Combinatorial screening of heterogeneous catalysts in selective oxidation of naphthalene by laser-induced fluorescence imaging

Heterogeneous catalysis is one of the most important processes in the petroleum and the chemical industries. To be able to screen catalysts at high throughput will dramatically improve performance and reduce costs. Here we used laser-induced fluorescence imaging as a high-throughput screening technique in the combinatorial discovery of active catalysts for naphthalene oxidation. Binary catalysts of V-Mo-O, V-Sn-O, V-Ti-O, and V-W-O in various 15-member libraries were screened. Laser ablation ICPMS was employed to confirm the composition of the individual catalysts in the combinatorial library. The addition of MoO₃, WO₃, SnO₂, and TiO₂ to V₂O₅ did not improve the catalytic activity in the conversion of naphthalene to naphthoquinone, but the overall activity was found to increase for certain binary samples. The screening of ternary catalysts of V-Sn-Mo-O revealed that the combination of V (45%)-Sn (45%)-Mo (10%) gave 70% higher catalytic activity than pure V₂O₅ in converting naphthalene to naphthoquinone. Reaction temperature and sample preparation effects on the activity and selectivity of catalysts are also studied in a combinatorial manner.