Ni x Co y /H-ZrO2 catalysts composed of highly dispersed Ni x Co y nanoparticles supported by mesoporous ZrO2 hollow sphere are synthesized by templating and impregnation processes. According to thermogravimetric analysis, X-ray photoelectron spectroscopy, and dry reforming results, a synergetic reaction mechanism is proposed to explain the better performance of alloy catalysts compared to Ni/H-ZrO2 or Co/H-ZrO2. In dry reforming of methane (DRM) reaction, Ni and Co act as catalysts for CH4 cracking and CO2 reduction, respectively, and the induced carbon deposits on Ni can be oxidized by the active oxygen left on Co, which regenerate the metal surface for the following reaction. Among all the alloy catalysts, the Ni0.8Co0.2/H-ZrO2 catalyst presents the highest activity and stability because the strong metal–support interaction prevents the sintering of nanocatalysts at high temperature and the hollow structure enhances the mass transportation of reactants and products. More importantly, Ni and Co can synergistically balance the speed of CH4 cracking and CO2 reduction, which effectively avoid coke accumulation/catalyst oxidation and ensure fast and stable conversion for DRM reaction.

Three kinds of nickel-loaded anhydrous calcium silicate nanocatalysts( ACS), including Ni-ACS-Dop, Ni-ACS-Iex and Ni-ACS-Im, were prepared by introducing Ni species through doping in the synthesis of calcium silicate hydrate (CSH) nanosheets, ion-exchange with premade CSH nanosheets and deposition on calcined ACS nanosheets, respectively.A lthough Ni speciesw ere introduced in different ways, all the Ni-ACS catalysts showed similarc hemical compositions and microstructures, where Ni nanoparticles were highly dispersed on the ultrathin ACS nanosheets with a large surface area and good thermal stability.H owever,t he differences in the way of Ni introduction did produce Ni with differente lectronic states. The Ni-ACS-Iex catalyst with "surface Ni" as ad ominant form had more electrons enriched on the surface of Ni, which led to the highest activity in the dry reforming of methane (DRM) reaction among the three catalysts, whereas the Ni-ACS-Dop catalystw ith "lattice Ni" as adominant form showed an electron-deficient property and lowesta ctivity.D ifferent from the introduction of a more favourablen anostructure or chemical component to the catalyst system, this work controlled the chemical environment of metal precursorsa nd created metal catalysts with ap referred surfacee lectronic state during synthesis, which could be an ew strategy to improvet he catalytic activity.

The uncalcined but highly dispersive oxide-supported metal catalyst for liquid phase reactions may suffer from the agglomeration of metal nanoparticles and the drop of metal catalyst in solution, which will decrease the activity and shorten their life in catalysis. Here, a one-pot successive polyol reaction was developed to prepare M-E O colloidal particles as heterogeneous nanocatalysts, which merge the controlled synthesis of metal catalysts and oxide supports, the in situ loading of catalyst, and even the mesopore amplification into a highly integrated process. Unlike the traditional surface-deposited catalysts, the noble metal nanoparticles even with a large amount of loading are internally dispersed in the mesoporous oxide particles, which show higher activity and stability in the hydrogenation of nitroaromatics compared to the isolated nanocatalysts or surface-deposited catalysts. The improved activity and stability comes from the physical confinement of metal nanoparticles and good mass transportation of substrate/product within the support particles. This work proposed a novel method to prepare highly dispersed metal catalysts, which could be potentially useful to heterogeneous catalytic reactions with high-throughput and long-life demands.

Dry reforming of methane (DRM) is one of the most valuable ways to convert carbon dioxide (CO2) and methane (CH4) simultaneously. Although Ni-based catalysts have been widely used due to...