Patent Application
20150322353
Various hydrocarbon streams, such as vacuum gas oil (VGO), light cycle oil (LCO), and naphtha, may be converted into higher value hydrocarbon fractions such as diesel fuel, jet fuel, naphtha, gasoline, and other lower boiling fractions in refining processes such as hydrocracking and fluid catalytic cracking (FCC). However, hydrocarbon feed streams for these materials often have high amounts of nitrogen which are more difficult to convert. For example, the degree of conversion, product yields, catalyst deactivation, and/or ability to meet product quality specifications may be adversely affected by the nitrogen content of the feed stream. It is known to reduce the nitrogen content of these hydrocarbon feed streams by catalytic hydrogenation reactions such as in a hydrotreating process unit. However, hydrogenation processes require high pressures and pressure
Various processes using ionic liquids to remove sulfur and nitrogen compounds from hydrocarbon fractions are also known. U.S. Pat. No. 7,001,504 discloses a process for the removal of organosulfur compounds from hydrocarbon materials which includes contacting an ionic liquid with a hydrocarbon material to extract sulfur containing compounds into the ionic liquid. U.S. Pat. No. 7,553,406 discloses a process for removing polarizable impurities from hydrocarbons and mixtures of hydrocarbons using ionic liquids as an extraction medium. U.S. Pat. No. 7,553,406 also discloses that different ionic liquids show different extractive properties for different polarizable compounds.
There remains a need in the art for improved processes that enable the removal of contaminants from hydrocarbon streams.
One aspect of the invention is process for removing a contaminant from a hydrocarbon stream. In one embodiment, the process includes contacting the hydrocarbon stream comprising the contaminant with a lean hydrocarbon-immiscible lactamium ionic liquid to produce a mixture comprising the hydrocarbon and a rich hydrocarbon-immiscible lactamium ionic liquid comprising at least a portion of the removed contaminant; and separating the mixture to produce a hydrocarbon effluent and a rich hydrocarbon-immiscible lactamium ionic liquid effluent comprising the rich hydrocarbon-immiscible lactamium ionic liquid. The hydrocarbon-immiscible lactamium ionic liquid comprises at least one of:
a reaction product of a lactam compound having a general formula
wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8,
and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide;
with the proviso that when n is 3, R is not hydrogen;
or
a reaction product of a lactam compound having a general formula
wherein the ring has at least one C—C double bond, R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8,
and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide;
or
a reaction product of a lactam compound having a general formula
wherein R is hydrogen or an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8, and the rings can be saturated or unsaturated;
and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide.
In general, the invention may be used to remove contaminants from a hydrocarbon stream using a lactamium based ionic liquid.
The hydrocarbon stream typically has a boiling point in the range of about 30° C. to about 525° C. Examples of hydrocarbon streams include, but are not limited to, at least one of vacuum gas oil streams, light cycle oil streams, naphtha streams, coker gas oil streams, kerosene streams, streams made from biorenewable sources, fracking condensate streams, streams from hydrocracking zones, streams from hydrotreating zones, and streams from fluid catalytic cracking zones.
The term “contaminant” means one or more species found in the hydrocarbon material that is detrimental to further processing. Contaminants include, but are not limited to, nitrogen, sulfur, metals (e.g., nickel, iron, and vanadium) and Conradson carbon residue or carbon residue. The metals content of such components, for example, may be in the range of 100 ppm to 2,000 ppm by weight or more, the total sulfur content may range from 0.1 to 7 wt %, the nitrogen content may be from about 40 ppm to 30,000 ppm, and the API gravity may range from about −5° to about 35°. The Conradson carbon residue of such components is generally less than 30 wt %.
The ionic liquid can remove one or more of the contaminants in the hydrocarbon feed. The hydrocarbon feed will usually comprise a plurality of nitrogen compounds of different types in various amounts. Thus, at least a portion of at least one type of nitrogen compound may be removed from the hydrocarbon feed. The same or different amounts of each type of nitrogen compound can be removed, and some types of nitrogen compounds may not be removed. In an embodiment, the nitrogen content of the hydrocarbon feed is reduced by at least about 3 wt %, at least about 5 wt %, or at least about 10 wt %, or at least about 15 wt %, at least about 20 wt %, or at least about 30 wt %, or at least about 40 wt %.
