Journal articles: '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.

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Kaminskiy, V. N., A. V. Loik, A. Yu Titchenko, E. A. Alikin, G. G. Nadareyshvili, and P. A. Shcheglov. "Application of storage catalytic converters of nitrogen oxides for reducing exhaust toxicity of tractor diesel engines." Traktory i sel hozmashiny 83, no. 11 (November 15, 2016): 3–7. http://dx.doi.org/10.17816/0321-4443-66232.

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Reduction of harmful effects of agricultural machinery on the ecosphere is an important task; its solution requires extensive use of emission reducing devices. Compliance with up-to-date legal requirements causes the cost increase of systems of diesel exhaust gases aftertreatment. This applies especially the systems that require an additional reagent feeding into exhaust system. The cost factor determines the study aim that is the creation of prototype of alternative aftertreatment system for selected engine type with the possibility of rapid adaptation to other types of the same power class. The article considers the operating principles of a storage-type system of catalytic reduction of nitrogen oxides, the design features of the system for tractor engine. An important advantage of this system is the fact that there is no need for additional reagent. The experimental studies of converter prototype as part of series-production engine were conducted on the engine test bench. In addition, the tests of samples of catalyst bricks with different types of catalytic coating were carried out. As a result of testing and selection of optimal catalytic coating, the new fuel supply system with increased performance is obtained and the converter design recommended for agricultural machinery is modified. The storage catalytic converter system allows to reduce the nitrogen oxides emissions by 40-50 %. With such efficiency of the system, its cost is noticeably lower than the cost of the system of selective catalytic reduction. The proposed design allows to adapt the storage system to engines of any power class without change in systems and control algorithms. The optimal field of application of storage systems is determined.

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Sawatmongkhon, B., A. Tsolakis, K. Theinnoi, A. P. E. York, P. J. Millington, and R. R. Rajaram. "Microkinetic modelling for selective catalytic reduction (SCR) of NOx by propane in a silver-based automotive catalytic converter." Applied Catalysis B: Environmental 111-112 (January 2012): 165–77. http://dx.doi.org/10.1016/j.apcatb.2011.09.031.

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Suresh Kumar, K., G. Balaji, P. Teja, and S. Rahul Kumar. "Experimental investigation on reducing agents for catalytic converters of CI engine." Journal of Physics: Conference Series 2054, no. 1 (October 1, 2021): 012029. http://dx.doi.org/10.1088/1742-6596/2054/1/012029.

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Abstract High level pollution and emissions arising out of ever-increasing transport vehicles are wrecking a lot of havoc on the environment globally. Stringent emission norms and regulations force the research community across the globe to develop exhaust gas after-treatment systems for effective emission control. Catalytic converters are used to reduce the emissions of hydrocarbon, nitrogen oxides, carbon monoxide and particulate matter. Selective catalytic reduction (SCR) is a system used in IC engines, in which the NOx emission is reduced by injecting a reducing agent in the presence of catalyst. Normally adblue solution is used as the reducing agent for the dissociation of NOx into nitrogen and water. However, it has many drawbacks like NH3 slip, deposit formation and incomplete conversion of NOx. In the present study investigation has been carried out in a CI engine provided with a Vanadium based catalytic converter. Three different reducing agents were used for the dissociation of NOx into nitrogen and water and their effectiveness in controlling the NOx emission has been analyzed and reported.

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Blinov, Artem, Nikolay Malastowski, and Leonid Myagkov. "Development of the model for a diesel engine catalytic converter." E3S Web of Conferences 140 (2019): 06013. http://dx.doi.org/10.1051/e3sconf/201914006013.

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One of the key issues of the modern engine development is to comply with today’s stringent emission standards. It forces the manufacturers to enhance in-engine and after treatment emission reduction technologies continuously. The selective catalytic reduction (SCR) is still the most effective technique for nitrogen oxides removal from exhaust gases of vehicles with diesel engines. Numerical modelling is widely used for SCR systems development and assessment. In this paper, a simplified one-dimensional numerical model of diesel SCR catalyst, which was implemented in Matlab, is described. The algorithm for automatic mesh generation describing real cross-section geometry of the catalyst block and the calculation procedure allowing to take into account non-uniform distribution of the gas flow parameters at the catalyst inlet are presented. Model was validated by the experimental data available in the literature. Numerical simulations for the full-scale modern SCR catalyst were carried out. The effect of the gas velocity non-uniformity at the catalyst inlet on the overall NOx reduction efficiency was evaluated.

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Solomon, S. J., T. Custer, G. Schade, A. P. Soares Dias, and J. Burrows. "Atmospheric methanol measurement using selective catalytic methanol to formaldehyde conversion." Atmospheric Chemistry and Physics Discussions 5, no. 3 (May 31, 2005): 3533–59. http://dx.doi.org/10.5194/acpd-5-3533-2005.

