Maki Matsuka

Ce0.6 ( Mn0.3Fe0.1 ) O2 as an Oxidation-Tolerant Ceramic Anode for SOFCs Using LaGaO3-Based Oxide Electrolyte

The anodic performance of CeO 2 doped with Mn and Fe was studied by using a Co-doped LaGaO 3 -based oxide (LSGMC) electrolyte. The open-circuit potential approximate to the theoretical value (1.1 V) was exhibited on the cell using Ce(Mn,Fe)O 2 oxide for the anode. A high maximum power density (0.622 W/cm 2 at 1273 K) was attained by co-doping Mn and Fe into CeO 2 . After a few cycles of oxidation treatment at 1073 K, there was an increase in the maximum power density. Therefore, Mn- and Fe-doped CeO 2 is a potential oxidation-tolerant oxide anode for solid oxide fuel cells (SOFCs) using an LSGMC-based electrolyte.

Numerical study of hydrogen permeation flux in ytterbium doped strontium cerate and thulium doped strontium cerate (II)

This study analyses the hydrogen permeation flux model with (1) modifications in the defect concentration calculations where the concentration of substitutional cation on cerium site is utilised as the independent variable for the calculation, instead of the previous step-wise calculation with the concentration of oxygen vacancy as the independent variable and (2) the additional terms to include the oxygen partial pressure gradients for calculation of hydrogen permeation flux. The modification in the defect concentration method allows a short model simulation run time, which consequently allows incorporation of the concentration constraints in the parametric sensitivity analysis, but still produces the same set of defect concentrations as calculated in the previous methods. It is also found in this study that the discrepancy between the model and experimental results (in terms of the effect of changes in hydrogen partial pressure gradients on the hydrogen permeation flux) is not due to the influence of oxygen partial pressure gradients. Parametric sensitivity analysis shows that there is no significant difference in the sensitivity of the model by comparing Case A and B. The result of parameter tuning to predict the hydrogen permeation flux for 5% thulium doped strontium cerate in Case B shows a similar trend to the previous study (Case A). These results suggest negligible oxygen ion conductivities in these types of membrane, as reported in the literature.

Effects of fluorinated hydrocarbon addition on H2O2 direct synthesis from H2 and air over an Au–Pd bimetallic catalyst supported on rutile-TiO2

Synthesis of H2O2 by oxidation of H2 with air on Au–Pd/TiO2 was studied and it was found that H2 conversion and H2O2 selectivity were strongly affected by the crystal phase of the TiO2 support for Au–Pd. At 0.1 MPa, brookite type TiO2 was active for H2O2 synthesis because of high H2 conversion (40%) and selectivity (67%). In contrast, rutile type TiO2 showed high H2 conversion but low selectivity. With increasing H2 pressure, H2O2 selectivity increased on Au–Pd/rutile TiO2 and the H2O2 yield became much higher on the catalyst supported on rutile TiO2 than those on brookite or anatase at 1.0 MPa. The effects of fluorinated hydrocarbon addition to reaction media were also studied, and it was found that the addition of a small amount of fluorinated hydrocarbon was effective for increasing H2O2 productivity. The optimized fluorinated hydrocarbon was CF3(CF2)5CF3, and the amount was 1/10 (7.5 ml) of the reaction media (75 ml). The H2O2 formation rate of 3.78 mmol h−1 was achieved under the optimized conditions, and the concentration of 1.8 wt% H2O2 was achieved after 20 h.

Mixed Conductivity, Nonstoichiometric Oxygen, and Oxygen Permeation Properties in Co‐Doped Sr3Ti2O7−δ

Electrical conductivity and oxygen permeation rates in Co-doped Sr(3)Ti(2)O(7-δ) with Ruddesden-Popper type structures were investigated. The effects of metal dopants (M) in the Ti site of Sr(3)Ti(2)(M)O(7-δ) on the mixed conductivity were also studied. Doping of Sr(3)Ti(2)O(7-δ) with Co was found to be effective for improving the electrical conductivity as well as the oxygen permeation rate, which could be assigned to the increased oxygen vacancy concentration by doping Co(3+) into Ti(4+) sites. The nonstoichiometric oxygen of these oxides was measured by using a thermal gravimetric method. The creation of oxygen vacancies, which is compensated with Co(3+) doping, leads to higher oxide ion conductivity. The oxygen permeation rate monotonously increased with increasing amounts of Co in the Ti site. Sr(3)Ti(0.8)Co(1.2)O(7-δ) exhibited high oxide ion conductivity and a large oxygen permeation rate. The highest oxygen permeation rate achieved a value of 2.02 cc min(-1) cm(-2) at 1273 K for Sr(3)Ti(0.8)Co(1.2)O(7-δ). Neutron diffraction analysis and redox titration suggests that the oxygen diffusion occurs through oxygen vacancies in the perovskite block, but not through excess oxygen in the rock salt block.

FCCU transition-probability model

The adequacy of the use of transition-probability matrices for modelling fluidised catalyst cracker unit emissions was investigated. A number of different-sized matrices that modelled the processes of attrition and agglomeration were used, and it was found that an 8x8 sized matrix provided the best results. The processes of attrition within the matrix were studied, indicating an oscillatory attrition curve, and may suggest a preferred attrition size range. Studies on the effects that the agglomeration parameters had on the model indicated that, as time and the size of the matrix increased, agglomeration became more important. The results of the modelling were compared with laboratory experiments, and indicated very good agreement between the model outputs and the observed emissions.