LU84006A1 - CATALYTIC COMPOSITION GETTING SULFUR OXIDES AGENT FOR CONTROLLING SOX EMISSIONS AND METHOD FOR CRACKING HYDROCARBON FEEDSTOCKS - Google Patents

Description

The present invention relates to catalysts which are used for the catalytic cracking of hydrocarbons, as well as to sulfur oxide net / absorbent agent compositions which can be used to control emissions of sulfur oxides.

More particularly, the present invention contemplates the preparation and use of catalytic cracking catalysts capable of reducing the amount of sulfur oxides (SOX) emitted to the atmosphere during regeneration of the catalyst, as well as very strong agents. SO control that can be used to Λ control SO emissions from a wide variety of Λ processes.

The cracking catalysts that are used.

15 to crack hydrocarbon feedstocks become relatively inactive due to deposits of carbonaceous materials on the catalyst. These carbonaceous deposits are commonly called coke. When the feedstock contains organic sulfur compounds, the coke on the catalyst contains sulfur. After the cracking step, the catalyst passes to an extraction zone where steam is used to remove, from the catalyst, the hydrocarbons which can be extracted.

The catalyst then passes to the regenerator where it is. “25 regenerated by burning coke in an oxygen-containing gas. This converts the carbon and hydrogen in the coke to carbon monoxide, carbon dioxide and water. The sulfur in coke is converted to sulfur oxides, SQ ^ and SO ^, i.e. SO ^.

In general, the greater the amount of sulfur in the feed, the greater the amount of sulfur in the coke. Likewise, the greater the amount of sulfur in the coke, the greater the amount of sulfur oxides in the flue gas leaving the regenerator. In general, the amount of S02 and SO-, that is to say S0Xj in the flue gas reaches about 250 to 2,500 parts per million by volume.

h- k 2 The prior art has suggested various methods for removing or preventing the release of SO to the atmosphere λ during combustion by oxidation, of sulfur-containing fuels / residues. Typically, the fluid catalytic cracking / combustion units were equipped with conventional scrubbers where the SOx components were removed from the flue gases by absorption / reaction with getter agents (sometimes called "SO ^ acceptors") * such as calcium oxide. In some cases, hydrocarbon feedstocks are pretreated (hydrotreated) to remove sulfur. It has been said that emissions of sulfur oxides from fluid catalytic cracking units can be controlled using a cracking catalyst in combination with a sulfur absorbing agent or oetter agent. It has also been said that these sulfur-reducing agents are more effective when used in the presence of oxidation catalysts.

Oxidation catalysts are commonly used in fluid catalytic cracking units to oxidize CO to CO ^ in the catalyst bed during the step of burning coke in the regenerator. The oxidation of CO to CO ^ in the catalyst bed brings many benefits. One of them is the reduction of CO emissions. Another is to avoid "post-combustion", that is, the oxidation of CO to CO 2 outside the catalyst bed, which results in loss of thermal energy and which damages the cyclones and flue gas outlet lines. The major benefit of using oxidation catalysts to oxidize CO to C0o 30 in the catalyst regenerator bed is that the heat released when CO is oxidized to CCV. This heat “c.

raises the temperature of the catalyst bed, thereby increasing the rate of combustion of the coke. This domes a lower level of residual carbon on the regenerated catalyst 35 (CRC). This, in turn, makes the regenerated catalyst more active for the cracking step. This increases the quantity of useful products obtained in the cracking unit 3 catalytic fluid.

In view of the fact that CO oxidation catalysts are commonly used in many fluid catalytic cracking units for economic reasons, SO 2 cetter agents. for use in fluid catalytic cracking units must be compatible and effective in the presence of oxidation catalysts *. Furthermore, the agents of SO to be used in fluid catalytic cracking units 10 must be effective under the real conditions which are seen in these units, such as temperatures of 427-538 ° C. and residence times of the catalyst. from 3 to 15 seconds in the reducing atmosphere of the reactor, temperatures of 427-538 ° C in the vapor atmosphere of the rectifier, temperatures of 593-760 ° C and residence times of the catalyst from 5 to 15 minutes in the oxidizing atmosphere of the regenerator. In addition, agents * c ~ tter from SO to

-* AT

used in fluid catalytic cracking units must be effective in the presence of materials present in these units, such as cracking catalysts of various compositions, oil feedstocks of various compositions and their cracked products and as ts on l 'indicated previously, the oxidation catalysts. - to oxidize CO to Οθ £.

In the following U.S. patents, the use of cracking catalysts containing various agents controlling carbon monoxide and sulfur emissions is disclosed.

3 542 670 30 3 699 037: 3 835 031 4 071 436 4 115 249 4 115 250 35 4 115 251 4 137 151 4 151 119 4 4 152 298 4 153 534 4 153 535 4 166 787 5 4 182 693 4 187 199 4 200 520 4 206 039 4 206 085: 10 4 221 677 4 238 317

As can be seen from the references noted above, the organic sulfur present during the regeneration of the cracking catalyst is finally oxidized to sulfur trioxide (SO 2) which reacts with a clearing agent to form a stable sulfate which is retained in the catalytic inventory of the fluid catalytic cracking unit.

The regenerated catalyst containing the sulfate compound is recycled to the cracking zone where the catalyst is mixed with an oil and vapor dispersing agent to effect the cracking reaction and the conversion of the oil into useful products (gasoline , light olefins, ex others).

