FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
"A CATALYST ADDITIVE FOR REDUCTION OF FLUID
CATALYTIC CRACKING (FCC) GASOLINE SULFUR AND
METHOD OF ITS PREPARAITON THEREOF"
We, BHARAT PETROLEUM CORPORATION LIMITED, of Bharat Bhawan, 4 & 6, Currimbhoy Road, Ballard Estate, Mumbai - 400 001, Maharashtra, India.
The following specification particularly describes the nature of the invention and the manner in which it is performed:

A CATALYST ADDITIVE FOR REDUCTION OF FLUID CATALYTIC CRACKING (FCC) GASOLINE SULFUR AND METHOD OF ITS PREPARATION THEREOF
FIELD OF THE INVENTION
The invention relates to method for the preparation of a sulfur reduction catalyst additive and utilizing the said catalyst additive for gasoline sulfur reduction in fluid catalytic cracking {hereinafter referred to as "FCC") process. More particularly, the invention relates to catalyst additive which is prepared by inexpensive refinery spent catalyst of hydrotreating processes by subjecting the spent catalyst to ex situ regeneration. Further, the invention relates to using the said catalyst additive for sulfur removal and reforming along with fresh fluid catalytic cracking {hereinafter referred to as "FCC") catalyst in variable proportions. BACKGROUND AND PRIOR ART OF THE INVENTION
Varieties of catalysts are used in the petroleum refinery operations to improve the process efficiency. The catalysts often contain chemicals (e.g. metals, metal oxide, metal sulfides, inorganic support), which facilitate difficult hydrocarbon transformations with high selectivity and permit the refiners to produce full range of clean transportation fuels with desired specifications from petroleum distillates and residues. The availability of various catalyst and additives allows the refiners to encash quickly the demands of market and meet the product specifications by using available feed stocks. The catalysts used in the refining processes deactivate with time, and is usually regenerated either in situ or ex situ and reused. When the activity of the catalyst declines below the acceptable level, reuse, and regeneration may not be economically feasible and the spent catalysts are discarded as solid wastes. The quantity of spent catalysts discharged from different processing units depends largely on the capacity of the unit, fresh catalysts used, their life and the amount of deposits formed on them during the use in the reactors. In most refineries, a major portion of the spent catalyst as waste come from fluid catalytic cracking (hereinafter referred to as "FCC"), reformer and hydro processing. The volume of spent hydroprocessing or hydrotreating catalysts discarded as solid waste has increased significantly in recent years due to the following reasons: (i) A rapid growth in the distillates hydrotreating capacity to meet the increasing demand for ultra-low sulfur transportation fuels, (ii) Reduced cycle

times due to higher severity operations in hydroprocessing units, (iii) A steady increase in the processing of heavier feed stocks, (iv) Rapid deactivation and unavailability of reactivation process for latest residue hydro processing catalysts. The market demand for hydrotreating catalysts is estimated to increase. The total quantity of spent hydrotreating catalysts generated worldwide is in the range of 150,000-170,000 t/year (Dufresne P. Hydroprocessing catalysts regeneration and recycling. Appl Catal A Gen 322, 2007; 67-75). Disposal of spent catalysts requires compliance with stringent environmental regulations. Spent hydroprocessing catalysts have been classified as hazardous wastes by the environmental protection agency (EPA) in the USA.
As a result of the stringent environmental regulations on spent catalyst handling and disposal, research on the development of process for recycling and reutilization of waste hydrotreating catalysts has received considerable attention. Furimsky (Spent refinery catalysts: environment, safety and utilization. Catal Today 30, 1996; 223-86) reviewed the environmental, disposal and utilization aspects of spent refinery catalysts and the various options studied such as (a) minimizing spent catalyst waste generation (b) utilization to produce new catalysts and other useful materials, (c) recycling through recovery of metals and (d) treatment of spent catalysts for safe disposal, are available to refiners to handle the spent catalyst problem.
The present invention provides a novel method to prepare FCC catalyst additive from inexpensive but hazardous refinery spent catalyst of hydrotreating processes by subjecting the said spent catalyst to ex situ regeneration and reforming. The present invention is a pioneer work towards developing a process for recycling of hazardous waste of hydrotreating refinery spent catalysts and effectively using it in FCC processes for removal of sulfur compounds.
Catalytic cracking is a major secondary conversion process in petroleum refining which converts heavier hydrocarbons to useful value added middle distillates. In the catalytic cracking process heavy hydrocarbon fractions are converted into lighter products by reactions taking place at elevated temperature, in the presence of a catalyst, with the majority of the conversion or cracking occurring in the vapor phase. The feedstock is thereby converted into middle distillate and other lighter gaseous products

