Selective oxidation catalysis will be playing a crucial role in the ambitious goal of replacing the crude-oil based raw materials of today`s petro-chemical industry by more sustainable, ideally renewable resources. One of the key challenges is the efficient and direct functionalization of alkanes from natural gas or future regenerative carbon-based feedstocks. However, a major breakthrough in this field is still impeded by the lack of suitable catalysts and the absence of a detailed mechanistic understanding of the few efficient alkane oxidation reactions.



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The so far only industrially applied selective alkane oxidation reaction is the oxidation of n-butane (C4) to maleic anhydride (MA) on vanadyl pyrophosphate (VPP) catalysts, though the achieved MA yield of about 60% still shows potential for improvement. The direct oxidation of propane to acrylic acid (AA) on the M1 phase of the polynary transiton metal oxide MoVTeNbO_x is with optimized AA yields of 50% still awaiting its commercial breakthrough. Though the oxidative dehydrogenation (ODH) of ethane over the same catalyst exhibits ethylene yields in the range of 70%, this process is still economically unfavourable in comparison to steam-cracking, not to mention the either very low yields or very harsh conditions needed for the selective oxidation of methane to valuable products. Due to the rather high amount of charge carriers formally transferred in a catalytic redox cycle (e.g. 14 electrons from C4 to MA), it is still controversially debated if such oxidation reactions can be explained just on the basis of the single site concept with an isolated active center large enough to “store” reversibly the high charge carrier number, or if (and how) subsurface layers with appropriate charge transfer properties have to be taken into account.