Academic literature on the topic 'Selective catalytic converter'
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Journal articles on the topic "Selective catalytic converter"
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Skřivánek, Antonín, Pavel Sedlák, Adam Polcar, and Petr Dostál. "Monitoring of Basic Parameters for Selective Catalytic Reduction System Used in an Agricultural Tractor." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 62, no. 1 (2014): 225–30. http://dx.doi.org/10.11118/actaun201462010225.
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Presented paper describes monitoring of basic parameters for selective catalytic reduction (SCR) system used in an agricultural tractor. SCR systems are used to reduce emissions of nitrogen oxides (NOx) produced by combustion of fuel. The usage of SCR catalytic converters entails certain disadvantages in the use of reducing agent and the necessity of suitable operating conditions to achieve optimum efficiency of the catalytic converter. This paper aims to predict consumption of AdBlue depending on the temperature of SCR catalytic converter, which reflects the engine load and monitoring the effectiveness of SCR catalytic converter when operating a tractor engine with a maximum dose of fuel. To fulfill those aims, the measurements have been performed on the Case Puma 185 CVX agricultural tractor. As the measurement results indicate, the lowest NOx emissions correspond to high consumption of AdBlue. Other studies imply that the catalytic converter operates at optimal operating temperature and with the highest efficiency of NOx emission reduction. The effectiveness of NOx emission reduction is thus affected not only by quantity of injected reagent but also by catalytic converter thermal load. Further measurement results indicate that the lowest amount of emissions of NOx (and the highest efficiency rate) is achieved by catalytic converter in a range in which the engine operates with the highest engine efficiency.
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Xu, Hang, Fang Yin Tu, Zhi Xia He, Jun Ma, and Qian Wang. "Modelling of the Selective Catalytic NOx Reduction for Diesel Engine." Applied Mechanics and Materials 71-78 (July 2011): 2098–102. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.2098.
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As Future emission limits of diesel engines is more stringent, model-based control strategy of selective catalytic reduction (SCR) is becoming necessary. Therefore, a catalytic converter mathematical model for simulating selective catalytic deNOx reaction is very important. In this paper, a one dimension catalytic converter mathematical model that consists of thermal energy model, SCR reaction model and NH3storage model for simulating urea-SCR reaction process is presented. Based on this model, the impact of temperature and gas hourly space velocity (GHSV) on NOx conversion efficiency has been researched. According to the results of simulation, it shows good agreement with experimental data.
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Setiawan, Fendi Handika, Sumarli Sumarli, and Paryono Paryono. "PENGARUH UREA (NH2)2CO SEBAGAI DIESEL EXHAUST FLUID PADA SELECTIVE CATALYTIC REDUCTION BERBAHAN ZEOLITE TERHADAP DAYA DAN EMISI GAS BUANG MESIN DIESEL." Jurnal Teknik Otomotif : Kajian Keilmuan dan Pengajaran 6, no. 1 (April 1, 2022): 29. http://dx.doi.org/10.17977/um074v6i12022p29-34.
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Hasil penelitian akan digunakan untuk pengayaan keilmuan teknik otomotif terapan dan untuk keperluan praktisi teknik otomotif. Untuk meneliti masalah tersebut, telah dilakukan pengujian daya mesin diesel Toyota Kijang LGX 2500cc menggunakan dayno test di bengkel Roda Jaya Speed Malang dan pengujian emisi gas buang yang diteliti yaitu kadar kepekatan gas buang/opasitas mesin diesel Toyota Kijang LGX 2000 cc menggunakan smoke tester di bengkel Otomotif Universitas Negeri Malang. Dengan menggunakan variasi tipe Catalytic ( Catalytic converter, Catalytic SCR dengan DEF 20%,32.5%,40% ,dan tidak menggunakan catalytic) kemudian di uji pengaruhnya terhadap daya dan kadar kepekatan gas buang/opasitas pada putaran mesin 1000, 1250, 1500, 1750, 2000, 2250, 2500, 2750, 3000 RPM, didapatkan hasil bahwa: 1) Ada perbedaan daya yang signifikan antara penggunaan catalytic converter dengan catalytic SCR dengan DEF 20%,32.5%,40% mesin diesel Toyota Kijang LGX 2500cc, 2) Ada perbedaan daya yang signifikan antara penggunaan catalytic converter dengan yang tidak menggunakan catalytic mesin diesel Toyota Kijang LGX 2500cc, 3) Ada perbedaan kadar kepekatan gas buang/opasitas yang signifikan antara penggunaan catalytic converter dengan catalytic SCR dengan DEF 20%,32.5%,40% mesin diesel Toyota Kijang LGX 2500cc, 4) Ada perbedaan kadar kepekatan gas buang/opasitas yang signifikan antara penggunaan catalytic converter dengan catalytic SCR dengan DEF 20%,32.5%,40% mesin diesel Toyota Kijang LGX 2500cc. Berdasarkan hasil penelitian di atas, beberapa saran yang diberikan oleh peneliti antara lain: 1) bagi akademisi universitas negeri malang sebagai referensi dan masukan yang konkret ilmiah, sehingga dapat digunakan untuk prngayaan ilmu teknik otomotif dan pengembangan penelitian yang relevan selanjutnya; 2) bagi praktisi industri, membuat kendaran lebih GO green.
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Wang, Qian, Xiao Jing Han, Ping Qi, and Jing Wang. "Simulation of Urea-SCR Catalytic Converter for Diesel Engine." Advanced Materials Research 354-355 (October 2011): 513–17. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.513.
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A three-dimensional model of a diesel Urea-SCR（Selective Catalytic Reduction）catalytic converter system was set up with aid of CFD software AVL FIRE coupled with available knowledge of SCR chemical reaction kinetics. Basing on the validation of the spray injection model of Urea-water-solution, the numerical simulation was made to get the distribution of pressure, velocity, temperature and species concentration in the converter and NOxconversion in different conditions by considering the injection and evaporation of the urea-water-solution, the thermal decomposition and hydrolysis into ammonia and the surface catalytic reactions in the monolith. The simulated results have some reference meaning for improving NOxconversion efficiency and optimizing the diesel SCR catalytic converter.
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Kamenev, V. F., and P. A. Scheglov. "Principles for construction of mathematical model of a modern low-toxic diesel engine for transport and technological means and agricultural machines." Traktory i sel hozmashiny 83, no. 1 (January 15, 2016): 3–8. http://dx.doi.org/10.17816/0321-4443-66099.
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The article considers the principles of mathematical modeling of thermodynamic and gasdynamic processes in modern diesel engine and in systems intended to reduce the harmful substances level in exhaust gases, namely in oxidation catalytic converter, in particulate filter with regeneration system and in selective catalytic reduction system for nitrogen oxides neutralization.
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Marek, Vít, Lukáš Tunka, Adam Polcar, and Dušan Slimařík. "Reduction of NOx Emission of a Diesel Engine with a Multiple Injection Pump by SCR Catalytic Converter." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 64, no. 4 (2016): 1205–10. http://dx.doi.org/10.11118/actaun201664041205.
