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排序方式: 共有1521条查询结果,搜索用时 15 毫秒
1.
应用静态吸附、动态吸附、程序升温脱附和程序升温还原等实验方法,考察了噻吩在Ni基非晶态合金上的吸附和脱附行为。常温下,噻吩分子首先吸附在清洁的Ni表面,并立刻被活化,发生氢解反应,C-S键断裂,释放出烃类部分,S留在Ni原子上。噻吩可以在Ni基非晶态合金表面发生强度不同的化学吸附。弱化学吸附的噻吩可以脱附;强化学吸附的噻吩不会脱附,而在高温下发生氢解反应。 相似文献
2.
过渡金属对Au-Pd/TiO_2-Al_2O_3催化剂加氢脱硫性能的影响 总被引:2,自引:1,他引:1
研究了掺杂过渡金属Ru,Ni,Co对Au-Pd/TiO2-Al2O3催化剂催化噻吩加氢脱硫活性的影响,并采用X射线衍射、电感耦合等离子发射光谱、程序升温还原和程序升温脱附等方法对TiO2-Al2O3复合载体、Au-Pd/TiO2-Al2O3和Au-Pd-TM/TiO2-Al2O3(TM表示过渡金属)催化剂进行了表征。实验结果表明,掺杂过渡金属未改变Au-Pd/TiO2-Al2O3催化剂的结构;掺杂Ru或Ni增强了Au-Pd/TiO2-Al2O3催化剂的活性组分与TiO2-Al2O3复合载体的相互作用,降低了反应活化能,提高了催化剂活性组分的分散度和活性比表面积,改善了Au-Pd/TiO2-Al2O催化剂的吸附性能,从而提高了Au-Pd/TiO2-Al2O3催化剂催化噻吩加氢脱硫的活性;而掺杂Co的效果则与之相反。 相似文献
3.
Shishan Xue Guanfei Liu Jingjuan Lai Peng An Yang Liu Yuanpeng Wu Yu Wang Zhiyong Ye Qiao Tang Hongwei Zhou 《大分子材料与工程》2021,306(11):2100415
Self-healing hydrogels often possess poor mechanical properties which largely limits their applications in many fields. In this work, boron nitride nanosheets are introduced into a network of the poly(vinyl alcohol)/borax (PVA/borax) hydrogels to enhance the mechanical properties of the hydrogel without compromising the self-healing abilities. The obtained hydrogels exhibit excellent mechanical properties with a tensile strength of 0.410 ± 0.007 MPa, an elongation at break of 1712%, a Young's Modulus of 0.860 ± 0.023 MPa, and a toughness of 3.860 ± 0.075 MJ m−3. In addition, the self-healing efficiency of the hydrogels is higher than 90% within 10 min at room temperature. Benefiting from the excellent self-healing properties, the shapeability of the hydrogel fragments is observed using different molds. In addition, the hydrogels display rapid pH-driven shape memory effects and can recover to their original shape within 260 s. Overall, this work provides a new approach to hydrogels with integrated excellent mechanical properties, self-healing abilities, and rapid pH-driven shape memory effects. 相似文献
4.
Solvent assisted spreading of CoO over monolayer MoO3/Al2O3 catalysts has been studied. CoCO3 · Co(OH)2 and CoCO3 reacted with MoO3/Al2O3 in water slurries. CoO deposition over MoO3/Al2O3 extrudates was followed by EPMA. In the set of eleven MoO3/Al2O3 catalysts, the amount of CoO adsorbed was roughly proportional to the surface area of MoO3 monolayer. The adsorbed Co species efficiently enhanced the HDS activity. 相似文献
5.
The isotopic exchange has been studied between catalyst radiosulfur and H2S, formed in thiophene hydrodesulfurization (HDS) (named S-displace) on alumina supported molybdena, on CoMoOx, PdMoOx, PtMoOx and on silica–alumina supported NiWOx. S-displace was compared with radiosulfur exchange data between catalyst radiosulfur and gas phase H2S (Sexc) determined previously. The extent of Sexc was higher than that of the S-displace for Mo, CoMo in and NiW, whereas the extent of S-displace from PdMoO and PtMoO was
significantly higher, than that of Sexc. Thiophene HDS product distribution data are discussed in terms of increased C=C hydrogenation and C–C hydrogenolysis activity,
explained by increasing H2S production with longer circulation time of the thiophene/H2 mixture, The C1/C3<1 ratios among C4-hydrogenolysis products indicate some coke formation. The decrease of thiophene HDS activity is presumably a consequence
of increasing site-blocking with the formation of more H2S and coke with longer duration of thiophene treatment. 相似文献
6.
Shielding coatings based on graphite nanosheets were prepared by compounding method. The surface morphology of the graphite nanosheets and conductive coatings was examined by scanning electron microscopy. The surface resistivity of the coatings was greatly declined by incorporating the graphite nanosheets. The electromagnetic interference shielding effectiveness (SE) from 0.3 MHz to 1.5 GHz was also studied, and found that the SE of the coatings was consistent with its conductivity. The best sample was shown to exhibit up to 38 dB of SE at 1.5 GHz (with a thickness of 400 μm). The main shielding mechanism of the system was reflection and multiple reflections. 相似文献
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9.
Bahaa M. Kamel M. El-Sherbiny K. A. Abed M. Abd-Rabou 《Fullerenes, Nanotubes and Carbon Nanostructures》2017,25(7):429-434
The effect of graphene nanosheets (GNS) on the rheological characteristics and thermal conductivity of calcium grease used in marine applications, and water pumps for lower demanding applications, has been experimentally evaluated in this paper. Various volume fractions of GNS (0.5, 1, 2, 3, and 4% wt.) have been immersed in the grease aiming at finding the better percentages that improve the properties of nanogrease. The rheological characteristics and thermal conductivity were evaluated with a Brookfield Rheometer DV-III ULTRA and KD2 thermal analyzer, respectively. The results of the modified calcium grease indicated that the best concentration of GNS is 3% wt. The rheological characteristics of the grease with a different volume fraction of GNS indicated a non-Newtonian behavior. Thermal conductivity of nanogreas also increases with an increase of GNS volume fraction. Moreover, the apparent viscosity, shear stress and dropping point increase by 59%, 52%, and 65%, respectively, with increasing GNS volume fraction. 相似文献
10.
Zhonghai Song Ning Cao Xuejiao Gao Qiu Liang 《Fullerenes, Nanotubes and Carbon Nanostructures》2017,25(2):65-70
Ultrathin Co3O4 nanosheets grown on the reduced graphene oxide (Co3O4/rGO) was synthesized by a simple hydrothermal method and was investigated as a cathode in a Li-O2 battery. Benefited from the synergistic effect between Co3O4 and rGO, the hybrid exhibits a high initial capacity of 10,528 mAh g?1 along with a high coulombic efficiency (84.4%) at 100 mA g?1. In addition, the batteries show an enhanced cycling stability and after 113 cycles, the cut-off discharge voltage remains above 2.5 V. The outstanding performance is intimately related to the high surface area of rGO, which not only provide carbon skeleton for the uniform distribution of Co3O4 nanosheets but also facilitate the reversible formation and decomposition of insoluble Li2O2. The results of electrochemical tests confirm that the Co3O4/rGO hybrid is a promising candidate for the Li-O2 batteries. 相似文献