Platinum diesel engines

S. Caroli, A. Alimonti, F. Petrucci, B. Bocca, P. Schramel, M. Zischka, C. Pettersson, U. Wass, M. Luna, J. C. Saenz, J. SantamarEnvironmental risk of particulate and soluble platinum group elements released from gasoline and diesel engine catalytic converters, Sci. Total Environ., 296 (2002), 199D208. 

Figure 102. Emission of particulates (part) and gaseous hydrocarbons (HC) from a heavy duty diesel engine in the US transient engine test cycle, as a function of the catalyst volume (monolith catalyst with 46 cells cm" diesel oxidation catalyst formulation with platinum at a loading of 1.76 g 1 , fresh).

Figure 103. The amount of soluble organic fraction (SOF) adsorbed on an aged diesel oxidation catalyst, as a function of the washcoat formulation (monolith catalyst with 62cellscm", dedicated diesel washcoat formulations with platinum at a loading of l.76gl diesel engine bench aging for 50 h diesel fuel containing 0.15 wt. % sulfur). Reprinted with permission from ref. (68], C 1991 Society of Automotive Engineers, Inc.

Figure 1 5. Conversion of carbon monoxide, gaseous hydrocarbons and sulfur dioxide reached over a diesel catalyst with and without measures to suppress the formation of sulfates, as a function of the exhaust gas temperature (monolith catalyst with 62 cells cm dedicated diesel washcoat formulations with platinum at a loading of 1.76 g I" diesel engine test bench light-off test at a space velocity of 120000 N1 F h diesel engine bench aging procedure for 100 h at a catalyst inlet temperature of 773 K).

Figure 107. Conversion of (a) gaseous hydrocarbons (b) total particulate (PT) matter and (c) the soluble organic fraction (SOF) as a function of the exhaust gas temperature, reached over diesel eatalysts based on platinum or on palladium (monolith catalyst with 62 cells cm dedicated diesel washeoat formulations with platinum and palladium both at a loading of 0.35 g 1" and 1.41 g 1" in the fresh state heavy duty diesel engine bench light-off test at an average engine speed setting and various engine load settings).

Figure 109. Conversion of carbon monoxide and gaseous hydrocarbons reached over a diesel oxidation catalyst at various settings of the exhaust gas temperature, for a model gas composition with and without SO2 (monolith catalyst with 62cells cm dedicated diesel washcoat formulations with platinum loading of 1.76gl" in the fresh state model gas light-off test at a space velocity of 50000Nir h model gas simulates the exhaust gas composition of an IDI passenger car diesel engine at medium load and speed).

Table 27. Amount of sulfur, phosphorus and carbon on a diesel catalyst after aging on a diesel engine bench, as a function of the platinum loading, and of the composition of the fuel and the engine lubricating oil. (Reprinted with permission from ref [69], C 1992 Society of Automotive Engineers, Inc.)...

Figure 111. Emission of aldehydes, acrolein and various polynuclear aromatic hydrocarbons of two passenger cars equipped with an IDI/NA and with a DI/NA diesel engine, once without and once with a diesel oxidation catalyst, in the US-FTP 75 vehicle test cycle (monolith catalyst with 62 cells cm dedicated diesel washcoat formulation with a platinum loading of 1.76 g 1 in the fresh state vehicle dynamometer tests according to the US-FTP 75 vehicle test procedure, with passenger cars equipped with a DI/NA and with an IDI/NA diesel engine of displacement 2.0 1). Reprinted with permission from ref [70], 1990 Society of Automotive Engineers, Inc.

Platinum based catalysts to reduce NO in the exhaust gas of diesel engines with hydrocarbon addition have been proved successful under the dynamic conditions that occur during an activity test with a vehicle. As shown in Fig. 114, the degree of NOv conversion depends primarily on the exhaust gas temperature during the different phases of the vehicle test. In addition to the exhaust gas temperature, the space velocity (Fig. 115), the NO concentration (Fig. 116), the hydrocarbon concentration (Fig. 117), and the type of hydrocarbon (Fig. 118) have a strong impact on the overall NO conversion [71, 72]. 

The soot from diesel engines and wood smoke carry mutagenic polycyclic aromatic hydrocarbons and their nitro derivatives.45 Some typical ones are shown in 15.1, the first being a potent mutagen in the Ames Salmonella test. Catalytic afterburners (containing platinum) are now required... 

The work presented in this paper is the first part of a project aiming at the development of tailor-made oxidation catalysts for diesel engines fuelled by alcohol fuels, ethanol or methanol. The investigation is focused on the influence of support material on the low temperature oxidation of ethanol and acetaldehyde. The study presents results from an experimental investigation with precious metal catalysts applied on monolithic cordierite substrates. Platinum or palladium were applied onto a support consisting of either aluminum oxide, cerium dioxide, silicon dioxide or titanium dioxide. 

Moldovan M, Rauch S, Gomez M, Palacios M, Morrison GM (2001) Bioaccumulation of palladium, platinum and rhodium fixrm urban particulates and sediments by the freshwater isopod Asellus aquaticus. Water Res 35 4175-4183 Moldovan M, Palacios MA, Gomez MM, Morrison G, Rauch S, McLeod C, Ma R, Caroli S, Alimonti A, Petrucci F, Bocca B, Schramel P, Zischka M, Pettersson C, Wass U, Luna M, Saenz JC, Santamarfa J (2002) Environmental risk of particulate and soluble platinum group elements released from gasoline and diesel engine eatalytic converters. Sci Total Environ 296 199-208... 

Also for oxidation reactions, the choice of the alumina support mainly depends on two criteria the stability of the phase at the reaction temperature and the reactivity (or better the lack thereof) toward feed components and products. For example, ethylene oxychlorination to ethylenedichloride is performed at approximately 220-250° C and 5-6 atm in the presence of a y-Al203-supported catalyst, which has a surface area of from 100 to 200 m and contains 10wt% CUCI2 and 3 wt% KCl, (423,424). Another example is a process called ammonia selective oxidation (ASO, or also selective catalytic oxidation, SCO), which converts small amounts of NH3 from waste gases to N2 at reaction temperatures of 150—300 °C. The process is used to abate the ammonia sHp after a selective catalytic reduction process with ammonia or urea in diesel-engine-exhaust after-treatment (425). The patented catalyst consists of Y-AI2O3 (60—300 m g ) loaded with 0.5-4 wt% platinum and 0.5—4 wt% vanadia and is coated onto the surface of a ceramic or metallic monoftthic structure (426). 

Sampara CS, Bissett EJ, Chmielewski M, Assanis D (2007) Global Kinetics for Platinum Diesel Oxidation Catalysts. Industrial Engineering Chemistry Research 46 7993-8003... 

Recently, perovskite-type oxides have been assessed as promising components of NSR systems as they demonstrated higher NO-to-N02 conversions than a commercial platinum-based diesel oxidation catalyst [81]. In the next section, few indicative, not exhaustive but interesting cases of perovskite applications in diesel engine de-NO technology will be presented and discussed. 

The concentration of the active metal usually ties in the range 0.35-1.76 g titerSmaller volumes of catalyst are required for diesel engines than for gasoline engines, and this results in a higher space velocity. Palladium catalysts have a lower activity for the oxidation of sulfur dioxide than platinum catalysts. Nevertheless, a lower metal content is used at the present time to avoid excessive oxidation of sulfur dioxide to the trioxide. 

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