Abstract: The present invention relates to new crystalline molecular sieve SSZ-75 prepared using a tetramethylene-1,4-bis-(N-methylpyrrolidinium)dication as a structure-directing agent, and its use in catalysts for hydrocarbon conversion reactions.

Abstract: A method of treating a ZSM-5-type zeolite catalyst is carried out by treating a ZSM-5 zeolite catalyst having a silica/alumina mole ratio of at least about 200 with a phosphorus compound. The phosphorus-treated ZSM-5 zeolite catalyst is calcined and steamed. Steaming of the catalyst is carried out at a temperature of less than about 300° C. The phosphorus-treated ZSM-5 zeolite catalyst has less than 0.05% by weight of the catalyst of any other element other than phosphorus provided from any treatment of the ZSM-5 zeolite with a compound containing said other element. The catalyst may be used in aromatic alkylation by contacting the catalyst with feed of an aromatic hydrocarbon and an alkylating agent within a reactor under reactor conditions suitable for aromatic alkylation. Water cofeed may be introduced water into the reactor during the aromatic alkylation reaction.

Abstract: A process is described for producing phenylalkanes by alkylating at least one aromatic compound using at least one linear olefin containing 9 to 16 carbon atoms per molecule. The alkylation reaction is carried out in the presence of at least two different catalysts used in at least two distinct reaction zones. The selectivity for a monoalkylated products of the catalyst contained in the first reaction zone is lower than that for the catalyst contained in the second reaction zone located downstream of the first in the direction movement of the fluids.

Abstract: Disclosed is an alkylation reactor for preparing ethylbenzene. The reactor comprises a monolith catalyst system that includes a monolith support impregnated or co-formed with a catalyst suitable to catalyze the alkylation of benzene with ethylene. The catalyst may be selected from, for example, zeolites such as beta zeolite and MCM-22 zeolite, and fixed super acids. Also disclosed is a method of preparing ethylbenzene by alkylating a mixture of benzene and ethylene in an alkylation reactor comprising a monolith catalyst system, including a monolith support impregnated or co-formed with a suitable catalyst. In one embodiment the invention provides a convenient means of upgrading an existing reactor that has previously been used for conventional liquid phase alkylations such as those catalyzed by aluminum trichloride. The inventive alkylation method may be effectively and advantageously carried out under critical or near critical conditions, if desired.

Abstract: An alkylating process for the production of at least one of 2-, 3-, 4-, 5-, and 6-phenylalkanes by alkylation of an aromatic compound with a feedstock containing at least one olefin comprising at least 9 carbon atoms per molecule, in the presence of a catalyst comprising at least one substrate based on at least a zeolite and a non-zeolitic silica-alumina matrix with a low content of macropores, whereby said matrix contains an amount of more than 5% by weight and less than or equal to 95% by weight of silica (SiO2), whereby said process is carried out at a temperature of between 30 and 400° C., a pressure of between 0.1 and 10 MPa, an hourly volumetric flow rate of 0.50 to 200 h?1, and an aromatic compound/olefin molar ratio of between 1:1 and 50:1.

Abstract: The present invention provides a process for producing an alkylaromatic compound comprising the step of contacting an alkylatable aromatic compound with an alkylating agent under alkylation conditions in the presence of a alkylation catalyst comprising phosphorus and a porous crystalline inorganic oxide material having an X-ray diffraction pattern including the d-spacing maxima at 12.4±0.25, 6.9±0.15, 3.57±0.07 and 3.42±0.07 Angstrom.

Abstract: A process for the catalytic alkylation of monocyclic aromatic compounds in a hydrocarbon process stream comprising contacting the monocyclic aromatic compound-containing hydrocarbon process stream with an alkylation agent under alkylation conditions with a mesoporous zeotype catalyst having an intracrystalline, non-crystallographic mesopore system and a mesopore volume of the zeotype crystals above 0.25 ml/g.

Abstract: The present invention relates to a novel oxidative coupling arenes with olefins to yield aryl alkenes, which uses ruthenium (Ru) or Osmium (Os) compounds as catalysts.

Abstract: A method of converting methanol to a xylene product is achieved by providing a reactor containing a non-steamed, phosphorus-treated ZSM-5-type zeolite catalyst. The catalyst is contacted with a toluene/methanol feed under reactor conditions suitable for the methylation of toluene. Water cofeed is introduced into the reactor during the methylation reaction under conditions that provide substantially no structural aluminum loss of the catalyst from such introduction of water to provide a selectivity for methanol of at least 40%.

