RU2793858C1 - Method for fluidized cracking to increase yield of olefins and intended catalytic composition - Google Patents

Abstract

FIELD: cracking process.

SUBSTANCE: fluidized cracking method and a composition of a regenerated catalyst. A fluidized cracking process is presented, comprising contacting a hydrocarbon feed with a circulating available amount of regenerated fluid catalytic cracking catalyst to form a product flow, where the regenerated fluid catalytic cracking catalyst in the available amount has a carbon content in the range from 0.005 to 0.30% by weight, based on the total amount of the regenerated catalyst composition available, and contains a pentasil-containing catalyst/additive composition that contains a pentasil zeolite; from 0.7 to 4.0% by weight of iron oxide; and from 5.0 to 20% by weight of phosphorus (calculated as P₂O₅); where the amounts of iron oxide and phosphorus are given based on the % by weight of composition of the pentasil-containing catalyst/additive. In another implementation, a regenerated catalyst composition is provided in an available amount of circulating catalyst in a fluidized cracking process, wherein the regenerated catalyst has a carbon content in the range of 0.005 to 0.30% by weight, based on the total amount of catalyst available, and contains a pentasil-containing composition of a catalyst/additive that contains pentasil zeolite; from 0.7 to 4.0% by weight of iron oxide; and from 5.0 to 20% by weight of phosphorus (calculated as P₂O₅); where the amounts of phosphorus and iron oxide, respectively, are given based on the amount of phosphorus and iron oxide in the pentasil-containing catalyst/additive composition.

EFFECT: increased yield and selectivity for light olefins.

30 cl, 4 dwg, 6 tbl, 8 ex

Description

RELATED APPLICATIONS

[0001] This application is based on and claims priority on US Provisional Application No. 62/872468, dated July 10, 2019, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] Fluid catalytic cracking (FCC) generally refers to a process in which high boiling, high molecular weight hydrocarbon compounds contained in hydrocarbon feedstocks such as crude oil are converted into higher value products such as gasoline, diesel fuel and light olefins. During the process, a hydrocarbon feed is fed into a fluidized bed reactor and combined with a catalyst at high temperatures, resulting in the conversion of high molecular weight hydrocarbons to lower molecular weight products.

[0003] The product stream resulting from the fluid catalytic cracking process typically contains the highest amounts of hydrocarbons. The amount of light olefins such as propylene and ethylene produced during the process may depend on various factors. Recently, the demand for propylene as an important raw material for the production of a wide range of chemicals and polymers has increased dramatically. Despite significant investment in propylene production capacity, global supply continues to lag behind demand for light olefins. For example, the use of polypropylene polymers remains one of the fastest growing applications of synthetic materials in new and existing applications.

[0004] In view of the foregoing, those skilled in the art have attempted to modify the fluid catalytic cracking process to increase the yield of light olefins, such as the yield of propylene. For example, US Patent Publication No. 2009/0134065, which is incorporated herein by reference, describes a fluidized catalyst composition that increases olefin yield compared to other commercially available catalysts. The catalyst composition described in the '065 application has made significant progress in the production of light olefins such as propylene.

[0005] Light olefins such as propylene and ethylene are important feedstocks used in the production of a wide variety of chemicals and products, including various polymers. Despite significant investment in light olefin production capacity, the supply of light olefins has not matched demand. Therefore, there remains a need for further improvements in the development of FCC processes and catalyst and/or additive compositions to produce hydrocarbon products with increased yield and selectivity for light olefins.

SUMMARY OF THE INVENTION

[0006] The present invention relates to an improved process for producing light olefin products from a fluid catalytic cracking process, wherein the process increases the yield of light olefins, i. C2-C4 olefins compared to known commercially available FCC process. Preferably, the process also improves selectivity for C2 and C3 olefins. The present invention also relates to an improved FCC catalyst composition and/or additive and their use in an FCC process to improve yield and selectivity for C2 and C3 olefins over C4 olefins.

Accordingly, the present invention relates to the FCC method of the invention, where the method includes:

(a) introducing a hydrocarbon feed into a fluid catalytic cracking unit (FCCU) reaction zone, consisting of a reactor (also known as a "lift reactor"), a stripper, and a regenerator, in which the feed is characterized as having an initial boiling point of about 30° C with end temperatures up to about 850°C;

(b) catalytically cracking said feedstock in said riser reactor at a temperature of from about 400°C to about 700°C by contacting the feedstock with a circulating available amount of regenerated catalyst containing a pentasil-containing catalyst/additive composition, which includes:

(i) a pentasil zeolite having a silica/alumina skeleton,

(ii) at least 5.0% by weight of phosphorus (P ₂ O ₅ ) and

(iii) from about 0.7 to about 4% by weight of iron oxide (Fe ₂ O ₃ ); where the percentage of phosphorus and iron oxide is given based on the total amount of phosphorus or iron oxide in the composition of the pentasil-containing catalyst/additive; where the regenerated catalyst contains carbon from about 0.005 to about 0.30% by weight, based on the total weight of the amount of catalyst available;

(c) desorbing the recovered spent catalyst particles in the available amount of catalyst with stripping steam in the stripper to remove some of the hydrocarbonaceous material or coke therefrom;

(d) recovering the stripped hydrocarbons from the stripper and circulating the stripped catalyst particles to a regenerator;

(e) regenerating said cracking catalyst particles in a regeneration zone by burning a significant amount of coke on said catalyst particles at a temperature sufficient to obtain a carbon content of about 0.30% by weight or less of the total amount of regenerated catalyst available;

(f) recycling said available amount of regenerated catalyst to the reactor to continue the cracking process.

[0007] The pentasil-containing catalyst/additive composition can be used in the available amount of the FCC process catalyst of the invention as the sole catalyst or as an additive. In addition, the pentasil-containing catalyst/additive composition can be used in combination with individual conventional FCC catalyst particles not containing pentasil zeolite, for example, a faujasite zeolite-containing FCC catalyst.

[0008] As described above, it was found that the method of the present invention significantly increases the yield of light olefins. For example, the product stream may contain propylene in an amount of from about 4.5% by weight to about 40% by weight. The product stream may also contain ethylene in an amount of from about 0.5% by weight to about 25% by weight.

[0009] The present invention also relates to a regenerated fluidized catalyst composition comprising a pentasil-containing catalyst/additive composition that, when recycled to a fluidized cracking process, produces hydrocarbon products having increased yield and light olefin selectivity.

[0010] In one embodiment, the pentasil-containing catalyst/additive composition used in the available amount of regenerated catalyst contains at least 10% of the mass. pentasil zeolite such as ZSM-5, about 4.0% by weight or less, preferably about 2.5% by weight or less, iron oxide, and about 20% by weight, preferably about 19% by weight or less, more preferably about 18% by weight or less, but at least about 5% by weight or more, of phosphorus (measured as P ₂ O ₅ ).

