g of aluminum sol (containing 19.4 wt % of alumina) was added and the stirring was continued for 30 minutes to form a gel. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the catalyst C-5 of the present invention.

Example 8

(37) (1) 798 g (on dry basis) of NH.sub.4Y molecular sieve and water were mixed according to the weight ratio of the molecular sieve (on dry basis): water=1:5 to form a slurry.

(38) (2) 69.2 mL of rare earth nitrate, 16 g of citric acid, and 3 g methyl hydroxyethyl cellulose were added into 0.7 L of deionized water and stirred at a temperature of 25° C. for 15 minutes, and then 64 g of ammonium oxalate was added and the stirring was continued for 15 minutes to form a rare earth-containing precipitate slurry.

(39) (3) The precipitate slurry formed in step (2) was mixed with the molecular sieve slurry obtained in step (1) and stirred for 15 minutes, the obtained molecular sieve was hydrothermally calcined in a calcination furnace under 100% steam atmosphere at a temperature of 650° C. for a calcination time of 2 hours to obtain the modified molecular sieve Z-6.

(40) 500 g (on dry basis) of molecular sieve Z-6 was added to 1.0 L of deionized water, and the molecular sieve slurry Z-6J was obtained after sand milling. 867 g of kaolin (ignition loss: 14.6%), 587 g of pseudo-boehmite, 222 g of silica, and 2.0 L of water were mixed and slurried. 50 mL of hydrochloric acid was added and stirred for 0.5 hour. Then the molecular sieve slurry Z-6J was added and stirred for 25 minutes, then 870 g of aluminum sol (containing 19.4 wt % of alumina) was added and the stirring was continued for 30 minutes to form a gel. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the catalyst C-6 of the present invention.

Comparative Example 2

(41) (1) 16 g of citric acid, 4 g of ethylene glycol, 54 g of yttrium nitrate and 1 L of deionized water were mixed and stirred for 15 minutes to form a yttrium-containing solution.

(42) (2) The yttrium-containing solution obtained in step (1) was added to the synthesized yttrium-containing Y-type molecular sieve slurry Y-1, and stirred at a temperature of 55° C. for 10 minutes. The resultant was filtered, washed with water, and the filter cake was calcined at 600° C. under 100% steam atmosphere for 2 hours to obtain the comparative molecular sieve DZ-1.

(43) 600 g (on dry basis) of molecular sieve DZ-1 was added to 1.2 L of deionized water, and the molecular sieve slurry DZ-1J was obtained after sand milling. 619 g of aluminum sol (containing 19.4 wt % of alumina), 1499 g of kaolin (ignition loss: 14.6%), and 2.2 L of water were mixed and slurried. Then the molecular sieve slurry DZ-1J was added and stirred for 30 minutes. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the comparative catalyst DC-1 containing the comparative molecular sieve DZ-1.

Comparative Example 3

(44) (1) 54 g of yttrium nitrate and 1 L of deionized water were mixed to form a homogeneous solution, then 100 g of ammonium oxalate was added therein and stirred for 15 minutes to form a yttrium-containing precipitate slurry.

(45) (2) The precipitate slurry formed in step (1) was added to the synthesized yttrium-containing Y-type molecular sieve slurry Y-1, and stirred at a temperature of 55° C. for 10 minutes. The resultant was filtered, washed, and the filter cake was calcined at 600° C. under 100% steam atmosphere for 2 hours to obtain the comparative molecular sieve DZ-2.

(46) 600 g (on dry basis) of molecular sieve DZ-2 was added to 1.2 L of deionized water, the molecular sieve slurry DZ-2J was obtained after sand milling. 619 g of aluminum sol (containing 19.4 wt % of alumina), 1499 g of kaolin (ignition loss: 14.6%), and 2.2 L of water were mixed and slurried. Then the molecular sieve slurry DZ-2J was added and stirred for 30 minutes. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the comparative catalyst DC-2 containing the comparative molecular sieve DZ-2.

Comparative Example 4

(47) The synthesized yttrium-containing Y-type molecular sieve slurry Y-1 was stirred at a temperature of 55° C. for 10 minutes. The resultant was filtered, washed with water, and the filter cake was calcined at 600° C. under 100% steam atmosphere for 2 hours to obtain the comparative molecular sieve DZ-3.

(48) 600 g (on dry basis) of molecular sieve DZ-3 was added to 1.2 L of deionized water, and the molecular sieve slurry DZ-3J was obtained after sand milling. 619 g of aluminum sol (containing 19.4 wt % of alumina), 1499 g of kaolin (ignition loss: 14.6%), and 2.2 L of water were mixed and slurried. Then the molecular sieve slurry DZ-3J was added and stirred for 30 minutes. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the comparative catalyst DC-3 containing the comparative molecular sieve DZ-3.