of four or less carbon atoms per molecule. During the cracking reactions coke is deposited onto the catalyst which reduces the activity of the catalyst and regeneration is required to regain its activity. The regenerated catalyst is then reused in the cracking step. FCC feed stocks normally contain sulfur in the form of organic sulfur compounds such as mercaptans, sulfides and thiophenes/substituted thiophenes. The products of the cracking process correspondingly tend to contain sulfur impurities even though about half of the sulfur is converted to hydrogen sulfide during the cracking process, mainly by catalytic cracking of non-thiophenic sulfur compounds achieved by use of additives. Sulfur distribution in the cracking products is dependent on a number of factors including feed quality, catalyst type, additives used, conversion and other operating conditions. But, in any case a certain proportion of the sulfur ends up in the light or heavy gasoline fractions and passes over to the product pool. Meeting Euro-IV specifications on gasoline sulfur is becoming essential. FCC gasoline is the main contribution to the refinery gasoline pool, so there is more concern and attention paid to this particular stream.
There are various approaches for FCC gasoline sulfur reduction one approach has been to remove the sulfur from the FCC feed by hydrotreating before cracking is initiated. This route is more effective but cost intensive in terms of requirement of additional reactor and H2 gas requirement and less popular due to octane loss. Another approach is post-treating the cracked products, such as gasoline, after the FCC process. While this may be effective, this approach has the drawback that valuable product octane may be lost when the high octane olefins are saturated. In yet another approach, an additive for sulfur reduction in the regenerator of an FCC unit can be used to reduce sulfur in gasoline without having to treat either the FCC feed or the FCC cracked products.
The art of removing gasoline sulfur from FCC process is well known. Many patents have also been filed for the removal of sulfur from FCC gasoline (US 7347929, 6974787, 6923903, and references cited therein). U.S. 4292288 discloses usage of spent reforming catalyst for reducing CO in FCC regenerator off gas. Notwithstanding the teachings of the prior art and the existing state of technology, there is still need for advanced technologies for effective recycling of the spent refinery catalyst for more

efficient gasoline sulfur reduction in FCC without affecting the FCC product slate. Considering these problems, research is being conducted in this area of technology.
Accordingly, there is a continuous need in this field of technology to provide an improved catalyst for gasoline sulfur reduction in FCC without affecting the FCC product slate. The catalyst should be more efficient in sulfur reduction and at the same time also cost effective so that it can commercialized. OBJECTS OF THE INVENTION
The primary object of the invention is to provide for a method of preparation of gasoline sulfur reduction catalyst additive by ex situ regeneration and reforming of spent refinery catalyst.
Another object of the invention is to provide gasoline sulfur reduction catalyst additive prepared from refinery spent catalyst
Yet another object of the invention is to provide for a method for sulfur removal/reduction in fluid catalytic cracking (FCC) by contacting feed stream with the catalyst additive along with fresh fluid catalytic cracking catalyst in variable proportions.
A further object of the invention is to provide for product streams of light and heavy gasoline fractions with substantially lower amounts of sulfur-containing compounds. SUMMARY OF THE INVENTION
Accordingly, the present invention relates to a process for the preparation of a sulfur reduction catalyst additive comprising:
(i) pretreating hydrotreating spent catalyst by controlled decoking to burn the deposited carbon from the said spent catalyst and simultaneously bring the pore size in the range of 20A to 200A, with average pore size of 80-88 A with a surface area in the range of 200-250 m2/g, pore volume of 0.4 to 0.5 cc/g, bulk density in the range of 0.8 to 0.9 g/ml and attrition index of about 4 - 6 % by weight to obtain pretreated catalyst additive; (ii) sizing the said pretreated catalyst additive obtained from step (i) by crushing and sieving to obtain a sulfur reduction catalyst additive having required particle size in the range of 20-180 microns.

