Catalytic Combustion of Diesel Soot on Co-Sr-K Catalysts

摘要

The catalytic activities of Co_3O_4, Sr(NO_3)_2, Co-Sr, and Co-Sr-K catalysts were studied, and the effect of the contact mode on the soot onset ignition temperature and soot oxidation rate was also discussed. All the catalysts were characterized by X-ray diffraction and thermogravimetry/differential scanning calorimetry. The catalytic activities were evaluated by a soot oxidation reaction using the temperature-programmed reaction system. The soot onset ignition temperature is 370 °C for Co-Sr catalysts with molar ratios of 1:1 and 2:1, which is the same as that of pure Co_3O_4. The Co-Sr catalysts containing KNO_3 can greatly lower the soot onset ignition temperature. The catalytic activity of pure Co_3O_4 and Sr(NO_3)_2 is affected by catalysts-soot contact intensity, which has nearly no effect on the soot onset ignition temperature and soot oxidation rate for Co-Sr catalysts with appropriate ratios. The cooperation of CO_3O_4 and Sr(NO_3)_2 can accelerate the soot oxidation rate and reduce the effect of the soot-catalyst contact mode on catalytic activity. The soot onset ignition temperature is not affected by contact intensity for the catalysts with proper Co-Sr-K ratios, which shows that the cooperation of Co_3O_4, Sr(NO_3)_2, and KNO_3 can lower the soot onset ignition temperature whether in the tight contact mode or in the loose contact mode. The soot oxidation rate is greatly accelerated when the Co-Sr-K catalysts and soot are in the tight contact mode.