Distinguished iNANO Lecture: Direct conversion of methane to methanol – fundamentals, challenges and opportunities

Lead Scientist Pablo Beato, Atomic Scale Analysis Group, Research and Development, Haldor Topsøe A/S, DK

Direct conversion of methane to methanol – fundamentals, challenges and opportunities

The direct low-temperature conversion of methane to methanol (MTM) is currently a heavily investigated field, due to its enormous potential for the energy and chemicals sector. However, the high energy required for cleavage of the C−H bond in CH₄ combined with the facile over-oxidation to CO_x pose great challenges for the realization of such a process. This is why in industry this process is still considered a “dream reaction”.

In nature, mono-oxygenase enzymes in methanotrophic bacteria are able to transform methane to methanol at ambient temperatures. These enzymes have inspired researchers in the field of heterogeneous catalysis to mimic such a unique reactivity. Metal-exchanged zeolites are able to stabilize well-defined metal-oxo sites: different zeolite topologies have been demonstrated to stabilize copper, iron, and other metal-oxo clusters and all of them have shown activity for stoichiometric transformation of methane to methanol.

In the focus of this lecture, I will try evidence the complex nature and dynamics of Cu ions in zeolites and explore the impact of this complexity on the MTM conversion. Compositional characteristics (Cu/Al and Si/Al ratios) appear to determine an upper threshold for the productivity of the materials. An optimum combination of framework Al distribution (influenced by synthesis parameters and Si/Al ratio) together with the Cu loading can provide uniquely high activity for methane conversion. Synergizing the most favorable synthesis and compositional parameters and reaction conditions, our group recently obtained the highest methanol yield per Cu yet reported for MTM over Cu-zeolites, of 0.47 mol_MeOH/mol_Cu.

Finally, I will give a personal perspective on the possible industrial application of this reaction and discuss how far away we still are from the dream of directly converting methane to methanol at an industrial scale.

References

1. Pappas, D. K., Borfecchia, E., Dyballa, M., Pankin, I. A., Lomachenko, K.A., Martini, A., Teketel, S., Arstad, B., Berlier, G., Lamberti, C., Bordiga, S., Olsbye, U., Lillerud, K. P., Svelle, S., Beato, P. J. Am. Chem. Soc. 139, 42 (2017).
2. Pappas, D. K., Martini, A., Dyballa, M., Kvande, K., Teketel, S., Lomachenko, K.A., Baran, R., Glatzel, P., Arstad, B., Berlier, G., Lamberti, C., Bordiga, S., Olsbye, U., Svelle, S., Beato, P., and Borfecchia, E. J. Am. Chem. Soc. 140, 15270 (2018).
3. Borfecchia, E., Beato, P., Svelle, S., Olsbye, U., Lamberti, C., Bordiga, S., Chem. Soc. Rev. 47, 8059 (2018).
4. Martini, A., Borfecchia, E., Lomachenko, K.A., Pankin, I. A., Negri, C., Berlier, G., Beato, P., Falsig, H., Bordiga, S., Lamberti, C. Chem. Sci., 8, (2017).

Host: Associate Professor Jeppe Vang Lauritsen, iNANO & Dept. of Physics and Astronomy, AU

Coffe, tea, and bread will be served from 10:00 in front of the auditorium