Description:FIELD OF THE INVENTION

The present invention provides a catalyst additive composition for reducing sulfur in gasoline. More particularly, the present invention provides a catalyst additive composition comprising 10-50 wt. % of silica, 40-80 wt. % of alumina, 1-20 wt.% of copper oxide, 1-20 wt.% of cerium oxide, and 0.1-5 wt.% of zinc oxide. The present invention also provides a process for preparing the catalyst additive composition. The catalyst additive composition comprises Ce-Zn alloyed Cu with oxygen vacancy for sulfur removal and is developed by using mixed metal oxide system. The catalyst additive composition shows higher sulfur reduction and olefine retention compared to conventional technology.

BACKGROUND OF THE INVENTION

Environmentally driven regulations throughout the world demand dramatic improvements in the quality of transportation fuels gasoline and diesel. Sulfur in gasoline and diesel fuels not only contribute directly to SOx emission in the exhaust gases but also poison catalytic converter in automobiles. Therefore, the refiners are under constant environmental pressure to achieve more rigorous standards on sulfur content in fuel used in transportation sector. In India, BS VI standards was effective from April 1, 2020, and the new gasoline specification requires sulfur, aromatics and research octane number (RON) content to be 10 ppm (maximum), 35 vol % and 91 (minimum) respectively. In the refinery, commercial gasoline pool is made up of different fractions coming from reforming, isomerization and fluid catalytic cracking (FCC). The gasoline from FCC makes up about 30-35 vol % of gasoline blend stocks/pool, and at the same time accounts for over 90% of the sulfur (90-98%) and olefins in the entire gasoline pool. Therefore, desulfurization of FCC gasoline without sacrificing research octane number (RON) is very important to make it acceptable for various applications.

Different approaches are available to reduce sulfur content in FCC gasoline, which includes (i) reducing the end boiling point of the gasoline stream, but this will add sulfur in the light cycle oil (LCO) stream and can be removed by LCO hydrotreater, (ii) pre-treating the FCC feed to remove sulfur through FCC feed hydrotreater, but the disadvantage of FCC feed hydrotreatment is its high opex and capex, (iii) post-treatment of the gasoline product leads to a significant loss of octane number and yield, (iv) processing of relatively light and low-sulfur crude oil, which can force the refiner into purchasing more expensive feeds and (v) use of gasoline sulfur reduction FCC catalyst additives along with main catalyst. Sulfur reduction by use of additive along with base catalyst inside the FCC unit offers economic advantages over the pre-treatment and post-treatment processes.

US4,957,892 discloses an improved process for converting hydrocarbons using a catalyst which is periodically regenerated to remove carbonaceous deposits, the catalyst being comprised of a mixture containing, as a major component, solid particles capable of promoting hydrocarbon conversion at hydrocarbon conversion conditions, and, as a minor component, discrete entities comprising at least one spinel, preferable alkaline earth metal-containing spinel; thereby reducing the amount of sulfur oxides exiting the catalyst regeneration zone. Improved hydrocarbon conversion catalysts are also disclosed.

US6,379,536 discloses a composition comprising a component containing (i) an acidic oxide support, (ii) an alkali metal and/or alkaline earth metal or mixtures thereof, (iii) a transition metal oxide having oxygen storage capability, and (iv) a transition metal selected from groups Ib and/or IIb of the periodic table provide NOx control performance in FCC processes. The acidic oxide support preferable contains silica alumina. Ceria is the preferred oxygen storage oxide. Cu and Ag are preferred group I/II b transition metals. The compositions are especially useful in the cracking of hydrocarbon feedstocks having above average nitrogen content. US5,990,030 discloses that sulfur oxides are removed in the regenerator zone and rapidly released as H2S in the reactor zone of an FCC system employing a particulate SOx reducing additive comprising an alkali metal oxide. Embodiments comprise the incorporation of an inorganic support, MgO, CeO2 or Ag and V2O5.

