CLIAMS:1. An improved multi-metallic catalyst system comprising:
i. at least one support; and
ii. at least one promoter component, and an active component comprising at least two active metals uniformly dispersed on said support.
2. The improved multi-metallic catalyst system as claimed in claim 1, wherein said promoter component comprises at least one metal selected from the group consisting of Group IIA metals, Group IIIA metals, Group VA metals, Group VB metals and Group VIIB metals.
3. The improved multi-metallic catalyst system as claimed in claim 1, wherein said active metal is at least one selected from the group consisting of Group VIB metals, Group VIIB metals, Group VIII metals and noble metals.
4. The improved multi-metallic catalyst system as claimed in claim 1, wherein said support is selected from the group consisting of alumina, silica, zirconia, alumina-silica, zeolite and molecular sieves.
5. A process for the preparation of an improved multi-metallic catalyst system; said process comprising the following steps:
i. procuring at least one support;
ii. impregnating said support with at least one promoter in the presence of at least one stabilizing agent, followed by filtering, drying and calcining to obtain a promoter impregnated support; and
iii. charging said promoter impregnated support with at least two active metal salts in the presence of said stabilizing agent, followed by filtering, drying, calcining and reducing to obtain the improved multi-metallic catalyst system.
6. The process as claimed in claim 5, further includes the step of sulfiding the catalyst system using at least one sulfiding agent selected from the group consisting of dimethyl disulfide and dimethyl sulfoxide.
7. The process as claimed in claim 5, wherein said stabilizing agent is at least one selected from the group consisting of hexamethyleneimine, ammonia solution, piperidine, pyrrolidine, morpholine, piperazine hydrate, 2-methylcyclohexyl amine and cyclohexylamine. ,TagSPECI:FIELD
The present disclosure relates to an improved multi-metallic catalysts and a process for their preparation.
BACKGROUND
The concept of catalysts, that came into existence due to the pioneering work of Berzelius around a hundred and forty years ago, has seen a transformational change. Simple catalysts, composite catalysts, homogenous catalysts, heterogeneous catalysts, unsupported and supported catalysts are different classes of catalysts that have been invented, developed and used for multifarious applications.
Beginning with applications such as isolation of useful byproducts from petrochemical crudes and preparation of polymers; use of catalysts has been translated far too deep and wide into the modern chemical industry where catalysts are being used in almost every process including production of fine chemicals for pharmaceutical applications and production of bulk chemicals.
Single metal catalysts have been surpassed today by more advanced versions such as bimetallic catalysts and even multi-metallic catalysts. The present disclosure envisages a multi-metallic catalyst that has numerous applications in the fields of petrochemicals, polymers, metallurgy and the like and a process for its preparation.

SUMMARY
The present disclosure envisages an improved multi-metallic catalyst system comprising at least one support, and at least one promoter component and an active component comprising at least two active metals uniformly dispersed on the support. The present disclosure further provides a process for the preparation of the afore-stated catalyst system which includes procuring at least one support, impregnating said support with at least one promoter in the presence of at least one stabilizing agent, followed by filtering, drying and calcining to obtain a promoter impregnated support and charging said promoter impregnated support with at least two active metal salts in the presence of the stabilizing agent, followed by filtering, drying, calcining and reducing to obtain the catalyst system.