In a preferred embodiment of the process of the invention, the said controlled decoking comprises heating the said hydrotreating spent catalyst at the rate of 2°C/minute till the reaction temperature reaches around 550°C, dwelling the reaction mixture at about 300-550°C for 2-6 hours in an controlled oxygen atmosphere.
The present invention also relates to a gasoline sulfur reduction catalyst additive comprising:
(a) from 0.01 to 20 % by weight of a metal of group VI B, and
(b) from 0.01 to 6 % by weight of a metal of Group VIII,
wherein the said catalyst additive is incorporated on a mesoporous inorganic oxide support material having uni-model pore distribution with pores in the range of 20A to 200A, with average pore size of 80-88 A with a surface area in the range of 200-250 m2/g, pore volume of 0.4 to 0.5 cc/g, bulk density in the range of 0.8 to 0.9 g/ml and attrition index of about 4 - 6 % by weight.
In a preferred embodiment of the invention the said of the catalyst additive support is gamma alumina.
In another preferred embodiment of the invention the said metal of Group VIB of the catalyst additive is Molybdenum, preferably in the range of 2-20 wt%.
In yet another preferred embodiment of the invention, the said metal of Group VIII of the catalyst additive is cobalt, preferably in the range of l-6wt%.
In a preferred embodiment of the invention, the catalyst additive comprises 1-80 wt% alumina, 1-20 wt% Molybdenum and 0.01 - 5 wt% Cobalt.
In another preferred embodiment of the invention, the gasoline sulfur reduction catalyst additive has lewis acid sites.
The present invention also relates to a sulfur reduction Fluid Catalytic Cracking (FCC) catalyst composition comprising catalyst additive in combination with fresh base FCC catalyst for reducing the gasoline sulfur in FCC process by contacting the said composition with FCC feed.
The present invention further relates to use of sulfur reduction catalyst additive, for reducing gasoline sulfur in Fluid Catalytic Cracking (FCC) process comprising addition of catalyst additive as claimed in any preceding claim to the FCC regenerator along with fresh base FCC catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention can be more fully understood by reference to the following detailed description of the invention and to the accompanying drawings, in which:
Figure 1: Shows the comparative pore size distribution of catalyst additive of the invention after reforming.
Figure 2 : Shows the pore size distribution of refinery spent catalyst. DETAILED DESCRIPTION OF THE INVENTION
Accordingly, the present invention provides for a catalyst additive useful in fluid catalytic cracking processes. The catalyst additive of the invention is capable of reducing sulfur compounds normally found in gasoline fraction of fluid catalytic process. The present invention therefore also, provides product streams of light and heavy gasoline fractions with substantially lower amounts of sulfur-containing compounds. The reduction of gasoline sulfur in FCC is achieved by using catalyst additive of the invention which is prepared by inexpensive refinery spent catalyst along with fresh FCC main cracking catalyst in variable proportion. The present invention discloses reusing the spent refinery catalyst in FCC for sulfur removal by subjecting the spent catalyst by way of ex situ regeneration and reforming it. The spent refinery inexpensive catalyst is regenerated before mixing with the fresh catalyst.
The catalyst additive of the invention is used for the removal of sulfur from catalytically cracked vacuum gas oil stream. The catalyst additive of the invention is prepared by the use of spent refinery catalyst and is effective in removal of sulphur compounds when added in a suitable ratio with FCC catalyst. The spent refinery catalyst is no longer efficient in a refinery process for the desired application where it was used when fresh. However, it is effective for reduction of gasoline sulfur after regeneration and reforming to desired particle size.
Accordingly, the present invention discloses a better gasoline sulfur reduction catalyst additive for use in fluid catalytic cracking comprising active elements (a) from 0.01 to 20 % by weight of a group VIB and (b) from 0.01 to 6 % by weight of a metal of Group VIII, wherein said catalyst is present on a supported material.
The present invention also discloses a method of making improved gasoline sulfur reduction catalyst additive using spent refinery regenerated catalyst comprising

