Catalytic cracking catalyst for high-efficiency conversion of heavy oil and preparation method thereof

Abstract

The present invention provides a catalytic cracking catalyst for heavy oil and preparation methods thereof. The catalyst comprises 2 to 50% by weight of a phosphorus-containing ultrastable rare earth Y-type molecular sieve, 0.5 to 30% by weight of one or more other molecular sieves, 0.5 to 70% by weight of clay, 1.0 to 65% by weight of high-temperature-resistant inorganic oxides, and 0.01 to 12.5% by weight of a rare earth oxide. The phosphorus-containing ultra-stable rare earth Y-type molecular sieve uses a NaY molecular sieve as a raw material. The raw material is subjected to a rare-earth exchange and a dispersing pre-exchange; the molecular sieve slurry is then filtered, washed with water and subjected to a first calcination to obtain a rare earth sodium Y molecular sieve which has been subjected to such first-exchange first-calcination, wherein the steps of rare earth exchange and dispersing pre-exchange are not restricted in sequence; and then the rare earth sodium Y molecular sieve which has been subjected to one-exchange one-calcination is subjected to second exchange and second calcination including ammonium exchange and a phosphorus modification, wherein the steps of the ammonium exchange and the phosphorus modification are not restricted in sequence. The steps of the ammonium exchange and the phosphorus modification can be conducted continuously or non-continuously, the second calcination is conducted after the ammonium exchange for reducing sodium, the phosphorus modification can be conducted before or after the second calcination. The catalyst provided by the invention has the characteristics of high heavy oil conversion capacity, high total liquid yield, and high yield of light oil.

Claims

1. A catalytic cracking catalyst for heavy oil, characterized in that the catalyst composition comprises 2% to 50% by weight of a phosphorus-containing ultrastable rare earth Y-type molecular sieve, 0.5% to 30% by weight of one or more other molecular sieves, 0.5% to 70% by weight of clay, 1.0% to 65% by weight of high-temperature resistant inorganic oxides, and 0.01% to 12.5% by weight of rare earth oxide; wherein the phosphorus-containing ultrastable rare earth Y-type molecular sieve comprises 1% to 20% by weight of rare earth oxide, not more than 1.2% by weight of sodium oxide, and 0.1% to 5% by weight of phosphorus in terms of P, and has a crystallinity of 51% to 69%, and a lattice parameter of 2.449 nm to 2.469 nm; wherein the phosphorus-containing ultrastable rare earth Y-type molecular sieve is prepared by a process comprising, (a) treating a NaY-type molecular sieve to a rare-earth exchange, a dispersing pre-exchange, and a first calcination to afford a one-exchanged one-calcinated rare earth sodium Y-type molecular sieve, wherein the rare-earth exchange and the dispersing pre-exchange are carried out in an unlimited sequence, and are carried out consecutively without a calcination process therebetween; and subjecting the one-exchanged one-calcinated rare earth sodium Y-type molecular sieve to an ammonium salt exchange, a phosphorus modification and a second calcination to obtain a phosphorous-containing ultrastable rare earth Y-type molecular sieve, wherein the ammonium salt exchange and the phosphorus modification are carried out in an unlimited sequence, and the second calcination is performed after the ammonium salt exchange; and (b) mixing the phosphorus-containing ultrastable rare earth Y-type molecular sieve, clay, and a precursor of a high-temperature resistant inorganic oxide to obtain a mixture, and homogenizing, spraying, and calcinating the mixture to obtain the catalyst cracking catalyst, wherein a dispersing agent in the dispersing pre-exchange process is any one or more selected from sesbania powder, boric acid, urea, ethanol, polyacrylamide, acetic acid, oxalic acid, adipic acid, formic acid, hydrochloric acid, nitric acid, citric acid, salicylic acid, tartaric acid, benzoic acid, and starch; and wherein no ammonium salt is used in the rare earth exchange or the dispersing pre-exchange.

2. The catalytic cracking catalyst for heavy oil according to claim 1, wherein the dispersing pre-exchange comprises adding the dispersing agent in an amount of 0.2% to 5% by weight, an exchange temperature is 60 C. to 95 C., and an exchange duration is 0.1 to 1.5 h.

