15 research outputs found
Preparation of Exo-tetrahydrotricyclopentadiene Based High Energy Density Fuels
Preparation of Exo-tetrahydrotricyclopentadiene Based High Energy Density Fuel
四环庚烷的合成
以低沸点石油醚/丙酮为混合溶剂,芳香酮类化合物为光敏剂,对降冰片二烯异构化生成四环庚烷的反应进行了研究。考察了反应物初始浓度、光敏剂的用量及种类和时间对此反应的影响,得到四环庚烷合成的最佳工艺条件:室温下,初始浓度1.0 mol·L~(-1),6%二苯甲酮为光敏剂,紫外光照反应15 h,可获得93%转化率和100%选择性。反应液经减压蒸馏即可获得高纯度的四环庚烷燃料(73%收率,95%纯度)
TiO2促进的Ir/Al2O3催化剂用于氧化亚氮直接分解
Introduction
Doping transition metal oxides or alkali and alkaline earth metal oxides into noble metal based catalysts is an extensively used method to adjust the physiochemical properties of the catalysts and improve the catalytic activities [1]. However, TiO2 doped Al2O3 catalysts have been scarcely investigated, especially for the catalytic decomposition of N2O. In this work, an obvious activity improvement on direct N2O decomposition has been obtained on Ir/AlTix catalysts, and possible reasons have been explored with different characterization techniques. The high dispersity of Ir particles and special textural features of the catalysts have been assumed to closely correlate with the high activities.
Results and discussion
5 wt % Ir/AlTix catalysts with different atomic ratios of Ti/Al (x) were prepared with an impregnation method. Great improvement on the catalytic activities of direct N2O decomposition has been observed on the TiO2 doped catalysts (Fig. 1), which is obviously varied with the Ti/Al ratio. The highest activity was obtained on the Ir/AlTi1 catalyst, completely decomposing N2O at 350 oC, a fairly low temperature under the same test conditions. The reasons for the activity improvement have been detailedly investigated. The Ir particle sizes were found less than 3 nm and abundantly exposed on the surface of the doped catalyst (Fig. 2a), while the majority of Ir on the single oxide based catalysts were agglomerated into larger particles (Fig. 2b and 2c). The high dispersity of Ir particles may be responsible for the activity improvement of the TiO2 doped catalysts. More interestingly, SEM images revealed that rough surfaces with the fluffy structures were formed on the doped catalysts (Fig. 2d), in contrast, the surfaces of the single TiO2 or Al2O3 catalysts remained smooth and clean. These surface irregularities probably acted as obstacles to the immigration of Ir during the calcination process, finally resulting in the high dispersity of Ir particles as well as the high catalytic activities. Further studies on the role of TiO2 are still in progress.
Fig. 1. N2O activities of TiO2 doped Ir/Al2O3 catalysts Fig. 2. TEM and SEM images
Conclusions
TiO2 doped Ir/Al2O3 catalysts greatly promoted the catalytic activity of direct N2O decomposition, probably due to the high dispersity of Ir particles induced by the irregular surfaces.
References
[1] Junhua Li, Yongqing Zhu, Rui Ke, Jiming Hao, Applied Catalysis B: Environmental 80 (2008) 202–213.Introduction
Doping transition metal oxides or alkali and alkaline earth metal oxides into noble metal based catalysts is an extensively used method to adjust the physiochemical properties of the catalysts and improve the catalytic activities [1]. However, TiO2 doped Al2O3 catalysts have been scarcely investigated, especially for the catalytic decomposition of N2O. In this work, an obvious activity improvement on direct N2O decomposition has been obtained on Ir/AlTix catalysts, and possible reasons have been explored with different characterization techniques. The high dispersity of Ir particles and special textural features of the catalysts have been assumed to closely correlate with the high activities.