above materials with uni-model pore distribution in the range of 20-200 A with a peak maximum centered at 80-90 A (Fig-1). The pore size distribution of refinery spent catalyst as such lies in the range of 40-175 A with peak maxima centered at 70-80 A (Fig-2).
The gasoline sulfur reduction catalyst additive has lewis acid sites along with other metals/elements or their compounds from groups VI and VIII. In one embodiment, group VI metal is Molybdenum. In another embodiment, group VIII metal is Cobalt. In a further embodiment, the gasoline sulfur reduction catalyst additive comprises 1-80 wt % alumina, 1-20 wt% Molybdenum, 0.01 - 5 wt% Co.
The spent regenerated catalyst have characteristic properties like surface area in the range of 200-250m /g, pore volume of 0.4 to 0.6 ml/g, apparent bulk density in the range of 0.7-0.9 g/cc, ASTM attrition index of about 1-5 wt % and average particle size of 60-80 microns.
The invention provides for a novel gasoline sulfur reduction catalyst additive where the additive is produced by controlled decoking of the spent catalyst and sizing the particles to FCC catalyst range. The present invention also describes a method for catalytically reducing the gasoline sulfur in FCC reactor by contacting with spent regenerated hydroprocessing catalyst when used along with FCC fresh catalyst or equilibrium catalyst.
The catalyst additive of the invention comprises 0.01 to 20.0% of a group VI transition metal or a compound thereof on a porous inorganic oxide base which promotes the reduction of sulfur under FCC regenerator conditions. The metal component of the catalyst may additionally be comprised of bimetallic admixtures such as group VIII and group VI and others which are known to catalyze the reduction of sulfur (Hydrotreating catalysis: Science and Technology by Topsoe et al, Springer verlag, Berlin, Vol II, 1996, edited by J.R Anderson and M. Boudart), The above described metals may also be present in the form of oxide, sulfide, or other. Essential feature of the catalyst additive of the invention is that it is a spent hydrotreating catalyst containing lewis acidity on refractory alumina support. The main feature of the invention is use of regenerated spent hydrotreating catalyst containing transition metals. This discarded material is no longer active to achieve the desired low sulfur levels

when used in its original application. But the spent regenerated hydro treating catalyst containing transition metals/their oxide can reduce the gasoline sulfur in FCC process under operating conditions of plant.
As described in literature {Hydrotreating catalysis: Science and Technology by Topsoe et al, Springer verlag, Berlin, Vol II, 1996, edited by J.R Anderson and M. Boudarf) and references cited therein the support material used to make hydrotreating catalysts is gamma alumina type with required mechanical properties and ABD of 0.8 to 0.9 gm/cc.
In order to verify the composition of spent hydrotreating catalyst which works for gasoline sulfur reduction in FCC, few formulations were made using commercial support with similar properties and incorporating the metals of group VI and VIII either by wet impregnation or equilibrium adsorption method followed by drying and calcinations at suitable conditions known to the specialists in this art.
The catalyst additives described above may be added to the Fluid Catalytic Cracking Units (hereinafter referred to as "FCCU") without changing the mode of operating conditions. The catalyst additive particles may be added directly to the cracking stage, to the regeneration stage of the cracking apparatus or at any other suitable point. The catalyst additive particles may be added to the circulating catalyst inventory while the cracking process is underway or they may be present in the inventory at the start-up of the FCC operation.
As an example, the catalyst additive of this invention can added to a FCCU when replacing existing equilibrium catalyst inventory in addition to the fresh catalyst. The refiner usually balances the cost of new catalyst addition to the inventory with respect to the production of desired hydrocarbon product fractions. Under FCCU reactor conditions carbocation reactions occur to cause molecular size reduction of petroleum hydrocarbon feedstock introduced into the reactor. As fresh catalyst equilibrates within FCCU, it is exposed to various conditions, such as the deposition of feedstock contaminants produced during the reaction and severe regeneration operating conditions. Thus, equilibrium catalysts may contain high levels of metal contaminants, exhibit somewhat lower activity, have lower aluminum content in the zeolite framework and have different physical properties than fresh catalyst. In normal

operation, refiners withdraw small amount of the equilibrium catalyst from the regenerators and replace it with fresh catalyst to control the quality (e.g., its activity and metal content) of the circulating catalyst inventory.
The FCC process using the catalyst additive of this invention is conducted in conventional FCC units wherein the reaction temperatures range from about 400°C to 600°C, with regeneration occurring at temperatures from about 500°C to 800°C. The particulars will depend on the petroleum feedstock being treated, the product streams desired and other conditions well known to refiners. The FCC catalyst is circulated within the unit in a continuous manner between catalytic cracking and regeneration zones while maintaining the desired level of catalyst inventory in the reactor.
The effect of the present catalyst additive and process of using the same is to reduce the sulfur content, especially those associated with thiophenes and substituted thiophenes and benzothiophene of the light products (e.g. those of the gasoline fraction having a boiling point of up to about 220°C in a FCCU product fraction). Thiophenic and benzothiophene compounds are major constituents of gasoline present in higher boiling range and these are difficult to crack. It is generally believed that thiophene conversion requires hydrogen transfer (HT) reactions before cracking (Scheme-1).

