OP-II-3

PP-III-8DE-NO X SYSTEM BASED ON H 2 -SCR CATALYSTSUBensaid S.U, Russo N., Fino D. 1Dipartimento di Scienza dei Materiali e Ingegneria Chimica - Politecnico di Torino,Corso Duca degli Abruzzi 24, 10129 Turin – ITALYU1H debora.fino@polito.itUThe following after-treatment system is based on the on-board generation ofactivated species, able to reduce NO x emissions from diesel engines. H 2 and CO areproduced through an auto-thermal reforming (ATR) of post-injected fuel, placed as aby-pass of the close coupled DOC (Diesel Oxidation Catalyst) and DPF (DieselParticulate Filter), as depicted in Fig. 1. The proper inlet composition to the reformeris achieved by the simultaneous control ofthe exhaust gas flow rate, split from themain flow by means of a plug valve, and therequired amount of vaporized diesel, fed tothe reformer at the front of the reactor. Infact, an appropriate oxygen to carbon ratiohas to be ensured into the reformer toenhance H 2 selectivity, and consequentlyfor fuel penalty minimization. A sparkignition system is placed to eliminate lightoff issues.Fig. 1. Prototype of the system.Some commercial catalysts were testedin order to investigate the performance of the ATR under such conditions. The testsshow the reformer performance at different oxygen to carbon ratios and spacevelocities. The best operating conditions is at a GSHV of 20400 h –1 , and an oxygento carbon ratio equal to 0.5. At each engine operative condition, given an optimaloxygen to carbon ratio in the ATR, and a required H 2 yield for NO x reduction, fuelconsumption can be evaluated, and the exhaust gases split to the ATR is sizedaccordingly.A series of perovskite-type catalysts (LaFeO 3 , La 0.8 Sr 0.2 FeO 3 ,La 0.8 Sr 0.2 Fe 0.9 Pd 0.1 O 3 , La 0.7 Sr 0.2 Ce 0.1 FeO 3 , La 0.7 Sr 0.2 Ce 0.1 Fe 0.9 Pd 0.1 O 3 ) were preparedby the solution combustion synthesis method and fully characterized by XRD, BET,FESEM and TPD/R analyses. Two of them (Pd/La 0.8 Sr 0.2 FeO 3 ,Pd/La 0.7 Sr 0.2 Ce 0.1 FeO 3 ) were prepared by deposition of the Pd nitrate precursor viaincipient wetness impregnation onto the pre-formed perovskites. For the sake of455