Results and discussion
5 wt % Ir/AlTix catalysts with different atomic ratios of Ti/Al (x) were prepared with an impregnation method. Great improvement on the catalytic activities of direct N2O decomposition has been observed on the TiO2 doped catalysts (Fig. 1), which is obviously varied with the Ti/Al ratio. The highest activity was obtained on the Ir/AlTi1 catalyst, completely decomposing N2O at 350 oC, a fairly low temperature under the same test conditions. The reasons for the activity improvement have been detailedly investigated. The Ir particle sizes were found less than 3 nm and abundantly exposed on the surface of the doped catalyst (Fig. 2a), while the majority of Ir on the single oxide based catalysts were agglomerated into larger particles (Fig. 2b and 2c). The high dispersity of Ir particles may be responsible for the activity improvement of the TiO2 doped catalysts. More interestingly, SEM images revealed that rough surfaces with the fluffy structures were formed on the doped catalysts (Fig. 2d), in contrast, the surfaces of the single TiO2 or Al2O3 catalysts remained smooth and clean. These surface irregularities probably acted as obstacles to the immigration of Ir during the calcination process, finally resulting in the high dispersity of Ir particles as well as the high catalytic activities. Further studies on the role of TiO2 are still in progress.
Fig. 1. N2O activities of TiO2 doped Ir/Al2O3 catalysts Fig. 2. TEM and SEM images
Conclusions
TiO2 doped Ir/Al2O3 catalysts greatly promoted the catalytic activity of direct N2O decomposition, probably due to the high dispersity of Ir particles induced by the irregular surfaces.
References
[1] Junhua Li, Yongqing Zhu, Rui Ke, Jiming Hao, Applied Catalysis B: Environmental 80 (2008) 202–213
Perovskite La1-xSrxFe1-yMnyO3 hollow nanospheres: the synthesis and the application in catalytic hydrogen peroxide decomposition
Perovskite La1-xSrxFe1-yMnyO3 hollow nanospheres: the synthesis and the application in catalytic hydrogen peroxide decompositio
一种贵金属催化剂及其制备和应用
本发明涉及一种贵金属催化剂及其制备和应用。该催化剂以TiO2改性的Al2O3为载体、VIII族贵金属为活性组分,能够显著改善氧化铝的高温热稳定性、降低N2O分解起始反应温度,满足N2O分解较高的低温活性和高温热稳定性要求。本发明催化剂原料易得,工艺简单,具有很好的应用前景。待填
一种以环戊酮为原料合成高密度航空燃料的方法
本发明涉及一种以木质纤维素基平台化合物为原料的,完全不依赖化石能源的高密度、高体积热值的环烃类碳氢燃料合成路线。该方法所获得的液体燃料可以用于各类航空飞行器或作为添加剂提高航空燃料的燃烧性能。本发明方法共分为两部分:1)在酸/碱催化剂的促进作用下,环戊酮(糠醛选择性加氢产物)通过羟醛自缩合反应合成具有多环结构碳数为10和15的不饱和有机化合物;2)采用负载金属A/X型催化剂,对步骤1生成产物在较低温度、无溶剂的条件下进行一步加氢脱氧和加氢反应,获得碳数为10和15的多环烃类燃料。这些液体燃料具有较高密度(C10:0.92g/cm3;C15:1.12g/cm3)能有效提高飞行器携带能量,降低发动机油耗比,满足高航速、大载荷、远射程的要求
一种由生物质衍生物制备航空煤油和柴油的方法
本发明涉及一种基于木质纤维素为原料获得平台化合物的,完全不依赖化石能源的液态链烃燃料新合成路线。该方法所获得的液体燃料可以用作航空煤油和柴油的替代品或作为提高燃料的十六烷值和抗寒能力的添加剂,从而降低国家在液体燃料方面对进口石油的依赖程度。本发明方法共分为两部分:1)在新型固体酸催化剂上含醛基化合物(如甲醛、乙醛、丙醛、丁醛等)与呋喃类平台化合物(如呋喃、甲基呋喃、羟甲基呋喃等)通过酸催化烷基化反应制取碳链长度在8至16之间的含氧有机化合物;2)通过对烷基化产物进行加氢和加氢脱氧,对不饱和键加氢并去除其中的氧,制备碳链长度在8至16之间的生物质航空煤油或高品位柴油