Nanocatalyst for heavy crude oil upgrading and method for synthesizing same

Abstract

A dispersing-type nanocatalyst for catalytic hydrocracking of heavy oil, a method for preparing the same, and the use thereof in catalytic hydrocracking of heavy oil. The present invention is also directed to reducing the operational temperature of catalytic hydrocracking of heavy crude oil, and also increasing the yield of the process by utilizing a lower concentration of said nanocatalyst.

Claims

1. A heavy crude oil nanocatalyst comprising: exfoliated transition metal sulfide nanoparticles, wherein said nanoparticles are dispersed in a nonpolar solvent.

2. The heavy crude oil nanocatalyst according to claim 1, wherein the transition metal is from the fifth or the sixth group of transition metals in the periodic table of the elements.

3. The heavy crude oil nanocatalyst according to claim 1, wherein said transition metal sulfide is selected from the group consisting of molybdenum disulfide, tungsten disulfide, chromium sulfide, and mixtures thereof.

4. The heavy crude oil nanocatalyst according to claim 1, wherein said nonpolar solvent is decalin.

5. The heavy crude oil nanocatalyst according to claim 1, wherein said transition metal sulfide is molybdenum disulfide.

6. The heavy crude oil nanocatalyst according to claim 1, wherein said transition metal sulfide is tungsten disulfide.

7. The heavy crude oil nanocatalyst according to claim 1, wherein said exfoliated transition metal sulfide comprises a weight percentage of the nanocatalyst ranging from about 0.5% to about 5%.

8. The heavy crude oil nanocatalyst according to claim 1, wherein said exfoliated transition metal sulfide nanoparticles have an average size of about 30 nm to about 90 nm.

9. The heavy crude oil nanocatalyst according to claim 1, wherein said nanocatalyst comprises a layered structure.

10. A method for synthesizing a heavy crude oil upgrading nanocatalyst, the method comprising: synthesizing transition metal sulfide nanoparticles; exfoliating the transition metal sulfide nanoparticles in a polar solvent; and exchanging the polar solvent with a nonpolar solvent, such that the heavy crude oil upgrading nanocatalyst is formed.

11. The method according to claim 10, wherein the transition metal is from the fifth or the sixth group of transition metals in the periodic table.

12. The method according to claim 10, wherein said transition metal sulfide is selected from the group consisting of molybdenum disulfide, tungsten disulfide, chromium sulfide, and mixtures thereof.

13. The method according to claim 10, wherein said transition metal sulfide is molybdenum disulfide.

14. The method according to claim 10, wherein said transition metal sulfide is tungsten disulfide.

15. The method according to claim 10, wherein said polar solvent is water.

16. The method according to claim 10, wherein said nonpolar solvent is decalin.

17. The method according to claim 10, wherein said synthesizing is done using a technique selected from the group consisting of hydrothermal, sulfidation, sol-gel, spray pyrolysis, and combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as forming the present invention, it is believed that the invention will be better understood from the following description taken in conjunction with the accompanying DRAWINGS, where like reference numerals designate like structural and other elements, in which:

(2) FIG. 1 illustrates the rim-edge model of a MoS.sub.2 catalytic particle;

(3) FIG. 2 illustrates X-ray diffraction (XRD) patterns of MoS.sub.2 nanoparticles prepared by the indirect method, pursuant to the teachings of the present invention;

(4) FIG. 3 is a scanning electron microscope (SEM) image of MoS.sub.2 nanoparticles prepared by the indirect method with image resolution of 500 nm;

(5) FIG. 4 is a scanning electron microscope (SEM) image of MoS.sub.2 nanoparticles prepared by hydrothermal method, pursuant to the teachings of the present invention;

(6) FIG. 5 is the transmission electron microscope (TEM) images of the exfoliated MoS.sub.2 nanoparticles, with image resolutions of 200 nm, 64 nm, and 32 nm, respectively; and

(7) FIG. 6 is the transmission electron microscopy (TEM) images of the exfoliated commercial MoS.sub.2 microparticles, with image resolutions of 200 nm (TOP LEFT), 160 nm (TOP RIGHT), 100 nm (BOTTOM LEFT), and 80 nm (BOTTOM RIGHT).

