Diesel particles

A number of environmental applications [3] have been performed in order to size characterize colloids collected in rivers (riverbome particles, SPM, and sediments), clay samples and ground limestone (from soils), coal particles, diesel soot particles (from combustion processes), or airborne particles in urban areas (from waste incinerators, vehicles, household-heating systems, and manufacturing). In many of these cases, not only the size but also the particle size distribution was important and thus, in conjunction with the traditional UV detector, specific detectors such as ETAAS, ICP-MS, ICP-AES were used [40] in order to obtain more detailed, more specific compositional information. 

DOT CLASSIFICATION 3 Label None SAFETY PROFILE Mildly toxic by ingestion. A moderate skin irritant. Questionable carcinogen. Flammable when exposed to heat or flame can react vigorously with oxidizing materials. To fight fire, use CO2, dry chemical. When heated to decomposition it emits acrid smoke and irritating fumes. See also DIESEL EXHAUST, DIESEL EXHAUST EXTRACT, DIESEL EXHAUST PARTICLES, DIESEL FUEL MARINE. 

Dasenbrock et al. (1996) have investigated the carcinogenic potency of carbon particles, diesel soot and benzo[a]pyrene in rats from repeated intracheal administration in a 16-week study. A total dose of 15 mg pure benzo[a]pyrene caused lung tumor in the experimental animals at a rate similar to that caused by diesel soot and carbon black particles. 

Carero, A.D.P., Hoet, P.H.M, Verschaeve, L., Schoeters, G and Nemery, B. (2(X)1). Genotoxic effects of carbon black particles, diesel exhaust particles, and urban air particulates and their extracts on a human alveolar epithehal ceU fine (A549) and a human monocytic ceU line (THP-1). Environ. Mol. Mutagen., 37, 155—163. 

LIDAR (1) Continuous monitoring (2) Accurate and fast (1) Impossible in rainy or misty conditions and certain atmospheric conditions (2) Cannot distinguish background aerosol particles (diesel, smoke, pollen) from potential bioagent plumes (3) Distinguish clouds having similar distributions in aerosol size but of different material compositions... 

Diesel manufacturers have found it difficult to meet the stringent emissions targets. Development of exhaust treatment devices to reduce particulates and meet NO standards has been underway. These devices either trap or catalyticaHy oxidize the particles or both. 

An important appHcation of MMCs in the automotive area is in diesel piston crowns (53). This appHcation involves incorporation of short fibers of alumina or alumina—siHca in the crown of the piston. The conventional diesel engine piston has an Al—Si casting alloy with a crown made of a nickel cast iron. The replacement of the nickel cast iron by aluminum matrix composite results in a lighter, more abrasion resistant, and cheaper product. Another appHcation in the automotive sector involves the use of carbon fiber and alumina particles in an aluminum matrix for use as cylinder liners in the Prelude model of Honda Motor Co. 

Fuels and Lubricants. Rare-earth neodecanoates have been claimed as additives for diesel fuels that reduce the precipitation of particles and gum (108). Neodecanoic acid has also been used in the preparation of ashless detergent additives for fuels and lubricants that reduce engine deposits in internal combustion engines (109). 

The sources of particulate matter in the atmosphere can be primary, directly injected into the atmosphere, or secondary, formed in the atmosphere by gas-to-particle conversion processes (13). The primary sources of fine particles are combustion processes, e.g., power plants and diesel... 

The electrical low-pressure impactor was used to measure the number concentrations of diesel exhaust particles. The particle size distribution ranges from 30 nm upward were then determined using the aerodynamic diameter as the characteristic dimension. ... 

Ahlvik, Peter, Leonidas Ntziachristos, forma Keskinen, and Annele Virtaiien. Real Time Measurements of Diesel Particle Size Distribution with an Electrical l.ow Pressure Impactor. SAL Technical paper 980410. Reprinted from General Emissions (SP-13.3,5). lnternation.al Congress and Exposition, Detroit, February, 23-26 (1998). 