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Abstract. A novel atmospheric methanol measurement technique, employing selective gas-phase catalytic conversion of methanol to formaldehyde followed by detection of the formaldehyde product, has been developed and tested. The effects of temperature, gas flow rate, gas composition, reactor-bed length, and reactor-bed composition on the methanol conversion efficiency of a molybdenum-rich, iron-molybdate catalyst [Mo-Fe-O] were studied. Best results were achieved using a 1:4 mixture (w/w) of the catalyst in quartz sand. Optimal methanol to formaldehyde conversion (>95% efficiency) occurred at a catalyst housing temperature of 345°C and an estimated sample-air/catalyst contact time of <0.2 s. Potential interferences arising from conversion of methane and a number of common volatile organic compounds (VOC) to formaldehyde were found to be negligible under most atmospheric conditions and catalyst housing temperatures. Using the new technique, atmospheric measurements of methanol were made at the University of Bremen campus from 1 to 15 July 2004. Methanol mixing ratios ranged from 1 to 5 ppb with distinct maxima at night. Formaldehyde mixing ratios, obtained in conjunction with methanol by periodically bypassing the catalytic converter, ranged from 0.2 to 1.6 ppb with maxima during midday. These results suggest that selective, catalytic methanol to formaldehyde conversion, coupled with existing formaldehyde measurement instrumentation, is an inexpensive and effective means for monitoring atmospheric methanol.

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Solomon, S. J., T. Custer, G. Schade, A. P. Soares Dias, and J. Burrows. "Atmospheric methanol measurement using selective catalytic methanol to formaldehyde conversion." Atmospheric Chemistry and Physics 5, no. 10 (October 24, 2005): 2787–96. http://dx.doi.org/10.5194/acp-5-2787-2005.

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Abstract. A novel atmospheric methanol measurement technique, employing selective gas-phase catalytic conversion of methanol to formaldehyde followed by detection of the formaldehyde product, has been developed and tested. The effects of temperature, gas flow rate, gas composition, reactor-bed length, and reactor-bed composition on the methanol conversion efficiency of a molybdenum-rich, iron-molybdate catalyst [Mo-Fe-O] were studied. Best results were achieved using a 1:4 mixture (w/w) of the catalyst in quartz sand. Optimal methanol to formaldehyde conversion (>95% efficiency) occurred at a catalyst housing temperature of 345°C and an estimated sample-air/catalyst contact time of <0.2 seconds. Potential interferences arising from conversion of methane and a number of common volatile organic compounds (VOC) to formaldehyde were found to be negligible under most atmospheric conditions and catalyst housing temperatures. Using the new technique, atmospheric measurements of methanol were made at the University of Bremen campus from 1 to 15 July 2004. Methanol mixing ratios ranged from 1 to 5 ppb with distinct maxima at night. Formaldehyde mixing ratios, obtained in conjunction with methanol by periodically bypassing the catalytic converter, ranged from 0.2 to 1.6 ppb with maxima during midday. These results suggest that selective, catalytic methanol to formaldehyde conversion, coupled with existing formaldehyde measurement instrumentation, is an inexpensive and effective means for monitoring atmospheric methanol.

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Manoj Kumar, A. P., and P. Mohanan. "Effect of Physical Parameters on DeNOx Conversion in Selective Catalytic Converter Used in Diesel Vehicles." Applied Mechanics and Materials 376 (August 2013): 13–16. http://dx.doi.org/10.4028/www.scientific.net/amm.376.13.

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The Urea SCR system is a promising approach to reduce NOx in order to meet stringent limits on Euro 1V and Euro V standards. Apart from thermodynamic properties (temperature, pressure,heat and mass transfer), the cell geometry of SCR also got significant role in reduction of NOx. The current study focuses on the calculation of NOx conversion by varying the Open Frontal area of monolith, volume of monolith, cell density thereby to choose best cell geometry which will result in maximum DeNOx efficiency. It has been found that as the cell density increases the NOx conversion efficiency also increases. In the current analysis, a cell density varying from 200 CPSI to 400 CPSI is considered. One dimensional steady state and transient kinetic analysis are carried out using AVL BOOST software. The monolith volume is varied from 0.002m3 to 0.008m3 and the effects on DeNOx efficiency are discussed. The Open frontal area of SCR catalyst also been varied, and the effects on NOx conversion is studied. It has been found that as the cell density, monolith volume increases, the NOx conversion efficiency also increases, where as it decreases with increase in Open frontal area. The results are validated through experimental results obtained from the literature.

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Xiao, You Hong, Wei Zheng, Yu Shan Jin, and Xin Na Tian. "Investigation on the Simulation of Control Strategy for a SCR System." Advanced Materials Research 860-863 (December 2013): 770–73. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.770.

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In this paper, the model of SCR after-treatment system is established by the software MATLAB and the control strategy for the system is studied also. Based on Eley-rideal mechanism, four major chemical reactions including the adsorption of ammonia, desorption of ammonia, selective catalytic reduction and oxidation of adsorbed ammonia are selected to study the SCR control strategy. Based on the energy conservation law, the equation calculating the temperature of the layered model is derived. Combined with the equations of chemical reaction process, a mathematical model of SCR catalytic converter is established. To achieve a high NOXreduction efficiency of SCR system, the reasonable and efficacious control strategies for the micro-element models of SCR catalytic is simulated, which including the feedback control strategy based on the feed-forward controller and the PID control strategy.

