resumo
Nanosized MoO2 can be prepared by different protocols, which yield different morphologies of the nanoparticles. Among their many properties, they can serve as catalysts for styrene oxidation (among other olefins), which is an industrially relevant transformation. In this work, we prepared MoO2 nanosized catalysts by two slightly different hydrothermal protocols using ethylenediamine and either Fe2O3 or hydroquinone. When used in catalysis, kinetic data evidenced that depending on the synthesis protocol of MoO2, induction periods occur (for the catalyst prepared with hydroquinone) with obvious different kinetic profiles and, in addition, product selectivity was also affected. To gain some insight on what is behind these results of the catalytic activity, a combined approach of studies has been conducted. DRIFT and inelastic neutron scattering (INS) techniques were used to assess the adsorbed species at the surface of both the fresh (DRIFT and INS) and recovered (INS) catalysts. Results from this study showed that when hydroquinone was used, an organic shell coated the MoO2 nanoparticles, which negatively influenced the catalytic performance.
palavras-chave
HETEROGENEOUS CATALYSIS; MESOPOROUS MATERIALS; OXIDATION
categoria
Chemistry; Physics
autores
Nunes, CD; Rudic, S; Vaz, PD
nossos autores
Pedro Miguel Duarte Vaz
Colaboradoragradecimentos
The authors thank Fundacao para a Ciencia e a Tecnologia (FCT) through POCI and FEDER funding programmes (projects UID/MULTI/00612/2019 and EXPL/QEQ-QIN/1137/2013) for financial support, and the STFC Rutherford Appleton Laboratory for access to the ISIS Pulsed Neutron andMuon Source facility. We are grateful to the European Commission for support under the 7th Framework Programme through the 'Research Infrastructures' action of the 'Capacities' Programme, NMI3-II Grant number 283883. The authors also thank Bruce Hudson, from Syracuse University, USA, for measuring the spectrum of p-benzoquinone. The reviewers are also thanked for raising critical questions, which contributed to increasing the quality of this work.