FR2501531A1 - CATALYTIC COMPOSITION, SULFUR OXIDE GETTING AGENT, SOX EMISSION CONTROL METHOD, AND METHOD OF CRACKING HYDROCARBON FEEDSTOCKS - Google Patents

Abstract

THE INVENTION RELATES TO A CATALYTIC COMPOSITION. ACCORDING TO THE INVENTION, IT CONTAINS A HYDROCARBON CRACKING CATALYST AND A SULFUR OXIDE GETTER WHICH CONSISTS OF AN ALUMINA SUBSTRATE COATED WITH LANTHANUM OXIDE; THE ATTACHED DRAWING GIVES THE SO INDEX AS A FUNCTION OF THE LAO CONTENT IN THE GETTER AGENT. THE INVENTION APPLIES IN PARTICULAR TO THE CRACKING OF HYDROCARBONS CONTAINING SULFUR.

Description

The present invention relates to catalysts which are used for

  catalytic cracking of hydrocarbons, as well as getter / sulfur oxide absorber 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 (SO) emitted to the atmosphere during catalyst regeneration, as well as highly effective catalysts. SOX control that can be used to control SOx emissions from a wide variety of processes. Cracking catalysts that are used to crack hydrocarbon feedstocks become relatively inactive due to carbonaceous material deposits 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,

  of the catalyst, the hydrocarbons being extractable.

  The catalyst then passes to the regenerator where it is regenerated by burning the coke in an oxygen-containing gas. This converts carbon and hydrogen in the coke into carbon monoxide, carbon dioxide and water. Sulfur in the coke is converted to sulfur oxides, SOI

and SQ3, that is, SQx.

  In general, the greater the amount of sulfur in the feedstock, 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 feed gas of the regenerator. In general, the amount of SQ2 and SQ3, i.e., SOx} in the flue gas

  reaches about 250 to 2,500 parts per million by volume.

  The prior art has suggested various methods for removing or preventing the release of SOX to the atmosphere during oxidation combustion from 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 9etters (sometimes referred to as "QS acceptors") such as calcium oxide. In some cases, charges

  hydrocarbon feed are pre-treated (hydro-

  treated) to remove sulfur. It has been said that sulfur oxide emissions from fluid catalytic cracking units can be controlled by using a cracking catalyst in combination with a sulfur absorbing agent or metering agent. It has also been said that these sulfur getter agents were more effective in them

  using in the presence of oxidation catalysts.

  Oxidation catalysts are commonly used in fluid catalytic cracking units to oxidize CO to CO 2 in the catalyst bed during the coke combustion step in the regenerator. Oxidation of CO to CO 2 in the catalyst bed causes many benefits. One of them is the reduction

  CO emissions. Another allows to avoid the "post-

  combustion ", ie the oxidation of CO to CO2 outside the catalyst bed, which results in a loss of thermal energy and which damages the cyclones and lines

  output of flue gases. The major benefit of using

  The use of the oxidation catalysts to oxidize CO to CO 2 in the catalyst regenerator bed derives from the heat liberated when CO is oxidized to CO 2. This heat raises the temperature of the catalyst bed and thus increases the combustion rate of the coke. This gives a lower level of residual carbon on the regenerated catalyst (CRC). This, in turn, makes the regenerated catalyst more active for the cracking step. This increases the amount of useful products obtained in the cracking unit

fluid catalytic.

  Given the fact that catalysts

  oxidation of CO are commonly used in many

  Because of its economical catalytic cracking units, SO x getterg agents for use in fluid catalytic cracking units must be compatible and effective in the presence of the oxidation catalysts. In addition, SQx getter agents for use in fluid catalytic cracking units must be effective under the actual conditions seen in these units, such as temperatures of 427-5380C and catalyst residence times of 15 seconds in the reducing atmosphere of the reactor, temperatures of 427-538oC in the steam atmosphere of the rectifier, temperatures of 593-7600C and residence times of the catalyst of 5 to 15 minutes in the oxidizing atmosphere of the regenerator . In addition, SO 2 getter agents for use in fluid catalytic cracking units must be effective in the presence of the materials present in these units, such as cracking catalysts of various compositions, oil feedstocks of various compositions, and their cracked products and as previously indicated, the oxidation catalysts

to oxidize CO to CO2.

  The following U.S. patents disclose the use of cracking catalysts containing various agents controlling carbon monoxide and sulfur emissions.

