Because of these facts, we attempted to design a new POM–IL catalyst system that can combine the advantages of homogeneous catalysis
with straightforward separation, recovery and reuse of the heterogeneous catalyst. Our main focus is on the 12-tungstophosphoric acid,
H3PW12O40 (PW), as the strongest acid among the Keggin POMs. A
series of POM–ILs were synthesized using different sulfonated organic
cations and Keggin PW anion (Scheme 1).