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1.
采用水热法合成了负载K的纳米片状水滑石衍生CoAlO金属氧化物,其表现出优异的催化碳烟燃烧活性.氢气-程序升温还原(H2-TPR)实验结果表明,K与Co之间的相互作用提高了催化剂的氧化还原性能.X射线光电子能谱(XPS)分析结果表明,K的负载增大了表面Co2+/Co3+的比例,促进了氧空位的产生,提高了催化剂对气相氧的吸附能力.碳烟-程序升温还原(Soot-TPR)实验结果表明,K的负载增加了表面吸附氧数量.动力学实验结果表明,K的负载增加了单位质量催化剂上的活性氧数量、反应速率和转化频率(TOF),从而提高了催化剂的本征活性.另外,碳烟颗粒可以分散在纳米片的层间,与活性位点的接触效率得到提高,也有利于提高催化碳烟燃烧活性.  相似文献   
2.
《中国化学快报》2020,31(9):2483-2486
Structural and functional biomimicking of the active site of [NiFe]-hydrogenases can provide helpful hints for designing bioinspired catalysts to replace the expensive noble metal catalysts for H2 generation and uptake. Treatment of dianion [Ni(phma)]2− [H4phma = N,N'-1,2-phenylenebis(2-mercaptoacetamide)] with [NiCl2(dppp)] (dppp = bis(diphenylphosphino)propane) yielded a dinickel product [Ni(phma)(μ-S,S')Ni(dppp)] (1) as the model complex relevant to the active site of [NiFe]-H2ases. The structure of complex 1 has been characterized by single-crystal X-ray analysis. From cyclic voltammetry and controlled potential electrolysis studies, complex 1 was found to be a moderate electrocatalyst for the H2-evoluting reaction using ClCH2COOH as the proton source.  相似文献   
3.
A highly efficient catalytic system composed of a bifunctional polyacrylonitrile fiber (PANF‐PA[BnBr]) and a metal chloride was employed to produce 5‐hydroxymethylfurfural (HMF) from sucrose in mixed‐aqueous systems. The promoter of PANF‐PA[BnBr] incorporates protonic acid groups that promote the hydrolysis of the glycosidic bond to convert sucrose into glucose and fructose, and then catalyzes fructose dehydration to HMF, while the ammonium moiety may promote synergetically with the metal chloride the isomerization of glucose to fructose and transfer HMF from the aqueous to the organic phase. The detailed characterization by elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber promoter during the modification and utilization processes. Excellent results in terms of high yield (72.8 %) of HMF, superior recyclability (6 cycles) of the process, and effective scale‐up and simple separation procedures of the catalytic system were obtained. Moreover, the prominent features (high strength, good flexibility, etc.) of the fibers are very attractive for fix‐bed reactor.  相似文献   
4.
《Mendeleev Communications》2020,30(3):273-275
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5.
本文较为系统地研究了铜粉催化剂加入方式对C.I.颜料红177中间体4,4'-二氨基-1,1'-二蒽醌-3,3'-二磺酸(DAS)合成过程中的乌尔曼偶联反应速率的影响规律。 研究结果表明,在55 ℃较佳反应温度下,先加入与溴氨酸钠质量比为2:5的铜粉,反应一段时间后再加入与溴氨酸钠的质量比为1:5的铜粉,与一次性加入与溴氨酸钠的质量比为3:5的铜粉相比较,综合反应时间可节省2~3 h。 另外,对于DAS中混有的铜盐,采取在制备过程中加入柠檬酸的方法予以去除,此举可提高DAS的纯度。 当铜粉与柠檬酸的质量比为6:1时,可使DAS中铜盐的含量小于0.001%。 此外还探究了蒸馏后滤液的剩余量对DAS收率的影响,结果表明,滤液的剩余量在20 mL时,DAS的收率在95%以上。 基于本文的研究结果提出,欲进一步提高该反应的收率,需要寻找更高效的催化剂。  相似文献   
6.
A series of non-platinic lean NOx trap (LNT) CuO-K2CO3/TiO2 catalysts with different Cu loadings were prepared by sequential impregnation, and they showed relatively good performance for lean NOx storage and reduction. The catalyst containing 8% (w) CuO showed not only the largest NOx storage capacity of 1.559 mmol·g-1 under lean conditions, but also the highest NOx reduction percentage of 99% in cyclic lean/rich atmospheres. Additionally, zero selectivity of NOx to N2O was achieved over this catalyst during NOx reduction. Multiple techniques, including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), temperature-programmed desorption of CO2 (CO2-TPD), extended X-ray absorption fine structure (EXAFS), temperature-programmed reduction of H2 (H2-TPR), and in-situ diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS), were used for catalyst characterization. The results indicate that highly dispersed CuO is the main active phase for oxidation of NO to NO2 and reduction of NOx to N2. The strong interaction between K2CO3 and CuO was clearly revealed, which favors NOx adsorption and storage. The appearance of negative bands at around 1436 and 1563 cm-1, corresponding to CO2 asymmetric stretching in bicarbonates and -C=O stretching in bidentate carbonates, showed the involvement of carbonates in NOx storage. After using the catalysts for 15 cycles of NOx storage and reduction in alternative lean/rich atmospheres, the CuO species in the catalysts showed little change, indicating high catalytic stability. Based on the results of in-situ DRIFTS and the other characterizations, a model describing the NOx storage processes and the distribution of CuO and K2CO3 species is proposed.  相似文献   
7.
