Mineral oils: processes and products – Chemical conversion of hydrocarbons – Cracking
Reexamination Certificate
1999-04-15
2001-04-10
Dunn, Tom (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Cracking
C208S121000, C208S122000, C502S060000, C502S064000, C502S065000, C502S068000, C502S079000
Reexamination Certificate
active
06214211
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a catalytic cracking catalyst composition useful for the catalytic cracking of heavy oils, and also to a catalytic cracking catalyst and a method of catalytically cracking heavy oils by using the catalytic cracking catalyst.
(b) Description of the Related Art
As crude oils are becoming heavier and the demand for gasoline and light fuel oils is increasing, the catalytic cracking of heavy oils is acquiring greater importance. In these circumstances, there is a demand for new catalytic cracking catalysts, which can crack heavy oils, such as desulfurized heavy oils, and give increased yields of gasoline and LCO fractions (light fuel fractions).
Cracking heavy oils, such as desulfurized heavy oils, into LCO fractions (light fuel fractions) or gasoline fractions requires rough cracking in macro pores (large pores) followed by more efficient cracking in meso pores (medium pores: 40-400 Å).
When a catalyst poor in meso pores is used, heavy oil fractions resulting from the primary cracking cannot penetrate into the area abounding cracking active sites, but stay in macro pores for a long time to form large amounts of coke and gas, failing to use the catalyst effectively. Increasing meso pores (medium pores: 40-400 Å), therefore, is required to crack efficiently the heavy oil fractions resulting from the primary cracking.
A means of increasing meso pores is the use of silica. Silica improves the diffusion of heavy oils, but hardly effects cracking into LCO and gasoline owing to the scarcity of cracking active sites. Another means is the use of silica alumina. Using silica.alumina alone, however, causes excessive cracking of heavy oils, increase the yields of gas and coke owing to a large quantity of strongly acidic cracking active sites. To produce LCO and FCC gasoline, it is therefore necessary to control meso pores and prevent excessive cracking by adding alumina, which is a relatively weak acid.
Japanese Patent Application Examined Publication No. 63-36291 (1988) discloses a hydrocarbon cracking composition containing spray-dried &ohgr; alumina. It, however, is unsuitable for the production of LCO and gasoline from heavy oils, such as desulfurized heavy oils because the objective pores are not meso pores but macro pores of 1000-3000 Å, and &khgr; alumina is not a boehmite gel alumina.
Japanese Patent Application Unexamined Publication No. 2-277548 (1990) discloses a catalytic cracking catalyst containing bayerite and/or &eegr; alumina, but does not mention meso pores. Further, bayerite and &eegr; alumina transfer to &thgr; alumina having a decreased surface area at high temperatures in the regenerators of residual oil fluidized catalytic cracking apparatuses for treating heavy oils, such as desulfurized heavy oils, to decrease the yields of LCO and gasoline fractions.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a catalytic cracking catalyst, which is useful for the catalytic cracking of heavy oils, such as desulfurized heavy oils, and affords high yields of gasoline and LCO and low yields of coke and gas.
Another object of the present invention is to provide a method of catalytic cracking heavy oils by using the catalytic cracking catalyst, which affords high yields of gasoline and LCO and low yields of coke and gas.
We have studied to solve the above problems and have found that high yields of gasoline and LCO and low yields of coke and gas can be afforded by cracking heavy oils by using a catalytic cracking catalyst produced from a catalytic cracking catalyst composition containing spherical boehmite gel alumina. We have completed the present invention on the basis of the finding.
That is, the present invention provides a catalytic cracking catalyst composition comprising (a) a spherical boehmite gel alumina, (b) a zeolite, (c) a clay mineral and (d) a binder.
The present invention further provides a catalytic cracking catalyst produced by spray-drying a slurry containing the catalytic cracking catalyst composition to obtain a spherical catalyst, and calcining the spherical catalyst.
The present invention further provides a method of catalytically cracking a heavy oil, which comprises catalytically cracking a heavy oil in the presence of the catalytic cracking catalyst.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The (a) spherical boehmite gel alumina contained in the catalytic cracking catalyst composition of the present invention is preferably produced by spray-drying a slurry of boehmite gel. For example, to produce the spherical boehmite gel alumina, first, alumina gel is precipitated by the neutralization reaction of an aqueous aluminum sulfate solution with aqueous ammonia, or of an aqueous sodium aluminate solution with a mineral acid, such as sulfuric acid or nitric acid, or of an aqueous aluminum sulfate solution with an aqueous sodium aluminate solution. The alumina gel is filtered and washed to remove sodium ion and sulfuric aci ion, to obtain alumina gel (boehmite gel) cake. Ion-exchanged water is added to the alumina gel cake to form a slurry of a solid content of 5-30 wt %, which is then spray-dried at a temperature of 100-250° C. to give spherical boehmite gel alumina. Examples of commercially available, spherical boehmite gel alumina include VERSAL 150, VERSAL 250, VERSAL 450 and VERSAL 900 (trade name).
The spherical boehmite gel alumina produced by spray-drying a slurry of boehmite gel preferably has a particle size of 0.2-150 &mgr;, more preferably 0.2-80 &mgr;m. The spherical boehmite gel alumina preferably has a single pore size peak in the range of 50-300 Å.
Preferred examples of the (b) zeolite contained in the catalytic cracking catalyst composition of the present invention include USY-zeolite, REY-zeolite which is an ion-exchanging product of NaY-zeolite with a rare earth element, and REUSY-zeolite obtainable by steaming REY-zeolite. The zeolite preferably has a specific surface area of 300-1,000 m
2
/g, more preferably 400-900 m
2
/g.
Preferred examples of the (c) clay mineral contained in the catalytic cracking catalyst composition of the present invention include kaolin and bentonite.
Preferred examples of the (d) binder contained in the catalytic cracking catalyst composition of the present invention include silica sol, alumina sol and silica.alumina sol.
The catalytic cracking catalyst composition of the present invention may contain silica.alumina when necessary. The ratio of silica/alumina in the silica.alumina is preferably 5/95 to 80/20 (wt/wt), more preferably 10/90 to 70/30 (wt/wt). Silica.alumina with higher silica ratios cannot have pores of large size in the product catalyst, or may broaden the pore size distribution of the product catalyst, inhibiting heavy oils from penetrating into pores.
A particular example of the preparation of silica.alumina is described hereinafter. JIS No. 3 water glass (SiO
2
content: 28 wt %) is diluted with ion-exchanged water to prepare an aqueous solution containing 4.0-12.0 wt % of SiO
2
. Aluminum sulfate 14 hydrate is diluted with ion-exchanged water to prepare an aqueous solution containing 4.0-12.0 wt % of aluminum sulfate. The same amounts of the aqueous water glass solution and the aqueous aluminum sulfate solution are added alternately to ion-exchanged water 0 to 10 times. When the aqueous water glass solution is added, the solution mixture is adjusted to pH 10 or higher. Basic agents, such as ammonia or sodium hydroxide, may be added to adjust the pH when necessary. When the aqueous aluminum sulfate solution is added, the solution mixture is adjusted to pH 4-8. Acidic or basic agents may be added to adjust the pH when necessary.
After the reaction, precipitate is filtered, and the residue on the filter is dispersed in an aqueous ammonium nitrate solution, subsequently in ion-exchanged water, and is filtered again to remove residual sodium. After the procedure is repeated 3 to 6 times, the resulting filter cake is washed with ion-exchanged water. When used as a materi
Antonelli Terry Stout & Kraus LLP
Dunn Tom
Idemitsu Kosan Co. Ltd
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