3,542,670

3,699,037

3,835,031

4,071,436

4,115,249

4,115,250

4,115,251

4,137 151

4,151 119

4,152,298

4,153,534

4,153,535

4,166,787

4,182,693

4,187,199

4,200,520

4,206,039

4,206,085

4,221,677

4,238,317

  As can be seen in the above-noted references, the organic sulfur present during the regeneration of the cracking catalyst is ultimately oxidized to sulfur trioxide (SOO) which reacts with a getter agent to form a stable sulfate which is retained in inventory

  catalytic unit 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, olefins light, and others). When the sulphate-containing catalyst is exposed to the reducing and hydrolysis conditions present during the cracking step and the subsequent hydrolysis conditions present in the steam rectifier, the sulphate is reduced and is hydrolysed to form sulphide. hydrogen (H2S) and restore or regenerate the cretcher. Hydrogen sulfide is recovered as a component of the cracked product stream. The getter agent

  is recycled to the regenerator to repeat the process.

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

greatly reduced.

  However, it has been found that attempts to produce S0 control cracking catalysts to 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 catalytic cracking composition which makes it possible to reduce oxide emission efficiently and economically.

  of sulfur of fluid catalytic cracking units.

  Another object of the present invention is a sulfur oxide getter capable of removing sulfur oxides over a long period of time during cycles.

multiple getter / regeneration.

  Another object of the present invention is

  SQX control additive that can be added to the inven-

  catalytic cracking unit in quantities needed to reduce the flue gas emissions of the sulfur oxide regenerator to a

acceptable level.

  The present invention also relates to getter agents. very effective sulfur oxides

  advantageously be combined with conventional compositions.

  cracking catalyst or used to control SO 2 emissions from a wide variety of

process.

  The invention will be better understood, and other purposes, features, details and advantages thereof

  will appear more clearly during the description

  explanatory text which will follow with reference to the accompanying schematic drawing given by way of example only, illustrating an embodiment of the invention and in which: the single figure is a graphical representation of data illustrating the SQ index, on the y-axis as a function of the La2O3 content on the axis

  abscissas of SO getters according to the invention.

  In general, the present invention contemplates catalyst catalytic cracking compositions which contain a SQx getter agent with lanthanum oxide-alumina. Furthermore, the present invention contemplates an improved SOx getter agent, which contains a lanthanum oxide (Al 2 O 3) coated alumina (Al 2 O 3) substrate in amounts producing approximately one theoretical monolayer of La 2 O 3 molecules on the surface. alumina substrate. These gettert agents can be effectively combined or included in particulate catalytic compositions used for the catalytic cracking of hydrocarbons, or the getter5 agents can be used in any combustion process

  which produces SOx components that must be selected

  removed from the products of combustion.

  In particular, it has been found that an agent

  particularly effective absorbent / SX-getter

  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 alumina substrate, a lanthanum oxide layer having about

a molecule of thickness.

  In practice, it has been found that the desired result is obtained with about 5 to 50% by weight of La 2 O 3 combined with an alumina substrate having a surface area in the range of 45 to 450 m 2 / g; preferably, about 12 to 30% by weight of La 2 O 3 in combination with an alumina substrate having a surface area of about 110 to 270 m 2 / g; and more preferably there is about 20% by weight of La 2 O 3 in combination with an alumina substrate having a surface area in the order of

m2 / g.

  Suitable substrates of alumina are available

  many commercial sources, and they understand

  alumina hydrates, such as alpha-monohydrate

  alumina, alpha-alumina trihydrate, beta-alumina monohydrate and beta-alumina trihydrate. The calcined versions of the above hydrates of alumina are also considered to be very suitable. These are the

  gamma-alumina, chi-alumina, eta-alumina, kappa

  alumina, delta-alumina, theta-alumina, alpha-alumina

  alumina and mixtures thereof. The lanthanum oxide component which is spread on the surface of the alumina can be obtained in the form of a commercialized lanthanum salt such as nitrate or

  lanthanum chloride or sulphate or alternatively

  a mixed salt of rare earths that contains other pollutants

  rare earths such as Nd, Ce, Pr and Sm can be used.

  The rare earth component of a typical and commercial mixed rare earth salt solution which contains lanthanum has the following approximate composition, expressed as oxides: 60% La203, 20% Nd203, 14% CeO2, 5% Pr6011 and 1% Sm2O3. It will be understood that in the case where a source of mixed rare earth salts is used, the amount of salts used must be sufficient to obtain the desired level of La 2 O 3 on

the alumina substrate.

  The amount of lanthanum oxide which is used in the preparation of the SOx getter agent according to the invention is preferably the amount which will form a monolayer of lanthanum oxide molecules on the surface of the alumina substrate. . In the case where the amount of lanthanum oxide, as specified above, is substantially exceeded, i.e. lanthanum oxide is formed in several layers or in bulk this adversely affects the effectiveness of the SOx getter agent. Moreover, if lanthanum oxide is used in an insufficient quantity, the effectiveness of the agent

  cetter is less than it should be.

