Current society has become more concerned about being environmentally friendly. Catalytic gas after treatment is one of the solutions adopted to reduce pollutant emissions from a combustion engine. A Three Way NOx Storage Catalytic Converter (TWNSC) is a new development of Daimler AG together with Umicore AG [1]. It consists of a Catalyst with some of the main properties of a Three Way Catalyst (TWC) together with NOx storage capacity (lean-NOx trap). This catalyst is used in Otto direct-injection engines with lean/rich operation mode. This technology can reduce fuel consumption in a range of 10%. During lean engine operation time, high quantities of Nitrogen Oxides (NOx) are generated. In presence of a TWNSC, this NOx can be stored. When the engine changes to rich operating mode, the amount of NOx in exhaust gases decreases become rich of unburned hydrocarbons (HC), hydrogen (H2) and carbon monoxide (CO) that can reduce the NOx stored. However, during NOx reduction, formation of undesired byproducts occur. That is the case of nitrous oxide (N2O) and ammonia (NH3). In this Master thesis, studies on the reduction of nitrous oxide formation in Three Way NOx Storage Catalytic Converter are performed. Studies on N2O formation during catalyst performance have not been widely studied and published. In this master thesis, lean/rich experimentations on two new TWNSC (catalyst A and B) are performed to find conditions in which N2O formation can be reduced. Experiments are performed in a test bench where lean gases are provided by a 1- cylinder-engine and rich gases from synthetic gas mixtures. At the beginning of the master thesis, two preliminary investigations are performed. The first consists of the calculation of Oxygen Storage Capacity (OSC) of a cylindrical sample (25 mm diameter, 30 mm length) of catalyst A and B. The results of the experiment show that catalyst B has less Oxygen Storage Capacity. The experiment consisted on applying a flow of 12,5 l/min of Oxygen (O2) in nitrogen (N2) (0,4% by volume) through the previously reduced sample. An average of 0,3 g./l.cat. less oxygen is stored in catalyst B for temperatures of 300, 350 and 400 oC. At 300oC, catalyst A stores 1,44 g/l.cat. compared to the 0,93 g/l.cat. in catalyst B. The second preliminary investigation consists of determining the temperature in which the Diesel Oxidation Catalyst (DOC) in reactor 1 has to operate. The objective of this DOC is to oxidize the HC and maintain the original NO2/NOx ratio from the engine exhaust gases. During lean mode, gases from a 1-cylinder-engine (Hatz-motor [2]) are used. NOx and HC concentrations are analyzed for a range of temperatures from 150 to 650 oC. It is concluded that a temperature of 620 oC has to be reached in reactor one to get rid of HC and maintain the NO2/NOx ratio of the bypass exhaust gases (2% of NO2 in NOx). After the preliminary investigations, the first objective is getting to know the basic performance of the two different TWNSC. Lean/rich experimentations are performed on both samples A and B at the range of temperatures from 150oC to 450oC. Lean/rich timing is set on 120/15 seconds respectively. In addition, three different rich gas mixtures (lambdas 0,95, 0,9 and 0,82) have been used for the rich mode. Results show that for lambda 0,95 less N2O is generated (0,06 g/l.cat. at 300oC in catalyst A). The minimum N2O detected is at catalyst B at temperatures of 400 and 450oC (0,01 and 0,00 g/l.cat.). The main part of the Master Thesis consists of four different experimentations that have the objective to find any reduction in N2O formation: 1. N2O formation studies with lean/rich experimentations at modified TWNSC catalysts. Instead of the 30 mm sample previously used, two 15 mm samples are used together. Modifications are applied on the first 15 mm sample and consist on five perforations (2 mm diameter) and the introduction of an uncoated central part section. These modifications try to increase reductants velocity during rich mode. Results show a decrease in N2O formation in the experiment with 15 mm uncoated catalyst A together with another 15 mm catalyst A. An average of 2,8 g/l.cat. of N2O reduction is obtained at temperature of 300oC. In addition, an increase of NOx conversion efficiency has been detected: for the same sample and temperature an average increase of 20% NOx performance 2. N2O formation studies with lean/rich experimentations at a combination of catalysts A and B together. It is concluded that the combination of catalyst A and B does not have a beneficial effect on N2O formation. 3. N2O formation studies with lean/rich experimentations with variation of rich time period. The objective is to see if the reduction of rich time period has an effect on N2O formation. 4. Lean/rich experimentations with variation of the lambda during rich period. The objective is to see if a reduction in N2O is obtained with these variations. For low temperatures (150oC and 200oC) a diminution in N2O formation is appreciated (0,05 g/l.cat to 0,04 g./l.cat at 150oC for 30 mm TWNSCA with uncoated section). This Master Thesis represents a base line study for further investigations on N2O formation on TWNSC. Catalyst modifications are a feasible solution for N2O diminution as well as NOx conversion efficiency. These results encourage further experimentations with these current and other new catalyst modifications. Variation of lambda during rich period and variation of the rich time period are variables that can have a relevant role.

