Progress and prospective of nitrogen-based alternative fuels

Alternative fuels are essential to enable the transition to a sustainable and environmentally friendly energy supply. Synthetic fuels derived from renewable energies can act as energy storage media, thus mitigating the effects of fossil fuels on environment and health. Their economic viability, environmental impact, and compatibility with current infrastructure and technologies are fuel and power source specific. Nitrogen-based fuels pose one possible synthetic fuel pathway. In this review, we discuss the progress and current research on utilization of nitrogen-based fuels in power applications, covering the complete fuel cycle. We cover the production, distribution, and storage of nitrogen-based fuels. We assess much of the existing literature on the reactions involved in the ammonia to nitrogen atom pathway in nitrogen-based fuel combustion. Furthermore, we discuss nitrogen-based fuel applications ranging from combustion engines to gas turbines, as well as their exploitation by suggested end-uses. Thereby, we evaluate the potential opportunities and challenges of expanding the role of nitrogen-based molecules in the energy sector, outlining their use as energy carriers in relevant fields

Resolving the Oxygen Species on Ozone Activated AgAu Alloy Catalysts for Oxidative Methanol Coupling

Bimetallic alloy catalysts frequently demonstrate distinct performances that are superior to their monometallic counterparts, yet their surface chemistry needs to be carefully studied to understand their structure–activity relationships. The nanoporous Ag0.03Au0.97 alloy catalyst becomes highly active and selective for oxidative methanol coupling to methyl formate after O3 activation. HS-LEIS reveals the O3 treatment results in enrichment of Ag (>30%) on the outermost surface layer, while oxygen treatment additionally leads to segregation of a larger portion of Cu impurity on the surface. A series of characteristic Raman bands at 395, 577, 867, and 904 cm–1 only form under oxidative methanol coupling reaction on O3-activated AgAu catalyst. These bands correspond to Ag3–O* (395 cm–1), M–O* on O–Au(111) and AgAu alloy (577 cm–1), CH3OH* (867 cm–1), and HOOH* (904 cm–1), as revealed by DFT calculations. The cyclic in situ Raman and reactivity studies indicate the detected oxygen species could be related to a “memory effect” of the catalyst upon pretreatment. The current study highlights the importance of applying surface-specific techniques for investigation of compositions of outermost surface layers of alloy catalysts, as well as integration of in situ spectroscopies and computational investigations for understanding surface structures at the molecular level under reaction conditions

Lithium carbonate-promoted mixed rare earth oxides as a generalized strategy for oxidative coupling of methane with exceptional yields

Abstract The oxidative coupling of methane to higher hydrocarbons offers a promising autothermal approach for direct methane conversion, but its progress has been hindered by yield limitations, high temperature requirements, and performance penalties at practical methane partial pressures (~1 atm). In this study, we report a class of Li2CO3-coated mixed rare earth oxides as highly effective redox catalysts for oxidative coupling of methane under a chemical looping scheme. This catalyst achieves a single-pass C2+ yield up to 30.6%, demonstrating stable performance at 700 °C and methane partial pressures up to 1.4 atm. In-situ characterizations and quantum chemistry calculations provide insights into the distinct roles of the mixed oxide core and Li2CO3 shell, as well as the interplay between the Pr oxidation state and active peroxide formation upon Li2CO3 coating. Furthermore, we establish a generalized correlation between Pr4+ content in the mixed lanthanide oxide and hydrocarbons yield, offering a valuable optimization strategy for this class of oxidative coupling of methane redox catalysts