Abstract: Methods of oligomerizing hydrocarbons are disclosed. These methods include contacting olefins with an oligomerization catalyst in an oligomerization zone under oligomerization reaction conditions.

Abstract: The benzene content in a gasoline pool is reduced by a process that hydrogenates a benzene-containing isomerization zone feedstream. The additional cyclic hydrocarbons produced by the saturation of benzene can be processed in the isomerization zone for ring opening to increase the available paraffinic feedstock or the isomerization zone can be operated to pass the cyclic hydrocarbons through to a product recovery section. The isomerization zone feedstream is treated to remove contaminants and dried before entering the hydrogenation zone.

Abstract: The benzene content in a gasoline pool is reduced by a process that hydrogenates a benzene-containing isomerization zone feedstream. The additional cyclic hydrocarbons produced by the saturation of benzene can be processed in the isomerization zone for ring opening to increase the available paraffinic feedstock or the isomerization zone can be operated to pass the cyclic hydrocarbons through to a product recovery section. The isomerization zone feedstream is treated to remove contaminants and dried before entering the hydrogenation zone.

Abstract: A process for the production of alkylbenzene includes the steps of introducing benzene and an olefin feed into a first alkylation reaction zone in the presence of a first alkylation catalyst under first alkylation reaction conditions to produce alkylbenzene and a vapor containing unconverted olefin; absorbing the unconverted olefin into an aromatic stream containing benzene and alkylbenzene; and, introducing the aromatic stream containing absorbed olefin into a second alkylation reaction zone containing a second alkylation catalyst under second alkylation reaction conditions to convert the absorbed olefin and at least some of the benzene of the aromatic stream to alkylbenzene. The process is particularly advantageous for the alkylation of benzene with ethylene to produce ethylbenzene. About 99.9% conversion of ethylene is achieved overall, with a substantial reduction in the required catalyst.

Abstract: A process for the production of alkylbenzene includes introducing benzene and an olefin feed into a first alkylation reaction zone in the presence of a first alkylation catalyst under first alkylation reaction conditions to produce a first alkylation effluent containing alkylbenzene and a first alkylation overhead stream. The first alkylation overhead stream is separated into a liquid portion containing benzene and a vapor portion containing unconverted olefin and ethane. A major portion of the unconverted olefin in the vapor portion of the first alkylation overhead stream is absorbed into a de-ethanized aromatic lean oil stream containing benzene and alkylbenzene in an absorption zone to produce a rich oil stream containing olefins and at least some of the ethane.

Abstract: The present invention relates to a process for the production of alkene(s) from a feedstock comprising of at least one monohydric aliphatic paraffinic alcohol in a reactive distillation reactor with olefin recycle.

Abstract: A process for preparing a gas oil cut comprises the following steps in succession: 1) oligomerizing an olefinic C2-C12 hydrocarbon cut, preferably C3-C7 and more preferably C3-C5; 2) separating the mixture of products obtained in step 1) into three cuts: a light cut containing unreacted C4 and/or C5 olefinic hydrocarbons, an intermediate cut having a T95 in the range 200-220° C. and a heavy cut comprising the complement; T95 being the temperature at which 95% by weight of product has evaporated, as determined in accordance with standard method ASTM D2887; 3) oligomerizing the intermediate cut obtained in the separation step; characterized in that in step 3), oligomerization is carried out in the presence of an olefinic C4 and/or C5 hydrocarbon cut in a weight ratio of intermediate cut to olefinic C4 and/or C5 cut in the range of 60/40 to 80/20.

Abstract: A cross-metathesis process for preparing an ?,?-functionalized olefin, such as methyl 9-decenoate, and an ?-olefin having three or more carbon atoms, such as 1-decene.

Abstract: A process for producing a monoalkylation aromatic product, such as ethylbenzene and cumene, utilizing an alkylation reactor zone and a transalkylation zone in series or a combined alkylation and transkylation reactor zone.

Abstract: A process for producing propylene from ethylene and a feed stream comprising 1-butene is disclosed. The feed stream is contacted with an isomerization catalyst to produce an isomerized stream. The isomerized stream is reacted with ethylene in a distillation column reactor containing a metathesis catalyst to generate a reaction mixture; and the reaction mixture is concurrently distilled to produce an overhead stream comprising ethylene and propylene, and a bottoms stream comprising 1-butene, 2-butene, and C5 and higher olefins. Propylene is separated from the overhead stream.

