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ディーゼル自動車から排出される黒煙，粒子状物質（PM）低減に向けて金属を含まない無灰系添加剤の検討を行った。その結果，亜硝酸エステルや硝酸エステル系添加剤を軽油に添加すると，直噴エンジンで回転数2100 rpm，負荷80％ の定常運転では黒煙やPMの低減が認められた。特に，黒煙低減効果は筒内の酸素濃度が低いほど大きくなった。また，筒内燃焼圧のサイクル変動を抑制する効果も認められた。 含酸素化合物については，燃料油中の酸素濃度を増加させるほど黒煙低減率も増加した。ただし，サイクル変動については抑制効果が認められなかった。 次に，副室式エンジンを用いて，ディーゼル自動車10・15モード排出ガス測定法に基づいた試験を行った結果，軽油に亜硝酸n -ヘキシルを添加した所，燃費向上と同時にPM低減，NOx低減が認められた。

Nano-sized titanium oxide particles were synthesized in a stationary, laminar, premixed, stagnation flame burning an ethylene–oxygen–argon mixture at an equivalence ratio of 0.36 under the atmospheric pressure. The titanium precursor, titanium tetraisopropoxide (TTIP), was fed into the flame by a carrier argon flow through a heated TTIP bath. Particles synthesized in this flame were characterized for their size distribution, morphology, phase purity, and crystal structure, by scanning mobility particle sizer, transmission electron microscopy, and X-ray diffraction. It was found that the mean diameter of the particles was highly controllable and ranged from 3 to 6 nm depending on TTIP loading. The particle size was nearly uniform, and particles appeared to be single crystals without excessive aggregation. XRD analyses show that particles directly synthesized in the flame are pure anatase. Upon sintering and size growth on the flame stabilizer, a notable portion of particles transformed into rutile with much larger crystal sizes.

The effects of the volume and pH of the impregnation solution and of the calcination conditions were examined on the physicochemical and catalytic properties of a 13 wt% MoO3/Al2O3 extrudate catalyst. The Al2O3 support and drying procedures (static conditions without flowing air) were fixed in the preparations. In the present series of catalysts, the amount of crystalline MoO3 was marginally small. It was found that the dispersion of Mo oxide species increased as the volume of the impregnation solution increased, gradually approaching a maximum value. The increase in pH (2–8) of the impregnation solution was found to reduce the dispersion of Mo oxide species. The Mo dispersion increased slightly for the impregnation catalysts as the calcination temperature increased (673–873 K), whereas it decreased for the equilibrium adsorption catalysts. The effects of the calcination atmosphere (with or without flowing air, or with flowing humid air) were very small on the dispersion of Mo oxide species under the present preparation conditions. On the other hand, the methanol oxidation activity of MoO3/Al2O3 was sensitive to the preparation parameters examined here. It was demonstrated by means of EPMA and XPS that a considerable migration of Mo took place during the calcination. In the present study on the preparation of a 13 wt% MoO3/Al2O3 catalyst, an impact index is proposed to measure the magnitude of the effects of the respective parameter(s) on the physicochemical and catalytic properties. With the Mo dispersion, the effects of the preparation parameter decreased in the order, surface area of the support >> drying process > volume of the impregnation solution > pH, calcination temperature and atmosphere. The size of the impact index for the dispersion of Mo sulfide species is 70–75% of that for the Mo oxide species. The HDS activity of the catalyst was less affected by the preparation parameters than the Mo sulfide dispersion. The preparation parameters affected the segregation of Mo on the outer surface of extrudates in a decreasing order: drying process > volume of the impregnation solution > pH, calcination conditions. It was found that the oxidation of methanol was affected most intensely by the drying procedures. The volume of the impregnation solution, calcination conditions and pH of the impregnation solution also strongly affected the oxidation activity. The impact index suggests that the sensitivity to the preparation variables of the physicochemical and catalytic properties of MoO3/Al2O3 decreases in the order, methanol oxidation activity > surface Mo segregation > Mo oxide dispersion > Mo sulfide dispersion > HDS activity.

In the present part of the group study on the preparation of 13 wt% MoO3/Al2O3, the effects of drying processes were investigated on the physicochemical and catalytic properties. Two series of catalysts were prepared by a conventional impregnation technique and by an equilibrium adsorption method using a common extrudate support. XPS and EPMA results demonstrated that the distribution of Mo oxide species in extrudates was strongly affected by drying processes. A rapid drying, in particular at a reduced pressure, was found to induce a strong segregation of Mo oxides on the outer surface of the extrudates, forming a sharp egg shell type distribution of Mo. On the other hand, drying under static conditions produced a moderate egg shell type distribution, suggesting that a slow drying rate is favorable for a homogeneous distribution of Mo. The equilibrium adsorption technique was found to provide considerably flat Mo profiles inside the extrudates except for the utmost surfaces where Mo concentrations increased steeply.

