Description:FIELD OF THE INVENTION
[0001] The present disclosure relates to an oil soluble asymmetric antimony complex of formula (I) having high antimony content and it requires low dosage while achieving effective passivation. The present disclosure also relates to method of preparation of an asymmetric antimony complex of formula (I) that can passivate contaminants nickel metal in hydrocarbon feedstocks. Present disclosure also relates to the development of testing method of said oil soluble metal complexes in plant/pilot plant to determine the nickel passivation efficacy.

BACKGROUND OF THE INVENTION
[0002] During the cracking reactions occurring in an FCC unit, metals present at the feed are deposited on the catalyst and, as a result, modify the overall catalytic performance. Although many metals have been detected, nickel, vanadium and iron are in general the most abundant. Nickel, being a dehydrogenation catalyst, leads to an increase of coke and hydrogen and a reduction in gasoline production. As a result, a loss in activity and gasoline selectivity occurs.
[0003] Numerous strategies to deal with the deleterious effect of nickel and vanadium have been developed. These include the addition of nickel passivation agents, hydrotreatment to remove metals from the resid FCC feed, and development of metal-resistant catalysts. Use of metal passivation has become an established practice and it has been found that compounds containing antimony are the most effective, followed in effectiveness by Ti, Bi, P and Zn.
[0004] The role played by these passivantsis to decrease the yield of hydrogen and coke, while increasing the yield of gasoline. Then, with the decreased load on the compressor, refineries are able either to process a poorer quality feed or increase throughput of the unit.
[0005] By using imaging secondary ion mass spectrometry (SIMS) it has been shown that whilst vanadium has a significant degree of mobility both within and between particles under normal FCC conditions, nickel tends to be immobilized once deposited. Although the values reported in the literature vary, nickel on the catalyst is about four times more active than vanadium or iron at equal concentration in terms of gases and coke formation. Its greatest effect is produced when combined with alumina or extra framework material present in modified zeolite.
[0006] It can be observed that nickel produces a decrease in bottoms conversion probably due to the poisoning of sites of mild acidity present on the matrix and on the external surface of the zeolite.
[0007] US4207204A discloses a hydrocarbon cracking catalyst which is treated with a crude antimony tris(O,O-dihydrocarbylphosphorodithioate) to passivate contaminating metals like Ni. The antimony compound is prepared by reacting antimony trioxide with O,O-dihydrocarbylphosphorodithioic acid. The cracking catalyst can be regenerated and the addition of antimony compound increased in the gasoline production and decrease in the hydrogen production.
[0008] US4321129A discloses a novel cracking catalyst for hydrocarbon cracking wherein the adverse effect of metals like nickel is mitigated by contacting the catalyst with a combination of antimony and tin compounds. The antimony compound used can be antimony tris(O,O-dipropyl phosphorodithioate). The cracking catalyst can be regenerated, and the addition of antimony compound resulted in an increase in the gasoline production and decrease in the hydrogen production and in an improved conversion of the feed.
[0009] US4111845A discloses a cracking catalyst for cracking of hydrocarbons. Antimony or its compounds are incorporated into the cracking catalyst. The catalyst can be regenerated and due to the addition of antimony compound the gasoline yield is increased with decrease in hydrogen yield.
[0010] Richard H. Nielsen et al in chapter-10 (Surface Science and Catalysis, 1993, 76, 339-384) discloses oil soluble antimony compounds as nickel passivators, preferably antimony trisdipropyldithio-phosphate. Antimony with sulphur and phosphorus groups led to the increased production of gasoline and decreased production of hydrogen rather than other antimony compounds without S and P groups.
[0011] Research focused on heavy oil cracking and contaminant metals on cracking catalyst led Phillips Petroleum Company in the late sixties to mid-seventies to the discovery of several metals’ passivation agents. Antimony containing compounds discovered by Johnson et al. [US 3,711,422] consistently were outstanding metals passivation agents. The first commercially used additive was an oil-soluble compound containing antimony, phosphorus, and sulfur in a hydrocarbon solvent developed by Phillips Petroleum Company called Phil-Ad@ CA. The active compound was antimony trisdipropyldithio-phosphate. The antimony content was typically 10.5 to 12.5 wt%; sulfur, 17.5 wt%, and phosphorus, 7.5 wt% minimum.
[0012] US4198317A discloses a method for passivating a nickel contaminated hydrocarbon cracking catalyst which comprises adding to said catalyst, an antimony tris(hydrocarbyl sulfonate). A catalytic composition comprising a hydrocarbon cracking catalyst and an antimony tris(hydrocarbonyl sulfonate) is also disclosed. The catalyst can be regenerated and due to the addition of antimony compound the gasoline yield is increased with decrease in hydrogen yield. Various nickel passicators and their application is given in Table 1 below:
Table 1: Various nickel passivators and their application if hydrocarbon cracking.
References Metal complex used Oil solubility Catalyst regeneration
Result
US4207204A
Antimony tris(O,O-dihydrocarbylphosphorodithioate; hydrocarbyl group can be alkyl, cycloalkyl or aryl) (includes the compound antimony tris(O,O- dipropylphosphorodithioate) Oil/ hydrocarbon soluble Cracking catalyst is regenerated High gasoline yield and Low level of H2
US4321129A
Several antimony compounds (Also includes Antimony tris(O,O-dipropyl phosphorodithioate) Dissolved or dispersed Cracking catalyst is regenerated
High yield of liquid fuels, Low level of H2 and conversion of feed is higher
US4111845A
Antimony tris(O,O-dihydrocarbyldithiophosphate).(Inluding antimony tris(O,O-dipropyldithiophosphate) Oil insoluble form of antimony compound preferred Cracking catalyst is regenerated High gasoline yield,
low level of H2 and better hydrocarbon conversion
US4207204A
Antimony tris(O,O-dihydrocarbylphosphorodithioate; hydrocarbyl group can be alkyl, cycloalkyl or aryl) (includes the compound antimony tris(O,O- dipropylphosphorodithioate) Oil/ hydrocarbon soluble Cracking catalyst is regenerated High gasoline yield and Low level of H2
US4321129A
Several antimony compounds (Also includes Antimony tris(O,O-dipropyl phosphorodithioate) Dissolved or dispersed Cracking catalyst is regenerated
High yield of liquid fuels, Low level of H2 and conversion of feed is higher