,. * When the sulfate-containing catalyst is exposed to the reducing and hydrolysis conditions present during the cracking step and to the subsequent hydrolysis conditions present in the steam rectifier, | the sulfate is reduced and hydrolyzed to form hydrogen sulfide (^ S) and to restore or regenerate the agent. Hydrogen sulfide is recovered as a component of the cracked product stream. The agent çetter; 'is recycled to the regenerator to repeat the process.

By the use of catalysts containing suitable cleaning agents, it is revealed that the amount of sulfur oxides emitted by the regenerator can be considerably reduced.

5

However, it has been found that attempts to produce cracking SOX control catalysts which achieve a significant reduction in sulfur oxide emissions over long periods of time have generally been unsuccessful.

. Consequently, the subject of the present invention is a cracking catalytic composition making it possible to reduce efficiently and economically the emission of sulfur oxides T from fluid catalytic cracking units.

Λ0 The subject of the present invention is a cetter agent of sulfur oxides capable of removing the sulfur oxides over a long period of time during multiple getter / regeneration cycles.

Another subject of the present invention is an SO control additive which can be added to the catalytic inventory of a fluid catalytic cracking unit in amounts necessary to reduce the exhaust gas emissions from the oxide regenerator. sulfur to an acceptable level.

A further subject of the present invention is very efficient sulfur oxide getter agents which can advantageously be combined with conventional cracking catalyst compositions or used to control SO emissions from a wide variety of processes.

The invention will be better understood, and other objects, characteristics, details and advantages thereof will appear more clearly during the explanatory description which follows, given with reference to the appended schematic drawing given solely by way of example illustrating an embodiment of the invention and in which: - the single figure is a graphical representation of data illustrating the index of S0y on the axis 35 of the ordinates as a function of the content of on the abscissa axis, of SO giietteûrs agents according to the invention.

i '’i - * / In general, the present invention contemplates" 6 catalytic cracking catalyst compositions which contain a SO oxide getter agent

AT

lanthanum-alumina. On the other hand, the present invention contemplates an improved SO ket agent, which contains an alumina substrate (A ^ O ^) coated with a lanthanum oxide (La ^ Oz) in amounts producing roughly a theoretical monolayer of molecules on the j - surface of the alumina substrate. These getter agents can i! 'be effectively combined or included in compositions: particulate catalysts used for the catalytic cracking of hydrocarbons, or else getter agents can be used in any combustion process' which produces SOX components which must be selectively removed from the combustion products .

15 In particular, it was found that an officer

: particularly effective absorbent / getter of SO

AT

suitable for use with a catalytic cracking catalyst could be obtained by combining the solution of the soluble lanthanum salt with a porous alumina substrate in amounts distributing on the surface of the substrate j; in alumina, a layer of lanthanum oxide having about one molecule thick.

j · ‘In practice, we have found that the desired result is obtained with approximately 5 to 50% o by weight of! 25 La20 ^ combined with an alumina substrate having a surface area of the order of 45 to 450 m ^ / g; preferably there are about 12 to 30% by weight of La .-. O-, in combination with an alumina substrate having a surface area of; 2 in the range of 110 to 270 m / g; and better still there are about 30 2.0% by weight of La.-O ^ in combination with an alumina substrate i before a surface area of the order of

: P

; 180 m / g.

Suitable alumina substrates are available from many commercial sources, and include alumina hydrates, such as alpha-1 monohydrate; alumina, alpha-alumina trihycrate, _ beta-alumina monohydrate and this beta-alumina mrihydrate. The calcined versions of the above hydrates of alumina are also considered to be very suitable. These are gamma-alumina, chi-alumina, eta-alumina, kappa-alumina, delta-alumina, theta-alumina, alpha-5 alumina and their mixtures.

The lanthanum oxide component which is spread over the surface of the alumina can be obtained in the form of a commercial lanthanum salt such as nitrate or chloride or sulphate of lanthanum or alternatively, a mixed rare earth salt which contains other rare earth elements such as Nd, Ce, Pr and Sm can be used.

The rare earth component of a typical commercial solution of mixed rare earth salt containing lanthanum has the following approximate composition, expressed as oxides: 60% La ^ O ^, 20% 14%

CeOg, 5% Pr ^ O ^ and 1% Sn ^ O ^. It will be understood that in the case where a source of mixed rare earth salts is used, the quantity of the salts used must be sufficient to obtain the desired level of La 2 O 4 on the alumina substrate.

The amount of lanthanum oxide that is used in the preparation of the SO oetter agent according to

♦ A

the invention is preferably the amount which will form a monolayer of lanthanum oxide molecules on the surface of the alumina substrate. In the event that the quantity of lanthanum oxide, as specified above, is appreciably exceeded, that is to say that lanthanum oxide is formed in several layers or in bulk , this adversely affects the effectiveness of the getter agent 30 of SC). Furthermore, if insufficient lanthanum oxide is used, the effectiveness of the agent: getter is less than it should be.

While the precise mechanism is not fully understood, it is believed that the active species is a 35 Lao0 ~ molecule attached to the alumina surface in some sort of a La20 · ^ and Al ^ surface complex O ^ · This La ^ -93 surface complex on A1 ~ 0- is very reactive by combining 23 2 p i.