The hydrocarbon feed will typically also comprise a plurality of sulfur compounds of different types in various amounts. Thus, at least a portion of at least one type of sulfur compound may be removed from the hydrocarbon feed. The same or different amounts of each type of sulfur compound may be removed, and some types of sulfur compounds may not be removed. When the ionic liquid is made with a Brønsted acid only, there is little sulfur removal. More sulfur removal occurs when the ionic liquid anion contains a halometallate. In an embodiment, the sulfur content of the hydrocarbon feed is reduced by at least about 1 wt %, or at least about 2 wt %, or at least 3 wt %, or at least 5 wt %, or at least 10 wt %, or at least 20 wt %, or at least 30 wt %, or at least 35 wt %, or at least 40 wt %.
The hydrocarbon feed will usually contain various metals, including, but not limited to, nickel, iron, and vanadium. In an embodiment, the metal content of the hydrocarbon feed can be reduced by at least about 10% on an elemental basis, or at least about 20 wt %, or at least about 25 wt %, or at least about 30 wt %, or at least about 40 wt %, or at least about 50%. The metal removed may be part of a hydrocarbon molecule or complexed with a hydrocarbon molecule.
The nitrogen content may be determined using ASTM method D4629-02, Trace Nitrogen in Liquid Petroleum Hydrocarbons by Syringe/Inlet Oxidative Combustion and Chemiluminescence Detection. The sulfur content may be determined using ASTM method D5453-00, Ultraviolet Fluorescence. The metals content may be determined by UOP389-09, Trace Metals in Oils by Wet Ashing and ICP-OES. The Conradson carbon residue may be determined by ASTM D4530. Unless otherwise noted, the analytical methods used herein such as ASTM D5453-00 and UOP389-09 are available from ASTM International, 100 Barr Harbor Drive, West Conshohocken, Pa., USA.
Processes according to the invention remove contaminants from hydrocarbon streams. That is, the process removes at least one contaminant. It is understood that the hydrocarbon will usually comprise a plurality of contaminants of different types in various amounts. Thus, the process removes at least a portion of at least one type of contaminant. The process may remove the same or different amounts of each type of contaminant, and some types of contaminants may not be removed.
Lactamium base ionic liquids are used to extract one or more contaminants from the hydrocarbon stream. Lactamium based ionic liquids suitable for use in the instant invention are immiscible in the hydrocarbon stream being treated. As used herein the term “immiscible ionic liquid” means the formation of two phases that can be separated.
Lactam compounds can be converted to ionic liquids through reactions with strong acids followed by a second reaction with a metal halide if needed, as described in U.S. application Ser. No. ______, entitled Synthesis of Lactam Based Ionic Liquids, filed on even date herewith (Attorney Docket No. H0042599), and U.S. application Ser. No. ______, entitled Synthesis of N-Alkyl Lactam Based Ionic Liquids, filed on even date herewith (Attorney Docket No. H0042600), each of which is incorporated herein by reference.
The ionic liquids have a lactam cation. One type of lactamium based ionic liquid catalyst has the general formula:
wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, and X− is an anion group of a Brønsted acid HX or a halometallate; with the proviso that when n is 3, R is not hydrogen.
In one embodiment, when n is 3, X− is p-toluenesulfonate, and R is an alkyl group, the alkyl group has from 1 to 5 carbon atoms.
In one embodiment, when n is 3, X− is not a zinc halometallate.
Another way to represent this compound is:
wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, and X− is an anion group of a Brønsted acid HX or a halometallate.
Formula (I) is intended to cover both representations.
Another type of lactamium based ionic liquid has the general formula:
wherein the ring has at least one C—C double bond, R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, and X− is an anion group of a Brønsted acid HX or a halometallate.
The ring has at least one double bond. Larger rings may have more than one double bond. The double bond can be between any two adjacent carbons capable of forming a double bond.
Another way to represent this compound is
wherein the ring has at least one C—C double bond, R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, and X− is an anion group of a Brønsted acid HX or a halometallate.
Formula (II) is intended to cover both representations.