3. The catalytic cracking catalyst for heavy oil according to claim 1, wherein the one or more other molecular sieves are selected from one or more of Y-type zeolite or a modification thereof, L zeolite or a modification thereof, ZSM-5 zeolite or a modification thereof, zeolite or a modification thereof, aluminum phosphate zeolite or a modification thereof, and zeolite or a modification thereof, wherein the modification to the molecular sieves is selected from the group consisting of HY, USY, REY, REHY, REUSY, H-ZSM-5, and H.

4. The catalytic cracking catalyst for heavy oil according to claim 1, wherein the clay is selected from one or more of kaolin, halloysite, montmorillonite, sepiolite, and perlite.

5. The catalytic cracking catalyst for heavy oil according to claim 1, wherein the high-temperature-resistant inorganic oxide is selected from one or more of Al.sub.2O.sub.3, SiO.sub.2, SiO.sub.2Al.sub.2O.sub.3, and AlPO.sub.4.

6. A preparation method of the catalytic cracking catalyst for heavy oil comprising 2% to 50% by weight of a phosphorus-containing ultrastable rare earth Y-type molecular sieve, 0.5% to 30% by weight of one or more other molecular sieves, 0.5% to 70% by weight of clay, 1.0% to 65% by weight of high-temperature resistant inorganic oxides, and 0.01% to 12.5% by weight of rare earth oxide; wherein the phosphorus-containing ultrastable rare earth Y-type molecular sieve comprises 1% to 20% by weight of rare earth oxide, not more than 1.2% by weight of sodium oxide, and 0.1% to 5% by weight of phosphorus in terms of P, and has a crystallinity of 51% to 69%, and a lattice parameter of 2.449 nm to 2.469 nm, wherein the method comprises the steps of: (1) preparing a phosphorus-containing ultrastable rare earth Y-type molecular sieve from a NaY molecular sieve comprising a rare-earth exchange, a dispersing pre-exchange, and a first calcination to afford a one-exchanged one-calcinated rare earth sodium Y-type molecular sieve, wherein the rare-earth exchange and the dispersing pre-exchange are carried out in an unlimited sequence; and subjecting the one-exchanged one-calcinated rare earth sodium Y-type molecular sieve to an ammonium salt exchange, a phosphorus modification and a second calcination to obtain a phosphorous-containing ultrastable rare earth Y-type molecular sieve, wherein the ammonium salt exchange and the phosphorus modification are carried out in an unlimited sequence, and the second calcination is performed after the ammonium salt exchange; and (2) mixing the phosphorus-containing ultrastable rare earth Y-type molecular sieve, clay, and a precursor of a high-temperature resistant inorganic oxide to obtain a mixture, and homogenizing, spraying, and calcinating the mixture to obtain the catalyst cracking catalyst, wherein a dispersing agent in the dispersing pre-exchange process is any one or more selected from sesbania powder, boric acid, urea, ethanol, polyacrylamide, acetic acid, oxalic acid, adipic acid, formic acid, hydrochloric acid, nitric acid, citric acid, salicylic acid, tartaric acid, benzoic acid, and starch; and wherein no ammonium salt is used in the rare earth exchange or the dispersing pre-exchange.

7. The preparation method according to claim 6, wherein the rare-earth exchange comprises adding a rare earth compound, wherein the mass ratio of the rare earth oxide (RE.sub.2O.sub.3) equivalent of the rare earth compound to Y zeolite is 0.005 to 0.25, an exchange temperature of 0 to 100 C., an exchange pH of 2.5 to 6.0, and an exchange duration of 0.1 to 2 h.

8. The preparation method according to claim 7, wherein the mass ratio of RE.sub.2O.sub.3 to Y zeolite is 0.01 to 0.20, the exchange temperature is 60 C. to 95 C., the exchange pH is 3.5 to 5.5, and the exchange duration is 0.3 to 1.5 h.

9. The preparation method according to claim 6, wherein the phosphorus modification comprises adjusting the molecular sieve slurry to a concentration, in terms of a solid content, of 80 to 400 g/L, and adding 0.1% to 5% by weight of phosphorus-containing compound in terms of P for an exchange at an exchange temperature of 0 to 100 C. for an exchange duration of 0.1 to 1.5 h.

10. The preparation method according to claim 8, wherein the phosphorus-containing compound is any one or more selected from phosphoric acid, phosphorous acid, phosphoric anhydride, diammonium phosphate, monoammonium phosphate, triammonium phosphate, triammonium phosphite, monoammonium phosphite, and aluminum phosphate.