Includes two overview chapters covering both technical and regulatory aspects of nitrogen oxide emissions from stationary sources. Discusses new directions in the field, such as direct composition of NO 2, different reducing agents, new catalytic materials, and two new noncatalytic techniques. Provides a thorough insight into the phenomena involved in existing technologies. Offers a broad spectrum of studies tackling the problem of NO 2 reduction.

Vehicle exhaust emissions, particularly from diesel cars, are considered to be a significant problem for the environment and human health. Lean NOx Trap (LNT) or NOx Storage/Reduction (NSR) technology is one of the current techniques used in the abatement of NOx from lean exhausts. Researchers are constantly searching for new inexpensive catalysts with high efficiency at low temperatures and negligible fuel penalties, to meet the challenges of this field. This book will be the first to comprehensively present the current research on this important area. Covering the technology used, from its development in the early 1990s up to the current state-of-the-art technologies and new legislation. Beginning with the fundamental aspects of the process, the discussion will cover the real application standard through to the detailed modelling of full scale catalysts. Scientists, academic and industrial researchers, engineers working in the automotive sector and technicians working on emission control will find this book an invaluable resource.

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

The book is about calorimetry and thermal analysis methods, alone or linked to other techniques, as applied to the characterization of catalysts, supports and adsorbents, and to the study of catalytic reactions in various domains: air and wastewater treatment, clean and renewable energies, refining of hydrocarbons, green chemistry, hydrogen production and storage. The book is intended to fill the gap between the basic thermodynamic and kinetics concepts acquired by students during their academic formation, and the use of experimental techniques such as thermal analysis and calorimetry to answer practical questions. Moreover, it supplies insights into the various thermal and calorimetric methods which can be employed in studies aimed at characterizing the physico-chemical properties of solid adsorbents, supports and catalysts, and the processes related to the adsorption desorption phenomena of the reactants and/or products of catalytic reactions. The book also covers the basic concepts for physico-chemical comprehension of the relevant phenomena. Thermodynamic and kinetic aspects of the catalytic reactions can be fruitfully investigated by means of thermal analysis and calorimetric methods, in order to better understand the sequence of the elemental steps in the catalysed reaction. So the fundamental theory behind the various thermal analysis and calorimetric techniques and methods also are illustrated.

NOx Emission Control Technologies in Stationary and Automotive Internal Combustion Engines: Approaches Toward NOx Free Automobiles presents the fundamental theory of emission formation, particularly the oxides of nitrogen (NOx) and its chemical reactions and control techniques. The book provides a simplified framework for technical literature on NOx reduction strategies in IC engines, highlighting thermodynamics, combustion science, automotive emissions and environmental pollution control. Sections cover the toxicity and roots of emissions for both SI and CI engines and the formation of various emissions such as CO, SO2, HC, NOx, soot, and PM from internal combustion engines, along with various methods of NOx formation. Topics cover the combustion process, engine design parameters, and the application of exhaust gas recirculation for NOx reduction, making this book ideal for researchers and students in automotive, mechanical, mechatronics and chemical engineering students working in the field of emission control techniques. Covers advanced and recent technologies and emerging new trends in NOx reduction for emission control Highlights the effects of exhaust gas recirculation (EGR) on engine performance parameters Discusses emission norms such as EURO VI and Bharat stage VI in reducing global air pollution due to engine emissions