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Miraval, Claudine, Saghi Saedlou, Romain Evrard, Pierre-Olivier Santacreu, and Johan Leseux. "Influence of Selective Catalytic Reduction (SCR) system on stainless steel durability." Rem: Revista Escola de Minas 66, no. 2 (June 2013): 153–58. http://dx.doi.org/10.1590/s0370-44672013000200003.

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Stainless steel is largely used in the car exhaust market and will be applied now for truck and off-road vehicles. In that field of application, designs are more and more complex with the integration of a catalytic converter and particle filter, consequence of more and more severe diesel depollution regulations. In particular, due to the necessity of reducing NOx emission established by Euro 5 standard (2009), Euro 6 (2014) and American Tier 4 (2014), new equipment were developed for diesel vehicles (truck as well as car). The most promising technology is called Selective Catalytic Reduction (SCR) and takes advantage of the reduction feature of ammonia (NH3) on NOx. As NH3 cannot be stored directly within the vehicle for safety reasons (toxicity & flammability of ammonia) urea in water solution was selected to initiate the reaction by means of a spraying nozzle. To get a better understanding of the involved hot corrosion mechanisms and afterward to improve material selection, a dedicated laboratory test was developed at Isbergues Research Center. The simulated test consists of spraying urea solution on cyclic heated stainless steel in a range from 200ºC to 600ºC. We evidenced a nitriding mechanism due to the urea decomposition on the surface of stainless steel at high temperature, and also the very different behaviours between austenitic and ferritic grades. The last one, in particular K41X (1.4509-441) and K33X (1.4513-molybdenum stabilized ferritic) grades show the best performance in particular when compared to the standard 304 austenitic grade. The paper will review the test set-up, the result obtained and will discuss the stainless steel grade selection for the SCR application.

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Faghihi, Ehsan Majd, and Amir H. Shamekhi. "Development of a neural network model for selective catalytic reduction (SCR) catalytic converter and ammonia dosing optimization using multi objective genetic algorithm." Chemical Engineering Journal 165, no. 2 (December 1, 2010): 508–16. http://dx.doi.org/10.1016/j.cej.2010.09.055.

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Shepelev, V., A. Gritsenko, and G. Salimonenko. "Control of hydrocarbon emissions when changing the technical condition of the exhaust system of modern cars." FME Transactions 49, no. 3 (2021): 749–55. http://dx.doi.org/10.5937/fme2103749s.

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The most applicable ICE monitoring method is selective control followed by individual corrections for the current technical condition. The combination of a gas analyzer installed individually in each collector, a motor tester, and a loader which provides test modes makes it possible to recognize failures of exhaust and other systems with high accuracy and to assign an individual corrective action to ensure specified environmental and economic parameters. We developed a generalized mathematical model of changes in the composition of exhaust gases depending on changes in the resistance of the catalytic converter, the spark gap of the spark plug, and the capacity of the electromagnetic nozzle.

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Papadopoulos, Christos, Marios Kourtelesis, Anastasia Maria Moschovi, Konstantinos Miltiadis Sakkas, and Iakovos Yakoumis. "Selected Techniques for Cutting SOx Emissions in Maritime Industry." Technologies 10, no. 5 (August 30, 2022): 99. http://dx.doi.org/10.3390/technologies10050099.

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Burning fuels with high sulfur content leads to SOx emissions, especially SO2, which leads to various environmental and health problems. The maritime sector is responsible for 13% of the global anthropogenic emissions of SO2. Thus, the International Maritime Organization (IMO) has issued a protocol, known as MARPOL Annex VI, which aims to further limit SO2 emissions derived from ships along with NOx, particulate matter and volatile organic compound emissions. This has led ship owners and operators to choose between more expensive fuels with low sulfur content or to apply a DeSOx solution, which still allows them to use the cheapest heavy fuel oil. The current work reviews the state-of-the-art DeSOx solutions both for the maritime and land-based sector. Next, it proposes an alternative cheaper and environmentally friendly DeSOx solution based on the selective reduction of SO2 to elemental sulfur by utilizing a catalytic converter based on metal oxides, similar to the ones used in the automotive industry. Finally, it reviews the most promising metal oxide catalysts reported in the literature for the selective reduction of SO2 towards elemental sulfur.

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Limjuco, Lawrence A., and Francis Kirby Burnea. "Evaluation of dithiadiamide-based molecular ion imprinted polymer (MIIP) for selective recovery of platinum from acid-digested spent automobile catalytic converter (ACC) solution." MRS Communications 12, no. 2 (February 8, 2022): 175–82. http://dx.doi.org/10.1557/s43579-022-00158-9.

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Yang, Xiaorui, Jing Zhao, Jinhua Liang, and Jianliang Zhu. "Efficient and Selective Catalytic Conversion of Hemicellulose in Rice Straw by Metal Catalyst under Mild Conditions." Sustainability 12, no. 24 (December 18, 2020): 10601. http://dx.doi.org/10.3390/su122410601.