  While the precise mechanism is not fully understood, it is believed that the active species is a La203 molecule attached to the surface of alumina in some kind of a surface complex of La203 and AA1203. This La2O3 surface complex on Al203 is very reactive by combining

- 2501531

  with the sulfur oxides to form a thermally stable solid sulphate or sulfate-type compound. Moreover, this thermally stable solid sulphate or sulphate-type sulphate can easily be reduced-hydrolysed to produce volatile hydrogen sulphide and restore or

  regenerate the original La203 surface complex on A1203.

  Hydrogen sulfide can be recovered as a component of the product stream. The restored or regenerated gltter agent can be recycled to repeat the steps

absorption and regeneration.

  To prepare the new SOX getter agent the alumina substrate is uniformly and totally mixed with a certain amount of a solution of a lanthanum salt which will give the desired uniform dispersion of lanthanum oxide on the surface. Typically, salt

  soluble lanthanum, preferably lanthanum nitrate.

  Num, 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 solution of the lanthanum salt, 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 alumina surface. While it is envisaged that calcining temperatures will reach

  8161C can be used, calcination temperatures

  the order of 5181C were satisfactory.

  In a preferred embodiment of the invention,

  the alumina substrate to be impregnated into the form of

  microspheroidal particles, with about 90% of the particles

  having diameters in the range of dimensions that can be fluidized from 20 to 149. The getter agent prepared using these microspherical particles may advantageously be physically mixed with the fluid catalytic cracking catalyst in amounts between

  about 0.5 and 60% by weight of the total composition.

  In another embodiment of the invention, the alumina substrate to be impregnated is in the form of particles having an average size of less than 20, A, in diameter, and preferably less than 10 .ANG. In diameter. The finished getter agent prepared using these fine particles may be incorporated into a composition of a cracking catalyst during formation of the catalyst particles. Typically, lanthanum-impregnated alumina is added to an aqueous slurry of catalyst components prior to shaping, i.e., spray drying.

  in the case of catalytic cracking catalysts fluid.

  In another embodiment of the invention, the alumina substrate to be impregnated is in the form of particles 1 millimeter in diameter or larger. The finished getter agent prepared using these particles can be used either in fixed bed or moving bed, to reduce

  SQx from a wide variety of processes.

  Therefore, it can be seen that the present cetter agent can be used as a separate additive which is added to the catalyst as a separate particulate component, or the getter agent can be combined with the catalyst during its preparation to obtain catalyst particles which contain the setter agent as an integral component. In addition, the getter agent can be used in itself to reduce emissions

  of SOx from a wide variety of processes.

  Cracking catalysts which can advantageously

  The combined SOX getter agent according to the invention are commercially available compositions, and typically comprise crystalline zeolites in admixture.

  with inorganic oxides as binders and clay.

  Typically, these catalysts contain from about 5 to% by weight of crystalline aluminosilicate zeolite in combination with a hydrogel binder or silica sol, silica-alumina or alumina, and optionally of the order of 10 to 80% by weight of clay. Zeolites typically used in the preparation of cracking catalysts

  are stabilized Y-type zeolites, the preparation of which

  This invention is disclosed in US Pat. Nos. 3,293,192, 3,375,065, 3,402,996, 3,449,070 and 3,595,611. The preparation of the catalyst compositions which can be used in the practice of the invention is typically disclosed in US Patent Nos. 3,957,689, 3,867,308, 3,912,611

  and in Canadian Patent NI 967,136.

  In the preferred practice of the invention, the getter composition of the cracking catalyst will be used in combination with an oxidation catalyst of one or more

  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 an aluminum chlorhydroxide, a clay / zeolite composition bonded thereby. is revealed in the patent

  NI 967 136 mixed with an oxidation catalyst

  containing platinum particulate to obtain a composition which contains 0.5 to 60% by weight of the getter agent, 40 to 99% by weight of the cracking catalyst and

  1 to 5 parts per million platinum.

  In another preferred practice of the invention, the SOX getter is combined with a zeolite cracking catalyst which has a matrix essentially

  silica-free. These catalysts are obtained using

  The process described in Canadian Pat. No. 967,136 by mixing the following materials together: 5 to 50% by weight of zeolite, 10 to 80% by weight of alumina hydrate (dry basis) and 5 to 40% by weight of an aluminum chlorohydroxide sol (Al 2 O 3), and water The mixture was spray-dried to obtain a finely divided composite catalyst and then calcined at a temperature of the order of 53 ° C. SQx agent setter can be incorporated as a component of the spray-dried slurry in place of a portion of the alumina hydrate or the SO 2 getter agent can be physically mixed with the catalyst at a quantity of 1%. From 0.5 to 60% by weight As indicated 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 getter agent can be incorporated into the catalyst particle by mixing the additive to

  components of the catalyst before forming the catalyst.