[0011] The available amount of regenerated catalyst used in the process of the invention contains carbon in an amount of less than about 0.30% by weight, preferably less than about 0.25% by weight, more preferably less than about 0.20%. by weight, even more preferably less than about 0.15% by weight, most preferably less than about 0.1% by weight, but in any case not less than about 0.005% by weight of carbon of the total available amount of catalyst.

[0012] Other features and aspects of the present invention are discussed in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A full and detailed disclosure of the present invention is set forth in more detail in the remainder of the description with reference to the accompanying drawings, in which:

Figure 1: Indicates the effect of the level of iron oxide in the catalyst on the stability of specific surface area under propylene vapor cycling (CPS) conditions. The loss of stability of the specific surface area is observed with a gradual increase in the content of iron oxide in the catalyst.

Figure 2: Shows the specific surface area of the catalyst modified with iron oxide after 24 hours of hydrothermal deactivation. With a gradual increase in the content of iron oxide in the catalyst, no loss of specific surface area was observed.

Figure 3: Shows less than 0.30% of the mass. carbon on the regenerated catalyst; the sample modified with iron oxide has a higher propylene activity compared to the sample not modified with iron oxide. Above 0.30% wt. carbon on the catalyst propylene activity drops significantly.

Figure 4: Shows that at all levels of coke on the catalyst, iron oxide modified catalysts have higher selectivity for ethylene+propylene at constant total wet gas (hydrogen+C1-C4 hydrocarbons) compared to the base catalyst without iron oxide in the catalytic compositions.

DEFINITIONS

[0014] The weight % of iron and phosphorus used herein are based on the amount of each of the above components contained in the particles of the pentasil-containing catalyst/additive. The amount of iron in the particles of the pentasil-containing catalyst/additive is measured as iron oxide, and the amount of phosphorus contained in the particles of the pentasil-containing catalyst/additive is measured as P ₂ O ₅ .

[0015] The term "average particle size" is used herein to refer to the average relative amount, by volume, of particles present according to size in a sample measured by a laser diffraction technique. The equipment used is the Mastersizer 3000, available from Malvern P Analytical, which uses a laser diffraction technique to measure the particle size distribution.

[0016] The term "catalytic cracking activity" is used herein to refer to the ability of a catalyst to reduce higher molecular weight (high boiling) hydrocarbon feedstocks to lower molecular weight (lower boiling) hydrocarbon products.

[0017] The term "fluid catalytic cracking conditions" is used herein to refer to the operating conditions used to contact hydrocarbon feedstock and catalyst particles, such as contact time, temperature, and catalyst/oil ratio, to reduce higher molecular weight (high-boiling) hydrocarbon feedstocks. into lower molecular weight (low boiling) hydrocarbon products, during the fluidized catalytic cracking process.

[0018] The term "coked catalyst" is used herein to refer to the FCC cracking catalyst that exited the riser and stripper during the FCC process. The coked catalyst is regenerated in a "regenerator" before it is recycled to the riser reactor in the FCCU during the cracking process.

DETAILED DESCRIPTION

[0019] A person skilled in the art should be clear that the present discussion is a description of examples of implementation only and is not intended to limit the broader aspects of the present invention.

[0020] The present invention relates to a fluid catalytic cracking process that improves the yield of light olefins such as propylene, ethylene and butylene, as well as increases the selectivity for C2 and C3 olefins. In general, the method relates to using an available amount of regenerated catalyst having a reduced carbon content and containing particles of a phosphorus stabilized pentasil zeolite-containing catalyst/additive having a low iron oxide content, wherein said available amount of regenerated catalyst has a reduced carbon content. It has been found that the yield of light olefins can be significantly increased not only by maintaining relatively low amounts of iron in the pentasil-containing catalyst/additive composition, but also by maintaining the iron in an oxidized state by minimizing reducing agents such as carbon, generally available in the presence of the amount of regenerated catalyst.

Pentasil Catalyst/Additives

[0021] Suitable zeolites for use in the pentasil-containing catalyst/additive composition suitable in the present invention include zeolite structures that have a five-membered ring in the structural framework. The framework contains silicon dioxide and alumina in tetrahedral coordination. In one embodiment, the catalyst composition contains one or more pentasils having a ZSM-5 or ZSM-11 x-ray diffraction pattern. Commercially available synthetic shape selective zeolites are also suitable.

[0022] Pentasil zeolites typically have a permeability index of 1-12. Details of the permeability test are given in J. Catalysis, 67, 218-222 (1981) and US Pat. No. 4,711,710. Such pentasils are exemplified by medium pore zeolites, for example those zeolites having pore sizes from about 4 to about 7 angstroms. The pentasil may have a silica to alumina (SiO ₂ /Al ₂ O ₃ ) molar ratio, eg less than 300:1, such as less than 100:1, eg less than 50:1. In one embodiment, pentasil has a silica to alumina ratio of less than 30:1. Pentasil can also be exchanged with metal cations. Suitable metals include alkaline earth metals, transition metals, rare earth metals, phosphorus, boron, noble metals, and combinations thereof.

[0023] The catalyst/additive particles typically contain pentasil zeolite in an amount generally sufficient to increase the yield of light olefins. Typically, the pentasil zeolite catalyst/additives contain pentasil in the range of from about 10% to about 80%, preferably from about 20% to about 70% by weight, most preferably from about 40% to about 60% by weight of the pentasil zeolite in the catalyst composition. /additives.

Phosphorus

[0024] The pentasil-containing catalyst/additive composition typically contains phosphorus (measured as P ₂ O ₅ ) in an amount of less than about 20% by weight and typically more than about 5% by weight of phosphorus, when measured as phosphorus pentoxide. For example, phosphorus may be present in an amount of more than about 7% by weight, for example, in an amount of more than about 9% by weight, for example, in an amount of more than about 11% by weight, and usually in an amount of less than about 18% by weight. .

[0025] The phosphorus used is chosen to stabilize the pentasil zeolite in the catalyst/additive composition and, in combination with other ingredients, to act as a binder. It is measured as phosphorus pentoxide (P ₂ O ₅ ). Without wishing to be bound by any particular theory, it is believed that the phosphorus reacts with the acid sites of the pentasil alumina, thereby stabilizing the site against any dealumination that may occur during use under typical fluid catalytic cracking conditions or even more. harsh conditions. Thus, phosphorus stabilizes the activity of pentasil in relation to the conversion of hydrocarbon molecules in the range of naphtha and, thereby, increases the yield of olefins in FCC processes. Phosphorus can be added to the pentasil before, during or after the formation of the catalyst/additive particles containing pentasil. Phosphorus-containing compounds suitable as a source for this invention include phosphoric acid (H ₃ PO ₄ ), phosphorous acid (H ₃ PO ₃ ), salts of phosphoric acid, salts of phosphorous acid, and mixtures thereof. Ammonium salts such as monoammonium phosphate (NH ₄ )H ₂ PO ₄ , diammonium phosphate (NH ₄ ) ₂ HPO ₄ , monoammonium phosphite (NH ₄ )H ₂ PO ₃ , diammonium phosphite (NH ₄ ) ₂ HPO ₃ and mixtures thereof can also be used. . Other compounds include phosphines, phosphonic acid, phosphonates, and the like.

