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Book Selective Catalytic Reduction of NOx

Download or read book Selective Catalytic Reduction of NOx written by Oliver Kröcher and published by MDPI. This book was released on 2018-12-14 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Selective Catalytic Reduction of NOx" that was published in Catalysts

Book Selective Catalytic Reduction of NOx by NH3 NH3 SCR in Small Pore Cu exchanged Chabazite CHA Catalysts

Download or read book Selective Catalytic Reduction of NOx by NH3 NH3 SCR in Small Pore Cu exchanged Chabazite CHA Catalysts written by Di Wang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen oxides, NOx (NO+NO2), are considered significant air pollutants. Selective catalytic reduction of NOx with NH3 (NH3-SCR) is a leading technology candidate for NOx emissions control for diesel engine vehicles. Recently, the Cu-exchanged chabazite framework type zeolite with small pores, such as SAPO-34 and SSZ-13, has received a great deal of attention due to exceptional hydrothermal durability and enhanced SCR activity. I have carried out a systematic study over both Cu-SAPO-34 and Cu-SSZ-13 catalysts to elucidate the reaction mechanisms, acid properties, Cu structures, active centers and deactivation modes. First, the intrinsic mechanism of the SCR reaction over a Cu-exchanged SAPO-34 catalyst at low temperature was studied by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), coupled with a mass spectrometer to measure inlet and outlet gas concentrations. The evolution of the surface intermediates, as well as the reactivity of NH3 with surface NOx species and NOx with surface NH3 species, was evaluated. Second, a series of SAPO-34 catalysts with various Cu loadings (ranging 0.7-3.0 wt%) was prepared by a solid state ion exchange method (SSIE). The acid properties as well as the Cu structures were characterized by XRD, NH3-TPD, UV-vis, DRIFTS and H2-TPR. Third, a SSIE method was developed to synthesize Cu-SSZ-13 catalysts with excellent NH3-SCR performance and durable hydrothermal stability. After the SSIE process, the SSZ framework structure and surface area was maintained. DRIFTS and NH3-TPD experiments provide evidence that Cu ions were successfully exchanged with Brønsted acid protons in the pores. Fourth, the hydrothermal stability of Cu-SAPO-34 and Cu-SSZ-13 was studied. Their different evolutions of zeolite framework, acidity and Cu structure during the hydrothermal aging were probed by XRD, DRIFTS and NH3-TPD. The results suggest that Cu-SAPO-34 is more resistant to hydrothermal aging in comparison to Cu-SSZ-13. Last, the SO2 poisoning effect over Cu-SAPO-34 catalyst was investigated by using in-situ DRIFTS combined with temperature programmed desorption (TPD) experiments. It was found that the low temperature deactivation mechanism involved the formation of ammonium sulfate species as well as the competitive adsorption SO2 with NOx.

Book DOPING OF CeO2 IN V2O5 TiO2 CATALYST FOR LOW TEMPERATURE SELECTIVE CATALYTIC REDUCTION OF NITROGEN OXIDE BY AMMONIA

Download or read book DOPING OF CeO2 IN V2O5 TiO2 CATALYST FOR LOW TEMPERATURE SELECTIVE CATALYTIC REDUCTION OF NITROGEN OXIDE BY AMMONIA written by Warawut Waiwasa and published by . This book was released on 2014 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research investigated the selective catalytic reduction of NO by NH3 over V2O5-CeO2/TiO2 catalyst at low temperature. Formation of nitrogen oxide from the ammonia oxidation reaction and SCR reaction was also investigated. Titanium dioxide support was prepared by a sol-gel method. Then vanadium and cerium were deposited via an incipient wetness impregnation method. The amounts of vanadium and cerium in the catalyst ranged from 1 to 7%wt and 5 to 30%wt, respectively. The catalysts were characterized by N2 physisorption, ICP-OES, XRD and NH3-TPD techniques. The testing of SCR activity of the catalyst was carried out in a tubular reactor at a temperature in the range of 120-450oC. From the result, the catalyst containing 5 %wt. V2O5, 30 %wt. CeO2 showed superior SCR activity at low temperature and reached the highest activity at 250oC. The addition of CeO2 increased the specific surface area and the total acid site of catalyst, resulting in high catalytic activity. The extent of ammonia oxidation increased as the reaction temperature and the vanadium content in catalysts increased. Addition of cerium to catalyst inhibited ammonia oxidation reaction and retained the SCR activity at high temperature. Furthermore, the addition of cerium oxide to the V2O5-TiO2 catalyst yielded SCR catalysts an excellent resist to water vapor and sulfur dioxide under our test conditions.

