A method of recovering paraxyiene in a pressure swing adsorption unit with varying hydrogen purge pressures. The pressure swing adsorption zone is adapted to adsorb and desorb paraxyiene based on the cycling of partial pressure in the zone. A first hydrogen purge fed to the zone is within 50 psi of the adsorption pressure of paraxyiene in the zone. A second hydrogen purge fed to the zone is within 50 psi of the desorption pressure of paraxyiene in the zone. The overall amount of hydrogen necessary to operate the pressure swing adsorption zone is reduced and heat may be recovered from the effluent leaving the pressure swing adsorption zone.

A method for producing para-xylene (PX) includes introducing a C.sub.8 aromatic-containing composition to a xylene rerun column to separate the C.sub.8 aromatic-containing composition into a xylene-containing effluent and a heavy effluent and passing the xylene-containing effluent to a PX processing loop that includes a PX recovery unit operable to separate a PX product from the xylene-containing effluent, a membrane isomerization unit operable to convert a portion of the MX, OX, or both from the xylene-containing effluent to PX, an EB dealkylation unit operable to dealkylate EB from the xylene-containing effluent to produce benzene, toluene, and other C.sub.7− compounds, and a membrane separation unit operable to produce a permeate that is PX-rich and a retentate that is PX-lean. The permeate is passed to the PX recovery unit for recovery of PX, which the retentate is bypassed around the PX recovery unit circulated through the xylene processing loop.

A transalkylation process co-feeds benzene at a relatively high proportion with C9+ aromatics in a feed stream to a transalkylation reactor. At lower proportions (≤5 wt %) of benzene, ring loss is greater for benzene than toluene and ring loss is increased by increasing the proportion of benzene in the feed stream. When the benzene is co-fed in a proportion sufficiently greater than 5 weight percent of the feed stream, ring loss is unexpectedly reduced.

Systems and methods are provided for integration of an aromatic formation process for converting non-aromatic hydrocarbon to an aromatic product and subsequent methylating of a portion of the aromatic product to produce a methylated product, with improvements in the aromatic formation process and/or the methylation process based on integrating portions of the secondary processing trains associated with the aromatic formation process and the methylation process. The aromatic formation process and methylation process can be used, for example, for integrated production of specialty aromatics or gasoline blending components.

Systems and methods are provided for integration of an aromatic formation process for converting non-aromatic hydrocarbon to an aromatic product and subsequent methylating of a portion of the aromatic product to produce a methylated product, with improvements in the aromatic formation process and/or the methylation process based on integrating portions of the secondary processing trains associated with the aromatic formation process and the methylation process. The aromatic formation process and methylation process can be used, for example, for integrated production of specialty aromatics or gasoline blending components.

A method of recovering paraxyiene in a pressure swing adsorption unit with varying hydrogen purge pressures. The pressure swing adsorption zone is adapted to adsorb and desorb paraxyiene based on the cycling of partial pressure in the zone. A first hydrogen purge fed to the zone is within 50 psi of the adsorption pressure of paraxyiene in the zone. A second hydrogen purge fed to the zone is within 50 psi of the desorption pressure of paraxyiene in the zone. The overall amount of hydrogen necessary to operate the pressure swing adsorption zone is reduced and heat may be recovered from the effluent leaving the pressure swing adsorption zone.

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.

A hydrocarbon conversion process is described. The process includes contacting in a reactor an inert gas with one or more catalyst compositions suitable for methylation of toluene and hydrogenation of phenol; contacting a reducing agent with the one or more catalyst compositions under conditions suitable for reducing metal oxide content of the catalyst composition; contacting at least part of toluene and/or benzene-containing with a oxygenate in the presence of the one or more catalyst compositions and under conditions effective to convert toluene to xylenes and produce a reactor effluent stream comprising para-xylene and having a lower concentration of phenol than the toluene-containing stream; separating at least one para-xylene-enriched stream from the reactor effluent stream; and separating from the at least one para-xylene enriched stream at least one toluene-enriched stream and at least one para-xylene-product stream. An apparatus for carrying out such a process is also described.

A hydrocarbon conversion process is described. The process includes contacting in a reactor an inert gas with one or more catalyst compositions suitable for methylation of toluene and hydrogenation of phenol; contacting a reducing agent with the one or more catalyst compositions under conditions suitable for reducing metal oxide content of the catalyst composition; contacting at least part of toluene and/or benzene-containing with a oxygenate in the presence of the one or more catalyst compositions and under conditions effective to convert toluene to xylenes and produce a reactor effluent stream comprising para-xylene and having a lower concentration of phenol than the toluene-containing stream; separating at least one para-xylene-enriched stream from the reactor effluent stream; and separating from the at least one para-xylene enriched stream at least one toluene-enriched stream and at least one para-xylene-product stream. An apparatus for carrying out such a process is also described.