The critical impacts of anion and cosolvent on morpholinium ionic liquid pretreatment for efficient renewable energy production from triticale straw

Abstract

Morpholinium ionic liquids (ILs) using N-allyl-N-methylmorpholinium ([AMMorph]) cation in combination with acetate ([OAc]), formate ([OFo]), carbonate ([CO3]), and sulfate ([SO4]) anions were used for the pretreatment of triticale straw. The pretreatment was performed with various percentages of IL as well as water and dimethyl sulfoxide (DMSO) as cosolvents. These cosolvents reduced IL consumption and increased the ethanol efficiencies up to 90% and 76% after pretreatment with [AMMorph][OAc] or [AMMorph]2[CO3], respectively, and water cosolvent. Whereas the mixture of water and DMSO resulted in the maximum ethanol yields of 82% and 69% for [AMMorph][OFo] and [AMMorph]2[SO4], respectively. Among the studied IL-cosolvent combinations, the best solvent for the pretreatment of triticale straw was a mixture of [AMMorph][OAc] with 20% water to achieve highest ethanol production. The performance of this IL was further studied in terms of temperature and time, resulting in hydrolysis and ethanol yields of 99% and 94%, respectively. The results revealed that the anion plays a key role in the pretreatment efficiency and the organic anions, i.e., acetate and formate, had better performance in the presence of cosolvent compared with inorganic anions. Moreover, the amount and type of cosolvent for obtaining the highest yields are highly dependent on the anion type.