CeO2 with varied morphologies (nanopolyhedra, nanorods, and nanocubes) were synthesized via a hydrothermal method and applied to the catalytic combustion of toluene. The physicochemical properties of all catalysts were characterized by transmission electron microscopy, N2-physisorption, X-ray diffraction, H2-temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The CeO2 nanopolyhedra showed superior catalytic activity compared to CeO2 nanorods and nanocubes. Kinetic studies showed that the catalytic combustion of toluene processed through the Mars–van-Krevelen (MvK) mechanism and the oxidation of the reduced CeO2 surface by molecular oxygen are the rate-determining steps in the low-temperature region. The XPS and H2-TPR results showed that CeO2 with varied morphologies had distinct oxygen distribution, especially surface lattice oxygen. A linear relationship between surface lattice oxygen and catalytic activity was observed, indicating that surface lattice oxygen played an important role in the catalytic activity of toluene combustion. Furthermore, the in situ DRIFTS results provided a full roadmap of catalytic combustion of toluene: toluene first rapidly adsorbed onto the surface of CeO2 to form molecularly adsorbed toluene, which then reacted with the surface hydroxyl groups to generate benzyl species without O2. The benzyl species could be further oxidized to benzyloxy, benzaldehyde, and benzoate species, and finally fully oxidized to CO2 and H2O. All these results indicated that the reactivity of surface lattice oxygen was crucial on the catalytic combustion of toluene, providing a basic understanding for the catalytic combustion of toluene on CeO2 with varied morphologies.

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Four manganese oxides with different crystal structures in the similar nanorod‐shaped morphology were synthesized and investigated for the catalytic combustion of benzene. The physicochemical properties of the materials were characterized by N2 physisorption‐desorption, transmission electron microscope (TEM), X‐ray photoelectron spectroscopy (XPS), Raman spectra, O2 temperature programmed desorption (O2‐TPD) and temperature programmed surface reaction (TPSR). The catalytic activities on benzene combustion over various manganese oxides decreased in the order: γ‐MnO2 > β‐MnO2 > α‐MnO2 > δ‐MnO2. The activation energy of benzene combustion over γ‐MnO2 (67.4 kJ/mol) was lower than that over α‐MnO2 (69.2 kJ/mol), β‐MnO2 (79.1 kJ/mol) and δ‐MnO2 (85.2 kJ/mol). The TPSR results with or without gaseous oxygen revealed that the reaction pathway was occurred via MVK mechanism. The surface adsorbed oxygen species concentration and low temperature O2 desorption of these manganese oxides, determined by XPS and O2‐TPD, decreased in the order of γ‐MnO2 > β‐MnO2 > α‐MnO2 > δ‐MnO2, are in good agreement with the sequence of their catalytic performance on benzene combustion. It is concluded that higher surface adsorbed oxygen species ratio and better low temperature O2 desorption were crucial to the superior catalytic performance of the α‐MnO2, β‐MnO2, γ‐MnO2 and δ‐MnO2 materials.

Formic acid and formate derivatives as hydrogen source on the hydrogenation of para‐chloronitrobenzene (p‐CNB) over supported gold catalysts were investigated. The hydrogenation activity in various formate derivatives followed the order: HCOOH < HCOONa < HCOOK < HCOONH4, which was in accordance with the decrement of electronegativity of cation species in formate derivatives. Moreover, in the case of HCOONH4 as hydrogen source, the p‐CNB conversion could enhance ten‐fold as the hydrogen source of H2 at 60 oC. This promotion effect was also found in other supported Au catalysts. These results provide a general alternative hydrogen source to replace conventional H2 as reducing agent for fine chemical processes.

A series of manganese-based catalysts supported by 5-10 nm, 10-25 nm, 40 nm and 60 nm anatase TiO 2 particles was synthesized via an impregnation method to investigate the effect of the initial support particle size on the selective catalytic reduction (SCR) of NO with NH 3 . All catalysts were characterized by transmission electron microscopy (TEM), N 2 physisorption/desorption, X-ray diffraction (XRD), temperature programmed techniques, X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared transform spectroscopy (DRIFTS). TEM results indicated that the particle sizes of the MnO x /TiO 2 catalysts were similar after the calcination process, although the initial TiO 2 support particle sizes were different. However, the initial TiO 2 support particle sizes were found to have a significant influence on the SCR catalytic performance. XPS and NH 3 -TPD results of the MnO x /TiO 2 catalysts illustrated that the surface Mn 4+ /Mn molar ratio and acid amount could be influenced by the initial TiO 2 support particle sizes. The order of surface Mn 4+ /Mn molar ratio and acid amount over the MnO x /TiO 2 catalysts was as follows: MnO x /TiO 2 (10-25) > MnO x /TiO 2 (40) > MnO x /TiO 2 (60) > MnO x /TiO 2 (5-10), which agreed well with the order of SCR performance. In situ DRIFTS results revealed that the NH 3 -SCR reactions over MnO x /TiO 2 at low temperature occurred via a Langmuir-Hinshelwood mechanism. More importantly, it was found that the bridge and bidentate nitrates were the main active substances for the low-temperature SCR reaction, and bridge nitrate adsorbed on Mn 4+ showed superior SCR activity among all the adsorbed NO x species. The variation of the initial TiO 2 support particle size over MnO x / TiO 2 could change the surface Mn 4+ /Mn molar ratio, which could influence the adsorption of NO x species, thus bringing about the diversity of the SCR catalytic performance.