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Rice straw is an abundant material with the potential to be converted into a sustainable energy resource. Transition-metal catalysis activated the C–O bond in the hemicellulose of raw rice straw, cleaving it to form monosaccharides. The mechanism of rice straw catalytic conversion had a synergistic effect due to in situ acid catalysis and metal catalysis. The conditions for the hydrogenation of hemicellulose from rice straw were optimized: catalyst to rice straw solid/solid ratio of 3:10, stirring speed of 600 r/min, temperature of 160 °C, time of 3 h, solid/liquid ratio of 1:15, and H2 gas pressure of 1.5 MPa. An excellent hemicellulose conversion of 97.3% with the yields of xylose and arabinose at 53.0% and 17.3%, respectively, were obtained. The results from FTIR and SEM experiments also confirmed the destruction of the rigidity and reticulate structure of rice straw after the catalytic reaction.

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MODAN, Ecaterina–Magdalena, and Adriana-Gabriela PLAIASU. "An overview on metal-oxide catalytic converters." University of Pitesti. Scientific Bulletin - Automotive Series 30, no. 1 (November 1, 2020): 1–7. http://dx.doi.org/10.26825/bup.ar.2020.002.

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Diesel vehicles produce exhaust gases that include nitrogen oxides (NOx), carbon monoxide and hydrocarbons.A major environmental problem is the elimination of nitrogen oxides, as they are major air pollutants. Global restrictions on NOx emissions from fuel combustion have been imposed. Efforts have been made to develop catalysts for the selective catalytic reduction of NOx. In this paper is presented the types of catalytic converters used nowadays for dissipate emissions and selective catalytic reduction.

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Al-Hunaiti, Afnan, Batool Abu-Radaha, Darren Wraith, and Timo Repo. "Catalytic behaviour of the Cu(i)/L/TEMPO system for aerobic oxidation of alcohols – a kinetic and predictive model." RSC Advances 12, no. 13 (2022): 7864–71. http://dx.doi.org/10.1039/d1ra09359b.

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Here, we disclose a new copper(i)-Schiff base complex series for selective oxidation of primary alcohols to aldehydes under benign conditions. Both benzylic and aliphatic alcohols were converted to aldehydes selectively with 99% yield.

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Fedotov, A. S., M. V. Tsodikov, and A. B. Yaroslavtsev. "Hydrogen Production in Catalytic Membrane Reactors Based on Porous Ceramic Converters." Processes 10, no. 10 (October 12, 2022): 2060. http://dx.doi.org/10.3390/pr10102060.

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This article presents the results of the development of membrane-catalytic methods for obtaining purified hydrogen of various degrees of purity required for feeding high-, medium-, and low-temperature fuel cells. In order to conduct this, porous ceramic catalytic converters were obtained using self-propagating high-temperature synthesis. These converters are suitable for high-speed processes for producing synthesis gas with different carbon monoxide content (0.08–0.1 vol. %), which can be used to feed fuel cells of various types. Using a hybrid catalytic membrane reactor, in which the stage of catalytic conversion of organic substrates was combined with the stage of selective extraction of ultrapure hydrogen (content of H2 was not less than 99.9999 vol. %) from the reaction zone, combined carbon dioxide and steam reforming of organic substrates of various origins were carried out. The result of the work was the creation of a prototype of a small-sized electric generator plant in which a catalytic membrane reactor was combined with a solid-oxide fuel cell.

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Smolders, Simon, Jannick Jacobsen, Norbert Stock, and Dirk De Vos. "Selective catalytic reduction of NO by cerium-based metal–organic frameworks." Catalysis Science & Technology 10, no. 2 (2020): 337–41. http://dx.doi.org/10.1039/c9cy02029b.

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Antunes, Margarida M., Andreia F. Silva, Carolina D. Bernardino, Auguste Fernandes, Filipa Ribeiro, and Anabela A. Valente. "Catalytic Transfer Hydrogenation and Acid Reactions of Furfural and 5-(Hydroxymethyl)furfural over Hf-TUD-1 Type Catalysts." Molecules 26, no. 23 (November 27, 2021): 7203. http://dx.doi.org/10.3390/molecules26237203.

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Heterogeneous catalysis, which has served well the petrochemical industry, may valuably contribute towards a bio-based economy by sustainably enabling selective reactions to renewable chemicals. Carbohydrate-containing matter may be obtained from various widespread sources and selectively converted to furanic platform chemicals: furfural (Fur) and 5-(hydroxymethyl)furfural (Hmf). Valuable bioproducts may be obtained from these aldehydes via catalytic transfer hydrogenation (CTH) using alcohols as H-donors under relatively moderate reaction conditions. Hafnium-containing TUD-1 type catalysts were the first of ordered mesoporous silicates explored for the conversion of Fur and Hmf via CTH/alcohol strategies. The materials promoted CTH and acid reactions leading to the furanic ethers. The bioproducts spectrum was broader for the reaction of Fur than of Hmf. A Fur reaction mechanism based on literature data was discussed and supported by kinetic modelling. The influence of the Hf loading and reaction conditions (catalyst load, type of alcohol H-donor, temperature, initial substrate concentration) on the reaction kinetics was studied. The reaction conditions were optimized to maximize the yields of 2-(alkoxymethyl)furan ethers formed from Fur; up to 63% yield was reached at 88% Fur conversion, 4 h/150 °C, using Hf-TUD-1(75), which was a stable catalyst. The Hf-TUD-1(x) catalysts promoted the selective conversion of Hmf to bis(2-alkoxymethyl)furan; e.g., 96% selectivity at 98% Hmf conversion, 3 h/170 °C for Hf-TUD-1(50).

