DESC:FIELD OF THE INVENTION

The present invention relates to a Fluid Catalytic Cracking (FCC) catalyst composition and a process for bottom up-gradation to distillates with reduction in dry gas and coke. Further, this invention also relates to a process for bottom up-gradation with reduction in dry gas and coke, employing low active spent FCC catalyst which is modified for acidity with a suitable component and further bonded employing a competent binder.

BACKGROUND OF THE INVENTION

Large quantities of cracking catalysts are used in the Fluid catalytic cracking process in the refinery for upgrading of various petroleum streams and residues. Catalysts used in FCC process gradually lose activity and selectivity over a period of time and reach a stage, where continuing further with the said de-activated catalyst will render the process uneconomical. Loss in activity of FCC catalyst is mainly due to dealumination of zeolite which reduces its efficiency. The detrimental effect of accumulated metal from feed leads to reduction in activity of catalyst and enhanced coke and dry gas formation during cracking reaction. Moreover during a period of continuous ageing of catalyst in the reactor and regenerator of FCC unit, the catalyst became sintered, causes reduction in accessibility of hydrocarbon feed molecules to acid sites of catalysts.

Nevertheless, Catalyst on losing substantial catalytic activity still possesses some activity. This catalyst can be further used as an additive by employing the process disclosed in this present invention. The spent catalysts are usually discarded as solid wastes. Mainly spent catalyst are used as a flushing catalyst, top-up catalyst and majority are being sent for land filling.

Indian Patents 234914, 235706 and 248230 describes the process of utilization of spent FCC catalyst in cement products for enhancing fineness, cursing strength, in refractory kiln and ceramic industry. US5520797 and US4359379 describes the processes for the fluid catalytic cracking of heavy oils rich in Ni and V by withdrawing a portion of ferrite-containing catalyst particles circulating in a fluid catalytic cracking apparatus, by using a magnetic separator.
US5188995 describes the process in which spent metal-contaminated zeolite-containing catalytic cracking catalyst is reactivated by a process which comprises contacting the spent catalyst with at least one dissolved carboxylic acid and at least one antimony compound. This invention more particularly describes a method of reactivating spent, metal-contaminated zeolite-containing catalytic cracking catalysts. In another aspect, this invention relates to a catalytic cracking process employing a reactivated spent catalytic cracking catalyst.

US5151391 describes the process in which, spent metal contaminated zeolite-containing catalytic cracking catalyst composition is reactivated by a process which comprises contacting with an aqueous solution of HCl and/or HNO3 and/or H2SO4. Thus reactivated catalyst composition can be employed in a catalytic cracking. Further this invention relates to a method of reactivating spent, metal-contaminated zeolite-containing catalytic cracking catalysts. In another aspect, this invention relates to a catalytic cracking process employing a reactivated spent catalytic cracking catalyst.

US5888919 describes the process in which a spent zeolite-containing hydrocarbon cracking catalyst is treated by regenerating it to remove carbonaceous deposits. A portion of the regenerated catalyst is withdrawn from the circulating catalyst inventory of a hydrocarbon processing unit and slurried with a liquid containing an activating agent. This invention relates to process for improving the activity of fluid catalytic cracking (FCC) or moving bed cracking (TCC) catalyst, including any additives containing zeolitic material as one of the active components and which may be employed with each type catalyst, which process can be integrated with the operations of the hydrocarbon processing unit in which the catalyst is employed.

US4919787 describes the process for an improved method for passivating metals in a hydrocarbon feedstock during catalytic cracking. Further this invention involves contacting the feedstock with a passivating agent comprising a precipitated porous rare earth oxide, alumina, and aluminium phosphate precipitate. The passivating agent may be coated on a cracking catalyst, be part of the matrix of a cracking catalyst, or be added to the cracking operation as discrete particles.

EP73874B1 discloses Immobilization of vanadia deposited on catalytic materials during the conversion of oil that contains coke precursors and heavy metals.

US application 20100025297A1 discloses additives for metal contaminant removal. It also discloses a catalytic cracking additive comprising metal trapping material; and a high activity catalyst. This invention is directed to processes for the catalytic cracking of feedstock comprising contacting said feedstock under catalytic cracking conditions with a composition comprising a bulk catalyst and a catalytic cracking additive, wherein the catalytic cracking additive comprises a metal trapping material; and a high activity catalyst.

Therefore, there is a need to provide an improved process and a catalyst composition for converting low activity spent catalyst, to an efficient catalyst composition to be used in FCC process for enhancing catalytic activity of host catalyst.

OBJECTIVE OF THE INVENTION

The primary object of the present invention is to provide a single catalyst composition suitable for fluid catalytic cracking, riser cracking and fixed bed cracking in which high value middle distillate and gasoline can be enhanced significantly with marginal reduction in bottom yields.

Another objective of the present invention is to provide a suitable catalyst composition which is prepared by employing spent FCC catalyst, capable of withstanding rigors of fluidization, transport, stripping steps and maintaining integrity of particles with adequate apparent bulk density (ABD) and attrition resistance.

Another objective of the present invention is to provide a process to prepare a catalyst by employing a spent FCC catalyst wherein the acidity of spent catalyst was modify in such a way that the performance of overall catalyst in FCCU cracking of the heavy hydrocarbon molecules enhances yields of gasoline and distillate and simultaneously suppress yields of low value coke and dry gas.