11. The preparation method according to claim 6, wherein the rare-earth exchange and the dispersing pre-exchange independently comprises a tank-type exchange, belt-type exchange, filter cake exchange, and combinations thereof.

12. The preparation method according to claim 6, wherein the rare-earth exchange and the dispersing pre-exchange are multiple exchanges.

13. The preparation method according to claim 6, wherein the first calcination is carried out at 350 C. to 700 C. under 0 to 100% steam for 0.3 to 3.5 h.

14. The preparation method according to claim 6, wherein step (1) comprises treating a slurry of the one-exchanged one-calcinated rare earth sodium Y-type molecular sieve to a phosphorus modification exchange first, filtering to obtain a filter cake therefrom; mixing the filter cake with an ammonium salt solution to undergo a filter cake exchange, and calcinating the filter cake.

15. The preparation method according to claim 6, wherein step (1) comprises, treating a slurry of the one-exchanged one-calcinated rare earth sodium Y-type molecular sieve to a phosphorus modification exchange first, mixing with an ammonium salt solution to undergo an exchange, filtering to obtain a filter cake therefrom; and calcinating the filter cake.

16. The preparation method according to claim 6, wherein step (1) comprises, treating a slurry of the one-exchanged one-calcinated rare earth sodium Y-type molecular sieve to an ammonium salt exchange first, filtering to obtain a filter cake therefrom; mixing the filter cake with a phosphorus modification solution to undergo a filter cake exchange, and calcinating the filter cake.

17. The preparation method according to claim 6, wherein step (1) comprises, treating a slurry of the one-exchanged one-calcinated rare earth sodium Y molecular sieve to an ammonium salt exchange first, mixing with a phosphorus modification solution to undergo an exchange; filtering to obtain a filter cake; and calcinating the filter cake.

18. The preparation method according to claim 6, wherein step (1) comprises, treating a slurry of the one-exchanged one-calcinated rare earth sodium Y-type molecular sieve to an ammonium salt exchange first, filtering to obtain a first filter cake; calcinating the first filter cake; mixing the filter cake with a phosphorus modification solution to undergo an exchange; filtering to obtain a second filter cake; and calcinating the second filter cake.

19. The preparation method of the catalyst according to claim 6, wherein the calcination in step (2) is carried out at 200 C. to 700 C. for a duration of 0.05 to 4 hours.

20. The preparation method of the catalyst according to claim 6, wherein the precursor of the high-temperature-resistant inorganic oxide in step (2) is one or more selected from silica-alumina gel, silica sol, alumina sol, silica-alumina composite sol, and pseudoboehmite.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(1) The examples below are used to further explain the features of the present invention but do not limit the scope of the present invention.

(2) I. Method for Analysis and Evaluation Used in Examples

(3) 1. Lattice parameter (a.sub.0): X-ray diffraction.

(4) 2. Crystallinity (C/C.sub.0): X-ray diffraction.

(5) 3. Silica-to-alumina ratio: X-ray diffraction.

(6) 4. Na.sub.2O content: flame photometry.

(7) 5. RE.sub.2O.sub.3 content: colorimetry.

(8) 5. P content: spectrophotometry

(9) 7. Microreactor activity: samples were pretreated at 800 C. under 100% steam for 4 hours. The raw material for the reaction was Dagang light diesel, the reaction temperature was 460 C., the reaction duration was 70 seconds, the catalyst load was 5.0 g, the catalyst/oil ratio was 3.2, and the overall conversion percentage was taken as the microreactor activity.

(10) 8. ACE heavy oil microreactor: the reaction temperature was 530 C., the catalyst/oil ratio was 5, and the raw oil was Xinjiang oil blended with 30% vacuum residual oil.

(11) II. Specification of Raw Materials Used in Examples

(12) 1. NaY molecular sieves: NaY-1 (the silica/alumina ratio: 4.8, crystallinity: 92%), NaY-2 (the silica/alumina ratio: 4.1, crystallinity: 83%), manufactured by Lanzhou Petrochemical Company Catalyst Plant.

(13) 2. Ultrastable one-exchanged one-calcinated molecular sieve samples: crystallinity being 60%, sodium oxide being 4.3 m %, manufactured by Lanzhou Petrochemical Company, Catalyst Plant.

