Effects of cerium and vanadium on the activity and selectivity of MnOx-TiO2 catalyst for low-temperature NH3-SCR

MnOx-TiO2,CeO2-MnOx-TiO2 and V2O5-MnOx-TiO2 catalysts for low-temperature NH3-SCR were prepared by sol-gel method.The results showed that both cerium and vanadium prevented the transformation of anatase TiO2 to the rutile phase.The addition of vanadium oxide induced the segregation of crystalline Mn2O3,which contributed little to low-temperature SCR and ammonia oxidation,from the MnOx-TiO2 solid solutions.However,the selectivity of the V-containing catalyst was almost 100% due to the decreased ammonia consump-tion and enhanced adsorption capacity of ammonia on Br(?)nsted acid sites at relatively high temperatures.The electron-donating effect of ce-rium reduced the Mn4+/Mn3+ ratio to some extent,resulting in a decreased activity for ammonia oxidation.This,in combination with the en-hanced ammonia adsorption capacity by Cen+ as additional Lewis acid sites,endowed the Ce-doped catalyst a higher N2 selectivity than MnOx-TiO2 despite the slightly elevated light-off temperature for NO conversion.     

Electrochemical behavior of Cu in the (NaCl-KCl-CuCl) molten salt

The electrochemical reaction mechanism and electrocrystallization process of Cu on copper electrode in the eutectic NaCl-KCl-CuCl molten salt were investigated by means of cyclic voltammetry, chronopotentiometry and chronoamperometry technique at 710 C. The results show that the electrochemical reaction process of Cu is a quasi-reversible process mix-controlled by Cu + diffusion rate and electron transport rate; the electrochemical reduction mechanism is Cu + +e→Cu; the electrocry stallization process of co...     

A review on energy,economical, and environmental benefits of the use of CHP systems for small commercial buildings for the North American climate

The use of combined heating and power (CHP) systems to produce both electricity and heat is increasing rapidly due to their high potential of reducing primary energy consumption (PEC), cost, and emissions in domestic, commercial, and industrial applications. In addition to producing both electricity and heat, CHP systems can be coupled with vapor compression systems to provide cooling. This paper analyzes a natural gas engine CHP system together with a vapor compression system for different American climate zones. Performance is measured in terms of operational costs, PEC, and carbon dioxide emissions as a percent of a reference building. The objective of this paper is to compare the performance of a CHP system operating 24 h a day with a system that only operates during typical office hours. Furthermore, the system is optimized based on reducing PEC, minimizing costs, and reducing emissions. In addition, the benefits of CHP systems based on the Energy Star program and the Leadership in Energy and Environmental Design (LEED) program are presented. Results show that, in general, it is more beneficial to operate the CHP system during typical office hours than to operate the system 24 h a day. Also, the CHP system performance strongly depends on the location where it is installed. In addition to reductions in cost, primary energy, and emissions, CHP systems can help achieve the Energy Star label for commercial office buildings and help obtain LEED points that go toward achieving LEED certification status. Copyright © 2009 John Wiley & Sons, Ltd.     

The improved electrocatalytic activity of palladium/graphene nanosheets towards ethanol oxidation by tin oxide

Tin oxide (SnO₂)/graphene nanosheets (GNS) composite was prepared by a simple chemical-solution method as the catalyst support for direct ethanol fuel cells. Then the SnO₂-GNS composites supporting Pd (Pd/SnO₂-GNS) catalysts were synthesized by a microwave-assisted reduction process. The Pd/SnO₂-GNS catalysts were characterized by using X-ray diffraction, transmission electron microscopy and energy-dispersive spectroscopy techniques. The electrocatalytic performances of Pd/SnO₂-GNS catalysts for ethanol oxidation were studied by cyclic voltammetric and chronoamperometric measurements. It was found that compared with Pd/GNS, the Pd/SnO₂-GNS catalyst showed superior electrocatalytic activity for ethanol oxidation when the mass ratio of SnCl₂·2H₂O precursor salt to graphite oxide was about 1:2.     

