Catalytic automotive exhaust aftertreatment

It has now been over 25 years since the introduction of the catalytic converter to reduce emissions from the internal combustion engine. It is considered one of the greatest environmental successes of the 20th century, however, new emission control technologies are still being developed to meet ever more stringent mobile source (gasoline and diesel) emissions. This short review will discuss the basis for improvements and highlight technology area, which will require further improvements in emissions and fuel economy. Some of the issues related to fuel cells which some believe may replace the internal combustion engines for automobile applications is also be briefly discussed.

International journal of engineering research and technology, 2013

Today, modern cars emit up to 99% less exhaust pollutants than 30 years ago. But due to incomplete combustion in the engine, there are a number of incomplete combustion products CO, HC, NO x, particulate matters etc. These pollutants have negative impact on air quality as well as on human health. This paper gives an overview of the advanced technologies currently used for abating emissions from the gasoline and diesel internal combustion engines also discusses automotive exhaust emission and its harmful impact, automotive exhaust emission control technique, catalytic converter and its types, DOC, limitation of catalytic converter, DPF, SCR and also significance of catalytic converter.

Today, air pollution is one of the major environmental concerns on a global scale. Rapid industrialization and urbanization of the world has resulted in uncontrolled, large amounts of noxious emissions into the atmosphere. One of the biggest sources of these emissions is the transportation industry. Automobiles using internal combustion engines burn fossil fuels to generate power and these engines emit NOx, CO and unburnt hydrocarbons (UHCs). These pollutants are harmful to human health and in presence of sunlight, these substances result in formation of O3 at ground level. Prevention of emission of these pollutants is thus crucial, by precombustion as well as post-combustion techniques. Transportation in today's world is the most inevitable part of daily life, thus eliminating fuel combustion completely is not a viable solution. The most effective post-combustion technique, the catalytic converter, has been studied in this paper. The first ever converter and its subsequent evolutions have been discussed. A study of several peer-reviewed research papers has been carried out and inferences have been made regarding the physical and chemical processes involved in the process. Catalytic converters have limitations such as cold-start emissions, high material costs, direct and indirect environmental illeffects. There have been developments such as variable-conductance insulation, phase-change material and thermal management systems, aimed at reducing cold-start emissions. These techniques and other developments aimed at cost-reduction in catalytic converters have been discussed.

2004

Perovskite type non-noble metal-based catalytic materials have been developed for their possible applications in diesel exhaust emission control. These materials have been evaluated for their applications in regeneration of diesel particulate filter (DPF) and also as diesel catalytic converter (DCC). Both the applications require low temperature oxidation catalysis properties. Temperature-programmed desorption studies revealed the lowtemperature oxygen desorption of perovskite catalyst, which may be useful for the oxidation of carbon/soot at lower temperature. Laboratory evaluation results on activated carbon show the carbon oxidation activity of the catalyst in a temperature range of 300-450°°C. However, this was achieved under the tight contact of carbon and catalyst. Catalyst coated-ceramic foams have been used to fabricate laboratory prototype of regenerative type DPF. Although its evaluation on a vehicle shows significant reduction in smoke density, however, the regeneration temperature was still higher than desired. The DCC shows 10-25% reduction in smoke density depending on engine conditions. The perovskite-type catalyst appears to follow a redox mechanism for soot oxidation through oxygen removal and replenishment, while hydrocarbons adsorbed on soot particles may also help in oxidation of the carbonaceous part.

A major part of the air pollution caused is due to the vehicular emission which is increasing at an alarming rate. The different types of vehicles like car, bus, truck etc. contribute a way as well as play a dominant duty in increasing air pollution. These vehicles find its running source mainly form the extracts of fossil fuels like petrol, diesel. The fuels undergo combustion to generate energy so as to support the vehicle for duty. The incomplete combustion of the fuels in the engine paves a way for production of products like the carbon monoxide, hydrocarbons and particulate matters. A high emission level is therefore a proved result. For the purpose of forcing the fuel to have efficient combustion and for reduction of the emission levels for reducing air pollution a wide range of processes are applicable. These include improvising engine design, fuel pre-treatment etc. Among these wide ranges of options available catalytic converter is found to be a better way for establishing an efficient combustion in the controller engine of the vehicle. Usage of noble group metal is an effective way for effective combustion like the platinum group metal serves way good for reducing the exhausts. With the help of secondary measures efficiency of the engine is improved as well. The techniques are still under development as because there are some limitations of the catalytic converters which are needed to be dealt with but the application of this technique has better achievement points as well.