8 with sulfur oxides to force a thermally stable solid sulfate or sulfate type compound. Furthermore, this thermally stable or composite sulphate solid sulfate can easily be reduced-hydrolyzed to produce volatile hydrogen sulfide and restore or regenerate the original surface complex LagO ^ ευΓ ^ “2 ^ 3 * Sulfide hydrogen can be recovered as

V

component of the product stream. The restored or regenerated counting agent can be recycled to repeat steps i .10 of absorption and regeneration.

I To prepare the new getter agent for SO, -Λ.

the alumina substrate is uniformly and completely mixed with a certain amount of a lanthanum salt solution which will give the desired uniform dispersion of lanthanum oxide on the surface. Typically, the soluble lanthanum salt, preferably lanthanum nitrate, is dissolved in water to obtain a desired volume of solution which has the desired concentration of lanthanum salt. The alumina substrate is then impregnated, as uniformly as possible, with the lanthanum salt solution, to give the desired amount of lanthanum on the alumina. The impregnated alumina is then calcined at a temperature sufficient to decompose the lanthanum salt and fix the resulting lanthanum oxide uniformly on the surface of al und ne. While it is contemplated that calcination temperatures of up to 816 ° C may be used, the calcination temperatures in the range of 518 ° C have been found to be satisfactory.

In a preferred embodiment of the invention-30 tion, the alumina substrate to be impregnated has the form of this microspheroidal particles, with approximately 90γί particles having diameters in the range of dimensions which can be fluidized from 20 to lA3y6c ·· Advantageously, the getter agent prepared using these particles can be physically mixed with the fluid catalytic cracking catalyst in amounts of from about 0.5 to 60% by weight of the total ujposion.

9

In another embodiment of the invention, the alumina substrate to be impregnated has the form of particles which have an average size of less than 20 in diameter, and preferably less than 10 in diameter. The finished getter agent prepared using these fine particles can be incorporated into a cracking catalyst composition during the formation of the catalyst particles.

Typically, lanthanum impregnated alumina is. 10 added to an aqueous slurry of the components of the catalyst before shaping, that is to say spray drying, in the case of catalysts for fluid catalytic cracking.

In another embodiment of the invention, the alumina substrate to be impregnated has the form of particles 15 of a millimeter in diameter or more. The finished getter agent prepared using these particles can be used either in a fixed bed or in a moving bed, to reduce S0 emissions from a wide variety of processes.

Therefore, it can be seen that the present getter agent can be used as a separate additive which is added to the catalyst as a separate particulate component, or. well the getter agent can be combined with the catalyst during its preparation in order to obtain catalyst particles which contain the getter agent as an integral component. In addition, the getter agent can be used by itself to reduce the SO 2 emissions from a wide variety of processes.

.Λ.

Cracking catalysts which can advantageously be combined with the SO getter agent according to the invention are commercial compositions, and typically comprise crystalline zeolites in admixture with inorganic oxides as binders and clay. Typically, these catalysts contain on the order of 5 to 50% by weight of crystalline aluminosilicate zeolite in combination with a hydrogel or sol binder, silica-alumina or alumina, and optionally in the order of 10 to 80% by weight of clay. The zeolites typically used in the preparation of cracking catalysts are stabilized Y-type zeolites, the preparation of which is disclosed in US Pat. Nos. 3,293,193, 3,375,065, 3,402,996, 3,449,070 and 3 595 611. Preparation 5 of the catalyst compositions which can be used in the practice of the invention is typically disclosed in US Pat. Nos. 3,957,689, 3 S67,308, 3,912,611 and in the Canadian patent No. 967,135.

In the preferred practice of the invention, the geiter composition of the cracking catalyst will be used in combination with an oxidation catalyst of a noble metal such as platinum and / or palladium.

In another preferred practice of the invention, the SOX getter is combined with a cracking catalyst which comprises an aluminum sol, such as a solution of aluminum hydrochloride, a clay / zeolite composition bound as this is disclosed in Canadian Patent No. 967,136 in admixture with an oxidation catalyst containing particulate platinum to obtain a composition which contains 0.5 to 60% by weight of the gettor agent, 40 to 95% by weight cracking catalyst and 1 to 5 parts per million platinum.

In another preferred practice of the invention, the oetter agent 30 is combined with a T * -Λ catalyst.

! Cracking of zeolite which has a matrix essentially free of silica. Our catalysts are obtained in use. sant the process indicated in Canadian Patent No. 967 136 I by mixing together the following materials: 5 to 50% by weight of zeolite. 10 to 80% by weight of alumina hydrate 30 (dry base) and 5 to -0% by weight of a sol this aluminum hydrochloride ji (A120 ^), and water. The mixture was spray dried to obtain a finely subdivided composite catalyst which was calcined at a temperature of about 538 ° C. the net agent of S0 may be. 35 incorporated as a component of the dried porridge by | spraying instead of part of the alumina hydrate or the SO 2 getter agent can be physically mixed with the catalyst in an amount of the order of 0.5 to 60% by weight.

As noted above, the getter agent can be used in the form of a separate particulate additive which is physically mixed with a particulate catalyst or the oetter agent can be incorporated into the catalyst particle. mixing the additive with the components of the catalyst before shaping the catalyst.