Comparative Example 5

(49) According to the preparation method of a molecular sieve containing rare earth disclosed by Chinese patent CN99105792.9: 798 g (on dry basis) of REUSY molecular sieve, 16 g (on dry basis) of ZSM-5 molecular sieve and water were mixed and slurried according to the weight ratio of molecular sieve (on dry basis): water=1:3 to form a molecular sieve slurry, 110 g of ethylenediamine tetraacetic acid was added, and the pH value of the molecular sieve slurry was adjusted with aqueous ammonia to be in the range of 7.5 to 8.0. And 23 g of ethanol was added therein, and stirred at room temperature (25° C.) for 45 minutes. The resultant was filtered, washed, and the filter cake was dried at 200° C. to obtain the comparative molecular sieve DZ-4.

(50) 600 g (on dry basis) of molecular sieve DZ-4 was added to 1.2 L of deionized water, and the molecular sieve slurry DZ-4J as obtained after sand milling. 619 g aluminum sol (containing 19.4 wt % of alumina), 1513 g of diatomaceous earth, and 2.2 L of water were mixed and slurried. Then the molecular sieve slurry DZ-4J was added and stirred for 30 minutes. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the comparative catalyst DC-4 containing the comparative molecular sieve DZ-4.

Comparative Example 6

(51) (1) 798 g (on dry basis) of REUSY molecular sieve and water were mixed according to the weight ratio of molecular sieve (on dry basis): water=1:3 to form a molecular sieve slurry.

(52) (2) 85 g of lanthanum nitrate was added into 0.8 L of deionized water and stirred, the pH value of the molecular sieve slurry was adjusted with aqueous ammonia to be in the range of 6.5 to 7.0, and the stirring was continued at room temperature (25° C.) for 1.5 hours to form a rare earth-containing precipitate slurry.

(53) (3) The precipitate slurry formed in step (2) was added to the molecular sieve slurry obtained in step (1), and stirred at room temperature (25° C.) for 15 minutes. The mixed slurry was dried at 250° C. to obtain the comparative molecular sieve DZ-5.

(54) 600 g (on dry basis) of molecular sieve DZ-5 was added to 1.2 L of deionized water, and the molecular sieve slurry DZ-5J was obtained after sand milling. 1054 g of kaolin (ignition loss: 14.6%), 587 g of pseudo-boehmite, and 2.2 L of water were mixed and slurried. 60 mL of hydrochloric acid was added and stirred for 1 hour. Then the molecular sieve slurry DZ-5J was added and stirred for 15 minutes. 515 g of aluminum sol (containing 19.4 wt % of alumina) was added and stirring was continued for 30 minutes to form a gel. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the comparative catalyst DC-5 containing the comparative molecular sieve DZ-5.

Comparative Example 7

(55) 798 g (on dry basis) of NH.sub.4Y molecular sieve were mixed with water according to the weight ratio of molecular sieve (on dry basis): water=1:5 and form a slurry. 0.6 L of deionized water was added therein and the resultant was stirred at a temperature of 35° C. for 70 minutes to obtain the comparative molecular sieve DZ-6 slurry. The comparative molecular sieve DZ-6 slurry was spray-dried to obtain the comparative molecular sieve DZ-6.

(56) 1030 g of kaolin (ignition loss: 14.6%), 440 g of pseudo-boehmite, 120 g of boehmite, and 2.2 L of water were mixed and slurried. 33 mL of hydrochloric acid was added and stirred for 1 hour. Then 600 g (on dry basis) of the molecular sieve DZ-6 slurry was added and stirred for 15 minutes. 619 g of aluminum sol (containing 19.4 wt % of alumina) was added and the stirring was continued for 30 minutes to form a gel. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the comparative catalyst DC-6 containing the comparative molecular sieve DZ-6.

Comparative Example 8

(57) (1) 798 g (on dry basis) of NH.sub.4Y molecular sieve were mixed with water according to the weight ratio of molecular sieve (on dry basis): water=1:3.5 to form a slurry.

(58) (2) 70 g of diammonium phosphate, 64 g of cerium nitrate were added to 0.4 L of deionized water and stirred at a temperature of 15° C. for 30 minutes to form a rare earth-containing precipitate slurry.

(59) (3) The precipitate slurry formed in step (2) was added to the molecular sieve slurry obtained in step (1), and stirred at a temperature of 15° C. for 25 minutes. The resultant was spray-dried, and the obtained molecular sieve was hydrothermally calcined in a calcination furnace under 100% steam atmosphere at a temperature of 550° C. for a calcination time of 2.5 hours to obtain the comparative molecular sieve DZ-7.