[0026] Phosphorus is added in amounts during the preparation of the catalyst/additive composition such that, based on particles containing pentasil, the amount of phosphorus can range from about 5 to 20% by weight, preferably from about 7 to about 19% by weight. by weight, and even from about 9 to 18% by weight, or from about 11 to 18% by weight.

iron oxide

[0027] The iron present in the pentasil-containing catalyst/additive composition is measured as iron oxide. In general, the catalyst/additive composition contains iron oxide in an amount of about 4% by weight or less, for example, in an amount of about 3.0% by weight or less, for example, in an amount of about 2.5% by weight or less, for example, in an amount of about 2.3% by weight or less, for example, in an amount of about 2% by weight or less, for example, in an amount of about 1.8% by weight or less. Iron oxide is typically present in an amount greater than about 0.7% by weight, such as greater than about 0.9% by weight, based on the total amount of iron oxide in the pentasil-containing catalyst/additive composition. Typically, the amount of iron oxide is in the range from about 0.7% to about 4.0% by weight, preferably from about 0.9% to about 3% by weight, even from about 0.9% to about 2.5 % by weight, based on the amount of the pentasil-containing catalyst/additive composition.

[0028] The amounts of iron or iron oxide may come from the matrix, zeolite, binder, or clay that may be present in the pentasil-containing catalyst/additive composition. Therefore, iron is usually found in the catalyst matrix or binder, and is also found in the pore structure of pentasil. The iron may be present outside or inside the pentasil framework. By "outside the framework of pentasil" is meant iron that is outside the coordinates of the tetrahedral structure of silicon dioxide/alumina. The iron may include iron bound to the acid site of the backbone, for example, in the form of an exchanged cation at that site. Iron may be present on the outside of the pentasil zeolite, ie. in the matrix included in the composition of the pentasil-containing catalyst/additive.

[0029] Indeed, the iron specified as a component of the pentasil-containing catalyst/additive is usually iron that is added alone and in combination with other raw material used to obtain the catalyst/additive composition. Although iron is described here as iron oxide (ie, Fe ₂ O ₃ ), it is also believed that iron in the composition may exist in other forms, such as iron phosphate. However, the actual form depends on how the iron is introduced into the catalyst/additive composition. For example, the iron may be in the form of iron oxide in embodiments in which the iron is added in the form of insoluble iron oxide. On the other hand, if iron is added as a water-soluble salt, iron may react with an anion to form, for example, iron phosphate when iron halide is added to a spray dryer mixture containing phosphoric acid. However, iron oxide was chosen to reflect the proportion of iron in the composition in large part because the analytical methods commonly used in the industry to measure the content of iron and other metals typically report their results in terms of their oxides.

Optional Components

[0030] In addition to iron oxide and phosphorus, the pentasil-containing catalyst/additive composition contains additional components such as clay and a suitable matrix and, optionally, binders.

[0031] The amount of matrix present in the catalyst/additive composition can vary widely. The matrix component may be present in the catalyst composition in amounts ranging from 0 to about 60 wt%. The matrix is typically an inorganic oxide which has activity towards the modified FCC process product, and in particular activity to form naphtha range olefin molecules, which the pentasils described above can act on. Suitable inorganic oxides as a matrix include, without limitation, non-zeolitic inorganic oxides such as silica, alumina, silica-alumina, magnesium oxide, boron oxide, titanium dioxide, zirconia, metal phosphates, and mixtures thereof. In some embodiments, the implementation of the matrix contains alumina in an amount of from about 10 to about 50 wt% of the entire catalyst/additive composition. In other embodiments, the implementation of the matrix contains alumina in an amount of more than about 3% by weight and in an amount of less than about 10% by weight.

[0032] The pentasil-containing catalyst/additive composition may include one or more of various known clays such as montmorillonite, kaolin, halloysite, bentonite, attapulgite, and the like. Other suitable clays include clays that are leached with acid or base to increase the specific surface area of the clay, eg, increase the specific surface area from about 50 to about 350 m ² /g as measured by BET.

[0033]Suitable clays also include iron-bearing clays, sometimes referred to as hard kaolin clays or "grey" clays. The latter term is sometimes used because these hard kaolin clays have a gray tint or coloration. Hard kaolin clays are reported to have a significant iron content, typically from about 0.6 to about 5 wt%. Fe₂O₃. In embodiments containing gray clays, their iron content may be included as part of the iron oxide used. However, given the amount of iron commonly used and the fact that the iron in these clays is in a form that is not always easily reactive, it would be preferable to use additional sources of iron.

[0034] Matrix and clays are typically provided and included in the catalyst/additive composition when formulated as particulates. When formulated from a mixture of pentasil-containing particles, the matrix may have a specific surface area of at least about 5 m ² /g, preferably from about 15 to about 130 m ² /g. The specific surface area of the matrix can be measured by t-plot analysis based on ASTM 4365-95. The total specific surface area of the catalyst/additive composition is in most cases at least about 50 m ² /g, either fresh or treated at 816° C. for 4 hours with 100% steam. The total specific surface area can be measured using BET.

[0035] Suitable materials for optional binders include inorganic oxides such as alumina, silica, silica-alumina, aluminum phosphate, as well as other metal phosphates known in the art. Aluminum chloride can also be used as a binder. When using metal phosphate binders other than aluminum phosphate, the metal may be selected from the group consisting of Group IIA metals, lanthanide series metals including scandium, yttrium, lanthanum, and transition metals. In some embodiments, Group VIII metal phosphates are suitable. In one embodiment, the fresh pentasil catalyst/additive composition used to form the regenerated catalyst is provided as an aqueous slurry containing various ingredients, e.g., pentasil zeolite, phosphorus and iron oxide, clay, optional matrix materials in the amounts described herein above. . For example, in one embodiment, the aqueous slurry may contain pentasil zeolite, iron oxide, phosphate, alumina, and/or clay. The resulting aqueous suspension is stirred well and then spray dried.

[0036] Other methods for preparing a pentasil-containing catalyst/additive composition include, without limitation, the following general processes:

[0037] (1) Ion exchange or impregnation of the selected pentasil zeolite with iron and incorporation of the ion exchange or impregnation zeolite into the optional components mentioned previously and formation of a catalyst/additive composition.

[0038] (2) Simultaneously combining the iron source with the pentasil zeolite and additional components and forming the desired catalyst/additive composition.

[0039] (3) Manufacture of a pentasil-containing catalyst in a conventional manner, for example, forming a pentasil composition containing the pentasil zeolite and the optional components mentioned above, and subjecting the formed catalyst particles to ion exchange to incorporate iron.

[0040] (4) Preparation of a conventional catalyst/additive composition as described in (3), except that the particles of the pentasil-containing catalyst/additive are impregnated, for example, by the initial moisture method, with an iron precursor to incorporate iron.