In addition, it is contemplated that the getter agent can be used in any combustion / reaction process where it is desirable to collect or remove sulfur oxides from a product gas stream. Typically, the SOX getter agent can be used in a fluidized coal combustion process to remove SO formed Λ

15 during the combustion of coal. SO getter agent

Λ can then be removed from the combustion / reaction zone, periodically or continuously, to restore or regenerate the getter agent by subjecting it to a reduction-hydrolysis in the presence of hydrogen or of a mixture of gases reducing carbon monoxide -hydrogen (like synthetic gas) and HgO. Using this technique, the SO component in combustion products is, Λ.

selectively removed as a stable sulfate, and the sulfate is subsequently reduced-hydrolyzed to release 25 H ^ S and restore or regenerate the getter agent. The can be recovered using conventional adsorption techniques.

Having described the basic aspects of the present invention, the following examples are given to illustrate specific embodiments.

EXAMPLE 1

A lanthanum nitrate solution was prepared by dissolving 79.7 g of lanthanum nitrate, La (NOSILO, in a sufficient amount of water to give 100 ml of solution. 10 ml of this solution contains 3.0 g of lanthanum by expressing in the form of lanthanum oxide, / Ls20312! EXAMPLE 2

36.8 g (27 g on a dry basis) were impregnated with a marketed alpha-alumina monohydrate having a | mean particle size (APS) of 67 ^ / c, with 96% of the particles in the size range from 20 to 149 microns, of 10 ml of the solution described in Example 1. The impregnated alumina was heated at 338 ° C and maintained at 538 ° C for 30 minutes. The sample resulting from ►- La ^ O ^ / A ^ O ^ contained 10% by weight of EXAMPLE 3 'Alpha-alumina monohydrate of the type described in Example 2 was calcined air, for 1 hour at 482 ° C. 27 g of this calcined alumina were impregnated with 10 ml of the solution described in Example 1. The impregnated sample 15 was heated to 538 ° C and kept at 538 ° C for 30 minutes. The resulting sample contained 10% by weight of lanthanum oxide La ^ O ^.

EXAMPLE 4

The process of Example 3 was repeated, but calcining the alumina hydrate for 1 hour at 677 ° C before; impregnation with the lanthanum nitrate solution.

EXAMPLE 5

The process of Example 3 was repeated, but calcining the alumina hydrate for 1 hour at 899 ° 0 before impregnation with the lanthanum nitrate solution.

EXAMPLE 6

The process of Example 3 was repeated, but calcining the alumina hydrate for 1 hour at 1Q1G ° C before impregnation with the lanthanum nitrate solution.

EXAMPLE 7

The process of Example 3 was repeated, but calcining the alumina hydrate at 1066 ° C before impregnation with the lanthanum nitrate solution.

t 13 EXAMPLE 8

Alumina hydrate of the type described in Example 2 was calcined in air for 1 hour at 677 ° C. 5 ml of the solution described in Example 1 were mixed with 5 ml of water to give 10 ml of a solution having a lanthanuum concentration of 1.50 g of lanthanum, expressing in the form of La 2 O 4. 28.5 g of the calcined alumina were impregnated with the 10 ml of the solution. The impregnated sample was heated to 538 ° C and held at 538 ° C for 30 minutes. The resulting sample of La ^ O ^ / Al ^ O ^ contained 5% by weight of La ^ O- ,.

2 5 EXAMPLE 9

Alumina hydrate of the type described in Example 2 was calcined in air for 1 hour at 677 ° C. 24 g of this calcined alumina were impregnated with 10 ml of the solution described in Example 1. The impregnated sample was heated to 538 ° C and kept at 538 ° C for 30 minutes. After allowing to cool to room temperature, the impregnated and calcined sample received a second impregnation of 10 ml of the solution described in Example 1. After this second impregnation, the sample was heated to 538 ° C and maintained at 538 ° C for 30 minutes. . The resulting sample of LagO ^ / AlgO ^ contained 20% by weight of La20 ^.

25 EXAMPLE 1Q

A lanthanum nitrate solution was prepared by dissolving 99.8 g of La (NO,) v6EL0 in water to give 100 ml of solution. 8 ml of solution contains 3.0 g of lanthanum exorimated by La ~ 0 2 3 *

30 E ^ itrlB

Alumina hydrate was calcined in air for 1 hour at 677 ° C as in Example 9. 21 g of this calcined alumina were impregnated with 8 ml of the decrj solution, bone free iO. The original sample was heated to 538 ° C and held at 538 ° C for 30 minutes. After allowing it to cool to room temperature,; 1 * Lillon screen j.mpregne cs_iciné g received a second 14 impregnation with 8 ml of the solution described in Example 10 After this second impregnation, the sample was heated to 538 ° C and kept at 538 ° C for 30 minutes .

After allowing it to cool to room temperature, this doubly impregnated and calcined sample received a third impregnation with 8 ml of the solution described in Example 10. After this third impregnation, the sample was heated to 53 °. C and maintained at 538 ° C for 30 minutes. The resulting sample of ka20 ^ / Al20 ^ 10 contained 30% by weight of La20 ^.

EXAMPLE 12

The process of Example 11 was repeated but using 18.0 g of calcined alumina, and after the third impregnation and calcination, the sample received a fourth impregnation and calcination at 538 ° C. The resulting sample of La ^^ / Al ^ O ^ contained 40% by weight of La20 ^.