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Jantan, Khairil A., Chuek Yee Kwok, Kuang Wen Chan, Luciano Marchiò, Andrew J. P. White, Paola Deplano, Angela Serpe, and James D. E. T. Wilton-Ely. "From recovered metal waste to high-performance palladium catalysts." Green Chemistry 19, no. 24 (2017): 5846–53. http://dx.doi.org/10.1039/c7gc02678a.

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Motroniuk, I., R. Stöber, and G. Fischerauer. "State determination of catalytic converters based on an ultra-wideband communication system." Journal of Sensors and Sensor Systems 4, no. 2 (August 10, 2015): 255–62. http://dx.doi.org/10.5194/jsss-4-255-2015.

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Abstract. A novel microwave-based approach for monitoring the state of aftertreatment systems such as diesel particulate filters (DPFs), three-way catalytic converters (TWCs), and selective catalytic reduction (SCR) catalysts is proposed. The volume inside the metallic housing of the DPF, TWC, or SCR is considered as a wireless communication channel between two terminals of a communication system. It is shown that, depending on the transmission channel characteristics, the properties of the catalyst, such as the catalyst state, can be inferred. This is done by means of an ultra-wideband (UWB) measurement and the subsequent evaluation and processing of the waveform in the time and frequency domains.

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Wang, Hongliang, Libing Zhang, Tiansheng Deng, Hao Ruan, Xianglin Hou, John R. Cort, and Bin Yang. "ZnCl2 induced catalytic conversion of softwood lignin to aromatics and hydrocarbons." Green Chemistry 18, no. 9 (2016): 2802–10. http://dx.doi.org/10.1039/c5gc02967h.

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Stojanac, Nada, and Zdenek Valenta. "Total synthesis of d,l-quassin." Canadian Journal of Chemistry 69, no. 5 (May 1, 1991): 853–55. http://dx.doi.org/10.1139/v91-125.

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The completion of the total synthesis of d,l-quassin 1 is described. Key steps are a facile intramolecular acylation of a protected cyanohydrin carbanion (4 → 5), a selective deprotonation with trioctyl methyl ammonium hydroxide leading to the removal of HCN from 8, and the unusual sequence 5 → 12 in which the ring C enol ether of 5 is converted selectively into ring C diosphenol of 12. Key words: quassin, synthesis, selective base, diosphenols, acylation.

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Wang, Tianmiao, Sibao Liu, Masazumi Tamura, Yoshinao Nakagawa, Norihito Hiyoshi, and Keiichi Tomishige. "One-pot catalytic selective synthesis of 1,4-butanediol from 1,4-anhydroerythritol and hydrogen." Green Chemistry 20, no. 11 (2018): 2547–57. http://dx.doi.org/10.1039/c8gc00574e.

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Gritsenko, Alexander Vladimirovich, Konstantin Vyacheslavovich Glemba, and Grigoriy Nikolaevich Salimonenko. "Engine diagnostics by selective gas analysis of exhaust gases." Transport of the Urals, no. 2 (2022): 84–91. http://dx.doi.org/10.20291/1815-9400-2022-2-84-91.

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In the paper the method of individual gas analysis of vehicles with using promising means, including an oscilloscope and an electronically controlled load device, is considered. During the research, the lower and upper limits of the variation of the variable toxicity parameters for modern gasoline cars, regardless of the number of cylinders, are theoretically justified. This generalized theoretical model can be used by machine-building plants and car service enterprises to assess the current state of catalytic converters, spark plugs, electromagnetic injectors, as well as forecasting the resource for the upcoming use cycles.

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Chan-Thaw, Carine, Aditya Savara, and Alberto Villa. "Selective Benzyl Alcohol Oxidation over Pd Catalysts." Catalysts 8, no. 10 (September 30, 2018): 431. http://dx.doi.org/10.3390/catal8100431.

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In the last decades, the selective liquid phase oxidation of alcohols to the corresponding carbonyl compounds has been a subject of growing interest. Research has focused on green methods that use “clean” oxidants such as O2 in combination with supported metal nanoparticles as the catalyst. Among the alcohols, benzyl alcohol is one of the most studied substrates. Indeed, benzyl alcohol can be converted to benzaldehyde, largely for use in the pharmaceutical and agricultural industries. This conversion serves as model reaction in testing new potential catalysts, that can then be applied to other systems. Pd based catalysts have been extensively studied as active catalytic metals for alcohol oxidation for their high activity and selectivity to the corresponding aldehyde. Several catalytic materials obtained by careful control of the morphology of Pd nanoparticles, (including bimetallic systems) and by tuning the support properties have been developed. Moreover, reaction conditions, including solvent, temperature, pressure and alcohol concentration have been investigated to tune the selectivity to the desired products. Different reaction mechanisms and microkinetic models have been proposed. The aim of this review is to provide a critical description of the recent advances on Pd catalyzed benzyl alcohol oxidation.