[0041] In one embodiment, after combining the exchange pentasil zeolite (1) with optional components in water, the resulting slurry can be spray dried into particles having an average particle size in the range of from about 20 to about 200 microns, for example, from 20 to about 100 μm, and the resulting catalyst/additive composition is then processed under normal conditions.

[0042] The source of iron in any of the above methods may be in the form of an iron salt and includes, without limitation, iron halides such as chlorides, fluorides, bromides and iodides. Iron carbonate, sulfate, phosphates, nitrates and acetates are also suitable sources of iron. The source of iron may be water-based, and the iron may be present in the exchange solution at concentrations of from about 1% to about 30%. When introducing iron by the exchange method, the exchange can be carried out in such a way that at least 10% of the exchange centers present in the zeolite are exchanged with iron cations. Iron can also be incorporated using solid phase exchange methods.

[0043] When impregnating a pentasil zeolite or a catalyst/additive containing a pentasil zeolite using method (1) or method (4), an iron source, usually in an aqueous solution, is added to the pentasil zeolite powder or catalyst particles until the initial moisture is reached. Iron concentrations for typical impregnating baths are in the range of 0.5-20%.

[0044] The source of iron for methods (1) and (2) can also be forms of iron, such as iron oxide, and such sources are not necessarily soluble, and/or their solubility depends on the pH of the medium to which the iron source is added.

[0045] The matrix and binder may be added to the pentasil zeolite mixture as dispersions, solids, and/or solutions. A suitable clay matrix contains kaolin. Suitable dispersible sols include alumina sols and silica sols known in the art. Suitable alumina sols are those obtained by peptizing alumina using a strong acid. Particularly suitable silica sols include ^Ludox® colloidal silica, available from WR Grace & Co.-Conn. Some binders, such as those formed from binder precursors such as aluminum chlorohydrol, are formed by introducing solutions of the binder precursors into a mixer and the binder is then formed during a spray drying process and/or further processing, such as calcination.

[0046] The final pentasil-containing catalyst/additive composition preferably has attrition resistance suitable to withstand the conditions typically used in FCC processes. Catalysts having these properties are often prepared using the Davison Attrition Index (DI). The lower the DI, the more attrition resistant the catalyst is. Commercially acceptable abrasion resistance is described by a DI of less than about 20, preferably less than 10, and most preferably less than 5.

Regenerated Catalyst

[0047] Once the pentasil-containing catalyst/additive composition is obtained, the composition can be used to make 100% of the available amount of catalyst, or it can be added to the available amount of catalyst as an additive, for example, as a "additive for light olefins" , or it may be combined with individual conventional FCC cracking catalyst particles and/or additives that do not contain pentasil zeolite to form an available amount of cracking catalyst. Typically, the pentasil-containing catalyst/additive composition may contain from about 0.5% to about 99%, such as from about 1% to about 60%, such as from about 1% to about 30%, by weight of the total amount of catalyst available.

[0048] A conventional FCC catalyst may comprise any FCC catalyst composition containing additional zeolites having catalytic cracking activity in the liquid hydrocarbon conversion process other than pentasil zeolites and conventional components such as clays, matrix, binder, etc. Typically, the additional FCC catalyst particles will contain a large pore zeolite having a pore structure with openings of at least 0.7 nm.

[0049] Suitable large pore zeolites include crystalline aluminosilicate zeolites such as synthetic faujasite, ie. zeolites type Y, zeolites type X and beta zeolite, as well as their heat-treated (calcined) and/or exchangeable rare earth derivatives. Zeolites that are particularly suitable include calcined exchange rare earth type Y zeolite (CREY), ultra stable type Y zeolite (USY), as well as various partial exchanged type Y zeolites. Other suitable large pore zeolites include MgUSY, ZnUSY, MnUSY, P-USY, HY, REY, CREUSY, REUSY zeolites and mixtures thereof. The zeolite can also be mixed with molecular sieves such as SAPO and ALPO.

[0050] Standard type Y zeolite is produced commercially by crystallization of sodium silicate and sodium aluminate. This zeolite can be converted to a USY type zeolite by dealumination, which increases the silicon/aluminum atomic ratio of the original structure of the standard Y type zeolite. The dealumination can be carried out by steam calcination or by chemical treatment. An additional zeolite-based cracking catalyst can also be formed from clay microspheres that have been "zeolitized" in situ to form zeolite Y. Briefly, zeolite Y is formed from calcined clay microspheres by contacting the microspheres with a caustic solution at 180°F (82°C) . See "Commercial Preparation and Characterization of FCC Catalysts", Fluid Catalytic Cracking: Science and Technology , Studies in Surface Science and Catalysis, Vol. 76, p. 120 (1993).

[0051] Exchangeable rare earth zeolites that can be used are obtained by ion exchange, during which the sodium atoms present in the structure of the zeolite are replaced by other cations, usually in the form of mixtures of salts of rare earth metals, such as salts of cerium, lanthanum, neodymium, i.e. e. rare earth metals common in nature and their mixtures, to obtain REY and REUSY types, respectively. These zeolites can be further processed by calcination to obtain the above CREY and CREUSY types of material. MgUSY, ZnUSY, and MnUSY zeolites can be formed using metal salts of Mg, Zn, or Mn, or mixtures thereof, in the same manner as described above for the formation of REUSY, except that magnesium, zinc, or manganese salts are used in place of the rare earth salt. metal to form REUSY.

[0052] The unit cell size of the preferred fresh Y-zeolite is from about 24.35 to 24.7 Å. The unit cell size (UCS) of a zeolite can be measured by X-ray diffraction analysis according to ASTM D3942 procedure. There is usually a direct relationship between the relative amounts of silicon and aluminum atoms in a zeolite and its unit cell size. While both the zeolite itself and the fluidized cracking catalyst matrix typically contain both silica and alumina, the SiO ₂ /Al ₂ O ₃ ratio of the catalytic matrix should not be confused with that of the zeolite. When an equilibrium catalyst is subjected to X-ray diffraction analysis, only the UCS of the crystalline zeolite contained therein is measured.

[0053] The unit cell size value of zeolite Y also decreases as it is exposed to the FCC regenerator environment and reaches equilibrium by removing aluminum atoms from the crystal structure. Thus, when using zeolite Y in the available amount of FCC catalyst, the Si/AI atomic ratio in its lattice increases from about 3:1 to about 30:1. The size of the unit cell decreases accordingly due to the contraction caused by the removal of aluminum atoms from the cell structure. The unit cell size of the preferred equilibrium zeolite Y is at least 24.22 Å, preferably 24.24 to 24.50 Å, and more preferably 24.24 to 24.40 Å.

[0054] In general, the amount of non-pentasyl zeolite present in conventional FCC catalyst particles will be sufficient to produce gasoline cut olefin molecules. For example, the additional FCC catalyst composition may contain from about 1 to about 99.5% by weight of a zeolite other than pentasil, such as a Y-type zeolite, with specific amounts depending on the amount of activity desired. More typical embodiments contain from about 10% to about 80%, and even more typical embodiments contain from about 13% to about 70% additional zeolite.

