Increasingly demanding exhaust emissions regulations require that automotive three-way catalysts (TWC) must exhibit excellent catalytic activity and durability. Thus, developing TWC based on an accurate understanding of deactivation mechanisms is critical. This work briefly reviews thermally induced deactivation mechanisms, which are the major contributor to deactivation, and provides an overview of the common strategies for improving durability and preventing deactivation. It highlights the interaction of metals with supports and the diffusion inhibition of atoms and crystallites in both washcoats and metal nanoparticles and concludes with some recommendations for future research directions towards ever more challenging catalyst manufacture to meet increasing durability requirements both now and in the future.
1. Introduction This symposium was organised by Chalmers University of Technology, Sweden, to commemorate the first 20 years of research at Competence Centre for Catalysis (KCK). The Frontiers in Environmental Catalysis conference was held on 24th September 2015 at Chalmers University of Technology. All previous and current KCK employees were invited, together with representatives of KCK’s...
The development of gasoline direct injection (GDI) engines has provided a strong alternative to port fuel injection engines as they offer increased power output and better fuel economy and carbon dioxide emissions. However, particulate matter (PM) emission reduction from GDI still remains a challenge that needs to be addressed in order to fulfil the increasingly stricter environmental...
Introduction When the first edition of this book by Karl B. Schnelle and Charles A. Brown was published (1) some 16 years ago, there were a number of texts available that covered various aspects of pollution emissions and their control, including “Practical Handbook of Environmental Control” by Conrad P. Straub (2) that gave in tabular form a huge amount of easily accessed relevant data,...
Driven by concerns on deteriorating ambient air quality, measures are being taken across the world to adopt and enforce tighter vehicular emission regulations to minimise tailpipe unburned hydrocarbons, nitrogen oxides (NOx) and particulate matter (PM). In regions with advanced regulations, the focus is on limiting the pollutants under real-world or in-use driving conditions. Given the intensified effort to curb global warming and limit fossil fuel use in the transportation sector, several countries have adopted targets on tailpipe carbon dioxide emissions. This confluence of stringent regulations for both criteria pollutant and greenhouse gas (GHG) emissions is leading to a rapid adoption of advanced powertrains and aftertreatment technologies. This is a review of some of these recent advances pertinent to reducing vehicular emissions and developing improved aftertreatment solutions. The scope is limited to gasoline vehicles where the adoption of gasoline direct injection (GDI) and hybrid powertrain technologies is leading to significant shifts in the aftertreatment solutions. There is significant work being done to improve diesel aftertreatment systems especially in light of real-world driving emission (RDE) regulations. These are not covered here, rather the reader is referred to a previous article in this journal’s archive (1), and to a more recent review (2).
Methanol is increasingly being looked at as a way to reduce the emissions potential of transport fuel. It may be used in place or in addition to gasoline fuel, for example. The amount of greenhouse gas (GHG) emitted in producing methanol can vary hugely according to the syngas generation technology selected and the choice of electrical or steam turbine drive for compressors and pumps. This paper looks at the impact of these technology choices on GHG emissions and how the carbon intensity of methanol used as a transport fuel compares to the carbon intensity of other hydrocarbon fuels. It is found that methanol produces lower well to wheel emissions than gasoline under all production methods studied and can even produce lower GHG emissions compared to ethanol as a fuel supplement. However, the same is not always true if methanol is used to produce gasoline from natural gas.
China has been the world’s largest new vehicle market since 2009 and new vehicle sales exceeded 28 million in 2016, among which more than 87% were light-duty vehicles (LDV). In order to reduce emissions and control air pollution China has recently adopted the China 6 emissions standard for LDV which is 50% more stringent than China 5. Besides strengthening the tailpipe emissions limits, China 6 changes the emissions test driving cycle to the Worldwide Harmonised Light-Duty Vehicle Test Cycle (WLTC), adds real road emissions requirements and significantly strengthens evaporative emissions control. This paper introduces the standard development background, summarises the key technical improvements and discusses the areas for further improvements in future.
The annual SAE Congress is the vehicle industry's largest conference and covers all aspects of automotive engineering. The 2012 congress took place in Detroit, USA, from 24th–26th April 2012. There were upwards of a dozen sessions focused on vehicle emissions technology, with most of these on diesel emissions. More than 70 papers were presented on this topic. In addition, there were two...
The 40th anniversary of the manufacture of the world's first commercial batch of autocatalysts for passenger cars at Johnson Matthey Plc's site in Royston, UK, was marked in May 2014. Despite the enormous progress made in reducing the emission of pollutants from vehicles since the 1970s, there has also been considerable recent discussion about the levels of nitrogen oxides (NOx),...
The control of oxides of nitrogen (NOx) emissions to meet more stringent motor vehicle emission legislation has been enabled by the development of various exhaust gas aftertreatment technologies, notably those that employ platinum group metals (pgms). Technology Developments For gasoline engines the most common aftertreatment for the control of NOx, as well as the other major regulated...
