Comparison of Direct, Selective Oxidation of Methane by N 2 O over Fe-ZSM-5, Fe-Beta, and Fe-FER Catalysts

作者：Guangyu Zhao, Emad Benhelal, Adesoji A. Adesina, Eric M. Kennedy, Michael Stockenhuber · 发表于：The Journal of Physical Chemistry C · 年份：2019 · DOI：10.1021/acs.jpcc.9b04388 · 被引用次数：47 · 研究领域：Catalytic Processes in Materials Science、Catalysis and Oxidation Reactions、Zeolite Catalysis and Synthesis

In this study, the activity and selectivity to Fe-ZSM-5, Fe-Beta, and Fe-FER catalysts were studied at 350 °C for the partial oxidation of methane using N 2 O as oxidant. Spectroscopic and solid characterization tools including H 2 -TPR, in situ IR, N 2 gas adsorption, CO chemisorption, and TGA-MS were used in the investigation. Ammonia adsorption data suggested that among the studied zeolites, H-FER zeolite contained the highest concentration of framework Al atoms, which are essential for the formation of active extra-framework Fe species. The oxidation state and redox active species of Fe-ZSM-5, Fe-Beta, and Fe-FER catalysts were studied by H 2 -TPR, which disclosed the presence of a unique reduction peak (originating from N 2 O pretreatment) centered at approximately 235 °C over the samples. The hydrogen consumption peak was more prominent over Fe-FER than other catalysts, demonstrating that the Fe-FER catalyst contained more active sites for N 2 O conversion in comparison to Fe-Beta and Fe-ZSM-5 catalysts. For IR spectra of NO adsorbed on the Fe zeolites, a band at 1874 cm –1 with a shoulder at 1894 cm –1 was observed over the three catalysts, suggesting the presence of extra-framework Fe clusters in ion exchange positions. We demonstrated these clusters are acting as active sites for the oxidation of methane with N 2 O. Bands of methoxy groups were observed in FTIR profiles of CH 4 and N 2 O adsorbed on Fe-FER, Fe-ZSM-5, and Fe-Beta catalysts at 350 °C. Over Fe-FER, the ...