Bavykina, Anastasiya; Yarulina, Irina; Al Abdulghani, Abdullah; Gevers, Lieven; Hedhili, Mohamed N.; Miao, Xiaohe; Galilea, Adrian; Pustovarenko, Alexey; Dikhtiarenko, Alla; Cadiau, Amandine; Aguilar-Tapia, Antonio; Hazemann, Jean-Louis; Kozlov, Sergey; Oud-Chikh, Samy; Cavallo, Luigi; Gascon, Jorge(ACS Catalysis, American Chemical Society (ACS), 2019-07-05)[Article]
The direct hydrogenation of CO2 to methanol using hydrogen is regarded as a potential technology to reduce greenhouse gas emissions and the dependence on fossil fuels. For this technology to become feasible, highly selective and productive catalysts that can operate under a wide range of reaction conditions near thermodynamic conversion are required. Here we combine a CO-producing In oxide catalyst with a methane-producing Co catalyst to obtain an In/Co catalyst for CO2 reduction to methanol. Density functional (DFT) simulations demonstrate that the charge transfer between the Co support and the In oxide film leads to enrichment of the surface of indium oxide with O vacancies, which serve as active sites for selective conversion of CO2 to methanol. Moreover, our simulations suggest that CO2 reduction on Co-supported In2O3–x films will preferentially yield methanol, rather than CO and methane. As a result, the prepared In@Co catalysts produce methanol from CO2 with high selectivity (>80%) and productivity (0.86 gCH3OH gcatalyst–1 h–1) at conversion levels close to thermodynamic equilibrium, even at temperatures as high as 300 °C and at moderate pressures (50 bar).
Aljuhani, Maha A.; Zhang, Ziyun; Barman, Samir; El Eter, Mohamad; Falivene, Laura; Ould-Chikh, Samy; Guan, Erjia; Abou-Hamad, Edy; Emwas, Abdul-Hamid M.; Pelletier, Jeremie; Gates, Bruce C.; Cavallo, Luigi; Basset, Jean-Marie(ACS Catalysis, American Chemical Society (ACS), 2019-08-06)[Article]
Selective hydroamination of terminal alkynes with primary aryl amines is catalyzed by an unprecedented well-defined silica-supported tantalum complex [(≡Si-O-)Ta(η1σ-NEtMe)2(=NtBu)]. A molecular-level characterization of the surface organometallic Ta species was done with the help of characterization tech-niques including as in situ infrared, in situ elemental microanal-ysis, 1H and 13C solid-state NMR (including double and triple quanta sequence), and X-ray absorption spectroscopies. These were complemented by the state-of-the-art DNP-SENS 15N characterization. Several catalytic intermediates have been isolated in particular the 4-membered metallacycle ring inter-mediate resulting from the anti Markovnikov addition of the alkyne to the surface tantalum imido. The mechanism proposed was based on the isolation of all intermediates. A DFT calcula-tion has confirmed all the elementary steps and intermediates that were fully characterized.
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