DETAILED DESCRIPTION OF THE INVENTION

(8) The following detailed description is presented to enable any person skilled in the art to make and use the invention. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that these specific details are not required to practice the invention. Descriptions of specific applications are provided only as representative examples. Various modifications to the preferred embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the scope of the invention. The present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.

(9) It should be understood by a person skilled in the art that the innovation described herein is directed to various improvements in the synthesis of a nanocatalyst for heavy crude oil upgrading, a method for preparing the same and the use thereof in catalytic hydrocracking of heavy oil. It should, of course, be understood that aspects of the instant invention may also prove useful in related contexts, as is understood to those of skill in the pertinent arts.

(10) The heavy crude oil upgrading nanocatalyst presented in this invention includes one or perhaps several exfoliated nanometal sulfides, such as from the sixth group of transition elements in the periodic table. This nanocatalyst has a layered structure consisting of planes with nanometric distances, as described further hereinbelow.

(11) A preferred synthesis method for the nanocatalyst is also disclosed in the present application, which includes preferably three main steps: first, synthesizing one or perhaps several nanometal sulfides using metals from sixth group of transition elements in the periodic table; second, exfoliating metal sulfide nanoparticles in a polar solvent; and, finally, exchanging the polar solvent with a nonpolar solvent as discussed in more detail hereinbelow.

(12) Regarding the first step or stage, transition metal sulfide nanoparticles can be synthesized by either sulphidation of transition metal oxide nanoparticles or by conventional, more direct methods, such as a hydrothermal method. Transition metal oxide nanoparticles can be synthesized via conventional methods known to a person skilled in the art, such as by sol-gel or spray pyrolysis, and like techniques.

(13) As is understood in the art, the hydrothermal method is carried out in a pressurized autoclave. In a preferred embodiment of the present invention, the precursor in the hydrothermal method is a water soluble transition metal salt, such as ammonium hepta molybdate, and the sulfur source is an alkaline metal sulfide, such as sodium sulfide.

(14) Hydrothermal cells are filled with water solution of said alkaline metal sulphide or sulfide and water soluble transition metal salt up to, for example, 75 percent by volume of the cell. The transition metal sulfide nanoparticles are then produced as the final product. In one embodiment of the present invention, materials, such as urea, are used to create a porous structure in the final product. Urea releases carbon dioxide or carbon monoxide, which leads to the formation of the aforementioned porous structures in the synthesized transition metal sulfide nanoparticles.

(15) As mentioned hereinabove, transition metal sulfide nanoparticles are also synthesized through an indirect method, in which transition metal oxide nanoparticles are sulphadized in the presence of H.sub.2/He as reducing gas, and H.sub.2S as sulphidizing gas in a horizontal tubular furnace.

(16) Transition metal sulfide nanoparticles produced via any of the two methods described hereinabove are exfoliated in the next stage of the nanocatalyst synthesis process of the present invention.

(17) It should be understood by a person skilled in the art that the transition metal sulfide nanoparticle (hereinafter termed nanometal sulfide) structure has a significant effect on the activity of the nanocatalyst. As is known from the prior art, nanometal sulfides have layered structures with weak van der Waals interlayer bondings. It is also known that active sites in nanometal sulfide are metallic sites with sulfur vacancies, and these sites are closely associated with the edges of the layers of the crystal.

(18) With reference now to FIG. 1 of the DRAWINGS, this figure illustrates a rim-edge model describing the aforementioned layered structure of an exemplar transition metal sulfide nanoparticle, namely MoS.sub.2. As can be seen in this figure, the top and bottom layers of the MoS.sub.2 slab are called the rim sites. The planes in between, designated by the color white, are called the edge planes.

(19) According to this rim-edge model, hydrogenation reactions are catalyzed predominantly by the aforedescribed rim sites. Both hydrogenation and hydrogenolysis are catalyzed on all the edge planes. The basal plane of the nanometal sulfide, also illustrated in FIG. 1, is considered to be inert catalytically.

(20) Regarding the second step or stage, the nanometal sulfide exfoliating stage, this is where a unique structure for the aforesaid nanoparticles catalyst is created. In this unique structure, each of the exfoliated nanometal sulfide layers can act as a rim site. In other words, exfoliation separates the nanometal sulfide layers, and thereby increases the number of active rim sites. Accordingly, the overall activity of nanocatalyst increases significantly.

