Patent Application
20110155643
1. Field of the Invention
This invention relates broadly to the distillation of crude oil (petroleum) or a fraction of crude oil distillation. More particularly, this invention relates to methods of increasing the distillates yield during distillation of an unprocessed (raw) hydrocarbon composition by adding nanoparticles to the unprocessed hydrocarbon composition.
2. State of the Art
For much of the last century, crude oil (petroleum) has been one of the primary sources of energy world-wide. Crude oil contains primarily hydrocarbons. One of the major uses of crude oil is in the production of motor fuels such as gasoline and diesel. These motor fuels are obtained through the refining of crude oil into its various component parts. Refining results in the production of not only gasoline and diesel, but kerosene and heavy residues.
Refining of crude oil is typically accomplished by boiling at different temperatures (distillation) and using advanced methods to further process the products which have boiled off at those different temperatures. The chemistry of hydrocarbons underlying the distillation process is that the longer the carbon chain of the hydrocarbon component of the crude oil, the higher the temperature at which that component boils. As a result, a large part of refining involves boiling at different temperatures in order to separate the different fractions of crude oil and other intermediate streams.
As previously mentioned, crude oil or petroleum contains a mixture of a very large number of different hydrocarbons, most of which have between 5 and 40 carbon atoms per molecule. The most common molecules found in the crude oil are alkanes (linear or branched), cycloalkanes, aromatic hydrocarbons and more complicated chemicals like asphaltenes. Each petroleum variety has a unique mix of molecules which define its physical and chemical properties.
The alkanes are saturated hydrocarbons with straight or branched chains which contain only carbon and hydrogen and have the general formula CnH2n+2. The alkanes from pentane (C5H12) to octane (C8H18) are typically refined into gasoline (petrol). The alkanes from nonane (C9H20) to hexadecane (C16H34) are typically refined into diesel fuel and kerosene which is the primary component of many types of jet fuel. The alkanes from hexadecane upwards (i.e., alkanes having more than sixteen carbon atoms) are typically refined into fuel oil and lubricating oil. The heavier end of the alkanes includes paraffin wax (having approximately 25 carbon atoms) and asphalt (having approximately 35 carbon atoms and more), although these are usually processed by modern refineries into more valuable products as discussed below. The lighter molecules with four or fewer carbon atoms (e.g., methane), are typically found in the gaseous state at room temperature.
The cycloalkanes are also known as naphthenes and are saturated hydrocarbons which have one or more carbon rings to which hydrogen atoms are attached according to the formula CnH2n. Cycloalkanes have similar properties to alkanes but have higher boiling points.
The aromatic hydrocarbons are unsaturated hydrocarbons which have one or more planar six-carbon (benzene) rings to which hydrogen atoms are attached.
Although just about all fractions of petroleum find uses, the greatest demand is for gasoline and diesel. While the amount (weight percentage) of hydrocarbons in the crude oil samples which through a simple distillation ends up in gasoline and diesel varies widely depending upon the geographical source of the crude oil, typically, crude oil contains only 10-40% gasoline and 20-40% of diesel. Increasing gasoline and diesel yield from a particular crude oil sample may be done by cracking, i.e., breaking down large molecules of heavy heating oil and residues; reforming, i.e., changing molecular structures of low quality gasoline molecules; and isomerization, i.e., rearranging the atoms in a molecule so that the product has the same chemical formula but has a different structure, such as converting normal heptane to isoheptane.
Generally, the simplest refineries undertake first-run distillation that separates the crude oil into light (gas, naphtha and gasoline), middle (kerosene and diesel) and heavy (residual fuel oil) distillates. These simple refineries may include some hydrotreating capacity in order to remove sulfur, nitrogen, and unsaturated hydrocarbons (aromatics) from the distillates, and may also include some reforming capabilities. The next level of refinery complexity typically incorporates cracking capabilities and some additional hydrotreating in order to improve distillates quality; i.e., increasing the octane number for gasoline fractions and decreasing the sulfur content for gasoline and diesel. The most complex refineries add coking, and more hydrotreating and hydrocracking.