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This paper deals with reduction of NOx-emission of a diesel engine with multiple injection pump by SCR catalytic converter. Main aim of the measurement was the detection of SCR catalyst converter efficiency. Tests were realized at the Research and Development workplace of Zetor Tractor a.s. Used engine was equipped with a multiple injection pump with electromagnetic regulator of a fuel charge. During the experiment selective catalytic reduction and diesel particulate filter were used as an after treatment of harmful pollutants reduction. Testing cycle of the eight-point test was chosen and Non-Road Steady Cycle (NRSC) was maintained according to 97/68/EC directive. Results confirmed the dependencies between temperatures of SCR catalyst and exhaust gases and the volume of exhaust gases on efficiency of SCR catalyst. During the operation load of the engine, selective catalytic reduction reached efficiency over 90 %. Used after treatment system is suitable for reduction of harmful pollutants according to the Tier 4f norm.
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Paramadayalan, Thiyagarajan, and Atul Pant. "Selective catalytic reduction converter design: The effect of ammonia nonuniformity at inlet." Korean Journal of Chemical Engineering 30, no. 12 (November 21, 2013): 2170–77. http://dx.doi.org/10.1007/s11814-013-0155-z.
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Cova, Camilla Maria, Alessio Zuliani, Mario J. Muñoz-Batista, and Rafael Luque. "Efficient Ru-based scrap waste automotive converter catalysts for the continuous-flow selective hydrogenation of cinnamaldehyde." Green Chemistry 21, no. 17 (2019): 4712–22. http://dx.doi.org/10.1039/c9gc01596e.
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Wang, Bao Yi, and Qian Wang. "Design of Urea-SCR Model of a Feedforward Controller Based on Simulation in Diesel Engine." Advanced Materials Research 562-564 (August 2012): 1924–27. http://dx.doi.org/10.4028/www.scientific.net/amr.562-564.1924.
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Using a mathematical model, a feedforward controller model of Urea-SCR (selective catalytic reduction, SCR) in diesel engine is realized. At steady-state conditions, the simulated NOX concentration shows great consistence with the experimental value in the downstream of the converter. It can be seen that the simulation results show comparatively accurate performance of the model with the converter temperature changing linearly in the range from 450K to 750K.
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Viswanathan, Karthickeyan. "Experimental investigation on emission reduction in neem oil biodiesel using selective catalytic reduction and catalytic converter techniques." Environmental Science and Pollution Research 25, no. 14 (March 1, 2018): 13548–59. http://dx.doi.org/10.1007/s11356-018-1599-9.
Full textDissertations / Theses on the topic "Selective catalytic converter"
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ANDREOLI, SILVIA. "Catalytic processes for the control of nitrogen oxides emissions in the presence of oxygen." Doctoral thesis, Politecnico di Torino, 2016. http://hdl.handle.net/11583/2640030.
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The emissions of nitrogen oxides (NOx) from power plant and vehicles are known to cause damages to human health and environmental safety. The introduction of the EURO 6 regulations has imposed new limits on emissions of different types of pollutants present in the flue gases of diesel engines.
In particular, the emission limits of autovehicles are different between stoichiometric oxygen-to-fuel ratios and oxygen-lean engine conditions: the latter ones are responsible of large amounts of particulate matter (PM) and nitrogen oxides (NOx), which are very dangerous air pollutants. Conversely, since under stoichiometric conditions PM emissions are quite negligible and NOx can be fruitfully removed by catalytic abatement, the former have been regulated by more stringent legislation. However, emissions limits are becoming stricter and stricter in recent years also for lean engines, although in the presence of oxygen the abatement of NOx results in a much harder task.
Also for stationary plant, such as coffee roasters, the NOx emissions will be limited and the new regulations will be enforced from April 2016, and also in these applications the presence of oxygen in the pollutants-containing gas will make any abatement process very difficult.
For these reasons, to fulfil the requests of the more stringent regulations, it is important to develop more efficient technologies which result in prevention of pollutants formation, together with improved abatement process for the pollutants emitted in the flue gases.
NOx emission levels from autovehicles have been reduced by 66% from Euro 5, requiring the use of NOx after-treatment devices in addition to in-cylinder measures such as cooled EGR (Exhaust gas recirculation). LNTs (Low NOx Trap) have shown good NOx reduction performance and durability while SCR (Selective Catalytic Reduction), while offering also good NOx reduction performance, offers more flexibility for fuel economy and reduction of CO2 emissions. Manufacturers will likely choose the NOx after-treatment technology based on a combination of cost, reliability, fuel economy, and consumer acceptance. In large stationary applications (power plants, chemical industry, etc.), the issue of the NOx removal is often accomplished through the post-treatment of the exhaust gases by means of the selective catalytic reduction (SCR) method. The main advantages got from the exploitation of this technology are its high efficiency and its reliability as well as stability of the catalytic reaction, but the high cost represents a considerable drawback as well as the need to have a proper temperature range of effective performances that obliges to place SCR unit. In addition to these general limits, a further drawback of ammonia SCR process lies in the low acceptability of such a technology in some different contexts, such as the food industry, due to the unpleasant smell and danger of the reactant molecule employed.
The extension to vehicle exhausts is very interesting too, provided that a proper catalytic system is developed in ordered to answer to the different requests of mobile NOx sources. The most important difference in the operating conditions can be represented by the range temperature of interest for the process.
Hence, SCR devices could be even employed in mobile applications after adequate and calibrated system revision and modification in order to give effectiveness at lower light-off temperature (120 °C), since no solution seems to be viable with non-specific reducers (CO, HCs) mainly in the presence of O2, for instance in diesel engines.
In particular, the development of ―Low Temperature‖ NH3-SCR catalysts that work in the range of temperature from 120 to 300 °C is considered an ideal way to control NOx emissions also from stationary sources besides being an unavoidable necessity for vehicles. As a matter of fact, the reduction of the nitrogen oxides by means of ammonia in an oxidizing atmosphere has raised the need of the development of new catalysts, characterized by low cost and capability of ensuring high conversions, even at relatively low temperatures.
On the other hand, such a solution appears to be not viable for specific applications such as coffee roasters in food engineering, due to the unacceptance of ammonia, costs and safety reasons. Much more interesting could appear the attempt to prevent pollutant formation by developing intrinsically clean upstream processes.
In the present PhD, I focused my attention on the research of lower cost, versatility, environment-friendly nature and, of course, performer catalysts. The work was devoted to synthesize, characterize and testing of MnOx and MnOx-CeO2 catalysts proposed as innovative LT SCR catalysts, and a series of other catalytic systems for the selective oxidation of the organic compound emitted by an industrial roaster of coffee, in order to prevent the NOx formation in such devices.
Generally, Mn is used in both reduction and oxidation reactions due to its various types of labile oxygen as well as to the presence of different structures and morphologies.
To the best of our knowledge, the optimal oxidation state of the metal has not been assessed for the SCR reaction, despite numerous studies dealing with the role of MnOx and the deactivation of the catalysts.
Manganese oxides were investigated as catalysts for low-T SCR. Different MnOx catalysts were prepared by means of different operating conditions and characterized, as well as tested in the SCR process under lab-scale conditions. The goal was thereafter to understand the suitable Mn oxidation state necessary for SCR performances and to study the nature of active sites, which does not seem to be well clarified to date although a great research effort in this field has been made in the last two decades.
The contribute of CeO2 with MnOx was investigate so the solution combustion route was chosen for synthesizing MnOx-CeO2 catalysts. The Mn/Ce molar ratio as well as quality and quantity of organic fuel in the reaction were investigated as key parameters and their influence on the structural, microstructural and superficial properties was studied. Moreover, the redox property of MnOx-CeO2 samples and the synergistic effect of Ce4+ and Mnn+ ions were analysed. All these properties were correlated to the catalytic activity in order to optimize the parameters for the best catalytic performance. We have already tried to correlate some chemical properties of the surface with the performances in the NH3-SCR of pure MnOx samples prepared by the SCS technique and in this paper a direct comparison among those results and the evidences obtained for the Mn-Ce catalysts will be performed.
