Effect of Location and Distribution of Al Sites in ZSM-5 on the Formation of Cu-Oxo Clusters Active for Direct Conversion of Methane to Methanol

Understanding and Optimizing the Performance of Cu‐FER for The Direct CH4 to CH3OH Conversion

“…Normalizing the yield with respect to the Cu loading (Figure b) it is demonstrated that increasing the Cu loading indeed leads to an increase of the amount of active Cu. In the case of Cu‐MOR, and Cu‐ZSM‐5 the molCH 3 OH/molCu has been reported not to depend on the Cu loading. However, Cu–CHA exhibited a similar effect at low Cu/Al ratio as seen for Cu‐FER, which was explained by the coordination of Cu ions in the very stable Al 6r positions as bare Cu II , making the Cu species inactive for the conversion ,…”

“…Different zeolites are known to possess the active Cu site motifs capable of the conversion. Cu–MOR,–,, Cu‐ZSM‐5,, and Cu‐SSZ‐13,,, exhibit high yields with the maximum being 0.47, 0.21 and 0.172 (molCH 3 OH/molCu) for each topology respectively. Due to the stoichiometric nature of the process, the CH 3 OH output is inevitably dictated by the density and nuclearity of the active sites.…”

Copper‐Exchanged Omega (MAZ) Zeolite: Copper‐concentration Dependent Active Sites and its Unprecedented Methane to Methanol Conversion

“…Copper exchanged zeolites can do just that when a stepwise looping procedure is applied . The most widely studied copper zeolites are ZSM‐5 and mordenite, and the overall methanol yield has improved over the last 15 years as we have gained better understanding of the procedure, extraction and favorable zeolite characteristics . However, the yield is still below any industrially viable levels, and there is no consensus on the active site or mechanism responsible for the methane to methanol conversion ,,,,,,.…”

“…A series of Cu‐omega (Cu– MAZ ) samples were prepared through cation exchange with varying amounts of copper ranging from 1.5 wt.% to 4.7 wt.% The details on the sample synthesis and its characterization are given in the Supporting Information. Each sample was tested for methane to methanol conversion under the conventional stepwise procedure,,,,, (activation at 723 K in oxygen and reaction at 473 K with methane at 1 bar) as well as under a high‐pressure procedure using methane at 30 bar and at 473 K during the methane reaction step . For comparison, a commercial mordenite (Zeoflair 800, Zeochem AG, Si/Al=10) was also tested.…”

“…[9][10][11][12][13][14][15][16][17] The most widely studied copper zeolites are ZSM-5 and mordenite, and the overall methanol yield has improved over the last 15 years as we have gained better understanding of the procedure, extraction and favorable zeolite characteristics. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] However, the yield is still below any industrially viable levels, and there is no consensus on the active site or mechanism responsible for the methane to methanol conversion. [9,10,13,15,18,21,[23][24][25][26][27] This has led researchers to explore other zeolites and non-zeolite materials in an attempt to achieve higher yields of methanol or uniform active sites.…”