(60) 600 g (on dry basis) of molecular sieve DZ-7 was added to 1.2 L of deionized water, after sanding treatment to obtain the molecular sieve slurry DZ-7J. 738 g of kaolin (ignition loss: 14.6%), 220 g of pseudo-boehmite, 1.5 L of water were mixed and slurried. 19 mL of hydrochloric acid was added and stirred for 1 hour. Then the molecular sieve slurry DZ-7J was added and stirred for 25 minutes, then 619 g of aluminum sol (containing 19.4 wt % of alumina) was added and the stirring was continued for 30 minutes to form a gel. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the comparative catalyst DC-7 containing the comparative molecular sieve DZ-7.

Comparative Example 9

(61) According to a method for increasing rare earth content of the ultrastable Y-type zeolite disclosed in Chinese patent CN200510114495.1, 798 g (on dry basis) of NH.sub.4Y molecular sieve was calcined under 100% steam atmosphere at 600° C. for 1.5 hours to obtain an ultrastable Y molecular sieve. The ultrastable Y molecular sieve were mixed with water according to the weight ratio of molecular sieve (on dry basis): water=1:5 to form a slurry, 40 g of ammonium citrate was added therein and stirred at 35° C. for 1 hour, then the resultant was washed, filtered and the filter cake was removed. The filter cake was mixed according to the weight ratio of molecular sieve (on dry basis):water=1:5, stirred and then added with 277 mL of rare earth nitrate. And the stirring was continued for 1 hour at 35° C., and the resultant was filtered and dried to obtain the comparative molecular sieve DZ-8.

(62) 600 g (on dry basis) of molecular sieve DZ-8 was added to 1.5 L of deionized water, and the molecular sieve slurry DZ-8J was obtained after sand milling. 1030 g of kaolin (ignition loss: 14.6%), 440 g of pseudo-boehmite, 120 g of boehmite, and 2.2 L of water were mixed and slurried. 50 mL of hydrochloric acid was added and stirred for 1 hour. Then the molecular sieve slurry DZ-8J was added and stirred for 15 minutes, then 619 g of aluminum sol (containing 19.4 wt % of alumina) was added and the stirring was continued for 30 minutes to form a gel. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the comparative catalyst DC-8 containing the comparative molecular sieve DZ-8.

Comparative Example 10

(63) According to a method for preparing a novel rare earth ultrastable Y molecular sieve containing a vanadium-resistant component for catalytic cracking of heavy oil disclosed by Chinese Patent No. CN02103909.7, 798 g (on dry basis) of NH.sub.4Y molecular sieve were mixed with water according to the weight ratio of molecular sieve (on dry basis): water=1:5 to form a slurry, 64 g of ammonium oxalate was added and stirred at a temperature of 25° C. for 0.5 hour. Then 69.2 mL of rare earth nitrate was added and further stirred sufficiently for 15 minutes. The resultant was filtered and washed with water, and the obtained molecular sieve was hydrothermally calcined in a calcination furnace under 100% steam atmosphere at a temperature of 650° C. for a calcination time of 2 hours to obtain the comparative molecular sieve DZ-9.

(64) 500 g (on dry basis) of molecular sieve DZ-9 was added to 1.0 L of deionized water, and the molecular sieve slurry DZ-9J was obtained after sand milling. 867 g of kaolin (ignition loss: 14.6%), 587 g of pseudo-boehmite, 222 g of silica, and 2.0 L of water were mixed and slurried. 50 mL of hydrochloric acid was added and stirred for 0.5 hour. Then the molecular sieve slurry DZ-9J was added and stirred for 25 minutes, then 870 g of aluminum sol (containing 19.4 wt % of alumina) was added and the stirring was continued for 30 minutes to form a gel. After homogenization, spray-drying and molding, calcining, washing with water and drying were carried out to obtain the comparative catalyst DC-9 containing the comparative molecular sieve DZ-9.