Yet another object of the present invention is to provide a catalyst having required pore size, and surface area required for facilitating smooth entry and exit of reactants and products from the catalyst.

SUMMARY OF THE INVENTION

The present invention is aimed to overcome the difficulties and limitations encountered to provide an improved process and a catalyst composition by employing spent FCC catalyst component for catalytic cracking of heavy oils in petroleum processing industry.

According to the invention there is provided a middle distillate enhancing Fluid Catalytic Cracking (FCC) catalyst composition comprising spent FCC catalyst introduced thereto a substance (acidity modifier) phosphate, selected from the group comprising of phosphoric acid, ammonium di hydrogen phosphate, ammonium mono hydrogen phosphate, tri-ammonium phosphate.

Furthermore, the present invention relates to a product and process for improving selectivity of spent catalyst through milling, treating with an acidity modifying agent and re-shaping to equivalent fresh FCC catalyst by employing a suitable binder.

In an aspect of the present invention, the one embodiment of the present invention relates to a process for preparing fluid catalytic cracking comprising the steps of: (a) burning, spent catalyst to obtain a de-carbonated spent catalyst; (b) milling the de-carbonated spent catalyst to obtain a milled de-carbonated spent catalyst; (c) treating the milled de-carbonated spent catalyst with a source of phosphate in an aqueous media to obtain a modified spent catalyst; (d) admixing the modified spent catalyst with a binder, a matrix material and a clay to obtain a slurry; (e) milling the slurry and spray drying to obtain a micro-spheroidal particles; and (f) calcining the micro-spheroidal particles to obtain the fluid catalytic cracking (FCC) catalyst.
Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein binder is prepared by a process comprising: dispersing aluminium trihydrate in water to get alumina slurry. Adding phosphoric acid to alumina slurry with continues stirring and keeping mixture for 1 hour at 70 °C to obtain clear solution of mono-aluminium phosphate. Diluting mono-aluminium phosphate solution water, adding aluminium nitrate to solution with continuous stirring and keeping for 30 minutes to get the binder.Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein the milled de-carbonated spent catalyst having a particle size in the range of 5 to 9 microns.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein the spent catalyst is burned at a temperature in the range of 500-600 °C.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein the milled de-carbonated spent catalyst is treated with a source of phosphate in aqueous media at temperature in the range of 25 – 90°C.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein the duration of treating the milled de-carbonated spent catalyst with a source of phosphate in aqueous media is 5 minutes to 12 hours.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein phosphate is selected from the group consisting of phosphoric acid, ammonium di hydrogen phosphate, ammonium mono hydrogen phosphate, tri-ammonium phosphate, ammonium hypophosphate, ammonium ortho-phosphate, ammonium di hydrogen ortho-phosphate, ammonium mono hydrogen ortho-phosphate, ammonium hypo phosphite, ammonium di hydrogen ortho-phosphite, and mixtures thereof.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein the matrix material is selected from the group consisting of alumina, silica, silica-alumina and clay.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein alumina is selected from the group consisting of aluminium oxide, aluminium hydroxide, or aluminium oxyhydroxide.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein clay is selected from the group consisting of kaolinite and halloysite and the clay is having having size in the range of 1 to 4 microns.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein the micro-spheroidal particles having size in the range of 5 to 200 microns.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein the micro-spheroidal particles are calcined at a temperature in the range 480°C to 570 °C.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein fluid catalytic cracking catalyst is having apparent bulk density in the range of 0.70 – 0.90 gm/ml and attrition index in the range of 2 to 10.

Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein the spent catalyst comprises: zeolite in the range of 1 - 15 wt.%; silica alumina matrix components in the range of 0.5 – 5 wt.%; and contaminating metals in the range of 100 - 15,000 ppm. Wherein, the zeolite is selected from the group consisting of ZSM-5 zeolite, faujasite zeolite, or combination thereof; and contaminating metals consisting of nickel and vanadium.Another embodiment of the present invention provides a process for preparing fluid catalytic cracking catalyst as herein described wherein the spent catalyst has a surface area in the range of 50 - 120 m2/gm, particle size in the range of 5 - 120 microns and apparent bulk density in the range of 0.70 - 0.90 gm/ml.

In another aspect of the present invention, the one embodiment of the present invention relates to a fluid catalytic cracking (FCC) catalyst, comprising: modified spent catalyst in the range 5 - 30 wt. %; binder in the range of 5 - 20 wt. %; alumina in the range of 5-15 wt. %; silica in the range of 10 - 40 wt. %; clay in the range of 30 - 50 wt. %; the percentage being based on weight of the fluid catalytic cracking (FCC) catalyst.

Another embodiment of the present invention provides a fluid catalytic cracking (FCC) catalyst as herein described wherein fluid catalytic cracking catalyst is having apparent bulk density in the range of 0.70 – 0.90 gm/ml and attrition index in the range of 2 to 10.