  In addition, it is contemplated that the getter agent may be used in any combustion / reaction process where it is desirable to collect or remove the sulfur oxides from a product gas stream. Typically, the SO aetter may be used in a fluidized coal combustion process to remove SOX formed during coal combustion. The SO 2 getter may then be removed from the combustion / reaction zone, periodically or continuously, to restore or regenerate the agent-getter by subjecting it to reduction-hydrolysis in the presence of hydrogen or reducing gas mixtures. carbon dioxide (such as synthetic gas) and H 2 O. Using this technique, the S x component in the combustion products is selectively removed as a stable sulfate, and the sulfate is subsequently reduced-hydrolyzed to release H2S and restore or regenerate the getter agent. H2S

  can be recovered using conventional techniques

adsorption.

  Having described the basic aspects of the present invention, the following examples are given for in

  illustrate specific embodiments.

EXAMPLE 1

  A solution of lanthanum nitrate was prepared by dissolving 79.7 g of lanthanum nitrate, La (NO 3) 3.6H 2 O, in sufficient water to give 100 ml of solution. 10 ml of this solution contains 3.0 g of lanthanum expressing as lanthanum oxide, La203

EXAMPLE 2

  36.8 g (27 g on a dry basis) of a marketed alphaaluminum monohydrate having a mean particle size (APS) of 67 "was impregnated with 96% of the particles in the size range of 20 to 149.

  microns, 10 ml of the solution described in Example 1.

  The impregnated alumina was heated to 538 ° C and held at 538 ° C for 30 minutes. The resulting sample of

  La 2 O 3 / Al 2 O 3 contained 10% by weight of La 2 O 3.

EXAMPLE 3

  Alpha-alumina monohydrate of the type described in Example 2 was calcined in air for 1 hour at 48 ° C. 27 g of this calcined alumina were impregnated with ml of the solution described in the example. 1. The impregnated sample was heated to 538 ° C and held at 538 ° C for minutes. The resulting sample of La203 / A1203

  contained 10% by weight of lanthanum oxide La203.

EXAMPLE 4

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

EXAMPLE 5

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

EXAMPLE 6

  The procedure of Example 3 was repeated but calcining the alumina hydrate for 1 hour at 10 ° C. before impregnation with the nitrate solution.

Lanthanum. -

EXAMPLE 7

  The process of Example 3 was repeated but calcining the alumina hydrate at 1066 ° C. before impregnation

  with the lanthanum nitrate solution.

EXAMPLE 8

  Alumina hydrate of the type described in Example 2 was calcined in air for 1 hour at 67 ° C. 5 ml of the solution described in Example 1 was mixed with 5 ml of water to give 10 ml of a solution having a lanthanuum concentration of 1.50 g of lanthanum expressing as La 2 O 3. 28.5 g of the calcined alumina was impregnated with the 10 ml of the solution. The impregnated sample has

  was heated to 5380C and held at 5380C for 30 minutes.

  The resulting La203 / A203 sample contained 5% by weight

from La203.

EXAMPLE 9

  Alumina hydrate of the type described in Example 2 was calcined in air for 1 hour at 67 ° C. 24 g of this calcined alumina was impregnated with 10 ml of the solution described in Example 1. The impregnated sample was

  was heated to 5380C and held at 5380C 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 5380C and held at 5380C for 30 minutes.

  The resulting sample of La203 / A1203 contained 20%

weight of La2O3.

EXAMPLE 10

  A solution of lanthanum nitrate was prepared by dissolving 99.8 g of La (NO 3) 3.6H 2 O in water to give 100 ml of solution. 8 ml of solution contain

  3.0 g of lanthanum expressed by La 2 O 3.

EXAMPLE 11

  Alumina hydrate was calcined in air for 1 hour at 67 ° C. as in Example 9. 21 g of this calcined alumina were impregnated with 8 ml of the solution described in Example 10. impregnated sample has been

  heated to 5380C and held at 5380C for 30 minutes.

  After allowing it to cool to room temperature, the impregnated and calcined sample received a second impregnation with 8 ml of the solution described in Example 10. After this second impregnation, the sample was

  heated at 53 ° C. and kept at 53 ° 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

  The sample was heated to 538WC and held at 5381C for minutes. The resulting sample of La203 / A1203

contained 30% by weight of La203.

EXAMPLE 12

  The procedure of Example 11 was repeated, but using 18.0 g of calcined alumina, and after the third impregnation and calcination, the sample was

  received a fourth impregnation and calcination at 538WC.

  The resulting sample of La203 / Al203 contained 40% in

weight of La203.

EXAMPLE 13

  A mixed rare earth nitrate solution was prepared by mixing 153.1 g of a commercial solution of rare earth mixed nitrates with water to give 100 ml. 8ml of the solution contained 3.0g of rare earth mixed as oxides. The rare earth component of this solution expressing by weight as oxides had the following composition:% La203, 20% Nd203, 14% CeO2, 5% Pr6011

and 1% Sm203.