(14) 3. Rare earth solutions: rare earth chloride (rare earth oxide: 277.5 g/L), rare earth nitrate (rare earth oxide: 252 g/L), both of which are industrial grade and purchased from Lanzhou Petrochemical Company, Catalyst Plant.

(15) 4. Sesbania powder, boric acid, urea, ethanol, polyacrylamide, oxalic acid, adipic acid, acetic acid, formic acid, hydrochloric acid, nitric acid, citric acid, salicylic acid, tartaric acid, and starch, all of which are chemically pure; ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium oxalate, phosphoric acid, phosphorous acid, phosphoric anhydride, diammonium phosphate, monoammonium phosphate, triammonium phosphate, triammonium phosphite, monoammonium phosphite, and aluminum phosphate, all of which are industrial grade.

(16) 5. Pseudoboehmite (Loss on Ignition: 36.2%), kaolin (Loss on Ignition: 16.4%), halloysite (Loss on Ignition: 21.4%), montmorillonite (Loss on Ignition: 15.8%), perlite (Loss on Ignition: 17.6%), all of which are solid; alumina sol with an alumina content of 23.0 weight %; silica sol with a silica content of 24.5 weight %; all of which are industrial grade.

(17) 6. REY, REHY, USY, REUSY molecular sieves, all of which are industrial grade, manufactured by Lanzhou Petrochemical Company, Catalyst Plant; zeolite, industrial grade, manufacture by Fushun Petrochemical Corporation; H-ZSM-5, industrial grade, manufactured by Shanghai Fudan University.

EXAMPLE 1

(18) To a reaction kettle equipped with a heating mantle, 3000 g NaY-1 molecular sieve (dry basis) and a certain amount of deionized water were consecutively added and blended into a slurry having a solid content of 220 g/L, and 82 g boric acid and 105 g sesbania powder were then added thereto. The temperature was then raised to 85 C., and an exchange reaction was carried out for 0.5 h under stirring, followed by filtration and washing. The resultant filter cake was placed in a reaction kettle, and then 1.67 L rare earth chloride was added. The system pH was adjusted to 4.0, the temperature was elevated to 80 C., an exchange reaction was carried out for 0.3 h, and the resultant filter cake was dried by flash evaporation such that the moisture content thereof was 30% to 50%, and was finally calcinated under 70% water vapor at 670 C. for 1.0 h to produce a one-exchanged one-calcinated RE-Na Y. To a reaction kettle equipped with a heating mantle, 500 g of the one-exchanged one-calcinated ultrastable RE-Na Y-type molecular sieve (dry basis) and a certain amount of deionized water were added to prepare a slurry having a solid content of 120 g/L, to which 120 g ammonium sulfate was added. The system pH was adjusted to 4.2, the temperature was raised to 90 C., and an exchange reaction was carried out for 0.8 h, followed by filtration and washing. The filter cake was beaten, and 115 g diammonium phosphate was added. After thorough mixing, the mixture was calcinated under 80% steam at 560 C. for 2.5 h to produce an active component, a phosphorus-containing rare earth ultrastable Y-type molecular sieve in accordance with the present invention, designated as Modified Molecular Sieve A-1.

(19) To a reaction kettle with water bath heating, 4.381 L water, 1062 g kaolin, 986 g alumina and 63.5 mL HCl were added and thoroughly mixed, and were stirred for 1 hour, followed by consecutive addition of 448 g Modified Molecular Sieve A-1, 63 g H-ZSM-5, and 755 g REUSY, then thoroughly mixed. 1500 g alumina sol was slowly added for gelation, and was then shaped by spraying. The resultant microspheres were calcinated at 400 C. for 0.5 hours. 2 kg calcinated microspheres were weighed, to which 15 kg deionized water was added to carry out washing at 60 C. for 15 min, and were filtered and dried to produce a cracking catalyst prepared in accordance with the present invention, designated as A.

