Description:FIELD OF THE INVENTION
The present invention relates to a process for preparation of a bi-metallic hydrogenating catalyst. More specifically, the present invention relates to a process for preparation of a bi-metallic nickel-ruthenium based hydrogenating catalyst, a bi-metallic nickel-ruthenium based hydrogenating catalyst, and uses thereof in the preparation of de-aromatized hydrocarbon solvents having aromatic content less than 100 ppm through selective hydrogenation of distillates having boiling point in range of 150° C to 350° C.
BACKGROUND OF THE INVENTION
Dearomatized hydrocarbon solvents commonly known as D-solvents or D-series, are considered an ideal replacement for traditional hydrocarbon solvents such as mineral or white spirits, kerosene etc. With its low to extremely low aromatic content (less than 0.1%), dearomatized fluids still provide optimal solvency in many applications such as printing inks, paint, coatings, metal working fluids, industrial and institutional cleaning, adhesives, sealants, drilling fluids etc., and maintain good safety, health, and environmental standards.
The processes for obtaining de-aromatized hydrocarbon solvents involve conversion of the aromatic compounds present in hydrocarbon feed to the corresponding saturated hydrocarbons by reacting the aromatic compounds with hydrogen in the presence of a suitable catalyst under appropriate process conditions. Further, the hydrogenated petroleum distillates obtained from the hydrogenation reaction are usually stabilized by the removal of the light, volatile hydrocarbon components.
In order to produce high valued de-aromatized hydrocarbon solvents, selection of suitable hydrocarbon feedstock is important. Further, competitive and highly efficient processes for hydrogenation reaction of the hydrocarbon stream are critical to produce these high value products meeting the existing and future market demand.
Conventionally, de-aromatized solvents are prepared from expensive hydrocarbon feedstock and the processes used for this purpose require harsh hydrogenation reaction conditions.
The art continues to develop processes for reaction of niche hydrocarbon feedstock with hydrogen to produce de-aromatized hydrocarbon solvents in an efficient and cost-effective manner.
To have an efficient and economic process for preparation of de-aromatized solvent from less expensive hydrocarbon feedstock through selective hydrogenation, a hydrogenating catalyst which has high selectivity, high active metal reducibility, and having less severe process condition requirements along with efficient de-aromatization capabilities is highly desirable.
Most used hydrogenating catalyst in the hydrocarbon industry is a catalyst comprising nickel loaded on a refractory metal oxide support. It has been observed that reducibility of active metal in a hydrogenating catalyst is crucial for its catalytic activity and dependent on various factors including presence of auxiliary agents like promotors, their concentration, and their impregnation process or order in relation to nickel.
IN202047044783 provides a method for preparing a catalyst comprising a bimetallic nickel- and copper-based active phase and a support comprising a refractory oxide. It cites that the pre-impregnation (with respect to the impregnation of the nickel precursor) of a copper precursor on the support makes it possible to obtain better results in terms of reducibility of the nickel compared to a post-impregnation of the copper precursor (with respect to the impregnation of the nickel precursor), this being for identical catalyst reduction operating conditions (temperature, time, reducing gas).
FR3080300 provides a process for preparing a catalyst comprising a bimetallic active phase based on nickel and platinum or palladium. It cites that preferably, step b) is carried out before step a), that is to say that a first step of impregnation of the support with a platinum or palladium precursor is carried out, then a reaction is carried out. second step of impregnation of the support with a nickel precursor (pre-impregnation). The pre-impregnation (vis-à-vis the impregnation of the nickel precursor) of a platinum or palladium precursor on the support makes it possible to obtain better results in terms of nickel reducibility by relative to a post-impregnation of the platinum or palladium precursor (vis-à-vis the impregnation of the nickel precursor), and this for identical catalyst reduction operating conditions (temperature, time, reducing gas).
It is observed that it possible to greatly improve the reducibility of the active phase of nickel on the refractory metal oxide support and also, to drastically reduce the content of nickel in the hydrogenating catalyst by incorporating optimized amount of ruthenium and adopting a spray impregnation process wherein nickel is impregnated before ruthenium on the refractory metal oxide support.
OBJECTIVES OF THE PRESENT INVENTION
It is the primary objective of the present invention to provide a process for preparation of a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a refractory metal oxide support.
It is another objective of the present invention to provide a process for preparation of a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on an alumina support.
It is another objective of the present invention to provide a process for preparation of a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a phosphorous modified alumina support.
It is another objective of the present invention to provide a process for preparation of a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a refractory metal oxide support wherein high reducibility of active phase of nickel on the refractory metal oxide support can be achieved.
It is another objective of the present invention to provide a process for preparation of a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a refractory metal oxide support wherein catalytic activity of nickel is retained even if reduced amount of nickel is present in the catalyst.
The other objective of the present invention is to provide a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a refractory metal oxide support.
It is another objective of the present invention to provide a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a refractory metal oxide support wherein active phase of nickel on the refractory metal oxide support has high reducibility.
It is another objective of the present invention to provide a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a refractory metal oxide support wherein significant reduction in weight percent of nickel in the hydrogenating catalyst is achieved without compromising the hydrogenation capabilities of the catalyst.
The other objective of the present invention is to provide a process for preparing de-aromatized hydrocarbon solvents by subjecting distillates having boiling point in range of 150° C to 350° C in presence of a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a refractory metal oxide support.
It is another objective of the present invention is to provide a process for preparing de-aromatized hydrocarbon solvents having aromatic content less than 100 ppm by subjecting distillates having boiling point in range of 150° C to 350° C in presence of a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a refractory metal oxide support.
It is another objective of the present invention to provide a process for preparing de-aromatized hydrocarbon solvents having aromatic content less than 100 ppm from a heavy hydrocarbon feedstream by subjecting the said feedstream to distillation followed by catalytic hydrotreatment of distillate having boiling point in the range of 180° C to 550° C in presence of a hydrotreatment catalyst, isodewaxing, fractionation, and subjecting the fraction having boiling point in range of 150° C to 350° C having aromatic content in range of 5000 ppm to 40000 ppm to selective hydrogenation in presence of a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on a refractory metal oxide support.
SUMMARY OF THE INVENTION
The present invention discloses a process for preparation of a bi-metallic hydrogenating catalyst comprising nickel and ruthenium dispersed on an alumina support. The process involves preparation of an alumina support, loading of nickel and ruthenium on the said alumina support using a spray impregnation process, drying the said nickel and ruthenium sprayed alumina support, and calcining the dried nickel-ruthenium loaded alumina support to obtain the bi-metallic nickel-ruthenium based hydrogenating catalyst.

