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The particulate matter emitted by transports, in particular Diesel vehicles, has been considered toxic for many years, and is subject to world-wide emission standards. Recently, size distribution and particulate number has emerged as influential parameters of particulate toxicity. Over the past twenty years, many technologies have been studied for the removal of Diesel particulates. These technologies include numerous kind of traps, that are efficient mainly for solid particles. The work presented here has been devoted to the study of the influence of various traps on particulate size distribution and number, by means of SMPS (Scanning Mobility Particle Sizer) technique, in the exhaust of a VW 1.9 I TDI engine set in an engine test cell. The candidates tested are the well known Corning wall-flow monolith, the 3M wound ceramic fibre cartridge, the Buck knitted fibre cartridge and the HJS/SHW sintered metal trap.

One of the most promising ways to insure the periodic regeneration of a particulate trap, consists of additising the fuel with organo-metallic compounds. The present paper deals with a novel alkali product, able to promote natural regenerations, for exhaust temperatures as low as 200 °C, and treatment rates as low as 5 ppm metal. Tests have been carried out on a soot reactor and on an engine bench, with various trap locations in the exhaust, showing that the regeneration occurrence depends on temperature, soot mass loaded inside the porous structure and engine conditions. A complete trap cleaning still needs gas temperatures up to 400 °C, which can be encountered for high load conditions of the engine.