(65) Physical and chemical properties of the molecular sieves Z-1 to Z-6 prepared in Examples 3 to 8 and the molecular sieves DZ-1 to DZ-9 prepared in Comparative Examples 2 to 10 were analyzed and tested. The results obtained are shown in Table 2:

(66) TABLE-US-00002 TABLE 2 Properties of the modified molecular sieves Rare earth Unit cell Sodium Yttrium oxide Crystallinity constant Items oxide wt % oxide wt % wt % wt % nm The molecular sieve Z-1 prepared by 1.56 5.81 — 68 2.455 Example 3 The molecular sieve Z-2 prepared by 1.20 — 7.06 48 2.458 Example 4 The molecular sieve Z-3 prepared by 1.24 — 8.00 45 2.456 Example 5 The molecular sieve Z-4 prepared by 1.53 — 7.98 44 2.454 Example 6 The molecular sieve Z-5 prepared by 1.52 — 3.06 52 2.452 Example 7 The molecular sieve Z-6 prepared by 1.59 — 1.99 56 2.450 Example 8 The molecular sieve DZ-1 prepared by 1.48 4.31 — 66 2.453 Comparative Example 2 The molecular sieve DZ-2 prepared by 1.44 5.79 — 68 2.457 Comparative Example 3 The molecular sieve DZ-3 prepared by 1.51 2.66 — 66 2.451 Comparative Example 4 The molecular sieve DZ-4 prepared by 1.18 — 4.02 50 2.456 Comparative Example 5 The molecular sieve DZ-5 prepared by 1.20 — 7.96 44 2.456 Comparative Example 6 The molecular sieve DZ-6 prepared by 1.64 — — 53 2.453 Comparative Example 7 The molecular sieve DZ-7 prepared by 1.51 — 2.98 52 2.452 Comparative Example 8 The molecular sieve DZ-8 prepared by 1.32 — 6.40 44 2.456 Comparative Example 9 The molecular sieve DZ-9 prepared by 1.48 — 1.81 54 2.450 Comparative Example 10

(67) The results in Table 2 show that, as compared with the molecular sieve DZ-1 prepared by Comparative Example 2, the sodium oxide content, degree of crystallinity, and unit cell constant of the molecular sieve Z-1 prepared by Example 3 are comparable to the comparative molecular sieve DZ-1, but the yttrium oxide content of the molecular sieve is higher than DZ-1 (1.50 wt % higher), indicating that the precipitating agent is indispensable in the preparation process of the molecular sieve of the present invention, which facilitates the precipitation of Group IIIB elements of the periodic table on the molecular sieve. In comparison with the molecular sieve Z-4 prepared by Example 6, the molecular sieve DZ-8 prepared by Comparative Example 9 has a low rare earth content in the molecular sieve and a low utilization of rare earth, since the filtration is carried out after the rare earth ion exchange, and there is a phenomenon that the rare earth that has not been exchanged to the molecular sieve is lost to the filtrate. The rare earth contained in the comparative molecular sieve DZ-8 enters the molecular sieve through ion exchange. These rare earth render the unit cells of the molecular sieve not easy to shrink in the hydrothermal calcination process, so its unit cell constant is higher than that of the molecular sieve Z-4 prepared by Example 6. In addition, in comparison with the molecular sieve Z-4 prepared by Example 6, the molecular sieve DZ-8 prepared by Comparative Example 9 involves the filtration treatment process of the molecular sieve, and the preparation process is relatively complicated. In comparison with the molecular sieve Z-6 prepared by Example 8, the molecular sieve DZ-9 prepared by Comparative Example 10 is also problematic in that the rare earth is lost and the molecular sieve preparation process is relatively complicated, due to the filtration after addition of rare earth to the molecular sieve. In the process of preparing molecular sieve Z-6 by Example 8, ammonium oxalate is mainly used as the precipitating agent for rare earth, but in the process of preparing molecular sieve DZ-9 by Comparative Example 10, ammonium oxalate firstly acts as a dealuminating agent to remove aluminum on the molecular sieve, and then reacts with the rare earth to precipitate the rare earth.

(68) In order to investigate the cracking activity and hydrothermal stability of the molecular sieves, the molecular sieves Z-1 to Z-6 prepared by Examples 3 to 8 and molecular sieves DZ-1 to DZ-9 prepared by Comparative Examples 2 to 10 were respectively used, 5% (in terms of alumina) of aluminum sol (containing 21.2 wt % of alumina) binder, 30% of the molecular sieve (on dry basis), 65% of kaolin (ignition loss: 18.6%, on dry basis) and a suitable amount of deionized water were mixed evenly, homogenized, dried, crushed and sieved. 20 to 40 mesh particles were selected to test the activity of the catalyst after 17 hours of steam aging respectively. The test results are shown in Table 3.

(69) In order to investigate the heavy metal contamination resistance ability of the molecular sieves, the above 20 to 40 mesh particles were impregnated with 5000 μg/g of V, and 3000 μg/g of Ni (relative to the catalyst particles) by incipient-wetness impregnation method. The vanadium and nickel-contaminated particles were treated under the condition of 800° C. and 100% of steam for 6h. The activity of vanadium and nickel-contaminated catalyst after 6 h steam aging was tested. The test results are shown in Table 3.

