Probing the Catalytic Efficiency of Supported Heteropoly Acids for Esterification: Effect of Weak Catalyst Support Interactions

Figure 2

FT-IR spectra of (a) 25% HPW/SiO₂ (HPW-S), (b) 25% HPW/kaolinite (HPW-K), (c) 25% HPW/bentonite (HPW-B), and (d) 25% HPW/montmorillonite (HPW-M).

(a)

(b)

(c)

(d)