Search

Several Cu and Ni-based catalysts were synthetized over Ce-based supports, either pure or mixed with different amounts of alumina (1:2 and 1:3 mol/mol). Different metal loadings (10–40 wt%) and preparation methods (wet impregnation, co-precipitation, and flame-spray pyrolysis—FSP) were compared for the oxidative steam reforming of methanol. Characterization of the catalysts has been performed, e.g., through XRD, BET, XPS, TPR, SEM, and EDX analyses. All the catalysts have been tested in a bench-scale continuous setup. The hydrogen yield and methanol conversion obtained have been correlated with the operating conditions, metal content, crystallinity of the catalyst particles, total surface area, and with the interaction of the metal with the support. A Cu loading of 20% wt/wt was optimal, while the presence of alumina was not beneficial, decreasing catalyst activity at low temperatures compared with catalysts supported on pure CeO2. Ni-based catalysts were a possible alternative, but the activity towards the methanation reaction at relatively high temperatures decreased inevitably the hydrogen yield. Durability and deactivation tests showed that the best-performing catalyst, 20% wt. Cu/CeO2 prepared through coprecipitation was stable for a long period of time. Full methanol conversion was achieved at 280 °C, and the highest yield of H2 was ca. 80% at 340 °C, higher than the literature data. [ABSTRACT FROM AUTHOR]

Solar-boosted photo-technology stands out as a powerful strategy for photosynthesis and photocatalytic processes due to its minimal energy requirements, cost-effectiveness and operation under milder, environmentally friendly conditions compared to conventional thermocatalytic options. The design and development of photocatalysts have received a great deal of attention, whereas photoreactor development must be studied deeper to enable the design of efficient devices for practical exploitation. Furthermore, scale-up issues are important for this application, since light distribution through the photoreactor is a concurrent factor. This review represents a comprehensive study on the development of photoreactors to be used mainly for the photoreduction of CO2 to fuels, but with concepts easily transferable to other photosynthetic applications such as ammonia synthesis and water splitting, or wastewater treatment, photovoltaics combined to photoreactors, etc. The primary categories of photoreactors are thoroughly examined. It is also explained which parameters influence the design of a photoreactor and next-generation high-pressure photoreactors are also discussed. Last but not least, current technologies for solar concentrators are recalled, considering their possible integration within the photoreactor. While many reviews deal with photocatalytic materials, in the authors' view, photoreactors with significant scale and their merged devices with solar concentrators are still unexploited solutions. These are the key to boost the efficiency of these processes towards commercial viability; thus, the aim of this review is to summarise the main findings on solar photoreactors for the photoreduction of CO2 and for related applications. [ABSTRACT FROM AUTHOR]