(21) The importance of the nanometric size of the transition metal sulfide particles and its effect on the exfoliation step results should be understood. Using transition metal sulfide nanoparticles, instead of transition metal microparticles, results in reactive rim sites with a more regular formation with the aforementioned rim sites having nanometric thicknesses and nanometric interlayer distances, which, in turn, leads to an increase in the catalyst reactivity.

(22) The nanometal sulfide, synthesized as described hereinabove, is preferably exfoliated via a conventional method known from the prior art. In this method, nanometal sulfide is intercalated with lithium by mixing the nanometal sulfide with n-butyllithium in hexane under nitrogen atmosphere. The mixture is then left to age. The supernatant is subsequently decanted and the remaining Li-intercalated nanometal sulfide is exfoliated by adding water and sonicating the resultant mixture. The exfoliated nanometal sulfide is then collected by centrifugation, and washed with water for neutralization. The resultant mixture contains nanometal sulfide particles dispersed in water, and is called or termed hereinafter as exfoliated nanometal sulfide.

(23) In a preferred embodiment of the present invention, nanometal sulfide is intercalated with lithium by mixing the nanometal sulfide with a 1.6 molar solution of n-butyllithium in hexane under nitrogen atmosphere. The mixture is then left to age for at least 72 hours.

(24) Finally, in the third step or stage, the exfoliated nanometal sulfide is washed with an alcoholic solvent for a phase exchange. The resultant mixture is then washed with a nonpolar solvent. The resultant nanocatalyst contains exfoliated nanometal sulfide particles dispersed in the aforementioned nonpolar solvent.

(25) In one embodiment of the present invention, the alcoholic solvent is preferably ethanol or 2-propanol. In another embodiment, the nonpolar solvent is preferably decalin.

(26) In some embodiments of the present invention, the minimum amount of the exfoliated nanometal sulfide particles dispersed in the nonpolar solvent is preferably about 0.5% to about 2% by weight.

(27) It should be understood by a person skilled in the art that the exfoliated nanocatalyst disclosed in the present invention can be used for any kind of heavy crude oil hydrocracking, and it can be used in any slurry hydrocracking process.

(28) As is known from the prior art, hydrocracking processes are usually carried out at temperatures higher than 400 C. and pressures between about 30 to 110 bars. The reaction time is generally between about 0.5 to about 2 hours. Using the nanocatalyst particles made by the instant invention as disclosed hereinabove, however, with a preferred concentration range from about 150 ppm and about 300 ppm, and more preferably form about 150 ppm and about 250 ppm, the hydrocracking process can be carried out in a lower temperature range, preferably from about 330 C. to about 370 C., and more preferably at about 350 C. As is well understood to those of skill in the art, the aforementioned reduction in the reaction temperature for the hydrocracking process is a significant industrial production advantage, achieved by the use of said nanometal sulfide particles prepared by the method described in the present invention.

(29) In an effort to illustrate the methods for the production of the catalyst pursuant to the present invention and their performance, some examples are set forth hereinbelow. It should be understood that these examples are exemplary and illustrative only. The examples should not be deemed as limiting the scope of the present invention. The only limitations of the scope of the instant case are set forth in the claims appended hereinbelow.

Example 1

(30) In this example MoS.sub.2 nanoparticles (hereinafter nano-MoS.sub.2 particles) are synthesized via the aforementioned indirect method. MoO.sub.3 nanoparticles are used as the precursor in the gas-phase reaction in the presence of H.sub.2/He as reducing gas and H.sub.2S as sulphidizing gas at 850 C. for 1 hour in a horizontal tubular furnace.

(31) With reference now to FIG. 2 of the DRAWINGS, this figure illustrates the X-Ray Diffraction (XRD) patterns of the nanoparticles synthesized via the indirect method, as described hereinabove. As is known to a person skilled in the art, comparing all the diffractions shown in this figure with the standard Joint Committee on Powder Diffraction Standards (JCPDS) card No. 37-149, confirms the presence of MoS.sub.2 hexagonal crystalline network in the prepared sample. The average particle size of the sample can be calculated from the 0002 diffraction plane, designated in FIG. 2 of the DRAWINGS, with a Debye-Scherrer formula, as is known to those of skill in the art. The average size of MoS.sub.2 particles, produced via the indirect method described hereinabove, is about 50 nm.