Book Low Temperature NH3 Storage Isothermal Desorption Reactive Consumption and Thermal Release from Cu SSZ 13 and V2O5 WO3 TiO2 Selective Catalytic Reduction Catalysts

Download or read book Low Temperature NH3 Storage Isothermal Desorption Reactive Consumption and Thermal Release from Cu SSZ 13 and V2O5 WO3 TiO2 Selective Catalytic Reduction Catalysts written by Nathan Ottinger and published by . This book was released on 2019 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Development and Characterization of Mixed Oxide Catalysts for the Selective Catlytic Reduction of Nitric Oxide from Stationary Sources Using Amonnia

Download or read book Development and Characterization of Mixed Oxide Catalysts for the Selective Catlytic Reduction of Nitric Oxide from Stationary Sources Using Amonnia written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Seven first row transition metals were deposited on various commercial TiO2, SiO2, and Al2 O3 supports to create mono- and bimetallic catalysts that were compared in the selective catalytic reduction of nitric oxide using ammonia at low temperatures ranging from 373-523 K. The catalyst with the highest activity both in the absence and presence of water in the feed was 20 wt.% Mn/Hombikat TiO2 synthesized from a nitrate precursor and calcined below 673 K. Under those conditions, it was capable of achieving 100% NO conversion at 393 K. Numerous surface characterization techniques were used to identify the surface properties that result in highly active and selective low temperature SCR catalysts. The deposition of manganese as MnO2, the ease of reducibility of the metal oxide, and the symmetric deformation of ammonia coordinated to Lewis acid sites at 1167 cm−1, were all found to be important for good catalytic performance. No synergistic effects were observed from combinations of the three most active transition metals. However, MnO x -NiO/TiO2 had an extended lifetime relative to MnO x /TiO2 in feeds containing SO2 . The extensive data collected from in-situ FTIR experiments in the presence of NO and NH 3 were used to propose a reaction mechanism for MnO x /TiO2 that begins with the coordination of NH3 over Mn4 species and proceeds through the formation of bridged nitrates. A combination of potentiometric titrations and UV/Vis spectroscopy were used to quantify the reduction of V5 to V4 after the addition of oxalic acid as the solution is aged. After approximately four hours, the aging vanadium oxalate solution reaches steady state, and the final distribution of the vanadium present is 89% V+4 and 11% V+5 . TiO2 supported monolayer catalysts synthesized from the aged (V+4) vanadium oxalate solution consistently outperformed catalysts made from freshly prepared (V+5) vanadium oxalate solutions. Surface characterization revealed that surface acid sites increase in strength and vanadia reduces more easily in catalysts synthesized from aged vanadium oxalate solutions, which enhances reaction mechanism depends upon acid sites and redox operation.

Book Selective Catalytic Reduction SCR of Nitric Oxide NO with Ammonia Over Vanadia based and Pillared Interlayer Clay based Catalysts

Download or read book Selective Catalytic Reduction SCR of Nitric Oxide NO with Ammonia Over Vanadia based and Pillared Interlayer Clay based Catalysts written by Hyuk Jin Oh and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The selective catalytic reduction (SCR) of nitric oxide (NO) with ammonia over vanadia-based (V2O5-WO3/TiO2) and pillared interlayer clay-based (V2O5/Ti-PILC) monolithic honeycomb catalysts using a laboratory laminar-flow reactor was investigated. The experiments used a number of gas compositions to simulate different combustion gases. A Fourier transform infrared (FTIR) spectrometer was used to determine the concentrations of the product species. The major products were nitric oxide (NO), ammonia (NH3), nitrous oxide (N2O), and nitrogen dioxide (NO2). The aim was to delineate the effect of various parameters including reaction temperature, oxygen concentration, NH3-to-NO ratio, space velocity, heating area, catalyst arrangement, and vanadium coating on the removal of nitric oxide. The investigation showed that the change of the parameters significantly affected the removals of NO and NH3 species, the residual NH3 concentration (or NH3 slip), the temperature of the maximum NO reduction, and the temperature of complete NH3 conversion. The reaction temperature was increased from the ambient temperature (25°C) to 450°C. For both catalysts, high NO and NH3 removals were obtained in the presence of a small amount of oxygen, but no significant influence was observed from 0.1 to 3.0% O2. An increase in NH3-to-NO ratio increased NO reduction but decreased NH3 conversions. For V2O5-WO3/TiO2, the decrease of space velocity increased NO and NH3 removals and broadened the active temperature window (based on NO> 88% and NH3> 87%) about 50°C. An increase in heating area decreased the reaction temperature of the maximum NO reduction from 350 to 300 ʻC, and caused the active reaction temperature window (between 250 and 400 ʻC) to shift toward 50 ʻC lower reaction temperatures (between 200 and 350°C). The change of catalyst arrangements resulted slight improvement for NO and NH3 removals, therefore, the change might contribute to more gas removals. The catalyst with extra vanadium coating showed higher NO reductions and NH3 conversions than the catalyst without the extra vanadium coating.