[0055]

The conventional FCC catalyst may be present in the regenerated catalyst in an amount sufficient to provide the desired cracking activity. Typically, conventional FCC will be present in the regeneration catalyst in amounts ranging from about 0.5% to about 99% by weight, preferably from about 40% to about 99% by weight, most preferably from about 70%. up to about 99% by weight of the total regenerated catalyst.

Obtaining a regenerated catalyst

[0056] The regenerated catalysts used in the present invention are prepared by forming the initial available amount of fluidizable catalyst using conventional means such that the available amount includes the required amount of the pentasil-containing catalyst/additive composition and optional individual particles of conventional FCC catalyst and /or additives, and by recycling the available amount of catalyst through the FCCU to obtain a coked catalyst. The coked catalyst is then recycled to the FCCU regenerator under conditions sufficient to provide an available amount of regenerated catalyst containing carbon in an amount of less than about 0.30% by weight, for example, in an amount of less than about 0.25% by weight, for example, in an amount of less than about 0.22% by weight, for example, in an amount of less than about 0.20% by weight, for example, in an amount of less than about 0.18% by weight, for example, in an amount of less than about 0.15 % by weight, such as less than about 0.10% by weight, such as less than about 0.08% by weight, such as less than about 0.05% by weight, such as less than about 0.03% by weight, for example, in an amount of less than about 0.01% by weight. Typically, the carbon content of the regenerated catalyst will be higher than 0.005%. Typically, the amount of carbon in the total amount of catalyst available is in the range of from about 0.005 to about 0.30% by weight, even from about 0.25 to about 0.1% by weight of the amount of regenerated catalyst available.

[0057] The regenerated catalyst composition preferably has attrition resistance suitable to withstand the conditions typically used in FCC processes. Preferably, the catalyst composition has a DI of less than about 20, preferably less than 10, and most preferably less than 5.

FCC processes

[0058] The method of the invention is particularly suitable for use in traditional FCC processes in which hydrocarbon feedstocks are cracked into lower molecular weight compounds in the absence of hydrogen addition. Typical FCC processes cause cracking of hydrocarbon feedstocks in a cracking reactor unit (FCCU) or reactor stage in the presence of fluidized cracking catalyst particles to form liquid and gaseous product streams. The product streams are removed and the catalyst particles are then sent to a regenerator stage where the particles are regenerated under an oxidizing atmosphere to remove contaminant coke. In particular, in accordance with the present invention, the catalyst particles are regenerated under regenerator conditions to reduce the carbon content of the catalyst composition to at least below 0.3% by weight. The recovered particles are then recycled to the cracking zone to catalyze further hydrocarbon cracking. Thus, an available amount of catalyst particles containing regenerated catalyst circulates through the FCCU during the entire cracking process.

[0059] The FCC unit can be operated using conventional conditions where reaction temperatures are in the range of about 400°C to 700°C, with regeneration occurring at temperatures from about 500°C to 900°C. Specific conditions depend on the crude oil being processed, the desired product streams, and other conditions well known to refiners. For example, lighter feedstocks can be cracked at lower temperatures. The catalyst composition (ie its available amount) circulates in the plant in a continuous manner between the reaction of catalytic cracking and regeneration while maintaining the equilibrium of the catalyst in the reactor.

[0060] The regenerated FCC catalyst composition and method described herein can be used in a variety of fluid cracking processes that use pentasil zeolite containing catalyst/additives. Such processes may include Deep Catalytic Cracking (DCC), Catalytic Pyrolysis Process (CPP), High Severity Fluid Catalytic Cracking (HS-FCC), KBR Catalytic Olefin Technology (K-COT™), Superflex™, Ultra Catalytic Cracking (UCC) . The conditions for these processes and typical operating conditions are shown in the table below.

FCC DCC HS-FCC KCOT/Superflex CPP UCC Temperature, °С 500-550 505-575 570-610 650-680 560-650 550-570 Catalyst/oil 5-10 9-15 13-30 n.a. ^* 15-25 18-22 Pressure in the reactor, atm 1-2 0.7-1.5 1 1.5 0.8 1-4 Dilution with steam, % wt. from filing 1-3 5-30 1-3 n.a. 30-50 20-35 WHSV 125-200 0.2-20 n.a. n.a. 50-80 Type of raw material VGO, vat residues VGO, light paraffin raw material VGO, vat residues Naphtha VGO, vat residues VGO, vat residues *n.a.=no data

[0061] The catalyst composition can be used to crack a variety of hydrocarbon feedstocks. A typical feed includes all or part of a gas oil (eg, light, medium or heavy gas oil) having an initial boiling point above about 30°C and an end temperature up to about 850°C. The feedstock may also include deep recovery gas oil, vacuum gas oil, thermal oil, residual oil, recycled feedstock, fully stripped oil, tar sands oil, shale oil, synthetic fuel, heavy hydrocarbon fractions from destructive coal hydrogenation, tar, tar, bitumen, hydrotreated feed obtained from any of the above, and the like. In one embodiment, the feedstock may be feedstock naphtha with a boiling point of less than 120°C. As noted, the distillation of high-boiling oils above about 400° C. must be carried out under vacuum to avoid thermal cracking. The boiling points used herein are expressed for convenience in terms of the boiling point corrected for atmospheric pressure.

[0062] Although the improvement in propylene yields varies with feedstock and FCC conditions, use of the catalyst composition in conventional FCC units operating on typical feedstocks and at about 75% conversion can result in increased propylene yields of at least 0.1%, in terms of feedstock, preferably at least 3% and most preferably at least 7% compared to processes using a catalyst that does not contain the catalyst composition of the present invention. Yields of LPG (hydrocarbons in the C3 to C4 range) from processes using the catalyst composition can be at least 0.1% by weight of the feedstock, preferably at least 5% and most preferably at least 12% higher than with processes using a catalyst that does not contain the catalyst composition of the present invention.

[0063] For example, in one embodiment, the product stream from the fluid catalytic cracker may contain propylene in an amount of more than about 4.5% by weight, for example, in an amount of more than about 10% by weight, for example, in an amount of more than about 20% by weight. Ethylene may be present in the product stream in an amount of more than about 0.5% by weight, for example, in an amount of more than about 1.5% by weight, for example, in an amount of more than about 2% by weight. Ethylene is typically present in the product stream in an amount of less than about 25% by weight, and propylene is typically present in the product stream in an amount of less than about 40% by weight.

[0064] To further illustrate the present invention and its advantages, the following specific examples are provided. The examples are provided for illustrative purposes only and are not intended to be limiting of the claims appended herein. However, it should be understood that the present invention is not limited to the specific details set forth in the examples.