(70) In Table 3, the activity preservation rate R1 is used to characterize the ability of heavy metal contamination resistance of the molecular sieve. Definition: activity preservation rate R1=activity after vanadium and nickel contamination and 6 h steam aging/activity after 17 h steam aging×100%.

(71) TABLE-US-00003 TABLE 3 The activity and heavy metal resistance properties of the catalysts prepared by the modified molecular sieves Activity against activity Activity after vanadium and nickel preservation 17 h steam contamination after rate R1, Items aging, wt % 6 h steam aging, wt % wt % Catalyst containing the molecular sieve Z-1 68 57 84 prepared by Example 3 Catalyst containing the molecular sieve Z-2 60 51 85 prepared by Example 4 Catalyst containing the molecular sieve Z-3 63 52 82 prepared by Example 5 Catalyst containing the molecular sieve Z-4 58 51 88 prepared by Example 6 Catalyst containing the molecular sieve Z-5 48 39 81 prepared by Example 7 Catalyst containing the molecular sieve Z-6 44 38 86 prepared by Example 8 Catalyst containing the molecular sieve DZ-1 64 45 70 prepared by Comparative Example 2 Catalyst containing the molecular sieve DZ-2 67 51 76 prepared by Comparative Example 3 Catalyst containing the molecular sieve DZ-3 58 41 71 prepared by Comparative Example 4 Catalyst containing the molecular sieve DZ-4 51 35 69 prepared by Comparative Example 5 Catalyst containing the molecular sieve DZ-5 62 45 72 prepared by Comparative Example 6 Catalyst containing the molecular sieve DZ-6 38 27 71 prepared by Comparative Example 7 Catalyst containing the molecular sieve DZ-7 49 36 73 prepared by Comparative Example 8 Catalyst containing the molecular sieve DZ-8 60 47 78 prepared by Comparative Example 9 Catalyst containing the molecular sieve DZ-9 44 34 77 prepared by Comparative Example 10

(72) The results in Table 3 show that in comparison with the molecular sieve DZ-1 to DZ-9 prepared by Comparative Examples 2 to 10, for the catalysts prepared using the molecular sieves Z-1 to Z-6 prepared by Examples 3 to 8 of the present invention as the active component all have improved activity preservation rate R1, indicating that the modified molecular sieve of the present invention has a stronger vanadium and nickel contamination resistance.

(73) In comparison with the molecular sieve DZ-1 prepared by Comparative Example 2, the catalyst prepared by using the molecular sieve Z-1 prepared by Example 3 of the present invention as an active component has a significantly higher (by 4%) 17h activity than the comparative catalyst containing the molecular sieve prepared in Comparative Example 2. After the catalyst was contaminated by vanadium and nickel, the catalyst prepared by using the molecular sieve Z-1 prepared by Example 3 of the present invention as an active component has the activity after vanadium and nickel contamination and 6h steam aging was significantly higher by 12% than the comparative catalyst (the catalyst containing the molecular sieve DZ-1 prepared by Comparative Example 2), the activity preservation rate R1 increased by 14%, indicating that the molecular sieve containing the precipitated yttrium of the present invention has a higher activity stability and resistance to vanadium, nickel contamination. In comparison with the molecular sieve DZ-2 prepared by Comparative Example 3, the catalyst prepared by using the molecular sieve Z-1 prepared by Example 3 of the present invention as the active component has the 17 h activity comparable to that of the comparative catalyst containing the molecular sieve prepared in Comparative Example 3, but when the catalyst was contaminated with vanadium and nickel, the catalyst prepared by using the molecular sieve Z-1 prepared by Example 3 of the present invention as an active component has the activity after vanadium and nickel-contamination and 6 h steam aging activity significantly higher by 6% than that of the comparative catalyst (the catalyst containing the molecular sieve DZ-2 prepared by Comparative Example 3) by 6%, the activity preservation rate R1 increased by 8%, indicating that the molecular sieve containing precipitated yttrium prepared by using the organic complexing agent and the dispersant of the present invention has a higher ability of resistance to vanadium and nickel contamination. In comparison with the molecular sieve DZ-3 prepared by Comparative Example 4, the catalyst prepared by using the molecular sieve Z-1 prepared by Example 3 of the present invention as an active component has a 17 hours activity significantly higher (by 10%) than that of the comparative catalyst containing the molecular sieve prepared by Comparative Example 4; when the catalysts were contaminated with vanadium and nickel, the catalyst prepared by using the molecular sieve Z-1 prepared by Example 3 of the present invention as an active component has a vanadium and nickel-contaminated 6h steam aging activity significantly higher (by 16%) than that of the comparative catalyst (the catalyst containing the molecular sieve DZ-3 prepared by Comparative Example 4), the activity preservation rate R1 increased by 13%, indicating that the molecular sieve containing precipitated yttrium of the present invention has higher activity stability and resistance to vanadium and nickel contamination.

