Physico-chemical properties of all the three samples
are given in Table 1. Indications of structural changes
are evidenced from the surface area and porosity, where
the surface area of parent mordenite HM is relatively
low (283 m2/g), and is increased to 329 m2/g and
347 m2/g, after acid leaching (samples ATHM-1 and
ATHM-3, respectively). No significant changes in the
total pore volume after acid treatment but a trend in
micropore volume is observed. The micropore volume
(0–20 A ˚ ) is increased from 0.1063 cm3/g of the parent
mordenite to 0.12489 cm3/g of HM-1 and 0.14350 cm3/
g of HM-3, acid leached mordenite samples. This clearly
indicates that the increase in surface area is mainly due
to the micropore formation (0–20 A ˚ ), which is in agreement
with the literature findings [12].
The H–K cumulative pore volume curves of the
mordenite samples are given in Fig. 1, where the increase
in nitrogen adsorption uptake of the samples from HM
to ATHM-3 can be observed. This also suggests the
increase in micropore volume of mordenite after acid
treatment i.e., from HM to ATHM-3. The total gas
adsorbed by filling of micropores (0–20 A ˚ ) present in
parent (HM), and two acid leached samples (ATHM-1
and ATHM-3) can be measured from Fig. 1 as
0.10 cm3/g, 0.13 cm3/g and 0.15 cm3/g, respectively