Abstract
Levulinic acid (LA) is currently one of the most promising chemicals derived from biomass. However, its large-scale production is hampered by the challenges in biomass hydrolysis and the poor selectivity due to the formation of humins (HUs). This study addresses these challenges using the biorefinery concept of biomass fractionation. A three-step process (pretreatment, delignification, and acid-catalyzed conversion) was optimized to produce LA from SCB considering the yield (YLA), efficiency (ELA), and concentration of LA (CLA) as functions of temperature, reaction time, acid concentration, and solids loading. By means of a multi-response optimization, values of YLA (20.9 ± 1.25 g/100gISF-D), ELA (37.5 ± 2.24 mol%), and CLA (25.1 ± 1.50 g/L) were obtained at 180 °C, 75 min, 7.0% w/v H2SO4, and 12.0% w/v of solids loading. Six scenarios for production of LA were analyzed in terms of yields of LA, HUs, lignin, and other sugar-derived products considering one-, two-, or three-step processes. The economic analysis indicated that the three-step scenario delivers better economic figures given that other valuable biomass fractions (hemicellulosic sugars and lignin) are better used and contribute to the overall economic performance of the process. The results also demonstrate the burden of HUs in the economics of the process because it was shown that the largest production of LA is also linked to the largest formation of HUs, which does not necessarily yield the best economic results. These findings indicate the importance of added value by-products for the profitable production of LA in biorefineries.
Highlights
Many solutions have been developed by the academy and industry to mitigate the consequences of the climate crisis, including the development of more sustainable processes [1]
When biomass hydrolysis is carried out in an environment with severe oxidation strength, cellulose is hydrolyzed to glucose, whose dehydration yields in 5-hydroxymethylfurfural (5-HMF), which in turn can be decomposed in Levulinic acid (LA) and formic acid (FA)
The first large-scale endeavor on the production of LA was based on the Biofine process, which consists of two reactors, each focused on different biomass fractions [9]
Summary
Many solutions have been developed by the academy and industry to mitigate the consequences of the climate crisis, including the development of more sustainable processes [1]. One of these chemicals is levulinic acid (LA, CH3(CO)CH2CH2COOH), a γ-keto acid obtained via hydrolysis sugars with applications in the chemical, food, agriculture, and fuel industry [6, 7]. Fractionation of biomass for the production of LA is being investigated to create a better understanding of the advantages of this approach: Pradipta et al [10] attained a yield of 43% from Indonesian SCB, Ji et al [11] obtained a yield of 58% from poplar wood, Jeong et al [12] obtained 16.5% from Mongolian oak, and Liang et al [13] obtained 39% after 7 fed-batch steps. Little attention is given to the lignin fraction of biomass, which is usually discarded with the humins (HUs) produced during the hydrolysis process
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