Abstract
Hydrogen peroxide is currently made in large scale via the auto-oxidation (AO) process, an indirect process via the hydrogenation of anthraquinone over a Pd catalyst, followed by reaction with O2. The AO process has a significant climate footprint since H2 is usually sourced from methane steam reforming. A more sustainable H2O2 production process is therefore highly relevant. Potential alternative routes include the direct reaction of H2 and O2 and processes that use electricity, either directly via electrochemical or bio-electrochemical systems or indirectly via plasmas. Despite research on these routes, there are currently no real challengers to the established AO process. An overview of these alternative processes is provided before considering the energetic, techno-economic, life cycle and safety challenges facing them. By highlighting these challenges through comparison with the AO process, this review aims to inspire further work for upscaling these alternative processes for truly determining their industrial viability. As these processes may ultimately prove more advantageous than the AO process for on-demand production, their industrialization might not need to occur at the same production scale as that of the AO process.