화학공학소재연구정보센터
Journal of Molecular Catalysis A-Chemical, Vol.228, No.1-2, 275-282, 2005
Improved sulfur resistance of Pt-Sn/gamma-Al2O3 catalysts for C3H8-NO-O-2 reaction under lean conditions due to Pt-Sn
The selective catalytic reduction (SCR) of NO with C3H8 was studied over unsulfated and pre-sulfated 1% Pt/gamma-Al2O3, and 1% Pt-2% Sn/gamma-Al2O3 catalysts. Carbon residues deposited were evaluated on all samples, after 12 h of C3H8-NO-O-2-SO2 reaction. X-ray photoelectron spectra (XPS) were recorded over unsulfated and pre-sulfated fresh samples. Pre-sulfated 1% Pt-2% Sn/gamma-Al2O3 catalyst showed a high resistance to deactivation by sulfur during C3H8-NO-O-2-SO2 reactions. Results are explained on basis of the effect of tin addition to 1% Pt/gamma-Al2O3 that results in (i) lowering the sulfates generated over the surface of the catalyst during sulfation; and (ii) preventing Pt particles from sintering during sulfation process. We also investigated the effect of Sn addition to 1% Pt/gamma-Al2O3 catalyst, and the effect of pre-sulfation on 1% Pt/gamma-Al2O3 and 1% Pt-2% Sn/gamma-Al2O3, on carbon depositions over the catalysts. Results showed a strong diminution of carbon depositions on sulfated 1% Pt-2% Sn/gamma-Al2O3 due to Pt-Sn surface interactions. The facts that tin addition to a Pt/gamma-Al2O3 catalyst, prevents Pt particles from sintering during high temperature sulfation and that sulfating a 1% Pt-2% Sn/gamma-Al2O3 catalyst prevents carbon residues deposition over the catalyst. suggest that this catalyst could resist high temperature reactions during automotive exhaust control without deactivation. (C) 2004 Elsevier B.V. All rights reserved.