Cesium as Alkali Promoter in Me-Cs (Me = Cu, Co, Fe)/ Al₂O₃ Structured Catalysts for the Simultaneous Removal of Soot and NO_x

Sonia Ascaso, María Elena Gálvez, Rafael Moliner, María Jesús Lázaro

Instituto de Carboquímica, Consejo Superior de Investigaciones Científicas, Miguel Luesma Castán, Zaragoza, Spain.

DOI: 10.4236/mrc.2013.23009                

Abstract

Structured catalysts for the simultaneous removal of soot and nitrogen oxides were prepared by means of coating cordierite monoliths with alumina-based suspensions containing Cu, Co or Fe and Cs as the catalytically active phase. Textural and chemical properties of the coated monoliths were determined by means of N₂-physisorption, SEM and temperature programmed reduction. Their activity in the simultaneous removal of soot and NO_x was assayed in a lab-scale installation, using a carbon black as diesel surrogate. Catalysts containing Cs exhibited significant activity in deNO_x, however soot oxidation activity is poorly enhanced probably due to the low NO₂ evolution, pointing to a different NO_x adsorption mechanism in the present case, in comparison to previous observations on analogous K and Ba containing catalysts.

Keywords

Exhaust Gas Cleaning; NOx Selective Reduction; Soot Oxidation; Cesium; Washcoating; Structured Catalysts

