Effects of Electrically Heated Catalyst on the Low Temperature Performance of Vanadium-Based SCR Catalyst on Diesel Engine

The NOx conversion efficiency of vanadium-based SCR catalyst is lower under low temperature. Utilizing an exhaust analyzer, the effects of electrically heated catalyst on the performance of vanadium-based SCR catalyst under low temperature was studied on the engine test bench. The inlet temperature of SCR catalyst without the electrically heated catalyst were in the range of 150°C∼270°C under various steady engine modes, and the NSR (Normalized Stoichiometric Ratio) was set as 0.4,0.6,0.8,1.0. The results showed that under the space velocity of 20000h⁻¹, with the application of the electrically heated catalyst, the inlet temperature of SCR increased about 19.9°C on average and the NOx conversion efficiency improved about 8.0%. The NOx conversion efficiency increased 1.7%∼8.6% at the temperatures of 150°C∼174°C, and 1.0%∼15.9% at the temperatures of 186°C∼270°C. The experiment space velocity properties indicated that with the electrically heated catalyst, the inlet temperature increase and the increasing rate of the NOx conversion efficiency both decreased with the increasing space velocity. At the inlet temperature of 210°C before the heater was activated, the inlet temperature increased 16.1°C∼30.4°C under various space velocities and the NOx conversion efficiency increased 6.4%∼18.7%.