FR2512050A1 - IMPROVED FLUID CATALYTIC CRACKING METHOD AND METAL ACTIVATOR USED IN THIS PROCESS - Google Patents

Abstract

THE INVENTION RELATES TO THE CRACKING TECHNIQUE. IT CONCERNS A PROCESS FOR CRACKING A HYDROCARBON CONTAINING SULFUR IN WHICH A PERFECTED OXIDATION ACTIVATOR IS USED TO CONVERT SO TO SO, CONSISTING OF INTIMATE ASSOCIATION, PALLADIUM AND AT LEAST ONE OTHER METAL CHOSEN BETWEEN PLAUMTINA , IRIDIUM, RHENIUM AND RHODIUM. APPLICATION TO SO OXIDATION IN A FLUID CATALYTIC CRACKING PROCESS.

Description

Fluid catalytic cracking involves the

  catalytic decomposition of heavy hydrocarbons in

  fuels and lighter petrochemicals

  The conventional catalytic cracking plant (fluid catalytic cracking) comprises a hydrocarbon cracking zone and a catalyst regeneration zone. A particulate catalyst, generally containing a zeolite, alternates between the cracking zone where the hydrocarbon feedstock is cracked and a regeneration zone where the coke formed on the catalyst in the cracking zone is burnt off The combustion gases formed in the regeneration zone usually contain certain gases

  harmful substances which are considered as atmospheric pollutants

  For example, carbon monoxide is generally

  formed during the oxidation of coke (see United States Patent

  In addition, when the hydrocarbon feeds contain sulfur and / or nitrogen, the combustion gases usually contain

  the oxides of these elements in various amounts.

  The carbon monoxide present in the flue gas can be controlled by the addition of small

  quantities of an oxidation activator of the

  Bone, such as platinum (see U.S. Patent No. 4,072,600). Sulfur oxides can be controlled by including a sulfur sorbent, such as alumina, in the bulk mass. circulating, ie, in admixture with the cracking catalyst (See U.S. Patent No. 4,071,436). It has also been found that the inclusion of an oxidation enhancer of sulfur dioxide promotes the removal of sulfur from the flue gas by the sulfur sorption material

  (see U.S. Patent No. 4,115,250).

  So far, platinum has been one of the most effective

  among oxidation activators of sulfur dioxide.

  Although it is effective, this activator has the incon-

  to increase the amount of nitrogen oxides in the flue gas. As noted above, the

  platinum can also act as an oxidizing activator

  It would be advantageous to use, in the regeneration process, an oxidation promoter which would retain platinum efficiency in the activation of the oxidation promoter.

  oxidation of carbon monoxide and sulphate

  furious without contributing to the formation of nitrogen oxides. It has been discovered that certain metal mixtures containing palladium and at least one other metal selected from the group consisting of platinum, osmium,

  iridium, rhodium and rhenium could be used

  as an effective activator of the oxidation of carbon monoxide and sulfur dioxide while minimizing the formation of nitrogen oxides. The discovery that the efficiency with which these mixtures activate the oxidation of the sulfur dioxide is ordinarily

  greater than the efficiency of the individual metals used

  in the formation of the mixture, is even more

  equally remarkable is the discovery of

  This increase in the ability to activate oxy-

  sulfur dioxide is usually accompanied by significant reductions in the amount of nitrogen oxides

  formed, compared to platinum alone.

  Accordingly, the present invention relates to an improved process of fluid catalytic cracking

  wherein a circulating charge comprising a catalyst

  A particulate cracking system alternates between a hydrocarbon cracking zone and a catalyst regeneration zone, and the sulfur content of the gases leaving the regeneration zone is reduced by incorporating, into the circulating mass, a hydrogenation material. sorption of sulfur oxides, the improvement of

  in the regeneration zone, in association with a

  port formed of an inorganic oxide, an oxidation activator

  sulfur dioxide formed by the intimate combination of palladium or a palladium compound with at least one other metal or compound of a metal selected from the group consisting of platinum, osmium, iridium, rhenium and

rhodium.

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  The present invention further relates to a composition useful in cracking a sulfur-containing hydrocarbon in the absence of added hydrogen, which composition comprises: (a) a particulate cracking catalyst;

  intended to crack hydrocarbons in the absence of hydro-

  gene; (b) a first particulate solid material

  other than said particulate cracking catalyst

  taking a sulfur sorption material capable of

  kill the sorption of sulfur trioxide; and (c) a second particulate solid material

  other than the particulate cracking catalyst comprises

  an inorganic carrier oxide in combination with

  a metal mixture comprising palladium or a

  deposited with palladium and at least one other metal or a compound of this other metal selected from the platinum group,

  osmium, iridium, rhenium and rhodium.

