Department of Industrial Chemistry, Chiang Mai University, Thailand 50200.
Langmuir. 2011 Mar 15;27(6):3138-43. doi: 10.1021/la104637w. Epub 2011 Feb 4.
Adsorption of SO2 on a Pt/C catalyst typically used in proton exchange- membrane fuel cells (PEMFCs) has been investigated by temperature programmed desorption (TPD). SO2 concentrations in N2 were varied from 5 ppm to 1% (vol) and adsorption isotherms were determined at 25, 50, and 80 °C. Oxygen assisted (O-assisted) desorption experiments (i.e., successive TPD experiments following exposure to room temperature O2 after the first TPD event) produced an additional SO2 peak at a temperature higher than the initial SO2 peak. These two types of SO2 adsorption were identified as weakly adsorbed SO2 species desorbed between 140 and 200 °C, depending on concentration, and a strongly adsorbed, dissociated species. For the strongly adsorbed, dissociative species, (18)O2 isotope introduction during O-assisted desorption yielded ratios of 50%, 36%, and 14% for SO2 masses of 64, 66, and 68, respectively. The activation energy and kinetic constant of desorption are reported for weakly adsorbed SO2 at 1% and 20 ppm SO2 using the Polanyi-Wigner equation.
采用程序升温脱附（TPD）法研究了质子交换膜燃料电池（PEMFC）中常用的 Pt/C 催化剂上 SO2 的吸附。在 N2 中，SO2 浓度从 5 ppm 变化到 1%（体积），在 25、50 和 80°C 下测定了吸附等温线。氧气辅助（O-assisted）脱附实验（即在第一次 TPD 事件后，在室温 O2 暴露后进行的连续 TPD 实验）在高于初始 SO2 峰的温度下产生了额外的 SO2 峰。这两种类型的 SO2 吸附被确定为在 140 至 200°C 之间脱附的弱吸附 SO2 物种，具体取决于浓度，以及强吸附、离解的物种。对于强吸附、离解的物种，在 O 辅助脱附过程中引入（18）O2 同位素，分别得到 SO2 质量为 64、66 和 68 的 50%、36%和 14%的比值。使用 Polanyi-Wigner 方程，报道了在 1%和 20 ppm SO2 下弱吸附 SO2 的脱附活化能和动力学常数。