US7,033,487 discloses a catalyst composition comprising about 5-55 wt. % metal doped anionic clay, about 10-50 wt. % zeolite, about 5-40 wt. % matrix alumina, about 0-10 wt. % silica, about 0-10 wt. % of other ingredients, and balance kaolin. In metal-doped anionic clays, the additive, i.e. the metal dopant, is distributed more homogeneously within the anionic clay than in impregnated anionic clays, without Separate phases of additive being present. Hence, abrasion of this catalyst composition will result in microfines poorer in additive than the prior art composition. Furthermore, the catalyst composition according to US7,033,487 results in a higher reduction of sulfur in fuels such as gasoline and diesel than is the case in composition comprising impregnated anionic clay.

US7,347,929 discloses novel methods for reducing sulfur in gasoline with hydrotalcite like compound additives, calcined hydrotalcite like compounds, and/or mixed metal oxide solution. The additives can optionally further comprise one or more metallic oxidants and/or supports. US7,347,929 is also directed to methods for reducing gasoline sulfur comprising contacting a catalytic cracking feedstock with a mixed metal oxide compound comprising magnesium and aluminum and having X-ray diffraction pattern displaying a reaction at least at a two theta peak position at about 43 degrees and about 62 degrees, wherein the ratio of magnesium to aluminum in the compound is from about 1:1 to about 10:1.

US9,403,155 and US8,409,428 disclose a novel additive composition for reducing sulfur content of a catalytically cracked gasoline fraction. This additive composition comprises a support consisting of porous clay into which a first metal from group IVB is incorporated and a second metal from group IIB is impregnated. Preferably, the first incorporated metal is zirconium and the second impregnated metal is zinc. The sulfur reduction additive is used in the form of a separate particle in combination with a conventional cracking catalyst in a fluidized catalytic cracking process to convert hydrocarbon feedstocks into gasoline having comparatively lower sulfur content and other liquid products.

US10,787,613 disclose a copper alumina spinel composition with different pore structure for the enhanced gasoline sulfur reduction for FCC gasoline. This additive comprises an active material as spinel.

US7431825B2 discloses gasoline sulfur reduction using hydrotalcite like compounds. US 6,852,214B1 discloses gasoline sulfur reduction in fluid catalytic cracking. US 6,036,847 discloses compositions for use in catalytic cracking to make reduced sulfur content gasoline. US 6,497,811 discloses reduction of sulfur content in FCC naphtha. US 6,482,315B1 discloses gasoline sulfur reduction in fluid catalytic cracking. KR20090004963A discloses catalyst composition reducing gasoline sulfur content in catalytic cracking process.

Hence, there is a need to further improve the reduction of sulfur in gasoline during the fluid catalytic cracking process cycle. The invention is directed to improved catalyst additive composition and provides higher Sulfur reduction and olefine retention compared to conventional technology. Also, the newly developed catalyst additive composition is cost effective.

SUMMARY OF THE INVENTION:

This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended to determine the scope of the invention.

The present invention provides a catalyst additive composition for reducing sulfur in gasoline comprising:
(i) silica as SiO2 in a range of 10-50 wt. % with respect to the catalyst additive composition;
(ii) alumina as Al2O3 in a range of 40-80 wt. % with respect to the catalyst additive composition;
(iii) copper oxide as CuO in a range of 1-20 wt.% with respect to the catalyst additive composition;
(iv) cerium oxide as CeO2 in a range of 1-20 wt.% with respect to the catalyst additive composition; and
(v) zinc oxide as ZnO in a range of 0.1-5 wt.% with respect to the catalyst additive composition,
wherein the composition comprises Ce-Zn alloyed Cu with oxygen vacancy for sulfur removal.

The present invention also provides a process for preparing catalyst additive composition for reducing sulfur in gasoline comprising:
(a) dissolving a zinc precursor, a cerium precursor, a copper precursor and an aluminum precursor in water to obtain a solution A;
(b) adding sodium hydroxide in water to obtain a solution B;
(c) heating water and adding the solution A and solution B simultaneously under stirring at pH in a range of 9-10.5 to obtain a precipitate;
(d) washing, drying and calcining the precipitate to obtain a calcined material;
(e) mixing the calcined material, kaolin clay, pseudoboehmite alumina, aluminium nitrate nonahydrate in water to obtain a slurry;
(f) milling the slurry to reduce particle size and obtaining a final slurry; and
(g) sieving, spray drying and calcining the final slurry to obtain the catalyst additive composition.

