μ波重畳無基材脱硫フィルターによるディーゼルエンジンのゼロエミッション化

金沢大学理工研究域機械工学系新規反応場の効果の検証ならびに，繊維状材料の新規合成法の確立による脱硫性能の向上の検討を実施した．脱硫だけでなく脱硝性能の発現の可能性を模擬排ガス中に窒素酸化物も導入して検討した．オゾン非導入時，脱硫性能は，窒素酸化物の硝酸塩化反応が阻害因子となり性能が低下した．それと同時に，脱硝性能も，硫黄酸化物の硫酸塩化に伴い阻害され性能が低下した．本結果より二酸化マンガンの脱硫脱硝性能はそれぞれの酸化物の塩化反応により阻害されることを明確にした．本フィルターにオゾンを導入し同様の検討を行った結果，オゾンによる酸化活性の向上に伴い，脱硫脱硝性能ともに向上し，特に脱硝性能は大きく向上したことを明らかにした．The potential study of novel plasma-assisted exhaust gas filter and synthesis of novel materials having low temperature activation by utilizing electron spinning method is investigated. In this year, gas purification performance including not only SOx but also NOx is evaluated to confirm the possibility of contemporaneous removal of SOx and NOx. The performance of DeSOx is reduced by NOx because of generation of nitrite. However, it is found that The performance of DeSOx and DeNOx is promoted by the existence of ozone which is generated by non thermal plasma. From this study, Plasma assist proves to be effective.研究課題/領域番号:15K16140, 研究期間(年度):2015-04-01 - 2017-03-3

ラディアル構造化プラズマ支援脱硫フィルターによるゼロエミッションディーゼルの開発

金沢大学理工研究域機械工学系ディーゼルエンジンはガソリンエンジンに比べて，燃費が良く，CO2排出量が少ないため内燃機関として普及が進められている．しか し，燃焼機構の特徴から窒素酸化物 NOx や硫黄酸化物 SOx を排出してしまう問題が挙げられる．これまでMnO2を担持した脱硫フィルターを用いて移動体搭載に向けたSOx浄化技術の確立を目指してきた．浄化性能向上に向けて排ガスに大気圧非平衡プラズマを重畳させることで生成される非平衡反応 場を応用した浄化プロセスを提案した．結果として，大気圧非平衡プラズマを反応部上流に重曹してガス改質することでSO2捕集能力は向上することを明らかにした．Compared with otto cycle, diesel engines have better conversion efficiency and lower CO2 emissions, and therefore, it is becoming popular as internal combustion engines. However, there is a problem that nitrogen oxides NOx and sulfur oxides SOx are emitted due to the characteristics of the combustion mechanism. We have aimed to establish SOx purification technology for mounting on moving bodies using desulfurization filters supporting MnO2. To improve the purification performance, we proposed a purification process that applies the nonequilibrium reaction field generated by superimposing atmospheric pressure nonequilibrium plasma on the exhaust gas.As a result, it was clarified that the SO2 trapping ability is improved by the atmospheric reforming of non-equilibrium plasma with sodium bicarbonate upstream of the reactor to reform the gas.研究課題/領域番号:17K00595, 研究期間(年度):2017-04-01 - 2020-03-31出典：「ラディアル構造化プラズマ支援脱硫フィルターによるゼロエミッションディーゼルの開発」研究成果報告書　課題番号17K00595（KAKEN：科学研究費助成事業データベース（国立情報学研究所））（https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-17K00595/17K00595seika/)を加工して作