EXAMPLE 13

A solution of mixed rare earth nitrates was prepared by mixing 153.1 g of a commercially available solution of mixed rare earth nitrates with water to give 100 ml. 8 ml of the solution contained 3.0 g of rare earths mixed in the form of oxides. The rare earth component of this solution by expressing 25 by weight in the form of oxides had the following composition: 60% of La203, 20% of Nd ^, 14% of Ce02, 5% of Pr ^ O ^ and 1 % of Smo0,.

2 3 EXAMPLE 14

The process of Example 9 was repeated but with the impregnation carried out with 6 ml of the solution described in Example 13. The resulting sample contained 20% by weight of rare earth oxides mixed. 60% of these rare earth oxides were represented by lanthanum oxide, therefore the resulting sample contained 12% by weight of La20 ^.

EXAMPLE 15 / "The process of Example 11 was repeated, but while carrying out the impregnations with 8 ml of the solution described in Example 13. The resulting sample contained 30% by weight of mixed rare earth oxides, of which 60% were lanthanum oxide, The resulting sample 5 contained 18% by weight of La ^^.

EXAMPLE 16

A solution of mixed rare earth nitrates was prepared by mixing 152.8 g of a commercially available solution of rare earth nitrates mixed with 10 of water to give 100 ml. 10 ml of the solution contain 3.75 g of rare earths mixed by expressing through the oxides. The rare earth component of this solution, expressing as oxides to the following composition: 60% of La20 ^, 20% of Nd ^ O ^, 14% of CeO ^, 5% of PrgO ^ and 15 1% of Sm203 .

EXAMPLE 17

The process of Example 9 was repeated but carrying out the impregnations with 10 ml of the solution described in Example 16. The resulting sample contained 20 to 25% by weight of rare earth oxides mixed. 60% of these rare earth oxides were represented by lanthanum oxide, and therefore the resulting sample contained 15% by weight of La 2 O 3 · EXAMPLE 18 25 Fine alpha-alumina monohydrate was calcined with air for 1 hour at 677 ° C. This calcined alumina had an average particle size of 15 to 20 / CC. 2,000 g (dry base) of this calcined alumina were mixed with a solution containing 592 g of 30 La (130,) ~ .6Ho0 dissolved in 1,400 ml of water in a mechanical mixer. The solution was added at the rate of 100 ml per minute, in this alumina. The impregnated alumina was removed from the mixer, heated to 538 ° C and held at 53SCC for 30 minutes. Sample 35 contained 10% by weight of La203 and had an average particle size of less than 10 / * -.

p __ k- 16 EXAMPLE 19

Alpha-alumina monohydrate was calcined in air for 1 hour at 677 ° C to obtain a product having an average particle size of 15 to 20yPc-5 in diameter. 2,000 g (dry base) of this calcined alumina were mixed with a solution of 670 g of La (NO ^) dissolved in 1,400 ml of water in a mixer. The solution was added at the rate of 100 ml per minute. The impregnated alumina was removed from the mixer, heated to 538 ° C and kept at 538 ° C for 30 minutes. This impregnated and calcined alumina was brought back to the mixer and received a second impregnation with 670 g of LaÇNO - ^^. ÔH ^ O in 1,200 ml of water which was added at the rate of 100 ml per minute. The impregnated material was heated to 538 ° C and held at 538 ° C for 30 minutes. The finished material contained 20% by weight of La ^ O ^ and had an average particle size of less than 10 EXAMPLE 20 The finished SO agent of Example 18 was incorporated into the particle of a cracking catalyst related to alumina. The catalyst was prepared by mixing the following materials together; the SOX getter agent of Example 18, a crystalline alumino silicate of type Y with exchanged rare earth ions, clay, a sol of aluminum hydrochloride (approximate formula: Α ^ ΟΙζΟΗ) ^) and some water. The mixture was spray dried and then calcined for 2 hours at 538 ° C. The proportion of the raw materials was such that the finished catalyst contained 20% of the getter agent of SO-30 of Example 18, 12% of the crystalline silicate alumina of type Y with ions of rare earth ions, 54% of clay and 14% alumina. The finished catalyst had an average particle size of 116y ^ with 65% er> weight these particles between 20 and 140y2 ~.

35 EXAMPLE 21

We repeated the process of example 20 but using / the SO getter agent. from example 19- ^. “" s ~ 17

In this example, the finished catalyst had an average particle size of 77 with 87% by weight of the particles between 20 and 149yO- * EXAMPLE 22 A cracking catalyst bound to the alumina sol was prepared, by mixing the following materials : a crystalline aluminosilicate of type Y with ions exchanged with, rare earths (CREY), clay, a sol of aluminum hydrochloride (approximate formula: 41 ^ 01 (0H) ^) and water.

* 10 The mixture was spray dried and then calcined for 2 hours at 538 ° C. The proportion of raw materials was such that the finished catalyst contained 12% of a crystalline aluminosilicate of the type Y with ions exchanged of rare earths, 78% of clay and 10% of alumina.

The finished catalyst had an average particle size of 71% - with 97% by weight of the particles between 20 and 149%.

29.89 g (dry base) of this alumina-linked cracking catalyst were totally mixed with 0.1110 g (dry base) of an oxidation catalyst containing 810 ppm of platinum on a gamma support. alumina having a particle size in the range that can be fluidized.

