Patent Description:
<CIT> discloses methods for operating a hydrocracking process for long on-stream periods under reasonable operating conditions without intolerable increases in catalyst fouling rates while maintaining the hydrocracking catalyst in a regenerable condition.

PNAs are aromatic hydrocarbons having <NUM> or more (preferably <NUM> to <NUM>) aromatic rings. There is a need to upgrade streams with an appreciable concentration of PNA (e.g., greater than <NUM> wt% PNA). Examples of such streams include steam cracker tar (the <NUM>+°F (<NUM>+°C) distillation bottoms produced from naphtha and vacuum gas oil steam cracking), FCC main column bottoms (MCB) (the <NUM>+°F (<NUM>+°C) distillation bottoms produced from refinery fluid catalytic crackers), coal tar (the <NUM>+°F (<NUM>+°C) distillation bottoms produced from steel industry coke ovens), coker tar (the <NUM>+°F (<NUM>+°C) bottoms produced from delayed, fluid, and flexicokers), and heavy oil tar (the <NUM>+°F (<NUM>+°C) bottoms produced by vacuum distillation of heavy oil). As used herein, the abbreviation of n°F+ refers to a composition being composed of components having a boiling point of n°F or greater. The most important single heavy oil resource is Canadian heavy oil or Canadian tar sands.

PNA is not soluble in waxy saturated hydrocarbons under traditional hydrocracking conditions, so PNA precipitates in refining processes, which plugs up machinery and cokes the catalyst. Accordingly, PNA concentrations in feedstocks for hydrocracking are limited to ppm levels. As a result, there is no economic pathway today to upgrade streams with appreciable concentrations of PNA into amounts of clean fuel products with any significant efficacy or efficiency. Most of these streams today are coked. Accordingly, by the time the tar or other starting material has been fully refined, over <NUM> wt% has been downgraded to coke and C<NUM>- paraffins.

The present disclosure relates to upgrading refining streams with high polynucleararomatic hydrocarbon (PNA) concentrations.

A method outside of the present invention can comprise: hydrocracking a PNA feed in the presence of a catalyst and hydrogen at <NUM> to <NUM>, <NUM> psig (<NUM> MPa) or greater, and <NUM> hr-<NUM> to <NUM> hr-<NUM> liquid hourly space velocity (LSHV), wherein the weight ratio of PNA feed to hydrogen is <NUM>:<NUM> to <NUM>:<NUM>, wherein the PNA feed comprises <NUM> wt% or less of hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and having an aromatic content of <NUM> wt% or greater to form a product comprising <NUM> wt% or greater of the hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and having an aromatic content of <NUM> wt% or less.

The invention is a method as defined in claim <NUM>.

The following figures are included to illustrate certain aspects of the embodiments, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure.

The present invention relates to upgrading streams with appreciable amounts of PNA to produce valuable hydrocarbons like liquid petroleum gas (LPG), gasoline, and ultralow sulfur diesel (ULSD) in a single stage or, preferably, a two-stage hydrocracking reactor. More specifically, the PNA feed stream is hydrocracked under conditions that facilitate solvency of the PNA and other components in the stream.

As used herein, the terms "polynucleararomatic hydrocarbon" and "PNA" refer to hydrocarbons comprising fused aromatic rings that can optionally have side chains.

As used herein, the terms "polyaromatic hydrocarbon" and "PAH" refer to PNAs without any side chains. PAHs are a subclass of PNAs.

Without being limited by theory, PNA is highly insoluble in <NUM>+ blends of paraffins, isoparaffins, and <NUM>-<NUM> ring naphthenes, but are soluble in aromatic cosolvents like long sidechain branched, <NUM>-<NUM> ring aromatics. Conventional hydrocracking technology selectively reacts away the aromatic cosolvents into either (a) a lower boiling range by cracking or (b) <NUM>-<NUM> ring naphthenes by aromatic hydrogenation reactions. Conventional hydrocracking catalysts simultaneously catalyze the production of high MW PNA and methyl and ethyl substituted PNAs. At high conversions, the PNA's precipitate into high viscosity sticky liquids or directly onto catalyst and equipment surfaces. Even ppm quantities of PNA precipitation can cause catastrophic catalyst and equipment failure within hours.

Generally, it is widely believed in the refining community that upgrading <NUM>-ring aromatics like phenanthrene and anthracene to full saturation is not thermodynamically possible in the presence of <NUM>+-aromatics. Further, it is widely held that the PNAs will coke under hydrocracking conditions. Additionally, the catalyst activity is believed to be insufficient for appreciable upgrading of <NUM>+-ring aromatics. The process of the invention avoids this problem by controlling the feedstock, the catalyst, and the conditions in the reactor to maximize reaction medium solvency, minimize PNA production, and prevent PNA precipitation.

Regarding controlling the feedstock, the solvency of the components of the feedstock are considered. The solvency criterion of Wiehe (Wiehe and Kennedy, 2000a) requires titration of the individual oils with a model solvent (e.g., toluene) and a model non-solvent (e.g., n-heptane). This enables measuring the solubility parameter of the mixture at which PNAs precipitate. This solubility parameter on a reduced n-heptane-toluene scale is called the insolubility number (IN). In addition, the tests measure the solubility parameter of the oil that on a reduced n-heptane-toluene scale is called the solubility blending number (SBN). The criterion for solvency of any blend is that the volume average solubility blending number is greater than the maximum insolubility number of any component in the blend.

In order to mitigate PNA precipitation, an insolubility number (IN) and a solvent blend number (SBN) are determined for the components of the feedstock. Optionally, a solvent can be used to achieve the IN and SBN of the feedstock that mitigates PNA precipitation. Successful blending can be accomplished with little or substantially no precipitation by combining the components in order of decreasing SBN, so that the SBN of the blend is greater than the IN of any component of the blend. <CIT>, incorporated herein by reference, describes the method of calculating IN and SBN.

PNA feed streams can have a SBN greater than <NUM> and a IN greater than <NUM>. Examples of PNA feed streams include, but are not limited to, steam cracker tar (the <NUM>+°F (<NUM>+°C) distillation bottoms produced from naphtha and vacuum gas oil steam cracking), FCC main column bottoms (MCB) (the <NUM>+°F (<NUM>+°C) distillation bottoms produced from refinery fluid catalytic crackers), coal tar (the <NUM>+°F (<NUM>+°C) distillation bottoms produced from steel industry coke ovens), heavy oil tar (the <NUM>+°F (<NUM>+°C) bottoms produced by vacuum distillation of heavy oil), and the like.

Solvents preferably are rich in aromatics, sulfur, and nitrogen. Solvents can have a SBN of <NUM> to <NUM> and a IN of less than <NUM>. Examples of solvents include, but are not limited to, <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point hydrocarbons, light cycle oils, extracts, naphthenic oils, and the like.

