Sugarcane bio-refinery products: An efficient one umbrella approach for synthesis of biofuel and value-added compounds using metal-free photo-catalyst

Abstract

The synchronized transformation of molasses, sugarcane juice, glucose, fructose, and sucrose into water insoluble platform chemicals, has stand up as a resourceful exercise to eradicate the expensive separation steps. On the other hand, the existing processes involve both acid-catalyzed and hydrogenation processes. We report herein, new green approaches for sequential conversion of sugarcane biorefinery products into biofuels using metal free carboxyl acid functionalized ionic liquid entangled porphyrin (CAFILP) photo-catalyst. Both levulinic acid (LA) and hydroxymethyl furfural (HMF) are water soluble and difficult to separate from the reaction mixture. Remarkably, the reaction of mixture containing LA and HMF easily converted to ethyl levulinate that considerably increases the yield of levulinate by affording another transformation technique excluding the hydrogenation step. The photo-catalytic activity of CAFILP affords ethyl levulinate (94%) and HMF (70%) yield that matches the acidic strength articulated by the Hammett acidity function. Photo-catalyst CAFILP exhibited intense absorptions in the visible regions with low band gap (1.49 eV) for visible light absorption is a key step of photocatalytic performance to convert sugarcane bio-refinery products into biofuels. The yield of HMF/LA was the highest from molasses, comprising more fructose that facilitates faster conversion compare to other biomass sources. Other products of sugarcane bio-refinery like sugarcane juice, sucrose, glucose, and fructose also have potential to add value in the bioenergy chain, affording HMF as the main product using optimized reaction conditions in presence of CAFILP photo-catalyst. The reusability of photocatalyst (up to 5 runs) was confirmed by easy filtration with good photo-catalytic activity.