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	R. J. Farrauto and K. E. Voss, “Monolithic Diesel Oxidation Catalysts,” Applied Catalysis B: Environmental, Vol. 10, No. 1-3, 1996, pp. 29-51. doi:10.1016/0926-3373(96)00022-7
[2]	P. Ciambellia, P. Corbob and F. Migliardinib, “Potentialities and Limitations of Lean De-NOx Catalysts in Reduc- ing Automotive Exhaust Emissions,” Catalysis Today, Vol. 59, No. 3-4, 2000, pp. 279-286. doi:10.1016/S0920-5861(00)00294-7
[3]	European Regulation, “Regulation EC N. 715/2007”. http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2007:171:0001:0016:EN:PDF
[4]	A. Boyano, M. J. Lázaro, C. Cristiani, F. J. Maldonado-Hodar, P. Forzatti and R. Moliner, “A Comparative Study of V2O5/AC and V2O5/Al2O3 Catalysts for the Selective Catalytic Reduction of NO by NH3,” Chemical Engineering Journal, Vol. 149, No. 1-3, 2009, pp. 149-173. doi:10.1016/j.cej.2008.10.022
[5]	A. Boyano, N. Lombardo, M. E. Gálvez, M. J. Lázaro and R. Moliner, “Vanadium-Loaded Carbon-Based Monoliths for the On-Board NO Reduction: Experimental Study of Operating Conditions,” Chemical Engineering Journal, Vol. 144, No. 3, 2008, pp. 343-351. doi:10.1016/j.cej.2008.01.037
[6]	I. P. Kandylas, O. A. Haralampous and G. Koltsakis, “Diesel Soot Oxidation with NO2: Engine Experiments and Simulations,” Industrial and Engineering Chemistry Re- search, Vol. 41, No. 22, 2002, pp. 5372-5384.
[7]	S. Matsumoto. “Recent Advances in Automobile Exhaust Catalysts,” Catalysis Today, Vol. 90, No. 3-4, 2004, pp. 183-190. doi:10.1016/j.cattod.2004.04.048
[8]	A. Setiabudi, B. A. A. L. van Setten, M. Makkee and J. A. Moulijn, “The Influence of NOx on Soot Oxidation Rate: Molten Salt versus Platinum,” Applied Catalysis B: Envi- ronmental, Vol. 35, No. 3, 2002, pp. 159-166. doi:10.1016/S0926-3373(01)00251-X
[9]	O. Salvat, P. Marez and G. Belot, “Passenger Car Serial Application of a Particulate Filter System on a Common Rail Direct Injection Diesel Engine,” SAE Technical Paper 2000-01-0473, 2000.
[10]	B. R. Stanmore, J. F. Brihlac and P. Gilot, “The Oxidation of Soot: A Review of Experiments, Mechanisms and Models,” Carbon, Vol. 39, No. 15, 2001, pp. 2247-2268. doi:10.1016/S0008-6223(01)00109-9
[11]	K. Hizbul, S. Kureti and W. Weisweiler, “Potassium Pro-Moted Iron Oxide Catalysts for Simultaneous Catalytic Removal of Nitrogen Oxides and Soot from Diesel Exhaust Gas,” Catalysis Today, Vol. 93-95, 2004, pp. 839-843. doi:10.1016/j.cattod.2004.06.094
[12]	N. Neja and M. J. Illán-Gómez, “Potassium-Copper and Potassium-Cobalt Catalysts Supported on Alumina for Simultaneous NOx and Soot Removal from Simulated Diesel Engine Exhaust,” Applied Catalysis B: Environmental, Vol. 70, No. 1-4, 2007, pp. 261-226. doi:10.1016/j.apcatb.2006.03.026
[13]	D. Fino, P. Fino, G. Saracco and V. Specchia, “Studies on Kinetics and Reactions Mechanism of La2?xKxCu1?yVyO4 Layered Perovskites for the Combined Removal of Diesel Particulate and NOx,” Applied Catalysis B: Environmental, Vol. 43, No. 3, 2003, pp. 243-259. doi:10.1016/S0926-3373(02)00311-9
[14]	V. G. Milt, E. D. Banus, M. A. Ulla and E. E. Miró, “Soot Combustion and NOx Adsorption on Co,Ba,K/ZrO2,” Catalysis Today, Vol. 133-135, 2008, pp. 435-440. doi:10.1016/j.cattod.2007.11.013
[15]	H. Lin, Y. Li, W. Shangguan and Z. Huang, “Soot Oxida-Tion and NOx Reduction over BaAl2O4 Catalyst,” Combustion Flame, Vol. 156, No. 11, 2009, pp. 2063-2070. doi:10.1016/j.combustflame.2009.08.006
[16]	W. F. Shangguan, Y. Teraoka and S. Kagawa, “Promotion Effect of Potassium on the Catalytic Property of CuFe2O4 for the Simultaneous Removal of NO(x) and Diesel Soot Particulate,” Applied Catalysis B: Environmental, Vol. 16, No. 2, 1998, pp. 149-154. doi:10.1016/S0926-3373(97)00068-4