  The present invention further relates to a composition useful in cracking a sulfur-containing hydrocarbon in the absence of added hydrogen, which composition comprises (a) a particulate cracking catalyst

  essentially formed of a cracking catalyst containing

  silica impregnated with an aluminum compound capable of sorbing sulfur oxides; and (b) a second particulate solid material

  other than the particulate cracking catalyst,

  taking an inorganic carrier oxide in combination with a metal mixture containing palladium or a palladium compound and at least one other metal or a compound of another metal selected from the group consisting of platinum,

  osmium, iridium, rhenium and rhodium.

  The term "circulating mass" refers to the particulate solids that alternate between the cracking zone and the regeneration zone. Thus, this expression includes, but is not necessarily limited to, the cracking catalyst, the particulate material, and

  Sulfur sorption and activator particles.

  The term "sulfur sorbent material" as used herein means a material capable of

  to form a stable association with sulfuric anhydride

  in the regenerator of a fluid catalytic cracking plant capable of dissociation in the hydrocarbon cracking zone. This combination can be formed by absorption, adsorption or by reaction.

  These sulfur sorbers include

  Most preferred is a "reactive alumina" which can be defined as an alumina having a specific surface area of at least 50 m 2 / g, for example gamma-alumina, or "alumina and magnesia". A suitable reactive alumina is not intimate combination with more than about 40% silica, and is preferably substantially non-reactive.

  mixed with silica We can find a description

  reactive alumina in the US Pat.

  United States of America No. 041,437, supra.

In the accompanying drawings

  Figure 1 is a graph comparing the

  study of various metals and various metal

  to activate the oxidation of sulfur dioxide and the formation of nitrogen oxides; and

  Figure 2 demonstrates in the form of a graphi-

  that the synergistic effect of various mixtures of palladium /

  platinum on the oxidation of sulfur dioxide.

  The present invention relates to an improved class of oxidation activators which are very effective for the conversion of sulfur dioxide to sulfur trioxide. In most cases, the oxidation activator can also serve as an activator of oxidation. oxidation for

  the conversion of carbon monoxide to car-

  This class of activators is particularly advantageous because the activators described in

  present memorandum may be made selective with respect to

  transformation of sulfur dioxide to sulfuric anhydride while minimizing the formation of nitrogen oxides The ratio of palladium to other metals varies according to the metals used and the mode of operation chosen when only one other metal is present in combination with palladium, the weight ratios of the two metals are in the range of about 1 to 1: 100, weight ratios of about 10: 1 to 1: Preferred for activating the oxidation of sulfur dioxide, activators containing palladium and iridium in the ratio of 10: 1 and palladium and platinum in the ratio of 10: 1 are particularly preferred. It is important that the metals are fixed

  on the support in the form of a mixture of these metals.

  It has been found that when the different metals are each placed on its own particles, the ability of these metals to activate the oxidation of sulfur dioxide

was significantly reduced.

  The medium used in conjunction with the

  can be any inorganic oxide that does not alter

  activity of the activator or the operation of the instru-

  Preferably, the carrier is a particulate solid material that can be physically mixed and circulated with the cracking catalyst and the sulfur sorbent material. Such materials include porous inorganic oxides such as alumina. and silica or mixtures of two or more inorganic oxides, for example silica-alumina, natural and synthetic clays, etc., crystalline zeolitic aluminosilicates, etc. A preferred carrier is a porous cracking catalyst which exhibits good attrition resistance in the fluid catalytic cracking plant to prevent loss of activator from the circuit. The Engelhard catalyst support HEZ-55 may be

  advantageously used as a support for the activator.

