Heteropolyanion-based ionic liquids catalysed conversion of cellulose into formic acid without any additives

Abstract

Heteropolyanion-based ionic liquids with –SO₃H functionalized cations and PMo₁₁VO₄₀⁴⁻ anions were synthesized and applied in the conversion of cellulose into formic acid (FA). It was demonstrated that the as-prepared ILs showed enhanced activity for catalysing cellulose conversion to FA in the presence of oxygen in water compared to H₄PMo₁₁VO₄₀. A high FA yield over 50% accompanied by a FA concentration of ∼10% in reaction solution was obtained at 180 °C and in an oxygen pressure of 1.0 MPa. The possible pathway of FA production from cellulose was investigated. It was indicated that the resulting ILs served as bifunctional catalysts with cations catalysing the cellulose hydrolysis to glucose and anions catalysing glucose oxidation to FA. These ILs may find more applications in cellulose conversion.