One-Pot Synthesized Fe-AEI Zeolite Catalysts Contribute to Direct Oxidation of Methane
Peipei Xiao, K. Nakamura, Yao Lu, Jun Huang, Lizhuo Wang, Ryota Osuga, Maiko Nishibori, Yong Wang, Hermann Gies, Toshiyuki Yokoi
Abstract
High Resolution Image Download MS PowerPoint Slide CH 4 and N 2 O are the two largest greenhouse gases after CO 2 . Conversion of CH 4 with N 2 O to value-added and clean chemicals contributes to endurable development. Fe-containing zeolite catalysts, especially small-pore zeolites, are widely used and highly active in both methane conversion and N 2 O decomposition. The combination of direct conversion of CH 4 with N 2 O to value-added chemicals on Fe-containing zeolite catalysts can effectively alleviate the environmental and energy problems of growing greenhouse gas emissions and the increasing demand for chemicals. Herein, we have successfully developed a method for directly and facilely crystallizing the Fe-containing aluminosilicate AEI-type zeolites (Fe-AEI) with varied Si/Fe ratios by the inter zeolite conversion method from FER zeolite. The Fe states have been carefully characterized by UV–vis, X-ray absorption spectroscopy, NO adsorption Fourier transform infrared (FTIR) spectroscopy, CO adsorption FTIR, and HADDF-STEM to demonstrate their highly dispersed properties. Thus, obtained one-pot synthesized Fe-AEI zeolites were applied to directly oxidize methane with N 2 O. The reaction conditions including the Si/Fe ratio, reaction temperature, ratio of CH 4 /N 2 O in feed, and H 2 O flow rate in feed were inspected. The catalytic activity of one-pot synthesized Fe-AEI zeolites was compared with the Fe-exchanged AEI (Fe/AEI) zeolites; the Fe-AEI zeolites exhibited much better activity due to the highly dispersed Fe species in Fe-AEI zeolites. Finally, a conceivable reaction pathway was provided based on the reaction results and FTIR spectra.