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Developing a noble-metal-based catalyst that works effectively for NOx removal in the presence of excess O-2 is still a big challenge in catalytic chemistry for exhaust gas purification. To overcome this challenge, in this study, we designed and prepared a nanoparticulate (Pd1-xPtx)In pseudobinary alloy using Al2O3 and CeO2 supports, where a portion of Pd was replaced with Pt to improve the oxidation tolerance of In during NOx reduction under lean conditions. Multiple characterization techniques were used to confirm the formation of the desired pseudobinary alloy phase. The prepared Pd-Pt-In/CeO2 catalyst exhibited high NO conversion to N-2 in NO-CO-O-2 reaction with a wide range of oxygen concentrations including lean conditions (80%-100%, 0.75 <= lambda <= 1.5, 350 degrees C) and retained its catalytic performance during rich-lean cycles.

We report herein that a commercially available CeO2 is an active and reusable catalyst for the C3-selective alkenylation of oxindole with aldehydes under solvent-free conditions. This. catalytic method is generally applicable to different aromatic and aliphatic aldehydes, giving 3-alkyledene-oxindoles in high yields (87%-99%) and high stereoselectivities (79%-93% to E-isomers). This is the first example of the catalytic synthesis of 3-alkenyl-oxindoles from oxindole and various aliphatic aldehydes. The Lewis acid-base interaction between Lewis acid sites on CeO2 and benzaldehyde was studied by in situ IR. The structure-activity relationship study using CeO2 catalysts with different sizes suggests that defect-free CeO2 surface is the active site for this reaction. (C) 2020, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Developing a noble-metal-based catalyst that works effectively for NOx removal in the presence of excess O-2 is still a big challenge in catalytic chemistry for exhaust gas purification. To overcome this challenge, in this study, we designed and prepared a nanoparticulate (Pd1-xPtx)In pseudobinary alloy using Al2O3 and CeO2 supports, where a portion of Pd was replaced with Pt to improve the oxidation tolerance of In during NOx reduction under lean conditions. Multiple characterization techniques were used to confirm the formation of the desired pseudobinary alloy phase. The prepared Pd-Pt-In/CeO2 catalyst exhibited high NO conversion to N-2 in NO-CO-O-2 reaction with a wide range of oxygen concentrations including lean conditions (80%-100%, 0.75 <= lambda <= 1.5, 350 degrees C) and retained its catalytic performance during rich-lean cycles.

We report herein that a commercially available CeO2 is an active and reusable catalyst for the C3-selective alkenylation of oxindole with aldehydes under solvent-free conditions. This. catalytic method is generally applicable to different aromatic and aliphatic aldehydes, giving 3-alkyledene-oxindoles in high yields (87%-99%) and high stereoselectivities (79%-93% to E-isomers). This is the first example of the catalytic synthesis of 3-alkenyl-oxindoles from oxindole and various aliphatic aldehydes. The Lewis acid-base interaction between Lewis acid sites on CeO2 and benzaldehyde was studied by in situ IR. The structure-activity relationship study using CeO2 catalysts with different sizes suggests that defect-free CeO2 surface is the active site for this reaction. (C) 2020, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

A series of Cu-Pd alloy nanoparticles supported on Al2O3 were prepared and tested as catalysts for deNO(x) reactions. XRD, HAADF-STEM, XAFS, and FT-IR analyses revealed that a single-atom alloy structure was formed when the Cu/Pd ratio was 5, where Pd atoms were well isolated by Cu atoms. Compared with Pd/Al2O3, Cu5Pd/Al2O3 exhibited outstanding catalytic activity and N-2 selectivity in the reduction of NO by CO: for the first time, the complete conversion of NO to N-2 was achieved even at 175 degrees C, with longterm stability for at least 30 h. High catalytic performance was also obtained in the presence of O-2 and C3H6 (model exhaust gas), where a 90% decrease in Pd use was achieved with minimum evolution of N2O. Kinetic and DFT studies demonstrated that N-O bond breaking of the (NO)(2) dimer was the rate-determining step and was kinetically promoted by the isolated Pd.

A series of Cu-Pd alloy nanoparticles supported on Al2O3 were prepared and tested as catalysts for deNO(x) reactions. XRD, HAADF-STEM, XAFS, and FT-IR analyses revealed that a single-atom alloy structure was formed when the Cu/Pd ratio was 5, where Pd atoms were well isolated by Cu atoms. Compared with Pd/Al2O3, Cu5Pd/Al2O3 exhibited outstanding catalytic activity and N-2 selectivity in the reduction of NO by CO: for the first time, the complete conversion of NO to N-2 was achieved even at 175 degrees C, with longterm stability for at least 30 h. High catalytic performance was also obtained in the presence of O-2 and C3H6 (model exhaust gas), where a 90% decrease in Pd use was achieved with minimum evolution of N2O. Kinetic and DFT studies demonstrated that N-O bond breaking of the (NO)(2) dimer was the rate-determining step and was kinetically promoted by the isolated Pd.