1. Introduction The Society of Automotive Engineers (SAE) 2014 Heavy-Duty Diesel Emission Control Symposium was, like its predecessors, hosted in Gothenburg, Sweden. This biennial two-day event attracted around 160 delegates. Most of the delegates (>95%) came from catalyst system and component suppliers as well as original equipment manufacturers (OEMs). A few delegates came from academia,...
Gasoline particulate filters (GPFs) are being developed to enable compliance with future particulate number (PN) limits for passenger cars equipped with gasoline direct injection (GDI) engines. A PN emissions limit of 6 × 1011 km–1 over the New European Drive Cycle (NEDC) will apply for new GDI vehicles from September 2017. (A three year derogation allowing a higher PN limit of 6 × 1012...
Many industrial processes produce hydrocarbon vapours which, if released to the atmosphere, contribute to the general pollution of the environment. The discharge of such vapours is now, not unnaturally, being subject to legislative control in many places as the extent of the damage resulting from such pollution is more fully realised. Platinum catalyst control systems are being increasingly employed to prevent air pollution as the cost benefits of employing such systems, are becoming more generally known. This paper describes the system one enterprising organisation has successfully employed to comply with the strict pollution control regulations in Los Angeles, a region where topography and climatic conditions result in particularly difficult pollution problems, while at the same time making substantial savings in fuel.
Introduction The 24th North American Meeting of the Catalysis Society (NAM) was held from 14th to 19th June 2015 at the David L. Lawrence Convention Center in Pittsburgh, Pennsylvania, USA, with the Pittsburgh-Cleveland Catalysis Society as hosts (1). This biennial meeting is recognised as the premier conference about the science and applications of catalysis and catalytic processes and as...
This symposium held in Bad Harrenalb, Germany, from 3rd–5th September, 2017, specifically focused on modelling and numerical simulation in automobile exhaust-gas aftertreatment. The purpose of the workshop was to support the exchange of state-of-the-art modelling and simulation techniques and new approaches among researchers, scientists and engineers from industry and academia. The meeting had over 100 registered participants, about 45% from academia and 55% from industry. The scientific programme was composed of four tutorials, plus oral and poster presentations.
This report gives a summary of the oral presentations, which will be divided into five sessions: selective catalytic reduction (SCR), methane oxidation, diesel oxidation catalyst (DOC), diesel particulate filter (DPF) and modelling and performance.
Introduction Three-way catalysts (TWCs) have been widely applied on stoichiometric-burn gasoline engine powered vehicles to reduce the tailpipe emissions of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx). A conventional TWC can convert the three pollutants at nearly 100% conversion efficiency once it reaches its operation temperature, typically above 400°C. As the...
1. Introduction The Carbon Dioxide Utilisation Summits are held twice per year, alternating between being hosted in a European location and in North America. They are organised by Active Communications International (ACI), Inc. This two-day event was held in Reykjavik, Iceland, on 18th and 19th October 2017. The main aim of this Summit series is to bring together key players from industry,...
A catalyst support is often used to disperse a catalyst material to enhance the contact area for reaction. In catalytic converters, a coating called the catalyst layer contains both the catalyst support and catalytically active material. Given the role of the catalyst layer in catalytic converters, its mechanical strength is of great importance as it determines the service life of catalytic converters. This review paper therefore summarises a number of methods which are currently used in the literature to measure the strength of a catalyst layer. It was identified that the methods applied at present could be divided into two groups. All methods regardless of the group have been successfully used to investigate the effect of a range of formulation and process parameters on the strength of a catalyst layer. In terms of measurement principles, Group 1 methods measure the strength based on mass loss after the layer sample is subjected to a destructive environment of choice. Group 2 methods tend to give more direct measurements on the strength of bonding between particles in a catalyst layer. Therefore, strength data generated by Group 2 methods are more reproducible between different researchers as the results are less dependent on the testing environment. However, methods in both groups still suffer from the fact that they are not designed to separately measure the cohesive and the adhesive strength of a catalyst layer. Two new methods have been recently proposed to solve this problem; with these methods, the cohesive and adhesive strength of a catalyst layer can be measured separately.
Introduction The topical conference series Catalysis and Automotive Pollution Control, generally known by the acronym ‘CAPoC’, has taken place periodically at the Université Libre de Bruxelles, Belgium, since the first one in 1986. The late Professor Alfred (Freddy) Frennet was central in establishing these conferences and for many years he was their guiding force. The first four...
The introduction and development of catalytic control for exhaust gas emissions from vehicles has been one of the major technical achievements over the last four decades. A huge number of cars were manufactured during this time that provided society with a high degree of personal mobility and without the continuous development of emissions control technologies the atmospheric pollution...