EFFECT OF HETEROATOM ON PROPERTIES OF SIO2-SUPPORTED HETEROPOLYMOLYBDATES

SiO2-supported trihydrogen phosphododecamolybdate acid H3PMo12O40 (den oted as H3PMo) and tetrahydrogen silicododecamolybdate acid H4SiMo12O4 0 (denoted as H4SiMo) and their lithium salts have been studied using IR spectroscopy, temperature programmed reduction and measurement of t he thiophene conversion. Lacunar anions of H3PMo and, under some condi tions, of H4SiMo are formed if lithium is present in the catalyst. Unl ike the supported hetero polyacids, lithium combined with the analogue s of defect Keggin anions formed during calcination enhances hydrodesu lfurization of thiophene.