EXAMPLE 2

(20) To a reaction kettle equipped with a heating mantle, 3000 g NaY-1 molecular sieve (dry basis) and a certain amount of deionized water were consecutively added and blended into a slurry having a solid content of 360 g/L, followed by addition of 0.82 L rare earth nitrate thereto. The system pH was adjusted to 3.3, the temperature was raised to 80 C., and an exchange reaction was carried out for 1.5 h, followed by filtration and washing. The resultant filter cake was placed in a reaction kettle, to which 202 g polyacrylamide and 30 g salicylic acid were then added. The temperature was then elevated to 78 C. for a dispersing exchange, and the exchange reaction was carried out for 0.5 h under stirring. The resultant filter cake was dried by flash evaporation such that the moisture content thereof was 30% to 50%, and was finally calcinated under 30% steam at 630 C. for 1.8 h to produce a one-exchanged one-calcinated RE-Na Y. To a reaction kettle equipped with a heating mantle, 500 g of the one-exchanged one-calcinated ultrastable RE-Na Y-type molecular sieve (dry basis) and deionized water were added to prepare a slurry having a solid content of 370 g/L, to which 200 g ammonium sulfate was added. The system pH was adjusted to 3.6, the temperature was raised to 90 C., and an exchange reaction was carried out for 1.2 h. Then 64 g diammonium phosphate was added, the system pH was adjusted to 3.6, the temperature was raised to 90 C., and an exchange reaction was carried out for 1.2 h, followed by filtration and washing. The filler cake was calcinated under 20% steam at 600 C. for 0.5 h, followed by filtration and washing. The filler cake was calcinated under 20% steam at 600 C. for 0.5 h, to produce an active component, a phosphorus-containing rare earth ultrastable Y-type molecular sieve according to the present invention, designated as Modified Molecular Sieve B-1.

(21) To a reaction kettle with water bath heating, 4.620 L water, 1024 g kaolin, 971 g pseudoboehmite and 90.8 mL HCl were added and thoroughly mixed, and were stirred for 1 hour, followed by consecutive addition of 338 g Modified Molecular Sieve B-1, 129 g zeolite, and 806 g REHY, then thoroughly mixed. 1304 g alumina sol was slowly added for gelation, and was then shaped by spraying. The resultant microspheres were calcinated at 400 C. for 1.0 h. 2 kg calcinated microspheres were weighed, to which 20 kg deionized water was added and stirred uniformly, followed by washing at 35 C. for 40 min, and were filtered and dried to produce a cracking catalyst prepared by the present invention, designated as B.

EXAMPLE 3

(22) To a reaction kettle equipped with a heating mantle, 3000 g NaY-1 molecular sieve dry basis) and deionized water were consecutively added and blended into a slurry having a solid content of 150 g/L. 43 g HCl was then added thereto, and a reaction was carried out at 85 C. for 1 h. Then 1.68 L rare earth chloride was added, the system pH was adjusted to 3.7, the temperature was raised to 90 C., and an exchange reaction was carried out for 1 h. Subsequently, the molecular sieve slurry was filtered and subjected to a belt-type exchange with a dispersing agent under the following belt-type exchange conditions: 35 g oxalic acid was formulated into a solution of pH=3.4, the temperature was raised to 85 C., and the vacuum degree in the belt-type filter was 0.04. The resultant filter cake was then dried by flash evaporation such that the moisture content thereof was 30% to 50%, and was finally calcinated under 10% steam at 510 C. for 2.0 h to produce a one-exchanged one-calcinated ultrastable RE-Na Y. To a reaction kettle equipped with a heating mantle, 500 g of the one-exchanged one-calcinated ultrastable RE-Na Y-type molecular sieve (dry basis) and deionized water were added to prepare a slurry having a solid content of 145 g/L, to which 80 g ammonium sulfate was added. The system pH was adjusted to 3.5, the temperature was raised to 90 C., and an exchange reaction was carried out for 1.2 h, followed by filtration and washing. The filter cake was calcinated under 50% steam at 650 C. for 2 h, and then rebeaten, and 110 g ammonium dihydrogen phosphate was added and thoroughly mixed. An exchange reaction was carried out for 1 h, followed by filtration, washing and drying, so as to produce the active component of a phosphorus-containing rare earth ultra-stable Y molecular sieve according to the present invention, designated as Modified Molecular Sieve C-1.

