Direct activation of CH4 to oxygenates and unsaturated light hydrocarbons was investigated using Fe-modified ZSM-5 and Ferrierite (FER) for a partial oxidation of CH4 with N2O oxidant. The amount of active α-oxygen sites and number of Bronsted acid sites on the Fe-modified zeolites were well correlated with CH4 conversion rate and product distributions. The amount of α-oxygen sites was largely changed according to preparation method such as wet impregnation or ion-exchange of iron precursor and types of zeolites. A large number of Bronsted acid sites and α-oxygen sites on the Fe-modified FER revealed a higher oxygenate formation such as methanol and dimethyl ether (DME) with COx, and a larger number of strong acid sites on Fe-modified ZSM-5 was also responsible for a higher selectivity to light hydrocarbons by a successive dehydration of oxygenates formed. The different catalytic performances were verified through proper measurements of the amount and type of acidic sites as well as the α-oxygen sites measured by N2O pulse chemisorption. The Fe-modified FER prepared by impregnation method possessed a larger amount of α-oxygen sites due to abundant Bronsted acid sites, which was responsible for a higher rate of CH4 conversion to oxygenates with the help of N2O decomposition on the α-oxygen sites originated from iron oxide nanoparticles.
Bibliographical noteFunding Information:
This work was also financially supported by an institutional program grant (2E26570-16-037) from the Korean Institute of Science and Technology (KIST) and by Fundamental Research Program of the Korea Institute of Materials Science (PNK4310). The authors would like to acknowledge the financial support from the National Research Foundation of Korea (NRF) grant funded by the Korea government (NRF-2014R1A1A2A16055557 and NRF-2016M3D3A1A01913253). This work was supported by the National Research Council of Science and Technology (NST) through Degree and Research Center (DRC) Program (2015). This work was financially supported by the R&D Center for Valuable Recycling (Global-Top R&D Program) of the Ministry of Environment of Korea (Project No. RE201606017).
© 2016 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Process Chemistry and Technology
- Physical and Theoretical Chemistry