Direct methanol production from mixed methane/H2O/N2O feedstocks over Cu–Fe/Al2O3 catalysts. (1st October 2021)

• Record Type: Journal Article
• Authors: Dasireddy, Venkata D.B.C.; Likozar, Blaž
• Is Part Of: Fuel. Volume 301(2021)
• Publication Date: 2021-10-01
• Subjects: Methane -- Methanol -- Oxidation -- Copper–iron/alumina -- Hydrothermal preparation method -- Metal redox mechanism; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2021.121084
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: A synergy between Cu and Fe in the single-step formation of methanol was observed. A reversible redox transformation (a mechanism) between both Cu and Fe was proposed. A high turnover frequency (TOF) to CH3 OH (18.3 × 10 –3 s −1 ) considering literature. High productivity of methanol (1228 µ molCH3OH gcat. –1 h −1 ) over Cu–Fe/Al2 O3 . The single-step oxidative chemical reaction for circumventing natural gas reforming. Abstract: Bimetallic Cu/Fe-based catalysts were prepared through a novel hydrothermal (HT) method, structurally examined, and catalytically employed for the oxidation of methane to methanol. The highest CH4 conversion rate, CH3 OH selectivity, and productivity were obtained over HT Cu–Fe/Al2 O3 . To compare the activity of the latter, bi-/monometallic Cu/Fe were also fabricated through support wet impregnation or co-precipitation (CP). These were characterised using chemisorption, reducibility, physisorption, diffraction and microscopy. N2 analysis showed that Cu or Fe species might be occupying pores, but was not incorporated into γ-Al2 O3 structure. For Cu–Fe/Al2 O3, interfacial copper nanoparticles acted as hydrogen activation sites, facilitating the reduction of Fe3 O4 at lower measured temperatures. A high CH3 OH synthesis yield was observed at 300 °C for HT Cu–Fe/Al2 O3, 350 °C for CP Cu–Fe/Al2 O3, while Cu/Al2 O3 or Fe/Al2 O3 demonstrated the optimum at 400 °C, which was in a correlation with the reducible material nature of Cu/Fe. The present catalysis process resulted from metal atom dispersion because of isolated Cu/Fe. The predominant direct chemosynthesis of alcohol (1228 µ molCH3OH gcat. –1 h −1 ) was determined when N2 O or a mixture of H2 O/N2 O was applied as the oxidant over Cu–Fe/Al2 O3 substance, produced via developed HT experimental steps. Comparatively, though, active Cu/Fe, dispersed on alumina surface layer, were more selective for the production of CH3 OH under N2 O atmosphere. The formation of CH3 OH by oxidizing CH4 followed an elementary redox mechanism, while reactivity, intermediate mechanistic pathways and the distribution of products depended on the oxidant molecule type in reactions involved.