Another embodiment of the present invention provides a fluid catalytic cracking (FCC) catalyst as herein described wherein the modified spent catalyst is obtained by: (a) burning to spent catalyst at a temperature in the range of 500 to 600 °C to obtain a de-carbonated spent catalyst; (b) milling the de-carbonated spent catalyst to obtain a milled de-carbonated spent catalyst; (c) treating the milled de-carbonated spent catalyst with a source of phosphate in an aqueous media to obtain the modified spent catalyst.

Another embodiment of the present invention provides a fluid catalytic cracking (FCC) catalyst as herein described wherein the spent catalyst comprises: zeolite in the range of 1 - 15 wt.%; silica alumina matrix components in the range of 0.5 – 5 wt.%; and contaminating metals in the range of 100 - 15,000 ppm. Wherein, the zeolite is selected from the group consisting of ZSM-5 zeolite, faujasite zeolite, or combination thereof; and contaminating metals consisting of nickel and vanadium.

Another embodiment of the present invention provides a fluid catalytic cracking (FCC) catalyst as herein described wherein the spent catalyst has surface area in the range of 50 - 120 m2/gm, particle size in the range of 5 - 120 microns and apparent bulk density in the range of 0.70 - 0.90 gm/ml.

Another embodiment of the present invention provides a fluid catalytic cracking (FCC) catalyst as herein described wherein phosphate is selected from the group consisting of phosphoric acid, ammonium di hydrogen phosphate, ammonium mono hydrogen phosphate, tri-ammonium phosphate, ammonium hypophosphate, ammonium ortho-phosphate, ammonium di hydrogen ortho-phosphate, ammonium mono hydrogen ortho-phosphate, ammonium hypo phosphite, ammonium di hydrogen ortho-phosphite, and mixtures thereof.

DETAILED DESCRIPTION OF THE INVENTION

While the invention is susceptible to various modifications and alternative forms, specific embodiment thereof will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the scope of the invention as defined by the appended claims.

According to the invention there is provided a middle distillate enhancing Fluid Catalytic Cracking (FCC) catalyst composition comprising spent FCC catalyst introduced thereto a substance (acidity modifier) phosphate, selected from the group comprising of phosphoric acid, ammonium di hydrogen phosphate, ammonium mono hydrogen phosphate, tri-ammonium phosphate.

According to this invention, spent FCC catalyst is first freed from any hydrocarbon including coke by burning off at sufficiently high temperature in presence of air, grinding this carbon free spent catalyst to a particle size in the range 5 - 9 microns, treating milled spent catalyst with a source of phosphate in aqueous media between temperature 25 - 95 °C for a duration of 5 minutes to 12 hours, admixing with a binder, adequate amount of matrix material selected from alumina, silica, silica-alumina and clay, milling final slurry and producing microspheroidal particles in the range of 5-200 microns by spray drying and finally calcining to a temperature in the range of 480 - 570°C.

The spent FCC catalyst according to this invention may contain any or both of ZSM-5 and faujasite type zeolite ranging from 1 to 15 %, contaminant metals such as nickel and vanadium ranging from 100 ppm to 15,000 ppm and others silica alumina matrix components including phosphate from 0.5 - 5 wt%. The starting spent FCC catalyst has a surface area of 50 - 120 m2 /gm, particle size of 5 -120 microns and apparent bulk density of 0.70 - 0.90 gm/ml.

The binder according to this invention is prepared by dispersing aluminium trihydrate in water to get alumina slurry. Adding phosphoric acid to alumina slurry with continues stirring and keeping mixture for 1 hour at 70 °C to obtain clear solution of mono-aluminium phosphate. Diluting mono-aluminium phosphate solution water, adding aluminium nitrate to solution with continuous stirring and keeping for 30 minutes to get the binder.

Acidity modifier of spent catalyst is a phosphate selected from the group comprising of phosphoric acid, ammonium di-hydrogen phosphate, ammonium mono hydrogen phosphate, tri-ammonium phosphate and mixtures thereof. Alumina is selected from the group comprising of aluminium oxide, aluminium hydroxide and aluminium oxyhydroxide as matrix. Other materials are selected from the group comprising of sodium/ammonium stabilized colloidal silica, clay is selected from the group comprising of kaolinite and halloysite with a size in the range of 1 - 4 microns. Binder is prepared by reacting aluminium tri-hydrate, phosphoric acid and aluminium nitrate. Final, distillate enhancing catalyst has an apparent bulk density of 0.70 - 0.90 gm/ml and an attrition index of below 10. The distillate enhancing catalyst has modified spent FCC catalyst in the range of 5 - 30 wt%, alumina phosphate binder in the range of 5 - 20 wt%, silica 10 - 40 wt%, clay in the range of 30 - 50 wt%, sodium oxide in the range of 0.1 - 0.5 wt%, total Nickel and Vanadium contaminant metals from 2 ppm to 5000 ppm and rare earth oxide of 0.1 - 2 wt%.

In one embodiment the process for preparing distillate enhancing catalyst from spent FCC catalyst comprises the following sequence of steps:
a) Burning off volatiles including carbon present in spent catalyst;
b) Milling of de-carbonated spent catalyst to particle size in the range of 5 – 9 microns;
c) Treating milled de-carbonated spent catalyst with a source of phosphate to modify acidity;
d) Preparation of binder;
e) Introducing acid modified spent catalyst to a binder prepared in step (d), adding matrix material selected from silica, alumina, silica-alumina and clay;
f) Homogenizing the product of step (e) and milling to produce catalyst precursor slurry with solid content ranging from 15 - 45 wt%;
g) Spray drying; and
h) Calcining of spray dried product to produce ready to use fluid catalytic cracking catalyst.

