Changes in the acidic properties of pillared taeniolites on heat treatment or alkene decomposition
The acidic properties of a series of Al-pillared taeniolite have been studied by inverse gas chromatography (IGC), sorption experiments and potentiometric titration. Results from IGC experiments demonstrate that these materials have activity for hydrocarbon decomposition. Two factors can influence the acidic properties: different heat treatment protocols and the deposition of a carbonaceous residue. Different activities were related to different distributions of acidic sites on the surface of the clays as revealed by analysis of potentiometric titration data. Sorption of propene followed by heat treatment at 473 K resulted in coke deposition on the surface, blocking of small pores (decrease in the surface area and micropore volume) and changes in total acidity in the pKa range 4–10, with creation of new acidic centres.