Ammonium carbonate as a catalyst for lignocellulose pretreatment and a nitrogen source for fermentation

• NH3 based CO2 capture process can provide a catalyst for lignocellulosic biofuels.
• RSM was applied to optimize (NH4)2CO3 pretreatment conditions for glucose yield.
• Under the optimum conditions, 60% enzymatic digestibility was achieved.
• Ammonium from pretreatment step was useful in SSF of pretreated corn stover.

In this work, ammonium carbonate (AC), a product released during the regeneration of ammonia-based carbon capture process, was evaluated as an alkaline catalyst for the pretreatment of lignocellulose; and as a nitrogen source in the subsequent fermentation process for bioethanol production. Response surface methodology was employed to attain an optimum pretreatment condition in terms of AC concentration (15–25%), reaction time (5–15 h) and temperature (60–100 °C). The highest enzymatic digestibility of 59.9% was achieved with AC concentration of 20.0% at 79.5 °C of treatment temperature for 9.46 h of reaction time. A fermentation medium containing ammonium ion derived from the liquid hydrolysate after the AC-based pretreatment was found to enhance the final concentration of ethanol produced by Saccharomyces cerevisiae from 9.13 g/L to 13.30 g/L. These results indicate that AC can indeed serve as a catalyst option for pretreating lignocellulosic biomass and has an added advantage of being used as a nitrogen source for the fermentation process.