  The metals may be added to the support in any suitable manner, for example by impregnation or ion exchange, or they may be added to a precursor of a previously selected solid support, for example by coprecipitation in an aqueous solution with a precursor inorganic oxide In the case of a particulate activator support, the solid material

  particles can be transformed into particles of a dia-

  meter suitable for use in a fluid catalytic cracking system by conventional means,

  for example by spray drying, grinding of particles,

  larger particles to the desired diameter, etc. When incorporating the activator into the

  mass circulating in the catalytic cracking plant

  lytic fluid, a sufficient amount of activator

  be present to activate the oxidation of the sulphate

  In addition, if it is desired that the oxidation activator also serves as an activator for the conversion of carbon monoxide to carbon dioxide, a sufficient amount of activator must be present to facilitate this reaction. Generally, the amount of activator required to oxidize the carbon monoxide is less than the amount desired to oxidize the sulfur dioxide, so this is not normally a factor to consider. the activator constitutes about 0.01 to about 2% by weight of the activator-carrier combination and about 0.01 to about 100 parts per million by weight of the weight

total in circulation.

  The sulfur sorption material included in

  the circulating mass is preferably a reactive alumina

  However, other sulfur sorbents have been described and could be used in the present invention. In general, a suitable sulfur sorption material should be capable of carrying out the sorption.

  at least about 50% by weight of the sulfur oxides

  in the regeneration zone In the case of a reactive alumina, the particles of the sulfur sorption material

  usually contain at least 60% by weight of alumina.

  Alumina must have a surface area of at least 50 m 2 / g

  and contains about 0.1 to 100% by weight of reactive alumina.

  Sulfur sorption material is usually present

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  in sufficient amount with the catalyst to have about 0.1 to about 25% by weight of alumina based on the total circulation mass. Generally, the sulfur sorbent material is incorporated in the form of particulate solid material in physical mixture

  only with the particles of the catalyst and with the

  However, the sulfur sorbent may also be present on the catalyst particles as described in the US Pat.

  United States of America No. 4,115,249.

  The catalyst used in the cracking of the hydrocarbon feed may be any catalyst capable of being

  used in a fluid catalytic cracking plant.

  Such catalysts normally contain silica

  and / or alumina Other refractory metal oxides

  such as magnesia and zirconium oxide have been suggested and could be used, if appropriate.

  types of molecular sieves made of natural aluminosilicates

  The choice of catalyst is not critical to the invention. It is recognized that the choice of catalyst depends on the batch to be cracked and the mode of operation rather than the activator of the catalyst. Thus, the choice of catalyst is entirely within the skill of those skilled in the art and does not require

  more comments in this memo.

  Various other types of material may be included in the circulating mass of the fluid catalytic cracking facility provided that such materials

  do not significantly interfere with the activities of

  Other oxidation activators of carbon monoxide may be added, such as copper

  or chromium Sodium has also been used in combination with

  cation with alumina in the sulfur sorption material Moderate amounts of these materials are not

  not unfavorable to the implementation of the invention.

  Oxidation promoters containing a mixture of palladium and iridium (10: 1) and a mixture of palladium and rhodium (10: 1) are particularly advantageous for

  to combat the formation of nitrogen oxides We appreciate

  particularly the mixture of palladium and iridium (10: 1) which also showed excellent ability to oxidize sulfur dioxide to sulfur trioxide.

  Further details of the invention

  Various oxidation activators have been deposited by impregnation on an equilibrium HEZ-55 catalyst, and the ability of the individual metals to oxidize.

  sulfur dioxide to sulfur trioxide was determined

  indirectly by measuring the adsorption rate of sulfur trioxide over alumina The table shows

  the activity of three metal catalysts selected during

that they are used alone.

BOARD

  Metallic activator SO 3 adsorption rate (ppm / min 3 0.1% platinum 599 0.1% palladium 497 0.1% iridium 318 The table above shows that

  three metals, platinum is by far the best

  Oxidation The iridium shows very poor

at the activation of the oxidation.

  As already mentioned, the ability of metal mixtures of the type described herein to activate the selective oxidation of sulfur dioxide while minimizing the formation of oxides

  nitrogen offers a distinct advantage over

  oxidation type of the type described in the prior art.

  This advantage is clearly illustrated in FIG. 1, which represents the activity of the individual metals indicated in the table and various mixtures of metals within the scope of the invention. FIG. 1 shows that all the metal mixtures which have been tested have an improved activity as sulfur dioxide activators, compared to the individual metals used to prepare the mixture It should be noted at the same time that the metal mixtures have significantly reduced the amount of nitrogen oxides formed, compared at platinum when used alone All the results obtained were obtained with a total of 0.1% by weight of metal on the support The abscissa axis carries the amounts of nitrogen oxides produced during the regeneration - catalyst ration and the ordinate axis indicates the

absorption rate of So 2.