Abstract: The invention relates to a process for producing alkylated aromatic hydrocarbons, preferably with an oxygen or sulfur containing alkylating agent, in the presence of a multi-component molecular sieve catalyst composition that includes a molecular sieve and an active metal oxide. The invention is also directed to methods of making and formulating the multi-component molecular sieve catalyst composition useful in producing alkylated aromatics.

Abstract: A process for the production of ethylbenzene by the ethylation of benzene in the critical phase over a molecular sieve aromatic alkylation catalyst. An aromatic feedstock having a benzene content of at least 90 wt. % is supplied into a reaction zone into contact with a zeolite beta alkylation catalyst having a silica/alumina ratio within the range of 20-500, specifically 50-150. The alkylation catalyst is a zeolite beta specifically a lanthanum-modified zeolite beta. Ethylene is supplied to the reaction zone to provide a benzene/ethylene mole ratio of 1-15. The reaction zone is operated under conditions in which benzene is in the supercritical phase to produce an alkylation product containing ethylbenzene as a primary product with heavier alkylated by-products of no more than 60 wt. % of the ethylbenzene. The alkylation product is recovered from the reaction zone and supplied to a separation and recovery zone to separate ethylbenzene from a polyalkylated component including diethylbenzene.

Abstract: A process for the alkylation of aromatics with olefins using a solid catalyst bed containing UZM-8 zeolite is disclosed. A polyalkylated aromatic is passed to the catalyst bed to reduce the concentration of the olefin at alkylation conditions. A portion of the effluent recovered from the catalyst bed may be recycled to the catalyst bed. Such operation can decrease the catalyst deactivation rate and the formation of diphenylalkanes. The process disclosed herein is applicable to processes for the production of a wide variety of commercially important alkylated aromatics, including ethylbenzene and cumene.

Abstract: A process for the regeneration of a deactivated zeolite beta catalyst such as rare earth promoted zeolite beta catalyst deactivated in the course of an aromatic alkylation reaction. A zeolite beta conversion catalyst deactivated with the deposition of coke is heated to a temperature in excess of 300° C. in an oxygen-free environment. An oxidative regeneration gas is supplied to the catalyst bed with oxidation of a portion of a relatively porous coke component to produce an exotherm moving through the catalyst bed. At least one of the temperature and oxygen content of the gas is progressively increased to oxidize a porous component of the coke. Regeneration gas is supplied having at least one of an increased oxygen content or increased temperature to oxidize a less porous refractory component of the coke. The regeneration process is completed by passing an inert gas through the catalyst bed at a reduced temperature.

Abstract: A method of making a crystalline molecular sieve of MFS framework type, said method comprising the steps of (a) adding at least one source of ions of tetravalent element (Y), at least one source of ions of trivalent element (X), at least one hydroxide source (OH?), at least one structure-directing-agent (R), at least one seed source (Seed), and water (H2O) to form a mixture having the following mole composition (expressed in term of oxide): YO2:(n)X2O3:(x)OH?:(y)R:(z)H2O+(m)Seed wherein the m is in the range of from about 10 wtppm to about 2 wt. % (based on total weight of the synthesis mixture), the n is in the range of from about 0.005 to 0.05, the x is in the range of from about 0.01 to about 0.3, the y is in the range of from about 0.

Abstract: An MCM-22 family molecular sieve having an X-ray diffraction pattern of the as-synthesized MCM-22 family molecular sieve including d-spacing maxima at 12.4±0.25, 3.57±0.07 and 3.42±0.07 Angstroms and at least one peak between 26.6° and 29° (2?). The peak between 26.6° to 29° (2?) has a two theta (2?) of about 26.9°. A method of manufacturing an MCM-22 family molecular sieve, said method comprising the steps of (a) combining at least one silicon source, at least one source of alkali metal hydroxide, at least one directing-agent (R), water, and optionally one aluminum source, to form a mixture having the following mole composition: Si:Al2=10 to infinity H2O:Si=1 to 20 OH?:Si=0.001 to 2 M+:Si=0.001 to 2 R:Si=0.001 to 0.34 wherein M is an alkali metal; (b) treating said mixture at crystallization conditions for less than 72 hr to form a treated mixture having said MCM-22 family molecular sieve, wherein said crystallization conditions comprises a temperature range from about 160° C. to about 250° C.