(74) In comparison with the molecular sieve DZ-4 prepared by Comparative Example 5, the catalyst prepared by using the molecular sieve Z-2 prepared by Example 4 of the present invention as an active component has a 17 hours activity significantly higher by 9% than that of the comparative catalyst containing the molecular sieve prepared by Comparative Example 5; after the catalysts were contaminated with vanadium and nickel, the catalyst prepared by using the molecular sieve Z-2 prepared by Example 4 of the present invention as an active component has the activity after vanadium and nickel contamination and 6h steam aging significantly higher by 16% than that of the comparative catalyst (the catalyst containing the molecular sieve DZ-4 prepared by Comparative Example 5), and the activity preservation rate R1 increased by 16%, indicating that the molecular sieve catalyst of the present invention containing the precipitated rare earth has higher activity stability and resistance to vanadium and nickel contamination.

(75) In comparison with the molecular sieve DZ-5 prepared by Comparative Example 6, the catalyst prepared by using the molecular sieve Z-3 prepared by Example 5 of the present invention as an active component has the 17h activity higher by 1% than that of the comparative catalyst containing the molecular sieve prepared by Comparative Example 6; after the catalysts were contaminated with vanadium and nickel, the catalyst prepared by using the molecular sieve Z-3 prepared by Example 5 of the present invention as an active component has the activity after vanadium and nickel-contamination and 6h steam aging significantly higher by 7% than that of the comparative catalyst (the catalyst containing the molecular sieve DZ-5 prepared by Comparative Example 6), and the activity preservation rate R1 increased by 10%, indicating that the molecular sieve catalyst prepared by using the dispersant and urea and the aqueous ammonia precipitating agent has higher activity stability and resistance to vanadium and nickel contamination than the molecular sieve catalyst prepared by the precipitation technique using aqueous ammonia only.

(76) In comparison with the molecular sieve DZ-6 prepared by Comparative Example 7, the catalyst prepared by using the molecular sieve Z-4 prepared by Example 6 of the present invention as an active component has a 17 h activity significantly higher by 20% than that of the comparative catalyst containing the molecular sieve prepared by Comparative Example 7; after the catalysts were contaminated with vanadium and nickel, the catalyst prepared by using the molecular sieve Z-4 prepared by Example 6 of the present invention as an active component has the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 24% than that of the comparative catalyst (the catalyst containing the molecular sieve DZ-6 prepared by Comparative Example 7), and the activity preservation rate R1 increased by 17%, indicating that the molecular sieve prepared by the present invention has higher activity stability and resistance to vanadium and nickel contamination than the molecular sieve without precipitated rare earth.

(77) In comparison with the molecular sieve DZ-7 prepared by Comparative Example 8, the catalyst prepared by using the molecular sieve Z-5 prepared by Example 7 of the present invention as an active component has a 17 h activity comparable to that of the comparative catalyst containing the molecular sieve prepared by Comparative Example 8; after the catalysts were contaminated with vanadium and nickel, the catalyst prepared by using the molecular sieve Z-5 prepared by Example 7 of the present invention as an active component has the activity after vanadium and nickel contamination and 6 h steam aging higher by 3% than that of the comparative catalyst (the catalyst containing the molecular sieve DZ-7 prepared by Comparative Example 8), the activity preservation rate R1 increased by 8%, indicating that the molecular sieve prepared by using the dispersant of the present invention has higher activity stability and resistance to vanadium and nickel contamination than the molecular sieve prepared by the precipitation technique using rare earth phosphate without using dispersant.

(78) In comparison with the molecular sieve DZ-8 prepared by Comparative Example 9, after the catalysts were contaminated with vanadium and nickel, the catalyst prepared by using the molecular sieve Z-4 prepared by Example 6 of the present invention as an active component has the activity after vanadium and nickel contamination and 6h steam aging significantly higher by 4% than that of the comparative catalyst (the catalyst containing the molecular sieve DZ-8 prepared by Comparative Example 9), and the activity preservation rate R1 increased by 10%, indicating that the molecular sieve prepared by the present invention has higher activity stability and resistance to vanadium and nickel contamination than the molecular sieve without precipitate of rare earth prepared by the method of Chinese patent CN200510114495.1 in the prior art.