Examples of Formula (II) ionic liquids include, but are not limited to, 1,5-dihydro-pyrrol-2-one ionic liquids, 1,5-dihydro-1-methyl-2H-pyrrol-2-one based ionic liquids, 1,3-dihydro-2H-pyrrol-one ionic liquids, and 1,3-dihydro-1-methyl-2H-pyrrol-2-one based ionic liquids.
Another type of lactamium based ionic liquid has the general formula:
wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8, X− is an anion group of a Brønsted acid HX or a halometallate, and the rings can be saturated or unsaturated.
The heterocyclic ring (ring with n) can be saturated or unsaturated. The hydrocarbon ring (ring with m) can be saturated, unsaturated, or aromatic. If the ring is unsaturated, the C—C double bond can be between any two adjacent carbons capable of forming a double bond. There can be one or more C—C double bonds in either ring or in both rings.
Another way to represent this compound is
wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8, X− is an anion group of a Brønsted acid HX or a halometallate, and the rings can be saturated or unsaturated.
Formula (III) is intended to cover both representations.
Examples of Formula (III) ionic liquids include, but are not limited to, octahydro-2H-indol-2-one ionic liquids, octahydro-1-methyl-2H-indol-2-one based ionic liquids, and 2-oxindole ionic liquids, and 1,3-dihydro-1-methyl-2H-indol-2-one based ionic liquids.
Suitable X− groups include, but are not limited to, carboxylates, nitrates, phosphates, phosphinates, phosphonates, imides, cyanates, borates, sulfates (including bisulfates), sulfonates (including fluoroalkanesulfonates), acetates, halides, halometallates, and combinations thereof. Examples include, but are not limited to, following tetrafluoroborate, triflate, trifluoroacetate, chloroacetate, nitrate, hydrogen sulfate, hydrogen phosphate, dicyanoimide, methylsulfonate, and combinations thereof. Suitable halides include, but are not limited to, bromide, chloride, and iodide. Halometallates are mixtures of halides, such as bromide, chloride, and iodide, and metals. Suitable metals include, but are not limited to, Sn, Al Zn, Mn, Fe, Ga, Cu, Ni, and Co. In some embodiments, the metal is aluminum, with the mole fraction of aluminum ranging from 0<Al<0.25 in the anion. Suitable anions include, but are not limited to, AlCl4−, Al2Cl7−, Al3Cl10−, AlCl3Br−, Al2Cl6Br−, Al3Cl9Br−, AlBr4−, Al2Br7−, Al3Br10−, GaCl4−, Ga2Cl7−, Ga3Cl10−, GaCl3Br−, Ga2Cl6Br−, Ga3Cl9Br−, CuCl2−, Cu2Cl3−, Cu3Cl4−, ZnCl3−, FeCl3
In some embodiments when making a halometallate, the lactamium compound is reacted with a Brønsted acid HX, such as HCl, where X is a halide to form a lactam halide. The lactam halide is then reacted with a metal halide to form the lactam halometallate.
As is understood by those of skill in the art, the particular Brønsted acid used will depend on the anion desired. Suitable Brønsted acids include for example, sulfuric acid, p-toluenesulfonic acid, hydrochloric acid, hydrobromic acid, nitric acid, phosphoric acid, tetrafluoroboric acid, triflic acid, trifluoroacetic acid, chloroacetic acid, and methanesulfonic acid.
The lactamium ionic liquid comprises at least one of:
a reaction product of a lactam compound having a general formula
wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8;
and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide;
with the proviso that when n is 3, R is not hydrogen;
or
a reaction product of a lactam compound having a general formula
wherein the ring has at least one C—C double bond, R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8,
and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide;
or
a reaction product of a lactam compound having a general formula
wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8, and the rings can be saturated or unsaturated;
and a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide.
A lactamium based ionic liquid can be made by reacting a lactam compound having a general formula
wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, and n is 1 to 8;
with a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide.
Another lactamium based ionic liquid can be made by reacting a lactam compound having a general formula
wherein the ring has at least one C—C double bond, R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, and n is 1 to 8,
with a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide.
Another lactamium based ionic liquid can be made by reacting a lactam compound having a general formula
wherein R is hydrogen, an alkyl group having from 1 to 12 carbon atoms, an amine, an ether, or a silyl group, n is 1 to 8, m is 1 to 8, and the rings can be saturated or unsaturated;
with a Brønsted acid HX; or a Brønsted acid HX, where X is a halide, and a metal halide.
