Understanding catalysis in aqueous phase is important for many applications, including energy storage (e.g. aqueous flow batteries) and production of renewable fuels and chemicals (e.g. hydrogenation of molecules to valuable products). In this talk we will discuss the role of water and pH on heterogeneous catalysis kinetics and discuss our work in spectroscopic probing of catalysts in aqueous conditions. We will focus on looking at the similarities and differences in the adsorption and reaction of hydrogen and organic molecules on metal surfaces in (i) the gas-phase (ii) thermally in the aqueous phase and (iii) electrochemically in the aqueous phase.<sup>1</sup> We focus on hydrogenation of phenol and benzaldehyde as model molecules to simulate bio-oil, a water-rich waste stream from pyrolysis or hydrothermal liquefaction. By hydrogenating the bio-oil, followed by deoxygenation we enable a process to produce liquid transportation fuels from waste biomass, unlocking a renewable way to produce high-density fuels.<br/>The talk will focus on understanding the adsorption of molecules onto metal surfaces and the role water plays in modifying the adsorption energies. We will also discuss observations for increased rate of hydrogenation by controlling the pH, and possible mechanisms. To understand some of these effects, we will discuss methods of spectroscopy in aqueous solution to probe the catalyst surface on Pt and Pd in aqueous phase. Taken together, we will show how we are beginning to understand the effect that water has on these reactions and how to interpret the observed reaction rates, and what is required to further increase rates for a system to cost-effectively convert waste products to valuable fuels and chemicals.<br/>

Hydrogenation of organic compounds on platinum group metals in aqueous media

256th National Meeting (2018)

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