MODEL COMPOUNDS FOR LIGHT CYCLE OIL CONVERSION

The reaction of dimethyl- and trimethylbenzenes with dibenzothiophene (DBT), phenanthrene, and a number of other polynuclear aromatics chara cteristic of light-cycle oils (LCOs) has been explored over zeolites Z SM-5, Y, and Beta. In catalyzing the reaction between trimethylbenzene and DBT, for example, zeolites Y and Beta yielded methyl-substituted DBTs in greater than 80% selectivity at DBT conversion levels exceedin g 90%. With smaller ring structures, e.g., in the reaction between m-x ylene and benzothiophene, ZSM-5 was similarly effective (but somewhat more prone to aging). It was also shape-selective in its product distr ibution. Transmethylation provides a simple and effective synthesis ro ute to the polymethyl polynuclear aromatics and thiophenes (PNAs and P NTs, respectively) needed in the reaction between m-xylene and benzoth iophene, ZSM-5 was similarly effective (but somewhat more prone to agi ng). It was also shape-selective in its product distribution. Transmet hylation provides a simple and effective synthesis route to the polyme thyl polynuclear aromatics and thiophenes (PNAs and PNTs, respectively ) needed in the search for improved catalytic routes to very low sulfu r distillate and other clean fuels products.