Abstract: The system and method for optimizing para-xylene production from a feed stream containing para-xylene, ortho-xylene, meta-xylene, ethylbenzene and non-aromatics propose directing the feed stream into an isomerization unit of the system rather than to a separator of the system to avoid causing a bottleneck at the separator and to initially remove ethylbenzene and non-aromatics from the feed stream. This system and method may further provide a reactor in the feed stream used in a pretreatment step, the reactor containing an isomerization catalyst in an amount sufficient to convert substantially all the ethylbenzene in the feed stream to benzene, which is immediately removed and to convert and remove non-aromatics therefrom to optimize equilibrium isomer concentration in the isomerization unit and substantially eliminate coking therein.

Abstract: This invention relates to a process and a chemical plant for the production primarily of paraxylene. In particular the process and chemical plant utilise zeolite membranes for enhanced paraxylene production.

Abstract: A process for isomerising aromatic compounds containing eight carbon atoms is described in which the catalyst used contains at least one zeolite with structure type EUO and a group VIII element. In FIG. 1, the feed to be isomerised is introduced into reactor R via line 1. This fresh feed is enriched via lines 6 and 11 with a mixture containing at least one compound selected from the group formed by paraffins containing eight carbon atoms, benzene, toluene and naphthenes containing eight carbon atoms. Hydrogen is added via line 15.

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: For isomerising aromatic compounds containing eight carbon atoms in the presence of hydrogen, a mixture containing compounds with a boiling point of about 80° C. to 135° C. comprising at least one paraffin containing eight carbon atoms, at least one naphthene containing eight carbon atoms, at least benzene and at least toluene is added to the feed before introducing it into the isomerisation reactor R via line 1. These additions are made by a recycle via line 6 or by adding fresh compounds via line 11, or be a combination of fresh and recycled compounds via lines 6 and 11. Hydrogen is added via line 15.

Abstract: A C.sub.8 aromatic feedstock is isomerized by an isomerization stage conducted at 320-380.degree. C. with a catalyst containing at least one EUO-structure-type zeolite and at least one metal of group VIII, to obtain an effluent containing isomerized alkyl aromatics and about 10-30% by weight of naphthenes. The effluent is then subjected to a dehydrogenation stage so as to convert the naphthenes to additional alkyl aromatics.

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: There are disclosed an industrially advantageous process for efficiently producing highly pure 2,6-dimethylnaphthalene (DMN) in high yield from a mixture of DMN by carrying out in turn, the steps of isomerizing a mixture of DMN in the presence of a catalyst; crystallizing the isomerization reaction product in the presence of a solvent (e.g.

Abstract: The present invention relates to a method of preparing 2,6-dimethylnaphthalene from a feed stream that contains hydrocarbons which contain dimethylnaphthalene isomers. The method includes the following steps:I. distillation and concentration of the dimethylnaphthalene isomers from the feed stream, to form a dimethylnaphthalene fraction,II. isomerization of the dimethylnaphthalene fraction to enrich the dimethylnaphthalene fraction in 2,6-dimethylnaphthalene, to form a 2,6-enriched dimethylnaphthalene fraction,III. purification of 2,6-dimethylnaphthalene from the 2,6-enriched dimethylnaphthalene fraction,wherein step II is conducted in the presence of a catalyst composition containing a synthetic zeolite characterized by an X-ray diffraction pattern including interplanar d-spacing (.ANG.)12.36.+-.10.411.03.+-.0.28.83.+-.10.146.18.+-.0.126.00.+-.0.104.06.+-.0.073.91.+-.0.013.42.+-.0.06,wherein the purification includes crystallization under pressure.

Abstract: A method for minimizing the loss of xylenes in an ethylbenzene conversion/isomerization process by adding toluene to the feedstock. The concentration of toluene in the feedstock is increased by co-feeding toluene or by recycling toluene separated from the ethylbenzene conversion reactor effluent. The increased toluene concentration reduces the loss of xylenes during the ethylbenzene conversion reaction and under preferred operating conditions increases the amount of xylenes in the product.