The present invention also provides a method of reducing the concentration of sulfur in cracked gasoline in an FCC unit comprising contacting catalytic cracking feedstock oil with an effective amount of the catalyst additive composition as described herein along with a FCC catalyst at a temperature in a range of 510 to 580°C, injection time in a range of 2 to 75 sec, and feed rate in a range of 1 to 3 gm/min.

BRIEF DESCRIPTION OF THE DRAWING

To further clarify advantages and aspects of the disclosure, a more particular description of the present disclosed process will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawing(s) and explained hereinafter in the description section. It is appreciated that the drawing(s) as provided herein depicts only typical embodiments of the process and are therefore not to be considered limiting of its scope.

Figure 1 represents the increases in the oxygen vacancy in the catalyst additive composition increasing trend in the sulfur removing capacity of the catalyst.

DETAILED DESCRIPTION OF THE INVENTION

Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps of the process, features of the system, referred to or indicated in this specification, individually or collectively and all combinations of any or more of such steps or features.

The articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”.

Throughout this specification, unless the context requires otherwise the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of elements or steps but not the exclusion of any other element or step or group of element or steps.

The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred method, and materials are now described.

The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products and processes are clearly within the scope of the disclosure, as described herein.

The present invention provides a catalyst additive composition for reducing sulfur in gasoline comprising:
(i) silica as SiO2 in a range of 10-50 wt. % with respect to the catalyst additive composition;
(ii) alumina as Al2O3 in a range of 40-80 wt. % with respect to the catalyst additive composition;
(iii) copper oxide as CuO in a range of 1-20 wt.% with respect to the catalyst additive composition;
(iv) cerium oxide as CeO2 in a range of 1-20 wt.% with respect to the catalyst additive composition; and
(v) zinc oxide as ZnO in a range of 0.1-5 wt.% with respect to the catalyst additive composition.

In one of the embodiments of the present invention, the catalyst additive composition as described herein comprises Ce-Zn alloyed Cu with oxygen vacancy for sulfur removal.

In yet another embodiment of the present invention, the catalyst additive composition is developed by using mixed metal oxide system.

In yet another embodiment of the present invention, the catalyst additive composition has apparent bulk density (ABD) in a range of 1.05 to 1.12g/cc, attrition index (AI) in a range of 2.2 to 3.1 % (ASTM D5757), surface area (SA) in a range of 129 to 148 m2/g, pore volume (PV) in a range of 0.40 to 0.42 m3/g, and relative oxygen vacancy in a range of 48% to 77%.

In one of the preferred embodiments of the present invention, the catalyst additive composition comprises 25 wt. % of SiO2, 60 wt. % of Al2O3, 10 wt. % of CuO, 1-20 wt.% of CeO2, and 0.1-5 wt. % of ZnO with respect to the additive composition.

The present invention also provides a process for preparing catalyst additive composition for reducing sulfur in gasoline comprising:
(a) dissolving a zinc precursor, a cerium precursor, a copper precursor and an aluminum precursor in water to obtain a solution A;
(b) adding sodium hydroxide in water to obtain a solution B;
(c) heating water and adding the solution A and solution B simultaneously under stirring at pH in a range of 9-10.5 to obtain a precipitate;
(d) washing, drying and calcining the precipitate to obtain a calcined material;
(e) mixing the calcined material, kaolin clay as silica source, pseudoboehmite alumina, aluminium nitrate nonahydrate in water to obtain a slurry;
(f) milling the slurry to reduce particle size and obtaining a final slurry; and
(g) sieving, spray drying and calcining the final slurry to obtain the catalyst additive composition.

In one of the embodiments of the present invention, water used in step (a) and step (c) of the process as described herein is distilled water. Water used in step (e) of the process as described herein is demineralized water (DM water).

In another embodiment of the present invention, in step (f) of the process as described herein, the slurry is milled to reduce the particle size of less than 1 micron to obtain the final slurry.