On the other hand, and also in connection with a project sponsored by a coffee-maker company, the issue of removal of NOx from roasting effluent was faced by studying catalysts and reactor conditions/configuration to prevention of the formation of nitrogen oxides itself.
The attention was given to catalysts consisting of nanoparticles of transition metals, such as copper, nickel, iron and manganese, which replace in part or in full the platinum group catalyst, usally used in industrial context to abate the large mass of VOC emitted in the process. A homogenous dispersion and control the size of the nanoparticles on the substrate was necessary to develop the most effective catalysts and with a higher yield.
The total or partial replacement of the platinum group with nanoparticles of transition metal catalysts leads to a considerable reduction in costs and also to the strengthening of sustainability and a secure supply of raw materials for EU producers.
The replacement of the catalyst with an oxidative catalyst active and selective at low temperature allows both to reduce VOCs (Volatile Organic Compounds) and the CO is to reduce the nitrogen compounds to molecular nitrogen.
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Hayes, Neil William. "Zeolite catalysts for the selective reduction of NOx." Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261783.
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Millington, Paul James. "An investigation of the selective catalytic reduction of nitrogen monoxide by hydrocarbons under oxidising conditions." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262564.
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Simon, Antoine. "Optimisation énergétique de chaînes de traction hybrides essence et Diesel sous contrainte de polluants : Étude et validation expérimentale." Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2010.
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L’hybridation électrique de la chaîne de traction automobile est l’une des solutions adoptées pour respecter les règlementations futures sur ses émissions. La stratégie de supervision de la chaîne de traction hybride répartit la puissance produite par le moteur à combustion interne et la machine électrique. Elle répond habituellement à un problème d’optimisation où l’objectif est de réduire la consommation de carburant mais nécessite à présent d’y ajouter les émissions polluantes. La chaîne de dépollution, placée à l’échappement du moteur, permet de diminuer la quantité de polluants émise dans l’atmosphère. Cependant, elle n’est efficace qu’à partir d’un seuil de température, et dépend de la chaleur apportée par les gaz d’échappement du moteur thermique. La première partie de ce travail est donc consacrée à la modélisation de la consommation énergétique et des émissions polluantes de la chaine de traction hybride. La modélisation de l’efficacité de la chaîne de dépollution est réalisée selon deux contextes. Le modèle zéro-dimensionnel est adapté aux contraintes de calcul de la commande optimale. Le modèle unidimensionnel associé à un estimateur d’état permet d’être embarqué et calculé en temps réel. À partir de ces travaux, la seconde partie de cette thèse déduit des stratégies de supervision à l’aide de la théorie de la commande optimale. Dans un premier cas, le principe de Bellman permet de calculer la commande optimale d’un véhicule hybride Diesel selon des critères de supervision ayant plus ou moins connaissance de l’efficacité de la chaîne de dépollution des émissions de NOX. Dans un second cas, une stratégie issue du Principe du Minimum de Pontryagin, embarquée sur un véhicule hybride essence, fonctionnant en temps réel et calibrée selon deux paramètres est proposée. L’ensemble de ces travaux est validé expérimentalement au banc moteur et montre une réduction significative des émissions polluantes pour une faible pénalité de carburantPowertrain hybridization is a solution that has been adopted in order to conform to future standards for emissions regulations. The supervisory strategy of the hybrid powertrain divides the power emitted between the internal combustion engine and the electric machine. In past studies, this strategy has typically responded to an optimization problem with the objective of reducing consumption. However, in addition to this, it is now necessary to take pollutant emissions into account as well. The after-treatment system, placed in the exhaust of the engine, is able to reduce pollutants emitted into the atmosphere. It is efficient from a certain temperature threshold, and the temperature of the system is dependent on the heat brought by the exhaust gas of the engine. The first part of this dissertation is aimed at modelling the energy consumption and pollutant emissions of the hybrid powertrain. The efficiency model of the after-treatment system is adapted for use in two different contexts. The zero-dimensional model conforms to the constraints of the optimal control calculation. The one-dimensional model associated with a state estimator can be embedded in a vehicle and calculated in real time. From this work, the second part of this dissertation deduces supervisory strategies from the optimal control theory. On the one hand, Bellman’s principle is used to calculate the optimal control of a Diesel hybrid vehicle using different supervisory criteria, each having more or less information about the after-treatment system efficiency over NOX emissions. On the other hand, a strategy from Pontryagin’s minimum principle, embedded in a gasoline hybrid vehicle, running in real time and calibrated with two parameters, is proposed. The whole of this work is validated experimentally on an engine test bed and shows a significant reduction in pollutant emissions for a slight fuel consumption penalty
Book chapters on the topic "Selective catalytic converter"
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Lambert, Tristan H. "Functional Group Reduction." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0010.
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The reduction of azobenzene 1 with catalyst 2 was reported (J. Am. Chem. Soc. 2012, 134, 11330) by Alexander T. Radosevich at Pennsylvania State University, representing a unique example of a nontransition metal-based two-electron redox catalysis platform. Wolfgang Kroutil at the University of Graz found (Angew. Chem. Int. Ed. 2012, 51, 6713) that diketone 4 was converted to piperidinium 5 with very high stereoselectivity using a transaminase followed by reduction over Pd/C. Dennis P. Curran at the University of Pittsburgh reported (Org. Lett. 2012, 14, 4540) that NHC-borane 7 is a convenient reducing agent for aldehydes and ketones, showing selectivity for the former as in the monoreduction of 6 to 8. A catalytic reduction of esters to ethers with Fe3(CO)12 and TMDS, as in the conversion of 9 to 10, was developed (Chem. Commun. 2012, 48, 10742) by Matthias Beller at the Leibniz-Institute for Catalysis. Meanwhile, iridium catalysis was used (Angew. Chem. Int. Ed. 2012, 51, 9422) by Maurice Brookhart at the University of North Carolina at Chapel Hill for the reduction of esters to aldehydes with diethylsilane (e.g., 11 to 12). As an impressive example of selective reduction, Ohyun Kwon at UCLA reported (Org. Lett. 2012, 14, 4634) the conversion of ester 13 to aldehyde 14, leaving the malonate moiety intact. The cobalt complex 16 was found (Angew. Chem. Int. Ed. 2012, 51, 12102) by Susan K. Hanson at Los Alamos National Laboratory to be an effective catalyst for C=O, C=N, and C=C bond hydrogenation, including the conversion of alkene 15 to 17. The use of frustrated Lewis pair catalysis for the low-temperature hydrogenation of alkenes such as 18 was developed (Angew. Chem. Int. Ed. 2012, 51, 10164) by Stefan Grimme at the University of Bonn and Jan Paradies the Karlsruhe Institute of Technology. Guanidinium nitrate was found (Chem. Commun. 2012, 48, 6583) by Kandikere Ramaiah Prabhu at the Indian Institute of Science to catalyze the hydrazine-based reduction of alkenes such as 20. The hydrogenation of thiophenes is difficult for a number of reasons, but now Frank Glorius at the University of Münster has developed (J. Am. Chem. Soc. 2012, 134, 15241) an effective system for the highly enantioselective catalytic hydrogenation of thiophenes and benzothiophenes, including 22.