Electrochemical hydrodehalogenation of polychloromethanes at silver and carbon electrodes

The reductive dehalogenation of CCl₄, CHCl₃, CH₂Cl₂ and CH₃Cl has been investigated by cyclic voltammetry and controlled-potential electrolysis at Ag, glassy carbon (GC) and graphite electrodes in dimethylformamide (DMF) + 0.1 M Et₄NClO₄ in the absence and presence of a proton donor. In particular, the study was focused in the evaluation of the intermediates and final products of the reduction process and how their distribution could be affected by tuning relevant chemical and electrochemical parameters. In general, depending on the value of the applied potential, all polychloromethanes (PCMs) can be partially or completely dechlorinated, methane being exclusively formed in the latter case. The nature of the electrode material and the proton availability of the medium affect drastically the distribution of reduction products. The results point out that at both types of electrode, reduction of PCMs takes place through two competing reaction pathways both leading to methane. One reaction route involves a sequence of reductive dehalogenation steps, with the removal of one chlorine atom at a time, whereas the other is based on hydrogenolysis of carbenes and bypasses the intermediacy of partially dechlorinated PCMs. The presence of a proton source affects substantially the hydrodehalogenation efficiency, enhancing the concentration of intermediate PCMs and the final yield of methane. The silver electrode exhibits an extraordinary electrocatalytic effect resulting in remarkable positive shifts of the reduction potentials of all PCMs with respect to GC. The Ag surface strongly affects the kinetics of the dissociative electron transfer to CH_nCl_(4−n) (n = 0–3) as well as the reactivity of the intermediate radicals, carbanions and carbenes.     

树脂原位吸附提高酒明串珠菌不对称合成(R)-2-辛醇的催化效率

通过运用原位吸附技术构建水/树脂反应系统,利用树脂的原位吸附来提高酒明串珠菌Oenococcus oeni CECT 4730不对称合成(R)-2-辛醇的催化效率。通过比较6种不同型号的吸附树脂对反应的影响,选出了最适的树脂AB-8。通过考察树脂的用量及水/树脂相中底物浓度对反应的影响,发现反应体系中加入一定量合适的吸附树脂,能够显著减小底物和产物的抑制,大幅度的提高初始底物浓度和反应产率。AB-8树脂加量为15g/L的水/树脂系统中,底物浓度为30g/L时,反应产率达到58%,较之水相系统提高了1.7倍。     

（3+1）维广义KdV-Zakharov-Kuznetsev方程的对称、约化和精确解

利用直接对称方法得到了广义KdV-Zakharov-Kuznetsev方程（简写为mKdV-ZK）的对称约化、精确解，其中包括椭圆函数解，幂级数解，艾米儿函数解等. 利用得到的对称，求出了该方程的守恒律.     

A novel robotic leg design with hybrid dynamics

A new leg mechanism is designed to achieve optimal behaviour in both the stance and swing phases. The leg is designed such that its dynamics and kinematics optimally mimic those of simpler mechanisms, namely the spring-loaded inverted pendulum (SLIP) and the double pendulum, for the stance and swing phase, respectively. Controllers based on the simpler mechanisms can thus be used, resulting in an effective control strategy that is simple and transparent.     

Nash and integrated solutions in a just-in-time seller–buyer supply chain with buyer's ordering cost reductions

The seller frequently offers the buyer trade credit to settle the purchase amount. From the seller's prospective, granting trade credit increases not only the opportunity cost (i.e., the interest loss on the buyer's purchase amount during the credit period) but also the default risk (i.e., the rate that the buyer will be unable to pay off his/her debt obligations). On the other hand, granting trade credit increases sales volume and revenue. Consequently, trade credit is an important strategy to increase seller's profitability. In this paper, we assume that the seller uses trade credit and number of shipments in a production run as decision variables to maximise his/her profit, while the buyer determines his/her replenishment cycle time and capital investment as decision variables to reduce his/her ordering cost and achieve his/her maximum profit. We then derive non-cooperative Nash solution and cooperative integrated solution in a just-in-time inventory system, in which granting trade credit increases not only the demand but also the opportunity cost and default risk, and the relationship between the capital investment and the ordering cost reduction is logarithmic. Then, we use a software to solve and compare these two distinct solutions. Finally, we use sensitivity analysis to obtain some managerial insights.     

Preparation of Ti5Si3 by silicothermic reduction of titanium-bearing blast furnace slag

In the present study, the silicothermic reduction experiments of titanium-bearing blast furnace slag were carried out in argon atmosphere at different temperatures in order to prepare titanium silicide (Ti₅Si₃). The influences of temperature and reaction time on the reaction process were studied by X-ray diffraction and scanning electron microscope equipped with energy-dispersive spectroscopy. It was found that most of the titanium can be transformed to Ti₅Si₃ within a short time when the reduction temperature was higher than 1773?K. The produced Ti₅Si₃ particles were sintered and formed a porous skeleton structure due to its high melting point, with liquid slags filled in it. Meanwhile, it was found that high temperatures and long reaction time were beneficial for the separation of slag from Ti₅Si₃. This novel method of preparing Ti₅Si₃ may provide a route to recycle titanium-bearing blast furnace slag.