Effect Of Oxidation Catalyst Research Articles

Direct observation of accelerating hydrogen spillover via surface-lattice-confinement effect

Uncovering how hydrogen transfers and what factors control hydrogen conductivity on solid surface is essential for enhancing catalytic performance of H-involving reactions, which is however hampered due to the structural complexity of powder catalysts, in particular, for oxide catalysts. Here, we construct stripe-like MnO(001) and grid-like Mn3O4(001) monolayers on Pt(111) substrate and investigate hydrogen spillover atop. Atomic-scale visualization demonstrates that hydrogen species from Pt diffuse unidirectionally along the stripes on MnO(001), whereas it exhibits an isotropic pathway on Mn3O4(001). Dynamic surface imaging in H2 atmosphere reveals that hydrogen diffuses 4 times more rapidly on MnO than the case on Mn3O4, which is promoted by one-dimension surface-lattice-confinement effect. Theoretical calculations indicate that a uniform and medium O-O distance favors hydrogen diffusion while low-coordinate surface O atom inhibits it. Our work illustrates the surface-lattice-confinement effect of oxide catalysts on hydrogen spillover and provides a promising route to improve the hydrogen spillover efficiency.

Effect of oxide catalysts on the properties of bio-oil from in-situ catalytic pyrolysis of palm empty fruit bunch fiber

Fast pyrolysis is a potential technology for converting lignocellulosic biomass into bio-oil. Nevertheless, the high amounts of acid, oxygenated compounds, and water content diminish the energy density of the bio-oil and cause it to be unsuitable for direct usage. Catalytic fast pyrolysis (CFP) is able to improve bio-oil properties so that downstream upgrading processes can be economically feasible. Here, calcium oxide (CaO), magnesium oxide (MgO), and zinc oxide (ZnO) were employed due to their potential in enhancing bio-oil properties. The results showed that overall, all three catalysts positively impacted the empty fruit bunch fibre-derived bio-oil properties. Among the catalysts, CaO showed the most favorable effects in terms of reducing the acidity of the bio-oil and anhydrosugar. Thermal stability of bio-oils produced in the presence of CaO was studied as well.

I32 DPFシステムのPM酸化性能評価法について : DPF差圧に及ぼす酸化触媒の効果比較(I3 エンジンの燃焼(排気と計測2))

I32 DPFシステムのPM酸化性能評価法について : DPF差圧に及ぼす酸化触媒の効果比較(I3 エンジンの燃焼(排気と計測2))

Effect of Oxidation Catalysts on Diesel Soot Particles

The effect of a conventional oxidation catalyst and a novel particle oxidation catalyst (POC) on diesel particles is studied using identical methodology. Regulated particulate matter emission measurement is followed by analyzing soluble organic fraction. In addition, size distributions are measured using a partial flow sampling system with a thermodenuder as an option. A parallel ELPI-SMPS method is used to study the particle effective density and, further, the mass. Tests are conducted using a heavy duty diesel engine with a very low sulfur fuel. A decrease in particle mass was observed when using a catalyst. When using a conventional catalyst the decrease was attributed to the decrease of soluble organic fraction, while using POC the nonsoluble fraction was also found to decrease, by 8-38%. This observation is confirmed by particle number measurement, and POC was found to decrease the dry particle number concentration measured downstream of a thermodenuder by 13-28%. Further particle structure analysis indicated lower density values when using conventional catalyst or POC. The physical size of the particles was not changed noticeably over either catalyst--implying the soluble organic fraction was condensed onto the soot, filling the voids in the porous structure of soot agglomerates, when no catalyst is used.

Effect of Oxide Catalyst on Heterogeneous Nucleation in Fe-10mass%Ni Alloys

In order to elucidate the nature of heterogeneous nucleation, a differential scanning calorimetry (DSC) thermal analysis of Fe–10mass%Ni alloys containing oxide catalysts was conducted. For all oxide catalysts, the maximum frequency in the particle-size distributions diminishes and the modal value increases with a decrease in the amount of deoxidizers or with an increase in the elapsed time after deoxidizer addition. That is, the number of smaller particles decreases, while the number of larger particles increases. In proportion to this change of the particle-size distribution, the critical undercooling (ΔT) increases. For the same amount of deoxidizers and the same elapsed time, the value of ΔT for the primary crystal of the γ phase is smaller in the order of MgO, ZrO2, Al2O3, and CaO–Al2O3. Oxide catalysts grow by Ostwald ripening, therefore the growth can be controlled by the diffusion of oxygen. Thus, the decrease of the soluble oxygen content by strong deoxidizers results in the inhibition of particle growth.