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Ionic Liquids 英超联赛直播液体
A series of FeOx- and Al2O3-supported Pt, Pd catalysts (0.23–2.1%) were prepared in this study. Pt/FeOx exhibited high CO oxidation activity with turnover frequency of 151 10 3 s 1 (1% CO balanced with air, atmospheric pressure, 27 C). A systematical study of FeOx- and Al2O3-supported Pt, Pd catalysts by means of X-ray photoelectron spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, temperature-programmed reduction, H2–O2 titration, and time-resolved CO titration is reported. From 7% to 39% of Fe3+ was reduced to Fe2+ over Fe(OH)x-supported Pd and Pt catalysts, accompanied by Pd, Pt hydrogenation and hydroxyl loss, and a large amount of oxygen vacancies were proposed to be produced. Results of H2–O2 titration and time-resolved CO titration showed that a large amount of oxygen adsorbed onto FeOx support in the presence of Pt, Pd. This made CO oxidations over Pt/FeOx, Pd/FeOx proceed over two adjacent but different active sites (Pt, Pd for CO and FeOx for oxygen) with low apparent activation energies (30–34 kJ/mol), which accounted for their high activity in low-temperature CO oxidation.
Keywords: CO oxidation; Pt catalyst; Pd catalyst; Kinetic measurements; Strong metal–support interaction (SMSI); effect; Oxygen vacancy; H2–O2 titration; Time-resolved CO titration
★★★☆☆ Liu LQ,Zhou F,Wang LG,et al. Low-temperature Co Oxidation Over Supported Pt, Pd Catalysts: Particular Role Of Feox Support For Oxygen Supply During Reactions[J]. Journal Of Catalysis,2010,274:1-10.
Chemoselective hydrogenation of aromatic nitro compounds were first efficiently achieved over Au/Fe(OH)x at 100–120 1C for 1.5–6 h (depending on different substrates) in the presence of CO and H2O.
★★★★☆ Liu LQ,Qiao BT,Chen ZJ,et al. Novel Chemoselective Hydrogenation Of Aromatic Nitro Compounds Over Ferric Hydroxide Supported Nanocluster Gold In The Presence Of Co And H2o[J]. Chemical Communications,2009:653-655.
An attempt to prepare ferric hydroxide supported Au subnano clusters via modified co-precipitation without any calcination was made. High resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) have been employed to study the structure and chemical states of these catalysts. No Au species could be observed in the HRTEM image nor from the XRD pattern, suggesting that the sizes of the Au species in and on the ferric hydroxide support were less than or around 1 nm. Chemoselective hydrogenation of aromatic nitro compounds and a,b-unsaturated aldehydes was selected as a probe reaction to examine the catalytic properties of this catalyst. Under the same reaction conditions, such as 100 ◦C and1MPaH2 in the hydrogenation of aromatic nitro compounds, a 96–99% conversion (except for 4-nitrobenzonitrile) with 99% selectivity was obtained over the ferric hydroxide supported Au catalyst, and the TOF values were 2–6 times higher than that of the corresponding ferric oxide supported catalyst with 3–5 nm size Au particles. For further evaluation of this Au catalyst in the hydrogenation of citral and cinnamaldehyde, selectivity towards unsaturated alcohols was 2–20 times higher than that of the corresponding ferric oxide Au catalyst.
★★★★☆Liu LQ,Qiao BT,Ma YB,et al. Ferric Hydroxide Supported Gold Subnano Clusters Or Quantum Dots: Enhanced Catalytic Performance In Chemoselective Hydrogenation[J]. Dalton Trans.,2008:2542-2548.