کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5369501 | 1388438 | 2008 | 10 صفحه PDF | دانلود رایگان |

The catalytic reduction of NO in the presence of benzene on the surface of Pt(3Â 3Â 2) has been studied using Fourier transform infra red reflection-absorption spectroscopy (FTIR-RAS) and thermal desorption spectroscopy (TDS). IR spectra show that while the presence of benzene molecules at low coverage (e.g., following an exposure of just 0.25Â L) promotes NO-Pt interaction, the adsorption of NO on Pt(3Â 3Â 2) at higher benzene coverages is suppressed. It is also shown that there are no strong interactions between the adsorbed NO molecules and the benzene itself or benzene-derived hydrocarbons, which can lead to the formation of intermediate species that are essential for N2 production.TDS results show that the adsorbed benzene molecules undergo dehydrogenation accompanied by hydrogen desorption starting at 300Â K and achieving a maximum at 394Â K. Subsequent dehydrogenation of the benzene-derived hydrocarbons then begins with hydrogen desorption starting at 500Â K. N2 desorption from NO adlayers on clean Pt(3Â 3Â 2) surface becomes significant at temperatures higher than 400Â K, giving rise to a peak at 465Â K. This peak corresponds to N2 desorption from NO dissociation on step sites. The presence of benzene promotes N2 desorption, depending on the benzene coverage. When the benzene exposure is 0.25Â L, the N2 desorption peak at 459Â K is dramatically increased. Increasing benzene coverage also results in the intensification of N2 desorption at â¼410Â K. At benzene exposures of 2.4Â L, N2 desorption develops as a broad peak with a maximum at â¼439Â K.It is concluded that the catalytic reduction of NO by platinum in the presence of benzene proceeds by NO decomposition and subsequent oxygen removal at temperatures lower than 500Â K, and NO dissociation is a rate-limiting step. The contribution of benzene to N2 desorption is mainly attributed to providing a source of H, which quickly reacts with NO-derived atomic O, leaving the surface with more vacant sites for further NO dissociation.
Journal: Applied Surface Science - Volume 254, Issue 6, 15 January 2008, Pages 1666-1675