OP-II-3

PP-III-8brevity, the results of the catalytic activity tests are shown only forLa 0.7 Sr 0.2 Ce 0.1 Fe 0.9 Pd 0.1 O 3 , which was selected as the best catalyst on the grounds oftemperature programmed reduction (TPR), desorption (TPD), and reaction (TPRe),the latter being the NO to N 2 reduction with H 2 , in the absence and in the presence ofO 2 . The catalyst was then deposited over a cordierite substrate (diameter: 35 mm,length: 25 mm, cell density: 200 cpsi), coated with 5wt% γ-alumina, at a loading W/Fequal to 0.02 g . cat s . cm –3 (20 wt%). In Fig. 2-left it appears that for a NO and H 2mixture of 1:10 ppmv, without O 2 , the catalyst has a T 50 equal to 130 °C at 30000 h –1 ,with a complete NO reduction at 200°C. In the presence of O 2 (5 vol%), at least atwo-fold higher H 2 concentration was required to achieve the same NO to N 2reduction obtained with the powder catalyst (Fig. 2-right).Fig. 2. GSHV = 30,000 h –1 . Left: 1,000 ppmv NO, 10,000 ppmv H 2 (♦), N 2 balance;Right: 100 ppmv NO, 1,000 (♦) – 2,000 (▲) – 4,000 (■) ppmv H 2 , 5% O 2, N 2 balance.As compared to other catalysts of H 2 -SCR found in the literature [1-3], the NO xconversion degree is satisfactory since it is reached without the use of Pt, with a lowW/F factor (mass of catalyst over the flow rate), and for temperatures (130°C-150°C)and GHSVs compatible with those of the exhaust line of a diesel passenger car.Studies are now in progress to improve the catalyst selectivity in the presence of O 2 ,minimizing N 2 O and NO 2 porduction for fuel consumption minimization. Hence,presently the fuel penalty is around 4% for a NO x to N 2 conversion of 60%.References[1]. Costa N.C., Savva P.G., Andronikou C., Lambrou P.S., Polychronopoulou K., Belessi V.C.,Stathopoulos V.N., Pomonis P.J., Efstathiou, J. Catal. 2002, 209, 456-471.[2]. Costa N.C, Efstathiou A.M., Appl. Catal. B, 2007, 72, 240-252.[3]. Ferri D., Forni L., Dekkers M.A.P., Nieuwenhuys B.E. Appl. Catal. B, 1998, 16, 339-345.AcknowledgementsThe EU funded project TOP EXPERT is gratefully acknowledged.456