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- The influence of multiwalled carbon nanotubes and graphene oxide additives on the catalytic activity of 3d metal catalysts towards 1-phenylethanol oxidationPublication . Da Costa Ribeiro, Ana Paula; Fontolana, Emmanuele; Alegria, Elisabete; Kopylovich, Maximilian; Bertani, Roberta; Pombeiro, Armando3d metal (Cu, Fe, Co, V) containing composite catalysts for the solvent-free microwave-assisted trans-formation of 1-phenylethanol to acetophenone with tert-butyl hydroperoxide (TBHP) as oxidant wereprepared by ball milling. The influence of multiwalled carbon nanotubes (CNTs) and graphene oxide (GO)additives on the catalytic activity of the catalysts was studied. CNTs or GO were mixed by ball millingwith the metal salts (CoCl2), oxides (CuO, Fe2O3, V2O5) or binary systems (Fe2O3-CoCl2, CoCl2-V2O5, CuO-Fe2O3). For CoCl2-based catalytic systems, addition of small amounts (0.1–5%) of CNTs or GO leads tosignificant improvement in catalytic activity, e.g. 1% of the CNTs additive allows to rise yields from 28to 77%, under the same catalytic conditions. The CoCl2-5%CNTs composite is the most active among thestudied ones with 85% yield and TON of 43 after 1 h
- Ball milling as an effective method to prepare magnetically recoverable heterometallic catalysts for alcohol oxidationPublication . Fontolan, Emmanuele; Alegria, Elisabete; Da Costa Ribeiro, Ana Paula; Kopylovich, Maximilian; Bertani, Roberta; Pombeiro, ArmandoHeterometallic double Fe2O3–CoCl2, CoCl2–V2O5, MoO3–V2O5, and triple CuO–Fe2O3–CoCl2 3d metal dispersed systems were easily prepared by ball milling at room temperature and characterized by scanning electron microscopy (SEM), field emission gun scanning electron microscopy (FEGSEM), energydispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). They catalyze the microwave-assisted solvent-free heterogeneous oxidation of 1-phenylethanol to acetophenone with tert-butyl hydroperoxide (t-BuOOH) as oxidant, used as a model reaction. In most of the heterometallic systems a significant improvement in the catalytic activity was observed in comparison to homometallic ones. For the tested catalytic systems and experimental conditions, the CuO–Fe2O3–CoCl2 and Fe2O3–CoCl2 systems exhibit the highest activity with maximum 78% yield and TON 39 after 1 h. The possibility of magnetic recovery of the catalysts was demonstrated for the Fe2O3–CoCl2 (3:1) system.