Investigation on SCR Activity of Ag-Pt-W/TiO2 Catalyst

Öz

In this study, the effect of catalyst containing silver (Ag)-platinum (Pt)-tungsten (W) on the selective catalytic reduction (SCR) of nitrogen oxides (NOx) was investigated. Cordierite was used as catalyst support material and catalyst production was carried out by impregnation method. Before coating, the cordierite material was pre-treated with 40% oxalic acid solution and made ready for coating by increasing the surface area. After coating, the catalyst was characterized by BET analysis. When the surface area of not pre-treated cordierite and synthesized catalyst was compared, it was found that the surface area of the catalyst was approximately 60.76 times higher. The activity of the Ag-Pt-W/TiO2 catalyst within the temperature range of 200 to 270 °C, at three different space velocities (40000 h-1, 50000 h-1, 60000 h-1) and four different engine loads (1 kW, 2 kW, 3 kW 4 kW) has been investigated. It was found that the catalytic activity increased with the increase in temperature but decreased with the increase in the engine load. The highest NOx conversion ratio of the catalyst was found to be 86.1%, which was achieved at 40000 h-1 space velocity, 270 °C temperature and 4 kW engine load.

Anahtar Kelimeler

• Ethanol
• Catalyst
• NOx
• SCR

Ag-Pt-W/TiO2 Katalizörünün SCR Aktivitesinin Araştırılması

Öz

Bu çalışmada gümüş (Ag)-platin (Pt)-tungsten (W) içeren katalizörün azot oksitlerin (NOx) seçici katalitik indirgenmesine (SCR) etkisi araştırılmıştır. Katalizör destek materyali olarak kordiyerit kullanılmış olup katalizör üretiminde daldırma yöntemi kullanılmıştır. Kaplamadan önce kordiyerit materyali %40’lık okzalik asit çözeltisiyle ön muamele işleminden geçirilmiş ve yüzey alanı arttırılarak kaplamaya hazır hale getirilmiştir. Kaplama işleminden sonra BET analizi ile katalizör karakterize edilmiştir. Sentezlenen katalizör ile ön muamele işleminden geçirilmeyen kordiyeritin yüzey alanı karşılaştırıldığında, katalizörün yüzey alanının yaklaşık olarak 60,76 kat fazla olduğu tespit edilmiştir. Ag-Pt-W/TiO2 katalizörünün aktivitesi 200 ile 270 °C sıcaklık aralığında, üç farklı akış hızında (40000 h-1, 50000 h-1, 60000 h-1) ve dört farklı motor yükünde (1 kW, 2 kW, 3 kW, 4 kW) araştırılmıştır. Katalitik aktivitenin sıcaklık artışına bağlı olarak arttığı fakat motor yükü artışına bağlı olarak azaldığı belirlenmiştir. Katalizörün en yüksek NOx dönüşüm oranı %86,1 olarak bulunmuştur ve bu değer 40000 h-1 akış hızında, 270 °C sıcaklıkta ve 4 kW motor yükünde elde edilmiştir.

Anahtar Kelimeler

• Etanol
• Katalizör
• NOx
• SCR

Kaynakça

1. 1. Casapu, M., Bernhard, A., Peitz, D., Mehring, M., Elsener, M., Kröcher, O., 2011. A Niobia- Ceria Based Multi-purpose Catalyst for Selective Catalytic Reduction of NOx, Urea Hydrolysis and Soot Oxidation in Diesel Exhaust. Applied Catalysis B: Environmental, 103, 79–84.
2. 2. Sawatmongkhon, B., 2011. Modelling of Catalytic Aftertreatment of NOx Emissions Using Hydrocarbon as a Reductant. The University of Birmingham, Doctor of Philosophy.
3. 3. Reşitoğlu, İ.A., Altınışık, K., Keskin, A., 2015. The Pollutant Emissions from Diesel-engine Vehicles and Exhaust Aftertreatment Systems. Clean Technologies and Environmental Policy, 17, 15–27.
4. 4. Valanidou, L., Theologides, C., Zorpas, A.A., Savva, P.G., Costa, C.N., 2011. A Novel Highly Selective and Stable Ag/MgO-CeO2-Al2O3 Catalyst for the Low- temperature Ethanol-SCR of NO. Applied Catalysis B: Environmental, 107, 164-176.
5. 5. Shan, W., Liu, F., He, H., Shi, X., Zhang, C., 2012. An Environmentally-benign CeO2-TiO2 Catalyst for the Selective Catalytic Reduction of NOx with NH3 Insimulated Diesel Exhaust. Catalysis Today, 184, 160–165.
6. 6. Wang, J., Liu, Z., Feng, G., Chang, L., Bao, W., 2012. In Situ Synthesis of CuSAPO- 34/Cordierite and its Selective Catalytic Reduction of Nitrogen Oxides in Vehicle Exhaust the Effect of HF. Fuel, 109, 101-109.
7. 7. Hsieh, M.F., Wang, J., 2011. Design and Experimental Validation of an Extended Kalman Filter-based NOx Concentration Estimator in Selective Catalytic Reduction System Applications. Control Engineering Practice, 19, 346-353.
8. 8. Mrad, R., Aissat, A., Cousin, R., Courcot, D., Siffert, S., 2015. Catalysts for NOx Selective Catalytic Reduction by Hydrocarbons (HC-SCR). Applied Catalysis A.: General, 504, 542-548.

