Effects of sulfur content on particulate matter emitted from diesel engine

A diesel engine with and without diesel oxidation catalyst (DOC) was used to study the effects of sulfur content on particulate matter. Number concentration and size distribution were measured in real time by Electrical Low Pressure Impactor. A pump of 80 L/min and sampler with Teflon filters were used to sample engine particles. The abio-salt components and water-soluble ions were analyzed by inductive coupled plasma-atomic emission spectroscopy (ICP-AES) and ion chromatography (IC) respectively. Results show that, at engine speeds 2 690 r/min and 3 200 r/min and loads of 50% and 100%, the number concentration of nucleation mode particles decreases while the number concentration of accumulation mode particles and coarse mode particles increase by 40% to 80% with increasing sulfur content. At engine speed 2 690 r/min and full load, emission concentration of Na, K, Mg, Ca and SO₄^2- increase with increasing sulfur content, and SO₄^2- emission concentration of high sulfur (1 000×10^-6) diesel is 17.5 times of that of low sulfur (19×10^-6) diesel. For diesel engine with DOC, at engine speeds of 2 125 r/min, 2 690 r/min and 3 200 r/min and load of 50%, conversion efficiency of DOC reduces by 5% to 20% with increasing sulfur content.