Further, the solvent preferably maintains the liquid phase in the hydrocracking reactor at a reasonably low viscosity. If too much <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point hydrocarbons are removed in the process, the liquid film thickness in the reactor will increase, and the catalyst will coke rapidly.

Regarding the reactor conditions used to maximize reaction medium solvency and minimize PNA production, the conditions are maintained to facilitate kinetic control over the reaction. That is, the diffusion of the reactive molecules is faster than the reaction, which speeds up the desired reactions. One such condition regulated is pressure. Higher pressure shifts the reaction equilibrium toward aromatic saturation, which lowers the concentration of PNA precursors and accelerates the hydrodenitrogenation reactions. The hydrodenitrogenation reactions prevent the formation of nitrogen-containing PNAs.

Additionally, the gas treat rate is preferably high in the reactor because the more gas in the reactor, the more light liquids are stripped from the liquid phase. Without being limited by theory, molecules below their critical temperatures dissolved in liquids have a disproportionate impact on the solvency of the liquid. For example, naphthalene has a critical temperature of <NUM> and propylbenzene has a critical temperature of <NUM>. The instant invention operates preferably between <NUM> and <NUM>. High levels of low molecular weight dissolved molecules dramatically reduce solubility. High gas treat rates keep molecules with critical temperatures below the reaction temperature largely in the gas phase in the reactor.

Further, a low liquid hourly space volume (LHSV) when operating the hydrocracking reactor minimizes the diffusion limitations and keep start of cycle temperature down.

Regarding the catalyst to maximize reaction medium solvency and minimize PNA production, the catalyst preferably has large pores to facilitate diffusion of the reactive molecules. Further, in some instances, a series of stacked catalyst beds are used to control the reaction progression as the feed passes through the reactor. For example, cracking reactions can be minimized until after the nitrogen and sulfur have been removed and the bulk of the aromatics are saturated by ordering the catalyst beds appropriately. This minimizes the concentration of PNA precursors exposed to the hydrocracking catalyst.

<FIG> is an illustrative diagram of an example process <NUM> outside of the present invention. A hydrocracking unit <NUM> includes a hydrocracking reactor and downstream separator. The hydrocracking reactor receives a PNA feed stream <NUM>, optionally a solvent stream <NUM>, and a hydrogen stream <NUM>. Each stream may be introduced to the hydrocracking reactor separately, or two or more may be mixed before introduction to the hydrocracking reactor.

As used herein, when a compositional term modifies "stream," the stream comprises that composition. The compositional term does not indicate that the stream consists of only that composition. For example, a PNA feed stream is a stream that comprises PNA and does not necessarily consist only of PNA. Further, the compositional term does not indicate a certain minimum concentration of the composition in the stream. For example, a PNA feed stream can comprise <NUM> mol% PNA or less.

The hydrocracking reactor contains one or more catalysts that catalyze the cracking of the components in the PNA feed stream. The product is then transported to the separator (e.g., an atmospheric or vacuum distillation unit) where it is separated by boiling point into several product streams <NUM>-<NUM>. The composition and relative concentration of each product stream <NUM>-<NUM> depends on the composition of the PNA feed stream <NUM>, the catalysts used, and the distillation parameters. Examples of product streams <NUM>-<NUM> include, but are not limited to, C<NUM>- paraffins, gasoline, ULSD, base stock oil, H<NUM>S gas, and the like.

The hydrocracking can convert <NUM> wt% or greater (e.g., <NUM> wt% to <NUM> wt%) of the <NUM>-ring aromatics in the PNA feed stream to saturates, or alternatively <NUM> wt% or greater of the <NUM>-ring aromatics in the PNA feed stream to saturates, or alternatively <NUM> wt% or greater of the <NUM>-ring aromatics in the PNA feed stream to saturates.

<FIG> is an illustrative diagram of an example process 20C outside of the present invention that upgrades streams with appreciable amounts of PNA. This example upgrades the vacuum residue from tar sand refining. A hydrogen stream <NUM> is entrained with a feed stream <NUM> comprising vacuum residue from tar sand refining, which is then fed into a hydroprocessing reactor <NUM> (e.g., a fixed bed hydroprocessing reactor). The product <NUM> is then transported to a separation unit <NUM> for separation (e.g., by distillation) into several product streams <NUM>-<NUM>. Examples of such streams include, but are not limited to, an H<NUM>S gas stream <NUM>, a C<NUM>- paraffins stream <NUM>, a naphtha stream <NUM>, a <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point stream <NUM> (or a distillate stream <NUM>), and a <NUM>+°F (<NUM>+°C) boiling point stream <NUM>. The bottoms, which in this example is <NUM>+°F (<NUM>+°C) boiling point stream <NUM>, is transported to a fluid catalytic cracking (FCC) reactor <NUM>. In the fluid catalytic cracking reactor, the components of stream <NUM> are converted to lower boiling hydrocarbons suitable for use as fuels. The resultant product <NUM> is then transported to a separation unit <NUM> for separation (e.g., by distillation) into several product streams <NUM>-<NUM>. Examples of such streams include, but are not limited to, a C<NUM>- paraffins stream <NUM>, an ethylene stream <NUM>, a propylene stream <NUM>, a butenes stream <NUM>, a gasoline stream <NUM>, a liquid cycle oil stream <NUM>, and a main column bottoms stream <NUM>.

In a traditional operation, the main column bottoms stream <NUM> is used for making high sulfur heavy aromatic fuel oil (HAFO). In contrast, this method uses the main column bottoms stream <NUM> as a PNA feed stream and the liquid cycle oil stream <NUM> as a solvent stream as feed for hydrocracking. The main column bottoms stream <NUM> and the liquid cycle oil stream <NUM> along with a hydrogen stream <NUM> are fed to a hydrocracking reactor <NUM>. The hydrogen and liquid cycle oil act as solvents for the main column bottoms. Two or more of these three streams <NUM>, <NUM>, <NUM> can be mixed before entry into the hydrocracking reactor <NUM>. Alternatively, each stream <NUM>, <NUM>, <NUM> can enter the hydrocracking reactor <NUM> separately. The hydrocracking process produces a product stream <NUM> that is separated in separation unit <NUM>. In this example, the separation unit <NUM> produces a H<NUM>S stream <NUM>, a LPG stream <NUM>, a gasoline stream <NUM>, and a ULSD stream <NUM>. The separation unit <NUM> can be designed for other product streams.

