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21.
二氧化碳氧化剂在烷烃催化转化反应中的应用研究进展 总被引:1,自引:0,他引:1
本文综述了近年来国内外有关利用二氧化碳作为氧化剂在烷烃催化转化反应中的研究状况。担载型的金属氧化物催化剂具有较好的催化活性。催化剂表面碱性位的存在可稳定活性中心并且有利于CO2的活化,CO2的作用是与烷烃脱氢产物H2和生成的表面积炭反应,从而提高反应活性及催化剂的稳定性。 相似文献
22.
磷酸高铈(Ce3(PO4)4)是一种难溶于水的化合物,本文测定磷酸高铈在常温pH=0.4的Ksp值为1~8×10-34,但在测定过程中发现Ce3(PO4)4的溶解度受温度变化的影响较大,尤其在50℃以上时,Ce3(PO4)4饱和溶液体系中的Ce4 、PO43-和pH值均变化异常。根据测得的Ce4 、PO43-浓度以及pH值,推断出50℃以上时Ce3(PO4)4转化为Ce(HPO4)2,并建立了相应的转化机理,测定出Ce(HPO4)2的Ksp为3~7×10-13。 相似文献
23.
本文在对有机光伏电池载流子产生机理分析的基础上,从有机光伏电池激活层的微观结构对光电转换效率影响的角度,系统介绍了目前该领域的一些重要研究成果,详细分析了影响光电转换效率的主要因素,并提出了一系列改善光伏电池效率的方法,对未来该领域的研究作了展望。 相似文献
24.
A study was carried out on the composition and nature of the stabilizing additive on the activity of nickel-containing composites
based on zirconia in the methane steam conversion. The methane conversions were 91–99% on Ni/ZrO2(Y, Sc, Ce) at 700–800 °C. 相似文献
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The synthesis of mixed alcohols (C1-C5) from syngas has been studied at 6. 0 MPa over modified Co/CuLaZr catalysts. The molybdenum addition enhanced greatly the activity and the selectivity to alcohols. The improvement of hydrogenation capacity of the system via a reversible spillover effect of hydrogen could explain this effect, together with a great capacity of CO insertion, illustrated by the effect of C2H4 addition as a probe to syngas. Under our experimental conditions, a mixed alcohol production of 147.1g/kg. cat/h containing a proportion of 33. 1% of higher alcohols (C2 OH) was obtained with a selectivity to ROH of 52. 8%. 相似文献
28.
Luis C. Mendes Andrea D. Tedesco Mauro S. Miranda Marcia R. Benzi Beatriz S. Chagas 《Polymer Testing》2005,24(8):963-968
In this third work, we evaluated the degree of conversion (DC) versus depth of dental filling composite named Prodigy Condensable™ using infrared spectroscopy. Confirming previous results, there was a gradual reduction of DC with increasing depth but the composite exhibited extreme values of DC, an upper value (45.9%) on the surface and a lower one (6.1%) at a depth of 5 mm. The composite presented the worst performance among materials studied. The composite formulation was 80% of inorganic fillers and BisfenolA/dimethacrylate (BisGMA) (18%)/triethyleneglycoldimethacrylate (TEGDMA) (2.0%) as monomers. As stated before, type/ratio/viscosity of monomers and type, amount, size and size distribution of fillers all together had an important role in the cure reaction contributing to the final performance of the composite. 相似文献
29.
Zouhair Boukha Mohamed Kacimi Mahfoud Ziyad Alain Ensuque Franois Bozon-Verduraz 《Journal of molecular catalysis. A, Chemical》2007,270(1-2):205-213
Palladium loaded calcium-hydroxyapatite, Pd(z)/CaHAp, and calcium-fluoroapatite, Pd(z)/CaFAp, were synthesised and characterised by TEM, XRD, IR and UV–vis–NIR spectroscopies. Introduction of palladium does not change the structure of CaHAp and CaFAp. The average size of PdO particles was found to be around 4–5 nm on Pd(1)/CaHAp but larger (6–7 nm) on Pd(1)/CaFap. The acid–base properties of the supports and of the catalysts were studied using butan-2-ol conversion. On CaHAp and CaFAp, the butenes yield (dehydration reaction) is very low either in the absence or in the presence of oxygen. The methyl ethyl ketone yield (dehydrogenation reaction) is significant only in the presence of oxygen and higher over CaFAp. Conversely, the performances of Pd(z)/CaHAp are better than those of Pd(z)/CaFAp below 180 °C. Above 180 °C, buta-2-ol combustion is favoured on Pd/CaHAp but not on Pd/CaFAp.
In methane oxidation, Pd(z)/CaHAp showed also a much larger activity than Pd(z)/CaFAp. On 2 wt% Pd loaded CaHAp, the methane oxidation reaches a conversion of almost 100% at 350 °C, which is comparable with the performance of conventional Pd/Al2O3 catalysts. The reducibility of PdO under methane–oxygen mixtures is lower on Pd(z)/CaHAp. For both reactions, the lower activity of Pd(z)/CaFAp is related to its higher acidity, resulting from the substitution of OH− by F−, and to the larger PdO particle size. 相似文献
30.
JiangBinXIA FuYouLI ShuMingYANG ChunHuiHUANG 《中国化学快报》2004,15(5):619-622
Composite nanoporous electrode SnO2/TiO2 was fabricated for the dye sensitized solar cell (DSSC) with N3 (Cis-Ru). After introducing of TiO2, the open-circuit photovoltage (Voc) was higher than that of the pure SnO2 electrode, while short-circuit photocurrent (Isc) was varied with the ratio of the TiO2. Appropriate content of the TiO2 can be beneficial to the efficiency of the solar cell, and it gives negative impact on the composite electrode when the content of TiO2 is higher. 相似文献