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Taber, Douglass F. "Functional Group Protection." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0011.
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Zhong-Jun Li of Peking University developed (J. Org. Chem. 2011, 76, 9531) a Co catalyst for selectively replacing one benzyl protecting group of 1 with silyl. Carlo Unverzagt of Universität Bayreuth devised (Chem. Commun. 2011, 47, 10485) oxidative conditions for debenzylating the azide 3 to 4. Tadashi Katoh of Tohoku Pharmaceutical University found (Tetrahedron Lett. 2011, 52, 5395) that the dimethoxybenzyl protecting group of 5 could be selectively removed in the presence of benzyl and p-methoxybenzyl. Scott T. Phillips of Pennsylvania State University showed (J. Org. Chem. 2011, 76, 7352) that in the presence of phosphate buffer, catalytic fluoride was sufficient to desilylate 7. Philip L. Fuchs of Purdue University employed (J. Org. Chem. 2011, 76, 7834, not illustrated) the neutral Robins conditions (Tetrahedron Lett. 1992, 33, 1177) to effect a critical desilylation. Pengfei Wang of the University of Alabama at Birmingham found (J. Org. Chem. 2011, 76, 8955) that an excess of the diol 9 both oxidized the primary alcohol 10 and installed the photolabile protecting group on the product aldehyde. Hiromichi Fujioka of Osaka University showed (Angew. Chem. Int. Ed. 2011, 50, 12232) that addition of Ph3P to 12 transiently protected the aldehyde, allowing selective reduction of the ketone to the alcohol. Willi Bannwarth of Albert-Ludwigs-Universität Freiburg deprotected (Angew. Chem. Int. Ed. 2011, 50, 6175) the chelating amide of 14, leaving the usually sensitive Fmoc group in place. Bruce C. Gibb, now at Tulane University, hydrolyzed (Nature Chem. 2010, 2, 847) 16 more rapidly than the very similar 17, by selective equilibrating complexation of 16 and 17 with a cavitand. Aravamudan S. Gopalan of New Mexico State University converted (Tetrahedron Lett. 2010, 51, 6737) proline 19 to the amide ester 10 by exposure to triethyl orthoacetate. K. Rajender Reddy of the Indian Institute of Chemical Technology oxidized (Angew. Chem. Int. Ed. 2011, 50, 11748) the formamide 22 to the carbamate 23 by exposure to H2O2 in the presence of 21. James M. Boncella of the Los Alamos National Laboratory deprotected (Org. Lett. 2011, 13, 6156) 24 by exposure to visible light in the presence of a Ru catalyst.
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Taber, Douglass F. "Reactions of Alkenes: The RajanBabu Synthesis of Pseudopterosin G-J Aglycone Dimethyl Ether." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0029.
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Xiangge Zhou of Sichuan University showed (Tetrahedron Lett. 2011, 52, 318) that even the monosubstituted alkene 1 was smoothly converted to the methyl ether 2 by catalytic FeCl3. Brian C. Goess of Furman University protected (J. Org. Chem. 2011, 76, 4132) the more reactive alkene of 3 as the 9-BBN adduct, allowing selective reduction of the less reactive alkene to give, after reoxidation, the monoreduced 4. Nobukazu Taniguchi of the Fukushima Medical University added (Synlett 2011, 1308) Na p-toluenesulfinate oxidatively to 1 to give the sulfone 5. Krishnacharya G. Akamanchi of the Indian Institute of Chemical Technology, Mumbai oxidized (Synlett 2011, 81) 1 directly to the bromo ketone 6. Osmium is used catalytically both to effect dihydroxylation, to prepare 8, and to mediate oxidative cleavage, as in the conversion of 7 to the dialdehyde 9. Ken-ichi Fujita of AIST Tsukuba devised (Tetrahedron Lett. 2011, 52, 3137) magnetically retrievable osmium nanoparticles that can be reused repeatedly for the dihydroxylation. B. Moon Kim of Seoul National University established (Tetrahedron Lett. 2011, 52, 1363) an extraction scheme that allowed the catalytic Os to be reused repeatedly for the oxidative cleavage. Maurizio Taddei of the Università di Siena showed (Synlett 2011, 199) that aqueous formaldehyde could be used in place of Co/H2 (syngas) for the formylation of 1 to 10. Hirohisa Ohmiya and Masaya Sawamura of Hokkaido University prepared (Org. Lett. 2011, 13, 1086) carboxylic acids (not illustrated) from alkenes using CO2. Joseph M. Ready of the University of Texas Southwestern Medical Center selectively arylated (Angew. Chem. Int. Ed. 2011, 50, 2111) the homoallylic alcohol 11 to give 12. Many reactions of alkenes are initiated by hydroboration, then conversion of the resulting alkyl borane. Hiroyuki Kusama of the Tokyo Institute of Technology photolyzed (J. Am. Chem. Soc. 2011, 133, 3716) 14 with 13 to give the ketone 15. William G. Ogilvie of the University of Ottawa added (Synlett 2011, 1113) the 9-BBN adduct from 1 to 16 to give 17. Professors Ohmiya and Sawamura effected (Org. Lett. 2011, 13, 482) a similar conjugate addition, not illustrated, of 9-BBN adducts to α,β-unsaturated acyl imidazoles.
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Taber, Douglass. "Functionalization of C-H Bonds: The Baran Synthesis of Dihydroxyeudesmane." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0016.
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Arumugam Sudalai of the National Chemical Laboratory, Pune reported (Tetrahedron Lett. 2008, 49, 6401) a procedure for hydrocarbon iodination. With straight chain hydrocarbons, only secondary iodination was observed. Chao-Jun Li of McGill University uncovered (Adv. Synth. Cat. 2009, 351, 353) a procedure for direct hydrocarbon amination, converting cyclohexane 1 into the amine 3. Justin Du Bois of Stanford University established (Angew. Chem. Int. Ed. 2009, 48, 4513) a procedure for alkane hydroxylation, converting 4 selectively into the alcohol 6. The oxirane 8 usually also preferentially ozidizes methines, hydroxylating steroids at the C-14 position. Ruggero Curci of the University of Bari found (Tetrahedron Lett. 2008, 49, 5614) that the substrate 7 showed some C-14 hydroxylation, but also a useful yield of the ketone 9. The authors suggested that the C-7 acetoxy group may be deactivating the C-14 C-H. C-H bonds can also be converted directly to carbon-carbon bonds. Mark E. Wood of the University of Exeter found (Tetrahedron Lett. 2009, 50, 3400) that free-radical removal of iodine from 10 followed by intramolecular H-atom abstraction in the presence of the trapping agent 11 delivered 12 with good diastereo control. Professor Li observed (Angew. Chem. Int. Ed. 2008, 47, 6278) that under Ru catalysis, hydrocarbons such as 13 could be directly arylated. He also established (Tetrahedron Lett. 2008, 49, 5601) conditions for the direct aminoalkylation of hydrocarbons such as 13, to give 17. Huw M. L. Davies of Emory University converted (Synlett 2009, 151) the ester 4 to the homologated diester 19 in preparatively useful yield using the diazo ester 18, the precursor to a selective, push-pull stabilized carbene. Intramolecular bond formation to an unactivated C-H can be even more selective. Guoshen Liu of the Shanghai Institute of Organic Chemistry developed (Organic Lett. 2009, 11, 2707) an oxidative Pd system that cyclized 20 to the seven-membered ring lactam 21 . Professor Du Bois devised (J. Am. Chem. Soc. 2008 , 130, 9220) a Rh catalyst that effected allylic amination of 22, to give 23 with substantial enantiocontrol. Dalibor Sames of Columbia University designed (J. Am. Chem. Soc. 2009, 131, 402) a remarkable cascade approach to C-H functionalization. Exposure of 24 to Lewis acid led to intramolecular hydride abstraction. Cyclization of the resulting stabilized carbocation delivered the tetrahydropyan 25 with remarkable diastereocontrol.
