▎ 摘　　要

NOVELTY - Method for separating and purifying trimethylbenzene from 9C heavy aromatics comprises (i) performing alkylation reaction of 9C heavy aromatics under action of methanol as alkylation reagent, nitrogen atmosphere and alkylation catalyst, where the alkylation catalyst is a niobium oxide material supported by graphene/porous magnesium/aluminum metal oxide composite nanosheets, (ii) putting alkylated solvent in a rectifying tower for vacuum distillation, collecting 90-150 degrees C/750 mmHg fractions, subjecting the collected fractions to dealkylation reaction in presence of steam in a tubular furnace reactor, and (iii) putting the above-mentioned dealkylated solvent in a cryogenic crystallizer, reducing the temperature, performing cryogenic treatment, centrifuging, melting solid, adding to the cryogenic crystallizer, cooling to -30 to -40 degrees C at a rate of 0.005-0.01 degrees C/minute, performing cryogenic treatment for 1-2 hours, and centrifuging to obtain trimethylbenzene crystals. USE - The method is useful for separating and purifying trimethylbenzene from 9C heavy aromatics. ADVANTAGE - The method provides trimethylbenzene with high yield and high purity. DETAILED DESCRIPTION - Method for separating and purifying trimethylbenzene from 9C heavy aromatics comprises (i) performing alkylation reaction of 9C heavy aromatics under action of methanol as alkylation reagent, nitrogen atmosphere and alkylation catalyst, where the alkylation catalyst is a niobium oxide material supported by graphene/porous magnesium/aluminum metal oxide composite nanosheets, (ii) putting alkylated solvent in a rectifying tower for vacuum distillation, collecting 90-150 degrees C/750 mmHg fractions, subjecting the collected fractions to dealkylation reaction in presence of steam in a tubular furnace reactor, and (iii) putting the above-mentioned dealkylated solvent in a cryogenic crystallizer, reducing the temperature to -80 to -100 degrees C at a rate of 0.1-0.15 degrees C/minute, performing cryogenic treatment for 1-2 hours, centrifuging, melting the solid obtained by centrifugation, adding to cryogenic crystallizer, cooling down to -50 to -60 degrees C at a rate of 0.03-0.05 degrees C/minute, performing cryogenic treatment for 1-2 hours, centrifuging, melting solid obtained by centrifugation, adding to the cryogenic crystallizer, cooling to -30 to -40 degrees C at a rate of 0.005-0.01 degrees C/minute, performing cryogenic treatment for 1-2 hours, and centrifuging to obtain trimethylbenzene crystals.