[17]	M. E. Gálvez, S. Ascaso, R. Moliner and M. J. Lázaro. “Me (Cu, Co, V)-K/Al2O3 Supported Catalysts for the Simultaneous Removal of Soot and Nitrogen Oxides from Diesel Exhausts,” Chemical Engineering Science, Vol. 87, 2013, pp. 75-90. doi:10.1016/j.ces.2012.10.001
[18]	R. Matarrese, L. Castoldi, L. Lietti and P. Forzatti, “Soot Combustion: Reactivity of Alkaline and Alkaline Earth Metal Oxides in Full Contact with Soot,” Catalysis Today, Vol. 136, No. 1-2, 2008, pp. 11-17. doi:10.1016/j.cattod.2008.03.022
[19]	L. Castoldi, R. Matarrese, L. Lietti and P. Forzatti, “Intrinsic Reactivity of Alkaline and Alkaline-Earth Metal Oxide Catalysts for Oxidation of Soot,” Applied Catalysis B: Environmental, Vol. 90, No. 1-2, 2009, pp. 278-285. doi:10.1016/j.apcatb.2009.03.022
[20]	A. Setiabudi, N. K. Allaart, M. Makkee and J. A. Moulijn, “In Situ Visible Microscopic Study of Molten Cs2SO4?V2O5-Soot System: Physical Interaction, Oxidation Rate, and Data Evaluation,” Applied Catalysis B: Environmental, Vol. 60, No. 3-4, 2005, pp. 233-243. doi:10.1016/j.apcatb.2005.03.005
[21]	A. Aissat, S. Siffert and D. Courcot, “Investigation of Cs-Cu/ZrO2 Systems for Simultaneous NOx Reduction and Carbonaceous Particles Oxidation,” Catalysis Today, Vol. 191, No. 1, 2012, pp. 90-95. doi:10.1016/j.cattod.2012.01.020
[22]	N. F. Galdeano, A. L. Carrascull, M. I. Ponzi, I. D. Lick and E. N. Ponzi, “Catalytic Combustion of Particulate Matter: Catalysts of Alkaline Nitrates Supported on Hydrous Zirconium,” Thermochimica Acta, Vol. 421, No. 1-2, 2004, pp. 117-121. doi:10.1016/j.tca.2004.04.006
[23]	M. Boutros, J.-M. Trichard and P. Da Costa, “Effect of the Synthesis Method on Alumina Supported Silver Based Catalyst for NOx Selective Reduction by Ethanol,” Topics in Catalysis, Vol. 52, No. 13-20, 2009, pp. 1781-1785. doi:10.1007/s11244-009-9335-9
[24]	C. Cristiani, A. Grossale and P. Forzatti, “Study of the Physico-Chemical Characteristics and Rheological Behaviour of Boehmite Dispersions for Dip-Coating Applications,” Topics in Catalysis, Vol. 42-43, No. 1-4, 2007, pp. 455-459. doi:10.1007/s11244-007-0224-9
[25]	N. R. Peela, A. Muyabi and D. Kunzru, “Washcoating of γ-Alumina on Stainless Steel Microchannels,” Catalysis Today, Vol. 147, 2009, pp. S17-S23. doi:10.1016/j.cattod.2009.07.026
[26]	F. Bonnefoy, P. Gilot, B. R. Stanmore and G. Prado, “A Comparative Study of Carbon Black and Diesel Soot Reactivity in the Temperature Range 500 – 600°C -effect of additives,” Carbon, Vol. 32, No. 7, 1994, pp. 1333-1340. doi:10.1016/0008-6223(94)90120-1
[27]	M. E. Gálvez, S. Ascaso, R. Moliner, R. Jiménez, X. García, A. Gordon and M. J. Lázaro, “Catalytic Filters for the Simultaneous Removal of Soot and NOx: Effect of CO2 and Steam on the Exhaust Gas of Diesel Engines,” Catalysis Today, Vol. 176, No. 1, 2011, pp. 134-138. doi:10.1016/j.cattod.2011.01.030
[28]	M. E. Gálvez, S. Ascaso, I. Tobías, R. Moliner and M. J. Lázaro, “Catalytic Filters for the Simultaneous Removal of Soot and NOx: Influence of the Alumina Precursor on Monolith Washcoating and Catalytic Activity,” Catalysis Today, Vol. 191, No. 1, 2012, pp. 96-105. doi:10.1016/j.cattod.2011.12.012
[29]	M. E. Gálvez, S. Ascaso, R. Moliner and M. J. Lázaro, “Influence of the Alkali Promoter on the Activity and Stability of Transition Metal (Cu, Co, Fe) Based Structured Catalysts for the Simultaneous Removal of Soot and NOx,” Topic in Catalysis, in Press.
[30]	M. Colic, G. V. Franks, M. L. Fisher and F. F. Lange, “Effect of Counterion Size on Short Range Repulsive Forces at High Ionic Strengths,” Langmuir, Vol. 13, No. 12, 1997, pp. 3129-3135. doi:10.1021/la960965p
[31]	B. R. Stanmore, V. Tschamber and J. F. Brilhac, “Oxidation of Carbon by NOx, with Particular Reference to NO2 and N2O,” Fuel, Vol. 87, No. 2, 2008, pp. 131-146. doi:10.1016/j.fuel.2007.04.012