Bifunctional and recyclable Dawson-type polyoxometalates catalyze oxidative degradation of lignocellulose to selectively produce phthalates

Abstract

Acid-redox bifunctional Dawson-type polyoxometalates K₆P₂W₁₈O₆₂ (P₂W₁₈) and K₁₀P₂W₁₇O₆₁ (P₂W₁₇) were introduced as the new-type catalysts in oxidative decomposition of lignocellulose. The lignin and hemicellulose ingredients of lignocellulose could be decomposed by P₂W₁₇ to produce diisobutyl phthalate with the selectivity of 75.67% and other aromatic and aliphatic compounds under mild conditions, evidently differed from other POMs-catalyzed lignocellulose depolymerization in which aromatic ketones and phenols were the main compounds. Diisobutyl phthalate was obtained from the oxidation of C_α-OR and α-OH of the phenyl structure. The catalyst could be recycled for three times without obvious deactivation. This is the first report of lignocellulose decomposition catalyzed by Dawson-type polyoxometalates to selectively produce phthalates.

Keywords: Catalysis; Lignocellulose; Oxidative decomposition; Polyoxometalates; Recycle.