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2.
ZrO2在Cu-ZnO-ZrO2甲醇水蒸汽重整制氢催化剂中的作用 总被引:2,自引:0,他引:2
通过对一系列Cu-ZnO-ZrO2甲醇水蒸汽重整(SRM)催化剂的XRD、TEM和BET表征及催化性能测定,研究催化剂中ZrO2对催化剂粒径、比表面以及对SRM反应性能的影响.结果表明,ZrO2的加入,使催化剂的粒径从15 nm降至10 nm(其中CuO和ZnO的平均粒径分别从7.7和10.4 nm降至3.9和8.7 nm),BET比表面从60 m2•g-1增至78 m2•g-1.随着催化剂含ZrO2量不同,甲醇的转化率和H2、CO2的选择性均产生变化,当催化剂中Zr含量为24.0%(w),反应温度为220 ℃,水、醇摩尔比为1.3时,甲醇的转化率达到51.6%, H2和CO2的选择性达到100%(CO和CH4在产物气体中的体积分数小于10-4),这一结果对甲醇燃料电池甲醇重整器的应用具有重要的意义. 相似文献
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Steam-reforming reactions of methanol over NiO/Al2O3 and CuO/ZnO have been investigated. Over the nickel catalyst, the reaction rate is of zero kinetic order with respect to either methanol or steam, and the activation energy is 12.4 kJmol?1, whereas with copper catalyst, the rate is expressed according to the literature as kPa/(1 + KaPa + Kb+Pb) in which “a” and “b” are methanol and steam, respectively. The rate-controlling step of the reaction is assigned to the dissociation of O-H bond with dehydrogenation of C-H bond proceed rapidly to form carbon oxides. With copper catalyst the intrinsic participation of a water molecule during the dehydrogenation of C-H bond leads to the formation of carbon dioxide. With nickel catalyst, the dehydrogenation proceed more rapidly than the migration of a water molecule from an alumina site to a nickel site and causes almost exclusively the formation of carbon monoxide and hydrogen at a lower reaction temperature. 相似文献
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Summary Dynamic headspace and simultaneous steam distillation-extraction techniques were used to isolate volatile components of Parmesan cheese. Identification of the substances was carried out by GC and GC-MS; 110 compounds were identified in the samples obtained using the headspace technique, 105 in the extracts; among them, about 50 compounds were isolated with both procedures. Mass spectral data showed evidence for a number of newly reported compounds such as 3-(methylthio)propanal, -tetradecalactone, 9-tetra-decenoic and 9-hexadecenoic acids. Mass spectra of some compounds are discussed and a comparison between the results obtained with the two sampling methods is given. 相似文献
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系统地研究Nb2TiO7与Nb1.33Ti0.67O4材料相互转变的氧化还原循环可逆性能,同时研究Nb2TiO7和Nb1.33Ti0.67O4样品随温度和氧分压变化的电导率,并与复合电极对称电池和电解池的电化学性能相关联. 在830 oC下,对Nb1.33Ti0.67O4复合电极电解池进行水蒸气的电解研究测试. 电流电压曲线和电解池短期性能测试表明在低电压下主要为电极的还原和活化过程;而在高电压下主要为水蒸气的电解. 当3%H2O/Ar/4%H2气体通入阴极时电解池水蒸气电解的法拉第效率为98.9%;而当通入气体转换为3%H2O/Ar时效率为89%. 相似文献
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冠心苏合丸中挥发性组分的分析及主成分冰片的测定 总被引:1,自引:0,他引:1
采用同时蒸馏-萃取法提取冠心苏合丸中的挥发性组分,测得两种冠心苏合丸中的挥发性组分含量分别为14%和9.8%。利用GC-MS方法对两种冠心苏合丸所得的挥发性组分进行分析,通过检索NIST98谱图库,并结合标准谱图库和有关文献,从冠心苏合丸的挥发性组分中分别确定出14、19种化学成分,分别占挥发性组分总检出量的97.24%和98.76%。用峰面积归一化法,得出各化学成分在挥发性组分中的相对百分含量。主要挥发性组分是冰片。并采用气相色谱法对冠心苏合丸中冰片的含量进行了测定冰片质量浓度在1.0~5、0mg/mL范围内成良好的线性关系,冰片的平均回收率为98%~106%。 相似文献
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Tellez MR Khan IA Schaneberg BT Crockett SL Rimando AM Kobaisy M 《Journal of chromatography. A》2004,1025(1):51-56
A new method involving concurrent solid-phase microextraction combined with continuous hydrodistillation of essential oil was developed. This new methodology allowed for the detection by GC-MS of very small amounts of a diagnostic peak for the authentication of Ephedra sinica, in a short period of time and using only small sample sizes. This diagnostic peak was identified as 4-vinylanisole, and elucidated from the chromatographic profile allowed for the identification of a sample as E. sinica among other species investigated in this study. To the best of our knowledge this is the first report on using continuous solid-phase microextraction coupled to hydrodistillation for the investigation of essential oil components, and the first report of 4-vinylanisole as a marker compound for E. sinica. A total of 46 collections representing 21 species of Ephedra were studied. 相似文献