Methane oxy-steam reforming reaction: performances of Ru/γ-Al2O3 catalysts loaded on structured cordierite monoliths

The in situ deposition of 1.5 wt.% Ru/γ-Al2O3 catalytic layers on cordierite monoliths (400 cpsi, diameter 1 cm, length 1.5 cm), combining Solution Combustion Synthesis (SCS) with Wet Impregnation (WI), was addressed. First of all, the physicochemical properties of the catalyst at powder level were investigated by X-ray Diffraction (XRD), N2 adsorption (BET), and H2 chemisorption, while the morphology of final structured catalysts was evaluated by SEM analysis and mechanical strength tests by sonication. The catalytic activity towards methane Oxy-Steam Reforming (OSR) reaction was studied after the choice of the most suitable catalyst load, carrying out tests varying the temperature (500 - 800°C), the oxygen-to-carbon ratio (O/C = 0.45 - 0.75, oxygen as moles), the steam-to-carbon ratio (S/C = 1.0 - 2.4), and the weight space velocity (WGS = 34,000 - 400,000 Nml gcat–1 h–1), in order to identify the optimum operative conditions. The results showed that a total catalytic layer load (active metal plus oxide carrier) equal to 6.5 mg cm–2 was enough to achieve excellent performances, while no substantial improvements were obtained at higher catalytic layer loads. Moreover, the coated Ru/γ-Al2O3 monolith exhibited a good catalytic activity towards the studied reaction also at considerably high WSV values (till 400,000 Nml gcat–1 h–1)

Preferential oxidation of carbon monoxide in hydrogen-rich streams over CuO/CeO2 catalysts: How nano (and subnano) structure affects catalytic activity and selectivity

Preferential oxidation of carbon monoxide in hydrogen-rich streams needs a suitable catalyst that selectively oxidizes CO avoiding H2 oxidation. Among the proposed catalysts, copper oxide supported on ceria (CuO/CeO2) received wide interest due to its intrinsic activity and selectivity and low cost with respect to noble metals. In particular, it has been shown that the performances are significantly affected by optimizing the copper-ceria interaction, and then the copper dispersion. In this light, reducing to nanoscale levels has been proven to be the solution. In this chapter, results of the effect of nano and subnano structures of CuO/CeO2 catalysts on the CO-PROX performance are reviewed and critically discussed. At nanosize, Cu dispersion and oxygen mobility are both enhanced. Furthermore, the copper reduction to the metallic Cu (H2 oxidation sites) is limited and CO2 desorption is activated at lower temperatures. The role of dopants and/or supports as graphene and carbon nanotubes in improving the intrinsic activity and the resistance to the inhibiting effect of carbon dioxide and water vapor are also discussed, highlighting the effect of dopants on the modification of the redox properties by increasing bulk and/or surface oxygen vacancies