The second method used to reduce exliaust emissions incorporates postcombustion devices in the form of soot and/or ceramic catalytic converters. Some catalysts currently employ zeolite-based hydrocarbon-trapping materials acting as molecular sieves that can adsorb hydrocarbons at low temperatures and release them at high temperatures, when the catalyst operates with higher efficiency. Advances have been made in soot reduction through adoption of soot filters that chemically convert CO and unburned hydrocarbons into harmless CO, and water vapor, while trapping carbon particles in their ceramic honeycomb walls. Both soot filters and diesel catalysts remove more than 80 percent of carbon particulates from the exliatist, and reduce by more than 90 percent emissions of CO and hydrocarbons. 

Oxidative catalytic converters are used to reduce CO and HCs originating from imperfect combustion in engines. At certain temperatures, these converters may also oxidize NO to NO2. Original equipment manufacturer (OEM) particle filters (PFs) employ NO2 to oxidize trapped soot at lower temperatures. However, the excess NO2 may escape from the system as tailpipe emissions. NO2 is very toxic to humans, and it also has impacts on atmospheric ozone-forming chemistry. Alvaraz et al. have stated that the primary NO2 emissions of modern diesel cars are increasing [76]. 

Understanding particulate emissions, their formation and control, is another key issue in meeting the new particulate emission Hmits set by the new EURO emission standards. The particulate emissions formed in diesel engines have a mass median diameter of 0.05-1.0 gm. Particle consists of carbon with various HCs adsorbed on it including polyaromatic hydrocarbon (PAH) as well as nitro-PAH compounds. 

The small particles are reported to be very harmful for human health [98]. To remove particulate emissions from diesel engines, diesel particulate filters (DPF) are used. Filter systems can be metallic and ceramic with a large number of parallel channels. In applications to passenger cars, only ceramic filters are used. The channels in the filter are alternatively open and closed. Consequently, the exhaust gas is forced to flow through the porous walls of the honeycomb structure. The solid particles are deposited in the pores. Depending on the porosity of the filter material, these filters can attain filtration efficiencies up to 97%. The soot deposits in the particulate filter induce a steady rise in flow resistance. For this reason, the particulate filter must be regenerated at certain intervals, which can be achieved in the passive or active process [46]. 

Studies on the particulate distributions from compressed natural gas (CNG) or diesel-fuelled engines with diesel oxidation catalyst (DOC) or partial diesel particle filter (pDPF) have also been performed. The results obtained are used as data for the model, to study the particle penetration into the human respiratory tracts. As a result, the number distribution of particles in different parts of lungs can be modeled [99-101]. Understanding the particle formation and their effects and finding the methods to ehminate the formed particulates from exhaust gas contribute to a cleaner urban environment and thus to a better quality of life. 

The first is to add to the diesel fuel a catalytic additive, which accumulates in the soot particles formed. The catalyst is thus brought to the right place and there is contact. 

Engines. Vehicular petrol engines are potential ignition sources by means of the spark-ignition system, dynamo or battery, or hot exhaust pipe. Non-flameproof diesel engines are potential ignition sources due to a hot exhaust pipe or carbonaceous particles or flames from the exhaust. 

One of principal problems in larger urban centers is the presence of particulate material in the atmosphere due to the emission of diesel engine[l]. One of the most dangerous components of diesel exhaust is particulate, which consists of agglomerates of small carbon particles with a number of different hydrocarbons and sulfates adsorbed on their surfece. A potential way to face the related enviromnental problem is that of filtering the particulate and burning it out in catalyzed traps before any emission of diesel exhausts in the environment. 

Nakagawa R, S Kitamori, K Horikawa, K Nakashima, H Tokiwa (1983) Identification of dinitropyrenes in diesel-exhaust particles. Their probable presence as the major mutagens. Mutation Res 124 201-211. 

Salmeen IT, AM Pero, R Zator, D Schuetzle, TL Riley (1984) Ames assay chromatograms and the identification of mutagens in diesel particle extracts. Environ Sci Technol 18 375-382. 

Moreover, the increasing industrial demand for low-aromatic diesel fuels [2] stimulated by the discovery that diesel exhaust particles generate various respiratory allergies, contributes to developing this area of research area [3-5]. 

The reactor system works nicely and two model systems were studied in detail catalytic hydrogenation of citral to citronellal and citronellol on Ni (application in perfumery industty) and ring opening of decalin on supported Ir and Pt catalysts (application in oil refining to get better diesel oil). Both systems represent very complex parallel-consecutive reaction schemes. Various temperatures, catalyst particle sizes and flow rates were thoroughly screened. 

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