The catalytic cracking process utilizes elevated heat and pressure and optionally a catalyst to break or “crack” large hydrocarbon molecules into a range of smaller ones, specifically those used in gasoline and diesel components. In other words, the cracking produces light hydrocarbons from heavy hydrocarbons, for example, gasoline and kerosene from heavy residues. Typically, a mixture of gases (hydrogen, methane, ethane, ethylene) is also produced in cracking of heavy distillates. Likewise, a residual oil may be produced by the conventional cracking process.
Cracking of heavy hydrocarbons without a catalyst requires the use of high pressures and temperatures, e.g. pressures of 600-7000 kPa and temperatures of 500°-750° C. With a catalyst, the temperatures and pressures may be lower, e.g. 480°-530° C. and moderate pressure of about 60-200 kPa. However, even at these relatively lower temperatures and pressures, a separate unit must be built to accommodate the process.
During cracking the hydrocarbon molecules are broken up in a fairly random manner to produce mixtures of smaller hydrocarbons, some of which have carbon-carbon double bonds. A typical reaction involving the hydrocarbon might be:
CnHk=Cn−mHk−1+Cn−pHk−q+Cm+pHl+q
Catalytic cracking generally uses solid acids as the catalyst, particularly zeolites. Zeolites are complex aluminosilicates which are large lattices of aluminium, silicon and oxygen atoms carrying a negative charge which are typically associated with positive ions such as sodium ions. The heavy hydrocarbon (i.e., large molecule alkane) is brought into contact with the catalyst at a temperature of about 500° C. and moderately low pressures (e.g., 60-200 kPa). The zeolites used in catalytic cracking (e.g., ZSM-5, Y, and E) are chosen to yield high percentages of hydrocarbons with between 5 and 10 carbon atoms which are particularly useful for generating petrol (gasoline).
According to one aspect of the invention, metal or metal-oxide nanoparticles, or combinations of metal and metal-oxide nanoparticles are added to crude oil before initial distillation in order to increase the yield of light hydrocarbons obtained during initial distillation.
According to another aspect of the invention, metal or metal-oxide nanoparticles or combinations of metal and metal-oxide nanoparticles of characteristic size less than 90 nm are added to crude oil before initial distillation in order to increase the yield of light hydrocarbons obtained during initial distillation.
According to a further aspect of the invention, metal or metal-oxide nanoparticles or combinations of metal and metal-oxide nanoparticles are added to crude oil before initial distillation in a weight percentage of between 0.0004 and 0.02%, and more preferably in a weight percentage of between 0.001 and 0.01% in order to increase the yield of light hydrocarbons obtained during initial distillation.
According to an additional aspect of the invention nanoparticles of metals or metal-oxides, are mixed with zeolite micropowders and added to crude oil before initial distillation in order to increase the yield of light hydrocarbons obtained during initial distillation.
According to another aspect of the invention, nanoparticles of metals or metal-oxides, are mixed with nanoparticles of solid acids (e.g., zeolites or or halides) and added to crude oil before initial distillation in order to increase the yield of light hydrocarbons obtained during initial distillation.
According to yet another aspect of the invention, metal or metal-oxide nanoparticles are added to a crude oil residue after an initial to increase the yield of diesel oil in a second or later stage processing.
Turning now to
As described in more detail hereinafter, the nanoparticles utilized at step 10 have a characteristic size of less than 90 nm and are added in an amount such that they constitute a weight percentage of between 0.0004 and 0.02%, and more preferably in a weight percentage of between 0.001 and 0.01% of the crude oil/nanoparticle mixture. Also, as described in more detail hereinafter, the nanoparticles utilized at step 10 may be nanoparticles of metals, metal-oxides, a combination of metals and metal-oxides, or a combination of metals or metal-oxide nanoparticles and micropowders of solid acids such as zeolites or halides. The preferred size and preferred concentration of the nanoparticles utilized is believed to be at least partially dependent on the type or combinations of nanoparticles utilized.