The main component of distillate maximization catalyst of the present invention is spent FCC catalyst. The detail of spent FCC catalyst is given below.

Spent Catalyst - Fresh FCC/RFCC catalysts are produced from shape selective zeolite material either in ammonia or in rare earth form ranging from 20 - 45 wt%. These zeolites are bonded by either silica or alumina or by silica-alumina composite, while clay is used as a diluent/heat sink/low cost filler. Fresh catalysts generally possess very high microactivity (vacuum gas oil conversion) and have surface area in the range 180 - 300 m2/gm and Y-zeolite crystallinity above 20% while unit cell size (UCS) above 24.40 Å. As these catalysts pass through high temperature and steam zones in FCC/RFCC unit, thereby undergo severe degradation during initial few hours dwell in the unit. Degradation is in terms of surface area, crystallinity and UCS. This is reflected in catalyst performance, where it steeply falls from over 70 % to below 65 %. After initial few hours steep fall in these parameters, further fall is gradual. During initial stage in the catalyst plant, the zeolite component present in the catalyst undergoes severe dealumination, while silica from matrix keeps healing those vacancies. A stage will be reached where, there is equilibrium. Such a catalyst is named as equilibrium catalyst (E-catalyst) and will have more or less stable activity. Further, dwell of E-catalyst in the plant, will cause gradual degradation on activity and a stage will be reached where further continuation of catalyst will offset economic benefits over fresh catalyst performance. At this time, considerable amount of catalyst is withdrawn from the plant and substituted with fresh catalyst. Such a catalyst is known as spent catalyst and will have surface area in the range 50 - 170 m2/gm, while Y zeolite crystallinity is in the range of 1 - 15 wt%. Spent catalyst may have metals such as Vanadium & Nickel in the range 100 - 3000 ppm in case of VGO (FCC) operation. These metal levels are much higher in case of RFCC units where the total metal levels (Nickel & Vanadium) will be in the range of 3000 - 15000 ppm. The crystallinity and surface area of spent catalyst samples is lower compared to FCC catalysts due to higher operational severity and higher deactivation due to metals.

The following non-limiting examples illustrate in details about the invention. However, they are, not intended to be limiting the scope of present invention in any way.