In yet another embodiment of the present invention, the process for preparing catalyst additive composition as described herein comprises step of dissolving 0.1-5 wt.% of the zinc precursor, 1-20 wt.% of the cerium precursor, 1-20 wt.% of the copper precursor and 40-80 wt. % of the aluminum precursor in water to obtain the solution A.

In yet another embodiment of the present invention, the zinc precursor is selected from the group comprising zinc nitrate hexahydrate, zinc sulphate monohydrate, zinc chloride hexahydrate, and zinc acetate dihydrate.

In yet another embodiment of the present invention, the cerium precursor is selected from the group comprising cerium nitrate hexahydrate, Cerium(III) chloride heptahydrate, and Cerium triacetate.

In yet another embodiment of the present invention, the copper precursor is selected from the group comprising copper nitrate trihydrate, copper sulphate pentahydrate, and copper chloride dihydrate.

In yet another embodiment of the present invention, the aluminum precursor is selected from the group comprising aluminum sulphate octadecahydrate, aluminum nitrate nonahydrate, and aluminum chloride.

In yet another embodiment of the present invention, in step (c) of the process as described herein, water is heated at a temperature in a range of 70 to 90°C; and after complete addition of the solution A and solution B, a reaction mixture is obtained and the reaction mixture is stirred for 1 to 3 h at 80°C to obtain the precipitate, wherein the precipitate is bluish green precipitate. In one of the preferred embodiments of the present invention, in step (c) of the process as described herein, water is heated at a temperature of 80°C; and after complete addition of the solution A and solution B, a reaction mixture is obtained and the reaction mixture is stirred for 1 h at 80°C to obtain the precipitate, wherein the precipitate is bluish green precipitate.

In yet another embodiment of the present invention, in step (d) of the process as described herein, washing is carried out with distilled water at a temperature in a range of 70 to 90°C for 4-5 times to reduce impurities to obtain a washed material; drying of the washed material is carried out for 8 to 15 h at 100 to 150°C to obtain a dried material, calcining of the dried material is carried out at 600 to 900°C for 4 to 10 h. In one of the preferred embodiments of the present invention, in step (d) of the process as described herein, washing is carried out with distilled water at temperature above 80°C for 4-5 times to reduce impurities to obtain a washed material; drying of the washed material is carried out for about 10 h at 120°C to obtain a dried material, calcining of the dried material is carried out at 700°C for 5 h.

In yet another embodiment of the present invention, in step (g) of the process as described herein, the spray drying is carried out in a co-current spray drier unit at inlet temperature in a range of 300 to 500°C and outlet temperature in a range of 120 to 250°C; and after spray drying, the calcination is carried out at a temperature in a range of 500 to 700°C for 2 to 5 h. In one of the preferred embodiments of the present invention, in step (g) of the process as described herein, the spray drying is carried out in the co-current spray drier unit at inlet temperature of 450°C and outlet temperature of 210°C; and after spray drying, the calcination is carried out at temperature of 600°C for 4 h.

The present invention also provides a method of reducing the concentration of sulfur in cracked gasoline in an FCC unit comprising contacting catalytic cracking feedstock oil with an effective amount of the catalyst additive composition as described herein along with a FCC catalyst at a temperature in a range of 510 to 580°C, injection time in a range of 2 to 75 sec, and feed rate in a range of 1 to 3 gm/min. In one of the preferred embodiments of the present invention, in the method as described herein, the catalytic cracking feedstock oil is contacted with an effective amount of the catalyst additive composition as described herein along with the FCC catalyst at temperature of 540°C, injection time of 30 sec, and feed rate of 2.5 gm/min.

In one of the embodiments of the present invention, the Catalyst Load is in a range of 6 to 9 gm and Catalyst-to-Oil ratio in a range of 4.84 to 7.25 wt./wt. In one of the embodiments of the present invention, the term Catalyst includes both the catalyst additive composition and FCC catalyst.