Examples for Various Nanoparticles and Their Compositions.
Three different samples of crude oil were obtained. First portions of each sample were distilled as a control using a standard test method for distillation of petroleum products at atmospheric pressure (i.e., European Standard EN 228 and ASTM D2892-05 Standard Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column). The results of their distillation are presented in Table 1 below.
To test the method set forth in
Iron (Fe) nanoparticles (characteristic size of 43 nanometers) were added to second portions of the samples so that the iron nanoparticles constituted 0.004% by weight of the mixture. Upon distillation using the same procedure as the control, the yields of light hydrocarbons increased significantly over the yields of Table 1 (the controls) as set forth in Table 2 below.
Iron oxide nanoparticles (characteristic size of 20 nanometers) were added to third portions of the samples so that the iron oxide nanoparticles constituted 0.01% by weight of the mixture. Upon distillation using the same procedure as the control, the yields of light hydrocarbons increased significantly over the yields of Table 1 (the controls) as set forth in Table 3 below.
A mixture of nanoparticles of iron (characteristic size 43 nm) and zeolite Y micropowder (characteristic size of between 20 nm and 10 micrometers (10,000 nm) were added to seventh portions of the samples so that the iron nanoparticles constituted 0.001% by weight of the mixture and the zeolite Y constituted 0.01% of the mixture. Upon distillation using the same procedure as the control, the yields of light hydrocarbons increased significantly over the yields of Table 1 (the controls) as set forth in Table 4 below.
Based on the above examples, studies were conducted on different size nanoparticles. Thus, iron nanoparticles of different sizes were added in the amount 0.004% to various samples in order to determine yield and residue. Table 5 shows yields and residue resulting from adding seven different diameters of iron nanoparticles to crude oil and distilling as discussed above.
From Table 5, it is seen that iron nanoparticles of 43 nm provided the best result when added at an amount by weight of 0.004%. It is also interesting to note that when a control with no nanoparticles added to the sample was subjected to the distillation procedure, the yield of petrol and naphtha and diesel and the residue were exactly the same as when adding nanoparticles of 450 nm diameter (as seen by comparing Table 5 results above with the control of Table 8 below). Further, it is noted that nanoparticles of 110 nm diameter and of 17 nm provided little improvement over the control.
A similar size study was carried out with iron-oxide nanoparticles which were added to samples in the amount of 0.01%. As seen in Table 6, the use of larger size nanoparticles (i.e., 90 nm and larger) provided no ascertainable advantage. In addition, for iron-oxide, tests showed that the best results were obtained with 20 nm particles.
Yet another similar size study was carried out with cobalt-oxide nanoparticles which were added to samples in the amount of 0.01%. As seen in Table 7, the use of larger size nanoparticles (i.e., 140 nm and larger) provided no ascertainable advantage. In addition, for cobalt-oxide nanoparticles, tests showed that the best results were obtained with 2 nm particles.
Based on Examples 1-3 discussed above, and according to another aspect of the invention, additional studies were conducted where the concentration of a particularly-sized nanoparticle was varied and added to samples which were subjected to the distillation procedure, in order to determine the yield of petrol and naphtha and diesel and the residue. Table 8 provides results from a study conducted with different concentrations of iron nanoparticles of diameter 43 nm (±12 nm).
