Tracking Active Phase Behavior on Boron Nitride during the Oxidative Dehydrogenation of Propane Using Operando X-ray Raman Spectroscopy

Kinetic Insights into Boron-Based Materials Catalyzed Oxidative Dehydrogenation of Light Alkanes

“…The aforementioned shared features of boron-based catalysts, including the linear selectivity-conversion relationship, the formation of hydroxylated boron oxide species during the ODH condition, and the apparent kinetic parameters, suggest that the ODH reaction proceeds via a similar reaction mechanism. The importance of gas-phase radical reactions in ODH catalyzed by boron-based catalysts was first recognized by Hermans and co-workers. ,, They observed that the ODH rates were proportional to the volume of the catalyst bed, rather than the mass of boron nitride . (Figure a and b) A mechanism involving both surface and gas-phase reactions was proposed by Venegas et al, in which radicals were generated on boron sites and water promoted the ODH by enabling an additional pathway for radical generation .…”

“…The importance of gas-phase radical reactions in ODH catalyzed by boron-based catalysts was first recognized by Hermans and co-workers. 61,69,70 They observed that the ODH rates were proportional to the volume of the catalyst bed, rather than the mass of boron nitride. 69 (Figure 2a and b) A mechanism involving both surface and gas-phase reactions was proposed by Venegas et al, in which radicals were generated on boron sites and water promoted the ODH by enabling an additional pathway for radical generation.…”

From microkinetic model to process: understanding the role of the boron nitride surface and gas phase chemistry in the oxidative dehydrogenation of propane

“…[8][9][10][11][12][13][14][15][16][17] Further investigation revealed that boron-based catalysts undergo an induction period, forming a boron oxyhydroxide layer that likely kicks off surface-initiated, radical gas-phase propagated propane oxidation. [18][19][20][21][22][23] In particular, microkinetic modeling suggests that propane is typically activated by oxidants such as HO 2 ˙radical that leads to formation of n-propyl and i-propyl radicals, key intermediates in the formation of propylene via H-abstraction by O 2 . 21,24 The relative ratio of n-propyl vs. ipropyl radicals formed has tremendous implications for the selectivity of the process, and the ratio is determined by the nature of the H-abstracting species.…”