(23) To a reaction kettle with water bath heating, 4.854 L water, 1125 g halloysite, 825 g pseudoboehmite and 51.4 mL HCl were added and thoroughly mixed, and were stirred for 1 hour, followed by consecutive addition of 456 g Modified Molecular Sieve C-1 and 903 g USY, then thoroughly mixed. 1224 g silica sol was slowly added for gelation, and was then shaped by spraying. The resultant microspheres were calcinated at 600 C. for 0.3 h. 2 kg calcinated microspheres were weighted, to which 15 kg deionized water was added, followed by washing at 80 C. for 30 min, and were filtered and dried to produce a cracking catalyst prepared in accordance with the present invention, designated as C.

EXAMPLE 4

(24) To a reaction kettle equipped with a heating mantle, 3000 g NaY-1 molecular sieve (dry basis) and a certain amount of deionized water were consecutively added and blended into a slurry having a solid content of 320 g/L. 30 g nitric acid was then added thereto. The temperature was then raised to 85 C., and an exchange reaction was carried out for 0.8 h under stirring, followed by addition of 0.95 L rare earth nitrate. The system pH was adjusted to 3.3, the temperature was elevated to 80 C., an exchange reaction was carried out for 1.8 h. Then 62 g starch was added, and a reaction was carried out at 80 C. for 0.5 h, followed by filtration and washing. The resultant filter cake was dried by flash evaporation such that the moisture content thereof was 30% to 50%, and was finally calcinated under 60% steam at 560 C. for 2 h to produce a one-exchanged one-calcinated RE-Na Y. To a reaction kettle equipped with a heating mantle, 500 g of the one-exchanged one-calcinated ultrastable RE-Na Y-type molecular sieve (dry basis) and deionized water were added to prepare a slurry having a solid content of 280 g/L, to which 130 g ammonium sulfate was added. The system pH was adjusted to 4.0, the temperature was raised to 90 C., and an exchange reaction was carried out for 0.5 h, followed by filtration and washing. Then 55 g diammonium phosphate was added, and a reaction was carried out for 2 h, followed by filtration and washing. The filter cake was calcinated under 50% steam at 650 C. for 2 h to produce an active component, a phosphorus-containing rare earth ultrastable Y-type molecular sieve in accordance with the present invention, designated as Modified Molecular Sieve D-1.

(25) To a reaction kettle with water bath heating, 4.577 L water, 1055 g kaolin, 983 g alumina and 63.5 ml HCl were added and thoroughly mixed, and were stirred for 1 hour, followed by consecutive addition of 892 g Modified Molecular Sieve D-1, 63 g ZSM-5 zeolite, 118 g USY and 188 g REY, then thoroughly mixed. 1500 g alumina sol was slowly added for gelation, and was then shaped by spraying. The resultant microspheres were calcinated at 400 C. for 0.5 h. 2 kg calcinated microspheres were weighed, to which 10 kg deionized water was added, followed by washing at 40 C. for 20 min, and were filtered and dried to produce a cracking catalyst prepared by the present invention, designated as D.

EXAMPLE 5

(26) To a reaction kettle equipped with a heating mantle, 3000 g NaY-1 molecular sieve (dry basis) and a certain amount of deionized water were consecutively added and blended into a slurry having a solid content of 350 g/L. 42 g citric acid and 28 g sesbania powder were then added thereto. The temperature was raised to 82 C., and an exchange reaction was carried out for 1.3 h under stirring. When the reaction was completed, 0.56 L rare earth nitrate was added, and an exchange reaction was carried out at 85 C. for 0.8 h. Subsequently, the molecular sieve slurry was filtered and subjected to a belt-type exchange under the following conditions: the temperature of the rare earth nitrate solution was raised to 88 C., the pH for exchange was 4.7, the rare earth nitrate was added in a RE.sub.2O.sub.3/Y zeolite ratio (by mass) of 0.04, and the vacuum degree in the belt-type filter was 0.03. The resultant filter cake was then dried by flash evaporation such that the moisture content thereof was 30% to 50%, and was finally calcinated under 80% steam at 530 C. for 1.5 h to produce a one-exchanged one-calcinated ultrastable RE-Na Y. To a reaction kettle equipped with a heating mantle, 500 g of the one-exchanged one-calcinated ultrastable RE-Na Y-type molecular sieve (dry basis) and deionized water were added to prepare a slurry having a solid content of 150 g/L, to which 100 g ammonium sulfate was added. The system pH was adjusted to 4.0, the temperature was raised to 90 C., and an exchange reaction was carried out for 1 h, followed by filtration and washing. The filter cake was calcinated under 60% steam at 620 C. for 2 h, then rebeaten, and 55 diammonium phosphate was added and thoroughly mixed, reacted at 90 C. for 1.5 h, and subjected to a calcination under 100% steam at 620 C. for 2 h, so as to produce an active component, a phosphorus-containing rare earth ultrastable Y-type molecular sieve in accordance with the present invention, designated as Modified Molecular Sieve E-1.

