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The subject of the research is features of synthesis of alumina cements on the basis of compositions of system CaO – CoO – Al2O3 – MoO3 with use of cobalt‐molybdenum‐containing waste for reception of refractory materials with a complex of the set properties. The processes of phase formation in raw mixtures have been investigated. X‐ray phase studies of clinkers fired at different temperatures and holding times proved that as a result of the interaction of the raw materials of the mixture in the material synthesizes a mixture of hydraulically active calcium mono‐ and di‐aluminate and refractory cobalt spinel, which provides the resulting complex high strength, accelerated curing time, fire resistance. The absence of phases corresponding to molybdenum compounds is explained by the fact that they are part of hydraulically active aluminates as limited solid solutions, deforming the crystal lattice and increasing hydraulic activity. Thus, it was found that the high strength of cement is due to the presence of calcium hydroaluminates such as C2AH8, aluminum hydroxide, as well as unhydrated grains of calcium aluminates, which will contribute to further long‐term strength. It is this coexistence of phases in both the crystalline and colloidal states provide high strength cement stone. [ABSTRACT FROM AUTHOR]

Cesium-promoted cobalt spinel is promising as a catalyst for the low-temperature decomposition of nitrous oxide for use in the second stage of a single-reactor unit for the combined removal of nitrogen oxides. This work studied the effect of the conditions for the preparation of granular and block bulk catalysts based on Co3O4 by extrusion molding. [ABSTRACT FROM AUTHOR]

Mechanistic investigations based on a combination of periodic-DFT+U and first principle thermodynamic modeling combined with IR and catalytic isotopic studies were used to ascertain the pathways of CO-PROX reaction over cobalt spinel nanocube catalyst. Structural, energetic, electronic, and magnetic characteristics of all surface intermediates (O 2 /O, H 2 , H 2 O, CO, CO 2 , CO 3 adspecies) interacting single octahedral and tetrahedral (Cotet and Cooct) and double (Cotet‿Cooct and Cooct‿Cooct) active sites, was determined and their thermodynamic stabilities and mechanistic role were established. For the bare surface, CO and H 2 oxidation were modeled based on an intrafacial Mars-van Krevelen mechanism, with the activation barriers of Δ E a = 1.21 for CO and 1.71 eV for H 2. For the surface covered with different monoatomic oxygen species (Cotet 2 C -O and Cooct 5 C -O), various variants of the Eley-Rideal scheme of direct CO and H 2 oxidation mechanisms were examined. These processes exhibit lower activation energies (Δ E a = 0.65 for CO and 1.11 eV for H 2) than the intrafacial ones but are controlled by demanding prior dissociation of O 2. The most stable in the CO-PROX conditions diatomic oxygen species give rise to the formation of Cotet-CO 3 2--Cooct and Cooct-CO 3 2--Cooct carbonate adspecies (with Δ E a = 0.42 and 0.35 eV, respectively), observed in IR. The Cotet-CO 3 2--Cooct adduct being more stable acts as a spectator (CO 2 release occurs with Δ E a = 1.21 eV), whereas the less stable Cooct-CO 3 2--Cooct, as a key CO-PROX reaction intermediate (Δ E a of CO 2 release equals to 0.81 eV). The prime role of the carbonate intermediates was substantiated by the isotopic experiments of the CO-PROX reaction over the Co 3 O 4 nanocubes using 18O 2 as an oxidant. [Display omitted] [ABSTRACT FROM AUTHOR]