The heterocyclic ring (ring with n) can be saturated or unsaturated. The hydrocarbon ring (ring with in) can be saturated, unsaturated, or aromatic. If the ring is unsaturated, the C—C double bond can be between any two adjacent carbons capable of forming a double bond. There can be one or more C—C double bonds in either ring or in both rings.
The reaction can take place at temperatures in the range of about −36° C. to the decomposition temperature of the ionic liquid, or about −20° C. to less than the decomposition temperature of the ionic liquid, or about 0° C. to about 200° C., or about 0° C. to about 150° C., or about 0° C. to about 120° C., or about 20° C. to about 80° C.
The reaction typically takes place at atmospheric pressure, although higher or lower pressures could be used if desired.
When making halometallate compounds, the reaction should take place in an inert atmosphere.
The reaction typically takes about 1 min to multiple days, depending on the ionic liquid. Those made with the Brønsted acid typically take minutes to hours, while the halometallates typically take minutes to one or more days.
The reaction may be practiced in laboratory scale experiments through full scale commercial operations. The process may be operated in batch, continuous, or semi-continuous mode.
In some embodiments, the reaction can take place in the absence of a solvent. In other embodiments, it can take place in the presence of a solvent. The contacting can take place in the presence of one or more solvents. Suitable solvents for non-halometallate ionic liquids include, but are not limited to water, toluene, dichloromethane, liquid carboxylic acids such as acetic acid or propanoic acid, alcohols, such as methanol and ethanol, and combinations thereof. When water is used as the solvent, an additional product may form. The products can be separated using known separation techniques Non-protic solvents, such as dichloromethane, are suitable for use with halometallates.
The ratio of the Brønsted acid to the lactam compound is about 1:1 to about 3:1. In some embodiments, when making a halometallate using a Brønsted acid followed by the addition of a metal halide, the ratio of Brønsted acid to the lactam compound is about 1:1. In general, increasing the lactam:acid ratio increased the contaminant removal.
Consistent with common terms of art, the ionic liquid introduced to the contaminant removal step may be referred to as a “lean lactamium ionic liquid” generally meaning a hydrocarbon-immiscible lactamium ionic liquid that is not saturated with one or more extracted contaminants. Lean lactamium ionic liquid may include one or both of fresh and regenerated lactamium ionic liquid and is suitable for accepting or extracting contaminants from the hydrocarbon feed. Likewise, the lactamium ionic liquid effluent may be referred to as “rich lactamium ionic liquid”, which generally means a hydrocarbon-immiscible lactamium ionic liquid effluent produced by a contaminant removal step or process or otherwise including a greater amount of extracted contaminants than the amount of extracted contaminants included in the lean lactamium ionic liquid. A rich lactamium ionic liquid may require regeneration or dilution, e.g. with fresh lactamium ionic liquid, before recycling the rich lactamium ionic liquid to the same or another contaminant removal step of the process.
In an embodiment, the invention is a process for removing contaminants from a hydrocarbon feed stream comprising a contacting step and a separating step. In the contacting step, a hydrocarbon feed stream comprising a contaminant and a hydrocarbon-immiscible lactamium ionic liquid are contacted or mixed. The contacting may facilitate transfer or extraction of the one or more contaminants from the hydrocarbon feed stream to the lactamium ionic liquid. Although a lactamium ionic liquid that is partially soluble in the hydrocarbon may facilitate transfer of the contaminant from the hydrocarbon to the ionic liquid, partial solubility is not required. Insoluble hydrocarbon/lactamium ionic liquid mixtures may have sufficient interfacial surface area between the hydrocarbon and lactamium ionic liquid to be useful. In the separation step, the mixture of hydrocarbon and lactamium ionic liquid settles or forms two phases, a hydrocarbon phase and a lactamium ionic liquid phase, which are separated to produce a hydrocarbon-immiscible lactamium ionic liquid effluent and a hydrocarbon effluent.