From Table 8, various conclusions may be drawn. First, adding iron nanoparticles of 43 nm size in as small an amount by weight fraction of 0.0004% provided an increase in light fraction yield, and adding the nanoparticles in an amount by weight fraction as small as 0.001% provided a significant increase in light fraction yield. Second, adding too many iron nanoparticles of 43 nm size does not increase yield at all and may actually decrease yield. Thus, when iron nanoparticles were added to the crude oil to constitute 0.02% by weight and then the crude oil was distilled, no improvement was seen, and when more iron nanoparticles were added, the resulting light fractions decreased. Thus, for iron nanoparticles of 43 nm size, a concentration range of 0.0004% to 0.015% by weight percentage provided an advantage, and the advantage was greatest between 0.002% and 0.01% (0.004% providing the best result).
A similar study on the effect of the nanoparticle concentration was conducted on 2 nm cobalt-oxide nanoparticles. Table 9 provides the results of adding different amounts of 2 nm cobalt-oxide nanoparticles to samples which were then subjected to the distillation procedure in order to determine the yield of petrol and naphtha and diesel and the residue.
From Table 9 it is seen that adding nanoparticles of cobalt-oxide having a diameter of 2 nm to crude oil such that the nanoparticles constitute a weight concentration in the range of 0.001% to 0.02% provided an advantage. The largest advantage was obtained with concentrations between 0.005% and 0.015% (with 0.01% providing the best result). In addition, it is noted that adding too much cobalt-oxide 2 nm nanoparticles (e.g., 0.05%) did not increase yield. Further, it is noted that the percentage range that provided improved results for the 2 nm cobalt-oxide nanoparticles (0.001 to 0.02) was not the same percentage range as provided improved results with 43 nm iron nanoparticles (0.0004 to 0.015). Thus, for a particular nanoparticle being utilized (e.g., iron, or iron-oxide, or cobalt-oxide or another metal or metal-oxide), desirable results depend not only on the size of the nanoparticles, but on the concentrations for that type of nanoparticle.
According to another aspect of the invention, it is believed that nanoparticles of the same composition but different sizes can be effectively utilized to increase light fraction yield. Thus, for example, 2 nm cobalt-oxide nanoparticles can be used in conjunction with 47 nm cobalt-oxide nanoparticles in suitable concentrations to increase the light fraction yield. Similarly, 7 nm iron nanoparticles can be used in conjunction with 43 nm iron nanoparticles in suitable concentrations to increase the light fraction yield.
According to another aspect of the invention, nanoparticles of two or more different compositions (e.g., different metals or different metal-oxides, or one or more metals and one or more metal-oxides) may be utilized together to increase light fraction yield. For example, 0.003% 43 nm iron nanoparticles were added to a crude oil sample together with 0.001% 2 nm cobalt-oxide nanoparticles, and the resulting fractions were 21% petrol and naphtha, 35% diesel and 44% residue. Comparing this result to Table 8, this result was better than the results obtained with just 0.003% 43 nm iron nanoparticles (17% petrol and naphtha, 34% diesel, and 49% residue), and comparing this result to Table 9, this result was better than the results obtained with just 0.001% 2 nm cobalt-oxide nanoparticles (14% petrol and naphtha, 24% diesel and 62% percent residue). However, this result was not better than the results obtained with 0.004% 43 nm iron nanoparticles.
As another example, 0.004% 43 nm iron nanoparticles were added to a crude oil sample together with 0.001% 2 nm cobalt-oxide, and the resulting fractions were 22% petrol and naphtha, 38% diesel, and 40% residue. Comparing this result to Table 8, this result was better than the results obtained with just 0.004% 43 nm iron nanoparticles (21% petrol and naphtha, 36% diesel, and 43% residue), and it was also better than the results obtained with 0.005% 43 nm iron nanoparticles (21% petrol and naphtha, 35% diesel, and 44% residue). Likewise, comparing this result to Table 9, this result was better than the results obtained with 0.001% 2 nm cobalt-oxide nanoparticles (14% petrol and naphtha, 24% diesel and 62% percent residue), and better than the results obtained with 0.005% 2 nm cobalt-oxide nanoparticles (16% petrol and naphtha, 27% diesel and 57% percent residue). Thus, adding cobalt-oxide nanoparticles to the “best” percentage of iron nanoparticles provided yet better results.