The present invention discloses catalyst additive composition for reducing gasoline sulfur during catalytic cracking process. The catalyst composition consists of Ce-Zn alloyed Cu with higher oxygen vacancy provides better sulfur removal efficiency than mixed metal oxide structure. It also discloses the method of making new catalyst additive. The catalyst additive composition of the present invention is used in FCC unit along with main FCC catalyst. The results show higher sulfur reduction and olefine retention compared to conventional technology.

XPS is the one of the most important characterization techniques for analysing oxygen vacancy, which was characterized by the difference in the atomic number ratio of metal ions to lattice oxygen. To measure relative oxygen vacancy of the materials, Scienta Omicron, Electron Spectroscopy for Chemical Analysis (ESCA+) XPS instrument is employed under ultrahigh vacuum (10-7 Pa) using monochromated Al Ka radiation (hm = 1486.6 eV) operated at 210 W. For a spinel alloyed with Ce-Zn, distinct peaks between 525 and 535?eV (depending on charge correction value) has been interpreted as oxygen vacancies.

EXAMPLES:

Having described the basic aspects of the present invention, the following non-limiting examples illustrate specific embodiments thereof. Those skilled in the art will appreciate that many modifications may be made in the invention without changing the essence of invention.

Example -1 (Comparative example)
Copper aluminate spinel was synthesized by co-precipitation method using copper (II) nitrate hexahydrate as source of copper and sodium aluminate as source of aluminium. Sodium hydroxide is used as hydrolyzing agent. 241.6 g of copper (II) nitrate hexahydrate, 630 g of aluminium sulphate hexadecahydrate and 5000 g of DM water were mixed uniformly (Solution - A). In another beaker, 320 g of sodium hydroxide and 2000 g of DM water were stirred thoroughly to obtain clear solution of B. The solution – B and solution – A were simultaneously mixed at constant flow rate by employing peristaltic pump at half an hour of addition time. During the simultaneous addition, pH of the slurry was monitored by using Metrohm digital pH meter. Final pH of the slurry was 11 and reaction temperature is 40°C. After the precipitation was completed, the stirring was continued for 1 h to obtain uniform mixing and to complete the hydrolysis. After 1 h, entire slurry was filtered out and washed repeatedly with hot water to obtain the material without sodium ion as impurities. The material was dried at 120°C for overnight, and calcined at 850°C and 1000°C for 2 h. The synthesized material is designated as copper aluminate CuAl2O4. The XRD pattern of the sample calcined at 850°C shows mixed CuO and CuAl2O4 (43%) and the sample calcined at 1000°C shows 95% CuAl2O4 spinel. Catalyst additive was prepared by mixed copper alumina spinel, alumina and clay after milling. The additive composition was spinel (10-30%): Alumina (20-40%): Clay (40-60%). The final catalyst additive was as comparative example -1 (Prior art).

Example-2: (Present invention)
7.3 g of zinc nitrate hexahydrate, 12.6 g of cerium nitrate hexahydrate, 130.6 g of copper nitrate trihydrate and 326 g of Aluminum sulphate octadecahydrate was weighed in a 5000 ml beaker and dissolved in 1000 g of distilled water (Solution-A). In another beaker, 340 g of sodium hydroxide flakes was added into 900 g of distilled water (Solution-B). In 5 L autoclave, 100 g of distilled water was added and heated to 80°C and solution A and B were added simultaneously under stirring at constant pH of 9-10.5. After the complete addition of solution, A & B, the autoclave was stirred for 1 h at 80°C. Bluish green precipitate was filtered and washed with hot distilled water of above 80°C for 4-5 times to reduce impurities. After washing, the received material of about 1000 g was kept at oven for drying for 10 h at 120°C. The dried product/material was calcined at 700°C for 5 h.