EXAMPLE 14

  The procedure of Example 9 was repeated but impregnated with 8 ml of the solution described in Example 13. The resulting sample contained% by weight of mixed earth oxides. 60% of these rare earth oxides were represented by lanthanum oxide, so the resulting sample contained 12% by

weight of La203.

EXAMPLE 15

  The procedure of Example 11 was repeated but impregnating with 8 ml of the solution described in Example 13. The resulting sample contained% by weight of mixed rare earth oxides of which 60% was lanthanum oxide. The resulting sample contained 18% by weight of La2O3.

EXAMPLE 16

  A mixed rare earth nitrate solution was prepared by mixing 152.8 g of a commercial solution of rare earth nitrates mixed with water to give 100 ml. 10 ml of the solution contain 3.75 g of mixed rare earth by expressing by the oxides. The rare earth component of this solution, expressing in oxides has the following composition: 60% of La203, 20% of Nd2O3, 14% of CeO2, 5% of Pr6011 and

1% of Sm203.

EXAMPLE 17 The procedure of Example 9 was repeated, but by carrying out the

  impregnated with 10 ml of the solution described in Example 16. The resulting sample contained 5% by weight of mixed rare earth oxides. 60% of these rare earth oxides were represented by lanthanum oxide, and thus the resulting sample

contained 15% by weight of La203.

EXAMPLE 18

  Fine alpha-alumina monohydrate was calcined in air for 1 hour at 6770C. This calcined alumina had an average particle size of 15 to 20 / LL. 2.000 g (dry basis) of this calcined alumina was mixed with a solution containing 592 g of La (NO 3) 3.6 H 2 O dissolved in 1400 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 53 ° C. and held at 53 ° C. for 30 minutes. The sample contained 10% by weight of La203 and had a dimension

  average particles less than 10/4.

EXAMPLE 19

  Alpha-alpha monohydrate was calcined in air

  alumina for 1 hour at 677 C to obtain a product

  having an average particle size of 15 to 20 / p-

  of diameter. 2.000 g (dry basis) of this calcined alumina was mixed with a solution of 670 g of La (NO 3) 3.6 H 2 O dissolved in 1400 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 held at 538 ° C for 30 minutes. This impregnated and calcined alumina was returned to the mixer and further impregnated with 670 g of La (NO 3) 3 H 2 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 53 ° C for 30 minutes. The finished material contained 20% by weight of La203 and had a dimension

  average particles less than 10 / ".

EXAMPLE 20

  The SOx finished agent of Example 18 was incorporated into the particle of an alumina bonded cracking catalyst. The catalyst was prepared by mixing together the following materials: the SOx getter agent of Example 18, a rare earth exchanged ion type crystalline aluminosilicate, clay, an aluminum chlorhydroxide sol ( approximate formula:

  A12Cl (OH) 5) and water. The mixture was spray dried

  The proportion of the raw materials was such that the finished catalyst contained 20% of the SO 2 getter agent of Example 18, 12% of the crystalline type I ion aluminosilicate exchanged. rare earths, 54% clay and 14% alumina. The finished catalyst had a mean particle size of 116, with 65% by weight of

particles between 20 and 140 /.

EXAMPLE 21

  The process of Example 20 was repeated, but

  using the SOx getter agent of Example 19.

  In this example, the finished catalyst had a mean particle size of 77 / 4- with 87%

  particle weight between 20 and 149 μg.

EXAMPLE 22

  An alumina-bonded cracking catalyst was prepared by mixing the following materials: a rare earth ion exchanged ion (CRY) type crystalline aluminosilicate, clay, a chlorhydroxide sol

  aluminum (approximate formula: A12Cl (OH) 5) and water.

  The mixture was spray-dried and calcined for 2 hours at 538 C. The proportion of raw materials was such that the finished catalyst contained 12% of a crystalline ion exchange type Y aluminosilicate.

  rare earths, 78% clay and 10% alumina.

  The finished catalyst had a mean particle size of 71r with 97% by weight of particles between

and 149 / z.

  29.89 g (dry basis) of this alumina-bonded cracking catalyst were thoroughly mixed with 0.11 g (dry basis) of an oxidation catalyst containing 810 ppm platinum on a gamma carrier. alumina having a particle size in the fluidizable range.

EXAMPLE 23

  26.89 g (dry basis) of the cracking catalyst described in Example 22 was thoroughly mixed with 0.11 g (dry basis) of the oxidation catalyst, also described in Example 22. in this mixture which was well mixed, 3.00 g (dry basis) of a monohydrate

alpha-alumina marketed.