<FIG> is an illustrative diagram of another example process <NUM> outside of the present invention that upgrades streams with appreciable amounts of PNA. This example upgrades the vacuum residue (feed) from tar sand refining. A hydrogen stream <NUM> is entrained with a feed stream <NUM> comprising vacuum residue from tar sand refining, which is then fed into a slurry hydrocracking reactor <NUM>. The product <NUM> is then transported to a separation unit <NUM> for separation (e.g., by distillation) into several product streams <NUM>-<NUM>. Examples of such streams include, but are not limited to, an H<NUM>S gas stream <NUM>, a C<NUM>- paraffins stream <NUM>, a naphtha stream <NUM>, a <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point stream <NUM>, and a <NUM>+°F (<NUM>+°C ) boiling point stream <NUM>. The bottoms, which in this example is <NUM>+°F (<NUM>+°C) boiling point stream <NUM>, is transported to a solvent assisted hydroprocessing reactor <NUM>. A hydrogen stream <NUM> is also fed into the solvent assisted hydroprocessing reactor <NUM>. In the solvent assisted hydroprocessing reactor <NUM>, the components of stream <NUM> and hydrogen stream <NUM> are converted to lower boiling hydrocarbons suitable for use as fuels. The resultant product <NUM> is then transported to a separation unit <NUM> for separation (e.g., by distillation) into several product streams <NUM>-<NUM>. Examples of such streams include, but are not limited to, a H<NUM>S stream <NUM>, a C<NUM>- paraffins stream <NUM>, a gasoline stream <NUM>, a <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point stream <NUM>, a <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point stream <NUM>, and a <NUM>°F+ (<NUM>+°C) boiling point stream <NUM>.

In a traditional operation, the <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point stream <NUM> is used for making HAFO. In contrast, this process uses the <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point stream <NUM> as a PNA feed stream and the <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point stream <NUM> as a solvent stream as feed for hydrocracking. The <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point stream <NUM> and the <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point stream <NUM> along with a hydrogen stream <NUM> are fed to a hydrocracking reactor <NUM>. The hydrogen and <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point product act as solvents for the <NUM>°F (<NUM>) to <NUM>°F (<NUM>) boiling point product. Two or more of these three streams <NUM>, <NUM>, <NUM> can be mixed before entry into the hydrocracking reactor <NUM>. Alternatively, each stream <NUM>, <NUM>, <NUM> can enter the hydrocracking reactor <NUM> separately. The hydrocracking process produces a product stream <NUM> that is separated in separation unit <NUM>. In this example, the separation unit <NUM> produces a LPG stream <NUM>, a gasoline stream <NUM>, and a ULSD stream <NUM>. The separation unit <NUM> can be designed for other product streams.

<FIG> is an illustrative diagram of yet another example process <NUM> outside of the present invention that upgrades streams with appreciable amounts of PNA. Feed stream <NUM> is distilled in separator <NUM> to produce a vacuum residue <NUM> stream and a vacuum gas oil stream <NUM>. The vacuum residue <NUM> stream is deasphalted in a deasphalting unit <NUM> to produce deasphalted oil <NUM> and rock <NUM>. The rock <NUM> is treated by slurry hydrocracking in hydrocracker <NUM> in the presence of hydrogen <NUM> to produce a product stream <NUM> and an H<NUM>S stream <NUM>. The product stream <NUM> from the hydrocracker <NUM> is fed to the separator <NUM>. The deasphalted oil <NUM> is hydroprocessed in a hydroprocessing unit <NUM> (e.g., a fixed bed hydroprocessing unit) to produce a H<NUM>S stream <NUM>, a C<NUM>- paraffin stream <NUM>, and a <NUM>+°F (<NUM>+°C) stream <NUM>. The <NUM>+°F (<NUM>+°C) stream <NUM> is entrained with the vacuum gas oil stream <NUM> to produce a mixed stream <NUM> that is fed to the fluid catalytic cracking (FCC) unit <NUM>. The products of the FCC unit <NUM> are fed to the separator <NUM>. The product stream <NUM> from the hydrocracker <NUM> and the mixed stream <NUM> are separated (e.g., via distillation) in the separator <NUM> to produce a plurality of product streams <NUM>-<NUM>. Examples of such streams include, but are not limited to, a C<NUM>- paraffins stream <NUM>, an ethylene stream <NUM>, a propylene stream <NUM>, a butenes stream <NUM>, a gasoline stream <NUM>, a liquid cycle oil stream <NUM>, and a main column bottoms stream <NUM>.

In a traditional operation, the main column bottoms stream <NUM> is used for making heavy aromatic fuel oil (HAFO). In contrast, this process uses the main column bottoms stream <NUM> as a PNA feed stream and the liquid cycle oil stream <NUM> as a solvent stream as feed for hydrocracking. The main column bottoms stream <NUM> and the liquid cycle oil stream <NUM> along with a hydrogen stream <NUM> are fed to a hydrocracking reactor <NUM>. The hydrogen and liquid cycle oil act as solvents for the main column bottoms. Two or more of these three streams <NUM>, <NUM>, <NUM> can be mixed before entry into the hydrocracking reactor <NUM>. Alternatively, each stream <NUM>, <NUM>, <NUM> can enter the hydrocracking reactor <NUM> separately. The hydrocracking process produces a product stream <NUM> that is separated in separation unit <NUM>. In this example, the separation unit <NUM> produces a H<NUM>S stream <NUM>, a LPG stream <NUM>, a gasoline stream <NUM>, and a ULSD stream <NUM>. The separation unit <NUM> can be designed for other product streams.

<FIG> is an illustrative diagram of another example process <NUM> that incorporates the process of the present invention that upgrades streams with appreciable amounts of PNA. In this example, the process of the present invention is used twice: first for upgrading an as-produced high PNA feed and second for recycle upgrading of the first upgraded product. A hydrogen stream <NUM>, main column bottoms stream <NUM> (high PNA stream), and optionally a solvent stream <NUM> are fed to a hydroprocessing reactor <NUM> for the first upgrading process of the present invention. The product stream <NUM> from the hydrocracking reactor <NUM> is vacuum flash separated in separator <NUM> to produce an overheads stream <NUM> and a <NUM>+°F (<NUM>) bottoms stream <NUM>. The <NUM>+°F (<NUM>+°C) bottoms stream <NUM> is considered the only non-upgraded product of the process. The overheads stream <NUM> is mixed with a recycle stream <NUM> (described below) to produce mixed stream <NUM>, which is distilled in separator <NUM> to produce several upgraded product streams <NUM>-<NUM>. Examples of these streams include, but are not limited to, a H<NUM>S stream <NUM>, a C<NUM>- paraffin stream <NUM>, a gasoline stream <NUM>, a ULSD stream <NUM>, and a <NUM>°F (<NUM>) to <NUM>°F (<NUM>) stream <NUM>. The <NUM>°F (<NUM>) to <NUM>°F (<NUM>) stream <NUM> and hydrogen stream <NUM> are fed to a second hydrocracking reactor <NUM> for upgrading by the processes of the present invention. The product from the hydrocracking reactor <NUM> is the recycle stream <NUM> that is mixed with the overheads stream <NUM> from the separator <NUM> for distillation in separator <NUM>.

