Design and preparation of N-doped ordered mesoporous carbon with Ia3d symmetry as bifunctional enzyme-like catalyst for conversion of carbohydrates

Inspired by synergistically cooperation of two or more active sites in enzymes, we have prepared a novel bifunctional acid-base ordered mesoporous carbon denoted as Ionic liquid derived Bimodal cubic Ordered Mesoporous Carbon (IBOMC) via nanocasting protocol using KIT-6 as a hard template. High basicity, significant surface acidity, high surface area, well-defined pore size, high thermal stability and high nitrogen content are the noticeable properties of this carbon that has never been collectively observed in other carbon materials. By attention to these fascinating properties, especially the balance between the basic and acidic sites, we considered the performance of this material in preparation of 5-hydroxymethylfurfural (5-HMF) as a versatile intermediate between biomass-based carbohydrate chemistry and petroleum-based industrial organic chemistry. The efficiency of this material as an acid carbocatalyst was proven in formation of 5-HMF from fructose with 98% yield. Moreover, the one-pot conversion of complex carbohydrates such as glucose, sucrose and cellulose was performed with taking advantage of the double-acting acid-base character of this carbocatalyst. It was shown that the presence of base active site is crucial for isomerization of glucose into fructose. The catalyst could be recycled up to 5 cycles. In addition, this unique catalyst displayed the excellent performance in selective aerobic oxidation of 5-HMF into Diformylfuran (DFF) in the absence of any metal (Scheme 1). For the first time, this study has revealed the importance of morphology and balanced acid-base properties of carbon catalysts for the conversion of biomass.