抄録
Porous metal oxide particles were prepared by freeze-drying to serve as combustion bulk catalysts for diesel soot. Copper oxide-based catalysts were prepared as follows: Aqueous copper sulfate solutions mixed with other metal sulfate solutions were utilized as starting materials for freeze-drying. Spherical drops of the solutions were instantly frozen in a liquid nitrogen bath. The frozen particles were dried in a vacuum chamber. And then, these were calcined into metal oxide particles, and subsequently fired to yield durable strength. The open porosity induced by sublimation of ice crystals in the freeze-dried particles was retained during calcination and firing. These porous particles would be directly utilized for the bulk catalyst packed in the diesel soot trap. The thermal analysis, TG-DTA was employed to evaluate the activity of the catalysts for the oxidation of soot from diesel exhaust and amorphous carbon powders. The mixing of carbon powder with catalysts was carried out in an agate mortar. The mixed samples were submitted to thermal analysis. The starting temperature of carbon oxidation was measured. To achieve intimate contact between catalyst and carbon powder, some metal chlorates were added to the samples expecting to form liquid phase during carbon combustion. The appearance activation energy of soot combustion was assessed for activity comparison. Among the prepared catalysts, CuO/Co3O4 with KCl- FeCl2 exhibited appreciable activity and durability, showing the ignition temperature about 300°C.