  Particularly active oxidation inhibitors of sulfur dioxide come out of mixtures of

  palladium and iridium (10: 1) and palladium

dium and platinum (10: 1).

  Figure 2 of the accompanying drawings illustrates, comparatively, the effect of various palladium: platinum ratios on oxidation activation of sulfur dioxide. The abscissa indicates the catalyst composition (Pd%) and the axis ordinates carry the absorption rates of SOL It emerges from this figure that the various mixtures of platinum and palladium show a true synergistic effect, that is to say that the mixture shows a greater activation of oxidation than Mon

  or the other of the metals used alone

  The maximum oxidation ratio is obtained for a palladium: platinum ratio of about 1: 1, it is usually economically desirable to operate with less platinum in the mixture than the optimal amount. high price of platinum compared to that

palladium.

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Claims (12)

  An improved process for catalytic cracking   fluid in which a circulating mass comprising a particulate cracking catalyst alternates between a hydrocarbon cracking zone and a regeneration zone.   of the catalyst and the sulfur content of the   both of the regeneration zone is influenced by the   corporation of a sulfur oxides sorption material   to the mass in circulation, characterized in that   is to provide in the regeneration zone   in combination with an inorganic carrier oxide, an oxidation activator of sulfur dioxide formed by the intimate combination of palladium or a palladium compound with at least one other metal or a compound of another metal chosen from the group comprising platinum,   osmium, iridium, rhenium and rhodium.   Process according to claim 1, characterized   characterized in that the sorption material of the sulfur oxides consists of separate particles in physical mixture with the cracking catalyst.   The process according to claim 1, wherein   characterized in that the oxidation activator of sulfur dioxide also serves as an oxidation activator of carbon monoxide.   Process according to claim 1, characterized   characterized in that the inorganic carrier oxide is a particulate solid material which can be mixed with the circulating mass and alternates between the   cracking and the regeneration zone.   The process of claim 1, wherein   characterized in that the oxidation activator of sulfur dioxide is a combination of palladium or a palladium compound and another metal or a compound of a other metal.   Process according to claim 5, characterized   characterized in that the other metal is platinum, iridium or rhodium, the metals being preferably present in a ratio of percentages by weight included in the 2512 O Si O   range from about 10: 1 to about 1:10.   Process according to claim 4, characterized   in that the total metal content of the activa-   is in the range of about 0.01 to about 2% by weight and is about 0.01 to about 100 parts   per million by weight of the cracking catalyst.   Process according to claim 4, characterized   characterized in that the support is a cracking catalyst   porous amorphous abrasion resistant.   9 Composition useful in cracking a hydro-   carbide containing sulfur in the absence of added hydrogen, characterized in that it comprises: (a) a particulate cracking catalyst   for cracking hydrocarbons in the absence of hydro-   gene; (b) a first particulate solid material   other than the particulate cracking catalyst comprises   a sulfur sorption material capable of   kill the sorption of sulfur trioxide; and (c) a second particulate solid material   other than the particulate cracking catalyst comprises   an inorganic carrier oxide in combination with a metal mixture containing palladium or a palladium compound and at least one other metal or a compound of this other metal selected from the group consisting of platinum,   osmium, iridium, rhenium and rhodium.   Composition according to Claim 9,   characterized in that the first solid material in particular   ticules contains about 0.1 to 100% by weight of alumina reactive.   Composition according to Claim 9,   characterized in that the second solid material in particular   cules contains palladium or a palladium compound and another metal or a compound of another metal, and the total metal content of the second particulate solid material is in the range of about 0.01 to about 2% by weight and constitutes about 0.1 to about 100 parts   per million by weight of the cracking catalyst.   Composition according to Claim 11, characterized in that the other metal is platinum, iridium or rhodium, the metals being preferably present in a ratio of percentages by weight in the range of about 10: 1 to about 1:10.   13 Composition useful in cracking a hydro-   carbide containing sulfur in the absence of added hydrogen, characterized in that it comprises (a) a particulate cracking catalyst   essentially formed of a cracking catalyst containing   silica impregnated with an aluminum compound capable of sorbing sulfur oxides; and (b) a second particulate solid material   other than the particulate cracking catalyst comprises   an inorganic carrier oxide in combination with palladium or a palladium compound and at least one other metal or a compound of another metal selected from the group consisting of platinum, osmium, iridium, rhenium and rhodium.