The alumina support is obtained by extruding alumina dough prepared by mixing alumina powder with an acid using a trilobite dye and drying the wet alumina extrudes for a duration of 5 to 15 hours at a temperature range of 60 to 120 ℃ followed by calcining at a temperature range of 450 to 550 ℃ for a duration of 2 to 10 hours.

The wet alumina extrudes is preferably dried for 10 to 12 hours at a temperature range of 80 to 100 ℃ and calcined at a temperature range of 450 to 550 ℃ for a duration of 2 to 10 hours.

The acid mixed in the alumina powder to prepare alumina dough is selected from phosphoric acid, nitric acid, and acetic acid. Further, the acid is nitric acid. The alumina powder is one or more selected from boehmite, pseudo boehmite, gibbsite, direct alumina, aluminum hydroxide, aluminum chlorides, aluminum sulfates, dawsonites and the alumina powder has surface area in range of 200 to 400 m2/gr. Further, the alumina powder is pseudo-boehmite, phosphorous modified alumina, and a combination thereof and has surface area in range of 250 to 330 m2/gr.

The alumina support thus obtained is then loaded with nickel and ruthenium by spray impregnation process wherein first precursor solution containing a salt of nickel dissolved in water is sprayed on the alumina support followed by spraying of second precursor solution containing a salt of ruthenium dissolved in water to obtain nickel and ruthenium sprayed alumina support.

The first precursor solutions of varying concentration are prepared by dissolving 0.2 mol % to 1.5 mol % of one or more nickel salt selected from nickel (II) nitrate hexahydrate and nickel (II) acetate tetrahydrate in water. Further, the first precursor solution is prepared by dissolving 0.4 mol % to 0.6 mol % of nickel (II) nitrate hexahydrate in water.

The second precursor solutions of varying concentration are prepared by dissolving 0.01 mol % to 0.1 mol % of one or more ruthenium salt selected from ruthenium chloride hydrate, ruthenium (III) nitrosyl nitrate in water. Further, the second precursor solution is prepared by dissolving 0.01 mol % to 0.05 mol % of ruthenium chloride in water.

The nickel and ruthenium sprayed alumina support thus obtained is dried to obtain dried nickel-ruthenium loaded alumina support. The drying step involves initial drying under vacuum at a temperature range of 50 to 100 ℃, followed by drying in an oven at a temperature range of 60 to 120 ℃, and then air drying at a temperature range of 450 to 550 ℃ for a duration of 4 to 12 hours. Further, the intermittent drying involves initial drying under vacuum at a temperature range of 60 to 80 ℃, followed by drying in an oven at a temperature range of 80 to 100 ℃, and then air drying at a temperature range of 450 to 520 ℃ for a duration of 8 to 12 hours.

The dried nickel-ruthenium loaded alumina support obtained at the end of spray impregnation process is subjected to calcination at a temperature range of 450 to 550 ℃ for a duration of 2 to 10 hours to obtain the bi-metallic hydrogenating catalyst. Further, the calcination is carried out at a temperature range of 480 to 520 ℃ for a duration of 4 to 8 hours to obtain bi-metallic hydrogenating catalyst.

