Alma Olivos

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Van der Maasweg 9, 2629 HZ Delft 


Tel: *31 (0)15 2788321

A.I.OlivosSuarez@tudelft.nl




Towards Mild Methane Oxidation

Methane, as major component of natural gas, is highly abundant and therefore its usage is an attractive alternative to solve the current energy demands. However, natural occurrence in remote regions, the high cost of transportation and safety issues associated with its low boiling point and flammability make natural gas widely underutilized as feedstock. Thus, scientific interest focuses on the oxidation of methane to liquid fuels and chemical feedstocks such as methanol.[i]

The selective conversion of methane to methanol is intrinsically challenging as a result of the high homolytic C-H bond strength of methane relative to that of methanol. Currently, industrial production of methanol is achieved via the intermediate manufacture of synthesis gas (a mixture of CO and H2) from methane, followed by the synthesis of methanol over a Cu/ZnO/Al2O3 catalyst. This process operates at high temperatures and very high pressures and utilizes multiple steps that lead to capital intensive processes only economically attractive at very large scales. A direct conversion of methane to methanol at low temperature and with high selectivity could lead to revolutionary petrochemical technology, enabling the natural gas reserves to be revalorized as primary feedstock for fuels and chemicals.[ii]

Promising alkene oxidizing systems have been already developed and breakthroughs on C-H bond activation at metal centres have been achieved.[iii] However, no direct process for the industrial production of methanol without syngas production has been developed and, moreover, none of these systems is yet economically competitive.

In nature, the soluble and the particulate methane monooxygenases (MMO’s) can achieve the controlled oxidation of alkenes under mild conditions. The main differences in between these two types of enzymes reside in the active centres. While the sMMO has a diiron active centre,[iv] pMMO uses a combination of bimetallic Cu centres.[v]

The aim of this project is to bring the advantages of two worlds, homogeneous and heterogeneous catalysis, to develop a catalyst able to activate one of the most challenging chemical bonds, C-H in methane. We are currently exploring the implementation of metallic (i.e. Fe, Cu, Co) active centres in MOFs and COFs as a more stable alternative to efficient homogeneous catalytic systems. The main objective is to develop a robust catalyst able to operate under mild reaction conditions. 

Acknowledgements

This research receives funding from the Dutch National Science Foundation (NWO-CW) / VIDI Grant Agreement n. 723.012.107, MetMOFCat

References

[i] Arakawa, H., Aresta, M., Armor, J. N., Barteau, M. A., Beckman, E. J., Bell, A. T., et al. (2001). Catalysis Research of Relevance to Carbon Management:  Progress, Challenges, and Opportunities. Chem. Rev., 101(4), 953–996.

[ii] Hammond, C., Conrad, S., & Hermans, I. (2012). Oxidative Methane Upgrading. ChemSusChem, 5(9), 1668–1686.

[iii] Periana, R. A., Bhalla, G., Tenn, W. J., III, Young, K. J. H., Liu, X. Y., Mironov, O., et al. (2004). Perspectives on some challenges and approaches for developing the next generation of selective, low temperature, oxidation catalysts for alkane hydroxylation based on the CH activation reaction. Journal of Molecular Catalysis a-Chemical, 220(1), 7–25.

[iv] Kopp, D. A., & Lippard, S. J. (2002). Soluble methane monooxygenase: activation of dioxygen and methane. Current Opinion in Chemical Biology.

[v] Balasubramanian, R., & Rosenzweig, A. C. (2007). Structural and Mechanistic Insights into Methane Oxidation by Particulate Methane Monooxygenase. Accounts of Chemical Research, 40, 573-580.