EXAMPLE 24

  26.89 g (dry basis) of the cracking catalyst described in Example 22 were thoroughly mixed with 0.111 g (dry basis) of the oxidation catalyst, also described in Example 22. this mixture, and was thoroughly mixed, 3.00 g (dry basis) of the composition

  of La 2 O 3 / Al 2 O 3 prepared in Example 2.

EXAMPLES 25-36

  The procedure of Example 24 was repeated but using, for the third component to be blended, the composition prepared in Example 3. Similarly, the process was repeated but with, for the third components, the compositions prepared at the same time. Examples 4, 5, 6, 7, 8, 9,

11, 12, 14, 15 and 17.

EXAMPLE 37

  29.89 g (dry basis) of the finished catalyst of Example 20 was thoroughly mixed at 0.111 g (dry basis)

  of the oxidation catalyst described in Example 22.

EXAMPLE 38

  29.89 g (dry basis) of the finished catalyst of Example 21 were thoroughly mixed at 0.111 g (dry basis)

  of the oxidation catalyst described in Example 22.

EXAMPLE 39

  A laboratory scale catalytic cracking unit was used to test the catalyst compositions for their ability to reduce carbon emissions.

Sox (SO2 + SO3) of the regenerator.

  Prior to testing in the laboratory unit, the catalysts or catalytic mixtures were steam-quenched with 100% steam at 1.03 bar and 732 ° C. for 8 hours. This steam deactivation simulates the deactivation that occurs in a commercialized catalytic cracking unit. The ability of a catalyst or catalytic mixture to reduce S x emissions in the laboratory test unit after this steam deactivation will be a measure of its ability to reduce SOx emissions in commercialized units . In contrast, the ability of a fresh or non-deactivated catalyst or catalytic mixture to reduce SOx emissions in a laboratory test is inconclusive with respect to the ability of the catalyst or catalyst mixture to be reduced. SOx emissions in commercial units, because the catalyst or catalyst mixture will be deactivated in the business unit shortly after being introduced into this unit, and may become ineffective

* for the reduction of emissions of S0.-

  In the laboratory unit, a low sulfur gas oil was cracked on the catalyst or

  catalytic mixture at a temperature of 5270C. The regeneration

  catalyst or catalytic mixture, that is,

  say the coke burning step, was performed with air at 6770C. The air used for the coke combustion stage contained 2,000 ppm SO 2. This is equivalent to the amount of SQ2 forming in the regenerator with a high sulfur gas oil used for the stage

cracking.

  The regenerated catalyst or catalyst mixture was then subjected to the cracking and steam extraction steps to release the SOs as H 2 S,

captured in the regenerator.

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

steam extraction.

  An SQx index, which gives the measurement of SOx captured in the regenerator and released into the reactor and the rectifier, can be defined by SOx index = sulfur content, sulfur content, percentage by weight, by weight, in the the catalyst-catalyst 1.000 or the catalytic mixture or mixture catalyzed after the step after the cracking and steam extraction regeneration steps

  A sample calculation for the catalytic mixture

  described in Example 31 and shown in Table I is

given below.

  S0 0 index = [(0.167) - (0.097) J 1000 = 70 It should be noted that the SQx index is a measure of the amount of SOX captured in the regenerator and released into the reactor and the rectifier. Catalyst or catalytic mixture capturing SOx in the regenerator

  but not releasing it into the reactor and rectifying

  will have an index of S0x of zero. Such catalyst or catalytic mixture will soon be saturated, probably after one or two cycles, to lose

  its effectiveness in reducing SOx emissions.

  For long-term efficiency, a catalyst or catalytic mixture must not only capture SQx in the regenerator but be able to release it into the reactor and the rectifier, thereby restoring

  its ability to repeat the process.

  The greater the Davison SQx Index, the greater the long-term effectiveness of the catalyst or mixture

  to reduce SOx emissions from the regeneration

  is important. As noted above, a Davison SOX index of zero means that the catalyst is not effective in the long run for reducing Sox emissions for the regenerator. At the other extreme, a SQx Davison index of 100 essentially means 100% efficiency, in the long run in reducing

  SQx emissions from the regenerator.

  The catalyst 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 SOx indices are given in Table I. A graphical representation of data from Table I (with the exception of the catalytic mixture described in Example 22 is shown in the single figure where the SOX index is represented as a percentage The curve shown in the figure indicates that the maximum index of S0, x is obtained when the getter agent of S0, x contains about 20% of La203. The data in Table I show that the maximum of the SOx index is obtained at concentrations

  La203 on Al203 above 12% and below

30% (Examples 32 and 34).

Table I

  Catalytic mixture SO index described in the example

22 10

23 18

26 42

34 58

35 70

31 69

32 56

33 44

EXAMPLE 40

  The catalyst mixtures described in Examples 37 and 38 were examined for their ability to reduce

  SOx emissions according to the process described in Example 39.

