Here we report on the first electrochemical fluorination exemplarily performed on perovskite type BaFeO2.5. A cell setup of the type BaFeO2.5 II La0.9Ba0.1F2.9 II MFx (with MFx being MgF2 and CeF3) was used to perform the reaction, charging the cell up to voltages of about 4 V. Formation of a compound of approximate composition BaFeO2.5F∼0.5 was observed, in agreement with diffraction studies of the independently performed chemically fluorinated compound using F2 gas, and also possessing a capacity which is close to the theoretical capacity of the material. This new method gives an alternative towards the use of highly reactive and toxic F2 gas, and provides potential in adjusting the chemical potential for oxidative chemical fluorinations.

The oxidation state of the active metal is an important factor for catalyst stability under dry and steam reforming conditions. This work explores the correlation of the oxidation state of the active metal with the coking behavior of alumina‐supported cobalt and nickel catalysts from a thermodynamic point of view. To this end, the thermodynamics of the oxidation of Co/γ‐Al2O3 and Ni/γ‐Al2O3 were investigated by using calculations at both standard and technical reforming conditions. It is shown that oxidation of nickel by water or CO2 cannot occur spontaneously under reforming conditions regardless of participation of the alumina support material because of the positive Gibbs reaction energies. Cobalt, in contrast, is more easily oxidized and may form CoAl2O4 through interaction with the support. This phase may react with surface carbon to regenerate the catalyst after carbon formation through thermal cracking of methane. A Mars–van Krevelen type reaction scheme is proposed to explain the higher coking resistance of cobalt compared to nickel.

Dry and steam reforming of methane is studied over Co-hexaaluminate as a prospective coking-resistant transition-metal catalyst. Kinetic measurements and X-ray diffraction investigations reveal that the formation of metallic Co and the activity of the catalyst are strongly affected by the gas composition. While co-feeding of H2 proves to be beneficial to the conversion of methane, decreasing the ratio of CH4 to the oxidant in the feed gas is found to be detrimental to the activity of the catalyst. A considerable inhibition effect is demonstrated particularly in the presence of H2O. As the local gas composition inside the reactor varies with conversion, axial changes in the degree of Co reduction are observed. A microkinetic model is proposed, which accounts for the varying fractions of oxidic and metallic Co by means of oxygen surface coverages, to perform steady-state reactor simulations. Strengths and weaknesses of the approach are critically evaluated by comparing experimental and simulation results.

Chemical bonding in and electronic structure of lithium and magnesium rhodium hydrides are studied theoretically using DFT methods. For Li3RhH4 with planar complex RhH4 structural units, Crystal Orbital Hamilton Populations reveal significant Rh−Rh interactions within infinite one-dimensional ∞ 1 [RhH4] stacks in addition to strong rhodium−hydrogen bonding. These metal−metal interactions are considerably weaker in the hypothetical, heavier homologue Na3RhH4. Both compounds are small-band gap semiconductors. The electronic structures of Li3RhH6 and Na3RhH6 with rhodium surrounded octahedrally by hydrogen, on the other hand, are compatible with a classical complex hydride model according to the limiting ionic formula (M+)3[RhH6]3− without any metal−metal interaction between the 18-electron hydridorhodate complexes. In MgRhH, building blocks of the composition (RhH2)4 are formed with strong rhodium−hydrogen and significant rhodium−rhodium bonding (bond lengths of 298 pm within Rh4 squares). These units are linked together to infinite two-dimensional layers ∞ 2 [(RhH2/2)4] via common hydrogen atoms. Li3RhH4 and MgRhH are accordingly examples for border cases of chemical bonding where the classical picture of hydridometalate complexes in complex hydrides is not sufficient to properly describe the chemical bonding situation.