As another example, 0.002% 43 nm iron nonoparticles were added to a crude oil sample together with 0.001% 2 nm cobalt-oxide, and the resulting fractions were 19% petrol and naphtha, 40% diesel, and 41% residue. Comparing this result to Table 8, this result was better than the results obtained with just 0.002% 43 nm iron nanoparticles (16% petrol and naphtha, 34% diesel, and 50% residue), and it was also better than the results obtained with 0.003% 43 nm iron nanoparticles (17% petrol and naphtha, 34% diesel, and 49% residue). Likewise, comparing this result to Table 9, this result was better than the results obtained with 0.001% 2 nm cobalt-oxide nanoparticles (14% petrol and naphtha, 24% diesel and 62% percent residue).
According to another aspect of the invention, and based on Example 3 above, solid acid micropowders (20 nm<particle size<10 micrometers) were added with metal or metal-oxide nanoparticles. As seen in Table 10 below, use of the zeolites such as Faujasite (also known as Zeolite Y), Mordenite, and HZSM-5 (based on a zeolite synethic available from the Mobil Oil Company (ZSM)) significantly enhanced the yield of the light fractions. They also made the composition more stable. In addition, it is expected that other solid acids can be utilized.
Examples b, c, e, g, i and k of Table 10 are provided for comparative purposes. Thus comparing example a with examples b and c, it will be appreciated that the combination of 0.004% iron (43 nm) and 0.01% Zeolite Y provides a better result than just the iron nanoparticles or just the Zeolite Y micropowder. Similarly, comparing example d with examples b and e, it will be appreciated that the combination of 0.004% iron (43 nm) and 0.04% HZSM-5 zeolite provides a better result than just the iron nanoparticles (example b) or just the HZSM-5 zeolite micropowder (example e). Likewise, comparing example f with examples b and g, it will be appreciated that the combination of 0.004% iron (43 nm) and 0.02% Mordenite zeolite provides a better result than just the iron nanoparticles (example b) or just the Mordenite micropowder (example g). It is noted that example f provided the best yield of all of the examples. Also, comparing example h with examples c and i, it will be appreciated that the combination of 0.005% cobalt-oxide nanoparticles (2 nm) and 0.01% Zeolite Y micropowder provides a better result than just the 0.005% cobalt-oxide 2 nm nanoparticles (example i) or just the Zeolite Y micropowder (example c). Comparing example j with examples k and c, it will be appreciated that the combination of 0.01% cobalt-oxide nanoparticles (2 nm) and 0.01% Zeolite Y micropowder provides a better result than just the 0.01% cobalt-oxide 2 nm nanoparticles (example k) or just the 0.01 Zeolite Y micropowder (example c). Further, comparing example 1 to examples i and e, it will be appreciated that the combination of 0.005% cobalt-oxide nanoparticles (2 nm) and 0.04% HZSM-5 micropowder provides a better result than just the 0.005% cobalt-oxide 2 nm nanoparticles (example i) or just the 0.04% HZSM-5 micropowder (example e). In addition, comparing example m to examples k and e, it will be appreciated that the combination of 0.01% cobalt-oxide nanoparticles (2 nm) and 0.04% HZSM-5 micropowder provides a better result than just the 0.01% cobalt-oxide 2 nm nanoparticles (example k) or just the 0.04% HZSM-5 micropowder (example c). Comparing example n with examples i and g, it will be appreciated that the combination of 0.005% cobalt-oxide nanoparticles (2 nm) and 0.02% Mordenite micropowder provides a better result than just the 0.005% cobalt-oxide 2 nm nanoparticles (example i) or just the Mordenite micropowder (example g). Finally, comparing example o with examples k and g, it will be appreciated that the combination of 0.01% cobalt-oxide nanoparticles (2 nm) and 0.02% Mordenite micropowder provides a better result than just the 0.01% cobalt-oxide 2 nm nanoparticles (example k) or just the Mordenite micropowder (example g).
