Processes for converting aromatic hydrocarbons via alkyl-demethylation

A process for converting aromatic hydrocarbons, the process comprising:

• (I) providing a C6+ aromatic hydrocarbon-containing stream comprising a C2+-hydrocarbyl-substituted aromatic hydrocarbon, wherein the C2+-hydrocarbyl-substituted aromatic hydrocarbon has (i) a C2+ alkyl substitute attached to an aromatic ring therein and/or (ii) an aliphatic ring annelated to an aromatic ring therein;
• (II) optionally contacting the C6+ aromatic hydrocarbon-containing stream with a first alkyl-demethylation catalyst in a first alkyl-demethylation zone under a first set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon to an alkyl-demethylated aromatic hydrocarbon to obtain an optional first alkyl-demethylated effluent exiting the first alkyl-demethylation zone;
• (III) separating at least a portion of the C6+ aromatic hydrocarbon-containing stream and/or the first alkyl-demethylated effluent in a first separation apparatus to obtain a C6-C7 hydrocarbons-rich stream and a first C8+ aromatic hydrocarbons-rich stream;
• (IV) optionally contacting the first C8+ aromatic hydrocarbons-rich stream with a second alkyl-demethylation catalyst in a second alkyl-demethylation zone under a second set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon, if any, contained in the first C8+ aromatic hydrocarbons-rich stream to an alkyl-demethylated aromatic hydrocarbon to obtain an optional second alkyl-demethylated effluent exiting the second alkyl-demethylation zone;
• (V) separating at least a portion of the first C8+ aromatic hydrocarbons-rich stream and/or the second alkyl-demethylated effluent in a second separation apparatus to obtain a xylenes-rich stream and a C9+ aromatic hydrocarbons-rich stream;
• and
• (VI) optionally separating the xylenes-rich stream in a first p-xylene recovery sub-system to obtain a first p-xylene product stream and a first p-xylene depleted stream;
• wherein:
• at least one of steps (II) and (IV) is carried out;
• the first and/or the second sets of alkyl-demethylation conditions comprise a temperature in a range from 200 to 500° C.;
• an absolute pressure in a range from 350 to 2500 kilopascal;
• a molar ratio of molecular hydrogen to hydrocarbon in a range from 0.5 to 20;
• and a liquid weight hourly space velocity in a range from 1 to 20 hour−1;
• and
• the first and/or second alkyl-demethylation catalysts, the same or different, comprises a first metal element selected from groups 7, 8, 9, and 10 metals and combinations thereof, an optional second metal element different from the first metal element, an optional third metal element selected from Groups 1 and 2 elements, and a support.