(79) In comparison with the molecular sieve DZ-9 prepared by Comparative Example 10, after the catalysts were contaminated with vanadium and nickel, the catalyst prepared by using the molecular sieve Z-6 by Example 8 of the present invention as an active component has the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 4% than that of the comparative catalyst (the catalyst containing the molecular sieve DZ-9 prepared by Comparative Example 10), and the activity preservation rate R1 increased by 9%, indicating that the molecular sieve prepared by using the complexing agent and dispersant of the present invention has higher activity stability and resistance to vanadium and nickel contamination than the molecular sieve prepared by the method of Chinese patent CN02103909.7 in the prior art.

(80) In order to further investigate the cracking activity and the hydrothermal stability of the catalysts, the catalysts C-1 to C-6 prepared by Examples 3 to 8 and the comparative catalysts DC-1 to DC-9 prepared by Comparative Examples 2 to 10 were respectively tested for the activity of catalysts after 17 h steam aging. The test results are shown in Table 4.

(81) In order to investigate the ability of heavy metal contamination resistance of the catalysts, the catalysts C-1 to C-6 and the comparative catalysts DC-1 to DC-9 were respectively impregnated with 5000 μg/g of V, and 3000 μg/g of Ni (relative to the catalysts) by incipient-wetness impregnation method. The vanadium and nickel-contaminated catalysts were treated under the condition of 800° C. and 100% of steam for 6h, and tested for the activity of vanadium and nickel-contaminated catalyst after 6h steam aging was tested. The test results are shown in Table 4:

(82) TABLE-US-00004 TABLE 4 Activity and heavy metal resistance properties of the catalysts vanadium and nickel-contaminated 6 h water vapor aging 17 h water vapor aActivity after Activity aging aActivity vanadium and nickel preservation after 17 h steam contamination and 6 h rate R1, Items aging, wt % steam aging, wt % wt % catalyst C-1 prepared in Example 3 70 58 83 catalyst C-2 prepared in Example 4 63 54 86 catalyst C-3 prepared in Example 5 67 57 85 catalyst C-4 prepared in Example 6 61 54 88 catalyst C-5 prepared in Example 7 56 46 82 catalyst C-6 prepared in Example 8 44 39 89 comparative catalyst DC-1 67 49 73 prepared in Comparative Example 2 comparative catalyst DC-2 prepared 70 53 76 in Comparative Example 3 comparative catalyst DC-3 prepared 60 43 72 in Comparative Example 4 comparative catalyst DC-4 prepared 54 38 70 in Comparative Example 5 comparative catalyst DC-5 prepared 63 47 75 in Comparative Example 6 comparative catalyst DC-6 prepared 41 30 73 in Comparative Example 7 comparative catalyst DC-7 prepared 57 42 74 in Comparative Example 8 comparative catalyst DC-8 prepared 61 48 79 in Comparative Example 9 comparative catalyst DC-9 prepared 44 34 77 in Comparative Example 10

(83) In Table 4, the activity preservation rate R1 is used to characterize the ability of heavy metal contamination resistance of the catalysts. Definition: activity preservation rate R1=activity after vanadium and nickel contamination and 6 h steam aging/activity after 17 h steam aging×100%.

(84) The results in Table 4 show that in comparison with the molecular sieve DC-1 to DC-9 prepared by Comparative Examples 2 to 10, for the catalysts prepared using the molecular sieves C-1 to C-6 prepared by Examples 3 to 8 of the present invention all have improved activity preservation rate R1, indicating that the modified molecular sieve catalysts of the present invention has a higher resistance to vanadium and nickel contamination.

(85) In comparison with the catalyst DC-1 prepared by Comparative Example 2, the catalyst C-1 prepared by Example 3 of the present invention has a 17 h activity significantly higher 3% than that of the comparative catalyst DC-1 prepared by Comparative Example 2; after the catalysts were contaminated with vanadium and nickel, the catalyst C-1 prepared by Example 3 has the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 9% than that of the comparative catalyst (DC-1), and the activity preservation rate R1 increased by 10%, indicating that catalyst containing precipitated yttrium of the present invention has higher activity stability and resistance to vanadium and nickel contamination. In comparison with the catalyst DC-2 prepared by Comparative Example 3, the catalyst C-1 prepared by Example 3 of the present invention has a 17h activity comparable with that of the comparative catalyst DC-2; after the catalysts were contaminated with vanadium and nickel, the catalyst C-1 prepared by Example 3 has the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 5% than that of the comparative catalyst (DC-2), and the activity preservation rate R1 increased by 7%, indicating that catalyst containing precipitated yttrium prepared with the organic complexing agent and dispersant of the present invention has higher activity stability and resistance to vanadium and nickel contamination. In comparison with the catalyst DC-3 prepared by Comparative Example 4, the catalyst C-1 prepared by Example 3 of the present invention has a 17 h activity significantly higher by 10% than that of the comparative catalyst DC-3; after the catalysts were contaminated with vanadium and nickel, the catalyst C-1 prepared by Example 3 of the present invention has the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 15% than that of the comparative catalyst (DC-3), and the activity preservation rate R1 increased by 11%, indicating that the catalyst containing precipitated yttrium of the present invention has higher activity stability and resistance to vanadium and nickel contamination.