[0013] As per abovementioned literature study, it is understood that most of the antimony complexes/compounds that are employed for nickel passivation are symmetric complex. Disclosures are mainly based on single anchoring ligands which are tri-coordinated with antimony metal to form complexes to make it oil/ hydrocarbon soluble nickel passivators. Symmetric ligand complex is less labile than asymmetric and may exhibits less passivation effect while in exposure to nickel or other targeted metal. Moreover, symmetric antimony complexes disclose in various patents comprises less antimony content and thus needs high dosing amount to achieve similar passivation effect. Accordingly, in this study asymmetric antimony complexes syntheses were undertaken having high antimony content. Moreover, asymmetric ligands may be more labile for ligand exchange due to different electronic environment compared to symmetrically coordinated ligands.

OBJECTS OF THE INVENTION
[0014] The main objective of the present invention is to provide an asymmetric antimony complex of formula (I).
[0015] Another objective of the present invention is to provide a method of preparation of an asymmetric antimony complex of formula (I) that can passivate nickel contaminants resid FCC feedstocks/Vacuum gas oil (VGO) feed.
[0016] Another objective of the present invention is to provide an oil/hydrocarbon soluble asymmetric antimony complex so that dosing of passivator become easier while running plant.
[0017] Yet another objective of the present invention is to provide a testing method involved real-time cracking of feedstock consisting of high concentration of nickel contaminants and the passivator followed by catalyst regeneration.

SUMMARY OF THE INVENTION
[0018] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in Detailed Description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
[0019] The present disclosure discloses an asymmetric antimony complex of formula (I) comprising:

(I)
wherein R is the alkyl chain consisting of carbon number 2 to 10 or phenoxy or substituted phenoxy group.
[0020] The present disclosure also discloses a method of preparation of an asymmetric antimony complex of formula (I) comprising:
a) taking an antimony salt solution;
b) taking a solution of ethane-1,2-dithiol;
c) taking a solution of chelating ligand;
d) mixing the antimony salt solution with the solution of ethane-1,2-dithiol to obtain a first reaction mixture; and
e) mixing the solution of chelating ligand with the first reaction mixture such that the antimony salt, ethane-1,2-dithiol and chelating ligand are in a ratio in the range of 1:1-2:1-2 to obtain the asymmetric antimony complex of formula (I):

(I)
wherein R is the alkyl chain consisting of carbon number 2 to 10 or phenoxy or substituted phenoxy group.
[0021] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.

