Disclosed is a method for providing improved hydrogenation activity by pretreating a catalyst in a three-step manner before selective hydrogenation of unsaturated hydrocarbons in an aromatic fraction in the presence of an oxide-type bimetallic (particularly nickel-molybdenum) supported catalyst.

A process for isomerizing an aromatic cut containing at least one aromatic compound containing eight carbon atoms per molecule is described, comprising bringing said cut into contact with at least one catalyst comprising at least one metal from group VIII of the periodic classification of the elements, at least one zeolitic support comprising a zeolite selected from zeolites with structure type EUO and MOR, used alone or as a mixture, and at least one matrix, such that the specific surface area of the matrix in the zeolitic support of said catalyst is in the range 5 to 200 m.sup.2/g.

A process for isomerizing an aromatic cut containing at least one aromatic compound containing eight carbon atoms per molecule is described, comprising bringing said cut into contact with at least one catalyst comprising at least one metal from group VIII of the periodic classification of the elements, at least one zeolitic support comprising a zeolite selected from zeolites with structure type EUO and MOR, used alone or as a mixture, and at least one matrix, such that the specific surface area of the matrix in the zeolitic support of said catalyst is in the range 5 to 200 m.sup.2/g.

The present invention relates to a catalyst for isomerization of alkylated aromatics such as mixed xylenes, using xylene isomerization catalyst particles including post-framework modified USY zeolite in which zirconium atoms and/or titanium atoms and/or hafnium atoms form a part of a framework of an ultra-stable Y-type zeolite.

Systems and methods for processing a C.sub.3 and C.sub.4 hydrocarbon mixture have been disclosed. The C.sub.3 and C.sub.4 hydrocarbon mixture is first processed in an isomerization unit to isomerize n-butane to form isobutane. The resulting effluent stream from the isomerization unit comprising primarily isobutane and C.sub.3 hydrocarbons, collectively, is flowed into a separation unit configured to separate the effluent stream to form a C.sub.3 stream comprising C.sub.1 to C.sub.3 hydrocarbons and a C.sub.4 stream comprising primarily isobutane. The isobutane in the C.sub.4 stream is further dehydrogenated to form isobutene, which is further flowed into an MTBE synthesis unit as a feedstock for producing MTBE.

The present invention relates to a catalyst for isomerization of alkylated aromatics such as mixed xylenes, using xylene isomerization catalyst particles including post-framework modified USY zeolite in which zirconium atoms and/or titanium atoms and/or hafnium atoms form a part of a framework of an ultra-stable Y-type zeolite.

Para-xylene production processes are disclosed, with such processes being integrated with extractive distillation or other separation to effectively separate, for example to remove and recover, ethylbenzene and other components that co-boil with the isomers of xylene. This allows for xylene isomerization, downstream of the separation of para-xylene from its other isomers, to be operated under milder conditions (e.g., liquid phase, absence of added hydrogen) without the need for ethylbenzene conversion. The associated decreased yields of byproducts such as light gases and non-aromatic hydrocarbons, together with the generation of purified ethylbenzene having value for styrene monomer production, can significantly improve overall process economics.

Para-xylene production processes are disclosed, with such processes being integrated with extractive distillation or other separation to effectively separate, for example to remove and recover, ethylbenzene and other components that co-boil with the isomers of xylene. This allows for xylene isomerization, downstream of the separation of para-xylene from its other isomers, to be operated under milder conditions (e.g., liquid phase, absence of added hydrogen) without the need for ethylbenzene conversion. The associated decreased yields of byproducts such as light gases and non-aromatic hydrocarbons, together with the generation of purified ethylbenzene having value for styrene monomer production, can significantly improve overall process economics.

Alkyl-demethylation of C2+-hydrocarbyl substituted aromatic hydrocarbons can be utilized to treat one or more of a heavy naphtha reformate stream, a hydrotreated SCN stream, a C8 aromatic hydrocarbon isomerization feed stream, a C9+ aromatic hydrocarbon transalkylation feed stream, and similar hydrocarbon streams to produce additional quantity of xylene products.

Alkyl-demethylation of C2+-hydrocarbyl substituted aromatic hydrocarbons can be utilized to treat one or more of a heavy naphtha reformate stream, a hydrotreated SCN stream, a C8 aromatic hydrocarbon isomerization feed stream, a C9+ aromatic hydrocarbon transalkylation feed stream, and similar hydrocarbon streams to produce additional quantity of xylene products.