大気圧プラズマを併用したゼロエミッションディーゼル用低温作動脱硫フィルターの開発

ディーゼルエンジンのゼロエミッション化を目指して，大気圧非平衡プラズマ重畳による低温脱硫性能の発現ならびに無基材脱硫フィルターによる小型化を提案した．大気圧非平衡プラズマ重畳効果の明確化のため，バリア放電によるオゾン生成が脱硫性能を向上させることを明らかにした．また，無基材脱硫フィルターにより，これまでの既存フィルターより5倍程度の小型化を達成した．しかし，フィルター合成時の熱負荷によって材料利用率が低下し，熱負荷の軽減によりさらなる小型化が達成可能であることを示した．Atmospheric non-equilibrium plasma induced substrate-less DeSOx filter is proposed for improvement of low temperature activation in dry desulfulization. It was clear that low temperature desulfurization performance is improved by the generation of ozone applied barrier discharge plasma. However, in detail of mechanism why SO2 absorption performance is improved by generation of ozone is not proclaimed. in our future work, clarification of this mechanism must be investigated.Miniaturization is achieved by substrate-less MnO2 DeSOx filter in according to remove honeycomb substrate which is occupied about half volume of DeSOx filter in comparison with conventional MnO2 DeSOx filter supported on honeycomb substrate. Its volume became 5 times smaller than conventional filter. However, this result falls short of expectations because of heat degradation of MnO2. So, more small filter can be achieved by improvement of heat treatment.研究課題/領域番号:25740031, 研究期間(年度):2013-04-01 - 2015-03-3

The Origins of the High Performance of Pd Catalysts Supported on Carbon Black-Embedded Carbon Nanofiber for Formic Acid Oxidation

In this study, we developed a carbon black (CB)-embedded carbon nanofiber (CNF) as a Pd support, which showed a high level of formic acid oxidation reaction (FAOR) activity. For the support preparation, heat treatment involving calcination at 1000 °C in a nitrogen atmosphere (carbonization) followed by calcination at 850 °C in water vapor (steam activation) was conducted to form a CB, which contained carbon nanofibers made from a polyacrolynitrile (PAN) fiber prepared by electrospinning. This catalyst showed a high level of FAOR activity. In this situation, the CB was also heat-treated, therefore, it was unclear whether the origin of the high FAOR activity of the CB-embedded CNF was caused by the CNF itself or the heat treatment of the CB. In order to establish the cause of the high FAOR activity of the CB-embedded CNF, the CBs underwent several heat treatments; i.e., stabilization, carbonization, and steam activation. Two types of carbon black with different pore structures, i.e., Ketjen black and Vulcan XC-72, were used to investigate the FAOR activity. The appropriate heat treatment of the CB promotes the improved FAOR activity; however, excessive heat treatment caused a deterioration in the FAOR activity, especially for Ketjen due to the presence of numerous micropores. However, by embedding the CB into the CNF, the FAOR activity improved, especially in the case of Ketjen, even though the embedded CB underwent several heat treatments. The optimum ratio of CB/PAN in the CB-embedded CNF was also investigated. The highest FAOR activity was observed at 0.25 CB/PAN for both the Vulcan and Ketjen. The electronic state of Pd3d in which the binding energy of the metallic Pd shifted to a lower binding energy suggested that the metal–support interaction is strong at the CB/PAN ratio of 0.25. On the basis of these results, it was found that heat treatment of the CB by embedding it in the CNF is a promising way to achieve a metal–support interaction without destroying its structure

Effect of Doped Alkali Metal Ions on the SO2 Capture Performance of MnO2 Desulfurization Materials at Low Temperature

Sulfur dioxide (SO2) emissions from diesel exhaust pose a serious threat to the environment and human health. Thus, desulfurization technology and the performance of desulfurization materials must be improved. In this study, MnO2 was modified with various alkali metal ions using the impregnation method to enhance its SO2 capture performance. The composites were characterized intensively by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, and Brunauer-Emmett-Teller theory. The SO2 capture performance of these composites were measured via thermogravimetry, and the effect of doping with alkali metal ions on the SO2 capture performance of MnO2 was investigated. Results showed that the SO2 capture performance of MnO2 could be enhanced by doping with alkali metal ions, and the MnO2 composite doped with LiOH (2.0 mol/L) had the best SO2 capture capacity (124 mg(SO)(2)/g(Material)), which was 18% higher than that of pure MnO2. Moreover, the type and concentration of alkali metal ions had varying effects on the SO2 capture performance of MnO2. In our experiment, the SO2 capture performance of the MnO2 doped with NaOH, LiCl, Na2CO3, K2CO3, and Li2CO3 composites were worse than that of pure MnO2. Therefore, the influences of the type and concentration of alkali metal ions to be doped into desulfurization materials must be considered comprehensively

