New ideas and solutions are necessary to face challenges in the electricity industry. The application of electricity storage systems (ESS) can improve the quality and stability of the existing electricity network. ESS can be used for peak shaving, instead of installing new generation or transmission units, renewable energy time-shift and many other services. There are few ESS technologies existing today: mechanical, electrical and electrochemical storage systems. Flow batteries are electrochemical storage systems which use electrolyte that is stored in a tank separated from the battery cell. Electrochemistry is very important to understand how a flow battery functions and how it stores electric energy. The functioning of a flow battery is based on reduction and oxidation reactions in the cell. To estimate the voltage of a cell the Nernst equation is used. It tells how the half-cell potential changes depending on the change of concentration of a substance involved in an oxidation or reduction reaction. The first flow battery was invented in the 1880’s, but was forgotten for a long time. Further development was revived in the 1950’s and 1970’s. A flow battery consists of two parallel electrodes separated by an ion exchange membrane, forming two half-cells. The electro-active materials are stored externally in an electrolyte and are introduced into the device only during operation. The vanadium redox battery (VRB) is based on the four possible oxidation states of vanadium and has a standard potential of 1.23 V. Full ionic equations of the VRB include protons, sulfuric acid and the corresponding salts. The capital cost of a VRB is approximately 426 $/kW and 100 $/kWh. Other flow batteries are polysulfide-bromine, zinc bromine, vanadium-bromine, iron-chromium, zinc-cerium, uranium, neptunium and soluble lead-acid redox flow batteries. Flow batteries have long cycle life and quick response times, but are complicated in comparison with other batteries. / Nya idéer och lösningar är nödvändiga för att möta utmaningarna i elbranschen. Användningen av elektriskt lagringssystem (ESS) kan förbättra kvalitén och stabiliteten av det nuvarande elnätet. ESS kan användas till toppbelastningsutjämning, istället för att installera nya produktions eller kraft överförnings enheter, förnybar energi tidsförskjutning och många andra tjänster. I dagsläget finns det få olika ESS: Mekaniska, elektriska och elektrokemiska lagringssystem. Flödesbatterier tillhör kategorin elektrokemiska lagringssystem som använder sig utav elektrolyt som är lagrad i en tank separerad från battericellen. För att kunna förstå hur flödesbatteriernas funktioner och på vilket sätt som dem lagrar elektriskt energi är det viktigt att kunna elektrokemi. Flödesbatteriernas funktion är baserad på reduktions och oxidations reaktioner i cellen. Nernsts ekvation används för att kunna uppskatta voltantalet i en cell. Nernsts ekvation säger hur halvcell potentialen ändras beroende av ändringen av koncentrationen av ämnet involverat i oxidations eller reduktions reaktionen. Det första flödesbatteriet uppfanns 1880-talet, men blev bortglömt under en lång tid. Vidare utveckling förnyades under 1950 och 1970-talet. Ett flödesbatteri består utav två parallella elektroder som är separerade utav ett jonbytes membran vilket formar två halvceller. Dem elektroaktiva materialen är lagrade externt i elektrolyt och är införs bara i anordningen under användning. Vanadium redox batteriet (VRB) är baserat på dem fyra möjliga oxidations tillstånden av vanadium och har en standard potential på 1.23 V. Fullt joniska ekvationer av VRB inkluderar protoner, svavelsyra och deras motsvarande salter. Kapitalkostnaden av ett VRB är ungefär 426 $/kW och 100 $/kWh. Det finna andra flödesbatterier som är polysulfide-brom, zink-brom, vanadium-brom, järn-krom, uran, neptunium och löslig blysyre redox flödesbatterier. Flödesbatterier har en lång omloppstid samt en snabb svarstid men är komplicerade jämfört med andra batterier.

In this work, the steady-state performance of zeolite-based Cu-ZSM-5, vanadium based honeycomb monolith catalysts (V), vanadium-titanium based pillared inter layered clay catalyst (V-Ti PLIC) and vanadium-titanium-tungsten-based honeycomb monolith catalysts (V-Ti-W) was investigated in the selective catalytic reduction process (SCR) for NO removal using NH3 in presence of oxygen. The objective is to obtain the expression that would predict the conversion performance of the catalysts for different values of the SCR process parameters, namely temperature, inlet oxygen concentration and inlet ammonia concentration. The NOx emission, its formation and control methods are discussed briefly and then the fundamentals of the SCR process are described. Heat transfer based and chemical kinetics based SCR process models are discussed and widely used rate order based model are reviewed. Based on the experimental data, regression analysis was performed that gives an expression for predicting the SCR rate for the complete temperature range and the rate order with respect to inlet oxygen and ammonia concentration. The average activation energy for the SCR process was calculated and optimum operating conditions were determined for each of the catalyst. The applicable operating range for the catalyst depends on the NO conversion as well as on the ammonia slip and the N2O and NO2 emission. The regression analysis was repeated for the applicable range and an expression was obtained that can be used to estimate the catalyst performance. For the Cu-ZSM-5, the best performance was observed for 400oC, 660 ppm inlet ammonia concentration and 0.1% inlet oxygen concentration. For the V based honeycomb monolith catalyst, the best performance was observed for 300oC, 264 ppm inlet ammonia concentration and 3% inlet oxygen concentration. For the V-Ti based PLIC catalyst, the best performance was observed for 350oC, 330 ppm inlet ammonia concentration and 3% inlet oxygen concentration. For the V-Ti-W based honeycomb monolith catalyst, the best performance was observed for 300oC, 330 ppm inlet ammonia concentration and 3% inlet oxygen concentration. The conversion performance of all of these catalysts is satisfactory for the industrial application. At the operating conditions listed above, the N2O emission is less than 20 ppm and the NO2 emission is less than 10 ppm. The results were validated by comparing the findings with the similar work by other research groups. The mechanism of SCR process is discussed for each of the catalyst. The probable reactions are listed and adsorption and desorption process are studied. The various mechanisms proposed by the researchers are discussed briefly. It is concluded that V-Ti-W and Cu-ZSM-5 catalyst are very promising for SCR of NOx. The expressions can be used to estimate the conversion performance and can be utilized for optimal design and operation. The expressions relate the SCR rate to the input parameters such as temperature and inlet oxygen and ammonia concentration hence by controlling these parameters desired NOx reduction can be achieved with minimal cost and emission.