Abstract: The present invention relates to a process and apparatus for recovering product from reactor effluent of a reactor for a hydrocarbon feedstream. An indigenous C4 stream is used as lean oil in a demethanizer, which facilitates significant cost and operational savings. C4 bottoms from a downstream depropanizer is used as lean oil recycle.

Abstract: This invention provides a process for the production of diesel boiling range hydrocarbons, the process including at least the steps of obtaining an olefinic feed stream from one or more hydrocarbon producing processes wherein the olefinic feed stream contains branched short chain olefins having a chain length of from three to eight carbon atoms, and contacting the feed stream with a shape selective medium pore acid zeolite catalyst in a pressurised reactor at elevated temperature so as to convert said short chain olefins to higher hydrocarbons. The invention also provides an apparatus for carrying out the process and recovering the catalyst for reuse.

Abstract: The present invention relates to a process for the preparation of para-xylene from trimethylpentane.

Abstract: Disclosed is a method and reactor system for converting oxygenate and/or olefin contaminants in a methanol to olefin reactor system product effluent to hydrocarbons, including paraffin compounds, preferably over a sulphided catalyst of the type Nickel or Cobalt combined with Molybdenum or Tungsten. In one embodiment, the oxygenate-containing stream to be hydrogenated comprises one or more of the following streams, alone or in combination: a quench tower bottoms stream, a water absorption unit bottoms stream, a C4+ stream, and/or a C5+ stream.

Abstract: The present invention provides a process for the conversion of synthesis gas to hydrocarbons comprising the steps of: a) contacting synthesis gas at an elevated temperature and pressure with a particulate Fischer-Tropsch catalyst in a Fischer-Tropsch reactor system to generate hydrocarbons comprising gaseous and liquid hydrocarbons; b) in a gas separation zone, separating a gaseous phase comprising saturated gaseous hydrocarbons from a liquid phase comprising liquid hydrocarbons and from the particulate Fischer-Tropsch catalyst; c) passing at least a portion of the separated gaseous phase to a dehydrogenation reactor where at least a portion of the saturated gaseous hydrocarbons are converted to unsaturated hydrocarbons; and d) recycling at least a portion of said unsaturated hydrocarbons back to the Fischer-Tropsch reactor system.

Abstract: A process is described for the production of hydrocarbons with a high octane number starting from mixtures essentially consisting of n-butane and isobutane (such as for example field butanes) comprising a skeleton isomerization section, a dehydrogenation section of paraffins, a selective hydrogenation section of butadiene, two conversion sections of olefins, in which the isobutene is firstly selectively transformed by means of dimerization and/or etherification, followed by the linear butenes by means of alkylation, in order to obtain, by joining the products of the two conversion sections, a product having excellent motoristic properties (octane number, volatility and distillation curve).

Abstract: C2-C8-olefins are oligomerized in a process in which a stream of an olefin-containing hydrocarbon mixture is passed over a heterogeneous, nickel-containing oligomerization catalyst in n successive adiabatically operated reaction zones, where n?2, and the hydrocarbon mixture experiences a temperature increase 66 Treact in each reaction zone and the hydrocarbon mixture enters the first reaction zone at a temperature Tin and before entering each further reaction zone is cooled to a temperature which in each case may be up to 20° C. above or below Tin, and the relative catalyst volumes of the individual reaction zones are such that the difference in ?Treact between any two reaction zones is not more than 20° C.

Abstract: A slurry Fischer-Tropsch hydrocarbon synthesis process for synthesizing liquid hydrocarbons from synthesis gas in a synthesis reactor also hydroisomerizes the synthesized hydrocarbon liquid, which comprises the slurry liquid, in one or more lift reactors immersed in the slurry body in the synthesis reactor. A monolithic catalyst is preferably used for the hydroisomerization, and slurry circulation up through the lift reactors from the surrounding slurry body, is achieved at least in part by the lift action of the hydroisomerization treat gas. Preferably, catalyst particles are also removed before the slurry contacts the catalyst. Hydroisomerization occurs while the synthesis reactor is producing hydrocarbons, without interfering with the synthesis reaction. A gas bubble reducing downcomer may be used to produce and feed the gas bubble reduced slurry into the lift reactor, thereby providing a hydraulic head assist in the slurry circulation up through and out of the lift reactor.

