Oxidative dehydrogenation of propane
to propylene can be achieved
using conventional, oxygen-assisted dehydrogenation of propane (O2–ODHP) or via the use of soft oxidants, such as CO2, N2O, S-containing compounds, and halogens/halides.
The major roles of soft oxidants include inhibiting overoxidation
and improving propylene selectivity, which are considered to be current
challenges in O2-assisted dehydrogenation. For both CO2– and N2O–ODHP reactions, significant
efforts have been devoted to developing redox-active (e.g., chromium,
vanadate, iron, etc.), nonredox-type main group metal oxide (e.g.,
group IIIA, gallium), and other transition metal/metal oxide catalysts
(e.g., molybdenum, palladium platinum, rhodium, ruthenium, etc.),
as well as zeolite-based catalysts with adjustable acid–base
properties, unique pore structures, and topologies. Metal sulfides
have shown promising performance in DHP, whereas the development of
suitable catalysts has lagged for SO2- or S-assisted ODHP.
Recently, significant efforts have been focused on homogeneous and
heterogeneous ODHP using halogens (e.g., Br2, I2, Cl2, etc.) and hydrogen halides (e.g., HCl and HBr)
for the development of facile processes for C3H6 synthesis. This Review aims to provide a critical, comprehensive
review of recent advances in oxidative dehydrogenation of propane
with these soft oxidants, particularly highlighting the current state
of understanding of the following factors: (i) relationships between
composition, structure, and catalytic performance, (ii) effects of
the support, acidity, and promoters, (iii) reaction pathway and mechanistic
insights, and (iv) the various roles of soft oxidants. Theoretical
and computational insights toward understanding reaction mechanisms
and catalyst design principles are also covered. Future research opportunities
are discussed in terms of catalyst design and synthesis, deactivation
and regeneration, reaction mechanisms, and alternative approaches.