Abstract: A method for increasing the efficiency of xylene isomerization by using a two stage isomerization process. In the first stage of the process, a C.sub.9.sup.+ aromatics feedstock is subjected to ethylbenzene conversion and xylene isomerization. Non-C.sub.8 aromatics are removed from the effluent, which is then processed in a second stage of the process to remove para-xylene and isomerize the para-xylene depleted effluent. The effluent from the second stage isomerization unit is then recycled into the inlet of the second stage of the process and a slip stream from the para-xylene separator is recycled to the feedstock and to the effluent of the ethylbenzene conversion unit. In this way, the production of para-xylene is maximized. In a preferred embodiment, toluene is co-fed into the feedstock to minimize the loss of xylenes during the ethylbenzene conversion reaction.

Abstract: A process for producing highly pure 2,6-dimethylnaphthalene in a high yield from a mixture of dimethylnaphthalene isomers in the presence of a solvent, such as an aliphatic or alicyclic saturated hydrocarbon. Highly pure 2,6-dimethylnaphthalene can be produced steadily for a long time by filtering the 2,6-dimethylnaphthalene crystal precipitated by the crystallizing by using a filtration apparatus, such as a rotary vacuum filter, peeling-off the filtered cake from a filter cloth and cleaning the filter cloth with a solvent, at a temperature not lower than a filtration temperature.

Abstract: To continuously produce and separate high purity p-xylene from a C.sub.8 aromatic hydrocarbon charge, successive use is made in combination of (1) a stage of separating low-purity p-xylene (75 to 98%) by simulated moving bed adsorption chromatography; (2) a stage of purifying and washing the low-purity p-xylene by recrystallization (-25 to +10.degree. C.); (3) a stage of catalytic isomerization of the charge which has been p-xylene-depleted by the separating stage (1); and recovering an isomerate which is then recycled to the charge. The solvent for desorption in stage (1) and washing in stage (2) is advantageously toluene.

Abstract: Utilization of thermodynamic ratios to produce pure rac and pure meso isomers or a mixture thereof.

Abstract: A mixed aromatic stream is hydrotreated to remove olefins and fractionated to separate C.sub.9 + heavies in a distillation column reactor and the C.sub.8 and lighter material is fed to a selective adsorption unit where the para-xylene is removed. The para-xylene depleted raffinate therefrom may be subjected to isomerization to form additional para-xylene. The effluent from the isomerization can be fed to the distillation column reactor for hydrogenation of any olefins formed during the isomerization or directly to the adsorption unit.

Abstract: A process for producing alkylnaphthalene from a feedstock comprising isomers of dialkylnaphthalene and naphthalene by contacting the feedstock with a catalyst composition, in which the process comprising transalkylation between isomers of dialkylnaphthalene and naphthalene to produce monoalkylnaphthalene, and isomerization of dialkylnaphthalene, wherein the catalyst composition comprising a synthetic zeolite characterized by an X-ray diffraction pattern including interplanar d-spacing as set forth in Table A of the specification.

Abstract: An integrated three-column process for recovering hydrocarbon distillate products from a hydroprocessing or hydrocracking reactor effluent stream and a hydrocarbon distillate product recovery train are disclosed. According to the present recovery process, an effluent stream from the cracking reactor is cooled and separated into light and heavy phase streams. The heavy phase stream is depressurized and stripped of light end components in a steam stripping column. The light phase stream is further cooled to separate a liquid stream which is combined with the light ends from the stripper and fed to a debutanizer. A C.sub.4 -rich light end stream taken overhead from the debutanizer is condensed to produce LPG product stream(s). A C.sub.4 -lean heavy end stream removed from the bottoms of the debutanizer is combined with a heavy end bottoms stream from the stripper and fed to a fractionator for fractionation into product distillate streams such as light and heavy naphtha, jet fuel, diesel oil, and the like.

Abstract: Dimethylnaphthalenes are isomerized into 2,6-dimethylnaphthalene by utilizing hydrogen fluoride as a catalyst and straight chain saturated aliphatic hydrocarbons having carbon atoms in the range from 5 to 12 as the solvent. Isomerization to other undesirable isomers such as 2,7-dimethylnaphthalene and side reactions such as disproportionation are suppressed and a very high degree of the isomerization to 2,6-DMN can be attained.