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Popsavin, Velimir, Sanja Grabez, Ivana Krstic, Mirjana Popsavin, and Dejan Djokovic. "A formal synthesis of (+)-muricatacin from D-xylose." Journal of the Serbian Chemical Society 68, no. 11 (2003): 795–804. http://dx.doi.org/10.2298/jsc0311795p.

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A multistep route towards the aldehydo-lactone 19, the final chiral precursor in a new stereospecific synthesis of (+)-muricatacin, has been developed starting from D-xylose. The key step of the synthesis involves an E-selective Wittig olefination of the lactol 6 with methoxycarbonylmethylidene triphenylphosphorane, followed by successive catalytic reduction and ?-lactonisation processes. Subsequent selective functional groups interconver- sions furnished the key six-carbon intermediate 19, which can be converted into the (+)-muricatacin via a three-step sequence already described in the chemical literature.

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Assal, Mohamed E., Mufsir Kuniyil, Mujeeb Khan, Mohammed Rafi Shaik, Abdulrahman Al-Warthan, Mohammed Rafiq H. Siddiqui, Joselito P. Labis, and Syed Farooq Adil. "Comparative Catalytic Evaluation of Nano-ZrOx Promoted Manganese Catalysts: Kinetic Study and the Effect of Dopant on the Aerobic Oxidation of Secondary Alcohols." Advances in Materials Science and Engineering 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/3958319.

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This work reports the zirconia (ZrOx) nanoparticles doped MnCO3 catalysts prepared by facile and simple coprecipitation technique and the synthesis of zirconia-manganese carbonate [X% ZrOx–MnCO3] (where X% = 0–7%) catalyst which upon calcination at 400°C is converted to zirconia-manganese dioxide [1% ZrOx–MnO2] and when calcined at 500°C is converted to zirconia-manganic trioxide [1% ZrOx–Mn2O3]. A comparative catalytic study was performed to investigate the catalytic efficiency between carbonate and oxides for the selective oxidation of 1-phenylethanol by using molecular O2 as a clean oxidant. The influence of several parameters such as w/w% of ZrOx, reaction time, calcination temperature, catalyst amount, and reaction temperature has been thoroughly examined using oxidation of 1-phenylethanol as a model substrate. The 1% ZrOx–MnCO3 precalcined at 300°C exhibited the best catalytic efficiency. It was found that ZrOx nanoparticles also play an essential role in enhancing the effectiveness of the catalytic system for the aerobic oxidation of alcohols. Furthermore, the physical and chemical properties of synthesized catalysts were evaluated by microscopic and spectroscopic techniques. An extremely high specific activity of 40 mmol·g−1·h−1 with a 100% conversion of oxidation product and selectivity of >99% was achieved within extremely short reaction time (6 min).

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Long, Jingxuan, Wenfeng Zhao, Yufei Xu, Hu Li, and Song Yang. "Carbonate-Catalyzed Room-Temperature Selective Reduction of Biomass-Derived 5-Hydroxymethylfurfural into 2,5-Bis(hydroxymethyl)furan." Catalysts 8, no. 12 (December 7, 2018): 633. http://dx.doi.org/10.3390/catal8120633.

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Catalytic reduction of 5-hydroxymethylfurfural (HMF), deemed as one of the key bio-based platform compounds, is a very promising pathway for the upgrading of biomass to biofuels and value-added chemicals. Conventional hydrogenation of HMF is mainly conducted over precious metal catalysts with high-pressure hydrogen. Here, a highly active, sustainable, and facile catalytic system composed of K2CO3, Ph2SiH2, and bio-based solvent 2-methyltetrahydrofuran (MTHF) was developed to be efficient for the reduction of HMF. At a low temperature of 25 °C, HMF could be completely converted to 2,5-bis(hydroxymethyl)furan (BHMF) in a good yield of 94% after 2 h. Moreover, a plausible reaction mechanism was speculated, where siloxane in situ formed via hydrosilylation was found to be the key species responsible for the high reactivity.

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Chihara, Teiji, Tamie Wakabayasi, Kazuo Taya, and Haruo Ogawa. "Selective reduction of less reactive carbonyl groups in the presence of diborane and sodium bisulfite on silica gel." Canadian Journal of Chemistry 68, no. 5 (May 1, 1990): 720–24. http://dx.doi.org/10.1139/v90-112.

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The less reactive carbonyl group of a mixture of reducible groups of carbonyl compounds was preferentially reduced with diborane on silica gel by first forming an adduct of the more reactive carbonyl group with sodium bisulfite. For example, 4-acetylbenzaldehyde could be converted to 4-(1-hydroxylethyl)benzaldehyde in 93% selectivity; in a mixture of 4-phenyl-acetophenone and 4-phenylbenzaldehyde, biphenylethanol was preferentially formed in 95% yield with 16% yield of 4-phenylbenzyl alcohol. Silica gel and sodium bisulfite were essential for this selective reaction. Aliphatic and aromatic aldehydes and unhindered cyclohexanones could be selectively protected by this method. Keywords: sodium bisulfite, silica gel, carbonyl compound, selective reduction, diborane.