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Taber, Douglass F. "Reduction of Organic Functional Groups." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0011.
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Cornelis J. Elsevier of the University of Amsterdam developed (ACS Catal. 2014, 4, 1349) an improved Pd-based protocol for the hydrogenation of an alkyne 1 to the Z-alkene 2. Yongbo Zhou and Shuang-Feng Yin of Hunan University showed (Adv. Synth. Catal. 2014, 356, 765) that under Cu catalysis, hypophosphorous acid selectively reduced the terminal alkyne of 3 to the ene-yne 4. Hidefumi Makabe of Shinshu University found (Tetrahedron Lett. 2014, 55, 2822) that the iodoalkyne 5 was reduced to the iodoalkene 6 by diimide, conveniently generated from the arenesulfonyl hydrazide. Manat Pohmakotr of Mahidol University used (Eur. J. Org. Chem. 2014, 1708) P- 2 Ni to reduce the sulfoxide 7 to the alkene 8. Shinya Furakawa and Takayuki Komatsu of the Tokyo Institute of Technology devised (ACS Catal. 2014, 4, 1441) a Pd catalyst for the selective reduction of the nitro group of 9 to the aniline 10. Hiroshi Kominami of Kinki University employed (Chem. Commun. 2014, 50, 4558) a Ti- promoted Ag catalyst to deoxygenate the epoxide 11 to the alkene 12. Benjamin R. Buckley and K. G. Upul Wijayantha of Loughborough University described (Synlett 2014, 25, 197) an alternative protocol (not illustrated) for epoxide deoxygenation. Xiaohui Fan of Lanzhou Jiaotong University observed (Eur. J. Org. Chem. 2014, 498) that the reduction of 13 to 14 proceeded without cyclopropane opening, suggesting the reaction did not involve substantial charge separation. Michel R. Gagné of the University of North Carolina deployed (Angew. Chem. Int. Ed. 2014, 53, 1646) catalytic trispentafluorophenylborane to selectively reduce 15 to 16. Gojko Lalic of the University of Washington reduced (Angew. Chem. Int. Ed. 2014, 53, 752) a secondary iodide 17 to the hydrocarbon 18 under Cu catalysis. Primary bromides and triflates could also be reduced, while many other functional groups, including tosylates, were stable. Marc Lemaire of the Université Claude-Bernard Lyon 1 converted (Tetrahedron Lett. 2014, 55, 23) the nitrile 19 to the aldehyde 20 by V-catalyzed reduction followed by hydrolysis. Matthias Beller of the Universität Rostock showed (Chem. Eur. J. 2014, 20, 4227) that a nitrile 21 could be reduced to the amine 22 with very little by- product dimer.
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Taber, Douglass. "Enantioselective Construction of Alkylated Stereogenic Centers." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0040.
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Carsten Bolm of RWTH Aachen developed (Angew. Chem. Int. Ed. 2008, 47, 8920) an Ir catalyst that effected hydrogenation of trisubstituted enones such as 1 with high ee. Benjamin List of the Max-Planck-Institut Mülheim devised (J. Am. Chem. Soc. 2008, 130, 13862) an organocatalyst for the enantioselective reduction of nitro acrylates such as 3 with the Hantzsch ester 4. Gregory C. Fu of MIT optimized (J. Am. Chem. Soc. 2008, 130, 12645) a Ni catalyst for the enantioselective arylation of propargylic halides such as 6. Both enantiomers of 6 were converted to the single enantiomer of 8. Michael C. Willis of the University of Oxford established (J. Am. Chem. Soc. 2008, 130, 17232) that hydroacylation with a Rh catalyst was selective for one enantiomer of the allene 9, delivering 11 in high ee. Similarly, José Luis García Ruano of the Universidad Autónoma de Madrid found (Angew. Chem. Int. Ed. 2008, 47, 6836) that one enantiomer of racemic 13 reacted selectively with the enantiomerically- pure anion 12, to give 14 in high diastereomeric excess. Ei-chi Negishi of Purdue University described (Organic Lett. 2008, 10, 4311) the Zr-catalyzed asymmetric carboalumination (ZACA reaction) of the alkene 15 to give the useful chiron 16. David W. C. MacMillan of Princeton University developed (Science 2008, 322, 77) an intriguing visible light-powered oxidation-reduction approach to enantioselective aldehyde alkylation. The catalytic chiral secondary amine adds to the aldehyde to form an enamine, that then couples with the radical produced by reduction of the haloester. Two other alkylations were based on readily-available chiral auxiliaries. Philippe Karoyan of the Université Pierre et Marie Curie observed (Tetrahedron Lett . 2008, 49, 4704) that the acylated Oppolzer camphor sultam 20 condensed with the Mannich reagent 21 to give 22 as a single diastereomer. Andrew G. Myers of Harvard University developed the pseudoephedrine chiral auxiliary of 23 to direct the construction of ternary alkylated centers. He has now established (J. Am. Chem. Soc. 2008, 130, 13231) that further alkylation gave 24, having a quaternary alkylated center, in high diastereomeric excess.
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Taber, Douglass. "Transition Metal-Mediated Ring Construction: The Yu Synthesis of 1-Desoxyhypnophilin." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0075.
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Both 1 and 3 are inexpensive prochiral starting materials. Tae-Jong Kim of Kyungpook National University devised (Organomet. 2008, 27, 1026) a chiral Cu catalyst that efficiently converted 1 (other ring sizes worked as well) to the enantiomerically pure ester 2. Alexandre Alexakis of the University of Geneva found (Adv. Synth. Cat. 2008, 350, 1090) a chiral Cu catalyst that mediated the enantioselective coupling of 3 with Grignard reagents such as 4 . The π-allyl Pd complex derived from 6 is also prochiral. Barry M. Trost of Stanford University showed (Angew. Chem. Int. Ed. 2008, 47, 3759) that with appropriate ligand substitution, coupling with the phthalimide 7 proceeded to give 8, readily convertible to (-)-oseltamivir (Tamiflu) 9, in high ee. Jonathan W. Burton of the University of Oxford found (Chem Commun. 2008, 2559) that Mn(OAc)3 -mediated cyclization of 10 delivered the lactone 12 with high diastereocontrol. John Montgomery of the University of Michigan observed (Organic Lett. 2008, 10, 811) that the Ni-catalyzed cyclization of 12 also proceeded with high diastereocontrol. Ken Tanaka of the Tokyo University of Agriculture and Technology combined (Angew. Chem. Int. Ed. 2008, 47, 1312) Rh-catalyzed ene-yne cyclization of 14 with catalytic ortho C-H functionalization, leading to 16 in high ee. Eric N. Jacobsen of Harvard University designed (Angew. Chem. Int. Ed. 2008, 47, 1469) a chiral Cr catalyst for the intramolecular carbonyl ene reaction, that converted 17 to 18 in high ee. Using a stoichiometric prochiral Cr carbene complex 20 and the enantiomerically-pure secondary propargylic ether 19, Willam D. Wulff of Michigan State University prepared (J. Am. Chem. Soc. 2008, 130, 2898) a facially-selective Cr-complexed o -quinone methide intermediate, that cyclized to 21 with high ee. A variety of methods have been put forward for the transition metal-mediated construction of polycarbocyclic systems. One of the more powerful is the enantioselective Rh-catalyzed stitching of the simple substrate 22 into the tricycle 23 devised (J. Am. Chem. Soc. 2008, 130, 3451) by Takanori Shibata of Waseda University. Inter alia, ozonolysis of 23 delivered the cyclopentane 24 containing two all-carbon quaternary centers.