EXAMPLE-1:
Preparation of modified spent catalyst
Spent FCC catalyst having surface area of 90 m2/gm was taken and burning at 550°C for 1 hr to remove the volatiles including carbon present. 1000 gm of spent FCC catalyst was taken and milled for 2 hrs to produce a particle below 10 microns. 463.40 gm of di-ammonium hydrogen phosphate (PO4 content 71.93 wt %) was dissolved in 1630 gm of DM water to prepare a di-ammonium hydrogen phosphate solution. This solution was added to milled spent catalyst particle and stirred for 30 min to form phosphated spent catalyst with modified acidity slurry ready for use in the preparation of FCC additive for distillate maximization. The phosphated spent catalyst content in this slurry is 45 wt%.
EXAMPLE -2:
Preparation of binder
223.94 gm of aluminium trihydrate (LOI=34 wt%) was dispersed in 380 gm of DM water to form alumina slurry then 1002.59 gm of phosphoric acid (85 wt%) was added to it to under stirring condition, while the mixture was maintained at a temperature of 70°C and was kept for 1 hr to obtain clear solution of mono-aluminium phosphate.
Further 519.09 gm of this mono-aluminium phosphate (LOI=42.63) as prepared above was diluted with 310 gm of DM water and then 716.53 gm of Al (NO3)3.9H2O was added under stirring and kept for 30 min to form aluminium phosphate solution. The aluminium phosphate content in this binder solution is 23.23 wt%.
EXAMPLE -3:
Preparation of FCC catalyst using 10 wt% modified spent catalyst & 10 wt% binder .
5 gm of tamol is dispersed in 430.48 gm of binder prepared as per Example 2 (AlPO4 content = 23.23 wt%) and 666.66 gm of ammonium polysilicate (Silica content =30 wt%) was added to the binder under stirring and continued the stirring for 30 minutes. To this binder solution, 582.35 gm of clay (LOI: 15 wt %), 135.14 gm of pseudo-bohemite alumina (LOI: 26 wt %) were added and stirred for 30 minutes for homogenizing the ingredients to form binder-clay-silica-alumina slurry. 222.22 gm of phosphated spent catalyst slurry (phosphated spent catalyst in the slurry= 45 wt%) prepared as per example-1 was added to this binder-clay-silica-alumina slurry to obtain final slurry. Final slurry was then sieved through 40 mesh SS sieve and spray dried with inlet temperature of 350-380°C and out let temperature of 120-160°C with a feed pump discharge pressure of 20-30 kg/cm2 to form FCC catalyst microsphere. Thus prepared spray-dried microsphere was calcined at 550 °C for two hours to form final FCC catalyst.
The calcined FCC catalyst has surface area 121 m2/gm, higher ABD (0.88 gm/cc), higher attrition resistance properties (Attrition Index 2.3) and average particle size of 85 microns.
The final FCC catalyst was steam de-activated and evaluated in Advanced Cracking Evaluation R+ Micro Activity Test unit at 5 wt% concentration in base FCC catalyst. During evaluation reaction temperature was considered at 510 0C at a cat/oil ratio of 6.02.
The performance results of the final FCC catalyst prepared under this examples indicate improvement of distillate yield by 0.67 wt%, gasoline yields by 0.66 wt% and reduction in bottom yields by 0.52 wt%, Dry Gas by 0.2 wt % and coke by 0.4 wt % with respect to base catalyst (100 % FCC catalyst ). Physical properties along with performance results are shown in a Table 2A & 2B.
EXAMPLE-4:
Preparation of FCC catalyst using 20 wt% modified spent catalyst & 10 wt% binder.
5 gm of tamol is dispersed in 430.48 gm of binder prepared as per Example 2 (AlPO4 content = 23.23 wt %) and 666.66 gm of ammonium polysilicate (Silica content =30 wt %) was added to the binder under stirring and continued the stirring for 30 minutes. To this binder solution, 464.70 gm of clay (LOI: 15 wt %), 135.14 gm of pseudo-bohemite alumina (LOI: 26 wt %) were added and stirred for 30 minutes for homogenizing the ingredients to form binder-clay-silica-alumina slurry. 444.44 gm of phosphated spent catalyst slurry (phosphated spent catalyst in the slurry= 45 wt%) prepared as per example-1 was added to this binder-clay-silica-alumina slurry to obtain final slurry. Final slurry was then sieved through 40 mesh SS sieve and spray dried with inlet temperature of 350-380 °C and out let temperature of 120-160°C with a feed pump discharge pressure of 20 - 30 kg/cm2 to form FCC catalyst microsphere. The prepared spray-dried microsphere was calcined at 550 °C for two hours to form final FCC catalyst.
The calcined final FCC catalyst has surface area 128 m2/gm, higher ABD (0.81 gm/cc), higher attrition resistance properties (Attrition Index 3.1) and average particle size of 83 microns.
The final FCC catalyst was steam de-activated and evaluated in Advanced Cracking Evaluation R+ Micro Activity Test unit at 5 wt% concentration in base FCC catalyst. During evaluation reaction temperature was considered at 510 0C at a cat/oil ratio of 6.02.
The performance results of the final FCC catalyst prepared under this examples indicate improvement of distillate yield by 0.84 wt%, gasoline yields by 0.78 wt% and reduction in bottom yields by 0.58 wt%, Dry Gas by 0.18 wt % and coke by 0.54 wt % with respect to base catalyst (100 % FCC catalyst ). Physical properties along with performance results are shown in a Table 2A & 2B.
EXAMPLE-5:
Preparation of FCC catalyst using 30 wt% modified spent catalyst & 10 wt% binder.
5 gm of tamol is dispersed in 430.48 gm of binder prepared as per Example 2 (AlPO4 content = 23.23 wt%) and 666.66 gm of ammonium polysilicate (Silica content =30 wt%) was added to the binder under stirring and continued the stirring for 30 minutes. To this binder solution, 347.05 g of clay (LOI: 15 wt %), 135.14 gm of pseudo-bohemite alumina (LOI: 26 wt %) were added and stirred for 30 minutes for homogenizing the ingredients to form binder-clay-silica-alumina slurry. 666.66 gm of phosphated spent catalyst slurry (phosphated spent catalyst in the slurry= 45 wt%) prepared as per example-1 was added to this binder-clay-silica-alumina slurry to obtain final slurry. Final slurry was then sieved through 40 mesh SS sieve and spray dried with inlet temperature of 350-380 °C and out let temperature of 120-160 °C with a feed pump discharge pressure of 20 - 30 kg/cm2 to form FCC additive microsphere. The prepared spray-dried microsphere was calcined at 550 °C for two hours to form final FCC catalyst.