The present invention further provides a bi-metallic hydrogenating catalyst comprising 5 to 50 weight % of nickel and 0.01 to 0.5 weight % of ruthenium dispersed on a refractory metal oxide support for producing de-aromatized hydrocarbon solvents through selective hydrogenation of heavy and middle hydrocarbon distillate having aromatic content in range of 5000 ppm to 40000 ppm, and sulfur content ranging from 0 ppm to 1 ppm. The bi-metallic nickel-ruthenium based catalyst has reducibility of nickel metal in the range of 80 % to 90 % at a reduction temperature in the range of 440 to 480 ℃. Further, the bi-metallic hydrogenating catalyst comprises 20 to 30 weight % of nickel and 0.05 to 0.2 weight % of ruthenium dispersed on a refractory metal oxide support.

The refractory metal oxide is one or more selected from the group consisting of alumina, silica, titania, and zirconia. The alumina support in the bi-metallic nickel-ruthenium based hydrogenating catalyst is alumina or modified alumina. The modified alumina is a phosphorous modified alumina.

The present invention further provides a process for preparing de-aromatized hydrocarbon solvents having aromatic content less than 100 ppm from a heavy hydrocarbon feedstream by subjecting the said feedstream to distillation followed by catalytic hydrotreatment of distillate having boiling point in the range of 180° C to 550° C and aromatic content in range of 5000 ppm to 40000 ppm in presence of a hydrotreatment catalyst, fractionation, and subjecting the fraction having boiling point in range of 150° C to 350° C to selective hydrogenation in presence of a bi-metallic nickel-ruthenium based hydrogenating catalyst comprising nickel metal dispersed on a refractory metal oxide support.

The fractioned hydrocarbon feedstream utilized in the process for preparation of de-aromatized solvents is a low-cost hydrocarbon feedstream having high aromatic content ranging from 5000 ppm to 20,000 ppm, and sulfur content ranging from 0 ppm to 1 ppm. Further, the aromatic content of the hydrocarbon feedstream is in range of 5000 ppm to 40000 ppm and sulfur content is in range of 0.5 ppm to 1 ppm. The feedstream comprises one or more selected from crude oil, heavy vacuum gas oil, and lube base oil.

The de-aromatized solvent preparation process starts with the distillation of heavy hydrocarbon feedstream to obtain a first distillate having boiling point in range of 180° C to 550° C. The first distillate is then subjected to hydrotreatment in presence of a hydrotreatment catalyst to obtain a hydrotreated hydrocarbon stream having sulfur content of less than 100 ppm, The hydrotreatment of the first distillate is carried out at a reactor temperature ranging from 300° C to 450 °C, reactor pressure ranging from 60 bar to 180 bar, weight hourly space velocity (WHSV) ranging from 0.5 h−1 to 3.0 h−1, and volume ratio of hydrogen to heavy hydrocarbon stream ranging from 100 Nm3/m3 to 1500 Nm3/m3. Further, the hydrotreatment of the first distillate is carried out at a reactor temperature ranging from 350° C to 400 °C, reactor pressure ranging from 100 bar to 150 bar, weight hourly space velocity (WHSV) ranging from 0.75 h−1 to 1.25 h−1, and volume ratio of hydrogen to heavy hydrocarbon stream ranging from 400 Nm3/m3 to 1000 Nm3/m3

The hydrotreated hydrocarbon stream having sulfur content less than 100 ppm is further subjected to isodewaxing which is mainly done to isomerize hydrocarbons and fractionation to obtain a second distillate having boiling point in the range of 150° C to 350° C.

The second distillate is further subjected to selective hydrogenation in presence of a bi-metallic nickel-ruthenium based catalyst to obtain de-aromatized solvents having aromatic content of de-aromatized solvent obtained is in a range of 5 ppm to 100 ppm and sulfur content in range of 0.5 to 1 ppm. In the most preferred embodiment, the aromatic content of de-aromatized solvents obtained is in a range of 20 ppm to 50 ppm.

The selective hydrogenation of the second distillate is carried out at a reactor temperature ranging from 80 °C to 200 °C, reactor pressure ranging from 25 bar to 35 bar, liquid hourly space velocity (LHSV) ranging from 0.25 h-1 to 2.0 h-1, and volume ratio of hydrogen to second distillate ranging from 40 Nm3/m3 to 100 Nm3/m3. Further, the selective hydrogenation of the second distillate is carried out at a reactor temperature ranging from 140 °C to 180 °C, reactor pressure ranging from 10 bar to 45 bar, liquid hourly space velocity (LHSV) ranging from 0.5 h-1 to 1.0 h-1, and volume ratio of hydrogen to second distillate ranging from 50 Nm3/m3 to 70 Nm3/m3.

The reactor pressure and volume ratio of hydrogen to second distillate is advantageously low in comparison to other processes for the preparation of de-aromatized solvents from heavy hydrocarbon feedstream.