Abstract: The invention relates to a crystalline molecular sieve composition which is obtainable by crystallizing a pre-formed extrudate mixture in a reactor and, during crystallization, removing excess alkali metal hydroxide from the pre-formed extrudate. The pre-formed extrudate mixture comprises at least one source of ions of tetravalent element Y, at least one source of alkali metal hydroxide, water, optionally at least one seed crystal, and optionally at least one source of ions of trivalent element X. The reaction mixture has the following mole composition: Y:X2=10 to infinity; OH?:Y=0.001 to 2; and M+:Y=0.001 to 2; wherein M is an alkali metal. The amount of water in the mixture is at least sufficient to permit extrusion of said reaction mixture.

Abstract: A method of manufacturing a molecular sieve of the MCM-22 family, said method comprising the steps of (a) providing a mixture comprising at least one source of ions of tetravalent element, at least one source of alkali metal hydroxide, at least one directing-agent (R), water, and optionally at least one source of ions of trivalent element, said mixture having the following mole composition: Y:X2=10 to infinity H2O:Y=1 to 20 OH?:Y=0.001 to 2 M+:Y=0.001 to 2 R:Y=0.001 to 0.34 wherein Y is a tetravalent element, X is a trivalent element, M is an alkali metal; (b) treating said mixture at crystallization conditions for less than 72 hr to form a treated mixture having said molecular sieve, wherein said crystallization conditions comprise a temperature in the range of from about 160° C. to about 250° C.; and (c) recovering said molecular sieve.

Abstract: A method of crystallizing a crystalline molecular sieve having a pore size in the range of from about 2 to about 19 ?, said method comprising the steps of (a) providing a mixture comprising at least one source of ions of tetravalent element (Y), at least one hydroxide source (OH?), and water, said mixture having a solid-content in the range of from about 15 wt. % to about 50 wt. %; and (b) treating said mixture to form the desired crystalline molecular sieve with stirring at crystallization conditions sufficient to obtain a weight hourly throughput from about 0.005 to about 1 hr?1, wherein said crystallization conditions comprise a temperature in the range of from about 200° C. to about 500° C. and a crystallization time less than 100 hr.

Abstract: A method of preparing a crystalline molecular sieve is provided, which method comprises (a) providing a reaction mixture comprising at least one source of ions of tetravalent element Y, at least one source of alkali metal hydroxide, water, optionally at least one seed crystal, and optionally at least one source of ions of trivalent element X, said reaction mixture having the following mole composition: Y:X2=10 to infinity OH?:Y=0.001 to 2 M+:Y=0.001 to 2 wherein M is an alkali metal and the amount of water is at least sufficient to permit extrusion of said reaction mixture; (b) extruding said reaction mixture to form a pre-formed extrudate; and (c) crystallizing said pre-formed extrudate under vapor phase conditions in a reactor to form said crystalline molecular sieve whereby excess alkali metal hydroxide is removed from the pre-formed extrudate during crystallization. The crystalline molecular sieve product is useful as catalyst in hydrocarbon conversion processes.

Abstract: This invention relates to a method for separating a stream having benzene, toluene and alkyl benzene, said method comprising: feeding the stream into a first distillation column, wherein the stream comprises between about 60 mole percent to about 85 mole percent toluene, between about seven mole percent to about 20 mole percent benzene, and between about seven mole percent to about 20 mole percent alkyl benzene; separating the steam into a first mixture stream and a second mixture stream; feeding the first mixture stream and the second mixture stream into a distillation system; separating the first mixture stream and the second mixture stream into a first product stream, a system recycle stream, and a second product stream.

Abstract: A catalyst for use in aromatic alkylation, such as toluene alkylation with methanol, is comprised of a zeolite with pore size from about 5.0 to about 7.0 ? containing a hydrogenating metal. The catalyst may be used in preparing an alkyl aromatic product by providing the catalyst within a reactor. The catalyst may be contacted with an aromatic hydrocarbon and an alkylating agent in the presence of hydrogen under reaction conditions suitable for aromatic alkylation. The catalyst may also be treated to further increase its stability. This is accomplished by heating the hydrogenating metal loaded zeolite catalyst in the presence of a reducing agent prior to use in an aromatic alkylation reaction to a temperature of from about 400° C. to about 500° C. for about 0.5 to about 10 hours.

