the surface area and the pore volume in the clay structure also
add to the efficiency of the catalyst. Total acidity can be further
increased by 'proton-exchange' on treating the clay with dilute
acid or driving out NH3 by heating the NH4 + ion treated clay. It
is clear from this description that strong corrosive acid medium
is completely avoided, if we use clay as Bronsted acid instead of
mineral acids to achieve the same purpose.