In the example illustrated in <FIG>, the hydrocracking reactor <NUM> can have a catalyst that is more robust and less susceptible to fouling because the main column bottoms stream <NUM> can have high concentrations of sulfur (e.g., greater than <NUM> wt% sulfur) and nitrogen. The separator <NUM> removes the sulfur and nitrogen from the mixed stream <NUM>, so that the <NUM>°F (<NUM>) to <NUM>°F (<NUM>) stream <NUM> has less than <NUM> ppm of sulfur and less than <NUM> ppm nitrogen. Accordingly, a base metal catalyst may be suitable for use in the first hydrocracking reactor <NUM>; and a more active catalyst like a NiMo sulfided catalyst and/or a noble metal catalyst may be suitable for use in the second hydrocracking reactor <NUM>. Examples of base metal catalysts include, but are not limited to, a zeolitic base selected from zeolite Beta, zeolite X, zeolite Y, faujasite, ultrastable Y (USY), dealuminized Y (Deal Y), Mordenite, ZSM-<NUM>, ZSM-<NUM>, ZSM-<NUM>, ZSM-<NUM>, ZSM-<NUM>, and combinations thereof, which base can advantageously be loaded with one or more Group VIB and Group VIII non-noble metals. Commercially available base metal catalyst include the NEBULA® catalysts (available from Albemarle Catalysts Company LP). Examples of noble metal catalysts include, but are not limited to, noble metal and noble metal complexes of ruthenium, rhodium, platinum, palladium, and the like on supports like amorphous supports, mesoporous supports, and zeolites. Specific examples of noble metal catalysts and methods of making such catalysts can be found in <CIT>; <CIT>; and <CIT>.

When multiple catalysts are used in the second hydrocracking reactor <NUM>, one or more base metal catalyst may be used in the second hydrocracking reactor <NUM> upstream of the more active catalyst. In this example, by using two types of catalyst and recycling product for further upgrading, up to <NUM> wt% (e.g., <NUM> wt% to <NUM> wt%, or alternatively <NUM> wt% to <NUM> wt%) of the original PNA feed can be upgraded to products like LPG, gasoline, and ULSD. When successive hydrocracking is performed (e.g., <FIG>), the successive hydrocracking processes can convert <NUM> wt% or greater (e.g., <NUM> wt% to <NUM> wt%) of the <NUM>-ring aromatics in the PNA feed stream to saturates, or alternatively <NUM> wt% or greater of the <NUM>-ring aromatics in the PNA feed stream to saturates, or alternatively <NUM> wt% or greater of the <NUM>-ring aromatics in the PNA feed stream to saturates.

The hydrocracking reactor according to the processes of the present invention (e.g., as described in <FIG>) operates at <NUM> to <NUM>, alternatively <NUM> to <NUM>, or alternatively <NUM> to <NUM>.

The hydrocracking reactor according to the processes of the present invention operates at <NUM> psig (<NUM> MPa) or greater, alternatively <NUM> psig (<NUM> MPa) or greater, or alternatively <NUM> psig (<NUM> MPa) or greater.

The hydrocracking reactor according to the processes of the present invention operates at <NUM> hr-<NUM> to <NUM> hr-<NUM> LSHV, alternatively <NUM> hr-<NUM> to <NUM> hr-<NUM> LSHV, or alternatively <NUM> hr-<NUM> to <NUM> hr-<NUM> LSHV.

The hydrocracking reactor according to the processes of the present invention operates at <NUM> to <NUM>, <NUM> psig (<NUM> MPa) or greater, and <NUM> hr-<NUM> to <NUM> hr-<NUM> LSHV. One skilled in the art will recognize that reactor design and materials should be modified for safe operation under such conditions.

When a solvent is used, the weight ratio of PNA feed stream to solvent according to the processes of the present invention can be <NUM>:<NUM> to <NUM>:<NUM>, alternatively <NUM>:<NUM> to <NUM>:<NUM>, or alternatively <NUM>:<NUM> to <NUM>:<NUM>.

The weight ratio of PNA feed stream to hydrogen according to the processes of the present invention is <NUM>:<NUM> to <NUM>:<NUM>, alternatively <NUM>:<NUM> to <NUM>:<NUM>, or alternatively <NUM>:<NUM> to <NUM>:<NUM>.

The PNA feed stream and product stream from the hydrocracking reactor according to the processes of the present invention can be characterized in different ways regarding their composition.

The PNA feed stream has <NUM> wt% or less of hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and having an aromatic content of <NUM> wt% or greater, alternatively <NUM> wt% or less of hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and having an aromatic content of <NUM> wt% or greater, or alternatively <NUM> wt% or less of hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and having an aromatic content of <NUM> wt% or greater, while the product stream from the hydrocracking reactor can comprises <NUM> wt% or greater of the hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and having an aromatic content of <NUM> wt% or less, alternatively <NUM> wt % or greater of the hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and having an aromatic content of <NUM> wt% or less, or alternatively <NUM> wt % or greater of the hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and having an aromatic content of <NUM> wt% or less.

The PNA feed stream can comprise <NUM> mol% or less of saturates, and the product comprises <NUM> mol% or greater of saturates. Alternatively, the PNA feed stream can comprise <NUM> mol% or less of saturates, and the product comprises <NUM> mol% or greater of saturates. Alternatively, the PNA feed stream can comprise <NUM> mol% or less of saturates, and the product comprises <NUM> mol% or greater of saturates.

The PNA feed stream can comprise <NUM> mol% or less of PNA <NUM>+°F (<NUM>+°C) vacuum residue pitch, alternatively <NUM> mol% or less of PNA <NUM>+°F (<NUM>+°C) vacuum residue pitch, or alternatively <NUM> mol% or less of PNA <NUM>+°F (<NUM>+°C) vacuum residue pitch.

The distilled product streams except any H<NUM>S stream can have a sulfur content of <NUM> ppm or less, or alternatively <NUM> ppm or less, or alternatively <NUM> ppm or less.

The product stream from the hydrocracking reactor and/or the streams after distillation of the product stream from the hydrocracking reactor can optionally be further refined, for example, by hydrotreating, by the Arosat process, and/or further hydrocracking according to the processes of the present invention.

The catalyst bed in the hydrocracking reactor according to the processes of the present invention can include one or more hydroprocessing catalysts. Suitable hydroprocessing catalysts include those comprising (i) one or more bulk metals and/or (ii) one or more metals on a support. The metals can be in elemental form or in the form of a compound. In one or more embodiments, the hydroprocessing catalyst includes at least one metal from any of Groups <NUM> to <NUM> of the Periodic Table of the Elements (tabulated as the Periodic Chart of the Elements, <NPL>). Examples of such catalytic metals include, but are not limited to, vanadium, chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron, cobalt, nickel, ruthenium, palladium, rhodium, osmium, iridium, platinum, or mixtures thereof.

The catalyst can have a total amount of Groups <NUM> to <NUM> metals per gram of catalyst of at least <NUM> grams, or at least <NUM> grams or at least <NUM> grams, in which grams are calculated on an elemental basis. For example, the catalyst can comprise a total amount of Group <NUM> to <NUM> metals in a range of from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams. In a particular embodiment, the catalyst further comprises at least one Group <NUM> element. An example of a preferred Group <NUM> element is phosphorus. When a Group <NUM> element is utilized, the catalyst can include a total amount of elements of Group <NUM> in a range of from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, in which grams are calculated on an elemental basis.

