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 method for producing hydrocarbons is proposed wherein a catalysis product stream (b) rich in n-butane, isobutane, 1-butene, 2-butene, isobutene and hydrocarbons with more than four and/or less than four carbon atoms is produced in a catalysis unit (1), using one or more catalyst feed streams containing oxygenates and/or olefins (a) and wherein additionally a steam cracking product stream (h) is produced in a steam cracking unit (2) using one or more steam cracking feed streams (g, r, s). It is provided that using the catalysis product stream (b) a skeletal isomerisation feed stream (f, q) poor in 1-butene, 2-butene and isobutene and containing at least isobutane is produced, in which the isobutane is at least predominantly reacted by skeletal isomerisation to form n-butane, and which is subsequently used at least partly as the, or one of the, steam cracking feed streams (g, r). The invention also relates to an apparatus (100, 200).

A method for producing hydrocarbons is proposed wherein a catalysis product stream (b) rich in n-butane, isobutane, 1-butene, 2-butene, isobutene and hydrocarbons with more than four and/or less than four carbon atoms is produced in a catalysis unit (1), using one or more catalyst feed streams containing oxygenates and/or olefins (a) and wherein additionally a steam cracking product stream (h) is produced in a steam cracking unit (2) using one or more steam cracking feed streams (g, r, s). It is provided that using the catalysis product stream (b) a skeletal isomerisation feed stream (f, q) poor in 1-butene, 2-butene and isobutene and containing at least isobutane is produced, in which the isobutane is at least predominantly reacted by skeletal isomerisation to form n-butane, and which is subsequently used at least partly as the, or one of the, steam cracking feed streams (g, r). The invention also relates to an apparatus (100, 200).

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.

A method for the recovery paraxylene with reduced crystallization. Paraxylene is recovered from a mixture of C8 aromatic hydrocarbons in a pressure swing adsorption zone and a crystallization zone. The invention provides for lower throughput through the crystallization zone, resulting in lower capital costs, reduced electricity in operating separation equipment, as well as reduced refrigeration duty.

A method for recovering paraxylene from a mixture of aromatic hydrocarbons. The process uses a pressure swing adsorption zone followed by a paraxylene recovery zone. The invention provides for lower throughput through the paraxylene recovery zone, resulting in lower capital costs and operating costs.

A method for recovering paraxylene from a mixture of aromatic hydrocarbons. The process uses a pressure swing adsorption zone followed by a paraxylene recovery zone. The invention provides for lower throughput through the paraxylene recovery zone, resulting in lower capital costs and operating costs.

Methods for utilizing carbon dioxide to produce multi-carbon products are disclosed. The systems and methods of the present disclosure involve: reducing CO.sub.2 to produce a first product mixture comprising an alcohol product mixture comprising one or more alcohols and a paraffin product mixture comprising one or more paraffins; dehydrating the alcohol product mixture to form an olefin product mixture comprising one or more olefins; oligomerizing the olefin product mixture to form a higher olefin product mixture comprising unsaturated paraffins and optionally aromatics; and reducing the higher olefin product mixture to form a higher hydrocarbon product mixture comprising unsaturated paraffins and optionally aromatics. Catalyst materials and reaction conditions for individual steps are disclosed to optimize yield for ethanol or jet fuel range hydrocarbons.

A method for the recovery paraxylene with reduced crystallization. Paraxylene is recovered from a mixture of C8 aromatic hydrocarbons in a pressure swing adsorption zone and a crystallization zone. The invention provides for lower throughput through the crystallization zone, resulting in lower capital costs, reduced electricity in operating separation equipment, as well as reduced refrigeration duty.