Ir/SiO2 and Rh/SiO2 catalysts showed excellent activity for NO reduction with CO or H2 in the presence of O2 and SO2. Ir/SiO2 catalyzed NO reduction with both CO and H2, whereas Rh/SiO2 catalyzed reduction only with H2. The most important characteristic was that coexistence of O2 and SO2 is essential for NO reduction to occur. Surface science investigation using Ir(111) single crystal model catalyst revealed that the atomic sulfur was formed via disproportionation of SO2 and reacted with oxygen adsorbed on the surface to form SO2, which desorbed from the surface. Therefore, the iridium surface reverted to its initial metallic state. FT-IR measurements on Ir/SiO2 also indicated that the SO2 both stabilized and created Ir0 sites in the oxidizing atmosphere. The addition of Li and Ba to Ir/SiO2 and Zn to Rh/SiO2 was quite effective to enhance the catalytic activity for NO reduction in the presence of O2 and SO2 by acting as oxidation retardant to prevent deactivation of the active Ir and Rh metals supported on SiO2.
The recycling ratio of reclaimed asphalt pavement (RAP) reached about 99% in 2002, the highest for any industrial waste, a clear sign that recycling efforts are actively applied in the road pavement field. Even more effective use of resources and materials will require the incorporation of environmentally-friendly processes over the entire cycle. It is also necessary to establish a pavement recycling system that can cope with the diversification of pavement materials and reclaimed materials, such as modified reclaimed materials, of which production of which is predicted to increase. This study proposes a pavement recycling technique in which high-temperature and high-pressure water is used to separate and recover aggregate and asphalt binders in RAP for reuse. The removal performance of two types of deteriorated asphalt binders was evaluated. The properties and quality of separated and recovered aggregate were also tested to examine the suitability of the recovered aggregate as pavement. The tests and analyses showed that high-temperature and high-pressure water was very effective for removing deteriorated binders and modified binders. High-temperature and high-pressure water is an environmentally friendly recycling technique with great potential and repeated reuse of recovered aggregate is feasible.
To improve the lifetime of catalysts for CO2 reforming of methane, Ni/H-mordenite catalyst was modified, which has high performance for the reaction. The unmodified catalyst was deactivated due to collapse of the zeolite structure at 1173 K, and the catalyst activity was reduced by carbon deposition at 923-973 K. Two methods of modification were evaluated to suppress deactivation of the catalyst. Firstly, surface modification of the mordenite support with alumina or titania resulted in no deactivation at 1173 K. XRD analysis of the fresh and the used catalysts showed higher stability of the modified catalysts. Secondly, Co-loading of nickel with cobalt and/or potassium resulted in suppression of the catalyst deactivation by carbon deposition at 973 K. Finally, a new catalyst with longer lifetime, Ni-Co-K/HM-Al2O3, was prepared with activity maintained for more than 300 h at 973 K.
To develop a gasification process for biomass, the steam reforming reaction of acetic acid, which is one of the major components of bio-oil, was carried out using Ru catalyst supported on zirconia prepared by a sol-gel method and/or a template method. The catalysts prepared by the sol-gel method consisted of 10-20 nm zirconia crystallites, with nano pores (mean diameter about 10 nm) formed by the grain boundary. The surface areas of catalysts prepared by the sol-gel method were larger than those of Ru/JRC-ZrO2 catalyst prepared from the reference catalysts (JRC-ZRO-2, Catalysis Society of Japan). Catalytic activity was tested using acetic acid solution (CH3COOH/H2O mole ratio = 3) in a flow reactor. Except for the Ru/ZrO2-SDS catalyst prepared using sodium dodecyl sulfate as a template, the Ru/ZrO2-n catalysts promoted acetic acid steam reforming reaction at 673 K. In particular, hydrogen formation activity and stability over Ru/ZrO2-W catalyst, prepared by the sol-gel method without templates, was highest over the catalysts prepared in this study. All catalysts used in this study provided ratios of (hydrogen formation rate)/(carbon dioxide formation rate) smaller than 2, which is the stoichiometry of the acetic acid steam reforming reaction. Therefore, the steam reforming reaction competes with direct decomposition of acetic acid.