[0065] All parts and percentages in the examples, as well as in the rest of the description, which refer to solid compositions or concentrations, are mass, unless otherwise indicated. However, all parts and percentages in the examples, as well as in the rest of the description, which refer to gas compositions, are given in moles or by volume, unless otherwise indicated.

[0066] The present invention can be better understood with reference to the following examples.

Examples

[0067] The following examples demonstrate some of the advantages and benefits of catalyst compositions formulated in accordance with the present invention.

[0068] The amount of iron oxide and phosphorus pentoxide in the pentasil zeolite catalyst/additive composition was determined using inductively coupled plasma (ICP) spectroscopy and X-ray fluorescence spectroscopy (XRF). The carbon contained in the inventory of the regenerated catalyst was measured with a LECO carbon analyzer.

[0069] The "Davison Attrition Index" (DI) was determined by taking a 7.0 cc sample ^of the catalyst. The catalyst sample was sieved to remove particles in the range of 0-20 µm. The remaining particles after sieving were then brought into contact in an open container made of hardened steel with a hole of a calibrated size, through which a stream of humidified (60%) air was supplied at a flow rate of 21 l/min for 1 hour. DI was defined as the percentage of 0-20 μm fragments, formed during the test, relative to the amount of material initially present with a size of >20 µm, i.e. according to the formula below:

DI=100 × (% wt. 0-20 µm of material formed during the test) / (% wt. starting material 20 µm or more before testing)

DI is described in Cocco et al., Particle Attrition Measurement Using Jet Cup, the ^13th International Conference on Fluidization-New Paradigm in Fluidization Engineering, Art. 17 [2010].

Comparative example 1:

Comparative catalysts 1 and 3 were prepared without adding an iron compound. The dry powder of ZSM-5 was suspended in water. To this suspension was added alumina, kaolin clay and concentrated (85%) H ₃ PO ₄ . The slurry was mixed in a high shear mixer, ground with media in a Drais mill, and then spray dried. The Bowen spray dryer was operated at an inlet temperature of 400°C and an outlet temperature of 150°C. The spray-dried catalyst was calcined for 40 min at 593°C. The composition of comparative catalysts 1 and 3 and their resulting properties are shown in Tables 1 and 2. All of the Fe ₂ O ₃ in the catalyst comes from the clay.

Comparative Example 2

Comparative catalyst 2 with 4.6% Fe ₂ O ₃ was prepared according to the following procedure. The dry powder of ZSM-5 was suspended in water. Aluminum oxide, kaolin clay, FeCl ₂ ∙4H ₂ O powder and concentrated (85%) H ₃ PO ₄ were added to this suspension. The slurry was mixed in a high shear mixer, ground with media in a Drais mill, and then spray dried. The Bowen spray dryer was operated at an inlet temperature of 400°C and an outlet temperature of 150°C. The spray-dried catalyst was calcined for 40 min at 593°C. The composition of comparative catalyst 2 and its obtained properties are shown in Table 1.

Example 1 Additions of 40% ZSM-5 with 0.6-3.4% Fe ₂ O ₃

A series of ZSM-5 catalysts with 0.6-3.4% Fe ₂ O ₃ was prepared according to the following procedure. The dry powder of ZSM-5 was suspended in water. Aluminum oxide, kaolin clay, FeCl ₂ ∙4H ₂ O powder and concentrated (85%) H ₃ PO ₄ were added to this suspension. The slurry was mixed in a high shear mixer, ground with media in a Drais mill, and then spray dried. The Bowen spray dryer was operated at an inlet temperature of 400°C and an outlet temperature of 150°C. The spray-dried catalyst was calcined for 40 min at 593°C. The composition of catalysts A - C and their obtained properties are shown in table 1.

Table 1

Sample Comparative Catalyst 1 Catalyst A Catalyst B Catalyst C Comparative Catalyst 2 Pentasil zeolite, % wt. 40 40 40 40 40 Aluminum oxide, % wt. 6 6 6 6 6 P ₂ O ₅ , wt %. 13 14 15 16 17 Added Fe ₂ O ₃ , wt %. 0 1 2 3 4 Clay, % wt. 41 39 37 35 33 Wed bulk density (ABD), g/cm ³ 0.70 0.70 0.70 0.70 0.71 Davison Wear Index (DI) 5 8 7 6 6 Al ₂ O ₃ ,% 26 25 24 23 22 _Na2O , % 0.2 0.2 0.2 0.2 0.2 _{P2O5 ,} % 13 14 15 16 17 Fe ₂ O ₃ ,% 0.6 1.6 2.6 3.4 4.6 Decontaminated properties: CPS steaming at 1480°F (804°C) Oud. surface (SA), m ² /g 131 110 96 75 60 Decontaminated Properties: 1500°F/816°C Hydrothermal Steam (4 hours, 100% steam) Oud. surface (SA), m ² /g 125 121 119 122 124

Example 2 Additions of 55% ZSM-5 with 0.4-3.1% Fe ₂ O ₃

A series of catalysts ZSM-5 with 0.4-3.1% Fe ₂ O ₃ was obtained by the following method. The dry powder of ZSM-5 was suspended in water. To this suspension was added concentrated (85%) H ₃ PO ₄ , soluble iron salt, alumina and kaolin clay. The slurry was mixed in a high shear mixer, ground with media in a Drais mill, and then spray dried. The Bowen spray dryer was operated at an inlet temperature of 400°C and an outlet temperature of 150°C. The spray-dried catalyst was calcined for 2 h at 593°C. The composition of the catalysts (Catalyst D - Catalyst H) and their resulting properties are shown in Table 2.

table 2

Sample Comparative Catalyst 3 Catalyst D Catalyst E Catalyst F Catalyst G Catalyst H Pentasil zeolite,% wt. 55 55 55 55 55 55 Aluminum oxide, % wt. 6 6 6 6 6 6 P ₂ O ₅ , wt %. 13.5 13.7 13.9 14.1 14.4 15.3 Added Fe ₂ O ₃ , wt %. 0 0.3 0.6 1 1.5 3 Clay, % wt. 25.5 25 24.5 23.9 23.1 20.7 Wed bulk density (ABD), g/cm ³ 0.70 0.70 0.70 0.70 0.71 0.72 Davison Wear Index (DI) 4 7 7 6 4 6 Al ₂ O ₃ ,% 19.1 19.3 18.9 18.6 18.4 18.5 _{P2O5 ,} % 13.9 14.1 14.2 14.6 14.9 15.2 Fe ₂ O ₃ ,% 0.4 0.6 0.8 1.2 1.7 3.1 Decontaminated properties: CPS steaming at 1480°F (804°C) Specific surface area (SA), m ² /g 202 199 198 188 158 131 Decontaminated properties: hydrothermal steaming at 1500°F/816°C Specific surface area (SA), m ² /g 198 196 195 196 190 188

Example 3 Stability of Steamed Catalysts During Redox Steam Deactivation Cycles.

