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151.
Dalmo Mandelli Rafael A. Steffen Georgiy B. Shul''pin 《Reaction Kinetics and Catalysis Letters》2006,88(1):165-173
Summary Epoxidation of natural terpene (+)-carvone by the system consisting of a catalyst, oxalic acid (co-catalyst) and H2O2 (70% aqueous solution; oxidant) was studied and factorial design methods were applied for the optimization of this reaction.
A dinuclear manganese(IV) complex [LMn(O)3MnL](PF6)2 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) was used as a catalyst, and acetonitrile was employed as a solvent. An analysis
by methods of the complete 24 factorial design showed that an increase in the catalyst concentration gives a strong positive effect on the carvone conversion
and selectivity. Hydrogen peroxide has a smaller positive effect on the conversion, but at high concentration, H2O2 leads to some decrease in the selectivity. An increase in the oxalic acid concentration has a beneficial effect on the conversion,
but does not affect the selectivity. 相似文献
152.
Gar B. Hoflund Steven D. Gardner David R. Schryer Billy T. Upchurch Erik J. Kielin 《Reaction Kinetics and Catalysis Letters》1996,58(1):19-26
The influence of promoters on Pt/SnOx/SiO2 and Au/MnOx low-temperature CO oxidation catalysts has been investigated under stoichiometric reaction conditions with no CO2 added to the feed gas. The performance of Pt/SnOx/SiO2 catalysts is improved significantly by the addition of 1 wt.% Fe but reduced by the addition of 5 wt.%Fe, 1 wt.% Sb, 5 wt.% Sb, 1 wt.% As, 5 wt.%As and 1.8 wt.% P. The performance of Au/MnOx is improved significantly by the addition of 1 at.% Ce but reduced by the addition of 1 at.% Co. For the catalysts and conditions examined, the Au/MnOx catalysts are superior to the Pt/SnOx/SiO2 catalysts with respect to both activity and decay characteristics. 相似文献
153.
N(1)取代5-氟尿嘧啶乙酸、5-氟尿嘧啶丙酸与Cu(Ⅱ)、Co(Ⅱ)、Ni(Ⅱ)、Zn(Ⅱ)、Mn(Ⅱ)的配合物的合成及表征 总被引:1,自引:0,他引:1
合成了N(1)取代5-氟尿嘧啶乙酸、5-氟尿嘧啶丙酸与铜(Ⅱ)、钴(Ⅱ)、镍(Ⅱ)和锰(Ⅱ)的十种金属配合物。通过元素分析、差热-热重分析确定了它们的化学组成,并对这些化合物进行了红外光谱、氢核磁共振谱,电子光谱的表征。讨论了各配合物中金属离子与配体的配位状态。在Cu(Ⅱ)配合物中,Cu(Ⅱ)是与配体的N3原子和C4上的羰基氧原子配位,其他金属配合物中,金属离子是与配体的C2的羰基氧原子和羧基配位。 相似文献
154.
Katerina Liberkov Raymonde Touroude 《Journal of molecular catalysis. A, Chemical》2002,180(1-2):221-230
Selective hydrogenation of crotonaldehyde was performed on 5% Pt/SnO2 catalysts, in gaseous phase, at atmospheric pressure, at 353 K. Two types of catalyst were prepared using H2PtCl6 and Pt(NH3)4(NO3)2 as metallic precursors. Their performances were compared as a function of the reduction temperature and both catalysts were characterised by X-ray diffraction after different reduction treatments. Using the ex-chloride catalyst, the selectivity values to the unsaturated alcohol (UOL) resulted into a maximum of 45% while a selectivity as high as 70–77%, in 0–25% conversion range, was achieved by using ex-nitrate catalyst reduced at 443 K. The formation of Pt–Sn alloy on the metal particles of platinum was thought to be necessary to improve the activity and the selectivity on these catalysts. In the contrast, a presence of PtSn2 formed at a reduction temperature higher than 473 K led to a decrease of activity and selectivity. 相似文献
155.
A novel histidine-selective method has been developed for the determination of histidine in aqueous solutions by resonance light scattering (RLS) technique. At pH 8.0, the weak RLS intensity of tetraphenylporphyrin manganese (III) chloride [MnTPPCl] was greatly enhanced by the addition of histidine with the maximum peak located at 483 nm. Under the optimum conditions, it was found that the enhanced RLS intensity was in proportion to the concentration of histidine in the range 7.8 × 10−7-2.4 × 10−5 mol l−1. Low detection limit of 9.2 × 10-8 mol l−1 has been achieved. The histidine concentrations in synthetic samples and real samples were determined with satisfactory results. The sensitivity and selectivity of this method are high enough to permit the determination of trace amounts of histidine without any significant interference from high levels of other components such as common anions and especially, other amino acids. 相似文献
156.
157.
LiMnC2O4(Ac) precursor in which Li+ and Mn2+ were amalgamated in one molecule was prepared by solid-state reaction at room-temperature using manganese acetate, lithium hydroxide and oxalic acid as raw materials. By thermo-decomposition of LiMnC2O4(Ac) at various temperatures, a series of Li1+y[Mn2−xLix]16dO4 spinels were prepared with Li2MnO3 as impurities. The structure and phase transition of these spinels were investigated by XRD, TG/DTA, average oxidation state of Mn and cyclic voltammeric techniques. Results revealed that the Li-Mn-O spinels with high Li/Mn ratio were unstable at high temperature, and the phase transition was associated with the transfer of Li+ from octahedral 16c sites to 16d sites. With the sintering temperature increasing from 450 to 850 °C, the phase structure varied from lithiated-spinel Li2Mn2O4 to Li4Mn5O12-like to LiMn2O4-like and finally to rock-salt LiMnO2-like. A way of determining x with average oxidation state of Mn and the content of Li2MnO3 was also demonstrated. 相似文献
158.
Chang Xiu Han Ji Li Ren Xue Jiao Tang Bao Gui Zhang 《中国化学快报》2007,18(10):1285-1288
A new ternary Fe-based alloy catalyst FeCuP applied to decompose PH_3 was prepared with low-cost material by chemical reduction deposition method.The properties of it were characterized by XRD,ICP and SEM.Its catalytic activity on the decomposition of PH_3 and the decomposition conditions were studied.FeCuP alloy exhibits high thermal stabilities and high catalytic activity.Using it as catalyst,the decomposition temperature of phosphine decreases from over 800℃to 400-500℃.The decomposition rate of phosphine achieved 100%. 相似文献
159.
催化增强化学蒸气沉积法在聚酰亚胺上沉积钯-铂合金薄层 总被引:4,自引:0,他引:4
以N2,O2作载气,通过催化增强化学蒸气沉积(CECVD)分别制得在聚酰亚胺上的金属铂、钯及其合金薄层。铂、钯配合物的共同沉积可生成Pt-Pd合金薄膜。在Pd-Pt合金的沉积过程中,Pd/Pt的原子数比率随共同沉积的条件改变而变化。O2为载气、300 ℃条件下,用Pd(η3-allyl)(hfac)和Pt(COD)Me2作前驱体共沉积制备Pd-Pt合金,得到含Pd 37.2%,Pt 62.8%且不 相似文献
160.