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 element 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 process for preparation of a bi-metallic nickel-ruthenium based hydrogenating catalyst disclosed herein involves preparation of a refractory metal oxide support, loading of nickel and ruthenium on the said refractory metal oxide support using spray impregnation process, drying the said nickel and ruthenium sprayed refractory metal oxide support and calcining the dried nickel-ruthenium loaded refractory metal oxide support to obtain the bi-metallic nickel-ruthenium based hydrogenating catalyst.

The refractory metal oxide support used in the process is selected from alumina, silica, titania, and zirconia. In preferred embodiments, the refractory metal oxide support is selected from alumina support, modified alumina support and combination thereof. In most preferred embodiments, the modified alumina support is a phosphorus modified alumina support.

The preparation of refractory metal oxide support in the process disclosed herein involves extrusion of refractory metal oxide powder using a dye, drying the refractory metal oxide extrudes, and calcination of dried refractory metal oxide extrudes to obtain the refractory metal oxide support.

In one of the preferred embodiments, the refractory metal oxide support is an alumina support prepared by extruding alumina dough using a dye of 2 mm X 3 mm Trilobite shape. The wet extruded alumina is then dried and calcined to obtain the alumina support. In another preferred embodiment wherein alumina support is phosphorous modified, the calcined alumina support thus obtained is sprayed with a solution of phosphoric acid to obtain phosphorous modified alumina support.

The alumina dough used for preparing the alumina support or modified alumina support is prepared by mixing commercially available alumina powder with an acid selected from nitric acid, acetic acid, and phosphoric acid. In the most preferred embodiments, acid is nitric acid. The alumina powder is selected from boehmite, pseudo boehmite, gibbsite, direct alumina, aluminum hydroxide, aluminum chlorides, aluminum sulfates, and dawsonites. In the most preferred embodiments, alumina powder is boehmite or pseudo boehmite. The surface area of alumina powder used for preparing the alumina dough is in the range of 200 to 400 m2/gr. In the most preferred embodiment, the surface area of alumina powder is in the range of 250 to 330 m2/gr.

The process disclosed herein involves drying of wet alumina extrudes during the preparation of alumina support to obtain dried alumina extrudes. The wet alumina extrudes is dried for 5 to 15 hours at a temperature range of 60 to 120 ℃. In most preferred embodiments, the wet alumina extrudes is dried for 10 to 12 hours at a temperature range of 80 to 100 ℃.

The dried alumina extrudes is then calcined to obtain the alumina support ready for loading of nickel and ruthenium. The calcination of dried alumina extrudes is carried out at a temperature range of 450 to 550 ℃ for a duration of 2 to 10 hours to obtain calcined alumina support. In most preferred embodiments, the dried alumina extrudes are calcined at a temperature range of 480-520 ℃ for a duration of 4 to 8 hours. The calcination is preferably performed in an open-air furnace.

The alumina support obtained after calcination is ready for loading of nickel and ruthenium using spray impregnation process, wherein, a first precursor solution containing a salt of nickel dissolved in water is sprayed on the alumina support followed by spraying of second precursor solution containing a salt of ruthenium dissolved in water to obtain nickel and alumina sprayed alumina support.

The first precursor solutions of varying concentration are prepared by dissolving 0.2 mol % to 1.5 mol % of one or more nickel salt selected from nickel (II) nitrate hexahydrate and nickel (II) acetate tetrahydrate in water. In most preferred embodiments, the first precursor solution is prepared by dissolving 0.4 mol % to 0.6 mol % of nickel (II) nitrate hexahydrate in water.

The second precursor solutions of varying concentration are prepared by dissolving 0.01 mol % to 0.1 mol % of one or more ruthenium salt selected from ruthenium chloride hydrate, ruthenium (III) nitrosyl nitrate in water. In most preferred embodiments, the second precursor solution is prepared by dissolving 0.01 mol % to 0.05 mol % of ruthenium chloride in water.

The nickel and ruthenium sprayed alumina support is then dried to obtain dried nickel-ruthenium loaded alumina support. The wet nickel and ruthenium sprayed alumina support is dried initially under vacuum at a temperature range of 50 to 100 ℃. The partially dried nickel-ruthenium loaded alumina support thus obtained is further dried in an oven at a temperature range of 60 to 120 ℃. Depending upon the moisture content of the dried nickel-ruthenium loaded alumina support, further drying may be performed in air at a temperature range of 450 to 550 ℃ for a duration of 4 to 12 hours.

In most preferred embodiments, the wet nickel and ruthenium sprayed alumina support is dried initially under vacuum at a temperature range of 60 to 80 ℃, followed by drying in an oven at a temperature range of 80 to 100 ℃, and then air drying at a temperature range of 450 to 520 ℃ for a duration of 8 to 12 hours.