Example-3:
7.3 g of zinc nitrate hexahydrate, 25 g of cerium nitrate hexahydrate, 115 g of copper nitrate trihydrate and 326 g of Aluminum sulphate octadecahydrate was weighed in a 5000 ml beaker and dissolved in 1000 g of distilled water (Solution-A). In another beaker, 340 g of sodium hydroxide flakes was added into 900 g of distilled water (Solution-B). In 5 L autoclave, 100 g of distilled water was added and heated to 80°C and solution A and B were added simultaneously under stirring at constant pH of 9-10.5. After the complete addition of solution, A & B, the autoclave was stirred for 1 h at 80°C. Bluish green precipitate was filtered and washed with hot distilled water of above 80°C for 4-5 times to reduce impurities. After washing, the received material of about 1000 g was kept at oven for drying for 10 h at 120°C. The dried product was calcined at 700°C for 5 h.

Example-4:
7.3 g of zinc nitrate hexahydrate, 38 g of cerium nitrate hexahydrate, 100 g of copper nitrate trihydrate and 326 g of Aluminum sulphate octadecahydrate was weighed in a 5000 ml beaker and dissolved in 1000 g of distilled water (Solution-A). In another beaker, 340 g of sodium hydroxide flakes was added into 900 g of distilled water (Solution-B). In 5 L autoclave, 100 g of distilled water was added and heated to 80°C and solution A and B were added simultaneously under stirring at constant pH of 9-10.5. After the complete addition of solution, A & B, the autoclave was stirred for 1 h at 80°C. Bluish green precipitate was filtered and washed with hot distilled water of above 80°C for 4-5 times to reduce impurities. After washing, the received material of about 1000 g was kept at oven for drying for 10 h at 120°C. The dried product was calcined at 700°C for 5 h.

Example-5:
14.6 g of zinc nitrate hexahydrate, 12.6 g of cerium nitrate hexahydrate, 124.5 g of copper nitrate trihydrate and 666 g of Aluminum sulphate octadecahydrate was weighed in a 5000 ml beaker and dissolved in 1000 g of distilled water (Solution-A). In another beaker, 340 g of sodium hydroxide flakes was added into 900 g of distilled water (Solution-B). In 5 L autoclave, 100 g of distilled water was added and heated to 80°C and solution A and B were added simultaneously under stirring at constant pH of 9-10.5. After the complete addition of solution, A & B, the autoclave was stirred for 1 h at 80°C. Bluish green precipitate was filtered and washed with hot distilled water of above 80°C for 4-5 times to reduce impurities. After washing, the received material of about 1000 g was kept at oven for drying for 10 h at 120°C. The dried product was calcined at 700°C for 5 h.

Example-6:
Preparation of catalyst additive composition / gasoline sulfur reduction additive:
315 g calcined materials from example 2, 527 g of Kaolin clay, 300 g of High density pseudoboehmite alumina, 365 g of aluminium nitrate nonahydrate was mixed with 1700 g of DM water. The slurry was transferred to a 3D ball mill and milled for 5 h to reduce the particle size of less than 1 micron. The final slurry was sieved, and spray dried at inlet temperature of 450°C and outlet temperature of 210°C in a co-current spray drier unit. The microsphere after spray drying was kept calcination at 600°C for 4 h to obtain final catalyst additive composition/ gasoline sulfur reduction additive.

Example-7-10:
315 g of calcined material from example 1, 3, 4, 5 used similar to example -6 for prepared gasoline sulfur reduction additive/catalyst additive composition.

Table 2 shows catalyst additive compositions and its physico-chemical properties such as the composition has apparent bulk density (ABD) in a range of 1.05 to 1.12g/cc, attrition index (AI) in a range of 2.2 to 3.1 % (ASTM D5757), surface area (SA) in a range of 129-148 m2/g, pore volume (PV) in a range of 0.40-0.42 m3/g, and relative oxygen vacancy (figure 1) in a range of 48% to 77%.

Table 2
Properties Example-6 Example-7
Comparative Example-8 Example-9 Example-10
ABD, g/cc 1.1 0.87 1.09 1.12 1.05
AI, % (ASTM D5757) 2.2 18 2.8 3.1 2.7
SA, m2/g 148 98 133 138 129
PV, m3/g 0.42 0.33 0.40 0.41 0.40
Relative oxygen vacancy, % 48% 20% 59% 77% 52%
Chemical composition
SiO2 24.75 25.02 24.8 24.52 24.68
Al2O3 60.25 59.98 60.2 60.48 60.32
CuO 12.9 15 11.4 9.9 12.3
CeO2 1.5 0 3 4.5 1.5
ZnO 0.6 0 0.6 0.6 1.2

Figure 1 represents the increases in the oxygen vacancy in the catalyst additive composition, increasing trend in the sulfur removing capacity of the catalyst. The present invention explains clearly about understanding of the oxygen vacancies which can enhance electron transport and regulate the surface chemical properties of catalysts. The correlation of oxygen vacancy in the alloyed metal oxides was never discussed with reduction of sulfur in gasoline.

Example 11:
Fluid catalytic cracking (FCC) experiments with base catalyst (FCC catalyst), base catalyst along with catalyst additive composition, and base catalyst along with reference catalyst have been conducted with feedstock at FCC condition. The properties and characterization of feedstock is given in Table 3. The FCC condition is given in Table 4. Experiments were conducted at three different Cat / Oil ratio with different catalyst load. The yields and sulfur reduction of base catalyst, base catalyst along with catalyst additive composition, and base catalyst along with reference catalyst were calculated at the constant cracking temperature, injection time, and feed rate. Figure 1 indicates increases in the oxygen vacancy in the catalyst increasing trend in the sulfur removing capacity of the catalyst.

Feedstock Characterization
The feed used in the present study is vacuum gas oil feed and its properties are listed in Table-3.

Table-3: Feed Properties
Sample FCC feed
Density at 15 °C, gm/cc 0.925
Sulfur, wt. % 2.05
CCR, wt. % 1.40
Distillation: ASTM-7169, wt. %
IBP 203.93
5 290.44
10 315.95
30 369.45
50 413.34
70 459.11
90 540.19
95 588.70

Table 4: FCC condition and Results

Base Base + Present invention from Example-9 BASE + Reference from the example 7
Cracking Temperature, °C 540 540 540 540 540 540 540 540 540
Injection Time, sec 30 30 30 30 30 30 30 30 30
Feed Rate, gm/min 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
Catalyst Load, gm 6 7.5 9 6 7.5 9 6 7.5 9
Recovery, wt.% 101.4 101.7 101.6 101.9 97.9 97.2 101.7 100.1 101.4
Catalyst-to-Oil, wt./wt. 4.84 6.05 7.25 4.84 6.05 7.25 4.84 6.05 7.25
Conversion, wt.% 67.25 70.82 73.93 68.12 71.36 74.23 67.17 71.36 73.38
Yields, wt.%:
Coke 4.2 5.1 6.0 4.7 5.5 5.9 5.2 6.4 7.3
Dry Gas 2.8 3.2 3.6 3.2 3.6 4.0 2.9 3.4 3.4
LPG 24.7 27.6 29.1 27.5 29.9 30.6 25.0 28.6 29.2
Naphtha 35.5 34.9 35.2 32.8 32.4 33.7 34.0 33.0 33.5
LCO 16.1 15.2 14.1 15.6 14.3 13.6 15.4 14.3 13.9
Bottoms 16.6 14.0 12.0 16.3 14.3 12.2 17.4 14.3 12.7
Ethylene 1.1 1.2 1.3 1.4 1.6 1.7 1.2 1.4 1.5
Propylene 9.5 10.3 10.7 10.6 11.4 11.8 9.9 11.0 11.1
C4 Olefins 8.8 9.5 9.7 9.7 10.2 10.1 9.0 9.9 9.8
Gasoline Sulfur, ppm 720 684 642 410 375 330 471 432 398
Gasoline Sulfur reduction, wt% - - - 43.1 45.2 48.6 34.6 36.8 38.0
, Claims:1. A catalyst additive composition for reducing sulfur in gasoline comprising:
(i) silica as SiO2 in a range of 10-50 wt. % with respect to the catalyst additive composition;
(ii) alumina as Al2O3 in a range of 40-80 wt. % with respect to the catalyst additive composition;
(iii) copper oxide as CuO in a range of 1-20 wt.% with respect to the catalyst additive composition;
(iv) cerium oxide as CeO2 in a range of 1-20 wt.% with respect to the catalyst additive composition; and
(v) zinc oxide as ZnO in a range of 0.1-5 wt.% with respect to the catalyst additive composition,
wherein the composition comprises Ce-Zn alloyed Cu with oxygen vacancy for sulfur removal.

2. The catalyst additive composition as claimed in claim 1, wherein the composition is developed by using mixed metal oxide system.

3. The catalyst additive composition as claimed in claim 1, wherein the composition has apparent bulk density (ABD) in a range of 1.05 to 1.12g/cc, attrition index (AI) in a range of 2.2 to 3.1 % (ASTM D5757), surface area (SA) in a range of 129 to 148 m2/g, pore volume (PV) in a range of 0.40 to 0.42 m3/g, and relative oxygen vacancy in a range of 48% to 77%.

4. A process for preparing a catalyst additive composition for reducing sulfur in gasoline comprising:
(a) dissolving a zinc precursor, a cerium precursor, a copper precursor and an aluminum precursor in water to obtain a solution A;
(b) adding sodium hydroxide in water to obtain a solution B;
(c) heating water and adding the solution A and solution B simultaneously under stirring at pH in a range of 9-10.5 to obtain a precipitate;
(d) washing, drying and calcining the precipitate to obtain a calcined material;
(e) mixing the calcined material, kaolin clay as silica source, pseudoboehmite alumina, aluminium nitrate nonahydrate in water to obtain a slurry;
(f) milling the slurry to reduce particle size and obtaining a final slurry; and
(g) sieving, spray drying and calcining the final slurry to obtain the catalyst additive composition.

5. The process as claimed in claim 4, wherein 0.1-5 wt.% of the zinc precursor, 1-20 wt.% of the cerium precursor, 1-20 wt.% of the copper precursor and 40-80 wt. % of the aluminum precursor are dissolved in water to obtain the solution A.

6. The process as claimed in claim 4, wherein:
(a) the zinc precursor is selected from the group comprising zinc nitrate hexahydrate, zinc sulphate monohydrate, zinc chloride hexahydrate, and zinc acetate dihydrate;
(b) the cerium precursor is selected from the group comprising cerium nitrate hexahydrate, Cerium(III) chloride heptahydrate, and Cerium triacetate ;
(c) the copper precursor is selected from the group comprising copper nitrate trihydrate, copper sulphate pentahydrate, and copper chloride dihydrate; and
(d) the aluminum precursor is selected from the group comprising aluminum sulphate octadecahydrate, aluminum nitrate nonahydrate, and aluminum chloride.

7. The process as claimed in claim 4, wherein in step (c) water is heated at a temperature in a range of 70 to 90°C; and after complete addition of the solution A and solution B, a reaction mixture is obtained and the reaction mixture is stirred for 1 to 3 h at 80°C to obtain the precipitate, wherein the precipitate is bluish green precipitate.

8. The process as claimed in claim 4, wherein in step (d) washing is carried out with distilled water at a temperature in a range of 70 to 90°C for 4-5 times to reduce impurities to obtain a washed material; drying of the washed material is carried out for 8 to 15 h at 100 to 150°C to obtain a dried material, calcining of the dried material is carried out at 600 to 900°C for 4 to 10 h.

9. The process as claimed in claim 4, wherein in step (g) the spray drying is carried out in a co-current spray drier unit at inlet temperature in a range of 300 to 500°C and outlet temperature in a range of 120 to 250°C; and after spray drying the calcination is carried out at a temperature in a range of 500 to 700°C for 2 to 5 h.

10. A method of reducing the concentration of sulfur in cracked gasoline in an FCC unit comprising contacting catalytic cracking feedstock oil with an effective amount of the catalyst additive composition as claimed in claim 1 along with a FCC catalyst at a temperature in a range of 510 to 580°C, injection time in a range of 2 to 75 sec, and feed rate in a range of 1 to 3 gm/min.

11. The method as claimed in claim 10, wherein Catalyst Load is in a range of 6 to 9 gm and Catalyst-to-Oil ratio in a range of 4.84 to 7.25 wt./wt.