The calcined final FCC catalyst has surface area 135 m2/gm, higher ABD (0.75 g/cc), higher attrition resistance properties (Attrition Index 4.8) and average particle size of 79 microns.
The final FCC catalyst was steam de-activated and evaluated in Advanced Cracking Evaluation R+ Micro Activity Test unit at 5 wt% concentration in base FCC catalyst. During evaluation reaction temperature was considered at 510 °C at a cat/oil ratio of 6.02.
The performance results of the final FCC catalyst prepared under this example indicate improvement of distillate yield by 0.97 wt%, gasoline yields by 0.14 wt% and reduction in bottom yields by 0.35 wt% and coke by 0.70 wt % with respect to base catalyst (100 % FCC catalyst). Physical properties along with performance results are shown in a Table 2A & 2B.
EXAMPLE-6:
Preparation of FCC catalyst using 40 wt% modified spent catalyst & 10 wt% binder.
5 gm of tamol is dispersed in 430.48 gm of binder prepared as per Example 2 (AlPO4 content = 23.23 wt%) and 666.66 gm of ammonium polysilicate (Silica content =30 wt%) was added to the binder under stirring and continued the stirring for 30 minutes. To this binder solution, 229.41 gm of clay (LOI: 15 wt %), 135.14 g of pseudo-bohemite alumina (LOI: 26 wt %) were added and stirred for 30 minutes for homogenizing the ingredients to form binder-clay-silica-alumina slurry. 888.89 gm of phosphated spent catalyst slurry (phosphated spent catalyst in the slurry= 45 wt%) prepared as per example-1 was added to this binder-clay-silica-alumina slurry to obtain final slurry. Final slurry was then sieved through 40 mesh SS sieve and spray dried with inlet temperature of 350-380 °C and out let temperature of 120-160 °C with a feed pump discharge pressure of 20-30 kg/cm2 to form FCC additive microsphere. The prepared spray-dried microsphere was calcined at 550 °C for two hours to form final FCC catalyst.
The calcined final FCC catalyst has surface area 141 m2/gm, higher ABD (0.66 g/cc), higher attrition resistance properties (Attrition Index 9.6) and average particle size of 71 microns.
The final FCC catalyst was steam de-activated and evaluated in Advanced Cracking Evaluation R+ Micro Activity Test unit at 5 wt% concentration in base FCC catalyst. During evaluation reaction temperature was considered at 510 0C at a cat/oil ratio of 6.02.
The performance results of the final FCC catalyst prepared under this examples indicate improvement of distillate yield by 0.66 wt%, LPG yields by 0.54 wt% and reduction in bottom yields by 0.05 wt%, coke by 0.15 wt % and reduction in gasoline yields by 1.28 % with respect to base catalyst (100 % FCC catalyst ). Physical properties along with performance results are shown in a Table 2A & 2B.
EXAMPLE-7:
Preparation of FCC catalyst using 20 wt% modified spent catalyst & without binder.
5 gm of tamol is dispersed in 930 gm of DM water, 582.35 gm of clay (LOI: 15 wt %) and 135.14 gm of pseudo-bohemite alumina (LOI: 26 wt %) were added and stirred for 30 minutes to form clay alumina slurry. To this slurry, 666.66 gm of ammonium polysilicate (Silica content =30 wt%) was added under stirring to form clay-alumina-silica slurry. 444.44 gm of phosphated spent catalyst slurry (phosphated spent catalyst in the slurry=28.06 wt%) prepared as per example-1 was added to this clay-alumina-silica slurry to obtain final slurry. Final slurry was then sieved through 40 mesh SS sieve and spray dried with inlet temperature of 350 - 380 °C and out let temperature of 120 - 160 °C with a feed pump discharge pressure of 20-30 kg/cm2 to form FCC additive microsphere. The prepared spray-dried microsphere was calcined at 550 °C for two hours to form final FCC catalyst.
The calcined final FCC catalyst has surface area 110 m2/gm, inferior ABD (0.61 gm/cc), lower attrition resistance properties (Attrition Index >10) and average particle size of 70 microns.
The final FCC catalyst was steam de-activated and evaluated in Advanced Cracking Evaluation R+ Micro Activity Test unit at 5 wt% concentration in base FCC catalyst. During evaluation reaction temperature was considered at 510 °C at a cat/oil ratio of 6.02.
The performance results of the final FCC catalyst prepared under this example indicate improvement of distillate yield by 0.76 wt%, gasoline yields by 0.72 wt% and reduction in bottom yields by 0.55 wt% and coke by 0.46 wt% with respect to base catalyst (100 % FCC catalyst). Physical properties along with performance results are shown in a Table 2A & 2B
EXAMPLE-8:
Preparation of FCC catalyst using 20wt% normal spent catalyst & 10 wt% binder.
5 gm of tamol is dispersed in 430.48 gm of binder prepared as per Example 2 (AlPO4 content = 23.23 wt%) and 666.66 gm of ammonium polysilicate (Silica content =30 wt%) was added to the binder under stirring and continued the stirring for 30 minutes. To this binder solution, 582.35 gm of clay (LOI: 15 wt %), 135.14 gm of pseudo-bohemite alumina (LOI: 26 wt %) were added and stirred for 30 minutes for homogenizing the ingredients to form binder-clay-silica-alumina slurry. 200 gm of spent catalyst (calcined spent catalyst without phosphate treated) prepared as per example-1 was added to this binder-clay-silica-alumina slurry to obtain final slurry. Final slurry was then sieved through 40 mesh SS sieve and spray dried with inlet temperature of 350 - 380 °C and out let temperature of 120 - 160 °C with a feed pump discharge pressure of 20 - 30 kg/cm2 to form FCC additive microsphere. The prepared spray-dried microsphere was calcined at 550 °C for two hours to form final FCC catalyst.
The calcined final FCC catalyst has surface area 125 m2/gm, higher ABD (0.79 g/cc), higher attrition resistance properties (Attrition Index 2.9) and average particle size of 80 microns.
The final FCC catalyst was steam de-activated and evaluated in Advanced Cracking Evaluation R+ Micro Activity Test unit at 5 wt% concentration in base FCC catalyst. During evaluation reaction temperature was considered at 510 °C at a cat/oil ratio of 6.02.
The performance results of the final FCC catalyst prepared under this example indicate improvement of distillate yield by 0.67 wt%, gasoline yields by 0.66 wt% and reduction in bottom yields by 0.52 wt% and increase in coke by 0.17 wt% with respect to base catalyst (100 % FCC catalyst). Physical properties along with performance results are shown in a Table 2A & 2B.