Iron oxide containing ZSM-5 Catalysts A-H and Comparative Catalysts 1, 2 and 3 were deactivated without any metal contaminants by a propylene vapor cycling (CPS) process that includes oxidation/reduction cycles. A description of the CPS process was published in D. Wallenstein, RH Harding, JR D Nee, LT Boock, "Recent Advances in the Deactivation of FCC Catalysts by Cyclic Propylene Steaming in the Presence and Absence of Contaminant Metals" Applied Catalysis A, General 204 (2000 ) 89-106. The specific surface area of the catalysts after deactivation is shown in Tables 1 and 2. The data presented in FIG. 1 shows that redox cycles have a negative effect on surface stability when the catalyst has higher iron contents. This is especially true above 4% Fe ₂ O ₃ , where there is a >50% loss in specific surface area compared to Base Comparative Catalysts 1 and 3 without any addition of Fe ₂ O ₃ .

Example 4: Stability of steamed catalysts during hydrothermal deactivation.

ZSM-5 Catalysts D-H and Comparative Catalyst 3 were deactivated with 24 h hydrothermal deactivation with 100% steam at 816°C. Figure 2 shows the specific surface area of the catalysts after 24 hours of hydrothermal deactivation with 100% steam at 816°C. The data show that loss of specific surface area is minimal in the presence of Fe ₂ O ₃ when CPS redox steaming is not used.

Example 5: Performance testing after redox steam decontamination cycles

Comparative Catalysts 1 and 2 and Catalysts A-C deactivated with CPS in Example 3 were tested as mixtures with Aurora™ cracking catalyst, a commercially available FCC catalyst from WR Grace & Co.-Conn. ZSM-5 additives were mixed at a level of 5% wt. with a steam-deactivated Aurora cracking catalyst and tested in an ACE Model AP Fluid Bed Microactivity unit at 527°C. Several tests were carried out for each catalyst using a catalyst/oil ratio of 3 to 10. The catalyst/oil ratio was varied by varying the weight of the catalyst and keeping the feed weight constant. The mass of raw material used for each test was 1.5 g and the raw material feed rate was 3.0 g/min. ACE hydrocarbon yields were interpolated to constant conversion for catalyst comparison. Feedstock properties are shown in Table 4. Interpolated ACE data (Table 5) shows that AC catalysts of the invention exhibit improved propylene yields compared to low (0.6% Fe ₂ O ₃ ) and high iron comparative catalysts 1 and 2 ( 4.6% Fe ₂ O ₃ ).

Example 6 Effect of Oxidized vs. Reduced Fe ⁿ⁺ to the yield of light olefins

Comparative Catalyst 1 and Comparative Catalyst 2 deactivated with hydrothermal steam (24 h at 816°C in 100% steam) were tested as deactivated (Comparative Catalyst 1 and Comparative Catalyst 2) and after reduction in hydrogen at 500°C for 2 hours (comparative catalyst 1 (reduced) and comparative catalyst 2 (reduced)). Fe ₂ O ₃ is in a mostly oxidized state after deactivation and in a more reduced state after reduction with hydrogen. Comparative Catalyst 1, Comparative Catalyst 1 (reduced), Comparative Catalyst 2, and Comparative Catalyst 2 (reduced) were tested as blends with Aurora™ cracking catalyst, a commercially available FCC catalyst from WR Grace & Co.-Conn. Testing conditions were the same as described in example 5. ZSM-5 additives were mixed at a level of 5% wt. with steam deactivated Aurora cracking catalyst. ACE hydrocarbon yields were interpolated to constant conversion for catalyst comparison. Feedstock properties are shown in Table 4. The ACE data (Table 6) show that Comparative Low Iron Catalyst 1 deactivated under oxidized and reduced conditions has very similar propylene yields, while Comparative Catalyst 2 with high iron shows that the sample deactivated under oxidized conditions has a significantly better propylene yield than Comparative Catalyst 2 reduced in hydrogen. Comparative Catalyst 2 (reduced) has a similar performance to Comparative Catalyst 1. This indicates that the iron must be in an oxidized state to improve light olefin productivity.

Table 4

Raw material properties:

API Gravity 24.7 K-factor 12.01 Sulfur 0.35 total nitrogen 0.14 Carbon according to Conradson 0.32 Simulated distillation, vol.% Initial Boiling Point (IBP) 10% thirty% 50% 70% 90% End Boiling Point (FBP)

Table 5

Comparative Catalyst 1 Catalyst A Catalyst B Catalyst C Comparative Catalyst 2 Conversion 75 75 75 75 75 Catalyst/oil 6.1 5.7 6.3 6.1 5.5 Ethylene, % wt. 0.81 1.05 1.15 0.91 0.84 Propylene, % wt. 9.0 10.2 10.7 10.1 8.7 C4 olefins, wt %. 9.0 9.4 9.8 9.6 8.7 Wet gas, % wt. 28.0 30.2 31.9 29.8 27.1 Gasoline, % wt. 44.0 41.8 40.0 42.3 45.1 Light cycle oil, % wt. 19.3 19.2 19.4 19.4 19.3 VAT residue, % wt. 5.7 5.8 5.6 5.6 5.7 Coke, % wt. 3.0 3.0 3.1 2.9 2.8

Table 6

Comparative
catalyst 1 Comparative
catalyst 1 (restored) Comparative
catalyst 2 Comparative
catalyst 2 (restored) Conversion 76 76 76 76 Catalyst/oil 6.1 6.1 6.0 6.2 Ethylene, % wt. 0.7 0.7 1.3 0.8 The total amount of dry gas, % wt. 1.7 1.7 2.2 1.9 Propylene, % wt. 8.2 8.3 10.8 8.0 The total amount of C4=, % wt. 9.0 9.2 9.8 8.6 The total amount of wet gas, % wt. 26.2 26.6 31.0 26.3 C5+ gasoline, % wt. 47.1 46.7 42.3 46.6 LCO, % wt. 18.4 18.4 18.2 18.5 VAT residue, % wt. 5.6 5.6 5.8 5.5 Coke, % wt. 2.7 2.6 2.7 3.0

Example 7 Effect of Carbon on Regenerated Catalyst Performance.

Comparative Catalyst 3 and Catalyst F were subjected to hydrothermal steam treatment for 24 hours in 100% steam. The steamed catalyst was then mixed with laboratory deactivated FCC base catalyst at 5% wt. Then the mixture of catalysts was coked in a pilot plant. The measured coke content on the catalysts was >0.6% wt. The coked catalyst was then calcined at various temperatures to achieve target levels of coke on the catalyst. The regenerated catalyst was then evaluated in ACE for propylene activity. The data show less than 0.30% of the mass. carbon on the regenerated catalyst; the sample modified with Fe ₂ O ₃ has a significantly higher propylene activity compared to the sample not modified with Fe ₂ O ₃ . Above 0.30% wt. carbon on the catalyst propylene activity drops rapidly, as shown in Fig.3.

Example 8 Advantage in C2= and C3= selectivity of the catalyst according to the invention.

