Stepwise conversion of methane to methanol on Cu and Fe/zeolites prepared in solid state: the effect of zeolite type and activation temperature

Abstract

BACKGROUNDGrand efforts have been recently devoted to the development of catalysts based on the excellent performance of Cu‐ and Fe‐dependent enzymes in methanotrophic bacteria for the partial oxidation of methane to methanol under ambient conditions. As a continuation of the study on the stepwise manner for this conversion over zeolite‐based catalysts, in this work, the effects of zeolite topology and activation temperature on the catalytic performance of Cu‐ and Fe‐containing zeolites were investigated.RESULTSCu species exchanged in the medium‐pore zeolites (mordenite, ZSM‐5, and ferrierite) afforded better methanol production, while large‐pore zeolites (zeolite β and zeolite γ) were inappropriate to accommodate active Cu sites. Notably, Cu/silicalite‐1 containing CuO species was also reactive to methane after the activation in O2, yielding a minor methanol amount. Furthermore, the activity of Fe/mordenite towards the methanol in the O2‐assisted procedure was reported for the first time but with a much lower yield as compared to that of Cu/mordenite. The methanol yield over Cu/mordenite increased with the activation temperature because increasing the activation temperature favored the Cu‐exchange degree with a higher priority at the side pockets as compared to the main channels of mordenite, as evidenced from infrared analysis.CONCLUSIONThe selective oxidation of methane to methanol by O2 via a stepwise manner can be obtained over both ion‐exchanged Cu species and well‐dispersed CuO nanoparticles with better activity being recorded for the former. The activity of Cu‐exchanged zeolites was considerably dependent on the zeolite topology and the charge‐balancing position of the Cu2+ cations. © 2023 Society of Chemical Industry (SCI).

Competition between Mononuclear and Binuclear Copper Sites across Different Zeolite Topologies

“…Although the methanol produced in cyclic PMO over different zeolites depends on the Al distribution, activation conditions, ,,,− and Cu-exchange protocol, ,− some zeolite topologies, ,, and specific compositions for a given topology, have generally been reported to have higher methanol per Cu yields. While we emphasize our goal here is not to determine specific active sites and activities for PMO, we next tested if observed trends in methanol yields correlate with our predicted total dimer populations.…”

Special issue: 6th International Conference of Chemical Engineering & Industrial Biotechnology 2022 (ICCEIB 2022)

“…The Ni-based catalyst exhibited commendable efficacy, yielding the target compound at 85%, and displayed the ability to be retrieved and reused with minimal degradation of catalytic activity. Le et al 9 examined the catalytic efficacy of zeolites containing Cu and Fe for the partial oxidation of methane to methanol. Zeolites with medium-sized pores (mordenite, ZSM-5, and ferrierite), when incorporated with Cu species, exhibited enhanced methanol generation, whereas zeolites with larger pores were less conducive to hosting active Cu sites.…”

“…The Ni‐based catalyst exhibited commendable efficacy, yielding the target compound at 85%, and displayed the ability to be retrieved and reused with minimal degradation of catalytic activity. Le et al 9 . examined the catalytic efficacy of zeolites containing Cu and Fe for the partial oxidation of methane to methanol.…”