it can be seen that the acid-activated clay gave high conversion while the
thermal and alkaline activation only improved the conversion a little above the
uncatalysed reaction. This is an indication that the active ingredient of the catalysis is
proton (H+) from the acid. The thermally activated clay showed a better conversion than
the alkaline and the uncatalysed. This is confirmation that heating of the clay to remove
the interstitial water increases the surface area and its Bronsted acidity. The little
improved conversion shown by alkaline activation indicates that while there was a small
improvement in the catalytic property of the clay due to drying, the alkaline treatment
reduced the acidity of the natural clay.