Transalkylation processes for converting aromatic hydrocarbons comprising alkyl-demethylation

A process for converting aromatic hydrocarbons, the process comprising:

• (A) providing a C9+ aromatic hydrocarbon 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;
• (B) optionally contacting at least a portion of the C9+ aromatic hydrocarbon stream with an alkyl-demethylation catalyst No. 1 in an alkyl-demethylation zone No. 1 under a set of alkyl-demethylation conditions No. 1 to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon contained in the C9+ aromatic hydrocarbon stream to an alkyl-demethylated hydrocarbon to produce an alkyl-demethylated effluent No. 1 exiting the alkyl-demethylation zone No. 1;
• (C) optionally separating the C9+ aromatic hydrocarbons stream and/or the alkyl-demethylated effluent No. 1 in a separation device No. 1 to obtain a C9-C10 aromatic hydrocarbons-rich stream and a C11+ aromatic hydrocarbons-rich stream;
• (D) optionally contacting at least a portion of the alkyl-demethylated effluent No. 1 and/or at least a portion of the C9-C10 aromatic hydrocarbons-rich stream with an alkyl-demethylation catalyst No. 2 in an alkyl-demethylation zone No. 2 under a set of alkyl-demethylation conditions No. 2 to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbon, if any, contained in the alkyl-demethylated effluent No. 1 and/or the C9-C10 aromatic hydrocarbons-rich stream to an alkyl-demethylated hydrocarbon to produce an alkyl-demethylated effluent No. 2 exiting the alkyl-demethylation zone No. 2;
• (E) feeding at least a portion of the C9+ aromatic hydrocarbons stream, and/or at least a portion of the alkyl-demethylated effluent No. 1, and/or at least a portion of the C9-C10 aromatic hydrocarbons-rich stream, and/or at least a portion of the alkyl-demethylated effluent No. 2, and an optional benzene/toluene stream to a transalkylation zone;
• (F) contacting C9+ aromatic hydrocarbons with benzene/toluene in the presence of a transalkylation catalyst in the transalkylation zone under transalkylation conditions to produce a transalkylation effluent exiting the transalkylation zone;
• and
• (G) separating the transalkylation effluent in a separation device No. 2 to obtain an optional benzene product stream, a toluene-rich stream, and a C8+ aromatic hydrocarbons-rich stream;
• wherein:
• at least one of steps (B) and (D) is carried out;
• the set of alkyl-demethylation conditions No. 1 and the set of alkyl-demethylation conditions No. 2, the same or different, comprise at least one of:
• 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 alkyl-demethylation catalyst and/or the second alkyl-demethylation catalyst, the same or different, comprises a first metal element selected from groups 7, 8, 9, and 10 metals and combinations thereof, and a support.