The dried nickel-ruthenium loaded alumina support thus obtained is calcined to obtain the bi-metallic nickel-ruthenium based hydrogenating catalyst. The calcination is carried out at a temperature range of 450 to 550 ℃ for a duration of 2 to 10 hours in muffle air-furnace. In most preferred embodiments, the calcination is carried out at a temperature range of 480 to 520 ℃ for a duration of 4 to 8 hours to obtain bi-metallic nickel-ruthenium based hydrogenating catalyst.

The bi-metallic hydrogenating catalyst provided by the present invention comprises nickel and ruthenium loaded on a refractory metal oxide support. The bi-metallic catalyst comprises 5 to 50 weight percent of nickel and 0.01 to 0.5 weight percent of ruthenium. In the most preferred embodiments, the weight percent of nickel in the bi-metallic catalyst is 20 to 30 percent by weight and the weight percent of ruthenium is 0,05 to 0.2 percent by weight. Advantageously, the bi-metallic hydrogenating catalyst has reducibility of nickel metal in the range of 80 % to 90 % at a reduction temperature in the range of 440 to 480 ℃. The applicant has unexpectedly observed that it is possible to optimize the weight percent of nickel and ruthenium in the bi-metallic nickel-ruthenium based hydrogenating catalyst to enhance reducibility of nickel along with reduction of the weight percent of nickel in the catalyst without compromising the hydrogenation capabilities of the nickel catalyst.

The refractory metal oxide support on which nickel is loaded is selected from alumina, silica, titania, and zirconia. In preferred embodiments, the refractory metal oxide support is an alumina support or modified alumina support. The modified alumina support is phosphorus modified alumina support.

The bi-metallic nickel-ruthenium based hydrogenating catalyst disclosed herein can be advantageously used to produce solvents having very low aromatic content from a heavy hydrocarbon feedstream. The heavy hydrocarbon feedstream may have very high aromatic content in range of 5000 ppm to 40000 ppm, and sulfur content ranging from 0 ppm to 1 ppm. In the most preferred embodiments, the heavy hydrocarbon feedstream has aromatic content in range of 5000 to 20000 ppm. The de-aromatized solvents obtained using the bi-metallic nickel-ruthenium catalyst has very low aromatic content in a range of 5 ppm to 100 ppm and sulfur content in a range of 0.5 ppm to 1 ppm. In the most preferred embodiments, the aromatic content in the de-aromatized solvents is in range of 20 ppm to 50 ppm.

The process for preparing de-aromatized hydrocarbon solvents from the selective hydrogenation of a hydrocarbon feedstream disclosed herein involves distillation of a heavy hydrocarbon feedstream, followed by catalytic hydrotreatment, fractionation and catalytic selective hydrogenation.

The hydrocarbon feedstream utilized for the production of de-aromatized solvents is one or more selected from crude oil, heavy vacuum gas oil, and lube base oil. The hydrocarbon feedstream is distilled to obtain a first distillate having boiling point in the range of 180° C to 550° C.

The first distillate is then subjected to hydrotreatment in presence of hydrotreating catalyst to obtain a hydrocarbon stream having sulfur content of less than 100 ppm, The hydrotreating catalyst used in the process comprises one or more active metals selected from cobalt, nickel, and molybdenum-phosphorus impregnated on one or more support selected from alumina, silica, titania, and zirconia.

The hydrotreatment of the first distillate in the process is carried out at a reactor temperature ranging from 300° C to 450 °C, reactor pressure ranging from 60 bar to 180 bar, weight hourly space velocity (WHSV) ranging from 0.5 h−1 to 3.0 h−1, and volume ratio of hydrogen to heavy hydrocarbon stream ranging from 100 Nm3/m3 to 1500 Nm3/m3. In the most preferred embodiments, the hydrotreatment of the first distillate is carried out at a reactor temperature ranging from 350° C to 400 °C, reactor pressure ranging from 100 bar to 150 bar, weight hourly space velocity (WHSV) ranging from 0.75 h−1 to 1.25 h−1, and volume ratio of hydrogen to heavy hydrocarbon stream ranging from 400 Nm3/m3 to 1000 Nm3/m3

The hydrocarbon stream having sulfur content of less than 100 ppm is then isodewaxed and fractionated to obtain a second distillate having boiling point in the range of 150° C to 350° C.

The second distillate is then subjected to selective hydrogenation in the presence of a bi-metallic nickel-ruthenium based hydrogenating catalyst to obtain the de-aromatized hydrocarbon solvents aromatic content in a range of 5 ppm to 100 ppm and sulfur content in a range of 0.5 ppm to 1 ppm. In the most preferred embodiment, the aromatic content of de-aromatized solvent obtained is in a range of 20 ppm to 50 ppm.

