Fig. 4 shows the amounts of VOCs adsorbed on various zeolites,
which were obtained from breakthrough curves in Fig. 3. As a
whole, HY901 and MS13X gave the most adsorption capacity for
all VOCs. In Table 1, the BET surface area of HY901 and MS13X
was similar to that of HY5.6 and HY 4.8, but their adsorption capacities
for VOCs was far better. In other words, adsorption capacity
for VOCs of the used zeolites did not appear to depend on their
BET surface area. HY901 and MS13X consist of higher and lower
Si/Al ratio, respectively. Nevertheless, adsorption capacities of
HY901 and MS13X were superior to that of mordenites for all VOCs
in this work. It was also revealed that Si/Al ratio had no relevant
influence on the adsorption properties. HY901 and MS13X had a
similar number of acid sites, but they had relatively fewer of acid
sites than the other zeolites studied. From this point of view, acidity
of the zeolites seems to be not a main factor in adsorption
capacity.