Abstract: A slurry Fischer-Tropsch hydrocarbon synthesis process for synthesizing liquid hydrocarbons from synthesis gas in a synthesis reactor also hydroisomerizes the synthesized hydrocarbons in one or more external lift reactor hydroisomerizing loops outside of the reactor, but which are a part of the reactor. A monolithic catalyst is used for the hydroisomerization and slurry circulation between the synthesis reactor and one or more loops is achieved, at least in part, by the lift action of a hydrogen treat gas injected into each loop.

Abstract: A multistage process for preparing propene, in which the first stage is the reaction of 1-butene, 2-butene and isobutene to give propene, 2-pentene and 2-methyl-2-butene in the presence of a metathesis catalyst comprising at least one compound of a metal of transition group VIb, VIIb or VIII of the Periodic Table of the Elements; the second stage is separation of the propene and 2-pentene/2-methyl-2-butene formed; the third stage is reaction of the 2-pentene and 2-methyl-2-butene with ethehe to give propene, 1-butene and isobutene in the presence of a metathesis catalyst comprising at least one compound of a metal of transition group VIb, VIIb or VIII of the Periodic Table of the Elements; the fourth stage is separation of the propene and 1-butene/isobutene formed and returning the 1-butene and isobutene formed to the first stage.

Abstract: The present invention relates to a process for the preparation of para-xylene from trimethylpentane.

Abstract: This invention relates to processes and systems for the conversion of methane in high yields to C4+ hydrocarbons. The principal steps of the recycle process include reacting methane and O2 in an oxidative coupling reactor over a Mn/Na2WO4/SiO2 catalyst at 800° C. to convert the methane to ethylene, and oligomerizing the ethylene product by reacting it with an H-ZSM-5 zeolite catalyst at 275° C. in a catalytic reactor for subsequent conversion of the ethylene to higher hydrocarbons. Total yields of C4+ products using the process of the invention are in the range of about 60% to about 80%, and yields of C4+ nonaromatic hydrocarbons are in the range of about 50% to about 60%.

Abstract: A process and/or system is provided for isomerizing a hydrocarbon feedstock comprising saturated C6 hydrocarbons by contacting the hydrocarbon feedstock, in the presence of hydrogen and optionally a chloride, with a first isomerization catalyst composition in a first isomerization reactor defining a first reaction zone operated at a first reaction temperature, withdrawing a first intermediate stream comprising cyclohexane and n-hexane from the first reaction zone, separating the first intermediate stream, via a first separator, into a first product stream comprising cyclohexane and a second intermediate stream comprising n-hexane, contacting the second intermediate stream, in the presence of hydrogen and optionally a chloride, with a second isomerization catalyst composition in a second isomerization reactor defining a second reaction zone operated at a second reaction temperature greater than the first reaction temperature, and withdrawing from the second reaction zone a second product stream comprising isoh

Abstract: A process for the alkylation of aromatics with olefins using a solid catalyst is disclosed, wherein the olefin ratio and/or the maximum olefin concentration in the alkylation catalyst, bed is maintained less than an upper limit. Such operation can decrease the catalyst deactivation rate and the formation of diphenylalkanes. This invention is applicable to processes for the production of a wide variety of commercially important alkylated aromatics, including ethylbenzene and cumene.

Abstract: Propene and, if desired, 1-butene are prepared by first reacting 1-butene and 2-butene to give propene and 2-pentene in the presence of a metathesis catalyst containing at least one compound of a metal of transition group VIb, VIIb or VIII of the Periodic Table of the Elements. The propene and 2-pentene formed are subsequently separated, and the 2-pentene is then reacted to give propene and 1-butene in the presence of a metathesis catalyst containing at least one compound of a metal of transition group VIb, VIIb or VIII. The propene and 1-butene formed are subsequently separated, and at least some of the 1-butene is discharged or at least partly isomerized to give 2-butene in the presence of an isomerization catalyst. Undischarged 1-butene and the 2-butene formed are subsequently returned to the initial reaction step, together with that part of the C4 fraction which was not reacted in the initial reaction step.

Abstract: A process for making a lube base stock wherein a highly paraffinic feedstock (with boiling points within the range of from 258° to 1100° F.) is dehydrogenated to produce an olefinic feedstock, which is oligomerized to produce an oligomerized product, which is separated into a lighter fraction and a heavier fraction. That heavier fraction has a flash point within the lube base oil range.

