Development of DPF System for Commercial Vehicles - Pre-Catalyst Supporting to Active Regeneration (3rd Report)

The active regeneration method of a DPF system wherein fuel is supplied to a pre-catalyst with post-injection to cause filter heat-up, was described in previous reports. To succeed in the active regeneration, a pre-catalyst must have high fuel combustion performance at low temperature. Platinum (Pt) had been used as active species of the pre-catalyst. This conventional catalyst was improved by the addition of Palladium (Pd). Fundamental experiments for the catalyst have shown that Pd is very effective for fuel combustion and optimization of the ratio of Pd to Pt causes enhanced NO₂ formation to contribute to lengthen the interval between active regenerations. The high performance and enough heat resistance of the newly developed pre-catalyst have been confirmed by engine test.