. * EXAMPLE 25 26.89 g (dry base) of the cracking catalyst described in Example 22 were completely mixed with 0.1110 g (dry base) of the oxidation catalyst, also described in Example 22. To this mixture, which has been well mixed, was added 3,000 g (dry base) of a commercially available alpha-alumina monohydrate.

EXAMPLE 24

26.89 g (dry base) of the cracking catalyst described in Example 22 were completely mixed with 0.1110 g (dry base) of the oxidation catalyst, also described in Example 22. in this mixture, and a total mixture, 3.00 g (dry base) of the composition / Lao0_ / Alo0v prepared in Example 2.

/ vs. O eL j: -p.

18 EXAMPLES 25- ^ 6

The process of Example 24 was repeated, but using the composition prepared for Example 3 for the third component to be mixed. Likewise, the process was repeated, but with the compositions prepared for the third components. in examples 4, 5, 6, 7, 8, 9, i '11, 12, 14, 15 and 17.

! v EXAMPLE 37 | 29.89 g (dry base) of the finished catalyst of Example 20 was completely mixed with 0.1110 g (dry base) t j. of the oxidation catalyst described in Example 22. · I EXAMPLE 38; 29.89 g (dry base) of the finished catalyst of Example 21 were totally mixed with 0.1110 g (dry base) of the oxidation catalyst described in Example 22.

EXAMPLE 39

A laboratory scale catalytic cracking unit was used to test the catalytic • compositions for their ability to reduce emissions of 20 S0X (SO2 + S03) from the regenerator.

Before trying in the laboratory unit,; the catalysts or catalytic mixtures were deactivated with steam with 100% steam at 1.03 bar and 732 ° C for 8 hours. This steam deactivation 5 · * * | 25 simulates the deactivation that occurs in a unit of | commercial catalytic cracking. The ability of a catalyst or catalytic mixture to reduce S0y emissions in the laboratory test unit after this steam deactivation will be a measure of its ability to reduce SO6 emissions in commercial units . On the contrary, the capacity of a fresh or un-deactivated catalyst or catalytic mixture to reduce SOX emissions in a laboratory test is not conclusive as regards the capacity of the catalyst or of the mixture of catalysts to reduce i SO emissions in commercial units, because the co-catalyst or the mixed catalyst will be deactivated in the commercial unit shortly after being introduced into this unit, and may become ineffective in reducing emissions from S0X ·

In the laboratory unit, a low sulfur gas oil was cracked on the catalyst or the catalyst mixture at a temperature of 527 ° C. The regeneration of the catalyst or of the catalytic mixture, that is to say the step of combustion of the coke, was carried out with fi of air at 677 ° C. The air used for the combustion stage. 10 of the coke contained 2,000 ppm SO2 · This is equivalent to the amount of SO £ formed in the regenerator with a high sulfur diesel used for the cracking step.

The regenerated catalyst or catalytic mixture ‘15 was then subjected to the steps of cracking. And of steam extraction to release, in the form of E ^ S, the δΟχ captured in the regenerator.

The regeneration and cracking and steam extraction steps were repeated. During this second cycle, part of the catalyst or catalyst mixture was removed after the regeneration step, and another part of the catalyst or catalyst mixture was removed after the cracking and steam extraction steps .

25 An SO index, which gives the measure of SO

captured in the regenerator and released in the reactor and the rectifier can be defined by

SO index ^ = / content of \ / content of \. -rr) / sulfur, in \ / sulfur, in \ ^ / percentage \ / percentage \ by weight, \ J by weight, in the in the catalyst - catalyst 1.000 or the mixture or the mixture \ catalytic catalytic \ after the stage / after the 35 \ of regeneration / stages of

Vation / cracking and __ \ extraction / \ steam / 20

A sample calculation for the catalytic mixture described in Example 31 and indicated in Table I is given below.

DeSOx index = [(0.167) - (0.097) J 1000 = 70 5

It should be noted that the SO index is a measure - quantité of the amount of SO x captured in the regenerator and released in the reactor and the rectifier. A catalyst | 9 or catalytic mixture capturing SO in the regenerator s 10 but not releasing it in the reactor and the rectifier will have an SO index of zero. Such a catalyst or

AT

catalytic mixture will quickly become saturated, probably after one or two cycles, to lose its effectiveness in reducing SO emissions.

15 For long-term efficiency, a catalyst

or catalytic mixture must not only capture SO

AT

in the regenerator but be able to release it in the reactor and the rectifier, in order to restore its ability to repeat the process.

The higher the Davison S0 „index, the greater the long-term effectiveness of the catalyst or catalytic mixture in reducing S0y emissions from the regenerator. As noted above, a Davison S0X index of zero means that catalyst 25 is not effective in the long term in reducing S0y emissions to the regenerator. At the other extreme, a Davison S0V index of 100 essentially means 100% long-term efficiency in reducing S0x emissions from the regenerator.

