Impact of Sr Addition on Zirconia-Alumina-Supported Ni Catalyst for COx-Free CH4 Production via CO2 Methanation.

Zirconia-alumina-supported Ni (5Ni/10ZrO2+Al2O3) and Sr-promoted 5Ni/10ZrO2+Al2O3 are prepared, tested for carbon dioxide (CO2) methanation at 400 °C, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, surface area and porosity, infrared spectroscopy, and temperature-programmed reduction/desorption techniques. The CO2 methanation is found to depend on the dispersion of Nickel (Ni) sites as well as the extent of stabilization of CO2-interacted species. The Ni active sites are mainly derived from the reduction of 'moderately interacted NiO species'. The dispersion of Ni over 1 wt % Sr-promoted 5Ni/10ZrO2+Al2O3 is 1.38 times that of the unpromoted catalyst, and it attains 72.5% CO2 conversion (against 65% over the unpromoted catalyst). However, increasing strontium (Sr) loading to 2 wt % does not affect the Ni dispersion much, but the concentration of strong basic sites is increased, which achieves 80.6% CO2 conversion. The 5Ni4Sr/10ZrO2+Al2O3 catalyst has the highest density of strong basic sites and the highest concentration of active sites with maximum Ni dispersion. This catalyst displays exceptional performance and achieves approximately 80% CO2 conversion and 70% methane (CH4) yield for up to 25 h on steam. The unique acidic-basic profiles composed of strong basic and moderate acid sites facilitate the sequential hydrogenation of formate species in the COx-free CH4 route.

Elevated CO-free hydrogen productivity through ethanol steam reforming using cubic Co-Nanoparticles based MgO catalyst.

Hydrogen production through the processes of ethanol catalytic steam reforming (SR) is one of the promising routes due to its extensive yield that can be gained. However, catalyst deactivation (as a result of coke formation) is a major drawback in such a process. Therefore, this research work introduces efficient MgO supported Cubic cobalt oxide catalyst for the process of ethanol SR. This catalyst was successfully able to produce gases that have high contents of CO-free hydrogen was produced (above 78%) at 500°C and various flow rates of feed. This catalyst had also avoided coke formation at that temperature while attaining capture of the in-situ produced CO2 gas. The employment of an operating temperature beyond 500°C, during the SR process, could reduce the percentages of hydrogen (in products) to less than 55%. Such increases in the operational temperature could leave behind the detection of coke deposits onto the catalyst surface. The presence of these deposits was confirmed visually as well as via Raman spectroscopy.