How to scrutinize adsorbed intermediates observed by in situ spectroscopy: Analysis of Coverage Transients (ACT)

The understanding of catalytic mechanisms is enhanced by the observation surface intermediates at reaction conditions using spectroscopic techniques, but this insufficient, as observed species may not be involved in reaction. This work describes a general method analysis hydrogenation or oxidation reactions which uses transient data to determine whether an adsorbed reactive intermediate spectator on surface. assumptions and limitations are summarized. Although technique approximate, it easy implement, provides order-of-magnitude estimates rate intermediate. consists measuring change coverage with time, d?/dt, during adsorption inert gas conditions. An example given hydrodeoxygenation model compound ?-valerolactone (GVL) Ni2P/MCM-41 catalyst, one most effective catalysts reported for transformation. relevant upgrading bio-oil derived from pyrolysis lignocellulosic feedstocks. kinetics situ infrared spectroscopy GVL its transformation pentanoic acid consistent Langmuir-Hinshelwood mechanism. Analysis X-ray absorption fine structure shows that true