Abstract: Tetrahydroindene is dehydrogenated in a vapor phase in the presence of a metallic catalyst, e.g., a nickel-molybdenum catalyst, to produce indene, which is industrially useful in high yield while inhibiting the catalyst from suffering a decrease in activity. In particular, a higher yield can be attained by a method in which tetrahydroindene is dehydrogenated to first convert it into indane, which is further dehydrogenated to obtain indene.

Abstract: A process for producing alkyl aromatics using a transalkylation reaction zone and an alkylation reaction zone is disclosed. One portion of the transalkylation reaction zone effluent passes to an alkylation reaction zone where an aromatic substrate is alkylated to the desired alkyl aromatic. At least a portion of the alkylation reaction zone effluent and another portion of the transalkylation reaction zone effluent pass to a product recovery zone. This process decreases the capital and operating costs of recycling aromatic substrate to the transalkylation and/or alkylation reaction zone while maintaining operational flexibility. This process is well suited for solid transalkylation and alkylation catalysts. Ethylbenzene and cumene may be produced by this process.

Abstract: The present invention relates to a process for the production of light olefins comprising olefins having from 2 to 4 carbon atoms per molecule from an oxygenate feedstock. The process comprises passing the oxygenate feedstock to an oxygenate conversion zone containing a metal aluminophosphate catalyst to produce a light olefin stream. A propylene stream and/or mixed butylene is fractionated from said light olefin stream and cracked to enhance the yield of ethylene and propylene products. This combination of light olefin product and propylene and butylene cracking in a riser cracking zone or a separate cracking zone provides flexibility to the process which overcomes the equilibrium limitations of the aluminophosphate catalyst. In addition, the invention provides the advantage of extended catalyst life and greater catalyst stability in the oxygenate conversion zone.

Abstract: A process for isomerising a feed comprising aromatic compounds containing 8 carbon atoms is carried out in two steps: an isomerisation step and a dehydrogenation step. In FIG. 1, the feed to be treated is introduced into isomerisation zone R1 via line 1. Substantially pure hydrogen is introduced into line 1 via line 12 and recycled hydrogen is introduced into line 1 via line 13. Hydrogen which circulates in line 13 is purged via line 15. The effluent from isomerisation zone R1 is sent to a separation zone S1 via line 2. In S1, hydrogen contained in the effluent is isolated and recycled to the inlet to isomerisation zone R1 via line 13, the remaining effluent being evacuated from this separation zone S1 via line 3. The fluid contained in line 3 is heated in an oven F1 then evacuated therefrom via line 4. The effluent leaving the oven is enriched in recycled hydrogen via line 14 then it is introduced into dehydrogenation zone R2. The effluent from zone R2 is sent via line 5 to separation zone S2.

Abstract: The present invention relates to a process for preparing propene by metathesis of olefins.

Abstract: Process for the production of linear alkylaromatic hydrocarbons comprising: a) dehydrogenating C10-C14 n-paraffins; b) selectively hydrogenating the diolefins produced during step (a); c) feeding stream (b) and an aromatic hydrocarbon to an alkylation unit; d) distilling the alkylated stream into its main constituents; e) subjecting a paraffinic stream containing aromatic by-products, leaving step (d), to a hydrogenation step; f) recycling the stream leaving step (e) to the dehydrogenation unit of step (a).

Abstract: A method for improving the operation of a propane-propylene splitter in a process for the dehydrogenation of propane wherein the propane is dehydrogenated to produce a stream containing propylene and trace quantities of methyl acetylene and propadiene compounds and which stream is selectively hydrogenated to selectively saturate at least a majority of the trace quantities of methyl acetylene and propadiene compounds. The resulting effluent from the selective hydrogenation zone is fractionated in a propane-propylene splitter to produce a high-purity propylene product stream, an unconverted propane stream which is introduced to the dehydrogenation zone and a small slip stream or side-cut containing methyl acetylene and propadiene compounds which is introduced into the selective hydrogenation zone.

Abstract: A cyclic process for the purification of a diolefin hydrocarbon stream produced in a naphtha steam cracker to produce a high quality diolefin hydrocarbon stream having extremely low levels of acetylene over an extended period because of the ability to readily cyclically regenerate catalyst contained in an off-line selective hydrogenation reaction zone. The spent or partially spent catalyst is contacted with a stream containing naphtha and hydrogen to restore at least a portion of the fresh catalyst activity by the extraction of polymer compounds therefrom.