  The SQx indices obtained are given in Table II.

Table II

  Catalytic mixture SQ index described in Example x

37 46

38 58

EXAMPLE 41

  The catalyst mixtures of Examples 24, 25, 26, 27, 28 and 29 were examined for their ability to reduce SOx emissions according to the process described in Example 39. The Davison SOx indices obtained are given in US Pat.

Table III.

  The data in Table III show the effect of calcination on alumina hydrate prior to impregnation with La (NO 3) 3.6H 2 O solution. 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 10660C.

  Table III Effect of calcination of alumina before impregnation Catalytic mixture described in the example SOx index

24 32

35

26 42

27 35

28 29

29 36

EXAMPLE 42

  The cracking catalyst used in this example is a commercially available cracking catalyst containing 17% by weight of a rare earth ion exchanged ion (REY) crystalline aluminosilicate, 63% by weight of clay and 20% by weight a silica sol-alumina binder. 29.89 g (dry basis) of this cracking catalyst was thoroughly mixed at 0.110 g (dry basis) of an oxidation catalyst containing 810 ppm of platinum impregnated on a gamma-alumina support having a particles in the range that can be fluidized.

EXAMPLE 43

  26.89 g (dry basis) of the cracking catalyst described in Example 42 were thoroughly mixed with 0.11 g (dry basis) of the oxidation catalyst, also described in Example 42. to this mixture, 3.00 g (dry basis) of a marketed alpha-alumina monohydrate, and

we totally mixed.

EXAMPLE 44

  26.89 g (dry basis) of the cracking catalyst described in Example 42 were thoroughly mixed with 0.11 g (dry basis) of the oxidation catalyst, also described in Example 42. to this mixture, 3.00 g (dry basis) of the La 2 O 3 / Al 2 O 3 composition prepared with

  Example 9 and totally mixed.

EXAMPLE 45

  The catalyst mixtures described in Examples 42, 43 and 44 were examined for their ability to reduce

  SOx emissions according to the process described in Example 39.

  The SQx indices obtained are given in Table IV.

  The results show that the cracking catalyst of a silicalumin sol gave a SQx index of zero (Example 42). The use of alumina as a SQx getter agent gave an SQx index of 5 (Example 43). The use of an SQx g2tter agent composed of La 2 O 3 / Al 2 O 3 according to the invention gave a SOX value of 50 (Example 44), which represents an improvement.

  considerable compared to the use of alumina.

Table IV

  Catalytic mixture SO index described in Example x

42 0

43 5

44 50

EXAMPLE 46

  27.00 g (dry basis) of the cracking catalyst described in Example 22 were completely mixed at 3.00 g (dry basis) of the La 2 O 3 / Al 2 O 3 composition prepared in Example 9. This catalytic mixture was was examined for its ability to reduce SOx emissions by the process described in Example 39. The obtained SOx

  value of 48. This can be compared to a SQ-

  x 69 obtained for the catalytic mixture described in Example 31, containing an oxidation catalyst. This shows that the SOX getter agent according to the invention

  operates without the presence of an oxidation catalyst.

  This also shows that the presence of an oxidation catalyst increases the getter agent's ability to reduce SO 2 emissions.

Claims (31)