DETAILED DESCRIPTION OF THE INVENTION
[0022] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0023] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0024] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
[0025] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.
[0026] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it is individually recited herein.
[0027] All processes described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0028] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0029] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0030] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0031] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description that follows, and the embodiments described herein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present disclosure. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.
[0032] It should also be appreciated that the present invention can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.
[0033] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0034] An embodiment of the present disclosure discloses an asymmetric antimony complex of formula (I) comprising:

(I)
wherein R is the alkyl chain consisting of carbon number 2 to 10 or phenoxy or substituted phenoxy group.
[0035] Another embodiment of the present disclosure discloses the compound complex having the formula (I) is
.
[0036] Yet another embodiment of the present disclosure discloses method of preparation of an asymmetric antimony complex of formula (I) comprising:
a) taking an antimony salt solution;
b) taking a solution of ethane-1,2-dithiol;
c) taking a solution of chelating ligand;
d) mixing the antimony salt solution with the solution of ethane-1,2-dithiol to obtain a first reaction mixture; and
e) mixing the solution of chelating ligand with the first reaction mixture such that the antimony salt, ethane-1,2-dithiol and chelating ligand are in a ratio in the range of 1:1-2:1-2 to obtain the asymmetric antimony complex of formula (I):

(I)
wherein R is the alkyl chain consisting of carbon number 2 to 10 or phenoxy or substituted phenoxy group.
[0037] Another embodiment of the present disclosure discloses that the antimony salt is SbCl3.
[0038] Another embodiment of the present disclosure discloses that the solution is prepared in a solvent selected from toluene, xylene, chlorobenzene and benzene.
[0039] Another embodiment of the present disclosure discloses that the chelating ligand is selected from a group consisting of O,O-dihydrocarbylphosphorodithioate, O,O-di-alkyl phosphorodithioate and diaryldithiophosphate.
[0040] Another embodiment of the present disclosure discloses that the antimony salt solution is mixed with the solution of ethane-1,2-dithiol in step d) with constant stirring for period in the range of 1-3 hours.
[0041] Another embodiment of the present disclosure discloses that the solution of chelating ligand is mixed with the first reaction mixture in step e) with stirring for a period in the range of 3-5 hours.
[0042] Another embodiment of the present disclosure discloses that the steps d) and e) are performed at a temperature in the range of 25-40°C.
[0043] In another embodiment, the present invention relates to the method of synthesizing asymmetric antimony complex using combination of two chelating ligands whereas one chelating ligand is 1,2-ethaneduithiol and another chelating ligand is various substituents of O,O-dihydrocarbylphosphorodithioate. Such asymmetric antimony complex may be more susceptible for ligand exchange owing to asymmetric electronic environment compared to symmetrically coordinated complex.
[0044] Another embodiment of the present disclosure relates to a method for synthesizing asymmetric antimony complexes using two chelating ligands together whereas one chelating 1,2-ethanedithiol and another one is O,O-di-alkyl phosphorodithioate. Alkyl substituted phosphorodithioate exhibits better passivation effects than aromatic counter part as given in Table-1.
[0045] The present invention also provides synthesis method for asymmetric antimony complex having high antimony content >20wt% and most preferably >25wt% so that low antimony dosing is required to maintain suitable Ni/Sb ratio most preferably 10 while Ni-passivation. The method provides synthesis method asymmetric antimony complex having minimum molecular weight so that antimony weight percent become higher in prepared complex. The commercial antimony complex named Phil-Ad@ CA contents 10.5-12.5 wt% of antimony. More the active antimony component in a complex less dosage is required for effective passivation while maintaining suitable Ni/Sb ratio 10 or more than 10.
[0046] The present invention relates to provide method for the synthesis of asymmetric antimony complexes low in molecular weight, yet they are highly soluble in hydrocarbon feed. Thus, dosage can be done in the feed zone rather than the catalyst zone to minimize catalyst equilibrium time and achieve immediate or real time passivation effect. The benefit of oil soluble nickel passivator over modified catalyst based passivators hereafter referred to as metal traps, is that the passivation effect is apparent sooner in case of oil soluble passivators. Heterogenous metal traps are added into the catalyst inventory in amounts corresponding to the then perceived organometallic contaminant concentration in the feed. It takes a fixed time for the metal trap concentration to equilibrate in the catalyst inventory. This equilibration time is dependent on the cracker design. Hence there is always a fixed delay between any changes in the contaminant metal concentration and the metal trap nickel passivation. However, in case oil soluble passivator, the addition rate can easily be manipulated with respect to the incoming feed contaminant level. The passivation effect can be observed in the same shift when the passivator addition is started. Hence the operator’s response to feed quality fluctuations is dynamic. With the increasing total metal content in cracking catalyst, spent catalyst disposal becomes complicated.
[0047] The present invention also relates to provide testing method involved real-time cracking of feedstock which was adulterated with high nickel concentration of 2000 ppm followed by suitable dosage of passivator -antimony complex to make Ni/Sb ratio 10 and then catalyst regeneration was performed till 50 cycles run (Table 2).
Table-2 : Cyclic deactivation of FCC catalyst
Oil Vacuum Gas oil
Metal Salt name Ni(II) 2,4 pentanedionate
No of cycles 5 10 15 20 25 30 35 40 45 50
Metal salt conc in oil (ppm) 173.21 173.21 173.21 173.21 173.21 173.21 173.21 173.21 173.21 173.21
Cumulative Oil injected/cycle (g) 10 20 30 40 50 60 70 80 90 100
Catalyst Surface area 238 216 214 212 211 190 188 185 182 175
Ni (ppm) on catalyst 388.4 426.1 676.4 799.35 900.12 1050.01 1394.3 1584.3 1939.2 2150
Sb (ppm) on catalyst 215