(86) In comparison with the catalyst DC-4 prepared by Comparative Example 5, the catalyst C-2 prepared by Example 4 of the present invention has a 17 h activity significantly higher by 9% than that of the comparative catalyst DC-4 prepared by Comparative Example 5; after the catalysts were contaminated with vanadium and nickel, the catalyst C-2 prepared by Example 4 of the present invention has the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 16% than that of the comparative catalyst (DC-4), and the activity preservation rate R1 increased by 16%, indicating that the catalyst containing the precipitated rare earth of the present invention has higher activity stability and resistance to vanadium and nickel contamination.

(87) In comparison with the catalyst DC-5 prepared by Comparative Example 6, the catalyst C-3 prepared by Example 5 of the present invention has a 17 h activity higher than that of the comparative catalyst DC-5 prepared by Comparative Example 6 by 4%; after the catalysts were contaminated with vanadium and nickel, the catalyst C-3 prepared by Example 5 of the present invention has the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 10% than that of the comparative catalyst (DC-5), and the activity preservation rate R1 increased by 10%, indicating that the catalyst prepared by using the dispersant and urea and the aqueous ammonia precipitating agent of the present invention has higher activity stability and resistance to vanadium and nickel contamination than the catalyst prepared by the precipitation technique using aqueous ammonia only.

(88) In comparison with the catalyst DC-6 prepared by Comparative Example 7, the catalyst C-4 prepared by Example 6 of the present invention has a 17 h activity significantly higher by 20% than that of the comparative catalyst DC-6 prepared by Comparative Example 7; after the catalysts were contaminated with vanadium and nickel, the catalyst C-4 prepared by Example 6 of the present invention has the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 24% than that of the comparative catalyst (DC-6), and the activity preservation rate R1 increased by 15%, indicating that the catalyst prepared by the present invention has higher activity stability and resistance to vanadium and nickel contamination than the catalyst without precipitated rare earth.

(89) In comparison with the catalyst DC-7 prepared by Comparative Example 8, activity of the catalyst C-5 prepared by Example 7 of the present invention has a 17 h activity comparable with that of the comparative catalyst DC-7; after the catalysts were contaminated with vanadium and nickel, the catalyst C-5 prepared by Example 7 of the present invention has the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 4% than that of the comparative catalyst (DC-7), and the activity preservation rate R1 increased by 8%, indicating that the catalyst prepared by using the dispersant of the present invention has higher activity stability and resistance to vanadium and nickel contamination than the catalyst prepared by the precipitation technique using rare earth phosphate without dispersant.

(90) In comparison with the catalyst DC-8 prepared by Comparative Example 9, after the catalysts were contaminated with vanadium and nickel, the catalyst C-4 prepared by Example 6 of the present invention has an activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 6% than that of the comparative catalyst (DC-8), and the activity preservation rate R1 increased by 9%, indicating that the catalyst prepared by the present invention has higher activity stability and resistance to vanadium and nickel contamination than the catalyst without precipitated rare earth prepared by the method of Chinese patent CN200510114495.1 in the prior art.

(91) In comparison with the catalyst DC-9 prepared by Comparative Example 10, after the catalysts were contaminated with vanadium and nickel, the catalyst C-6 prepared by Example 8 of the present invention the activity after vanadium and nickel contamination and 6 h steam aging significantly higher by 5% than that of the comparative catalyst (DC-9), and the activity preservation rate R1 increased by 12%, indicating that the catalyst prepared by using the complexing agent and dispersant of the present invention has higher activity stability and resistance to vanadium and nickel contamination than the catalyst prepared by the method of Chinese patent CN02103909.7 in the prior art.

(92) The present invention certainly may have various other Examples. Various corresponding changes and modifications may be made by those skilled in the art according to the present invention without departing from the spirit and essence of the present invention. However, these corresponding changes and modifications should fall within the protection scope of the claims of the present invention.