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 (Y_LA), efficiency (E_LA), and concentration of LA (C_LA) as functions of temperature, reaction time, acid concentration, and solids loading. By means of a multi-response optimization, values of Y_LA (20.9 ± 1.25 g/100g_ISF-D), E_LA (37.5 ± 2.24 mol%), and C_LA (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.

中文翻译：

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甘蔗渣生物精炼概念对白蛋白和腐殖质价值的挑战

乙酰丙酸（LA）是目前最有前途的源自生物质的化学物质之一。然而，其大规模生产受到生物质水解的挑战和由于腐殖质（HUs）形成的选择性差的困扰。这项研究使用生物精炼的生物质分离概念解决了这些挑战。考虑到收率（Y _LA），效率（E _LA）和LA浓度（C _LA）与温度的关系，优化了三步工艺（预处理，去木质素和酸催化转化）以从SCB制备LA ，反应时间，酸浓度和固体含量。通过多响应优化，Y _LA的值（20.9±1.25 g / 100g _ISF-D），E _LA（37.5±2.24 mol％）和C _LA（25.1±1.50 g / L）在180°C，75分钟，7.0％w / v H _2下获得SO ₄，以及固体含量的12.0％w / v。根据LA，HU，木质素和其他糖衍生产品的产量，分析了LA生产的六种情况，并考虑了一步，两步或三步过程。经济分析表明，考虑到其他有价值的生物质部分（半纤维素糖和木质素）得到更好的利用，并有助于该过程的整体经济绩效，三步走的情景可提供更好的经济数据。该结果还证明了HUs在流程经济学中的负担，因为表明LA的最大产量也与HUs的最大形成有关，这不一定能产生最佳的经济结果。这些发现表明，增值副产品对于生物精炼厂LA的盈利生产至关重要。