The catalytic mixtures described in Examples 22, 23, 26, 31, 32, 33, 34 and 35 were examined for their ability to reduce SOx emissions according to the process described above. The indices of S0X are given in the table

I. A graphical representation of data from Table I

35 (with the exception of the catalytic mixture described in Example 22 is shown in the single figure where the SO index is represented as a function of the nourcentase of La-Qr in the arent - - · - zy - 21 getter de SO in the mixture The curve shown in the figure indicates that the maximum SO index is obtained when the getter agent of SOX contains about 20% of La ^ O ^ · More generally, the data in Table I show that the maximum SO index is obtained at concentrations

AT

trations of "^ 2 ^ 3 greater than 12% and less than 30% (examples 32 and 34) ·

Table I

Catalytic mixture S0 index 10 described in example 22 10 23 18 26 42 34 58 15 35. 70 31 69 32 .56 33 44 EXAMPLE 40 The catalytic mixtures described in Examples 37 and 38 were examined for their capacity to reduce SO emissions according to the process described in Example 39 *

AT

The SO indices obtained are given in Table II.

AT

Table II

25 Catalytic mixture Indlce ûe 30χ described in the example ---—— 37 46 38 58 30 EXAMPLE 41

The catalytic mixtures of these examples 24, 25, 26, 27, 28 and 29 were examined for their capacity to reduce the emissions of SO according to the process described in the example.

AT

39 · The Davison indices of S0, _ obtained are given in x 35 table III.

The data in Table III show the effect of calcination on the alumina hydrate before impregnation with a solution of La (NO ^) ^ -6 ^ 0. In Example 24, the alumina hydrate was not calcined before impregnation. In Examples 25, 26, 27, 28 and 29, the alumina hydrate was calcined at temperatures between 482 and 1056 ° C.

5 Table III

Effect of calcination of alumina before impregnation

Catalytic mixture SO index

e described in the example - 10 24 32 25 35 26 42 27 35 28 29 15 29 36 EXAMPLE 42

The cracking catalyst used in this example is a commercial cracking catalyst containing 17% by weight of a crystalline aluminosilicate of type Y with rare earth exchange ions (REY), 63% by weight of clay and 20% by weight. a silica-alumina sol binder.

29.89 g (dry base) of this cracking catalyst were completely mixed with 0.1110 g (dry base) of an oxidation catalyst containing 810 ppm of platinum impregnated on a gamma-alumina support having a dimension of particles in the range that can be fluidized.

30 EXAMPLE 4 5

26.89 g (dry base) of the cracking catalyst described in Example 42 were totally mixed with 0.1110 g (dry base) of the oxidation catalyst, also described in Example 42. Was added, to this mixture, 3.00 g (dry base) of a commercially available alpha-alumina monohydrate, and was thoroughly mixed.

23 EXAMPLE 44

26.89 g ("dry base") of the cracking catalyst described in Example 4-2 were completely mixed with 0.1110 g (dry base) of the oxidation catalyst, also described in Example 42. To this mixture was added 3.00 g (dry base) of the composition prepared in Example 9 and completely mixed.

EXAMPLE 43

The catalytic mixtures described in Examples 42, 10 43 and 44 were examined for their ability to reduce SOV emissions according to the process described in Example 39.

The SO indices obtained are given in Table IV.

The results show that the cracking catalyst of a silica-alumina sol gave a 15 SO index of zero (Example 42). The use of alumina as an S0X getter agent gave an S0X index of 5 (example 43) · The use of an SO getter agent composed of

Lao0-r / Alo0, according to the invention gave an S0V 2323 x Index of 50 (Example 44), which represents a considerable improvement compared to the use of alumina.

Table IV

Mix ^ SQ maice catalog

'described in the example --— 42 0 25 43 3 44 50 EXAMPLE 46

27.00 g (dry base) of the cracking catalyst described in Example 22 were totally mixed with 3.00 g (dry base) of the composition of La ^ yéAJ ^ O ^ prepared in Example 9. This catalytic mixture was examined for its ability to reduce SOx emissions according to the process described in Example 39 · The SO index obtained had a value of 48. This can be compared to an SO index

X

of 69 obtained for the catalytic mixture described in Example 31, containing an oxidation catalyst. This means that the SO getter agent according to the invention Λ works without the presence of an oxidation catalyst. It also shows that the presence of an oxidizing catalyst increases the ability of the getter agent to reduce SOx - emissions. <s ·

Claims (21)