The catalyst can comprise at least one Group <NUM> metal. Examples of preferred Group <NUM> metals include chromium, molybdenum and tungsten. The catalyst may contain, per gram of catalyst, a total amount of Group <NUM> metals of at least <NUM> grams, or at least <NUM> grams, or at least <NUM> grams, in which grams are calculated on an elemental basis. For example, the catalyst can contain a total amount of Group <NUM> metals per gram of catalyst in the range of from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, the number of grams being calculated on an elemental basis.

The catalyst can include at least one Group <NUM> metal and further include at least one metal from Group <NUM>, Group <NUM>, Group <NUM>, Group <NUM>, or Group <NUM>. Such catalysts can contain, e.g., the combination of metals at a molar ratio of Group <NUM> metal to Group <NUM> metal in a range of from <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>, in which the ratio is on an elemental basis. Alternatively, the catalyst will contain the combination of metals at a molar ratio of Group <NUM> metal to a total amount of Groups <NUM> to <NUM> metals in a range of from <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>, in which the ratio is on an elemental basis.

When the catalyst includes at least one Group <NUM> metal and one or more metals from Groups <NUM> or <NUM> (e.g., molybdenum-cobalt and/or tungsten-nickel), these metals can be present at a molar ratio of Group <NUM> metal to Groups <NUM> and <NUM> metals in a range of from <NUM> to <NUM>, or from <NUM> to <NUM>, in which the ratio is on an elemental basis. When the catalyst includes at least one of Group <NUM> metal and at least one Group <NUM> metal, these metals can be present, e.g., at a molar ratio of Group <NUM> metal to Group <NUM> metal in a range of from <NUM> to <NUM>, or from <NUM> to <NUM>, where the ratio is on an elemental basis. Catalysts that further comprise inorganic oxides, e.g., as a binder and/or support, are within the scope of the invention. For example, the catalyst can comprise (i) ≧<NUM> wt % of one or more metals selected from Groups <NUM>, <NUM>, <NUM>, and <NUM> of the Periodic Table and (ii) ≧<NUM> wt % of an inorganic oxide, the weight percents being based on the weight of the catalyst.

The catalyst is a bulk multimetallic hydroprocessing catalyst with or without binder. For example, the catalyst can be a bulk trimetallic catalyst comprised of two Group <NUM> metals, preferably Ni and Co and the one Group <NUM> metals, preferably Mo.

The catalytic metals can be incorporated into (or deposited on) a support to form the hydroprocessing catalyst. The support can be a porous material. For example, the support can comprise one or more refractory oxides, porous carbon-based materials, zeolites, or combinations thereof suitable refractory oxides include, for example, alumina, silica, silica-alumina, titanium oxide, zirconium oxide, magnesium oxide, and mixtures thereof. Suitable porous carbon-based materials include, but are not limited to, activated carbon and/or porous graphite. Examples of zeolites include, but are not limited to, Y-zeolites, beta zeolites, mordenite zeolites, ZSM-<NUM> zeolites, and ferrierite zeolites. Additional examples of support materials include gamma alumina, theta alumina, delta alumina, alpha alumina, or combinations thereof. The amount of gamma alumina, delta alumina, alpha alumina, or combinations thereof, per gram of catalyst support, can be in a range of from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, or at most <NUM> grams, as determined by x-ray diffraction. In a particular embodiment, the hydroprocessing catalyst is a supported catalyst, the support comprising at least one alumina (e.g., theta alumina) in an amount in the range of from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, or from <NUM> grams to <NUM> grams, the amounts being per gram of the support. The amount of alumina can be determined using, for example, x-ray diffraction. In alternative embodiments, the support can comprise at least <NUM> grams, or at least <NUM> grams, or at least <NUM> grams, or at least <NUM> grams of theta alumina.

When a support is utilized, the support can be impregnated with the desired metals to form the hydroprocessing catalyst. The support can be heat-treated at temperatures in a range of from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>, prior to impregnation with the metals. In certain embodiments, the hydroprocessing catalyst can be formed by adding or incorporating the Groups <NUM> to <NUM> metals to shaped heat-treated mixtures of support. This type of formation is generally referred to as overlaying the metals on top of the support material. Optionally, the catalyst is heat treated after combining the support with one or more of the catalytic metals at a temperature in the range of from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>. Optionally, the catalyst is heat treated in the presence of hot air and/or oxygen-rich air at a temperature in a range between <NUM> and <NUM> to remove volatile matter such that at least a portion of the Groups <NUM> to <NUM> metals are converted to their corresponding metal oxide. In other embodiments, the catalyst can be heat treated in the presence of oxygen (e.g., air) at temperatures in a range of from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>. Heat treatment can take place for a period of time in a range of from <NUM> to <NUM> hours to remove a majority of volatile components without converting the Groups <NUM> to <NUM> metals to their metal oxide form. Catalysts prepared by such a method are generally referred to as "uncalcined" catalysts or "dried. " Such catalysts can be prepared in combination with a sulfiding method, with the Groups <NUM> to <NUM> metals being substantially dispersed in the support. When the catalyst comprises a theta alumina support and one or more Groups <NUM> to <NUM> metals, the catalyst is generally heat treated at a temperature ≧<NUM>° C. to form the hydroprocessing catalyst. Typically, such heat treating is conducted at temperatures ≦<NUM>° C.

The catalyst can be in shaped forms (e.g., one or more of discs, pellets, extrudates, etc.) though this is not required. Non-limiting examples of such shaped forms include those having a cylindrical symmetry with a diameter in the range of from about <NUM> to about <NUM> (<NUM>/32nd to <NUM>/8th inch), from about <NUM> to about <NUM> (<NUM>/20th to <NUM>/10th inch), or from about <NUM> to about <NUM> (<NUM>/20th to <NUM>/16th inch). Similarly-sized non-cylindrical shapes like trilobe and quadralobe are within the scope of the invention. Optionally, the catalyst has a flat plate crush strength in a range of from <NUM>-<NUM> N/cm, or <NUM>-<NUM> N/cm, or <NUM>-<NUM> N/cm, or <NUM>-<NUM> N/cm, or <NUM>-<NUM> N/cm.

Porous catalysts, including those having conventional pore characteristics, are within the scope of the invention. When a porous catalyst is utilized, the catalyst can have a pore structure, pore size, pore volume, pore shape, pore surface area, etc., in ranges that are characteristic of conventional hydroprocessing catalysts, though the invention is not limited thereto. For example, the catalyst can have a median pore size that is effective for hydroprocessing SCT molecules, such catalysts having a median pore size in the range of from <NUM>Å to <NUM>Å, or <NUM>Å to <NUM>Å, or <NUM>Å to <NUM>Å. Pore size can be determined according to ASTM D4284-<NUM> Mercury Porosimetry.

