Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

OP-III-14reactivity (compared to other hydrocarbons), and high H/C ratio with favourable consequenceon global warming [5].In this work, we have investigated the properties of a series of catalysts obtained frominert substrates in the shape of plates of different materials characterized by variable thermoconductibility(SiC, α-Al 2 O 3 , FeCrAlloy), that have been coated with a γ-Al 2 O 3 washcoat anda perovskite-type active phase constituted by LaMnO 3 (supported onto alumina pores). Theeffect of doping the active phase with smallamounts of Pt (0.2-1% wt.) has been tested too.All catalysts have been investigated in thecombustion of methane, hydrogen and H 2 -CH 4 60mixtures. A stainless steel reactor has been40accomplished in order to house the catalytic20system and carry out combustion tests. TheT=800°C0reactor design allows to modulate the height of0 2 4 6 8 10Hthe combustion chamber so to change the S/V2/CH 4Fig. 1. CH 4 -H 2 combustion on FeCrAlloy slab(catalyst surface/reactor volume) ratio. The results coated with LaMnO 3 /Al 2 O 3 catalyst at twosurface-to-volume ratiosshow that a little amount of Pt into the perovskitestructure is very effective in enhancing the catalytic activity towards H 2 oxidation,significantly diminishing ignition temperature, while high temperature CH 4 combustion rate isdetermined by perovskite content (the activity towards methane combustion seems to be notaffected at all by the presence of Pt). Particular attention has been devoted to the combustionof the H 2 -CH 4 mixtures. H 2 enrichment of the fuel is effective to enhance CH 4 combustionrate by means of the activation of radical paths in the homogenous phase. Fig. 1 shows thatmethane conversion increases with increasing H 2 content in the fuel (at constant calorificpower of the entire mixture). The results obtained at two S/V ratio are reported; as shown inthe figure, increasing the volume available for the homogeneous reaction, CH 4 totalconversion is obtained at a lower H 2 /CH 4 .References1. C. Fernandez-Pello, P Combust Inst, 29 (2002) 883.2. J.A. Federici, D.G. Norton, T. Bruggemann, K.W. Voit, E.D. Wetzel, D.G. Vlachos, J Power Sources, 161(2006) 1469; W. M. Yang, S. K. Chou, C. Shu, Z. W. Li, H. Xue, J Phys D Appl Phys, 38 (2005) 4252.3. X. Wang, J. Zhu, H. Bau, R.J. Gorte, Catal Lett, 77(4) (2001) 173; C.M. Spadaccini, X. Zhang, C.P. Cadou,N. Miki, I.A. Waitz, Sensor Actuat A-Phys, 103 (2003) 219; D.G. Norton and D.G. Vlachos, P CombustInst, 30 (2005) 2473.4. S. Cimino, L. Lisi, R. Pirone, G. Russo, M. Turco, Catal Today, 59 (2000) 19.5. P. Dagaut, A. Nicolle, P Combust Inst 30 (2005) 2631; O. Deutschmann, L.I. Maier, U. Riedel,A.H. Stroemman, R.W. Dibble, Catal Today, 59 (2000) 141.CH 4Conversion, %10080S/V=2.5 cm -1S/V=10 cm -1118