Gasoline sulfur reduction mechanism is not fully understood. However it is believed that the reduction follows cracking of sulfur species formed in the process to release H2S, or inhibition of formation of sulfur compounds. Harding et al. ("New developments in FCC technology" Appl. Catal. A 221 (2001), P389) have proposed that gasoline sulfur reduction additives primarily enhance the rate of tetra hydro thiophene (THT) cracking to H2S, thus preventing its conversion to thiophene by hydrogenation reactions.
Alternatively, gasoline sulfur reduction could be due to improved hydrogen transfer to thiophenic species initiated by the increase of coke production (Anderson et al, Catal. Today, 53 (1999) 565, T. Myrstad et al . Catal. A Gen. 87 (1999) 207). More recently, Shan et al. and Vargas et al (Shan et al, Catal.Today, 77 (2002) 117

and Vargas et al Catal. Today 107-108 (2005) have proposed that sulfur reduction occurs by strong adsorption of thiophenic species on Lewis acid sites of the additive and further cracking.
The exact amount of sulfur compounds contained in the gasoline fractions produced by conventional FCC process depends on the sulfur content of the feed that is processed. Gasoline cuts from FCC process normally have a boiling point ranging up to 220 °C. In general, the sulfur content of the whole of FCC gasoline is over 300 ppm by weight. When the end point of the cut is greater than 220 °C, the sulfur content can be over 1000 ppm by weight. Removal of the sulfur contaminants is beneficially accomplished when using the FCC catalyst composition of the present invention. The degree of reduction readily achieved depends on the amount of Lewis Acid component in the catalyst inventory. The sulfur is generally converted to inorganic form and released as hydrogen sulfide. This material can be readily recovered in the mariner as is conventional for FCC processes. The increased load of increased hydrogen sulfide recovery is not deemed critical or economically detrimental when taking into consideration the improved, reduced sulfur content of light hydrocarbon products formed. The sulfur reduction performance described above is based on tests conducted in a lab bench scale unit. The product analysis was carried out using GC-SCD.
Base experiments were carried out without catalyst additive. Base experiments were conducted to compare the activities and efficiency of the presently available FCC catalyst and the FCC catalyst additive prepared by the method of the invention. Composition of the presently used/available FCC catalyst is known in the area of this technology and is being referred to as "base FCC catalyst" hereinafter.
The catalyst additive of the present invention improves the sulfur reduction activity when it is used in the concentration of 10 wt% in base FCC catalyst. Higher concentrations of the additive viz 10-30 wt% gives more activity. The catalyst additive is stable having gasoline sulfur reduction activity when used in FCC reactor.
For the purposes herein, and/or the examples below, and unless otherwise stated, the terms below have the definitions indicated.
(i) "Fresh" fluid cracking catalyst is the base FCC catalyst, as manufactured and sold by catalyst vendors.

U 3 SEP 2010

(ii) "Equilibrium" fluid catalytic cracking catalyst (E-Cat) is the catalyst drawn from the inventory of circulating catalyst after certain time.
(iii) The hydrocarbon stripped coke laid catalyst which was taken out from the FCC stripper is referred as "Spent catalyst".
(iv) "SA" is Surface Area.
(v) "AP is Attrition Index.
(vi) "ABD" is Average Bulk Density.
(vii) "APS" is Average Particle Size. MAIN ADVANTAGES OF THE INVENTION
• Recycling of refinery spent catalyst thereby partly addressing the problem of disposal of hydro processing catalysts
• Providing an effective way of using the refinery spent hydro processing catalyst as catalyst additive for sulfur reduction in FCC process obtained by a novel method of reforming and regeneration of the spent catalyst.
• Development of cost effective FCC catalyst additive with better physical properties.
• Substantially improving the catalytic activity of base FCC catalyst by adding the catalyst additive of the invention in the various proportions.
• Providing a novel, cost effective, environment friendly and easy to carry out method for reforming, regeneration and recycling of the waste spent catalysts.
The following examples describe preferred embodiments of the invention. The specific examples given herein, however, should not to be construed as forming the only genus that is considered as the invention, and any combination of the process or their steps may itself form a genus. Other embodiments within the scope of the claims herein will be apparent to one skilled in the art from consideration of the specification or practice of the invention as disclosed herein. The following examples demonstrate the procedure for making the additive catalyst having improved properties as described in the present invention. These examples also compare various approaches made to arrive at a better catalyst composition.
The properties of gasoline sulfur reduction catalyst additive of the present invention are summarized in Table-3 and Table-4.

