The Royal Society of Chemistry eBooks, Jul 15, 2020
This chapter deals with the use and development of heterogeneous non-precious metal oxide-based c... more This chapter deals with the use and development of heterogeneous non-precious metal oxide-based catalysts for aerobic oxidation reactions in gas–solid and liquid–solid phases. The main solid catalysts from transition metal ions (Mn, Cu, Fe, V, Ce, Nd, Mo, W) are described. Many examples are given about the reactions, catalytic performances, catalysts used and major industrial processes, either existing at present using petroleum-based raw materials or future processes using biomass-derived raw materials. It concerns selective oxidation and ammoxidation (NH3 + O2) reactions of alkanes to alkenes; alkanes to carboxylic acids, aldehydes and nitriles; olefins to carboxylic aldehydes and acids and aromatics to the corresponding acids or nitriles. Total oxidation reactions for depollution treatment and combustion are also briefly presented regarding atmospheric pollutants, such as industrial volatile organic compounds (VOCs). Some reaction mechanisms (radical-type or Mars and van Krevelen-type) along with concerns on the structure and size of active sites are discussed. Different reactor types, including packed bed, membrane and moving bed technology, are discussed depending on the intended reaction, as well as considerations on physical aspects of the solid catalysts, related to thermal and electrical conductivities, attrition resistance, deactivation and regeneration of the catalysts.
Journal of the Acoustical Society of America, Apr 1, 2022
Within the context of sustainable chemistry, sonochemistry is now emerging as an alternative unco... more Within the context of sustainable chemistry, sonochemistry is now emerging as an alternative unconventional technology in catalysis. While ultrasound-generated radicals can participate in chemical reactions, mastering the reaction selectivity of polyfunctional substrates remains an elusive task. To address this challenge, we designed nanostructured metal oxides with leaf-like morphologies (e.g., CuO) by sonochemical synthesis (20 kHz) and investigated their activity for controlling the selectivity of oxidation reactions under ultrasonic irradiation in aqueous solution. We demonstrated that colocalization of the cavitation event onto the CuO surface active sites enables the direct utilization of radicals generated by cavitation for chemo-selective chemical reactions. In particular, we provided evidence for an alternative reaction pathway in glucose selective oxidation through synergistic cavitation–catalyst interactions at 550 kHz. We showed that the unwanted H• radicals stemming from water sonolysis are trapped by the surface lattice oxygen of CuO, thereby increasing the coverage of •OH radicals on the catalyst surface, and steering the selective oxidation of glucose to glucuronic acid, a valuable chemical whose synthesis remains a formidable challenge in the field of catalysis. This work also highlights that the particle size of the sonocatalyst is a key parameter governing an optimal transfer of radicals from the cavitation bubbles to the catalyst surface.
Wine made or stored in clayware ceramic pots attracts the attention of consumers, but this practi... more Wine made or stored in clayware ceramic pots attracts the attention of consumers, but this practice is less studied than when classic stainless steel tanks or wood barrels are used. It is known that wine can be influenced by the container in which it is aged. To analyse the influence of ceramics on the chemical composition of wine, Armenian clay-based ceramic tablets were immersed in model wine and aged from 1 hour up to 16 months at 25 °C in darkness. The concentrations of 26 elements (namely: Al, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sr, Ti, V, W and Zn) in 19 samples were determined by ICP-AES analysis. Proton time domain NMR relaxometry was used to characterise the iron redox processes that occurred in the model wine in contact with a ceramic. A fast increase in the pH of the model wine in contact with the bare ceramic tablet (from 2.35 to 5) was recorded in 4 days. The coating of the ceramic tablets with beeswax showed a significant effect ...
Glycerol was oxidized selectively to oxalic and tartronic acids in 78% yield over a highly crysta... more Glycerol was oxidized selectively to oxalic and tartronic acids in 78% yield over a highly crystalline CuO catalyst prepared within a few minutes by a sonochemical synthesis.
