Evaluation of Amberlyst15 for hydrolysis of alkali pretreated rice straw and fermentation to ethanol

• Use of Amberlyst 15 in hydrolysis of alkali pretreated biomass.
• Conditions for catalytic biomass hydrolysis optimized.
• Solid acid catalyst recycled and reused twice for hydrolysis.
• Inhibitors generated are less compared to acidic hydrolysis.
• Alcohol production demonstrated with catalytic hydrolysate.

Solid acid catalysts are potent alternatives to enzymes or mineral acids currently used in the hydrolysis of lignocellulosic biomass to generate sugars for further applications in biofuel or chemicals manufacturing. They are considered green, environmentally safe, and are reusable. In the present work, Amberlyst 15 was evaluated as a solid acid catalyst for the hydrolysis of alkali pretreated biomass. A response surface methodology was used to optimize the hydrolysis of pretreated rice straw. Optimized conditions of 7.0% biomass and catalyst loading resulted in a sugar yield of 255 mg/g of pretreated biomass in 4.0 h. The catalytic hydrolysate generated lesser amount of fermentation inhibitors compared to similar treatment by mineral acids. Recovery and reusability of the catalyst was also studied. The catalytic hydrolysate could be used for fermentative production of bioethanol. Results indicate the possibility to use solid acid catalysts as an alternative strategy for biomass hydrolysis.