In a particular embodiment, the hydroprocessing catalyst has a median pore diameter in a range of from <NUM>Å to <NUM>Å. Alternatively, the hydroprocessing catalyst has a median pore diameter in a range of from <NUM>Å to <NUM>Å, or <NUM>Å to <NUM>Å, or <NUM>Å to <NUM>Å. In another embodiment, the hydroprocessing catalyst has a median pore diameter ranging from <NUM>Å to <NUM>Å. Alternatively, the hydroprocessing catalyst has a median pore diameter in a range of from <NUM>Å to <NUM>Å, or from <NUM>Å to <NUM>Å. In yet another alternative, hydroprocessing catalysts having a larger median pore diameter are utilized, e.g., those having a median pore diameter in a range of from <NUM>Å to <NUM>Å, or <NUM>Å to <NUM>Å, or <NUM>Å to <NUM>Å.

Generally, the hydroprocessing catalyst has a pore size distribution that is not so great as to significantly degrade catalyst activity or selectivity. For example, the hydroprocessing catalyst can have a pore size distribution in which at least <NUM>% of the pores have a pore diameter within <NUM>Å, <NUM>Å, or <NUM>Å of the median pore diameter. In certain embodiments, the catalyst has a median pore diameter in a range of from <NUM>Å to <NUM>Å, or from <NUM>Å to <NUM>Å, with at least <NUM>% of the pores having a pore diameter within <NUM>Å, <NUM>Å, or <NUM>Å of the median pore diameter.

When a porous catalyst is utilized, the catalyst can have a pore volume ≧<NUM><NUM>/g, such ≧<NUM><NUM>/g, or ≧<NUM><NUM>/g. In certain embodiments, pore volume can range from <NUM><NUM>/g to <NUM><NUM>/g, <NUM><NUM>/g to <NUM><NUM>/g, or <NUM><NUM>/g to <NUM><NUM>/g.

In certain embodiments, a relatively large surface area can be desirable. As an example, the hydroprocessing catalyst can have a surface area ≧<NUM><NUM>/g, or ≧<NUM><NUM>/g, or ≧<NUM><NUM>/g, or ≧<NUM><NUM>/g, or ≧<NUM><NUM>/g, or ≧<NUM><NUM>/g; such as in the range of from <NUM><NUM>/g to <NUM><NUM>/g, or <NUM><NUM>/g to <NUM><NUM>/g, or <NUM><NUM>/g to <NUM><NUM>/g, or <NUM><NUM>/g to <NUM><NUM>/g.

Conventional hydrotreating catalysts can be used, but the invention is not limited thereto. In certain embodiments, the catalysts include one or more of KF860 available from Albemarle Catalysts Company LP; NEBULA® Catalyst, such as NEBULA® <NUM>, available from the same source; CENTERA® catalyst, available from Criterion Catalysts and Technologies, such as one or more of DC-<NUM>, DN-<NUM>, DC-<NUM>, and DN-<NUM>; ASCENT® Catalyst, available from the same source, such as one or more of DC-<NUM>, DC-<NUM>, and DN-<NUM>; and FCC pretreat catalyst, such as DN3651 and/or DN3551, available from the same source. However, the invention is not limited to only these catalysts.

When hydrocracking methods of the present invention are utilized in sequence, preferably the first hydrocracking reactor uses a base metal catalyst that can tolerate higher concentrations of nitrogen and sulfur. The second hydrocracking reactor can use a noble metal catalyst. Examples of noble metal catalysts include, but are not limited to, a zeolitic base selected from zeolite Beta, zeolite X, zeolite Y, faujasite, ultrastable Y (USY), dealuminized Y (Deal Y), Mordenite, ZSM-<NUM>, ZSM-<NUM>, ZSM-<NUM>, ZSM-<NUM>, ZSM-<NUM>, and combinations thereof, which base can advantageously be loaded with one or more Group VIII noble metals such as platinum and/or palladium.

When more than one catalyst is used in a single hydrocracking reactor, the catalysts can be blended and/or stacked. In a stacked configuration, the PNA feed stream is exposed to the catalysts sequentially.

While compositions and methods are described herein in terms of "comprising" various components or steps, the compositions and methods can also "consist essentially of" or "consist of" the various components and steps.

To facilitate a better understanding of the embodiments of the present invention, the following examples of preferred or representative embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the invention.

In the Examples, <NUM> barrel = <NUM><NUM>.

Example <NUM>. A simulation was run using the process <NUM> illustrated in <FIG> with Cold Lake vacuum residue as the vacuum residue starting material. Table <NUM> includes the amount compositions of the various streams where reference numbers refer to <FIG>.

Example <NUM>. A main columns bottom (MCB) was produced and run using the process <NUM> illustrated in <FIG> without solvent. The MCB had the following properties: <NUM>/cc density; <NUM> wt% sulfur; <NUM> wt% nitrogen; <NUM> wt% MCR; <NUM> wt% n-heptane insolubles; <NUM> wt% hydrogen; <NUM> cSt viscosity at <NUM>; <NUM> cSt viscosity at <NUM>; and simulated distillation values for T10 of <NUM>°F (<NUM>), T50 of <NUM>°F (<NUM>), T90 of <NUM>°F (<NUM>), and <NUM> wt% <NUM>+°F (<NUM>+°C).

<FIG> illustrates the catalyst bed design <NUM> of the first hydrocracking reactor <NUM>. The reactants (hydrogen and MCB) are fed into a first catalyst bed <NUM> via stream <NUM>. The first catalyst bed <NUM> includes <NUM><NUM> of a low activity, large pore sulfide NiMo on alumina catalyst stacked on <NUM><NUM> of medium pore sulfided NiMo on alumina hydrotreating catalyst bed <NUM>. The material then passes to a second catalyst bed <NUM> containing <NUM><NUM> of medium pore sulfided NiMo on alumina hydrotreating catalyst <NUM>. The material then passes to a third catalyst bed <NUM> containing <NUM><NUM> of medium pore sulfided NiMo on alumina hydrotreating catalyst <NUM> stacked on <NUM><NUM> of sulfide noble metal hydrotreating catalyst <NUM>. The material then passes to a fourth catalyst bed <NUM> containing <NUM><NUM> of sulfided noble metal hydrotreating catalyst <NUM> stacked on <NUM><NUM> of a sulfided NiMo on USY bound with alumina catalyst <NUM>. The resultant product stream <NUM> is product stream <NUM> of <FIG>. The product <NUM> was vacuum distilled to take <NUM> vol% overhead. The distillate contained in the <NUM>-°F (<NUM>-°C) fraction contained very close to <NUM> ppm sulfur enabling use of this stream as ULSD.