The Royal Society of Chemistry eBooks, Jul 15, 2020
This chapter deals with the use and development of heterogeneous non-precious metal oxide-based c... more This chapter deals with the use and development of heterogeneous non-precious metal oxide-based catalysts for aerobic oxidation reactions in gas–solid and liquid–solid phases. The main solid catalysts from transition metal ions (Mn, Cu, Fe, V, Ce, Nd, Mo, W) are described. Many examples are given about the reactions, catalytic performances, catalysts used and major industrial processes, either existing at present using petroleum-based raw materials or future processes using biomass-derived raw materials. It concerns selective oxidation and ammoxidation (NH3 + O2) reactions of alkanes to alkenes; alkanes to carboxylic acids, aldehydes and nitriles; olefins to carboxylic aldehydes and acids and aromatics to the corresponding acids or nitriles. Total oxidation reactions for depollution treatment and combustion are also briefly presented regarding atmospheric pollutants, such as industrial volatile organic compounds (VOCs). Some reaction mechanisms (radical-type or Mars and van Krevelen-type) along with concerns on the structure and size of active sites are discussed. Different reactor types, including packed bed, membrane and moving bed technology, are discussed depending on the intended reaction, as well as considerations on physical aspects of the solid catalysts, related to thermal and electrical conductivities, attrition resistance, deactivation and regeneration of the catalysts.
Journal of the Acoustical Society of America, Apr 1, 2022
Within the context of sustainable chemistry, sonochemistry is now emerging as an alternative unco... more Within the context of sustainable chemistry, sonochemistry is now emerging as an alternative unconventional technology in catalysis. While ultrasound-generated radicals can participate in chemical reactions, mastering the reaction selectivity of polyfunctional substrates remains an elusive task. To address this challenge, we designed nanostructured metal oxides with leaf-like morphologies (e.g., CuO) by sonochemical synthesis (20 kHz) and investigated their activity for controlling the selectivity of oxidation reactions under ultrasonic irradiation in aqueous solution. We demonstrated that colocalization of the cavitation event onto the CuO surface active sites enables the direct utilization of radicals generated by cavitation for chemo-selective chemical reactions. In particular, we provided evidence for an alternative reaction pathway in glucose selective oxidation through synergistic cavitation–catalyst interactions at 550 kHz. We showed that the unwanted H• radicals stemming from water sonolysis are trapped by the surface lattice oxygen of CuO, thereby increasing the coverage of •OH radicals on the catalyst surface, and steering the selective oxidation of glucose to glucuronic acid, a valuable chemical whose synthesis remains a formidable challenge in the field of catalysis. This work also highlights that the particle size of the sonocatalyst is a key parameter governing an optimal transfer of radicals from the cavitation bubbles to the catalyst surface.
Wine made or stored in clayware ceramic pots attracts the attention of consumers, but this practi... more Wine made or stored in clayware ceramic pots attracts the attention of consumers, but this practice is less studied than when classic stainless steel tanks or wood barrels are used. It is known that wine can be influenced by the container in which it is aged. To analyse the influence of ceramics on the chemical composition of wine, Armenian clay-based ceramic tablets were immersed in model wine and aged from 1 hour up to 16 months at 25 °C in darkness. The concentrations of 26 elements (namely: Al, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sr, Ti, V, W and Zn) in 19 samples were determined by ICP-AES analysis. Proton time domain NMR relaxometry was used to characterise the iron redox processes that occurred in the model wine in contact with a ceramic. A fast increase in the pH of the model wine in contact with the bare ceramic tablet (from 2.35 to 5) was recorded in 4 days. The coating of the ceramic tablets with beeswax showed a significant effect ...
Glycerol was oxidized selectively to oxalic and tartronic acids in 78% yield over a highly crysta... more Glycerol was oxidized selectively to oxalic and tartronic acids in 78% yield over a highly crystalline CuO catalyst prepared within a few minutes by a sonochemical synthesis.
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