(32) With reference now to FIG. 3 of the DRAWINGS, there is illustrated a scanning electron microscope (SEM) image of nano-MoS.sub.2 particles prepared by the indirect method described hereinabove, with an image resolution of 500 nm. This image confirms the nanometric size of MoS.sub.2 particles and their semi-spherical morphology and homogeneous distribution.

Example 2

(33) In this example, nano-MoS.sub.2 particles are synthesized via the aforementioned hydrothermal method. Here, 2 grams of ammonium hepta molibdate and 2 grams of urea are dissolved in 150 milliliters of distilled water. Then, the solution is transferred to the hydrothermal cell and the hydrothermal reaction is carried out at 180 C. for 24 hours. The product is washed with water and ethanol; finally, it is dried in the oven.

(34) With reference now to FIG. 4 of the DRAWINGS, there is illustrated a scanning electron microscope (SEM) image of nano-MoS.sub.2 particles prepared by the hydrothermal method described hereinabove, with an image resolution of 500 nm. This image illustrates the strain-like structure of said MoS.sub.2 particles, as well as their nanometric size.

Example 3

(35) In this example, nano-MoS.sub.2 particles are exfoliated via a method described in more details hereinafter. Here, 7 grams of the nano-MoS.sub.2 particles, prepared via either of the two methods described hereinabove, are exfoliated using 400 milliliters of a 1.6 molar solution of n-butyl Lithium in n-Hexane under nitrogen atmosphere for 3 hours. The product is then washed with water, 2-Propanol and decalin, consecutively. The solution is preferably sonicated in a sonication bath for 15 minutes at ambient temperature for each washing step. The resultant solution contains the exfoliated nanometal sulfide particles dispersed in decalin.

Example 4

(36) In this example, a hydrocracking reaction is carried out at 350 C. using the exfoliated MoS.sub.2 nanocatalyst, synthesized as described in the examples 1-3 hereinabove. Here, 200 ppm of the aforementioned exfoliated nanocatalyst, which contains 2% by weight of the active metal in decalin, is added to about 150 grams of a heavy crude oil with properties presented hereinbelow in TABLE 1. A steel autoclave is loaded with this mixture and is pressurized with H.sub.2 gas, and then it is heated at a rate of 5 C./min up to the desired reaction temperature. The reaction pressure could be in the range of about 30 bars to about 80 bars, and the reaction time is about 0.5 to 2 hours. The resultant liquid product is called sample No. 1.

(37) TABLE-US-00001 TABLE 1 Heavy crude oil properties Property Amount Specific gravity @ 15.6/15.6 C. 0.9860 API Gravity 12.0 Kinematic Viscosity @ 100 C. (cSt) 96.05 Sulfur content (wt %) 4.80 Carbon content (wt %) 84.0 Hydrogen content (wt %) 10.5

Example 5

(38) In this example, hydrocracking reaction is carried out at 370 C. using the exfoliated MoS.sub.2 nanocatalyst. Here, 200 ppm of the aforementioned exfoliated nanocatalyst, which contains 2% by weight of the active metal in decalin, is added to about 200 grams of a heavy crude oil with properties presented hereinabove in TABLE 1. A steel autoclave is loaded with this mixture and is pressurized with H.sub.2 gas, and then it is heated at a rate of 5 C./min up to the desired reaction temperature. The reaction pressure could be in the range of about 30 bars to about 80 bars, and the reaction time is about 0.5 to 2 hours. The resultant liquid product is called sample No. 2.

Example 6

(39) In this example, a hydrocracking reaction is carried out at 297 C. using the exfoliated MoS.sub.2 nanocatalyst, synthesized as described in example 3 hereinabove. In this example, 200 ppm of the aforementioned exfoliated nanocatalyst, which contains 2% by weight of the active metal in decalin, is added to about 200 grams of a heavy crude oil with properties presented hereinabove in TABLE 1. A steel autoclave is loaded with this mixture and is pressurized with H.sub.2 gas, and then it is heated at a rate of 5 C./min up to the desired reaction temperature. The reaction pressure could be in the range of about 30 bars to about 80 bars, and the reaction time is about 0.5 to 2 hours. The resultant liquid product is called sample No. 3.