(27) To a reaction kettle with water bath heating, 6.5 L water, 995 g kaolin, 676 g alumina and 130 ml HCl were added and thoroughly mixed, and were stirred for 1 hour, followed by consecutive addition of 558 g Modified Molecular Sieve E-1, 19 g H-ZSM-5, and 830 g REUSY, then thoroughly mixed. 1359 g alumina sol was slowly added for gelation, and was then shaped by spraying. The resultant microspheres were calcinated at 500 C. for 0.6 h. 2 kg calcinated microspheres were weighed, to which 19 kg deionized water was added, followed by washing at 80 C. for 10 min, and were filtered and dried to produce a cracking catalyst prepared in accordance with the present invention, designated as E.

COMPARATIVE EXAMPLE 1

(28) A REUSY molecular sieve was prepared by the same method as that shown in Example 3, with the only exception that HCl and oxalic acid were not added. The resultant ultrastable rare earth Y-type molecular sieve is designated as F-1, and the resultant catalyst is designated as F.

COMPARATIVE EXAMPLE 2

(29) In this comparative example, the molecular sieve preparation method described in CN200510114495.1 was used in order to examine the reaction performance of this molecular sieve. The preparation process of the catalyst was the same as that in Example 5.

(30) 3000 g (dry basis) ultrastable one-exchanged one-calcinated molecular sieve sample (Na.sub.2O content: 1.4 weight %, RE.sub.2O.sub.3 content: 8.6 weight %, lattice parameter: 2.468 nm, relative crystallinity: 62%) produced hydrothermally by the Lanzhou Petrochemical Company, Catalyst Plant was added into a 3 L aqueous solution of 2N oxalic acid, and was stirred and thoroughly mixed. The temperature was raised to 90 to 100 C., and a reaction was carried out for 1 hour, followed by filtration and washing. The resultant filter cake was placed into 6 L deionized water, to which a 1.46 L solution of rare earth nitrate was added. The temperature was raised to 90 to 95 C., at which a reaction was carried out for 1 hour, followed by filtration and washing. The filter cake was oven dried at 120 C. to afford the molecular sieve sample of this comparative example, designated as H-1.

(31) To a reaction kettle with water bath heating, 6.5 L water, 995 g kaolin, 676 g alumina and 130 mL HCl were added and thoroughly mixed, and were stirred for 1 hour, followed by consecutive addition of 558 g Modified Molecular Sieve H-1, 19 g H-ZSM-5, and 830 g REUSY, then thoroughly mixed. 1359 g alumina sol was slowly added for gelation, and was then shaped by spraying. The resultant microspheres were calcinated at 500 C. for 0.6 h. 2 kg calcinated microspheres were weighed, to which 19 kg deionized water was added, followed by washing at 80 C. for 10 min, and were filtered and dried to produce a cracking catalyst of this comparative example, designated as H.

COMPARATIVE EXAMPLE 3

(32) A REUSY molecular sieve was prepared by the same method as that shown in Example 5, with the only exception that citric acid and sesbania powder were not added. The resultant ultrastable rare earth Y-type molecular sieve is designated as G-1, and the resultant catalyst is designated as G.

(33) The physical and chemical properties of the ultrastable rare earth Y-type molecular sieves obtained in accordance with the Examples and Comparative examples of the present invention are listed in Table 1. The analysis result demonstrates that the novel molecular sieves are characterized by good structural stability and a small particle size, as compared to the comparative examples.

