COLLINS Sebastian Enrique
congresos y reuniones científicas
Design and optimization of a flow-through ATR-FTIR cell for transient and modulated operando experiments
Congreso; 4th International Congress on Operando Spectroscopy; 2012
Attenuated total reflection (ATR) infrared (IR) spectroscopy is a powerful tool for the investigation of reaction pathways in solid(catalyst)/liquid(reactive) systems, because it provides the detection of species adsorbed on a catalyst under reaction conditions. How-ever, the presence of strongly absorbent solvents, spectator species and/or the catalyst it-self can make very difficult or preclude the identification and tracking of the true active species, that is, the reaction intermediates. Then, transient experiments are widely applied in the analysis of reaction intermediates by perturbing a catalytic system working under steady state conditions (ss). More recently, modulation excitation spectroscopy (MES) with phase sensitive detection (PSD) have proved to be an adequate methodology to separate a weak response from a strong background signal [1]. MES experiments are based on the disturbance of a ss system by the periodical variation of an external parame-ter such as the temperature, the pressure, or the concentration of a reactant. Therefore, all the species in the system that are affected by this parameter will also change periodically with the same frequency of the perturbation, but with a phase lag. Thus, MES, coupled with PSD analysis, applied to in situ ATR-IR experiments can allow the sensitive and selective detection of species directly involved in a reaction at the liquid/solid interface, and the monitoring of their dynamic behaviors. In this work we present an optimized design of a flow-through ATR cell for transient and operando-modulated experiments in the solid-liquid interface. Examples of application are also shown.