SiO2-supported Ni-Mo bimetallic phosphides were prepared by temperature-programmed reduction(TPR) method from the phosphate precursors calcined at different temperatures. Their properties were characterized by means of ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis DRS), H2temperature-programmed reduction(H2-TPR), X-ray diffraction(XRD), transmission electron microscopy(TEM), CO chemisorption, H2 and NH3temperature-programmed desorptions(H2-TPD and NH3-TPD). Their catalytic performances for the deoxygenation of methyl laurate were tested in a fixed-bed reactor. When the precursors were calcined at 400 and 500?C, respectively, Ni Mo P2 phase could be formed apart from Ni2 P and Mo P phases in the prepared C400 and C500 catalysts. However, when the precursors were calcined at600, 700 and 800°C, respectively, only Ni2 P and Mo P phases could be detected in the prepared C600, C700 and C800 catalysts. Also, in C400, C500 and C600 catalysts, Mo atoms were found to be entered in the lattice of Ni2 P phase, but the entering extent became less with the increase of calcination temperature. As the calcination temperature of the precursor increased, the interaction between Ni and Mo in the prepared catalysts decreased, and the phosphide crystallite size tended to increase, subsequently leading to the decrease in the surface metal site density and the acid amount. C600 catalyst showed the highest activity among the tested ones for the deoxygenation of methyl laurate. As the calcination temperature of the precursor increased, the selectivity to C12 hydrocarbons decreased while the selectivity to C11 hydrocarbons tended to increase. This can be mainly attributed to the decreased Ni-Mo interaction and the increased phosphide particle size. In sum, the structure and performance of Ni-Mo bimetallic phosphide catalyst can be tuned by the calcination temperature of precursor.  相似文献   
8.
An unprecedented α‐allylation of amines was achieved by combining palladium catalysis and visible‐light photoredox catalysis. In this dual catalysis process, the catalytic generation of allyl radical from the corresponding π‐allylpalladium intermediate was achieved without additional metal reducing reagents (redox‐neutral). Various allylation products of amines were obtained in high yields through radical cross‐coupling under mild reaction conditions. Moreover, the transformation was applied to the formal synthesis of 8‐oxoprotoberberine derivatives which show potential anticancer properties.  相似文献   
9.
We report the complete ethanolysis of Kraft lignin over an α‐MoC1?x/AC catalyst in pure ethanol at 280 °C to give high‐value chemicals of low molecular weight with a maximum overall yield of the 25 most abundant liquid products (LP25) of 1.64 g per gram of lignin. The LP25 products consisted of C6–C10 esters, alcohols, arenes, phenols, and benzyl alcohols with an overall heating value of 36.5 MJ kg?1. C6 alcohols and C8 esters predominated and accounted for 82 wt % of the LP25 products. No oligomers or char were formed in the process. With our catalyst, ethanol is the only effective solvent for the reaction. Supercritical ethanol on its own degrades Kraft lignin into a mixture of small molecules and molecular fragments of intermediate size with molecular weights in the range 700–1400, differing in steps of 58 units, which is the weight of the branched‐chain linkage C3H6O in lignin. Hydrogen was found to have a negative effect on the formation of the low‐molecular‐weight products.  相似文献   
10.
The effects of Bi on the catalytic performance of selective oxidation of isobutane to methacrolein over MoVO/AlPO4 catalyst were investigated by XRD, FT-Raman, XPS, UV-vis DRS techniques. The results show that the addition of Bi component into the MoVO/AlPO4 catalyst obviously improves the catalytic performance, and the selectivity to methacrolein can increase from 14.2% to 45.1% with the increase of Bi/V molar ratio from 0 to 1. Combining the characterization results with the reaction evaluation, it is concluded that the catalytic activities of the MoV0.3Bix/AlPO4 catalysts are related to the crystalline phase composition and the dispersion of molybdenum and vanadium oxides species in general, and also to the V5+/V4+ molar ratio on the surface in particular.  相似文献   
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