Properties of feed where all the above additives prepared as per examples-3 to 7 are evaluated are given below Table-1:
Table-1: Feed properties
Sr. No. Attributes Unit Value
1 Density @ 15 °C gm/cc 0.8653
2 Kinematic Viscosity @ 100 °C Cst 23
3 Distillation, D-1160
4 IBP °C 286
5 5% °C 347
8 30% °C 402.9
9 50% °C 429.15
10 70% °C 461.79
11 Sulphur wt% 0.6-0.7

Table-2A: Composition and physical properties of additives under Examples 3-8
Example-3 Example-4 Example-5 Example-6 Example-7 Example-8

Additive composition

Dispersant 0.5 0.5 0.5 0.5 0.5 0.5
Binder as per Example-2
10 10 10 10 0 10
Alumina
10 10 10 10 10 10
SiO2
20 20 20 20 20 20
Clay
49.5 39.5 29.5 19.5 49.5 39.5
Modified Spent Catalyst as per Example-1
10 20 30 40 20 0
Calcined spent catalyst without phosphate treated
0 0 0 0 0 20

Additive Physical properties
Surface are, m2/gm
121 128 135 141 110 125
ABD, gm/cc
0.88 0.81 0.75 0.66 0.61 0.79
Attrition Index
2.3 3.1 4.8 9.6 >10 3.5

Table-2B: Performance results of additives under Examples 3-7
Catalyst composition Base Base +
5 wt% of Example-3 Base +
5 wt% of Example-4 Base +
5 wt% of Example-5 Base +
5 wt% of Example-6 Base+
5 wt% of Example-7 Base +
5 wt% of Example-8
Cat/oil 6.02 6.02 6.02 6.02 6.02 6.02 6.02
Conv., wt% 71.12 71.07 71.08 70.54 70.41 71.08 71.14
Product yields, wt%
Coke 6.18 5.80 5.64 5.48 6.03 5.72 6.35
Dry Gas 2.36 2.27 2.18 2.37 2.62 2.23 2.62
LPG 28.68 28.34 28.36 28.61 29.22 28.35 30.38
Gasoline 25.64 26.30 26.42 25.78 24.36 26.36 23.96
HN 8.26 8.36 8.48 8.30 8.18 8.42 7.83
LCO 16.93 17.50 17.55 17.86 17.59 17.53 16.58
TCO(Distillate) 25.19 25.86 26.03 26.16 25.77 25.95 24.41
Bottoms 11.95 11.43 11.37 11.60 12.00 11.40 12.28

The physico-chemical properties as well as performance results of Table-2A & Table-2B indicates that the additive prepared with modified spent catalyst under Example-3,4 5 and 7 showed enhanced the distillate yields and gasoline yields with marginal reduction in bottom yields under FCCU operation.
The additive prepared under Examples-6 where the concentration of modified spent catalyst was over 30 wt% showed enhanced distillate yields and LPG yields with marginal increase in bottom yields. It also showed inferior physical properties w.r.t ABD and attrition resistance properties.
The additive (as per example-7) prepared with modified spent catalyst, but without employing aluminium phosphate binder also showed inferior physical properties w.r.t ABD and attrition resistance properties.
Further, the additive (as per example-8) as prepared with spent catalyst (as such calcined spent catalyst) in combination with aluminium phosphate binder and silica-alumina binder showed increase in LPG yields by 1.7 wt%, increase in bottom yields by 0.33 wt%, decrease in gasoline yield by 1.68 wt%, decrease in distillate yields by 0.78 wt%.
ADVANTAGES
1. The present invention is advantageous as the catalyst composition is prepared by employing low activity spent FCC or RFCC catalyst for further use in FCC/RFCC unit to enhance the yields of high value hydrocarbons.

2. The present invention is advantageous due to efficient process and a catalyst composition from spent catalyst, which enhances the catalytic activity and selectivity of spent catalysts.

3. Furthermore, the present invention relates to a product and process for improving selectivity of spent catalyst through milling, treating with an acidity modifying agent and re-shaping to equivalent fresh FCC catalyst by employing a suitable binder. The catalyst prepared by this route is beneficial in view of disposal of spent FCC catalysts as well as enhancing economy of FCC/RFCC process.

4. The present invention is advantageous to have a process, by which the spent FCC catalyst is re-shaped suitably having adequate physical properties for fluidization and to modify its acid strength so that it can used as an FCC additive for enhancing distillate yields in FCCU.
,CLAIMS:WE CLAIM:

1. A process for preparing a fluid catalytic cracking (FCC) catalyst, comprising:

(a) burning spent catalyst to obtain a de-carbonated spent catalyst;
(b) milling the de-carbonated spent catalyst to obtain a milled de-carbonated spent catalyst;
(c) treating the milled de-carbonated spent catalyst with a source of phosphate in an aqueous media to obtain a modified spent catalyst;
(d) admixing the modified spent catalyst with a binder, a matrix material and a clay to obtain a slurry;
(e) milling the slurry and spray drying to obtain a micro-spheroidal particles; and
(f) calcining the micro-spheroidal particles to obtain the fluid catalytic cracking (FCC) catalyst.