(34) TABLE-US-00001 TABLE 1 Analysis of physical and chemical properties of molecular sieves Rare Earth Sodium Lattice Retention rate Collapse Molecular Oxide Phosphorus Oxide Parameter Relative of Relative Temp. Item Sieve No. m % m % m % nm Crystallinity % Crystallinity % C. Examples A-1 15.45 0.96 1.1 2.470 50 68.4 1019 B-1 6.89 0.58 0.94 2.472 54 71.1 1022 C-1 15.54 1.1 0.92 2.479 56 73.2 1018 D-1 7.98 0.54 1.05 2.473 51 72.3 1025 E-1 8.70 0.58 0.86 2.473 53 67.8 1017 Comparative F-1 6.78 1.05 1.1 2.464 52 51.2 998 Examples H-1 8.27 0.52 1.60 2.467 54 54.5 1002 G-1 8.70 0.58 0.82 2.468 52 56.3 1000

(35) The results for evaluation of the reaction performance of the catalysts prepared in Examples 1 to 5 and the Comparative Examples are listed in Table 2.

(36) TABLE-US-00002 TABLE 2 Evaluation results for the microreactor activity for ACE heavy oil Catalyst No. A B C D E F H G Molecular sieves A-1 B-1 C-1 D-1 E-1 F-1 H-1 G-1 Mass balance Dry gas 2.79 2.72 2.72 2.75 2.75 2.81 2.90 2.84 m % Liquified gas 22.48 22.52 22.44 22.42 22.42 23.26 23.59 23.22 Gasoline 53.41 52.76 53.26 53.57 53.57 52.92 52.84 53.22 Diesel 10.88 11.10 11.07 10.87 10.87 9.82 9.69 9.99 Heavy oil 3.97 4.67 4.32 4.15 4.15 4.31 3.94 4.11 Coke 6.46 6.22 6.18 6.23 6.23 6.88 7.05 6.61 Total 100 100 100 100 100 100 100 100 Conversion, m % 85.14 84.23 84.61 84.97 84.97 85.87 86.38 85.90 Total liquid yield, m % 86.78 86.38 86.78 86.87 86.87 86.00 86.11 86.44 Light oil yield, m % 64.29 63.86 64.33 64.45 64.45 62.75 62.52 63.21

(37) From the evaluation results about the microreactor activity for ACE heavy oil, it can be seen that the catalysts prepared by the methods according to the present invention have a superior heavy-oil-conversion capacity and coke selectivity, as compared to comparative catalysts, and also have a total liquid yield and a light oil yield both significantly higher than those of the comparative catalysts. Table 4 shows the evaluation results of catalyst B in a riser. As compared to catalyst G, using the catalyst of the present invention, the total liquid yield can be increased by 0.97%, and the light yield can be increased by 0.77%, while the gasoline properties in both cases are similar.

(38) TABLE-US-00003 TABLE 4 Evaluation results of a catalyst riser Comparative Inventive Catalysts catalyst G catalyst Mass Dry gas (H2-C2) 1.05 1.17 balance, Liquified gas (C3-C4) 17.95 18.16 % Gasoline (C5-204 C.) 50.20 50.44 Diesel (204 C.-350 C.) 16.58 17.12 Heavy oil (>350 C.) 6.54 5.55 Coke 7.36 7.30 Loss 0.30 0.27 Selectivity Conversion 76.87 77.33 % Light oil yield 66.79 67.56 Total liquid yield 84.74 85.71 Gasoline Normal alkanes 4.48 4.34 composition Isoalkanes 23.75 24.50 % Gasoline olefins 45.05 44.00 Cycloalkanes 9.97 10.01 Aromatic 16.75 17.15 hydrocarbons Gasoline MON 83.40 83.42 Gasoline RON 93.69 93.82

INDUSTRIAL APPLICABILITY

(39) One of the major active components of the novel catalyst for heavy oil according to the present invention is a phosphorus-containing rare earth ultrastable Y-type molecular sieve having high cracking activity stability. In the process of preparing this molecular sieve by rare earth modification, a dispersing agent is used to pre-disperse NaY molecular sieves, thereby lowering the degree of agglomeration of molecular sieve particles, allowing more molecular sieve surface to be in contact with rare earth ions, and reducing the obstruction to rare earth ion exchange. As a result, more rare earth ions are exchanged into molecular sieve cages and then migrate into sodalite cages in the subsequent steam calcination process, thereby the structural stability and activity stability of the molecular sieve are improved. As rare earth ions are located in sodalite cages, there are no rare earth ions present in super-cages or on the surface of the molecular sieve, thereby reducing the acidic intensity and density in these sites, lowering the coking probability at these active sites, and satisfactorily resolving the conflict between the heavy-oil conversion capacity and the coke selectivity of catalysts.