The process may be conducted in various equipment which is well known in the art and is suitable for batch or continuous operation. For example, in a small scale form of the invention, hydrocarbon and a hydrocarbon-immiscible lactamium ionic liquid may be mixed in a beaker, flask, or other vessel, e.g., by stirring, shaking, use of a mixer, or a magnetic stirrer. The mixing or agitation is stopped and the mixture forms a hydrocarbon phase and a lactamium ionic liquid phase which can be separated, for example, by decanting, centrifugation, or use of a pipette to produce a hydrocarbon effluent having a lower contaminant content relative to the incoming hydrocarbon. The process also produces a hydrocarbon-immiscible lactamium ionic liquid effluent comprising the one or more contaminants.
The contacting and separating steps may be repeated, for example, when the contaminant content of the hydrocarbon effluent is to be reduced further to obtain a desired contaminant level in the ultimate hydrocarbon product stream from the process. Each set, group, or pair of contacting and separating steps may be referred to as a contaminant removal step. Thus, the invention encompasses single and multiple contaminant removal steps. A contaminant removal zone may be used to perform a contaminant removal step. As used herein, the term “zone” can refer to one or more equipment items and/or one or more sub-zones. Equipment items may include, for example, one or more vessels, heaters, separators, exchangers, conduits, pumps, compressors, and controllers. Additionally, an equipment item can further include one or more zones or sub-zones. The contaminant removal process or step may be conducted in a similar manner and with similar equipment as is used to conduct other liquid-liquid wash and extraction operations. Suitable equipment includes, for example, columns with: trays, packing, rotating discs or plates, and static mixers. Pulse columns and mixing/settling tanks may also be used.
The contact step can take place at a temperature in the range of about 20° C. to the decomposition temperature of the lactamium based ionic liquid, or about 20° C. to about 120° C., or about 20° C. to about 80° C.
The contacting time is sufficient to obtain good contact between the lactamium based ionic liquid and the hydrocarbon feed. The contacting time is typically in the range of about 1 min to about 1 hr, or about 5 min to about 30 min.
An optional hydrocarbon washing step may be used, for example, to recover lactamium ionic liquid that is entrained or otherwise remains in the hydrocarbon effluent stream by using water to wash or extract the ionic liquid from the hydrocarbon effluent. In this embodiment, a portion or all of hydrocarbon effluent stream 6 (as feed) and a water stream 12 (as solvent) are introduced to hydrocarbon washing zone 400. The hydrocarbon effluent and water streams introduced to hydrocarbon washing zone 400 are mixed and separated to produce a washed hydrocarbon stream 14 and a spent water stream 16, which comprises the lactamium ionic liquid. The hydrocarbon washing step may be conducted in a similar manner and with similar equipment as used to conduct other liquid-liquid wash and extraction operations as discussed above. Various hydrocarbon washing step equipment and conditions such as temperature, pressure, times, and solvent to feed ratio may be the same as or different from the contaminant removal zone equipment and conditions. In general, the hydrocarbon washing step conditions will fall within the same ranges as given below for the contaminant removal step conditions. A portion or all of the washed hydrocarbon stream 14 may be passed to hydrocarbon conversion zone 800.
An optional lactamium ionic liquid regeneration step may be used, for example, to regenerate the ionic liquid by removing the contaminant from the ionic liquid, i.e. reducing the contaminant content of the rich lactamium ionic liquid. In an embodiment, a portion or all of hydrocarbon-immiscible lactamium ionic liquid effluent stream 8 (as feed) comprising the contaminant and a regeneration solvent stream 18 are introduced to ionic liquid regeneration zone 500. The hydrocarbon-immiscible lactamium ionic liquid effluent stream 8 and regeneration solvent stream 18 are mixed and separated to produce an extract stream 20 comprising the contaminant, and a regenerated lactamium ionic liquid stream 22. The lactamium ionic liquid regeneration step may be conducted in a similar manner and with similar equipment as used to conduct other liquid-liquid wash and extraction operations as discussed below. Various lactamium ionic liquid regeneration step conditions such as temperature, pressure, times, and solvent to feed may be the same as or different from the contaminant removal conditions. In general, the ionic liquid regeneration step conditions will fall within the same ranges as given below for the contaminant removal step conditions.
