CO2 Conversion via Reverse Water Gas Shift Reaction Using Fully Selective Mo–P Multicomponent Catalysts

The reverse water gas shift reaction (RWGS) has attracted much attention as a potential means to widespread utilization of CO₂ through the production of synthesis gas. However, for commercial implementation of RWGS at the scales needed to replace fossil feedstocks with CO₂, new catalysts must be developed using earth abundant materials, and these catalysts must suppress the competing methanation reaction completely while maintaining stable performance at elevated temperatures and high conversions producing large quantities of water. Herein we identify molybdenum phosphide (MoP) as a nonprecious metal catalyst that satisfies these requirements. Supported MoP catalysts completely suppress methanation while undergoing minimal deactivation, opening up possibilities for their use in CO₂ utilization.

High Channel Density Ceramic Microchannel Reactor for Syngas Production

Solid oxide fuel cells can operate with carbonaceous fuels, such as syngas, biogas, and methane, using either internal or external reforming, and they represent a more efficient alternative to internal combustion engines. In this work, we explore, for the first time, an alumina membrane containing straight, highly packed (461,289 cpsi), parallel channels of a few micrometers (21 µm) in diameter as a microreformer. As a model reaction to test the performance of this membrane, the dry reforming of methane was carried out using nickel metal and a composite nickel/ceria as catalysts. The samples with intact microchannels were more resistant to carbon deposition than those with a powdered sample, highlighting the deactivation mitigation effect of the microchannel structure. The coke content in the microchannel membrane was one order of magnitude lower than in the powder catalyst. Overall, this work is a proof of concept on the use of composite alumina membrane as microchannel reactors for high temperature reactions.

Efficient Waste to Energy Conversion Based on Co-CeO2 Catalyzed Water-Gas Shift Reaction

Waste to energy technology is attracting attention to overcome the upcoming environmental and energy issues. One of the key-steps is the water-gas shift (WGS) reaction, which can convert the waste-derived synthesis gas (H2 and CO) to pure hydrogen. Co–CeO2 catalysts were synthesized by the different methods to derive the optimal synthetic method and to investigate the effect of the preparation method on the physicochemical characteristics of Co–CeO2 catalysts in the high-temperature water-gas shift (HTS) reaction. The Co–CeO2 catalyst synthesized by the sol-gel method featured a strong metal to support interaction and the largest number of oxygen vacancies compared to other catalysts, which affects the catalytic activity. As a result, the Co–CeO2 catalyst synthesized by the sol-gel method exhibited the highest WGS activity among the prepared catalysts, even in severe conditions (high CO concentration: ~38% in dry basis and high gas hourly space velocity: 143,000 h−1).

Au/CeO2-ZnO/Al2O3 as Versatile Catalysts for Oxidation Reactions: Application in Gas/Liquid Environmental Processes

The present work showcases the versatility of nanogold systems supported on Zn-doped ceria when applied in two important environmental processes, the total CO oxidation, and the liquid phase oxidation of glucose to gluconic acid. In the CO oxidation the suitability of these materials is clearly demonstrated achieving full conversions even at sub-ambient conditions. Regarding the glucose oxidation our materials display high conversion values (always over 50%) and very importantly full or almost full selectivity toward gluconic acid-an added value platform chemical in the context of biomass upgrading routes. The key factors controlling the successful performance on both reactions are carefully discussed and compared to previous studies in literature. To our knowledge this is one of the very few works in catalysis by gold combining liquid and gas phase reactions and represents a step forward in the flexible behavior of nano gold catalysts.

Pt-Au/MOx-CeO₂ (M = Mn, Fe, Ti) Catalysts for the Co-Oxidation of CO and H₂ at Room Temperature

A series of nanostructured Pt-Au/MO_x-CeO₂ (M = Mn, Fe, Ti) catalysts were prepared and their catalytic performance for the co-oxidation of carbon monoxide (CO) and hydrogen (H₂) were evaluated at room temperature. The results showed that MO_x promoted the CO oxidation of Pt-Au/CeO₂, but only the TiO₂ could enhance co-oxidation of CO and H₂ over Pt-Au/CeO₂. Related characterizations were conducted to clarify the promoting effect of MO_x. Temperature-programmed reduction of hydrogen (H₂-TPR) and X-ray photoelectron spectroscopy (XPS) results suggested that MO_x could improve the charge transfer from Au sites to CeO₂, resulting in a high concentration of Ce³⁺ and cationic Au species which benefits for the CO oxidation. In-situ diffuse reflectance infrared Fourier transform spectroscopy (In-situ DRIFTS) results indicated that TiO₂ could facilitate the oxidation of H₂ over the Pt-Au/TiO₂-CeO₂ catalyst.

Pt–Au/CeO2 catalysts for the simultaneous removal of carbon monoxide and formaldehyde

A series of Pt–Au/CeO₂ catalysts were prepared via the impregnation deposition–precipitation (IDP) and reduction–deposition precipitation (RDP) methods.

Gas-Phase Neutral Binary Oxide Clusters: Distribution, Structure, and Reactivity toward CO

Neutral binary (vanadium-cobalt) oxide clusters are generated and detected in the gas phase for the first time. Their reactivities toward carbon monoxide (CO) are studied both experimentally and theoretically. Experimental results suggest that neutral VCoO4 can react with CO to generate VCoO3 and CO2. Density functional theory studies show parallel results as well as provide detailed reaction mechanisms.