Reproduction de : Thèse de doctorat : Chimie physique : Lyon 1 : 2005. / Titre provenant de l'écran titre. 200 réf. bibliogr.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 110-113). Also available on the Internet.

Thesis (Ph. D.)--Columbia University, 1933. / Vita. Bibliography: p. 38-39.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 110-113). Also available on the Internet.

This dissertation addresses atomic-level structure and related properties of the (100) surfaces of Vanadium and Niobium. The primary motivation of the surface structure experiments is based on an observation by P.J. Feibelman [[superscript 3,4]] that ab-initio calculations of surface relaxation (interplanar separation of near-surface planes) exhibit significant and consistent deviation from corresponding experimental relaxation values obtained through LEED crystallography. The deviation is much larger than the accepted accuracy of both the theoretical and experimental techniques. Resolving this dilemma is the primary objective for this systematic investigation of multilayer relaxation at transition metal surfaces. This research also addresses important secondary issues. Closely related to the surface relaxation issue for Nb(100) are experiments that provide an experimentallydetermined structural basis for the "sub-surface valve" model that has been proposed to explain the novel hydrogen uptake kinetics in Niobium. Definitive experiments that address the longstanding search for ferromagnetic order at the surface of V(100) is another important issue.

Vanadium and molybdenum oxide catalysts have been prepared on different Ti02 supports by a variety of methods. Solutions of VOC13, VO(O'Bu)3 and MoOC14 were used to graft VOX and MoOX monolayers onto the supports in a single treatment. The other methods were intended to produce more than one monolayer (i. e. aqueous impregnation and multiple treatments of VOC13 and VO(O1Bu)3 ). TPR and Raman spectroscopy showed the formation above the monolayer of a phase denoted as disordered vanadium oxide, which has the same reducibility as the monolayer species but which has a band in the Raman spectrum at 995 cm-l. Raman spectroscopy also showed the formation of a disordered molybdenum oxide phase. With supports which contained phosphorus and potassium as impurities, TPR and Raman spectoscopy indicated a potassium-containing vanadium oxide, which was difficult to reduce and which showed no band at 995 cm-1. "Paracrystalline" V205 and MoO3 are formed when the oxide content exceeds four monolayers. XPS measurements confirm the dispersion of MOX species (M = V, Mo) on the surface of the support in the monolayer region; they also show that disordered and paracrystalline oxide phases occupy a limited area of the monolayer surface, but could not distinguish between them. ESR results showed 95% of the supported vanadium in the oxidation state +5. Phosphorus and potassium impurities in (or on) the TiO2 support influence the structure and catalytic properties of the VOX monolayer phase. In the case of catalysts made on supports with low impurities, activities in butadiene oxidation and isopropanol decomposition are principally due to the monolayer species and little contribution is made by the disordered or paracrystalli ne V205, while in the catalysts made on the supports with relatively high level of impurities, the activities in both reactions increase with V205 content in the region of one to four monolayers. MoOX catalysts showed low activities and selectivities in butadiene oxidation.

M. Tech. Chemical Engineering. / Evaluates the use of modified eccalite as an adsorbent for the efficient removal of vanadium from industrial wastewater. The specific objectives of the study are: i. To determine whether modification of eccalite with a surfactant such as (hexadecyltrimethylammonium bromide HDTMA-Br, CTAB) will gives an optimal performance in vanadium removal from industrial wastewater; ii. To conduct batch adsorption experiments for modified eccalite for the determination of equilibrium adsorption capacity, kinetics, and thermodynamic parameters; iii. To perform column/dynamic adsorption experiments for modified eccalite in order to determine the dynamic adsorption capacity and breakthrough profiles. iv. Fit the experimental data to existing mathematical model describing the sorption process of vanadium removal from wastewater.

The hyperfine structure of the ground state of vanadium, is calculated in the nonrelativistic framework of the multi-configiuration Hartree-Fock approximation. A configuration state function limiting algorithm is used to make the calculations feasible and to study the influence of core, valence and core-valence correlations in detail.