Diesel engines have high efficiency, durability, and reliability together with their low-operating cost. These important features make them the most preferred engines especially for heavy-duty vehicles. The interest in diesel engines has risen substantially day by day. In addition to the widespread use of these engines with many advantages, they play an important role in environmental pollution problems worldwide. Diesel engines are considered as one of the largest contributors to environmental pollution caused by exhaust emissions, and they are responsible for several health problems as well. Many policies have been imposed worldwide in recent years to reduce negative effects of diesel engine emissions on human health and environment. Many researches have been carried out on both diesel exhaust pollutant emissions and aftertreatment emission control technologies. In this paper, the emissions from diesel engines and their control systems are reviewed. The four main pollutant emissions from diesel engines (carbon monoxide-CO, hydrocarbons-HC, particulate matter-PM and nitrogen oxides-NOx) and control systems for these emissions (diesel oxidation catalyst, diesel particulate filter and selective catalytic reduction) are discussed. Each type of emissions and control systems is comprehensively examined. At the same time, the legal restrictions on exhaust-gas emissions around the world and the effects of exhaust-gas emissions on human health and environment are explained in this study.

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The pollutant emissions from diesel-engine vehicles and exhaust aftertreatment systems

A method of converting nitrogen oxides in a gas to nitrogen by contacting the nitrogen oxides with a nitrogenous reducing agent in the presence of a zeolite catalyst containing at least one transition metal, wherein the zeolite is a small pore zeolite containing a maximum ring size of eight tetrahedral atoms, wherein the at least one transition metal is selected from the group consisting of Cr, Mn, Fe, Co, Ce, Ni, Cu, Zn, Ga, Mo, Ru, Rh, Pd, Ag, In, Sn, Re, Ir and Pt.

Transition metal/zeolite scr catalysts

Provided is a catalyst article for simultaneously remediating the nitrogen oxides (NOx), particulate matter, and gaseous hydrocarbons present in diesel engine exhaust streams. The catalyst article has a soot filter coated with a material effective in the Selective Catalytic Reduction (SCR) of NOx by a reductant, e.g., ammonia.

Catalyzed scr filter and emission treatment system

An exhaust emission control system of an internal combustion engine capable of post injection is disclosed which provides control such that the injection timing in sub injection is set to a point earlier than the target injection timing when the sub injection is started, and the injection timing in the sub injection is then delayed to the target injection timing. This realizes the post injection under the optimum conditions and enables an efficient rise in the exhaust temperature while inhibiting deterioration of the drivability due to a rapid change in torque.

Exhaust emission control system of internal combustion engine

Zeolite catalysts and systems and methods for preparing and using zeolite catalysts having the CHA crystal structure are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stable at high reaction temperatures. The zeolite catalysts include a zeolite carrier having a silica to alumina ratio from about 15:1 to about 256:1 and a copper to alumina ratio from about 0.25:1 to about 1:1.

Copper cha zeolite catalysts

A diesel engine aftertreatment exhaust system uses catalyzed soot filters for particulate matter reduction and urea SCR catalysts for NOx reduction on diesel engines in a combined system to lower particulate matter and NOx at the same time. With this integral emission control system, diesel engines are able to meet ultra low emission standards.

Exhaust system for enhanced reduction of nitrogen oxides and particulates from diesel engines

Provided is an emissions treatment system for an exhaust stream, having a NOx storage reduction (NSR) catalyst (2) with a NOx sorbent at a concentration of at least 0.1g/in3 and a platinum group metal component dispersed on a refractory metal oxide support; and an SCR catalyst (3) disposed downstream of the NSR catalyst (2). The emissions treatment system is advantageously used for the treatment of exhaust streams from diesel engines and lean burn gasoline engines.

Emissions treatment system with NSR and SCR catalysts

Provided is an emissions treatment system and method for reducing NOx emissions in the exhaust stream produced from an internal combustion engine. The system has an injector for periodically metering ammonia or an ammonia precursor into an exhaust stream; and a first substrate with a first SCR catalyst composition, downstream of the injector. The first substrate has an inlet end, an outlet end, a length extending between the inlet end to the outlet end, wall elements and a plurality of passages defined by the wall elements. The first SCR catalyst composition is disposed on the wall elements from the inlet end toward the outlet end to a length that is less than the substrate's axial length to form an inlet zone. The first substrate also has an NH3 destruction catalyst composition with a platinum group metal component dispersed on a refractory metal oxide. The NH3 destruction catalyst is disposed on the wall elements from the outlet end toward the inlet end to a length that is less than the substrate's axial length to form an outlet zone. Generally, there is from 0.1 to 10 g/ft3 of platinum group metal component in the outlet zone.

Joseph A. Patchett

Papers

Catalyzed scr filter and emission treatment system

Copper cha zeolite catalysts

Exhaust system for enhanced reduction of nitrogen oxides and particulates from diesel engines

Emissions treatment system with NSR and SCR catalysts

Zone coated catalyst to simultaneously reduce NOx and unreacted ammonia