In an embodiment, the regeneration solvent stream 18 comprises a hydrocarbon fraction lighter than the hydrocarbon and which is immiscible with the lactamium ionic liquid. The lighter hydrocarbon fraction may consist of a single hydrocarbon compound or may comprise a mixture of hydrocarbons. In an embodiment, the lighter hydrocarbon fraction comprises at least one of a naphtha, gasoline, diesel, light cycle oil (LCO), and light coker gas oil (LCGO) hydrocarbon fraction. The lighter hydrocarbon fraction may comprise straight run fractions and/or products from conversion processes such as hydrocracking, hydrotreating, fluid catalytic cracking (FCC), reforming, coking, and visbreaking. In this embodiment, extract stream 20 comprises the lighter hydrocarbon regeneration solvent and the contaminant. In another embodiment, the regeneration solvent stream 18 comprises water, and the ionic liquid regeneration step produces extract stream 20 comprising the contaminant and regenerated hydrocarbon-immiscible lactamium ionic liquid 22 comprising water and the lactamium ionic liquid. In an embodiment wherein regeneration solvent stream 18 comprises water, a portion or all of spent water stream 16 may provide a portion or all of regeneration solvent stream 18. Regardless of whether regeneration solvent stream 18 comprises a lighter hydrocarbon fraction or water, a portion or all of regenerated hydrocarbon-immiscible lactamium ionic liquid stream 22 may be recycled to the contaminant removal step via a conduit not shown consistent with other operating conditions of the process. For example, a constraint on the water content of the hydrocarbon-immiscible lactamium ionic liquid stream 4 or the lactamium ionic liquid/hydrocarbon mixture in contaminant removal zone 100 may be met by controlling the proportion and water content of fresh and recycled ionic liquid streams
Optional ionic liquid drying step is illustrated by drying zone 600. The ionic liquid drying step may be employed to reduce the water content of one or more of the streams comprising ionic liquid to control the water content of the contaminant removal step as described above. In the embodiment of
Separation vessel 165 may contain a solid media 175 and/or other coalescing devices which facilitate the phase separation. In other embodiments, the separation zone 300 may comprise multiple vessels which may be arranged in series, parallel, or a combination thereof. The separation vessels may be of any shape and configuration to facilitate the separation, collection, and removal of the two phases. In a further embodiment, contaminant removal zone 100 may include a single vessel wherein lean lactamium ionic liquid stream 4 and hydrocarbon feed stream 2 are mixed, then remain in the vessel to settle into the hydrocarbon effluent and rich lactamium ionic liquid phases.
In an embodiment, the process comprises at least two contaminant removal steps. For example, the hydrocarbon effluent from one contaminant removal step may be passed directly as the hydrocarbon feed to a second contaminant removal step. In another embodiment, the hydrocarbon effluent from one contaminant removal step may be treated or processed before being introduced as the hydrocarbon feed to the second contaminant removal step. There is no requirement that each contaminant removal zone comprises the same type of equipment. Different equipment and conditions may be used in different contaminant removal zones.
The contaminant removal step may be conducted under contaminant removal conditions including temperatures and pressures sufficient to keep the hydrocarbon-immiscible lactamium ionic liquid and hydrocarbon feeds and effluents as liquids. For example, the contaminant removal step temperature may range between about 10° C. and less than the decomposition temperature of the lactamium ionic liquid, and the pressure may range between about atmospheric pressure and about 700 kPa(g). When the hydrocarbon-immiscible ionic liquid comprises more than one lactamium ionic liquid component, the decomposition temperature of the lactamium ionic liquid is the lowest temperature at which any of the lactamium ionic liquid components decompose. The contaminant removal step may be conducted at a uniform temperature and pressure or the contacting and separating steps of the contaminant removal step may be operated at different temperatures and/or pressures. In an embodiment, the contacting step is conducted at a first temperature, and the separating step is conducted at a temperature at least 5° C. lower than the first temperature. In a non-limiting example, the first temperature is about 80° C. Such temperature differences may facilitate separation of the hydrocarbon and lactamium ionic liquid phases.
