Saisai Cheng,Ningzhao Shang,Xin Zhou,Cheng Feng,Shutao Gao,Chun Wang,Zhi Wang
Bimetallic AgPd nanoparticles anchored on metal–organic framework (UiO-66) derived N-doped porous carbon (NPC-UiO-66) was fabricated and used as a catalyst for the catalytic transfer hydrogenation of nitroarenes using formic acid-formate as the hydrogen source. The results demonstrated that the Ag1Pd9@NPC-UiO-66 composite exhibited extraordinary catalytic activity toward the hydrogenation of nitroarenes to anilines at room temperature. A series of substituted nitroarenes were successfully converted to the corresponding anilines in high yields under ambient conditions with other reducible groups remaining intact. The superior catalytic performance of the prepared catalyst can be attributed to the synergistic effect between the highly dispersed AgPd nanoparticles and the unique structure of the NPC-UiO-66 support, as well as the high adsorption ability of the catalyst for the nitroarenes.
Xue Sun,Fang Li,Zhimiao Wang,Hualiang An,Wei Xue,Yanji Wang
Graphical Nanocatalysis : Highly uniformly dispersed AgPd alloy nanoparticles were anchored on a porous TiO 2 carrier, obtained by calcining precursor and template MIL-125(Ti), and used for FA dehydrogenation, achieving excellent catalytic activity. At 60 °C, the total TOF value of Ag 2 Pd 8 /TiO 2 -M-450-catalyzed FA dehydrogenation was 2579 h −1 . TiO 2 with a disc-like morphology was prepared by direct pyrolysis of a titanium metal–organic framework [MIL-125(Ti)] in air. Highly dispersed bimetallic AgPd nanoparticles were then anchored on TiO 2 and their catalytic performance in the dehydrogenation of formic acid was systematically investigated. The Ag/Pd ratio had a significant effect on the catalyst activity, with Ag 2 Pd 8 /TiO 2 exhibiting the highest total turnover frequency value of 2579 h −1 at 60 °C under an ambient atmosphere. This excellent performance was attributed to the low-crystallinity anatase phase structure and large specific surface area of the TiO 2 carrier, the alloying effect of the AgPd nanoparticles, and abundant electron transfer between the carrier and metal alloy nanoparticles.
Shutao Gao,Tao Feng,Qiuhua Wu,Cheng Feng,Ningzhao Shang,Chun Wang
A novel bimetallic catalyst, AgPd nanoalloy supported on Vulcan XC-72 carbon (AgPd@C-72), has been successfully fabricated and used for catalyzing H2 generation from formaldehyde aqueous solution at room temperature for the first time. The catalyst exhibits high catalytic activity and good stability, and the hydrogen generation rates could reach up to 237.4 mL min−1 g−1, which could be attributed to the high dispersion of metal nanoparticles, the synergistic effect of bimetal AgPd, and distinct interaction between the bimetal and the support. The excellent performance of the new catalytic system renders it quite attractive as a superior competitor for efficient hydrogen production from formaldehyde at room temperature. This work might open up a new way to further develop cost-effective and highly efficient bimetallic catalysts for the generation of H2 from formaldehyde aqueous solution.
Production of 2,5-furandicarboxylic acid (FDCA, a platform chemical for the chemical industry in the future) by the selective aerobic oxidation of 5-hydroxymethyl-furfural is a crucial component to enable the FDCA production from sugars. The challenge is to achieve a high FDCA yield at low temperatures. Here, we report a catalyst composed of alloyed nanoparticles (containing 1.5 wt % Ag and 1.5 wt % Pd) supported on CeO2 nanofibers, which achieved an excellent FDCA yield (93%) at 20 °C. Interesting observations include yield deterioration at higher reaction temperatures; water is the source of the oxygen atom(s) added to the oxidized intermediates and product, while O2 molecules adsorbed onto the catalyst scavenge electrons, yielding OH• radicals from OH– ions in the reaction system to drive the oxidation. At 20 °C, we avoid side reactions, but there is no external energy provided for overcoming the activation barriers. The barriers for activating the alcohol groups are significant. We find that the appropriate chemisorption on the catalyst is critical for a high FDCA yield. By tuning the Ag/Pd ratio, we attained the most catalytically active sites, bimetallic surface sites, at the boundaries between Ag and Pd clusters. The chemisorption at these sites is strong enough to cause the selective oxidation of both the aldehyde and alcohol groups in HMF at 20 °C, avoiding side reactions at high temperatures. The knowledge acquired from this study is expected to have implications for other catalytic systems where competitive reactions proceed.
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