Ten types of 13 wt% MoO3/Al2O3 catalysts were prepared by a conventional impregnation or equilibrium adsorption method using a common extrudate support. These catalysts were subjected to a comprehensive characterization and catalytic reactions to find important preparation parameters in practical preparations. It was demonstrated in the present group study that the formation of crystalline MoO3 was strongly correlated with the Mo segregation on the outer surface of the extrudate. When the amount of the impregnation solution was large (ca. 10 cm3 g-Al2O3−1), a considerably homogeneous distribution and high dispersion of Mo oxide species were attained irrespective of the other preparation parameters. It is suggested that when a pore volume impregnation or incipient wetness technique is employed, drying processes strongly affect the dispersion and distribution of Mo oxide species. Drying at a reduced pressure is suggested to result in a segregation of Mo oxides on the outer surface of the extrudate, and accordingly a formation of crystalline MoO3.

It is demonstrated that the structural control of the metal ion precursors in the impregnating solution by adding the chelating agents is effective to prepare the higher active CoMo supported on alumina catalysts (Co-MoAl2O3) for hydrodesulfurization (HDS). Coordination structures of the Co and Mo complexes in the CoMo impregnating solution and distributions of the Co and Mo complexes were evaluated by spectroscopic characterization techniques and by using a computational calculation, respectively. An addition of a chelating agent, such as NTA (nitrilotriacetic acid) and Glu (L-glutamic acid), in the CoMo solution results in the selective formation of the Co complexes, while the amount of the Mo complex is negligibly small at the practical pH of 9.2. The addition of the chelating agent increases the thiophene HDS activity of the sulfided catalysts typically by 50%, compared with that prepared without the chelating agent. Dispersion results of Co and Mo species on both oxidic and sulfided catalysts indicate that the higher HDS activity is explained by the higher degree of surface exposure of Co sites (namely the dispersion of Co) rather than that of Mo sites. The selective formation of the Co-chelate complexes keeps Co ions stable in solution up to high concentration. Furthermore, the Co complexes are estimated to be stable on the support even in the initial step of calcination, which would depress the formation of crystalline Co compounds, such as CoAl2O4 and CoMoO4. These effects result in the higher dispersion of the active Co surface species.

The effect of hardness and grain size of steels and their welds on fracture stress and sensitivity of Liquid Metal Embrittlement Cracking in molten Zinc (LMEC) was investigated. The experiment was conducted using commercial weldable structural steels and Sustained Load Test (SLT) was conducted in molten Zinc with heating range of 430°C-470°C.The results obtained are as follows.(1) The LMEC behavior of steels and welds in molten Zinc is of thermal activated process, and fractures are intergranular (IG) type which corresponds to actual LMEC in hot dip galvanizing.(2) Estimation of fracture stress of steels and welds in molten Zinc is obtained by measuring Vicker's hardness and grain size, and these estimation values are correspond with test results.(3) The sensitivity of LMEC is affected by hardness of steels and welds.

The liquid metal embrittlement cracking (LMEC) of heat affected zone (HAZ) of steel in hot dip galvanizing was investigated. The experiment was conducted using synthetic HAZ of JIS G 3444 STK55 and Sustained Load Test (SLT) at 370°C-470°C heating range in liquid (molten) and solid Zinc.The results obtained are as follows.(1) LMEC behavior is of thermal activated process and LMEC sensitivity is affected by hardness of HAZ.(2) The coarse grain region in HAZ showed the highest LMEC sensitivity.(3) The interfacial energy of steel is reduced by the existence of Zinc.(4) The reaction rate process of LMEC of steel is controlled by grain boundary diffusion of Zinc.(5) The nucleation and the propagation of LMEC in steel are likely to have a close relation to the reduction of interfacial energy due to the grain boundary diffusion of Zinc.

This study deals with the estimation of occurrence and preventive condition of the Liquid Metal Embrittlement cracking (LMEC) due to hot dip galvanizing using Y-Groove Crack ing Test pieces.The results obtained are as follows, (1) Using Y-Groove Cracing Test piece is appropriate for the estimation test of the LMEC in welded steel structures.(2) The critical condition for LMEC occurrence is indicated by the relation between the intensity of restraint and the maximum hardness in HAZ (Hv max.).(3) The LMEC preventive condition for welded steel structures to be galvanized are obtained by the Hv max. under the condition that welded joints have the most severerity value of the intensity of restraint in each type of structure. For example, the LMEC preventive condition of weldment in transmission tubular tower structures is assumed that Hv max. keeps less than 260.