Preparation of various manganese dioxide composites and their desulfurization performance

The performance of desulfurization materials plays a key role in desulfurization technology. In this study, different types of manganese dioxide (MnO2) composites were prepared to improve desulfurization performance. These composites were characterized intensively via SEM, XRD, XPS, and BET. Desulfurization performance was measured through thermogravimetry (TG), and the desulfurization mechanism of different types of MnO2 composite was investigated. Results showed that the desulfurization performances of MnO2 composites are determined by the combined effects of the materials' pore structure, specific surface area, active components and Mn valence contents. The desulfurization performances of high specific surface area MnO2 and porous MnO2 were enhanced on account of their excellent physical structures. The desulfurization performance of alkali metal additive LiOH doped MnO2 improved through the addition of active components. The desulfurization performance of bimetallic oxide MnO2/CeO2 improved through the synergistic effect of bimetallic oxides. The desulfurization performance of carrier type MnO2/NaY improved through the dispersion of MnO2 particles. Among the composites obtained, porous MnO2 revealed the best desulfurization performance, this composite demonstrated an average SO2 capture rate of 0.283 g(SO2)/g(material).h within the first hour of reaction, and its SO2 capture capacity was 0.633 g(SO2)/g(material). (C) 2020 Published by Elsevier Ltd on behalf of Energy Institute

The influence of exhaust gas compositions in MnO2 dry DeSO(x) filter for diesel emission control

Sulfur dioxide purification has adverse effects on the environment and the human body. In this study, the dry desulfurization process from exhaust gas exhaust by dry DeSO(x) filter is investigated for constructing a sulfur-based capture-and-reuse system. The activated MnO2 having a high-specific surface area (HSSA MnO2) is utilized as an absorbent to indicate high SO2 capture performance in the low-temperature region. To improve the capture performance, (SO2 concentration, space velocity, and gas composite) is analysed on SO2 capture performance of dry DeSO(x) filter. Results showed that SO2 capture performance in high SO2 concentration was constant regardless of space velocity. However, in low SO2 concentration, the SO2 capture performance decreased with increasing space velocity. Moreover, the presence of H2O in the flow gas exhibited a beneficial effect on SO2 capture performance. [GRAPHICS]

Effect of hydrogen addition on combustion and heat release characteristics of ammonia flame

As a key parameter of fuel, the heat release characteristics of ammonia (NH3) flames under hydrogen (H-2)-enriched conditions constitute the emphasis of this research. The effect of H-2 addition on heat release characteristics of premixed laminar NH3 flames are numerically investigated by considering the detailed chemical mechanism. The NH3,O-2,H2O,NO, and N2O mole fraction distributions based on the Dagaut-Keromnes mechanism agree well with experimental results, thereby potentially providing repeatable and accurate outcomes with NH3 flames using this mechanism. The OH x N radical positively affects the net heat release rate at various equivalence ratios and H-2 addition ratios conditions. The chemical effect is evidently important at low H-2 addition ratios, while the transport effect becomes dominant at high H-2 addition ratios because of the high mobility of H-2. For the three top endothermic elementary reactions of NH3 flames, the contribution of R236: H + O-2=OH + O increases, while R171: H + NO(+M) = HNO(+M) and R240: H2O + O=OH + OH decrease with increasing H-2 addition ratios. Diverse key exothermic elementary reactions of NH3 flames occur at various equivalence ratios and different H-2 addition ratios. The large contribution of R128: N + NO=N-2+O at fuel-rich conditions can be applied to reduce NOx emissions of the NH3 flame under pure and H-2 addition conditions. (C) 2019 Elsevier Ltd. All rights reserved