The selective hydrogenation of the second distillate in the process is carried out at a reactor temperature ranging from 80 °C to 200 °C, reactor pressure ranging from 25 bar to 35 bar, liquid hourly space velocity (LHSV) ranging from 0.25 h-1 to 2.0 h-1, and volume ratio of hydrogen to second distillate ranging from 40 Nm3/m3 to 100 Nm3/m3. In the most preferred embodiments, the selective hydrogenation of the second distillate in the process is carried out at a reactor temperature ranging from 140 °C to 180 °C, reactor pressure ranging from 10 bar to 45 bar, liquid hourly space velocity (LHSV) ranging from 0.5 h-1 to 1.0 h-1, and volume ratio of hydrogen to second distillate ranging from 50 Nm3/m3 to 70 Nm3/m3.
The reactor pressure and volume ratio of hydrogen to second distillate is advantageously low in comparison to other processes for the preparation of de-aromatized solvents from hydrocarbons.
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: Preparation of bi-metallic nickel-ruthenium based hydrogenating catalyst
Example 1.1: Preparation of alumina support
Commercial pseudo boehmite (PB700, Pacific Industrial Development corporation, PIDC) is mixed with 0.1 N HNO3 solution to prepare a dough which is then extruded using a dye of 2 mm X 3 mm Trilobite, followed by drying for 12 hours at 120 ℃ and calcination at 500 ℃ with a heating ramp rate of 5 ℃ /min. The sample is then subjected to calcination for 4 hours in an open-air furnace to obtain alumina extrudes of Trilobite shape having diameter of 2mm X 3 mm. The alumina extrudes thus obtained is sprayed with precursor solution of nickel with varying concentrations to obtained nickel sprayed alumina extrudes. The nickel sprayed alumina extrudes are then sprayed with precursor solution of ruthenium to obtain bi-metallic Ni-Ru based catalyst disclosed in the present invention. The bi-metallic Ni-Ru hydrogenating catalyst in Example 1.2-1.4 provided below are prepared using nickel salt solution having nickel salt w/w % as 260, 218 and 69 respectively. The Ru salt w/w % in the ruthenium salt solution is kept constant at 2 w/w % in all the examples.
Example 1.2: Preparation of Ni-Ru catalyst using 260 w/w % Ni salt solution and 2 w/w % of Ru salt solution
37.5 grams of alumina extrudes prepared as per the process disclosed in Example-1 above is then dispersed with nickel and ruthenium through spray impregnation wherein a solution containing 182 grams of Ni(NO3)2.6H2O in 70 ml of distilled water is sprayed on the extrudes followed by spraying of a solution containing 0.2 grams of ruthenium chloride hydrate in 10 mL (0.1 percent weight basis) of distilled water. The wet nickel and ruthenium sprayed alumina extrudes thus obtained is dried under vacuum at 70 ℃ followed by drying at 120 ℃ for 12 hours. The dried extrudes is then subjected to calcination at 450 ℃ at a heating rate 5 ℃/min for a duration of 5 hours in an open -air muffle furnace to obtain a catalytic system comprising nickel and ruthenium dispersed on alumina support.
Example 1.3: Preparation of Ni-Ru catalyst using 218 w/w % Ni salt solution and 2 w/w % of Ru salt solution
37.5 grams of alumina extrudes prepared as per the process disclosed in Example-1 above is then dispersed with nickel and ruthenium through spray impregnation wherein a solution containing 109.2 grams of Ni(NO3)2.6H2O in 50 ml of distilled water is sprayed on the extrudes followed by spraying of a solution containing 0.2 grams of ruthenium chloride hydrate in 10 mL (0.1 percent weight basis) of distilled water. The wet nickel and ruthenium sprayed alumina extrudes thus obtained is dried under vacuum at 70 ℃ followed by drying at 120 ℃ for 12 hours. The dried extrudes is then subjected to calcination at 450 ℃ at a heating rate 5 ℃/min for a duration of 5 hours in an open -air muffle furnace to obtain a catalytic system comprising nickel and ruthenium dispersed on alumina support.
Example 1.4: Preparation of Ni-Ru catalyst using 69 w/w % Ni salt solution and 2 w/w % of Ru salt solution
37.5 grams of alumina extrudes prepared as per the process disclosed in Example-1 above is then dispersed with nickel and ruthenium through spray impregnation wherein a solution containing 103.2 grams of Ni(NO3)2.6H2O in 150 ml of distilled water is sprayed on the extrudes followed by spraying of a solution containing 0.2 grams of ruthenium chloride hydrate in 10 mL (0.1 percent weight basis) of distilled water. The wet nickel and ruthenium sprayed alumina extrudes thus obtained is dried under vacuum at 70 ℃ followed by drying at 120 ℃ for 12 hours. The dried extrudes is then subjected to calcination at 450 ℃ at a heating rate 5 ℃/min for a duration of 5 hours in an open -air muffle furnace to obtain a catalytic system comprising nickel and ruthenium dispersed on alumina support.
Example 2: Assessment of physical-chemical and mechanical characteristics of the Ni-Ru catalyst
The physical-chemical and mechanical characteristics of the catalytic systems prepared in Examples 1.2, 1.3, and 1.4 are assessed and the data is provided below in Table-1:
Table-1: Physical-chemical and mechanical characteristics of the Ni-Ru catalyst