<FIG> illustrates the catalyst bed design <NUM> for the second hydrocracking reactor <NUM>. The distillation resid <NUM> (e.g., <NUM>°F (<NUM>) to <NUM>°F (<NUM>) stream <NUM> of <FIG>) are fed into a first catalyst bed <NUM> containing <NUM><NUM> of medium pore sulfided NiMo on alumina hydrotreating catalyst <NUM> stacked on <NUM><NUM> of sulfide noble metal hydrotreating catalyst <NUM>. The material is then passed through a second catalyst bed <NUM> containing <NUM><NUM> of a Pt on USY noble metal hydrocracking catalyst <NUM>. The resultant product stream <NUM> is the recycle stream <NUM> of <FIG>. The conditions in the second catalyst bed <NUM> were <NUM>, <NUM> psig (<NUM> MPa), <NUM>,<NUM> SCFB (<NUM><NUM>/m<NUM>) hydrogen co-feed, and <NUM> LHSV. At these conditions, the reactor product <NUM> had <NUM> ppm sulfur. It is believed that it would be practical to hold the reactor at <NUM> ppm sulfur at <NUM> LHSV for more than a year. Surprisingly, the catalyst was stable within experimental error at the following conditions where extinction recycle hydrocracking was demonstrated at <NUM> psig (<NUM> MPa), <NUM> LHSV, <NUM> C, <NUM>,<NUM> SCFB (<NUM><NUM>/m<NUM>) hydrogen circulation, and <NUM>:<NUM> recycle to fresh feed ratio.

The reaction consumed close to <NUM> SCFB (<NUM><NUM>/m<NUM>) of hydrogen across both stages. The liquid product (LPG (<NUM>/cc) + Gasoline (<NUM>/cc, <<NUM> ppm S) + ULSD (<NUM>/cc, <NUM>-<NUM> ppm sulfur) was <NUM> vol% of the feed. The stage <NUM> hydrocracker gasoline was <NUM> wt% aromatics, <NUM> wt% naphthenes, and <NUM> wt% paraffins + isoparaffins. The stage <NUM> full range ULSD was <NUM> wt% paraffins + isoparaffins, <NUM>% naphthenes, and <NUM> wt% aromatics. The <NUM>+°F (<NUM>+°C) tail of the stage <NUM> ULSD was enriched in aromatics (<NUM> wt% saturates/<NUM> wt% aromatics). The <NUM>-°F (<NUM>-°C) products were comprised of <NUM> wt% paraffins, <NUM> wt% naphthenes, and <NUM> wt% aromatics. Table <NUM> includes the amount compositions of the various streams where reference numbers refer to <FIG>.

Example <NUM>. A main columns bottom (MCB) was produced with the following properties: <NUM>/cc density; <NUM> wt% sulfur; <NUM> wt% nitrogen; <NUM> wt% micro carbon residue; <NUM> wt% n-heptane insolubles; <NUM> wt% hydrogen; <NUM> cSt viscosity at <NUM>; <NUM> cSt viscosity at <NUM>; and simulated distillation values for T10 of <NUM>°F (<NUM>), T50 of <NUM>°F (<NUM>), T90 of <NUM>°F (<NUM>), and <NUM> wt% <NUM>+°F (<NUM>+°C). With the high micro carbon residue value, this feed is considered a high coking feedstock. No solvent was used in this example.

A standard fixed bed reactor with a stacked catalyst bed was used for hydrocracking. The stacked catalyst bed was <NUM> vol% lightly crushed extrudates of high activity, medium pore sulfide NiMo on alumina hydrotreating catalyst stacked on top of <NUM> vol% lightly crushed extrudates of noble metal hydrotreating catalyst stacked on top of <NUM> vol% a sulfided NiMo on USY bound with alumina. The MCB blend was hydrocracked at the following conditions: <NUM>; <NUM> psig (<NUM> MPa); <NUM>,<NUM> standard cubic feed per barrel (SCFB) (<NUM><NUM>/m<NUM>) hydrogen co-feed; and <NUM> LHSV total (<NUM> LHSV DN-<NUM>; <NUM> LHSV sulfide noble metal catalyst; <NUM> LHSV ZFX).

The reaction consumed <NUM> SCFB (<NUM><NUM>/m<NUM>) of hydrogen. The liquid product (LPG (<NUM>/cc) + Gasoline (<NUM>/cc) + ULSD (<NUM>/cc) + naphthenic base stock (<NUM>/cc)) was <NUM> vol% of the feed. The reactor divided the product into three buckets with the following yields: <NUM> wt% gas (<NUM> wt% H<NUM>S; <NUM> wt% C<NUM>- paraffins; <NUM> wt% C<NUM>+ paraffins); <NUM> wt% light liquids (<NUM>/cc density; less than <NUM> ppm nitrogen plus sulfur; simulated distillation values for T10 of <NUM>°F (<NUM>), T50 of <NUM>°F (<NUM>), T90 of <NUM>°F (<NUM>); and <NUM> wt% heavy liquids (<NUM>/cc density; <NUM> ppm sulfur; <NUM> ppm nitrogen; simulated distillation values for T10 of <NUM>°F (<NUM>), T50 of <NUM>°F (<NUM>), T90 of <NUM>°F (<NUM>)).

The combined liquids of the product were distilled into <NUM> wt% <NUM>°F (<NUM>) to <NUM>°F (<NUM>) gasoline (<NUM>/cc density; <<NUM> ppm nitrogen plus sulfur), <NUM> wt% <NUM>°F (<NUM>) to <NUM>°F (<NUM>) ULSD (<NUM>/cc density; <NUM> ppm sulfur), and <NUM> wt% of <NUM>°F (<NUM>) to <NUM>°F (<NUM>) naphthenic basestock (<NUM>/cc density; <NUM> ppm sulfur; <NUM> ppm nitrogen).

The greater than <NUM>°F (<NUM>) fraction of gasoline was analyzed via gas chromatography (results in Table <NUM>). The simulated distillation values were T10 of <NUM>°F (<NUM>), T50 of266°F (<NUM>), and a T90 of <NUM>°F (<NUM>).

The <NUM>°F (<NUM>) to <NUM>°F (<NUM>) naphthenic basestock fraction was analyzed by liquid chromatography and produced the following composition: <NUM> wt% paraffins + isoparaffins + <NUM>-ring naphthenes; <NUM> wt% <NUM>-<NUM> ring naphthenes (mostly <NUM>-<NUM> ring naphthenes); <NUM> wt% <NUM>-ring aromatics (mostly <NUM>-<NUM> ring napthenoaromatics); <NUM> wt% <NUM>-ring aromatics (mostly <NUM>-<NUM> ring naphthenoaromatics); <NUM> wt% <NUM>-ring aromatics (mostly <NUM>-<NUM> ring naphthenoaromatics); and <NUM> wt% <NUM>+ ring PNA. Accordingly, this fraction may be useful as a napthenic basestock, solvent, rubber blending oil, resin, and the like. The sulfur and nitrogen were concentrated in the <NUM>+°F (<NUM>+°C) tail. By excluding this tail, the sulfur and nitrogen are low enough that the product could be directly hydrogenated with noble metal catalysts.

