It is significantly important to improve not only diesel emission but also fuel consumption simultaneously. It is difficult to achieve high NOx conversion by catalyst for low and middle engine load operations so that clean diesel combustion must be achieved by both innovative combustion technology and fuel technology. The aim of this study is to enhance clean diesel combustion operation range (engine-out emission: NOx < 0.2 g/kWh, Soot < 0.02 g/kWh). In this study, performance of a single-cylinder test engine which has a hydraulic valve actuation system and ultra-high pressure fuel injection system was investigated. And also it was clarified how fuel properties, such as auto-ignitability, volatility and aromatic hydrocarbon component, would influence on combustion performance. The results show that lots of EGR (exhaust gas recirculation) could dramatically reduce NOx but increase soot. However low cetane number fuel could suppress soot formation because it elongated premixing periods of fuel and air. And high volatile fuel could also decrease soot formation because it promoted fuel evaporation and mixing with air. Cetane number and aromatic hydrocarbon component could affect on combustion performance with the hydraulic valve actuation system which can change compression ratio of the test engine to control auto-ignition and combustion timings, and with the ultra-high pressure fuel injection system which can make significant turbulence in the combustion chamber to achieve well-mixed mixtures. From the results from this study, it was concluded that an optimal fuel for a next-generation diesel engine has lower cetane number (CN: 40-45) and no aromatic hydrocarbon.
Antioxidant activities (including photo-antioxidant activities) of flavonoids were evaluated fundamentally and kinetically for the potential to produce plastic food packages with high antioxidant performance and food safety. Chalcones with two aromatic rings acquire additional another ring by ring-closure in the metabolic pathway of chalcones and form a flavanone (naringenin), with dramatically decreased antioxidant activities. As further metabolism proceeds, naringenin produces various flavonoids, which gradually acquire antioxidant activities comparable to and finally higher than those of chalcones. Therefore, a plant can again form an enhanced antioxidant, especially with photo-antioxidant activities. In general, flavonoids are present in the concentration of 1-10 mmol/dm3 in plants. The metabolite with the highest antioxidant activities, quercetin, was found to protect a plant almost completely in the concentration of 0.5 mmol/dm3 from harmful UV radiation. The complex metabolic pathway of tyrosine or phenylalanine to flavonoids will be partly necessary for the safe photo-synthesis of plants without suffering UV damage. Such flavonoids are expected to be useful for the safe stabilization of petrochemicals, especially food packages.
A series of Ru/Mn/Al2O3 catalysts with different concentrations of manganese were investigated on catalyst characterization and activity for Fischer-Tropsch synthesis in a continuous stirred tank reactor. The Ru/Al2O3 and Ru/MnO showed low catalytic activity and deactivation rate was clearly observed at 493 K and 2 MPa. On the other hand, the addition of small amount of manganese in Ru/Mn/Al2O3 (Mn/Al = 1/19) improved catalytic performance for Fischer-Tropsch synthesis. In an investigation, we observed a pressure effect between 1 and 6 MPa over Ru/Mn/Al2O3, and this catalyst showed high CO conversion and high stability with time on stream at 4 and 6 MPa. At 4 MPa, CO conversion was estimated to be about 95%. The catalysts were characterized by BET surface area, BJH porosity, CO chemisorption, XRD, TPR, TEM and XPS. Characterization results suggest that a suitable ratio of manganese to aluminum in Ru/Mn/Al2O3 increases the concentration of active ruthenium metals and it can be associated with the formation of manganese chloride at the catalyst surface.
H-ZSM-5 zeolite was treated with phosphorus acid by impregnating H-ZSM-5 with aqueous solutions of phosphoric acid at various concentrations. H-ZSM-5 (P-HZSM-5) modified with phosphoric acid was used as a catalyst for the methanol-to-olefin reaction. The molar ratios of P/Si and Si/Al in H-ZSM-5 and P-HZSM-5 were measured by EDX analysis. The Si/Al molar ratios of P-HZSM-5 increased with higher concentration of H3PO4 in the solution, which might be caused by partial dealumination of H-ZSM-5 by the H3PO4 treatment. The P/Si molar ratio of P-HZSM-5 after washing was proportional to the H3PO4 concentrations in the aqueous solutions. The remaining phosphorus species after the washing must be strongly adsorbed by interaction with the pore surface of H-ZSM-5 zeolite. The P-HZSM-5 catalyst showed very high propylene selectivity up to 57% with methanol conversion of 100%. Furthermore, catalyst stability was significantly improved for the P-HZSM-5 catalysts. Ammonia TPD spectra showed that the strong acid sites of H-ZSM-5 disappeared after the phosphoric acid treatment. Consequently, the formation of aromatics and coke was inhibited, resulting in higher light olefin selectivity and catalyst stability.