2. The process as claimed in claim 1, wherein the binder is prepared by a process comprising:
(a) dispersing aluminium tri-hydrate in water to get alumina slurry;
(b) adding phosphoric acid to the alumina slurry obtained in step (a) with continues stirring to obtain a clear solution of mono-aluminium phosphate;
(c) diluting mono-aluminium phosphate solution obtained in step (b) with water; and
(d) adding aluminium nitrate to solution obtained in step (c) with continuous stirring to get the binder.
3. The process as claimed in claim 1, wherein the milled de-carbonated spent catalyst having a particle size in the range of 5 to 9 microns.

4. The process as claimed in claim 1, wherein the spent catalyst is burned at a temperature in the range of 500 - 600 °C.

5. The process as claimed in claim 1, wherein the milled de-carbonated spent catalyst is treated with a source of phosphate in aqueous media at temperature in the range of 25 – 90°C.

6. The process as claimed in claim 1, wherein the duration of treating the milled de-carbonated spent catalyst with a source of phosphate in aqueous media is 5 minutes to 12 hours.

7. The process as claimed in claim 1, wherein phosphate is selected from the group consisting of phosphoric acid, ammonium di hydrogen phosphate, ammonium mono hydrogen phosphate, tri-ammonium phosphate, ammonium hypophosphate, ammonium ortho-phosphate, ammonium di hydrogen ortho-phosphate, ammonium mono hydrogen ortho-phosphate, ammonium hypo phosphite, ammonium di hydrogen ortho-phosphite, and mixtures thereof.

8. The process as claimed in claim 1, wherein the matrix material is selected from the group consisting of alumina, silica, silica-alumina and clay.

9. The process as claimed in claim 8, wherein the alumina is selected from the group consting of aluminium oxide, aluminium hydroxide, or aluminium oxyhydroxide.

10. The process as claimed in claim 8, wherein the clay is selected from the group consisting of kaolinite and halloysite and the clay is having size in the range of 1 to 4 microns.

11. The process as claimed in claim 1, wherein the micro-spheroidal particles having size in the range of 5 to 200 microns.

12. The process as claimed in claim 1, wherein the micro-spheroidal particles are calcined at a temperature in the range of 480 - 570 °C.

13. The process as claimed in claim 1, wherein fluid catalytic cracking catalyst is having apparent bulk density in the range of 0.70 – 0.90 gm/ml and attrition index in the range of 2 to 10.

14. The process as claimed in claim 1, wherein the spent catalyst comprises:
zeolite in the range of 1 - 15 wt.%;
silica alumina matrix components in the range of 0.5 – 5 wt. %; and
contaminating metals in the range of 100 - 15,000 ppm,
wherein:
the zeolite is selected from the group consisting of ZSM-5 zeolite, faujasite zeolite, or combination thereof; and
contaminating metals consisting of nickel and vanadium.

15. The process as claimed in claim 1, wherein the spent catalyst has a surface area in the range of 50 - 120 m2/gm, particle size in the range of 5 - 120 microns and apparent bulk density in the range of 0.70 - 0.90 gm/ml.

16. A fluid catalytic cracking (FCC) catalyst, comprising:
modified spent catalyst in the range 5 - 30 wt. %;
binder in the range of 5 - 20 wt. %;
alumina in the range of 5 - 15 wt. %;
silica in the range of 10 - 40 wt. %;
clay in the range of 30 - 50 wt. %;
the percentage being based on weight of the fluid catalytic cracking (FCC) catalyst.

17. The composition as claimed in claim 16, wherein fluid catalytic cracking catalyst is having apparent bulk density in the range of 0.70 – 0.90 gm/ml and attrition index in the range of 2 to 10.

18. The composition as claimed in claim 16, wherein the modified spent catalyst is obtained by:
(a) burning to a spent catalyst at a temperature in the range of 500 - 600 °C to obtain a de-carbonated spent catalyst;
(b) milling the de-carbonated spent catalyst to obtain a milled de-carbonated spent catalyst;
(c) treating the milled de-carbonated spent catalyst with a source of phosphate in an aqueous media to obtain the modified spent catalyst.

19. The composition as claimed in claim 18, wherein the spent catalyst comprises:
zeolite in the range of 1 - 15 wt.%;
silica alumina matrix components in the range of 0.5 – 5 wt. %; and
contaminating metals in the range of 100 - 15,000 ppm,
wherein:
the zeolite is selected from the group consisting of ZSM-5 zeolite; faujasite zeolite, or combination thereof; and
contaminating metals consisting of nickel and vanadium.

20. The composition as claimed in claim 18, wherein the spent catalyst has surface area in the range of 50 - 120 m2/gm, particle size in the range of 5 - 120 microns and apparent bulk density in the range of 0.70 - 0.90 gm/ml.

21. The composition as claimed in claim 16, wherein phosphate is selected from the group consisting of phosphoric acid, ammonium di hydrogen phosphate, ammonium mono hydrogen phosphate, tri-ammonium phosphate, ammonium hypophosphate, ammonium ortho-phosphate, ammonium di hydrogen ortho-phosphate, ammonium mono hydrogen ortho-phosphate, ammonium hypo phosphite, ammonium di hydrogen ortho-phosphite, and mixtures thereof.