CO tolerance of Pt and Rh catalysts:: effect of CO in the gas-phase oxidation of H2 over Pt and Rh supported catalysts
CO tolerance of Pt and Rh catalysts:: effect of CO in the gas-phase oxidation of H2 over Pt and Rh supported catalysts
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DOI：
10.1016/j.apcatb.2004.07.016
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发表时间：
2005-03-10
影响因子：
22.1
通讯作者：
Ioannides, T
中科院分区：
文献类型：
--
作者：
Avgouropoulos, G;Ioannides, T
用工业Pt/C、Pt-Ru/C和Pt-Sn/C电催化剂，以及实验室制备的Pt和Rh负载于不同载体（γ-Al_2 O_3、TiO_2、TiO_2（WO_3、SiO_2、WO_3、MoO_3和C）上的催化剂，研究了Pt和Rh催化剂在H_2-CO混合气气相氧化中的催化行为。本研究的目的是评估催化剂的CO耐受性，即在CO存在下H-2氧化速率的降低，通常在气相和电化学环境中观察到。一个显着的氢氧化速率下降，高达5个数量级，观察到在CO的存在下。CO抑制强烈依赖于支持的性质。标准Pt/C电催化剂是最不耐CO的催化剂，而Pt-Sn/C，以及Pt和Rh负载在MoO 3和TiO 2基载体上的催化剂是最具活性和耐CO的。实验结果表明，CO抑制是由于CO吸附在线性和/或桥接的形式取决于金属和支持的类型。催化剂的CO耐受性取决于CO和氢在金属表面上的相对吸附强度。CO抑制的模拟表明，在最大和最小CO耐受性催化剂之间，Δ H（CO）（或Δ H（CO）和Δ H（H2）的相对值）可以变化高达20-40 kJ/mol。(C)2004 Elsevier B. V.保留所有权利。
The catalytic behavior of Pt and Rh catalysts during the gas-phase oxidation of H-2-CO mixtures was studied with commercial Pt/C, Pt-Ru/C and Pt-Sn/C electrocatalysts, as well as laboratory prepared catalysts of Pt and Rh supported on various carriers (gamma-Al2O3, TiO2, TiO2(WO3 SiO2, WO3, MoO3 and carbon). The goal of this study was to assess the CO-tolerance of the catalysts, i.e. the lowering of the H-2 oxidation rate in the presence of CO, generally observed both in gas-phase and electrochemical environments. A significant drop of hydrogen oxidation rate, up to 5 orders of magnitude, was observed in the presence of CO. CO inhibition was strongly dependent on the nature of the support. The standard Pt/C electrocatalyst was the least CO-tolerant catalyst among those tested, while Pt-Sn/C, as well as Pt and Rh supported on MoO3 and TiO2-based carriers were the most active and CO-tolerant catalysts. The experimental findings indicate that CO inhibition is due to CO adsorption in linear and/or bridged form depending on the type of metal and support employed. The CO tolerance of the catalysts depends on the relative adsorption strength of CO and hydrogen on the metal surface. Simulation of CO inhibition showed that DeltaH(CO) (or the relative values of DeltaH(CO) and DeltaH(H2)) may vary up to 20-40 kJ/mol between the most and least CO-tolerant catalysts. (C) 2004 Elsevier B.V. All rights reserved.