Hydrogenation of naphthalene in the presence of CO was examined as a step in the organic hydride method for utilizing low grade hydrogen. Development of CO-tolerant hydrogenation catalysts will allow this process to achieve purification and storage of hydrogen simultaneously, and hydrogen with high purity can be obtained by the dehydrogenation step. Pd catalysts supported on TiO2, Al2O3 and TiO2–Al2O3 mixed oxides prepared by the sol-gel method were evaluated. Using pure hydrogen as the reactant, Pd/TiO2–Al2O3 catalysts containing 50-80 wt% of TiO2 had high activity. Using hydrogen containing 2% CO, Pd/TiO2–Al2O3 catalyst containing 80 wt% of TiO2 had the highest activity. The synergetic effect of the mixed oxide support was more clearly observed in the presence of CO impurity than with pure hydrogen. CO probe FT-IR spectra contained 5 peaks, corresponding to the surface geometry. Adsorbed CO on coordinatively unsaturated sites, such as corner and edge sites, increased with higher TiO2 content. These sites released adsorbed CO at lower temperatures, indicating weaker adsorption. These coordinatively unsaturated sites are active for hydrogenation in the presence of CO.
Epoxidation of α, β-unsaturated carbonyl compounds is an important reaction in organic synthesis. In this study, epoxidation of α,β-unsaturated carbonyl compounds was carried out in hexane or water solvent, using hydrogen peroxide and calcium vanadateapatite (VAp) as a solid base catalyst. Calcium hydroxyapatite [HAp, (Ca10(PO4)6(OH)2)] is a typical apatite. Calcium vanadateapatite [VAp, (Ca10(PO4)6(OH)2)] was prepared by substituting VO4 for PO4 in the whole apatite matrix. The present study found excellent epoxidation in hexane as an organic solvent. In addition, the oxides were obtained in good yield in the presence of water and surfactant. The VAp could be easily recovered and reused.
Oxidative desulfurization of naphtha with H2O2 in the presence of H2SO4 in the naphtha/acetic acid (AcOH) biphasic system was investigated. All organosulfur compounds examined were smoothly oxidized in AcOH by peracetic acid effectively formed from AcOH and H2O2 in the presence of H2SO4. The order of the oxidation reactivities was sulfides, disulfides > benzothiophenes > thiophenes. The organosulfur compounds in octane were also oxidized with H2O2 in the presence of H2SO4 in the octane/AcOH biphasic system. The oxidation proceeded in the AcOH phase and most of the oxidized sulfur compounds resided in this phase, resulting in the successive removal of the sulfur compounds from the octane phase. This oxidative treatment effectively reduced the sulfur content of naphtha, and adsorption with silica gel further reduced the sulfur content to below 0.5 mass ppm. In addition, hydrodesulfurization is an effective pretreatment for this oxidative desulfurization of naphtha, resulting in further reduction of the sulfur content to below 0.1 mass ppm.
Solvent deasphalting (SDA) of heavy oil generally uses alkanes, from propane to heptane. The solvent power of propane is the weakest, and that of heptane is the strongest. Ethyl ether has slightly stronger solvent power than heptane. Dimethyl ether (DME), an alternative to diesel fuels, is thus expected to have good solvent power for SDA. DME was used for asphaltene separation from vacuum residue of Arabian Light crude oil (AL-VR) at DME/AL-VR weight ratio of 10-60, and compared with separation using pentane by the conventional method. The recoveries of maltene and asphaltene were comparable with pentane more at DME/AL-VR ratio by weight of over 40. Both maltene and asphaltene recovered by DME and pentane had almost the same H/C atomic ratio, hydrogen distribution and carbon aromaticity, respectively. The deasphalting performance of DME was equivalent to that of pentane.
Catalytic cracking of bitumen with steam was examined. The heavy oil fraction of bitumen reacted with active oxygen species generated from steam with the iron oxide catalyst, producing significant amounts of light oil. However, some coke formed in the reaction of bitumen using toluene solvent because the oxygen species might be insufficient to react with heavy oil fraction. To enhance the reaction of heavy oil with the oxygen species, 1-methylnaphthalene was used as solvent at higher time factor. As a result, coke formation was successfully suppressed.