Search Results

The purpose of this study is to evaluate catalysts suitable for the reduction of particulate emissions from heavy duty diesel engines over the European R49 cycle. Catalyst formulations were screened in a laboratory reactor in order to select promising candidates for further evaluation in test engines. The approach was to evaluate different support materials in relation to storage of sulphates and the optimisation of precious metal loadings with promotors and inhibitors. The objective was to obtain the optimum balance between gaseous activity and particulate control. Catalysts selected from the screening process were installed on a test bed engine. Emissions were measured over the European R49 test procedure, to determine the effect of fuel properties on catalyst efficiency and exhaust emissions. The test engine was selected to represent the technology used to meet Euro 1 emissions standards (1992/3).

Flow-through diesel oxidation catalysts (DOC's) have been shown to be an effective means of reducing emissions from diesel engines. In this work, the further development of diesel oxidation catalysts for the control of emissions from heavy duty engines is illustrated. Laboratory reactor and engine dynamometer data obtained from engine-based accelerated poisoning and aging studies demonstrate that HC, CO and SO2 oxidation by DOC's can be modified by adjusting platinum and vanadium loadings in alumina-based Pt/V catalyst formulations. The performance and durability of this type of catalyst system are demonstrated with several aging cycles on heavy-duty engines. The fresh performance of two catalyst systems was determined on both US Heavy Duty Transient and ECE-R49 Test cycles with a 1991 calibration Perkins Phaser 6.0 L engine. Gas phase emissions were reduced by a similar amount for both catalysts over both cycles (HC: 60-70%, CO: 45-75%).