EXAMPLES
Gasoline sulfur reduction catalyst additive activity studies as described in the examples hereinafter were carried out in a fixed bed quartz reactor. The reaction was carried out in an isothermal condition. Synthetic feed containing known thiophenic sulfur compounds in n-octane was used for all the runs. Total feed sulfur concentration was fixed as 2000 ppm. All the catalyst additives evaluation was carried out with 10.0 wt% additive along with the fixed amount of base equilibrium catalyst. Nitrogen gas was used as carrier during the reaction. The reaction was carried out for two hours at 510°C with a C/O ratio of 6. Liquid product samples were stripped off for dissolved H2S gas and analyzed for total sulfur using thermo euro glass analyzer and GC-SCD as per ASTM method.
The following equation is used to define the sulfur reduction activity: "Sulfur reduction Activity (%) = (Sulfur in feed-Sulfur in product)/ Sulfur in feed *100"
Examplc-1
Property Catalyst-1
SA( m2/g) 190
AI (wt%) 4
ABD( g/cc) 0.8
APS(u) 81
Sulfur reduction activity (%) 8
As a base experiment, known amount of base FCC catalyst (i.e. FCC commercial equilibrium catalyst without any catalyst additive) was evaluated in a fixed bed reactor as described above. The product collected is analyzed for total sulfur and this is considered as base experiment for the purpose of comparison. The properties of E-cat and activity for sulfur reduction is given in Table-1 below. Table: 1
Property Catalyst-1
SA( m%) 190
AI (wt%) 4
ABD( g/cc) (U
APS(μ) 81
Sulfur reduction activity (%) 8
Example-2

A 10 wt% commercially available sulfur reduction catalyst additive along with the known weight of equilibrium catalyst was tested under similar conditions as described in example-1. The properties and the activity results are given in Table-2 below. Table-2
Property Catalyst 2
SA( m'/g) 185
AI (wt %) Tb
ABD(g/cc) [ 0~!9
APS(u) 72
Sulfur reduction Activity (%) 50
(Excluding base catalyst activity)
Even though this additive has better sulfur reduction activity, it is not preferred to use
commercially in reactors/plants due to its poor attrition strength.
Example-3
Spent refinery hydrotreating catalyst was used as sulfur reduction additive in FCC after suitable treatment. The hydrotreating catalyst, a composite material, contains alumina based material whose catalytic activity diminishes over a period of time. The loss in activity is mainly due to the attainment of end of the run conditions. Based on the published information (Hydrotreating catalysis: Science and Technology by Topsoe et al, Springer Verlag, Berlin, Vol II, 1996, edited by J.R. Anderson and M. Boudart) the spent hydrotreating catalyst contains about l-80wt% of a gamma alumina, 1-20wt% of Molybdenum, 1-5 wt% of Cobalt. Coke on spent catalysts was burned off by controlled heating in a controlled oxygen atmosphere (i.e. Oxygen 2-5 vol% in an inert gas like Nitrogen) thereof for 2-6 Hrs at 300-550°C. The coke free spent catalyst was crushed to a fine powder with an average particle size of about 60-80 microns. The coke freed powdered catalyst contains unimodal pore distribution having pores in the range of 20-200A and with average pore size distribution of 88A calculated by BJH equation using desorption. branch. (Fig-1). The modified spent hydro treating catalyst

which is used as FCC sulfur reduction additive is designated as Catalyst 3. Properties of the finished additive are as given below. Table -3:

Property Catalyst 3
SA(mVg) 210
AI (Wt%) 6.0
ABD (g/ml) 0.9
APS (μ) 75
Sulfur reduction activity, (%)
With 10% additive 61
With 20% additive 75
With 30% additive 86
This gasoline sulfur reduction additive prepared using the spent hydrotreating catalyst was found to be active and activity has increased with increasing amount of additive. The catalyst additive works well in presence of FCC main cracking catalyst when used in the range of 10-30 wt%. The additive also has better attrition strength compared to commercially available additives.
Example-4
Another gasoline sulfur reduction catalyst was prepared by using a commercially available porous, high surface area λ-alumina with an average particle size of 20-120 microns as support. The support material contains unimodal pore distribution having majority of the pores in the range of 20-100A. Gasoline sulfur reduction additive was prepared by depositing desired amount of Mo and Co on support by wet impregnation method using molybdenum and cobalt salts. The support was calcined at 500°C in air for 4 Hrs, before incorporating active metals. After impregnation the material was dried at 110-120°C for 16 Hrs and calcined at 500-550°C for 4 Hrs. This sample is referred as Catalyst 4. Catalyst 4 was tested for sulfur reduction activity as per the procedure described in the other examples. The above described catalyst had the following characteristics and activity.

able 4 :
Property Catalyst 4
SACmVg) 250
AI (wt%) 10
ABD(g/cc) 0.8
APS 56
Sulfur reduction activity, % (Excluding base catalyst activity) 58
Though Sulfur reduction activity of the above gasoline sulfur reduction additive catalyst is higher, it is not considered because of its poor attrition property. However it is clear that catalyst containing Co and Mo on gamma alumina support with the above describe properties acts as catalyst for removal of sulfur in gasoline range.

We Claim:
1. A process for the preparation of a sulfur reduction catalyst additive comprising: (i) pretreating hydrotreating spent catalyst by controlled decoking to burn the deposited carbon from the said spent catalyst and simultaneously bring the pore size in the range of 20A to 200A, with average pore size of 80-88 A with a surface area in the range of 200-250 m2/g, pore volume of 0.4 to 0.5 cc/g, bulk density in the range of 0.8 to 0.9 g/ml and attrition index of about 4-6 % by weight to obtain pretreated catalyst additive; (ii) sizing the said pretreated catalyst additive obtained from step (i) by crushing and sieving to obtain a sulfur reduction catalyst additive having required particle size in the range of 20-180 microns.
2. The process as claimed in claim 1, wherein the said controlled decoking comprises heating the said hydrotreating spent catalyst at the rate of 2°C/minute till the reaction temperature reaches around 550°C, dwelling the reaction mixture at about 300-550°C for 2-6 hours in an controlled oxygen atmosphere.
3. A gasoline sulfur reduction catalyst additive comprising:

(a) from 0.01 to 20 % by weight of a metal of group VI B, and
(b) from 0.01 to 6 % by weight of a metal of Group VIII,
wherein the said catalyst additive is incorporated on a mesoporous inorganic oxide support material having uni-model pore distribution with pores in the range of 20A to 200A, with average pore size of 80-88 A with a surface area in the range of 200-250 m2/g, pore volume of 0.4 to 0.5 cc/g, bulk density in the range of 0.8 to 0.9 g/ml and attrition index of about 4 - 6 % by weight.
4. The catalyst additive as claimed in claim 3, wherein the said support is gamma
alumina.

i. The catalyst additive as claimed in any preceding claim, wherein the said metal of Group VIB is Molybdenum, preferably in the range of 2-20 wt%.
6. The catalyst additive as claimed in any preceding claim, wherein the said metal of Group VIII is cobalt, preferably in the range of l-6wt%.
7. The catalyst additive as claimed in any preceding claim comprising 1-80 wt% alumina, 1-20 wt% Molybdenum and 0.01-5 wt% Cobalt.
8. The catalyst additive as claimed in any preceding claim, wherein the gasoline sulfur reduction catalyst additive has lewis acid sites.
9. A sulfur reduction Fluid Catalytic Cracking (FCC) catalyst composition comprising catalyst additive as claimed in claims 3 to 8 in combination with fresh base FCC catalyst for reducing the gasoline sulfur in FCC process by contacting the said composition with FCC feed.
10. Use of sulfur reduction catalyst additive as claimed in claims 3 to 9, for reducing gasoline sulfur in Fluid Catalytic Cracking (FCC) process comprising addition of catalyst additive as claimed in any preceding claim to the FCC regenerator along with fresh base FCC catalyst.