Book Experimental and Kinetic Modeling Studies of Selective Catalytic Reduction of NOx with NH3 on Fe and Cu Zeolite Monolithic Catalysts

Download or read book Experimental and Kinetic Modeling Studies of Selective Catalytic Reduction of NOx with NH3 on Fe and Cu Zeolite Monolithic Catalysts written by Pranit Subhash Metkar and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The selective catalytic reduction (SCR) of NOx with NH3 is considered to be the most promising technique for the efficient reduction of highly detrimental NOx (to N2) emitted from diesel engine vehicles. Amongst the various catalysts available for SCR, Fe- and Cu-zeolite catalysts are found to be highly stable and efficient towards maximum NOx reduction over a wide temperature range. Cu-zeolites are more active at low temperatures ( 350 oC) while Fe-zeolites are more active at high temperatures ( 400 oC). We carried out a comprehensive experimental and kinetic modeling study of key SCR reactions on Fe- and Cu-zeolite catalysts and present a detailed understanding of mass transfer limitations and kinetics and mechanistic aspects of various SCR reactions on these catalysts. Experiments carried out on monolith catalysts having different washcoat loadings, washcoat thicknesses and lengths indicate the presence of washcoat (or pore) diffusion limitations at intermediate to high temperature range in all the SCR reactions. A detailed analysis of the effect of temperature on the transitions between various controlling regimes (kinetic, washcoat diffusion and external mass transfer) is presented. Agreement in the differential kinetics studies of NO oxidation and standard SCR (NO + O2 + NH3) reactions indicates NO oxidation is the rate determining step for standard SCR. A detailed kinetic model capturing key features of all the SCR reactions is developed. This model accurately predicts the experimentally observed NOx conversions over a wide temperature range and different feed conditions. Finally, a systematic study of various SCR reactions is carried out on a combined system of Fe- and Cu-zeolite monolithic catalysts to determine if a high NOx conversion could be sustained over a wider temperature range than with individual Fe- and Cu-zeolite catalysts. Amongst various configurations, a dual-layer catalyst with a thin Fe-zeolite layer on top of a thick Cu-zeolite layer resulted in a very high NOx removal efficiency over a broad temperature range of practical interest. The kinetic model accurately captures the experimental data with a combined system of Fe- and Cu-zeolite catalysts and provides further insights into the catalyst arrangements for maximum NOx reduction efficiency.

Book Low Temperature Selective Catalytic Reduction Catalysts

Download or read book Low Temperature Selective Catalytic Reduction Catalysts written by Weiguo Pan and published by Springer. This book was released on 2025-02-22 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Low Temperature Selective Catalytic Reduction SCR of Nitric Oxide NO on Active Carbon Fibre ACF Supported Transition Metal Catalysts

Download or read book Low Temperature Selective Catalytic Reduction SCR of Nitric Oxide NO on Active Carbon Fibre ACF Supported Transition Metal Catalysts written by David Madill and published by . This book was released on 2002 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Investigation and Rational Design of the Catalyst support Interface in Redox Catalysis by Ceria

Download or read book Investigation and Rational Design of the Catalyst support Interface in Redox Catalysis by Ceria written by Zhongqi Liu and published by . This book was released on 2020 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigating and controlling the catalyst-support interfacial interaction/structure and their effects on catalytic performance are crucial for optimizing the activity, selectivity, and durability of catalytic materials, as the heterogeneous catalytic reactions typically take place on the catalyst surface and/or at the interface between the catalyst and support. Ceria (CeO2), due to its remarkable redox activity, has been widely adopted as an active support material or promoter in a multitude of redox catalytic reactions and is the focus of this research. With the goal of bridging the predictable catalyst design-fundamental understanding of performance-practical application, we expect to develop uniform and well-defined CeO2 nanostructures as model supports to investigate the underlying mechanism of the catalyst-support interactions, and furthermore establish the correlation between interfacial structure and catalytically active sites. In Chapter 2, reducible CeO2 nanorods and nanocubes, as well as irreducible SiO2 nanospheres supported cobalt oxides (CoOx) catalysts were synthesized and comparatively studied to understand the effects of support morphology, surface defect, support reducibility, in addition to the CoOx-support interactions on their redox and catalytic properties. Chapter 3 focuses on exploring the role of “bimetallic catalysts-support interaction” over highly active CeO2 nanorods supported pure cobalt oxides and cobalt-based bimetallic oxides nanoparticles (Fe-Co, Ni-Co and Cu-Co). The interactions between cobalt with the second transition metals (Fe, Ni and Cu) are discussed as well. Nanoparticle agglomeration issue always exists when using wet-chemical methods to synthesize CeO2 nanomaterials, which is harmful for catalytic applications due to decreased surface area. Therefore, Chapter 4 presents a scalable and facile electrospinning process for designing novel fibrous structured CeO2 and one-pot synthesis of high-surface-area, thermally stable and low-temperature active Ru-CeO2 nanofiber catalysts. Besides, attracted by the great interest of three-dimensional (3D) nanoarray structures fabrication towards novel and high-performance catalyst design, as well as nanodevice applications, electrochemical deposition technique was adopted for fabricating CeO2 nanoarrays in Chapter 5. Processing factors on growing controllable CeO2 nanoarrays, including the current density, reaction temperature, stirring rate, anode and substrate types were comprehensively investigated. A scale-up synthetic strategy for CeO2 nanoarrays fabrication is developed. Besides, possible mechanisms for morphological evolution and growth of CeO2 nanoarrays are discussed.

Book The Selective Catalytic Reduction of Nitric Oxide with Ammonia

Download or read book The Selective Catalytic Reduction of Nitric Oxide with Ammonia written by Hans Bosch and published by . This book was released on 1987 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: