Niobium oxide catalyst for delignification of switchgrass for fermentable sugar production

In this research, niobium oxide, a solid acid catalyst was evaluated as a pretreatment agent for delignification of Alamo switchgrass. The objectives were to determine the effects of temperature, catalyst loading, and pretreatment time on delignification and enzymatic hydrolysis of switchgrass and evaluate reusability of the catalyst. Batch experiments were performed using a Box-Behnken statistical model to study the effects of temperature, pretreatment time, and catalyst loading followed by hydrolysis using Cellic (R) Ctec2 (Novozymes). Niobium oxide was able to reduce total lignin concentrations up to 44.6 +/- 0.97%. Hydrolysis experiments performed for 72 and 168 h (7% enzyme loading) indicated that a maximum glucose yield of 0.169 g g(-1) (59.94% conversion)-0.196 g g(-1) (77.51% conversion) was obtained. Catalyst reusability studies suggested that niobium oxide was able to pretreat four separate batches of switchgrass without losing activity. Niobium oxide is expected to serve as a reusable pretreatment catalyst and make ethanol production inexpensive and environmentally friendly. (C) 2013 Elsevier B.V. All rights reserved.