This book is a printed edition of the Special Issue "Selective Catalytic Reduction of NO_x" that was published in Catalysts

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.

Urea-SCR Technology for deNOx After Treatment of Diesel Exhausts presents a complete overview of the selective catalytic reduction of NOx by ammonia/urea. The book starts with an illustration of the technology in the framework of the current context (legislation, market, system configurations), covers the fundamental aspects of the SCR process (catalysts, chemistry, mechanism, kinetics) and analyzes its application to useful topics such as modeling of full scale monolith catalysts, control aspects, ammonia injections systems and integration with other devices for combined removal of pollutants.

Engineers, applied scientists, students, and individuals working to reduceemissions and advance diesel engine technology will find the secondedition of Diesel Emissions and Their Control to be an indispensablereference. Whether readers are at the outset of their learning journey orseeking to deepen their expertise, this comprehensive reference bookcaters to a wide audience.In this substantial update to the 2006 classic, the authors have expandedthe coverage of the latest emission technologies. With the industryevolving rapidly, the book ensures that readers are well-informed aboutthe most recent advances in commercial diesel engines, providing acompetitive edge in their respective fields. The second edition has alsostreamlined the content to focus on the most promising technologies.This book is rooted in the wealth of information available on DieselNet.com, where the “Technology Guide” papers offer in-depth insights. Eachchapter includes links to relevant online materials, granting readers accessto even more expertise and knowledge.The second edition is organized into six parts, providing a structuredjourney through every aspect of diesel engines and emissions control: Part I: A foundational exploration of the diesel engine, combustion, andessential subsystems. Part II: An in-depth look at emission characterization, health andenvironmental impacts, testing methods, and global regulations. Part III: A comprehensive overview of diesel fuels, covering petroleumdiesel, alternative fuels, and engine lubricants. Part IV: An exploration of engine efficiency and emission controltechnologies, from exhaust gas recirculation to engine control. Part V: The latest developments in diesel exhaust aftertreatment,encompassing catalyst technologies and particulate filters. Part VI: A historical journey through the evolution of dieselengine technology, with a focus on heavy-duty engines in the NorthAmerican market. (ISBN 9781468605693, ISBN 9781468605709, ISBN 9781468605716, DOI: 10.4271/9781468605709)