Abstract: Methods of forming ethylbenzene are described herein. In one embodiment, the method includes contacting dilute ethylene with benzene in the presence of an alkylation catalyst to form ethylbenzene, wherein such contact occurs in a liquid phase reaction zone and recovering ethylbenzene from the reaction zone.

Abstract: A process for producing an alkylaromatic compound includes contacting a dilute olefin feed with a lean oil stream containing aromatic compound and alkylaromatic compound in an absorption zone to provide an alkylation reaction stream containing aromatic compound, alkylaromatic compound and olefin. The alkylation reaction stream is reacted under alkylation reaction conditions in an alkylation reaction zone to provide an effluent containing the aromatic compound and alkylaromatic compound. The effluent of step is separated into the lean oil stream which is recycled to the absorption zone and a product portion from which an alkylaromatic product is recovered.

Abstract: The invention relates to a process for the production of phenylalkanes comprising an alkylation reaction of at least one aromatic compound by at least one linear olefin having from 9 to 16 carbon atoms per molecule. Said reaction is carried out in a catalytic reactor in which n reaction zones are present each containing at least one same solid acid catalyst, n being greater than or equal to 2, and at the inlet to each of which at least one fraction of the total quantity of olefins necessary for said reaction is introduced. The phenylalkanes obtained by the process according to the invention are particularly suitable for manufacturing detergents.

Abstract: A method for the manufacture of polycarbonate by combining methane and inlet water to produce methanol, converting the methanol to propylene, gasoline aromatics, and gasoline olefins, converting the propylene and gasoline olefins to hydrogen, first benzene, and toluene, reacting the first benzene with propylene to form cumene, reacting the cumene with oxygen to form cumene hydroperoxide, cleaving the cumene hydroperoxide to produce acetone and phenol, reacting the phenol, additional phenol, and acetone to produce a dihydric aromatic compound, and reacting the dihydric aromatic compound with a carbonate precursor to form polycarbonate.

Abstract: A method of continuously producing polyalkylbiphenyls involves reacting biphenyl and an olefin in the presence of a solid acid catalyst to obtain a reaction mixture containing monoalkylbiphenyls and dialkylbiphenyls, separating a fraction containing biphenyl and at least a part of the monoalkylbiphenyls, circulating the separated fraction to the reactor such that the ratio of biphenyls to monoalkylbiphenyls is designed to be 0.1 or more and is designed to be less than the soluability of biphenyl to monoalkylbiphenyl at a circulation temperature, and recovering polyalkylbiphenyls.

Abstract: This invention related to an improved process for preparation of cumene. More particularly, the present invention relates to a process for the preparation of cumene using catalytic membrane reactors. The membrane used in the process facilitates reaction in a forward direction such that byproduct formation is reduced or eliminated.

Abstract: A method of modifying a zeolite catalyst to increase selectivity of the catalyst is achieved by dissolving alumina in a phosphorus-containing acid solution, and treating the zeolite catalyst with the dissolved alumina solution. A method of preparing an aromatic product, such as a xylene product, is also achieved by contacting the modified zeolite catalyst with an aromatic hydrocarbon, such as toluene, and an alkylating agent, such as methanol, under reaction conditions suitable for aromatic alkylation. For xylene products the aromatic hydrocarbon may be toluene and the reaction conditions may be suitable for at least one of toluene methylation and transalkylation.

Abstract: The process disclosed herein is a process for producing phenyl-alkanes by alkylation of an aryl compound with an olefinic compound and which uses a mordenite catalyst and a silica-alumina catalyst. The selectivity of the process to 2-phenyl-alkanes can be varied over a wide range.

Abstract: A process is provided for the production of xylenes from reformate by reactive distillation. The process is carried out by methylating the benzene/toluene present in the reformate in a reactive distillation zone and under reactive distillation conditions to produce a resulting product having a higher xylenes content than the reformate. Greater than equilibrium amounts of para-xylene can be produced by the process.

Abstract: The present invention is directed to novel alkylated aromatic compositions, zeolite catalyst compositions and processes for making the same. The catalyst compositions comprise zeolite Y and mordenite zeolite having a controlled macropore structure. The present invention is also directed to the preparation of the catalyst compositions and their use in the preparation of novel alkylated aromatic compositions. The catalyst compositions of the present invention exhibit reduced deactivation rates during the alkylation process, thereby increasing the life of the catalysts.

Abstract: A process is provided for the production of xylenes from reformate. The process is carried out by methylating under conditions effective for the methylation, the benzene/toluene present in the reformate outside the reforming loop, to produce a resulting product having a higher xylenes content than the reformate. Greater than equilibrium amounts of para-xylene can be produced by the process.

Abstract: A process is described for the valorization of a charge of hydrocarbons and for reducing the vapour pressure of said charge, comprising three steps: a step a) consisting of separating said charge of hydrocarbons into a fraction (O1) comprising essentially compounds containing 5 carbon atoms, including at least 2% by weight of pentenes, a step b) consisting of placing said fraction (O1) in contact with a cut of hydrocarbons (O2) at least partly comprising hydrocarbons having a number of carbon atoms between 6 and 10, including at least 2% by weight of olefins, and a step c) consisting of separating the effluents originating from step b) into a gasoline cut (?) the upper distillation point of which is less than 100° C. and a kerosene cut (?) having a distillation range between 100° C. and 300° C.

Abstract: Hydrocarbon or oxygenate conversion process in which a feedstock is contacted with a non zeolitic molecular sieve which has been treated to remove most, if not all, of the halogen contained in the catalyst. The halogen may be removed by one of several methods. One method includes heating the catalyst in a low moisture environment, followed by contacting the heated catalyst with air and/or steam. Another method includes steam-treating the catalyst at a temperature from 400° C. to 1000° C. The hydrocarbon or oxygenate conversion processes include the conversion of oxygenates to olefins, the conversion of oxygenates and ammonia to alkylamines, the conversion of oxygenates and aromatic compounds to alkylated aromatic compounds, cracking and dewaxing.

Abstract: In a process for preparing an olefinic hydrocarbon mixture comprising at least 5% by weight of mono-olefin oligomers of the empirical formula: CnH2n where n is greater than or equal to 6, a feedstock comprising n-butene and propylene in a molar ratio of about 1:0.01 to about 1:0.49 is contacted under oligomerization conditions with surface deactivated ZSM-23. The resultant mono-olefin oligomers comprise at least 20 percent by weight of olefins having at least 12 carbon atoms, wherein said olefins having at least 12 carbon atoms have an average of from about 0.8 to about 2.0 C1–C3 alkyl branches per carbon chain.

Abstract: The invention relates to a process for producing alkylated aromatics, preferably ethylbenzene, in a multiple bed reactor in which at least two catalysts, each comprising a molecular sieve, are used in sequential beds. The first alkylation catalyst is selected to have a higher activity or alpha value than the subsequent alkylation catalyst.

Abstract: A process is provided for the production of xylenes from reformate. The process is carried out by methylating under conditions effective for the methylation, the benzene/toluene present in the reformate outside the reforming loop, to produce a resulting product having a higher xylenes content than the reformate. Greater than equilibrium amounts of para-xylene can be produced by the process.

Abstract: A novel crystalline aluminophosphate and metalloaluminophosphate of the molecular sieve type, denominated SSZ-51, is prepared by hydrothermal synthesis from reactive sources of aluminum and phosphorus, fluorine and an organic templating agent, 4-dimethylaminopyridine. SSZ-51 is useful in catalysts for, e.g., hydrocarbon conversion reactions.

Abstract: A repeated “soak and dry” selectivation process for preparing a modified metallosilicate catalyst composite is disclosed comprising of a mixture of amorphous silica, alumina and a pore size controlled metallosilicate useful for alkylaromatic conversion. The process comprises (a) contacting an intermediate pore metallosilicate with an organosilicon compound in a solvent for a specific duration and then recovering the solvent, (b) combining the organosilicon compound treated metallosilicate with water and then drying the catalyst, (c), repeating the steps a) and b) above and (d) calcining the catalyst in an oxygen containing atmosphere sufficient to remove the organic material and deposit siliceous matter on the metallosilicate. In a another embodiment, when the organosilicon compound is water soluble, step (b) may be avoided.

Abstract: The present invention relates to new molecular sieve SSZ-71 prepared using a N-benzyl-1,4-diazabicyclo[2.2.2]octane cation as a structure-directing agent, methods for synthesizing SSZ-71 and processes employing SSZ-71 in a catalyst.

Abstract: Hydrocarbon conversion processes using a new family of zeolites identified as UZM-8 and UZM-8HS are described. The UZM-8 and UZM-8HS are related in that the UZM-8HS are derived from the UZM-8 zeolite by treating the UZM-8 with a fluoro-silicate salt, an acid, etc. The UZM-8 and -8HS have unique x-ray diffraction patterns. These zeolites can be used in alkylation of aromatics, transalkylation of aromatics, isomerization of aromatics and alkylation of isoparaffins.

Abstract: The present invention relates to new crystalline molecular sieve SSZ-65 prepared using 1-[1-(4-chlorophenyl)-cyclopropylmethyl]-1-ethyl-pyrrolidinium or 1-ethyl-1-(1-phenyl-cyclopropylmethyl)-pyrrolidinium cation as a structure-directing agent, methods for synthesizing SSZ-65 and processes employing SSZ-65 in a catalyst.

Abstract: A method of preparing a xylene product is carried out in a reactor containing a phosphorus-treated ZSM-5-type zeolite catalyst. The method includes initiating a unique start-up of a toluene methylation reaction by contacting the catalyst with a toluene/methanol feed and a cofeed of hydrogen introduced into the reactor at certain start-up conditions. By utilizing the start-up conditions high selectivity for p-xylene can be achieved while providing stable catalytic activity over extended periods.

Abstract: The present invention relates to new crystalline molecular sieve SSZ-70 prepared using a N,N?-diisopropyl imidazolium cation as a structure-directing agent, methods for synthesizing SSZ-70 and processes employing SSZ-70 in a catalyst.

Abstract: There is provided a process for aromatics conversion by contacting a feed suitable for aromatics conversion under conversion condition and in the presence of a catalyst comprising ITQ-13. Examples of such conversion processes include isomerization of aromatic (xylenes) feedstock, disproportionation of toluene to benzene and xylenes, alkylation and transalkylation of aromatics, conversion of light paraffins and light olefins to aromatics, conversion of naphtha to aromatics, and conversion of alcohol to aromatics.

Abstract: This invention provides novel stable metallic mesoporous transition metal oxide molecular sieves and methods for their production. The sieves have high electrical conductivity and may be used as solid electrolyte devices, e.g., in fuel cells, as sorbents, e.g. for hydrogen storage, and as catalysts. The invention also provides room temperature activation of dinitrogen, using the sieves as a catalyst, which permits ammonia production at room temperature.

Abstract: The present invention is directed to a mordenite zeolite catalyst having a controlled macropore structure. The present invention is also directed to a mordenite zeolite catalyst composite and a process for preparing the catalyst composite. The catalyst composite exhibits reduced deactivation rates during the alkylation process, thereby increasing the life of the catalyst.

Abstract: A method of preparing a xylene product is carried out by providing a reactor containing a non-steamed, phosphorus-treated ZSM-5-type zeolite catalyst. The catalyst is contacted with a toluene/methanol feed and a cofeed of hydrogen under reactor conditions suitable for the methylation of toluene. Water is introducing into the reactor during the methylation reaction under conditions that provide substantially no structural aluminum loss of the catalyst from such introduction of water.

Abstract: A process and system for the vapor phase alkylation of an aromatic substrate in a multi-stage alkylation reaction zone having a plurality of series-connected catalyst beds spaced from one another to provide mixing zones between adjacent catalyst beds. A feedstock containing an aromatic substrate and a C2–C4 alkylating agent is supplied to an inlet side of the reaction zone. The reaction zone is operated at conditions in which the aromatic substrate is in the gas phase and causing vapor phase alkylation of the aromatic substrate as the aromatic substrate and the alkylating agent flow through the reaction zone and pass from one catalyst bed to the next. A quench fluid comprising one or both of the aromatic substrate and the alkylating agent is supplied into the interior of the mixing zone through a plurality of flow paths in which one portion of the flow paths is directed upwardly within the mixing zone and another portion downwardly within the mixing 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; and IV. alkylating the naphthalene and monoalkylnaphthalene fractions of step I; wherein the hydrocarbon feedstock is fed to step I or step III.