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 p otentiometric titration Results from IGC experiments demonstrate that these materials have activity for hydrocarbon decomposition. TWO facto rs can influence the acidic properties: different heat treatment proto cols and the deposition of a carbonaceous residue. Different activitie s were related to different distributions of acidic sites on the surfa ce of the clays as revealed by analysis of potentiometric titration da ta. Sorption of propene followed by heat treatment at 473 K resulted i n coke deposition on the surface, blocking of small pores (decrease in the surface area and micropore volume) and changes in total acidity i n the pK(a) range 4-10, with creation of new acidic centres.