9. 9. Zhang, C., He, H., Shuai, S., Wang, J., 2007. Catalytic Performance of Ag/Al2O3-C2H5OH- Cu/Al2O3 System for the Removal of NOx from Diesel Engine Exhaust. Environmental Policy, 147, 415-421.
10. 10. Li, F., Shen, B., Tian, L., Li, G., He, C., 2016. Enhancement of SCR Activity and Mechanical Stability on Cordierite Supported V2O5- WO3/TiO2 Catalyst by Substrate Acid Pretreatment and Addition of Silica. Powder Technology, 297, 384-391.
11. 11. Popovych, N.O., Kyriienko, P.I., Soloviev, S.O., Orlyk, S.M., Dzwigaj, S., 2016. Influence of Partial Dealumination of BEA Zeolites on Physicochemical and Catalytic Properties of AgAlSiBEA in H2-promoted SCR of NO with Ethanol. Microporous and Mesoporous Materials, 226, 10-18.
12. 12. Wang, J., Peng, Z., Chen, Y., Bao, W., Chang, L., Feng, G. 2015. In-situ Hydrothermal Synthesis of Cu-SSZ-13/cordierite for the Catalytic Removal of NOx from Diesel Vehicles by NH3. Chemical Engineering Journal, 263, 9-19.
13. 13. Popovych, N.O., Soloviev, S.O., Orlyk, S.M., 2016. Selective Reduction of Nitrogen Oxides (NOx) With Oxygenates and Hydrocarbons Over Bifunctional Silver-alumina Catalysts: a Review. Theoretical Experimental Chemistry, 226 10-18.
14. 14. Yeom, Y.H., Li, M., Sachtler, W.M.H., Weitz, E., 2006. A Study of the Mechanism for NOx Reduction with Ethanol on γ-alumina Supported Silver. Journal of Catalysis, 238 100-110.
15. 15. Yu, Y., He, H., Feng, Q., Gao, H., Yang, X., 2004. Mechanism of the Selective Catalytic Reduction of NOx by C2H5OH Over Ag/Al2O3. Applied Catalysis B: Environmental, 49, 159–171.
16. 16. Silva, R., Cataluna, R., Martinez-Arias, A., 2009. Selective Catalytic Reduction of NOx Using Propene and Ethanol Over Catalysts of Ag/ Al2O3 Prepared by Microemulsion and Promotional Effect of Hydrogen. Catalysis Today, 143, 242-246.
17. 17. Tamaldin, N., 2010. Experimental Investigation of Emission from a Light Duty Diesel Engine Utilizing Urea Spray SCR System. Coventry University, Doctor of Philosophy.
18. 18. Cao, L., Wu, X., Xu, Y., Lin, Q., Hu, J., Chen, Y., Ran, R., Wen, D., 2019. Ceria-modified WO3-TiO2-SiO2 Monolithic Catalyst for High Temperature NH3-SCR. Catalysis Communications, 120, 55-58.
19. 19. Chen, H., Xia, Y., Fang, R., Huang, H., Gan, Y., Liang, C., Zhang, J., Zhang, W., Liu, X., 2018. The Effects of Tungsten and Hydrothermal Aging in Promoting NH3-SCR Activity on V2O5/WO3-TiO2 Catalysts. Applied Surface Science, 459, 639-646.
20. 20. Dong, H., Shuai, S., Li, R., Wang, J., Shi, X., He, H., 2008. Study of NOx Selective Catalytic Reduction by Ethanol Over Ag/Al2O3 Catalyst on a HD Diesel Engine. Chemical Engineering Journal, 135, 195-201.
21. 21. Resitoglu, I.A., Altinisik, K., Keskin, A., Ocakoglu K., 2020. The Effects of Fe2O3 Based DOC and SCR Catalyst on the Exhaust Emissions of Diesel Engines. Fuel, 262, 116501.
22. 22. Keskin, A., Yaşar, A., Candemir, O.C., Özarslan, H., 2020. Influence of Transition Metal Based SCR Catalyst on the NOx Emissions of Diesel Engine at Low Exhaust Gas Temperatures. Fuel, 273, 117785.