RESUMO
Rare-earth orthoferrites have found wide application in thermocatalytic reduction-oxidation processes. Much less attention has been paid, however, to the production of CeFeO3, as well as to the study of its physicochemical and catalytic properties, in particular, in the promising process of CO2 utilization by hydrogenation to CO and hydrocarbons. This study presents the results of a study on the synthesis of CeFeO3 by solution combustion synthesis (SCS) using various fuels, fuel-to-oxidizer ratios, and additives. The SCS products were characterized by XRD, FTIR, N2-physisorption, SEM, DTA-TGA, and H2-TPR. It has been established that glycine provides the best yield of CeFeO3, while the addition of NH4NO3 promotes an increase in the amount of CeFeO3 by 7-12 wt%. In addition, the synthesis of CeFeO3 with the participation of NH4NO3 makes it possible to surpass the activity of the CeO2-Fe2O3 system at low temperatures (300-400 °C), as well as to increase selectivity to hydrocarbons. The observed effects are due to the increased gas evolution and ejection of reactive FeOx nanoparticles on the surface of crystallites, and an increase in the surface defects. CeFeO3 obtained in this study allows for achieving higher CO2 conversion compared to LaFeO3 at 600 °C.
RESUMO
Correction for 'Catalyst supports based on ZnO-ZnAl2O4 nanocomposites with enhanced selectivity and coking resistance in isobutane dehydrogenation' by Anna N. Matveyeva et al., Dalton Trans., 2022, 51, 12213-12224, https://doi.org/10.1039/d2dt02088b.
RESUMO
Development of coking resistant supports and catalysts for hydrocarbons conversion is challenging, especially when using such acidic materials as alumina. Apparently, this problem can be mitigated by using spinels that are less acidic, being, however, thermally stable. In this study, a series of ZnO-ZnAl2O4 nanocomposites with different ZnO loading were prepared by urotropine-nitrate combustion synthesis to be used as supports for isobutane dehydrogenation catalysts. The nanocomposites were characterized by XRD, SEM, N2-physisorption analysis, EDS, H2-TPR, TPD of NH3 and tested in isobutane dehydrogenation. Spinels with small amounts of ZnO displayed higher acidity and specific surface areas than samples with a higher ZnO content (30-40 mol%). At the same time, the maximum activity and the lowest selectivity to by-products (CH4 and C3H6) after 10 min of the reaction were observed for the nanocomposite containing 20 mol% of ZnO. The obtained nanocomposites have demonstrated better resistance to coking compared to commercial alumina.