Example 7

(40) In this example, the hydrocracking reaction is carried out at 350 C. using the exfoliated MoS.sub.2 nanocatalyst, synthesized as described in the example 3 hereinabove. In this example, 400 ppm of the aforementioned exfoliated nanocatalyst, which contains 2% by weight of the active metal in decalin, is added to about 200 grams of a heavy crude oil with properties presented hereinabove in TABLE 1. A steel autoclave is loaded with this mixture and is pressurized with H.sub.2 gas, and then it is heated at a rate of 5 C./min up to the desired reaction temperature. The reaction pressure could be in the range of about 30 bars to about 80 bars, and the reaction time is about 0.5 to 2 hours. The resultant liquid product is called sample No. 4.

Example 8

(41) In this example, the hydrocracking reaction is carried out at 350 C. using the exfoliated MoS.sub.2 nanocatalyst, synthesized as described in the example 3 hereinabove. In this embodiment example, 100 ppm of the aforementioned exfoliated nanocatalyst, which contains 2% by weight of the active metal in decalin, is added to about 200 grams of a heavy crude oil with properties presented hereinabove in TABLE 1. A steel autoclave is loaded with this mixture and is pressurized with H.sub.2 gas, and then it is heated at a rate of 5 C./min up to the desired reaction temperature. The reaction pressure could be in the range of about 30 bars to about 80 bars, and the reaction time is about 0.5 to 2 hours. The resultant liquid product is called sample No. 5.

(42) Heavy crude oil properties are compared with the various hydrocracking products obtained as described in examples 4-8 hereinabove, designated as samples No. 1-5, respectively. Based on the results presented in TABLES 2 and 3 hereinbelow, the exfoliated nanocatalyst exhibits remarkable performance in different operational conditions. With reference to the tables, sample No. 1 shows the lowest specific gravity and distillation range, and the highest API gravity.

(43) TABLE-US-00002 TABLE (2) Heavy crude oil properties in comparison with hydrocracking products obtained as described in examples 4-8 Heavy Sample crude Sample Sample Sample Sample Sample Properties oil NO. 1 NO. 2 NO. 3 NO. 4 NO. 5 API Gravity 12.0 28.0 21.3 17.5 11.2 16.3 Specific gravity 0.9860 0.8870 0.9260 0.9495 0.9915 0.9575 @15.6/ 15.6 C. Kinematic 2.177 4.413 2.177 6.168 2.605 Viscosity @ 40 C. (cSt) Kinematic 96.05 18.49 Viscosity @ 100 C. (cSt) Sulphur content 4.80 2.84 4.62 4.62 3.39 3.41 (wt %) Carbon 84.0 85.5 83.2 83.2 86.2 86.9 content (wt %) Hydrogen 10.5 10.8 10.5 10.5 8.4 8.4 content (wt %) Nitrogen 1.1 1.3 1.2 1.2 0.6 0.7 content (wt %)

(44) TABLE-US-00003 TABLE (3) Heavy crude oil properties in comparison with hydrocracking products obtained as described in examples 4-8 Distillation range 760 mmHg (vol %) Heavy Sample Sample Sample Sample ASTM D86 C. crude oil NO. 1 NO. 2 NO. 3 NO. 4 IBP 262 84 55 211 22.2 @ 5% 290 98 101 265 110.0 @ 10% 312 105 114 303 143.0 @ 15% 355 111 117 346 165.0 @ 20% 387 115 129 395 180.0 @ 30% 410 121 147 445 190.0 @ 40% 455 130 156 505 196.0 @ 50% 148 159 533 205.0 @ 60% 495 211 223.0 @ 70% 517 271 290.0 @ 80% 533 358.0 EP 533 533 392.0

Comparative Example

(45) It should be understood that the use of MoS.sub.2 microparticles to synthesize exfoliated MoS.sub.2 catalysts is known in the prior art. In this comparative example, however, the structure and the performance of the exfoliated MoS.sub.2 nanocatalyst is compared with the structure and the performance of an exfoliated MoS.sub.2 catalyst, synthesized using commercial MoS.sub.2 microparticles (hereinafter micro-MoS.sub.2). Both nano-MoS.sub.2 particles and micro-MoS.sub.2 particles are exfoliated via the method described in connection with Example 3 hereinabove. The resultant catalysts are then used in a heavy crude oil hydrocracking process. The experimental conditions under which the hydrocracking process is carried out in the present invention is compared to the hydrocracking conditions disclosed in the prior art, as set forth and shown in TABLE 4 presented hereinbelow.