Example Surface area in m2/g Pore volume in
Cc/g Pore diameter in Angstroms Metal percentage by ICP
1.2 154 0.46 60 27.1% Ni, 0.1 % Ru
1.3 167 0.46 62 27.2% Ni, 0.1 % Ru
1.4 184 0.42 53 27% Ni, 0.1 % Ru

Example 3: Assessment of de-aromatization efficiency of the Ni-Ru catalyst

A hydrocarbon feedstream comprising 8500 ppm of monoaromatics, 115 ppm of di-aromatics, and 52 ppm of poly-aromatics is subjected to a hydrogenation reaction in presence of catalyst systems prepared in Examples 1.2, 1.3, and 1.4 at a temperature of 160 ℃, pressure of 30 bar, H2/HC ratio of 100 Nm3/m3 and LHSV of 0.71 s-1 at 24 hours TOS and the amount of monoaromatics, diaromatics and polyaromatics in the output stream is ascertained to determine de-aromatization efficiency of the catalysts. The results are provided in Table-2 below: Nm3/m3 and LHSV of 0.71

Table-2: Content of monoaromatics, diaromatics, and polyaromatics in the output stream

Example Feedstream
[Overall aromatic content]
Out-put stream
[Content of mono aromatics in ppm] Out-put stream
[Content of di-aromatics in ppm) Out-put stream
(Content of poly-aromatics in ppm)
1.2 8667 PPM 562 ND ND
1.3 8667 PPM 25 ND ND
1.4 8667 PPM 41 ND ND
ND: Non detectable
The bi-metallic Ni-Ru hydrogenating catalyst in Examples 1.2-1.4 are prepared using nickel salt solution having nickel salt w/w % as 260, 218 and 69 respectively. The Ru salt w/w % in the ruthenium salt solution is kept constant in Examples 1.2-1.4. The results in Table-2 reflect that the bi-metallic Ni-Ru hydrogenating catalysts prepared in Examples 1.2-1.4 are significantly reducing the content of mono-aromatics and completely saturating di-aromatics and poly-aromatics present in the heavy hydrocarbon feedstream. It can also be observed that the hydrogenation capabilities of bi-metallic Ni-Ru catalysts prepared by the process disclosed in Examples 1.2-1.4 is improving even if the concentration of nickel salt is decreasing in the nickel precursor solution used for spray impregnation.

