Characterization of LaMnAl11O19 by FT-IR spectroscopy of adsorbed NO and NO/O-2

Cataloged from PDF version of article.The nature of the NOx species produced during the adsorption of NO at room temperature and during its coadsorption with oxygen on LaMnAl11O19 sample with magnetoplumbite structure obtained by a sol–gel process has been investigated by means of in situ FT-IR spectroscopy. The adsorption of NO leads to formation of anionic nitrosyls and/or cis-hyponitrite ions and reveals the presence of coordinatively unsaturated Mn3+ ions. Upon NO/O2 adsorption at room temperature various nitro–nitrato structures are observed. The nitro–nitrato species produced with the participation of electrophilic oxygen species decompose at 350 8C directly to N2 and O2. No NO decomposition is observed in absence of molecular oxygen. The adsorbed nitro–nitrato species are inert towards the interaction with methane and block the active sites (Mn3+ ions) for its oxidation. Noticeable oxidation of the methane on the NOx -precovered sample is observed at temperatures higher than 350 8C due to the liberation of the active sites as a result of decomposition of the surface nitro–nitrato species. Mechanism explaining the promoting effect of the molecular oxygen in the NO decomposition is proposed. (c)2005 Elsevier B.V. All rights reserved

Oxidative Conversion of Hexane to Olefins-Influence of Plasma and Catalyst on Reaction Pathways

An integrated plasma-Li/MgO system is efficient for the oxidative conversion of hexane. In comparison to the Li/MgO catalytic system, it brings considerable improvements in the yields of light olefins (C 2 = –C 5 = ) at relatively low temperatures indicating synergy from combination of plasma and catalyst. The study on the influence of temperature on the performance of the integrated plasma-Li/MgO system shows dominancy of plasma chemistry at the lower temperature (500°C), while contribution from the catalyst both in hexane activation and in enhancing olefin formation becomes significant at the higher temperature (600°C). At 500°C significant amount of acetylene formation is observed. This is minimized at 600°C at oxygen depleting condition

Charge injection from carbon nanofibers into hexane under ambient conditions

The observation of charge injection from carbon nanofibers (CNFs) into liquid hexane under ambient conditions is reported. A CNF-coated electrode and a counter electrode are brought into micrometer proximity in a quasi-parallel geometry using a strain-gauge-based proximity sensor. Controlled charge injection is obtained at interelectrode distances of 4, 6, 9, and 15 μm. The resulting emission current shows an onset of about 3 V/μm , and it follows the Fowler-Nordheim behavior. The work reported here opens new applications for free electron chemistry in liquids and novel liquid field emitter devices

Particle suspension reactors and materials for solar-driven water splitting

Reactors based on particle suspensions for the capture, conversion, storage, and use of solar energy as H_2 are projected to be cost-competitive with fossil fuels. In light of this, this review paper summarizes state-of-the-art particle light absorbers and cocatalysts as suspensions (photocatalysts) that demonstrate visible-light-driven water splitting on the laboratory scale. Also presented are reactor descriptions, theoretical considerations particular to particle suspension reactors, and efficiency and performance characterization metrics. Opportunities for targeted research, analysis, and development of reactor designs are highlighted

Characterization of LaMnAl11O19 by FT-IR Spectroscopy of Adsorbed NO and NO/O2,

The nature of the NOx species produced during the adsorption of NO at room temperature and during its coadsorption with oxygen on LaMnAl11O19 sample with magnetoplumbite structure obtained by a sol-gel process has been investigated by means of in situ FT-IR spectroscopy. The adsorption of NO leads to formation of anionic nitrosyls and/or cis-hyponitrite ions and reveals the presence of two types of coordinatively unsaturated Mn3+ ions. Upon NO/O2 adsorption at room temperature various nitro-nitrato structures are observed. The nitro-nitrato species produced with the participation of electrophilic oxygen species decompose at 3500C directly to N2 and O2. No NO decomposition is observed in absence of oxygen. The adsorbed nitro-nitrato species are inert toward the interaction with methane and block the active sites (Mn3+ ions) for its oxidation. Noticeable oxidation of the methane on the NOx-precovered sample is observed at temperatures higher than 3500C due to the liberation of the active sites as a result of decomposition of the surface nitro-nitrato species. A mechanism explaining the promoting effect of the molecular oxygen in the NO decomposition is proposed