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Mitina, E. G., N. S. Filimonov, R. V. Shaﬁgulin, A. V. Bulanova, I. V. Shishkovsky, and Y. G. Morozov. "The study of catalytic activity ofcopper nanoparticles in the reaction of hydrogenation of hexyne-1." Vestnik of Samara University. Natural Science Series 21, no. 10 (May 15, 2017): 151–59. http://dx.doi.org/10.18287/2541-7525-2015-21-10-151-159.

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The process of hydrogenation of unsaturated hydrocarbons is one of the main processes of the petrochemical industry. Unsaturated hydrocarbons are practi- cally inseparable from alkanes, which have the same mass, and to obtain high--quality gasoline unsaturated hydrocarbons are to be eliminated. Furthermore, acetylenic hydrocarbons must be removed from an oleﬁnic feedstock, which is intended for the production of polymers. These problems can be solved by using catalysts with diﬀerent selectivities. The article studied the copper nanoparti- cles in the hydrogenation reaction hexyne-1. The nanoparticles were obtained by means of levitation blasting and mixed with inerton. Analysis of the reaction mixture was performed by means of gas chromatography. We calculated the rate constants at diﬀerent temperatures and measured the activation energy of the reaction. It is shown that the ﬁrst hexyne-1 is converted to hexene-1, followed by hexane. Thus, the catalyst shows the analyzed selective properties, which enables selection of the conditions for obtaining the priority of a particular product.

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Qiu, Tao, Xu Chu Li, Jing Peng, Yan Lei, and Guang Zhao Yue. "Study on Development of a Urea-SCR System of Diesel Engine." Applied Mechanics and Materials 541-542 (March 2014): 747–51. http://dx.doi.org/10.4028/www.scientific.net/amm.541-542.747.

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Aimed at the diesel engine, a selective catalytic reduction (SCR) system was developed. In this system, the urea pump is integrated with a urea tank, air and urea mix in the injector, catalyst convertor is based on vanadium. Combining with a self-developed control unit, the urea-SCR system was tested on the engine bench. The ESC experiment results indicate that the NOx emission can be reduced effectively which meets the China stage IV regulation.

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Medvedev, Gennady V., and Mikhail Y. Khramov. "THE EFFECT OF MARINE POWER PLANTS EXHAUST GASES TEMPERATURE ON THE QUALITY OF THEIR CLEANING USING THE CATALYTIC NEUTRALIZATION METHOD." Russian Journal of Water Transport, no. 62 (March 10, 2020): 167–74. http://dx.doi.org/10.37890/jwt.vi62.47.

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The use of catalytic neutralization for the purification of harmful emissions from ship power plants can significantly reduce the negative impact of exhaust gases on all environmental objects. The attractiveness of the proposed method lies in the possibility of selecting the appropriate composition of the catalytic material depending on the required degree of purification.The functional properties of catalytic materials are largely determined by the qualitative and quantitative composition of the material used, as well as the conditions of its operation - the temperature regime.In order to determine the acceptable composition of the catalytic converter material, we made an analyses of materials of various compositions. The optimum degree of purification was achieved on materials containing valuable components (rhodium, iridium, palladium). However, the issue of reducing the treatment system cost is important. So, the possibility of replacing such metals with ore grindings (bastnesite, loparite) has been studied in the paper.

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Müller, Tobias, Kristina Djanashvili, Joop A. Peters, Isabel W. C. E. Arends, and Ulf Hanefeld. "Tetrahedral boronates as basic catalysts in the aldol reaction." Zeitschrift für Naturforschung B 70, no. 8 (August 1, 2015): 587–95. http://dx.doi.org/10.1515/znb-2015-0029.

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Abstractβ-Hydroxyketones are versatile building blocks in organic synthesis, which can be conveniently synthesized from ketones and aldehydes by aldol reactions. Unfortunately, these reactions often suffer from dehydration of the initially formed β-hydroxyketones. Previously, tetrahedral 3,5-difluorophenylborate was shown to be an efficient and selective catalyst for this reaction. The present investigation concerns the catalytic performance of phenyl borates with different substitution patterns in the aldol reaction. It appears that the dehydration reaction can be suppressed by selecting substituents and substituent positions with reduced electron withdrawing effects on the borate function. Optimal suppression of the dehydration of β-hydroxyketones was obtained for compounds corresponding to phenylboronic acids with a pKa > 7. The reactions between benzaldehyde and butanone or 3-pentanone did not show diastereoselectivity, which suggests that the catalysts merely act as bases rather than as templates for the transition state of the aldol reaction. Sterically more demanding ketones were not converted.

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Ighachane, Hana, Brahim Boualy, Mustapha Ait Ali, My H. Sedra, Larbi El Firdoussi, and Hassan Bihi Lazrek. "Catalytic Synthesis and Antifungal Activity of New Polychlorinated Natural Terpenes." Advances in Materials Science and Engineering 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/2784303.

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Various unsaturated natural terpenes were selectively converted to the corresponding polychlorinated products in good yields using iron acetylacetonate in combination with nucleophilic cocatalyst. The synthesized compounds were evaluated for their in vitro antifungal activity. The antifungal bioassays showed that 2c and 2d possessed significant antifungal activity against Fusarium oxysporum f. sp. albedinis (Foa), Fusarium oxysporum f. sp. canariensis (Foc), and Verticillium dahliae (Vd).