Comparative Catalyst 2 and Catalyst F were subjected to hydrothermal steam treatment for 24 hours in 100% steam. The steamed catalyst was then mixed with laboratory deactivated FCC base catalyst at 5% wt. Then the mixture of catalysts was coked in a pilot plant. The measured coke content on the catalysts was >0.6% wt. The coked catalyst was then calcined at various temperatures to achieve target levels of coke (between 0.05% and <0.5%) on the catalyst. The regenerated catalyst was then evaluated in ACE for activity and selectivity for ethylene+propylene. The data in Figure 4 shows that at all levels of coke on the catalyst, the Fe ₂ O ₃ -modified sample has higher ethylene+propylene selectivity at constant total dry gas (hydrogen+C1-C2 hydrocarbons) than the sample modified unmodified Fe ₂ O ₃ . Higher selectivity for C2 and C3 olefins is important for plants that are limited by wet gas compressor capacity. This allows the refinery to maximize profitability by producing more C2 and C3 olefins at a constant amount of dry gas.

Claims (39)

1. A fluidized cracking process, comprising: contacting a hydrocarbon feed with a circulating available amount of regenerated fluid catalytic cracking catalyst to form a product stream wherein the regenerated fluid catalytic cracking catalyst in the available amount has a carbon content in the range of 0.005 to 0.30% by weight, based on total amount of regenerated catalyst composition available, and contains a pentasil-containing catalyst/additive composition that contains (a) pentasil zeolite; (b) from 0.7 to 4.0% by weight of iron oxide; And (c) from 5.0 to 20% by weight of phosphorus (calculated as P ₂ O ₅ ); where the amounts of iron oxide and phosphorus are given based on the wt % composition of the pentasil-containing catalyst/additive. 2. The method of claim 1, wherein the regenerated catalyst composition has an average particle size in the range of 20 to 200 microns. 3. The method of claim 1 wherein the iron oxide is present in the pentasil catalyst/additive in an amount of 0.9 to 2.5% by weight of the pentasil catalyst/additive composition in the regenerated catalyst. 4. The method according to claim 1 or 2, wherein phosphorus (based on P ₂ O ₅ ) is present in the composition of the pentasil-containing catalyst/additive in an amount of from 7 to 18% by weight of the pentasil-containing catalyst/additive in the regenerated catalyst. 5. The process of claim 4 wherein phosphorus (as P ₂ O ₅ ) is present in the pentasil catalyst/additive composition in an amount of 9 to 18% by weight of the pentasil catalyst/additive composition. 6. The method according to claim 1 or 2, wherein the regenerated catalyst contains carbon in an amount of 0.01 to 0.25% by weight of the available amount of regenerated catalyst. 7. Process according to claim 1 or 2, wherein said feedstock is subjected to catalytic cracking in said reactor at a temperature of 400 to 700°C. 8. The method according to claim 1 or 2, wherein the pentasil-containing catalyst/additive composition contains pentasil zeolite in an amount of more than 45% by weight of the catalyst/additive composition. 9. Process according to claim 1 or 2, wherein the product stream contains more than 4.5% propylene by weight of the product stream. 10. Process according to claim 1 or 2, wherein the product stream contains ethylene in an amount greater than 0.5% by weight of the product stream. 11. The method of claim 1 or 2 wherein the pentasil zeolite comprises ZSM-5 or ZSM-11. 12. The process of claim 1 or 2, wherein the regenerated catalyst composition has a Davison Attrition Index (DI) of less than 20, such as less than 10, such as less than 5. 13. The method according to claim 1 or 2, wherein the pentasil zeolite is ZSM-5. 14. The method of claim 1 or 2, wherein the catalyst, in an available amount, further comprises individual particles of an additional cracking catalyst composition suitable for cracking hydrocarbons, along with a pentasil-containing catalyst/additive composition. 15. The method of claim 14 wherein the additional cracking catalyst composition comprises a faujasite zeolite. 16. The method of claim 15 wherein the faujasite zeolite is selected from the group consisting of Y zeolite, REY, REUSY and mixtures thereof. 17. The composition of the regenerated catalyst in the available amount of circulating catalyst in the process of fluidized cracking, where the regenerated catalyst has a carbon content in the range from 0.005 to 0.30% by weight, based on the total amount of catalyst available, and contains a pentasil-containing catalyst composition / supplement that contains (a) pentasil zeolite; (b) from 0.7 to 4.0% by weight of iron oxide; And (c) from 5.0 to 20% by weight of phosphorus (calculated as P ₂ O ₅ ); where the amounts of phosphorus and iron oxide, respectively, are given based on the amount of phosphorus and iron oxide in the pentasil-containing catalyst/additive composition. 18. The regenerated catalyst composition of claim 17, wherein the regenerated catalyst composition has an average particle size in the range of 20 to 200 microns. 19. The regenerated catalyst composition of claim 17 or 18, wherein the iron oxide is present in the pentasil catalyst/additive composition in an amount ranging from 0.9 to 3.0% by weight of the pentasil catalyst/additive composition in the regenerated catalyst. 20. The regenerated catalyst composition of claim 19, wherein the pentasil catalyst/additive composition contains iron oxide in an amount ranging from 0.9 to 2.5% by weight of the pentasil catalyst/additive composition in the regenerated catalyst. 21. The regenerated catalyst composition of claim 17 or 18, wherein phosphorus (as P ₂ O ₅ ) is present in the pentasil catalyst/additive in an amount of 7% to 18% by weight of the pentasil catalyst/additive composition. 22. The regenerated catalyst composition of claim 21, wherein phosphorus (as P ₂ O ₅ ) is present in the pentasil catalyst/additive composition in an amount of 9 to 18% by weight of the pentasil catalyst/additive composition. 23. The regenerated catalyst composition of claim 17, wherein the regenerated catalyst composition contains carbon in an amount of less than 0.25% by weight of the regenerated catalyst composition. 24. The regenerated catalyst composition of claim 17, wherein the regenerated catalyst composition contains carbon in an amount ranging from 0.01 to 0.25% by weight of the available amount of catalyst. 25. The regenerated catalyst composition of claim 17, wherein the pentasil catalyst/additive composition contains pentasil zeolite in an amount ranging from 10 to 80% by weight of the pentasil catalyst/additive composition. 26. The regenerated catalyst composition of claim 17 wherein the pentasil zeolite is ZSM-5 or ZSM-11. 27. The regenerated catalyst composition of claim 17, wherein the pentasil-containing catalyst/additive composition has a Davison attrition index (DI) of less than 20, such as less than 10, such as less than 5. 28. The regenerated catalyst composition of claim 17, wherein the regenerated catalyst further comprises an additional cracking catalyst composition. 29. The regenerated catalyst composition of claim 28, wherein the additional cracking catalyst comprises a faujasite zeolite. 30. The regenerated catalyst composition of claim 29, wherein the faujasite zeolite is selected from the group consisting of Y zeolite, REY, REUSY, and mixtures thereof.

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