Palladium diesel engines

Figure 106. Conversion of carbon monoxide, gaseous hydrocarbons and sulfur dioxide reached over diesel oxidation catalysts as a function of the preeious metal formulation at equimolar loading (monolith catalyst with 62 cells cm - dedicated diesel washeoat formulations with platinum, palladium and rhodium at an equimolar loading of 8 mmol I, fresh model gas test at a gas temperature at catalyst inlet of 723 K a space velocity 50000Nil h model gas simulates the exhaust gas composition of an IDl passenger car diesel engine at medium load and speed and contains 100 vol. ppm SO2). Reprinted with permission from ref. [68], C 1991 Society of Automotive Engineers, Inc.

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).

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... 

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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