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Li, Junhui, Kai Tong, Zhiwen Xi, Ying Yuan, Zhonghua Hu, and Zhirong Zhu. "Highly-efficient conversion of methanol to p-xylene over shape-selective Mg–Zn–Si-HZSM-5 catalyst with fine modification of pore-opening and acidic properties." Catalysis Science & Technology 6, no. 13 (2016): 4802–13. http://dx.doi.org/10.1039/c5cy01979f.

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Shaikh, Isak Rajjak, Rafique Ahmed Shaikh, Alamgir Abdulla Shaikh, Javeed Ahmad War, Shankar Poshetti Hangirgekar, Ahmad Lalahmad Shaikh, Parveen Rajjak Shaikh, and Rafik Rajjak Shaikh. "H-ZSM-5 Zeolite Synthesis by Sourcing Silica from the Wheat Husk Ash: Characterization and Application as a Versatile Heterogeneous Catalyst in Organic Transformations including Some Multicomponent Reactions." Journal of Catalysts 2015 (January 29, 2015): 1–14. http://dx.doi.org/10.1155/2015/805714.

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ZSM-5 zeolite was synthesized by sourcing silica from wheat husk ash and was converted into its protonated form following careful, conventionally accepted ion-exchange method and calcinations. The H-ZSM-5 zeolite (Si/Al ratio = 30) prepared was appropriately characterized by XRD, FT-IR, SEM, TEM, TG-DTA, CV, and so forth, and evaluated as recyclable catalyst in selective organic transformations including three- and four-component reactions. The catalytic activity of the zeolite sample supposedly relates to increased density of the accessible acid sites.

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Gomes, Ana C., Patrícia Neves, Luís Cunha-Silva, Anabela A. Valente, Isabel S. Gonçalves, and Martyn Pillinger. "Oxidomolybdenum complexes for acid catalysis using alcohols as solvents and reactants." Catalysis Science & Technology 6, no. 13 (2016): 5207–18. http://dx.doi.org/10.1039/c5cy02052b.

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With ethanol as solvent and reactant, a molybdenum (pre)catalyst promotes selective acid-catalysed reactions. Depending on the conditions, the Mo^VIcomplex is converted to Mo^VIoxidoalkoxido, Mo^Voxido-bridged dinuclear, and Mo^VIoctanuclear complexes.

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Maumela, Mulisa, Sanette Marx, and Reinout Meijboom. "Heterogeneous Ru Catalysts as the Emerging Potential Superior Catalysts in the Selective Hydrogenation of Bio-Derived Levulinic Acid to γ-Valerolactone: Effect of Particle Size, Solvent, and Support on Activity, Stability, and Selectivity." Catalysts 11, no. 2 (February 23, 2021): 292. http://dx.doi.org/10.3390/catal11020292.

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Catalytic hydrogenation of a biomass-derived molecule, levulinic acid (LA), to γ-valerolactone (GVL) has been getting much attention from researchers across the globe recently. This is because GVL has been identified as one of the potential molecules for replacing fossil fuels. For instance, GVL can be catalytically converted into liquid alkenes in the molecular weight range close to that found in transportation fuels via a process that does not require an external hydrogen source. Noble and non-noble metals have been used as catalysts for the selective hydrogenation of LA to GVL. Of these, Ru has been reported to be the most active metal for this reaction. The type of metal supports and solvents has been proved to affect the activity, selectivity, and yields of GVL. Water has been identified as a potential, effective “green” solvent for the hydrogenation of LA to GVL. The use of different sources of H2 other than molecular hydrogen (such as formic acid) has also been explored. In a few instances, the product, GVL, is hydrogenated further to other useful products such as 1,4-pentanediol (PD) and methyl tetrahydrofuran (MTHF). This review selectively focuses on the potential of immobilized Ru catalysts as a potential superior catalyst for selective hydrogenation of LA to GVL.

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Sakkosit, Sirichai, Somsak Damronglerd, and Chawalit Ngamcharussrivichai. "Degradation of Poly(methyl methacrylate) over Zeolites in a Batch Reactor." Advanced Materials Research 622-623 (December 2012): 1173–77. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.1173.

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Thermal degradation is an attractive way to eliminate poly(methyl methacrylate) (PMMA) waste to which high temperatures are applied in the absence of oxygen. However, the process is not selective, resulting in a complex composition of products. Catalytic degradation over zeolites provides an effective route to selectively convert PMMA into desired products at lower temperatures, since zeolites have high acidity and shape-selectivity. In this work, the degradation of PMMA over various zeolites, including ZSM-5, BETA and USY, has been investigated in a batch reactor as a feasibility study to recover methyl methacrylate (MMA) as well as other valuable chemicals. The results showed that PMMA can be completely degraded at 300 oC and MMA was recovered as light oil. With increasing the degradation time, PMMA was converted over zeolites into more gaseous and light oil products, while the thermal degradation gave higher portion of heavy oil. From GC-MS analysis of light oil, MMA was found as the main product, co-existing with methyl 2-methyl propionate and methyl 2-methyl butyrate both of which can be used as synthetic fragrance.

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Journal articles on the topic 'Selective catalytic converter'

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