A series of research developments are summarized based on the research and development of a dimethyl ether (DME) medium-duty truck as below.
- Examination of lubricity improvement which is an important fuel characteristic,
- Engine and vehicle development,
- Evaluation of the emission characteristics including trace levels of harmful substances,
- Vehicle field test.
Evaluation of lubricity used newly developed equipment to evaluate the effects of lubricity improvers. Checking the correlation between the durability of the injection pump and lubricity on fuel, and normalizing the equipment, allowed standardization of the evaluation method of lubricity for DME.
Investigation of trace level emissions found that the unique fuel properties of DME affect the emission levels, so DME has great potential for satisfying more severe emission regulations compared to conventional diesel fuel.
In vehicle and field testing, the overall quality of the DME truck was improved by solutions for the problems that occurred during the field tests.

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Advantages and effectiveness of using an organic polydentate ligand in the sol-gel process were discussed. The sol-gel method using the ligand was presented herein for preparation of metal oxides including mixed oxides. Design of metal oxide particles using organic polydentate ligands, i.e., control of specific surface area, particle size, pore size, and structure, was examined for silica, alumina, iron oxides, and some mixed oxides. Furthermore, regarding the mixed oxides, the dispersibility of constituent particles and homogeneity of the composition were compared among the sol-gel, coprecipitation, and kneading methods. The mixed oxides prepared using the sol-gel method showed the highest dispersibility and homogeneity. Reflecting this, the sol-gel silica/alumina was much more acidic and effective for alkylation of aromatics than the coprecipitation and kneading ones. The sol-gel method also yielded thermostable alumina and alumina mixed oxides that were useful as combustion catalyst supports; platinum-loaded or palladium-loaded sol-gel alumina, and alumina mixed oxides showed high performance for model purification reactions of exhaust gas. Regarding the supported metal catalysts prepared using the sol-gel method, ruthenium/silica and palladium/silica catalysts activated in hydrogen without calcination, respectively showed high performance for partial hydrogenation of benzene to cyclohexene and for conversion of acid chlorides to the corresponding aldehydes. Furthermore, ruthenium/tin/alumina catalysts activated in a similar manner converted unsaturated fatty acids to corresponding alcohols through hydrogenation while maintaining carbon-carbon double bonds. This type of ruthenium/tin/alumina catalyst was also effective for conversions of aromatic acids and dibasic acids, respectively, to the corresponding alcohols and diols via hydroxycarboxylic acids.

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Phenylpropanoids are one of the metabolic products of phenylalanine and tyrosine. The antioxidant and photo- antioxidant activities were studied kinetically and along the metabolic pathway, to investigate the possibility of application to petrochemical products. The metabolites showed only slight photo-antioxidant activities, compared with a commercial ultraviolet absorber (2-hydroxybenzophenone). In contrast, almost all metabolites showed higher or more excellent antioxidant activities than a typical commercial antioxidant, 3,5-di-t-butyl-4-hydroxytoluene (BHT). Ethyl caffeate can trap 2.7 mol/mol of peroxy radicals, and has 2.4 times higher antioxidant performance than BHT. Such a metabolite can be safely applied to petrochemical products as an excellent antioxidant for food preservation or food containers.

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Ba-doped Ir/WO₃-SiO₂ catalyst has high activity and good durability for the selective catalytic reduction of NO with CO in the presence of O₂ (CO-SCR). The performance of this catalyst was investigated for real diesel exhaust. In addition, the possibility of a combined catalytic system using CO-SCR and NH₃-SCR was evaluated. Ba/Ir/WO₃-SiO₂ catalyst provided more than 45% conversion with 3000 ppm CO at 280°C under SV (space velocity) <6000 h⁻¹, even with high oxygen concentrations. The activity of a combined catalyst system using Cu-BEA for NH₃-SCR and Ba/Ir/WO₃-SiO₂ for CO-SCR was evaluated. The combined catalyst provided about 60% NO_x conversion when only NH₃ was added. NO_x conversion was further increased with the addition of 3000 ppm CO. Thus, the efficiency of the combined system was confirmed. Improvement of activity under high space velocity and prevention of catalyst deactivation by smoke are the key targets for the development of practical systems.

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