Durability of V2O5-WO3/TiO2 selective catalytic reduction catalysts for heavy-duty diesel engines using B20 blend fuel

• Published in: Energy (Oxford) 2019-07, Vol.179, p.383-391
• Main Authors: Tan, Pi-qiang, Wang, Shi-yan, Hu, Zhi-yuan, Lou, Di-ming
• Format: Article
• Language: English
• Subjects: Anatase; Biodiesel fuels; Biofuels; Catalysis; Catalyst characterization; Catalysts; Cross-sections; Deterioration; Diesel; Diesel engine; Diesel engines; Durability; Durability test; Exhaust gases; Flow rates; Flow velocity; Fluorescence; Internal combustion engines; Nitrogen oxides; NOx emissions; Performance degradation; Selective catalytic reduction; Specific surface; Surface area; Titanium dioxide; Tungsten oxides; Vanadium pentoxide; X-ray diffraction; X-ray fluorescence
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2019.04.149

The durability of V2O5-WO3/TiO2 selective catalytic reduction (SCR) catalysts for heavy-duty diesel engines was evaluated based on 500 h SCR durability tests conducted using B20 fuel (20% v/v biodiesel + 80% v/v petroleum diesel). The fresh and deteriorated SCR catalysts were characterized by X-ray fluorescence, X-ray diffraction, and Brunauer-Emmett-Teller surface area measurements to investigate the deterioration mechanism of the catalysts. The results show that the SCR de-NOx performance is degraded after SCR durability testing, particularly at high engine speeds. The NOx conversion efficiency of the deteriorated SCR catalysts decreases at temperatures above 400 °C but remains high at temperatures between 250 and 400 °C. The catalyst characterization results reveal that the deterioration in the de-NOx performance is not owing to anatase-to-rutile transformation of TiO2, but because of a decrease in the specific surface area and the loss of the catalyst components, which are greater in the front cross section of the SCR than in the rear cross section. For a given catalyst cross section, the decrease in the specific surface area exhibits a positive correlation with the flow rate of the exhaust gas. •SCR performance decreases after durability testing, especially at high engine speeds.•NOx conversion efficiency of deteriorated catalysts decreases at high temperatures.•Deterioration of catalysts in front of SCR is more serious than in rear.•Deterioration is due to a decrease in specific surface area and catalyst components.•Anatase-to-rutile transformation of TiO2 does not happen, not cause of deterioration.