The above and other contaminant removal step conditions such as the contacting or mixing time, the separation or settling time, and the ratio of hydrocarbon feed to hydrocarbon-immiscible lactamium ionic liquid (lean lactamium ionic liquid) may vary greatly based, for example, on the specific lactamium ionic liquid or liquids employed, the nature of the hydrocarbon feed (straight run or previously processed), the contaminant content of the hydrocarbon feed, the degree of contaminant removal required, the number of contaminant removal steps employed, and the specific equipment used. In general, it is expected that contacting time may range from less than one minute to about two hours; settling time may range from about one minute to about eight hours. The weight ratio of hydrocarbon feed to lean lactamium ionic liquid introduced to the contaminant removal step may range from about 1:10,000 to about 10,000:1, or about 1:1,000 to about 1,000:1, or about 1:100 to about 100:1, or about 1:20 to about 20:1, or about 1:10 to about 10:1. In an embodiment, the weight of hydrocarbon feed is greater than the weight of lactamium ionic liquid introduced to the contaminant removal step.
In an embodiment, a single contaminant removal step reduces the contaminant content of the hydrocarbon by more than about 10 wt %, or more than about 20 wt %, or more than about 30 wt %, or more than about 40 wt %, or more than about 50 wt %, or more than about 60 wt %, or more than about 70 wt %, or more than about 75 wt %, or more than about 80 wt %, or more than about 85 wt %, or more than about 90 wt %. As discussed herein, the invention encompasses multiple contaminant removal steps to provide the desired amount of contaminant removal.
The degree of phase separation between the hydrocarbon and lactamium ionic liquid phases is another factor to consider as it affects recovery of the lactamium ionic liquid and hydrocarbon. The degree of contaminant removed and the recovery of the hydrocarbon and lactamium ionic liquid may be affected differently by the nature of the hydrocarbon feed, the variations in the specific lactamium ionic liquid or liquids, the equipment, and the contaminant removal conditions such as those discussed above.
The amount of water present in the hydrocarbon/hydrocarbon-immiscible lactamium ionic liquid mixture during the contaminant removal step may also affect the amount of contaminant removed and/or the degree of phase separation, i.e., recovery of the hydrocarbon and lactamium ionic liquid. In an embodiment, the hydrocarbon/hydrocarbon-immiscible lactamium ionic liquid mixture has a water content of less than about 10% relative to the weight of the lactamium ionic liquid, or less than about 5% relative to the weight of the lactamium ionic liquid, or less than about 2% relative to the weight of the ionic liquid. In a further embodiment, the hydrocarbon/hydrocarbon-immiscible lactamium ionic liquid mixture is water free, i.e., the mixture does not contain water.
Unless otherwise stated, the exact connection point of various inlet and effluent streams within the zones is not essential to the invention. For example, it is well known in the art that a stream to a distillation zone may be sent directly to the column, or the stream may first be sent to other equipment within the zone such as heat exchangers, to adjust temperature, and/or pumps to adjust the pressure. Likewise, streams entering and leaving contaminant removal, washing, and regeneration zones may pass through ancillary equipment such as heat exchanges within the zones. Streams, including recycle streams, introduced to washing or extraction zones may be introduced individually or combined prior to or within such zones.
The invention encompasses a variety of flow scheme embodiments including optional destinations of streams, splitting streams to send the same composition, i.e. aliquot portions, to more than one destination, and recycling various streams within the process. Examples include: various streams comprising ionic liquid and water may be dried and/or passed to other zones to provide all or a portion of the water and/or ionic liquid required by the destination zone. The various process steps may be operated continuously and/or intermittently as needed for a given embodiment e.g. based on the quantities and properties of the streams to be processed in such steps. As discussed above the invention encompasses multiple contaminant removal steps, which may be performed in parallel, sequentially, or a combination thereof. Multiple contaminant removal steps may be performed within the same contaminant removal zone and/or multiple contaminant removal zones may be employed with or without intervening washing, regeneration and/or drying zones.
By the term “about,” we mean within 10% of the value, or within 5%, or within 1%.
The example is presented to further illustrate some aspects and benefits of the invention and is not to be considered as limiting the scope of the invention.
A LCO feed containing 597 ppm nitrogen was added to caprolactamium hydrogen sulfate ionic liquid in a 10:1 ratio of LCO feed:ionic liquid. The mixture was stirred at room temperature. After 1 hr, the stirring was stopped, and the LCO feed and the ionic liquid were allowed to separate. The LCO feed was decanted away from the ionic liquid layer. The experiment was repeated at different molar ratios of caprolactam:acid.
The experiments were repeated using a naphtha feed containing 49 ppm nitrogen.
The results are shown in Table 1.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.