The <NUM>°F (<NUM>) to <NUM>°F (<NUM>) ULSD fraction was further analyzed by liquid chromatography and produced the following composition: <NUM> wt% paraffins + isoparaffins + <NUM>-ring naphthenes; <NUM> wt% <NUM>+ ring naphthenes; <NUM> wt% <NUM> ring aromatics (mostly <NUM>-<NUM> ring naphthenoaromatics; <NUM> wt% <NUM> ring aromatics; and <NUM> wt% <NUM>+ring aromatics. Accordingly, this fraction may be useful as a napthenic basestock, solvent, transformer oil, and the like. This fraction has less than <NUM> ppm combined sulfur and nitrogen. Accordingly, this fraction could be directly hydrogenated with noble metal catalysts.

The <NUM>-°F (<NUM>-°C) hydrocarbon products from this example were comprised of <NUM> wt% paraffins, <NUM>% naphthenes, and <NUM> wt% aromatics.

Example <NUM>. The MCB from a hydrotreating operation were used in combination with hydrogen and passed through a hydrocracking reactor with a noble metal hydrotreating catalyst. The feed had <NUM> ppm sulfur, <NUM> ppm nitrogen, <NUM> cSt viscosity at <NUM>, and <NUM> mmol/kg total aromatics of which <NUM> mmol/kg was <NUM>+ring aromatics. After hydrotreating the product had <NUM> ppm sulfur, <NUM> ppm nitrogen, and <NUM> mmol/kg total aromatics of which <NUM> mmol/kg was <NUM>+ring aromatics. The product was distilled into four fractions: naphtha fraction, distillate fraction, <NUM>°F (<NUM>) to <NUM>°F (<NUM>) fraction, and <NUM>+°F (<NUM>+°C) fraction. <FIG> is a photograph of the <NUM>°F (<NUM>) to <NUM>°F (<NUM>) fraction showing a thick and dark fluid.

The <NUM>°F (<NUM>) to <NUM>°F (<NUM>) fraction was further hydrotreated with additional hydrogen to produce the product in the <FIG> photograph, which is a lower viscosity than the <NUM>°F (<NUM>) to <NUM>°F (<NUM>) fraction. This product was then treated with the Arosat process and distilled into two fractions: a <NUM>-°F (<NUM>-°C) fraction and a <NUM>+°F (<NUM>+°C) fraction. <FIG> is a photograph of the <NUM>+°F (<NUM>+°C) fraction, which is low viscosity and clear with a <NUM> cSt viscosity at <NUM> that can be used as basestock.

The distillate fraction was similarly hydrotreated and distilled into four fractions: transformer oil, traction fluid, EV/HV oil, and bottoms. The various fractions have the properties provided in Table <NUM>.

Example <NUM>. A main columns bottom (MCB) was produced having the following properties: <NUM>/cc density; <NUM> wt% sulfur; <NUM> wt% nitrogen; <NUM> wt% MCR; <NUM> wt% n-heptane insolubles; <NUM> wt% hydrogen; <NUM> cSt viscosity at <NUM>; <NUM> cSt viscosity at <NUM>; and simulated distillation values for T10 of <NUM>°F (<NUM>), T50 of <NUM>°F (<NUM>), T90 of <NUM>°F (<NUM>), and <NUM> wt% <NUM>+°F (<NUM>+°C).

A standard fixed bed reactor was loaded with <NUM> vol% lightly crushed extrudates of high activity, medium pore sulfide NiMo on alumina hydrotreating catalyst stacked on top of <NUM> vol% sulfided NiMo on USY bound with alumina. The MCB blend was hydrocracked at the following conditions: <NUM>; <NUM> psig (<NUM> MPa), <NUM>,<NUM> SCFB (<NUM><NUM>/m<NUM>) hydrogen co-feed; and <NUM> LHSV.

The reaction consumed <NUM> SCFB (<NUM><NUM>/m<NUM>) of hydrogen. The liquid product (LPG (<NUM>/cc) + Gasoline (<NUM>/cc) + ULSD (<NUM>/cc) + naphthenic base stock (<NUM>/cc)) was <NUM> vol% of the feed. The reactor divided the product into three buckets: (<NUM>) <NUM> wt% gas (<NUM> wt% H<NUM>S, <NUM> wt% C<NUM>- paraffins, and <NUM> wt% C<NUM>+ paraffins), (<NUM>) <NUM> wt% light liquids (<NUM>/cc density, <<NUM> ppm combined nitrogen and sulfur, and simulated distillation values for T10 of <NUM>°F (<NUM>), T50 of <NUM>°F (<NUM>), T90 of <NUM>°F (<NUM>)), and (<NUM>) <NUM> wt% heavy liquids (<NUM>/cc density, <NUM> ppm sulfur, <NUM> ppm nitrogen, and simulated distillation values for T10 of <NUM>°F (<NUM>), T50 of <NUM>°F (<NUM>), T90 of <NUM>°F (<NUM>)). The products of this reaction boiling below <NUM>°F (<NUM>) were close to <NUM> wt% paraffins, <NUM> wt% naphthenes, and <NUM> wt% aromatics. The products of this reaction boiling below <NUM>°F (<NUM>) were close to <NUM> wt% paraffins, <NUM> wt% naphthenes, and <NUM> wt% aromatics.

Claim 1:
A method comprising:
hydrocracking a polynucleararomatic hydrocarbon (PNA) feed in the presence of hydrogen and a base metal catalyst at <NUM> to <NUM>, <NUM> psig (<NUM> MPa) or greater, and <NUM> hr-<NUM> to <NUM> hr-<NUM> liquid hourly space velocity (LSHV), wherein the weight ratio of PNA feed to hydrogen is <NUM>:<NUM> to <NUM>:<NUM>, wherein the PNA feed comprises <NUM> wt% or less of hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and <NUM> wt% or greater sulfur and having an aromatic content of <NUM> wt% or greater to form a first product;
separating the first product into an overheads stream and a <NUM>+°F (<NUM>) bottoms stream, wherein the overheads stream comprises <NUM> wt% or greater of the hydrocarbons having a boiling point of <NUM>°F (<NUM>) or less and having an aromatic content of <NUM> wt% or less;
distilling the overheads stream into a <NUM>+°F (<NUM>+°C) boiling point stream having less than <NUM> ppm sulfur and one or more fractions selected from the group consisting of: a C<NUM>- paraffin stream comprising less than <NUM> ppm sulfur, a naphtha fraction having less than <NUM> ppm sulfur, and a distillate fraction having less than <NUM> ppm sulfur;
hydrocracking the <NUM>+°F (<NUM>+°C) boiling point stream in the presence of hydrogen and a noble metal catalyst to form a second product; and
recycling the second product to mix the second product and the overheads before distillation.