[0048] The present invention relates provide synthesis of antimony complex and also its application and or testing method in plant/or pilot plant to achieve liquid yield by improvement of 2.5 wt% and reduction in gas formation by 2.4 wt% for vacuum gas oil feed / resid FCC feed conversion improvement of 2 wt% after 50 cycles run for each case (Table 2).
[0049] The following examples are provided to illustrate the invention and are not to be construed as limiting thereof.
[0050] While the foregoing describes various embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
[0051] While the foregoing describes various embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
EXAMPLES
[0052] The present invention is further explained in the form of following examples. However, it is to be understood that the following examples are merely illustrative and are not to be taken as limitations upon the scope of the invention.
Example 1: Preparation of Synthesis of Sb-complex with diethyl dithiophophate and ethane dithiol (Sb wt% 30.50%)
[0053] A 100 ml toluene solution of SbCl3 (6.3 g/27.6 mmol) was added dropwise to toluene solution (100 ml) of ethane-1,2-dithiol (2.6 g/27.6 mmol) in a 1000 ml round-bottom flask with constant stirring for two hours followed by addition of toluene suspension (300 ml) of (diethyl dithiophosphateammonium salt (5.63 g/ 27.7 mmol). The reaction contents were further stirred for four hours till the colour of changed from white to yellow indicating the completion of reaction. The yellow solution showed white turbidity due to precipitation of ammonium chloride and confirmed the formation of the desired complex. The precipitated ammonium chloride was filtered off. The excess solvent was removed from the filtrate under reduced pressure and the product was dried finally in vacuo when the compound was isolated as yellow sticky solid in 90% yield. This compound was labelled as BNipass-1.
[0054] Exact mass of C6H14O2PS4Sb: 399.13 Found 400.12 in ESI positive mode of LC-MS;IR (KBr): ? = 1150, s [?(P)-O-C], 967, 673, s [?P-S], 615, m [?P-S], 445, w [?Sb-S], 2926, w [?C-H] cm-1; 600 MHz 1H NMR (DMSO-d6, ppm): = 1.28 (t, 6H, 2-CH3), 3.05 (t, J = 8 Hz, 4H, CH2) 4.12 (q, J= 7 Hz, 4H, CH2); 150 Hz 13C NMR (DMSO-d6, ppm): 16.21 (2-CH3), 36.23 (2-CH2-S-), 63.73 (2-CH2-O-); 31P NMR (DMSO-d6, ppm): 93.62 (s).
Example 2: Synthesis of Sb-complex with and diaryldithiophosphate (Sb wt% 22.08 %)
[0055] Synthesis was performed as mentioned in Example 1 except the different quantity of diaryldithiophosphate was taken as per molecular weight. The compound was isolated as yellow sticky solid in 85% yield. This compound was labelled as BNipass-2.
[0056] Exact mass of C18H22O2PS4Sb: 551.32 Found 552.24 in ESI positive mode of LC-MS; IR (KBr):?? = 1147, s [? (P)-O-C], 967, s [?P-O-(C)], 635, s [?P-S], 615, m [?P-S], 430, w [?Sb-S], 2939, w [?C-H] cm-1; 600 MHz 1H NMR (DMSO-d6 ppm): 1.99 (s, 12H, 3,5-(CH3)2), 6.55 (s, 4H, H2), 6.78 (s, 2H, H4) 3.10 (t, J = 7 Hz, 4H, CH2); 150 MHz 13C NMR (DMSO-d6, ppm): 22.12 (3,5-(CH3)2), 123.56 (C2,6), 129.64 (C4), 146.33 (C3,5-CH3), 155.53 (C1–O) 36.23 (CH2); 31P NMR (DMSO-d6, ppm): 94.6(s)
[0057] Paasication effect of commercial passivator and BNipass-1 and BNipass-2 of the present invention is given in Table 3.
Table 3: Passivation effect of various passivators determined while VGO cracking experiments at 550 oC.
Without passivator Commercial passivator BNipass -1 added by maintaining Ni/Sb ration 10 BNipass -2 added by maintaining Ni/Sb ration 10
Coke 2.38 2.31 2.13 2.43
DG 4.35 2.88 1.63 1.79
LPG 29.77 31.12 30.62 31.79
Total GAS 34.12 34.00 32.25 33.58
Conversion of VGO 75.89 76.00 80.08 77.51

