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Nanostructured Co 3 O 4 -CeO 2 and CuO-CeO 2 catalysts with the specific surface areas exceeding 100 m 2 g -1 were synthesized by a surfactant-templated method. The catalytic performance of these catalysts was investigated using the total oxidation of CO and C 3 H 8 as model reactions. The results show that the Co 3 O 4 -CeO 2 catalysts are less active for CO oxidation but are more active for C 3 H 8 oxidation as compared with the CuO-CeO 2 catalysts. Moreover, the Co 3 O 4 -CeO 2 catalysts exhibit a volcano-type performance for CO oxidation with the cobalt content increasing. The in situ diffuse reflectance infrared spectroscopy (DRIFTS) study shows that CO is adsorbed mainly as carbonyl (2106 cm -1 ) and bidentate carbonate (1568 and 1281 cm -1 ) on CuO-CeO 2 , and only as bidentate carbonate (1591 and 1268 cm -1 ) on Co 3 O 4 -CeO 2 . On the basis of the results of structural characterization, redox properties, and in situ DRIFTS study, the active sites for CO and C 3 H 8 oxidation are identified, respectively. Carbon monoxide oxidation preferentially occurs at the interface between CeO 2 and CuO or Co 3 O 4 , whereas propane oxidation takes place on the neighboring surface lattice oxygen sites in CuO or Co 3 O 4 crystallites. The different requirements of the active sites are determined by the different reaction mechanisms and the rate-determining steps. It is also found that the introduction of a small amount of Pd to Co 3 O 4 -CeO 2 can remarkably promote the CO oxidation activity, but it hardly enhanced the C 3 H 8 oxidation activity of the catalyst. The different reaction mechanisms, on molecular level, are identified and discussed in detail.

A series of mesoporous MnOx−CeO2 binary oxide catalysts with high specific surface areas were prepared by surfactant-assisted precipitation. The CO and C3H8 oxidation reactions were used as model reactions to evaluate their catalytic performance. The techniques of N2 adsorption/desorption, XRD, XPS, TPR, TPO, TPD, and in situ DRIFTS were employed for catalyst characterization. It is found that the activity for CO and C3H8 oxidation of the catalysts exhibits a volcano-type behavior with the increase of Mn content. The catalyst with a Mn/Ce ratio of 4/6, possessing a high specific surface area of 215 m2/g, exhibits the best catalytic activity, which is related not only to its highest reducibility and oxygen-activation ability, as revealed by TPR and TPO, but also to the formation of more active oxygen species on the MnOx−CeO2 interface as identified by TPD. After the addition of a small amount of Pd to the MnOx−CeO2 catalyst, its activity for CO oxidation is greatly enhanced, due to the acceleration of gas-phase oxygen activation and transferring via spillover. However, the activity for C3H8 oxidation is hardly promoted due to the different reaction pathways for CO and C3H8 oxidation. For CO oxidation, the gas-phase oxygen activated by Pd can directly react with the adsorbed CO to form CO2, while, for C3H8 oxidation, which takes place at a much higher temperature than CO oxidation, the C−H bond activation and cleavage may be mainly driven by the active oxygen species on the interface between MnOx and CeO2. The addition of Pd shows little effect on the active interface oxygen species, so no promotion upon C3H8 oxidation is observed.

Black TiO2 was usually obtained via hydrogenation at high pressure and high temperature. Herein, we reported a facile hydrogenation of TiO2 in the presence of a small amount of Pt at relatively low temperature and atmospheric pressure. The hydrogen spillover from Pt to TiO2 accounts well for the greatly enhanced hydrogenation capability. The as-synthesized Pt/TiO2 exhibits remarkably improved photocatalytic activity for water splitting.

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Ethanol was directly synthesized from dimethyl ether (DME) and syngas with the combined H-Mordenite and Cu/ZnO catalysts that were separately loaded in a dual-catalyst bed reactor. Methyl acetate (MA) was formed by DME carbonylation over the H-Mordenite catalyst. Thereafter, ethanol and methanol were produced by MA hydrogenation over the Cu/ZnO catalyst. With the reactant gas containing 1.0% DME, the optimized temperature for the reaction was at 493 K to reach 100% conversion. In the products, the yield of methanol and ethanol could reach 46.3% and 42.2%, respectively, with a small amount of MA, ethyl acetate, and CO(2). This process is environmentally friendly as the main byproduct methanol can be recycled to DME by a dehydration reaction. In contrast, for the physically mixed catalysts, the low conversion of DME and high selectivity of methanol were observed.

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