R E V E N D I C A T I 0 N S   1. Catalytic composition, characterized in that it contains: (a) a hydrocarbon cracking catalyst, and (b) a sulfur oxide getter agent which contains an alumina substrate coated with an oxide of lanthanum. 2. Composition according to claim 1, characterized in that the aforesaid alumina substrate contains from 5 to 50% by weight of lanthanum oxide. 3. Composition according to claim 1, characterized in that the abovementioned alumina has a surface area of the order of 45 to 450 m 2 / g and preferably of the order of 110 to 270 m 2 / g and contains approximately 12 at 30% by weight of lanthanum oxide.   4. Composition according to claim 1, characterized in that the aforesaid alumina is coated   essentially a monolayer of lanthanum oxide.   5. Composition according to claim 1, characterized in that the aforementioned alumina substrate is an alumina hydrate.   6.- Composition according to any one of   1 or 4, characterized in that the substrate of the above-mentioned alumina is calcined.   7. Composition according to claim 1, characterized in that the lanthanum oxide mentioned above is   incorporated with a mixture of rare earth oxides.   8. Composition according to claim 1, characterized in that the aforementioned cracking catalyst contains a crystalline zeolite mixed with a matrix of an inorganic oxide, said zeolite being selected from the group consisting of hydrogen and / or zeolite type X or type Y exchanged with rare earths, zeolites ZSM and mixtures thereof.   9. Composition according to claim 1, characterized in that the aforementioned cracking catalyst contains a crystalline zeolite mixed with a matrix which contains clay and / or alumina hydrate and a dried alumina sol. . 10. Composition according to claim 1, characterized in that the aforementioned catalytic composition contains from about 0.1 to 100 parts per million of a noble metal as oxidation catalyst, said oxidation catalyst being added to said catalyst composition in the form of a noble metal impregnated on a particulate inorganic oxide, and said oxidation catalyst is selected from the group consisting of platinum, palladium and mixtures thereof.   11. Composition according to claim 1, characterized in that the aforementioned lanthanum oxide is distributed on the surface of the aforesaid 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 g.etter agent are physically mixed with the particles of the aforementioned catalyst.   13. Composition according to claim 1, characterized in that the aforementioned agent is   embedded in the particles of the aforementioned catalyst.   14.- Composition according to claim 1, characterized in that it contains from about 0.5 to 60%   by weight of the g etter agent of sulfur oxides.   15.- composition of getter agent of sulfur oxides, characterized in that it contains alumina and lanthanum oxide distributed essentially in   a monolayer on the surface of said alumina.   16. A composition according to claim 15, characterized in that it contains from about 5 to 50% by weight of lanthanum oxide which is uniformly distributed on the surface of an alumina having a surface area of from minus 45 m2 / g and preferably of the order of 110 to 270 m2 / g and it contains about 12 to 20% by weight of lanthanum oxide.   17. The composition according to claim 16, characterized in that the lanthanum oxide mentioned above is   incorporated with a mixture of rare earth oxides.   18. A composition according to claim 16, characterized in that the lanthanum oxide mentioned above is   distributed on the surface of the alumina in monolayer.   19. A composition according to claim 15, characterized in that it has the form of microspheroidal particles having about 90% of the particles in the   range of diameters from 20 to 105?   20. Composition according to claim 15, characterized in that it is in the form of particles with about 90% of the particles in the range of diameters from 0.5 to 20 p. 21. A composition according to claim 15, characterized in that it has the form of particles having more than one millimeter in diameter.   22. The composition according to claim 15,   characterized in that it contains an oxidation catalyst   which is a noble metal oxidation catalyst, said oxidation catalyst being included in amounts between about 0.1 and 1000 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 an inorganic oxide particulate.   23. The composition as claimed in claim 15, characterized in that the abovementioned lanthanum oxide is distributed on the surface of the alumina in combination with an oxidation catalyst selected from the group consisting of   platinum, palladium and mixtures thereof.   24. A process for controlling the emissions of SOXY, characterized in that it consists in: (a) incorporating, into a reaction zone, a g.etter agent according to claim 15 to be combined with the sulfur oxides in said zone; ; (b) restoring or regenerating said sulfur-containing getter agent obtained in step (a). 25.- Process according to claim 24, characterized in that an oxidation catalyst is present in said area.   26.- Process according to.revendication 24, characterized in that the aforementioned agent getter is restored or regenerated by reduction and / or hydrolysis in   presence of a reducing agent and / or vapor.   27. The method as claimed in claim 24, characterized in that the regenerated getter agent or   restored is recycled to the reaction zone.   28. A process for the cracking of feedstocks   hydrocarbon containing organic sulfur compounds, characterized in that it comprises: (a) reacting hydrocarbon feedstocks containing organic sulfur compounds with the catalyst composition of claim 1 under conditions of catalytic cracking to obtain a combined stream of (b) to a catalytic hydrocarbon zone; (c) extracted to sulfur is water and oxides cracked product and a catalyst composition coke containing sulfur; passing said vapor extraction catalytic composition to remove extractable thereof, from the composition passing said catalytic composition a regeneration zone where the oxidized coke containing said carbon monoxide, carbon dioxide, sulfur, and said oxidation oxides; sulfur combine with said getter agent of said catalyst composition to form a sulfate or thermally stable sulfate compound; and (d) returning said regenerated catalyst composition obtained in step (c) to the reaction step (a) ? 501,531   and the vapor extraction step (b) wherein said sulfur-containing watch agent is reduced and hydrolyzed to produce volatile hydrogen sulphide which is recovered as a component of the stream of the cracked product and to restore or regenerate the getter agent that is recycled in the process.   29.- Process according to claim 28, characterized in that the aforementioned agent is incorporated   as a particulate additive.   30. The process as claimed in claim 29, characterized in that an oxidation catalyst is incorporated in the quantities required to obtain a desired level of oxidation of the carbon monoxide and / or of the sulfur oxide, said catalyst oxidation agent being selected from the group consisting of platinum, palladium and mixtures thereof, and is added in amounts of from about 0.1 to 1,000 parts per million by weight of a noble metal.   31.- Process according to claim 28, characterized in that H2S is recovered from the stream of cracked gas.