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Taber, Douglass F. "The Nicolaou Synthesis of (+)-Vannusal." In Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0090.
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The correct assignment of relative configuration for portions of a complex structure that are remote one from another can present substantial difficulties. This was brought home in the course of the synthesis of (+)-vannusal 3 described (Angew. Chem. Int. Ed. 2009, 48, 5642, 5648) by K. C. Nicolau of Scripps/La Jolla. In fact, they prepared several alternative diastereomers, including the originally assigned structure, before finally coming to 3, the spectra of which matched those of the natural product. Their synthetic strategy was based on the late-stage convergent coupling of the aldehyde 13 with the iodide 19, leading to 1. The preparation of 13 began with conjugate addition of the 1-propenyl Grignard reagent 5 to the cyclohexenone 4. Deprotection, oxidation, and acetal formation led to 6, which cyclized with high diastereocontrol to 7. Carbomethoxylation of the ketone followed by Mn(OAc)3 cyclization delivered the highly strained norbornane 8 as a single diastereomer. Condensation of the derived ketone 9 with acetone 10 followed by reduction set the three remaining ternary stereogenic centers of 13. O-Alkylation of the aldehyde 11 followed by Claisen rearrangement established the alkylated quaternary center. Functional group manipulation then converted 12 into 13. The preparation of the iodide 19 began with the diene 14. Hydroboration followed by acetylation provided the meso diol. Enzymatic hydrolysis proceeded with high enantioselectivity, giving 15. Opening of the epoxide 16 with 2-propenyl lithium gave the trans alcohol, which was converted to the requisite cis alcohol 17 by Mitsunobu esterification followed by hydrolysis. Shapiro iodination of 18 then delivered 19. The iodide 19 was enantiomerically pure, but the aldehyde 13 was racemic, so coupling of the two led to 1 and its diastereomer. The cyclization of 1 with SmI2 proceeded with remarkable diastereocontrol, to give the desired 2 directly. Deprotection and oxidation then completed the synthesis of (+)-vannusal B 3. It is noteworthy that throughout this synthesis, the radicals AZADO 20 and 1-Me-AZADO 21, developed by Yoshiharu Iwabuchi (Organic Highlights, March 8, 2010), more efficient than the traditional TEMPO, were used to effect selective catalytic oxidation.
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Taber, Douglass F. "The Li Synthesis of (–)-Fusarisetin A." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0097.
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Fusarisetin A 3 is an intriguing inhibitor of cell migration and invasion that is not itself cytotoxic. Ang Li of the Shanghai Institute of Organic Chemistry developed (J. Am. Chem. Soc. 2012, 134, 920) a total synthesis of (–)-fusarisetin A, demonstrating that the natural material had the absolute configuration opposite to that originally assigned. A key step in the synthesis was the highly diastereoselective cyclization of 1 to 2. The absolute configuration of 1 and so of synthetic 3 was derived from commercial citronellol, which is prepared on an industrial scale by asymmetric synthesis. To this end, the reagents 6 and 8 were required. The β-ketothio ester 6 was prepared from the Meldrum’s acid 4 and the phosphonate 8 was derived from methyl sorbate 7. The acetal of citronellal 9 was ozonized with reductive work-up to give the alcohol 10. Protection followed by hydrolysis gave the aldehyde 11, which was condensed with 8 to give the triene 12. Deprotection followed by oxidation delivered an aldehyde, which was condensed with 6 to give the Diels-Alder precursor 1. With BF3 • OEt2 catalysis, the Diels-Alder cycloaddition proceeded under mild conditions, –40oC for 40 min, leading to 2 as a single diastereomer. Comparable intramolecular Diels-Alder cyclizations with single carbonyl activation gave mixtures of diastereomers. The alcohol 13 was prepared by transesterification of 2 with trifluoroethanol. Activation with MsCl led directly to the kinetic O-alkylation product 14. Following the precedent of Trost (J. Am. Chem. Soc. 1980, 102, 2840), exposure to a Pd catalyst smoothly converted 14 into 15 as the desired diastereomer. Condensation of the ester 15 with the amine 16 gave the diene 17. Selective oxidation of the monosubstituted alkene under Wacker conditions gave the ketone, which was reduced selectively by the Luche protocol to the alcohol 18. Exposure of 18 to NaOCH3 initiated Dieckmann cyclization, leading to (–)-fusarisetin A 3.
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Taber, Douglass F. "C–H Functionalization: The Shaw Synthesis of E-δ-Viniferin." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0022.
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Thomas Lectka of Johns Hopkins University reported (J. Org. Chem. 2014, 79, 8895) a simple protocol for free radical monofluorination, exemplified by the conversion of 1 to 2. Michael K. Hilinski of the University of Virginia used (Org. Lett. 2014, 16, 6504) a catalytic amount of the ketone 4 to mediate the oxidation of 3 to 5. Oxidation of 3 with DMDO gave the regioisomeric tertiary alcohol (not illustrated). Jeung Gon Kim and Sukbok Chang of KAIST used (Chem. Commun. 2014, 50, 12073) an Ir catalyst to convert 6 selectively to the primary sulfonamide 7. Paul J. Chirik of Princeton University employed (J. Am. Chem. Soc. 2014, 136, 12108) a Co catalyst to effect the migration of the internal alkene of 8 to the terminal alkene, that then underwent dehydrogenative silylation with 9 to deliver the allyl silane 10. Jiang Cheng of Changzhou University developed (J. Org. Chem. 2014, 79, 9847) conditions for the aminoalkylation of cyclohexane 11 with 12 to give 13. Ilhyong Ryu of Osaka Prefecture University and Maurizio Fagnoni of the University of Pavia observed (Chem. Sci. 2014, 5, 2893) high selectivity in the addition of 14 to 15. Of the five possible regioisomers, 16 dominated. In another light-mediated transformation, Shin Kamijo of Yamaguchi University and Masayuki Inoue of the University of Tokyo added (Chem. Sci. 2014, 5, 4339) 17 to 18 to give 19. Huw M. L. Davies of Emory University established (J. Am. Chem. Soc. 2014, 136, 17718) conditions for the enantioselective alkylation of a methyl ether 21 with 20 to give the ester 22. Selective methyl insertion was observed even with much more complex substrates. The trichloroethyl ester was critical for this transformation. James A. Bull of Imperial College London effected (Org. Lett. 2014, 16, 4956) selective cis-arylation of the proline-derived amide 23 with 24 to give 25. E. Peter Kündig of the University of Geneva coupled (Chem. Eur. J. 2014, 20, 15021) the amine 27 with 26, then cyclized that product to the indoline 28. The enantiomeric Pd catalyst delivered the regioisomeric C–H insertion product.
