A method of producing p-xylene, the method comprising the steps of converting the C9+ aromatic hydrocarbons and the hydrogen gas in the presence of a dealkylation catalyst to produce a dealkylation effluent, separating the dealkylation effluent to produce a carbon-nine (C9) aromatics stream, a xylene stream, and a toluene stream, separating the p-xylenes from the xylene stream in the p-xylene separation unit to produce a p-xylene product and a p-xylene depleted stream, converting the m-xylene and o-xylene in the p-xylene depleted stream in the isomerization unit to produce an isomerization effluent, reacting the C9 aromatics stream and the hydrogen stream in the presence of a transalkylation catalyst in the transalkylation reactor to produce a transalkylation effluent, separating the C6 to C9+ aromatic hydrocarbons in the isomerization effluent and the transalkylation effluent in the splitter column to produce a benzene recycle, a toluene recycle, a xylene recycle and a C9+ recycle.

In a process for separating dimethyl biphenyl isomers a mixture comprising one or more 3,3, 3,4- or 4,4-dimethyl biphenyl isomers, one or more 2,X-dimethyl biphenyl isomers (where X=2, 3, or 4) and one or more further hydrocarbon components is contacted with a first adsorbent, thereby selectively adsorbing one or more of the dimethyl biphenyl isomers within the first adsorbent. A first raffinate stream containing less selectively adsorbed components is withdrawn from the first adsorbent and a first extract stream containing selectively adsorbed dimethyl biphenyl isomers is withdraw. The selectively adsorbed dimethyl biphenyl isomers comprise one or more of 3,3-, 3,4- or 4,4-dimethyl biphenyl isomers and one or more of 2,X-dimethyl biphenyl isomers (where X=2, 3, or 4).

The present invention relates to a process and to a device for the separation of a feedstock comprising benzene, toluene and C8+ compounds, in which: a toluene column (C10) is fed directly with a C7+ cut resulting from the bottom of a stabilization column (C11) positioned downstream of a transalkylation unit (P4); a C7 cut is withdrawn at the top of the toluene column (C10) and a C8+ cut is withdrawn at the bottom; a benzene column (C9) is fed with the C7 cut resulting from the toluene column (C10); an essentially aromatic cut resulting from an aromatics extraction unit (P1) is injected into the toluene column (C10) separately above the feeding of the C7+ cut or into the benzene column (C9).

Systems and methods are provided for forming para-xylene from aromatics-containing streams having reduced or minimized amounts of C.sub.2+ side chains. Reduced or minimized amounts of C.sub.2+ side chains can provide benefits for improving and/or allowing modification of transalkylation conditions, xylene isomerization conditions, or a combination thereof. Such aromatics-containing streams can be formed, for example, by conversion of methyl halide, methanol, syngas, and/or dimethyl ether to aromatics by an aromatic conversion process. The methyl halide, methanol, syngas, and/or dimethyl ether can be formed by conversion of methane.

A method of producing p-xylene, the method comprising the steps of converting the C9+ aromatic hydrocarbons and the hydrogen gas in the presence of a dealkylation catalyst to produce a dealkylation effluent, separating the dealkylation effluent to produce a carbon-nine (C9) aromatics stream, a xylene stream, and a toluene stream, separating the p-xylenes from the xylene stream in the p-xylene separation unit to produce a p-xylene product and a p-xylene depleted stream, converting the m-xylene and o-xylene in the p-xylene depleted stream in the isomerization unit to produce an isomerization effluent, reacting the C9 aromatics stream and the hydrogen stream in the presence of a transalkylation catalyst in the transalkylation reactor to produce a transalkylation effluent, separating the C6 to C9+ aromatic hydrocarbons in the isomerization effluent and the transalkylation effluent in the splitter column to produce a benzene recycle, a toluene recycle, a xylene recycle and a C9+ recycle.

Processes and apparatuses for producing para-xylenes are provided. The processes comprises providing a hydrocarbon stream comprising C7+ hydrocarbons. The hydrocarbon stream is separated to provide a C8 aromatics stream and an ortho-xylene rich stream. The C8 aromatics stream is passed to a para-xylene separation unit for separating para-xylene to provide a para-xylene stream and a raffinate stream. At least a portion of the raffinate stream is passed to a first isomerization unit to provide a first isomerization effluent, wherein the first isomerization effluent is produced in the presence of an ethylbenzene (EB) isomerization catalyst. At least a portion of the ortho-xylene rich stream is contacted with an isomerization catalyst in a second isomerization unit in liquid phase at isomerization conditions in substantial absence of hydrogen to produce a second isomerization effluent.

Processes and apparatuses for producing para-xylenes are provided. The processes comprises providing a hydrocarbon stream comprising C7+ hydrocarbons. The hydrocarbon stream is separated to provide a C8 aromatics stream and an ortho-xylene rich stream. The C8 aromatics stream is passed to a para-xylene separation unit for separating para-xylene to provide a para-xylene stream and a raffinate stream. At least a portion of the raffinate stream is passed to a first isomerization unit to provide a first isomerization effluent, wherein the first isomerization effluent is produced in the presence of an ethylbenzene (EB) isomerization catalyst. At least a portion of the ortho-xylene rich stream is contacted with an isomerization catalyst in a second isomerization unit in liquid phase at isomerization conditions in substantial absence of hydrogen to produce a second isomerization effluent.

Methods for the production of para-xylene include flowing a xylenes-containing stream comprising PX, meta-xylene (MX), and ortho-xylene (OX), to a first crystallization stage. In addition, the methods include lowering a temperature of the xylenes-containing stream to below the eutectic point of the xylenes-containing stream within the first crystallization stage to crystallize at least some of the PX and at least some of one of both of the MX and the OX within the xylenes-containing stream. Further, the methods include separating the xylenes-containing stream into a first crystallization effluent stream and a first filtrate stream.

Methods for the production of para-xylene include flowing a xylenes-containing stream comprising PX, meta-xylene (MX), and ortho-xylene (OX), to a first crystallization stage. In addition, the methods include lowering a temperature of the xylenes-containing stream to below the eutectic point of the xylenes-containing stream within the first crystallization stage to crystallize at least some of the PX and at least some of one of both of the MX and the OX within the xylenes-containing stream. Further, the methods include separating the xylenes-containing stream into a first crystallization effluent stream and a first filtrate stream.

A process for the production of high purity toluene and para-xylene is described. More specifically, the process involves the production of high purity toluene produced via a light-desorbent selective adsorption process for para-xylene production, such as light desorbent para-xylene extraction, without the need for dedicated solvent extraction or olefin removal from the toluene stream.