It will be appreciated by those skilled in the art that Table 10 is representative of just a few of the combinations that can be made, and that many other combinations of nanoparticles (metal, metal-oxide or combinations thereof) can be made with the same or different sizes and with the same or different zeolites, and that the percentages utilized of each can be changed.
It has been shown that the addition of metal or metal-oxide nanoparticles into the crude oil increases a resulting yield of light hydrocarbons (gasoline and diesel) during distillation. It is believed that the increased yield is due to catalytic low temperature cracking. It is believed that the addition of the metal or metal-oxide nanoparticles is environmentally benign. In addition, according to one aspect of the invention, the addition of the metal or metal-oxide nanoparticles into the crude oil helps prevent a corrosion of the distillation. It is noted that the addition of the metal or metal-oxide nanoparticles does effect the fractional composition of gasoline as it results in decreasing the benzene concentration in gasoline. The appears that benzene concentration is decreased due to the benzene alkylation reactions by low chain hydrocarbons catalyzed by Luis acid cites which are naturally present in the metal or metal-oxide nanoparticles. The addition of the metal or metal oxide nanoparticles also results in decreasing the sulfur contamination in the diesel fraction. The decrease in the sulfur contamination is believed caused by preferable catalytic breaks of the C—S bonds during catalytic cracking resulting in increasing the sulfur contamination in the residue.
Turning now to
According to another aspect of the invention, metal and/or metal-oxide nanoparticles, or metal and/or metal-oxide nanoparticles plus solid acid micropowders are added to a crude oil fraction that remains after initial distillation of the crude oil to remove gas, gasoline and optionally crude oil. The nanoparticles and solid acid micropowders are mixed into the remaining crude oil fraction before the crude oil fraction is subjected to additional distillation. Thus, as seen in
Using the method of
As seen in Table 11, by adding nanoparticles of a metal (e.g., 43 nm iron), or a metal-oxide (e.g., 20 nm iron-oxide), or a nanoparticles of a metal (e.g., 43 nm iron) plus a micropowder of solid acid (Mordenite) to a crude oil residue which had already had gasoline and diesel distilled out, and then subjecting the crude oil residue/nanoparticle or residue/nanoparticle/solid acid micropowder mixture to a distillation up to 340° C., significant additional amount of diesel is obtained. Also, as shown in Table 12 below, when the temperature was raised even further to 420° C., the increase in the yield of the diesel from the residue was extremely large.
At both temperatures (340° C. and 420° C.), the combination of 0.004% Fe, 43 nm, and 0.02% Mordenite micropowder provided the best results.
Based on the improved results shown in Tables 11 and 12, it is believed that even after a partial initial distillation, the addition to the residue of nanoparticles of different metals or metal-oxides, or combinations thereof, in different sizes and different amounts such as discussed above with reference to Tables 5-9 (but not limited thereto), will yield improved results. Likewise, it is believed that the additional of nanoparticles of different metals or metal-oxides, or combinations thereof, in further combination with micropowders of different solid acids such as discussed above with reference to Table 10 (but not limited thereto), will likewise yield improved results.
There have been described and illustrated herein several embodiments of methods for increasing the light fraction output of a crude oil distillation by adding nanoparticles of metals, metal-oxides, combinations thereof, or any of the same with solid acid micropowders. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while particular metals and metal-oxides have been disclosed, it will be appreciated that other metals and metal-oxides could be used as well. In addition, while particular types of solid acids have been disclosed, it will be understood that other solid acids can be used. Also, while certain ranges of concentrations of the metals and metal-oxides were described preferred, it will be recognized that other amounts could be utilized. Furthermore, while certain diameter nanoparticles were described, it will be understood that other diameter nanoparticles can be similarly used. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.
