On the accessibility of acid sites in ferrierite for pyridine

A discussion covers the results of different studies on the accessibility of acid sites in FER (of commercial interest for catalyzing the skeletal isomerization of alkenes) for pyridine; the suitability of pyridine as a probe molecule for quantitative analysis of FER acidity; the adsorption of pyridine mainly on the external SiOH groups of H-FER that leaves the bridging OH groups unaffected, an indication that pyridine cannot enter the FER pores; and the accessibility of all Broensted acid sites of FER for pyridine.