MATEC Web of Conferences, 2016

Exhaust emission from automobile source has become a major contributor to the air pollution and environmental problem. Catalytic converter is found to be one of the most effective tools to reduce the overwhelming exhaust pollutants in our environment. The development of sustainable catalytic converter still remains a critical issue due to the stringent exhaust emission regulations. Another issue such as price and availability of the precious metal were also forced the automotive industry to investigate the alternatives for producing a better replacement for the material used in catalytic converter. This paper aims at reviewing the present development and improvement on the catalytic converter used on the reduction of exhaust emission in order to meet the regulations and market demand. The use of new catalyst such as to replace the noble metal material of Platinum (Pt), Palladium (Pd) and Rhodium (Rh) has been reviewed. Material such as zeolite, nickel oxide and metal oxide has been found to effectively reduce the emission than the commercial converter. The preparation method of the catalyst has also evolved through the years as it is to ensure a good characteristic of a good monolith catalyst. Ultrasonic treatment with combination of electroplating technique, citrate method and Plasma Electrolytic Oxidation (PEO) has been found as the latest novel preparation method on producing an effective catalyst in reducing the exhaust emission.

International Journal of Recent Technology and Engineering (IJRTE), 2019

The purpose of the work presented in this paper is to find and suggest a suitable solution to the exhaust pollution coming from the Diesel Automobiles particularly in the metro cities. Due to incomplete combustion of fuel oil pollutants like CO, HC, NOx are released into atmosphere causing negative impact on air quality, environment and human health. Researchers all over the world concentrated on how to reduce the pollutants. Euro norms specify the allowable percentages of CO, HC and NOx in the exhaust gases. Euro norms being implemented in the developed countries have given stringent values which has led to the development of catalytic converter which is an added equipment in automobile. Hitherto in the catalytic converters supplied in modern cars, Platinum and Rhodium metals are used for coating monoliths. These metals are rare and hence expensive. In the research carried out by the authors, suitable monolith substrates are tested and used in the catalytic converters with coating ...

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2001

The application of computer simulation in the development of catalytic exhaust aftertreatment systems for cars is over thirty years old. However, ever-increasingly stringent exhaust emissions legislation requires an ever-increasing degree of accuracy and complexity in the mathematical models applied. Traditionally, the Langmuir-Hinshelwood kinetics were applied in the majority of the models available, with a small number of representative chemical reactions. In this paper it is proved, by means of typical case studies, that the above modelling approach, with the necessary re ning, can be brought to the level of accurately predicting the behaviour of advanced catalyst systems employed in EURO-3 and EURO-4 emissions homologation. An essential characteristic that was introduced to this end is the computer-aided selection ( best t) of the tunable parameters representing the apparent chemical kinetics and oxygen storage and release properties of each diVerent catalystwashcoat combination. Other modelling improvements are also discussed in the present paper, setting the scene for high accuracy simulations in view of the current and future emissions standards for spark-ignited, diesel and gasoline direct injection (GDI )-engined vehicles. These include the modelling of the aged catalyst, as well as taking into account the eVect of precious metal loading variation on the apparent kinetics.

New Trends and Developments in Automotive Industry, 2011

International Journal of Modern Trends in Engineering & Research

In automobile industry, the exhaust from the internal combustion engine is a complex mixture of gases and fine particles. Many pollutants are introduced in the environment such as Carbon Monoxide (CO), Nitrogen Oxides (NOx), Hydrocarbons (HC), etc. These pollutants may lead to affect the respiratory system as well as increase the risk of heart problems, premature death and lung cancer. To control the emission of these pollutants in environment catalytic converters are used. The commonly used catalyst in converters is mostly a precious metal such as Palladium, Palladium and Rhodium. Platinum is widely used and very active catalyst, but is very expensive. Rhodium is used as reduction catalyst, while Palladium is used as oxidation catalyst. Since, these materials are expensive the cost of catalytic converter increases. Thus the purpose of the project is to improve effectiveness of catalytic converter by using a different material along with the regular used noble metals. These materials perform the same task along with the catalyst and the additional task of storing and releasing oxygen during rich mixture combustion.