25 1. Catalytic composition, characterized in that it contains: (a) a hydrocarbon cracking catalyst, and (b) a getter agent of sulfur oxides which contains an alumina substrate coated with an oxide of f lanthanum. 2. Composition according to claim 1, characterized in that the aforementioned alumina substrate 10 contains around 5 to 50% by weight of lanthanum oxide. 3. Composition according to claim 1, characterized in that the aforementioned alumina has a surface area of the order of 45 to 450 m / g and preferably of the order of 110 to 270 m ^ / g and contains approximately 12 to 30% by weight of lanthanum oxide. 4. Composition according to claim 1, characterized in that the aforementioned alumina is coated essentially with a monolayer of lanthanum oxide. 5. A composition according to claim 1, ‘characterized in that the aforementioned alumina substrate is„ an alumina hydrate. 6. Composition according to any one of claims 1 or 4, characterized in that the aforementioned alumina substrate is calcined. 7. Composition according to claim 1, characterized in that the above-mentioned lanthanum oxide is. incorporates with a mixture of rare earth oxides. 8. Composition according to claim 1, characterized in that the aforementioned cracking catalyst contains a crystalline zeolite in admixture with a matrix of an inorganic oxide, said zeolite being chosen from the group consisting of hydrogen and / or zeolite of type X or of type Y exchanged for rare earths, 35 ZSM zeolites and their mixtures. / 26 9 · - Composition according to Claim 1, characterized in that the above-mentioned cracking catalyst contains a crystalline zeolite in admixture with a matrix which contains clay and / or alumina hydrate and an alumina sol dried. 10.- Composition according to claim 1, characterized in that the aforementioned catalytic composition * contains of the order of 0.1 to 100 parts per million of a noble metal as an oxidation catalyst, said catalyst 10 oxidation being added to said catalytic composition in the form of a noble metal impregnated on a particulate inorganic oxide, and said oxidation catalyst is chosen from the group consisting of platinum, palladium and their mixtures. 11. Composition according to Claim 1, characterized in that the above-mentioned lanthanum oxide is distributed over the surface of the above-mentioned alumina in combination with an oxidation catalyst chosen from the group consisting of platinum, palladium and mixtures thereof. 12. - Composition according to claim 1, characterized in that particles of the above-mentioned getter agent are physically mixed with the particles of the above-mentioned catalyst. ; - 13 · - Composition according to claim 1, 25 characterized in that the agent. aforementioned getter is! incorporated into the particles of the above catalyst. | 1h.- Composition according to claim 1, | l characterized in that it contains around 0.5 to 605¾! by weight of the agent g.etter of sulfur oxides. 30 15 - Composition of sulfur oxide getter agent, characterized in that it contains alumina j and lanthanum oxide distributed essentially in a monolayer on the surface of said alumina. 16.- CoEîposition according to claim 15s; 35 characterized in that it contains about 5 to 50> £ by weight of lanthanum oxide which is uniformly distributed on the surface of an alumina having a surface sire 27 of at least 45 i / g and preferably of the order of 110 to 270 m / g and it contains about 12 to 20% by weight of lanthanum oxide. 17. Composition according to claim 16, '5 characterized in that the above-mentioned lanthanum oxide is incorporated with a mixture of rare earth oxides. 18. Composition according to claim 16, characterized in that the above-mentioned lanthanum oxide is distributed on the surface of the alumina in a monolayer. „10 19 · - Composition according to Claim 15, characterized in that it has the form of microspheroidal particles having approximately 90% of the particles in the range of diameters from 20 to 105fl. 20. Composition according to claim 15, 15 characterized in that it has the form of particles with approximately 90% of the particles in the range of diameters from 0.5 to 20μ. 21. Composition according to claim 15, characterized in that it has the form of particles having more than one millimeter in diameter. 22. Composition according to claim 15, characterized in that it contains an oxidation catalyst, which is an oxidation catalyst of a noble metal,. said oxidation catalyst being incorporated in amounts of between about 0.1 and 1,000 parts per million by weight of the composition, and is selected from the group consisting of platinum, palladium and mixtures thereof, being added to said composition in the form of palladium and / or platinum impregnated on a particulate inorganic oxide. 23. Composition according to claim 15, characterized in that the above-mentioned lanthanum oxide is distributed on the surface of the alumina in combination with an oxidation catalyst chosen from the group consisting of platinum, palladium and their mixtures. 24. Method for controlling SOX emissions> characterized in that it consists in: __ 28 (a) incorporating, in a reaction zone, a getter agent according to claim 15 which must combine with the sulfur oxides in said zone ; (b) restore or regenerate said getter agent 5 containing sulfur obtained in step (a). 25.- The method of claim 24,! characterized in that an oxidation catalyst is present: e J in said zone. 26. The method of claim 24, “10 characterized in that the aforementioned getter agent is. restored or regenerated by reduction and / or hydrolysis in the presence of a reducing agent and / or of vapor, j 27.- Process according to claim 24, i characterized in that the agent g.etter regenerated or restored is recycled to the reaction zone, s 28.- Process for cracking feedstocks of hydrocarbons containing sulfur compounds 5! · Organic, characterized in that it consists in: (a) reacting feedstocks ij 20 of hydrocarbons containing organic sulfur compounds j with the catalytic composition according to claim 1 'under catalytic cracking conditions for obtaining a stream of the cracked product and a catalytic composition combined with sulfur-containing coke; | · 25 ‘(b) passing said catalytic composition to a steam extraction zone to remove them; extractable hydrocarbons of the catalytic composition; (c) passing said extracted catalytic composition 30 to a regeneration zone where the coke containing - 1 sulfur is oxidized to carbon monoxide, carbon dioxide, water and sulfur oxides, and said sulfur oxides are | combine with said getter agent of said catalytic composition I to form a thermally stable sulfate or type 35 sulfate compound; (d) returning said regenerated catalytic composition obtained in step (c) to the reaction step (i / '29 and the steam extraction step (b) where said sulfur-containing scavenger is reduced and hydrolyzed to produce volatile hydrogen sulfide which is recovered as a component of the cracked product stream and to restore or regenerate the getter agent which is recycled in the process. 29. Method according to claim 28, characterized in that the aforementioned getter agent is incorporated in the form of a particulate additive. 30. The process according to claim 29, characterized in that an oxidation catalyst is incorporated in amounts required to obtain a desired level of oxidation of carbon monoxide and / or sulfur oxide, said oxidation catalyst being selected from the group consisting of platinum, palladium and mixtures thereof, and is added in amounts of between about 0.1 and 1,000 parts per million by weight of a noble metal. 31. “Method according to claim 28, 20 characterized in that the cracked gas stream is recovered. ! a 1 1 i '("V \ \." -. · / \ V \ VJ