(46) Furthermore, the resultant products from the two hydrocracking processes are compared and the results are also set forth and shown in TABLE 5 presented hereinbelow.

(47) TABLE-US-00004 TABLE 4 Experimental conditions of hydrocracking process in the presence of MoS.sub.2 micro and nano particles Exfoliated MoS.sub.2 Exfoliated MoS.sub.2 Reaction Conditions microparticles nanoparticles Reaction Temperature 400-450 C. 350 C. Catalyst concentration 600 ppm 200 ppm

(48) TABLE-US-00005 TABLE 5 Product properties of hydrocracking process in the presence of MoS.sub.2 micro and nano particles Wt % of the product Wt % of the product using Exfoliated MoS.sub.2 using Exfoliated MoS.sub.2 BOILING POINTS microparticles nanoparticles LESS THAN 177 C. 4.04 17 177-343 C. 25.02 48 343-525 C. 29.71 15 MORE THAN 525 C. 41.23 20

(49) As can be seen in TABLE 4, the optimal catalyst dosage, as set forth in the prior art for exfoliated micro-MoS.sub.2 catalyst, is 600 ppm, while the optimal catalyst dosage in the comparative example for a nanocatalyst synthesized according to the method described in the present invention is about 200 ppm. The results obtained and presented in TABLE 5 hereinabove show that the hydrocracking process carried out using the nanocatalyst disclosed in the present invention produces lighter liquids compared to the process disclosed in the prior art, even though using a significantly lower dosage of the nanocatalyst in the process.

(50) Furthermore, the aforementioned reduction in the reaction temperature, as well as reduction in the overall amount of the catalyst dosage for the hydrocracking process, represent a significant economic advantage and makes the slurry hydrocracking process economically feasible, which is not feasible in the prior art.

(51) For a more detailed comparison between the two catalysts described hereinabove, transmission electron microscope (TEM) images of the exfoliated nano-MoS.sub.2 catalyst and the exfoliated micro-MoS.sub.2 catalyst are presented in FIGS. 5 and 6 of the DRAWINGS, respectively, described hereinbelow.

(52) With reference now to FIG. 5 of the DRAWINGS, this figure illustrates transmission electron microscope (TEM) images of the aforesaid exfoliated nano-MoS.sub.2 particles, with image resolutions of 200 nm, 64 nm, and 32 nm, respectively. As can be seen in these images, the exfoliated MoS.sub.2 nanocatalysts, synthesized as disclosed via the techniques of the present invention, exhibit a regular formation with all the exfoliated planes formed parallel to each other, with the thickness of each exfoliated plane being about 3 nm.

(53) With reference now to FIG. 6 of the DRAWINGS, this figure illustrates transmission electron microscope (TEM) images of the exfoliated commercial micro-MoS.sub.2 particles, with image resolutions of 200 nm, 160 nm, 100 nm, and 80 nm respectively. As can be seen in these images, the resultant catalyst does not have the regular formation exhibited by the nanocatalysts formulated pursuant to the teachings and principles of the present invention. Considering the effect of the formation of the exfoliated MoS.sub.2 particles on the reactivity of the catalyst, the superior activity exhibited by the nanocatalysts of the instant invention can be explained.

(54) Using transition metal nanocatalysts disclosed in the present invention not only reduces the hydrocracking process temperature and catalyst dosage, but also increases lighter liquid yields, as is amply demonstrated in the comparative results set forth in TABLES 4 and 5 hereinabove.

(55) While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the breadth or scope of the applicant's concept. Furthermore, although the present invention has been described in connection with a number of exemplary embodiments and implementations, the present invention is not so limited but rather covers various modifications and equivalent arrangements, which fall within the purview of the appended claims.