Example 4: Obtaining low sulfur 2nd distillate from 1st distillate for production of de-aromatized hydrocarbon solvents
First distillate having IBP of 341 Deg C and FBP of 507 Deg C with sulfur of 1.2 wt% was hydrotreated at 348 Deg C, hydrogen to feed ratio of 664 Nm3/m3, WHSV 0.92 Hr-1, pressure 145 barg, using hydrotreating catalyst of Nickel-Cobalt on alumina. Then the hydrotreated stream was isodewaxed and fractionated to obtain second distillate having IBP of 160 Deg C and FBP of 336 Deg C having sulfur less than 1 ppm and aromatics 6800 ppm.
Table 3: Properties of First Distillate and second distillate
Properties First Distillate Second distillate
ASTM D86 (Deg C) IBP 341 160
5% 376 168
10% 386 186
20% 402 218
30% 411 243
40% 422 263
50% 430 280
60% 438 293
70% 446 304
80% 456 314
90% 470 324
95% 481 330
FBP 507 336
Sulfur ppm 12000 less than 1
Density gm/cc 0.8719 0.804
Aromatics ppm - 6800
, Claims:1. A process for preparation of a bi-metallic hydrogenating catalyst, wherein the process comprises steps of:
(i) obtaining an extruded alumina support from an alumina dough, wherein the alumina dough is prepared by mixing alumina powder in an acid;
(ii) drying the extruded alumina support for a duration of 5 to 15 hours at a temperature range of 60 to 120 ℃ to obtain a dried alumina support;
(iii) calcining the dried alumina support at a temperature range of 450 to 550 ℃ for a duration of 2 to 10 hours to obtain a calcined alumina support;
(iv) spraying a first precursor solution on the calcined alumina support to obtain a nickel sprayed alumina support, wherein the first precursor solution is prepared by dissolving a salt of nickel in water;
(v) spraying a second precursor solution on the nickel sprayed alumina support to obtain a nickel-ruthenium sprayed alumina support, wherein the second precursor solution is prepared by dissolving a salt of ruthenium in water;
(vi) drying the nickel-ruthenium sprayed alumina support to obtain a dried nickel-ruthenium loaded alumina support; and
(vii) calcining the dried nickel-ruthenium loaded alumina support at a temperature range of 450 to 550 ℃ for a duration of 2 to 10 hours to obtain the bi-metallic hydrogenating catalyst.
2. The process as claimed in claim 1, wherein the alumina powder is selected from boehmite, pseudo boehmite, gibbsite, direct alumina, aluminum hydroxide, aluminum chlorides, aluminum sulfates, dawsonites, and a combination thereof, and wherein the alumina powder has surface area in range of 200 to 400 m2/gr.
3. The process as claimed in claim 1, wherein the acid is selected from nitric acid, acetic acid, phosphoric acid, and a combination thereof.
4. The process as claimed in claim 1, wherein the first precursor solution contains salt of nickel in the range of 0.2 to 1.5 mol %, and wherein the salt of nickel is selected from nickel (II) nitrate hexahydrate, nickel (II) acetate tetrahydrate, and combination thereof.
5. The process as claimed in claim 1, wherein the second precursor solution contains salt of ruthenium in the range of 0.01 to 0.1 mol %, and wherein the salt of ruthenium is selected from ruthenium chloride hydrate, ruthenium (III) nitrosyl nitrate, and a combination thereof.
6. The process as claimed in claim 1, wherein drying is carried out initially under vacuum at a temperature range of 50 to 100 ℃, followed by drying in an oven at a temperature range of 60 to 120 ℃, and then air drying at a temperature range of 450 to 550 ℃ for a duration of 4 to 12 hours.
7. A bi-metallic hydrogenating catalyst for producing de-aromatized hydrocarbon solvents through selective hydrogenation of a hydrocarbon feedstream, wherein the bi-metallic hydrogenating catalyst comprises 5 to 50 weight % of nickel and 0.01 to 0.5 weight % of ruthenium dispersed on a refractory metal oxide.
8. The catalytic composition as claimed in claim 7, wherein the refractory metal oxide is selected from the group consisting of alumina, silica, titania, zirconia, and combination thereof.
9. The catalytic composition as claimed in claim 8, wherein the refractory metal oxide support is selected from alumina, a modified alumina, and a combination thereof.
10. The catalytic composition as claimed in claim 9, wherein the modified alumina is a phosphorous modified alumina.
11. The catalytic composition as claimed in claim 7, wherein the hydrocarbon feedstream is heavy and middle distillate having aromatic content ranging from 5000 ppm to 40000 ppm, and sulfur content ranging from 0 ppm to 1 ppm.
12. The catalytic composition as claimed in claim 7, wherein the nickel metal has reducibility in the range of 80 % to 90 % at a reduction temperature in the range of 440 to 480 ℃.
13. A process for preparing de-aromatized hydrocarbon solvents from selective hydrogenation of a hydrocarbon feedstream, wherein the process comprises steps of:
(i) distilling a heavy hydrocarbon feedstream to obtain a first distillate having boiling point in the range of 180° C to 550° C;
(ii) hydrotreating the first distillate in the presence of a hydrotreating catalyst to obtain a stream having sulfur content less than 100 ppm;
(iii) iso-dewaxing followed by fractionating the stream having sulfur content less than 100 ppm to obtain a second distillate having boiling point in the range of 150° C to 350° C; and
(iv) subjecting the second distillate to selective hydrogenation in the presence of a bi-metallic hydrogenating catalyst as claimed in claims 1-12 in a hydrogenation reactor to obtain the de-aromatized hydrocarbon solvents.
14. The process as claimed in claim 13, wherein the hydrotreatment is carried out at a reactor temperature ranging from 300° C to 450 °C, reactor pressure ranging from 60 bar to 180 bar, weight hourly space velocity (WHSV) ranging from 0.5 h−1 to 3.0 h−1, and volume ratio of hydrogen to heavy hydrocarbon stream ranging from 100 Nm3/m3 to 1500 Nm3/m3.
15. The process as claimed in claim 13, wherein the selective hydrogenation is carried out at a reactor temperature ranging from 80 °C to 200 °C, reactor pressure ranging from 10 bar to 45 bar, liquid hourly space velocity (LHSV) ranging from 0.25 h-1 to 2.0 h-1, and volume ratio of hydrogen to second distillate ranging from 40 Nm3/m3 to 100 Nm3/m3.
16. The process as claimed in claim 13, wherein the second distillate having aromatic content ranging from 5000 ppm to 20,000 ppm, and sulfur content ranging from 0 ppm to 1 ppm.
17. The process as claimed in claim 13, wherein the hydrocarbon feedstream is selected from crude oil, heavy vacuum gas oil, lube base oil, and a combination thereof.
18. The process as claimed in claim 13, wherein the hydrotreating catalyst is selected from a catalyst having active metals impregnated on a support selected from alumina, silica, titania, zirconia, and wherein the active metals are selected from cobalt, nickel, molybdenum, phosphorus, and a combination thereof.
19. The process as claimed in claim 13, wherein the de-aromatized hydrocarbon solvent has an aromatic content in a range of 5 ppm to 100 ppm and sulfur content in a range of 0.5 ppm to 1 ppm.