Abstract: An economically advantageous process for preparing 2-methylnaphthalene is provided. The process comprises the steps of azeotropically distilling a 1-methylnaphthalene-containing oil with ethylene glycol to produce a denitrified oil; subjecting the denitrified oil to an isomerization to promote an isomerization from 1-methylnaphthalene to 2-methylnaphthalene and produce an isomerization product; and recovering 2-methylnaphthalene from the isomerization product. The process may further comprise the step of hydrodesulfurizing or hydrogenating a portion or all of the denitrified oil to produce a hydrodesulfurized or hydrogenated product so that the product alone or the product together with the non-hydrodesulfurized or hydrogenated oil can be subjected to the subsequent isomerization step. Catalytic life of the isomerization catalyst is markedly prolonged to enable a production of 2-methylnaphthalene at a high yield.

Abstract: A process is disclosed for the production of a desired xylene isomer, preferably paraxylene, and high quality benzene. The desired isomer (11) is recovered from the feed (1) and recycle (3) streams in a xylene separation zone (2). The raffinate (5) from the separation zone is passed into a catalytic xylene isomerization zone (6). The isomerization zone effluent stream is passed into a high severity transalkylation zone (14) which contains a catalyst comprising both a ZSM-5 zeolite and mordenite. Ethylbenzene in the feed stream is subjected to staged conversion in the two catalytic reaction zones to both xylenes and benzene. The overall ethylbenzene conversion efficiency is improved.

Abstract: A process is disclosed for the production of a desired xylene isomer, preferably paraxylene, and high quality benzene. The desired isomer is recovered from the feed and recycle streams in a xylene separation zone. The net effluent or raffinate from the separation zone is passed into a catalytic xylene isomerization zone. The isomerization zone effluent stream is passed into a high severity transalkylation zone. Ethylbenzene in the feed stream is subjected to staged conversion in the two catalytic reaction zones and thereby converted to both xylenes and benzene.

Abstract: An improved process for concentration, separation and formation of paraxylene of the type wherein a hydrocarbon feed such as reformate is subjected to solvent extraction, fractionation and then Parex adsorption to remove paraxylene. The adsorber raffinate is isomerized to produce more paraxylenes and then recycled to the adsorber to remove the newly formed paraxylenes from the isomerization. The improvement includes a step of removing a stream from the process, downstream of the isomerization and introducing this stream upstream of the solvent extraction so that the concentration of non-aromatic such as naphthenes and paraffins produced in the isomerization will be reduced.

Abstract: A process is disclosed for the production of high quality benzene and a desired xylene isomer, preferably paraxylene, from a mixture of C.sub.7 -plus alkylaromatic hydrocarbons. The desired xylene isomer is recovered by absorptive separation from a stream of two or three xylene isomers. The resultant isomer-depleted stream is passed into a transalkylation zone together with both feed and recycled toluene and C.sub.9 aromatic hydrocarbons instead of being passed into a xylene isomerization zone. Benzene and xylenes are fractionated from the transalkylation zone effluent stream, with the xylenes being passed into the absorptive separation zone. A nonmetal catalyst is employed in the transalkylation zone, which must be operated at high severity (high temperature) conditions.

Abstract: A method is disclosed for promoting isomerization of sym-octahydrophenanthrene (s-OHP) to sym-octahydroanthracene (s-OHA) in the presence of a catalyst provided by aluminum chloride or aluminum bromide, or a mixture of these two compounds. The rate of isomerization is increased by having the reaction run in the presence of an aryl phenone such as benzophenone.

Abstract: A method of preparing benzene and xylenes from catalysates of reforming of gasoline fractions comprising a mixture of aromatic C.sub.6 -C.sub.10 hydrocarbons and non-aromatic hydrocarbons which involves separation of a low-boiling fraction boiling out at a temperature of 90.degree.-108.degree. C. from a reforming catalysate by rectification. The remaining high-boiling fraction is processed in the presence of a hydrogen-containing gas at a temperature within the range of from 450.degree. to 600.degree. C. under a pressure of from 10 to 60 atm on a catalyst. The catalyst consists of 1 to 85% by weight of H-mordenite, 0.1 to 10% by weight of a hydrogenating component as which use might be made of oxides of metals of Group VI of the periodic system, sulphides of these metals, metals of Group VIII of the periodic system, sulphides thereof; the balance being a binder.

Abstract: A hydrocarbon mixture is fed to a system of adsorbents in a plug flow so as to form at least one displacement boundary in the system to accumulate the composition in the vicinity of the boundary. The process is simple to operate and suitable for separation of a hydrocarbon mixture containing components with similar physical and chemical properties such as a mixture of hydrocarbon isomers.