Abstract: A separation arrangement for a cumene process that operates with a relatively wet feed to an alkylation zone and relatively dry feed to a transalkylation zone reduces utilities and capital expenses for the separation and recycle of distinct wet and dry components by using an arrangement that first separates effluent from the trans alkylation and alkylation reaction zone in a benzene column before performing light ends and drying in a downstream depropanizer column. The arrangement uses a portion of the net overhead stream from the benzene column as a wet recycle stream for return to the alkylation reaction zone and sends another portion of the benzene net overhead to the depropanizer to supply a dry benzene recycle for the trans alkylation reaction zone.

Abstract: A process for producing 2,6-dialkylnaphthalene from a hydrocarbon feedstock that contains at least one component selected from the group consisting of dialkylnaphthalene isomers, monoalkylnaphthalene isomers, polyalkylnaphthalenes, and naphthalene, is provided that includes the following steps:I. separating the hydrocarbon feedstock and/or a dealkylation product fed from step III into a naphthalene fraction, a monoalkylnaphthalene fraction, a dialkylnaphthalene fraction and a remaining products fraction;II. separating and purifying 2,6-dialkylnaphthalene from the dialkylnaphthalene fraction of step I;III. dealkylating the hydrocarbon feedstock and/or the remaining products fraction of step I and feeding the dealkylation product to step I; andIV. alkylating the naphthalene and monoalkylnaphthalene fractions of step I;wherein the hydrocarbon feedstock is fed to step I or step III.

Abstract: A process for producing alkyl aromatics using a transalkylation reaction zone and an alkylation reaction zone is disclosed. The transalkylation reaction zone effluent passes to the alkylation reaction zone where aromatics in the transalkylation reaction zone effluent are alkylated to the desired alkyl aromatics. This process decreases the capital and operating costs of recycling the aromatics in the transalkylation reaction zone effluent. This process is well suited for solid transalkylation and alkylation catalysts. Ethylbenzene and cumene may be produced by this process.

Abstract: Process for the production of styrene which comprises:a) feeding to an alkylation unit a stream of benzene and a stream of recycled product containing ethylene;b) mixing the stream at the outlet of the alkylation unit, containing ethylbenzene, with a stream consisting of ethane;c) feeding the mixture thus obtained to a dehydrogenation unit containing a catalyst capable of contemporaneously dehydrogenating ethane and ethylbenzene;d) feeding the product leaving the dehydrogenation unit to a separation section to produce a stream essentially consisting of styrene and a stream containing ethylene;e) recycling the stream containing ethylene to the alkylation unit.

Abstract: This process for the production of heavy oligomers by a combination of dehydrogenation and oligomerization uses a bed of saturation catalyst in a debutanizer to simplify the saturation and recycle of C.sub.4 hydrocarbons to the dehydrogenation zone. The catalytic distillation zone is located in the top of the debutanizer column and may offer further efficiency improvements to the process when used in series with a bed of alkylation or oligomerization catalyst in the distillation zone. The bed of alkylation or oligomerization catalyst reduces the quantity of C.sub.4 hydrocarbons recycled to the dehydrogenation zone by oligomerizing unconverted C.sub.4 olefins in the distillation column. Conversion of C.sub.4 olefins in the distillation column facilitates the operation of the oligomerization zone at lower conversion conditions that favor production of high octane products.

Abstract: The present invention relates to a process of preparing dialkylnaphthylenes and polyalkylenenaphthyleneates.

Abstract: A thermosetting plastic foam solid formed from the reaction product of: (a) either polyisocyanate or isocyanate-based foam; (b) a polyol-based foam; (c) a catalyst which is capable of promoting the thermosetting reaction between the polyisocyanate or isocyanate-based foam and the polyol-based foam; and (d) a blowing agent which comprises a high purity cyclopentane product, wherein the high purity cyclopentane product is about 95% or greater pure cyclopentane, and, optionally, (e) water and/or (f) liquid flame retardant.