Conference papers on the topic "Selective catalytic converter"
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Koralewska, Ralf. "NOx Reduction: The Challenge for Innovative Concepts in Europe." In 19th Annual North American Waste-to-Energy Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/nawtec19-5438.
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During combustion, most of the waste’s nitrogen content is transferred to the flue gases as nitrogen oxide, NOx. The EU Waste Incineration Directive defines a maximum emission limit value for NOx of 200 mg/Nm3 as a daily average value referred to 11% O2. Based on National Emission Ceilings (NEC) defined by the Gothenburg Protocol, it can be expected that the limit values for NOx in the EU will become even more stringent. In some European countries (e.g. The Netherlands, Austria, Switzerland) a lower emission limit has already been introduced. Selective Catalytic Reduction (SCR) technologies are used in many cases to achieve the above-mentioned NOx limits. However, there are drawbacks to SCR systems such as high investment cost. Operation cost is also quite high due to the energy consumption necessary for the reheating of the flue gas as well as the increased pressure loss. Innovative technologies are therefore required to make it possible to reconcile both requirements: reduced emissions and increased energy efficiency. Selective Non-Catalytic Reduction (SNCR) systems are based on the selective reaction of ammonia or urea injected into the upper furnace. In many cases SNCR technologies are limited by the ammonia slip which increases in case of more stringent NOx requirements. According to the relevant BREF document, an ammonia slip limit of 10 mg/Nm3 is generally required at the stack. In order to achieve reduced NOx values, it is necessary to implement measures to reduce ammonia slip, by means of either a wet scrubber or a High-dust catalytic converter. EfW plants in Mainz (Germany) and Brescia (Italy) are examples of operational plants combining SNCR with such a catalytic converter type. In addition R&D activities are carried out on the development of simplified reaction mechanisms to be implemented in Computational Fluid Dynamics (CFD) codes. With these tools it will be possible to describe the interaction between turbulent mixing, radiation and chemical reaction rates. Another option to achieve low NOx values (below 100 mg/Nm3) is the reduction of NOx by so-called primary measures, e.g. the Very Low NOx process (VLN), which has been developed by MARTIN jointly with its cooperation partners. The VLN process is based on a grate-based combustion system. The “VLN gas” is drawn off at the rear end of the grate and is reintroduced into the upper furnace in the vicinity of the SNCR injection positions. NOx will be reduced significantly, ensuring low NOx emission values at the stack as required, at low values for ammonia slip. The new EfW plant in Honolulu (USA) will be equipped with the VLN process. In Coburg (Germany), the VLN process will be retrofitted in an existing installation. This paper documents the potential and the limitations of different measures for NOx reduction as well as examples of recent innovative EfW plants in Europe using MARTIN technologies successfully.
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Jayasuriya, Jeevan, Arturo Manrique, Reza Fakhrai, Jan Fredriksson, and Torsten Fransson. "Gasified Biomass Fuelled Gas Turbine: Combustion Stability and Selective Catalytic Oxidation of Fuel-Bound Nitrogen." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90988.
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Low heating value of gasified biomass and its fuel bound nitrogen containing compounds challenge the efforts on utilizing gasified biomass on gas turbine combustor. Low heating value of the gas brings along combustion stability issues and pollutant emission concerns. The fuel bound nitrogen present in gasified biomass could completely be converted to NOx during the combustion process. Catalytic combustion technology, showing promising developments on ultra low emission gas turbine combustion of natural gas could also be the key to successful utilization of biomass in gas turbine combustor. Catalysts could stabilize the combustion process of low heating value gas while the proper design of the catalytic configuration could selectively convert the fuel bound nitrogen into molecular nitrogen. This paper presents preliminary results of the experimental investigations on combustion stability and nitrogen selectivity in selective catalytic oxidation of ammonia in catalytic combustion followed by a brief description of the design of catalytic combustion test facility. The fuel-NOx reduction strategy considered in this study was to preprocess fuel in the catalytic system to remove fuel bound nitrogen before real combustion reactions occurs. The catalytic combustion system studied here contained two stage reactor in one unit containing fuel preprocessor (SCO catalyst) and combustion catalysts. Experiments were performed under lean combustion conditions (λ value from 6 up to 22) using a simulated mixture of gasified biomass. The Selective Catalytic Oxidation approach was considered to reduce the conversion of NH3 into N2. Results showed very good combustion stability, higher combustion efficiency and good ignition performances under the experimental conditions. However, the selective oxidation of fuel bound nitrogen into N2 was only in the range of 20% to 30% under the above conditions.
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Toema, Mohamed, and Kirby S. Chapman. "Modeling of Lambda Sensor Output With Exhaust Gas Mixtures From Natural Gas-Fueled Engines." In ASME 2011 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/icef2011-60188.
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The increasingly strict emission regulations may require implementing Non-Selective Catalytic Reduction (NSCR) system as a promising emission control technology for stationary rich burn spark ignition engines. Many recent investigations used NSCR systems for stationary natural gas fueled engines showed that NSCR systems were unable to consistently control the emissions level below the compliance limits. Modeling of NSCR components to better understand, and then exploit, the underlying physical processes that occur in the lambda sensor and the catalyst media is now considered an essential step toward the required NSCR system performance. This paper presents the work done to date on a modeling of lambda sensor that provides feedback to the air-to-fuel controller. Several recent experimental studies indicate that the voltage signal from the lambda sensor may not be interpreted correctly because of the physical nature in the way the sensor senses the exhaust gas concentration. Correct interpretation of the sensor output signal is necessary to achieve consistently low emissions level. The goal of this modeling study is to improve the understanding of the physical processes that occur within the sensor, investigate the cross-sensitivity of various exhaust gas species on the sensor performance, and finally this model serves as a tool to improve NSCR control strategies. This model simulates the output from a planar switch type lambda sensor. The model consists of three modules. The first module models the multi-component mass transport through the sensor protective layer. Diffusion fluxes are calculated using the Maxwell-Stefan equation. The second module includes all the surface catalytic reactions that take place on the sensor platinum electrodes. All kinetic reactions are modeled based on the Langmuir-Hinshelwood kinetic mechanism. The model incorporates for the first time methane catalytic reactions on the sensor platinum electrode. The third module is responsible for simulating the reactions that occur on the electrolyte material and determine the sensor output voltage. The model results are validated using field test data obtained from a mapping study of a natural gas-fueled engine equipped with NSCR system. The data showed that the lambda sensor output voltage is influenced by the reducing species concentration, such as carbon monoxide (CO) and hydrogen (H2). The results from the developed model and the experimental data showed strong correlations between CO and H2 with the sensor output voltage within the lambda operating range between 0.994 to 1.007 (catalytic converter operating window). This model also showed that methane does not significantly influence the lambda sensor performance compared to the effect of CO and H2.
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Wanker, R., J. C. Wurzenberger, and D. Higbie. "1D and 3D CFD Simulation of Exhaust-Gas Aftertreatment Devices: Parameter Optimization via Genetic Algorithm." In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-3088.
