ATR-IR spectroscopic cell for in situ studies at solid-liquid interface at elevated temperatures and pressures

•An in situ ATR-IR cell for studies in hot compressed water was designed and tested.•Mechanically stable catalyst layers are obtained by spray coating method.•Hydrodynamics in the cell were characterized by both experiments and simulation.•Cell can perform ATR-IR spectroscopy for aqueous phase reforming of hydroxyacetone.

An in situ ATR-IR spectroscopic cell suitable for studies at solid-liquid interface is described including the design and experimental details in continuous flow mode at elevated temperatures (230 °C) and pressures (30 bar). The design parameters considered include the cell geometry, the procedure to immobilize the catalyst on a cylindrical internal reflection element (IRE), as well as shape and material of choice for the IRE, optics configuration and temperature/pressure control. The hydrodynamics and concentration profiles in the cell were assessed via numerical simulations using incompressible Navier-Stokes equation and convection-diffusion model showing significant deviation from ideal plug flow. Experimental response times at ambient and elevated temperatures derived from ATR-IR spectra agree well with the simulations, demonstrating that the hydrodynamics of the reactor is accurately described. Homogeneous Pt/ZrO2 and AlO(OH) layers were obtained by spray-coating which are stable for at least 12 h during testing in 2 mL/min water flow. Preliminary spectra collected during aqueous phase reforming of hydroxyacetone demonstrated that the cell can be operated at 230 °C and 30 bar with simultaneous detection of IR-active species both in the liquid as well as adsorbed on the surface of the catalyst.

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