Ionic ammonium and anilinium based polymolybdate hybrid catalysts for olefin epoxidation

Ionic polymolybdate hybrids (IPH) are interesting catalysts for liquid phase olefin epoxidation with tert-butylhydroperoxide; (tbhp), e.g. conversion of terpenic and fatty acid methyl ester (FAME) components of biomass to useful bio-products. IPHs may be easily prepared, under clean, mild, aqueous phase conditions. The type of organic precursor and the synthesis conditions influence the structural features of the IPHs. In this work, IPH epoxidation catalysts possessing one- (1-D) or two-dimensional (2-D) structures were investigated, which included the new materials 1-D methylanunoniurn ammonium trimolybdate [Mo3O10 center dot CH3NH3 center dot NH4] (1) and 2-D bis(2,5-dimethylanilinium) pentamolybdate [Mo5O16 center dot 2(NH3C6H3(CH3)(2))] (4) with solved structures, and 1-D bis (3,5-dimethylanilinium) trimolybdate [Mo3O10 center dot 2(NH3C6H3(CH3)(2))] (2), bis(4-methylanilinium) trimolybdate [Mo3O10 center dot 2(NH3C6H4CH3)] (3), 2-D bis(anilinium) pentamolybdate [Mo5O16 center dot 2(NH3C6H5)] (5), bis(4-methylanilinium) pentamolybdate [Mo5O16 center dot 2(NH3C6H4CH3)] (6) and bis(4-ethylanilinium) pentamolybdate [Mo5O16 center dot 2(NH3C6H4C2H5)] (7). Systematic characterisation and catalytic studies helped gain insights into structure-activity relationships. The best-performing catalyst (2) was effective for the epoxidation of the FAMEs such as, methyl oleate which gave 92% methyl 9,10-epoxyoctadecanoate yield, at 99% conversion, at 70 degrees C. The reaction conditions (temperature, type of cosolvent and oxidant) influenced the catalytic reaction. Catalytic performance in consecutive batch runs was steady, and the structural features were essentially preserved.