RESUMO
The catalytic hydrogenation of CO2 to methane is one of the highly researched areas for the production of chemical fuels. The activity of catalyst is largely affected by support type and metal-support interaction deriving from the special method during catalyst preparation. Hence, we employed a simple solvothermal technique to synthesize Ni-based catalysts with different supports and studied the support role (CeO2, Al2O3, ZrO2, and La2O3) on structure-activity relationships in CO2 methanation. It is found that catalyst morphology can be altered by only changing the support precursors during synthesis, and therefore their catalytic behaviours were significantly affected. The Ni/Al2O3 with a core-shell morphology prepared herein exhibited a higher activity than the catalyst prepared with a common wet impregnation method. To have a comprehensive understanding for structure-activity relationships, advanced characterization (e. g., synchrotron radiation-based XAS and photoionization mass spectrometry) and in-situ diffuse reflectance infrared Fourier transform spectroscopy experiments were conducted. This research opens an avenue to further delve into the role of support on morphologies that can greatly enhance catalytic activity during CO2 methanation.
RESUMO
Natural materials are gaining interest as coating feedstock because their "quality to cost" ratio is better and they are more environmentally friendly than most of the synthetic ceramics. They give sufficient protection to metal surfaces against harsh conditions such as corrosion, wear, and high temperature. In the current study, chromite mineral was beneficiated and reduced to two different sizes to be used as feedstock material for thermal spray coating. Powders were upgraded by gravity and magnetic separation, respectively, and thermally sprayed onto mild steel samples by using atmospheric plasma spray (APS) equipment. Morphology, structure, phases, elemental distribution of chromite powder, and coatings were studied using field emission scanning electron microscopy, X-ray diffraction, X-ray fluorescence spectroscopy, and energy-dispersive X-ray spectroscopy. Tribological properties of APS chromite coatings were investigated by using a ball-on-disk tribometer, and corrosion resistance properties were evaluated by carrying out potentiodynamic polarization testing in 3.5% NaCl solution. It is observed that the coating has better wear and corrosion resistance and is worn by abrasive wear that includes scratching and particles pull out. Coating efficiency, surface morphology, and microhardness of the coating developed by fine powder were better than those of coarse powder coating.