DETAILED DESCRIPTION
The disclosure will now be described with reference to the accompanying embodiments, which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein, the various features, and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
In accordance with one aspect, the present disclosure provides an improved multi-metallic catalyst system that includes, but is not limited to, the components: at least one support, at least one promoter component and an active component comprising at least two active metals being uniformly dispersed on the support. The afore-stated components in the catalyst system are present in pre-determined quantities and proportions with respect to each other.
The support of the present disclosure is selected from the group that includes, but is not limited to, alumina, silica, zirconia, alumina-silica, zeolite and molecular sieves. In one embodiment, the support of the present disclosure is a carrier. Further, the support is in at least one form selected from the group that includes, but is not limited to, extrudates, spheres, granules and pellets.
The promoter component of the present disclosure is at least one metal selected from the group that includes, but is not limited to, Group IIA metals, Group IIIA metals, Group VA metals, Group VB metals and Group VIIB metals. The promoter component typically performs the function of enhancing the overall activity of the catalyst.
The active component includes, but is not limited to, at least two active metals. The active metal of the present disclosure includes, but is not limited to, Group VIB metals, Group VIIB metals, Group VIII metals and noble metals.
In one embodiment, the improved multi-metallic catalyst system is in reduced form. In another embodiment, the improved multi-metallic catalyst system is in sulfided form.
In one exemplary embodiment, the improved multi-metallic catalyst system of the present disclosure consists of niobium as a part of the promoter component, cobalt and molybdenum as a part of the active component on an alumina support. In another exemplary embodiment, the improved multi-metallic catalyst system of the present disclosure consists of phosphorus as a part of the promoter component, cobalt and molybdenum as a part of the active component on an alumina support. The improved multi-metallic catalyst could be present in a sulfided form in such an embodiment. In a yet another exemplary embodiment, the improved multi-metallic catalyst system of the present disclosure consists of boron as a part of the promoter component, cobalt and molybdenum as a part of the active component on an alumina support.
In accordance with another aspect, the present disclosure provides a process for the preparation of the afore-stated catalyst system. The process includes, but is not limited to, the steps presented herein below.
Initially, at least one support suitable for preparing an improved multi-metallic catalytic system is procured. In one embodiment, the support is in an amorphous state prior to further processing. Typically, the support used in the present process is selected from the group that includes, but is not limited to, alumina, silica, zirconia, alumina-silica, zeolite and molecular sieves.
The support is then impregnated, in a pre-determined quantity, with at least one promoter that is selected from the group that includes, but is not limited to, Group IIA metals, Group IIIA metals, Group VA metals, Group VB metals and Group VIIB metals. In one embodiment, the step of impregnating is carried out by the equilibrium method. In this method, a solution of any of the afore-stated metals is prepared by dissolving the metal in water or in an organic solvent. The support is then added into the solution and allowed to stand until the system reaches equilibrium. This particular process is carried out in the presence of at least one stabilizing agent, a pre-determined temperature and at a predetermined pressure range. The stabilizing agent, which in one embodiment, is also a solubilizing agent, is selected from the group that includes, but is not limited to, hexamethyleneimine, ammonia solution, piperidine, pyrrolidine, morpholine, piperazine hydrate, 2-methylcyclohexyl amine and cyclohexylamine. In one embodiment, the pre-determined temperature ranges from 40-60 oC and the pre-determined pressure is atmospheric pressure.
The step of impregnation is followed by filtration and then by drying, the latter step being carried out at a pre-determined temperature for a pre-determined time period. In one embodiment, the pre-determined temperature is 120 oC and the pre-determined time period ranges from 6 to 10 hours. After drying the catalyst is calcined at a pre-determined temperature for a pre-determined time period to obtain a promoter impregnated support. In one embodiment, the pre-determined temperature is 600 oC and the pre-determined time period is 6 hours. In another embodiment, the step of calcining is carried out in the presence of air.
Into the promoter impregnated support, at least two active metal salts are charged or impregnated, in pre-determined quantities, in the presence of at least one stabilizing agent. The active metal salt of the present disclosure comprises a cation that includes, but is not limited to, Group VIB metals, Group VIIB metals, Group VIII metals and noble metals and an anion that includes, but is not limited to, chloride, bromide, fluoride, iodide, sulfate, phosphate, phosphonate, nitrate, nitrite, carbonate, acetate, bicarbonate, hydroxide and oxide. The stabilizing agent used in the present step of charging may be the same or different as that used in the earlier step. The step of charging or impregnation, in one embodiment, is carried out by the equilibrium method. The resulting active metal loaded catalyst is further filtered, dried, calcined and optionally reduced as in the previous steps to obtain the improved multi-metallic catalyst system of the present disclosure.
The improved multi-metallic catalyst system thus obtained is used either in a reduced form or a sulfided form using at least one sulfiding agent selected from the group that includes, but is not limited to, dimethyl disulfide and dimethyl sulfoxide.
The improved multi-metallic catalyst system, described herein above, has applications in multifarious fields such as petrochemicals, polymers, metallurgy and the like; making the subject matter of the present disclosure highly industrially applicable. Furthermore, the spent catalyst system of the present disclosure is capable of being regenerated; thereby increasing the economy of the process in which it is used. The improved multi-metallic catalyst system may be regenerated by at least one process selected from the group that includes, but is not limited to, filtration, washing, calcination and reduction. In one embodiment, the multi-metallic catalyst system can be recycled and reused at least 5 times without any loss in its catalytic activity. Still further, the improved multi-metallic catalyst system of the present disclosure is a highly stable system which can be used both in the presence and in the absence of a solvent.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

TECHNICAL ADVANCEMENTS AND ECONOMIC SIGNIFICANCE
The improved multi-metallic catalyst system of the present disclosure described herein above has several technical advantages including but not limited to the realization of:
? The improved multi-metallic catalyst system is capable of being recycled and regenerated.
? The reusability of the improved multi-metallic catalyst system makes its use economical.
? The improved multi-metallic catalyst system has a wide spectrum of industrial applicability.
? The improved multi-metallic catalyst system is a highly stable system which can be used both in the presence and in the absence of a solvent.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.