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Horace’s second book of Satires (30 BCE), written in the troubled period around Actium, shows two big differences from Book 1. First, there is a new focus on the Saturnalia, which is the setting for both 2.3 and 2.7. This was traditionally a time for playful freedoms and festive self-indulgences (and had some affinities with satura itself). But second, Horace’s own already-humble persona becomes far less visible, and the original giver of diatribes now receives them from others. How do we resolve the contradiction? The reason why Horace de-carnivalized the Saturnalia is that his close friend Virgil recently engaged with Saturnus and the Golden Age in the Georgics (29 BCE). The Saturnalia could no longer be a straightforward revival of fun and freedom. Instead, at the dangerous birth of the Principate, Horace makes the Saturnalia another way to refract his satiric voice. Horace avoids talking about either a Golden Age or Saturn in his post-Aeneid poetry (Zanker 2010). I argue that this festive Saturnalian vision is already missing from Satires 2. The reason is the same. Virgil and Horace’s poetic projects, simultaneously fashioning Roman identity, had to move in parallel: crossing paths would be fatal to both.

Horace’s second book of Satires (30 BCE), written in the troubled period around Actium, shows two big differences from Book 1. First, there is a new focus on the Saturnalia, which is the setting for both 2.3 and 2.7. This was traditionally a time for playful freedoms and festive self-indulgences (and had some affinities with satura itself). But second, Horace’s own already-humble persona becomes far less visible, and the original giver of diatribes now receives them from others. How do we resolve the contradiction? The reason why Horace de-carnivalized the Saturnalia is that his close friend Virgil recently engaged with Saturnus and the Golden Age in the Georgics (29 BCE). The Saturnalia could no longer be a straightforward revival of fun and freedom. Instead, at the dangerous birth of the Principate, Horace makes the Saturnalia another way to refract his satiric voice. Horace avoids talking about either a Golden Age or Saturn in his post-Aeneid poetry (Zanker 2010). I argue that this festive Saturnalian vision is already missing from Satires 2. The reason is the same. Virgil and Horace’s poetic projects, simultaneously fashioning Roman identity, had to move in parallel: crossing paths would be fatal to both.

Metal promoted indium oxide (In2O3) catalysts are promising materials for CO2 hydrogenation to products such as methanol and carbon monoxide. The influence of the dispersion of the promoting metal on the methanol selectivity of In2O3 catalysts is a matter of debate, which centers around the role of atomically dispersed single metal atoms vs. metal clusters as catalysts for methanol formation. In this study, we used density functional theory calculations to compare the role of single atoms (SAs) of Ni, Pd, Pt and Rh placed on the In2O3(111) surface to study CO2 hydrogenation to CO and methanol. Direct and hydrogen-assisted CO2 dissociation pathways leading to CO as well as methanol formation via either formate or CO intermediates are explicitly considered. Microkinetic simulations show that all SA models mainly catalyze CO formation via a redox pathway involving oxygen vacancies where adsorbed CO2 dissociates followed by CO desorption and water formation. The higher barriers for hydrogenation of formate intermediates compared to the overall barrier for the rWGS reaction explain the negligible CH3OH selectivity.

Ni-promoted indium oxide (In2O3) is a promising catalyst for the selective hydrogenation of CO2 to CH3OH, but the nature of the active Ni sites remains unknown. By employing density functional theory and microkinetic modeling, we elucidate the promoting role of Ni in In2O3-catalyzed CO2 hydrogenation. Three representative models have been investigated: (i) a single Ni atom doped in the In2O3(111) surface, (ii) a Ni atom adsorbed on In2O3(111), and (iii) a small cluster of eight Ni atoms adsorbed on In2O3(111). Genetic algorithms (GAs) are used to identify the optimum structure of the Ni8 clusters on the In2O3 surface. Compared to the pristine In2O3(111) surface, the Ni8-cluster model offers a lower overall barrier to oxygen vacancy formation, whereas, on both single-atom models, higher overall barriers are found. Microkinetic simulations reveal that only the supported Ni8 cluster can lead to high methanol selectivity, whereas single Ni atoms either doped in or adsorbed on the In2O3 surface mainly catalyze CO formation. Hydride species obtained by facile H2 dissociation on the Ni8 cluster are involved in the hydrogenation of adsorbed CO2 to formate intermediates and methanol. At higher temperatures, the decreasing hydride coverage shifts the selectivity to CO. On the Ni8-cluster model, the formation of methane is inhibited by high barriers associated with either direct or H-assisted CO activation. A comparison with a smaller Ni6 cluster also obtained with GAs exhibits similar barriers for key rate-limiting steps for the formation of CO, CH4, and CH3OH. Further microkinetic simulations show that this model also has appreciable selectivity to methanol a

Indium oxide (In2O3) is a promising catalyst for selective CH3OH synthesis from CO2 but displays insufficient activity at low reaction temperatures. By screening a range of promoters (Co, Ni, Cu, and Pd) in combination with In2O3 using flame spray pyrolysis (FSP) synthesis, Ni is identified as the most suitable first-row transition-metal promoter with similar performance as Pd–In2O3. NiO–In2O3 was optimized by varying the Ni/In ratio using FSP. The resulting catalysts including In2O3 and NiO end members have similar high specific surface areas and morphology. The main products of CO2 hydrogenation are CH3OH and CO with CH4 being only observed at high NiO loading (≥75 wt %). The highest CH3OH rate (∼0.25 gMeOH/(gcat h), 250 °C, and 30 bar) is obtained for a NiO loading of 6 wt %. Characterization of the as-prepared catalysts reveals a strong interaction between Ni cations and In2O3 at low NiO loading (≤6 wt %). H2-TPR points to a higher surface density of oxygen vacancy (Ov) due to Ni substitution. X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and electron paramagnetic resonance analysis of the used catalysts suggest that Ni cations can be reduced to Ni as single atoms and very small clusters during CO2 hydrogenation. Supportive density functional theory calculations indicate that Ni promotion of CH3OH synthesis from CO2 is mainly due to low-barrier H2 dissociation on the reduced Ni surface species, facilitating hydrogenation of adsorbed CO2 on Ov.