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Reaction Control (reaction + control)
Selected AbstractsAn Approach to Simple Reaction Control for Auto-thermal Fuel-reforming SystemsFUEL CELLS, Issue 4 2004M. Komachiya Abstract A simple approach to reaction control for auto-thermal fuel-reforming systems was proposed and examined. The amount of air supplied to the fuel-reforming system was chosen as the variable in the feedback (closed-loop) control operation, and simply by varying the amount of air supplied, it was attempted to control and stabilize the temperature of the auto-thermal reforming reaction. The amounts of other fuels and water were chosen from pre-determined values by open-loop operation. Since the feedback operation was limited to the air-supply mechanism, it was expected that both the hardware structure of the system and its software configurations could be significantly simplified. The applicability of this simple feedback control operation was confirmed experimentally by using a methanol reformer of the direct-injection type. [source] Reaction Control in Synthetic Organic Photochemistry: Switching between [5+2] and [2+2],Modes of Cycloaddition,ANGEWANDTE CHEMIE, Issue 46 2009Claudio Roscini Gespaltene Persönlichkeit: Die Photocycloaddition von Maleimiden kann ausgezeichnet gesteuert werden: Bei direkter Bestrahlung ist die [5+2]-Variante bevorzugt, in Gegenwart eines Sensibilisators folgt ein vollständiger Wechsel zur [2+2]-Variante (siehe Schema; TBS = tert -Butyldimethylsilyl). [source] An Approach to Simple Reaction Control for Auto-thermal Fuel-reforming SystemsFUEL CELLS, Issue 4 2004M. Komachiya Abstract A simple approach to reaction control for auto-thermal fuel-reforming systems was proposed and examined. The amount of air supplied to the fuel-reforming system was chosen as the variable in the feedback (closed-loop) control operation, and simply by varying the amount of air supplied, it was attempted to control and stabilize the temperature of the auto-thermal reforming reaction. The amounts of other fuels and water were chosen from pre-determined values by open-loop operation. Since the feedback operation was limited to the air-supply mechanism, it was expected that both the hardware structure of the system and its software configurations could be significantly simplified. The applicability of this simple feedback control operation was confirmed experimentally by using a methanol reformer of the direct-injection type. [source] Combustion of chlorinated hydrocarbons in catalyst-coated sintered metal fleece reactors,JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2-3 2003K Everaert Abstract Incinerators emit chlorinated hydrocarbons, such as polychlorinated benzenes (PCBz) and phenols (PCPh), polychlorinated biphenyls (PCB) and polychlorinated dibenzodioxins and furans (PCDD/F), as very dilute streams. High temperatures (>1000,°C) are required in traditional oxidizers. From an energy-saving perspective and to avoid de novo synthesis of PCDD/F, exhaust gas clean-up must be performed at low temperatures (250,350,°C). Catalytic combustion can be applied in this temperature range and different reactor layouts are used (eg monoliths, honeycomb). The present investigation uses a novel catalyst-coated sintered metal fleece. Thin metal fibers are sintered (non-woven) to fleece of various thickness, structure and porosity. V,Ti,W catalysts are examined. The paper will briefly review the catalyst coating method suitable to provide a structured fleece reactor with adequate characteristics. Experiments were carried out in the temperature range of 260,340,°C with various hydrocarbons injected in a carrier air stream. The experimental investigations demonstrated: (i) that the conversion of the hydrocarbons (volatile organic compounds, VOC) is independent of the oxygen concentration, corresponding to a zero-order dependence of the reaction rate; (ii) that the conversion of the hydrocarbons is a first-order reaction in the VOC; (iii) that the oxidation of the VOC proceeds to a greater extent with increasing temperature, with chlorine substitution enhancing the reactivity, and (iv) that the reaction rate constant follows an Arrhenius-dependence with activation energies between 37.3 and 58.4,kJ,mol,1. An assessment of the results leads to a model expression with kinetic reaction control. This model can be used in a scale-up strategy. © 2003 Society of Chemical Industry [source] A theoretical study on the structures and energetics of hypothetical TiM(NCN)3 compounds of the 3d transition metalsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 11 2005Maxence Launay Abstract Quasi-ternary cyanamides and carbodiimides of general formula AB(NCN)3 with A , B have neither been predicted nor synthesized. Thus, hypothetical compounds of that kind containing 3d transition metals were considered (A = Ti, B = Mn, Fe, Co, Ni, Cu) by means of density-functional calculations on 34 structural models, most of which were derived from chemically related phases. After performing structure optimizations based on the local-density approximation, the relative energetic orderings are rationalized in terms of geometrical factors such as molar volumes and polyhedral connections. Total-energy generalized-gradient calculations evidence that the most stable models are enthalpically favored with respect to the elements. Even at ambient temperatures, the ternary phases are predicted as being thermodynamically stable in terms of their Gibbs free formation energies, especially if energetically competing and low-lying binaries (TiC, TiN) can be excluded by a kinetic reaction control. The best models are characterized by low-spin magnetic transition metals found in octahedral coordination, and the TiN6 and MN6 polyhedra either share faces or edges. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1180,1188, 2005 [source] The effect of ligand on the rate of propagation of Cu(0)-wire catalyzed SET-LRP of MA in DMSO at 25 °CJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2009Nga H. Nguyen Abstract The effect of initial ligand concentration on the apparent rate constant of propagation of single-electron transfer living radical polymerization (SET-LRP) of MA in DMSO at 25 °C was examined using various lengths of Cu(0) wire as catalyst. It was determined that unlike other parameters such as initiator concentration, solvent concentration, and deactivator concentration, no simple external rate-order for the ligand concentration could be determined. Rather, the response of the rate of SET-LRP to initial ligand concentration is complex and is likely determined by a competition of ligand-dependent extent of disproportionation as well as the role of ligand concentration in the surface mediated activation process. Results suggest that a minimum concentration of ligand is needed to achieve both acceptable reaction rate and reaction control, and therefore, ligand concentration must be considered in designing experimental conditions for SET-LRP. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5629,5638, 2009 [source] | ||||||||||