Increases in vehicle exhaust emission regulations have led to research, development and improvements in catalytic converter technologies for gasoline-powered vehicles since the 1970s. Nowadays, there are strict regulations and standards for diesel engines as well, and one of the regulated species is nitrogen oxides (NOX). The lean NOX trap (LNT) catalyst has been studied and developed for use in lean burn (of which diesel is an example) engine exhaust as a technology to reduce NOX to N2. Typical LNT catalysts contain Pt, which catalyzes NO oxidation and NOX reduction, and an alkali or alkaline earth material for NOX storage via nitrate formation. The catalyst is operated in a cyclic mode, with one phase of the cycle under oxidizing conditions where NOX is trapped, and a second phase, which is reductant-rich relative to O2, where stored NOX is reduced to N2. A recently developed catalyst uses a perovskite material as part of the LNT formulation for the oxidation reactions thereby eliminating the need for Pt in a LNT. This catalyst does include Pd and Rh, added to accommodate hydrocarbon oxidation and NO reduction, respectively. Ba was used as the trapping component, and Ce was also part of the formulation. NO oxidation kinetics over the fully-formulated and bare perovskite material were determined, with NO, O2 and NO2 orders being at or near 1, 1 and -1, respectively for both samples. The fully-formulated sample, which contains Ba supported on the perovskite, was evaluated in terms of NOX trapping ability and NOX reduction as a function of temperature and reduction phase properties. Trapping and overall performance increased with temperature to 375°C, primarily due to improved NO oxidation, as NO2 is more readily trapped, or better diffusion of nitrates away from the initial trapping sites. At higher temperatures nitrate stability decreased, thus decreasing the trapping ability. At these higher temperatures, a more significant amount of unreduced NOX formed during the reduction phase, primarily due to nitrate instability and decomposition and the relative rates of the NOX and oxygen storage (OS) components reduction reactions. Most of the chemistry observed was similar to that observed over Pt-based LNT catalysts. However, there were some distinct differences, including a stronger nitrate diffusion resistance at low temperature and a more significant reductant-induced nitrate decomposition reaction. The perovskite-based lean NOX trap (LNT) catalyst was also evaluated after thermal aging and sulfur exposure. NO oxidation, NOX trapping ability and NOX reduction as a function of temperature and reduction phase properties were evaluated. Similar overall performance trends were seen before and after degradation, however lower performance after thermal aging and sulfur exposure were seen due to sintering effects and possible build-up of S species. Although performance results show that most of the sulfur was removed after desulfation, some sulfur remained affecting the trapping and reduction capabilities as well as the water gas shift (WGS) extent at lower temperatures. The Oxygen storage capacity (OSC) on the other hand was maintained after the catalyst was exposed to thermal aging and sulfur poisoning then desulfation, all of which suggest that the perovskite or Pd components were irreversibly poisoned to some extent.

There is a mounting consensus that human behavior is changing the global climate and its consequence could be catastrophic. Reducing the 24 billion metric tons of carbon dioxide emissions from stationary and mobile sources is a gigantic task involving both technological challenges and monumental financial and societal costs. The pursuit of sustainable energy resources, environment, and economy has become a complex issue of global scale that affects the daily life of every citizen of the world. The present mitigation activities range from energy conservation, carbon-neutral energy conversions, carbon advanced combustion process that produce no greenhouse gases and that enable carbon capture and sequestion, to other advanced technologies. From its causes and impacts to its solutions, the issues surrounding climate change involve multidisciplinary science and technology. This handbook will provide a single source of this information. The book will be divided into the following sections: Scientific Evidence of Climate Change and Societal Issues, Impacts of Climate Change, Energy Conservation, Alternative Energies, Advanced Combustion, Advanced Technologies, and Education and Outreach.

Periodical regeneration of NOx storage catalyst (also known as lean NOx trap) by short rich pulses of CO, H2 and hydrocarbons is necessary for the reduction of nitrogen oxides adsorbed on the catalyst surface. Ideally, the stored NOx is converted into N2, but N2O and NH3 by-products can be formed as well, particularly at low-intermediate temperatures. The N2 and N2O products are formed concurrently in two peaks. The primary peaks appear immediately after the rich-phase inception, and tail off with the breakthrough of the reductant front accompanied by NH3 product. In addition, the secondary N2 and N2O peaks then appear at the rich-to-lean transition as a result of reactions between surface-deposited reductants/intermediates (CO, HC, NH3, -- NCO) and residual stored NOx under increasingly lean conditions.