[0058] A skilled artisan will appreciate that the quantity and type of each ingredient can be used in different combinations or singly. All such variations and combinations would be falling within the scope of present disclosure.
[0059] The foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.
, Claims:1. An asymmetric antimony complex of formula (I) comprising:

(I)
wherein R is the alkyl chain consisting of carbon number 2 to 10 or phenoxy or substituted phenoxy group.
2. The complex as claimed in claim 1, wherein the complex having the formula (I) is
.
3. A method of preparation of an asymmetric antimony complex of formula (I) comprising:
a) taking an antimony salt solution;
b) taking a solution of ethane-1,2-dithiol;
c) taking a solution of chelating ligand;
d) mixing the antimony salt solution with the solution of ethane-1,2-dithiol to obtain a first reaction mixture; and
e) mixing the solution of chelating ligand with the first reaction mixture such that the antimony salt, ethane-1,2-dithiol and chelating ligand are in a ratio in the range of 1:1-2:1-2 to obtain the asymmetric antimony complex of formula (I):

(I)
wherein R is the alkyl chain consisting of carbon number 2 to 10 or phenoxy or substituted phenoxy group,
4. The method as claimed in claim 3, wherein the antimony salt is SbCl3.
5. The method as claimed in claim 3, wherein the solution is prepared in a solvent selected from toluene, xylene, chlorobenzene and benzene.
6. The method as claimed in claim 3, wherein the chelating ligand is selected from O,O-dihydrocarbylphosphorodithioate, O,O-di-alkyl phosphorodithioate and diaryldithiophosphate.
7. The method as claimed in claim 3, wherein the antimony salt solution is mixed with the solution of ethane-1,2-dithiol in step d) with constant stirring for period in the range of 1-3 hours.
8. The method as claimed in claim 3, wherein the solution of chelating ligand is mixed with the first reaction mixture in step e) with stirring for a period in the range of 3-5 hours.
9. The method as claimed in claim 3, wherein steps d) and e) are performed at a temperature in the range of 25-40°C.