Abstract: The present invention relates to a process for the production of light olefins comprising olefins having from 2 to 4 carbon atoms per molecule from an oxygenate feedstock. The process comprises passing the oxygenate feedstock to an oxygenate conversion zone containing a metal alumninophosphate catalyst to produce a light olefin stream. The light olefin stream is fractionated and a portion of the products are metathesized to enhance the yield of the ethylene, propylene, and/or butylene products. Propylene can be metathesized to produce more ethylene, or a combination of ethylene and butene can be metathesized to produce more propylene. This combination of light olefin production and metathesis, or disproportionation provides flexibility to overcome the equilibrium limitations of the metal aluminophosphate catalyst in the oxygenate conversion zone. In addition, the invention provides the advantage of extended catalyst life and greater catalyst stability in the oxygenate conversion zone.

Abstract: A novel process is provided which integrates the cracking of hydrocarbon containing feedstocks with the olefins purification and olefins derivative process utilizing dilute olefin feedstocks.

Abstract: Integrated process for the production of butene-1 which comprises feeding a C.sub.4 hydrocarbon stream to a separation unit of butene-1 and recycling the remaining stream to the same unit after treatment in a bond isomerization section to convert the remaining butenes-2 into butene-1, a molecular sieve separation unit is inserted in the cycle operating with the hydrocarbons in a vapour phase, for the purge of the paraffins.

Abstract: The present invention relates to a process for the production of light olefins comprising olefins having from 2 to 4 carbon atoms per molecule from an oxygenate feedstock. The process comprises passing the oxygenate feedstock to an oxygenate conversion zone containing a metal aluminophosphate catalyst to produce a light olefin stream. A propylene stream and/or mixed butylene is fractionated from said light olefin stream and cracked to enhance the yield of ethylene and propylene products. This combination of light olefin product and propylene and butylene cracking in a riser cracking zone or a separate cracking zone provides flexibility to the process which overcomes the equilibrium limitations of the aluminophosphate catalyst. In addition, the invention provides the advantage of extended catalyst life and greater catalyst stability in the oxygenate conversion zone.

Abstract: There is provided a process for producing alkylaromatics, especially ethylbenzene and cumene, wherein a feedstock is first fed to a transalkylation zone and the entire effluent from the transalkylation zone is then cascaded directly into an alkylation zone along with an olefin alkylating agent, especially ethylene or propylene.

Abstract: A process is provided for the production of a gasoline blending fraction rich in isooctane by the dimerization of isobutylene using tertiary butyl alcohol modifier and isoalkane diluent; advantageously the isobutylene is derived from the dehydration of tertiary butyl alcohol and the isoalkane used as diluent in the dimerization is the product formed by hydrogenation of the oligomerization product.

Abstract: A process for the production of a diesel fuel includes contacting a feedstock comprising cracked stocks in the presence of hydrogen under conditions of elevated temperature and pressure with a first catalyst comprising a Group VI hydrogenation metal component and a Group VIII hydrogenation metal component on a substantially non-acidic carrier, and then contacting at least a portion of the effluent from the first catalyst with a second catalyst comprising a Group VI hydrogenation metal component and a Group VIII hydrogenation metal component on an acidic carrier. This process can produce diesel fuels having an improved cetane index and API gravity. The effluent from the second catalyst bed may be contacted with a third catalyst bed which contains a catalyst comprising a Group VI hydrogenation metal component and a Group VIII hydrogenation metal component on a substantially non-acidic carrier.

Abstract: A process combination is disclosed to selectively upgrade naphtha in accordance with expected trends leading to more-aliphatic gasolines. Such gasolines contain lower concentrations of aromatics and have lower end points with concomitant reduced harmful automotive emissions. The present process combination converts the higher-boiling portion of the naphtha, yields isobutane and other isoparaffins which are particularly suitable for upgrading or blending, and reduces cyclics in intermediate processing steps.

Abstract: A process for producing 2,6-dialkylnaphthalene from a hydrocarbon feedstock that contains at least one component selected from the group consisting of dialkylnaphthalene isomers, monoalkylnaphthalene isomers, polyalkylnaphthalenes, and naphthalene, is provided that includes the following steps: I. separating the hydrocarbon feedstock and/or a dealkylation product fed from step III into a naphthalene fraction, a monoalkylnaphthalene fraction, a dialkylnaphthalene fraction and a remaining products fraction; II. separating and purifying 2,6-dialkylnaphthalene from the dialkylnaphthalene fraction of step I; III. dealkylating the hydrocarbon feedstock and/or the remaining products fraction of step I and feeding the dealkylation product to step I; and IV. alkylating the naphthalene and monoalkylnaphthalene fractions of step I; wherein the hydrocarbon feedstock is fed to step I or step III.