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Future limits on emissions for both gasoline and Diesel engines require adequate and advanced systems for the aftertreatment of the exhaust gas. Computer models as a complementary tool to experimental investigations are indispensable to design reliable after-treatment devices such as catalytic converters and Diesel particulate filters. Therefore, the objective of this contribution is to present an integrated 1D to 3D simulation workflow of catalytic converters (Three-Way-Catalyst, Diesel Oxidation Catalyst, Selective Catalytic Reduction Catalyst, ...) and Diesel particulate filters. The parameters or sets of parameters are obtained by a fast and efficient 1D-approach of BOOST. They are readily transferable to the 3D simulation code FIRE to investigate detailed aspects such as spatial distribution of temperatures or heat losses. Thus, identical models predicting flow, energy and conversion of species of the exhaust gas were employed to both the 1D gas exchange/cycle and the 3D CFD simulation code. This approach allows to carry out a basic analysis and to define first layouts for the exhaust system. Characteristic parameters of this first design stage are used for the multi-dimensional simulation to evaluate the overall performance including fine tuning of aftertreatment systems.
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Verma, Anil. "Rib Selection to Ensure Optimum Monolith Stresses in Catalytic Converters." In International Congress & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1991. http://dx.doi.org/10.4271/910376.
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Benoit, Jeffrey A., Charles Ellis, and Joseph Cook. "Ultra Low Emissions Combustion and Control Systems: Installation Into Mature Power Plant Gas Turbines." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22261.
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The search for power plant sustainability options continues as regulating agencies exert more stringent industrial gas turbine emission requirements on operators. Purchasing power for resale, de-comissioning current capabilities altogether and repowering by replacing or converting existing equipment to comply with emissions standards are economic-driven options contemplated by many mature gas turbine operators. One Las Vegas Nevada, USA operator, NV Energy, with four (4) natural gas fired W501B6 Combined Cycle units at their Edward W. Clark Generating Station, was in this situation in 2006. The units, originally configured with diffusion flame combustion systems, were permitted at 103 ppm NOx with regulatory mandates to significantly reduce NOx emissions to below 5ppm by the end of 2009. Studies were conducted by the operator to evaluate the economic viability of using a Selective Catalytic Reduction (SCR) system, which would have forced significant modifications to the exhaust system and heat recovery steam generator (HRSG), or convert the turbines to operate with dry low-emissions combustion systems. Based on life cycle cost and installation complexity, the ultra-low emission combustion system was selected. This technical paper focuses on a short summary of the end user considerations in downselecting options, the ultra low emissions technology and key features employed to achieve these low emissions, an overview of the conversion scope and a review and description of the control technology employed. Finally, a technical discussion of the low emissions operational flexibility will be provided including performance results of the converted units.
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Hotz, Nico. "Micro- and Nano-Structured Catalytic Reactor for Biofuel Reforming in a Solar Collector." In ASME 2012 6th International Conference on Energy Sustainability collocated with the ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/es2012-91338.
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In this study, a novel flow-based method is presented to place catalytic nanoparticles into a reactor by solgelation of a porous ceramic consisting of copper-based nanoparticles, silica sand, ceramic binder, and a gelation agent. This method allows for the placement of a liquid precursor containing the catalyst into the final reactor geometry without the need of impregnating or coating of a substrate with the catalytic material. The so generated foam-like porous ceramic shows properties highly appropriate for use as catalytic reactor material, e.g., reasonable pressure drop due to its porosity, high thermal and catalytic stability, and excellent catalytic behavior. The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement. The results of the present study confirm that product gas mixtures with up to 75% hydrogen content and less than 0.2% CO content can be achieved, which is an excellent result. The reactor temperature can be kept as low as 220°C while obtaining a methanol conversion of up to 70%. The used PROX catalyst showed selective CO conversion rates above 99.5% for temperatures between 80 and 100°C in presence of large molar fractions of H2O and CO2.
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Wang, Tianyou, Shuliang Liu, Hongjun Xu, Xing Li, Maolin Fu, Landong Li, and Naijia Guan. "Evaluation of In-Situ Synthesized Monolithic Metal-MFI/Cordierite Catalysts to Remove NOx From Lean Exhaust." In ASME 2005 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/icef2005-1253.
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In this study, ZSM-5 zeolites were successfully in situ synthesized on the surface of honeycomb cordierite substrate and certified by XRD and SEM techniques. Strong interaction between zeolite and substrate has been found during in-situ synthesis, and hydrothermal stabilities of the zeolites was improved by entailing. The in-situ synthesized monolithic ZSM-5/cordierite showed superior thermal and hydrothermal stabilities. Cu-ZSM-5/cordierite was prepared by ion-exchange and impregnation methods were studied as catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NOx) in a lean-burn gasoline engine. Engine test results show that NOx emission was decreased by reductants of HC and CO in the exhaust gas without any other extra reducing agents. It also exhibited high activities. Using Cu-ZSM-5/cordierite, the maximum NOx conversion efficiency to N2 reached to 64% at the exhaust temperature of 400 °C and the gas hourly space velocity (GHTV) of 25 000/h. Meanwhile, the HC conversion efficiency was about 60%, while CO was little converted. Cu-ZSM-5/cordierite also showed good duration and anti-poison properties. Furthermore, the activated temperature of the Cu-ZSM-5/cordierite was decreased and the NOx conversion was increased via addition of iridium as a modifier.
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Varghese, Vinay, and Soham Mujumdar. "Effect of Porosity on Tool Wear During Micromachining of Additive Manufactured Titanium Alloy." In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-80096.
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Abstract Porosity is a major quality issue in additively manufactured (AM) materials due to improper selection of raw material or process parameters. While porosity is kept to a minimum for structural applications, parts with intentional (engineered) porosity find applications in prosthetics, sound dampeners & mufflers, catalytic converters, electrodes, heat exchangers, filters, etc. During post-processing of additive manufactured components using secondary machining to obtain required dimensional tolerance and/or surface quality, part porosity could lead to fluctuating cutting forces and reduced tool life. The machinability of the porous AM material is poor compared to the homogenous wrought material due to the intermittent cutting and anisotropy of AM materials. The cutting parameters for machining are generally optimized for continuous wrought material and are not applicable for porous AM material. Micromilling experiments were carried out on AM Ti6Al4V alloy with different porosity levels and cutting speed using a 1 mm diameter end mill. The progression of tool wear and associated mechanisms during micro-milling of additive manufactured Ti6Al4V samples with different porosity levels are experimentally investigated. Insights into tool-workpiece interaction during micro-machining are obtained in cases where pore size could be comparable to the cutting tool diameter. This research could lead to efficient hybrid additive-subtractive manufacturing technologies with improved tool life and reduced costs.
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Kaul, Sanjay, Rajpalsinh Gohil, Parul Bisharia, and Apoorva Roy. "Analysis of CCR Expansion Joints." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10559.
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Abstract The CCR (Continuous Catalytic Reforming) Platforming™ process is Honeywell UOP’s technology to convert low octane naphtha to high octane fuel or petrochemical feedstock such as aromatics. It is accomplished in a hydrogen atmosphere at elevated temperature and pressure across a platinum containing catalyst. The process flow is routed through heaters, blowers and coolers between reactors to maintain the heat of reaction. This article captures the procedure of selecting a suitable expansion joint for absorbing thermal movement between two important pieces of CCR equipment — the regeneration cooler and regeneration blower. It shows the design calculations of a universal hinged expansion joint operating at 0.14 MPa and 593°C in a pipe of 762mm diameter. The joint contains 5 single-ply INCOLOY 800H bellows with unreinforced convolutions. Design calculations of the expansion joint have been carried out using formulae prescribed in the Expansion Joints Manufacturers Association (EJMA) standard. Since it is difficult to quantify stresses using a movement test, the EJMA calculations have been verified against finite element analysis results of the bellows.