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: The invention concerns a catalyst comprising at least one zeolite with structure type EUO for example EU-1, at least partialy in its acid form, at least one matrix, and at least one metal from group VIII of the periodic table. the zeolite comprising silicon and at least one element T selected from the group formed by aluminium, iron, gallium and boron (preferably aluminium and boron), with a global Si/T atomic ratio over 5, the catalyst being characterized in that the dispersion of the group VIII metal is in the range 50% to 100%, limits included, and the macroscopic distribution coefficient of the group VIII metal is in the range 0.7 to 1.3, limits included, the catalyst having a mechanical strength such that the bed crush strength is more than 0.7 MPa. The invention also relates to the preparation of the catalyst and to the use of the catalyst in a process for isomerizing aromatic compounds containing 8 carbon atoms per molecule.

Abstract: In a process for the separation of p-xylene from a feed to be treated containing a mixture of xylenes and olefinic impurities, at least a portion of the feed is circulated in an enrichment zone (14) to enrich a first fraction (15) in p-xylene and provide a second fraction (18) which is depleted in p-xylene. The second fraction is circulated in an isomerisation zone (19) and an isomerate (20) is recovered which is recycled to the enrichment zone. At least a portion of the feed to be treated, the isomerate, or a mixture thereof is circulated in at least one selective hydrogenation zone (3) to partially remove the olefinic impurities and thereafter in at least one clay tretment zone (8) to remove additional olefinic impurities. An effluent is recovered which is sent to the enrichment zone.

Abstract: The invention concerns a process for isomerising a feed containing essentially hydrocarbons, preferably paraffins preferably containing 5 and/or 6 carbon atoms per molecule, in which said feed is treated in a distillation zone comprising an exhausting zone and a rectification zone associated with an isomerisation reaction zone, in the presence of an isomerisation catalyst and a gas stream containing hydrogen, characterized in that the reaction zone is at least partially internal to the distillation zone, and wherein the hydrogen-containing gas is fed by a dedicated gas distributor to the bottom of at least one catalytic bed within the isomerization reaction zone.

Abstract: The invention concerns a process for isomerizing a feed containing essentially hydrocarbons, preferably paraffins containing principally 4 to 8, preferably principally 4 to 6 and more preferably principally 5 and/or 6 carbon atoms per molecule, comprising a fractionation zone and at least two isomerization reaction zones, said process comprising carrying out the following steps:(1) sending the feed to a fractionation zone;(2) drawing off at least a portion of the liquid circulating in said zone, via at least two draw-off levels;(3) sending the major portion of the liquid drawn off in step (2) to at least two isomerization zones, each isomerization zone being associated with a draw-off level;(4) sending the major portion of the effluents from step (3) to the fractionation zone, substantially adjacent to the draw-off levels;(5) recovering an effluent from the fractionation zone.

Abstract: A process is described for the high-efficiency selective hydrogenation of an aromatic hydrocarbon cut which also contains monoolefinic hydrocarbons and polyolefinic and/or acetylenic hydrocarbons with a bromine number of 10000 to 100 mg per 100 g of product with an aromatic degree of conversion which is limited to a maximum of 0.15% by weight, the process being characterized in that the cut, which is at least partially in the liquid phase, is passed with hydrogen into a hydrogenation zone in contact with a catalyst containing 0.1% to 1% by weight (with respect to the support) of palladium, the catalyst having been treated before activation with at least one organic sulphur-containing compound to introduce 0.05% to 1% of sulphur (by weight with respect to the weight of the catalyst), the process being carried out at a temperature in the range 20.degree. C. to 25.degree. C., at a pressure of 4-50 bar, a GHSV of 0.2-25 h.sup.-1 and with a H.sub.2 /monoolefin +polyolefin and/or acetylenes ratio in the range 0.

Abstract: Disclosed is a process for the alkylation of an isoparaffin by an olefin in the presence of a catalyst. In the process, a portion of the isoparaffin recovered after extraction from the reaction zone (R) is recycled to the reaction zone and the feed is periodcally injected into the reaction zone while the recycled isoparafin fraction is continuously injected into the reaction zone.

Abstract: A process for the alkylation of at least one isoparaffin by at least one olefin in the presence of at least one solid acidic catalyst, characterized in that the major portion of the olefin is initially brought into contact with the catalyst in a complexing zone to form an olefin-catalyst complex in the presence of the isoparaffin, and in that the suspension of the complex in the isoparaffin is then sent to at least one alkylation reaction zone.

Abstract: The present invention concerns a catalyst comprising a porous organic or mineral support, preferably silica, and an acidic phase containing B(OSO.sub.2 CF.sub.3).sub.3 and at least one acid selected from the group formed by sulphuric acid (H.sub.2 SO.sub.4) and trifluoromethane sulphonic acid (CF.sub.3 SO.sub.3 H), the support having been impregnated by said acidic phase, said catalyst being such that it is constituted essentially by particles with an average diameter of between 0.1 and 150 .mu.m, such that the support, prior to its impregnation with said acidic phase, has a total pore volume of between 0.5 and 6 cm.sup.3 per gram and said catalyst being characterized in that said acidic phase contains:between 0.1 and 70% by weight of B(OSO.sub.2 CF.sub.3).sub.3 ;between 0 and 90% by weight of H.sub.2 SO.sub.4 ;between 0 and 90% by weight of CF.sub.3 SO.sub.3 H.

Abstract: The invention concerns a rejuvenation process for a solid catalyst for the alkylation of at least one isoparaffin by at least one olefin. The process is characterised in that the catalyst is rejuvenated in the reaction zone by circulating an isoparaffin-rich liquid fraction over the bed, said fraction originating from a zone for separating the reaction effluent extracted from the reaction zone.

Abstract: A catalyst comprising a porous organic or mineral support, preferably silica, and an acidic phase containing B(OSO.sub.2 CF.sub.3).sub.3 and at least one acid selected from the group formed by sulphuric acid (H.sub.2 SO.sub.4) and trifluoromethane sulphonic acid (CF.sub.3 SO.sub.3 H), said support having been impregnated with said acidic phase and said support prior to impregnation having a total pore volume of 0.1-0.6 cm.sup.3 /g, said catalyst being essentially constituted by particles with an average diameter of between 0.1 and 30 .mu.m, said catalyst being characterized in that said acidic phase contains:between 0.1 and 70% by weight of B(OSO.sub.2 CF.sub.3).sub.3 ;between 0 and 90% by weight of H.sub.2 SO.sub.4 ;between 0 and 90% by weight of CF.sub.3 SO.sub.3 H.is suitable for the catalytic alkylation of isobutane and/or isopentane in the presence of at least one olefin containing 2 to 6 carbon atoms per molecule, preferably 3 to 6 carbon atoms per molecule.