Heterocyclic compounds including nitrogen (quinoline, isoquinoline, and pyridine) were separated from n-heptane mixtures through supported liquid membranes using room temperature ionic liquids, based on 1-alkyl-3-methylimidazolium and quaternary ammonium salts. The organic nitrogen compounds selectively permeated the membranes. The differences in the structures of room temperature ionic liquids had little effect on the permeability of organic nitrogen compounds. Liquid membranes that used more hydrophilic room temperature ionic liquids yielded higher selectivity. Lower pyridine concentration and temperature caused increases in selectivity. Application of supported liquid membranes based on ionic liquids has potential for the separation process of organic nitrogen compounds and heptane.
H2 production from biomass is an important area of research. Steam reforming of apple pomace at high temperatures at > 973 K was carried out over a commercial steam reforming Ni catalyst using a fluid bed reactor. The Ni catalyst could catalyze the reaction between apple pomace and H2O to produce H2. The balance between the reactant apple pomace and the product gases together with thermogravimetric data suggested that apple pomace was decomposed to H2, CO, CH4, CO2 and carbon deposits prior to steam reforming, and the resultant deposited carbon reacted with H2O to produce H2, CO, and CO2. This conclusion was supported by the observation that potassium and calcium compounds added to the Ni catalyst considerably increased the extent of gasification, probably by promotion of the reaction between deposited carbon and H2O. Enhancement of the reaction between deposited carbon and H2O is a possible way to develop a high performance system for H2 production from steam reforming of biomass.
Low viscosity base oils are one of the candidates for fuel saving lubricants for internal combustion engines. These lubricants reduce viscous friction under hydrodynamic conditions, so reduce total energy loss at tribological contact. However, these oils provide thinner oil films resulting in magnified wear. Therefore, wear protection of rubbing surfaces is very important to apply low viscosity oils in practice. Effects of phosphorus-containing additives on antiwear properties of low viscosity base oils were evaluated under boundary lubrication conditions using a four-ball type wear tester according to ASTM D 4172. For mineral based oils, dialkyl phosphonates considerably reduced wear whereas trialkyl and triaryl phosphonates did not. Compatibility of additive with mineral based oil depends on the refining process of the oil. Wear prevention by phosphorus-containing additive in solvent-extracted mineral oils was sometimes unpredictable. Additive response for hydrogen-refined mineral oils was better than that for solvent-extracted oils. The results showed good accordance with phosphorus contents on the worn surfaces obtained by surface analysis. At least 0.062 mass% (620 ppm) of phosphorus is required to achieve sufficient antiwear properties in hydrogen-refined mineral oils. Synthetic esters have good lubricity in comparison with mineral oils. However, conventional antiwear additives for mineral oils are not always effective for synthetic esters, especially low viscosity esters. Hydroxyalkyl phosphates, with a polar functional group in the molecule, reduced wear effectively even at 0.016 mass% (160 ppm) of phosphorus in low viscosity synthetic esters. The new additives provided boundary films with high phosphorus contents. Kinetics of the boundary film formation were examined by the electric contact resistance method. Formation of the boundary film from the new additives was higher than that from conventional additives. The replenishment process of the boundary film under dynamic conditions is very important for low viscosity lubricants.
This paper describes a new wheel tracking test for analyzing movements of aggregates in mixtures. The test device is conducted using as examples four-layered specimens taken from two Swiss national motorways, where severe rutting (G section) and longitudinal cracking (H section) were observed. This test method was developed by Moriyoshi. Tests can be carried out under temperature distributions similar to field situation. Two-dimensional movements and strains between aggregates for four-layered specimens due to the moving wheel loads were analyzed by right angle for direction of wheel pass. For this purpose, the cross section of the slabs with a width of 30 cm was divided optically into 5 vertical subsections. The transverse permanent surface deformations, the area changes in the transversal subsections as well as the maximum deformation of the surface and layer-interface through the centerline of the applied wheel load were determined. Strain distributions between aggregates in mixtures at high temperature (45°C) under 600 passes were also measured by photo analysis. Test results show consolidation of the asphalt mixtures and material flow on the surface near the wheel load. The results also demonstrate that the aggregates (size of aggregate: 2 mm or larger) in each mixture move mainly in vertical direction. Large strains (40% or larger) between aggregates at summer condition were measured in the surface mixture near wheel track after 600 passes.